On the Cauchy problem for Wigner–Poisson–BGK equation in the Wiener algebra

In this paper, we prove the existence and uniqueness of the local mild solution to the Cauchy problem of the n‐dimensional (n≥3) Wigner–Poisson–BGK equation in the space of some integrable functions whose inverse Fourier transform are integrable. The main difficulties in establishing mild solution are to derive the boundedness and locally Lipschitz properties of the appropriate nonlinear terms in the Wiener algebra. Copyright © 2015 John Wiley & Sons, Ltd.     

α-次积分C-半群与抽象柯西问题

本文引入一般的α-次积分C-半群和mildα-次积分C-存在族概念,并讨论它们与抽象柯西问题的联系．     

MODELLING OF WAVE PROPAGATION IN THE NEARSHORE REGION USING THE MILD SLOPE EQUATION WITH GMRES-BASED ITERATIVE SOLVERS

The mild slope equation in its linear and non-linear forms is used for the modelling of nearshore wave propagation. The finite difference method is used to descretize the governing elliptic equations and the resulting system of equations is solved using GMRES-based iterative method. The original GMRES solution technique of Saad and Schultz is not directly applicable to the present case owing to the complex coefficient matrix. The simpler GMRES algorithm of Walker and Zhou is used as the core solver, making the upper Hessenberg factorization unneccessary when solving the least squares problem. Several preconditioning-based acceleration strategies are tested and the results show that the GMRES-based iteration scheme performs very well and leads to monotonic convergence for all the test-cases considered.     

不同酸解聚麦秸产物分析及其动力学

以麦秸为研究对象,解聚剂为HCl、HNO₃和H₃PO₄,对解聚产物进行定性和定量分析,并利用动力学模型描述木糖及糠醛的产生过程。 结果表明,解聚液中的产物有葡萄糖、木糖、阿拉伯糖、纤维二糖、乙酸、糠醛、5-羟甲基糠醛。 通过引入变量(α,木糖/木聚糖的比值)利用Saeman动力学模型获得了不同温度下,木聚糖的水解速率常数、木糖的转化速率常数以及糠醛的生成速率常数。 HCl、HNO₃和H₃PO₄解聚麦秸,木糖的生成活化能分别为55.5、46.3和59.8 kJ/mol。 结合反应温度、反应时间、反应速率以及木糖和糠醛的浓度,确定最佳解聚条件为:硝酸作解聚剂,在130 ℃下水解95 min。     

盐酸介质中水杨醛缩氨基硫脲对碳钢的缓蚀作用

合成了新型席夫碱缓蚀剂:水杨醛缩氨基硫脲(ST),并考察了其在1 mol/L盐酸溶液中对碳钢的缓蚀性能。通过静态失重、动电位极化曲线、交流阻抗等技术手段研究缓蚀剂浓度对腐蚀速率及缓蚀效率的影响,阐明缓蚀作用机理。结果表明,ST在盐酸介质中对碳钢具有良好的缓蚀性能。随着缓蚀剂浓度的增加,缓蚀效率逐渐增大。ST的加入显著降低了自腐蚀电流密度,为抑制阴极反应为主的缓蚀剂。ST在碳钢表面的吸附符合Langmuir吸附模型,为物理吸附与化学吸附共同作用。     

SULFATION OF PACHYMAN WITH CHLOROSULFONIC ACID USING THE IMPROVED WOLFROM METHOD

High purity polysaccharide of pachyman was isolated from the powder of Poria cocos sclerotium with an yield of 77.8%. The intrinsic viscosity of polysaccharide was found to be 78.95 mL/g in DMSO solution at 25℃. The isolated polysaccharide was reacted with chlorosulfonic acid to obtain pachyman sulfate using the improved Wolfrom method. The results of the orthogonality experiment on the sulfation reaction identified that the effectiveness of the reaction conditions on the degree of sulfation and the value of intrinsic viscosity is in the following order: molar ratio of chlorosulfonic acid to glucoside (3-5) ＞ reaction temperature (60-80℃) ＞ reaction time (1-2 h). The kinetic studies of the pachyman sulfationindicated that the hydrolysis is accompanied with the sulfation process. The decrease in intrinsic viscosity of the sulfated pachyman is proportional to the increase in the degree of sulfation under the mild reaction conditions of ＜ 80℃,chlorosulfonic acid/glucoside mole ratio ＜ 5, and reaction time ＜ 2 h. Beyond the above reaction conditions, excessive loss of -OH group occurs during hydrolysis. The NMR results indicated a complete sulfation on C-6 and a partial sulfation on the C-2 and C-4 of glucoside.     

Investigation of Lignins by FTIR Spectroscopy

Summary: Applying special computer mathematical treatments to increase resolution of experimental spectra there were established a set of stable characteristic bands for isolated softwood lignins. In the 740–1620 cm⁻¹ spectral range the band maximum positions did not change but values of bandwidths and peak intensities were varied in limits 15% and 32%. After analysis of the infrared spectra of 30 investigated samples a softwood lignin spectral model was constituted. This model allowed to clear discrepancies in the bands parameters of different mild isolated (lignins of Bjorkman, Pepper and Freudenberg), dioxane and technical lignin spectra. It was helpful for studying lignin structure changes during degradation procedures.     

布朗动力学理论模拟动态肌动蛋白纤维的增长

肌动蛋白的聚合耦合三磷酸腺酐(ATP)分子水解成二磷酸腺苷(ADP)分子和磷酸(Pi)的释放两个过程. 因此, 肌动蛋白纤维上的原聚体存在三种不同状态, 即分别结合ATP, ADP/Pi和ADP分子. 原聚体的不同状态导致纤维具有不同的空间图谱, 这些状态的空间分布将影响纤维的各种行为. 为此,建立了相应的分子模型,在布朗动力学模拟中实现了遵循时间演化的连续马尔可夫随机过程的解聚和水解反应; 重点阐述了如何实现纤维两端的聚合和解聚达到化学平衡的方法, 并系统研究了纤维在结合ATP分子的肌动蛋白单体溶液中的增长行为.     

Avoiding Carbothermal Reduction: Distillation of Alkoxysilanes from Biogenic,Green, and Sustainable Sources

The direct depolymerization of SiO₂ to distillable alkoxysilanes has been explored repeatedly without success for 85 years as an alternative to carbothermal reduction (1900 °C) to Si_met, followed by treatment with ROH. We report herein the base‐catalyzed depolymerization of SiO₂ with diols to form distillable spirocyclic alkoxysilanes and Si(OEt)₄. Thus, 2‐methyl‐2,4‐pentanediol, 2,2,4‐trimethyl‐1,3‐pentanediol, or ethylene glycol (EGH₂) react with silica sources, such as rice hull ash, in the presence of NaOH (10 %) to form H₂O and distillable spirocyclic alkoxysilanes [bis(2‐methyl‐2,4‐pentanediolato) silicate, bis(2,2,4‐trimethyl‐1,3‐pentanediolato) silicate or Si(eg)₂ polymer with 5–98 % conversion, as governed by surface area/crystallinity. Si(eg)₂ or bis(2‐methyl‐2,4‐pentanediolato) silicate reacted with EtOH and catalytic acid to give Si(OEt)₄ in 60 % yield, thus providing inexpensive routes to high‐purity precipitated or fumed silica and compounds with single Si?C bonds.