24 research outputs found

    Improvement of Switching Speed of a 600-V Nonpunch-through Insulated Gate Bipolar Transistor Using Fast Neutron Irradiation

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    AbstractFast neutron irradiation was used to improve the switching speed of a 600-V nonpunch-through insulated gate bipolar transistor. Fast neutron irradiation was carried out at 30-MeV energy in doses of 1 × 108 n/cm2, 1 × 109 n/cm2, 1 × 1010 n/cm2, and 1 × 1011 n/cm2. Electrical characteristics such as current–voltage, forward on-state voltage drop, and switching speed of the device were analyzed and compared with those prior to irradiation. The on-state voltage drop of the initial devices prior to irradiation was 2.08 V, which increased to 2.10 V, 2.20 V, 2.3 V, and 2.4 V, respectively, depending on the irradiation dose. This effect arises because of the lattice defects generated by the fast neutrons. In particular, the turnoff delay time was reduced to 92 nanoseconds, 45% of that prior to irradiation, which means there is a substantial improvement in the switching speed of the device

    Sulfur management strategies to improve partial sulfur balance with irrigated peanut production on deep sands

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    Sands have favourable physical properties for harvesting peanut, but improving S and water use efficiency on these soils remains a challenge. We studied partial S balance in irrigated peanut crops on sands of Central Vietnam to identify key factors of S fertiliser management affecting S inputs and outputs. Field trials were conducted in the spring seasons of 2015 and 2016 to determine the effects of S application rates (0, 15, 30, 45 kg ha−1) on peanut yield and partial S balance. Sulfur balances were negative (-28.3 to 5.6 kg S ha−1) at rates < 30 kg S ha−1, while at higher rates of S fertiliser application that produced maximum pod yield (30 - 45 kg S ha−1), three of four sites showed neutral to slightly positive S balance (1.5 - 5.6 kg S ha−1). The negative partial S balance decreased with increasing S rates but was mostly attributable to the large S removal in peanut shoots (9.7 - 22.3 kg S ha−1) which are used on farms for animal feed. The negative partial S balance results in depletion of soil S reserves and hence efficient recycling of S on farms is critical for sustainable crop production on sands of VN

    The effects of magnetic field on the d-density wave order in the cuprates

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    We consider the effects of a perpendicular magnetic field on the d-density wave order and conclude that if the pseudogap phase in the cuprates is due to this order, then it is highly insensitive to the magnetic field in the underdoped regime, while its sensitivity increases as the gap vanishes in the overdoped regime. This appears to be consistent with the available experiments and can be tested further in neutron scattering experiments. We also investigate the nature of the de Haas- van Alphen effect in the ordered state and discuss the possibility of observing it.Comment: 5 pages, 4 eps figures, RevTex4. Corrected a silly but important typo in the abstrac

    Cochinchinochloa (Gramineae: Bambusoideae-Bambusineae), a new bamboo genus endemic to Braian mountain, southern Vietnam

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    A clambering bamboo endemic to Braian mountain, southern Vietnam represents a new monotypic endemic genus, Cochinchinochloa H.N.Nguyen & V.T.Tran (Gramineae: Bambusoideae-Bambusinae), which is described and illustrated. Its culm nodes and the nodes of leafy branches exhibit a thick swollen patella, and in the reproductive state this taxon bears pseudospikelets having two perfect florets, with an elongated rachilla internode between the perfect florets, a rachilla extension bearing an imperfect floret at maturity, a narrowly 2-keeled palea with a distinct abaxial groove, three lodicules, six stamens, free filaments, a glabrous ovary with a long style and three stigmas, and an oblong caryopsis with a relatively thin pericarp

    Improving irrigation, potassium and sulphur use efficiency of Peanut (Arachis hypogaea) in tropical sandy soils

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    Increasing the productivity of irrigated crops on low fertility sands depends on jointly improving water and nutrient use efficiencies. The aim of this study was to investigate the hypothesis that improved water scheduling and delivery would increase K and S use efficiency of irrigated peanut crops on deep sands. Factorial experiments (irrigation management and K, S rates) were conducted on two deep sands in Binh Dinh province, South Central Coastal Vietnam (SCV). Peanut yield increased 17% in response to switching from the farmers’ irrigation practice (FI) to sprinkler irrigation scheduled according to evaporation rates (ER), combined with increasing fertilizer K and S from 50 kg K ha−1 + 20 kg S ha−1 to 75 kg K ha−1 + 30 kg S ha−1. Nutrient loss with ER relative to FI decreased by 52–64% for K and by 20–24% for S. The irrigation water use efficiency of peanut (kg pod kL−1 of water) increased by 44% under the ER approach. Integrated water and nutrient management practices substantially improved use efficiency of K and S fertiliser, achieved substantial irrigation water savings and increased profits for peanut on infertile deep sands

    Linkage isomerism in the binding of pentapeptide Ac-His(ALA)3His-NH2 to (Ethylenediamine)Palladium(II): Effect of the binding mode on peptide conformation

