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71.
Farfaletti A Astorga C Martini G Manfredi U Mueller A Rey M De Santi G Krasenbrink A Larsen BR 《Environmental science & technology》2005,39(17):6792-6799
One of the major technological challenges for the transport sector is to cut emissions of particulate matter (PM) and nitrogen oxides (NOx) simultaneously from diesel vehicles to meet future emission standards and to reduce their contribution to the pollution of ambient air. Installation of particle filters in all existing diesel vehicles (for new vehicles, the feasibility is proven) is an efficient but expensive and complicated solution; thus other short-term alternatives have been proposed. It is well known that water/diesel (W/ D) emulsions with up to 20% water can reduce PM and NOx emissions in heavy-duty (HD) engines. The amount of water that can be used in emulsions for the technically more susceptible light-duty (LD) vehicles is much lower, due to risks of impairing engine performance and durability. The present study investigates the potential emission reductions of an experimental 6% W/D emulsion with EURO-3 LD diesel vehicles in comparison to a commercial 12% W/D emulsion with a EURO-3 HD engine and to a Cerium-based combustion improver additive. For PM, the emulsions reduced the emissions with -32% for LD vehicles (mass/km) and -59% for the HD engine (mass/ kWh). However, NOx emissions remained unchanged, and emissions of other pollutants were actually increased forthe LD vehicles with +26% for hydrocarbons (HC), +18% for CO, and +25% for PM-associated benzo[a]pyrene toxicity equivalents (TEQ). In contrast, CO (-32%), TEQ (-14%), and NOx (-6%) were reduced by the emulsion for the HD engine, and only hydrocarbons were slightly increased (+16%). Whereas the Cerium-based additive was inefficient in the HD engine for all emissions except for TEQ (-39%), it markedly reduced all emissions for the LD vehicles (PM -13%, CO -18%, HC -26%, TEQ -25%) except for NOx, which remained unchanged. The presented data indicate a strong potential for reductions in PM emissions from current diesel engines by optimizing the fuel composition. 相似文献
72.
Gloria A. Smart Marjorie Warrington William H. Evans 《Journal of the science of food and agriculture》1981,32(2):129-133
Preliminary experiments have been carried out to determine the uptake of lead from both hard and soft waters used in the preparation of food and beverages. Lead concentrations in water for the range of 0.05-0.5 mg litre?1 were used to prepare composite groups representing root vegetables, other vegetables and beverages whose composition reflected per capita consumption of these foods in the UK. The uptake of lead from water was highest for the composite group of other vegetables which comprises 70% by weight of green vegetables. For each of the composite groups and the particular water samples used there was little relative difference in uptake whether foods were prepared in hard or soft water. Calculations of the contribution made by lead in water used for preparation of foods and beverages to the total dietary lead intake indicates that at levels of lead of 0.02 mg litre?1, the contribution is about 10% but this can rise to about 40% as lead levels in the water approach 0.1 mg litre?1. 相似文献
73.
74.
The assessment of scattered light in lenses, sunglasses and eye protection has been carried out in various ways. Wide‐angle scatter (haze) is used in the United States, Australia and New Zealand. Small‐angle scatter (light diffusion) is specified in Europe. Little is known of the relationships within and between the methods. In an international standard, a single method is generally required. The measurement of wide‐angle scatter (haze) (two variations of a method) and small‐angle scatter (light diffusion) (three variations of a method) were carried out on 12 samples, 4 abraded, 4 with inclusion defects and 4 with surface coating defects, in an international inter‐laboratory comparison. The consensus means and confidence limits were used to compare two haze methods: the “Basic” light diffusion method and two variations of the “Simplified” light diffusion method. For abraded samples, haze and light diffusion measures are linearly related. For the remaining samples, the haze method was a much more sensitive detector of low levels of light scatter. The three measures of light diffusion are highly linearly correlated. Haze is the more sensitive measure for lower levels of light scatter when due to smaller scattering elements. The Basic and Simplified methods are highly linearly correlated. The red laser Simplified method returns a value 10% lower than that of the Basic method, and the green laser Simplified method returns a value 12% higher than that of the Basic method. These can be accounted for by a calibration factor or different acceptance values. © 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 416–423, 2016 相似文献
75.
M.A. Aramendía V. Borau C. Jiménez A. Marinas J.M. Marinas A. Porras F.J. Urbano 《Catalysis Letters》1998,50(3-4):173-177
Two MgO/B2O3 and SiO2/AlPO4 catalysts designated BM50 and PM2, respectively, were used in the gas-phase hydrogen transfer between acrolein and 2-propanol to obtain allyl alcohol and propanal. The acid-base properties and catalytic activity of the two systems were found to be rather different. Thus, the MgO/B2O3 catalyst is more selective towards allyl alcohol than is the SiO2/ AlPO4 catalyst (conversion to the alcohol was 28% with the former and 0% with the latter). This special selectivity is discussed in terms of the different ways in which acrolein can be adsorbed on the catalytic surface as revealed by temperature-programmed desorption profiles and DRIFT spectra for pre-adsorbed acrolein. This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
76.
