Complex impedance spectroscopy to investigate degradable chondroitin–poly(amino-serinate) complexes

Sodium chondroitin-4-sulfate and poly(amino-serinate) bromide can interact to form a degradable polyelectrolyte complex. The structure of each polymer and of their complex before and after degradation is investigated by complex impedance spectroscopy. Poly(amino-serinate) bromide and sodium chondroitin-4-sulfate exhibit dc conductivity and dielectric relaxation phenomena in the 10²–10⁶ Hz range. On the contrary, no dc conductivity and dielectric relaxation are observed in the polyelectrolyte complex before degradation. After degradation, the released chondroitin-4-sulfate is re-complexed with additional poly(amino-serinate) bromide. Contrary to the original parent complex the restored complex exhibits both dc conductivity and dielectric relaxation phenomena. This difference is assigned to structural defects due to the presence of residual poly(amino-serinate) oligomers which compete with the newly added poly(amino-serinate) to complex the released chondroitin-4-sulfate. This outcome is interpreted assuming the displacement of the low molecular by higher molecular weight chains in contrast to the behavior usually reported for this type of polymeric systems.     

无机物离子对CuS微晶形态结构的有效调控

以CuCl2·3H2O,Cu（CH3COO）2·H2O和CuSO4·5H2O作为铜源,并向反应体系中引入少量NaCl或NaNO3,通过乙二醇溶剂中的溶剂热反应,合成了形貌各异的CuS微晶．结合XRD和SEM表征,初步探讨了阴离子Cl-、CH3COO-、SO4^2-和阳离子Na’对CuS微晶生长过程的影响．结果表明,Na＋对CuS微晶的生长过程没有显著影响,而Cl、CH3COO-、SO4^2-由于在{1012}晶面上选择性吸附能力的差异,显著影响CuS微晶的形貌．本研究为进一步有效调控CuS微晶的形貌及性能奠定了基础．     

非线性流固耦合问题的ALE分步有限元数值方法

推导了一种基于ALE（Arbitrary Lagrangian-Eulerian,即任意的拉格朗日-欧拉）描述下的带有自由液面不可压液体与运动结构非线性耦合问题的一种有限元数值计算方法,在时间域上采用分步格式计算,这种方法与混合插值方法比较其优点是速度和压力可使用同阶线性插值,给数值计算带来很大方便,将所得到的方法应用到结构与TLD（调谐式（液体阻尼器）装置之间的耦合问题,数值计算结果验证了本文所推导的方法。     

二层供应链网络均衡模型的研究

利用均衡理论和二层规划理论来研究供应链网络均衡问题。针对供应链网络中上下层成员之间具有的Stackelberg博弈特征以及同层成员之间具有的非合作博弈特征,构建了二层供应链网络的均衡模型,该模型实际上一个均衡约束的二层规划问题。此外,为了使得供应链网络在整体上实现最优,本文还在模型中引入回收契约以协调供应链网络。最后,利用罚函数法对模型进行了求解,算例分析说明了模型的合理性和有效性。     

TL dating and XRF clay provenance analysis of ancient brick at Cuicul Roman city,Algeria

In this work, a terra-cotta brick collected from the famous archaeological Roman city Cuicul, Algeria, was successfully dated by thermoluminescence. The provenance of the fabrication material was also identified by X-ray fluorescence analysis (XRF). The results obtained show that the brick was probably made in 198 A.D. This date is in good agreement with the history of the dated site and the neighborhood Caracalla arch edified in honour to Caracalla emperor (211–217 A.D.). The XRF study demonstrates that the raw clay used for the fabrication of the brick is local and well selected by the Roman builders.

     

A New Method of Constructing the Functional Integral Directly from Hamiltonian in N (> 2)-Dimensional State space

Using the new method of constructing the functional path integral in state space, we accomplished the construction of the functional path integral in N(> 2)-dimensional state space, and illustrated it with the example of n = 3 dimensional case that leads to the same results with others.     

Frottements et pertes de pression des fluides non newtoniens dans des conduites non circulaires

The study of fluid flow in a duct requires characteristic parameters of the flow and dimensionless numbers to correlate and compare experimental results. For Newtonian fluids in simple configurations, the definition of the Reynolds number is quite standard, but for non-Newtonian fluid flows in ducts with arbitrary shape of cross section, the dependence of the apparent viscosity with the shear rate requires a generalization of this dimensionless number. This note proposes a general method valid for a large class of non-Newtonian fluids and for all duct shapes. An application is developed for a viscoelastic flow through a rectangular duct. Results obtained in the present investigation are in a good agreement with available correlations. To cite this article: M. Mahfoud et al., C. R. Mecanique 333 (2005).     

氮掺杂碳纳米管负载的Ru和Pd催化剂上异丙醇的转化(英文)

Ru and Pd (2 wt%) loaded on pure and on Ndoped carbon nanotubes (NCNTs) were prepared and tested using the isopropyl alcohol decomposition reaction as probe reaction. The presence of nitrogen functionalities (pyridinic, pyrrolic, and quaternary nitrogen) on the nitrogen doped support induced a higher metal dispersion: Pd/NCNT (1.8 nm) Pd/CNT (4.9 nm), and Ru/NCNT (2.4 nm) Ru/CNT (3.0 nm). The catalytic activity of the supports was determined first. Isopropyl alcohol conversion produces acetone on CNTs while on NCNTs it led to both dehydration and dehydrogenation products. At 210 °C and in the presence of air, the isopropyl alcohol conversion was higher on the NCNTs (25%) than on the CNTs (11%). The Pd loaded catalysts were more active and more selective than the Ru ones. At 115 °C, the Pd catalysts were 100% selective towards acetone for a conversion of 100%, whereas the Ru catalysts led to dehydration and dehydrogenation products. The nitrogen doping induced the appearance of redox properties when oxygen is present in the reaction mixture.     

Role of aggregation in the amplified spontaneous emission of [2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] in solution and films

The amplified spontaneous emission (ASE) spectra of the conjugated polymer [2-methoxy-5-(2′- ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) is investigated under different conditions such as thin film and solution, solvent type and concentration. Results indicate that aggregation has a pronounced effect on ASE spectra. In solution form, as concentration was increased and thus the proportion of aggregates, a decrease in the ASE emission bandwidth and a red shift of the ASE peak was observed. For the thin film samples, the ASE spectra show two emission bands which were assigned to the first and second vibronic transition of the polymer chains.     

石荠苧不同药用部位总黄酮及微量元素含量的测定

采用分光光度法测定了石荠芋不同药用部位总黄酮的含量,采用电感耦合等离子发射光谱法测定了其中微量元素的含量。结果表明,叶中总黄酮含量最高,根次之,茎最少;根、茎、叶中均含有Cu、Fe、Mn、Zn、Co等多种人体必需的微量元素,其中Fe含量最高,且叶中明显高于根、茎;3个部位均未检出有害重金属As,而Hg、Pb含量均未超标。该结果可为石荠芋不同药用部位的利用和药材的开发提供科学依据。