人工合成云母粉剥离细化的新方法

研究用超声波对人工合成云母粉剥离细化成片形微粉的新方法。将粒径为180～1 700μm的粗云母片用超声装置I进行剥离细化,得到d50为40.39μm的细云母粉,以X射线衍射、扫描电镜、粒度分析和计算结果为依据,探讨超声波对人工合成云母剥离细化的机制。结果表明,这种新方法克服了用轮碾机研磨时对云母表面的磨蚀与划伤的缺点,可以制备出粒度分布窄、表面光滑的片形微细云母粉。     

Analysis of Amyloid-β Peptides in Cerebrospinal Fluid Samples by Capillary Electrophoresis Coupled with LIF Detection

We report a CE-LIF method for the separation and detection of five synthetic amyloid-β peptides corresponding to an important family of CSF-biomarkers in the context of Alzheimer disease (AD). The presumed most relevant peptides (Aβ1-42, Aβ1-40, and Aβ1-38) that may support the differentiation between AD and healthy patients or other dementias were successfully detected in CSF by incorporating an immunoconcentration step prior to CE analysis of derivatized peptides. We labeled the Aβ peptides with a fluoroprobe dye before CE-LIF analysis. This reagent reacts with the amino groups of lysine residues and produced mostly ditagged Aβ peptides under the proposed experimental conditions. The labeling reaction displayed similar efficiency with each one of the five different synthetic Aβ peptides that were tested. The limit of detection of the CE-LIF method approached 280 attomoles of injected synthetic labeled Aβ peptides. We obtained excellent correlation between peak areas and peptide concentrations from 35 nM to 750 nM. For the detection of Aβ peptides in human CSF samples, we enriched the peptides by immunoprecipitation prior to the CE-LIF analysis. The comparison of the CE-LIF profiles obtained from CSF samples from 3 AD patients and 4 non-demented control subjects indicated noticeable differences, suggesting that this method, which relies on a multibiomarker approach, may have potential as a clinical diagnostic test for AD.     

大空间建筑空调气流组织设计方法的探讨

介绍了大空间气流组织设计中主要的三种方法,即计算公式法、数值模拟法和模型实验法,同时分析它们的优缺点并介绍一种综合应用的方法.     

Intermolecular interactions in blends of hyaluronic acid with poly(vinyl alcohol) and ethylene-vinyl alcohol copolymers

Films from blends of hyaluronic acid with poly(vinyl alcohol) and with ethylene-vinyl alcohol copolymers were prepared from solutions in water and dimethylsulfoxide by a casting method. The study of the interactions between the natural and synthetic component has been carried out through thermal and morphological analysis. The results show that the crystallinity of poly(vinyl alcohol) and its copolymers decreases with increasing hyaluronic acid content and these crystallizable polymers exhibit no tendency to crystallize when hyaluronic acid content is more than 80 wt%. The relatively good miscibility in these blends may be due to the capacity of the natural and synthetic component, each with abundant hydroxyl groups, to interact mutually through hydrogen bonding. The presence of such interactions was supported by the observation of the melting point depression of the synthetic component in thermal analysis of the blends. Melting point depression was more accentuated in melt recrystallized blends. These results suggest that the interactions between the two polymers are enhanced if the blends are brought close to the melting point of the synthetic component.     

测量不确定度直接评定法和综合评定法的几个典型实例第一讲直接评定法及其实例

采用直接评定法评定了带肋钢筋拉伸性能、金属材料维氏硬度检测结果的测量不确定度,用综合评定法评定了金属材料夏比缺口冲击试验、洛氏硬度检测结果的不确定度。结果表明,综合评定法在这些典型实例中解决了金属材料理化检测结果测量不确定度评定的某些难点。     

Caffeine in your drink: natural or synthetic?

Owing to possible adulteration and health concerns, it is important to discriminate between natural and synthetic food ingredients. A new method for compound-specific isotope analysis (CSIA) by coupling high-temperature reversed-phase liquid chromatography to isotope ratio mass spectrometry (HT-RPLC/IRMS) was developed for discrimination of natural and synthetic caffeine contained in all types of drinks. The analytical parameters such as stationary phase, column inner diameter, and column temperature were optimized for the separation of caffeine directly from drinks (without extraction). On the basis of the carbon isotope analysis of 42 natural caffeine samples including coffee beans, tea leaves, guaraná powder, and maté leaves, and 20 synthetic caffeine samples from different sources by high-temperature reversed-phase liquid chromatography coupled to isotope ratio mass spectrometry, it is concluded that there are two distinguishable groups of caffeine δ(13)C-values: one between -25 and -32‰ for natural caffeine, and the other between -33 and -38‰ for synthetic caffeine. Isotope analysis by HT-RPLC/IRMS has been applied to identify the caffeine source in 38 drinks. Four mislabeled products were detected due to added but nonlabeled synthetic caffeine with δ(13)C-values lower than -33‰. This work is the first application of HT-RPLC/IRMS to real-world food samples, which showed several advantages: simple sample preparation (only dilution), high throughput, long-term column stability, and high precision of δ(13)C-value. Thus, HT-RPLC/IRMS can be a very promising tool in stable isotope analysis of nonvolatile compounds.     

