The effects of temperature and oxygen content on the PCDD_PCDFs formation in MSW fly ash
实验报告英文
实验报告英文Experimental Report。
Introduction。
The purpose of this experiment was to investigate the effects of different temperatures on the rate of enzyme activity. Enzymes are biological catalysts that speed up chemical reactions in living organisms. They are sensitive to changes in temperature, and extreme temperatures can denature them, leading to a loss of function. Understanding the relationship between temperature and enzyme activity is important in various fields, including medicine, agriculture, and biotechnology.Materials and Methods。
The enzyme used in this experiment was catalase, which is found in the cells of most living organisms and helps break down hydrogen peroxide into water and oxygen. Three test tubes were prepared, each containing a small amount of catalase solution. The first test tube was placed in an ice bath, the second at room temperature, and the third in a water bath at 40°C. A small amount of hydrogen peroxide was added to each test tube, and the rate of oxygen production was measured using a gas pressure sensor connected to a computer.Results。
全球变暖的影响英语
全球变暖的影响英语English:Global warming has a range of impacts on the environment, ecosystems, and human society. Rising temperatures contribute to the melting of polar ice caps and glaciers, leading to rising sea levels and the loss of critical habitats for various species. This can result in the displacement of certain wildlife and an increase in the frequency and severity of natural disasters such as hurricanes, floods, and wildfires. Additionally, changes in temperature and precipitation patterns can have a significant impact on agricultural productivity, leading to food shortages and potential conflicts over resources. The increase in greenhouse gas emissions also contributes to air and water pollution, leading to health problems for humans and other species. Overall, global warming presents a significant threat to the well-being of the planet and its inhabitants.中文翻译：全球变暖对环境、生态系统和人类社会有着各种影响。
Effect of pyrolysis temperature and
holding time on biochar propertiesBiochar is becoming an increasingly popular alternative to traditional methods for managing soil organic matter, improving soil fertility, and sequestering carbon by converting agricultural wastes into a stable and recalcitrant form of carbon. Pyrolysis, the thermal decomposition of organic matter in the absence of oxygen, is widely used to produce biochar. The pyrolysis temperature and holding time are two critical factors that influence the properties of biochar. This article aims to explore the effect of pyrolysis temperature and holding time on biochar properties and their implications for soil management.Pyrolysis temperaturePyrolysis temperature is a important factor that influences the physicochemical properties of biochar. It determines the degree of thermal degradation of the material, leading to the production of different biochar properties. The effect of pyrolysis temperature on biochar properties can be divided into three categories: chemical composition, physical characteristics, and adsorption properties.Chemical compositionPyrolysis temperature has a significant effect on the chemical composition of biochar, including carbon content, ash content, pH, and functional groups. Higher pyrolysis temperatures generally result in higher carbon content, lower ash content, and higher pH. As the temperature increases, volatile components are driven off, leaving behind a more stable and recalcitrant carbon structure. At the same time, the increase in temperature may cause some functional groups, such as carboxyl and hydroxyl groups, to be decomposed, leading to a decrease in surface functional groups and a corresponding increase in hydrophobicity of the biochar.Physical characteristicsPyrolysis temperature also affects the physical characteristics of biochar, including surface area, pore size distribution, and bulk density. High-temperature pyrolysis leads to the formation of a more open pore structure and a higher surface area. However, pore size distribution is affected by both pyrolysis temperature and the type of feedstock, with higher temperatures resulting in a shift towards smaller pore sizes. Meanwhile, an increase in pyrolysis temperature may cause a decrease in bulk density and an increase in particle size.Adsorption propertiesPyrolysis temperature affects the adsorption properties of biochar, including its ability to adsorb nutrients, heavy metals, and other pollutants. High-temperature pyrolysis generally results in biochar with a higher adsorption capacity due to its higher surface area and pore volume. At the same time, the decrease in functional groups may lead to a reduction in the biochar’s ability to adsorb certain types ofpollutants. The specific effect of pyrolysis temperature on the adsorption properties of biochar is determined by the type and concentration of the adsorbate, as well as the properties of the biochar itself.Holding timeHolding time is another important parameter in pyrolysis that affects the properties of biochar. The holding time is the duration of the pyrolysis process at a given temperature. It is an important factor that determines the final carbonization degree and the degree of thermal degradability of the feedstock. The effects of holding time on biochar properties include chemical composition, surface area, and adsorption properties.Chemical compositionIncreasing the holding time can promote the decomposition of organic matter and improve the carbonization degree of the biochar. However, excessive holding time can lead to excessive thermal degradation and a reduction in the carbon content of the final biochar. The chemical composition of biochar can be affected by the holding time either directly or indirectly. Longer holding times can result in greater efforts to remove moisture and volatile organic matter components from the feedstock, leading to higher carbon yield and lower ash content.Surface areaHolding time can also affect the specific surface area of biochar. As the holding time increases, the surface area of the biochar may increase due to an increase in the extent of decomposition and subsequent micropore formation. However, too long a holding time can also lead to a reduction in specific surface area due to excessive carbonization and vaporization of the volatile components.Adsorption propertiesHolding time can also affect the adsorption performance of biochar. An increase in holding time can result in a higher surface area and micropore volume, leading to a greater adsorption capacity for certain types of pollutants such as heavy metals. However, excessive holding times can reduce the number of surface functional groups responsible for adsorption, merely increasing the micropore density in the biochar, and reducing the potential for adsorption of some other pollutants.ConclusionIn conclusion, pyrolysis temperature and holding time are two crucial factors that influence the properties of biochar, which in turn determine its effectiveness in soil applications. High-temperature pyrolysis tends to result in biochar with higher carbon content, larger surface area, and higher adsorption capacity than low-temperature pyrolysis. Longer holding times can also modify biochar properties,although the extent depends on the conditions of the individual pyrolysis process. A well-designed pyrolysis process can thus be tailored to produce biochar with specific properties suitable for a wide range of soil applications, such as improving soil fertility, reducing greenhouse gas emissions, and remediating contaminated soils.。
Effect of pH and Temperature on Enzyme Activity
Effect of pH and Temperature on EnzymeActivityEnzymes are biological catalysts that speed up chemical reactions in living organisms. They are essential for many biochemical processes, such as digestion, metabolism, and DNA replication. Enzyme activity is affected by many factors, including pH and temperature. In this article, we will discuss the effect of pH and temperature on enzyme activity.Effect of pH on Enzyme ActivitypH is a measure of the acidity or basicity of a solution. Enzymes have an optimal pH range at which they function most efficiently. This optimal pH range varies for different enzymes. For example, the optimal pH for pepsin, an enzyme found in the stomach that breaks down proteins, is around 2.0, which is very acidic. In contrast, the optimal pH for alkaline phosphatase, an enzyme found in the liver and bones, is around 9.0, which is very basic.When the pH of the environment deviates from the optimal pH range for an enzyme, the enzyme's activity decreases. This is because enzymes are sensitive to changes in pH. At low pH levels, the enzyme may denature or lose its shape, making it unable to bind to its substrate and catalyze the reaction. At high pH levels, the enzyme may become too alkaline, which can also cause denaturation.Effect of Temperature on Enzyme ActivityTemperature is another critical factor that affects enzyme activity. Enzymes have an optimal temperature range at which they function best. For most enzymes, this optimal temperature is around 37°C, which is body temperature. However, there are exceptions to this rule. For example, enzymes in psychrophiles, organisms that thrive in extreme cold, have an optimal temperature range of 0-15°C.When the temperature of the environment deviates from the optimal temperature range for an enzyme, the enzyme's activity decreases. At low temperatures, enzymes have less kinetic energy, which means they move more slowly. This slows down the rate of the reaction and reduces enzyme activity. On the other hand, high temperatures can cause enzymes to denature and lose their shape, rendering them inactive.pH and Temperature InteractionThe effect of pH and temperature on enzyme activity can also interact with each other. Enzymes may have different optimal temperature ranges depending on the pH of the environment. For example, acid phosphatase, an enzyme found in the prostate gland, has an optimal temperature range of 30-40°C at pH 4.5, but an optimal temperature range of 55-60°C at pH 7.0.ConclusionIn conclusion, pH and temperature are critical factors that affect enzyme activity. Enzymes have optimal pH and temperature ranges at which they function most efficiently. Deviations from these optimal ranges can reduce enzyme activity by causing denaturation or slowing down the reaction. The effect of pH and temperature on enzyme activity can also interact with each other, meaning optimal temperature ranges may change depending on the pH of the environment. Understanding the effect of pH and temperature on enzyme activity is essential for researchers and scientists studying biochemistry and biology.。
P6U3
此外，可再生能源系统经常造成局部干扰，许多人反对大量的风力涡轮机占用农村土地等等。
尽管存在这些障碍，自始至终可再生能源有一个美好的未来，并且继续增加其在世界能源需求中的比例，同时继续关注矿物燃料能源对气候的影响。
你能做什么
生物是一种可再生能源，因为它含有来自太阳的能量。通过光合作用，植物上的叶绿素通过将空气中的二氧化碳和土壤中的水转换成碳水化合物捕捉到了太阳能。当这些碳水化合物燃烧时，它们还原成二氧化碳和水，释放出它们带有的太阳能。这样，生物活动就是一种太阳能的自然存储。
关于可再生能源的问题
可再生能源
可再生能源如下：
太阳能 太阳给所有的生物提供一种基本的能量。太阳能是免费和用之不竭的。将阳光转换为人类消费的形式会产生成本。数千年来阳光被人类用来晒干农作物、加热水和建筑。二十世纪采用的是光电技术，即将阳光直接转换为电。
风能 空气的运动可被用来作为能源，从远古时代即是如此。今天，先进的空气动力学研究已研究出风力涡轮机，它可以非常经济地发电。风力涡轮机通常成组地置于农场，位于沿海或山顶的乡村开阔地带，那里全年都有盛行风。
实验报告英语作文模板
实验报告英语作文模板英文回答：Introduction。
The purpose of this experiment was to investigate the effect of temperature on the rate of a chemical reaction. The reaction studied was the decomposition of hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2). The hypothesis was that the rate of the reaction would increase as the temperature increased.Methods。
The experiment was conducted by measuring the volume of oxygen produced over time at different temperatures. The following materials were used:100 mL of 3% hydrogen peroxide solution。
10 mL of catalase enzyme solution。
250 mL graduated cylinder。
Thermometer。
Stopwatch。
The procedure was as follows:1. The hydrogen peroxide solution was poured into the graduated cylinder.2. The catalase enzyme solution was added to the hydrogen peroxide solution.3. The stopwatch was started.4. The volume of oxygen produced was recorded every minute for 10 minutes.5. The temperature of the solution was recorded everyminute for 10 minutes.Results。
影响盐雾试验结果的决定因素
影响盐雾试验结果的决定因素（Determining factors affecting the results of salt spray test）1、盐溶液的浓度及密度（1, the concentration and density of the salt solution）盐溶液的浓度对腐蚀速度的影响与材料和覆盖层的种类有关。
浓度在5%以下时钢、镍、黄铜的腐蚀速度随浓度的增加而增加；当浓度大于5%时，这些金属的腐蚀速度却随着浓度的增加而下降。
上述这种现象可以用盐溶液里的氧含量来解释，盐溶液里的氧含量与盐的浓度有关，在低浓度范围内，氧含量随盐浓度的增加而增加，但是，当盐浓度增加到5%时，氧含量达到相对的饱和，如果盐浓度继续增加，氧含量则相应下降。
氧含量下降，氧的去极化能力也下降即腐蚀作用减弱。
但对于锌、镉、铜等金属，腐蚀速度却始终随着盐溶液浓度的增加而增加。
The influence of the concentration of the salt solution on the corrosion rate is related to the type of the material and the covering layer. The corrosion rate of steel, nickel and brass increased with the increase of concentration in the concentration of 5%. When the concentration was greater than 5%, the corrosion rate of these metals decreased with the increase of concentration. This phenomenon can be explained by the oxygen content in the salt solution, salt solution, the oxygen content and salt concentration, in the low concentration range, the content of oxygen increased with the increase of salt concentration, however, when the salt concentration increased to 5%, the oxygen content reached the relative saturation, if the salt concentration continues to increase, the oxygen content decreased correspondingly. The oxygen content is decreased, and the depolarization ability of oxygen is decreased, and the corrosion effect is weakened. But the corrosion rate of zinc, cadmium, copper and other metals increased with the increase of the concentration of the salt solution.2、样品的放置角度及位置（2. The position and angle of the sample）样品的放置角度对盐雾试验的结果有明显影响。
