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11.
Proton nuclear magnetic resonance (1H NMR) was used to study the in vivo metabolism of Trypanosoma cruzi, the pathogen causing American trypanosomiasis (Chagas' disease). Three clones were isolated from a strain of T. cruzi (Bolivia strain), The clones I, II and III and the original strain were characterized according to the spectra of their metabolic pathways to test the hypothesis that clonal evolution of T. cruzi has a major impact on biologically relevant properties of this parasite. T. cruzi (Bolivia strain) excreted acetate, alanine, glycerol, and succinate as major end products, in the proportion 6:4:2:2. Comparing the spectra of T. cruzi clones with the original Bolivia strain revealed both quantitative, as well as qualitative differences in the metabolites excreted: the clones I and II, as opposed to the Bolivia strain and clone III, excreted significant quantities of ethanol. 相似文献
12.
Antecedents of interpersonally directed forms of citizenship and counterproductive behaviors (i.e., interpersonal helping and harming, respectively) have been studied most often under the broad categories of individual differences and job attitudes. Although these behaviors often are exhibited within the confines of interpersonal relationships, the impact of relationship quality and context on such behaviors has been understudied. The present study uses a social networks framework to examine the relational antecedents of interpersonal helping and harming in a sample of 62 members of a college sorority house. Results indicate that relational variables--direct, third-party, and structural or positional characteristics of positive and negative affective networks, and the frequency of voluntary interaction--explain substantial incremental variance (beyond traditional predictors) in helping and harming. Moreover, helping and harming were themselves weakly positively interrelated. Implications for theory and practice are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
13.
Chloromethylated styrene-divinylbenzene copolymer was chemically modified with ethylenediaminetetraacetic acid ligand. Catalytically
active polymer containing Ru(III) moieties were synthesized from this polymeric ligand. They were characterized using FTIR,
UV-vis, SEM, ESR and TGA. Other physico-chemical properties such as bulk density, surface area, moisture content and swelling
behaviour in different solvents were also studied. The polymer bound complex was used to study hydrogenation of 1-hexene ton-hexane under mild conditions. Influence of [1-hexene], [catalyst], temperature and nature of the solvent on the rate of the
reaction was investigated. A rate expression is proposed based on the observed initial rate data. Recycling efficiency of
the catalyst has also been studied. 相似文献
14.
15.
Urbach energy of valence band tails and mid-gap defect densities are important parameters for determining the performance of amorphous silicon (a-Si:H) devices. In this paper, we examine a technique which allows one to determine these parameters in device structures, as opposed to in films. The technique consists of measuring sub-gap quantum efficiency as a function of reverse bias and photon wavelength. We show that there is a distinction between the response of tail states and mid-gap states to the application of reverse bias, and that by analyzing these differences, one can locate the energies of the mid-gap states in the device. The technique gives an accurate measurement of Urbach edge of tail states, even on textured substrates, but only estimates mid-gap states within a factor of 2. 相似文献
16.
Cot death (sudden infant death syndrome) is one of the most common causes of death in the first year of life. Four cases with a pathological fear of cot death are presented. All the patients were depressed and in 2 cases the fear of cot death had an obsessional quality. In all cases there were complications during pregnancy (miscarriage, threatened abortion, recurrent vomiting in last trimester). In 1 case, the patient knew 3 mothers who had suffered cot deaths; in another, the infant was gravely ill in the neonatal period. Pathological fear of cot death can be recognised by the presence of two central features - overvigilance and excessive nocturnal checking of the baby's breathing. Therapeutic interventions are discussed. 相似文献
17.
Some graphical aids for deciding when to stop testing software 总被引:1,自引:0,他引:1
It is noted that the developers of large software systems must decide how much software should be tested before releasing it. An explicit tradeoff between the costs of testing and releasing is considered. The former may include the opportunity cost of continued testing, and the latter may include the cost of customer dissatisfaction and of fixing faults found in the field. Exact stopping rules were obtained by Dalal and Mallows (J. Amer., Statist. Assoc., vol.83, p.872, 1988), under the assumption that the distribution of the fault finding rate is known. Here, two important variants where the fault finding distribution is not completely known are considered. They are (i) the distribution is exponential with unknown mean and (ii) the distribution is locally exponential with the rate changing smoothly over time. New procedures for both cases are presented. In case (i) it is shown how to incorporate information from related projects and subjective inputs. Several novel graphical procedures which are easy to implement are proposed, and these are illustrated for data from a large telecommunications software system 相似文献
18.
J.S. Schrader J.L. Huguenin-Love R.J. Soukup N.J. Ianno C.L. Exstrom S.A. Darveau R.N. Udey V.L. Dalal 《Solar Energy Materials & Solar Cells》2006,90(15):2338-2345
Experimental results on thin films of the new material GexC1−x, deposited by a unique dual plasma hollow cathode sputtering technique are presented here. The (Ge, C) system is extremely promising since the addition of C to Ge has reduced the lattice dimensions enough to allow a lattice match to silicon, while increasing the bandgap close to that of c-Si. The most important contribution of this work shows that by the non-equilibrium growth conditions present using the hollow cathode technique, one can grow Group IV materials which cannot otherwise be grown using normal CVD or MBE processes. The sputtering is accomplished by igniting a DC plasma of the Ar and H2 gases which are fed through Ge and C nozzles, cylindrical tubes 30 mm in length with an 8 mm OD and a 3 mm ID. 相似文献
19.
A genetic system in wheat is described in which F1 produced by crossing a drought tolerant cultivar C306 and high yielding cultivar WL711 exhibits leaf necrosis leading to the death of the plant. The mechanism underlying hybrid necrosis is not yet known. The hybrid exhibited a higher level of superoxide anion compared to the healthy leaves of parents at similar developmental stages. This increase in superoxide generation preceded necrotic lesion formation and displayed a gradient from the leaf tip to base. The leaf tip where necrotic lesions make their first appearance exhibited a higher level of superoxide compared to the base. Superoxide anion thus appears to play a vital role in necrosis of leaves in F1 hybrid. This genetic system can be a model system for understanding cell death in higher plants. 相似文献
20.
Zehba A. S. Raizah Sameh E. Ahmed Dalal Alrowaili M. A. Mansour Z. Morsy 《亚洲传热研究》2021,50(3):2743-2763
Impacts of an inclined electromagnetic force on a mixed convective process in two-sided lid-driven geometries using the two-energy equation model are examined in this study. The flow domain is filled by a porous medium and the local thermal nonequilibrium model is applied. Magnetic micropolar nanofluids are assumed as working fluids consisting of water as a base fluid and CuO as nanoparticles. The forced convection situation is due to the moving of the upper and lower walls in the right direction with a constant velocity. The used methodology depends on the finite volume method, together with the SIMPLE algorithm. The obtained outcomes are visualized using contours of the streamlines, isotherms for the nanofluid phase, isotherms for the solid phase, and angular velocity. The main findings revealed that the increase in lengths of the heated parts and the Nield number reduces the Nusselt number for the nanofluid phase. Also, the average heat transfer rate for the nanofluid and solid phases are boosted with the increase in the vortex viscosity. 相似文献