水性环氧铁红底漆的研制

通过对水性环氧树脂实用性的选择,结合防锈颜料的作用机理,再配以各种助剂,成功地开发了水性环氧铁红底漆。漆膜具有较好的物理性能、耐水性、耐盐水性,施工适用期长达6 h,完全可以满足工业上的应用。漆膜具有优异的耐盐雾性,经1 500 h的盐雾试验后,漆膜无起泡、锈蚀、脱落现象。     

浅议利用雨洪资源解决定西市干旱缺水问题

定西市地处黄土高原,人畜饮水、生活用水和工业用水主要依靠地表水与提引洮河河水,随着经济社会的发展,水资源短缺严重制约着该区域的经济发展。根据定西市的水资源分布特点,提出充分利用汛期雨洪资源,缓解缺水问题。     

基于DEM的乌梁素海东部流域河网信息提取

以乌梁素海东部流域为研究区,基于免费获取的3〃的Shuttle Radar Topography Mission(SRTM)数字高程模型(DEM),利用HEC-GeoHMS模块,确定流域不同汇流累积量阈值的河网密度,通过二者关系曲线,得出东部流域最适汇流累积量阈值为15 km2.实现流域水系提取和子流域划分,继而将其与...     

断续软弱夹层岩石流变力学特性研究

 岩石流变力学特性是岩石力学研究中的重要课题,与岩石工程长期稳定性有着十分密切的联系。基于大型岩土工程分析软件 FLAC（3D）,采用黏弹塑性流变本构模型,模拟了非贯通断续软弱夹层的不同间距、不同长度及倾角等因素条件下岩石的弹塑性变形与流变变形情况。研究分析了各种因素对岩体弹塑性变形与流变变形的影响以及各影响因素之间多重相关性。结果表明：夹层长度、夹层厚度与夹层间距两两之间都有着较强的相关性;岩桥倾角和夹层倾角与其他影响因素的相关性较弱。夹层长度、夹层间距和夹层厚度对岩石弹塑性变形以及流变变形量影响较大,岩桥倾角和夹层倾角对岩石变形影响不显著。     

Validation of the performance of a GMO multiplex screening assay based on microarray detection

A new screening method for the detection and identification of GMO, based on the use of multiplex PCR followed by microarray, has been developed and is presented. The technology is based on the identification of quite ubiquitous GMO genetic target elements first amplified by PCR, followed by direct hybridisation of the amplicons on a predefined microarray (DualChip^® GMO, Eppendorf, Germany). The validation was performed within the framework of a European project (Co-Extra, contract no 007158) and in collaboration with 12 laboratories specialised in GMO detection. The present study reports the strategy and the results of an ISO complying validation of the method carried out through an inter-laboratory study. Sets of blind samples were provided consisting of DNA reference materials covering all the elements detectable by specific probes present on the array. The GMO concentrations varied from 1% down to 0.045%. In addition, a mixture of two GMO events (0.1% RRS diluted in 100% TOPAS19/2) was incorporated in the study to test the robustness of the assay in extreme conditions. Data were processed according to ISO 5725 standard. The method was evaluated with predefined performance criteria with respect to the EC CRL method acceptance criteria. The overall method performance met the acceptance criteria; in particular, the results showed that the method is suitable for the detection of the different target elements at 0.1% concentration of GMO with a 95% accuracy rate. This collaborative trial showed that the method can be considered as fit for the purpose of screening with respect to its intra- and inter-laboratory accuracy. The results demonstrated the validity of combining multiplex PCR with array detection as provided by the DualChip^® GMO (Eppendorf, Germany) for the screening of GMO. The results showed that the technology is robust, practical and suitable as a screening tool.     