全球气候变暖影响英文版
全球气候变暖影响英文版1．One of the effects of global warming is the destruction of many important ecosystems.Changing and erratic climate conditions will put our ecosystems to the test, the increase in carbon dioxide will increase the problem. The evidence is clear that global warming and climate change affects physical and biological systems. There will be effects to land, water, and life. Already today, scientists are seeing the effects of global warming on coral reefs, many have been bleached and have died. This is due to warmer ocean waters, and to the fact that some species of plants and animals are simply migrating to better suited geographical regions where water temperatures are more suitable. Melting ice sheets are also making some animals migrate to better regions. This effects the ecosystems in which these plants and animals live. Several climate models have been made and they predict more floods (big floods), drought, wildfires, ocean acidification, and the eventual collapse of many ecosystems throughout the world both on land and at sea. There have been forecasts of things like famine, war, and social unrest, in our days ahead. These are the types of effects global warming could have on our planet.2．Another important effect that global warming will bring is the loss and endangerment of many species. Did you know that 30 percent of all plant and animal species alive in the world today are at risk of extinction by the year 2050 if average temperatures rise more than 2 to 11.5 degrees Fahrenheit. These mass extinctions will be due to a loss of habitat through desertification, deforestation, and ocean warming. Many plants and animals will also be affected by the inability to adapt to our climate warming.Some species will survive though because they will migrate to other parts of the world where they can survive. A good example of that happening is the red fox that has already done it. The red fox used to live mainly in North America, but has migrated now to the Arctic. People like you and me are also in danger, people living in coastal areas will be badly hit if sea levels rise. Desertification will also be a problem for humans, food may become scarce.3．One very disappointing effect of global warming is war and conflicts.With a decline in the amounts of quality food, water, and land, it could bring an increase in global security threats, and war. Take the country Sudan for example, in that region global warming has played an important role. There is conflict in Sudan, global warming is not the only cause, but it has played its part. The roots of the problem in Sudan can be traced back to climate change, and the scarcity of natural resources. The conflict in Sudan started during a time of intense drought. Scientists and military analysts are predicting that climate change and the devastation it causes could bring war and conflict. When sufficient amounts of water and food are running short that is when war can come about. What this brings to light is the fact that ecological crisis and violence are both linked.4．Economic calamities are another effect that global warming could bring. Take hurricane Katrina for example, one thing that climate change does is that it brings us more extreme storms like Katrina. Hurricane Katrina resulted in millions and millions of dollars in damage. When severe storms and floods occur, crops, homes, businesses, and more all fail, and that costs a lot of money, and it hurts the economy. When severe floods occur you also need to make sure that the threat of disease iscontrolled. Hurrican Katrina resulted in 135$ billion in property damage. That really hurt the economy that year. When severe weather does damage it can also raise the price of insurance, and this hurts the everyday person.Cleaning up a disaster area also costs a lot of money. If too many extreme storms hit in a certain time frame the impact on the economy can be disastrous.5．Drought is an effect of global warming that we are already seeing right now. Many countries are finding that they are currently receiving more storms and rising waters, while other countries are suffering from drought. As the climate of the Earth warms, experts from Scientific American predict that drought conditions could increase by as much as 66 percent. Drought will mean a shrinking water supply and a decrease in crops. Drought can mean a danger for global food production and supply. This also mean that several countries experiencing drought could have a major famine on their hands. Currently, India, Pakistan, and some parts of Africa are already experiencing droughts. It is sad to say but experts are predicting that it will get much worse. One important effect global warming is having on our planet, is that it is producing more intense storms and floods. When you look at the scientific data concerning storms and floods in the last 30 years, you will see that category 4 and 5 hurricanes have nearly doubled in occurence. What many people don't know or realize is that warm waters give hurricanes their strenght and power. Many scientists today are associating the increase in ocean and atmospheric temperatures to the rate of violent storms. Between the years 1905 and 2005 the frequency of hurricanes has been on the rise. From 1905 to 1930 there were an average of 3.5 hurricanes per year, 5.1 between 1931 and 1994,and 8.4 between1995 and 2005. In 2005 there was a record number of tropical storms that came about, and in 2007 the worst flooding in 60 years hit Britain. More recently, Australia has seen the worst flooding they have had in a long time.6．Heat waves are also an effect of global warming. It is no secret that temperatures are breaking records in the US and Canada and abroad. More extremely hot summer days are in store for North America and elsewhere if global warming continues unabated. Here are some heat waves facts for you: air pollution in urban areas could get worse with the increased heat. This could result in more people having heart attacts, strokes, and asthma attacks. Children, the elderly, poor, and people of color are more vulnerable to the effects of a heat wave. Scientists have confirmed that the frequency and duration of heat waves has definitely increased by a lot over the last 50 years.7．One obvious effect of global warming is the shrinking of glaciers, this is happening wherever there are glaciers worldwide.Mountain glaciers have been in retreat for a long time now as global warming continues to effect us. What many people don't realize though is that it is happening more rapidly now then previously believed. Glaciers don't only recede they also shrink vertically. The lakes this melting produces can also lead to more melting. These lakes are like a cancer that is consuming our world's glaciers. Here is a fact that may surprise you: Even if all the world's mountain glaciers were to melt, the effect on sea levels would be small. However, the disappearance of mountain glaciers would have other impacts on nature aside from raising sea levels.8．Global warming will also bring a rising of sea levelsaround the world. As glaciers and polar ice sheets melt, the sea levels will rise more and more, and the sea temperatures will also warm. This means more hurricanes, and more flooding due to the rise of the sea level.The Effects of Global WarmingNowadays,our world is becoming hotter and hotter.And we called it“GlobalWarming”which is to describe the rise of tempe rature.The Global Warming has two sides of effect to the world’s creature.First,the Global Warming means there is more carbon dioxide in our atmosphere.So some plants can grow faster and stronger than before.This is its good effect.But on the other hand,the Global Warming will bring us more disasters than fortune.Because of the more and more carbon dioxide in the atmosphere,the earth’s temperature is rising day by day.The high temperature will cause many serious problems.Like the ice of Antarctica and Arctic Ocean begin to melting.After that happen, the height of sea level will lift.Then some terrible disasters will coming,like tsunami and so on.Maybe some countries,for example like Japan and some coastal cities will be submersed. One reason of Global Warming is that too much industrial emissions and poisonous gases which were made by human beings vented to our atmosphere.Especially methane and carbon dioxide.These gases make the temperature rise day afteerday.And that will cause many natural disasters.Like tsunami,flood, drought and so on. Finally ,if we don’t stop, the world will become a death world without lives.Our fate will like the dinosaurs.Another main reason of Global Warming is the fast growing ofthe world’s population.So if we don’t control the speed of growing population,the situation will be worse. So is it alreadytoo late to prevent the Global Warming?I think it is still not too late.If we plant more trees,produce less greenhouse gases like methane and carbon dioxide,and to control the growing of population.The situation of Global Warming will be better.And we must to do it first in our daily lives.Go to work by bus or on foot I think,is the best way to prevent the worse situation of Global Warming.全球气温变暖的主要原因：人类活动对气候变化肯定是有变化和影响的。
EFFECTS OF TEMPERATURE ON OXYGEN CONSUMPTION AND AMMONIA EXCRETION BY SOLENAIA OLEIVORA
R 22;6232X Q 2Q ,2x q q @63EFFECTS O F TEMPERATURE O N O X Y GEN CO N SUMPTIO NAN D AMMO NIA EXCRETIO N B Y SOL ENAIA OL EIVORAXU Qiao 2Qing 1,LIU J un 2and HUANG Hua 2Wei 1(1.A nimal Science College of Y angt ze Universit y ,J ingzhou 434025,China;2.Conti nuous Education College of Y angt ze Universit y ,J ingzhou 434025,China)A bstr act :T he effects of water temperature on ox ygen consu mpti on rate and amm on ia excretion rate of So lenaia oleiv ora w ere s tud 2ied in the lab oratory.T he results sh ow ed that ,under controlled conditions and ambient tem peratures 15—30℃,the relationship betw een ox ygen consum ption rate (O )[mg/h]and dry weight of s o ft tissue (W )[g]can be repres ented by an allometric equation O =aW b ,wh ile th e relationship between ammonia excretion rate (N )[μg/h]and dry weig ht of so ft tissue (W)[g]follows als o an allometric equation N =cW b .It is indicated that b oth metabolic rates are correlated positively w ith water tem perature.H igh temperature can reduce the lev el o f protein metabolism.T he linear regress ion am ong ox ygen consum ption rate (O),temperature (T )and dry weigh t of so ft tissue (W )can be des cribed by the equation O =-0.6513+0.0532T+0.1073W ,and for ammonia th is relati on is N =32.1626-1.0566T+1.3222W ,the mu ltiple relation coefficient was 0.9642and 0.8921,respectively.Key w or ds :Solenaia o leiv ora ;T emperature ;Ox ygen consu mpti on rate ;Am monia excretion rate CLC number :Q 507 Document code :A A r ticle ID :100023207(2006)0620697205 The respiration metabolism and excretion of marine bivalves w ere studied by different researchers [1—6].The metab olic rate of bivalves is in fluenced by a number ofvariables ,i ncluding temperature ,body size ,oxygen ten 2sion ,food c oncentration ,reproductive state ,activity level and physiological condition.The excreted metabolites of bivalves include amm onia ,urea ,uric acid and others ,w ith amm onia com prising 70%of the total excretion.Solenaia oleivora is a pr oper freshwater bivalve in China.F or the consumer it has the follow i ng advantages:a big foot ,delicious taste and alw ays w ell 2fed [7].T o t he au 2thors ’know ledge ,there are s o far no published report s or studies on the oxygen metaboli sm and excretion of thi s mussel species.1 Ma ter ials and met hodsS.oleivora were collected from the Zhanghe Reser 2v oir of J ingmen City in H ubei Pr ovince ,and w ere accli 2mated f or 8days to laboratory conditions and then divided into tw o ex perimental groups (36per group ).Shell length(S L),w et w eight (WW),dry weight of soft ti ssue (D W ,65℃,48h ),and dry shell w eight (SW ,65℃,48h )w ere determined.The fatness (F )of mussels show i ng the de 2gr ee of grossness w as calculated using the formula F =(DW/SW )×100.The biological par am eters of the experi 2mental individuals are listed in T ab.1.From T ab.1,gr oup A re presented larger mussels (15.5—17.0cm )and group B represented smaller mussel s (13.8—15.2cm).Fr om initial 15℃,the water tem perature w as i n 2creased by 1—2℃per day.A fter reachi ng t he exper i 2mental tem perat ure ,the mussel s w ere acclimated for 5days and w ere fed with Chlor ella sp.and Scenede smus sp.