Control of Switching Characteristics of Silicon-based Semiconductor Diode Using High Energy Linear Accelerator

This paper reports control of switching characteristics of silicon-based semiconductor diode using electron beam produced using linear accelerator. Conventionally, p-n junction chips of diode are exposed to gamma rays from a radioactive source or electron beam from a microtron, depending upon the required level of correction. High energy linear accelerators featuring simultaneous exposure of multiple chips are recent advancements in radiation technology. The paper presents the results of the radiation process using a 10 MeV linear accelerator as applied in industrial manufacturing of a high voltage diode (2600 V). The achieved values of reverse recovery time were found to be within the design limits. The suitability of the new process was verified by constructing the trade-off curve between the switching and conduction parameters of the diode for the complete range using large number of experimental samples. The paper summarizes the advantages of the new process over the conventional methods specifically with reference to industrial requirements. The developed process has been successfully implemented in semiconductor manufacturing. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3099

Investigations on the rôle of organic matter in plant nutrition Part VI. Effect of injecting Minute quantities of certain forms of organic matter on plant growth and reproduction

(1) Injection of minute quantities of certain organic extracts into mature sunflower plants led to not only better growth but also greatly increased flowering and seeding. The best results were obtained in the case of plants receiving extract of yeast or farmyard manure: the total yield of flower and seed was nearly tripled and the ratio of seed to the rest of the plant nearly doubled as compared with the untreated (control) plants. Dried blood was comparatively ineffective. Injection into tender plants did not lead to any significant improvement in yield. (2) Comparative trials with inorganic salts which were fed directly to pot-or plot-cultured French beans or barley did not lead to any marked improvement, more satisfactory results being obtained by applying the same salts (though in larger quantities) to the soil. In the latter case, the beneficial effects could be traced to increased assimilation and better general development rather than to any alteration in the ratio of seed (pod or grain) to the rest of the plant. (3) The practical significance of the above and other observations has been discussed

Glucosylceramide synthase upregulates MDR1 expression in the regulation of cancer drug resistance through cSrc and β-catenin signaling

<p>Abstract</p> <p>Background</p> <p>Drug resistance is the outcome of multiple-gene interactions in cancer cells under stress of anticancer agents. <it>MDR1 </it>overexpression is most commonly detected in drug-resistant cancers and accompanied with other gene alterations including enhanced glucosylceramide synthase (GCS). <it>MDR1 </it>encodes for P-glycoprotein that extrudes anticancer drugs. Polymorphisms of <it>MDR1 </it>disrupt the effects of P-glycoprotein antagonists and limit the success of drug resistance reversal in clinical trials. GCS converts ceramide to glucosylceramide, reducing the impact of ceramide-induced apoptosis and increasing glycosphingolipid (GSL) synthesis. Understanding the molecular mechanisms underlying <it>MDR1 </it>overexpression and how it interacts with GCS may find effective approaches to reverse drug resistance.</p> <p>Results</p> <p><it>MDR1 </it>and <it>GCS </it>were coincidently overexpressed in drug-resistant breast, ovary, cervical and colon cancer cells; silencing <it>GCS </it>using a novel mixed-backbone oligonucleotide (MBO-asGCS) sensitized these four drug-resistant cell lines to doxorubicin. This sensitization was correlated with the decreased <it>MDR1 </it>expression and the increased doxorubicin accumulation. Doxorubicin treatment induced GCS and <it>MDR1 </it>expression in tumors, but MBO-asGCS treatment eliminated "in-vivo" growth of drug-resistant tumor (NCI/ADR-RES). MBO-asGCS suppressed the expression of <it>MDR1 </it>with GCS and sensitized NCI/ADR-RES tumor to doxorubicin. The expression of P-glycoprotein and the function of its drug efflux of tumors were decreased by 4 and 8 times after MBO-asGCS treatment, even though this treatment did not have a significant effect on P-glycoprotein in normal small intestine. GCS transient transfection induced <it>MDR1 </it>overexpression and increased P-glycoprotein efflux in dose-dependent fashion in OVCAR-8 cancer cells. GSL profiling, silencing of globotriaosylceramide synthase and assessment of signaling pathway indicated that GCS transfection significantly increased globo series GSLs (globotriaosylceramide Gb3, globotetraosylceramide Gb4) on GSL-enriched microdomain (GEM), activated cSrc kinase, decreased β-catenin phosphorylation, and increased nuclear β-catenin. These consequently increased <it>MDR1 </it>promoter activation and its expression. Conversely, MBO-asGCS treatments decreased globo series GSLs (Gb3, Gb4), cSrc kinase and nuclear β-catenin, and suppressed <it>MDR-1 </it>expression in dose-dependent pattern.</p> <p>Conclusion</p> <p>This study demonstrates, for the first time, that GCS upregulates <it>MDR1 </it>expression modulating drug resistance of cancer. GSLs, in particular globo series GSLs mediate gene expression of <it>MDR1 </it>through cSrc and β-catenin signaling pathway.</p

Achieving One‐Step Surface Coating of Highly Hydrophilic Poly(Carboxybetaine Methacrylate) Polymers on Hydrophobic and Hydrophilic Surfaces

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108623/1/admi201400071.pd

Mechanistic Elucidation of the Arylation of Non-Spectator N-Heterocyclic Carbenes at Copper Using a Combined Experimental and Computational Approach

CuI(NHC)Br complexes (NHC = N-heterocyclic carbene) undergo a direct reaction with iodobenzene to give 2-arylated benzimidazolium products. The nature of the N-substituent on the NHC ligand influences the reactivity of the CuI(NHC)Br complex toward arylation. N-Benzyl or N-phenyl substituents facilitate arylation, whereas N-mesityl substituents hinder arylation. Density functional theory calculations show that an oxidative addition/reductive elimination pathway involving CuIII species is energetically feasible. A less hindered CuI(NHC)Br complex with N-benzyl groups is susceptible to oxidation reactions to give 1,3-dibenzylbenzimidazolium cations containing a CuIBr anion (various polymorphs). The results described herein are of relevance to C–H functionalization of (benz)azoles

Bioheterojunction Effect on Fluorescence Origin and Efficiency Improvement of Firefly Chromophores

We propose the heterojunction effect in the analysis of the fluorescence mechanism of the firefly chromophore. Following this analysis, and with respect to the HOMO-LUMO gap alignment between the chromophore's functional fragments, three main heterojunction types (I, II, and I*) are identified. Time-dependent density-functional theory optical absorption calculations for the firefly chromophore show that the strongest excitation appears in the deprotonated anion state of the keto form. This can be explained by its high HOMO-LUMO overlap due to strong bio-heterojunction confinement. It is also found that the nitrogen atom in the thiazolyl rings, due to its larger electronegativity, plays a key role in the emission process, its importance growing when HOMO and LUMO overlap at its location. This principle is applied to enhance the chromophore's fluorescence efficiency and to guide the functionalization of molecular optoelectronic devices.Comment: 7 pages, 6 figure