41 research outputs found
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Plasma-sprayed coatings for fusion reactor applications
A series of plasma-sprayed coatings has been given a preliminary evaluation to assess the potential of this class of materials in fusion reactor applications. TiC, TiB/sub 2/, Be and VBe/sub 12/ coatings on copper and stainless steel were tested for coating adherence, ion erosion resistance and susceptability to arc erosion. The coatings, in general, display a good resistance to thermal shock failure. The TiC and TiB/sub 2/ coatings exhibit favorable ion erosion characteristics and the resistance of the coatings to arc erosion was, in general, superior to that of stainless steel
Cell cycle and aging, morphogenesis, and response to stimuli genes are individualized biomarkers of glioblastoma progression and survival
<p>Abstract</p> <p>Background</p> <p>Glioblastoma is a complex multifactorial disorder that has swift and devastating consequences. Few genes have been consistently identified as prognostic biomarkers of glioblastoma survival. The goal of this study was to identify general and clinical-dependent biomarker genes and biological processes of three complementary events: lifetime, overall and progression-free glioblastoma survival.</p> <p>Methods</p> <p>A novel analytical strategy was developed to identify general associations between the biomarkers and glioblastoma, and associations that depend on cohort groups, such as race, gender, and therapy. Gene network inference, cross-validation and functional analyses further supported the identified biomarkers.</p> <p>Results</p> <p>A total of 61, 47 and 60 gene expression profiles were significantly associated with lifetime, overall, and progression-free survival, respectively. The vast majority of these genes have been previously reported to be associated with glioblastoma (35, 24, and 35 genes, respectively) or with other cancers (10, 19, and 15 genes, respectively) and the rest (16, 4, and 10 genes, respectively) are novel associations. <it>Pik3r1</it>, <it>E2f3, Akr1c3</it>, <it>Csf1</it>, <it>Jag2</it>, <it>Plcg1</it>, <it>Rpl37a</it>, <it>Sod2</it>, <it>Topors</it>, <it>Hras</it>, <it>Mdm2, Camk2g</it>, <it>Fstl1</it>, <it>Il13ra1</it>, <it>Mtap </it>and <it>Tp53 </it>were associated with multiple survival events.</p> <p>Most genes (from 90 to 96%) were associated with survival in a general or cohort-independent manner and thus the same trend is observed across all clinical levels studied. The most extreme associations between profiles and survival were observed for <it>Syne1</it>, <it>Pdcd4</it>, <it>Ighg1</it>, <it>Tgfa</it>, <it>Pla2g7</it>, and <it>Paics</it>. Several genes were found to have a cohort-dependent association with survival and these associations are the basis for individualized prognostic and gene-based therapies. <it>C2</it>, <it>Egfr</it>, <it>Prkcb</it>, <it>Igf2bp3</it>, and <it>Gdf10 </it>had gender-dependent associations; <it>Sox10</it>, <it>Rps20</it>, <it>Rab31</it>, and <it>Vav3 </it>had race-dependent associations; <it>Chi3l1</it>, <it>Prkcb</it>, <it>Polr2d</it>, and <it>Apool </it>had therapy-dependent associations. Biological processes associated glioblastoma survival included morphogenesis, cell cycle, aging, response to stimuli, and programmed cell death.</p> <p>Conclusions</p> <p>Known biomarkers of glioblastoma survival were confirmed, and new general and clinical-dependent gene profiles were uncovered. The comparison of biomarkers across glioblastoma phases and functional analyses offered insights into the role of genes. These findings support the development of more accurate and personalized prognostic tools and gene-based therapies that improve the survival and quality of life of individuals afflicted by glioblastoma multiforme.</p
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The extratropical upper troposphere and lower stratosphere
The extratropical upper troposphere and lower stratosphere (Ex-UTLS) is a transition region between the stratosphere and the troposphere. The Ex-UTLS includes the tropopause, a strong static stability gradient and dynamic barrier to transport. The barrier is reflected in tracer profiles. This region exhibits complex dynamical, radiative, and chemical characteristics that place stringent spatial and temporal requirements on observing and modeling systems. The Ex-UTLS couples the stratosphere to the troposphere through chemical constituent transport (of, e.g., ozone), by dynamically linking the stratospheric circulation with tropospheric wave patterns, and via radiative processes tied to optically thick clouds and clear-sky gradients of radiatively active gases. A comprehensive picture of the Ex-UTLS is presented that brings together different definitions of the tropopause, focusing on observed dynamical and chemical structure and their coupling. This integral view recognizes that thermal gradients and dynamic barriers are necessarily linked, that these barriers inhibit mixing and give rise to specific trace gas distributions, and that there are radiative feedbacks that help maintain this structure. The impacts of 21st century anthropogenic changes to the atmosphere due to ozone recovery and climate change will be felt in the Ex-UTLS, and recent simulations of these effects are summarized and placed in context
Boron coatings on graphite for fusion reactor applications
This study is an experimental investigation of boron coatings on graphite and the preliminary determination of some of their physical and nuclear related properties. The boron was obtained by the decomposition of diborane in argon at 500/sup 0/C and one atm. Adhesion to the graphite (POCO AXF-5Q) was good if a slightly abraded surface was provided. The boron was pseudo-amorphous, had high purity with no visually observable porosity and the fractured surface showed no growth features. It was very hard (VHN/sub 25/ = 2400 kg/mm/sup 2/) and had good resistance to hydrogen ion erosion and arcing. It may, therefore, be a suitable candidate for first wall and limiter coatings in tokamak fusion reactors
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Initial testing of coated limiters in ISX-B
Low-Z coatings on graphite substrates have been developed for testing as limiters in the Impurity Study Experiment (ISX-B) tokamak. Laboratory and tokamak testings have been accomplished. The laboratory tests included thermal shock experiments by means of pulsed e-beam irradiation, arcing experiments, and hydrogen and xenon ion erosion experiments. The tokamak testing consisted of ohmically heated plasma exposures with energy depositions up to 10 kJ/discharge on the limiters. The coatings, applied by chemical vapor deposition, consisted of TiB/sub 2/ and TiC deposited on POCO graphite substrates
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Development and laboratory testing of low Z refractory coatings for fusion reactor limiters
A materials development program for low Z (Z < 24) coated tokamak limiters is described. A variety of refractory coatings applied by chemical vapor deposition, plasma spraying and chemical conversion to graphite and copper substrates have been evaluated. The results of laboratory testing for low energy hydrogen ion erosion, arc erosion and thermal fatigue by pulsed electron beam heating are reported. The 250 V hydrogen ion erosion data, analysed in terms of the effect of plasma radiation losses from resultant contaminants, indicates near equivalence of the very low Z (B and B/sub 4/C e.g.) and the moderate Z (e.g., TiB/sub 2/) coatings. Thermal fatigue testing has identified several candidate materials which can survice 1000, 3 kJ /cm/sup 2/ pulses of electron beam heating. The development of prototype limiters of TiB/sub 2/, TiC and B coated graphite for testing in the ORNL ISX-B tokamak is described
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Operational history of stainless steel, TiC, TiB/sub 2/, and boron limiters in the ISX-B Tokamak
For the past eighteen months a variety of low-z coatings have been tested for service as limiters in both ohmically-heated and beam-heated ISX-B plasmas. To date TiC, TiB/sub 2/, and B coatings on a graphite substrate have been examined. The history of these materials in ISX-B is reviewed with particular emphasis and compared with previously used stainless steel limiters on machine performance