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排序方式: 共有888条查询结果,搜索用时 15 毫秒
881.
The total and dissolved concentration of cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel and zinc at various points in a conventional activated sludge treatment plant have been measured. The analysis of raw sewage samples collected hourly over a 3-day period showed that metal input to the sewage treatment plant was not a continuous process but consisted of slugs of metal lasting for a discrete time. The efficiency of heavy metal removal by this model treatment plant was determined by monitoring the influent and effluent metal levels over a 4-week period. 相似文献
882.
The paper deals with the failure mechanisms and behavior of composite steel-concrete beams prestressed with external tendons and subjected to positive bending. Experimental tests were carried out on beams with straight and draped tendons as well as on a non-prestressed beam. Six simply supported beams subjected to a positive static bending moment were tested up to failure. The influence of shear connection flexibility was taken into account and slip was measured along the beam axis. Concurrently, push-out specimens were made and tested to determine shear force vs. slip curves. It was found that at the same eccentricity of tendons (draped or straight without saddle points) the tendon shape has no significant effect on the behavior and ultimate resistance of composite steel-concrete beams. It is also shown that steel-concrete bond cohesion can significantly influence the behavior of the shear connection in composite beams. This influence is comparable with the design shear resistance of a single stud connector. 相似文献
883.
Mendoza E Orozco J Jiménez-Jorquera C González-Guerrero AB Calle A Lechuga LM Fernández-Sánchez C 《Nanotechnology》2008,19(7):075102
In this work we present the fabrication and characterization of immunosensors based on polystyrene (PS)-multiwalled carbon nanotube (MWCNT) composites. The electrochemical properties of the sensors have been investigated and show that the surface area is increased upon addition of the MWCNT-PS layer. Furthermore, a plasma activation process is used to partially remove the PS and expose the MWCNTs. This results in a huge increase in the electrochemical area and opens up the possibility of binding biomolecules to the MWCNT wall. The MWCNTs have been functionalized covalently with a model antibody (rabbit IgG). The biosensors have been tested using amperometric techniques and show detection limits comparable to standard techniques such as ELISA. 相似文献
884.
Abriola LM Drummond CD Hahn EJ Hayes KF Kibbey TC Lemke LD Pennell KD Petrovskis EA Ramsburg CA Rathfelder KM 《Environmental science & technology》2005,39(6):1778-1790
A pilot-scale demonstration of surfactant-enhanced aquifer remediation (SEAR) was conducted to recover dense nonaqueous phase liquid (DNAPL) tetrachloroethene (PCE) from a sandy glacial outwash aquifer underlying a former dry cleaning facility at the Bachman Road site in Oscoda, MI. Part one of this two-part paper describes site characterization efforts and a comprehensive approach to SEAR test design, effectively integrating laboratory and modeling studies. Aquifer coring and drive point sampling suggested the presence of PCE-DNAPL in a zone beneath an occupied building. A narrow PCE plume emanating from the vicinity of this building discharges into Lake Huron. The shallow unconfined aquifer, characterized by relatively homogeneous fine-medium sand deposits, an underlying clay layer, and the absence of significant PCE transformation products, was judged suitable for the demonstration of SEAR. Tween 80 was selected for application based upon its favorable solubilization performance in batch and two-dimensional sand tank treatability studies, biodegradation potential, and regulatory acceptance. Three-dimensional flow and transport models were employed to develop a robust design for surfactant delivery and recovery. Physical and fiscal constraints led to an unusual hydraulic design, in which surfactant was flushed across the regional groundwater gradient, facilitating the delivery of concentrations of Tween 80 exceeding 1% (wt) throughout the treatment zone. The potential influence of small-scale heterogeneity on PCE-DNAPL distribution and SEAR performance was assessed through numerical simulations incorporating geostatistical permeability fields based upon available core data. For the examined conditions simulated PCE recoveries ranged from 94to 99%. The effluent treatment system design consisted of low-profile air strippers coupled with carbon adsorption to trap off-gas PCE and discharge of treated aqueous effluent to a local wastewater treatment plant. The systematic and comprehensive design methodology described herein may serve as a template for application at other DNAPL sites. 相似文献
885.
