Stability and Heat Resistance of Silicide Coatings on Refractory Metals. Part 2. Stability and Heat Resistance of Silicide Coatings on Tungsten and Molybdenum at 1500-2000°C

The kinetics of diffusion redistribution of phases within the system WSi₂ W on heating tungsten silicide in air in the temperature range 1500-2000°C is studied. The stability and heat resistance of silicide coatings on tungsten is mainly governed by the diffusion of silicon towards the interphase boundaries W W₅Si₃, W₅Si₃ WSi₂, and WSi₂ SiO₂, formation at them of diffusion barriers of lower silicide W₅Si₃, and also a protective SiO₂ film at the outer boundary of the silicide coating. It is established that the transition rate for the higher to the lower tungsten silicide WSi₂ W₅Si₃ is on average four times slower than the transition rate for MoSi₂ Mo₅Si₃. It is shown that an increase in silicon concentration in the WSi₂ surface layer stimulates formation of diffusion barrier compounds at interphase boundaries. This leads to an increase in the stability of the phase composition and heat resistance of a silicide coating on metals. In particular at 1700°C the transition rate for molybdenum silicide on tungsten MoSi₂ (Mo, W)₅Si₃ is about twenty times slower than the transition rate for MoSi₂ Mo₅Si₃, and less by a factor of about eleven than the transition rate for WSi₂ W₅Si₃. Here there is also an increase in the heat resistance of silicide coatings on tungsten and molybdenum. It is shown that the SiO₂ film on tungsten silicide does not lose its protective properties up to 2000°C.     

Campbell’s and Rubin’s perspectives on causal inference.

Donald Campbell’s approach to causal inference (D. T. Campbell, 1957; W. R. Shadish, T. D. Cook, & D. T. Campbell, 2002) is widely used in psychology and education, whereas Donald Rubin’s causal model (P. W. Holland, 1986; D. B. Rubin, 1974, 2005) is widely used in economics, statistics, medicine, and public health. Campbell’s approach focuses on the identification of threats to validity and the inclusion of design features that may prevent those threats from occurring or render them implausible. Rubin’s approach focuses on the precise specification of both the possible outcomes for each participant and assumptions that are mathematically sufficient to estimate the causal effect. In this article, the authors compare the perspectives provided by the 2 approaches on randomized experiments, broken randomized experiments in which treatment nonadherence or attrition occurs, and observational studies in which participants are assigned to treatments on an unknown basis. The authors highlight dimensions on which the 2 approaches have different emphases, including the roles of constructs versus operations, threats to validity versus assumptions, methods of addressing threats to internal validity and violations of assumptions, direction versus magnitude of causal effects, role of measurement, and causal generalization. The authors conclude that investigators can benefit from drawing on the strengths of both approaches in designing research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of hippocampal and fimbria–fornix lesions on prepulse inhibition.

The present experiments tested the effects of conventional (dorsal aspiration and electrolytic) and excitotoxic (N-methyl-{d}-aspartate [NMDA]) hippocampal lesions and fimbria-fornix (FF) transection on prepulse inhibition (PPI) of startle response and on open-field activity. Activity was increased by FF transection and by conventional but not excitotoxic hippocampal lesions; complete NMDA lesion increased amphetamine-induced activity. Whereas dorsal hippocampal aspiration lesion disrupted PPI, the phenomenon was not affected by dorsal hippocampal. electrolytic lesion, partial or complete excitotoxic (NMDA) hippocampal lesions, or complete FF transection, which interrupted the cholinergic input to the hippocampus as well as the hippocampal-subicular input to the nucleus accumbens. Systemic apomorphine disrupted PPI in both FF-transected rats and their controls. It is suggested that the hippocampus is essential for PPI disruption rather than for PPI expression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Leader–member exchange and its dimensions: Effects of self-effort and other's effort on relationship quality.

Two hundred thirty-two manager–subordinate dyads provided data on the effort expended toward the development of leader–member exchange (LMX) relationships, how such effort related to expectations about relationship quality, and intentions to exert future effort toward relationship development. For both managers and subordinates, higher quality LMX relationships were reported and expectations were met when the other member of the dyad put forth effort into relationship development. One's own higher effort coupled with lower effort by the other was associated with a lower quality LMX relationship. Examination of the 4 dimensions of LMX (R. C. Liden & J. M. Maslyn, 1998) revealed unique effects depending on the dimension considered. In addition, LMX and relationship tenure interacted, showing that future effort toward relationship development was greatest when individuals had been in higher quality relationships for longer periods of time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of microelements on microstructures and properties of Al-1. 2Mg-1. 3Si-0. 6Cu-0. 3Mn alloy

In order to save energy and protect environmentin automobile industry, one of the important methodsis to reduce the automotive weight[1 ～4]. Since the a-luminum alloys showsuch as high specific strength,good formability, good corrosion resistance, and re-cycling potential, they are said to be the ideal candi-date to replace heavier materials in the automotiveindustry[5 ～7].Recently, the heat -treatable 6000series aluminum alloys have been considered as theperfect light-weight material for au…     

Impact of child teacher relationship training on teachers’ and aides’ use of relationship-building skills and the effects on student classroom behavior.

