Catanionic surfactants assisted synthesis of dilead pentaoxochromate nanorods

Single‐crystalline dilead pentaoxochromate (Pb₂CrO₅) with nanorod‐shape has been synthesized by adjusting the pH value of the catanionic reverse micelles formed by a cationic surfactant CTAB (hexadecyltrimethylammonium bromide) and an anionic surfactant SDS (sodium dodecyl sulfonate), followed by a hydrothermal process. The results show that reaction parameters play important roles in the formation of the single‐crystalline Pb₂CrO₅. The reaction parameters include the kinds of the surfactants, the molar ratio (r) between the mixed cationic and anionic surfactants, reaction time and temperature. The as‐synthesized products are characterized by transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM) and powder X‐ray diffraction (XRD). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Qualitative and Quantitative Analysis of Microbial Transformation of Steroidal Saponins in Dioscorea zingiberensis

Diosgenin is an important starting material in the steroidal hormone industry. In this paper diosgenin was obtained by biotransformation of steroidal saponins in Dioscorea zingiberensis with the fungus Aspergillus oryzae. In the pre- and post-biotransformed samples, five main steroidal saponins and the aglycone (diosgenin) were identified by evaporative light scattering detector. An LC-UV quantification method for them was established by using C18 column and a mobile phase of aqueous acetonitrile. By means of this method, a good linearity (r > 0.9995) and recovery of the analytes (97.5–101.3%) were obtained for all the compounds. During biotransformation, the sugar chains of saponins were hydrolyzed and the content of the hydrolyzed product (diosgenin) increased 16 times after 84 h fermentation.     

Superconvergence of finite volume methods for the Stokes equations

A general superconvergence result of finite volume method for the Stokes equations is obtained by using a L² projection post‐processing technique. This superconvergence result can be applied to different finite volume methods and to general quasi‐uniform meshes.© 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2009     

基于关键链方法的多项目共享人力资源均衡问题及其遗传算法

通过对多项目管理瓶颈的分析,结合关键链方法,设置了瓶颈缓冲,建立了基于关键链方法的多项目管理,为多项目管理提供了一种新的管理方法.将基于关键链方法的多项目管理方法应用于并行多项目共享人力资源冲突管理,建立了基于遗传算法的多项目共享人力资源均衡模型,为缓解多项目共享人力资源供求矛盾提供了一种具体的量化管理方法,并进行了算例分析,证明了模型的有效性、实用性.     

DBD在原子光谱领域内的应用进展

介质阻挡放电因其体积小、结构简单、能耗低、工作温度低、样品解离/激发能力强等显著特点,特别适合于分析仪器的微型化和便携化。目前,基于介质阻挡放电的原子化器或激发光源已成功应用于原子吸收光谱仪、原子荧光光谱仪和原子发射光谱仪中,促进了小型化原子光谱仪器的发展。总结了介质阻挡放电技术在原子光谱领域内的研究进展,着重阐述了介质阻挡放电-原子发射光谱系统在不同进样方式下的应用情况,分析了每种进样方式的优缺点。本文还对介质阻挡放电技术在诱导蒸气发生、固体直接进样方面的新应用方向进行了评述。虽然介质阻挡放电技术已在原子光谱领域内得到广泛的应用,但其反应机理仍然不明确,制约了其后续的拓展研究。     

Hereditary effects of exponentially damped oscillators with past histories

This paper presents hereditary effects of exponentially damped oscillators with past histories. Unlike the classical viscously damped oscillators, the nonviscously damped ones involve damping forces which depend on time-histories of vibrating motions via convolution integrals. As a result, equations of motion of such systems are a set of coupled second-order Volterra integro-differential equations. In this work, initial value problems for the integro-differential equations are revisited. The initial conditions should contain time-histories of vibrating motions. Then, initialization response of exponentially damped oscillators is obtained. It is used to characterize the hereditary effects on the dynamic response. At last, stability of initialization response is proved from the theoretical viewpoint and verified by numerical simulations. This reveals that the hereditary effects gradually recede with increasing of time.     

Relationship between mass discharge rate and granular temperature of silo flow with variance of outlets

A lower granular temperature zone near the orifice in silos was found by speckle visibility spectroscopy technology.Surprisingly,the values of granular temperat...     

$\alpha$-可分解4-圈系统

An m-cycle system of order v and index λ, denoted by m-CS（v,λ）, is a collection of cycles of length m whose edges partition the edges of λKv. An m-CS（v,λ） is α-resolvable if its cycles can be partitioned into classes such that each point of the design occurs in precisely α cycles in each class. The necessary conditions for the existence of such a design are m｜λv（v-1）/2,2｜λ（v -1）,m｜αv,α｜λ（v-1）/2. It is shown in this paper that these conditions are also sufficient when m = 4.     

Cubic Mesoporous Titanium Phosphonates with Multifunctionality

Cubic mesoporous titanium phosphonate materials with bridged organic groups inside the framework were synthesized by means of a one‐pot hydrothermal autoclaving process, with the assistance of cationic surfactant cetyltrimethylammonium bromide. 1‐Hydroxyethylidene‐1,1‐diphosphonic acid was used as the coupling molecule. A typical cubic mesophase with surface area of 1052 m² g^?1 and pore size of 2.6 nm was confirmed by XRD, TEM, and N₂ sorption analysis. The organophosphonate groups were homogeneously incorporated in the network of the mesoporous solids, as revealed by FTIR and magic‐angle spinning (MAS) NMR spectroscopy, and thermogravimetry and differential scanning calorimetry (TG‐DSC) measurements. The synthesized hydroxyethylidene‐bridged cubic mesoporous titanium phosphonates proved to be thermally stable up to 350 °C, with a well‐preserved hybrid framework and cubic mesoporous architecture. The obtained cubic mesophase could be transformed into a hexagonal mesophase by simply adjusting the molar ratios of the added raw materials, namely, a Ti/P molar ratio of 1:4 and a CTAB/Ti molar ratio of 1.9–2.3 for the cubic phase and Ti/P molar ratio of 3:4 and CTAB/Ti molar ratio of 0.1–0.4 for the hexagonal phase. The cubic hybrid materials could be used as efficient photocatalysts for the photodegradation of rhodamine B. Moreover, they were also used for adsorption of CO₂ and heavy metal ions and exhibited a significant capture amount of around 1.0 mmol g^?1 for CO₂ molecules at 35 °C and high adsorption capacity of 28.5 μmol g^?1 for Cu²⁺ ions with good reusability, which demonstrated their promising potential in environmental remediation.