液相剪切原位剥离蒙脱土纳米片增强高阻氧聚乳酸

提出了液相剪切剥离蒙脱土(MMT)制备寡层纳米片(MNSs)并将其原位引入PLA基体的方法, 可经简单的刮刀涂覆法(Blade coating)制备MNSs质量分数为2%, 5%和10%的PLA基纳米复合薄膜. 该技术路线赋予了MNSs在PLA基体中充分剥离(片层间距可达3.11 nm)和良好取向排列以及较强的界面相互作用. 这些结构特征使得纳米复合薄膜的结晶度和力学性能得到大幅提升, 同时显著降低了氧气渗透系数. 本文不仅提出了可规模化原位剥离二维纳米片的有效方法, 更为制备高强高阻隔全降解复合材料及其结构-性能关系研究提供了思路.     

沥青质及其亚组分与烷基苯磺酸盐溶液在降低界面张力中的协同作用

利用混合溶剂沉淀法将原油中的沥青质分为4个亚组分, 研究了含有各组分的模拟油与烷基苯磺酸钠(p-S14-4, p为对二甲苯; 14表示烷基链上有14个碳原子; S表示表面活性剂; 4表示芳基在长链烷基的4号碳原子上)水溶液间的动态界面张力(DIFTs). 结果表明, 沥青质及其亚组分的分子尺寸、 浓度和极性对DIFTs有显著影响. 分子尺寸较大的沥青质亚组分与p-S14-4分子之间难以形成混合吸附膜, 协同作用较弱, DIFTs曲线呈“L”形, 最小界面张力(IFT_min)受浓度和极性的影响较小. 在高浓度时, 分子尺寸较小的沥青质及其亚组分快速扩散至界面与p-S14-4分子形成紧密的混合吸附膜, 能够快速降低界面张力(IFT); 随着时间的延长, 界面层的分子发生重排, 导致DIFTs曲线呈“V”形, 且在这种情况下沥青质及其亚组分的极性越高, 降低IFT的协同作用越明显, IFT_min越低.     

Asiatic Acid Glucosamine Salt Alleviates Ultraviolet B-induced Photoaging of Human Dermal Fibroblasts and Nude Mouse Skin

Herbal extracts including asiatic acid (AA) have become popular candidates of anti-photoaging agents due to their anti-inflammatory and antioxidant properties and minimal side effect. Nevertheless, low bioavailability due to poor solubility limits their practical application. In this study, a highly bioavailable form of AA called AAGS (compounded by asiatic acid and glucosamine) was investigated for its anti-photoaging effect using both in vitro and in vivo models along with UVB irradiation. The results showed that AAGS alleviated UVB-induced cell proliferation inhibition by reducing G2 phase arrest and cell apoptosis rate as well as the gene expressions of P53, BAX, CASPASE 3 and CASPASE 9, but enhancing BCL-2 expression. It also reduced the production of reactive oxygen species along with increased gene expression of GPX-1 and downregulated the gene expression of IL-1β, IL-6, IL-8, IL-17 and TNF-α compared to nontreated cells. In vivo results demonstrated the antiphotodamaging effects by restoring skin thickness, collagen content and reducing MMPs expression, which are also supported by reduced MMPs gene expression and enhanced collagen I and TGF-β1 gene expression in vitro. Thus, AAGS may become a potential anti-photoaging agent for topical use due to its capability of self-assembling into a water gel.     

Pyromeconic acid derivatives from Conyza canadnsis(L.) Cronq

A new pyromeconic acid derivative,pyromeconic acid-3-O-β-D-glucopyranoside-3′-(O-β-D-glucopyranoside)-6′-(O-4″-hydroxybenzoate) (1),along with two known ones,were isolated from the whole plants of Conyza canadensis.Their structures were elucidated based on the analysis of their spectroscopic data.The in vitro antibacterial testing results showed that all of these three compounds were inactive towards two bacterial strains,Escherichia coli and Staphyloccocus aureus.     

