Design and Synthesis of 2‐Methyl‐7‐aminobenzoxazole as Auxiliary in the Palladium(II)‐Catalyzed Arylation of a beta‐Positioned C(sp3)?H Bond

A palladium(II)‐catalyzed direct arylation of methylene C(sp³) H bonds by 2‐methyl‐7‐aminobenzoxazole as an effective auxiliary is reported. This process exhibited high beta‐site selectivity, broad substrate scope, and compatibility with different functional groups with moderate to high yields up to 89%.

     

Phosphorylation of Glycine Derivatives via Copper(I)‐Catalyzed Csp3−H Bond Functionalization

A simple and efficient one‐pot approach has been developed for a copper‐catalyzed phosphorylation of glycine derivatives under air and at room temperature. The present cross‐dehydrogenative coupling allows various methoxyphenyl‐protected glycine derivatives to be phosphorylated using diverse alkyl and aryl phosphites through an oxidative coupling between Csp³−H and P−H bonds catalyzed by copper iodide. This method provides a new synthetic tool to obtain biologically active α‐aminophosphonates.

     

Characterizing the effects of fines on the liquefaction resistance of silty sands

Recent earthquakes in New Zealand and Japan indicate that evaluating the liquefaction potential of silty sands remains an area of difficulty and uncertainty in geotechnical engineering. This paper presents a comprehensive experimental study along with analysis and interpretation in the framework of critical state soil mechanics, with the aim to address the complicated effects of fines. Two series of sand-silt mixtures, formed by mixing two different base sands with the same type of non-plastic silt, were tested under a range of packing density, confining pressure and silt content, and a unified correlation was established between the cyclic resistance and the state parameter that collectively accounts for the effect of packing density and confining pressure. The proposed correlation is independent of packing density, confining pressure, fines content and base sand, and allows prediction of the cyclic resistance of silty sands under different states. Furthermore, the mechanism of the fines-content induced reduction of cyclic resistance and the mechanism of the base-sand effect observed from the tests are elaborated in the sound theoretical context. The present study suggests that the critical state soil mechanics is a rational and appealing framework for liquefaction analysis of both clean and silty sands.     

Influence of High Voltage Gradients on Electrokinetic Dewatering for Wenzhou Clay Slurry Improvement

Soil Mechanics and Foundation Engineering - Laboratory experiments were conducted to examine the feasibility and determine the optimal voltage gradient of electrokinetic consolidation of Wenzhou...     

基于空间句法的历史城区叙事空间研究

如何将历史城区的物质环境与社会文化等人文要素相结合,营造“高语境”、“原真性”的历史空间环境,是历史城区保护必须面对的重要问题。基于叙事学视角,从叙事簇群、叙事廊道、叙事点核的单元结构出发,引入空间句法量化方法,对历史城区叙事空间的空间权力表征、功能表征、特质表征给予量化解释,并为历史城区活化保护提供建议。     

英国乡村规划空间尺度的经验与启示

英国拥有完善的城乡规划体系,关于乡村规划空间尺度的研究成果与实践经验非常丰富。文章从英国乡村问题与规划尺度之关系出发,系统梳理了英国乡村规划发展演变的几个阶段和几种类型,总结了英国乡村规划空间尺度的特征,一是乡村问题有多个层次,二是乡村问题的空间尺度决定了规划尺度,三是英国乡村规划已经形成体系。通过分析中英乡村问题的共同特征,得出英国经验对我国乡村规划的参考和启示,建议扩大乡村规划的对象,扩大乡村规划作为区域规划的特征,深入分解乡村问题、制定规划目标,以及依据乡村问题尺度选择合适的规划尺度,以解决目前我国乡村规划的困境。     

正交异性钢桥面板结构体系的疲劳破坏模式和抗力评估

正交异性钢桥面板的疲劳问题属于包含多疲劳破坏模式的结构体系疲劳问题。基于这一本质特性,以典型的正交异性钢桥面板结构体系为研究对象,由结构体系的主导疲劳破坏模式出发,提出正交异性钢桥面板结构体系疲劳抗力评估的新方法。以纵肋与顶板焊接细节和纵肋与横隔板交叉构造细节为主要研究对象,设计8个足尺节段模型,主要包括传统纵肋与顶板焊接细节、新型镦边纵肋与顶板焊接细节和纵肋与横隔板交叉构造细节,通过模型试验研究了两类重要构造细节的主导疲劳破坏模式和实际疲劳抗力,在此基础上结合切口应力评估方法探讨正交异性钢桥面板构造细节切口应力S-N曲线方程、结构体系的主导疲劳破坏模式等关键问题。研究结果表明：传统纵肋与顶板焊接细节和新型镦边纵肋与顶板焊接细节的主导疲劳破坏模式均为疲劳裂纹萌生于焊根并沿顶板厚度方向扩展,二者的实际疲劳抗力基本相同;纵肋与横隔板交叉构造细节的疲劳破坏模式为焊趾开裂沿纵肋腹板方向扩展;对于研究对象而言,萌生于纵肋与顶板焊接细节焊根并沿顶板厚度方向扩展的疲劳破坏模式为控制结构体系疲劳抗力的主导疲劳破坏模式。     

简单复合岩体中TBM多滚刀破岩机理离散元分析

采用引入考虑胶结尺寸的微观接触模型的PFC^2D离散元软件,对全断面岩石掘进机（TBM）盘形滚刀作用下简单形式的复合岩体破岩机理进行数值模拟研究。进行了单滚刀、双滚刀和三滚刀作用下的复合岩体破碎过程的模拟。模拟结果表明：滚刀破岩过程可以分为三个阶段：加载阶段、卸载阶段和残余跃进阶段。通过双滚刀和三滚刀侵入复合岩体的推力-侵深曲线分析,软岩上的滚刀比硬岩上的滚刀进入各阶段稍慢,略有滞后;不同滚刀间的峰值法向推力相差较大,易造成滚刀磨损。对于花岗岩-绿片岩复合岩体,破岩时接触力链被岩体分界面分割,硬岩区胶结破坏数目较多,双滚刀、三滚刀侵入时易形成贯通裂缝;破岩效率由大到小为双滚刀效率、三滚刀效率、单滚刀效率,而且双滚刀能够将效率提高一倍左右。     

4,6-二甲基-2-甲磺酰基嘧啶的合成

以硫脲为原料,经碳酸二甲酯甲基化,乙酰丙酮环合,再用过氧化氢氧化得到4,6-二甲基-2-甲磺酰基嘧啶,3步反应的总收率为71.0%。目标化合物结构经GC-MS、1H NMR确证。     

β-Conglycinin Reduces the Tight Junction Occludin and ZO-1 Expression in IPEC-J2

Soybean allergy presents a health threat to humans and animals. The mechanism by which food/feed allergen β-conglycinin injures the intestinal barrier has not been well understood. In this study, the changes of epithelial permeability, integrity, metabolic activity, the tight junction (TJ) distribution and expression induced by β-conglycinin were evaluated using IPEC-J2 model. The results showed a significant decrease of trans-epithelial electrical resistance (TEER) (p < 0.001) and metabolic activity (p < 0.001) and a remarkable increase of alkaline phosphatase (AP) activity (p < 0.001) in a dose-dependent manner. The expression levels of tight junction occludin and ZO-1 were decreased (p < 0.05). The reduced fluorescence of targets and change of cellular morphology were recorded. The tight junction occludin and ZO-1 mRNA expression linearly declined with increasing β-conglycinin (p < 0.001).