酱香型酒香气成分研究3．珍酒、茅台酒前香成分的分离及气相色谱／质谱分析

用Ｎ２吹扫－冷凝方法分离、收集珍酒、茅台酒的前香。收集液经过感官评定，确认为珍酒、茅台酒的前香。用气相色谱／质谱联用方法研究它们的化学组成。鉴定了１２种化合物，并测定了它们的相对含量。     

酱香型酒香气成分研究：3.珍酒,茅台酒前香成分的分离及气相色谱…

用Ｎ２吹扫－冷凝方法分离、收集珍酒、茅台酒的前香。收集液经过感官评定，确认为珍酒、茅台酒的前香。用气相色谱／质谱联用方法研究它们的化学组成。鉴定了１２种化合物，并测定了它们的相对含量。     

食品中苯甲酸、山梨酸含量测量不确定度的评估

对按照SN 04024—87方法测定食品中苯甲酸、山梨酸含量的测量不确定度进行评估。该测量方法为相对测量法，前处理等过程直接用B类评定比较困难，直接以多次重复测量数据为依据，即以A娄评定为主、B类评定为辅的方法，结果更为客观、准确，完全适合实际操作。     

HPLC法测定己烯雌酚样品纯度的不确定度评定

根据国家质量技术监督局批准发布的JJF1059-1999计量技术规范《测量不确定度评定与表示》[1],并参考有关文献[2,3], 对HPLC法测定己烯雌酚样品纯度的不确定度进行了评定.本文介绍了该评定方法和评定结果.     

非均匀梯度尿液分析仪测量不确定度评定

对非均匀梯度尿液分析仪测量不确定度进行评定。分别采用对称区间不确定度评定方法、选择校准点左右两侧分辨力较大者进行不确定度评定的方法、不对称区间不确定度评定方法对非均匀梯度尿液分析仪测量不确定度进行评定。采用常规的对称区间不确定度评定方法所得出的置信区间左右对称，不符合这类仪器低浓度范围分辨能力高于高浓度范围分辨能力的特性。如果选择校准点左右两侧分辨力较大者进行不确定度评定，虽较为稳妥，但其置信区间宽，不确定度偏大，测量结果准确度偏低。而通过不对称区间不确定度评定方法所得出的置信区间，左侧比右侧窄，且与仪器梯度相符，适合用于非均匀梯度尿液分析仪测量不确定度的评定。     

基于HS-GC-IMS分析爆珠香精挥发性风味成分差异

采用顶空气相色谱-离子迁移谱（HS-GC-IMS）技术,对不同清新玫瑰爆珠样品中的香精挥发性成分进行鉴定,并通过感官评价,结合主成分分析（PCA）、偏最小二乘判别分析（PLS-DA）、偏最小二乘回归法（PLSR）等多元统计方法识别判定不同样品的主要风味成分差异。结果表明：(1)感官评价显示该爆珠样品风格特征主要以花香、果香、木香为主,并辅以青香、甜香与酒香香韵,不同样品在花香、果香属性上呈显著差异（p<0.05）;(2)GC-IMS非靶向定性出样品中22种主要的挥发性风味组分,其中醇类8种、酯类3种、酮类3种、醛类3种、烯烃类3种、酸类1种、吡嗪类1种,且指纹图谱直观显示出挥发性较强的醇类、酯类等香气化合物在样品间差异明显;(3)PCA、PLS-DA能对不同样品进行有效区别,并筛选出10个特征差异组分（VIP>1）,PLSR得出样品感官差异主要与2-甲基丁酸乙酯、丁酸乙酯、环己酮、苯乙酮、辛醛、正丙醇和芳樟醇有关。该方法可有效区分不同清新玫瑰爆珠样品,其判定结果与感官评价结果一致,具有准确可靠、可视化强等特点,能够为烟用爆珠产品感官质量快速检验提供技术支持。     

加强实验操作考核客观评定《分析化学》课程成绩

在搞好课堂理论教学的同时，要加强实验课程的教学和考核。提出了实验操作考核的具体内容及方法。强调正确掌握定量分析仪器操作的重要性。将学生理论考试成绩与实验操作考核成绩有机结合起来，客观评定该课程成绩     

原子荧光光谱法测定方便米饭中砷的测量不确定度评定

介绍了原子荧光光谱法测定方便米饭中砷的测量不确定度评定方法,该法根据最小二乘法原理计算校准曲线的标准不确定度,并充分分析和识别分析过程中的不确定度来源,较为全面地评定了测量不确定度,该法对原子吸收光谱法、电感耦合等离子发射光谱法和原子荧光光谱法等测定结果的不确定度评定具有参考作用。     

