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91.
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93.
Humic acid (HA) is one of the major components of soil organic matter. It strongly affects the sorption behavior of organic and inorganic contaminants in soils. To obtain a better understanding of the interactions of contaminants with HA, a repeated extraction technique has been applied to a peat soil to obtain HA fractions with varying aliphaticity and aromaticity, which were subsequently correlated to the sorption properties of 2,4,6-trichlorophenol (TCP). HA fractions were extracted repeatedly using an alkaline solution and each HA fraction was separated into two portions with an air-drying or re-suspending (denoted as RSHAs) process. Solid-state (13)C NMR and elemental analysis demonstrated that the aromaticity and polarity of HAs decreased with extractions. Kinetic results indicated that air-dried HAs exhibited two-step first order sorption behavior with a rapid stage followed by a slower stage. The slower sorption is attributed to the diffusion of 2,4,6-TCP in the condensed aromatic domains of HAs. Conversely, sorption of 2,4,6-TCP on RSHAs was extremely rapid and could not be fitted with any kinetic model. For air-dried HAs the sorption capacity (K(oc)) was weakly correlated with the chemical compositions of HAs. However, a positive trend between K(oc) and aromaticity was observed for RSHAs. Compared with the results of air-dried HAs with their counterparts of RSHAs, it is therefore concluded that air-drying may alter the structure of HAs through artificially creating a more condensed domain in HAs. The structural alternation may result in an incorrect interpretation of the relationship between sorption capacity and chemical composition of HAs and a misjudgment of the transport behavior of 2,4,6-TCP in soils and sediments. 相似文献
94.
Gu YY Yu SY Kong AG Hua CY Ding HM Shan YK 《Journal of nanoscience and nanotechnology》2008,8(6):3235-3240
A novel technique was developed to prepare highly pure heteropoly acid (HPA) nanocrystals inside mesoporous SBA-15 by the imprisoned reaction of HPA etherate and water, which was utilized as a main driving force for the transportation of building-blocks. The transmission electron microscopy, X-ray diffraction, FT-IR spectrum and NMR characterizations unambiguously demonstrate that this method allows the highly pure heteropoly acid nanocrystals with intact Keggin-type structure controlled directionally self-assembly within mesopores of silica SBA-15. Such method may open up a new entry to the highly pure multicomponent nanocrystalline particles inside the cavity of the porous materials. 相似文献
95.
An algorithm, based on ordinal optimisation (OO) and sensitive theories, is presented to solve a class of constrained weight least square problems with continuous and discrete variables. the proposed algorithm can cope with an enormous amount of computational complexity problems and has a high probability of obtaining a good enough solution according to the oo theory. this method has some advantages, such as computational efficiency, numerical stability and the superiority of the good enough solution. the proposed algorithm is explicit, compact and easy to program. test results demonstrate that the proposed approach is more computational-efficient than other existing approaches for solving constrained-state estimation problems with continuous and discrete variables on the ieee 30-bus and the ieee 118-bus systems. 相似文献
96.
97.
Disposable electrochemical immunosensor diagnosis device based on nanoparticle probe and immunochromatographic strip 总被引:4,自引:0,他引:4
We describe a disposable electrochemical immunosensor diagnosis device that integrates the immunochromatographic strip technique with an electrochemical immunoassay and exploits quantum dot (QD, CdS@ZnS) as labels for amplifying signal output. The device takes advantage of the speed and low cost of the conventional immunochromatographic strip test and the high sensitivity of the nanoparticle-based electrochemical immunoassay. A sandwich immunoreaction was performed on the immunochromatographic strip, and the captured QD labels in the test zone were determined by highly sensitive stripping voltammetric measurement of the dissolved metallic component (cadmium) with a disposable screen-printed electrode, which is embedded underneath the membrane on the test zone. The new device coupled with a portable electrochemical analyzer shows great promise for in-field and point-of-care quantitative testing of disease-related protein biomarkers. The parameters (e.g., voltammetric measurement of QD labels, antibody immobilization, the loading amount of QD-antibody, and the immunoreaction time) that govern the sensitivity and reproducibility of the device were optimized with IgG model analyte. The voltammetric response of the optimized device is highly linear over the range of 0.1-10 ng mL(-1) IgG, and the limit of detection is estimated to be 30 pg mL(-1) in association with a 7-min immunoreaction time. The detection limit was improved to 10 pg mL(-1) using a 20-min immunoreaction time. The device has been successfully applied for the detection of prostate-specific antigen (PSA) in human serum sample with a detection limit of 20 pg mL(-1). The results were validated by using the commercial PSA enzyme-linked immunosorbent assay kit and showed high consistency. The new disposable electrochemical diagnosis device thus provides a rapid, clinically accurate, and quantitative tool for protein biomarker detection. 相似文献
98.
