基于红外光谱的改性沥青中SBS掺量测试分析

准确的测试改性沥青中的SBS掺量有助于加强其质量控制。本研究分析了基质沥青和SBS掺量为3．6％，4．0％，4．4％，4．8％的改性沥青红外光谱的特征，选择测量SBS掺量的特征峰值，提出了基于红外光谱的改性沥青中SBS掺量测试分析方法。结果表明：SBS中反式丁二烯可作为测定SBS掺量的指标；反式丁二烯在968cm。处吸光度和SBS掺量线性关系良好，可基于此建立SBS定量测试的标准曲线；应用傅里叶变换红外光谱技术可实现SBS改性沥青中SBS含量的准确、快速测试。     

Ferroceneboronic acid for the electrochemical probing of interactions involving sugars

Ferroceneboronic acid (FcBA) was used as a redox-active probe suitable for monitoring of diol–boronate interactions. Voltammetric and amperometric measurements allowed to detect FcBA forms – free and bound in the boronate complex. In this way, the complexation interaction was studied for a set of saccharide molecules as model diols and the corresponding affinity equilibrium constants were determined. A shift of the peak potential on voltammograms accompanying formation of the boronate complex with FcBA was proposed as a probe for electrochemical characterization of surface-confined diol-containing structures. The model experiments were carried out using sorbitol- and 1,6-hexandiol-modified polyepichlorhydrin conjugates deposited on the electrodes; the former compound was able to form the boronate complex while no change of the peak potential for the latter conjugate was observed. This approach seems promising for artificial bioelectronic affinity receptors and technology of reagentless biosensors where the binding interaction directly stimulates a measurable electrochemical event.     

Relative Adhesion Measurement for Thin Film Microelectronics Structures

There is a difference between technologically-important adhesion or practical adhesion, and fundamental or basic adhesion. What is important in the understanding of fundamental adhesion may be of insignificant interest to technology. A manufacturer is interested in how to improve the reliability of the structure being built should an interface problem exist, rather than knowing the precise value of the fundamental adhesion. It is not possible to measure fundamental adhesion for technologically-important structures due to the inability to account for all energy dissipating processes during the test. Adhesion measurements are plagued with the mode of interface loading issue: the resemblance of test interface loading to that of the actual manufactured part. What technology needs is a simple adhesion test method that is practical for product development, giving reliable information about the interface integrity. The present paper compares the value of two adhesion tests for microelectronics applications and emphasizes the importance of locus of failure analyses. A realignment of structure reliability modeling is suggested by the usage of effective fundamental adhesion instead of the standard undeterminable fundamental adhesion.     

SAR测雨反演算法MREA的研究

介绍了利用X-SAR的归一化雷达散射截面(NRCS)来反演地表降雨量的算法:改进型回归经验算法(MREA),依据测雨反演算法的基本原理,重点分析了MREA算法的理论依据,对于矩形降雨分布在地表降雨量R=50 mm/h和R=100 mm/h的条件下用MREA算法进行反演,指出了NRCS随x轴坐标不断变化这一导致MREA算...     

Dynamic hydroelastic scaling of self-adaptive composite marine rotors

The objective of this work is to establish dynamic similarity relationships for self-adaptive composite marine rotors. Although scaling laws are well established for rigid propellers and turbines, relative little work has been shown for flexible marine rotors that are designed to interact with the surrounding flow. Considering recent interests in the development of large-scale, energy-efficient composite marine propellers and turbines, it is crucial to understand the scaling relationships to properly design and interpret model-scale studies. Explanations of the similarity requirements are presented, along with scaling factors for the various fluid and structural parameters that control the dynamic interactions between the flexible rotor and the surrounding flow. Finally, numerical results obtained using a fully coupled, three-dimensional, boundary element method–finite element method is shown to demonstrate the validity of theoretical scaling relationships and to investigate scaling effects. The results suggest that for most marine rotors where gravitational forces are negligible compared to other dominant forces and the boundary layer is fully turbulent, it is most practical to conduct model-scale experiments to satisfy Mach number similarity, even though the Mach number will be much less than one for most marine applications.     