ICP-AES法测定钯碳催化剂中钯的不确定度的评定

通过ICP-AES法测定钯碳催化剂中钯的不确定度的评定实践，分析了该方法测定过程的不确定度来源、建立了数学模型并计算了各标准不确定度分量、合成标准不确定度、展伸不确定度等。     

电感耦合等离子体质谱法测定镍基高温合金中磷含量的不确定度评定

采用电感耦合等离子体质谱(ICP-MS)法测定镍基高温合金中磷杂质含量,对该测定方法的不确定度进行评定。建立了不确定度评定的数学模型,对不确定度的来源进行了全面分析,通过计算得到扩展不确定度。采用ICP-MS法测定YSBC 41503-2012标准物质中的磷含量,测定值为0.0035%,测定结果与证书参考值一致。按照建立的不确定度评定方法得扩展不确定度为0.0002%(k=2)。该方法适用于ICP-MS法测定高温合金中磷含量的不确定度评定。     

WAVELENGTH-DEPENDENT ACTION DICHROISM: A THEORETICAL CONSIDERATION

Abstract— For a model structure the wavelength dependence of action dichroism is computed as a function of the angle(△) between the transition moments at two different wavelengths. With as small an angle as △ α = 20. inversion of action dichroism for parallel vs perpendicularly vibrating radiation is expected for different absorption bands if the sensory pigment molecules are in proper orientations. Thus published data on opposite action dichroism in the blue vs near-UV range are compatible with flavins as sensory pigments, although the calculations must not be considered as proof for the flavin hypothesis.     

A new linear method for analyzing four‐way multiblock tables: STATIS‐4

A new four‐way multiblock method is proposed to study the links between more than two sets of data tables (several multiblocks) measured on the same observations. This method, called STATIS‐4, generalizes the STATIS method to more than one set of matrices. In its first step, STATIS‐4 is searching for one consensus for each multiblock and a global consensus summarizing all the previous ones as good as possible. Some graphical representations can be made to visualize the proximities between the tables within a multiblock and to visualize those between all the multiblocks. Moreover, plots of the observations for each table, each multiblock and global observations can be made. The theory of STATIS‐4 and the algorithm used to obtain the optimal solutions are presented. Moreover, a real sensory dataset is studied with STATIS‐4. Copyright © 2008 John Wiley & Sons, Ltd.     

Universal method for computation of electrostatic potentials

A computational approach to determine electrostatic interaction and gravitational potentials by performing direct numerical integration is presented. The potential is expanded using finite-element functions of arbitrary order. The method does not involve any solutions of systems of linear equations. The potential is instead obtained as a sum of differential contributions. Thus, no boundary conditions for the potential are needed. It is computationally efficient and well suited for parallel computers, since the innermost loops constitute matrix multiplications and the outer ones can be used as parallel indices. Without using prescreening or other computational tricks to speed up the calculation, the algorithm scales as N4/3 where N denotes the grid size.     

Direct measurement of the angular dependence of the single-photon ionization of aligned N2 and CO2

By combining a state-of-the-art high-harmonic ultrafast soft X-ray source with field-free dynamic alignment, we map the angular dependence of molecular photoionization yields for the first time for a nondissociative molecule. The observed modulation in ion yield as a function of molecular alignment is attributed to the molecular frame transition dipole moment of single-photon ionization to the X, A and B states of N2(+) and CO2(+). Our data show that the transition dipoles for single-photon ionization of N2 and CO2 at 43 eV have larger perpendicular components than parallel ones. A direct comparison with published theoretical partial wave ionization cross-sections confirms these experimental observations, which are the first results to allow such comparison with theory for bound cation states. The results provide the first step toward a novel method for measuring molecular frame transition dipole matrix elements.     