(6.8×105cell/ml ).At water temperatures of 15,20,25and 30℃,the experiment was began after stop feeding for 8hours.A 5L beaker w as used as breathi ng bottle ,and it w as pressurized.The concentrations of dis 2s olved oxygen and amm onia 2N in the test medium w eredetermined be fore and after pressurization for 2hours bythe W i nkler met h od re f and by t he hypobr omite method for amm onia re f ,respectively.The relationship betw een oxy 2第30卷第6期水生生物学报Vol.30,No.62006年11月ACT A HY DROBIO LOGICA SINICANov.,2006 ec eive d da te :20041104Acce pted da te :2009Corre sponding a uthor :u iao ing E mail :u i a o ing gen consum ption rate (O )or amm onia excretion rate (N )and tem perature (T )w as reckoned using AN OV A method ,while t he relationship betw een oxygen consump 2tion rate (O )or amm onia excretion rate (N )and tem per 2ature (T )and dry weight (D W )w as calculated using multiple regression analysis.Tab.1 Bi ological parameters o f exper im ental individual s (�x ±S E).S L =Shell length (cm);WW =w et w eight (g);DW=dr y w eight (g);F =(DW /SW)×100G roupn S L WW DW F Larger s ize m uss el s (A)3616.33±0.1037.92±0.527.49±0.1019.7±0.002S maller s ize m uss el s (B)3614.29±0.0624.21±0.345.78±0.0523.9±0.0022 R esults2.1 E ffect of temperat ur e on oxygen consumpt ionra teThe relationship betw een oxygen consum ption (mg/h ind )and dry w eight of soft 2ti ssue (g )can be represented by the allometric equation O =aW b (T ab.2,r 2i s the re 2gression c oef ficient ),b ranged fr om 0.2856to 0.8678,mean of 0.5122;a ranged from 0.2479to 1.0638,peaked at 25℃,m ean of 0.5397.F ig.1shows the e ffect of tem perature on the oxygen consum ption rate (mg/(h g (D W ))of S.oleiv ora.The oxygen c onsumption rate w as negatively r elated to dry w eight of s oft tissue (the larger the size ,the low er the rate).The oxygen c onsum ption rate increased in the range of 15—25℃as tem perature went up and began to declinewhen temperature exceeded 25℃.AN O VA analysis re 2vealed that bot h tem perature and dry w eight had distinct e ffects on oxygen c onsum ption rates of S.ole ivora.F test indicated t hat both tem perat ure and dry w eight had m arked e ffects at significant levels (F >F 0.01and F >F 0.05,re 2s pectively)(T ab.3).Fig.1 E ffects of tem perat ure on oxygen c onsum ption rate of S.oleivoraTab.2 P aramet ers of t he allometr i c r el at ionship bet w een oxygen consumption (m g/h)and dry weight (g)of s oft 2t iss ue of S.ol eivora at four different t est temperat uresT (℃)a b r 2n 150.24830.56020.985818200.59890.28560.94011825 1.06380.33510.800118300.24790.86780.952418T ab.3 The resul ts of ANOVA of oxygen consumpt ion rate of S.olei vora under di fferent temperat ure exposur es(df =n -1,SS =square summ at ion ,MS =SS/df ,F val ue =MS (A )or(B)/MS (A ×B))S ource of variation df SS MS F value F 0.05val ue F 0.01val ue Dry body weight (A )10.12710.127113.5213 5.99313.74T em perature (B )3 5.5279 1.8426196.0213 4.769.7833Interact (A ×B)30.02610.00870.92554.769.78S am pling error 60.05640.0094T 3535 (3ff ;33y ff )698 ACT A HY DRO B I O LOG ICA SINICA 30卷ot al1.77:e ach treat has remarka ble di erenc e :ea ch treat ha s ve r re markable di ere nce2.2 E ffect of tempera ture on a mmoni a 2N excret ion ra teT he r elationship betw een am m onia 2N excretion (μg/h ind )and dr y w eight of s oft 2tissue (g )can be represented by the allometric equation N =cW d (Tab.4,r 2is the re 2gression coe fficient ).The d value ranged from 0.367to 0.924,mean of 0.624;c value ranged fr om 1.159to 14.502,peaked at 20℃,mean of 6.032.F ig.2show s the e ffect of tem perature on the am m onia 2N excretion quantity (μg/h g)of S.oleivora.The am 2m onia 2N excretion quantity of smaller mussel s w as higher than that of the larger ones.The amm onia 2N excr etion in 2creased in the range of 15—20℃and declined in the range of 20—30℃.A N OV A analysis revealed that temperature ,dr y w eight and their i nteraction all had distinct e ffects on am monia 2N excretion quantity of S.ole ivora.F test indi 2cated t hat the three factors had m arked e ffect s on am m onia 2N excretion quantity (F >F 0.01)(T ab.5).F ig.2 E ffects o f tem perature on am m onia 2N excreti on rate of S.ol eivoraTab.4 P ara m et ers of t he allometr i c r el at ionship bet w een ammonia 2N excret ion quant ity (μg/h)and dry weight (g)of so ft 2t is sue of S.olei voraT(℃)c d r 2n 15 3.93640.68290.9960182014.50170.52180.95711825 4.53590.36740.918718301.15190.92430.973618Tab.5 The results of AN OVA of ammon i a 2N excretion rate of S.oleivora under di fferent temperat ure(df =n -1,SS =square summ at ion ,MS =SS/df ,F val ue =MS (A )or(B)/MS (A ×B))S ource of variation df SS MS F value F 0.05val ue F 0.01val ue Dry body weight (A)141.789641.798681.0522 5.9913.7433Tem perat ure(B)33885.47221295.15742511.4551 4.769.7833Interact (A ×B )322.58047.526814.59534.769.7833S am pli ng error 6 3.09410.5157T otal133952.9453 33:each t reat has very rem arkable di fference2.3 R elat ionship bet w een oxygen consumption ,am 2monia 2N excr et ion ,temperat ure and dry w eightof soft t issueThe ex perimental data in this study were analyzed by multiple regression analysis.The linear regressive rela 2tionship between oxygen consum ption quantity (O )andtem perature (T )and dry w eight of s oft tissue (W )c ould be descr i bed by the equation O =-0.6513+0.0532T +0.1073W ,and am monia 2N excretion quantity (N)by the equation N =32.1626-1.0566T +1.3222W ,with t he multiple regression c oefficient r being 0.9642and 0.8921(T ab.6,7).Tab.6 The r esult s o f ANOVA relate t o dual i t y regress equation about oxygen con s umption rat e bet w een t emperature and dry w eight of soft 2t issue of S.oleivora (df =n -1,SS=s quare summ at i on ,MS=SS /df ,F value =MS (A )or (B )/MS (A ×B))S ource of variation df SS MS F value F 0.05val ue F 0.01val ue Regress ion 2 2.4259 1.21297.70973.475.7833L 3353T 35 33y ff 6期X U Qiao 2Qing et al.:E FFE CTS OF TE MPERAT URE O N OXYG E N CO NSU MPTI ONA ND A M MO NIA EX CRETIO N BY SO L ENAIA OL EIVOR A699 eavi ngs 21.0400.17otal2.7299:e ach t reat has ver remarka ble di erenc eTab.7 The result s of AN O V A relate t o dual i t y regres s equat ion about ammonia excret i on rat e bet w een temperat ure anddry w eight of soft2t issue of S.oleivora(df=n-1,SS=s quare summ at i on,MS=SS/df,F value=MS(A)or(B)/MS(A×B)) S ource of variation df SS MS F value F0.05val ue F0.01val ue Regress ion2850.555425.2776 4.2479 3.473 5.78 Leavi ngs212102.374100.113T otal233952.929 3:each t reat has rem arkable di fference Oxygen c onsum ption rate increased significantly with temperature raising from10℃to25℃,while amm onia2 N excretion rate peaked at20℃.The ratio of oxygen consumed to NH+4excreted(O:N,calculated in atom ic equivalents)could be used to identify the pr otein metabolic level of the mussel,and ranged from27.0819 to23616393,mean of130132±34124.The ratio peaked at25℃and it was negatively related to dry weight of s oft ti ssue(t he larger the size,the lower the rate)(T ab.8).Tab.8 The oxygen consumption rates(O)[mg/h g]and ammoni a excretion rates(Ns)[μg/h g]an d t heir rat io(atomicity O:N)of S.olei voraT(℃)A(Larger s ize m uss el s)B(S m all er size m us sels)O N O:N O N O:N150.1032 2.089252.48420.1152 2.262654.0971 200.1417 5.559327.08190.1737 6.299729.2960 250.2725 1.2481231.97960.3335 1.4974236.6393 300.18990.9887204.07480.1963 1.0082206.87243 DiscussionE ffec t of temperatur e on oxygen consumption rate and amm oni a2N excretion rate of S.oleivoraMussels are poikilotherms,and tem perature i s one of the im portant factors e ffecting t heir respiration.Many study indicated that the oxygen consumption is pr oportion2 al to a constant pow er of the body weight as described by the allometric equation.The value varies with many fac2 tors,such as tem perature and dissolved oxygen.In our experiment,the consumption values increased with w ater temperature raising fr om15℃to25℃,but over25℃, this rate declined with increasi ng tem perature.The result s are in agreement wit h those reported in the litera2 ture[1,4,8,9],also differ fr om those reported by oth2 ers[5,10,11,12].Bougrier et al.(1995)[12]c onsidered step changes in oxygen consumption being the result of tw o factors.On t he one hand,some studies w ere implemented in the natural conditions while in other studies,ex peri2 mental samples were adapted for different times.W i ddows (8)[3]xy f2ff22,22domestication.On the other hand,the tem perature range designed in an experiment maybe not within the optim al physiological experimental tem perature.In most st udies,the value for t he exponent b varied slightly in the equation O=aW b,and w as0.4—0.5 c omm only and that less than1m ostly.Bayne and N ewell (1983)[14]reported t he b value for23bivalve species w as 0.44—1.09,mean of0.75.The b value of our studied mussel w as0.2856—0.8678,mean of0.5099and less than0.75,and those agreed w ith above results by and large.This finding is also supported by results reported in the literature[2,4,5].D ifference of b value w as aroused by bivalve biology characteri stic.The relationship between amm onia2N excretion quan2 tity and dry weight of S.oleiv ora can be represented by the allometric equation N=cW d.The c value increased w ith increasing tem perature fr om15℃to20℃,and peaked to14.5017,whereafter dr oped with w ater temper2 ature.Those showed that exorbitant temperature restrained excretion of S.ole ivora on the c ontrary.The conclusionL()[8],Y(8)[],F()[5],W ()[]700 ACT A HY DRO B I O LOG ICA SINICA30卷1971reported that o gen consumption rate o mus sel sh owed di erent changing trends with changing tem perature w ithout pre adaptation short term and long term accorded w ith iu et al.1999but di sagreed wit h ang et al.1991an et al.2002and ang et al.20024.3.1 Effect of dr y w eight of soft2tissue on oxygenconsumpt ion rate and ammoni a2N excretionra te of S.oleivoraDry w eight of soft2ti ssue had distinct e ffect on oxygen consumption rate and amm onia2N excretion rate of S. ole ivora.In our experiment,the oxygen consumption rate and amm onia2N excretion per gram of smaller size was higher than t hat of larger size of S.oleiv ora.The result agreed w ith that reported in literature[3,5,15].3.2 Effect of temperat ure on meta bol iza bil ity of S.oleivoraO:N could be used to express the ratio of cataboli sm pr otein to that of fat and carbohydrate.Under t he c on2 tr olled conditions of water temperature from15℃to 30℃,O:N maximized at25℃of S.oleivora in our ex2 periment.The result accounted for pr otein metab olic level reduced while fat and carbohydrate metabolic level as2 cended in the metab olic substance of S.oleivora.This finding is also supported by Widdows(1978)[13],Y ang et al.(1998)[1]and Jiang et al.(1999)[3].R eferences:[1] Y ang,H.S.,T.Zhang,P.W ang,Y. C.He&F.S.Zhang,1998.E ffect of tem perature on oxygen consum ption and am m onia2Nexcretion of s outhern Bay s callop A rgopecten irradians concentricus.Acta Oceanologi ca S i nica20:91—96(in C hi nes e)[2] W ang,F.,S.L.D ong&D.S.Li,1997.Studies on res pirationand excretion of Ruditape s phili ppinarum and Chlamys farreri.Jour2nal of Fisheries of China21:252—257(i n Chinese)[3] Jiang,Z.H.&J.W ang,1999.Effects of t em perature and bodys ize on oxygen consum ption rate and am m onia excreti on rate of Arcasubcrenata.Journal of Ocean Univers ity of Qingdao12:75—79(inC hines e)[4] W ang,J.,Z.H.J iang&Q.S.Tang,2002.Oxygen consum ptionand am m onia2N excret i on of Chl amys farreri.C hines e Journal of Ap2 pli ed Ec ology13:1157—1160(i n Chinese)[5] F an,D.P.,L.Q.Pan,S.Ma&S.L.D ong,2002.E ffects oftem perature on oxygen consum ption and am m onia excretion rate ofSinonovacul a const ricta.J ournal of Ocean Univers ity of Qingdao32:56—62(in C hi nes e)[6] Li n,X.T.,J.X.Zhong,X.Y.X ie,Z.N.Xu&C.J.H uang,2002.E ffects of tem perature on the energy budget of Perna viridis.Mari ne Science26:13—16(i n Chinese)[7] X u,Q.Q.,J.Liu&H.Li u,2003.T he ne w s pecies of edible m uss el2Solenaia oleivora.S cientific Fish F arm i ng6:pp14(in C hines e) [8] Liu,Q.G.,H. D.Shen,H.Q.Zhou&W.M.Li u,1999.Oxygen consum ption and am m onia excretion of the freshwater clam,Corbicula flumi nea.Journal of S hanghai F i s heries Univers ity8:298—303(i n C hines e)[9] Hutchi ns on,S.&L. E.Hawki ns,1992.Quantificati on of thephys iological res pons es of t he European flat oys t er Ost rea edulisl totem perature salinity.Journal of Molluscan S tudies58:215—226 [10] C hang,Y.Q.&Z. C.W ang,1992.Prelim ary s t udy of oxygenconsum ption rate of Scaphara broughfonii during raft.Journal of F i s h2 ery S ciences11:1—5(in C hi nes e)[11] Ha o,Y.W.,X.L.Y ang&X.H.M ao,1993.R espi ration s t udyof B ay scallop,Argopec ten irradians.Journal of Oceanography ofHuanghai and Bohai Seas11:37—43(i n C hines e)[12] B ougrier,S.,P.G eairon&J.M.des lous2Pa oli,1995.A llom etri crelationships and e ffect s of tem perature on cl earance and oxygen con2 sum ption rates of Crasso sta gigas(Thunberg).Aquaculture134:143—154[13] W iddows,J.,1978.C om bined e ffect of body size,food,concentra2ti on and s eas on on the phys iol ogy of Mytilus edulis.Journal of theMari ne B iol ogical As s ociation of the UK58:109—124[14] Bayne,B.L.&R. C.New ell,1983.Phys i ological energetics ofm arine m ollusks.The M ollus ca4:407—515[15] Ji ang,Z.H.,J.W ang&Q.S.Tang,1999.S tudies on phys iolog2ical ecol ogy of short2necked clam(Ruditapes philippinarum).M arineF i s heries Research20:40—44(in Chi nese)6期X U Qiao2Qing et al.:E FFE CTS OF TE MPERAT URE O N OXYG E N CO NSU MPTI ONA ND A M MO NIA EX CRETIO N BY SO L ENAIA OL EIVOR A701。
中国石油大学高级英语译文及答案
Unit 1 Sources of EnergyText APetroleumSentence structure analysis1. Instead of originating in accumulating woody matter, petroleum may be the product of the accumulating fattymatter of ocean organisms such as plankton, the myriads of single-celled creatures that float in the surface layer of the ocean. (Para.2) 石油，并不是来自于逐渐积聚的木质物质，而可能是来自于逐渐积聚的海洋生物的脂肪物质。
比如浮游生物：大量浮游在海水表层的单细胞生物。
这是一个简单句，主语petroleum，谓语动词may be，表语product，构成句子主干。
instead of 介词短语作状语，such as plankton是product一词的同位语，the myriads of single-celled creatures that float in the surface layer of the ocean是名词性短语，做plankton的同位语。
2. It is only necessary that the organisms settle down into the ooze underlying shallow arms of the ocean underconditions of oxygen shortage. (Para. 3) 生物有机体只需在缺氧的条件下沉积到海湾浅水处的淤泥里。
该句的框架为：it is +adj.+that从句，it做形式主语，真正的主语是that从句的内容。
现在分词短语underlying…做后置定语修饰ooze。
冰川的消融：气候变化的影响 英语作文
