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Chemical Synthesis of an Octasaccharide Derivative Related to Group B Streptococcus Cell-Wall Polysaccharide

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Chinese Journal of Chemistry 2023年第2期41卷 151-158页

作者： Chongzhen Sun Zhaojun Liu Wuxian Zeng xiaolin ma Guirong Wang Guofeng Gu National Glycoengineering Research Center and Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology Shandong University72 Binhai RoadQingdaoShandong 266237China NMPA Key Laboratory for Quality Research and Evaluation of Carbohydrate-based Medicine Shandong University72 Binhai RoadQingdaoShandong 266237China

Group B Streptococcus(GBS)is the major pathogen that causes invasive infectious diseases in neonates and *** develop-ment of preventive and therapeutic strategies against GBS infection has been becoming the most pressing subject *** B carbohydrate(GBC),the group B-specific polysaccharide that distinguishes GBS with other streptococci species,has been identified as an attractive antigen for diagnosis and vaccine development because of its highly conservative tetra-antennary *** this paper,a highly convergent[3+5]glycosylation strategy for efficient synthesis of an octasaccharide derivative related to GBC oligo-saccharide unitⅡhas been *** this synthesis,each glycosylation reaction was efficiently constructed with glycosyl im-idates,especially trifluoroacetimidate,as donors,and each glycosidic bond was stereoselectively controlled via the neighboring group participation effect of acyl group on the 2-O-position of imidate donors or the solvent effect of Et_(2)***,the ami-noethylphosphate group was smoothly installed on the 6-O-position of D-glucitoll residue using the phosphoramidite *** global deprotection,the target octasaccharide was successfully obtained from o-glucitol in 29 steps with an overall yield of 1.37%.The free amino group installed on the aminoethylphosphate spacer of the target molecule enables its modification with functional-ized biomolecules for further biological studies.

关键词： Carbohydrate Oligosaccharide Glycosylation Chemical synthesis Group B carbohydrate

Influence of layer thickness on formation quality,microstructure,mechanical properties,and corrosion resistance of WE43 magnesium alloy fabricated by laser powder bed fusion

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Journal of magnesium and Alloys 2024年第4期12卷 1367-1385页

作者： Bangzhao Yin Jinge Liu Bo Peng Mengran Zhou Bingchuan Liu xiaolin ma Caimei Wang Peng Wen Yun Tian Yufeng Zheng State Key Laboratory of Tribology in Advanced Equipment Beijing100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Institute for Precision Medicine Tsinghua UniversityBeijing102218China Department of Orthopaedics Peking University Third HospitalBeijing 100191China Beijing AKEC Medical Co. Ltd.Beijing 102200China School of materials Science and Engineering Peking UniversityBeijing 100871China Engineering Research Center of Bone and Joint Precision Medicine Ministry of EducationBeijing 100191China

Laser powder bed fusion(L-PBF)of Mg alloys has provided tremendous opportunities for customized production of aeronautical and medical *** thickness(LT)is of great significance to the L-PBF process but has not been studied for Mg *** this study,WE43 Mg alloy bulk cubes,porous scaffolds,and thin walls with layer thicknesses of 10,20,30,and 40μm were *** required laser energy input increased with increasing layer thickness and was different for the bulk cubes and porous *** tended to occur at the connection joints in porous scaffolds for LT40 and could be eliminated by reducing the laser energy *** thin wall parts,a large overhang angle or a small wall thickness resulted in porosity when a large layer thicknesses was used,and the porosity disappeared by reducing the layer thickness or laser energy input.A deeper keyhole penetration was found in all occasions with porosity,explaining the influence of layer thickness,geometrical structure,and laser energy input on the *** the samples achieved a high fusion quality with a relative density of over 99.5%using the optimized laser energy *** increased layer thickness resulted to more precipitation phases,finer grain sizes and decreased grain *** the similar high fusion quality,the tensile strength and elongation of bulk samples were significantly improved from 257 MPa and 1.41%with the 10μm layer to 287 MPa and 15.12%with the 40μm layer,in accordance with the microstructural *** effect of layer thickness on the compressive properties of porous scaffolds was ***,the corrosion rate of bulk samples accelerated with increasing the layer thickness,mainly attributed to the increased number of precipitation phases.

