X52管线钢抗硫化氢应力腐蚀实验分析

介绍X52管线钢的抗硫化氢应力腐蚀实验。根据NACE 0284—2003和NACE TM 0177—2005,采用氢致开裂(HIC)实验,硫化物应力腐蚀(SSC-A,SSC-四点弯曲法)实验和电化学测试,检测X52管线钢的抗硫化氢应力腐蚀(SSC)开裂能力。将X52管线钢经过96 h的氢致开裂实验,加载比例分别为最小屈服强度的80%,85%,90%的SSC-A实验和SSC-四点弯曲实验720 h,均未发现裂纹。结果表明,X52管线钢具有较好的抗硫化氢应力腐蚀能力。     

高压离子色谱法快速测定水中7种无机阴离子

目的：建立高压离子色谱法快速测定水中氟离子、亚氯酸根离子、氯离子、硝酸根离子、氯酸根离子、溴离子、硫酸根离子7种无机阴离子含量的方法。方法：选用Dionex Integrion高压离子色谱仪和Ionpac AS19色谱分析柱,KOH淋洗液浓度为20 mmol/L、流速为2.00 mL/min条件下,通过抑制型电导检测器测定水中7种无机阴离子含量。结果：7种无机阴离子在7 min内实现分离,该方法的线性相关系数≥ 0.999,相对标准偏差＜2%,7种阴离子的样品加标回收率为95.3%~105.8%。结论：该方法具有简便快速、准确灵敏、环保高效等优点,适用于水质分析中7种无机阴离子的同时快速测定。     

Prediction model of the buildup of volatile organic compounds on urban roads

A model to predict the buildup of mainly traffic-generated volatile organic compounds or VOCs (toluene, ethylbenzene, ortho-xylene, meta-xylene, and para-xylene) on urban road surfaces is presented. The model required three traffic parameters, namely average daily traffic (ADT), volume to capacity ratio (V/C), and surface texture depth (STD), and two chemical parameters, namely total suspended solid (TSS) and total organic carbon (TOC), as predictor variables. Principal component analysis and two phase factor analysis were performed to characterize the model calibration parameters. Traffic congestion was found to be the underlying cause of traffic-related VOC buildup on urban roads. The model calibration was optimized using orthogonal experimental design. Partial least squares regression was used for model prediction. It was found that a better optimized orthogonal design could be achieved by including the latent factors of the data matrix into the design. The model performed fairly accurately for three different land uses as well as five different particle size fractions. The relative prediction errors were 10-40% for the different size fractions and 28-40% for the different land uses while the coefficients of variation of the predicted intersite VOC concentrations were in the range of 25-45% for the different size fractions. Considering the sizes of the data matrices, these coefficients of variation were within the acceptable interlaboratory range for analytes at ppb concentration levels.     

氢预处理与高压影响下石墨的Raman光谱研究及在金刚石高温高压合成中的意义

氢预处理及高压作用后石墨的Raman光谱的研究表明:酸浸泡及氢等离子体预处理均可以在石墨中造就有利于金刚石成核的-CH3:C-H类金刚石碳区,并使石墨的有序度显著降低;5.4GPa高压作用后,氢预处理石墨的有序度会有所提高,但不会超过常压下未经氢预处理石墨的有序度;高压下石墨向金刚石转变,石墨片层确实有褶曲,但在此之前可能存在一个石墨与氢等造就类金刚石碳区有关的必然环节。     

基于PLC控制的恒压变频调速供水系统设计与仿真

针对城市智能楼宇建筑生活及消防供水系统需求,利用PLC,变频器和PID调节器构建交流双恒压双变频闭环调速控制系统.该系统根据供水系统出口处的水压和流量,利用PLC控制变频/工频及电动机泵组的速度和切换,实现了闭环自动调节恒压变量供水.利用MCGS组态软件对该系统进行模拟调试,运行结果表明:该系统可靠性高、扩展性好,动态响应速度快,启动时压力波动小.     