Title:The Thawing of Time:Glaciers and the Impacts of Climate ChangeGlaciers,the majestic rivers of ice,are not mere static monuments of nature but dynamic archives that record the history of Earth's climate. Their slow,stately progress carves out valleys,shapes landscapes,and regulates sea levels.However,these silent sentinels of the environment are now facing an existential threat as global temperatures rise due to climate change,causing them to retreat at an alarming rate.This significant reduction in glacier mass not only affects the immediate ecosystems but also has far-reaching impacts on global climate patterns, water resources,and biodiversity.The process of glacier melting is a direct reflection of increased global temperatures.As the Earth warms,the equilibrium between snowfall accumulation and melting is disrupted.Glaciers grow when snow accumulates over time,compacting into ice;they shrink when melting and sublimation—the process by which ice changes directly into water vapor—exceed new ice formation.Rising global temperatures tip the balance toward more melting and less ice formation,leading to reduced glacier size and even complete disappearance in some areas.This melting trend brings a myriad of environmental consequences.One immediate effect is the rise in sea levels.Glaciers and ice caps contain a significant amount of freshwater;as they melt,this water flows into the oceans,contributing to sea-level rise.This poses a severe risk to coastal communities and low-lying countries,where flooding and saltwater intrusion into freshwater sources become pressing issues.Furthermore, the loss of glaciers means the loss of a natural storehouse for freshwater. In regions dependent on glacial melt for agriculture and drinking water, such as parts of South America and Asia,this can lead to water scarcity during the dry season,affecting local economies and food security.Glaciers play a crucial role in regulating global climate patterns through their influence on ocean currents.Meltwater from glaciers contributes to the formation of cold,dense water that drives the ocean's overturning circulation,including phenomena like the Gulf Stream. Changes in glacier melt rates can disrupt these currents,potentially altering weather patterns across the globe.Additionally,melting glaciers release ancient carbon trapped in ice and soil into the atmosphere, further exacerbating climate change.The loss of ice also impacts biological diversity.Many animals,such as the Arctic polar bear,have adapted to live in close association with glaciers.As these icy habitats diminish,so too does the habitat available for these specialized species,leading to declines in their populations and, potentially,extinction.The thawing permafrost also releases nutrients and organic matter once locked in ice,leading to changes in ecosystem nutrient cycles that can affect vegetation growth and wildlife populations.In confronting the challenge of glacier retreat,it becomes imperative to address the root causes of climate change.Reducing greenhouse gas emissions globally is critical to mitigating further warming and preserving the world’s remaining glaciers.Adaptation strategies such as sustainable water management and the development of drought-resistant crops are essential to cope with the changing conditions. Research and monitoring of glaciers also play a vital role in understanding the implications of their changes and developing informed policies to protect these natural wonders.As we witness the accelerated thawing of our planet's glaciers,we are faced with a profound reminder of the delicate balance of Earth's systems and the urgent need for action to combat climate change.The fate of glaciers rests in our collective hands,and the future they foretell depends on the measures we take today to safeguard our shared environmental heritage.。
高温对人类的影响英语作文
高温对人类的影响英语作文The Impact of High Temperature on HumansIn recent years, the issue of high temperature and its effects on human beings has bee increasingly prominent. High temperatures can have a significant impact on our lives in various aspects.Firstly, high temperatures pose a direct threat to our physical health. Heat strokes and heat exhaustion are mon problems during hot weather. The elderly, children, and those with certn chronic diseases are particularly vulnerable. Prolonged exposure to high temperatures can lead to dehydration, fatigue, and in severe cases, organ flure and even death.Secondly, high temperatures affect our dly activities and work efficiency. It bees unfortable to carry out outdoor work or exercise, as the heat makes us feel drned and less energetic. This can have an adverse effect on productivity in many industries, such as construction and agriculture.Moreover, high temperatures also put a strn on the power supply. The increased use of r conditioning and other cooling devices leads to a surge in electricity demand, which may result in power shortages and blackouts.High temperatures also have an impact on our mental well-being. The hot and unfortable environment can cause irritability, stress, and sleep disturbances, affecting our mood and overall quality of life.To cope with the challenges brought high temperatures, we need to take various measures. This includes staying hydrated, avoiding prolonged exposure to the sun, wearing light and breathable clothing, and using proper cooling methods. At the same time, the government and society should also strengthen infrastructure building to improve the ability to deal with extreme temperatures and promote energy conservation and emission reduction to mitigate the effects of climate change.In conclusion, high temperatures have multiple negative impacts on human beings, and it is crucial for us to be aware of these effects and take active steps to protect ourselves and our munities.。
Effect of Temperature on the Organic Solar Cells P
Journal of Energy and Power Engineering 6 (2012) 921-924Effect of Temperature on the Organic Solar Cells ParametersBelhocine-Nemmar Farida, Hatem Djediga, Boughias Ouiza and Belkaid Mohammed SaidAdvanced Technologies of Electrical Engineering Laboratory (LATAGE), Mouloud Mammeri University, Tizi-Ouzou 15000, Algeria Received: February 14, 2011 / Accepted: June 09, 2011 / Published: June 30, 2012.Abstract: The dependence of the organic solar cells parameters, e.g., the shirt circuit current I sc, open circuit voltage V oc, the fill factor FF and the efficiency eta on temperature is investigated. By expressing the different equations which link the parameters with temperature, it is observed that the short circuit current I sc increases so monotonous with temperature and then saturates to a maximum value before decreasing at high temperatures. The open circuit voltage V oc decreases linearly with the increasing of the temperature. The fill factor FF and the efficiency eta which are directly related with short circuit current I sc and the open circuit voltage V oc follow their variations.Key words:Cells parameters, organic materials, solar cells, temperature effect.1. IntroductionThe organic solar cells can be an alternative to the silicon based photovoltaic cells [1]. They have recently acquired a big interest because of their ease implementation and flexibility. They are made with a transparent semi-conductor as electrode, a mixture of organic semi-conductors in three dimensions, in continuous network as an active layer and a metal layer as against electrode. The best performance was obtained using a composite of two organic materials: a donor and an acceptor, in a bulk interpenetrated network. This concept is very investigated because it allows a large interfacial surface which provides good excitants separation. The best efficiencies are allowed from the cells which use a mixture of (poly-3 hexylthiophene) P3HT and ([6-6]-phenyl C61 butyric acid methyl ester) PCBM, which allows an efficiency of 5% [2].For the reliability of these devices in different operating conditions, the effect of variousCorresponding author: Belhocine-Nemmar Farida, Dr., research field: advanced technologies of electrical engineering laboratory(LATAGE).E-mail:************************.environmental parameters are investigated, e.g., temperature, humidity, electric and magnetic fields, sandstorm and illumination intensity on their performances.In this paper, the effect of temperature on the organic solar cells parameters has been studied. The relations which link the shirt circuit current I sc, open circuit voltage V oc, the fill factor FF and the efficiency eta with temperature were expressed and their interpretations have been discussed.2. Short Circuit Current I scIn a solar cell, at any point depth z in the bulk of the device, the density of the current J(z) (which is the current per surface unity (s)) is proportional to the difference between the rate of generation of free charge carriers G(z) and the recombination rate R(z) according to the following equation:)()()(1zGzRdzzdJq-=(1)In the heterojunction structure devices, therecombination in the bulk is of two types:ll Rights Reserved.Effect of Temperature on the Organic Solar Cells Parameters9222.1 The First Order RecombinationThe first order recombination is due to the presence of impurities in the mixtures of the active layer of the solar cell. The first order recombination depends on the density of the impurities which are traps for the generated free carriers. In the case of electrons, the first order recombination is given by Ref. [3]:τ)()(z n z R =(2)where n (z ) represents the density of electrons at a depth, z and τn is the lifetime of the electrons. 2.2 Bimolecular RecombinationThe bimolecular recombination depends on the density of free carriers, electrons and holes. It is expressed by the following relation:)()()(z p z n K z R = (3)where n (z ) and p (z ) are the densities of electrons and holes respectively and K is the bimolecular coefficient. In the organic solar cells, the generation of the free carriers is the result of two processes: generation of excitants in the donor material of the active layer and separation of these excitants at donor/acceptor interfaces. Thus, the generation rate G (z ) depends on the diffusion length of the excitants, the absorption coefficient of the active layer materials and the intensity of the incident light. The current density that flows in a PN junction under illumination is given by:L J KT qV J J -⎥⎦⎤⎢⎣⎡-=1)exp(0 (4)where, J L is the density of photogenerated current, K is the Boltzmann constant and J 0 is the saturation current density which is given by :⎪⎪⎭⎫ ⎝⎛+⎪⎭⎫ ⎝⎛-=p p n n c v tau p L tau n L KT Eg KT N N J exp 0 (5) N c and N v are the densities of states in the conduction and valence band respectively, p and n are the densities of the electrons and holes, L n and L p are the diffusion length, tau n and tau p are the lifetimes of electrons and holes.At zero bias (the cell is short-circuited), the short circuit current density J sc generated by the cell can beexpressed as:L sc J J -= (6)In a study done by Monestier and Simon [4], the short circuit current is found to be dependent on temperature. They found that the short circuit current I sc increases with temperature and tends to be saturated at a maximum value followed by a decrease at high temperatures. This behaviour can be explained by considering that the current delivered by the cell is proportional to the number of the free charge carriers generated and their mobility. For the organic semiconductors, the charge carrier transfer occurs via localized sites. The charge carrier transfer from one site to another nearby site is associated with phonons. The conductivity is thermally activated, otherwise say, increases with temperature. The increase of the mobility with temperature is supposed to be a hoping phenomenon enabled by the phonons. This hypothesis can be verified by considering that for organic materials, the conductivity is given by:2exp(0KTEdelta sigma sigma -= (7) and the mobility by:ensigmamu =(8) where delta E is the activation energy of the process. The activation energy delta E is a contribution of two factors [5], gap energy value (the energy required to excite an electron from highest occupied molecular orbital HOMO to lowest unoccupied molecular orbital LUMO) and the delocalisation energy of the charge carriers (energy required for an electron to outside a trap).At low temperatures, the probability of a phonon with an energy that allows a jump from a site to another nearby site is low; therefore, the mobility is low at low temperatures.3. Open Circuit Voltage V OCFor photovoltaic cells based on organic materials, the open circuit voltage depends directly on the band gap energy Eg . The open circuit voltage of a PNll Rights Reserved.Effect of Temperature on the Organic Solar Cells Parameters923junction based solar cell is given by:)1ln(+=s sc oc I I q nKTV (9) Taking into account that the short -circuit current I scis so greater than the saturation current I s , the open circuit voltage V oc will be written as:)])(ln[(pn oc ptau Lpntau Ln Icc Nv Nc q q nKT q nEg V +-=(10) The slope of the equation expressing the variationsof the short circuit voltage as a function of temperature is negative, so the short circuit voltage V oc decreases linearly with temperature. From Eq. (10), it is clear that the open circuit voltage V oc depends greatly on the temperature, diffusion length, lifetime and the density of the charge carriers and it depends slightly on the materials used for the cathodes.4. The Fill Factor FFView of the prospects for improving the efficiency of organic solar cells, the most critical factor for alarge impact on the different strategies depends onbetter fill factor FF which is given by the relation:max max oc scV I FF V I ⨯=⨯ (11)V max and I max are the voltage and the current at maximum energy delivered by the cell. Their values are deduced from the cell I-V curve under illumination represented in Fig. 1.The fill factor FF is the most sensitive parameter in a solar cell in comparison with the open circuit voltage V oc and the short circuit current I sc .The fill factor FF depends on the active layer material properties (charge carriers mobility and their lifetime), the active layer morphology and the physical and chemical properties of the interface active layer/cathode. The important role of the active layer/cathode interface depends on the cathode deposit conditions which can cause a variety of chemical and physical defects, which will be subsequently traps for charge carriers.Fig. 1 Current-tension characteristic of a solar cell.In organic solar cells, the free charge carrier photogeneration comes through the dissociation of the excitants at interfaces donors/acceptors with efficiency ηg . The charge carrier collection rate do not reach a unity because the excitants in organic materials have a very limited lifetime, about 30 ns [6], which promotes the recombination of excitants before their separation.5. The Efficiency etaAdding to their limited lifetime, the efficiency eta of the organic solar cells is another factor which impedes their commercialization. It is given by the following relation:inoc sc P FFV I eta =(12)where P in is the power of the incident light. It can be enhanced by the use of the polymer absorbing in the visible and infrared spectrum and the concept of the bulk heterojunction.6. ConclusionIn this paper, the influence of temperature on the organic solar cells parameters has been studied.The open circuit voltage decreases linearly with temperature with a negative slope dV co /dT . The short circuit current at low temperatures I sc increases with temperature before reaching a maximum value of saturation and then decreases for higher temperatures. The fill factor FF and the efficiency eta follow the changes of the open circuit voltage V oc and the shortll Rights Reserved.Effect of Temperature on the Organic Solar Cells Parameters 924circuit current I sc. These variations are explained by the charge carrier mobility behavior with temperature.References[1] A. Pivrikas, P. Stadler, Substituting the post productiontreatement for bulk heterojonction solar cells using chemical additives, Organic Electronics 9 (5) (2008) 775-782.