[Correction Notice: An erratum for this article was reported in Vol 18(4) of International Journal of Play Therapy (see record 2009-18366-003). There was an error in the abstract. In the current abstract the fourth sentence reads: Using a repeated measures design, results revealed that children in the experimental group (n 19) demonstrated a significant decrease (p .04) in Externalizing Problems between measurements 1 and 3 compared to children in the active control group (n 13). However, the fourth sentence should have read “Results of ANCOVA revealed a statistically significant difference (p .04) with a large effect size in externalizing scores between the experimental (n 19) and active control groups (n 13) at the end of treatment but no difference at the 10-week non-intervention follow-up.”] This study examined the impact of Child Teacher Relationship Training on educators’ use of relationship-building skills in the classroom and the effect on student behavior. Preschool-age children (3–4 years old) who scored in the Borderline/Clinical range on at least one scale of the Child Behavior Checklist-Caregiver/Teacher Report Form (C-TRF) qualified for the study (N = 32). In this quasi-experimental design, 12 teacher aide dyads (N = 24) were assigned to the experimental (n = 12) or active control groups (n = 12). Using a repeated measures design, results revealed that children in the experimental group (n = 19) demonstrated a significant decrease (p = .04) in Externalizing Problems between measurements 1 and 3 compared with children in the active control group (n = 13). A statistically significant relationship was found between educators’ higher use of relationship-building skills and students’ decrease in externalizing behaviors (p     

Overview no. 76: Mechanism of deformation and development of rolling textures in polycrystalline f.c.c. metals—II. Simulation and interpretation of experiments on the basis of Taylor-type theories

Simulations of f.c.c. rolling textures based on homogeneous slip under conditions of full and relaxed constraints (Taylor-type theories) are presented. The characteristic peak and fibre components found in the resultant ODFs for the various relaxed shear possibilities are analysed in great detail and compared with the experimentally observed textures in Al and the CuZn alloys given in Part I. Special attention has been paid to the questions of stability and metastability of different orientations, the position of the fibres in orientation space, the influence of initial textures, the pathways that individual orientations take together with their rates of rotation along and their arrival rates at the fibres. Finally the topological distribution of grains in connection with the compatibility problem of the different stable orientations caused by relaxed shears is discussed.     

A scientist–practitioner's viewpoint on the admissibility of behavioral and social scientific information.

Problems in applying the Daubert (1993) test to social science evidence are discussed, and new issues are raised. In particular, the difference between the legal treatment of clinical evidence, as opposed to actuarial evidence, is discussed. The changing nature of science and the effect of societal norms on evidence requirements are noted. Questions are raised about the definition of the scientific method, and an alternative to the traditional scientific treatment of data is offered and discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Lanthanum and Europium on Rooting of Plantlet Eriobotrya Japonica Lindl. in vitro

ＲａｒｅＥａｒｔｈＥｌｅｍｅｎｔｓ (ＲＥＥｓ)ｈａｖｅｂｅｅｎｗｉｄｅｌｙｕｓｅｄｄｕｅｔｏｔｈｅｉｒｓｐｅｃｉａｌｅｌｅｃｔｒｉｃｓｔｒｕｃ ｔｕｒｅｓａｎｄｖａｒｉｅｔｉｅｓｏｆｂｉｏｌｏｇｉｃａｌａｃｔｉｖｉｔｙ .ＩｎＣｈｉｎａ ,ＲＥＥｓａｓｆｅｒｔｉｌｉｚｅｒａｄｄｉｔｉｖｅｓｉｎａｇｒｉｃｕｌ ｔｕｒｅｈａｖｅｂｅｅｎｅｘｔｅｎｓｉｖｅｌｙｕｓｅｄ .ＮｕｍｅｒｏｕｓｆｉｅｌｄｅｘｐｅｒｉｍｅｎｔｓａｎｄｐｏｔｓｔｕｄｉｅｓｓｕｇｇｅｓｔｔｈａｔＲＥＥｆｅｒｔｉｌｉｚｅｒａｐｐｌｉｃａｔｉ…     

Numerical and Experimental Investigation on Heat Propagation through a Composite Sinter Bed with Non-uniform Voidage. Part 1 : Mathematical Model and Its Experimental Verification.

The present study discusses mechanisms of heat transfer through sinter beds of the MEBIOS process and offers its comprehensive mathematical model. The MEBIOS process, the concept of which has been proposed earlier by the authors, allows using both coarse and fine particles of iron ores in the same sinter bed. The study includes two parts. The first part describes the model content and the results of its experimental verification. The model accounts for coal combustion, limestone decomposition, moisture evaporation/condensation, melting/solidifying of solid phases. Good agreement was obtained between the model predictions and experimental data. Typical numerical results of the sintering process and the key parameters influencing the process efficiency will be discussed in the second part of the study.     

… and physiological psychology.

Comments on the importance of studying many species in physiological psychology (PHP), if it is to be devoted to an understanding of how behavior is related to biological structures and processes in all organisms, in response to G. Gottlieb's (see record 1976-21254-001) claim that a one-species (PHP) is adequate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)