Improved Dermal and Transdermal Delivery of Curcumin with SmartFilms and Nanocrystals

Poor aqueous solubility of active compounds is a major issue in today’s drug delivery. In this study the smartFilm-technology was exploited to improve the dermal penetration efficacy of a poorly soluble active compound (curcumin). Results were compared to the dermal penetration efficacy of curcumin from curcumin bulk suspensions and nanocrystals, respectively. The smartFilms enabled an effective dermal and transdermal penetration of curcumin, whereas curcumin bulk- and nanosuspensions were less efficient when the curcumin content was similar to the curcumin content in the smartFilms. Interestingly, it was found that increasing numbers of curcumin particles within the suspensions increased the passive dermal penetration of curcumin. The effect is caused by an aqueous meniscus that is created between particle and skin if the dispersion medium evaporates. The connecting liquid meniscus causes a local swelling of the stratum corneum and maintains a high local concentration gradient between drug particles and skin. Thus, leading to a high local passive dermal penetration of curcumin. The findings suggest a new dermal penetration mechanism for active compounds from nano-particulate drug delivery systems, which can be the base for the development of topical drug products with improved penetration efficacy in the future.     

合成温度对全梯度正极材料LiNi0.7Co0.15Mn0.15O2的结构和电化学性能影响

通过控制结晶法和浓度梯度进料的方式制备了Ni、Co和Mn三元素组分含量呈全梯度分布的类球形Ni_0.7Co_0.15Mn_0.15（OH）₂前驱体,与LiOH·H₂O均匀混合并焙烧后获得LiNi_0.7Co_0.15Mn_0.15O₂正极材料,系统研究了不同焙烧温度对材料Ni、Co和Mn三元素扩散情况、晶体结构及电化学性能的影响规律。通过能谱仪（EDXS）分析不同焙烧温度下材料颗粒中Ni、Co、Mn三元素的扩散程度。研究结果表明,在800℃下焙烧得到的正极材料梯度分布特征明显且电化学性能最佳,首次放电比容量为186.1 mAh·g^-1（2.8~4.3 V,0.2C）,2C大倍率充放电条件下循环200次后容量保持率为90.1%。这种材料兼具高比容量及良好的循环稳定性,可以用作下一代高能量密度锂离子电池正极材料。     

正交试验结合响应面法优化诃子多糖提取工艺

采用正交试验结合响应面法优化诃子多糖的提取工艺,以诃子多糖的提取率为指标,以固液比、提取温度、提取时间和提取次数为因素,正交试验初步筛选工艺参数,响应面法做进一步优化.结果表明,多糖提取的最佳工艺条件为固液比1∶28,提取温度69℃,提取时间1h,提取次数3次,各项指标相对误差均小于2%,应用响应面法可减少诃子多糖提取时间.     

Extension of the Method of Moments in Nonlinear Free Radical Polymerization

The method of moments is a simple, efficient method simulating polymerization processes. Its use is said to be limited in nonlinear free radical polymerizations with branching or crosslinking due to the assumptions needed. Here, moment equations are derived without assuming steady state, one radical per molecule, or a statistical distribution of connections. Equations are valid up to the gel point. The bulk solution is formally identical to the pseudo kinetic approach by Tobita and Hamielec if moments of dead polymer are replaced by the sum of dead and life polymers. The method relies on analytical solutions of the moments of the molecular weight distributions (MWD) of instantaneous primary chains. In emulsion polymerization compartmentalization of radicals complicates the calculation. An alternative approximation of these MWDs is presented. The present extension allows nonlinear free radical polymerization to be readily included in the computer based design and optimization of polymerization processes and to check more detailed calculations of the MWD.

     

A parametric investigation of the friction performance of PC‐ABS parts processed by FDM additive manufacturing process

The friction performance is an important factor of parts processed by fused deposition modeling (FDM) for various engineering applications. It is one type of failure made of surface contact. The proper use of FDM process parameters can bring a significant reduction in friction and the amount of wear, thereby leading to a reduction in the material waste. To date, very little studies have been performed in this area. This paper investigates the effect of FDM manufacturing parameters on the friction performance of polycarbonate‐acrylonitrile butadiene styrene prototypes processed by FDM using definitive screening design and partial least squares method. The observation of surface morphology was obtained by the scanning electron microscopy to examine the effect of process parameters on the microstructure. The experimental results have shown that layer thickness, air gap, raster angle, and build orientation are the most influential factors affecting the friction performance of FDM manufactured parts. The proposed approach presented in this study provides an impetus to develop analytical modeling and functional relationships between FDM manufacturing parameters and friction performance. Copyright © 2017 John Wiley & Sons, Ltd.     

