Substructure of recovered Ti-23Nb-0.7Ta-2Zr-O alloy

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NMR确定鸡血藤中1个新的降倍半萜类化合物布卢门醇A-6-O-反式-对羟基肉桂酸酯

·基础研究·△［基金项目］　国家中药标准化项目（ＺＹＢＺＨＣＨＵＮ２１）［通信作者］　杨秀伟，教授，博士生导师，研究方向：中药有效物质基础和药物代谢；Ｔｅｌ：（０１０）８２８０１５６９，Ｅｍａｉｌ：ｘｗｙａｎｇ＠ｂｊｍｕｅｄｕｃｎＮＭＲ确定鸡血藤中１个新的降倍半萜类化合物布卢门醇Ａ６Ｏ反式对羟基肉桂酸酯△杨秀伟，刘晓艳，崔泽旭北京大学药学院天然药物学系／天然药物及仿生药物国家重点实验室，北京　１００１９１［摘要］　目的：研究鸡血藤水提取物中的化学成分。

方法：采用硅胶、高效液相等柱色谱方法进行分离纯化，通过化合物的核磁共振（ＮＭＲ）数据鉴定其结构。

结果：从鸡血藤水提取物中分离出１个降倍半萜类化合物，根据其ＮＭＲ数据鉴定其化学结构为布卢门醇Ａ６Ｏ反式对羟基肉桂酸酯。

结论：布卢门醇Ａ６Ｏ反式对羟基肉桂酸酯为１个新的化合物。

［关键词］　鸡血藤；豆科；降倍半萜；布卢门醇Ａ６Ｏ反式对羟基肉桂酸酯［中图分类号］　Ｒ２８４［文献标识码］　Ａ［文章编号］　１６７３４８９０（２０２１）０３０４３２０５ｄｏｉ：１０１３３１３／ｊｉｓｓｎ１６７３４８９０２０２００８２３００１ＢｌｕｍｅｎｏｌＡ６ＯｔｒａｎｓｐＨｙｄｒｏｘｙｃｉｎｎａｍａｔｅａｓａＮｅｗＮｏｒｓｅｓｑｕｉｔｅｒｐｅｎｏｉｄＤｅｔｅｒｍｉｎｅｄｂｙＮＭＲＭｅｔｈｏｄｆｒｏｍＳｐａｔｈｏｌｏｂｉＣａｕｌｉｓＹＡＮＧＸｉｕｗｅｉ，ＬＩＵＸｉａｏｙａｎ，ＣＵＩＺｅｘｕＳｔａｔｅＫｅｙＬａｂｏｒａｔｏｒｙｏｆＮａｔｕｒａｌａｎｄＢｉｏｍｉｍｅｔｉｃＤｒｕｇｓ，ＤｅｐａｒｔｍｅｎｔｏｆＮａｔｕｒａｌＭｅｄｉｃｉｎｅｓ，ＳｃｈｏｏｌｏｆＰｈａｒｍａｃｅｕｔｉｃａｌＳｃｉｅｎｃｅｓ，ＰｅｋｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ１００１９１，Ｃｈｉｎａ［Ａｂｓｔｒａｃｔ］　Ｏｂｊｅｃｔｉｖｅ：ＴｏｓｔｕｄｙｔｈｅｃｈｅｍｉｃａｌｃｏｎｓｔｉｔｕｅｎｔｓｏｆａｑｕｅｏｕｓｅｘｔｒａｃｔｏｆＳｐａｔｈｏｌｏｂｉＣａｕｌｉｓＭｅｔｈｏｄｓ：Ｔｈｅｃｏｍｐｏｕｎｄｗａｓｓｅｐａｒａｔｅｄａｎｄｐｕｒｉｆｉｅｄｂｙｒｅｐｅａｔｅｄｃｏｌｕｍｎｃｈｒｏｍａｔｏｇｒａｐｈｙｏｎｓｉｌｉｃａｇｅｌａｎｄｈｉｇｈｐｅｒｆｏｒｍａｎｃｅｌｉｑｕｉｄｃｈｒｏｍａｔｏｇｒａｐｈｙ，ａｎｄｔｈｅｃｈｅｍｉｃａｌｓｔｒｕｃｔｕｒｅｗａｓｄｅｔｅｒｍｉｎｅｄｂｙｎｕｃｌｅａｒｍａｇｎｅｔｉｃｒｅｓｏｎａｎｃｅ（ＮＭＲ）ｓｐｅｃｔｒｏｓｃｏｐｉｃｄａｔａａｎａｌｙｓｅｓＲｅｓｕｌｔｓ：ＡｎｏｒｓｅｓｑｕｉｔｅｒｐｅｎｏｉｄｃｏｍｐｏｕｎｄｗａｓｏｂｔａｉｎｅｄＩｔｓｃｈｅｍｉｃａｌｓｔｒｕｃｔｕｒｅｗａｓｉｄｅｎｔｉｆｉｅｄａｓｂｌｕｍｅｎｏｌＡ６ＯｔｒａｎｓｐｈｙｄｒｏｘｙｃｉｎｎａｍａｔｅＣｏｎｃｌｕｓｉｏｎ：ＢｌｕｍｅｎｏｌＡ６Ｏｔｒａｎｓｐｈｙｄｒｏｘｙｃｉｎｎａｍａｔｅｉｓａｎｅｗｃｏｍｐｏｕｎｄ［Ｋｅｙｗｏｒｄｓ］　ＳｐａｔｈｏｌｏｂｉＣａｕｌｉｓ；Ｌｅｇｕｍｉｎｏｓａｅ；ｎｏｒｓｅｓｑｕｉｔｅｒｐｅｎｏｉｄ；ｂｌｕｍｅｎｏｌＡ６Ｏｔｒａｎｓｐｈｙｄｒｏｘｙｃｉｎｎａｍａｔｅ鸡血藤ＳｐａｔｈｏｌｏｂｉＣａｕｌｉｓ为豆科植物密花豆ＳｐａｔｈｏｌｏｂｕｓｓｕｂｅｒｅｃｔｕｓＤｕｎｎ的干燥藤茎［１］，主产于中国云南、广西等地，在缅甸、印度尼西亚等热带地区也有分布。

微生物屏障试验 DIN 58953-6_2010 Test report

Interlaboratory T est …Microbial barrier testing of packa ging materials for medical devices which are tobe ster ili ze d“according to DIN 58953-6:2010Test re portJanuary 2013Author: Daniel ZahnISEGA Forschungs- und Untersuchungsgesellschaft mbHTest report Page 2 / 15Table of contentsSeite1.General information on the Interlaboratory Test (3)1.1 Organization (3)1.2 Occasion and Objective (3)1.3 Time Schedule (3)1.4 Participants (4)2.Sample material (4)2.1 Sample Description and Execution of the Test (4)2.1.1 Materials for the Analysis of the Germ Proofness under Humidityaccording to DIN 58953-6, section 3 (5)2.1.2 Materials for the Analysis of the Germ Proofness with Air Permeanceaccording to DIN 58953-6, section 4 (5)2.2 Sample Preparation and Despatch (5)2.3 Additional Sample and Re-examination (6)3.Results (6)3.1 Preliminary Remark (6)3.2 Note on the Record of Test Results (6)3.3 Comment on the Statistical Evaluation (6)3.4 Outlier tests (7)3.5 Record of Test Results (7)3.5.1 Record of Test Results Sample F1 (8)3.5.2 Record of Test Results Sample F2 (9)3.5.3 Record of Test Results Sample F3 (10)3.5.4 Record of Test Results Sample L1 (11)3.5.5 Record of Test Results Sample L2 (12)3.5.6 Record of Test Results Sample L3 (13)3.5.7 Record of Test Results Sample L4 (14)4.Overview and Summary (15)Test report Page 3 / 15 1. General Information on the Interlaboratory Test1.1 OrganizationOrganizer of the Interlaboratory Test:Sterile Barrier Association (SBA)Mr. David Harding (director.general@)Pennygate House, St WeonardsHerfordshire HR2 8PT / Great BritainRealization of the Interlaboratory Test:Verein zur Förderung der Forschung und Ausbildung fürFaserstoff- und Verpackungschemie e. V. (VFV)vfv@isega.dePostfach 10 11 0963707 Aschaffenburg / GermanyTechnical support:ISEGA Forschungs- u. Untersuchungsgesellschaft mbHDr. Julia Riedlinger / Mr. Daniel Zahn (info@isega.de)Zeppelinstraße 3 – 563741 Aschaffenburg / Germany1.2 Occasion and ObjectiveIn order to demonstrate compliance with the requirements of the ISO 11607-1:2006 …Packaging for terminally sterilized medical devices -- Part 1: Requirements for materials, sterile barrier systems and packaging systems“ validated test methods are to be preferably utilized.For the confirmation of the microbial barrier properties of porous materials demanded in the ISO 11607-1, the DIN 58953-6:2010 …Sterilization – Sterile supply – Part 6: Microbial barrier testing of packaging materials for medical devices which are to be sterilized“ represents a conclusive method which can be performed without the need for extensive equipment.However, since momentarily no validation data on DIN 58953-6 is at hand concerns emerged that the method may lose importance against validated methods in a revision of the ISO 11607-1 or may even not be considered at all.Within the framework of this interlaboratory test, data on the reproducibility of the results obtained by means of the analysis according to DIN 58953-6 shall be gathered.1.3 Time ScheduleSeptember 2010:The Sterile Barrier Association queried ISEGA Forschungs- und Unter-suchungsgesellschaft about the technical support for the interlaboratory test.For the realization, the Verein zur Förderung der Forschung und Ausbildungfür Faserstoff- und Verpackungschemie e. V. (VFV) was won over.November 2010: Preliminary announcement of the interlaboratory test / Seach for interested laboratoriesTest report Page 4 / 15 January toDecember 2011: Search for suitable sample material / Carrying out of numerous pre-trials on various materialsJanuary 2012:Renewed contact or search for additional interested laboratories, respectively February 2012: Sending out of registration forms / preparation of sample materialMarch 2012: Registration deadline / sample despatchMay / June 2012: Results come in / statistical evaluationJuly 2012: Despatch of samples for the re-examinationSeptember 2012: Results of the re-examination come in / statistical evaluationNovember 2012: Results are sent to the participantsDecember 2012/January 2013: Compilation of the test report1.4 ParticipantsFive different German laboratories participated in the interlaboratory test. In one laboratory, the analyses were performed by two testers working independently so that six valid results overall were received which can be taken into consideration in the evaluation.To ensure an anonymous evaluation of the results, each participant was assigned a laboratory number (laboratory 1 to laboratory 6) in random order, which was disclosed only to the laboratory in question. The complete laboratory number breakdown was known solely by the ISEGA staff supporting the proficiency test.2. Sample Material2.1 Sample Description and Execution of the TestUtmost care in the selection of suitable sample material was taken to include different materials used in the manufacture of packaging for terminally sterilized medical devices.With the help of numerous pre-trials the materials were chosen covering a wide range of results from mostly germ-proof samples to germ permeable materials.Test report Page 5 / 15 2.1.1 Materials for the Analysis of Germ Proofness under Humidity according to DIN 58953-6, section 3:The participants were advised to perform the analysis on the samples according to DIN 58953-6, section 3, and to protocol their findings on the provided result sheets.The only deviation from the norm was that in case of the growth of 1 -5 colony-forming units (in the following abbreviated as CFU) per sample, no re-examination 20 test pieces was performed.2.1.2 Materials for the Analysis of Germ Proofness with Air Permeance according to DIN 58953-6, section 4:The participants were advised to perform the analysis on the samples according to DIN 58953-6, section 4, and to protocol their findings on the provided result sheets.2.2 Sample Preparation and DespatchFor the analysis of the germ proofness under humidity, 10 test pieces in the size of 50 x 50 mm were cut out of each sample and heat-sealed into a sterilization pouch with the side to be tested up.Out of the 10 test pieces, 5 were intended for the testing and one each for the two controls according to DIN 58953-6, sections 3.6.2 and 3.6.3. The rest should remain as replacements (e.g. in case of the dropping of a test piece on the floor etc.).For the analysis of the germ proofness with air permeance, 15 circular test pieces with a diameter of 40 mm were punched out of each sample and heat-sealed into a sterilization pouch with the side to be tested up.Test report Page 6 / 15 Out of the 15 test pieces, 10 were intended for the testing and one each for the two controls according to DIN 58953-6, section 4.9. The rest should remain as replacements (e.g. in case of the dropping of a test piece on the floor etc.).The sterilization pouches with the test pieces were steam-sterilized in an autoclave for 15 minutes at 121 °C and stored in an climatic room at 23 °C and 50 % relative humidity until despatch.2.3 Additional Sample and Re-examinationFor the analysis of the germ proofness under humidity another test round was performed in July / August 2012. For this, an additional sample (sample L4) was sent to the laboratories and analysed (see 2.1.2). The results were considered in the evaluation.For validation or confirmation of non-plausible results, occasional samples for re-examination were sent out to the laboratories. The results of these re-examinations (July / August 2012) were not taken into consideration in the evaluation.3. Results3.1 Preliminary RemarkSince the analysis of germ proofness is designed to be a pass / fail – test, the statistical values and precision data were meant only to serve informative purposes.The evaluation of the materials according to DIN58953-6,sections 3.7and 4.7.6by the laboratories should be the most decisive criterion for the evaluation of reproducibility of the interlaboratory test results. Based on this, the classification of a sample as “sufficiently germ-proof” or “not sufficiently germ-proof” is carried out.3.2 Note on the Record of Test Results:The exact counting of individual CFUs is not possible with the required precision if the values turn out to be very high. Thus, an upper limit of 100 CFU per agar plate or per test pieces, respectively, was defined. Individual values above this limit and values which were stated with “> 100” by the laboratories, are listed as 100 CFU per agar plate or per test piece, respectively, in the evaluation.Test report Page 7 / 153.3 Comment on the Statistical EvaluationThe statistical evaluation was done based on the series of standards DIN ISO 5725-1ff.The arithmetic laboratory mean X i and the laboratory standard deviation s i were calculated from the individual measurement values obtained by the laboratories.The overall mean X of the laboratory means as well as the precision data of the method (reproducibility and repeatability) were determined for each sample3.4 Outlier testsThe Mandel's h-statistics test was utilised as outlier test for differences between the laboratory means of the participants.A laboratory was identified as a “statistical outlier” as soon as an exceedance of Mandel's h test statistic at the 1 % significance level was detected.The respective results of the laboratories identified as outliers were not considered in the statistical evaluation.3.5 Record of Test ResultsOn the following pages, the records of the test results for each interlaboratory test sample with the statistical evaluation and the evaluation according to DIN 58953-6 are compiled.Test report Page 8 / 153.5.1 Record of Test Results Sample F1Individual Measurement values:Statistical Evaluation:Comment:Laboratory 4, as an outlier, has not been taken into consideration in the statistical Evaluation.Outlier criterion: Mandel's h-statistics (1 % level of significance)Overall mean X:91.0CFU / agar plateRepeatability standard deviation s r:17.9CFU / agar plateReproducibility standard deviation s R:19.8CFU / agar plateRepeatability r:50.0CFU / agar plateRepeatability coefficient of variation:19.6%Reproducibility R:55.5CFU / agar plateReproducibility coefficient of variation:21.8%Evaluation according to DIN 58953-6, Section 3.7:Lab. 1 - 6:Number of CFU > 5, i.e. the material is classified as not sufficiently germ-proof.Conclusion:All of the participants, even the Laboratory 4 which was identified as an outlier, came to the same results and would classify the sample material as “not sufficiently germ-proof”Test report Page 9 / 153.5.2 Record of Test Results Sample F2Individual Measurement values:Statistical Evaluation:Comment:Laboratory 4, as an outlier, has not been taken into consideration in the statistical Evaluation.Outlier criterion: Mandel's h-statistics (1 % level of significance)Overall mean X:0CFU / agar plateRepeatability standard deviation s r:0CFU / agar plateReproducibility standard deviation s R:0CFU / agar plateRepeatability r:0CFU / agar plateRepeatability coefficient of variation:0%Reproducibility R:0CFU / agar plateReproducibility coefficient of variation:0%Evaluation according to DIN 58953-6, Section 3.7:Lab. 1 – 3:Number of CFU = 0, i.e. the material is classified as sufficiently germ-proofLab. 4:Number of CFU ≤ 5, i.e. a re-examination on 20 test pieces would have to be done Lab. 5 – 6:Number of CFU = 0, i.e. the material is classified as sufficiently germ-proofConclusion:All of the participants, except for the Laboratory 4 which was identified as an outlier, came to the same results and would classify the sample material as “sufficiently germ-proof”.Test report Page 10 / 153.5.3 Record of Test Results Sample F3Individual Measurement values:Statistical Evaluation:Overall mean X:30.1CFU / agar plateRepeatability standard deviation s r:17.2CFU / agar plateReproducibility standard deviation s R:30.9CFU / agar plateRepeatability r:48.2CFU / agar plateRepeatability coefficient of variation:57.1%Reproducibility R:86.5CFU / agar plateReproducibility coefficient of variation:103%Evaluation according to DIN 58953-6, Section 3.7:Lab. 1 - 4:Number of CFU > 5, i.e. the material is classified as not sufficiently germ-proof. Lab. 5:Number of CFU = 0, i.e. the material is classified as sufficiently germ-proof. Lab. 6:Number of CFU > 5, i.e. the material is classified as not sufficiently germ-proof.Conclusion:Five of the six participants came to the same result and would classify the sample as “not sufficiently germ-proof”. Only laboratory 5 would classify the sample material as “sufficiently germ-proof”.Test report Page 11 / 153.5.4 Record of Test Results Sample L1Individual Measurement values:Statistical Evaluation:Overall mean X:0.09CFU / test pieceRepeatability standard deviation s r:0.32CFU / test pieceReproducibility standard deviation s R:0.33CFU / test pieceRepeatability r:0.91CFU / test pieceRepeatability coefficient of variation:357%Reproducibility R:0.93CFU / test pieceReproducibility coefficient of variation:366%Evaluation according to DIN 58953-6, Section 4.7:Lab. 1 - 6:Number of CFU < 15, i.e. the material is classified as sufficiently germ-proof.Conclusion:All participants came to the same result and would classify the sample as “sufficiently germ-proof”.Test report Page 12 / 153.5.5 Record of Test Results Sample L2Individual Measurement values:Statistical Evaluation:Overall mean X:0.73CFU / test pieceRepeatability standard deviation s r: 1.10CFU / test pieceReproducibility standard deviation s R: 1.18CFU / test pieceRepeatability r: 3.07CFU / test pieceRepeatability coefficient of variation:151%Reproducibility R: 3.32CFU / test pieceReproducibility coefficient of variation:163%Evaluation according to DIN 58953-6, Section 4.7:Lab. 1:Number of CFU > 15, i.e. the material is classified as not sufficiently germ-proof. Lab. 2 - 6:Number of CFU < 15, i.e. the material is classified as sufficiently germ-proof.Conclusion:Five of the six participants came to the same result and would classify the sample as “sufficiently germ-proof”. Only laboratory 1 exceeds the limit value slightly by 1 CFU, so that the sample would be classified as “not sufficiently germ-proof”.Test report Page 13 / 153.5.6 Record of Test Results Sample L3Individual Measurement values:Statistical Evaluation:Overall mean X:0.36CFU / test pieceRepeatability standard deviation s r: 1.00CFU / test pieceReproducibility standard deviation s R: 1.06CFU / test pieceRepeatability r: 2.79CFU / test pieceRepeatability coefficient of variation:274%Reproducibility R: 2.98CFU / test pieceReproducibility coefficient of variation:293%Evaluation according to DIN 58953-6, Section 4.7:Lab. 1 - 6:Number of CFU < 15, i.e. the material is classified as sufficiently germ-proof.Conclusion:All participants came to the same result and would classify the sample as “sufficiently germ-proof”.Test report Page 14 / 153.5.7 Record of Test Results Sample L4Individual Measurement values:Statistical Evaluation:Overall mean X:35.1CFU / test pieceRepeatability standard deviation s r:18.8CFU / test pieceReproducibility standard deviation s R:42.6CFU / test pieceRepeatability r:52.7CFU / test pieceRepeatability coefficient of variation:53.7%Reproducibility R:119CFU / test pieceReproducibility coefficient of variation:122%Evaluation according to DIN 58953-6, Section 4.7:Lab. 1 - 3:Number of CFU > 15, i.e. the material is classified as not sufficiently germ-proof. Lab. 4:Number of CFU < 15, i.e. the material is classified as sufficiently germ-proof. Lab. 5 - 6:Number of CFU > 15, i.e. the material is classified as not sufficiently germ-proof.Conclusion:Five of the six participants came to the same result and would classify the sample as“not sufficiently germ-proof”.Test report Page 15 / 15 4. Overview and SummarySummary:In case of four of the overall seven tested materials, a 100 % consensus was reached regarding the evaluation as“sufficiently germ-proof”and“not sufficiently germ-proof”according to DIN 58 953-6.As for the other three tested materials, there were always 5 concurrent participants out of 6 (83 %). In each case, only one laboratory would have evaluated the sample differently.It is noteworthy that the materials about the evaluation of which a 100 % consensus was reached were the smooth sterilization papers. The differences with one deviating laboratory each occurred with the slightly less homogeneous materials, such as with the creped paper and the nonwoven materials.。

