壳聚糖及其疏水衍生物自缔合行为

过去几十年里,有关疏水改性聚电解质的理论和应用研究取得了长足的进展,通常认为其不同寻常的流变及溶解特性是由疏水基团的分子间或分子内相互作用产生的.本文综述了近年来有关壳聚糖及脱氧胆酸、烷基化和棕榈酰改性壳聚糖衍生物自缔合性质的研究进展,并简要介绍它们在药物释放和转基因领域的应用研究.     

Two cobalt(II) 5-aminoisophthalate complexes and their stable supramolecular microporous frameworks

Two stable supramolecular microporous cobalt(II) polymers, namely [Co(HAIP)2]n.3nH2O (1) and [Co(AIP)(H2O)]n (2), AIP = 5-aminoisophthalate, were hydrothermally synthesized and characterized by single-crystal X-ray diffraction, IR spectra, thermogravimetric analyses, and variable-temperature magnetic susceptibility measurements. The two complexes are constructed from the same Co2(CO2)2 SBU, which is extended into a 1D chain in 1 and a 2D layer in 2. As a result, 1 and 2 are 2D and 3D coordination polymers, respectively. The 3D supramolecular network of complex 1 is held up by strong hydrogen bonds formed between carboxylate groups and shows very high stability when the free H2O molecules are removed, indicating an extraordinarily stable H-bonding system. Upon water ligands being liberated, complex 2 becomes a stable microporous solid with coordination-unsaturated Co centers. The behavior of the susceptibility curve of 1 suggests the occurrence of an interesting intrachain antiferromagnetic coupling between the Co(II) ions and the presence of a significant orbital contribution, whereas the features of 2 indicate an antiferromagnetic coupling with T(N) = 3.5 K and a long-range antiferromagnetic order with a field-induced magnetic transition.     

蟹,虾壳微观形貌与结构研究

用Ｘ射线衍射与扫描电镜研究了蟹壳，虾壳的形貌与微观结构，蟹壳中以方解石晶型存在的碳酸钙分布在网状结构的有机质中，网孔的尺寸约５～２５μｍ有机基质脱去蛋白后留下的甲壳质呈片层状结构，它的重复距离为０．９６ｎｍ。     

Analysis of alkaloids in Macleaya cordata (Willd.) R. Br. using high-performance liquid chromatography with diode array detection and electrospray ionization mass spectrometry

A method for the analysis of alkaloids in Macleaya cordata (Willd.) R. Br. using high-performance liquid chromatography with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI/MS) was developed. Using protopine (PRO), allocryptopine (ALL), sanguinarine (SA), and chelerythrine (CHE) as the model components, different columns for the separation and different mobile phases for the signal intensities of alkaloids in ESI/MS were investigated, respectively. The results showed that good separation and high signal intensities can be obtained on a high carbon loading (17%) reversed-phase C(18) column with 30 mM formic acid in mobile phase for the analysis of alkaloids. Under the optimal separation condition and UV detection (284 nm), linearity of the six alkaloids was obtained over concentration range from 0.05 to 100.00 microg/ml. The limit of detection (LOD) was 1.62, 1.87, 1.79, 1.76, 1.10, and 0.94 ng/ml for SA, CHE, PRO, ALL, dihydrosanguinarine (DHSA), and dihydrochelerythrine (DHCHE), respectively. The LODs with ESI/MS detection were lower three orders of magnitude than those obtained with UV detection. The proposed method could be used to control quality of the raw materials of the herb more comprehensively.     

Construction of aromatic [5,5] spiroketals via hypoiodite-catalyzed etherification combined in relay cascades

An approach is developed for the synthesis of bisbenzannelated spiro[5,5]ketals via a catalytic relay reaction cascade involving a new cyclo-etherification, which is prompted by fluoride and catalyzed by the hypoiodite species generated in situ from irradiative aerobic oxidation of an iodide ion formed in the former step of the reaction cascade.     

BEM for simulation of a 2D elastic body with randomly distributed circular inclusions

Based on our 2D BEM software THBEM2 which can be applied to the simulation of an elastic body with randomly distributed identical circular holes, a scheme of BEM for the simulation of elastic bodies with randomly distributed circular inclusions is proposed. The numerical examples given show that the boundary element method is more accurate and more effective than the finite element method for such a problem. The scheme presented can also be successfully used to estimate the effective elastic properties of composite materials. Project supported by the National Natural Science Foundation of China (No. 19772025).     

TiB2增强Al2O3陶瓷刀具高速干切削摩擦磨损性能

采用TiB2增强Al2O3陶瓷刀具对淬硬钢进行高速干切削试验,利用切削高温作用下的摩擦化学反应,在刀具表面原位生成具有润滑作用的反应膜,从而实现Al2O3/TiB2陶瓷刀具的自润滑.结果表明:低速干切削时,Al2O3/TiB2陶瓷刀具的磨损机制主要表现为粘着磨损和磨料磨损;而在高速干切削时,刀具的磨损机制主要表现为氧化磨损,刀具表面经由氧化反应生成具有润滑作用的反应膜而起到固体润滑作用,从而使刀具的耐磨性能提高,随着TiB2含量和切削速度的增加,反应膜的减摩抗磨作用增强;而在切削区通入氮气时,由于刀具表面氧化膜形成受阻,刀具的抗磨能力有所降低.     

Saprophytic Bacillus Accelerates the Release of Effective Components in Agarwood by Degrading Cellulose

The value of Agarwood increases with time due to the gradual release of its major components, but the mechanism behind this remains unclear. Herein we reveal that the potential driving force of this process is the degradation of cellulose in Agarwood by its saprophytic Bacillus subtilis. We selected 10-year-old Agarwood from different places and then isolated the saprophytic bacteria. We confirmed these bacteria from different sources are all Bacillus and confirmed they can degrade cellulose, and the highest cellulase activity reached 0.22 U/mL. By co-cultivation of the bacterium and Agarwood powder, we found that three of the strains could release the effective components of Agarwood, while they had little effect in increasing the same components in living Aquilaria sinensis. Finally, we demonstrated that these saprophytic Bacillus subtilis have similar effects on Zanthoxylum bungeanum Maxim and Dalbergiaod orifera T. Chen, but not on Illicium verum Hook. f, Cinnamomum cassia Presl and Phellodendron chinense Schneid. In conclusion, our experiment revealed that the saprophytic Bacillus release the effective components of Agarwood by degrading cellulose, and we provide a promising way to accelerate this process by using this bacterial agent.     

Mg/Cd共掺杂ZnO电子结构与光学性质的第一性原理研究

采用基于密度泛函理论的第一性原理平面波超软赝势法,研究了Mg/Cd(不同的Cd浓度)共掺杂ZnO的电子结构和光学性质.研究表明:Mg/Cd共掺杂ZnO,体系的晶胞尺寸变大,但结构稳定.当Mg/Cd为1:1时,吸收边略微发生蓝移.随Cd的掺杂浓度增加,导带部分逐渐下移,禁带宽度变窄,出现红移现象.除此之外体系的吸收率和反射率也减小.说明Mg/Cd共掺杂ZnO,不仅使得体系光学谱丰富,而且透射性增强.这对实验中制备出高透射率的材料具有一定的指导意义.     

Active Control of Thermo-mechanical Buckling of Composite Laminated Plates Using Piezoelectric Actuators

This paper is concerned with the active control of thermo-mechanical buckling of composite laminated plates using piezoelectric facesheets as actuators.The four...