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Theoretical Investigation on Hyperfine Structures of Perfluoropolyether Radicals

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Chemical Research in Chinese Universities 2011年第1期27卷 117-122页

作者： DONG su-li LIU ya-jun Key Laboratory of Theoretical and Computational Photochemistry Ministry of Education College of Chemistry Beijing Normal University Beijing 100875 P. R. China

The geometries of CF3OCF2, CF3OCFCF3 and CF3OCF2CF2 radicals were investigated by density functional theory（DFT） method. The calculated results indicate that all the three radicals have pyramidal shapes at their centers, and the aC is one top of the pyramids. Based on the DFT optimized geometries, the hyperfine coupling constants（hfec＇s） of the 19F atoms of the three radicals were calculated by B3LYP, MP2（full） and QCISD（full） methods. The calculated values agree with the experimental values, especially for the a values of Fa, the a values are 125.6× 10 -4, 104.2× 10 - 4, and 83.2×10 -4 T of CF3OCF2, CF3OCFCF3 and CF3OCF2CF2, respectively. These results better explain the experimental observation.

关键词： Perfluoropolyether radical Hyperfine coupling constant Density functional theory

A microexplosive shockwave-based drug delivery microsystem for treating hard-to-reach areas in the human body

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Microsystems & Nanoengineering 2022年第5期8卷 137-148页

作者： Yi sun Wenzhong Lou Hengzhen Feng Wenting su Sining lv Science and Technology on Electromechanical Dynamic Control Laboratory School of Mechatronical EngineeringBeijing Institute of technologyBeijingChina Beijing Institute of Technology Chongqing Innovation Center ChongqingChina

Implantable drug-delivery microsystems have the capacity to locally meet therapeutic requirements by maximizing local drug efficacy and minimizing potential side *** internal organs of the human body including the esophagus,gastrointestinal tract,and respiratory tract,with anfractuos contours,all manifest with endoluminal lesions often located in a curved or zigzag *** ability of localized drug delivery for these organs using existing therapeutic modalities is *** a drug onto these areas and using the adhesion and water absorption properties of the drug powder to attach to lesion areas can provide effective *** study aimed to report the development and application of microsystems based on microshockwave delivery of *** devices comprised a warhead-like shell with a powder placed at the head of the device and a flexible rod that could be inserted at the *** devices had the capacity to deposit drugs on mucous membranes in curved or zigzag areas of organs in the *** explosive impact characteristics of the device during drug delivery were analyzed by numerical *** the experiment of drug delivery in pig intestines,we described the biosafety and drug delivery capacity of the *** anticipate that such microsystems could be applied to a range of endoluminal diseases in curved or zigzag regions of the human body while maximizing the on-target effects of drugs.

关键词： organs drugs curved

Significance and challenges of stereoselectivity assessing methods in drug metabolism

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Journal of Pharmaceutical Analysis 2016年第1期6卷 1-10页

作者： Zhuowei Shen Chuang lv su Zeng Institute of Drug Metabolism and Pharmaceutical Analysis Zhejiang Province Key Laboratory of Anti-Cancer Drug Research College of Pharmaceutical Sciences Zhejiang University Biogen Idec Cambridge

Stereoselectivity in drug metabolism can not only influence the pharmacological activities, tolerability, safety, and bioavailability of drugs directly, but also cause different kinds of drug-drug interactions. Thus, assessing stereoselectivity in drug metabolism is of great significance for pharmaceutical research and development （R＆D） and rational use in clinic. Although there are various methods available for assessing stereoselectivity in drug metabolism, many of them have shortcomings. The indirect method of chro- matographic methods can only be applicable to specific samples with functional groups to be derivatized or form complex with a chiral selector, while the direct method achieved by chiral stationary phases （CSPs） is expensive. As a detector of chromatographic methods, mass spectrometry （MS） is highly sen- sitive and specific, whereas the matrix interference is still a challenge to overcome. In addition, the use of nuclear magnetic resonance （NMR） and immunoassay in chiral analysis are worth noting. This review presents several typical examples of drug stereoselective metabolism and provides a literature-based evaluation on current chiral analytical techniques to show the significance and challenges of stereo- selectivity assessing methods in drug metabolism.

关键词： Enantiomer Chiral chromatography Capillary electrophoresis Mass spectrometry NMR Immunoassay

Fabricating functionally graded Fe-Cr-Co permanent magnetic alloys via laser powder bed fusion

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Journal of Iron and Steel Research International 2024年第3期31卷 729-737页

作者： ya-zhou He ya-qing Hou Peng Shen Hao Zhang Dong Zhou Hang su Central Iron and Steel Research Institute Co. Ltd.Beijing 100081China Material Digital R&D Center China Iron and Steel Research Institute Group Co.Ltd.Beijing 100081China