Studied the use of reference systems in letters of recommendation to determine if status and solidarity norms reflect gender inequality in academia. Patterning of form of reference (i.e., recommender's use of first name, full name, last name, or formal title when referring to the candidate) was examined in 1,049 letters for 284 psychology and sociology candidates for academic positions. Sex of recommender, academic area, and quality of doctoral institution were used as controls. Results show more frequent references by title to females and by first name to males. A 2nd study of 102 academicians' perceptions of the meaning implied by different forms of reference provided the basis for interpreting the findings. As letter readers, Ss interpreted title to mean status and first name to indicate solidarity. Sex differences emerged when Ss were treated as letter writers: Men focused on the solidarity dimension, with first name clearly indicating liking, whereas women emphasized the status norm, using first name primarily to imply low status. Findings suggest that an interpretation of the application of solidarity and/or status norms with form of reference must consider both sex of recommender and sex of applicant. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
77.
Saab-Rincon Gloria; Juarez Victor Rivelino; Osuna Joel; Sanchez Filiberto; Soberon Xavier 《Protein engineering, design & selection : PEDS》2001,14(3):149-155
A monomeric version of triosephosphate isomerase from Trypanosomabrucei, MonoTIM, has very low activity, and the same is truefor all of the additional monomeric variants so far constructed.Here, we subjected MonoTIM to directed evolution schemes toachieve an activity improvement. The construction of a suitablestrain for genetic selection provided an effective way to obtainactive catalysts from a diverse population of protein variants.We used this tool to identify active mutants from two differentstrategies of mutagenesis: random mutagenesis of the whole geneand randomization of loop 2. Both strategies converged in theisolation of mutations Ala43 to Pro and Thr44 to either Alaor Ser, when randomizing the entire gene or to Arg in the caseof randomization of loop 2. The kinetic characterization ofthe two more active mutants showed an increase of 11-fold inkcat and a reduction of 4-fold in Km for both of them, demonstratingthe sensitivity of the selection method. A small differencein growth rate is observed when both mutant genes are compared,which seems to be attributable to a difference in solubilityof the expressed proteins. 相似文献
78.
One hundred twenty-seven individuals who ranged in age from18 to 90 years were tested on a reading span test and on measures of on-line and off-line sentence processing efficiency. Older participants had reduced working-memory spans compared with younger participants. The on-line measures were sensitive to local increases in processing load, and the off-line measures were sensitive to the syntactic complexity of the sentences. Older and younger participants showed similar effects of syntactic complexity on the on-line measures. There was some evidence that older participants were more affected than younger participants by syntactic complexity on the off-line measures. The results support the hypothesis that on-line processes involved in recognizing linguistic forms and determining the literal, preferred, discourse-coherent meaning of sentences constitute a domain of language processing that relies on its own processing resource or working-memory system. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
79.
Allison Chang Cynthia Rudin Michael Cavaretta Robert Thomas Gloria Chou 《Machine Learning》2012,88(3):369-398
A good or bad product quality rating can make or break an organization. However, the notion of ??quality?? is often defined by an independent rating company that does not make the formula for determining the rank of a product publicly available. In order to invest wisely in product development, organizations are starting to use intelligent approaches for determining how funding for product development should be allocated. A critical step in this process is to ??reverse-engineer?? a rating company??s proprietary model as closely as possible. In this work, we provide a machine learning approach for this task, which optimizes a certain rank statistic that encodes preference information specific to quality rating data. We present experiments on data from a major quality rating company, and provide new methods for evaluating the solution. In addition, we provide an approach to use the reverse-engineered model to achieve a top ranked product in a cost-effective way. 相似文献
80.
The authors tested the ability of capuchin monkeys (Cebus apella) to make inferences about hidden food. In Experiment 1, we showed the content of 2 boxes, 1 of which was baited (visual condition, VC) or we shook both boxes producing noise from the baited box (auditory condition, AC). Seven subjects (out of 8) were above chance in the VC, whereas only 1 was above chance in AC. During treatment, by manipulating empty and filled objects subjects experienced the relation between noise and content. When tested again, 7 capuchins were above chance in the VC and 3 in AC. In Experiment 2, we gave visual or auditory information only about the empty box and, consequently, successful choice implied inferential reasoning. All subjects (out of 4) were above chance in the VC, and 2 in the AC. Control tests ruled out the possibility that success resulted from simply avoiding the shaken noiseless box, or from the use of arbitrary auditory information. Similar to apes (Call, 2004), capuchins were capable of inferential reasoning. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献