Simulation, modeling, and crystal growth of Cd0.9Zn0.1Te for nuclear spectrometers

High-quality, large (10 cm long and 2.5 cm diameter), nuclear spectrometer grade Cd_0.9Zn_0.1Te (CZT) single crystals have been grown by a controlled vertical Bridgman technique using in-house zone refined precursor materials (Cd, Zn, and Te). A state-of-the-art computer model, multizone adaptive scheme for transport and phase-change processes (MASTRAP), is used to model heat and mass transfer in the Bridgman growth system and to predict the stress distribution in the as-grown CZT crystal and optimize the thermal profile. The model accounts for heat transfer in the multiphase system, convection in the melt, and interface dynamics. The grown semi-insulating (SI) CZT crystals have demonstrated promising results for high-resolution room-temperature radiation detectors due to their high dark resistivity (ρ≈2.8 × 10¹¹ Θ cm), good charge-transport properties [electron and hole mobility-life-time product, μτ_e≈(2–5)×10⁻³ and μτ_h≈(3–5)×10⁻⁵ respectively, and low cost of production. Spectroscopic ellipsometry and optical transmission measurements were carried out on the grown CZT crystals using two-modulator generalized ellipsometry (2-MGE). The refractive index n and extinction coefficient k were determined by mathematically eliminating the ∼3-nm surface roughness layer. Nuclear detection measurements on the single-element CZT detectors with ²⁴¹Am and ¹³⁷Cs clearly detected 59.6 and 662 keV energies with energy resolution (FWHM) of 2.4 keV (4.0%) and 9.2 keV (1.4%), respectively.     

Sex-and age-related differences in ceramide dihexosides of primary human brain tumors

Neutral glycolipids (NGL) are promising diagnostic markers of human gliomas, but differences in NGL with age and sex have not been examined. Previous work demonstrated that ceramide dihexosides (CDH) levels in mouse kidney are age- and sex-dependent, probably due to levels of sex hormones. We quantitated CDH in 181 human gliomas and found significant differences with sex and age, particularly menopause and male puberty. This emphasizes the importance of assessing results of studies on glycolipids in disease states with respect to age and sex in order to avoid erroneous conclusions concerning the relationship of glycolipid composition with diagnosis and pathogenesis.     

Mammalian Exocrine Secretions. XII: Constituents of Interdigital Secretions of Bontebok, Damaliscus dorcas dorcas, and Blesbok, D. d. phillipsi

In addition to the nine compounds identified in the interdigital secretion of the bontebok, Damaliscus dorcas dorcas, in a previous study, 76 compounds belonging to different compound types, were identified in the interdigital secretions of the bontebok and the blesbok, D. d. phillipsi. These compounds include alkanes, alcohols, aldehydes, ketones, fatty acids, terpenoids, -lactones, an isopropyl ester, long-chain hydroxyesters, 2-substituted pyridines, phenols, steroids, and dimethylsulfone. No qualitative differences were found between secretions from the two sexes or from animals from different habitats. Although no attempt was made to correlate territorial behavior or other behavioral phenomena with the qualitative composition of interdigital secretions from individual animals, available information seems to indicate that quantitative differences probably do not have a major semiochemical function. Only two species of bacteria, Bacillus brevis and Planococcus citreus, were found in the interdigital pouches of male and female members of the two subspecies, regardless of the habitat of the animals. B. brevis synthesized, among other unidentified constituents, (Z)-3-penten-2-ol, 2-hexanone, 2-octanone, 2-nonanone, tetradecanoic acid, pentadecanoic acid, heptadecanoic acid, octadecanoic acid, (Z)-9-hexadecenoic acid, and isopropyl hexadecanoate in vitro, while P. citreus produced, among others, the -lactones dodecan-4-olide and (Z)-6-dodecen-4-olide, which is one of the major constituents of the interdigital secretions of both subspecies. Some components of the interdigital secretions are not present in the interdigital glandular tissue, and the possibility is discused that these compounds could be produced by microbiological activity in the interdigital pouch.     

Effective Sample Size in Diffuse Reflectance Near-IR Spectrometry

Two independent methods for determination of the effectively sampled mass per unit area are presented and compared. The first method combines directional-hemispherical transmittance and reflectance measurements. A three-flux approximation of the equation of radiative transfer is used, to separately determine the specific absorption and scattering coefficients of the powder material, which subsequently are used to determine the effective sample size. The second method uses a number of diffuse reflectance measurements on layers of controlled powder thickness in an empirical approach. The two methods are shown to agree well and thus confirm each other. From the determination of the effective sample size at each measured wavelength in the visible-NIR region for two different model powder materials, large differences was found, both between the two analyzed powders and between different wavelengths. As an example, the effective sample size ranges between 15 and 70 mg/cm(2) for microcrystalline cellulose and between 70 and 300 mg/cm(2) for film-coated pellets. However, the contribution to the spectral information obtained from a certain layer decreases rapidly with increasing distance from the powder surface. With both methods, the extent of contribution from various depths of a powder sample to the visible-NIR diffuse reflection signal is characterized. This information is valuable for validation of analytical applications of diffuse reflectance visible-NIR spectrometry.     