Improving the water resistance of epoxy–anhydride matrices by the incorporation of bentonite

Epoxy–anhydride‐based polymers are commonly used as a matrix in pipeline systems exposed to water during their in‐service life. Water absorption at moderate temperatures and/or at long exposure times could lead to irreversible hydrolysis reaction decreasing considerably the polymer overall performance. A strategy to enhance the barrier properties of epoxy resins is to add nanofillers to traditional matrices. In this work, we added bentonite and chemically modified bentonite to this purpose. Water absorption of the resulting materials at three different temperatures (22°C, 80°C, and 93°C) was studied, and simultaneously, the evolution during the immersion tests of glass transition temperature and flexural modulus was recorded. Long‐term gravimetric results showed that composites with chemically modified bentonite produce a delay on the hydrolysis of epoxy–anhydride matrix, which is a relevant result, because of the tough application and uses of the system, from the technological point of view. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and catalytic performance of bimetallic NiMo- and NiW-ZSM-5/MCM-41 composites for production of liquid biofuels

This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil( CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized through a self-assembly of cetyltrimethylammonium bromide( CTAB) surfactant with silica-alumina from ZSM-5 zeolite,prepared from natural kaolin by the hydrothermal technique. Subsequently,the synthesized composites were deposited with bimetallic NiMo and NiW by impregnation method. The obtained catalysts presented a micro-mesoporous structure,confirmed by XRD,SEM,TEM,EDX,NH_3-TPD,XRF and N_2 adsorption-desorption measurements. The results of CPO conversion demonstrate that the catalytic activity of the synthesized catalysts decreases in the series of NiMo-ZSM-5/MCM-41 NiW-ZSM-5/MCM-41 Ni-ZSM-5/MCM-41 Mo-ZSM-5/MCM-41 W-ZSM-5/MCM-41 NiMo-ZSM-5 NiW-ZSM-5 ZSM-5/MCM-41 ZSM-5 MCM-41. It was found that the bimetallic NiMo-and NiW-ZSM-5/MCM-41 catalysts give higher yields of liquid hydrocarbons than other catalysts at a given conversion. Types of hydrocarbon in liquid products,identified by simulated distillation gas chromatography-flame ionization detector( SimDis GC-FID),are gasoline( 150-200 ℃; C5-12),kerosene( 250-300 ℃; C5-20) and diesel( 350 ℃; C7-20).Moreover,the conversion of CPO to biofuel products using the NiMo-and NiW-ZSM-5/MCM-41 catalysts offers no statistically significant difference( P 0.05) at 95% confidence level,evaluated by SPSS analysis.     

ZSM-5分子筛催化甲醇制汽油反应中的晶粒粒径效应研究

通过调控水热合成ZSM-5凝胶液中H_2O/Si物质的量比,实现了粒径为70、200、400和650 nm四种单分散ZSM-5的可控合成。采用XRD、TEM、BET和NH_3-TPD等多种表征对其微观结构进行分析,结合催化性能评价,考察了晶粒粒径对其催化甲醇制汽油反应性能的影响机制。结果表明,整体上随着ZSM-5晶粒粒径的增加,其外比表面积减小,结晶度提高,酸量呈现出先增加后基本不变的趋势。但外表面附着小晶粒的粒径为650 nm的分子筛体现出了大的外表面积和强的酸性。ZSM-5晶粒粒径的增加整体上降低了其催化MTG反应的寿命和最高收率。晶粒粒径为70 nm时,ZSM-5体现出了96 h的催化寿命和30.8%的最高收率。晶粒粒径为650 nm样品由于其大的外比表面积和较强的表面酸性,也体现出91 h的寿命。在大晶粒ZSM-5外表面附着生长小晶粒ZSM-5,是一种制备高性能催化剂的新方法。     

夹心法免疫层析试条的数学模型与仿真研究

基于夹心法免疫层析试条检测原理,结合对流扩散方程和流体动力学方程,建立了夹心法免疫层析试条动态反应过程的数学模型,并通过COMSOL软件对试条动态反应过程进行仿真.分别探究了目标待测物A浓度在0 ～ 20 mol/L,标记物P浓度在1×10-2～1×103 mol/L以及硝酸纤维素膜的孔隙率在0～1范围内变化时,检测线上夹心复合物浓度关于位置和时间的浓度变化情况,并分析了各物质初始浓度以及试条结构对于检测结果和检测时间的影响.结果表明,在一定浓度范围内,目标待测物A以及标记物P浓度的增加将提高试条的定量检测性能,而孔隙率通过影响混合液流速和混合液中各物质反应接触情况来影响检测结果.     

A fast discontinuous finite element discretization for the space‐time fractional diffusion‐wave equation

In this article, we study fast discontinuous Galerkin finite element methods to solve a space‐time fractional diffusion‐wave equation. We introduce a piecewise‐constant discontinuous finite element method for solving this problem and derive optimal error estimates. Importantly, a fast solution technique to accelerate Toeplitz matrix‐vector multiplications which arise from discontinuous Galerkin finite element discretization is developed. This fast solution technique is based on fast Fourier transform and it depends on the special structure of coefficient matrices. In each temporal step, it helps to reduce the computational work from required by the traditional methods to log , where is the size of the coefficient matrices (number of spatial grid points). Moreover, the applicability and accuracy of the method are verified by numerical experiments including both continuous and discontinuous examples to support our theoretical analysis.© 2017 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 2043–2061, 2017