Morphology and structure of YSZ powders: Comparison between xerogel and aerogel

Yttria-stabilized zirconia (YSZ) fine powders were prepared via sol–gel route in order to shape thermal barrier coatings (TBCs) from these powders. The main objective is to develop new undirectional coatings to allow best thermo-mechanical accommodations compared to conventional processes. To reach this aim, powders have to be able first to be highly dispersed into a sol (non-agglomeration, high specific surface area, etc.) and second to crystallize in the required metastable phase t′. Two routes have been used to dry gels: the conventional way which consists of simple evaporation of the solvent is compared to drying in supercritical conditions. Both YSZ powders after calcination at 950 °C of xerogel (Ex-xero-YSZ powder) and aerogel (Ex-aero-YSZ powder) crystallize in the tetragonal form. N₂ adsorption/desorption analysis of the Ex-xero-YSZ powder indicates an S_w of 2.8 m²/g. For the Ex-aero-YSZ powder, the S_w (26 m²/g) is much higher than of Ex-xero-YSZ, leading to a better sintering capability. This high S_w is correlated to the small crystallite size (26 nm) and the alveolar morphology of Ex-aero-YSZ powders compared to Ex-xero-powder (49 nm). By reducing particles size and increasing the S_w of the powders, supercritical drying appears as a promising way to prepare stable slurries or loaded sols from fine YSZ particles for TBC applications. Indeed, after preparing nanometric powders, they are dispersed into a sol before shaping on superalloys substrates. After thermal treatment at 950 °C for 2 h which corresponds to the working temperature of TBC, the final aim will be to prepare ceramic YSZ coatings.     

Acculturation, enculturation, parental adherence to Asian cultural values, parenting styles, and family conflict among Asian American college students.

The present study examined the relations between perceived parenting styles and family conflict with data from 149 Asian American college students. Ratings of parenting styles were highest for authoritarian style, followed by authoritative and permissive styles. Tests of mediation revealed that authoritarian parenting significantly explained why parents’ adherence to Asian cultural values was associated with increased family conflict. Tests of moderation showed that as permissive parenting increased, more acculturated participants reported lower family conflict, although the reverse was true for their less acculturated counterparts. When authoritarian parenting increased, integrated, separated, and assimilated participants reported increased family conflict, whereas the marginalized group reported lower family conflict. Finally, assimilated participants reported less family conflicts at higher levels of authoritative parenting in comparison to the integrated, separated, and marginalized groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dry vacuum pumping technology outperforms oil-sealed pumps for investment casting

Investment casting is a demanding application for a vacuum pump. Indeed, many traditional oil-sealed pumps cannot maintain the required vacuum performance and have fallen by the wayside, due to the high wear on machinery inherent in this dusty environment. However, in a 20-month trial at an investment casting company in South-West England, a dry pumping system has shown greater reliability, improved vacuum performance and reduced maintenance downtime over the previous oil-sealed technology.     

Proteomic analysis of BRCA1-depleted cell line reveals a putative role for replication protein A2 up-regulation in BRCA1 breast tumor development

Purpose : Germline mutations in BRCA1 result in a strong predisposition to breast cancer, with frequent loss of heterozygosity of the remaining wild‐type allele. The development of BRCA1 tumors is likely to depend on additional genetic alterations and gene expression changes which follow growth and DNA repair defects associated with BRCA1 deficiency. The identification of these modifications offers an opportunity to find surrogate markers of BRCA1 tumors. Here, we sought to identify differentially expressed proteins related to BRCA1 depletion. Experimental design : We used isogenic HeLa cells either stably knocked‐down or not for BRCA1 (BRCA1^KD) and compared protein profiles of these cells by DIGE. Results : We detected increased levels of Replication protein A2 (RPA2) in BRCA1^KD cells as compared to control cells. RPA2 is an essential protein required for DNA replication and repair. We further demonstrated that depletion of RPA2 subunit delays growth of BRCA1^KD respect to isogenic control cells. Strikingly, elevated levels of RPA2 were more frequently observed in BRCA1 tumors when triple‐negative tumors from BRCA1 mutation carriers (n=13) and non‐carriers (n=36) were stained in situ for RPA2. Conclusions and clinical relevance : RPA2 up‐regulation may thus be involved in the growth and/or survival of BRCA1 tumor cells and useful in immunohistochemical discrimination of triple‐negative BRCA1 tumors.     

Triacylglycerols and Polar Lipids in Cow and Goat Milk are Differentially Affected by Various Lipid Supplemented Diets

This study characterizes milk triacylglycerol (TAG) and polar lipid (PL) fractions from cows and goats fed various lipid supplements modulating milk fat content. Twelve Holstein cows and 12 Alpine goats, at 86 ± 24.9 and 61 ± 1.8 days in milk, respectively, are allocated to one of 4 groups to receive diets supplemented with either corn oil [5% dry matter intake (DMI)] plus wheat starch (COS), marine algae powder (MAP; 1.5% DMI) or hydrogenated palm oil (HPO; 3% DMI), or a no-added-lipid control diet (CTL), according to a 4 × 4 Latin square design with 28 d experimental periods. Milk TAG and PL contents are determined by liquid chromatography-mass spectrometry (LC-MS). Multivariate analysis and ANOVA demonstrate major between-species differences in diet effects. In cows, COS specifically increases TAG 54:3 and 54:4 associated with milk fat depression (MFD), and increases the sum of phosphatidylcholines (PC) and phosphatidylinositols (PI). In addition to causing a MFD, MAP diet increases long-chain polyunsaturated TAG in both species, with higher magnitude in cows than in goats, and decreases the sum of PI in goats. HPO increases TAG 52:1 and the sum of PI in cows, but not in goats. Practical applications: Feed strategies can quickly and efficiently modulate the ruminant milk fat production and composition to improve nutritional quality for consumers. Certain starch-rich diets supplemented with polyunsaturated fatty acids (PUFA)-rich vegetable oils and diets supplemented with marine products (long-chain PUFA) reduce milk fat secretion and modify the milk fatty acid (FA) profile in cows, but not—or less so—in goats. Advanced analysis of both the TAG and PL fractions of milk fat is required to unravel these differences in lipid metabolism between cows and goats fed various lipid-supplemented diets. This study brings new insight on using nutritional strategies to control milk lipid composition according to ruminant species.     