聚对二氧环己酮纤维——一种理想的胸外科修补材料

维普资讯
专题综述
聚合物［３１。ＰＳ的化学结构式为：Ｄ
－｛一（Ｈ —０— ｃＨ一ｃ＿Ｏｃ）０
碳细胞培养箱；日本电子光学公司的ＪＭ一６０Ｖ扫描电子显Ｓ５０Ｌ微镜；
由于原纤内各部分分子排列的密度和取向度不同造成水分子扩散难易程度不同pds降解要经历不同阶段在水解初期由于水分子最先进入结构松散的无定形区从而使得无定形区内大分子链的缠结度降低水解断链形成的缚结分子链段本身成为自由状态柔性分子链段在体外降解温度下37高于聚合物t易形成新的折叠链有序区限制水分子的渗入
＝＝ｔ曼一
文章编号：ｌｏ一０４（Ｏ）ｌ０２－３０ｌ７５２６００８０－－０
０引言
近年来，随着高分子生物材料和生物工程的
迅速发展，出现了人工合成可降解高分子材料。这
些材料不但具有特殊的生物活性和良好的生物相容性，而且由于能在机体生理环境下，通过水解、酶
解时间为ｉｏｄ８ ’得到了在这期间的质量降解曲线和强力降解曲线。最后证明了ＰＳ纤维韧性好，抗冲Ｄ
≯
击性强和降解时间长，是理想的胸外芹修补材料。＋ｌ关键词：胸外乖修辛材料；可降解高分子材料；Ｄｌ卜ＰＳ中图分类号．４蠹１２ｊ文献标识码Ａ
℃恒温二氧化碳细胞培养箱中；（２）取０周样为未降解样，作为参照物，按浸泡
时间分别为４、１、１、８２６、２、２０４Ｗ分别取出试样；（用滤纸除去取出试样表面水分，然后将该３）试样在４０℃恒温干燥４到恒重，再称重，计算８ｈ质量保持率；（）用纱线强力仪测试ＰＳ单丝强力，计算４Ｄ强力保持率；

热分解含氨草酸钴复盐制备纤维状多孔钴粉

热分解含氨草酸钴复盐制备纤维状多孔钴粉湛菁;周涤非;张传福;贺跃辉;岳建峰【摘要】以氨为配位剂,通过配位沉淀法制备纤维状钴粉复杂前驱体,并采用XRD,IR,SEM和TGA/DTA研究前驱体粉末的物相、成分与形貌,系统考察前驱体粉末热分解过程中热分解条件如热分解气氛、热分解温度、热分解时间和升温速率对金属钻粉形貌、粒度和比表面积的影响.研究结果表明:在Co(Ⅱ)-C2042——NH3-NH4+-H2O反应体系中得到的前驱体为含氨草酸钴复盐,形貌为纤维状,氨与钴离子配合并生成含氨草酸钴复盐是纤维状形貌形成的内在机制,它是通过含NH3基配合物以链状结构连接[(NH3)M-OX-M(NH3)]2+生长基元以轴向取向连生形成一维形貌;在弱还原性气氛、热分解时间为30～60 min、升温速率为15～20K/min、热分解温度为623～723 K条件下,热分解含氨草酸钴复盐粉末可以制备比表面积为10.44 m2·g-1的纤维状多孔金属钴粉,其孔结构为两端开放的管状毛细孔且多为中孔.%A novel precursor of fibrous cobalt powders was synthesized by coordination-precipitation process using ammonia as complex agent. The phase, composition and morphology of the novel precursor were characterized by XRD,IR, DTA/TGA and SEM analysis. The influences of various conditions in pyrolysis, such as decomposition atmosphere,decomposition temperature, decomposition time and heating rate, on the morphology, average size and specific surface area of the cobalt powders were investigated. The results show that the precursors obtained in reaction system Co(Ⅱ )-C2O42--NH3-NH4+-H2O is ammoniacal complex of cobalt oxalate and the morphology is fibrous. The formation of the complex of oxalate cobalt with ammonia precipitated bycoordination of ammonia and cobalt reacting with oxalate is quite essential to form fibrous morphology for the precursor, which may be formed through [(NH3)M-OX-M(NH3)] 2+growth units along the axial direction. The fibrous cobalt powders with 10.44 m2·g-1 for specific surface area are produced in weak reducing atmosphere, 623-723 K for decomposition temperature, 30-60 min for decomposition time, 15-20K/min of heating rate. The structure of pores in cobalt powders is capillary tube with open ports and the majority is mesoporous.【期刊名称】《中南大学学报（自然科学版）》【年(卷),期】2011(042)004【总页数】8页(P876-883)【关键词】含氨草酸钴复盐;钴粉;纤维状;多孔;生长机理【作者】湛菁;周涤非;张传福;贺跃辉;岳建峰【作者单位】中南大学冶金科学与工程学院,湖南长沙,410083;中南大学粉末冶金研究院,湖南长沙,410083;中南大学冶金科学与工程学院,湖南长沙,410083;中南大学冶金科学与工程学院,湖南长沙,410083;中南大学粉末冶金研究院,湖南长沙,410083;中南大学冶金科学与工程学院,湖南长沙,410083【正文语种】中文【中图分类】TF123.23超细钴粉由于其具有特殊的物理、化学性能，在硬质合金、电池、催化剂、磁性材料、吸波材料、陶瓷等领域应用中表现出许多优异性能[1-5]。

