Influence of hydrogen on the microstructure of plasma-sprayed yttria-stabilized zirconia coatings

The influence of secondary hydrogen and current on the deposition efficiency (DE) and microstructure of yttria-stabilized zirconia (YSZ) coatings was evaluated. To better understand the influence of the spray process on coating consistency, a YSZ powder, −125 +44 μm, was sprayed with nitrogen/hydrogen parameters and a 9 MB plasma gun from Sulzer Metco. DE and coating porosity, which were produced using two different spray gun conditions yielding the same input power, were compared. Amperage was allowed to vary between 500 and 560 A, and hydrogen was adjusted to maintain constant power, while nitrogen flow was kept at a fixed level. Several power conditions, ranging from 32 to 39 kW, were tested. Different injection geometries (i.e., radial with and without a backward component) were also compared. The latter was found to produce higher in-flight temperatures due to a longer residence time of the powder particles in the hotter portion of the plasma. Porosity was based on cross-sectional micrographs. In-flight particle temperature and velocity measurements were also carried out with a special sensor for each condition. Test results showed that DE and coating density could vary significantly when a different hydrogen flow rate was used to maintain constant input power. On the other hand, DE was found to correlate very well with the temperature of the in-flight particles. Therefore, to obtain more consistent and reproducible DE and microstructures, it is preferable to maintain the in-flight particle temperature around a constant value instead of keeping a constant input power by adjusting the secondary hydrogen flow rate.     

Formation and relative stability of interstitial solid solutions at interfaces in metal matrix composites

On the example of Cu-C composite material the way to calculate the occupation of the interstitial positions and its temperature dependence is shown. The results obtained on the basis of non-empirical calculations indicate the preferable occupation of octahedral positions up to T1200 K. This confirms the structure of the interstitial solid solution. Within this model the influence of the alloying on the height of the diffusion barrier and on the temperature dependence of carbon diffusion in copper is calculated.     

Contamination-free continuous flow microfluidic polymerase chain reaction for quantitative and clinical applications

We present a method for performing polymerase chain reaction (PCR) using isolated droplets flowing in an immiscible fluorinated solvent system. Thanks to an optimized control of interfacial properties, we could achieve in this capillary-based system reproducible amplification factors, without any detectable contamination between neighboring droplets. The system is readily amenable to further miniaturization and automation and serves as the first step toward a clinically viable, high-throughput, quantitative continuous flow PCR apparatus.     

Plasma modification of a protective coating formed by hexamethyleniminem-nitrobenzoate on iron

A layer of hexamethyleniminem-nitrobenzoate was modified in low-temperature plasma on the air-oxidized iron surface. The composition and physicochemical properties of the modified inhibitor was studied by XPES and atomic force microscopy. It was assumed and then justified that the enhanced protective properties of a plasma-treated coating are due to the formation of corrosion-resistant iron nitrides and oxides, as well as new nitrogen- and oxygen-containing organic compounds with better inhibitive and adhesive abilities. Plasma-induced polymerization of the coating results in a high-strength, dense hydrophobic film that seems to be responsible for its enhanced barrier properties.     

Comparison of radial and frontal blowing over a rotating screened disk

The results are presented of computer calculations of the flow of a viscous fluid between a cooled rotating disk and a fixed screen for two methods of supplying the cooling medium-radial and frontal.     

Poly(2,4-perfluoroalkylene-6-Perfluoroalkyltriazine)s,new high temperature elastomers

Poly(perfluoroalkyleneimidoylperfluoroalkylenoamidine)s have been prepared by the reaction of perfluoroalkane dinitriles with ammonia or with the diamidines of the dinitriles. The imidoylamidine polymers were treated with anhydrides to give poly(perfluoroalkyIenetriazine)s. Treatment of the imidoylamidine polymer with perfluoroglutaric anhydride or 4-cyanoperfluorobutyryl chloride gave pendant carboxyl or nitrile groups, respectively, on the triazine polymer which served as crosslinking sites. The formation of triazine crosslinks from the nitrile-pendant groups by trimerization with catalysts such as tetraphenyltin has given crosslinked polymers with tensile strengths of 1500 p.s.i., 70% elongation, and with thermal stability aproaching that of the original gum. The milling of catalysts and fillers with the polymer decreased the thermal stability in comparison with the original gum.     

Henry Goddard and the feeble-mindedness of Jews, Hungarians, Italians, and Russians.

Comments on R. Herrnstein's (1981) criticism of Albee for attributing to H. Goddard (1913, 1917) the statement that "83% of the Jews, 80% of the Hungarians, 79% of the Italians, and 87% of the Russians were 'feeble-minded'," on the basis of Binet tests given to a sample of immigrants at Ellis Island. The present author maintains that it is not Goddard's statement, but L. J. Kamin's (1974) and that Kamin's 2 reference notes on Goddard appear to be reversed and neither contains the page number of Goddard's table from which the information was taken. A reproduction of Goddard's table is presented for further clarification. It is emphasized that Goddard did not conclude that the high percentage of feeble-mindedness was evidence of a hereditary defect in immigrants. (4 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Toward the development of a system for instructional evaluation: Is there consensus regarding what constitutes effective teaching?

The judgment policies of faculty and students from 4 academic divisions were modeled using multiple regression to determine (a) what dimensions of teaching are considered most important, (b) whether faculty and students differ in their conceptions of effective teaching, and (c) whether the relative importance of the dimensions of teaching is seen as depending on the academic discipline being taught. 40 male faculty members and 40 male undergraduates rated profiles of 100 hypothetical instructors, which contained 7 quantified cues reflecting instructor performance on dimensions thought to be related to teaching effectiveness. The dimensions, in order of importance, were (a) amount of information imparted in the course (INFO), (b) arousal of student interest (AROU), (c) lecture and/or presentation style (LECT), (d) instructor's general knowledge of the field (KNOW), (e) intellectual demand of the course (DEMD), (f) general rapport with students (RAPR), and (g) clarity of course requirements and grading procedures (PROC). Findings suggest that a valid system of instructional evaluation should focus on INFO, AROU, LECT, and KNOW. Very few Ss varied the weight attached to the dimensions of teaching as a function of the area rate. Hierarchical grouping procedures were used to cluster raters according to policy homogeneity and 4 types of raters were identified. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)