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Thick (200 to 500 [micro]m) epitaxial GaAs layers have been grown on two inch wafers by using a chemical reaction technique which is inexpensive, is nonpolluting, and allows very high growth rates. X-ray detectors made of p/i/n structures have been realized using nonintentionally doped layers grown on [n.sup.+] GaAs substrates, with the [p.sup.+] layer at the surface obtained by ion implantation. These detectors have been validated by current and capacitance-voltage measurements, photocurrent induced by X-ray irradiation, and energy resolution measurements. The data obtained demonstrate that these detectors exhibit similar performances as those obtained previously with conventional epigrowth techniques. Under standard conditions of medical examination (anode voltage of 60 kV, current of 75 mA, and distance of 70 cm), up to 1[0.sup.13] charges per second per [mm.sup.2] can be collected. The observed response time is apparently limited by the decay of the X-ray pulse. Index Terms--Epitaxy, GaAs, X-ray detector.

OBJECTIVE: To explore whether plasmacytoma variant translocation 1 (PVT1) could regulate glioblastoma multiforme (GBM) progression via microRNA-1301-3p (miR-1301- 3p) and transmembrane BAX inhibitor motif containing 6 (TMBIM6) axis. MATERIALS AND METHODS: Expression patterns of PVT1 and RMBIM6 in GBM patients were analyzed using GEPIA, an online gene expression analysis tool. Levels of PVT1 in GBM cells and normal cells were analyzed with quantitative real-time PCR method. Cell Counting Kit-8 (CCK- 8), transwell invasion assay, and flow cytometry assay were applied to detect cell viability and apoptosis. Connections of PVT1 or TMBIM6 with miR-1301-3p were validated with bioinformatic tool and luciferase activity reporter assay. RESULTS: PVT1 was significantly expressed in GBM tissues and cells. PVT1 promotes GBM cell proliferation and invasion but inhibits apoptosis in vitro. TMBIM6 was significantly expressed in GBM tissues. The knockdown of TMBIM6 reversed the stimulation effects of PVT1 on GBM cell malignancy behaviors with miR- 1301-3p as a bridge. CONCLUSIONS: Collectively, we showed PVT1 elevated TMBIM6 expression mediated by miR-1301-3p and thus to promote GBM progression. [ABSTRACT FROM AUTHOR]

Citrus trees of cv. Huangguogan, 8-, 30-, and 280-year-old (8s, 30s, and 280s, respectively), were used to explore the photosynthesis and related enzyme activity. In spring shoot leaves, net photosynthetic rate (PN) of the 280s was significantly lower than that of the 30s and 8s, but it was opposite in summer shoot leaves. PN of the summer shoots was higher than that of the spring shoots. PN was significantly positively correlated with stomatal conductance, intercellular CO2 concentration, and transpiration rate, but was negatively correlated with maximum photochemical quantum yield of PSII photochemistry. The effect of age on variable fluorescence/minimal fluorescence was similar to that of minimal fluorescence, variable fluorescence, maximal fluorescence yield of the dark-adapted state. Fruits of the 280s had significantly lower sugar components than those of the 8s and 30s. Results showed that fruits of the 8s and 30s actively accumulated photosynthesis products, which was verified by the higher PN in the spring shoots, lower acidic invertase and neutral invertase activities, and higher sucrose phosphate synthase than that of the 280s. [ABSTRACT FROM AUTHOR]

The variations of the optical and electrical characteristics of a vertical cavity surface emitting laser based on GaAs quantum wells have been monitored versus irradiation with 1 MeV electrons. The results are understood by the introduction of nonradiative recombination centers in the wells whose characteristics, capture cross section for minority carriers times their introduction rate, can be determined. A similar study performed for proton irradiation shows that the results can be explained in the same way when the introduction rate of the defects is replaced by the proton energy loss into atomic collisions. These results allow us to deduce the equivalence between electron and proton irradiations: A flux of 1 proton cm-2 which loses an energy Enℓ (eV) into atomic collisions is equivalent to a fluence of about 9×10-2 Enℓ cm-2, 1 MeV electrons. [ABSTRACT FROM AUTHOR]

Pot experiments were conducted to determine the effects of nitrogen (N) fertilization rate on the photosynthetic efficiency of 'Huangguogan' (Citrus reticulata × Citrus sinensis). We observed that plant growth increased with increasing N. Maximum values for parameters evaluated were recorded for an N addition rate of 120 g per year. Leaf chlorophyll content was positively correlated with the leaf N content. The relative reduction in photosynthetic rate (PN) at high N (150 and 180 g) correlated with the parallel decreases in the leaf N content. Rubisco activity was positively correlated with the initial slope of the PN/Ci response curve.indicating that N supplement improved photosynthesis by enhancing carboxylation and CO2 diffusion, photosynthetic capacity increased with N supply up to 120 g. Thereafter, the rate of increase declined with any further increase in N supply. These results provide a reference for a rational application of nitrogen fertilizer in orchards of 'Huangguogan'. [ABSTRACT FROM AUTHOR]

We prepare planar chiral composites samples containing a random distribution of helixes of different parameters. The influence of the helix parameters on the reflectance of microwave energy by chiral composites is studied. The helix parameters include the helix diameter, the pitch, and the gauge diameter. The reflectance of the microwave by metal backed chiral samples is calculated from the complex permittivity, complex permeability, and complex chirality parameter measured with ordinary microwave circular waveguide measurement system in the frequency range of 8.5-11.5 GHz. The results show that the helix diameter, the pitch, and the gauge diameter have remarkable influence on the reflectance of microwave energy by chiral composites. There exist optimal helix parameters in order to obtain the lowest reflectance. Index Terms--Chiral composites, helix parameters, reflectance.