Phase transformation in the binary section of the UO2-FeO-Fe system

Phase transformations in the oxide binary section of the UO₂-FeO-Fe ternary system were studied. The melting onset point of the UO₂-FeO heterogeneous system (1335±5°C) was determined and the fusion curve of this system was constructed. The limiting solubility of FeO in the UO₂ solid solution was measured. The changes in crystal parameters in formation of the solid solution were determined. Uranium dioxide was found to be insoluble in the wüstite phase (FeO).     

Deactivation of a platinum reforming catalyst in a tubular reactor

This work concerns the methodology of characterizing the deactivation of a catalyst by coke deposition. The isomerization of n.pentane on a platinum reforming catalyst was studied in a tubular reactor permitting easy sampling of the gas phase at several positions in the reactor. Runs with high ratios of hydrogen to pentane did not show any deactivation and served to determine the kinetics of the main reaction and the principal side reaction, hydrocracking. At low ratios of hydrogen to pentane the catalyst was deactivated by carbonaceous deposits. At the end of the run the coke was determined in sections of the reactor and was found to be deposited according to a profile. Additional insight into the coking phenomenon was obtained from experiments on a thermobalance. A mathematical model for the performance of the tubular reactor subject to coking was set up and the parameters were determined from the experimental data. The parameters were found to be significantly determined and to obey the Arrhenius temperature dependence. The values of the parameters of the main reaction and of the hydrocracking side reaction which were derived from the experiments in the presence of coking were in agreement with those obtained from the runs in the absence of coking.     

Indecisiveness and high school students' career decision-making process: Longitudinal associations and the mediational role of anxiety.

This study examined how indecisiveness relates to adolescents' process of choosing a study in higher education, using a longitudinal design. A sample of 281 students participated at the beginning, middle, and end of Grade 12. Findings show that indecisiveness was a risk factor for future levels of coping with the career decisional tasks of broad and in-depth environmental exploration (amount of information and exploratory behavior), amount of self-information, decisional status, and commitment. However, indecisiveness did not relate to the degree of change in decisional tasks during Grade 12. Moreover, results suggest that the linkage of indecisiveness with the amount of in-depth environmental information, the amount of self-information, decisional status, and commitment was mediated by adolescents' career choice anxiety. Finally, stability data provided support for the conceptualization of indecisiveness as a trait. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Resistance of butyrylcholinesterase to inactivation by ultrasound: effects of ultrasound on catalytic activity and subunit association

We previously examined Moloney murine leukemia virus-induced fusion-from-within (FFWI) and fusion-from-without (FFWO) of SC-1 mouse cells. FFWI and FFWO can be distinguished by their stimulation by ionophores and polycations, respectively. FFWI is caused by infected cells. Normally, fusion between an infected cell and uninfected cells (heterofusions) is described, but we have surprisingly found that the infected cells also caused homofusion between uninfected cells in their vicinity (named neighbor homofusions). It was shown that neighbor homofusions were not induced by free virus particles (by FFWO). Transfectants expressing envelope proteins only induced heterofusions, indicating that virus production is necessary for the formation of neighbor homofusions. Both plasma membrane fragments and easily removable material from the surface of infected cells were able to induce fusion with the same stimulation pattern as FFWI and neighbor homofusion. These materials, especially the latter, have properties in common with virions, and it is discussed whether immature virions are involved in the formation of the neighbor homofusions.     

Physiological approach to heterologous human serum albumin production by Kluyveromyces lactis in chemostat culture

Production of recombinant human serum albumin (rHSA) controlled by the constitutive promoter phosphoglycerate kinase was studied in Kluyveromyces lactis. It was governed by both cell concentration and glycolytic flow. The triggering of the fermentation metabolism by unfavourable culture conditions (pH, pO₂, D) caused a decrease in the synthesis of the heterologous protein. The highest productivity (75 mg 1^?1 per h) and rHSA concentration (62 mg 1^?1) were obtained in chemostat culture with a dilution rate of 0·12 h^?1 and with 38 g 1^?1 dry weight.     