Rastislav Monosik Miroslav Stredansky Jan Tkac Ernest Sturdik 《Food Analytical Methods》2012,5(1):40-53
The importance of analyses of different parameters in food products and monitoring of a production process requires quick
and reliable analytical methods and devices. For this purpose, biosensors can be a suitable option, whereas most of the current
quality control techniques are time consuming, expensive, and unpractical. In this paper, we describe biosensors developed
for analysis of different components present in food samples, namely, glucose, fructose, sucrose, lactose, lactic, malic,
acetic, ascorbic, citric and amino acids, ethanol, glycerol, and triglyceride. Biosensors showed desirable sensitivity, selectivity,
and response time required for various applications. They are often designed to avoid interference from components present
in a complex sample to be analyzed. 相似文献
886.
Martinell M Salvatella X Fernández-Carneado J Gordo S Feliz M Menéndez M Giralt E 《Chembiochem : a European journal of chemical biology》2006,7(7):1105-1113
The applied interaction of synthetic molecules with defined regions of protein surfaces is an emerging strategy for the modulation of protein activity and/or stability. In spite of recent advances, the design of these molecules is not trivial. Among the most challenging aspects in designing these compounds is that they must compete with water molecules for interaction with polar patches of protein surfaces. Herein is reported the preparation of an arginine-rich peptide that interacts in aqueous solution with a very hydrophilic patch at the surface of the tetramerization domain of the tumor suppressor protein p53. The interaction has been studied by several complementary techniques. By using this peptide as a template, a library of peptides has been prepared and evaluated in order to examine the different factors that contribute to the recognition event. The conclusions extracted from this work could be useful for the design of ligands directed at highly hydrophilic protein surface patches. 相似文献
887.
Yuqi Guo Rodney Chua Yingqian Chen Yi Cai Ernest Jun Jie Tang J. J. Nicholas Lim Thu Ha Tran Vivek Verma Ming Wah Wong Madhavi Srinivasan 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(29):2207133
Rechargeable aqueous Zn/S batteries exhibit high capacity and energy density. However, the long-term battery performance is bottlenecked by the sulfur side reactions and serious Zn anode dendritic growth in the aqueous electrolyte medium. This work addresses the problem of sulfur side reactions and zinc dendrite growth simultaneously by developing a unique hybrid aqueous electrolyte using ethylene glycol as a co-solvent. The designed hybrid electrolyte enables the fabricated Zn/S battery to deliver an unprecedented capacity of 1435 mAh g−1 and an excellent energy density of 730 Wh kg−1 at 0.1 Ag−1. In addition, the battery exhibits capacity retention of 70% after 250 cycles even at 3 Ag−1. Moreover, the cathode charge–discharge mechanism studies demonstrate a multi-step conversion reaction. During discharge, the elemental sulfur is sequentially reduced by Zn to S2− (, forming ZnS. On charging, the ZnS and short-chain polysulfides will oxidize back to elemental sulfur. This electrolyte design strategy and unique multi-step electrochemistry of the Zn/S system provide a new pathway in tackling both key issues of Zn dendritic growth and sulfur side reactions, and also in designing better Zn/S batteries in the future. 相似文献
888.
Historically, the best lubrication performance has been achieved by the use of synthetic fluids, such as polyalphaolefins or esters. Advanced commercial processing techniques for producing base oils through significant molecular change are now available. In many applications, automotive and industrial products formulated with these high‐quality API Group III speciality base fluids can achieve the same good performance as that from traditional synthetic fluids. This paper represents continued work to understand and demonstrate features of very high viscosity index (VHVI) speciality base fluids. Ultimately, the performance of a finished fluid is the key market requirement. Actual field performance can vary dramatically, even among polyalphaolefin‐based formulations. Several examples are given to show that equivalent high‐level synthetic performance can be delivered through a synergistic balance of VHVI speciality base fluids and additive chemistry. 相似文献