Effect of water-miscible organic solvents on the catalytic activity of cytochrome c

The effect of five water-miscible organic solvents (tetrahydrofuran, N,N-dimethylformamide, acetonitrile, 2-propanol, and methanol) on the oxidation of pinacyanol chloride (Quinaldine Blue) by horse heart cytochrome c was determined. Hydrogen peroxide was used as the oxidant, and a change in catalytic property of the dissolved protein was observed after a certain threshold concentration of the organic solvent had been reached. The maximum specific activity was correlated with the Dimroth-Reichardt parameter for the solvents, which is directly related to the free energy of the solvation process. The kinetic constants for the oxidation of pinacyanol chloride were determined in systems containing different proportions of tetrahydrofuran. The best catalytic efficiency (kcat/KM,app) was obtained in a system containing 50% tetrahydrofuran in phosphate buffer. In a mixture containing 90% tetrahydrofuran, cytochrome c showed 18% of its maximum activity. The inactivation of cytochrome c was mainly due to the presence of hydrogen peroxide, and a direct correlation was found between the inactivation constant and the concentration of hydrogen peroxide in the system. The chemical modifications and immobilization of cytochrome c were able to change its biocatalytic activity and stability in the organic solvent system. The kinetic constants and the inactivation of three other type c cytochromes, from Saccharomyces cerevisiae, Pseudomonas aeruginosa, and Desulfovibrio vulgaris Hildenborough in a system containing 90% tetrahydrofuran were compared with those of cytochrome c from horse heart. Cytochrome c551 from P. aeruginosa showed the best stability against hydrogen peroxide and a higher catalytic efficiency than that of horse heart cytochrome c.     

Occupied interstices in stoichiometric and hyperstoichiometric V2H(D)

A geometric model based on criteria of a minimum hole size for occupation by H(D) and a minimum distance between pairs of H(D) atoms has been applied to V₂H(D). The model allows a rationalization for the observed occupation of octahedral o_Z1 sites in the stoichiometric compound and for randomization in all o_Z sites in hyperstoichiometric V₂H.     

Role of the input in visual hemispheric asymmetries.

Because the nature of the input is one of the most important variables in determining how the brain will process information, findings from tachistoscopic studies aimed at assessing hemispheric lateralization of functions are examined in terms of the characteristics of the incoming information either available or required for processing. The basic features of tachistoscopic experiments are analyzed with a special emphasis on methodology. Variables determining the quality of the input are investigated as a function of the properties of the human visual system. Exposure duration, luminance, retinal eccentricity, and stimulus size all contribute to the efficiency of the hemispheres and interact in complex ways in the emergence of visual-field superiorities. Task demands are also examined in terms of the information necessary for efficient processing. The present review suggests that in tachistoscopic experiments, the factors determining the quality of the input must be controlled if this technique is to prove a reliable source of information for assessing hemispheric asymmetries. (5 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Early intrauterine development: II. The rate of growth in Black and Central American populations between 10 and 20 weeks' gestation

The application of the growth-rate standards, extablished for Caucasian embryos and fetuses in a previous report, to Black and Central American racial groups has been investigated. Comparison between menstrual age and crown-to-rump length indicated differences in the 10 to 15 weeks' gestation range. However, growth rates for the same groups were practically identical between the 15th and 20th weeks of pregnancy. This finding suggests that the actual rate of growth is closely similar in the respective ethnic groups and that apparent discrepancies reflect erroneous, or purposefully false, menstrual histories rather than dissimilar growth patterns. Largely identical rates of development were suggested by the crown-rump length to foot length to body weight interrelations among the various racial groups. A moderate, but rather predictable, deviation from the earlier established standards was noted in the crown-rump length versus foot length ratios of Black American fetuses, providing the only exception to what appears to be a practically identical rate of growth for the investigated ethnic groups in the first half of gestation. The evaluation of the results was extended to involve the effect of educational and social factors on currently available data of embryonic and fetal growth. It is suggested that heretofore unconsidered factors may affect the validity of widely quoted standards of intrauterine growth.     

Bouyant density, conversion formulae, and the mole percent guanosine + cytosine content of Desulfovibrio sp

A reevaluation of the original buoyant density conversion formula used to calculate the molar percentage guanosine + cytosine (% G + C) contents of the accepted species of genus Desulfovibrio has been undertaken. It would appear that the formula used gives values 4-5% lower than those obtained using formulae more generally cited in modern literature. Recalculations of % G + C content values for Lesulfovibrio DNA are presented using the formulae of three different workers, and are compared with those values originally used in the classification of genus Desulfovibrio.