66 resultados para Alpha and beta liquid scintil. spectroscopy (0.2 µm cellulose nitrate filtered)


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In order to investigate the possible effects of the ecological environment on photosynthetic activity and the major light harvesting complex, the oxygen evolution rates and composition of phycobilisome from marine red alga Porphyra yezoensis Ueda and freshwater red alga Compsopogon coeruleus (Balbis) Montagne, which could grow and reproduce under salinity up to 35 ppt, were studied. The results showed that the oxygen evolution rate of P. yezoensis in seawater was significantly higher than that of C. coeruleus in freshwater, and P. yezoensis tolerated inorganic ions at a relatively higher concentration than C. coeruleus. Moreover, the phycoerythrin (PE) of P yezoensis was R-phycoerythrin containing alpha, beta, and gamma subunits comprised phycoerythrobilin and phycourobilin. In contrast, the PE from C. coeruleus consisted of alpha, beta, and gamma subunits comprised only phycoerythrobilin but not phycourobilin, suggesting that the PE from C. coeruleus was of a new type.

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Al2O3/SiO2 films have been prepared by electron-beam evaporation as ultraviolet (UV) antireflection coatings on 4H-SiC substrates and annealed at different temperatures. The films were characterized by reflection spectra, ellipsometer system, atomic force microscopy (AFM), X-ray diffraction (XRD) and Xray photoelectron spectroscopy (XPS), respectively. As the annealing temperature increased, the minimum reflectance of the films moved to the shorter wavelength for the variation of refractive indices and the reduction of film thicknesses. The surface grains appeared to get larger in size and the root mean square (RMS) roughness of the annealed films increased with the annealing temperature but was less than that of the as-deposited. The Al2O3/SiO2 films maintained amorphous in microstructure with the increase of the temperature. Meanwhile, the transition and diffusion in film component were found in XPS measurement. These results provided the important references for Al2O3/SiO2 films annealed at reasonable temperatures and prepared as fine anti-reflection coatings on 4H-SiC-based UV optoelectronic devices. (c) 2008 Elsevier B.V. All rights reserved.

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为了重建东亚季风区域2.5MaB.P.前后植被和气候变化的历史,更好地了解低纬度地区植被变化及其对全球变化的响应,本研究选择了南海南部ODP1143站深海沉积物中的孢粉样品进行研究。通过高分辨率(7ka)的孢粉样品的分析研究,建立起3.0~2.0MaB.P.时段南海深海沉积孢粉组合序列,系统建立了这一时段植被演替序列。在此基础上,重点研究了2.5MaB.P.前后气候变化在南海周边地区植被演替中的响应,为探索和揭示东亚古季风及古环境演变提供了孢粉学依据。 ODP 1143站位于南沙海区,北纬9º22´,东经113º17´,深海柱状样采于水深2772m的大陆坡。本研究以生物地层学和氧同位素年代学为依据建立了年龄框架,对1143站135~95m(3.0~2.6 Ma B. P.)深海沉积中的孢粉样品进行了分析,建立了3.0~2.0MaB.P.时段南海深海沉积孢粉组合序列。孢粉样品处理方法主要是用盐酸去掉钙质和氢氟酸浸泡溶解硅质后,再用筛子将样品在超声波发生器中震荡过滤。孢粉的鉴定和统计在光学透视显微镜下完成。研究结果表明: 1、孢粉谱的主要特征是沉积率变化显著。与3.0~2.6 Ma B. P. 相比,2.6~2.0 Ma B. P.各类型花粉及孢子沉积率均有显著提高。该结果表明2.6 Ma B. P.南海海平面有显著下降,可与北半球冰盖形成、东亚季风增强相对应。 2、2.6 Ma B. P.以来,各类型孢粉沉积率变化与深海氧同位素分期相对应,代表了多次冰期-间冰期旋回。该结果表明南海海平面曾有多次上升和下降。 3、频谱分析结果表明,3.0~2.0 Ma B. P.存在0.1 Ma(偏心率)和46.9ka(斜率)的周期。

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The distribution of microcystins (MCs) in various tissues of Wistar rats was studied under laboratory conditions. Rats were injected intravenously (i.v.) with extracted MCs at a dose of 80 mu g MC-LRequivalent/kg body weight. MCs concentrations in various tissues were detected at 1, 2. 4, 6, 12 and 24 h post-injection using liquid chromatography-mass spectrometry (LC-MS). The highest concentration of MCs was found in kidney (0.034-0.295 mu g/g dry weight), followed by lung (0.007-0.067 mu g/g dry weight), stomach (0.010-0.058 mu g/g dry weight) and liver (0.003-0.052 mu g/g dry weight). The maximum MCs content in the whole body of rat, 2.9% of the injected dose, was observed at 2 h post-injection. MCs concentration was higher in kidney than in liver during the experiment, and two peaks of MCs concentration (at 2 and 24 h, respectively) were observed in kidney, indicating that MCs can be excreted directly via kidney of rat. Though heart, intestine, spleen, brain, gonad and stomach contained less than 0.2% of injected MCs during the whole experiment stage, the presence of MCs in these tissues represents potential damage to them. (c) 2008 Elsevier Ltd. All Fights reserved.

