Infrared Reflection Spectroscopy and Effective Medium Modeling of As-Anodized and Oxidized Porous Silicon Carbide

We present a study of the infrared reflectance of porous silicon carbide (PSC) formed by the electrochemical dissolution of silicon carbide substrates of both 6H and 4H polytypes. The reflectance from n-PSC, both as-anodized and passivated, is reported for the first time. The passivation of PSC has been accomplished using a short thermal oxidation. Fourier transform infrared (FTIR) reflectance spectroscopy is employed ex situ after different stages of the thermal oxidation process. The characteristics of the reststrahlen band normally observed in bulk SiC are altered by anodization; further changes in the reflectance spectra occur following oxidation for different periods of time. An effective medium theory model that includes air, SiC and SiO₂ as component materials is shown to characterize the observed changes in the reflectance spectra after different stages of PSC oxidation.     

Benzofuran-terminated infrared dyes and their electro-optic properties in guest-host polymers

Molecular first hyperpolarizabilities and dipole moments of new benzo-fused dyes were calculated using quantum-mechanical density functional theory (DFT). Two new infrared dyes were synthesized: each one was terminated with 6-diethylaminobenzo[b]furan on one end, and with CF₃-tricyanodihydrofuran on the other end. The midsection of the π-electron framework for one dye contained a morpholino-substituted cyclohexenylene unit, and the other dye contained an ethoxysiloxane-substituted cyclohexenylene unit. Guest-host films were deposited on ITO-glass and contact poled. Electro-optic coefficients (r₃₃) were measured at a wavelength of 1550 nm by the attenuated total reflection method and by a modified simple Teng-Man reflection method. The measured values of r₃₃ were compared with values estimated from a well-known model that employs the molecular properties of the dyes and the film poling parameters. Thermal stability and electronic absorption spectra of the dyes were measured.     

Entwicklungszüge in der amerikanischen Sperrholzindustrie

Ohne Zusammenfassung

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Tendencies in the American plywood industry

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H. Gebhardt, H. v. Grudzinski u. H. Matz: Vergleich zwischen der europ?ischen und der amerikanischen Sperrholzindustrie, Holz als Roh- u. Werkstoff Bd.9 (1951) S. 190/193.—Dieselben: Herstellungsmethoden in amerikanischen Sperrholzfabriken. Holz als Roh- u. Werkstoff Bd.9 (1951)S. 273/278.—Dieselben: Erzeugnisse der nordamerikanischen Sperrholzindustrie. Holz als Roh- u. Werkstoff Bd.9 (1961) S. 348/351.—Dieselben: Folgerungen aus einer kritischen Betrachtung der Arbeitsmethoden in der amerikanischen Sperr-Roh- und Werkstoff Bd.9 (1951) S. 391/395.     

Deduction Graphs with Universal Quantification

Deduction Graphs are meant to generalise both Gentzen-Prawitz style natural deductions and Fitch style flag deductions. They have the structure of acyclic directed graphs with boxes. In [Herman Geuvers and Iris Loeb. Natural Deduction via Graphs: Formal Definition and Computation Rules. Mathematical Structures in Computer Science (Special Issue on Theory and Applications of Term Graph Rewriting), Volume 17(03):485–526, 2007.] we have investigated the deduction graphs for minimal proposition logic. This paper studies the extension with first-order universal quantification, showing the robustness of the concept of deduction graphs.     

Photoluminescence and electroreflectance studies of modulation-doped pseudomorphic AlGaAs/InGaAs/GaAs quantum wells

In this study, we describe the correlations between the photoluminescence (PL) spectra and electrical properties of pseudomorphic modulation-doped AlGaAs/InGaAs/GaAs quantum wells (MDQWs) grown by molecular beam epitaxy. In MDQWs, the presence of a large sheet carrier density contributes significantly to the PL linewidth. At low temperatures (4.2 K), free carrier induced broadening of the PL linewidth is influenced by the material quality of the structure. At higher temperatures (77 K), differences in the material quality do not affect the linewidth significantly, and under these conditions the PL linewidth is a good measure of the sheet carrier density. The ratio of the 77 K to 4.2 K PL linewidths provides useful information about the crystalline quality of the MDQW structures as illustrated by the correlation with 77 K Hall mobility data and a simple model. We present results of Electron Beam Electroreflectance (EBER) to characterize MDQWs and undoped quantum wells in the AlGaAs/InGaAs/GaAs material system. Several transitions have been observed and fitted to excitonic Lorentzian lineshapes, providing accurate estimates of transition energy and broadening parameter at temperatures of 96 K and 300 K.     