Imbalance between interstitial collagenase and tissue inhibitor of metalloproteinases 1 in synoviocytes and fibroblasts upon direct contact with stimulated T lymphocytes: involvement of membrane-associated cytokines

OBJECTIVE: To determine whether direct cell-cell contact with stimulated T lymphocytes (a) differentially modulates the production of interstitial collagenase (matrix metalloproteinase 1 [MMP-1]) and tissue inhibitor of metalloproteinases 1 (TIMP-1) on human synoviocytes and dermal fibroblasts, and (b) induces the production of prostaglandin E2 (PGE2); and to identify the membrane-associated factors on T cell surfaces involved in these mechanisms. METHODS: Dermal fibroblasts and fibroblast-like synovial cells (synoviocytes) were cultured with fixed T cells, isolated plasma membranes from T cells, interleukin-1beta (IL-1beta; 250 pg/ml), or transforming growth factor beta (TGFbeta; 5 ng/ml). Culture supernatants were assayed for the production of MMP-1, TIMP-1, and PGE2. The expression of MMP-1 and TIMP-1 messenger RNA was analyzed by Northern blot of total fibroblast RNA. RESULTS: Membranes of stimulated T cells, i.e., human peripheral blood T lymphocytes (PBTL) and the human T cell line HUT-78, induced the production of PGE2 and MMP-1 on both synoviocytes and dermal fibroblasts. TIMP-1 production was enhanced upon contact with PBTL stimulated for short periods of time (2-4 hours) but not for longer periods. Similar results were obtained with CD4+ and CD8+ synovial tissue T cell clones (TCCs), which induced the production of TIMP-1 by fibroblasts when stimulated for short (2-4 hours), but not long, periods of time. This time dependency was not observed with HUT-78 cells. The production of MMP-1 by fibroblasts and synoviocytes upon cellular contact with stimulated T cells was higher than that induced by an optimum concentration of IL-1beta, whereas the production of PGE2 was equivalent or slightly lower. Cell membrane-associated IL-1alpha and tumor necrosis factor a, but not CD69, CD40 ligand, or CD11b, were involved in the induction of MMP-1 and PGE2 production, as shown by blockade experiments using monoclonal antibodies and cytokine antagonists. CONCLUSION: Synovial tissue TCCs and PBTL stimulated for long periods of time trigger the production of PGE2 and MMP-1, but not TIMP-1, in synoviocytes and dermal fibroblasts, thus inducing an imbalance between the metalloenzyme and its inhibitor. These results demonstrate that T cells may affect fibroblast and synoviocyte functions directly (i.e., by contact activation) and indirectly (i.e., by activation of cytokine production in monocyte/macrophages, which in turn, trigger stromal cell functions). Since the production of MMPs in monocyte/macrophages is also induced upon contact with stimulated T cells, our results strongly suggest that contact of synovial cells with chronically stimulated T lymphocytes favors matrix catabolism. By analogy, this mechanism may trigger tissue destruction in vivo and, thus, may potentiate tissue destruction in chronic inflammatory diseases such as RA.     

Heavy metals in the hair of opossum from Palo Verde, Costa Rica

Levels of lead, cadmium, mercury, chromium, and manganese were measured in the hair of opossum (Didelphis virginiana) from Palo Verde, Guanacaste, Costa Rica. This area has some agriculture, but is slated for extensive water development that will increase ecosystem exposure to a variety of agricultural chemicals. Metal levels were generally not intercorrelated except for chromium and lead, chromium and cadmium, and cadmium and lead. There were significant gender differences only for lead and chromium, with the significantly smaller females having higher levels. It is suggested that hair from mammals, particularly abundant ominivores may be useful, bioindicators of environmental quality over a long time period.     

Einfluß der Holzabmessungen auf die Zugfestigkeit von Bauschnittholz

The effect of timber dimensions on tensile strength was investigated in 750 and 200 tests involving spruce and Douglas fir respectively, with dimensions ranging in thickness from 30 mm to 70 mm, in width from 50 mm to 200 mm, and in length from 150 mm to 2,500 mm. Results show tensile strength to be essentially related to knot ratio and density and to decrease with increasing length, in accordance with relationship f _t,1=f _t,0·(l ₀/l ₁)^0.1. Since specimens tend to exhibit decreasing knot ratios with increasing width, tensile strength was shown to rise with increasing width. Apart from this relationship no significant effect of width and thickness on the 5-percentiles of tensile strength, as assumed e.g. in Eurocode 5, was detected.     

Discrimination of the threat of direct versus tangential approach to the nest by incubating herring and great black-backed gulls.

Examined the ability of incubating herring (Larus argentatus) and black-backed (L. marinus) gulls to discriminate between people walking directly toward their nests and those merely walking tangentially by their nests. Study groups varied in their habitat (open vs vegetated) and previous exposure to human disturbance. Herring gulls responded when the experimenter (E) was at a greater distance from the nest if the approach was directly toward the nest with the person looking at the incubating bird, and gulls in disturbed areas responded sooner than birds in undisturbed areas. In habitats with low visibility (dense bush cover), the gulls could not see E early enough to show different responses to the 2 treatments. Black-backed gulls nested only in undisturbed areas, and only slight differences were evident in the distance at which they left the nest. However, they called more when E was approaching the nest directly. In this study, gulls habituated to the continual presence of humans by modifying their responses, but even habituated birds continued to reassess the potential danger of a nearby human and perceived subtle differences between a direct and a tangential approach. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

INHIBITION AND ACTIVATION OF BARLEY PEPTIDE HYDROLASES II. PEPTIDE HYDROLASES B AND C,AND L-LEUCYL-β-NAPHTHYLAMIDASE

Peptide hydrolase B is inhibited by DIPF and appears to be a “serine esterase” enzyme. Para-chloromercuribenzoate is also inhibitory, but it acts irreversibly and not as a mercaptide former. Dithiothreitol acts irreversibly to inhibit the enzyme and thioglycolate is a weak, reversible inhibitor. Peptide hydrolase C is also inhibited by DIPF, and no consistent indication of metal ion or sulphydryl group involvement was observed. L-leucyl-β-naphthylamidase apears to be a metalloenzyme. It is mildly inhibited by some chelating agents and is stimulated by Ni²⁺ after prior treatment with EDTA. The enzyme is moderately inhibited by PCMPS and exhibits variable responses to different sulphydryl compounds.