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51.
52.
Brett Gantt Shamia Hoque Kathleen M. Fahey Robert D. Willis Juana Maria Delgado-Saborit Roy M. Harrison 《Aerosol science and technology》2013,47(6):371-380
Despite the use of cerium oxide nanoparticles (nCe) in some regions as a diesel fuel additive, the physicochemical properties of the resulting exhaust particles in the ambient atmosphere are not well known. The mixing state of ceria with other exhaust particles is one such physicochemical property that has been shown to potentially affect ecosystem/human health. In this study, cerium-containing particles associated with an nCe additive were collected in the laboratory and in Newcastle-upon-Tyne, UK where the local bus fleet uses the Envirox nCe additive. Electron microscopy of laboratory-generated exhaust samples indicated both individual ceria and soot particles (external mixture) and ceria contained within soot agglomerations (internal mixture). Low ambient concentrations prevented quantification of the ceria particle mixing state in the atmosphere; therefore, a multicomponent sectional aerosol dynamic model was used to predict the size, chemical composition, and mixing state of ceria particles as a function of distance from an idealized roadway. Model simulations predicted that most ceria particles remain nonmixed in the ambient atmosphere (300 m downwind from the roadway) due to slow coagulation, with the mixing rate most sensitive to the ceria content of emitted nuclei-mode particles and the particle concentration upwind of the road. Although microscopy analysis showed both external and internal mixtures of ceria and soot in freshly emitted particles, the ambient mass concentration, and size distribution of ceria particles predicted by the model was insensitive to the emitted mixing state.Copyright 2015 American Association for Aerosol Research 相似文献
53.
C. Frias O. Frazão S. Tavares A. Vieira A.T. Marques J. Simões 《Materials & Design》2009,30(5):1841-1844
The aim of this work was the study and understanding of the behavior and linearity of an optical fiber Bragg grating (FBG) sensor embedded in bone cement. Test its ability to monitor strains inside bone cement during different mechanical tests, at real-time. Bone cement is a biomaterials based on polymethacrylate used as fixation method in artificial joints. Work as a bonding, load transfer and optimal stress/strain distribution inside the complex human body environment. Bone cement is the weakest element in a joint implant, being considered the main reason of prosthesis loosening.Inside the bone cement, its temperature, longitudinal strain and load were measured using fiber Bragg gratings. All the measurements report a linear response showing a good adaptation and optimization of the load transfer between the biomaterial and the embedded optical sensor. 相似文献
54.
Luis Juana Raúl Sánchez Leonor Rodríguez-Sinobas Francisco Laguna 《Canadian Metallurgical Quarterly》2009,135(2):186-199
This technical paper presents analytical expressions to estimate the probability function of head losses in any path of an on-demand branched irrigation network. They are developed for estimating the probability of pressure deficit of a given magnitude at any hydrant. They are also useful for examining the probability of a power deficit at a pumping station designed to guarantee service to a hydrant, as well as the head characteristic curve of the distribution system linked to a definite probability. All this quantified information is useful for decision making on network design and performance. The probabilities calculated with the developed expressions can be taken as complementary or alternative concepts to Clément’s classical design flow method, which is taken here as a benchmark for comparisons. Illustrative examples of network designs are presented to validate the proposed expressions. The least cost design solutions using Clément’s design flows are compared with design solutions here obtained to get the same probability of pressure deficit at the most unfavorable hydrants. The new solutions are less expensive because the flow constraint can be avoided. 相似文献
55.
Fernando Fungo Luis A. Otero Leonides Sereno Juana J. Silber Edgardo N. Durantini 《Dyes and Pigments》2001,50(3):163-170
A convenient procedure for the synthesis of a new porphyrin–C60 dyad via the reaction between 5-(4-aminophenyl)-10,15,20-tris(4-methoxyphenyl) porphyrin and a C60 carboxylic acid is described. The results of preliminary photoelectrochemical studies on nanostructured SnO2 electrodes coated with the new dyad suggest that the resultant substrate is suitable for solar energy conversion devices. 相似文献
56.
Mercedes Jimenez Josefa Escribano Manuela Pérez-Gilabert Soledad Chazarra Juana Cabanes Francisco García-Carmona 《Lipids》2001,36(10):1169-1174
Patatin was extracted from potato tubers (Solanum tuberosum L. cv. Spunta) and purified to homogeneity by ammonium sulfate salt fractionation and one sole chromatographic step. A spectrophotometric
mixed micellar assay for patatin lipid acyl hydrolase (LAH) activity was designed with the detergent octaethylene glycol monododecyl
ether (C12E8). Patatin LAH used p-nitrophenyl butyrate (PNP-butyrate) as substrate when solubilized in (C12E8) micelles. In the mixed micellar system, patatin LAH responds to the PNP-butyrate surface concentration expressed as mol%
(=[PNP-butyrate]·100/([detergent]-critical micellar concentration)) and not to the molarity of PNP-butyrate. The kinetic parameters
were determinined; V
max was independent of the mixed micelle concentration, as was K
m, when expressed as mol%. However, K
m was dependent on C12E8 concentration when expressed in molar concentration. C12E8/PNP-butyrate proved to be a reliable system for assaying patatin LAH activity and is superior to the commonly used Triton
X-100 and SDS methods. It permits investigation of the substrate requirements of patatin LAH activity because the concentration-independent
K
m can be determined both in mol% and as the absolute number of substrate molecules per micelle. In addition, the detergent
did not affect the enzyme activity. 相似文献
57.
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59.
The influence of hydrocortisone acetate i.m. administered (4 mg/100 g of body weight and day) to pregnant rats, on magnesium nutritive utilization and bone magnesium content in the mothers and its possible repercussions on newborn Mg content are studied. Hydrocortisone acetate treatment significantly reduces Mg content in the litters, which can be explained on the basis of a significant decrease in both the magnesium absorption and retention by the hormone-treated mothers. The mobilization of femoral magnesium and the increase in the urinary excretion of the cation provoke a reduction in magnesium retention in the treated mothers. 相似文献
60.
Luís Juana Alberto Losada Leonor Rodríguez-Sinobas Raúl Sánchez 《Canadian Metallurgical Quarterly》2004,130(1):47-59
Approximate analytical expressions were obtained that relate uniformity indices of water distribution in rectangular drip irrigation units as a function of the variables that define that unit: lengths and diameters of laterals and submain, spacing of emitters and laterals, ground slopes, parameters of the emitter discharge equation, and equivalent lengths characterizing local losses. The proposed expressions offer greater precision than might be needed in irrigation practice. They do not require iterative calculations and improve the procedures normally used. They may be useful in the design of drip irrigation units and in their evaluation and management. An example of their application is offered. The proposed relationships simplify studies of the sensitivity of variables involved in optimum hydraulic design. Users are thus allowed a rational understanding of their influence, improving that which can be gained from computer programs. Graphs obtained with the mentioned expressions are also offered. They can be of interest, although their use is not treated specifically in this paper. 相似文献