Immobilization of glucose oxidase with the blend of regenerated silk fibroin and poly(vinyl alcohol) and its application to a 1,1′- dimethylferrocene-mediating glucose sensor

The structure and properties of the blend of regenerated silk fibroin (RSF) and poly(vinyl alcohol) (PVA) were investigated. The two polymers in the blend are in the state of phase segregation. Infrared (IR) spectra indicate that the RSF in the blend maintains its intrinsic properties, thus, ethanol treatment can transfer silk I structure of RSF to silk II structure. The water absorption property and mechanical property of the blend are improved in comparison with those of RSF. The blend maintains the major merit of RSF, that is, it can immobilize glucose oxidase on the basis of the conformational transition from silk I structure to silk II structure. The properties of the immobilized enzyme are examined. Moreover, the second generation of glucose sensor based on the immobilized enzyme is fabricated and it has a variety of advantages including easy maintenance of enzyme, simplicity of construction, fast response time and high stability.     

Failure of elastomeric polymers due to rate dependent bond rupture

A new cohesive zone model is developed in order to study the mechanisms of adhesive and cohesive failures of soft rubbery materials. The fracture energy is estimated here using a strategy similar to that of Lake and Thomas (LT) by considering the dissipation of stored elastic energy followed by the extension and relaxation of polymer chains. The current model, however, departs from that of LT in that the force needed to break an interfacial bond does not have a fixed value; instead, it depends on the thermal state of the system and the rate at which the force is transmitted to the bond. While the force required to rupture a chain is set by the rules of thermomechanically activated bond dissociation kinetics, extension of a polymer chain is modeled within both the linear and nonlinear models of chain elasticity. Closed form asymptotic solutions are obtained for the dependence of crack propagation speed on the energy release rate, which are valid in two regimes: (I) slow crack velocity or short relaxation time for bond dissociation; (II) fast crack velocity or long relaxation time for bond dissociation. The rate independent and the zero temperature limit of this theory correctly reduces to the fracture model of LT. Detailed comparisons are made with a previous work by Chaudhury et al. which carried out an approximate analysis of the same problem.     

A new isocoumarin from bark of Pellodendron chinense

A new isocoumarin, 3-acetyl-3,4-dihydro-5,6-dimethoxy-1H-2-benzopyran-1-one, was isolated from the cortex of Phellodendron chinense schneid. The structure was determined on the basis of spectroscopic evidences.     

Synthesis,crystal structure,electrochemical properties and large optical limiting effect of a novel 3-(E)-ferrocenyl-vinyl-<Emphasis Type="BoldItalic">N</Emphasis>-hexyl carbazole

The novel compound, 3-(E)-ferrocenyl-vinyl-N-hexylcarbazole (FVHC) was first synthesized and fully characterized by elemental analysis, IR, ¹H-NMR, single-crystal X-ray diffraction, ultraviolet (UV) absorption, cyclic voltammograms (CV) and optical limiting (OL) measurements. The result of single crystal X-ray diffraction for the compound reveals that the ferrocenyl and carbazole groups are approximately coplanar, and bridged by double-bond with E configuration, showing that there is a well-delocalized π-electron system in the molecule. The electrochemical investigation indicated that the electron in the FVHC may partially be delocalized over the π-conjugated system and CT process in functionalized carbazole systems. Besides, the compound exhibited strong UV absorption and large optical limiting effect, indicating promising potential applications as useful OL materials.     

Staphylionosides A-K: megastigmane glucosides from the leaves of Staphylea bumalda DC

Chemical investigation of leaves of Staphylea bumalda DC., collected in the suburbs of Hiroshima City, afforded 11 new megastigmane glucosides, named staphylionosides A-K (3-13), along with two known megastigmane glucosides (1, 2). The relative structures were elucidated from spectroscopic evidence, and the absolute structures of the aglycones were determined by means of the combination of beta-D-glucosylation-induced shift-trends and the modified Mosher's method.     

Synthesis, antitumor and DNA photocleaving activities of novel naphthalene carboxamides: effects of different thio-heterocyclic rings and aminoalkyl side chains

Two kinds of thio-heterocyclic fused naphthalene carboxamides, 3a-b, 4a-b, were designed, synthesized and quantitatively evaluated as efficient antitumor and DNA photocleaving agents. Compound 3a or 3b, having the thiophene ring, intercalated into DNA more strongly than compound 4a or 4b, having the thioxanthene ring. Compound 4a or 4b, photocleaved DNA more efficiently than 3a or 3b via superoxide anion. Compound 4a was the strongest inhibitor for P388 (murine leukemia cell), while 3a was the most cytotoxic one against A549 (human lung cancer cell). Each new compound showed stronger DNA photocleaving activity than corresponding naphthalimide.     

全硅FER沸石上有机吸附物脱附行为的研究

运用热分析技术,研究吸附在体相和表面结构完美的单晶状疏水全硅FER沸石孔道中的有机化合物的脱附行为,测定亲和性指数AT值和负载量。所研究的吸附质为直链烷烃、直链烷基醇、直链烷基胺等,结果显示醇有较低的AT值,而直链烷烃有较高的AT值,胺类有最高的AT值。证明全硅FER沸石骨架对烷基、胺基呈现出强的"亲和性",而对羟基呈现出“憎性”。同时还发现吸附质的链长对脱附性质、AT值也有较大影响。     

Tweezer分子的合成和对有机阴离子的配位效应

本文报道新的Ｔｗｅｅｚｅｒ（１）的合成，用＾１ＨＮＭＲ研究了新的Ｔｗｅｅｚｅｒ分子和对硝基苯甲酸盐的配位效应，结果表明它兴通过氢键，静电引力和芳环夹心堆叠作用而自动缔合。     

Four new triterpene glycosides from Thalictrum squarrosum

Four new triterpene glycosides were isolated from the dried aerial parts of Thalictrum squarrosum (Ranunculaceae). They were designated as squarroside I, being a cycloartane-type glycoside, and squarrosides II, III and IV, being oleanene-type glycosides. Their structures were established by using two dimensional (2D) NMR techniques.     

A Novel Polyoxovanadium Cluster Shell: β‐As8V14O42

The hydrothermal reaction of VOSO₄, As₂O₅, piperazine and H₂O produces [H₂N(CH₂)₄NH₂]₄[β‐As₈V₁₄O₄₂(SO₄)]·2HSO₄ ( 1 ), which is the first arsenic‐vanadium cluster containing a spherical β‐As₈V₁₄O₄₂ shell. The structure of this compound was characterized by single crystal X‐ray diffraction, elemental analysis, TG, and IR spectrum. Crystal data for 1 : Orthorhombic, Cmcm, a = 15.369(1) Å, b = 16.404(1) Å, c = 25.772(1) Å, V = 6497.4(9) ų, Z = 4.