Invitrogen TrueCut Cas9 Proteins 说明书

For Research Use Only. Not for use in diagnostic procedures.TrueCut ™ Cas9 ProteinsCatalog Nos.A36496, A36497, A36498, A36499, A50574, A50575, A50576, A50577WARNING! Read the Safety Data Sheets (SDSs) and follow the handling instructions. Wear appropriate protective eyewear, clothing, and gloves. Safety Data Sheets (SDSs) are available from thermoﬁ/support .Product descriptionInvitrogen ™ TrueCut ™ Cas9 Proteins are used for genome editing applications with CRISPR technology. Cas9 protein forms a very stable ribonucleoprotein (RNP) complex with the guide RNA (gRNA) component of the CRISPR-Cas9 system. Incorporation of nuclear localization signals (NLS) aid its delivery to the nucleus, increasing the rate of genomic DNA cleavage. It is cleared rapidly, minimizing the chance for off-target cleavage when compared to plasmid systems (Liang et al ., 2015). The Cas9 nuclease hasbeen tested in a wide variety of suspension and adherent cell lines and has shown superior genomic cleavage efficiencies and cell survivability compared to plasmid-based CRISPR systems.Two types of TrueCut ™ Cas9 Proteins are available for selection, depending upon the requirements of your particular experiment:• TrueCut ™ Cas9 Protein v2 is a recombinant Streptococcus pyogenes Cas9 (wt) protein that is the preferred choice for most CRISPR genome editing procedures where the highest level of editing efficiency is required. • TrueCut ™ HiFi Cas9 Protein is an engineered high fidelity Cas9 protein which is ideal for experiments that are sensitive to off-target events, while still maintaining a high level of editing efficiency.Table 1.Contents and storagePub. No. MAN0017066Rev.D.0Storage and handling• Store TrueCut ™ Cas9 Protein v2 and TrueCut ™ HiFi Cas9 Protein at –20°C until required for use. • Maintain RNAse-free conditions by using RNAse-free reagents, tubes, and barrier pipette tips while setting up your experiments.Before you beginMaterials required but notprovided• TrueGuide™ Synthetic gRNAs (see /trueguide)orGeneArt™ Precision gRNA Synthesis Kit (Cat. No. A29377)• Lipofectamine™ CRISPRMAX™ Cas9 Transfection Kit (Cat. Nos. CMAX00001,CMAX00003, CMAX00008, CMAX00015, CMAX00030) (for most cell lines)orNeon™ Transfection System (Cat. Nos. MPK5000, MPK1025, MPK1096) (for highesttransfection efficiency in challenging cell types including suspension cell lines)• GeneArt™ Genomic Cleavage Detection Kit (Cat. No. A24372)• Opti-MEM™ I Reduced Serum Medium (Cat. No. 31985-062)• 1X TE buffer, pH 8.0 (Cat. No. AM9849) and nuclease-free water (Cat. No. AM9914G)Prepare working stock ofTrueGuide™ Synthetic gRNA If TrueGuide™ Synthetic gRNA is being used, resuspend the gRNA (sgRNA, crRNA, ortracrRNA) in1X TE buffer to prepare 100 μM (100 pmol/μL) stock solutions.Before opening, centrifuge each TrueGuide™ Synthetic gRNA tube at low speed (maximum1.RCF 4,000 × g) to collect the contents at the bottom of the tube, then remove the cap from thetube carefully.Using a pipette and sterile tips, add the required volume of 1X TE buffer to prepare 100 μM2.(100 pmol/μL) stock solutions.3.Vortex the tube to resuspend the oligos, briefly centrifuge to collect the contents at thebottom of the tube, then incubate at room temperature for 15–30 minutes to allow the gRNAoligos to dissolve.Vortex the tube again to ensure that all the contents of the tube are resuspended, then briefly4.centrifuge to collect the contents at the bottom of the tube.(Optional) Check the concentration of the resuspended oligos using the NanoDrop™5.Spectrophotometer (or equivalent) or a UV-base plate reader.6.(Optional) Aliquot the working stock into one or more tubes for storage.Use working stocks immediately or freeze at –20°C until needed for use.7.(Optional) Generate gRNA byin vitro transcription If using in vitro transcribed gRNA with TrueCut™ Cas9 Protein v2 or TrueCut™ HiFi Cas9Protein in CRISPR-Cas9-mediated genome editing, the GeneArt™ Precision gRNA SynthesisKit is recommended for preparation of the gRNA. For detailed instructions on how togenerate full length gRNA, see the GeneArt™ Precision gRNA Synthesis Kit User Guide (Pub.No. MAN0014538), at .Transfection guidelinesGeneral CRISPR/gRNAtransfection guidelines• The efficiency with which mammalian cells are transfected with gRNA varies accordingto cell type and the transfection reagent used. See Table 2 (page 3) for delivery reagentrecommendations.• For gene editing (including gene knockout) editing efficiency is highest with a 1:1 molarratio of gRNA to TrueCut™ Cas9 Protein v2 or TrueCut™ HiFi Cas9 Protein. In some celltypes such as iPSC and THP1, we have used up to 2 μg TrueCut™ Cas9 Protein v2 and400 ng gRNA per well in 24-well format.• For HDR knock-in editing, a 1.5:1 molar ratio of donor ssODN to gRNA or TrueCut™ Cas9Protein v2 or TrueCut™ HiFi Cas9 Protein is recommend for highest knock-in efficiency.The donor can be added directly to RNPs (a premixed gRNA-Cas9 protein). If using adsDNA donor, further optimization may be necessary to determine the appropriate donoramount, since the toxicity level is dependent on the length and format of the donor DNAand cell type.• The optimal cell density for transfection varies depending on cell size and growthcharacteristics. In general, use cells at 30–70% confluence on the day of transfectionwith lipid-mediated delivery, or 70–90% confluence for electroporation using the Neon™Transfection System.• After the optimal cell number and dosage of Cas9/gRNA and/or donor that providesmaximal gene editing efficiency is determined for a given cell type, do not varyconditions across experiments to ensure consistency.For an overview of the factors that influence transfection efficiency, see the “TransfectionBasics” chapter of the Gibco™ Cell Culture Basic Handbook, available at /cellculturebasics.• Use the TrueGuide™ Positive Controls (human AVVS1, CDK4, HPRT1, or mouse Rosa 26)and negative control gRNA (non-coding) to determine gRNA amount and transfectionconditions that give the optimal gene editing efficiency with highest cell viability. TheTrueGuide™ Positive and Negative sgRNA and crRNA Controls are available separatelyfrom Thermo Fisher Scientific. For more information, refer to /trueguide.• The cell number and other recommendations provided in the following proceduresare starting point guidelines based on the cell types we have tested. For multiplewells, prepare a master mix of components to minimize pipetting error, then dispense theappropriate volumes into each reaction well. When making a master mix for replicate wells,we recommend preparing extra volume to account for any pipetting variations.Recommended deliveryoptions• Choosing the right delivery reagent is critical for transfection and gene editing efficiency.See our recommendations in Table 2. For more information on transfection reagents, see/transfection.• For cell line specific transfection conditions using the Lipofectamine™ CRISPRMAX™Transfection Reagent or the Neon™ Transfection System, see the Appendix (page 13).• For best results, perform electroporation and transfection of cells using both TrueCut™Cas9 Proteins and TrueGuide™ Synthetic gRNA.HiFi Cas9 Protein.Table 2. Recommended delivery options for TrueCut™ Cas9 Protein v2 and TrueCut™Guidelines for verification of editing efficiencyVerification of gene editingefficiency• Before proceeding with downstream applications, verify the gene editing efficiency of thecontrol target and select the condition that shows the highest level of editing efficiency forfuture screening experiments.• To estimate the CRISPR-Cas9-mediated editing efficiency in a pooled cell population,use the GeneArt™ Genomic Cleavage Detection Kit (Cat. No. A24372), or performIon Torrent™ next generation sequencing or a Sanger sequencing-based analysis.• While the genomic cleavage detection (GCD) assay provides a rapid method forevaluating the efficiency of indel formation following an editing experiment, nextgeneration sequencing (NGS) of the amplicons from the edited population or Sangersequencing of amplicons cloned into plasmids give a more accurate estimate of thepercent editing efficiency and indel types for knockout and HDR knock-in editing.GeneArt™ Genomic CleavageDetection (GCD) Assay• After transfections, use the GeneArt™ Genomic Cleavage Detection Kit (Cat. No. A24372)to estimate the CRISPR-Cas9-mediated cleavage efficiency in a pooled cell population.• You can design and order target-specific primer sets for the GCD assay through ourTrueDesign Genome Editor, available at /crisprdesign.• To perform the GCD assay for the positive control, you need the primers listed in Table 3.We recommend using Invitrogen™ Custom DNA Value or Standard Oligos, available from/oligos, for target specific primer sets needed for the GCD assay.• You can set up the GCD assay in a 96-well plate format and analyze multiple gRNA-treated samples in parallel on a 2% E-Gel™ 48 agarose gel (48-well).• For more information and detailed protocols, see the GeneArt™ Genomic Cleavage DetectionKit User Guide (Pub. No. MAN0009849), available for download at /GCDManual.Table 3. Target sequences for the positive and negative control (non-targeting) TrueGuide™ Synthetic gRNA sequences.Guidelines for clone isolation and validationAfter you have determined the cleavage efficiency of the pooled cell population, isolate single cell clones for further validation and banking. You can isolate single cell clones from the selected pool using limiting dilution cloning (LDC) in 96-well plates or by single cell sorting using a flow cytometer.Limiting dilution cloning(LDC)• Based on the editing efficiency and estimated cell viability, you can estimate the number of single clones needed to obtain a desired knock-out (KO) clonal cell line. For example, if you desire a homozygous KO with mutations in both copies of a gene and the resulting GeneArt ™ cleavage detection efficiency was 50%, then the probability of having both alleles knocked out in any cell is 25% (0.5 × 0.5 = 0.25).If the probability of an indel leading to frame shift is 2/3, then the chance of having a homozygous KO is ~11% per cell [(0.5 × 0.5) × (0.66 × 0.66) = 0.11].• We recommend performing limiting dilution by targeting 0.8 cells/well, which requires you to resuspend the transfected cells (post-counting) at a density of8 cells/mL in complete growth medium, then transferring 100 µL of this to each well of a 96-well plate. If you plate at least ten 96-well plates in this manner and expect only 20% of cells tosurvive, then the probability of having homozygous KO clones in the 192 surviving cells will be 19–21 cells (192 × 11%).• Note that single cell clone survivability varies by cell type. Some cells that do not like to remain as single cells need to be plated at a low density to get well separated colonies, which will then have to be manually picked for further screening.Example LDC procedureusing 293FT cells1. Wash the transfected cells in each well of the 24-well plate with 500 µL of PBS. Carefully aspirate the PBS and discard.2. Add 500 µL of TrypLE ™ cell dissociation reagent to the cells and incubate for2–5 minutes at 37°C.3. Add 500 µL of complete growth medium to the cells to neutralize the dissociation reagent.Pipette the cells up and down several times to break up the cell aggregates. Make sure that the cells are well separated and are not clumped together. 4. Centrifuge the cells at 300 × g for 5 minutes to pellet.5. Aspirate the supernatant, resuspend the cells in an appropriate volume of pre-warmed(37°C) growth medium, then perform a cell count. 6. Dilute the cells to a density of 8 cells/mL of complete growth medium. Prepare a total ofSequence analysis• For next generation sequencing (NGS) based editing efficiency analysis, you canspecifically amplify the edited region and barcode amplicons by pooling all amplicons in a single tube and performing sequencing using various NGS platforms such as the Ion Torrent ™ Targeted Amplicon-seq Validation (TAV). For more information on NGS analysis, refer to Ion Torrent ™ targeted sequencing solutions at /ionapliseqsolutions .• For Sanger sequencing-based editing efficiency analysis, refer to our application note referenced at /sangercrispr .• Use the SeqScreener Gene Edit Confirmation App on Thermo Fisher ™ Connect todetermine the spectrum and frequency of targeted mutations (see Pub. No. MAN0019454 at . for details).50 mL of cell suspension at this cell density and transfer to a sterile reservoir.Note: You can also perform a serial dilution to get a better estimate of cell density.Using a multichannel pipettor, transfer 100 µL of the cell suspension into each well of 96-well7.tissue culture plates until the desired number of plates is seeded. Make sure to mix the cellsin between seeding the plates to avoid the formation of cell aggregates.Note: In general, we seed ten 96-well plates to achieve a large number of clones. Numberof plates to seed depends on the editing efficiency of pooled cell population and viability ofcells post single cell isolation.Incubate the plates in a 37°C, 5% CO2 incubator.8.Scan the plates for single cell colonies as soon as small aggregates of cells are visible under a9.4X microscope (usually after first week, depending on the growth rate of the cell line).Continue incubating the plates for an additional 2–3 weeks to expand the clonal populations10.for further analysis and characterization.Example single cell sortingprocedure in a 96-well plateusing flow cytometer Single cells can be sorted into a 96-well plate format using a flow cytometer with singlecell sorting capability. After sorting and expanding the single cell clones, analyze andcharacterize the clonal populations using suitable assays.1.Wash the transfected 293FT cells in each well of the 24-well plate with 500 µL of PBS.Carefully aspirate the PBS and discard.Add 500 µL of TrypLE™ cell dissociation reagent and incubate for 2–5 minutes at 37°C.2.Add 500 µL of complete growth medium to the cells to neutralize the dissociation reagent.3.Pipette the cells up and down several times to break up the cell aggregates. Make sure thatthe cells are well separated and are not clumped together.Centrifuge the cells at 300 × g for 5 minutes to pellet.4.5.Aspirate the supernatant, then wash the cell pellet once with 500 μL of PBS.Resuspend 1 × 106 cells in 1 mL of FACS buffer, then add propidium iodide (PI) to the cells at6.a final concentration of 1 µg/mL. Keep the resuspended cells on ice.Filter the cells using suitable filters before analyzing them on a flow cytometer with single7.cell sorting capability.Sort PI-negative cells into a 96-well plate containing 100 μL of complete growth medium. If8.desired, you can use 1X antibiotics with the complete growth medium.Incubate the plates in a 37°C, 5% CO2 incubator.9.Scan the plates for single cell colonies as soon as small aggregates of cells are visible under10.a 4X microscope. Colonies should be large enough to see as soon as 7–14 days (usually afterfirst week, depending on the growth rate of the cell line). You can perform image analysis toensure that the colonies are derived from single cells.11.After image analysis, continue incubating the plates for an additional 2–3 weeks to expandthe clonal populations for further analysis and characterization.Characterize edited clones You can analyze the single cell clones for purity and the desired genotype (homozygous orheterozygous allele) by various molecular biology methods such as genotyping PCR, qPCR,next generation sequencing, or western blotting.Supporting tools At Thermo Fisher Scientific, you can find a wide variety of tools to meet your gene editingand validation needs, including Invitrogen™ LentiArray CRISPR and Silencer™ Select RNAilibraries for screening, primers for targeted amplicon sequencing, antibody collection forknock-out validation, and ORF collections and GeneArt™ gene synthesis service for cDNAexpression clones that can be used for rescue experiment reagents.thermofisher .com/support | thermofisher .com/askaquestion thermofisher .comLimited product warrantyLife Technologies Corporation and/or its affiliate(s) warrant their products as set forth in the Life Technologies’ General Terms and Conditions of Sale found on Life Technologies’ website at /us/en/home/global/terms-and-conditions.html . If you have any questions, please contact Life Technologies at www /support .Manufacturer: Thermo Fisher Scientific Baltics UAB | V. A. Graiciuno 8 | LT-02241 Vilnius, LithuaniaThe information in this guide is subject to change without notice.DISCLAIMER: TO THE EXTENT ALLOWED BY LAW, LIFE TECHNOLOGIES AND/OR ITS AFFILIATE(S) WILL NOT BE LIABLE FOR SPECIAL, INCIDENTAL, INDIRECT, PUNITIVE, MULTIPLE OR CONSEQUENTIAL DAMAGES IN CONNECTION WITH OR ARISING FROM THIS DOCUMENT, INCLUDING YOUR USE OF IT.Revision history:Pub. No. MAN0017066Important Licensing Information: These products may be covered by one or more Limited Use Label Licenses. By use of these products, you accept the terms and conditions of all applicable Limited Use Label Licenses.©2021 Thermo Fisher Scientific Inc. All rights reserved. All trademarks are the property of Thermo Fisher Scientific and its subsidiaries unless otherwise specified .。

