218,179 research outputs found
Electrical Treeing Characteristics in XLPE Power Cable Insulation in Frequency Range between 20 and 500 Hz
No full textElectrical treeing is one of the main reasons for long term degradation of polymeric materials used in high voltage ac applications. In this paper we report on an investigation of electrical tree growth characteristics in XLPE samples from a commercial XLPE power cable. Electrical trees have been grown over a frequency range from 20 Hz to 500 Hz and images of trees were taken using CCD camera without interrupting the application of voltage. The fractal dimension of electric tree is obtained using a simple box-counting technique. Contrary to our expectation it has been found that the fractal dimension prior to the breakdown shows no significant change when frequency of the applied voltage increases. Instead, the frequency accelerates tree growth rate and reduces the time to breakdown. A new approach for investigating the frequency effect on trees has been devised. In addition to looking into the fractal analysis of tree as a whole, regions of growth are being sectioned to reveal differences in terms of growth rate, accumulated damage and fractal dimension
Application of virus-induced gene silencing technology in gene functional validation of orchids in Orchid biotechnology
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Photo‐Induced Ruthenium‐Catalyzed Double Remote C(sp(2))−H / C(sp(3))−H Functionalizations by Radical Relay
No full textDistal C(sp(2))−H and C(sp(3))−H functionalizations have recently emerged as step‐economical tools for molecular synthesis. However, while the C(sp(2))−C(sp(3)) construction is of fundamental importance, its formation through double remote C(sp(2))−H/C(sp(3))−H activation has proven elusive. By merging the ruthenium‐catalyzed meta‐C(sp(2))−H functionalization with an aliphatic hydrogen atom transfer (HAT) process, we, herein, describe the catalyzed twofold remote C(sp(2))−H/C(sp(3))−H functionalizations via photo‐induced ruthenium‐mediated radical relay. Thus, meta‐C(sp(2))−H arene bonds and remote C(sp(3))−H alkane bonds were activated by a single catalyst in a single operation. This process was accomplished at room temperature by visible light—notably without exogenous photocatalysts. Experimental and computational theory studies uncovered a manifold comprising ortho‐C−H activation, single‐electron‐transfer (SET), 1,n‐HAT (n=5–7) and σ‐activation by means of a single ruthenium(II) catalyst
Overexpression of Cyclin D1 and C-Myc Gene Products in Human Primary Epithelial Ovarian Cancer
No full textCyclin D1 and c-Myc are key participants in the cell-cycle pathway, in which aberrancies have been associated with malignant transformation. To date, data on the relationship of expression of these proteins and histologic subtype of epithelial ovarian cancer are still scarce and discordant. Immunohistochemical analysis was performed on 12 normal ovaries and 47 cases of serous, mucinous, endometrioid, and clear cell ovarian carcinomas. No abnormal expression of cyclin D1 or c-Myc was demonstrated in any of the 12 normal ovarian specimens. However, compared to normal ovarian tissues, overexpression of cyclin D1 and c-Myc was observed in 42.6% (20/47) and 65.9% (31/47) of tumors examined, respectively. There was no significant difference of overexpression of cyclin D1 or c-Myc gene products between these four histologic subtypes of ovarian adenocarcinomas. This study shows that cyclin D1 and c-Myc are frequently overexpressed in epithelial ovarian carcinomas, but they are not correlated with a particular histologic subtype. Although our preliminary results need to be validated in a larger number of tumors, the abnormal expression of cyclin D 1 and c-Myc in epithelial ovarian cancer reaffirms the notion that they are crucial components in the pathway of tumorigenesis and deserve further study
Photoinduced C—C Bond Cleavage and Oxidation of Cycloketoxime Esters
No full textA novel structural reorganization of cycloketoxime esters beyond the traditional Beckmann rearrangement process has been established to build cyano-containing ketones in the presence of photocatalyst. This novel transformation is remarkable with selective C—C bond cleavage and an oxidation process enabled by DMSO used as the solvent, oxidant, and oxygen source avoiding acid, base and toxic cyanide salts as the cyano source. Further applications in late-stage modification of complex and chiral molecules have also been reported
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