Teaching sustainable design in architecture education: Critical review of Easy Approach for Sustainable and Environmental Design (EASED)

In the current context of climate change and ecological awareness, designing sustainable environments is definitely understood as a shared responsibility. With the construction sector consuming half of the world׳s energy, the role of some key stakeholders such as architects becomes even more critical when providing responsible and relevant design for the built environment. Thus, improving the way our environments are being designed challenges some cultural systems that show evident limits, such as the training of future architects and engineers.In this research, the focus is on architecture students and aims to demonstrate how the use of a new sustainable performance simulation tool, called Easy Approach for Sustainable and Environmental Design (EASED) could contribute to educate them about innovatively sustainable design. This was assessed through the evaluation of student engagement, their use of the tool and its appropriation. Results show that individual work was not convincing, whereas success was met during group work. Limits and improvement possibilities were found in the interface of EASED as well as in the educational set up of the tool.     

Expression and effect of resistin on bovine and rat granulosa cell steroidogenesis and proliferation

Resistin, initially identified in adipose tissue and macrophages, was implicated in insulin resistance. Recently, its mRNA was found in hypothalamo-pituitary axis and rat testis, leading us to hypothesize that resistin may be expressed in ovary. In this study, we determined in rats and cows 1) the characterization of resistin in ovary by RT-PCR, immunoblotting, and immunohistochemistry and 2) the effects of recombinant resistin (10, 100, 333, and 667 ng/ml) ± IGF1 (76 ng/ml) on steroidogenesis, proliferation, and signaling pathways of granulosa cells (GC) measured by enzyme immunoassay, [(3)H]thymidine incorporation, and immunoblotting respectively. We observed that resistin mRNA and protein were present in several bovine and rat ovarian cells. Nevertheless, only bovine GC abundantly expressed resistin mRNA and protein. Resistin treatment decreased basal but not IGF1-induced progesterone (P<0.05; whatever the dose) and estradiol (P<0.005; for 10 and 333 ng/ml) production by bovine GC. In rats, resistin (10 ng/ml) increased basal and IGF1-induced progesterone secretion (P<0.0001), without effect on estradiol release. We found no effect of resistin on rat GC proliferation. Conversely, in cows, resistin increased basal proliferation (P<0.0001; for 100-667 ng/ml) and decreased IGF1-induced proliferation of GC (P<0.0001; for 10-333 ng/ml) associated with a decrease in cyclin D2 protein level (P<0.0001). Finally, resistin stimulated AKT and p38-MAPK phosphorylation in both species, ERK1/2-MAPK phosphorylation in rats and had the opposite effect on the AMPK pathway (P<0.05). In conclusion, our results show that resistin is expressed in rat and bovine ovaries. Furthermore, it can modulate GC functions in basal state or in response to IGF1 in vitro.     

Parameters effect on proton conductivity to obtain chitosan membranes for use as electrolytes in PEMFC

The chitosan biopolymer can be used as a proton‐conducting membrane in proton‐exchange membrane fuel cell. In the forms that they have normally obtained and tested, chitosan membranes typically show poor performance in conduction of protons, requiring modifications in the structure of the biopolymer or blending with other polymers to increase its proton conductivity. The present work investigates the individual properties of chitosan and relates them to the proton conductivity performance of membranes composed of this polymer. Evaluation was made of the effects of variables such as the degree of deacetylation (DD) and the molar mass (Mv) of chitosan membranes without addition of any other polymer. The DD and Mv values of the chitosan used to produce membranes determined the proton conduction, with lower DD and higher Mv resulting in higher conductivity. The thicker membranes presented greater crystallinity, with conductivity between 2.0 × 10^?4 and 1.8 × 10^?3 S cm^?1. The characteristic stages of degradation of the chitosan membranes were in the ranges 200 to 300°C and 500 to 600°C, indicating good thermal stability of the material.