Influence of Anionic Cosolutes and pH on Nanoscale Zerovalent Iron Longevity: Time Scales and Mechanisms of Reactivity Loss toward 1,1,1,2-Tetrachloroethane and Cr(VI)

Nanoscale zerovalent iron (NZVI) was aged over 30 days in suspension (2 g/L) with different anions (chloride, perchlorate, sulfate, carbonate, nitrate), anion concentrations (5, 25, 100 mN), and pH (7, 8). During aging, suspension samples were reacted periodically with 1,1,1,2-tetrachloroethane (1,1,1,2-TeCA) and Cr(VI) to determine the time scales and primary mode of NZVI reactivity loss. Rate constants for 1,1,1,2-TeCA reduction in Cl(-), SO(4)(2-), and ClO(4)(-) suspensions decreased by 95% over 1 month but were generally equivalent to one another, invariant of concentration and independent of pH. In contrast, longevity toward 1,1,1,2-TeCA depended upon NO(3)(-) and HCO(3)(-) concentration, with complete reactivity loss over 1 and 14 days, respectively, in 25 mN suspensions. X-ray diffraction suggests that reactivity loss toward 1,1,1,2-TeCA in most systems results from Fe(0) conversion into magnetite, whereas iron carbonate hydroxide formation limits reactivity in HCO(3)(-) suspensions. Markedly different trends in Cr(VI) removal capacity (mg Cr/g NZVI) were observed during aging, typically exhibiting greater longevity and a pronounced pH-dependence. Notably, a strong linear correlation exists between Cr(VI) removal capacities and rates of Fe(II) production measured in the absence of Cr(VI). While Fe(0) availability dictates longevity toward 1,1,1,2-TeCA, this correlation suggests surface-associated Fe(II) species are primarily responsible for Cr(VI) reduction.     

Combined effect of high hydrostatic pressure treatment and hydrogen peroxide on Salmonella Enteritidis in liquid whole egg

The effects of high hydrostatic pressure treatment (HHP) of 250, 350, 450 MPa and hydrogen peroxide additions at different concentrations of 0.1, 0.5, 1% in liquid whole egg following high hydrostatic pressure treatment at 250 MPa at 20 °C on Salmonella Enteritidis PT4 in liquid whole egg were investigated. At 20 °C for 5 min treatment, 56.63 and 49.38% injury were determined for the treatment pressures of 250 and 350 MPa, respectively. Injury was not detected and total destruction of Salmonella Enteritidis PT4 was obtained for 5 min treatment at 450 MPa. The obtained results indicated that HHP was a more effective treatment than preheating for the enhancement of the effectiveness of H₂O₂. In order to minimize the adverse effect of HHP on food texture, the HHP treatment of 250 MPa was used throughout this study. Therefore, treating with 0.5% H₂O₂ following 5 min HHP at 250 MPa was determined as an effective way of Salmonella Enteritidis destruction in liquid whole egg. The catalase activity retention was determined as 62.26±0.6% after 3.5 min treatment of LWE at 60 °C. A 5-min treatment at 250 and 450 MPa at 20 °C of LWE resulted in a 78.67±2.1 and 65.01±1.8% retention of catalase activity, respectively.     

瓦楞纸箱柔印的压力控制

最近，我们走访了一些瓦楞纸箱印刷企业，同他们进行了技术交流。发现在操作技术上还存在一些问题，应该引起重视。本文主要论述一下瓦楞纸箱柔印中压力的控制问题。柔性版印刷属于轻压力印刷，因而采取加压措施只会适得其反。把有限的墨量挤到不需要墨的部位，所以说柔印压力过大是产生硬口（野墨）、毛边、糊版等故障的主要原因。如何控制压力，关键在于操作调整，调整实际上就是要控制好印版的压缩变形，印版变形越小。印刷质量就越高。图１是瓦楞纸箱柔印原理示意图。在印刷过程中。有３个压力点（实际上是３条压印带），即墨斗辊与金属…     

Microwave-drying of sliced mushroom. Analysis of temperature control and pressure

The drying of sliced mushroom by microwave energy is studied for different operational conditions related to temperature control position and pressure and their effects on drying kinetics and quality. Thinly sliced mushrooms were dried in a guide cavity by applying microwave energy at 2.45 GHz. The influence on the quality of the dehydrated mushrooms was studied by two different techniques: sorption isotherms (Halsey and B.E.T. equations) and scanning electron microscopy (SEM). Drying kinetics were also analyzed through the determination of diffusivity by applying a mathematical model that takes into account changes in moisture on the product surface during the process. Thus, the results of SEM observations and quality can be linked with diffusivity values in each experiment. As a rule, the operational conditions imposed result in contrary tendencies in quality and drying kinetics. High heat levels usually lead to unfavorable quality results in the dehydrated product if not corrected with a favorable inverse temperature gradient characteristic of microwave heating.Industrial relevanceThe combination of drying and enzyme inactivation of mushrooms browning confers microwave drying a great interest with regard to its industrial application. The results referenced in this paper, concerning the position effect of temperature control and pressure will contribute to the continued development of microwave technology applied to food dehydration.     