硒化甜玉米芯多糖对非酶糖基化的抑制作用

王鑫，周卓，王峙力，等. 硒化甜玉米芯多糖对非酶糖基化的抑制作用[J]. 食品工业科技，2023，44（19）：17−23. doi:10.13386/j.issn1002-0306.2022100014WANG Xin, ZHOU Zhuo, WANG Zhili, et al. Inhibitory Effect of Selenium Sweet Corncob Polysaccharide on Non-Enzymatic Glycosylation[J]. Science and Technology of Food Industry, 2023, 44(19): 17−23. (in Chinese with English abstract). doi:10.13386/j.issn1002-0306.2022100014· 研究与探讨 ·硒化甜玉米芯多糖对非酶糖基化的抑制作用王　鑫，周　卓，王峙力，修伟业，罗　钰，马永强*（黑龙江省谷物食品与谷物资源重点实验室/哈尔滨商业大学食品工程学院，黑龙江哈尔滨 150028）摘　要：以甜玉米芯多糖（SCP ）为原料采用咪唑介导法合成一种硒含量为（7.19±0.067）mg/g 的硒化多糖（Se-SCP ），为探究Se-SCP 对非酶糖基化反应的抑制作用，本文选用了果糖、牛血清白蛋白（bovine serum albumin ，BSA ）为底物，建立清白蛋白/果糖模拟体系。

对非酶糖基化过程中的前、中、末期三个特征产物果糖胺→α-二羰基化合物→非酶糖基化终产物（AGEs ）进行测定并通过透射电子显微镜（TEM ）和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulfate-polyacrylamide gel electrophoresis ，SDS-PAGE ）在微观结构方面对比分析原多糖、硒多糖对非酶糖基化进程的影响。

甘蔗液泡膜二羧酸转运蛋白基因ScTDT克隆与表达分析

甘蔗液泡膜二羧酸转运蛋白基因ScTDT克隆与表达分析作者：冯小艳王俊刚赵婷婷彭李顺王文治冯翠莲沈林波张树珍来源：《南方农业学报》2021年第02期摘要：【目的】克隆甘蔗液泡膜二羧酸转运蛋白基因（ScTDT），并分析其在甘蔗不同组织及在铝胁迫下的表达模式，为深入研究该基因功能及抵抗铝胁迫的分子机制提供理论依据。

【方法】利用同源克隆技术从甘蔗品种ROC22中克隆ScTDT基因，利用生物信息学软件进行序列分析，采用实时荧光定量PCR技术检测该基因在甘蔗不同组织（根、茎和叶）及在铝胁迫（0、10和20 μmol/L Al3+）下的表达水平。

【结果】克隆获得的ScTDT基因，开放阅读框（ORF）全长1623 bp，编码540个氨基酸残基，蛋白相对分子量57.34 kD，理论等电点（pI）5.77，为不稳定的疏水蛋白，可能定位于质膜、液泡和/或高尔基体，其氨基酸序列与高粱（XP_002460443.1）、水稻（XP_015612609.1）和玉米（PWZ04635.1）的TDT氨基酸序列具有高度相似性，其中与高粱的TDT氨基酸序列相似性最高，达96.30%，说明ScTDT与高粱TDT的亲缘关系最近。

ScTDT基因在甘蔗根、茎和叶中均有表达，但根中表达量显著高于茎和叶（P<0.05，下同）。

在铝胁迫处理下，3个甘蔗品种（ROC22、柳城05-136和中糖1202）的根中ScTDT基因表达量较对照组（0 μmol/L Al3+）均显著升高，尤其是柳城05-136和中糖1202随着营养液中Al3+浓度增加，ScTDT基因的表达量呈显著升高趋势，说明高浓度Al3+胁迫更能诱导ScTDT基因高效表达。

3个甘蔗品种中，以中糖1202的ScTDT基因表达量变化最大，柳城05-136次之，以ROC22的变化最小。

【结论】克隆获得的ScTDT基因表达具有组织特异性，在根中高效表达可能与甘蔗抵抗铝胁迫相关，即植株通过上调根中ScTDT 基因表达，从而加快液泡中苹果酸的释放，促使苹果酸从根中分泌到土壤与Al3+反应，从而减少铝毒害，表明ScTDT基因可能参与甘蔗抵抗铝胁迫，且不同甘蔗品种的抗铝胁迫能力有所不同。

Effect of alloying elements on the microstructure and mechanical properties of nanostructured