关键词： magnesium alloy WE43 Laser powder bed fusion Layer thickness Process optimization

Improving corrosion resistance of additively manufactured WE43 magnesium alloy by high temperature oxidation for biodegradable applications

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Journal of magnesium and Alloys 2024年第3期12卷 940-953页

作者： Jinge Liu Bangzhao Yin Fei Song Bingchuan Liu Bo Peng Peng Wen Yun Tian Yufeng Zheng xiaolin ma Caimei Wang State Key Laboratory of Tribology in Advanced Equipment Beijing100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Department of Orthopaedics Beijing Tsinghua Changgung HospitalInstitute for Precision MedicineTsinghua UniversityBeijing102218China Department of Orthopaedics Peking University Third HospitalBeijing 100191China Engineering Research Center of Bone and Joint Precision Medicine Ministry of EducationBeijing 100191China School of materials Science and Engineering Peking UniversityBeijing 100871China Beijing AKEC Medical Co. Ltd.Beijing 102200China

Laser powder bed fusion(L-PBF)has been employed to additively manufacture WE43 magnesium(Mg)alloy biodegradable implants,but WE43 L-PBF samples exhibit excessively rapid *** this work,dense WE43 L-PBF samples were built with the relativity density reaching 99.9%.High temperature oxidation was performed on the L-PBF samples in circulating air via various heating temperatures and holding *** oxidation and diffusion at the elevated temperature generated a gradient structure composed of an oxide layer at the surface,a transition layer in the middle and the *** oxide layer consisted of rare earth(RE)oxides,and became dense and thick with increasing the holding *** matrix was composed ofα-Mg,RE oxides and Mg_(24)RE_(5) *** precipitates almost disappeared in the transition *** passivation effect was observed in the samples treated by a suitable high temperature *** original L-PBF samples lost 40%weight after 3-day immersion in Hank’s solution,and broke into fragments after 7-day *** casted and solution treated samples lost roughly half of the weight after 28-day *** high temperature oxidation samples,which were heated at 525℃ for 8 h,kept the structural integrity,and lost only 6.88%weight after 28-day *** substantially improved corrosion resistance was contributed to the gradient structure at the *** one hand,the outmost dense layer of RE oxides isolated the corrosive medium;on the other hand,the transition layer considerably inhibited the corrosion owing to the lack of ***,high temperature oxidation provides an efficient,economic and safe approach to inhibit the corrosion of WE43 L-PBF samples,and has promising prospects for future clinical applications.

关键词： Laser powder bed fusion Biodegradable magnesium alloy High temperature oxidation Corrosion resistance WE43.

Let the Bullet Trains Fly

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Beijing Review 2015年第36期58卷 22-23页

作者： ma xiaolin

Will China be able to outstrip Japan＇s established railway technology in the race for the Indonesian market？

关键词：中国经济经济增长经济建设国民收入

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A Turning Point?

Beijing Review 2016年第46期59卷 26-27页

作者： ma xiaolin Beijing Review

Improving relations between China and some of its neighbors cool tension in the South China Sea By ma xiaolin Viet Nam and the Philippines have taken pragmatic steps to mend ties with China after new administrations t... 详细信息

关键词：英语阅读理解越南总理

IMPETUS FOR PEACE &DEVELOPMENT

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Beijing Review 2016年第5期59卷 16-19页

作者： ma xiaolin Beijing Foreign Studies University

Chinese President Xi Jinping kicked-off his 2016 diplomatic schedule with state visits to Saudi Arabia, Egypt and Iran on January 19-23. It was his first trip to these countries since taking office in march 2013.

关键词：中国经济经济增长经济建设改革开放

Paying With Blood for Peace

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ChinAfrica 2016年第6期8卷 10-11页

作者： ma xiaolin Beijing Foreign Studies University

A Chinese peacekeeper was killed and five others were injured when a car bomb struck a UN mission camp in mali on may 31, the latest in a string of terror attacks. ma xiaolin, Professor of International Studies at Beijing Foreign Studies University, says with China assuming a greater role in UN peacekeeping missions, as expected by the international community, Chinese policymakers should urgently assess the risks for their peacekeepers in today＇s complex and varied environment. His ideas follow：

关键词： UN Paying With Blood for Peace

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A Painful Lesson

Beijing Review 2015年第43期58卷 26-27页

作者： ma xiaolin

The migrant crisis has a deep root in Western intervention in the Middle East

关键词：中国经济经济增长经济建设国民收入对外关系

The Chaos in Yemer--Will the Saudi-led multinational forces put an end to the Yemeni conflict？

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Beijing Review 2015年第39期58卷 28-29页

作者： ma xiaolin

Six Arabic countries, including Egypt, Jordan, Morocco, Sudan, Qatar and Kuwait, agreed on September 6 to join ground forces led by Saudi Arabia to try and defeat the Houthi militias in Yemen. With more multinational troops participating in ground battles to retake the Yemeni capital Sanaa, the situation in the war-torn country is expected to undergo decisive changes.

关键词：地面部队 LED 也门阿拉伯国家沙特混沌地面作战摩洛哥