Efficient control system for low-concentration inorganic gases from a process vent stream: application of surfactants in spray and packed columns

Control of low-concentration pollutants from a semiconductor process vent stream using a wet-scrubbing technique is a challenging task to meet Taiwan environmental emission standards. An efficient wet-scrubber is designed on a pilot scale and tested to control low concentration acid and base waste-gas emission. The scrubber system consisted of two columns, i.e., a fine spray column [cutoff diameter (based on volume), Dv(50) = 15.63 microm; Sauter mean diameter (SMD) = 7.62 microm], which is especially efficient for NH3 removal as the pH of the spraying liquid is approximately 7 followed by a packed column with a scrubbing liquid pH approximately 9.0 mainly for acids removal. It is observed that use of the surfactants in low concentration about 10(-4) M and 10(-7) M in the spray liquid and in the scrubbing liquid, respectively, remarkably enhances the removal efficiency of the system. A traditional packed column (without the spray column and the surfactant) showed that the removal efficiencies of NH3, HF, and HCl for the inlet concentration range 0.2 to 3 ppm were (n = 5) 22.6+/-3.4%, 43.4+/-5.5%, and 40.4+/-7.4%, respectively. The overall efficiencies of the proposed system (the spray column and the packed column) in the presence of the surfactant in the spray liquid and in the scrubbing liquid forthese three species were found to increase significantly (n = 5) from 60.3+/-3.6 to 82.8+/-6.8%, 59.1+/-2.7 to 83.4+/-4.2%, and 56.2+/-7.3 to 81.0+/-6.7%, respectively. In this work, development of charge on the gas-liquid interface due to the surfactants has been measured and discussed. It is concluded that the presence of charge on the gas-liquid interface is the responsible factor for enhancement of the removal efficiency (mass-transfer in liquid phase). The effects of the type of surfactants, their chain length, concentration in liquid, etc. on the removal efficiency are discussed. Since the pilot tests were performed under the operating conditions similar to most of the wet-scrubbers operated in semiconductors manufacturing facilities for inorganic pollutants, this study can be applied to modify the existing wet-scrubbers to enhance the removal efficiencies, especially for low-concentration pollutants.     

服装款式特征对人体局部传热性能的影响

为研究不同服装款式的衣下间隙分布特征,及其对人体局部区段向外环境热量传递的影响,采用同种纺织面料设计制作了3 款号型相同但款式不同的实验衬衫（H 廓型、A 廓型、X 廓型）,应用红外热像仪对裸体与服装外表面温度分布进行无干扰高精度探测,并将人体划分为不同的部位区段,量化人体各区段的局部衣表温度与皮 肤温度的差值,以此表征服装的局部传热性能。结果表明：人体局部的体型特征与服装款式共同影响服装局部传热性能,一方面,服装局部传热性能存在区段间差异;另一方面,款式A 的隔热性能最优,且在腹部、腰部、下背、前臀、后臀部位,其衣表温差显著高于其他2 款服装,而在上胸、下胸及上背区域,由于人体骨骼肌肉的隆起,3款服装间的局部传热性能未发现显著性差异。     

Phase transition in foods: effect of pressure and methods to assess or control phase transition

Food systems can be defined as heterogeneous and complex systems in which multiple interactions take place. In addition, food systems are unstable due to chemical and physical reactions. Food components (proteins carbohydrates, lipids, water …) might undergo phase transitions due to a pressure or temperature change. The effect of temperature and pressure on phase transitions of selected food components is discussed with emphasis on high pressure processing of food systems. The possibilities of Nuclear Magnetic Resonance and Magnetic Resonance Imaging in assessing phase transitions in food are highlighted.     

Redox control and hydrogen production in sediment caps using carbon cloth electrodes

Sediment caps that degrade contaminants can improve their ability to contain contaminants relative to sand and sorbent-amended caps, but few methods to enhance contaminant degradation in sediment caps are available. The objective of this study was to determine if, carbon electrodes emplaced within a sediment cap at poised potential could create a redox gradient and provide electron donor for the potential degradation of contaminants. In a simulated sediment cap overlying sediment from the Anacostia River (Washington, DC), electrochemically induced redox gradients were developed within 3 days and maintained over the period of the test (～100 days). Hydrogen and oxygen were produced by water electrolysis at the electrode surfaces and may serve as electron donor and acceptor for contaminant degradation. Electrochemical and geochemical factors that may influence hydrogen production were studied. Hydrogen production displayed zero order kinetics with ～75% Coulombic efficiency. Rates were proportional to the applied potential between 2.5 and 5 V and not greatly affected by pH. Hydrogen production was promoted by increasing ionic strength and in the presence of natural organic matter. Carbon electrode-stimulated degradation of tetrachlorobenzene in a batch reactor was dependent on applied voltage and production of hydrogen to a concentration above the threshold for biological dechlorination. These findings suggest that electrochemical reactive capping can potentially be used to create "reactive" sediments caps capable of promoting chemical or biological transformations of contaminants within the cap.     