Discontinuous surface measurement by wavelength-tuning interferometry with the excess fraction method correcting scanning nonlinearity

Wavelength-tuning interferometry can measure surface shapes with discontinuous steps using a unit of synthetic wavelength that is usually larger than the step height. However, measurement resolution decreases for large step heights since the synthetic wavelength becomes much larger than the source wavelength. The excess fraction method with a piezoelectric transducer phase shifting is applied to two-dimensional surface shape measurements. Systematic errors caused by nonlinearity in source frequency scanning are fully corrected by a correlation analysis between the observed and calculated interference fringes. Experiment results demonstrate that the determination of absolute interference order gives the profile of a surface with a step height of 1?mm with an accuracy of 12?nm.     

"双时域四谱"法在振动信号分析中的应用

准确地提取各种典型故障的振动信号的时频域特征是进行机械故障诊断的关键．为了综合提高诊断能力,突出信号特征,本文介绍了一种信号分析与故障诊断新方法,该方法以“双时域四谱”综合诊断法为理论基础．具体应用双时域（原始时域和包络时域分析）和四频域（功率谱分析、细化谱分析、解调谱分析、倒频谱分析）的振动诊断方法,综合各自的诊断优势,对用特征振动信号进行诊断的问题进行了研究,并阐述了这些方法的特点和功能．     

The PUFF equation of state parameters for synthetic rubber

The PUFF EOS (equation of state) is widely used to describe the mixed state of materials (mixture of gas state and solid state), and the Hugoniot parameters, Grüneisen coefficient and the sublimation energy are key parameters in PUFF EOS. In this paper, the method to determine these parameters for synthetic rubber is presented. First of all, the Hugoniot parameters at low pressure range for synthetic rubber are measured by shock compression experiments as 1.23 km/s and 3.02. Then the Grüneisen coefficient and the sublimation energy for synthetic rubber are determined with a new inverse analysis method, i.e. they are derived via the comparison between the blow-off impulse and thermal shock wave value obtained from the electron beam radiation experiments and which obtained from numerical simulation with our computer code DRAM (Dynamic Response Analysis of Material) in the same conditions as the experiments, and the results are the Grüneisen coefficient 5.02, the sublimation energy 0.9 kJ/g. Finally, our results are proved reliable via the comparison between the Grüneisen coefficient value obtained from the Huang equation with the shock compression experiments and the Grüneisen coefficient value obtained from the inverse analysis method.     

Geometric transformation based independent component analysis for mixed image separation

Abstract

An independent component analysis (ICA) method for image separation by geometric transformation of a scatter diagram is proposed. Geometric transformation and normalization are used to project mixed image signals to independent component space. This method includes four procedures: data correction, whitening, geometric rotation, and slant compensation. Several synthetic mixed image and real applications are used to evaluate the performance of the proposed method. From experimental results, mixed images are separated accurately by the proposed method.     

Dual-wavelength interferometric technique with subnanometric resolution

A new fringe subdivision method that employs a large synthetic wavelength to subdivide fringes formed by a small single wavelength is proposed. Based on this subdivision method, we demonstrate a novel dual-wavelength interferometric technique with subnanometric resolution, whose potential fringe subdivision factor derived from an evaluation of the interferometer can reach up to 1/440,000. Theoretical analysis and experimental results with a resolution of 0.05 nm are presented to show the feasibility of the interferometric technique.     

Photothermal gas analyzer for simultaneous measurements of thermal diffusivity and thermal effusivity

In this paper, we describe a new, simple, and fast photothermal method for simultaneous measurements of two important gas thermal properties: thermal diffusivity and thermal effusivity. The method consists essentially in combining a photoacoustic cell and a thermal wave pyroelectric cell enclosed in a single compact gas analyzer. The photoacoustic cell is kept filled with synthetic air and sealed. The pyroelectric cell is also filled with synthetic air, and after some warm up time, the synthetic air is exchanged to the gas of interest. It is shown that the analysis of the transient and saturation signals of both photoacoustic and pyroelectric cells is capable of measuring the thermal properties with an accuracy of 3%. This particular capability of performing simultaneously the measurements of thermal diffusivity and thermal effusivity allows us to carry on the complete characterization of the thermal properties of gases.     