LetterEffect of alloying elements on the microstructure and mechanical properties of nanostructured ferritic steels produced by spark plasmasinteringSomayeh Pasebani,Indrajit Charit ⇑Department of Chemical and Materials Engineering,University of Idaho,Moscow,ID 83844,USAa r t i c l e i n f o Article history:Received 23November 2013Received in revised form 23January 2014Accepted 29January 2014Available online 15February 2014Keywords:NanostructuresMechanical alloying Powder metallurgyTransmission electron microscopy High temperature alloya b s t r a c tSeveral Fe–14Cr based alloys with varying compositions were processed using a combined route of mechanical alloying and spark plasma sintering.Microstructural characteristics of the consolidated alloys were examined via transmission electron microscopy and atom probe tomography,and mechanical prop-erties evaluated using microhardness nthanum oxide (0.5wt.%)was added to Fe–14Cr leading to improvement in microstructural stability and mechanical properties mainly due to a high number den-sity of La–Cr–O-enriched nanoclusters.The combined addition of La,Ti (1wt.%)and Mo (0.3wt.%)to the Fe–14Cr base composition further enhanced the microstructural stability and mechanical properties.Nanoclusters enriched in Cr–Ti–La–O with a number density of 1.4Â1024m À3were found in this alloy with a bimodal grain size distribution.After adding Y 2O 3(0.3wt.%)along with Ti and Mo to the Fe–14Cr matrix,a high number density (1.5Â1024m À3)of Cr–Ti–Y–O-enriched NCs was also detected.For-mation mechanism of these nanoclusters can be explained through the concentrations and diffusion rates of the initial oxide species formed during the milling process and initial stages of sintering as well as the thermodynamic nucleation barrier and their enthalpy of formation.Ó2014Elsevier B.V.All rights reserved.1.IntroductionNanostructured ferritic steels (NFSs),a subcategory of oxide dis-persion strengthened (ODS)steels,have outstanding high temper-ature strength,creep strength [1,2]and excellent radiation damage resistance [3].These enhanced properties of NFSs have been attrib-uted to the high number density of Y–Ti–O-enriched nanoclusters (NCs)with diameter of 1–2nm [4].The Y–Ti–O-enriched NCs have been found to be stable under irradiation and effective in trapping helium [5].These NCs are formed due to the mechanical alloying (MA)of Fe–Cr–Ti powder with Y 2O 3during high energy ball milling followed by hot consolidation route such as hot isostatic pressing (HIP)or hot extrusion [6–8].Alinger et al.[4]have investigated the effect of alloying elements on the formation mechanism of NCs in NFSs processed by hot isostatic pressing (HIP)and reported both Ti and high milling energy were necessary for the formation of ler and Parish [9]suggested that the excellent creep properties in yttria-bearing NFSs result from the pinning of thegrain boundaries by a combined effect of solute segregation and precipitation.Although HIP and hot extrusion are commonly used to consoli-date the NFSs,anisotropic properties and processing costs are con-sidered challenging issues.Recently,spark plasma sintering (SPS)has been utilized to sinter the powder at a higher heating rate,low-er temperature and shorter dwell time.This can be done by apply-ing a uniaxial pressure and direct current pulses simultaneously to a powder sample contained in a graphite die [10].Except for a few studies on consolidation of simple systems such as Fe–9Cr–0.3/0.6Y 2O 3[11]and Fe–14Cr–0.3Y 2O 3[10],the SPS process has not been extensively utilized to consolidate the NFSs with complex compositions.Recently,the role of Ti and Y 2O 3in processing of Fe–16Cr–3Al–1Ti–0.5Y 2O 3(wt.%)via MA and SPS was investigated by Allahar et al.[12].A bimodal grain size distribution in conjunc-tion with Y–Ti–O-enriched NCs were obtained [12,13].In this study,Fe–14Cr (wt.%)was designed as the base or matrix alloy,and then Ti,La 2O 3and Mo were sequentially added to the ferritic matrix and ball milled.This approach allowed us to study the effect of individual and combined addition of solutes on the formation of NCs along with other microstructural evolutions.Furthermore,SPS instead of other traditional consolidation methods was used to consolidate the NFS powder.The mixture/10.1016/j.jallcom.2014.01.2430925-8388/Ó2014Elsevier B.V.All rights reserved.⇑Corresponding author.Tel.:+12088855964;fax:+12088857462.E-mail address:icharit@ (I.Charit).of Fe–Cr–Ti–Mo powder with Y2O3was also processed and characterized in a similar manner for comparison with the rest of the developed alloys.2.ExperimentalThe chemical compositions of all the developed alloys along with their identi-fying names in this study are given in Table1.High energy ball milling was per-formed in a SPEX8000M shaker mill for10h using Ar atmosphere with the milling media as steel balls of8mm in diameter and a ball to powder ratio(BPR) of10:1.A Dr.Sinter Lab SPS-515S was used to consolidate the as-milled powder at different temperatures(850,950and1050°C)for7min using the pulse pattern 12–2ms,a heating rate of100°C/min and a pressure of80MPa.The SPSed samples were in the form of disks with8mm in height and12mm in diameter.The density of the sintered specimens was measured by Archimedes’method. Vickers microhardness tests were performed using a Leco LM100microhardness tester operated at a load of1000g–f(9.8N).A Fischione Model110Twin-Jet Elec-tropolisher containing a mixture of CH3OH–HNO3(80:20by vol.%)as the electrolyte and operated at aboutÀ40°C was used to prepare specimens for transmission elec-tron microscopy(TEM).A FEI Tecnai TF30–FEG STEM operating at300kV was used. The energy dispersive spectroscopy(EDS)attached with the STEM was used to roughly examine the chemical composition of the particles.A Quanta3D FEG instrument with a Ga-ion source focused ion beam(FIB)was used to prepare spec-imens for atom probe tomography(APT)studies on14L,14LMT and14YMT sam-ples.The APT analysis was carried out using a CAMECA LEAP4000X HR instrument operating in the voltage mode at50–60K and20%of the standing volt-age pulse fraction.The atom maps were reconstructed using CAMECA IVAS3.6soft-ware and the maximum separation algorithm to estimate the size and chemical composition of NCs.This was applied to APT datasets each containing20–30million ions for each specimen.Lower evaporationﬁeld of the nanoparticles and trajectory aberrations caused estimation of higher Fe atoms in the nanoclusters.Although the contribution of Fe atoms from the matrix was examined here,the matrix-correction was not addressed in this study.3.Results and discussionThe TEM brightﬁeld micrographs for the various alloys SPSed at 950°C for7min are illustrated in Fig.1a–d.The microstructure of 14Cr alloy shown in Fig.1a revealed a complex microstructure with submicron subgrain-like structures,relatively high density of dislocations and low number density of oxide nanoparticles. The nanoparticles were larger(25–65nm)than the other SPSed al-loys and found to have chemical compositions close to Cr2O3and FeCr2O4as analyzed by energy dispersive spectroscopy.The microstructure of the consolidated14L alloy is shown in Fig.1b.The microstructure consisted of more ultraﬁne grains (<1l m but>100nm),a few nanograins with sharp boundaries and a higher number of nanoparticles mainly in the grain interiors. The number density of nanoparticles was higher than that of14Cr alloy shown in Fig.1a but lower than14LMT(Fig.1c)and14YMT (Fig.1d).In14L alloy,the nanoparticles with2–11nm in diameter were found inside the grains(hard to be observed at magniﬁcation given in Fig.1b and micrographs taken at higher magniﬁcations was used for this purpose)whereas the nanoparticles with 50–80nm in diameter were located at the grain boundary regions. The particles on the boundaries are likely to be mainly Cr2O3and LaCrO3,but the chemical analysis of those smallest particles could not be done precisely due to the signiﬁcant inﬂuence of the ferritic matrix.Fig.1c shows the microstructure of the SPSed14LMT alloy, consisting of both ultraﬁne grains(as deﬁned previously)and nanograins(6100nm).The nanoparticles present in the micro-structure were complex oxides of Fe,Cr and Ti.The nanoparticles with faceted morphology and smaller than10nm in diameter were enriched in La and Ti.No evidence of stoichiometric La2TiO5or La2Ti2O7particles was observed based on the EDS and diffraction data.A similar type of microstructure was revealed in the SPSed 14YMT alloy as shown in Fig.1d.The particle size distribution histograms of the14Cr,14L, 14LMT and14YMT alloys are plotted in Fig.2a–d,respectively. Approximately1000particles were sampled from each alloy to de-velop the histograms.The average particle size decreased in order of14Cr,14L,14LMT and14YMT.The highest fraction of the particle size as shown in the histograms of14Cr,14L,14LMT and14YMT was found to be associated with25±5nm(18±2.5%),10±5nm (28±3%),5±1nm(40±6%)and5±1nm(46±5%)in diameter, respectively.The number density of nanoparticles smaller than 5±1nm was higher in14YMT than14LMT alloy.The3-D APT maps for14L alloy revealed a number density (%3Â1022mÀ3)of CrO–La–O-enriched NCs.The average Guinier radius of these NCs was1.9±0.6nm.The average composition of the NCs in14L was estimated by using the maximum separation algorithm to be Fe–17.87±3.4Cr–32.61±3.2O–8.21±1.1La(at.%).A higher number density(%1.4Â1024mÀ3)and smaller NCs with average Guinier radius of 1.43±0.20nm were observed in the APT maps for14LMT alloy as shown in Fig.3a.The NCs were Cr–Ti–La–O-enriched with the average composition of Fe–10.9±2.8Cr–30.9±3.1O–17.3±2.5Ti–8.2±2.2La(at.%).According to the LEAP measurements,the chemical composition of NCs dif-fered considerably from stoichiometric oxides.A large amount of Fe and Cr was detected inside the NCs,and La/Ti and La/O ratios were not consistent with La2TiO5or La2Ti2O7as expected based on thermodynamic calculations,rather the ratios were sub-stoichi-ometric.The3-D APT maps for14YMT alloy were similar to14YMT alloy as shown in Fig.3b.The NCs with an average radius of 1.24±0.2nm and a number density of1.5Â1024mÀ3were Cr–Ti–Y–O-enriched.The chemical composition of NCs was estimated close to Fe–8.52±3.1Cr–37.39±4.5O–24.52±3.1Ti–10.95±3.1Y (at.%).The matrix-corrected compositions are currently being ana-lyzed and will be reported in a full-length publication in near future.The relative density of various alloys sintered at850–1050°C is shown in Fig.4a.Generally,a higher density was obtained in the specimens sintered at higher temperatures.At850and950°C, the density of unmilled14Cr specimen(97.2%and97.5%)was higher than the milled/SPSed14Cr(92.8%and95.5%)because the unmilled powder particles were less hard(due to absence of strain hardening)and plastically deformed to a higher degree than the milled powder leading to a higher density.Adding0.5and 0.7wt.%of La2O3and0.3wt.%Y2O3to the14Cr matrix signiﬁcantly decreased the density of the specimen,especially at850and 950°C;however,adding Ti to14L and14Y improved the density to some extent.The microhardness data of various alloys processed at different temperatures are shown in Fig.4b.In general,microhardness in-creased with increasing SPS temperatures up to950°C and then decreased.Both Y and La increased the hardness due to the disper-sion hardening effect.The hardness increased at the higher content of La due to the greater effect of dispersion hardening.Adding Ti separately to the14Cr matrix improved the hardness due to theTable1The alloy compositions and processing conditions(milled for10h and SPSed at850-1050°C for7min).Alloy ID Elements(wt.%)Cr Ti La2O3Y2O3Mo Fe14Cr-unmilled140000Bal.14Cr140000Bal.14T141000Bal.14L1400.500Bal.14Y14000.30Bal.14LM1400.500.3Bal.14LT1410.500Bal.14LMT(0.3)1410.300.3Bal.14LMT1410.500.3Bal.14LMT(0.7)1410.700.3Bal.14YMT14100.30.3Bal.S.Pasebani,I.Charit/Journal of Alloys and Compounds599(2014)206–211207dispersion hardening but only at lower temperature(850°C).The coarsening of Ti-enriched particles at above850°C plausibly decreased the hardness.However,at950°C,higher hardness (457HV)was achieved by a combined addition of La and Ti toFig.2.Particle size frequency histogram for(a)14Cr,(b)14L,(c)14LMT and(d)14YMT alloys. Fig.1.TEM brightﬁeld micrographs for various alloys(a)14Cr,(b)14L,(c)14LMT and(d)14YMT.the14Cr matrix to produce14LT.Further addition of Mo to14LT improved the hardness through solid solution strengthening in 14LMT(495HV).High dislocation density and no well-deﬁned grain boundaries were characteristics of14Cr alloy as shown in Fig.1a.The presence of a low number density and larger oxide particles(FeCr2O4and Cr2O3)at the boundaries could not create an effective pinning effect during sintering.As a result,some of these particles became conﬁned within the grain interiors.The coarse grains had the capacity to produce and store high density of dislocations that subsequently resulted in the strain hardening effect.The hardening mechanism in14Cr alloy can thus be attributed to greater disloca-tion activities and resulting strain hardening effect.The grain boundary or precipitation hardening cannot be the dominant mechanism because of larger particles,greater inter-particle spac-ing and weakened Zener drag effect at the temperature of sinter-ing.Such strain hardening capability in nanocrystalline Fe consolidated via SPS was reported by other researchers,too [14,15].Interestingly,the high hardness in Fe–14Cr alloy consoli-dated via SPS at1100°C for4min by Auger et al.[10]wasFig.3.Three-dimensional atom maps showing NCs for(a)14LMT–91Â34Â30nm3and(b)14YMT–93Â30Â30nm3.Fig.4.(a)The relative density and(b)microhardness values for different SPSed alloys processed at different SPS temperatures for a dwell time of7min.attributed to the formation of martensitic laths caused by higher carbon content diffusing from the die,possible Cr segregation and rapid cooling during SPS.It is noteworthy to mention that no martensite lath was observed in the consolidated14Cr alloy in the present study.The level of solutes in the bcc matrix could be much greater than the equilibrium level,associated with a large number of vacancies created during milling.Our recent study[16]has shown that high energy ball milling has a complex role in initiating nucle-ation of La–Ti–O-enriched NCs in14LMT alloy powder,with a mean radius of%1nm,a number density of3.7Â10À24mÀ3and a composition of Fe–12.11Cr–9.07Ti–4.05La(at.%).The initiation of NCs during ball milling of NFSs has also been investigated by other researchers[8,17,18].According to Williams et al.[8],due to a low equilibrium solubility of O in the matrix,the precipitation of nanoparticles is driven by an oxidation reaction,subsequently resulting in reduction of the free energy.As the SPS proceeds,the number density of NCs would decrease and larger grain boundary oxides would form with the grain structure developing simulta-neously during the sintering process[8].Formation of larger grain boundary oxides as shown in Fig.1a could have been preceded by segregation of O and Cr to grain boundaries leading to a decrease in the level of the solutes in the ferritic matrix.The initial oxides forming in a chromium-rich matrix can be Cr2O3as suggested by Williams et al.[8].However,formation of LaCrO3in14L alloy (shown in Fig.1b)was associated with a higher reduction in the free energy according to the enthalpy of formation of various oxi-des given in Table2.The presence of nanoparticles caused grain boundary pinning and subsequently stabilized the nanocrystalline grains.The high density of defects(dislocations and vacancies)in a supersaturated solid solution,such as14LMT and14YMT alloys, could dramatically increase the driving force for accelerated sub-grain formation during the initial stage of sintering.At the initial stage,the vacancies created during the milling are annihilated [8,17].Meanwhile,the temperature is not high enough to produce a signiﬁcant number of thermal vacancies;subsequently,any nucleation of new NCs will be prevented.As the SPS proceeds with no nucleation of new NCs,the high concentrations of extra solutes in the matrix are thermodynamically and kinetically required to precipitate out to form larger oxide particles.The larger solute-enriched oxide particles can be formed more favorably on the grain boundaries due to the higher boundary diffusivity.On the other hand,it should be considered that there is a dynamic plastic deformation occurring within the powder particles during SPS. The interaction of larger particles and dislocations introduced by dynamic hot deformation can explain the coarsening in some grains;because larger particles could not effectively pin the dislo-cations and the grain boundary migration could be facilitated fol-lowing the orientation with lower efﬁciency of Zener drag mechanism[19].Once the extra solutes present in the matrix pre-cipitated out,the microstructure will remain very stable because of the grain boundary pinning by triple-junctions of the grain bound-aries themselves[20],along with the high density of NCs and other ultraﬁne oxide particles[8].Further coarsening of the grains will be prevented even for longer dwell times at950°C.Therefore,a bi-modal grain size distribution emerged.The hardening of14LMT and14YMT alloys were attributed to a combined effect of solid solution strengthening,Hall-Petch strengthening and precipitation hardening.Based on the APT studies of the as-milled powder[16]and for-mation mechanism of the oxide particles suggested by Williams et al.[8]it could be speculated that in14LMT and14YMT alloys, Cr–O species formﬁrst and then absorb Ti and La/Y.This is associ-ated with a change in the interfacial energy of Cr–O species even though it is not thermodynamically the most favorable oxide.It has been established that the driving force for the oxide precipi-tates to form is the low solubility limit of oxygen in the ferritic ma-trix.The change in free energy due to oxidation reaction and nucleation of oxide nanoparticles is the leading mechanism[8].The majority of the oxygen required to generate the oxide nano-particles may be provided from the surface oxide during milling process.Furthermore,higher concentrations of Cr led to greater nucleation of Cr–O by inﬂuencing the kinetics of oxide formation. Concentrations and diffusivities of the oxide species along with the energy barrier for nucleation will control the nucleation of oxide nanoparticles.After the Cr–O formed during sintering,the Ti–O and Y/La-enriched clusters could form.The sub-stoichiome-tric NCs in14LMT and14YMT alloys were not due to insufﬁcient level of O in the matrix[8].Formation of stoichiometric Y2Ti2O7 and Y2TiO5requires very high temperatures[8],which were outside the scope of this study.4.ConclusionThe SPSed Fe–14Cr alloy was found to have a higher hardness at room temperature due to the strain hardening effect.The stability of its microstructure at high temperatures was improved by addi-tion of La forming the Cr–La–O-enriched NCs.Adding La and Ti to Fe–14Cr matrix signiﬁcantly improved the mechanical behavior and microstructural stability further due to the high number density of Cr–Ti–La–O-enriched NCs in14LMT alloy.It is demon-strated that the potential capability of La in developing new NFSs is promising but further investigations on their thermal and irradiation stability will still be required.AcknowledgementThis work was supported partly by the Laboratory Directed Research and Development Program of Idaho National Laboratory (INL),and by the Advanced Test Reactor National Scientiﬁc User Facility(ATR NSUF),Contract DE-AC07-05ID14517.The authors gratefully acknowledge the assistance of the staff members at the Microscopy and Characterization Suite(MaCS)facility at the Center for Advanced Energy Studies(CAES).References[1]M.J.Alinger,G.R.Odette,G.E.Lucas,J.Nucl.Mater.307–311(2002)484.[2]R.L.Klueh,J.P.Shingledecker,R.W.Swindeman,D.T.Hoelzer,J.Nucl.Mater.341(2005)103.[3]M.J.Alinger,G.R.Odette,D.T.Hoelzer,J.Nucl.Mater.329–333(2004)382.[4]M.J.Alinger,G.R.Odette,D.T.Hoelzer,Acta Mater.57(2009)392.Table2The standard enthalpies of formation of various oxide compounds at25°C[8,21,22].Element CompositionÀD H f(kJ molÀ1(oxide))Cr Cr2O31131CrO2583Fe Fe3O41118Fe2O3822Ti TiO543TiO2944Ti2O31522Ti3O52475Y Y2O31907YCrO31493Y2Ti2O73874La La2O31794La2Ti2O73855LaCrO31536210S.Pasebani,I.Charit/Journal of Alloys and Compounds599(2014)206–211[5]G.R.Odette,M.L.Alinger,B.D.Wirth,Annu.Rev.Mater.Res.38(2008)471.[6]ai,T.Okuda,M.Fujiwara,T.Kobayashi,S.Mizuta,H.Nakashima,J.Nucl.Sci.Technol.39(2002)872.[7]ai,M.Fujiwara,J.Nucl.Mater.307–311(2002)749.[8]C.A.Williams,P.Unifantowicz,N.Baluc,G.D.Smith,E.A.Marquis,Acta Mater.61(2013)2219.[9]ler,C.M.Parish,Mater.Sci.Technol.27(2011)729.[10]M.A.Auger,V.De Castro,T.Leguey,A.Muñoz,Pareja,R,J.Nucl.Mater.436(2013)68.[11]C.Heintze,M.Hernández-Mayoral, A.Ulbricht, F.Bergner, A.Shariq,T.Weissgärber,H.Frielinghaus,J.Nucl.Mater.428(2012)139.[12]K.N.Allahar,J.Burns,B.Jaques,Y.Q.Wu,I.Charit,J.I.Cole,D.P.Butt,J.Nucl.Mater.443(2013)256.[13]Y.Q.Wu,K.N.Allahar,J.Burns,B.Jaques,I.Charit,D.P.Butt,J.I.Cole,Cryst.Res.Technol.(2013)1,/10.1002/crat.201300173.[14]K.Oh-Ishi,H.W.Zhang Hw,T.Ohkubo,K.Hono,Mater.Sci.Eng.A456(2007)20.[15]B.Srinivasarao,K.Ohishi,T.Ohkubo,K.Hono,Acta Mater.57(2009)3277.[16]S.Pasebani,I.Charit,Y.Q.Wu, D.P.Butt,J.I.Cole,Acta Mater.61(2013)5605.[17]M.L.Brocq,F.Legendre,M.H.Mathon,A.Mascaro,S.Poissonnet,B.Radiguet,P.Pareige,M.Loyer,O.Leseigneur,Acta Mater.60(2012)7150.[18]M.Brocq,B.Radiguet,S.Poissonnet,F.Cuvilly,P.Pareige,F.Legendre,J.Nucl.Mater.409(2011)80.[19]H.K.D.H.Bhadeshia,Mater.Sci.Eng.A223(1997)64.[20]H.K.D.H.Bhadeshia,Mater.Sci.Technol.16(2000)1404.[21]W.Gale,T.Totemeier,Smithells Metals Reference Book,Amsterdam,Holland,2004.[22]T.J.Kallarackel,S.Gupta,P.Singh,J.Am.Ceram.Soc.(2013)1,http:///10.1111/jace.12435.S.Pasebani,I.Charit/Journal of Alloys and Compounds599(2014)206–211211。

乌药醚内酯的热稳定 -回复

乌药醚内酯的热稳定-回复乌药醚内酯（Z-ligustilide）是一种从乌药（Angelica sinensis）根茎中提取的有效成分，已被广泛应用于传统中医药中。

