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排序方式: 共有1600条查询结果,搜索用时 10 毫秒
121.
The CLAS forward electromagnetic calorimeter 总被引:1,自引:0,他引:1
M. Amarian G. Asryan K. Beard W. Brooks V. Burkert T. Carstens A. Coleman R. Demirchyan Yu. Efremenko H. Egiyan K. Egiyan H. Funsten V. Gavrilov K. Giovanetti R. M. Marshall B. Mecking R. C. Minehart H. Mkrtchan M. Ohandjanyan Yu. Sharabian L. C. Smith S. Stepanyan W. A. Stephens T. Y. Tung C. Zorn 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2001,460(2-3):239-265
The CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab utilizes six iron-free superconducting coils to provide an approximately toroidal magnetic field. The six sectors are instrumented individually to form six independent spectrometers. The forward region (8°<θ<45°) of each sector is equipped with a lead–scintillator electromagnetic sampling calorimeter (EC), 16 radiation lengths thick, using a novel triangular geometry with stereo readout. With its good energy and position resolution, the EC is used to provide the primary electron trigger for CLAS. It is also used to reject pions, reconstruct π° and η decays and detect neutrons. This paper treats the design, construction and performance of the calorimeter. 相似文献
122.
123.
Case Study: New Zealand Bridge Scour Experiences 总被引:1,自引:0,他引:1
Details of three case studies of scour damage for New Zealand bridges are presented. These cases cover ranges of bed materials, flood magnitudes, and river morphologies, and illustrate a range of scour processes occurring at bridge foundations. The case study details facilitate evaluation of proposed bridge scour calculation methodologies. Such a proposed methodology for the assessment of scour depths at a bridge site is illustrated for the presented case studies. The resulting scour predictions highlight the value of a judicious use of the proposed methodology, the effect of sediment supply and transport balance considerations for engineering projects, aspects of river morphology to be considered in bridge foundation design, and that the combination of various components of scour needs to be considered when assessing bridge scour. 相似文献
124.
Cover Picture: Discovery of MK‐8970: An Acetal Carbonate Prodrug of Raltegravir with Enhanced Colonic Absorption (ChemMedChem 2/2015) 下载免费PDF全文
Dr. Abbas M. Walji Dr. Rosa I. Sanchez Dr. Sophie‐Dorothee Clas Dr. Rebecca Nofsinger Dr. Manuel de Lera Ruiz Dr. Jing Li Dr. Amrithraj Bennet Christopher John Dr. David Jonathan Bennett Dr. John M. Sanders Christina N. Di Marco Somang Hope Kim Dr. Jaume Balsells Scott S. Ceglia Dr. Qun Dang Kimberly Manser Becky Nissley Dr. John S. Wai Dr. Michael Hafey Junying Wang Gene Chessen Dr. Allen Templeton Dr. John Higgins Dr. Ronald Smith Dr. Yunhui Wu Dr. Jay Grobler Dr. Paul J. Coleman 《ChemMedChem》2015,10(2):213-213
125.
126.
Mechanisms underlying the effects of membrane fouling on the nanofiltration of trace organic contaminants 总被引:3,自引:0,他引:3
The influence of membrane fouling on the retention of four trace organic contaminants - namely sulfamethoxazole, ibuprofen, carbamazepine, and triclosan - by nanofiltration membranes was investigated in this study. Humic acid, alginate, bovine serum albumin, and silica colloids were selected as model foulants to simulate various organic fractions and colloidal matter that are found in secondary treated effluent and surface water. The effects of membrane fouling on the separation process was delineated by comparing retention values of clean and fouled membranes and relate them to the membrane properties (under both clean and fouled conditions) as well as physicochemical characteristics of the trace organic contaminants. Membrane fouling was dependent on the physicochemical properties of the model foulants. Initial foulant-membrane interaction could probably be a major factor governing the process of membrane fouling particularly by the organic foulants. Such membrane-foulant interaction was also a dominating factor governing the effects of membrane fouling on the membrane separation efficacy. In good agreement with our previous study (Nghiem and Hawkes, 2007 [1]), the effects of fouling on retention were found to be membrane pore size dependent. In addition, results reported here suggest that these effects could also be foulant dependent. It was probable that the influence of membrane fouling on trace organic retention could be governed by four distinctive mechanisms: modification of the membrane charge surface, pore blocking, cake enhanced concentration polarisation, and modification of the membrane hydrophobicity. The presence of the fouling layer could affect the retention behavior of charged solutes by altering the membrane surface charge density. While the effect of surface charge modification was clear for inorganic salts, it was less obvious for the negatively charged pharmaceutical species (sulfamethoxazole and ibuprofen) examined in this investigation, possibly due to the interference of the pore blocking mechanism. Evidence of the cake enhanced concentration polarisation effect was quite clear, particularly under colloidal fouling conditions. In addition, organic fouling could also interfere with the solute-membrane interaction, and therefore, exerted considerable influence on the separation process of the hydrophobic trace organic contaminant triclosan. 相似文献
127.