Photoinitiation mechanisms and photogelation kinetics of blue light induced polymerization of acrylamide with bicomponent photoinitiators

Blue light induced free radical photopolymerization of acrylamide (AM) was studied using five bicomponent photoinitiators, camphorquinon, riboflavin-5′-phosphate sodium, curcumin, eosin Y, and Ru(bpy)₃Cl₂ (Ru(II)) as photosensitizer, and diphenyliodonium hexafluorophosphate or potassium persulfate as electron acceptor. Fluorescence and UV–vis spectroscopies were used in combination with molecular orbital computations to characterize the photochemical behaviors of the five bicomponent photoinitiators, explore the possible electron transfer pathways of the photoinitiation processes, and quantify photopolymerization efficiencies. Real-time photogelation behavior of poly(AM) was monitored by Photo-differential scanning calorimetry and photo-rheometry. Photogelation kinetic parameters, including dG′ (storage modulus)/dt, dG″ (loss modulus)/dt, time delay of gelation (t_d), and duration of gelation (Δt_gel), were derived from photorheological data analyses and used to identify the best bicomponent photoinitiator candidate for rapid fabrication of blue light induced photopolymerizable hydrogels for biomedical applications.     

低Ni含量和低比表面积六铝酸盐LaNiAl11O19-δ催化剂上CH4-CO2重整反应的积炭

 利用 X 射线粉末衍射、氢程序升温还原、X 射线光电子能谱和透射电镜技术研究了在低 Ni 含量和低比表面积六铝酸盐催化剂 LaNiAl11O19-δ 上 CH4-CO2 重整反应的积炭行为, 考察了该催化剂表面积炭的形貌、来源、积炭物种及其反应性能. 结果表明, LaNiAl11O19-δ 催化剂表面积炭主要由甲烷裂解产生, 并以 Ni 的碳化物形式存在于活性中心 Ni 的周围. 根据积炭物种活化程度的难易可分为 Cα, Cβ和 Cγ 三种类型, 其中 Cα 为容易被 CO2 消除的化合碳, 而 Cβ 和 Cγ则是不易被 CO2 消除的石墨碳. 透射电镜结果表明, Cα 以碳纳米管形式分布于催化剂颗粒周围, 但金属 Ni 活性中心仍能暴露于气相中, 因而不影响催化剂的活性.     

THE C~(1,α) REGULARITY OF SOLUTIONS TO DOUBLE OBSTACLE PROBLEM OF VARIATIONAL INEQUALITY

In this paper, a double obstacle problem of variational inequalities is considered and its solutions is obtained. The results of one-sided obstacle problem are not required in the analysis of our main results, which is different from the previous works.     

A STUDY ON THE ADSORPTION OF LOW CONCENTRATION FREE ALKALI BY SUBACID RESIN

1. INTRODUCTIONIn the purification process of food, drug, and biological products, usually the material to be purified were not neutral. Application of traditional neutralization method with acid or alkali could increase electrolyte content in the material to be purified. Due to the capability of the adsorption of free alkali by subacid resin, the defect of electrolyte absorption in neutralization could be avoided when used in the purification of food, drug, and biological products [1]. H…     

氧化镁负载钼钒磷酸铜催化剂上正己醇氧化脱氢制正己醛

 采用乙醇溶液浸渍法制备了MgO负载的Cu2PMo11VO40催化剂,考察了催化剂对正己醇氧化脱氢生成正己醛的催化性能,确定了最佳反应条件. 催化剂经50 h反应后活性没有下降,生成正己醛的选择性保持在96.0%以上. IR光谱和TPR结果表明,在反应条件下催化剂上不断有V5+从Keggin结构中移出,与Cu2+一起作为抗衡离子存在于Keggin结构单元之外,形成缺位的Keggin型结构,使催化剂处于活化状态; Cu2+的存在使催化剂的还原温度降低,Keggin结构之外的V5+与Cu2+之间存在相互作用,可使催化剂活性提高.     

Study on the Radius of an Electrical Spherical Micelle： Functional Theoretical Approach

For the purpose of eliminating restriction, the Poisson-Bokzmann (PB) equation, which represents the potential of the electrical double layer of spherical miceUes, can be solved analytically only under the lower potential condition, a kind of iterative method in functional analysis theory has been used. The radius of the spherical particle can be obtained from the diagram of the second iterative solution of the potential versus the distance from the center of the particle. The influences of the concentration of the ions, the charge number of ions, the aggregation number of the particle, the dielectric constant of solvent and the temperature of system on the radius also have been studied.