它具有多种药理活性，如抗炎、抗氧化和抗肿瘤等。

然而，乌药醚内酯的热稳定性一直是人们关注的一个问题。

在本文中，我们将逐步回答乌药醚内酯的热稳定性问题，并探讨如何提高其热稳定性。

首先，我们需要了解乌药醚内酯的分子结构。

乌药醚内酯的化学式为C12H14O2，它是一种六元环酮，具有一个吡咯环和一个稠杂环。

由于其结构的特殊性，乌药醚内酯在高温下容易发生分解，导致其药效的降低。

要探讨乌药醚内酯的热稳定性，我们需要从以下几个方面进行分析：1. 热分解机理：首先，我们需要了解乌药醚内酯在高温下发生分解的机理。

目前，研究表明乌药醚内酯的热分解主要经历两步反应，即吡咯环的开环和环氧环裂解。

这些反应导致乌药醚内酯分解产物的生成，进而降低其药效。

2. 影响热稳定性的因素：乌药醚内酯的热稳定性受多种因素的影响。

首先，温度是影响其热稳定性的最重要因素之一。

较高的温度会加速乌药醚内酯的分解反应。

此外，pH值、氧气和光照等环境条件也会对其热稳定性产生影响。

3. 提高热稳定性的方法：为了提高乌药醚内酯的热稳定性，人们进行了一系列的研究。

其中一个常用的方法是使用辅料进行复配。

例如，一些聚合物和多糖类化合物被用作乌药醚内酯的载体，能够提高其热稳定性。

此外，一些表面活性剂和抗氧化剂也被发现可以延缓乌药醚内酯的分解。

4. 热稳定性与药效关系的研究：乌药醚内酯作为一种药物成分，其热稳定性直接影响着其药效的持久性。

因此，研究人员通过测定乌药醚内酯在不同温度下的分解程度，来评估其热稳定性与药效之间的关系。

这些研究结果对进一步提高乌药醚内酯的热稳定性具有重要意义。

综上所述，乌药醚内酯的热稳定性一直是研究者关注的一个问题。

通过了解其热分解机理、影响热稳定性的因素，以及提高热稳定性的方法，可以帮助我们更好地理解和应用乌药醚内酯。

微波烧结生物医用多孔Ti-23%Nb形状记忆合金的参数优化

Trans. Nonferrous Met. Soc. China 28(2018) 700−710Parameter optimization of microwave sintering porous Ti−23%Nbshape memory alloys for biomedical applicationsMustafa K. IBRAHIM1, E. HAMZAH1, Safaa N. SAUD2, E. M. NAZIM1, A. BAHADOR11. Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia;2. Faculty of Information Sciences and Engineering,Management & Science University, 40100 Shah Alam, Selangor, MalaysiaReceived 13 March 2017; accepted 26 May 2017Abstract: Porous Ti−23%Nb (mole fraction) shape memory alloys (SMAs) were prepared successfully by microwave sintering with excellent outer finishing (without space holder). The effects of microwave-sintering on the microstructure, phase composition, phase-transformation temperature, mechanical properties and shape-memory effect were investigated. The results show that the density and size of porosity vary based on the sintering time and temperature, in which the smallest size and the most uniform pore shape are exhibited with Ti−23%Nb SMA after being sintered at 900 °C for 30 min. The microstructure of porous Ti−Nb SMA consists of predominant α", α, and β phases in needle-like and plate-like morphologies, and their volume fractions vary based on the sintering time and temperature. The β phase represents the largest phase due to the higher content of β stabilizer element with little intensities of α and α" phases. The highest ultimate strength and its strain are indicated for the sample sintered at 900 °C for 30 min, while the best superelasticity is for the sample sintered at 1200 °C for 30 min. The low-elastic modulus enables these alloys to avoid the problem of “stress shielding”. Therefore, microwave heating can be employed to sinter Ti-alloys for biomedical applications and improve the mechanical properties of these alloys.Key words: biomedical Ti−23%Nb alloy; microwave sintering; microstructure; transformation temperature; mechanical properties1 IntroductionTitanium-based alloys are characterized byexcellent corrosion resistance, good ductility and highyield strength; consequently, they are widely used forbiomedical applications as human-body implantsincluding hip joints, medical devices and dentalimplants [1,2]. Among many shape memory alloys(SMAs), Ti–Ni SMAs have been widely utilized forbiomedical applications. However, the toxicity andhypersensitivity of Ni have influenced the developmentof Ni-free shape memory alloys [3] that are non-toxicand good biocompatible elements such as Nb andTa [4−6]. Therefore, TiNb-based alloys are expectable tobe used to biomedical parts due to their low elasticmodulus, superior biocompatibility [7,8], superelasticityand good shape memory behaviour [3]. Being able to usepowder metallurgy is vital due to the ability to producenear-net-shape components without requiring anydeformation and machining operations [9−13]. Ti−Nballoys can be fabricated by powder metallurgy throughseveral methods including conventional sintering [14,15],metal-injection moulding [16−18], self-propagatinghigh-temperature synthesis [19], hot-isostaticpressing [20], spark-plasma sintering [14,21,22], andmicrowave sintering. The microwave sintering techniqueis a relatively new method to prepare Ti−Nb alloys, andit is considered a new sintering method for metals,composites, ceramics and semiconductors [23−25].Overall, microwave sintering has several advantagessuch as enhanced diffusion process, reduced energy andsintering-process time, rapid heating rates, and improvedmechanical and physical properties [23,24]. The presenceof pores that reduce the elastic modulus ofporous-titanium alloys [26−28] also allows the implantcells to grow into the pores and integrate with the hosttissue [28−30]. This reduced elastic modulus diminishesthe effect of “stress shielding”, which is generated due tothe large mismatch of elastic moduli between the implantmaterials (>100 GPa) and hard tissue (<20 GPa). The“stress shielding” may cause resorption of these har dCorresponding author: E. HAMZAH; E-mail: esah@fkm.utm.myDOI:10.1016/S1003-6326(18)64702-8Mustafa K. IBRAHIM, et al/Trans. Nonferrous Met. Soc. China 28(2018) 700−710 701tissues, loosen the implants and finally lead to implantation failure [31−33]. Several studies used the space-holder method for producing porous Ti-based alloys [34−38]. There are also some studies on using space holder and sintering methods to produce foam structures of different metal powders [39−41]. The main problem of using the space-holder method is removing this space holder material from the compacted parts during the sintering process [42]. The space holder materials should be removed carefully to prevent distortion and collapsing of the compacted powders. Moreover, the contamination that occurs due to the presence of oxygen, nitrogen and hydrogen in these materials, which are dissolved in titanium or titanium alloys via increasing temperature during the sintering process, adversely impacts mechanical properties [36]. The main aim of this research is to optimize microwave sintering parameters on the microstructure, mechanical and shape memory properties of Ti−23%Nb (mole fraction) for biomedical applications.2 ExperimentalThe raw materials are titanium powder (99.5% in purity and 150 µm in particle size) and niobium powder (99.85% in purity and 74 µm in particle size), and Ti−23%Nb. These powders were mixed using a planetary ball mill (Retsch PM100) for 1 h at a rotating speed of 300 r/min. Ball to powder mass ratio is 4:1 to homogenize the mixture of the powders. Ti−23%Nb powders were converted to pellets (d25 mm × 10 mm) by cold-pressing under a uniaxial pressure of 23 MPa for 5 min. Then, these green samples were microwave sintered either at 900, 1000 or 1200 °C for 10 or 30 min at a heating rate of 30 °C/min and furnace cooling to 250−300 °C, followed by water cooling (during furnace cooling, the cylindrical stainless steel 304 was under water cooling). The cooling rate at all parameters showed a small range of 8−9 °C/min. The microwave machine was HAMiLab-V3, SYNOTHERM Corp. Afterwards, Ti−23%Nb microwave-sintered samples were machined by electrical-discharge machining wire and cut to dimensions of 7 mm ×7 mm ×14 mm for the microstructure characterization and compression test and 10 mm ×10 mm ×20 mm for the shape-memory test, according to the standards of ASTM E9-09. Figure 1 presents the schematic diagram of microwave sintering pot consisting of infra-red pyrometer, outer water-cooled cylindrical stainless steel 304, insulation cylindrical cover made from cotton fibres, alumina crucible, rotator motor, small circular opening on the cover of the cylindrical stainless steel 304 used to approach the samples during sintering, which is covered by a sieve to prevent the microwaves from leaving the cylindrical stainless steel and glass, and silicon carbide used as auxiliary heat material. The microwaves were produced by two magnetrons, which were set to be 4.5 kW and 2.45 GHz. The temperature of the samples during sintering was measured by a Fluke Raytek infra-red pyrometer through the openings in the insulation cylindrical cover and alumina crucible, which is possible since infra-red rays can pass through the setup to reach the sample. The silicon carbide was used with a mass of 18−20 g and placed in an alumina crucible with a square top view and internal dimensions of 8.8 cm in length and width and 3.2 cm in height.The relative density was tested by the Archimedes- drainage method. The optical microscopy (Nikon microscope) was used to determine the average pore size by using software called “i Solution DT”. The microstructure was analyzed by SEM (SEM, Hitachi, model S−3400N).The pore size,pore shape,poreFig. 1 Schematic diagram of microwave sintering potMustafa K. IBRAHIM, et al/Trans. Nonferrous Met. Soc. China 28(2018) 700−710 702distribution, grain size, volume fraction of the needles and the plates were observed by Imagej software. The phase composition of Ti−23%Nb samples was characterized by X-ray diffraction (D5000 Siemens X-ray diffractometer) fitted with a Cu K X-ray source with a locked coupled mode, a 2θ range between 20° and 90°and a scanning step of 0.05 (°)/s. The phase transformation temperatures of these alloys were identified using a differential scanning calorimeter (DSC Q200, TA Instrument) under heating and cooling rates of 10 °C/min using TA Instrument software. The compression test was performed at room temperature using an Instron 600 DX-type universal testing machine and operated at an extension rate of 0.5 mm/min. The microhardness was measured by Vickers hardness test (Matsuzawa Vicker) using 30 kg force for 20 s, and the test was performed at room temperature. The shape memory effect (SME) test was performed using an Instron 600 DX-type universal testing machine, which operated with the special-program parameters according to the SME test, and the loading−unloading cycle compressive test was performed at a strain of 4%. The tests were performed at human body temperature (37 °C), which is below the martensite start temperature (M s), while below this temperature, the samples would be able to obtain shape recovery. Then, the deformed samples that still had an unrecoverable shape were heated above the austenite finish temperature at 200 °C for 30 min, followed by water quenching to recover the residual strain (ɛr). After the cooling process, the recovered shape was attributed to the transformation of the detwinned martensite to the austenite phase, which had been termed as transformation strain (ɛt).3 Results and discussion3.1 Microstructure characterizationThe relative density of Ti−23%Nb samples has a small range of 74%−78%, and the density decreased gradually with increasing sintering time and temperature. Figure 2 shows the optical micrographs of Ti−23%Nb samples sintered with different parameters of microwaveFig. 2 Optical micrographs of Ti−23%Nb samples sintered at 900 °C for 10 min (a) and 30 min (b), 1000 °C for 10 min (c) and 30 min (d), 1200 °C for 10 min (e) and 30 min (f)Mustafa K. IBRAHIM, et al/Trans. Nonferrous Met. Soc. China 28(2018) 700−710 703sintering time and temperature. The Ti−Nb sample shown in Fig. 2(b) exhibits the smallest average pore size with a good pore distribution and more uniform pore shape compared with the others samples. Irregular pore shape, non-homogeneous pore distribution, and sharp pore edges act as stress concentration and cause the decrease of mechanical and shape-memory properties, which leads to crack propagation through these pores [43−46]. Table 1 shows the relative density and average pore size of Ti−23%Nb samples. The existence of porosity in the Ti−23%Nb is mainly caused by the inter-diffusion process, and according to Kirkendall effect [10,47], the atoms are able to diffuse during the sintering of solid phase, thus causing the porosity. The diffusion process of niobium atoms into titanium is prominently faster than that of titanium atoms into niobium [48], and due to the unbalance of mass transfer that can result in a pore formation in the niobium-rich region. Figure 1 depicts the Ti−23%Nb samples with all the fabrication steps from the cooled pressed powder until the sample was prepared for microstructure characterization (located on the right side and indicated by the arrow of colored points). After microwave sintering, the Ti−23%Nb samples appeared to have a uniform surface without large cavities or non-uniform shrinkage to satisfy the main principle of powder metallurgy products of producing products without requiring any deformation operation and machining to produce near-net-shape components) [9−13].Figure 3 illustrates scanning electron microscopy (SEM) images of Ti−23%Nb SMAs. These imagesTable 1Relative density and average pore size of Ti−23%Nb samplesSinteringtemperature/°CSinteringtime/minRelativedensity/%Average poresize/µm 900 10 78±4 11.68±0.5900 30 77±3.7 9.78±0.451000 10 76.9±3.7 13.8±0.71000 30 75±3.6 13.94±0.71200 10 74.2±3.6 19.2±0.91200 30 74±3.6 24±1.2Fig. 3 SEM images of Ti−23%Nb SMAs sintered at 900 °C for 10 min (a) and 30 min (b), 1000 °C for 10 min (c) and 30 min (d), 1200 °C for 10 min (e) and 30 min (f)Mustafa K. IBRAHIM, et al/Trans. Nonferrous Met. Soc. China 28(2018) 700−710 704illustrate a presence of two types of microstructure morphologies, needle-like and plate-like. Sintering temperature had a larger effect than the sintering time due to the grain size and the volume fraction of the needles and plates. Therefore, the grain size increases with increasing sintering temperature, which may cause diminished mechanical properties because of the crack to propagate easily through the grain boundaries [45,46]. The volume fraction of the needles and plates increased with increasing sintering temperature. KIM et al [49] reported that Ti−(15−35)%Nb (mole fraction) alloys exhibit superelastic and shape-memory properties associated with the βto α" martensitic transformation, while CHAI et al [50] reported that Ti−(20−24)%Nb alloys exhibit self-accommodation morphologies of the α"consisting of solid and hollow triangular morphologies and V-shaped morphology. The solid plates of α"phase were observed in Figs. 3(a) and (b), while the hollow plates (hollow triangular morphology) were observed for samples sintered at 1200 °C, as indicated in Figs. 3(e) and (f), while the α" plates of the V-shaped morphology can be observed in some parts of the micrographs, as indicated in Fig. 3(c). According to the microstructure and XRD analysis, the βphase increased with increasing sintering temperature and time. Moreover, the increased sintering temperature and time cause dendritic plates-like morphology βD and needles-like morphology βN, as indicated in Figs. 3(d)−(f) [51]. For samples sintered at 900 °C, βneedle-like morphology similar to spaghetti or irregular lines with αphase between them appeared [52,53]. During cooling, a metastable βphase was retained and other metastable phases (α", α', α, and ω) were formed from the retained βphase. At low Nb content (i.e., 0.25%<x(Nb)<11%), a supersaturated phase of α' forms martensitically from the βphase during cooling, and regardless of the cooling rate, at higher Nb content (i.e., 11%<x(Nb)<27%) the α" structure forms from the βphase [54,55], while at the Nb content >27% (mole fraction), the (α+β) structure forms from the β phase [55]. In Ref. [49], the critical content of this alloy shows a scatter due to different cooling rates and impurity levels. Figure 4 shows the elemental mapping of Ti−23%Nb sample sintered at 900 °C for 30 min in Fig. 3(b), which displays the distribution of Ti and Nb in Ti−23%Nb SMA.Figure 5 demonstrates the XRD patterns of Ti−23%Nb SMAs with different parameters of sintering time and temperatures to verify the presence of β, α" and αphases in the microstructure and their effect on Ti−23%Nb SMAs. The βphase appears at the planes (110), (200), (211), (112) and (220) at 2θ values of 38.8°, 55.9°, 70°, 76° and 82.7°, respectively. The α" phaseFig. 