On-line Method for Montelukast Determination in Bile Salt Medium with Multivariate Optimization and Fluorescent Detection

Journal of Analytical Chemistry - The present development involved a flow injection strategy using a mini-column of multiwalled carbon nanotubes and fluorescent detection (λex of 283 nm,...     

Plasmon-induced terahertz absorption and photoconductivity in a grid-gated double-quantum-well structure

The terahertz absorption spectra of plasmon modes in a grid-gated double-quantum-well field-effect transistor structure is analyzed theoretically and numerically using the scattering matrix approach and is shown to faithfully reproduce strong resonant features of recent experimental observations of terahertz photo-conductivity in such a structure.     

Simple Constructions of Almost k-wise Independent Random Variables

We present three alternative simple constructions of small probability spaces on n bits for which any k bits are almost independent. The number of bits used to specify a point in the sample space is (2 + o(1)) (log log n + k/2 + log k + log 1/?), where ? is the statistical difference between the distribution induced on any k bit locations and the uniform distribution. This is asymptotically comparable to the construction recently presented by Naor and Naor (our size bound is better as long as ? < 1/(k log n)). An additional advantage of our constructions is their simplicity.     

Determination of physical properties of bitumens by use of near-infrared spectroscopy with neural networks. Joint modelling of linear and non-linear parameters

The fact that bitumens behave as non-Newtonian fluids results in non-linear relationships between their near-infrared (NIR) spectra and the physico-chemical properties that define their consistency (viz. penetration and viscosity). Determining such properties using linear calibration techniques [e.g. partial least-squares regression (PLSR)] entails the previous transformation of the original variables by use of non-linear functions and employing the transformed variables to construct the models. Other properties of bitumens such as density and composition exhibit linear relationships with their NIR spectra. Artificial neural networks (ANNs) enable modelling of systems with a non-linear property-spectrum relationship; also, they allow one to determine several properties of a sample with a single model, so they are effective alternatives to linear calibration methods. In this work, the ability of ANNs simultaneously to determine both linear and non-linear parameters for bitumens without the need previously to transform the original variables was assessed. Based on the results, ANNs allow the simultaneous determination of several linear and non-linear physical properties typical of bitumens.     

种植沙生植物--沙棘改善内蒙古地区生态环境

结合内蒙古地区现状，对沙棘的生物学和生态学特性、沙棘属植物化学成分和微量元素及种植沙生植物——沙棘的重要性和必要性进行了详细的研究和探讨。研究表明，沙棘属植物具有极强的生态适应性并富含多种营养成分和生物活性物质，并以耐干旱、耐瘠薄、萌蘖及固氮能力强等特点被称为治理非宜林地水土流失、改善生态环境的先锋树种。种植沙棘是治理内蒙古脆弱生态环境最经济、最有效的措施，是贫瘠的不毛之地发展经济、增加收入的经济树种。另外．种植沙棘的技术简便，容易掌握，投资少，见效快。     

内蒙古地区天然植物沙棘果中黄色素的提取工艺及性质研究

以内蒙古地区沙棘果实为原料，研究了提取黄色素的工艺条件，同时对该色素的性质进行了初步探讨。结果表明，以95％的乙醇溶液作浸提剂，提取的黄色素浓度最高，工艺流程简单易行，且无毒，无污染。对提取的黄色素进行的性质试验表明，沙棘黄色素对光、热具有较好的稳定性，适用于酸性或弱碱性的食品中，葡萄糖、氧化剂(H2O2)、还原剂(Na2SO3)等食品添加剂均无明显影响以上结果为这种优良天然色素的开发与应用提供了参考。     

Volumetric Properties of the Ternary System 1,4-Dioxane + Butyl Acrylate + Ethyl Acrylate and Its Binary Butyl Acrylate + Ethyl Acrylate at 298.15 K

Densities of the ternary system 1,4-dioxane + butyl acrylate + ethyl acrylate and its binary butyl acrylate + ethyl acrylate have been measured in the whole composition range, at 298.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes of the binary system are positive and were correlated with the Redlich–Kister equation and with a series of Legendre polynomials. Several models were used to correlate the ternary behavior from the excess molar volume data of their constituent binaries and were found equally good to fit the data. The best fit was based on a direct approach, without information on the component binary systems.