Laser powder bed fusion(LPBF)in-situ alloying technology offers the possibility to construct gradient materials with varied structures and *** graded Fe-Cr-Co permanent magnetic alloys were fabricated by LPBF and in-situ alloying mixed powders of Fe,Cr,and Co *** effects of different Fe,Cr and Co contents on the microstructure,magnetic properties and hardness of Fe-Cr-Co alloys prepared by LPBF were *** as-built Fe-Cr-Co alloys present a single body-centered-cubic phase and have a homogeneous distribution of *** mechanical properties and magnetic properties of the compositionally graded sample show a gradient *** the increase in Cr content,the Vickers hardness of the sample increases,and the saturation magnetization of the sample *** optimal magnetic properties in an isotropic state are given as coercivity HcB=21.65 kA/m,remanence Br=0.70 T and energy product(BH)_(max)=5.35 kJ/m^(3),which are comparable to or higher than the reported magnetic properties in an isotropic state prepared by traditional powder *** in-situ alloying technology has the potential to further explore Fe-Cr-Co magnetic materials,such as those consisting of multiple or more constituent elements,and to maximize the compositional flexibility of magnetic materials.

关键词： Fe-Cr-Co alloy Laser powder bed fusion In-situ alloying Functional material Magnetic property

Chain Dynamics Heterogeneity in Plasticized Poly(vinyl butyral)(PVB) as Elucidated by Solid-State NMR

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Chinese Journal of Polymer Science 2024年第1期42卷 113-124,I0010页

作者： Jing lv Xu Chen Zi-Shuo Wu ya-Hui Li Wei Chen National Synchrotron Radiation Laboratory Anhui Provincial Engineering Laboratory of Advanced Functional Polymer FilmCAS Key Laboratory of Soft Matter ChemistryUniversity of Scienceand Technology of ChinaHefei 230026China

The chain dynamics heterogeneity of the poly(vinyl butyral)(PVB) plasticized by triethylene glycol bis(2-ethylhexa noate)(TEG-EH) was investigated by various solid-state NMR *** plasticized PVB shows two domains in distinct molecular dynamics differences,namely,rigid and soft domains,where the latter is the plasticizer-rich *** time domain low field NMR was first used to investigate the dynamics heterogeneity of the plasticized PVB,and the results show the decreasing activated energy of components in the soft domain of plasticized PVB(E_a=20.2 kJ/mol) as compared with that of the pristine one(E_a=24.3 kJ/mol).Detailed dynamics heterogeneity was obtained by high-field NMR with site-specific *** quadrupole-echo ~2H-NMR was adopted to elucidate the dynamics heterogeneity of the vinyl alcohol(VA) units,where only the hydroxyl group of VA is *** ~1H-^(13)C WISE NMR spectra show that there is not much difference in the mobility of the VB unit in PVB with and without plasticizer,whereas the glass transition temperature differed by approximately 53℃.This is further supported by Torchia's T_1 relaxation *** origin of such an unusual phenomenon is attributed to the critical role of the remaining VA(~22%) in the soft domain,where the VA units locally aggregate through hydrogen ***,the existence of a mobility gradient in the VB unit has been ***,the mobility difference for VB with different stereo-geometry(meso or racemic conformation) is observed for the first *** indicates the importance of modulating the ratio of meso over racemic VB for controlling the macroscopic perfo rmance of PVB.

关键词： Poly(vinyl butyral) Dynamics heterogeneity Plasticizer Solid state NMR

Organoimido functionalized trinuclear gold(Ⅰ)clusters with fluorescent chromophore

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Rare Metals 2021年第6期40卷 1437-1442页

作者： Chun-Lin lv Chen-Huai yang Li-ya Liu Zhi-Cheng Zhang Key Laboratory of Ethnomedicine(Minzu University of China) Ministry of EducationBeijing 100081China School of Pharmacy and Center on Translational Neuroscience Minzu University of ChinaBeijing 100081China Tianjin Key Laboratory of Molecular Optoelectronic Sciences Department of ChemistrySchool of ScienceTianjin University&Collaborative Innovation Center of Chemical Science and EngineeringTianjin 300072China College of Life and Environmental Sciences Minzu University of ChinaBeijing 100081China

The post-functionalization of gold nanoclusters with organic molecules into organic-inorganic hybrid functional materials is an efficient approach to develop multifunctional *** introducing 1-pyrenamine and 3-aminofluoranthene into[O(AuPPh_(3))_(3)][BF_(4)]with a covalent bond,two novel organoimido functionalized trinuclear gold nanoclusters[C_(16)H_(9)N(AuPPh_(3))_(3)][BF_(4)](Au_(3)-P)and[C_(6)H_(4)-C_(10)H_(5)N(AuPPh_(3))_(3)][BF_(4)](Au_(3)-F)have been successfully *** structures have been determined by electrospray ionization mass spectroscopy(ESI-MS)and single-crystal X-ray diffraction(SC-XRD),and the photoluminescence properties have been investigated from both experimental and theoretical *** is found that the lowest-energy electronic transitions in the ultraviolet-visible(UV-Vis)absorption spectra of Au_(3)-P(403 nm)and Au_(3)-F(425 nm)exhibit a slight bathochromic shift compared to the corresponding transitions in the spectra of 1-pyrenamine and 3-aminofluoranthene,*** addition,the dichloromethane solutions of Au_(3)-P and Au_(3)-F complexes clearly display blue and yellowish-green fluorescence,*** results will help to design and prepare organic-inorganic nanocluster hybrid luminescent materials for potential applications in(bio)sensors,bioimaging and optoelectronic devices.