4Elemental mapping of Ti−23%Nb sample sintered at 900 °C for 30 min: (a) Ti; (b) NbFig. 5XRD patterns of Ti−23%Nb SMAs at different microwave sintering parametersappears at the planes (020), (021), (102) and (130) at 2θvalues of 36.7°, 40.2°, 52.7°and 63°, respectively. In addition, the α phase appears at the planes (100), (101), (110) and (201) at 2θvalues of 35.17°, 40.2°, 63°and 77.12°[21,56,57]. The shape-memory behaviour and superelasticity of Ti−23%Nb alloy are due to the thermoelastic martensitic transformation between the cubic β parent phase and the orthorhombic α" martensite phase, as reported by other studies [49,58−60]. The Ti−23%Nb sample, which was sintered at 1200 °C for 30 min, exhibits the minimum intensities of αand α" phase peaks. The samples exhibit reduced intensities of those peaks with increasing sintering temperature andMustafa K. IBRAHIM, et al/Trans. Nonferrous Met. Soc. China 28(2018) 700−710 705time. The composition has the main effect on the microstructure of Ti−Nb alloy due to the type of the phases which were produced during the cooling [54,55], but sintering parameters affect the intensities of these phases [61]. However, the β phase represents the largest phase (see Fig. 3) due to the higher content of β stabilizer element, with small intensities of α and α" [56].3.2 Transformation temperatureFigure 6 shows differential scanning calorimeter (DSC) curves of the Ti−23%Nb samples sintered at different parameters of temperature and time. The transformation temperatures are M s (martensite start temperature), A s (austenite start temperature), M f (martensite finish temperature) and A f (austenite finish temperature). These transformation temperatures were recorded by the directly extrapolating the baseline of the DSC curves by using TA Instrument software. The austenitic transformation peaks were difficult to be detected with increasing the sintering temperature and time in Figs. 6(d)−(f), while martensitic transformation peaks can be observed for all samples. In addition, the martensite start temperature (M s) was below 105 °C for all samples. Table 2 displays the transformationFig. 6Differential scanning calorimeter (DSC) curves of Ti−23%Nb samples sintered at 900 °C for 10 min (a) and 30 min (b), 1000 °C for 10 min (c) and 30 min (d), 1200 °C for 10 min (e) and 30 min (f)Mustafa K. IBRAHIM, et al/Trans. Nonferrous Met. Soc. China 28(2018) 700−710 706Table 2 Transformation temperatures of Ti−23%Nb SMAs atdifferent sintering time and temperaturesSintering temperature/°C Sinteringtime/minTransformation temperature/°CM s M f A s A f900 10 92.62 91 5.94 157900 30 102.4 100.8 −37 1081000 10 91.2 89 −13 781000 30 85.65 84.2 −15.6 451200 10 99.8 98 −17 −101200 30 90.8 89.2 −19.3 −14.2 temperatures of Ti−23%Nb SMAs. During heating, the ranges of the A s to A f transformation decreased with increasing sintering time and temperature. The DSC result indicates that these SMAs are suitable for biomedical applications, which makes any small load enough for austenite to transform into martensite. The A f temperature was reduced with increasing sintering time and temperature, enhancing the martensitic transformation at human body temperature.3.3 Mechanical properties3.3.1 Stress−strain curvesFigures 7(a) and (b) display the compressive curves of microwave sintered Ti−23%Nb SMAs. The compressive stress−strain curves can be divided into three main regions, as shown in Fig. 7(c) [62]. The first one is a region of the linear-elastic deformation, and its slope is considered as the elastic modulus of these samples, followed by the region of the plastic yield deformation in which a peak stress appears and is considered as the sample’s compressive strength. Lastly, the third region in which the rupture occurs is called the rupture region. Table 3 displays the maximum stress (fracture strength), strain at the maximum stress, elastic modulus, and Vickers hardness. The Ti−23%Nb sample sintered at 900 °C for 10 min exhibits the lowest strength and strain maybe due to poor bonding between the powders, and the energy dispersive spectroscopy (EDS) results showed poor diffusion between the Ti and Nb powders for this sample. The sample sintered at 900 °C for 30 min exhibits the maximum stress and strain due to good bonding, good diffusion between the powders and fine grain size. Thus, increasing sintering temperature causes increased grain size and reduced maximum stress and strain due to crack propagation through grain boundaries [45,46] (see Figs. 3(e) and (f)). From Fig. 3 we can observe clearly that the microstructure of the sample in Fig. 3(b) has the smallest grain size compared with all the others samples, which gives this sample the highest fracture strength and strain. The microstructure in Fig. 3(c) shows incomplete bonding with sharp spaces surrounding the atoms that diminish the mechanical properties. The Vickers hardness and elastic modulus increase with increasing sintering time at the same temperature and with increasing temperature at the same sintering time, except the elastic modulus for sample sintered at 1200 °C. The pores and microwave sintering process have the main effect on reducing the elastic modulus [26−28] and hardness.Fig. 7 Compressive stress−strain curves of Ti−23%Nb alloys at different microwave sintering parameters (a, b) and three main regions of stress−strain curve enlargment of zone A in Fig. 7(b) of sample sintered at 900 °C for 30 min (c)Mustafa K. IBRAHIM, et al/Trans. Nonferrous Met. Soc. China 28(2018) 700−710 7073.3.2 Shape-memory effectThe shape-memory effect arises because the martensitic phase can arrange itself into a self- accommodation, finely twinned structure (heterogeneous) with no or little macroscopic strain relative to austenite. Hence, upon cooling from austenitic to martensitic phase, little strain or shape change is usually observed (one-way SME). We call this a self-accommodation form of thermal martensite unless the material or alloy has been heavily processed to have the so-called two-way SME [63]. Figure 8 displays the shape memory behavior of Ti −23%Nb SMAs because of varying the sintering time and temperature. Table 4 displays the maximum stress, shape memory effect, residual strain, and superelasticty. As for the recovery of the residual strain of the compressed samples, after heating the samples above A f up to 200 °C, this strain recovery of these alloys is due to their SME. The shape memory effect representsthe strain recovery. Based on transformation temperature curves in Fig. 6(a)−(f), the M s of Ti −23%Nb is smaller than 150 °C, so applying the strain at 37 °C (below M s ) makes the Ti −23%Nb samples able to obtain shape recovery. The XRD patterns show that the β phase is the main phase in the sample sintered at 1200 °C for 30 min at ambient temperature, while α and α" phases are increased with reducing sintering time and temperature. The SME is decreased by increasing the precipitates of the equilibrium α phase [64]. However, the β phase can transform to martensitic α" phase by adding stress during loading; while during unloading with the release of the stress, the unstable martensitic α" phase mostly transforms back to the β phase [65]. The constituting phases in these samples were detected by diffraction in transmission. This shape memory behaviour which isTable 3 Effect of sintering parameters on maximum stress and strain, elastic modulus, and Vickers hardness of Ti −23%Nb alloysSintering temperature/°CSintering time/min Maximum strength,σmax /MPa Strain at σmax , εmax /% Elastic modulus,E /GPa Vickers hardness(HV) 900 10 285±14.2 9.88±0.45 6.6±0.33 51.45±2.5 900 30 515±25.7 26.3±1.3 8±0.4 61.7±3 1000 10 411±20.5 22.8±1.1 6.62±0.33 60±3 1000 30 354±17.7 15.24±0.76 8.69±0.43 64±3.2 1200 10 428±21.4 16.8±0.84 9.2±0.46 69±3.4 1200 30334.6±16.78.2±0.418.8±0.4487.4±4.3Fig. 8 Stress −strain curves of Ti −23%Nb alloys at human body temperature (37 °C) sintered at different temperatures for 10 min (a)and 30 min (b)Table 4 Shape memory properties of Ti −23%Nb alloys sintered at different time and temperaturesSintering temperature/°CSinteringtime/min Maximum stress,σmax /MPaShape memory effect,SME/%Residual strain,εr /% Superelasticty,SE/% 900 10 248±12.4 0.0005 2.2195±0.11 44.512±2.22 900 30 222±11 0.0015 2.3785±0.11 40.537±2 1000 10 249±12.45 0.0005 2.3995±0.11 40±2 1000 30 243±12.15 0.00014 2.1199±0.1 47±2.3 120010 278±13.9 0.0001 2.0299±0.1 49.252±2.4 120030315±15.750.00021.9398±0.0951.5±2.5Mustafa K. IBRAHIM, et al/Trans. Nonferrous Met. Soc. China 28(2018) 700−710 708associated with the βto α"martensitic transformation may be the reason of obtaining a good shape memory behaviour for the samples sintered at 1200 °C. While the sample sintered at 1000 °C for 10 min shows less superelasticty even from the samples sintered at lower temperature and time, and lower intensities of βphase may be due to the weakness in microstructure because of the non-completed or non-uniform diffusion leaves spaces between the atoms shown in Fig. 3(c).4 ConclusionsBy using the microwave sintering technique, we successfully fabricated the porous Ti−23%Nb SMAs, and investigated the effects of microwave sintering parameters on the microstructure, phase composition, phase transformation temperatures, mechanical properties and shape memory effect of these alloys. Needle-like and plate-like microstructures of Ti−23%Nb SMAs are evidenced. However, the plate-like microstructure is displayed in three morphologies, α", α', and αphases. Increasing the sintering time and temperature enhances the martensitic transformation due to the gradual decrease of A f temperatures that allow the martensitic transformation to easily occur at human body temperature. The highest stress and strain were attained for the sample sintered at 900 °C for 30 min due to the highest density, smallest pore size, and uniform pore shape and distribution, while the highest superelasticty was obtained for sample sintered at 1200 °C for 30 min. Our systematic methods for sample preparation and characterization may constitute a basis to produce quality-biocompatible Ti−23%Nb SMAs. AcknowledgementsThe authors would like to thank the Ministry of Higher Education of Malaysia and Universiti Teknologi Malaysia for providing the financial support under the University Research Grant No. Q.J130000.3024. 00M57 and research facilities.References[1]LONG M, RACK H. Titanium alloys in total joint replacement—A materials science perspective [J]. Biomaterials, 1998, 19(18):1621−1639.[2]HUISKES R, WEINANS H, van RIETBERGEN B. The relationshipbetween stress shielding and bone resorption around total hip stems and the effects of flexible materials [J]. Clinical Orthopaedics and Related Research, 1992, 274: 124−134.[3]MIYAZAKI S, KIM H, HOSODA H. Development andcharacterization of Ni-free Ti-base shape memory and superelastic alloys [J]. Materials Science and Engineering A, 2006, 438: 18−24.[4]WEVER D, VELDHUIZEN A, SANDERS M, SCHAKENRAAD J,van HORN J. Cytotoxic, allergic and genotoxic activity of a nickel−titanium alloy [J]. Biomaterials, 1997, 18(16): 1115−1120. [5]NIINOMI M. Fatigue performance and cyto-toxicity of low rigiditytitanium alloy, Ti−29Nb−13Ta−4.6Zr [J]. Biomaterials, 2003, 24(16): 2673−2683.[6]LAHEURTE P, PRIMA F, EBERHARDT A, GLORIANT T, WARYM, PATOOR E. Mechanical properties of low modulus βtitanium alloys designed from the electronic approach [J]. Journal of the Mechanical Behavior of Biomedical Materials, 2010, 3(8): 565−573.[7]INAMURA T, HOSODA H, WAKASHIMA K, MIYAZAKI S.Anisotropy and temperature dependence of Young’s modulus in textured TiNbAl biomedical shape memory alloy [J]. Materials Transactions, 2005, 46(7): 1597−1603.[8]MASAHASHI N, MIZUKOSHI Y, SEMBOSHI S, OHTSU N,JUNG T, HANADA S. Photo-induced characteristics of a Ti–Nb–Sn biometallic alloy with low Young’s modulus [J]. Thin Solid Films, 2010, 519(1): 276−283.[9]HEY J, JARDINE A. Shape memory TiNi synthesis from elementalpowders [J]. Materials Science and Engineering A, 1994, 188(1): 291−300.[10]ZHANG N, KHOSROV ABADI P B, LINDENHOVIUS J,KOLSTER B. TiNi shape memory alloys prepared by normal sintering [J]. Materials Science and Engineering A, 1992, 150(2): 263−270.[11]GREEN S, GRANT D, KELLY N. Powder metallurgical processingof Ni−Ti shape memory alloy [J]. Powder Metallurgy, 1997, 40(1): 43−47.[12]IGHARO M, WOOD J. Compaction and sintering phenomena intitanium−nickel shape memory alloys [J]. Powder Metallurgy, 1985, 28(3): 131−139.[13]MORRIS D, MORRIS M. NiTi intermetallic by mixing, milling andinterdiffusing elemental components [J]. Materials Science and Engineering A, 1989, 110(1): 139−149.[14]WEN M, WEN C, HODGSON P, LI Y. Fabrication of Ti−Nb−Agalloy via powder metallurgy for biomedical applications [J].Materials & Design, 2014, 56: 629−634.[15]XIONG J, LI Y, WANG X, HODGSON P, WEN C E. Mechanicalproperties and bioactive surface modification via alkali-heat treatment of a porous Ti−18Nb−4Sn alloy for biomedical applications [J]. Acta Biomaterialia, 2008, 4(6): 1963−1968.[16]ZHAO D, CHANG K, EBEL T, NIE H, WILLUMEIT R, PYCZAKF. Sintering behavior and mechanical properties of a metal injectionmolded Ti−Nb binary alloy as biomaterial [J]. Journal of Alloys and Compounds, 2015, 640: 393−400.[17]ZHAO D, CHANG K, EBEL T, QIAN M, WILLUMEIT R, YAN M,PYCZAK F. Microstructure and mechanical behavior of metal injection molded Ti−Nb binary alloys as biomedical material [J].Journal of the Mechanical Behavior of Biomedical Materials, 2013, 28: 171−182.[18]KAFKAS F, EBEL T. Metallurgical and mechanical properties ofTi−24Nb−4Zr−8Sn alloy fabricated by metal injection molding [J].Journal of Alloys and Compounds, 2014, 617: 359−366.[19]ALEKSANYAN A, DOLUKHANYAN S, SHEKHTMAN V S,KHASANOV S, TER-GALSTYAN O, MARTIROSYAN M.Formation of alloys in the Ti−Nb system by hydride cycle method and synthesis of their hydrides in self-propagating high-temperature synthesis [J]. International Journal of Hydrogen Energy, 2012, 37(19): 14234−14239.[20]MA L W, CHUNG C Y, TONG Y, ZHENG Y. Properties of porousTiNbZr shape memory alloy fabricated by mechanical alloying and hot isostatic pressing [J]. 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断裂二硫键能力测定