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Natural resistance associated macrophage protein (Nramp) controls partially innate resistance to intracellular parasites. Its function is to enhance the ability of macrophages to kill pathogens. However, little is known about the structure and function of Nramp in lower vertebrates such as teleosts. We have recently isolated a cDNA encoding Nramp from Japanese flounder (Paratichthys olivaceus). The full-length cDNA of the Nramp is 3066 bp in length, including 224 bp 5' terminal UTR, 1662 bp encoding region and 1180 bp 3' terminal UTR. The 1662-nt open reading frame was found to code for a protein with 554 amino acid residues. Comparison of amino acid sequence indicated that Japanese flounder Nramp consists of 12 transmembrane (TM) domains. A consensus transport motif (CTM) containing 20 residues was observed between transmembrane domains 8 and 9. The deduced amino acid sequence of Japanese flounder had 77.30%, 82.71%, 82.67%, 79.64%, 80.72%, 90.97%, 91.16%, 60.14%, 71.48%, 61.69%, 72.37% identity with that of rainbow trout Nramp alpha and beta, channel catfish Nramp, fathead minnow Nramp, common carp Nramp, striped sea bass Nramp, red sea bream Nramp, mouse Nramp 1 and 2, human Nramp 1 and 2, respectively. RT-PCR indicated that Nramp transcripts were highly abundant in spleen, head kidney, abundant in intestine, liver and gill, and less abundant in heart. The level of Nramp mRNA in embryos gradually increases during embryogenesis from 4 h (8 cell stage) to 80 h (hatched stage) after fertilization. (c) 2005 Elsevier Ltd. All rights reserved.

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The conduction-band offset Delta E-C has been determined for a molecular beam epitaxy grown GaAs/In0.2Ga0.8As single quantum-well structure, by measuring the capacitance-voltage (C - V) profiling, taking into account a correction for the interface charge density, and the capacitance transient resulting from thermal emission of carriers from the quantum well, respectively. We found that Delta E-C = 0.227 eV, corresponding to about 89% Delta E-g, from the C - V profiling; and Delta E-C = 0.229eV, corresponding to about 89.9% Delta E-g, from the deep-level transient spectroscopy (DLTS) technique. The results suggest that the conduction-band discontinuity Delta E-C obtained from the C-V profiling is in good agreement with that obtained from the DLTS technique. (C) 1998 American Institute of Physics.

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Baryon magnetic moments of p, n, Sigma(+), Sigma(-), Xi(0), Xi(-) and the beta decay ratios (G(A)/G(V)) of n -> p, Sigma(-) -> n and Xi(0) -> Sigma(+) are calculated in a colored quark cluster model. With SU(3) breaking, the model gives a good fit to the experimental values of those baryon magnetic moments and the beta decay ratios. Our results show that the orbital motion has a significant contribution to the spin and magnetic moments of those baryons and the strange component. in nucleon is small.

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In the present work specimens of mono-crystalline silicon carbide (4H polytype) were irradiated to three successively increasing ion fluences ranging from 7.2 x 10(14) to 6.0 x 10(16) ions/cm(2) (corresponding to the peak displacement damage of 1, 4 and 13 dpa) with Ne and Xe ions respectively with the energy of 2.3 MeV/amu. The irradiated specimens were subsequently annealed at temperatures of 1173 and 1273 K. Defect structure was investigated with transmission electron microscopy (TEM) using a cross-sectional specimen preparation technique. The typical microstructures of the annealed specimens irradiated with Ne or Xe ions to high fluences are characterized by small gas bubbles in high concentration in the peak damage region and black dots and dislocation loops (located in the basal plane) in a shallower and broader depth region. Larger dislocation loops were observed in the Xe-ion irradiated specimen than in the Ne-ion irradiated specimen at the same peak damage level. The enhanced formation of dislocation loops in the case of Xe-ion irradiation is understandable by assuming stronger inclination of heavier inert-gas atoms to occupy substitute site in the peak damage region.

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A facile and efficient one-pot synthesis of polysubstituted pyridin-2(1H)-ones from a variety of beta-oxo amides under Vilsmeier conditions is described, and a mechanism involving sequential halogenation, formylation and intramolecular nucleophilic cyclization is proposed

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We investigate the dewetting behavior of the bilayer of air/PS/PMMA/silanized Si wafer and find the two competing dewetting pathways in the dewetting process. The upper layer dewets on the lower layer (dewetting pathway 1, the liquid-liquid dewetting) and the two layers rupture on the solid substrate (dewetting pathway 2, the liquid-solid dewetting). To the two competing dewetting pathways, the process of forming holes and the process of hole growth, influence their competing relation. In the process of forming holes, the time of forming holes is a main factor that influences their competing relation. During the process of hole growth, the dewetting velocity is a main factor that influences their competing relation.

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A simple and rapid method for morphine detection has been described based on electrochemical pretreatment of glassy carbon electrode (GCE) which was treated by anodic oxidation at 1.75 V, following potential cycling in the potential range from 0 V to 1.0 V vs. Ag vertical bar AgCl reference electrode. The sensitivity for morphine detection was improved greatly and the detection limit was 0.2 mu M. The reproducibility of the voltammetric measurements was usually less than 3% RSD for six replicate measurements. Moreover, this method could readily discriminate morphine from codeine. And an electrochemical detection of morphine in spiked urine sample was succeeded with satisfactory results.

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Monodisperse, core-shell-structured SiO2@NaGd(WO4)(2):Eu3+ particles were prepared by the sol-gel method. The samples were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence (PL), and low-voltage cathodoluminescence (CL) as well as time-resolved PL spectra and lifetimes. PL and CL study revealed that the core-shell-structured SiO2@NaGd (WO4)(2):Eu3+ particles show strong red emission dominated by the D-5(0) - F-7(2) transition of Eu3+ at 614 nm with a lifetime of 0.74 ms. The PL and CL emission intensity can be tuned by the coating number of NaGd(WO4)(2):Eu3+ phosphor layers on SiO2 and by accelerating voltage and the filament current, respectively.