Long-Term Evolution of Coal Permeability Under Effective Stresses Gap Between Matrix and Fracture During CO2 Injection

Transport in Porous Media - Understanding the long-term evolution of coal permeability under the influence of gas adsorption-induced multiple processes is crucial for the efficient sequestration of...     

Effects of bubble size and approach velocity on bubble–particle interaction – a theoretical study

A theoretical analysis of the atomic force microscopy (AFM) approach–retract dynamic interaction between an air bubble and a hydrophilic silica plane was carried out based on the well-established Stokes–Reynolds–Young–Laplace model. An air bubble with different radii attached to the end of a cantilever approached the silica surface with different approach velocities in a 10^?3?M KCl solution. Results showed that with increasing approach velocity (0.1, 1, and 10?µm/s), the repulsive force, flattened area of the film, and hydrodynamic suction force between the 100-µm bubble and the silica plane increased. The film continued thinning at the initial stages of bubble retraction because of the attractive hydrodynamic pressure. When the bubble size decreased, the influence of hydrodynamic pressure was less evident. The final film thickness before bubble retraction was similar to the theoretical equilibrium thickness when the Laplace pressure was equal to the disjoining pressure.     

三嗪噁二唑基吡唑衍生物抑酶活性的QSAR模型

基于拓扑化学理论,原子类型电拓扑态指数(Mk)被用于表征18种三嗪噁二唑基吡唑衍生物的化学微环境。采用最佳变量子集回归方法,分别建立上述化合物对蛋白酪氨酸磷酸酯酶1B(PTP1B)、细胞分裂周期25磷酸酯酶B(Cdc25B)的抑酶活性(P_t、C_d)与Mk的定量构效关系(QSAR)模型。它们的最佳三元QSAR模型的判定系数(R~2)依次为0.896、0.828,逐一剔除法交叉验证相关系数(R_(cv)~2)依次为0.830、0.688。经R_(cv)~2、VIF、FT、AC等检验,该模型具有良好的稳健性及预测能力。经训练集验证,上述模型均具有良好的外部预测能力。模型显示,影响Pt、Cd的因素既有不同的结构基团(-CH_3、-O-、-NH_2和芳环中-N=),也有相同的因素(芳环中-C=)。     

Existence and Approximate Controllability of Solutions for an Impulsive Evolution Equation with Nonlocal Conditions in Banach Space

In this article, we study the existence of mild solutions and approximate controllability for non-autonomous impulsive evolution equations with nonlocal conditions in Banach space. The existence of mild solutions and some conditions for approximate controllability of these non-autonomous impulsive evolution equations are given by using the Krasnoselskii''s fixed point theorem, the theory of evolution family and the resolvent operator. In particular,the impulsive functions are supposed to be continuous and the nonlocal item is divided into Lipschitz continuous and completely bounded. An example is given as an application of the results.     

A simple procedure for the synthesis of benzoxanthene derivatives under microwave irradiation conditions

A rapid and efficient method is developed to synthesize a series of benzoxanthene derivatives by the reaction of aldehydes and 2‐hydroxynaphthalene‐1,4‐dione in mixed solvent of acetic acid and ethylene glycol under microwave irradiation. The method has the advantages of short synthetic route, operational simplicity and higher yields (70%～85%).     

Electrochemical C–H/N–H cross-coupling of 2-phenylindolizines with phenothiazines to synthesize novel N-aryl phenothiazine derivatives

A facile and elegant method for synthesis of novel N–aryl phenothiazine derivatives from 2-phenylindolizines and phenothiazines through direct electrochemical oxidation has been developed. This approach was performed smoothly at room temperature without external oxidant and catalyst. Cyclic voltammetry and in situ FTIR techniques were applied to analyze the cross-coupling process of phenothiazines and 2-phenylindolizines, which helped to select the appropriate reaction potential. Under the optimized conditions, a broad range of substrates were well tolerated, affording the desired products in moderate to excellent isolated yields (up to 91%) with high regioselectivity. Meanwhile, a plausible mechanism involving a radical pathway has been proposed.     

Synergistic Pd/Cu-catalyzed regio- and stereoselective cascade Heck cyclization/borylation/cross-coupling

A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes, B₂Pin₂ and alkene-tethered aryl halides is reported. This reaction proceeds under mild conditions and shows broad substrate scope, providing a variety of heterocycles containing tetrasubstituted alkenylboronate moieties in synthetically useful yields with excellent chemoselectivity and regioselectivity. This transformation features the catalytic generation of β-borylalkenylcopper intermediates and their use in Pd-catalyzed Heck cyclization/cross-couplings. An enantioselective cascade cyclization/cross-coupling process has also been developed for the synthesis of enantiomerically enriched oxindole bearing a tetrasubstituted alkenylboronate moiety.     

有机污染物的生物富集因子与拓扑指数的数学模型

依据价连接性指数(xi)、电性拓扑态指数(ej)及电性距离矢量(mk)构建239种有机污染物生物富集因子(FBC)的6参数QSFR(定量结构-生物富集因子相关性)模型, 不仅相关程度高, 而且所用自变量数少. 该模型的传统相关系数(R2)为0.821, LOO(levae-one-out)交互验证系数(Q2)为0.809, 证明具有良好的稳健性及预测能力. 根据进入该模型的6个参数可知, 影响有机污染物FBC的主要结构基团是: —C—、>C—、—O—、—X、—NH2以及分子的柔韧性、折叠程度等空间因素. 可以认为在生物富集过程中,“诱导契合机理”也发挥一定作用. 对自变量集进行正交变换, 既不影响模型的相关性, 又能降低其自相关性.     

电感耦合等离子体质谱(ICP-MS)法测定土壤中的碘

通过电感耦合等离子体质谱法(ICP-MS)测定土壤中的碘。样品预处理采用艾斯卡试剂熔融、热水提取和阳离子树脂静态交换,试验加入了不同剂量的阳离子交换树脂在不同程度上降低了溶液中Na+ 和Zn2+^{等阳离子的盐效应干扰。研究了乙醇在}ICP-MS中对碘元素的增强效应,用3%的氨水溶液清洗进样系统,有效减少的碘的记忆效应和清洗时间。该方法线性范围宽,方法灵敏度高,检出限低,试剂用量少,环境友好。对苏州及周边区域若干非污染土壤点位进行采样、制备和测试,碘平均含量为2.7μg.g_-1^;同步测试国家有证标准物质,精密度和准确度良好。