Theory and implementation of orthotropic materials in growing continua

Most biological tissues show a material behavior which is characterized through a pronounced anisotropy. In particular hard tissues such as bones or soft tissues as muscles are commonly modeled as either transversely isotropic or even orthotropic. In contrast to engineering materials, however, biological tissues possess the ability to adapt, e.g. their density, to the current loading situation. Based on a formulation for growth in isotropic continua, see for instance Kuhl, Menzel & Steinmann [3], and transversely isotropic continua as discussed e.g. in Himpel [2], we attend to a model for the functional adaption of orthotropic biomaterials. The material model has been implemented in a finite element code and is studied by means of a numerical example. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

离子基碳-氧键断裂能量的研究(Ⅱ)──负离子基的键能

合成了3个系列芳香类含碳一氧键的化合物,用循环伏安法测定了相关的氧化还原电势,通过热力学循环首次估测了负离子基的碳-氧键的断裂能量(ΔH_cleav[C-O]^·-).结果表明:得到1个电子形成负离子基可以活化碳-氧键。这与具有相同结构的正离子基的情况是一致的,但其活化程度略小。相关分析表明:ΔH_cleav[C-O]^·-vs(ΔE_red[C-O]+ΔpK_a[HA])和ΔH_cleav[C-O]^·+vs.(ΔBDE-ΔE_ox[C-O])均呈线性。讨论了负离子基和正离子基及其母体化合物中键的特征,并与文献中有关的键能数据进行了比较。     

(R)-α-烷基糠胺的立体控制合成

本文以2-羟基蒎烷-3-酮(1)为手性助剂, 经手性酮亚胺(3)的不对称烷基化反应, 立体控制合成了(R)-α-烷基糠胺(5)。反应的对映体过量值经手性毛细管柱色谱测定为91.4→98%。     

Crystal Structure of Ethyl 4-benzoyl-1a,2,3,4-tetrahydro-3-methyl-1a-(4-methylphenyl)-1H-azirino〔1,2-a〕〔1,5〕 benzodiazepine-1-carboxylate(C_(28)H_(28)N_2O_3)

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Adsorption of linear and star-shaped polyelectrolytes to monolayers of charged amphiphiles

Adsorption of polyelectrolytes has been studied employing monolayers of ionic amphiphiles at the air water interface as model surfaces. The adsorption of polyelectrolytes from a solution brought into contact with the amphiphile monolayer results in changes of the monolayer structure and properties. Monitoring these changes can be done by recording the changes in surface pressure. The kinetics of the adsorption depends strongly on the nature of the polyelectrolyte. Depending on the structure of the polyelectrolyte a purely diffusion controlled adsorption or a sequence of diffusion controlled adsorption and ordering processes have been identified to determine the kinetics. The influence of the molecular architecture on the polyelectrolyte adsorption has been further studied employing linear and star shaped poly(acrylic acid) and poly(N-propyl-4-vinyl pyridinium bromides), respectively. An unexpected behavior with an induction period in the adsorption kinetics of both polymers has been found. Furthermore, the degree of branching has only very minor effects on the adsorption kinetics.     

Investigation of PdSn-catalysts for nitrate removal in drinking water processing

PdSn catalysts prepared by various methods and used for nitrate reduction were investigated by means of in situ _119mSn Mössbauer spectroscopy. Characterization by ^119mSn Mössbauer spectroscopy revealed significant differences concerning the modification of the palladium particles supported on alumina. The controlled surface reaction preparation method (CSR) leads to formation of PdSn alloys with different tin contents besides small amounts of Sn(II) species and unalloyed metallic Sn. On the other hand the impregnation method leads to a small amount of PdSn alloys and higher contents of Sn(II) species. Sn(IV) species were found in both kinds of catalysts. The CSR prepared PdSn catalysts showed an improved activity and selectivity compared to the catalysts obtained by the impregnation method.     

粗糙模糊集的模糊性度量

研究粗糙模糊集的模糊性度量,提出了一种新的熵与条件熵的概念,并验证了这种熵与Shannon熵类似的性质。利用这种熵定义了粗糙模糊集的一种不确定性度量,证明了粗糙模糊集的模糊性度量FR（A）等于0的充分必要条件是A是经典集合且是可定义的。     

新型冠状病毒感染疫情下公众心理健康及影响因素研究进展

新型冠状病毒感染疫情是重大突发公共卫生事件,对全球公共心理健康产生了深远影响.本文对公众心理健康状况、影响心理健康水平的疫情因素(新型冠状病毒感染、隔离、失业和其他应激源)以及个人因素(青少年、女性、医护人员和既往有躯体/精神疾病史)进行综述,并从个人、社会、国家层面分析改善公众心理健康的对策,为应对疫情的长期影响提供参考.     

A Five-Membered Ring with Three Negative Charges and Solvent-Free Lithium Counterions

Remarkably short distances to the ring plane are shown by the η⁵-bound lithium ions in the first compound with a triply negatively charged five-membered ring, 1 , which was obtained by reduction of 2 with lithium. R=CH(SiMe₃)₂, Dur=2,3,5,6-tetramethylphenyl.