Application of thiol‐ene click chemistry to preparation of functional polyethylene with high molecular weight and high polar group content: Influence of thiol structure and vinyl type on reactivity

A series of functional polyethylenes have been simply and efficiently synthesized via the combination of regioselective ethylene/5‐vinyl‐2‐norbornene (VNB) copolymerization using [PhNC(CF₃)CHCO(Ph)]₂TiCl₂ catalyst and following ultraviolet light initiated thiol‐ene click reaction. On treatment of ethylene/VNB copolymer with different thiols including mercaptoethanol, 1‐thioglycerol, methyl mercaptoacetate, methyl mercaptopropionate, 2‐mercaptoethylamine, mercaptoacetic acid, and mercaptopropanoic acid, various polar groups have been successfully introduced into the polyethylene. Except 2‐mercaptoethylamine, the functionalizations are quite efficient with the degree of functionalization higher than 94%, which is independent of thiol structure and double bond content. The content of polar group in functional polyethylene can be tuned in a wide range of 0–30 mol %. Gel permeation chromatography profiles indicate all functional polyethylenes that have very high molecular weights (160–336 kg/mol) with homogeneous formation. Besides, systematic investigation of the influence of vinyl type and thiol structure on reactivity has been also carried out. By treatment of mercaptoethanol with different copolymers (ethylene/VNB, ethylene/5‐ethylidene‐2‐norbornene, and ethylene/dicyclopentadiene copolymer), the order of vinyl reactivity can be summarized as terminal > internal > cyclic double bond. For different thiols, the reactivity has the sequence of SHCH₂COOH > SHCH₂COOCH₃ > SHCH₂CH₂COOH > SHCH₂CH₂COOCH₃ > SHCH₂CH(OH)CH₂OH > SHCH₂CH₂OH > SHCH₂CH₂NH₂, which is depended on the solubility and the electron‐withdrawing inductive effect of polar group. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Halogenated chamigrane sesquiterpenes from Laurencia okamurae

Three new halogenated chamigrane sesquiterpenes, laurokamin A (1), laurokamin B (2), and laurokamin C (3), and four known halogenated chamigrane sesquiterpenes, 10‐bromo‐α‐chamigrene (4), 10‐bromo‐β‐chamigrene (5), 2,10‐dibromo‐3‐chloro‐β‐chamigrene (6), and obtusane (7), were isolated from the marine red alga Laurencia okamurae collected from the coast of Rongcheng, China. The structures of these compounds were unambiguously identified by one‐ and two‐dimensional NMR and mass spectroscopic methods. The antimicrobial activity of compounds 1–3 was evaluated. Copyright © 2012 John Wiley & Sons, Ltd.     

Heck reaction catalyzed by a recyclable palladium supported on shell powder

A novel palladium catalyst supported on shell powder has been prepared, and its application to the Heck reaction of aryl iodides with olefins has been reported. The results showed that the novel catalyst had extremely high activities for the reactions with the average yield over 90%. Also, this catalyst showed excellent stability in Heck reactions, being reused three times. The catalyst was characterized by X‐ray powder diffraction and field‐emission scanned electron microscopy images, and the energy dispersive X‐ray analyzer. Copyright © 2010 John Wiley & Sons, Ltd.     

Overlapping and communication policies in product development

Shorter product life cycles in many industries impel firms to accelerate the product development process. Overlapping development stages, combined with frequent information exchange, is commonly regarded as a core technique for faster product development. However, overlapping and communication require additional resources and can be costly. We investigate the time-cost tradeoffs involved in concurrent product development to determine the optimal overlapping and communication strategies. The methodology was applied to a refrigerator development process in order to illustrate its utility.     

一种新型CO_2响应型肿瘤靶向药物传递载体

将透明质酸(HA)依次接枝1,12-二氨基十二烷和N,N-二甲基乙酰胺二甲缩醛(DADA),构建得到CO_2刺激响应的透明质酸-脒基(HA-ami)。为了考察其结构、CO_2刺激响应性、细胞水平作为药物载体的可行性和肿瘤靶向性,进行了结构表征、CO_2刺激响应性表征、细胞摄取、细胞毒性和体内的组织分布实验。结果表明:HA-ami成功构建,并具有一定的CO_2刺激响应性,可携带模型药物摄取进入人乳腺癌细胞(MCF-7),而且没有出现明显的细胞毒性,具有体内肿瘤靶向性。     

New oxidized sterols from Aspergillus awamori and the endo‐boat conformation adopted by the cyclohexene oxide system

Two new oxidized sterols 1 and 2 were obtained from the active fraction of a mangrove fungus Aspergillus awamori isolated from the soils around the mangrove plant Acrostichum speciosum. Their structures were elucidated using spectroscopic methods as 22E‐7α‐methoxy‐5α,6α‐epoxyergosta‐8(14),22‐dien‐3β‐ol (1) and 22E‐3β‐hydroxy‐5α,6α,8α,14α‐diepoxyergosta‐22‐en‐7‐one (2). The NMR data and complete assignments for both DMSO‐d₆ and CDCl₃ were given. Their cytotoxic activity against A549 cell line was evaluated. Furthermore, the detailed conformation analysis for ring B (cyclohexene oxide system) of sterol 1 was given on the basis of NOEs. The endo‐boat conformation was considered as the preferred conformation for ring B rather than half‐chair conformation. Copyright © 2009 John Wiley & Sons, Ltd.     

The electrodynamics of rod-like microparticles based on optically induced dielectrophoresis

Due to its characteristics of noncontact, non-damage, high flux, and easy-to-achieve flexible manipulation, optically induced dielectrophoresis (ODEP) technology has been employed to manipulate microspherical biological particles, including separation, enrichment, capture, arrangement, and fusion. However, in nature, biomolecules are morphologically diverse, and some of them are rodlike. In order to illustrate the electrodynamics of rodlike particles under the action of ODEP, a transient multi-physical field coupling model of ODEP chip under the hypothesis of electrical double layer thin layer was established in this paper. The arbitrary Lagrangian–Eulerian method is used to track single-rod particle in the strong coupled flow field and electric field simultaneously. The influence of several key factors, including the applied alternating current (AC) electric voltage, the width of optical bright area, and the initial position of particle, on the trajectory of particle center was analyzed in positive dielectrophoresis (DEP) action and negative DEP action, respectively. Especially, the planar motion process of rodlike particles was discussed together. The research results reveal the electrodynamics behavior of rodlike particles based on the action of ODEP, which may provide theoretical support for the further design of rodlike biological cells manipulation chip based on AC ODEP technology in the future.     

Synthesis and ethylene oligomerization behavior of trinuclear nickel complex with phosphorus dendrimer

Transition Metal Chemistry - A phosphorus dendrimer with multiple amino groups was synthesized via a two-step reaction with phosphonitrilic chloride trimer and 4-acetamidophenol. The trinuclear...