断裂二硫键能力测定英文回答：Determining the ability to break disulfide bonds is an important aspect in various fields such as biochemistry, pharmaceuticals, and materials science. Disulfide bonds are covalent bonds formed between two sulfur atoms and are commonly found in proteins, peptides, and other organic compounds. Breaking these bonds can be crucial for studying protein structure and function, as well as for developing drug delivery systems and materials with desired properties.There are several methods available to determine the ability to break disulfide bonds. One commonly used methodis the reduction of disulfide bonds using reducing agents such as dithiothreitol (DTT) or tris(2-carboxyethyl)phosphine (TCEP). These reducing agents donate electrons to the sulfur atoms, breaking the disulfide bonds and forming thiol groups. The reduction can be monitored using techniques such as UV-visible spectroscopy or high-performance liquid chromatography (HPLC). By comparing the reduction kinetics or the extent of reduction in the presence of different reducing agents, the relative ability to break disulfide bonds can be determined.Another method to determine the ability to break disulfide bonds is by enzymatic cleavage. Enzymes such as thioredoxin or glutaredoxin have the ability tospecifically cleave disulfide bonds. By incubating the protein or peptide of interest with the enzyme and monitoring the cleavage using techniques such as SDS-PAGEor mass spectrometry, the efficiency of disulfide bond cleavage can be assessed.In addition to these methods, computational modelingand molecular dynamics simulations can also provideinsights into the stability and breaking of disulfide bonds. By studying the bond lengths, angles, and energies, as well as the surrounding environment, the likelihood of disulfide bond breakage can be predicted.中文回答：断裂二硫键能力的测定在生物化学、药学和材料科学等领域中具有重要意义。

多肽二级质谱非特异切割

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通过这种质谱图，我们可以得知多肽的分子量、氨基酸序列和部分修饰信息等。

在多肽二级质谱中，常用的有碰撞诱导解离（CID）和离子喷雾解离（ISD）两种方式。

2.非特异切割非特异切割是多肽制备过程中常见的一种方式，它指的是在非特定位置对多肽链进行切割。

与特异切割相比，非特异切割通常不需要特定的切割位点，而是通过一定的物理或化学条件使多肽链断裂。

3.切割机制非特异切割的机制主要包括化学切割和物理切割两种方式。

化学切割主要依赖于化学试剂与多肽链的作用，使肽键断裂。

而物理切割则主要依靠物理力（如机械力）使多肽链断裂。

4.切割应用非特异切割在多肽研究中有广泛的应用，如多肽库的构建、多肽药物的研发等。

通过非特异切割，我们可以获得多肽的不同片段，从而得到更多的生物学信息。

此外，非特异切割还可以用于蛋白质组学的研究，帮助我们更深入地理解蛋白质的功能和修饰。

5.切割影响因素影响非特异切割的因素有很多，包括切割试剂的种类和浓度、切割温度、切割时间等。

此外，多肽的氨基酸序列和二级结构也会影响切割效果。

6.切割技术比较在多肽制备过程中，除了非特异切割外，还有许多其他的切割技术，如特异切割、酶解等。

这些技术各有优缺点，适用于不同的应用场景。

非特异切割具有操作简单、适用范围广等优点，但也有切割位点不确定、切割效率低等缺点。

特异切割具有切割位点明确、切割效率高等优点，但需要识别特定的切割位点，对实验条件的要求较高。

酶解法具有专一性强、切割效率高等优点，但需要使用特定的酶，成本较高。

7.未来发展趋势随着生物技术的发展，非特异切割技术也在不断进步和完善。

未来，非特异切割技术将朝着更加高效、准确和便捷的方向发展。

同时，随着蛋白质组学研究的深入，非特异切割技术在生物学研究和药物研发等领域的应用也将更加广泛。

微波烧结生物医用多孔Ti

微波烧结生物医用多孔Ti−23％Nb形状记忆合金的参数优化Mustafa K.IBRAHIM;E.HAMZAH;Safaa N.SAUD;E.M.NAZIM;A.BAHADOR【期刊名称】《中国有色金属学报（英文版）》【年(卷),期】2018(028)004【摘要】通过微波烧结成功制备多孔Tiα23％Nb（摩尔分数）形状记忆合金（SMA），其具有优异的外部精加工（没有空间夹持器）。

研究了微波烧结对微观结构，相组合物，相变温度，机械性能和形状记忆效应的影响。

结果表明，孔隙率的密度和尺寸基于烧结时间和温度，其中在900℃烧结30分钟后，用Tiα32％Nb SMA显示出最小尺寸和最均匀的孔形状。

多孔Ti的微观结构由针状和板状形态的主要α“，α和β相组成，它们的体积馏分基于烧结时间和温度而变化。

β相代表最大的阶段β稳定剂元素的含量较高，α和α阶段的强度很小。

最高的极限强度及其菌株显示在900℃下烧结30分钟的样品，而最佳的超弹性是在1200℃烧结的样品30分钟。

低弹性模量使这些合金能够避免“应力屏蔽”的问题。

因此，微波加热可用于烧结用于生物医学应用的Ti-合金，并改善这些合金的机械性能。

％In用品微波法成形设备多重Ti？23％NB（摩尔分数）形状融合金（SMA）（不含造孔剂）。

研微波烧结烧结合金显微，相相成，相变温度，力学性能和形状效应的影响。

结果结果明，烧结时间和温度对合金密度和大小的影响较大，在900℃下烧结30min的Ti？23％Nb Sma具有最小的孔径和最的孔形状。

多重Ti？Nb sma的显微组织主要含和α“，α和β相，且体分数随烧结时空和不合物变化。

由于β相稳定元素的传输高，因此β相销量更多，而α和α“相少.900℃烧结30min的装饰品应变，而1200℃烧结30min的装饰品则具高。

这些合金的弹性模较，可以避免“应力屏蔽”效应。

因此，微波加加可应应于烧结生物医t烧结烧结提高分子性能。

【总页数】11页(P700-710)【作者】Mustafa K.IBRAHIM;E.HAMZAH;SafaaN.SAUD;E.M.NAZIM;A.BAHADOR【作者单位】Faculty of Mechanical Engineering,Universiti Teknologi Malaysia,81310 UTM Johor Bahru,Johor,Malaysia;Faculty of Mechanical Engineering,Universiti Teknologi Malaysia,81310 UTM JohorBahru,Johor,Malaysia;Faculty of Information Sciences and Engineering,Management&Science University,40100 ShahAlam,Selangor,Malaysia;Faculty of Mechanical Engineering,Universiti Teknologi Malaysia,81310 UTM Johor Bahru,Johor,Malaysia;Faculty of Mechanical Engineering,Universiti Teknologi Malaysia,81310 UTM Johor Bahru,Johor,Malaysia【正文语种】中文因版权原因，仅展示原文概要，查看原文内容请购买。

我国主导又一国际标准立项填补氧化石墨烯结构表征领域空白

我国主导又一国际标准立项填补氧化石墨烯结构表征领域空白01近日，我国申报的石墨烯领域国际标准《氧化石墨烯结构表征：AFM和SEM测量厚度和横向尺寸》(英文名《Structure characterization of grapheme oxide flakes: thickness and lateral size measurement by AFM and SEM》)获得国际纳米技术委员会(ISO/TC229/JWG2)立项，标准号为ISO/AWI TS 23879。

据悉，该国际标准由常州检验检测标准认证研究院与中国计量科学研究院等四家单位联合起草，规定了原子力显微镜(AFM)测量氧化石墨烯厚度方法和扫描电镜(SEM)测试氧化石墨烯横向大小方法，填补了氧化石墨烯结构表征方面的国际空白。

该国际标准申报前期已进行10个国际实验室比对工作，预计2024年完成审批并发布。

石墨烯具有极其优异的力学性能、导电性能、导热性能、载流子迁移率、光学性能及阻隔性等，被发现后就成为材料学研究的热点。

而氧化石墨烯(graphene oxide，GO)是石墨烯的氧化物，一般用GO 表示。

相对于原始石墨烯，. 含氧基团的引入不仅使得氧化石墨烯具有化学稳定性，而且为合成石墨烯基/氧化石墨烯基材料提供表面修饰活性位置和较大的比表面积。

并且由于石墨烯片层骨架的基面和边缘上有多种含氧官能团共存的结构，使得氧化石墨烯可以通过调控所含含氧官能团的种类及数量，来调制其导电性和带隙。

同时氧化石墨烯的还原也是制备是石墨烯材料的主要方法。

将石墨氧化、超声剥离后得到氧化石墨烯(GO)，再将其还原成石墨烯，这就是制备石墨烯的氧化还原法。

这种方法成本低、产率高，是大量生产石墨烯的最佳途径之一。

研究氧化石墨烯的结构有助于开发氧化石墨烯在各个领域的应用，也有利于改进石墨烯的氧化还原法。

我国成功申报氧化石墨烯结构表征技术的国际标准，展示了我国在石墨烯研究领域的技术实力，提升了我国在石墨烯标准化研究领域的国际影响力。

模糊综合评价优化明胶基微胶囊配方参数的研究

3月出版模糊综合评价优化明胶基微胶囊配方参数的研究Study of fuzzy comprehensive evaluation in optimization for thematrix of gelatin-based microcapsule1*谢岩黎，女，1971年出生，2007年毕业于江南大学，博士,博士副教授。

收稿日期：2008-12-22摘要利用明胶和蔗糖为复合壁材，应用喷雾干燥技术制备V A 微胶囊，采用旋转中心组合设计，以微胶囊化效率、产率和保留率为评价微胶囊品质的指标，建立模糊综合评价体系，计算出模糊综合评价值，以模糊综合评价值为目标函数，利用SAS8.1统计分析软件对实验数据作回归拟合，并对方程求一阶偏导。

确定V A 微胶囊最佳配方参数为：壁材中明胶的比例为16.57g/100g ，芯材的载量24.51g/100g ，固形物含量为29.78g/100g 。

关键词明胶基；微胶囊；模糊综合评价；配方参数；优化Abstract Vitamin A microcapsules were prepared by spray drying and gelatin and sucrose were adopted as wall-material.Microencapsulation efficiency ，encapsu-lation yield and stability used as the evaluation index in the central composite rotatable design.The system of fuzzy comprehensive evaluation was established and cal-culated the fuzzy comprehensive evaluating index ，which was regressively analysed using SAS8.1package.The optimum parameters were obtained by monadic operator of regression equation,which were as follow:the rate of gelatin in the wall material was 16.57%,the core materi-al load (w/w%)was 24.51%and total solids concentration (w/v%)was 29.78%.Keywords gelatin-based ；microcapsule ；fuzzy com-prehensive evaluation ；matrix parameter ；optimizeV A 作为营养补充剂被广泛地应用于食品中，因为其性质不稳定，在食品加工和贮藏过程中的易损失。

荧光PCR熔解曲线法在耐多药结核病诊治中的应用及分析

荧光PCR熔解曲线法在耐多药结核病诊治中的应用及分析秦万;王明栋;欧维正;徐勇【期刊名称】《安徽医学》【年(卷),期】2024(45)2【摘要】目的探讨荧光聚合酶链反应(PCR)熔解曲线法在耐多药结核病(MDR-TB)的快速诊断和有效药物快速筛选中的应用价值。

方法以利福平(RFP)、异烟肼(INH)、乙胺丁醇(EMB)、氟喹诺酮类(FQs)为检测药物,应用熔解曲线法和微孔板药敏法,对比检测2021年1~7月贵阳市公共卫生救治中心罗氏固体培养阳性的84株菌株。

两种方法药敏结果不一致的菌株用基因测序法作验证。

结果以微孔板法为标准,熔解曲线法对MDR-TB(微孔板诊断)的检出符合率、灵敏度、特异度、阳性预测值、阴性预测值和Kappa值依次为89.3%(75/84)、91.5%(43/47)、86.5%(32/37)、89.6%(43/48)、88.9%(32/36)、0.78。

溶解曲线法对RFP、INH、EMB、FQs的检出符合率、灵敏度、特异度、阳性预测值、阴性预测值和Kappa值分别为76.2%~97.6%、86.7%~95.7%、73.9%~100%、41.9%~100%、94.1%~98.6%和0.45~0.95。

对22份(26.19%,22/84)微孔板法敏感、熔解曲线法耐药的菌株进行测序验证,结果均显示含有耐药突变;而微孔板法耐药、熔解曲线法敏感的6份(0.71%,6/84)菌株在测序区域均为野生型。

结论荧光PCR熔解曲线法对微孔板药敏法检测结果的灵敏度、特异度、符合率、一致性均较高,可为耐多药结核病的初筛诊断及治疗方案制定提供实验室依据。

【总页数】5页(P163-167)【作者】秦万;王明栋;欧维正;徐勇【作者单位】贵阳市公共卫生救治中心检验科【正文语种】中文【中图分类】R52【相关文献】1.荧光PCR熔解曲线法检测结核分枝杆菌耐利福平突变研究2.荧光 PCR 熔解曲线法快速检测耐多药结核菌的临床应用3.荧光PCR熔解曲线技术在结核病耐药诊断中的应用价值4.荧光PCR熔解曲线法检测耐多药肺结核患者对左氧氟沙星和莫西沙星耐药性的效能研究5.荧光PCR探针熔解曲线法检测结核分枝杆菌耐利福平突变研究因版权原因，仅展示原文概要，查看原文内容请购买。

TiO2-SiO2系统凝胶玻璃薄膜折射率的研究

TiO2-SiO2系统凝胶玻璃薄膜折射率的研究
TiO2-SiO2系统凝胶玻璃薄膜折射率的研究
应用光度法研究了溶胶-凝胶系统组成、热处理温度对TiO2-SiO2系统凝胶玻璃薄膜折射率的影响规律.随薄膜中TiO2含量的增加以及热处理温度的升高,薄膜的折射率逐渐增大.通过调整TiO2-SiO2系统的组成及适当的热处理温度,可实现TiO2-SiO2系统薄膜折射率在1.5～2.4之间的连续变化.
作者：樊先平郝霄鹏姚华文王民权作者单位：樊先平,王民权(浙江大学材料科学与工程学系,浙江,杭州,310027浙江大学硅材料国家重点实验室,浙江,杭州,310027)
郝霄鹏,姚华文(浙江大学材料科学与工程学系,浙江,杭州,310027) 刊名：功能材料ISTIC EI PKU英文刊名：JOURNAL OF FUNCTIONAL MATERIALS 年，卷(期)：2002 33(2) 分类号：O484.41 关键词：溶胶-凝胶折射率 TiO2-SiO2薄膜。

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