Hydrolysis of an organophosphate ester by manganese dioxide 总被引:1,自引:0,他引:1
Amorphous manganese dioxide facilitates the hydrolysis of p-nitrophenyl phosphate to p-nitrophenol and orthophosphate despite insignificant adsorption of p-nitrophenyl phosphate or p-nitrophenol to the manganese dioxide. At pH 8, the orthophosphate product is released into solution; at pH 4 and pH 6, some remains adsorbed. The rate of hydrolysis is an order of magnitude more rapid than the same reaction facilitated by iron oxides. Because manganese dioxides are ubiquitous components of soils and sediments, this suggests the possibility of significant abiotic pathways for the formation of bioavailable orthophosphate from phosphate ester precursors. 相似文献
128.
Renate C. Smallegange Yu Tong Qiu Gabriella Bukovinszkiné-Kiss Joop J. A. Van Loon Willem Takken 《Journal of chemical ecology》2009,35(8):933-943
The role of aliphatic carboxylic acids in host-seeking response of the malaria mosquito Anopheles gambiae sensu stricto was examined both in a dual-choice olfactometer and with indoor traps. A basic attractive blend of ammonia + lactic acid
served as internal standard odor. Single carboxylic acids were tested in a tripartite blend with ammonia + lactic acid. Four
different airflow stream rates (0.5, 5, 50, and 100 ml/min) carrying the compounds were tested for their effect on trap entry
response in the olfactometer. In the olfactometer, propanoic acid, butanoic acid, 3-methylbutanoic acid, pentanoic acid, heptanoic
acid, octanoic acid, and tetradecanoic acid increased attraction relative to the basic blend. While several carboxylic acids
were attractive only at one or two flow rates, tetradecanoic acid was attractive at all flow rates tested. Heptanoic acid
was attractive at the lowest flow rate (0.5 ml/min), but repellent at 5 and 50 ml/min. Mixing the air stream laden with these
7 carboxylic acids together with the headspace of the basic blend increased attraction in two quantitative compositions. Subtraction
of single acids from the most attractive blend revealed that 3-methylbutanoic acid had a negative effect on trap entry response.
In the absence of tetradecanoic acid, the blend was repellent. In assays with MM-X traps, both a blend of 7 carboxylic acids
+ ammonia + lactic acid (all applied from low density polyethylene-sachets) and a simple blend of ammonia + lactic acid +
tetradecanoic acid were attractive. The results show that carboxylic acids play an essential role in the host-seeking behavior
of An. gambiae, and that the contribution to blend attractiveness depends on the specific compound studied. 相似文献
129.
Carlo Arcelli Nadia Brancati Maria Frucci Giuliana Ramella Gabriella Sanniti di Baja 《Signal processing》2011,91(1):61-71
We present an interpolation algorithm for adaptive color image zooming. The algorithm produces the magnified image in one scan of the input image, and is fully automatic since does not involve any a priori fixed threshold. Given any integer zooming factor n, each pixel of the input image generates an n×n block of pixels in the zoomed image. For the currently visited pixel of the input image, the pixels of its associated block are first assigned tentative values, which are then adaptively updated before building the next block. The method is suggested for RGB images, but can equally be employed in other color spaces. Peak signal to noise ratio (PSNR) and Structural SIMilarity (SSIM) are used to evaluate the performance of the algorithm. 相似文献
130.
Isolation of red wine components with anti-adhesion and anti-biofilm activity against Streptococcus mutans 总被引:1,自引:0,他引:1
Maria Daglia Monica Stauder Adele Papetti Caterina Signoretto Giovanni Giusto Pietro Canepari Carla Pruzzo Gabriella Gazzani 《Food chemistry》2010
Red wine is a widely consumed beverage with multiple beneficial effects on human health. In the present paper, the anticaries properties of red wine were studied in vitro and ex vivo. Our in vitro findings shows that dealcoholised red wine, besides exerting antibacterial activity, strongly interferes with Streptococcus mutans adhesion to saliva-coated hydroxyapatite (sHA) beads, promotes its detachment from sHA, and powerfully inhibits in vitro biofilm formation. The main components responsible for such activities were found to be proanthocyanidins. The ability of red wine to inhibit ex vivoS. mutans biofilm formation on the occlusal surface of natural human teeth also was demonstrated. 相似文献