[2]M. Urien, L. Vignau, E. Cloutet, Effect of the regularityof poly (3-hexythiophene) on the performances of organicphotovoltaic devices, Polymer Inrnational 57 (5) (2008)764-769.[3]S. Amon, O. Haba, Head to tail regularity of poly(3-hexylthiphene) in oxidative coupling polymerisation with FeCl3, Journal of Polymer Science 37 (13) (1999)1943-1948.[4] F. Monestier, J.J. Simon, Modeling the shorte ciruitcurrent density of polymer solar cells based on P3HT:PCBM blend, Solar Energy Materials and Solar Cells 91(5) (2007) 405-410.[5] D. Chirvase, Z. Chiguvare, M. Knipper, J. Parisi,Dependent characteristics of poly (3-hexylthiophene) fullerene based heterojunction organic solar cells, Journalof Applied Physics 93 (6) (2003) 1-8.[6]S.A. Boujeline, Realisation and characterization of plasticphotovoltaic cells, Doctorate Thesis, Angers University,France, 2004.ll Rights Reserved.。
2023年国开非英语专业学位英语考试真题
2023年国开非英语专业学位英语考试真题2023 National Open University Non-English Major Degree English Exam QuestionsPart I: Reading Comprehension (40 points)Section A: Read the following passage and answer the questions below.Since the dawn of the digital age, the way we consume media has been forever changed. With the rise of social media platforms such as Facebook, Twitter, and Instagram, people are constantly bombarded with information and content. This has led to a phenomenon known as information overload, where individuals are overwhelmed by the sheer volume of information available to them.1. What has changed the way we consume media?2. What is information overload?3. How has social media contributed to information overload?Section B: Read the following passage and answer the questions below.Climate change is one of the most pressing issues facing the world today. With rising temperatures and extreme weather events becoming more frequent, it is crucial that we take action to mitigate the effects of climate change. One of the key ways we can do this is by reducing our carbon footprint through measures such as transitioning to renewable energy sources and reducing our reliance on fossil fuels.4. What is the main focus of the passage?5. What are some ways we can mitigate the effects of climate change?6. Why is it important to reduce our carbon footprint?Part II: Writing (60 points)Choose one of the following topics to write an essay of 500-700 words.1. The impact of social media on society.2. The importance of biodiversity conservation.3. The role of technology in education.4. The benefits of multiculturalism in today's world.Part III: Listening Comprehension (30 points)Listen to the audio clips and answer the questions below.1. What is the main topic of the first audio clip?2. What is the speaker's opinion on the topic in the second audio clip?3. What are some of the key points discussed in the third audio clip?Part IV: Speaking (70 points)Respond to the following prompts in a coherent and articulate manner.1. Discuss the pros and cons of globalization.2. Describe a memorable travel experience you have had.3. Talk about a book, movie, or TV show that has had a significant impact on you.4. Share your thoughts on the importance of learning a second language.Overall, the 2023 National Open University Non-English Major Degree English Exam covers a wide range of topics and skills, testing students' ability to read, write, listen, and speak inEnglish. Good luck to all the test-takers, and may you ace the exam with flying colors!。
The effects of temperature on enzyme activity
The effects of temperature on enzymeactivityIntroductionEnzymes are protein molecules that catalyze different chemical reactions in living organisms. They control the chemistry of life by speeding up metabolic processes in cells. Enzymes are highly sensitive to changes in temperature, and even a small change in temperature can affect their activity. In this article, we will explore the effects of temperature on enzyme activity.Temperature and Enzyme ActivityEnzymes work best within a specific range of temperature. This range is called the optimum temperature range. The optimum temperature range differs according to the type of enzyme and the organism in which it functions. The optimum temperature for human enzymes is 37 degrees Celsius, which is the normal body temperature.When enzymes are exposed to temperatures outside their optimum range, their activity decreases. If the temperature is too high, the enzyme molecule can be denatured, which means that its three-dimensional shape is altered. This can lead to a loss of enzyme activity. When the temperature is too cold, the enzymes can freeze, which can also cause a loss of activity.Effect of High Temperature on Enzyme ActivityAt high temperatures, enzymes become denatured, and their activity is greatly reduced. This happens because the high temperature disrupts the weak bonds that hold the enzyme in its three-dimensional shape. Once these bonds are disrupted, the protein loses its shape, and the active site that binds to the substrate also changes. The enzyme molecule becomes permanently altered, and it cannot function again.This can be demonstrated by doing an experiment with hydrogen peroxide and catalase, an enzyme found in living organisms that breaks down hydrogen peroxide. In the experiment, we can measure the time it takes for the enzyme catalase to break down hydrogen peroxide at different temperatures. If we raise the temperature above the optimum temperature, the reaction rate will decrease because the enzyme will lose its structure and function less effectively.Effect of Low Temperature on Enzyme ActivityAt low temperatures, enzymes become less active. This is because the low temperature decreases the rate of diffusion and slows down the collision rate between the substrate and the enzyme. The enzyme activity will increase as the temperature is raised, but only up to the optimum range.This can be demonstrated by doing an experiment with amylase, an enzyme that breaks down starch into simpler sugars. In the experiment, we can measure the time it takes for the amylase to break down starch at different temperatures. If we lower the temperature below the optimum temperature, the reaction rate will decrease because the enzyme will not have enough kinetic energy to bind with the substrate effectively.ConclusionEnzymes are essential to life, and they play a vital role in metabolic processes in living organisms. Temperature greatly affects enzyme activity, and enzymes work best within an optimum temperature range. When enzymes are exposed to temperatures above or below their optimum range, their activity decreases. Understanding the effects of temperature on enzyme activity can help us better understand how enzymes work in living organisms and how they can be used in industry and medicine.。
人类与气候之间相互影响英语作文
人类与气候之间相互影响英语作文The Interactions Between Human and ClimateIntroductionHuman activities have a profound impact on the climate and environment. The relationship between human beings and climate is a complex and dynamic one. Our actions, whether intentional or unintentional, can have far-reaching consequences on the Earth's climate system. In this essay, I will explore the ways in which humans have influenced the climate, as well as how changes in climate can affect human societies.Human Impact on ClimateOne of the most significant ways in which humans have impacted the climate is through the emission of greenhouse gases. The burning of fossil fuels for energy production, transportation, and other industrial activities has led to a dramatic increase in the concentration of carbon dioxide and other greenhouse gases in the atmosphere. These gases trap heat from the sun, leading to a warming of the Earth's surface and changes in weather patterns.Deforestation is another major contributor to climate change. Trees absorb carbon dioxide from the atmosphere, sowhen large areas of forests are cut down, this leads to an increase in greenhouse gas emissions. Deforestation also reduces the Earth's ability to regulate its temperature, as trees play a crucial role in the water cycle.Changes in Land UseHuman activities such as agriculture and urbanization have also had a significant impact on the climate. The clearing of land for farming and development can lead to changes in the Earth's albedo, or reflectivity, which in turn affects the amount of solar radiation that is absorbed by the planet. Urban areas, with their vast expanses of concrete and asphalt, can also contribute to the urban heat island effect, leading to higher temperatures in cities compared to surrounding rural areas.Human societies are also vulnerable to the impacts of climate change. Extreme weather events such as hurricanes, droughts, and heatwaves can have devastating effects on communities, leading to loss of life, property damage, and disruptions to food and water supplies. Rising sea levels, a result of melting ice caps and glaciers due to global warming, pose a threat to coastal cities and low-lying island nations.Mitigating Climate ChangeIn order to address the challenges posed by climate change, it is essential that we take action to reduce our greenhouse gas emissions and transition to a more sustainable way of life. This can be achieved through a combination of policies, technological innovations, and changes in individual behavior.Renewable energy sources such as solar, wind, and hydro power offer a cleaner alternative to fossil fuels, and can help reduce our carbon footprint. Energy efficiency measures, such as improving the insulation of buildings and using energy-efficient appliances, can also help to lower emissions.Reforestation and sustainable land management practices are crucial for preserving the Earth's natural carbon sinks and mitigating the impacts of deforestation. Protecting and restoring ecosystems such as forests, wetlands, and mangroves can help to sequester carbon and reduce the risk of extreme weather events.Adapting to a Changing ClimateIn addition to mitigation efforts, it is also important that we adapt to the impacts of climate change that are already occurring. This can involve building resilient infrastructure, implementing early warning systems for natural disasters, and developing sustainable agriculture practices that can withstand changing weather patterns.Investments in research and education are also key to increasing our understanding of climate change and developing solutions to address its impacts. By working together at the local, national, and global levels, we can create a more sustainable future for ourselves and future generations.ConclusionThe interactions between human beings and the climate are complex and multifaceted. Our actions have far-reaching consequences on the Earth's climate system, and changes in climate can in turn affect human societies in profound ways. In order to address the challenges posed by climate change, it is essential that we take action to reduce our greenhouse gas emissions, protect natural ecosystems, and adapt to a changing climate. By working together and taking proactive measures, we can create a more sustainable future for ourselves and for future generations.。
水汽影响全球变暖英文作文
