Persistent photo-conductance and photoquenching of selectively doped Al0.3Ga0.7As GaAs/heterojunctions

The dependence on photon energy of the persistent photoconductivity (PPC) in selectively doped high mobility Al_0.3Ga_0.7As—GaAs heterostructures has been measured at temperatures below 80 K. A decrease in conductivity due to light exposure at one wavelength after exposure to light at another wavelength — photo-quenching — is also found. It is concluded that deep centers in GaAs and AlGaAs other than the DX center in AlGaAs are mainly responsible for PPC.     

Social information processing and cardiac predictors of adolescent antisocial behavior.

The relations among social information processing (SIP), cardiac activity, and antisocial behavior were investigated in adolescents over a 3-year period (from ages 16 to 18) in a community sample of 585 (48% female, 17% African American) participants. Antisocial behavior was assessed in all 3 years. Cardiac and SIP measures were collected between the first and second behavioral assessments. Cardiac measures assessed resting heart rate (RHR) and heart rate reactivity (HRR) as participants imagined themselves being victimized in hypothetical provocation situations portrayed via video vignettes. The findings were moderated by gender and supported a multiprocess model in which antisocial behavior is a function of trait-like low RHR (for male individuals only) and deviant SIP. In addition, deviant SIP mediated the effects of elevated HRR reactivity and elevated RHR on antisocial behavior (for male and female participants). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of poly(glycolide-co-D,L-lactide)/poly(D,L-lactide) microspheres for controlled release of GM-CSF

PURPOSE: This study describes the preparation and characterization of a controlled release formulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) encapsulated in poly(glycolide-co-D,L-lactide) (PLGA) and poly(D,L-lactide) (PLA) microspheres. METHODS: GM-CSF was encapsulated in PLGA/PLA microspheres by a novel silicone oil based phase separation process. Several different blends of PLGA and low molecular weight PLA were used to prepare the microspheres. The microspheres and the encapsulated GM-CSF were extensively characterized both in vitro and in vivo. RESULTS: Steady release of GM-CSF was achieved over a period of about one week without significant "burst" of protein from the microspheres. Analysis of microsphere degradation kinetics by gel permeation chromatography (GPC) indicated that low molecular weight PLA enhanced the degradation of the PLGA and thereby affected release kinetics. GM-CSF released from the microspheres was found to be biologically active and physically intact by bioassay and chromatographic analysis. Analysis of serum from mice receiving huGM-CSF indicated that the GM-CSF was biologically active and that a concentration of greater than 10 ng/mL was maintained for a period lasting at least nine days. MuGM-CSF was not detected following in vivo administration of muGM-CSF microspheres. The tissues of mice receiving muGM-CSF microspheres were characterized by infiltration of neutrophils, and macrophages which were in significant excess of those found in mice administered with placebo controls (i.e. microspheres without GM-CSF). CONCLUSIONS: This study demonstrates the influence of formulation parameters on the encapsulation of GM-CSF in PLGA/PLA microspheres and its controlled release in biologically active form. The intense local tissue reaction in mice to muGM-CSF microspheres demonstrates the importance of the mode of delivery on the pharmacologic activity of GM-CSF.     

Behaviour of Urethane Adhesives on Rubber Surfaces

The paper presents the results of chemical investigations into some of the bonding problems of the footwear industry and pays particular attention to the importance of the substrate surfaces.

The importance of the presence of metal soaps on rubber surfaces and their detrimental effect on adhesion is pointed out together with the concomitant beneficial effects of solvent soap dispersing treatments on subsequent adhesion.

The special needs of the footwear industry for a single adhesive system capable of adhering strongly to a wide range of substrates led to the requirement of improving the bond of urethane adhesives to rubber surfaces. The role of free isocyanates in promoting this bond is outlined.

The practical advantages of halogenating rubber surfaces in conferring excellent adhesion properties on moulded rubber surfaces when used with solvent urethane adhesives are pointed out. The observed phenomena associated with halogenation are discussed qualitatively in relation to proposed theories of adhesion.     

Development,growth, and adhesion of Al2O3 on platinum-aluminum alloys

The development, growth, and adhesion of -Al₂O₃ scales on platinum-aluminum alloys containing between 0.5 and 6 wt.% aluminum have been studied at temperatures in the interval between 1000 and 1450° C. The morphologies and microstructures of the -Al₂O₃ scales were found to be influenced by the temperature, oxygen pressure, and the microstructures of the alloys. The oxidation rates of the alloys appeared to be controlled by transport of oxygen along grain boundaries in the -Al₂O₃ scales. The -Al₂O₃ scales adhered to the platinum-aluminum substrates even after extensive periods of cyclic oxidation. The good adhesion of the -Al₂O₃ may result from mechanical keying of the oxide to the alloys due to the development of irregular oxide-alloy interfaces.This work was supported by the U.S. Army Research Office, Durham, under Contract Number DAHCO 4 73 C 0021.     

The interpersonal consequences of inflated self-esteem in an inpatient psychiatric youth sample.

This study tested R. F. Baumeister, L. Smart, and J. M. Boden's (1996) theory of inflated self-esteem with an inpatient psychiatric youth sample. Participants were assessed on their self-reported self-esteem, self-reported interpersonal problems, and peer rejection (measured by evaluations from 3 or 4 peers). Consistent with the hypotheses, those with low self-esteem reported the most interpersonal problems, followed consecutively by the moderate self-esteem group and then the high self-esteem group, who reported the fewest interpersonal problems. Also in line with the hypotheses, those with low and high self-esteem were rejected by their peers when compared with the moderate self-esteem group. Thus, the high self-esteem group was rejected by their peers but did not themselves report interpersonal problems. These findings provide further support for Baumeister et al.'s theory and generalize the theory to a clinical setting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigation of dissolution inhibitors for electrochemical mechanical planarization of copper using beta-alanine as a complexing agent

Dissolution inhibition capabilities of benzotriazole (BTAH) and ammonium dodecyl sulfate (ADS) are investigated, in combination with β-alanine, as a complexing agent for applications in electrochemical mechanical planarization (ECMP) of copper. Cu electrodissolution is induced by linear sweep voltammetry (LSV), and Fourier transform electrochemical impedance spectroscopy (FT-EIS) is combined with LSV to examine the relative roles of the electrolyte additives in governing the surface reactions of Cu under voltage activated conditions of ECMP. The experiments focus on the electrochemical rather than mechanical component of ECMP, and are designed to probe both the individual and combined effects of BTAH and ADS on Cu electro-dissolution in the absence of abrasion.