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121.
A method for creating nanoparticles directly from bulk metal by applying ultrasound to the surface in the presence of a two‐part surfactant system is presented. Implosive collapse of cavitation bubbles near the bulk metal surface generates powerful microjets, leading to material ejection. This liberated material is captured and stabilized by a surfactant bilayer in the form of nanoparticles. The method is characterized in detail using gold, but is also demonstrated on other metals and alloys, and is generally applicable. It is shown that nanoparticles can be produced regardless of the bulk metal form factor, and the method is extended to an environmentally important problem, the reclamation of gold from an electronic waste stream.  相似文献   
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123.
We have developed a sensitive, automated, competitive chemiluminescent immunoassay for the detection of 3-phenoxybenzoic acid (3-PBA), a metabolite common to many pyrethroid insecticides. The system uses a competitive hapten-protein conjugate that has been labeled with an acridinium ester as the chemiluminescent probe and secondary antibody-coated paramagnetic particles for the separation. After the immunoassay reagents and samples are combined for the competitive incubation step, a fully automated system is used to load the postincubation mixture into a delivery cuvette, facilitating the subsequent magnetic separation of the immunocomplex and the measurement of chemiluminescent signal for quantification. The immunoassay format described here supports the requirement for high throughput necessary for monitoring large numbers of samples in population-based studies. The optimized immunoassay was more sensitive than the conventional enzyme immunoassay in buffer (IC(50) = 0.1 and 2 microg/L, respectively). The mixed-mode solid-phase extraction used for sample preparation to reduce possible urinary matrix effects allowed the accurate measurement of 3-PBA levels as low as 1 microg/L. The automated chemiluminescent immunoassay described here is sensitive, simple to use, and more rapid than the previously reported standard microplate assay.  相似文献   
124.
Current developments in SELDI affinity technology   总被引:29,自引:0,他引:29  
The overall history and recent advancements in Surface-Enhanced Laser Desorption/Ionization (SELDI) affinity technology is reviewed. A detailed account of SELDI technology, utilizing Immobilized-Metal Affinity surfaces, pseudo-specific chromatographic surfaces, and biospecific interactive surfaces, is presented with particular emphasis placed upon examination of fundamental characteristics as well as specific applications for each. Finally, a detailed review of the specific use of such affinity surfaces in fundamental aspects of clinical, process, and research proteomics activity is presented.  相似文献   
125.
A stable surface-enhanced Raman scattering (SERS) substrate is developed through immobilization of gold sols onto aminated silica beads. The plasmon resonance is established by spacing of gold sols on the bead surface and remains stable over extended periods of time due to the large number of amine groups that provide stable anchoring of gold to the surface. Unlike planar supports, this substrate can be dispersed in a sample, providing high surface area for detection and efficient transport of analytes to its surface. This substrate can be used to detect the binding of a molecule to ligands on the silica surface, which avoids the stability limitations of thiol-bound ligands on gold. Chemical modification of the amine groups on the silica surface with benzoic anhydride could be readily detected in Raman scattering enhanced by the neighboring gold sols, with nearly the same sensitivity as benzylthiol bound directly to the gold surfaces. This result suggests future work involving the immobilization of other ligands through the residual amine groups to the silica, which could be used to selectively attract target analytes to the SERS-active surface.  相似文献   
126.
Flow patterns of dairy wastewater constructed wetlands in a cold climate   总被引:1,自引:0,他引:1  
Conservative tracer experiments, and spatial temperature and dissolved oxygen mapping within four subsurface treatment wetlands employed in this study demonstrated the importance of supplemental aeration and vegetation in reducing preferential flows in cold climate treatment wetlands. Four constructed wetlands, employing horizontal subsurface flow were used to treat dairy wastewater in a 2 x 2 factorial design consisting of two wetland cells with vegetation and two with supplemental aeration. Four tracer studies were conducted between November 2004 and May 2005. Two key observations were made, demonstrating that vegetation and aeration can be utilized in cold regions to prevent clogging and freezing, thereby reducing preferential flow paths which can reduce treatment efficiencies: (1) vegetation contributed to thermal protection and (2) aeration increased temperature and mixing. A comparison of multiple wetland cells with varying flow rates showed that the use of pore volume in tracer response curves was a better indicator of preferential flows than other indicators including volumetric efficiency, hydraulic efficiency and number of continuosly stirred tank reactors (CSTRs). This research helps further establish how constructed wetlands are a viable tool for treating wastewater in cold climates.  相似文献   
127.
Differences in the mesolimbic dopamine (DA) pathway that regulates alcohol preference may also increase sensitivity to the reinforcing effects of other drugs of abuse. In the present study, the curve-shift (rate-frequency) paradigm was used to quantify the interaction of amphetamine with the rewarding effects of lateral hypothalamic brain stimulation reward (BSR) in alcohol-preferring (P) and -nonpreferring (NP) rats. The role of D? and D? DA receptors of the nucleus accumbens (NAcc) in mediating the reward-potentiating effects of amphetamine was also determined. Animals were tested with randomly administered amphetamine (0.25, 0.75, 1.25 mg/kg ip), DA-receptor antagonists (SCH 23390 [2.0 μg, 5.0 μg]; eticlopride [2.0 μg, 5.0 μg]), or a combination of the 2 (SCH 23390 [2.0 μg, 5.0 μg] + 0.75 mg/kg amphetamine; eticlopride [2.0 μg, 5.0 μg] + 0.75 mg/kg amphetamine). Amphetamine produced comparable dose-related leftward shifts in the rate-frequency function for both P and NP rats, with a greater than 60% reduction observed in BSR threshold. On intervening days, baseline threshold was unaltered between tests and similar between rat lines. Unilateral infusion in the NAcc of either the D? or D? receptor antagonist produced rightward shifts in the rate-frequency function of amphetamine, completely reversing-attenuating its reward-enhancing effects. The results demonstrate that amphetamine produces similar threshold-lowering effects in both P and NP rats and that the reward-potentiating effects of amphetamine do not correlate with alcohol preference under the conditions of the present study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
128.
As marketing communications proliferate, the ability to target the right audience for a message is of ever-increasing importance. Audience targeting practices for mass media, both in research and in industry, have tended to emphasize demographics, behavior, and other characteristics of customer groups as the bases for matching communications to audiences. These approaches overlook the opportunity to leverage the nature of advertising content, by automatically matching advertisement content to appropriate media channels and target audience. We model the semantic and sentiment content of advertisements with 103 variables. Based on these variables, a neural network classifier is used to assign advertisements to groups that represent different media channels. In its ability to classify unseen advertisements, the model outperforms the classification result generated by a random model, by 100–300%. This method also enables us to identify and describe divergent advertisement characteristics, by industry.  相似文献   
129.
Requirements Engineering - We report experience in requirements elicitation of domain knowledge from experts in clinical and cognitive neurosciences. The elicitation target was a causal model for...  相似文献   
130.
USB3.0接口设备集合了通信速度为5Gbps的四个额外的数据通道,而且电源总线也有着高达900mA的最大输出电流。这些新的USB3.0规格加上集成芯片几何尺寸的不断缩小,使得预防电气瞬变和过流故障也变得更重要复杂。即使是很小的静电放电(ESD)和短路事故带来的危害也相比更大。寄生电容,低钳位电压和低电阻成为电路保护元件选择中的关键指标。本文网络版地址:http://www.eepw.com.cn/article/145483.htm  相似文献   
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