针织毛衫的风格及其整理

文章综述了针织毛衫的风格特点、影响因素、后整理技术及评价方法.较为详尽地讨论了针织毛衫风格整理剂的物理、化学结构及整理工艺对产品风格手感及色泽的影响,对生产实践具有一定的现实指导意义.此外,还在纤维特性、整理剂的选择和后整理工艺等方面就针织毛衫风格整理中存在的误区及技术要点进行了探讨.     

Significance of kinetics for sorption on inorganic colloids: modeling and experiment interpretation issues

A two-site kinetic model for solute sorption on inorganic colloids is developed. The model quantifies linear first-order sorption on two types of sites ("fast" and "slow") characterized by two pairs of rates (forward and reverse). We use the model to explore data requirements for long-term predictive calculations of colloid-facilitated transport and to evaluate laboratory kinetic sorption data of Lu et al.. Five batch sorption data sets are considered with plutonium as the tracer and montmorillonite, hematite, silica, and smectite as colloids. Using asymptotic results applicable on the time scale of limited duration experiments, a robust estimation procedure is developed for the fast-site partitioning coefficient K(C) and the slow forward rate alpha. The estimated range of K(C) is 1.1-76 L/g, and the range for alpha is 0.0017-0.02 1/h. The fast reverse rate k(r) is estimated in the range 0.012-0.1 1/h. Comparison of one-site and two-site sorption interpretations reveals the difficulty in discriminating between the two models for montmorillonite and to a lesser extent for hematite. For silica and smectite, the two-site model clearly provides a better representation of the data as compared with a single site model. Kinetic data for silica are available for different colloid concentrations (0.2 g/L and 1 g/L). For the range of experimental conditions considered, alpha appears to be independent of colloid concentration.     

The influence of malt and wort processing on spirit character: the lost styles of Scotch malt whisky

Over the last 50 years there has been considerable analytical research on the malt parameters which govern the flavour and aroma, i.e. the ‘character’, of Scotch malt whisky. This has led to a standard format, the Flavour Wheel, to describe the attributes of any malt spirit and to relate them to a common group of malt parameters. What has not been well documented in the same period are the changes in malt processing technology which have led to a gradual but significant change in the concentrations of reference compounds used in the Flavour Wheel relating to sulphury, nutty/burnt/smoky, peaty and fruity/estery characters. This review covers the most significant of these changes, which have become common practice across the industry, and specifically demonstrates how different malting barley varieties, malt kilning and peating, wort recovery, yeast management, and wash still heating have all contributed to the loss of some styles of malt whisky. © 2019 The Institute of Brewing & Distilling     

工字轮收线机液压站控制方式的改进

工字轮收线机液压站是与钢丝粗拉机配套的Φ1250工字轮收线机的辅助设备,原控制方式使液压站电机连续工作,液压系统一直处在较高的温度和压力状态,容易造成油路泄漏。通过对液压站的工况分析,采用间歇的手动控制与压力自动控制相结合的方式,不仅提高了液压站工作的可靠性,还能每年节约电能约3万kW.h。给出改进前后的控制原理图,并对原理进行说明。     

稻米中总砷及无机砷含量的测定与分析

采用氢化物原子荧光光度法测定13份稻米样品中的总砷和无机砷含量,结果表明：所测稻米样品中均检出总砷与无机砷,总砷含量范围为0.06~0.20 mg/kg,无机砷含量范围为0.039~0.150 mg/kg,无机砷占总砷的含量为50.0%~93.1%,无机砷含量在国家限量卫生标准以内;未冲洗大米样品中总砷含量仅为糙米的72.7%~90.0%,无机砷含量为糙米的62.7%~87.7%;多次冲洗的大米样品中总砷含量仅为未冲洗大米的75.0%~91.7%,无机砷含量为83.0%~93.6%。提高加工精度和用水淘洗均能在一定程度上降低总砷与无机砷的含量,减轻人们食用后对身体的危害。