Analysis of dielectric and conductive dispersion above Tg in glass-forming molecular liquids

Dynamics of the nonassociated supercooled liquids N-methyl-epsilon-caprolactam (NMEC) and glycerol in the frequency domain are investigated using full complex-nonlinear-least-squares fitting of immittance spectroscopy data for appreciable temperature ranges above the glass transition. Such fitting, not previously used for these materials, helps to identify physical processes responsible for the data and elements of their common behavior. Several different fitting models were applied to find a physically plausible best-fitting one to distinguish quantitatively between the dielectric effects of dipoles and the conductive effects of mobile ions. The utility of many composite fitting models was investigated, and although a pure conductive-system dispersive (CSD) fitting model led to good but physically unrealistic fits of all data sets, the dielectric-system dispersive (DSD) Davidson-Cole model best fitted the alpha-dispersion part of the responses. Nevertheless, the series combination of such a DSD model and a separate CSD model (one not associated with electrode effects) was found to yield much better fitting of the data for both materials. Although the CSD model plays somewhat the role of the conventional parallel DSD Johari-Goldstein beta-response, it is here in series and arises from mobile impurity-ion effects rather than from dipolar ones. Previous analyses of data of the present and other molecular materials have often involved two DSD models in parallel, but fitting with such a composite model led here to less physically plausible parameter values and ones with appreciably more uncertainties. Surprisingly, the series DSD and CSD composite-model fits led to comparable estimated values of the NMEC and glycerol dielectric strength parameters, as well as to the nearly equal small thermal activation energies of these parameters.     

Fluorometric monitoring of organic reactions on solid phase

The direct monitoring of reaction progress on solid supports by fluorescence spectroscopy is described. An immobilized fluorescent tracer molecule (dansyl chloride) is used to monitor the reaction on OH resins (Argopore Wang, PS Wang, and Argogel Wang), both in batch and in parallel chemistry. Fluorescence measurements were obtained directly on solid phase. The method demonstrated to be a valuable tool for the quantitative determination of resin-bound hydroxyl groups, to study reaction kinetics and for continuously monitoring the progress of the conversion of the hydroxyl resins into the chlorinated ones. The procedure proposed is highly sensitive compared to the traditional ones. The system can be extended to monitor a variety of reactions on solid supports, and in conjunction with a well-established technique such as flow analysis, basic studies on solid-phase become possible.     

A Solution-Phase Parallel Synthesis of 5-Substituted 3,6-Dihydro-7H-1,2,3-triazolo[4,5-d]pyrimidin-7-ones

5‐Substituted 7H‐1,2,3‐triazolo[4,5‐d]pyrimidin‐7‐ones ( 4 ) were rapidly prepared by a solution‐phase parallel synthetic method, which includes aza‐Wittig reaction of iminophosphorane ( 1 ) with phenyl isocynate to give carbodiimide ( 2 ) and subsequent reaction of 2 with various amine and alcohols in the presence of catalytic amount of sodium alkoxide in a parallel fashion.     

Effect of microhydration on the guanidinium···benzene interaction

The effect of microhydration on the interaction of guanidinium cation with benzene has been studied by employing ab initio calculations. Four different structural arrangements were considered for the guanidinium···benzene interaction to which up to six water molecules were added. T-shaped structures are usually the most stable, but as water molecules are included the energy differences with the parallel structures decrease, reaching a point where parallel complexes are even more stable than T-shaped ones. Therefore, the inclusion of water molecules promotes a change in the structure of the cation···π contact. The analysis reveals that these stability changes are more related with the structure of the hydrating water molecules than to a modulation of the cation···π interaction. Already with three water molecules, one water molecule in the T-shaped complex has to be located in the second solvation shell, whereas in parallel structures this occurs with four water molecules. As a consequence energy differences among structures decrease. The calculations show that the nature of the interaction is almost unaffected in T-shaped structures, whereas an important dispersion increment is observed in parallel ones, though its overall effect is small.     

A novel parallel algorithm for large-scale Fock matrix construction with small locally distributed memory architectures: RT parallel algorithm

We developed a novel parallel algorithm for large-scale Fock matrix calculation with small locally distributed memory architectures, and named it the "RT parallel algorithm." The RT parallel algorithm actively involves the concept of integral screening, which is indispensable for reduction of computing times with large-scale biological molecules. The primary characteristic of this algorithm is parallel efficiency, which is achieved by well-balanced reduction of both communicating and computing volume. Only the density matrix data necessary for Fock matrix calculations are communicated, and the data once communicated are reutilized for calculations as many times as possible. The RT parallel algorithm is a scalable method because required memory volume does not depend on the number of basis functions. This algorithm automatically includes a partial summing technique that is indispensable for maintaining computing accuracy, and can also include some conventional methods to reduce calculation times. In our analysis, the RT parallel algorithm had better performance than other methods for massively parallel processors. The RT parallel algorithm is most suitable for massively parallel and distributed Fock matrix calculations for large-scale biological molecules with more than thousands of basis functions.