Crosslinking Reaction in the Formation of Porous Clays

Clay minerals are a class of hydrous layer aluminosilicates of the so-called phyllosilicate^[1] family made up of two basic types of layers, the SiO₄ tetrahedral sheet and the Al₂(OH)₆[or Mg₃(OH)₆] octahedral sheet, many of which posses interlayer cations capable of exchanging reaction with other cations. The preparation of porous clays are based on this reactivity of exchangeable interlayer cations by using the intercalation of polycations such as Al₁₃⁷⁺ oligomers^[2] into the galleries of clay minerals to form a microporous materials^[3] Here we reported a study on the interlayered crosslinking of a 2:1 type montmorillonites with a hydrolysed polycations Al in the formation of porous clays. Na-montmorillonite gel (Na-mont, particle size<2 μ) were purified by using sedimentation of Na-bentonite fines (400 mesh, Zhejiang, China) and subsequent extensively washing to remove any soluble Na⁺. Hydrolysed polycations Al was prepared by NaOH hydrolysis of AlCl₃ solutions in a condition^[2] of OH/Al=2.0 and then aging at 70-90℃ for 4 h by the following process^[3].     

变热特性参数条件下肋片温度周期性变化的传热研究*

本文研究了变热特性参数下,根部温度作周期性变化的肋片传热情况.应用摄动法求解控制微分方程;并且采用打靶法和叠加原理进行数值计算,求解过程是嵌进的、非迭代的.对某种形状的肋片而言,当肋片根部温度作周期性变化时,其传热过程受以下几个参数的影响:E──导热系数的温度系数;N──肋片传热的特性参数;ε──温度波动的幅度参数;B──温度波动的频率;以及对流系数的变化模式等.文中给出了这些参数变化时对肋片的温度分布及热流率、肋效率等的影响情况.所得结果,不但具有理论价值,而且对工程设计也有现实指导意义.     

若干高精度恒稳的半显式差分格式

本文构造了解色散方程u₁=au_xxx的若干三层恒稳的半显式差分格式。第Ⅰ、Ⅱ类格式的局部截断误差的阶为O(τ²+h²+(τ²)/(h³));而第Ⅲ、Ⅳ类格式的局部截断误差的阶为O(τ²+h⁴+((τ)/(h))²+τh)。用判别稳定性的Von Neumann准则可证明:第Ⅰ、Ⅱ类格式及当参数α≤1时的第Ⅲ、Ⅳ类格式都是无条件稳定的,并且当必须的边界条件给定时它们可以显式地进行计算。     

Periodic heat transfer in the fins with variable thermal parameters

ＰＥＲＩＯＤＩＣＨＥＡＴＴＲＡＮＳＦＥＲＩＮＴＨＥＦＩＮＳＷＩＴＨＶＡＲＩＡＢＬＥＴＨＥＲＭＡＬＰＡＲＡＭＥＴＥＲＳ￥ＹａｎｇＸｉａｎｇｘｉａｎｇ（杨翔翔）;ＨｅＨｏｎｇｚｈｏｕ（何宏舟）（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃａｌＥｎｇｉｎｅｅｒ...     

Coordination of the Motion Parameters within Step-by-Step Integration for Dynamic Equation

A method is presented that coordinates the calculation of the displacement, velocity and acceleration of structures within the time-steps of different types of step-by-step integration. The dynamic equation is solved using an energy equation and the calculating data of the original method. The method presented is better than the original method in terms of calculating postulations and is in better conformity with the system's movement. Take the Wilson-θ method as an example. By using the coordination process, the calculation precision has been greatly im proved (reducing the errors by approximately 90% ), and the greater part of overshooting of the calculation result has been eliminated. The study suggests that the mal-coordination of the motion parameters within the time-step is the major factor that contributes to the result errors of step-by-step integration for the dynamic equation.     

Water-soluble phenylpropanoid constituents from aerial roots of Ficus microcarpa

New water-soluble phenylpropanoid constituents, ficuscarpanoside A, guaiacylglycerol 9-O-beta-D-glucopyranoside, and erythro-guaiacylglycerol 9-O-beta-D-glucopyranoside, along with known guaiacylglycerol, erythro-guaiacylglycerol, 4-methoxy guaiacylglycerol 7-O-beta-D-glucopyranoside, and 3-(4-hydroxy-3-methoxy phenyl) propan-1,2-diol, have been isolated from the aerial roots of Ficus microcarpa. Their structures were elucidated on the basis of 1D and 2D NMR experiments.     

基于真实情境的化学教学实践——以“复习糖类、油脂和蛋白质的性质”为例

以“下午茶”为情境线,设计若干个关键问题,引导学生探究奶茶、蛋糕配料中的营养成分,复习糖类、油脂、蛋白质的性质和检验,培养学生从化学角度看待、分析并解决社会生活中的真实问题,为奶茶、蛋糕制作行业的发展提出建议,感受化学学科在社会发展中的重要作用。     

A new adenosyl-alkaloid from Ostrea rivularis

A new adenosyl-alkaloid, ostrerine A, has been isolated along with an amino acid, tryptophan and a ribonucleoside, 2'-deoxythymidine from the Quanzhou marine mollusk, Ostrea rivularis, and the structures were elucidated by 1D and 2D NMR experiments, including (1)H-(1)H COSY, TOCSY, NOESY, HMQC, and HMBC methods.     

Investigation of Cr:YAG passive mode-locking in a pulsed Nd:YAG laser

Passive mode-locking of a pulsed Nd:YAG laser using a Cr⁴⁺:YAG saturable absorber was realized for the first time in a nearly critical stable resonator containing an antiresonant ring structure. The output energy and pulse duration are 13.5 mJ and 180 ps, respectively. The recovery time and saturable intensity for excited-state absorption of Cr⁴⁺:YAG under the action of strong laser pulses were calculated from rate equations.     

ON EXTREMALITY AND UNIQUE EXTREMALITY OF TEICHMULLER MAPPINGS

ＯＮＥＸＴＲＥＭＡＬＩＴＹＡＮＤＵＮＩＱＵＥＥＸＴＲＥＭＡＬＩＴＹＯＦＴＥＩＣＨＭＵＬＬＥＲＭＡＰＰＩＮＧＳ￥ＬＡＩＷＡＮＣＡＩ；ＷＵＺＨＥＭＩＮＡｂｓｔｒａｃｔ：ＣｏｎｓｉｄｅｒｔｈｅＴｅｉｃｈｍｕｌｌｅｒｍａｐｐｉｎｇｆａｓｓｏｃｉａｔｅｄｗｉｔ...