水汽影响全球变暖英文作文Water vapor is a major contributor to global warming. It is a greenhouse gas that traps heat in the atmosphere, leading to an increase in temperature worldwide.The impact of water vapor on global warming is significant. As the Earth's temperature rises, more water evaporates from the oceans, leading to an increase in water vapor in the atmosphere. This, in turn, amplifies the greenhouse effect, further warming the planet.In addition to its direct impact on temperature, water vapor also plays a role in the formation of clouds. Clouds can either reflect sunlight back into space, cooling the Earth, or trap heat, contributing to the warming of the planet.The relationship between water vapor and global warming is complex and multifaceted. While water vapor is a natural part of the Earth's atmosphere, human activities, such asthe burning of fossil fuels, have led to an increase in atmospheric water vapor, exacerbating the effects of global warming.In conclusion, water vapor is a key player in the global warming phenomenon. Its ability to trap heat in the atmosphere and influence cloud formation makes it a significant factor in the Earth's changing climate. Addressing the impact of water vapor on global warming is crucial in efforts to mitigate the effects of climate change.。
2005年6月全国大学英语六级考试全真模拟试题
2005年6月全国大学英语六级考试全真模拟试题Part I Listening Comprehension （20 minutes）(略)Part Ⅱ Reading Comprehension （35 minutes）Directions: There are 4 passages in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices mared A）, B）, C） and D）.You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the center.Passage OneQuestions 21 to 25 are based on the following passage:There are three basic ways in which individual economic units interact with one another. They are the market system, the administered system, and the traditional system.In a market system, individual economic units are free to interact among each other in the market place. Transactions may take place through barter or money exchange. In a barter economy,real goods such as automobiles, shoes, and pizzas are traded against each other. Obviously, finding somebody who wants to trade an old car in exchange for a sailboat may not always be an easy task. Hence the introduction of money as a medium of exchange eases transactions considerably.An alternative to the market system is administered control by some agency over all transactions. This agency will issue laws or commands as to how much each goods and service should be produced, exchanged, and consumed by each economic unit. Central planning may be one way of administering such an economy. The central plan drawn up by the government shows the amount of each commodity produced by the various firms and distributed to different households for consumption.In a traditional society, production and consumption patterns are governed by tradition. Each per son′s place with the economic system is fixed by parentage, religion, and custom. Transactions take place on the basis of tradition, too. People belonging to a certain group or caste may have an obligation to care for other persons, provide them with food and shelter, care for their health,and provide for their education. Clearly, in a system where every decision is made on the basis of tradition alone progress may be difficult to achieve.21. What is the main purpose of the passage?A） T o explain the science of economics.B） To outline types of economic systems.C） To argue for the superiority of one economic system.D） To compare barter and money exchange markets.22. In the second paragraph, by which of the following could the word "real" best be replaced?A） High quality.B） Concrete.C） Utter.D） Essential.23. According to the passage, a barter economy can lead toA） rapid speed of transactionsB） misunderstandingsC） inflationD） difficulties for the traders24. According to the passage who has the greatest degree of control on an administered system?A） Individual households.B） Small businesses.C） Major companies.D） The government.25. Which of the following statements is true?A） The central plan drawn up by the government is mainly based on the needs of the state as a whole.B） The economic system in China is based on the traditional system.C）In a market system, transactions are controlled by the government.D） In a traditional society, economy develops very fast.Passage TwoQuestions 26 to 30 are based on the following passage:In the atmosphere, carbon dioxide （二氧化碳） acts rather like a one-way mirror—the glass in the roof of a greenhouse which allows the sun′s rays to enter but prevents the hea t from escaping.According to a weather expert′s prediction, the atmosphere will be 3℃ warmer in the year 2050 than it is today, if man continues to burn fuels at the present rate. If this warming up took place, the ice caps in the poles would begin to melt, thus raising sea level several metres and severely flooding coastal cities, Also, the increase in atmospheric temperature would lead to great changes in the climate of the northern hemisphere, possibly resulting in an alteration of the earth′s-chief food-growing zones.In the past, concern about a man-made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet. But the weather experts are now paying more attention to West Antarctic, which may be affected by only a few degrees of warming: in other words, by a warming on the scale that will possibly take place in the next fiftyyears from the burning of fuels. Satellite pictures show that large areas of Antarctic ice are already disappearing. The evidence available suggests that a warming has taken place. This fits the theory that carbon dioxide warms the earth.However, most of the fuel is burnt in the northern hemisphere,where temperatures seem to be falling. Scientists conclude,therefore, that up to now natural influences on the weather have exceeded those caused by man. The question is: Which natural cause has most effect on the weather?One possibility is the variable behavior of the sun. Astronomers at one research station have studied the hot spots and "cold" spots（that is, the relatively less hot spots） on the sun.As the sun rotates, every 27.5 days, it presents hotter or "colder" faces to the earth, and different aspects to different parts of the earth. This seems to have a considerable effect on the distribution of the earth′s atmospheric pressure, and consequently on wind circulation. The sun is also variable over a long term: its heat output goes up and down in cycles, the latest trend being downward.Scientists are now finding mutual relations between models or solar-weather interactions and the actual climate over many thousand of years, including the last Ice Age. The problem is that the models are predicting that the world should be entering a new Ice Age and it is not. One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia of the earth′s climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful counter-b alance to the sun′s diminishing heat.26. It can be concluded that a concentration of carbon dioxide in the atmosphere would .A）prevent the sun′s rays from reaching the earth′s surfaceB） mean a warming up in the ArcticC） account for great changes in the climate in the northern hemisphereD）raise the temperature of the earth′s surface27. The article was written to explain .A） the greenhouse effectB） the solar effects on the earthC） the models of solar weather interactionsD） the causes affecting weather28. Although the fuel consumption is greater in the northern hemisphere, temperatures there seem to be falling. This is .A） mainly because the levels of carbon dioxide are risingB） possibly because the ice caps in the poles are meltingC）exclusively due to the effect of the inertia of the earth′s climateD） partly due to variations in the output of solar energy29. On the basis of their models, scientists are of the opinion that .A） the climate of the world should be becoming coolerB）it will take thousands of years fro the inertia of the earth′s climate to take effectC）the man made warming effect helps to increase the solar effectD）the new Ice Age will be delayed by the greenhouse effect30. If the assumption about the delay of a new Ice Age is correct, .A）the best way to overcome the cooling effect would be to burn more fuelsB） ice would soon cover the northern hemisphereC） the increased levels of carbon dioxide in the atmosphere could warm up the earth even more quicklyD）the greenhouse effect could work to the advantage of the earthPassage ThreeQuestions 31 to 35 are based on the following passage:Before the 1850′s the United States had a number of small colleges, most of them dating from colonial days. They were small,church-connected institutions whose primary concern was to shape the moral character of their students.Throughout Europe, institutions of higher learning had developed, bearing the ancient name of university. In Germany a different kind of university had developed. The German university was concerned primarily with creating and spreading knowledge,not morals. Between midcentury and the end of the 1800′s, more than nine thousand young Americans, dissatisfied with their training at home, went Germany for advanced study. Some of them returned to become presidents of venerable （受人尊敬的）colleges—Harvard, Yale, Columbia—and transform them into modern universities The new presidents broke all ties with the churches and brought in a new kind of faculty.Professors were hired for their knowledge of a subject, not because they were of the proper faith and had a strong arm for disciplining students. The new principle was that a university was to create knowledge as well as pass it on,and this called for a faculty composed of teacher scholars. Drilling and learning by rote （死记硬背）were replaced by the German method oflecturing, in which the pr ofessor′s own research was presented in class. Graduate training leading to the Ph. D, an ancient German degree signifying the highest level of advanced scholarly attainment, was introduced. With the establishment of the seminar system, graduate students learned to question, analyze,and conduct their own research.At the same time, the new university greatly expanded in size and course offerings, breaking completely out of the old, constricted curriculum of mathematics, classics, rhetoric, and music. The president of Harvard pioneered the elective system, by which students were able to choose their own courses of study. The notion of major fields of study emerged. The new goal was to make the university relevant to the real pursuits of the world. Paying close heed to the practical needs of society, the new universities trained men and women to work at its tasks, with engineering students being the most characteristic of the new regime. Students were also trained as economists, architects, agriculturalists, social welfare workers, and teachers.31. The word "this" （sentence 8, Para. 2） refers to which of the following?A）Creating and passing on knowledge. B）Drilling and learning by rote.C）Disciplining students. D）Developing moral principles.32. According to the passage, the seminar system encouraged students to .A） discuss moral issues B） study the classics, rhetoric, and musicC） study overseasD） work more independently33. It can be inferred from the passage that before 1850, allof the following were Characteristic of higher education EXCEPT .A） the elective system B） drillingC） strict discipline D） rote learning34. Those who favored the new university would be likely to agree with which of the following statements?A） Learning is best achieved through discipline and drill.B） Shaping the moral character of students should be the primary goal.C） Higher education should prepare students to contribute to society.D） Teachers should select their students courses.35. Why many students decided to study aboard?A）Because thousands of young Americans wanted to go to Germany to study.B）Because young Americans were not satisfied with their school system in the USA.C）Because American professors were not as good as those abroad.D）Because European universities were not connected with churches.Passage FourQuestions 36 to 40 are based on the following passage:The nuclear age in which the human race is living, and may soon be dying, began for the general public with the dropping of an atom bomb on Hiroshima on 6 August 1945. But for nuclear scientists and for certain American authorities, it had been known for some time that such a weapon was possible.An atom consists of a tiny core called the "nucleus" with attendant electrons circling round it. The hydrogen atom, whichis the simplest and lightest, has only one electron. Heavier atoms have more and more as they go up the scale. The first discovery that had to do with what goes on in nuclei was radioactivity, which is caused by particles being shot out of the nucleus. It was known that a great deal of energy is locked up in the nucleus, but until just before the outbreak of the Second World War, there was no way of releasing this energy in any large quantity. A revolutionary discovery was that, in certain circumstances, mass can be transformed into energy in accordance with Einstein′s formula which states that the energy generated is equal to the mass lost multiplied by the square of the velocity of light.The A-bomb, however, used a different process, depending upon radioactivity. In this process, called "fission", a heavier atomsplits into two lighter atoms. In general, in radioactive substances this fission proceeds at a constant rate which is slow where substances occurring in nature are concerned. But there is one form of uranium called "U235" which, when it is pure, sets up a chain reaction which spreads like fire, though with enormously greater rapidity. It is this substance that was used in making the atom bomb.The political background of the atomic scientists′ work was the determination to defeat the Nazis. It was held—I think rightly—that a Nazi victory would be an appalling disaster. It was also held, in Western countries, that German scientists must be well advanced towards making an A-bomb, and that if they succeeded before the West did they would probably win the war. When the war was over,it was discovered, to the complete astonishment of both American and British scientists, that the