Cryo preparation of isolated rabbit pancreatic islets

A Flotronic silver membrane has been used as a vehicle to process, via freeze substitution, collagenase-derived rabbit pancreatic islets. The procedure provides: (1) a simple, inexpensive method for handling larger numbers of tightly clustered islet aggregates; (2) a metal surface for rapid heat transfer from specimen to cryogen resulting in an increased circumferential zone of fine structural preservation; (3) the elimination of possible artifacts associated with impact or rotation of biological specimens against a cooled, highly polished metal block; (4) superior preservation of structural components not usually observed by conventional modes of fixation; (5) retention of metabolic components which may subsequently be available for immunocytochemical or X-ray energy dispersive procedures.     

A Meta-Analytic Review of Stopping Performance in Attention-Deficit/Hyperactivity Disorder: Deficient Inhibitory Motor Control?

This review discusses whether deficient inhibitory motor control is the core deficit of attention-deficit/hyperactivity disorder (ADHD). Inhibitory motor control is commonly assessed using the stop-signal paradigm. Since the last meta-analysis that was performed, 33 new studies have appeared. The current meta-analysis revealed a significant difference between ADHD patients and matched controls in stop latency (stop-signal reaction time) in both children and adults. Basic reaction time was significantly longer in children with ADHD, but not in adults, and there was a significant interaction between the elongation of the latency to stop and to respond in adults, but not in children. Deficient inhibitory motor control may be less crucial in children than in adults with ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vibrational spectroscopy and periodic DFT studies of LaMg2PdH7: A material with two types of hydride

The need for a safe, reliable and cheap method for hydrogen transportation has prompted an intense effort in the synthesis of novel hydrides. To direct the search for better materials, it is essential to understand the bonding present in these systems. A newly synthesized material is LaMg₂PdH₇ which is best formulated as {La³⁺}{Mg²⁺}₂{[PdH₄]⁴⁻}{H⁻}₃. Thus hydrogen is formally present both as a free hydride ion and also as a covalently bound ligand. The combination of inelastic neutron scattering (INS), infrared and Raman spectroscopies and periodic density functional theory (DFT) has been used to characterise the material. We find that the material is less ionic than Ba₂[PdH₄], which also contains [PdH₄]⁴⁻. The charges carried by both the coordinating and free hydrides are similar which hints at a degree of covalency in the interactions between the interstitial hydrides and the lanthanum and magnesium ions.     

Research in industrial and organizational psychology from 1963 to 2007: Changes, choices, and trends.

The authors conducted a content analysis of all articles published in the Journal of Applied Psychology and Personnel Psychology from January 1963 to May 2007 (N = 5,780) to identify the relative attention devoted to each of 15 broad topical areas and 50 more specific subareas in the field of industrial and organizational (I-O) psychology. Results revealed that (a) some areas have become more (or less) popular over time, whereas others have not changed much, and (b) there are some lagged relationships between important societal issues that involve people and work settings (i.e., human-capital trends) and I-O psychology research that addresses them. Also, much I-O psychology research does not address human-capital trends. Extrapolating results from the past 45 years to the next decade suggests that the field of I-O psychology is not likely to become more visible or more relevant to society at large or to achieve the lofty goals it has set for itself unless researchers, practitioners, universities, and professional organizations implement significant changes. In the aggregate, the changes address the broad challenge of how to narrow the academic-practitioner divide. (PsycINFO Database Record (c) 2010 APA, all rights reserved)