Improved version of the synthetic eddy method for setting nonstationary inflow boundary conditions in calculating turbulent flows

One method for generating synthetic turbulence, i.e., the synthetic eddy method, is tested by means of the example of canonical turbulent shear flows (plane-channel and boundary-layer flows). A modification of the method, differing from the original version by the determination of the linear scale of synthetic eddy structures, is proposed. The synthetic field of turbulent fluctuations evolves more quickly to the physically realistic one when the modified method is used instead of the original one. The friction coefficient and profiles of the average velocity and Reynolds stresses also deviate less and recover faster if the modified method is used.     

全自动固相萃取/超高效液相色谱串联质谱法检测食品中的9种合成色素

建立了超高效液相色谱串联质谱法检测食品中柠檬黄、苋菜红、胭脂红、日落黄、亮蓝、新红、靛蓝、诱惑红、赤鲜红9种合成色素的快速检测方法。采用反相-弱阴离子交换固相萃取小柱,在Labtech的Speline全自动固相萃取平台上实现对样品的连续、自动化处理过程,极大地提高了工作效率。净化液经Agilent XDB C18色谱柱,以甲醇和10mmol/L乙酸铵溶液为流动相梯度洗脱,6min内实现基线分离。采用电喷雾正离子模式（ESI＋）电离,多反应监测（MRM）模式定量检测。9种合成色素的质量浓度在10-500μg/L的范围内与其响应值呈线性关系,其检出限（3S/N）在0.009-0.044mg/kg之间。将该方法应用于食品中合成色素的测定,其回收率范围为88.8%-108.2%,相对标准偏差（n=6）均小于5%。该方法高效、快速、准确,可满足批量化检测的需求。     

属性综合评价系统在岩爆发生和烈度分级中的应用

应用属性数学理论,建立了岩爆发生预测和烈度分级的属性识别模型。选取影响岩爆的主要因素:如最大切向应力σθ、单轴抗压强度σc、单轴抗拉强度σt以及弹性能量指数Wet,以σθ/σc、σc/σt以及Wet作为岩爆评价指标和烈度分级标准;构造了属性测度函数;定义了单指标属性测度和样本综合属性测度的计算方法。利用国内外一些重大岩石地下工程实例对模型进行了验证,由于评判结果与实际情况基本一致,并且与模糊综合评判法、物元可拓评判法等的评判结果有较好的一致性,从而验证了属性识别模型应用于岩爆预测预报的可行性和有效性。此外,利用该模型对某水电站工程和秦岭隧道工程的岩爆情况进行了评判,结果与人工神经网络法、距离判别法等的评判结果一致。     

正交各向异性复合材料孔板性能参数识别测点的最优布置

基于静态位移的测量和边界元分析,性能参数识别的问题转化为极小化目标函数的问题,其中目标函数定义为测量位移与边界元计算的位移之差的平方和。求解此优化问题采用Levenberg-Marquardt算法。通过该算法适定性的分析,提出了考虑诸多因素综合影响的优化测点布置的方法。该方法的有效性得到了数值算例的验证,算例结果表明测点布置对正交各向异性复合材料孔板性能参数识别的结果有较大的影响。提出的方法可以找出测点的最优布置,得到令人满意的识别结果。     

High-sensitivity analysis of six synthetic musks by ultra-performance liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry

The occurrence and potential toxicity of synthetic musks in environmental media have aroused concerns for the impacts of these chemicals on ecosystems and human health. Here, we present the first method using ultra-performance liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry (UPLC-APPI-MS/MS) for analysis of the six most important synthetic musks. Analysis was performed on an API 3000 triple quadrupole equipped with a PhotoSpray APPI source. Two pairs of precursor/product ions are presented that are essential for confirmation. Chromatographic separation is completed in 7 min in the positive mode and 5.1 min in the negative mode. Furthermore, three dopant solutions (0.5% anisole in toluene, 0.5% 2,4-difluoroanisole (DFA) in bromobenzene, and 0.5% DFA in chlorobenzene) are compared in terms of sensitivity, linearity, precision, and accuracy. The best sensitivity is associated with 0.5% anisole in toluene as the dopant; all LODs are below 6 pg. The linear range is 5 to 500 ppb with fairly good precision and accuracy. This analytical method has also proven its applicability by analyzing real air samples. In summary, we present a fast, sensitive, and reliable UPLC-APPI-MS/MS method for six important synthetic musks; it can be readily applied to environmental studies.     

湿膜厚度规校准装置研究

分析了湿膜厚度规在建筑、喷涂等行业的应用技术要求,提出了一套实用并满足技术要求的校准装置设计方案,最后给出了误差源分析和校准结果的不确定度估算.     

2－甲硫基－5－甲氧基－苯并噻唑合成方法的研究

以间氨基苯酚为原料，合成２－甲硫基－５－甲氧基－苯并噻唑，原料易得，合成路线短。该化合物用作感蓝染料的中间体。