化学计量学非线性偏最小二乘算法进展评述

评述了偏最小二乘法(PLS)近年来非线性化的进展以及重要算法的原理、特性和应用。一类是对自变量进行非线性前处理的方法,包括二次变换、Chebychev变换和基于机理的变换;另一类是基于内部非线性映射的PLS,主要有多项式映射、样条函数映射、由遗传算法辅助实施的任意非线性映射和神经网络映射;介绍了具有类似功能的正交网模型。本文还就算法的普适性、稳健性和简易性,及其非线性化的演变进程予以评述、总结和展望。     

HATR-FTIR-排序法识别中药材紫花地丁及其伪品的研究

采用水平衰减全反射傅里叶变换红外光谱(HATR-FTIR)法测定了紫花地丁及其伪品如白花地丁、犁头草、辽宁堇菜及匍伏堇的根木质部和茎外表皮部的傅里叶变换红外光谱,采用主成分分析法(PCA)比较了正伪品之间的差异程度。结果表明：基于傅里叶变换红外光谱的主成分分析在反映同科同属不同种植物化学组成差异程度上具有应用价值。     

CO三重带系d3Δ-a3Π(4,0)和(5,0)带激光光谱研究

光外差磁旋转浓度调制激光光谱技术属于一种高灵敏度的吸收光谱测量方法 ,可以用于瞬态分子和激发态分子光谱的检测。采用这种技术分别在 16 4 0 0～ 16 6 5 0cm-1和 174 5 0～ 1775 0cm-1波段内直接观测到CO三重带系d3 Δ←a3 Π(4,0 ) (5 ,0 )振转吸收光谱。这种跃迁的上态d3 Δ1(v =4 ) ,d3 Δ2 (v =4 ) ,d3 Δ1(v =5 )分别与A1Π(v =0 ) ,D1Δ(v =0 )和A1Π(v =1)态存在微扰相互作用。通过对所测量到的 CO三重带系 (4,0 ) (5 ,0 )振转谱带作了包含微扰相互作用在内的分析 ,获得了上态d3 Δ(v =4 ,5 )的精确的分子转动光谱常数。     

Arene Trifunctionalization with Highly Fused Ring Systems through a Domino Aryne Nucleophilic and Diels–Alder Cascade

A convenient and efficient domino aryne process was developed under transition‐metal‐free conditions to generate a range of tetra‐ and pentacyclic ring systems. This transformation was realized via a 1,2‐benzdiyne through a nucleophilic and Diels–Alder reaction cascade using styrene as the diene moiety. Three new chemical bonds, namely one C?N and two C?C bonds, and two benzofused rings could be constructed concomitantly, which was made possible by distinct chemoselective control at both the 1,2‐aryne and 2,3‐aryne stages. Moreover, in‐depth studies were carried out on the domino aryne precursors and controlling the diastereoselectivity.     

Simulation of diesel spray combustion using LES and a multicomponent vapourisation model

Diesel spray and combustion in a constant-volume engine cylinder was simulated by a large eddy simulation (LES) approach coupling with a multicomponent vapourisation (MCV) modelling. The simulation focused on the inclusion of the interaction between fuel spray and gas-phase turbulence flow at the sub-grid scale. The LES was based on the dynamic structure sub-grid model, and an additional source term was added to the filtered momentum equation to account for the effect of drop motion on the gas-phase turbulence. The multicomponent drop vapourisation modelling was based on the continuous thermodynamics approach using a gamma distribution to describe the complex diesel fuel composition and was capable of predicting a more complex drop vapourisation process. The effect of gas-phase turbulence flow on the fuel drop vapourisation process was evaluated through the solution of the gas-phase moments of the distribution in the present LES framework. A non-evaporative spray in a constant-volume engine cylinder was first simulated to examine the behaviours of LES, in comparison with a Reynolds-averaged Navier–Stokes (RANS) simulation based on the RNG k–? model. More realistic diesel spray structures and improved agreement on liquid penetration length with the corresponding experimental data were predicted by the LES, using a grid resolution close to that of RANS. A more comprehensive simulation of diesel spray and combustion in cylindrical combustor was also performed. Predicted distributions of soot particles were compared to the experimental image, and improved agreement with the experimental data was also observed by using the present LES and MCV models. Consequently, results of the present models proved that improved overall performance of the fuel spray simulation can be achieved by the LES without a significant increase in the computational load compared to the RANS.     