Germans were nowhere near success, and, as everybody knows, the Germans were defeated before any nuclear weapon had beenmade. But I do not think that nuclear scientists of the West can be blamed for thinking the work urgent and necessary. Even Einstein favored it.When, however, the German war was finished, the great majority of those scientists who had collaborated towards making the A-bomb considered that it should not be used against the Japanese,who were already on the verge （边缘） of defeat and, in any case,did not constitute such a menace to the world as Hitler. Many of them made urgent represent ations to the American Government advocating that, instead of using the bomb as a weapon of war, they should after a public announcement, explode it in a desert, and that future control of nuclear energy should be placed in the hands of an international authority. Seven of the most eminent of nuclear scientists drew up what is known as "The Franck Report" which they presented to the Secretary of War in June 1945. This is a very admirable and far-seeing document, and if it had won the assent of the politicians, none of our subsequent terrors would have arisen.36. We may infer that the writer′s attitude towards the A bomb is that .A） it is a necessary evilB） it is a terrible threat to the whole of mankindC） it played a vital part in defeating the JapaneseD） it was a wonderful invention37. According to the passage, an atom is heavy if .A） it has a large nucleusB） it is radioactiveC） its nucleus has many electronsD） its nucleus shoots out many particles38. The American and British scientists were astonished atthe end of the Second World War against Germany because .A）the Germans had been defeated without the use of nuclear weaponsB）the Western countries had won before they had invented nuclear weaponsC） they thought the Germans would probably win the warD）the Germans had made little progress in developing nuclear weapons39. According to the writer, most scientists who had helped in making the A bomb considered that it should not be used against the Japanese because .A） it was such a dangerous weaponB） its use against the Japanese, was unnecessaryC） it was a very inhumane weaponD） the German war was finished40.It is implied that the nuclear scientists .A）might not have agreed to develop the bomb if there had been no Nazi threatB） would have developed the bomb even without the Nazi threatC）would have made the bomb, under peace time conditions, but only for the use of an international authority D）developed the bomb because Einstein thought it urgent and necessaryPart Ⅲ Vocabulary (20 minutes)Directions: There are 30 incomplete sentences in this part.For each sentence there are four choices marked A), B), C) andD). Choose the ONE answer that best completes the sentence.Then mark the corresponding letter on the Answer Sheet with asingle line through the center.41.The British Library____ the right to a free copy of everynew book published in the United Kingdom.A) contains B) retiresC) retains D) conveys42.The secretary____ the foreign minister____ an interview hewas to give that afternoon.A) reminded … ofB) reassured…aboutC) consulted…aboutD) questioned…to43. The way other people behave towards us influences howwe____ ourselves.A) conceive of B) consist of C) confront with D) conform to44. I suppose some people create an idea of who they want tobe and, they ____ it____.A) work…over B) bear…out C) live…out D) get… over45.With the economy of the country growing strong, the____mood is one of optimism .A) presiding B) circulating C) floating D) prevailing46. These technological advances in communication have____ theway people do business.A) revolted B) represented C) adopted D) transformed47. The workers of the textile mill ____ that trade unionleaders be elected from the workshops .A) urged B) related C) combated D) adapted48. It is a____ of our company to give refunds if goods arefaulty.A) policy B) discipline C) decision D) determination49. ____ friends helped him to get appointed ambassador toFrance .A) Efficient B) Influential C) Impressive D) Effective50.Their ambitious schemes for making money quickly____.A) took a chanceB) came to nothingC) went into actionD) got to the point51.She knew who wrote the letter, so without opening it shetore it into pieces____A) in excitementB) in disappointmentC) in disgustD) in expectation52.He had always been ____the way Ruth looked, and had neveronce paid her a compliment .A) oblivious to B) guilty of C) wary of D) subject to53.Familarity with a wide range of idiomatic expressions, andthe ability to use them appropriately____ are among thedistinguishing marks of command of English like a native.A) in context B) in practice C) in place D) in case54.We are still____ things here, but I can’t guarantee thesituation will stay that way.A) in memory ofB) in search ofC) in control ofD) in need of5.Democratic government is a phrase that is notoriously hardto____.A) credit B) defy C) modify D) define56.Bill is rich. His house is full of ____ such as expensivehigh-tech video systems and all the latest computerequipment.A) luxuries B) festivities C) dimensions D) instruments57.She is quite capable, but the problem is that she isnot____.A) consistent B) insistent C) beneficent D) resistant58.Based on the____ that every business is now free toformulate its own strategy in light of the changing market, I would predict a market improvement in the efficiency ofChina’s economy.A) guidance B) instruction C . premise D) eminence59.Nurses should do all they can to make their patients feel____.A .on board B) at ease C) at leisure D) at heart60.The accused was ____to have been the leader of the plot tooverthrow the government A) reconciled B) blended C) allegedD) referred61. She ____the letter, put it in the envelope and handed itto her father.A) folded B) wrapped C) rolled D) slided62. In the last century, new drugs have ____ improved healththroughout the world.A) inconsistently B) supposedly C) notedly D) markedly63. Now a paper argues that organic chemicals in the rock comemostly from ____ on earth rather than bacteria on Mars.A) configurationB) constitutionC) condemnationD) contamination64. When he went to the airport for the ticket, Tom suddenlyealized that his passport had ____ for half a year.A) abolished B) expired C) amended D) constrained65. Since the information was easily____, we found itimmediately.A) acceptable B) accessory C) accessible D) possible66.There is no known cure for SARS, but doctors are developingways to help sufferers ____ it.A) retard B) eliminate C) dispense D) handle67. She was____ her brains to remember the man’s time, but herbad memory failed her.A) hitting B) beating C) racking D) exhausting68. Many apartments have doors with a security window so thatone may____ outside and observe visitors without being seen.A) peer B) peek C) peel D) pile69. French cars are more elegantly styled than their British____.A) counterparts B) equals C) ones D) copies70. After failing his driving test four times, he finally____trying to pass.A) gave up B) gave away C) gave off D) gave inPart Ⅳ Error Correction (15 minutes）Directions: This part consists of a short passage. In this passage, there are altogether 10 mistakes, one in each numbered line. You may have to change a word, add a word or delete a word. If you change a word, cross it out write the correct word in the corresponding blank. If you add a word, put an insertion mark (∧） in the correct place and write the missing word in the blank. If you delete a word, cross it out and be sure to put slash (/) in the blank.[WTHZ]Error Correction:The first man known to use a signal other thana bonfire(大篝火)used a chandelier(枝形吊灯).He was lord of a castle that stood near a rocky seacoast..He hang the chandelier, containing many 71_________ large tallow candles ,in the highest tower of his castle .Thus he warned passing ship from the danger 72________ along the coast.Candles soon became the common fuel for signal lights.They were later replaced by oil lamps,that could burn longer and brighter. Kerosene and 73_________gas lamps also tried .These are still in use now in 74_________some smaller lighthouses. But today most lighthousessent electric light blazing out over the sea. 75_________ The ancient fire signals could only say “Danger!Keep off !”But the modern lighthouse alsoidentifies it in a code known to all shipping .Mostof 76_________the great lights have their own special signals. Thelight may be one that blinks—as a giant firefly in the 77_________night .Or it may be a revolved light that is red and 78_________then green. Or it may be only white .But however 79__________the signal ,it is sent very regularly. A ship within itsrange is never at a loss to know which lighthouse itis , and where it is being located . 80__________Part Ⅴ Writing （30 minutes）Directions: For this part, you are allowed 30 minutes to writes a composition entitled The Tears of A Bird.Your compositiom should be based on the outline below and should be no less than 150 words.(1)Describe the cartoon and deduce the purpose of the drawer of the picture;(2)State the harmful effects of the phenomenon;(3)Give suggestions as to how to solve the problem.The Tears of A Birdpart Ⅱ21. B）文章第一段点明了三种不同类型的经济体系。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
See discussions, stats, and author profiles for this publication at:https:///publication/12650757The effects of temperature and oxygen content on the PCDD/PCDFs formation in MSW fly ashArticle in Chemosphere · February 2000DOI: 10.1016/S0045-6535(99)00227-1 · Source: PubMedCITATIONS 40READS 452 authors, including:Moo Been ChangNational Central University149 PUBLICATIONS 2,691 CITATIONSSEE PROFILEAll content following this page was uploaded by Moo Been Chang on 06 April 2017.The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.The e ects of temperature and oxygen content on the PCDD/PCDFs formation in MSW ¯y ashMoo Been Chang *,Tsai Fei HuangGraduate Institute of Environmental Engineering,National Central University,Chungli 32054,Taiwan,ROCReceived 12March 1999;accepted 21May 1999AbstractIn this study,the e ects of the temperature,oxygen content in the gas stream and carbon content in ash particles on PCDD/Fs formation on the ¯y ash surface were investigated.The optimum temperatures for dioxin formation were found at 350°C for boiler ash,300°C for cyclone ash and 250°C for ESP ash,respectively.Preliminary results indicate that the optimum temperature will decrease as the particle size decreases.When the O 2concentration is varied between 0%and 100%,the optimum oxygen content for PCDD/Fs formation is found to be at 7.5%for cyclone ash,and the PCDD/PCDF ratio increases with the increase of oxygen content.Dioxin formation is observed even for the gas containing no oxygen passed through the ¯y ash.Hence,other reacted routes that do not need O 2for dioxin formation take place on ¯y ash.The carbon content in ¯y ash is varied between 0%and 20%in this study,and the results have indicated that the maximum dioxin formation is to be found at 5%.The precursors are not injected into the ¯y ash or gas stream in all formation experiments,however,dioxin is still formed in ¯y ash.Consequently,other chlorinated routes besides Deacon reactions may take place on the ¯y ash surface.Ó1999Elsevier Science Ltd.All rights reserved.Keywords:Dioxin formation;Municipal waste incinerators (MWI);Temperature;Oxygen content1.IntroductionFormation of PCDD/Fs from municipal waste in-cinerators (MWIs)and other combustion processes has been investigated and PCDD/Fs are found in the ¯y ash emitted from MWIs (Robert,1990).Previous studies indicated that ¯y ash acted as a heterogeneous catalyst and played a crucial role for the synthesis of PCDD/Fs in the MWI after the burning zone (Karasek and Dickson,1987;Goldfarb,1989;Altwicker et al.,1992).Schaub and Tsang (1983)indicated that the dioxin contents in ¯y ash are greater than that present in the incinerator input,so there are certain processes leading to dioxin formation during combustion (Schaub and Tsang,1983).In general,the dioxin formation can takeplace via two distinct routes,i.e.,from precursors or via De Novo synthesis from macromolecules.Laboratory research has successfully generated PCDDs and PCDFs through simulating combustion conditions of MWIs (Hegenmaier et al.,1987;Vogg and Stieglitz,1986).It is known that the dioxin content in-creases for ¯y ash in the downstream region of the waste combustion process.The temperature range of the downstream region is 200±400°C (Gullet and Raghu-nathan,1997).Addink et al.