Evaluation of parameters affecting modified atmosphere packaging engineering design for pomegranate arils

This study evaluated the effects of passive modified atmosphere packaging design parameters as a function of the amount of product (g), temperature (°C) and time (days) on two pomegranate cultivars. Arils (75, 100 and 125 g) were packed in trays, heat sealed with polylid film and stored at 5, 10 and 15 °C for 14 days, and analysed for physicochemical parameters viz headspace gas composition, weight loss, total soluble solids, titratable acidity, pH, anthocyanin, aerobic‐mesophilic bacterial and fungal load (log CFU g^?1). At the highest temperature and weight, O₂ concentration continuously decreased below the critical limit (2%) after 4 days, while at 5 °C, this lower limit was not reached. Shelf life of arils was limited to 10, 7 and 3 days by fungal growth ≥2 log CFU g^?1 at 5, 10 and 15 °C, respectively. Using unsteady‐state equation, a good agreement was found between simulated and experimental gas composition data.     

Phosphated crosslinked pectin as a potential excipient for specific drug delivery: preparation and physicochemical characterization

Pectin was chemically modified with different amounts of trisodium trimetaphosphate (STMP) in aqueous solution (pH = 12), thereby giving a material with reduced water solubility. The physiochemical characterization of this new material was carried out through Fourier transform infrared and thermogravimetric analyses. Phosphated pectin (Pect‐STMP) together with prebiotic (oligosaccharide) were incorporated into an aqueous dispersion of polymethacrylate (Eudragit^® RS 30 D) in order to obtain free films using a casting process (50 °C) on a Teflon plate. The free films were evaluated using water vapour transmission, average swelling index in simulated gastric fluid (SGF) and simulated intestinal fluid, scanning electron microscopy and a diffusion study with theophylline in buffer solution with and without pectinolytic enzyme. The results suggest that the new material can be used in the coating process for oral solid‐reservoir systems, to prevent the premature release of drugs in SGF (pH = 1.2). Furthermore, the presence of both Pect‐STMP and oligosaccharide favours the specific degradation of the pellicle by the action of the enzymes produced by colonic microflora. The material obtained in this work has the potential to be applied in devices for drug delivery in the colon, making possible modified release of drugs. Nevertheless, subsequent colon‐specific experiments in vivo need to be carried out in order to confirm the possible application of this new material. Copyright © 2009 Society of Chemical Industry     

Evaluation of Fatigue and Rutting Behavior of Asphalt Binder Containing Warm Additive

In this research study, Sasobit as warm additive was used to modify original binder (60/70 penetration grade). The binder fatigue and rutting performance was evaluated through linear amplitude sweep (LAS) and multiple stress creep and recovery test, respectively. Results indicated that 3% Sasobit modified binder has the highest percent recovery value and the lowest J_nr value, but had the highest sensitivity to a sudden increase in the stress level inside the asphalt mixture. The LAS test results demonstrated that the fatigue behavior of asphalt binders modified with 1% Sasobit is the highest one.     

Comparative analysis of mechanical properties of size films

The advent of very high speed shuttleless looms has increased the importance of sizing. Starch has been the most popular and economic size material. Synthetic binders are also being blended with starch to improve weaving loom efficiency. Some synthetic size materials have got restrictions in use mainly because of ecological reasons. In the recent years, many modifications have come up in the starch as a sizing agent. Different modifications give different properties, which can be suited for particular application. In the present study, a comparative analysis of different varieties of natural starch, modified starch and synthetic size materials have been carried out for their cohesion power, adhesion power, abrasion resistance and bending rigidity. Comparison is made between various varieties and also among different blends to see the effect of blending on different mechanical properties of size film. The effect of lubricant on properties of size film is also examined. In general, it is observed that paste characteristics and film properties of synthetic and modified starch are better than the natural starch.     

Separator-type robust stability theorem of sampled-data systems allowing noncausal LPTV scaling

This paper derives a necessary and sufficient condition for robust stability of sampled-data systems, which is stated by using the notion of separators that are dealt with in an operator-theoretic framework. Such operator-theoretic treatment of separators provides a new perspective, which we call noncausal linear periodically time varying scaling and leads to reducing conservativeness in robust stability analysis. A numerical example is given to demonstrate the results.