Synthesis and Herbicidal Activity of Novel β-Methoxyacrylate Derivatives Containing a Substituted Phenylpyridine Moiety

In this paper, a series of new β-methoxyacrylate derivatives containing a substituted phenylpyridine moiety was synthesized and bioassayed. The structures of all compounds were confirmed by nuclear magnetic resonance(NMR) and high-resolution mass spectrometry(HRMS). Preliminary bioassays demonstrated that compound 8d showed more than 95% inhibition against Brassica juncea and Chenopodium serotinum at 37.5 g a.i./10⁴ m², when compared with the positive control halauxifen-methyl at 150 g a.i./10⁴ m². The present work demonstrated that compound 8d exhibited the more promising herbicidal activity and may serve as a new herbicidal agent for herbicide.     

ZrV2结构、弹性和热力学性质的第一性原理计算

采用基于密度泛函理论的第一性原理平面波赝势方法研究ZrV₂的晶体结构和弹性,利用准谐Debye模型计算在不同温度(T=0~1200 K)和不同压强(P=0~20 GPa)下ZrV₂的热力学性质,包括弹性模量与压强,热熔与温度,以及热膨胀系数与温度和压力的关系.结果表明:计算的ZrV₂晶格常数与实验值符合较好,晶体材料的弹性常数随着压力增加而增加;在一定温度下,相对体积、热熔随着压强的增加而减小,德拜温度、弹性模量随着压强的增加而增加,且高压下温度对ZrV₂热膨胀系数的影响小于压强的影响.     

Kinematics and Mechanical Properties Analyses on Vibration Converter of Intelligent Damper for Drill Strings

Taking vibration converter of intelligent damper for drill strings as the study object, this paper analyzes the influential factors of motion state of the ball and conducts an explicit dynamics simulation by establishing a mechanics model of vibration converter. The study basis is Newton's laws of motion, D'Alembert's principle and Hertz contact theory. And we use world coordinate system, rotating coordinate system and Frenet coordinate system to deduce kinematics equations of vibration converter. The ultimate result demonstrates that the axial velocity and maximum contact stress change with the increment of ball diameter and helix angle. It also proves the validity of our derived kinematics and mechanical models and provides a good consultant value for the design and theoretical arithmetic of vibration converter for intelligent damper of drill strings.     

壳寡糖-水解麦醇溶肽共聚物的制备和表征

以初步纯化的微生物转谷氨酰胺酶(MTGase)催化合成壳寡糖-水解麦醇溶肽共聚物,研究最佳合成条件并对共聚物进行了表征。 结果表明,合成共聚物的最佳条件是:壳寡糖/水解麦醇溶肽质量比为1:40,在pH值6.00~6.50、50 ℃下搅拌反应50 min,共聚物的生成率达到60%~70%。 红外光谱分析显示,与壳寡糖相比,由于引入的吸电子基团产生诱导效应,共聚物酰胺-C=O基的伸展振动峰向高波数位移动且吸收强度加强。 由DTA分析可知,共聚物在60.91 ℃处失水,387.55 ℃处熔融,665.25 ℃处开始彻底分解,与壳寡糖和麦醇溶肽的差异明显。 XRD分析可知,共聚物的结晶度显著降低,晶胞数据不同于壳寡糖,表明其不易结晶。 HPLC分析表明,共聚物主要由两个组分构成,占共聚物总量的80.6%,其相对分子质量分别为66069和27285。 共聚物不溶于水及多种有机溶剂,微溶于1%NaOH,溶解度为0.184 mg/100 g。 熔程为162~163 ℃。     

混和菌株发酵富含共轭亚油酸酸奶的特性

功能性酸奶作为一种保健食品逐渐被人们熟知,其特别之处在于添加了具有独特功效的物质。本文利用植物乳杆菌R6、德氏乳杆菌保加利亚亚种、嗜热链球菌3株益生菌发酵添加了亚油酸的脱脂乳。其中植物乳杆菌R6能合成共轭亚油酸(CLA),从而制备出富含CLA的酸奶。进一步优化发酵条件,探寻最佳的发酵工艺。最后利用PCR-DGGE分析酸奶菌群变化与CLA合成关系,得出酸奶中混合菌株生长良好,相互之间没有抑制作用,因此,既能保证酸奶的品质,也保证了CLA的合成。 更多还原