(1991)showed that there was a great increase in PCDD/Fs formation between 2and 4h reaction time,and it was probably due to changes in the ¯y ash surface (Addink et al.,1991).Addink and Olie (1995a,b)varied O 2content in the gas stream from 0%to 10%by volume,and the maximum formation was found at P 5%(Addink and Olie,1995a).In recent years,some studies have been con-ducted on PCDD/Fs formation to determine the e ects of relevant parameters via laboratory-scaleapparatusChemosphere 40(2000)159±164*Corresponding author.Tel.:+886-3-4226724;fax:+886-3-4221602.0045-6535/00/$-see front matter Ó1999Elsevier Science Ltd.All rights reserved.PII:S 0045-6535(99)00227-1(Altwicker and Milligan,1993;Altwicker and Konduri,1993;Addink and Olie,1995b).A series of experiments on PCDD/Fs formation with extracted MWI ¯y ash have been carried out in this study to investigate the e ects of the reaction time,temperature,oxygen content in the gas stream and carbon content of ¯y ash for PCDD/Fs formation on its surface.2.Experimental 2.1.Sample acquisitionAshes from boiler,cyclone and ESP were sampled from two MWIs equipped with di erent APCDs in northern Taiwan.Before proceeding with the dioxin formation experiment,the ¯y ash has been previously extracted with toluene to remove all PCDD/Fs.In this work,the extracted MWC ¯y ash sample is used as a reactant for dioxin formation experiment.For the ex-periment of the carbon content of ¯y ash,all organic materials in ¯y ash were previously removed by heating the ash at 550°C for 2h.The ¯y ash was then mixed with 0%,2%,5%,10%and 20%(by mass)activated carbon and the mixture of the two solids was homogenized by the shaking process.2.2.Experimental apparatusThe schematic diagram of the experimental apparatus used for dioxin formation is given in Fig.1.10g of the ¯y ash sample was placed in a quartz boat and put in the quartz tube.The quartz tube was coupled with a steel inlet tube for introduction of a gas ¯ow through the ¯y ash bed,and placed into an oven for controlling thetemperature.A constant-¯ow and composition gas stream were then introduced into the oven.The gas ¯ow was controlled by a set of mass ¯ow controllers.The gases were heated in a preheated chamber containing a spiral steel tube.Experimental procedures include 10±15min of heating to reach the near set temperature (10°C below the set temperature)without the gas ¯owing through the ¯y ash bed,then 5±10min of heating with a gas ¯owing through the ¯y ash in order to reach the set temperature ( 7°C).A ®lter and XAD-2trap were in-stalled downstream of the oven for collecting dioxin in the gas stream.Particles that escaped from the ¯y ash were collected by a ®lter.Other products passing through the ®lter were collected by the XAD-2trap.After the experiment,the ¯y ash bed was immediately taken out of the furnace and cooled to room temperature for later analysis.The reaction time is 1h and total gas ¯ow rate is controlled at 10l/min for all formation experiments.2.3.PCDD/Fs analysisIn this study,only seventeen 2,3,7,8-substituted PCDD/Fs congeners were measured.10g of the sample was spiked with known amounts of 13C isotopically la-beled internal standard solution,the sample was then extracted by re¯uxing with toluene for 24h.The tolu-ene-extract was then concentrated and subjected to a series of liquid chromatographic clean-up sequences in-cluding conc.sulfuric acid partitioning process,a basic sulfuric acid silica gel column and a combination acidic aluminum column,and celite/carbon column.The PCDD/Fs analysis was carried out with HRGC/LRMS (Hewlett Packard 5890II and 5972).A fused silica capillary column DB-5MS (60m Â0X 25mm Â0X 25l m)was used for thispurpose.Fig.1.Schematics of the experimental apparatus used for dioxin formation.160M.B.Chang,T.F.Huang /Chemosphere 40(2000)159±1643.Results and discussionIn this work,the extracted MWC¯y ash sample is used as a reactant for dioxin formation via a laboratory-scale reactor.The blank tests have been carried out in triplicate in order to check the dioxin content in ex-tracted¯y ash.The purpose of this work is to ensure that the dioxin detected is generated from¯y ash during the dioxin formation experiment,rather from the dioxin remaining in the extracted¯y ash.The results indicate that trace amounts of dioxins are still found on the ex-tracted¯y ash,but the residual dioxins in the blank experiment are only1±3%of the lowest concentration found in formation experiments.Therefore,the dioxin content in the extracted¯y ash can be neglected and it can be assumed there is no dioxin existing in the ex-tracted¯y ash which is used as the reactant for all dioxin formation experiments.In this study,the e ects of the temperature,oxygen content in the gas stream and carbon content in the ash on PCDD/Fs formation on the ¯y ash have been investigated.The e ects of these fac-tors on dioxin formation are as follows:(1)Temperature.Many publications have indicated that the optimum temperature of dioxin formation is between250°C and400°C(Addink and Olie,1995b; Boscak,1990).A series of experiments have been carried out at the temperatures of200°C,250°C,300°C,350°C and400°C.The reaction time(RT)is1h and oxygen content is controlled at10%by volume.The e ects of the temperature on the PCDD/Fs formation for ashes from cyclone and ESP are shown in Fig.2.The optimum temperature range for PCDD/Fs formation is250±300°C for cyclone and ESP ashes.The particle size in the downstream of incinerators is generally smaller than that in the upstream.It is concluded that the particle size distribution from large to small sizes is boiler ash>cy-clone ash>ESP ash.These results indicate that the op-timum temperature decreases with the decreasing particle size.The concentration of dioxin for¯y ash is ESP ash>cyclone ash.The results indicate that the di-oxin concentration will increase as the particle size de-creases and are in agreement with the previous®ndings by Chang and Chung(1998).(2)Oxygen content.Since the waste materials can be incinerated with enriched oxygen or even pure oxygen the O2content of the gas stream introduced is varied from0%to100%by volume,and the carrier gas is ni-trogen.The reaction time(RT)is1h and the tempera-ture is controlled at300°C.The e ect of the oxygen content on the PCDD/Fs formation is shown in Fig.3. The results indicate that the optimum oxygen contents for dioxin formation for cyclone ash are at7.5%and 40%,and the maximum dioxin formation is found at 7.5%.Since the optimum oxygen content was found at two reactive regions,it is concluded that the dioxin formation may take place via two di erent routes re-sulting from the di erent oxygen-needed concentrations for dioxin formation.As the temperature(300°C)is not the optimal temperature(250°C)for ESP ash,the opti-mum oxygen content has not been found for ESP ash. The PCDD/PCDFs ratio for all¯y ashes experimented is<1.In other words,the homologue patterns aremoreFig.2.The e ect of the temperature on the PCDD/Fs forma-tion(Q 10l/min,RT 1h,[O2]10%).Fig.3.The e ect of the O2content on the PCDD/Fs formation(Q 10l/min,RT 1h,T 300°C).M.B.Chang,T.F.Huang/Chemosphere40(2000)159±164161favored to the distribution of PCDF congeners than to PCDDs.Di erent ring structures and the number of oxygen atoms bonded on the ring structure may account for such homologue distributions.The characteristic of mid-ring structure of PCDD is a six-sided hexagon and bonded with two oxygen atoms,and that of PCDF is a ®ve-sided pentagon and bonded with one oxygen atom.As a result,the ring structure of PCDF is simpler and the number of oxygen atoms bonded on the ring struc-ture is less than that of PCDD,and the homologue pattern of dioxin is more favored to the distribution of PCDF congeners.(3)Comparison of nitrogen gas and oxygen gas ¯owing through the ¯y ash .Oxygen is essential for De Novo synthesis and reactions of chemically similar gas-phase precursors to PCDD/Fs.However,trace amounts of PCDD/Fs have still been found in the ¯y ash when pure N 2was passing through the ¯y ash bed in this study (Fig.4(a)±(c)).In other words,dioxin formation has been observed even for the gas stream containing no oxygen passing through the ¯y ash.In addition to De Novo synthesis,other reacted routes which do not need O 2for dioxin formation occur on ¯y ash.Nevertheless,the dioxin content of ¯y ash with passing pure O 2¯ow is higher than that with passing pure N 2stream.Addink and Olie (1995a,b)showed that O 2can give a better adsorption to the ¯y ash surface than N 2and participate both in condensation or dechlorinated/destruction re-actions (Addink and Olie,1995b).The congeners dis-tribution of dioxin is shown in Fig.4(d)±(f).The results indicated that the concentration of higher chlorinated congeners greatly decreased in the absence of oxygen leading to a decrease of PCDD/Fs concentration.The decrease is attributed to the decrease of higher chlori-nated congeners.The concentration distribution of di-oxin for ¯y ash is ESP ash >cyclone ash >boiler ash.When operating parameters are controlled the same for other set of ¯y ash,the concentration distribution of dioxin for ¯y ash is still ESP ash >cyclone ash >boiler ash.From these results,it can be concluded that the factors a ecting dioxin formation are independent of the system environmental condition,but dependent on the physical and chemical characteristics of ash particles.These factors may include the size distribution and catalytic materials retained in ¯y ash.(4)Carbon content of ¯y ash .The carbon content in ¯y ash is varied between 0%and 20%(by mass)in this study.The reaction time (RT)is 1h,the temperature is 300°C,and oxygen content is 10%by volume.The e ect of the carbon content on the PCDD/Fs formation for cyclone ash is shown in Fig.5.When the carbon content of ¯y ash is 0%,no PCDD/Fs is formed on ¯y ash.In other words,carbon is essential for dioxin formation.The maximum formation is found at 5%of carbon content,and more or less than 5%will result in the decrease of the dioxin concentration of ¯y ash.The possible reasons are:(i)With increasing carbon content in ¯y ash,the chances for forming other organiccom-Fig.4.The dioxin formation with nitrogen and oxygen ¯owing through the ¯y ash bed (Q 10l/min,RT 1h,T 300°C).162M.B.Chang,T.F.Huang /Chemosphere 40(2000)159±164pounds also increase.The chlorine-like organic com-pounds among these compounds will then compete for available chlorine species.(ii)When the carbon content in ¯y ash increases,the mass percentage of the catalyst is signi®cantly lower under ®xed weight of mixed ash (carbon/¯y ash).With such a catalyst-de®cient condi-tion,the dioxin formation is decreased.The PCDD/PCDFs ratio is still <1in this series of tests.In other words,the homologue pattern of dioxin more favored the distribution of PCDF congeners.(5)Oxygen content under ®xed carbon content in ¯y ash .The carbon content is ®xed at 2%by mass in mixed ash for this series of experiment.The O 2content is controlled at 0%,5%and 10%(by volume),and the carrier gas is N 2.The reaction time (RT)is 1h and the temperature is controlled at 300C.The e ects of the oxygen concentration on the PCDD/Fs formation for cyclone ash and ESP ash are given in Fig.6.Under anoxygen-de®cient ¯ow,PCDD/Fs are hardly formed from a carbon/¯y ash mixture.As the O 2content is increased,signi®cant amount of dioxin is formed via De Novo synthesis reactions.The dioxin content and PCDD/PCDF ratio increase with increasing O 2content for both cyclone and ESP ash.The precursors were not injected into the ¯y ash or gas stream in all the dioxin formation experiments in this study,however,dioxin is still formed in ¯y ash under all experimental conditions.Other chlorinated routes for forming chlorine must take place on the ¯y ash surface in addition to Deacon reactions.Further study is needed to identify the possible routes for formation.4.ConclusionsIn retrospect,the conclusions can be reached from the present study.The optimum temperatures of dioxin for-mation for various ¯y ashes are di erent.The optimum temperature is 300°C for cyclone ash and 250°C for ESP ash,respectively.The optimum temperature for dioxin formation tends to decrease as the particle size decreases.The optimum contents of oxygen are found at 7.5%by volume for cyclone ash,and the PCDD/PCDF ratio in-creases as O 2content increases.The results indicate that formation of PCDD that contains two oxygen atoms is a ected more signi®cantly by O 2content of the gas stream than PCDF that contains only one oxygen atom.Dioxin formation has been observed even for the carrier gas containing no oxygen passing through the ¯y ash bed.It indicates that other reaction routes which do not need O 2for dioxin formation have occurred on ¯y ash.The maximum dioxin formation has been found at 5%(car-bon content ±by mass).More or less carbon content than this range will result in the decrease of the dioxin con-centration of ¯y ash.In all experiments of this study,the concentration distribution of dioxin is ESP ash >cyclone ash >boiler ash.We concluded that the factorsa ectingFig.6.The e ect of the O 2content in the gas stream on the PCDD/Fs formation (Carbon content is 2%bymass).Fig.5.The e ect of the carbon content on the PCDD/Fs formation (Q 10l/min,RT 1h,T 300°C,[O 2] 10%).M.B.Chang,T.F.Huang /Chemosphere 40(2000)159±164163dioxin formation are independent of the system condi-tions,but dependent on the physical and chemical char-acteristics of¯y ash.These factors may include the particle size distribution and catalyst contents.The pre-cursors are not injected into the¯y ash or gas stream in all formation experiments,however,dioxin is still formed in ¯y ash.In other words,di erent chlorinated routes may exist on the¯y ash surface other than Deacon reactions.AcknowledgementsFinancial support by the National Science Council of the Republic of China under grant No.NSC-87-2211-E-008-018and NSC-88-EPA-008-002is greatly acknowl-edged.ReferencesAddink,R.,Drijver,D.J.,Olie,K.,1991.Chemosphere23, 1205±1211.Addink,R.,Olie,K.,1995a.Environ.Sci.Technol.29,1425±1435.Addink,R.,Olie,K.,1995b.Environ.Sci.Technol.29,1586±1590.Altwicker,E.R,Konduri,R.K.,bust.Sci.Technol.88,349±368.Altwicker,E.R.,Konduri,C.L.,Milligan,M.S.,1992.Chemo-sphere25,1935±1944.Altwicker,E.R.,Milligan,M.S.,1993.Chemosphere27,301±307.Boscak,V.,1990.Presented at the DioxinÕ90EPRI Seminar.Bayreuth,F.R.G..Chang,M.B.,Chung,Y.T.,1998.Chemosphere36,1959±1968. Goldfarb,T.D.,1989.Chemosphere18,1051±1055. Gullett,B.K.,Raghunathan,K.,1997.Chemosphere34,1027±1032.Hagenmaier,H.,Brunner,H.,Hagg,R.,Kraft,M.,1987.Environ.Sci.Technol.21,1080±1084.Karasek,F.W.,Dickson,L.C.,1987.Science237,754±762. Robert,V.H.,Gary,A.E.,Yao,T.L.,Margaret,C.C.,Mao, Q.L.,1990.Environ.Sci.Technol.24,1635±1641. Schaub,W.M.,Tsang,W.,1983.Environ.Sci.Technol.17, 721±727.Vogg,H.,Stieglitz,L.,1986.Chemosphere15,1373±1378.164M.B.Chang,T.F.Huang/Chemosphere40(2000)159±164 View publication stats。