关键词： Nanoclusters Gold Organoimido Photoluminescence

High-temperature Thermo-oxidative Aging of Vulcanized Natural Rubber Nanocomposites:Evolution of Microstructure and Mechanical Properties

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Chinese Journal of Polymer Science 2023年第8期41卷 1287-1297,I0010页

作者： Zhou-Xian Li Yi-Ran Kong Xiang-Fei Chen ya-Jiang Huang ya-Dong lv Guang-Xian Li College of polymer science and engineering State key laboratory of polymer materials engineering of ChinaSichuan UniversityChengdu 610065China

The aging of natural rubber(NR)at high temperatures will seriously affect its service lifetime in many key *** the present work,the changes in microstructure and mechanical properties of semi-efficient vulcanized NR/carbon black(CB)vulcanizates during thermooxidative aging at high temperatures(150-200℃)and a moderate temperature(95℃)were *** high temperatures,a two-stage aging behavior,which was characteristic of a first rapid decline and then a continuous rise in the crosslinking density(ve),was identified and was found to be closely related to the depletion behavior of *** surface cracking behavior observed in the second stage of high-temperature aging was discussed in terms of the grafting reaction of macromolecular radicals on CB particles and thermal *** contrast,the aging of NR at moderate temperatures was much mild,which featured a continuous increase in ve and an oxidation mechanism dominated by peroxy radicals attacking double *** general,the mechanical properties of NR vulcanizates during high-temperature aging depended on the competition effects of structural evolution in the crosslinked network and oxidation-induced chain scission.

关键词： Natural rubber nanocomposites High-temperature Thermo-oxidative aging

Investigation on Metallurgical Factors Controlling Charpy Impact Toughness in 1Cr21Ni5Ti Duplex Stainless Steel

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Journal of Iron and Steel Research International 2009年第2期16卷 73-79页

作者： yaNG Zhuo-yue su Jie WANG ya-ming Institute of Structure Materials Central Iron and Steel Research Institute Beijing 100081 China Steel Tube Department China Iron and Steel Research Institute Group Beijing 100081 China

Based on the fact that toughness degradation occurred in 1Cr21Ni5Ti duplex stainless steel during slow cooling in a temperature interval of 400-600 ℃ following brazed welding, a simulated embrittlement treatment was utilized to evaluate its emhrittlement tendency. Accumulated experiences have shown that high Ti and A1 contents led frequently to severe toughness deterioration. To elucidate this phenomenon, four heats with various Ti and Al contents were prepared in laboratory-scale melts, which were used to investigate the inherent embrittlement nature. The results have shown that 550 ℃ aging led only to a modest toughness reduction, whereas, aging around 475 ℃ resulted in ferrite embrittlement, regardless of Ti, A1 levels. However, high Ti, A1 levels reduced the austenite phase, which, in the case of its inferior shape and distribution due to insufficient hot deformation, failed to resist cleavagetype cracks initiated in the ferrite phase. Increasing hot-forged areas reduction could modify the shape and distribution of austenite, resulting in the enhanced resistance of the austenite to the cleavage-type cracks, which have been confirmed to be beneficial for brittlement suppression of 1Cr21Ni5Ti duplex stainless steel.

关键词： 1Cr21Ni5Ti steel emhrittlement Ti content AI content impact toughness

Mechanism of high temperature reduction on iron carbide preparation with low-grade siderite

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Journal of Iron and Steel Research International 2022年第9期29卷 1357-1367页

作者： Dong Chen ya-nan lv Wei Zhao Fei-bao Wu Wei-ang Ying School of Iron and Steel Soochow UniversitySuzhou 215021JiangsuChina Department of Mechanical and Electrical Engineering Suzhou Institute of Industrial TechnologySuzhou 215104JiangsuChina

The carburization roasting followed by magnetic separation is a feasible method to utilize low-grade siderite *** order to enhance the carburization efficiency and separation effciency,high temperature reduction was carried out,and its mechanism was demonstrated by measuring carburization index,phase change,and microstructure under a carbon-sulfur infrared analyzer,an X-ray diffractometer,and a metallurgical *** results show that both the carburization effciency of siderite pellet and the separation efficiency of iron carbide from gangue are very ***,high temperature reduction is a useful way to enhance the carburization efficiency,as it can accelerate the reduction reaction rate and carburization reaction ***,high temperature reduction can improve the growth of iron carbide particle,promote the carburization efficiency,and strengthen the sodium modification reactions,thereby greatly accelerating the separation efficiency of iron carbide and *** the siderite pellets were reduced at 1050℃ for 90 min and carburized at 650℃ for 120 min,the carburization index of carburized pellets reached *** magnetic separation treatment,an electric furnace burden assaying 83.12 wt.%Fe and 6.96 wt.%C was prepared,and the corresponding iron recovery rate was 95.43%.The high temperature reduction is promisingly adopted to promote the utilization of low-grade siderite ores using carburization-magnetic separation technology.

关键词： Siderite High temperature reduction Carburization-Separation Iron carbide