细粒土K_(30)试验分级加载变形稳定标准探讨

分级加载的变形稳定标准是影响K_(30)试验准确性和效率的关键因素。对粉质黏土在最佳含水率下,开展了三组压实系数K分别为0.90、0.95和1.00的小型平板载荷试验,得到不同荷载作用下填土变形时程曲线,分析了分级加载下填土变形的时间效应程度,讨论了不同变形稳定标准对K_(30)值的准确性和试验效率的影响。研究表明:根据最后1min变形比(1%)和变形速率Δs(mm/min)两种变形稳定标准,K_(30)试验的分级加载时间随时间效应程度分别呈先增长后缩短和加速增长的变化趋势,后者更符合土变形稳定时间与时间效应程度的正相关变化规律;Δs取0.01能降低51%~58%的试验时间,试验误差在6%以内,Δs增大会使试验误差大幅提高,Δs减小则会使试验时间大幅增加;据此,提出了适用于细粒土压实质量检测的级数-时间分级加载控制法。所得成果可为提高细粒土压实质量检测效率提供试验依据。     

N-substituted-3(10H)-acridones as visible-light photosensitizers for organic photoredox catalysis

N-Substituted-3(10H)-acridones have been established as visible-light organic photocatalyst. These photosensitizers are efficient for oxidative coupling reaction of N-aryl tetrahydroisoquinolines with various nucleophiles. Notably, N-methyl-3(10H)-acridone (Ia) is stable and can be effectively prepared. It is a water-soluble and atom-economic catalyst, and thus holds promise for green chemical applications. Mechanistic studies confirm a single electron transfer (SET)-induced radical process and a rate-limiting step. Analysis of the photocatalytic reactivity?structure relationship reveals that the acridones are robust and tunable photosensitizers for photoredox catalysis.     

基于B样条的TERS形貌成像背景扣除方法

在针尖增强拉曼光谱(TERS)形貌成像过程中,由于针尖与扫描台无法绝对平行、样品电子密度骤变处针尖快速升降以及扫描控制系统响应时间特性差等综合原因的影响,往往使形貌图中带有倾斜或边界面卷曲的成像背景。成像背景对样品形貌的识别和分析带来十分不利的影响,而背景扣除就是解决该问题的重要手段,也是形貌成像预处理的重要组成部分。背景扣除的原理一般是通过拟合背景的方法来扣除成像中的背景。传统的背景扣除方法是利用多项式拟合的方法对成像进行逐行的基线校正,但是该方法在处理形貌成像时常常会由于过拟合而造成样品形貌的失真,同时容易在图片上留下明显的线条纹理。针对传统方法的缺点,本文提出采用B样条曲面拟合方法,直接对样品形貌图进行曲面背景拟合,发挥B样条低阶光滑的优点,能够有效克服传统方法的缺陷。在实验中,同时利用传统方法和该方法对金单晶和合成金片的形貌图进行背景扣除,实验结果表明,两种方法都能够扣除样品形貌图中的成像背景,但与传统方法相比,所提出的方法不会造成样品形貌的失真,且不会留下线条纹理,获得了更加良好的背景扣除效果,为进一步分析样品形貌特征提供了更准确可靠的信息,是一种更加有效的TERS形貌成像背景扣除算法。     

Mesoporous chitosan‐immobilized iron tetrakis(4‐carboxyphenyl)porphyrin as a model of cytochrome P‐450 enzyme for oxidation of ethylbenzene

Mesoporous chitosan‐grafted iron tetra (4‐carboxyphenyl) porphyrin catalyst (Fe TCPP/mesp‐CTS) was prepared and investigated as a practical model for the nano‐cavity and coordinate regulation‐catalysis(CRC) function in cytochrome P‐450 enzyme. Fe TCPP/mesp‐CTS was characterized by X‐ray Diffraction (XRD), Thermogravimetry (TG), Ultraviolet–visible spectroscopy(UV‐Vis), Ultraviolet–visible– Diffuse reflectance spectroscopy (UV‐DRS), Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT‐IR), and X‐ray photoelectron spectroscopy (XPS) techniques. The catalytic activity of Fe TCPP/mesp‐CTS for ethylbenzene oxidation was investigated and it was proved to be a better catalyst than Fe TCPP/macp‐CTS based on the ethylbenzene conversion, turnover numbers(TON), and the reusability. These results are attributed to the mesocavity and CRC of amino group in Fe TCPP/mesp‐CTS. The highest ethylbenzene conversion and yields of ketone and alcohol were 24.4% and 18.2%, respectively.     

Upgrading Pectin Production from Apple Pomace by Acetic Acid Extraction

Applied Biochemistry and Biotechnology - Pectin, as one of the most widely used functional polysaccharide, can be abundantly extracted from apple pomace which is the main by-product of apple juice...