Reduction of Escherichia coli O157:H7 and Salmonella Typhimurium DT 104 on fresh produce using an automated washer with near neutral electrolyzed (NEO) water and ultrasound

Automated produce washers can be a useful processing aid when treating fresh produce contaminated with pathogens. The use of near neutral pH electrolyzed (NEO) water as a wash or sanitizing solution has been shown to lead to significant reductions of Escherichia coli O157:H7 and Salmonella on fresh produce. To further enhance reported pathogen reductions, the effects of a combined NEO water (155 mg/L free chlorine, pH 6.5) and ultrasound wash protocol on lettuce and tomatoes inoculated with E. coli O157:H7 and S. Typhimurium DT 104 were studied. The effects of the pH of NEO water and washer agitation on pathogen reductions were also assessed. Inoculated tomatoes and lettuce leaves were treated with either chilled deionized water or NEO water, with or without 20 kHz ultrasound (130 W and 210 W). Tomatoes were treated for 1, 3 and 5 min while lettuce was treated for 5, 10 and 15 min. Ultrasound significantly increased the oxidation-reduction potential (ORP) of NEO water (p < 0.05) but did not affect the pH and free chlorine concentration (p > 0.05). Increased washing time and higher ultrasonic power led to significantly greater reductions of both pathogens on produce items (p < 0.05). NEO water combined with 210 W ultrasonication for 15 min led to 4.4 and 4.3 log reductions of E. coli O157:H7 and S. Typhimurium on lettuce, respectively, while 210 W ultrasound for 5 min completely inactivated both pathogens on tomatoes. Both pathogens were completely inactivated in NEO water solutions, suggesting that its use presents little chance of cross-contamination.     

Experimental and Calculational Studies of the Interactions of BF3 with Fluoroethers

BF₃ was co-condensed with (C₂H₅)₂O, (CF₃CH₂)₂O, and (C₂F₅)₂O in excess argon at 15 K. Infrared spectra of the matrices showed a definite Lewis acid-base interaction between BF₃ and diethyl ether; a weak but definite interaction with bis(2,2,2,-trifluorodiethyl)ether, and no observable interaction with perfluorodiethyl ether. Molecular orbital (MO) calculations complemented the experimental observations by revealing that fluorine atoms on the ethers decreased electron localization about the oxygen atom. Thus, the experimental data and MO calculations indicated a clear trend between strength of interaction with BF₃ and the degree of ether F substitution. The implications of the results for commercial perfluoro ether lubricant/metal oxide surface interactions are discussed.     

In Situ Confocal Raman Mapping Study of a Single Ti-Assisted ZnO Nanowire

In this work, we succeeded in preparing in-plane zinc oxide nanowires using a Ti-grid assisted by the chemical vapor deposition method. Optical spatial mapping of the Confocal Raman spectra was used to investigate the phonon and geometric properties of a single ZnO nanowire. The local optical results reveal a red shift in the non-polar E₂ high frequency mode and width broadening along the growth direction, reflecting quantum-confinement in the radial direction.     

聚氨酯中游离—NCO 分析的研究

本文介绍了在醋酸酸性条件下,以 P-N,N-二甲氨基苯甲醛(DMAB)为显色剂,N,N-二甲基甲酰胺(DMF)为溶剂,用分光光度法测定聚氨酯中残留游离-NCO 基的方法。大量试样的测定结果表明,当-NCO在10~1～10~3ppm 范围内,该方法的相对标准偏差在5%左右,分析准确度和精密度得到满意的结果。     

OFDMA无线宽带接入系统简介及性能仿真分析

为了提高在非可视环境下物理信道的传输质量，克服城市无线信道复杂环境中存在的多径和频率选择性衰落问题，文中介绍了基于OFDM调制的OFDMA宽带多址无线接入技术及OFDMA调制特点，分析了BWA的外部环境、容量和所需解决的问题，以及提高非可视环境下服务质量的策略。802．16协议支持两种OFDM调制系统，一种为简单的OFDM系统，另一种为OFDMA系统。文中重点介绍和分析了OFDMA调制系统的性能，并对其在非视距环境下的应用进行了分析和仿真。     

新型煤气化燃烧集成制氢系统的热力学研究

对于以CaO为CO2接受体的无氧气化法为基础的新型煤气化燃烧集成制氢系统进行了化学热力学分析，以化学热力学平衡为基础研究了温度、压力、煤种、H2O／C比对制氢过程的影响。计算结果表明CaO的加入在一定条件下可以大大提高H2产量，气化过程的温度过高会引起CaCO3的重新分解，而温度过低则降低H2产量，合适的温度为850℃左右，合适的压力范围为2-3MPa。以纯碳为原料、气化炉中碳转化率为69％时，半焦燃烧的热量可以满足CaCO3的分解。当H2O／C在3．0-3．5之间时，气化效率达到79％左右，制氢效率为65％左右，产品气中H2含量为85％左右。与烟煤、褐煤相比，无烟煤为原料时产品气中H2含量最高，接近于以纯碳为原料的工况，而褐煤由于挥发份中CH4的含量多导致H2含量降低。     

近红外光谱检测技术在仓储害虫识别中的应用

简要介绍了近红外光谱检测技术的发展过程及在仓储害虫识别应用中的基本原理,通过对近红外光谱检测技术在国内外仓储害虫识别中的发展状况的分析,提出了在仓储害虫识别中采用近红外光谱检测技术与图像处理识别技术结合的研究新思路。     

用于回波抵消的最大长度序列相关近端语音检测算法研究

回波抵消是语音通信系统中不可缺少的一个重要组成部分。大部分回波抵消技术都是基于自适应LMS算法的。在实际应用中，近端语音检测的准确性会在很大程度上影响自适应LMS算法在双向通信环境下回波抵消的效果。本文提出了一种基于最大长度序列相关算法的近端语音检测算法。这种近端语音检测算法和自适应LMS算法相结合，得到的回波抵消算法在模拟双向通信环境下的回波抵消效果比自适应LMS算法高约8db。     

Accelerated fluid bed drying using NIR monitoring and phenomenological modeling

A “fast-drying” method to accelerate the fluid bed drying process is presented. It relies on concepts of heat and mass transfer with real-time near-infrared (NIR) monitoring of moisture. Triplicate trials show that fast drying can reduce granulation drying time by half over single-temperature cycles. The product is equivalent in every way tested to material made using a conventional cycle even though the inlet temperature throughout the constant-rate stage was higher than the melting point of the compound. Tablets made from the fast-dried granulation exhibit equivalent physical characteristics to tablets made from granulations dried at a single, lower temperature.