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    The reaction of the pentapeptide Ac-His1-Ala2-Ala3-Ala4-His5-NH2 (AcHAAAHNH2) (1) with [Pd(en)(ONO2)(2)] (en = NH2CH2CH2NH2) in either DMF-d(7) or H2O:D2O (90%:10%) gave three linkage isomers of [Pd(en)(AcHAAAHNH2)](2+) (2), 2a, 2b, and 2c, which differ only in which pair of imidazole nitrogen atoms bind to Pd. In the most abundant isomer, 2a, Pd is bound by N1 from each of the two imidazole rings. In the minor isomers 2b and 2c, Pd is bound by N1(His1) and N3(His5) and by N3(His1) and N1(His5), respectively. The reactions of [Pd(en)(ONO2)(2)] with the N-methylated peptides Ac-(N3-MeHis)Ala-Ala-Ala-(N3-MeHis)-NH2 (AcH*AAAH*NH2) (3), Ac-(N3-MeHis)-Ala-Ala-Ala-(N1-MeHis)-NH2 (AcH*AAAH(#)NH(2)) (4), and Ac(N1-MeHis)-Ala-Ala-Ala-(N3-Me-His)-NH2 (AcH(#)AAAH*NH2) (5) each gave a single species [Pd(en)(peptide)](2+) in N,Ndimethylformamide (DMF) or aqueous solution, 7, 8, and 9, respectively, with Pd bound by the two nonmethylated imidazole nitrogen atoms in each case. These complexes were analogous to 2a, 2b, and 2c, respectively. Ac-(N1-MeHis)-Ala-Ala-Ala(N1-MeHis)-NH2 (AcH(#)AAAH(#)NH(2)) (6) with [Pd(en)(ONO2)21 in DMF slowly gave a single product, [Pd(en)(AcH(#)AAAH(#)NH(2))]21 (10), in which Pd was bound by the N3 of each imidazole ring, The corresponding linkage isomer of 2 was not observed. Complex 10 was also the major product in aqueous solution, but other species were also present. All compounds were exhaustively characterized in solution by multinuclear 1D (H-1, C-13, and, with N-15-labeled ethylenediamine, N-15) and 2D (correlation spectroscopy, total correlation spectroscopy, transverse rotating-frame Overhauser effect spectroscopy (T-ROESY), heteronuclear multiplebond correlation, and heteronuclear single quantum coherence) NMR spectra, circular dichroism (CD) spectra, electrospray mass spectroscopy, and reversed-phase high-performance liquid chromatography. ROESY spectra were used to calculate the structure of 2a, which contained a single turn of a peptide alpha helix in both DMF and water, the helix being better defined in DMF The Pd(en)(2+) moiety was not used in structure calculations, but its location and coordination by one imidazole N1 from each histidine to form a 22-membered metallocycle were unambiguously established. Convergence of the structures was greatest when calculated with two hydrogen-bond constraints (Ala4 pepticle NH center dot center dot center dot OC acetyl and His5 peptide NH center dot center dot center dot OC-His1) that were indicated by the low temperature dependence of these NH chemical shifts. Vicinal HN-CH alpha coupling constants and chemical shifts of alpha-H atoms were also consistent with a helical conformation. Similar long-range ROE correlations were observed for [Pd(en)(AcH*AAAH*NH2)](2+) (7), which displayed a CD spectrum in aqueous solution that suggested the presence of some helicity. Long-range ROE correlations were not observed for 8, 9, or 10, but a combination of NMR data and CD spectroscopy was interpreted in terms of the conformational behavior of the coordinated pentapeptide. Only for the linkage isomer [Pd(en)(AcH*AAAH(#)NH(2))](2+) (8) was there evidence of a contribution from a helical conformation

    Comprehensive analysis of the cytokine-rich chromosome 5q31.1 region suggests a role for IL-4 gene variants in prostate cancer risk

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    Although inflammation is emerging as a candidate prostate cancer risk factor, the T-helper cytokine-rich [interleukins (IL)-5, 13 and 4] chromosomal region at 5q31.1 has been implicated in prostate cancer pathogenesis. In particular, IL-4 has been associated with prostate cancer progression, whereas the IL-4 -589C>T (rs2243250) promoter variant has been associated with differential gene expression. We genotyped rs2243250 and 11 tag single-nucleotide polymorphisms (SNPs) spanning 200 kb across the 5q31.1 region on 825 cases and 732 controls from the Risk Factors for Prostate Cancer Study. The minor alleles of rs2243250 and an IL-4 tagSNP rs2227284 were associated with a small increase in prostate cancer risk. Per allele odds ratios (ORs) are 1.32 [95% confidence interval (CI) 1.08-1.61, P = 0.006] and 1.26 (95% CI 1.07-1.48, P = 0.005), respectively. Although these associations were not replicated in an analysis of the Melbourne Collaborative Cohort Study, including 810 cases and 1733 controls, no clinicopathological characteristic was implicated for this divergence. Correlating rs2243250 genotypes to IL-4 gene transcript levels and circulating IL-4 plasma levels, we observe in contrast to previous reports, a non-significant trend toward the minor T-allele decreasing the likelihood of IL-4 activity. From our observed association between a low IL-4 producing promoter T-allele and prostate cancer risk, our study suggests an antitumor role for IL-4 in prostate cancer. Although we saw no association for IL-5 or IL-13 gene variants and prostate cancer risk, our findings call for further evaluation of IL-4 as a contributor to prostate cancer susceptibility. © The Author 2010. Published by Oxford University Press. All rights reserved.Articl
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