We demonstrate the development of a simply equipped displacement sensor utilizing spatially dispersive confocal technology. It feeds the amplified spontaneous emission (ASE) of a laser diode to a wavelength-selective feedback structure that corresponds to the position of a measured surface. The displacement sensor has a detecting range of 4 microm and precision of less than 2 nm, as proven by the analysis of the spectral shifts of the multipassed amplified output ASE. As compared with traditional sensors, the displacement sensor presented in our study requires fewer components and has as high precision as complex systems and a higher measurement rate due to the simpler strategy of displacement determination. 相似文献
99.
移动无线传感器网络中基于过渡带思想的贪婪转发策略 总被引:2,自引:0,他引:2
针对移动无线传感器网络采用贪婪转发策略的地理路由协议中使用周期性信标交换所引起的通信暂盲现象,提出了一种基于过渡带思想的贪婪转发策略.其主要思想是在节点通信范围的边缘引入一个半径大小合适的过渡带,转发节点首先剔除过渡带内的邻居节点,然后选择离目的节点最近的且比转发节点离目的节点距离更近的邻居节点作为下一跳节点.仿真结果表明采用该转发策略的贪婪地理路由协议,在小量增加数据传输平均时延的情况下,能够有效地消除通信暂盲现象,大大提高数据传送成功率,具有很好的可靠性. 相似文献
100.
Thedistance transform(DT) is an image computation tool which can be used to extract the information about the shape and the position of the foreground pixels relative to each other. It converts a binary image into a grey-level image, where each pixel has a value corresponding to the distance to the nearest foreground pixel. The time complexity for computing the distance transform is fully dependent on the different distance metrics. Especially, the more exact the distance transform is, the worse execution time reached will be. Nowadays, quite often thousands of images are processed in a limited time. It seems quite impossible for a sequential computer to do such a computation for the distance transform in real time. In order to provide efficient distance transform computation, it is considerably desirable to develop a parallel algorithm for this operation. In this paper, based on the diagonal propagation approach, we first provide anO(N2) time sequential algorithm to compute thechessboard distance transform(CDT) of anN×Nimage, which is a DT using the chessboard distance metrics. Based on the proposed sequential algorithm, the CDT of a 2D binary image array of sizeN×Ncan be computed inO(logN) time on the EREW PRAM model usingO(N2/logN) processors,O(log logN) time on the CRCW PRAM model usingO(N2/log logN) processors, andO(logN) time on the hypercube computer usingO(N2/logN) processors. Following the mapping as proposed by Lee and Horng, the algorithm for the medial axis transform is also efficiently derived. The medial axis transform of a 2D binary image array of sizeN×Ncan be computed inO(logN) time on the EREW PRAM model usingO(N2/logN) processors,O(log logN) time on the CRCW PRAM model usingO(N2/log logN) processors, andO(logN) time on the hypercube computer usingO(N2/logN) processors. The proposed parallel algorithms are composed of a set of prefix operations. In each prefix operation phase, only increase (add-one) operation and minimum operation are employed. So, the algorithms are especially efficient in practical applications. 相似文献