Microstructure and mechanical properties of Ti-6Al-4V/Ti-22Al-25Nb joint formed by diffusion bonding

Ti-6Al-4V (wt.%) and Ti-22Al-25Nb (at.%) were joined by diffusion bonding at 950 °C and 15 MPa for 100 min, and the microstructure and mechanical properties of the resulting joints were investigated. The composition of the diffusion layer is B2/discontinuous α/α₂ layer/necklace-shaped β+α′ layer, where the content of any element at a given point mainly depends on the distance of the point from the interface and the phase type at the point. The tensile strength of the joint is 894 MPa, which is almost the same as that of the Ti-22Al-25Nb base alloy. The fracture surfaces on both sides of the joint are composed of two main regions. One region displays a relatively flat surface and fractures along the bonding interface. The other is composed of a moderate number of irregularly-shaped cavities on the Ti-6Al-4V side and many irregularly-shaped bulges on the Ti-22Al-25Nb side. Both regions result from fracture along the boundaries between β+α′ layers and α_p grains or from the transcrystalline fracture of α_p grains.     

Uniqueness and multiplicity criteria for an nth order chemical reaction

New and very strong criteria are presented for a priori prediction of the conditions for which the steady-state lumped parameter model of an nth order chemical reaction (n ≥ 0) in an adiabatic CSTR has either a unique or multiple solutions. The criteria show that the higher the order of the reaction the smaller is the region in the parameters space for which multiplicity can occur.New uniqueness and multiplicity criteria are developed also for an nth order reaction in a porous catalyst using a model, which accounts for intraparticle concentration gradients, while assuming a uniform intraparticle temperature different from the ambient one. The region in the parameters space for which steady state multiplicity can occur for this model is smaller than that for a corresponding lumped model, which ignores the intraparticle concentration gradients.     

超临界CO2萃取新疆紫草萘醌得率的响应曲面分析

本文通过二次回归正交设计得到了超临界二氧化碳萃取新疆紫草得率与温度和压力关系的回归方程并进行得率的响应曲面分析。结果表明：回归方程能较好预测萃取得率；通过响应曲面分析预测在27MPa，35℃条件下，紫草萘醌得率为4．1％～4．6％。     

内壁自动喷涂机控制系统的设计与研制

介绍了一种适合于圆形内表面喷涂的数控喷涂机的控制系统.首先,确定了喷涂工艺方案,接着,进行了控制系统的总体设计,包括元器件的选择、触摸屏的设计、传动部分的控制设计以及喷涂部分的控制设计,最后,确定了控制系统的流程.实际应用证明,该机具有结构紧凑、运动灵活、占用空间少、工作可靠、节能、装卸料容易等优点.     

Mechanism of paper wet strength development by polycarboxylic acids with different molecular weight and glutaraldehyde/poly(vinyl alcohol)

In our previous research, we found that crosslinking paper using poly(carboxylic acid)s with different molecular weight or using the combination of glutaraldehyde and poly(vinyl alcohol) (PVA) significantly improved the wet strength of the paper. In this research, we studied the mechanism of paper wet strength development using crosslinking systems with different molecular weight by measuring scanning electron microscopic (SEM) images, wet strength, folding endurance, wet thickness, water retention, and Z‐direction tensile strength of the treated paper. The paper crosslinked by a high‐molecular weight (MW) poly(carboxylic acid) shows more swelling by water than that crosslinked by a low‐MW polycarboxylic acid in the SEM micrographs even though both treated paper samples have similar wet strength. Thus, the data suggest that high‐MW poly(carboxylic acid)s promote the formation of interfiber crosslinking. Crosslinking paper by glutaraldehyde, a crosslinking agent of small molecular size, improves wet strength and reduces flexibility and swellability of paper because of the formation of intrafiber crosslinking. Combining glutaraldehyde with PVA as a coreactant increases wet strength and also retains flexibility and swellability of the treated paper because of the formation of interfiber crosslinking. The hypothesis that PVA reacts with glutaraldehyde to form a polymeric pentanedialated‐PVA crosslinking system and promotes the formation of interfiber crosslinking on the paper is supported by the data of wet strength, folding endurance, wet thickness, water retention, and Z‐direction tensile strength of the treated paper. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 277–284, 2006