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| 2. |
- Ding, Ling, et al.
(författare)
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Effects of brominated flame retardants and brominated dioxins on steroidogenesis in H295R human adrenocortical carcinoma cell line
- 2007
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Ingår i: Environmental Toxicology and Chemistry. - : Society of Environmental Toxicology and Chemistry (SETAC). - 0730-7268 .- 1552-8618. ; 26:4, s. 764-772
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Tidskriftsartikel (refereegranskat)abstract
- Brominated flame retardants (BFRs) and brominated dioxins are emerging persistent organic pollutants that are ubiquitous in the environment and can be accumulated by wildlife and humans. These chemicals can disturb endocrine function. Recent studies have demonstrated that one of the mechanisms of endocrine disruption by chemicals is modulation of steroidogenic gene expression or enzyme activities. In this study, an in vitro assay based on the H295R human adrenocortical carcinoma cell line, which possesses most key genes or enzymes involved in steroidogenesis, was used to examine the effects of five bromophenols, two polybrominated biphenyls (PBBs 77 and 169), 2,3,7,8-tetrabromodibenzo-p-dioxin, and 2,3,7,8-tetrabromodibenzofuran on the expression of 10 key steroidogenic genes. The H295R cells were exposed to various BFR concentrations for 48 h, and the expression of specific genes - cytochrome P450 (CYP11A, CYP11B2, CYP17, CYP19, and CYP21), 3β- hydroxysteroid dehydrogenase (3βHSD2), 17β-hydroxysteroid dehydrogenase (17βHSD1 and 17βHSD4), steroidogenic acute regulatory protein (StAR), and 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) - was quantitatively measured using real-time polymerase chain reaction. Cell viability was not affected at the doses tested. Most of the genes were either up- or down-regulated, to some extent, by BFR exposure. Among the genes tested, 3βHSD2 was the most markedly up-regulated, with a range of magnitude from 1.6- to 20-fold. The results demonstrate that bromophenol, bromobiphenyls, and bromodibenzo-p-dioxin/furan are able to modulate steroidogenic gene expression, which may lead to endocrine disruption.
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| 3. |
- Elsik, Christine G., et al.
(författare)
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The Genome Sequence of Taurine Cattle : A Window to Ruminant Biology and Evolution
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 324:5926, s. 522-528
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Tidskriftsartikel (refereegranskat)abstract
- To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.
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| 4. |
- Huang, Yue, et al.
(författare)
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Memory Effect of Metal-Oxide-Silicon Capacitors with Self-Assembly Double-Layer Au Nanocrystals Embedded in Atomic-Layer-Deposited HfO2 Dielectric
- 2009
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 26:10
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Tidskriftsartikel (refereegranskat)abstract
- We report the chemical self-assembly growth of Au nanocrystals on atomic-layer-deposited HfO2 films aminosilanized by (3-Aminopropyl)-trimethoxysilane aforehand for memory applications. The resulting Au nanocrystals show a density of about 4 x 10(11) cm(-2) and a diameter range of 5-8 nm. The metal-oxide-silicon capacitor with double-layer Au nanocrystals embedded in HfO2 dielectric exhibits a large C - V hysteresis window of 11.9 V for +/- 11 V gate voltage sweeps at 1 MHz, a flat-band voltage shift of 1.5 V after the electrical stress under 7 V for 1 ms, a leakage current density of 2.9 x 10(-8) A/cm(-2) at 9 V and room temperature. Compared to single-layer Au nanocrystals, the double-layer Au nanocrystals increase the hysteresis window significantly, and the underlying mechanism is thus discussed.
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| 5. |
- Lian, Ke-Yan, et al.
(författare)
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Density-functional studies of plasmons in small metal clusters
- 2009
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 130:17
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Tidskriftsartikel (refereegranskat)abstract
- We study the formation of plasmon modes of small gold clusters by modeling the excitation spectra. The shape change of the longitudinal mode as a function of cluster size is studied using time-dependent Kohn-Sham theory and Gaussian basis sets. The presence of d electrons in gold atoms affect the plasmon formation process, resulting in a high excitation energy for transverse mode and a complicated spectra profile in general. The transverse mode can still be identified with the help of a frozen-orbital approximation.
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| 6. |
- Liao, Zhong-Wei, et al.
(författare)
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Robust Low Voltage Program-Erasable Cobalt-Nanocrystal Memory Capacitors with Multistacked Al2O3/HfO2/Al2O3 Tunnel Barrier
- 2009
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 26:8, s. 087303-
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Tidskriftsartikel (refereegranskat)abstract
- An atomic-layer-deposited Al2O3/HfO2/Al2O3 (A/H/A) tunnel barrier is investigated for Co nanocrystal memory capacitors. Compared to a single Al2O3 tunnel barrier, the A/H/A barrier can significantly increase the hysteresis window, i. e., an increase by 9V for +/- 12V sweep range. This is attributed to a marked decrease in the energy barriers of charge injections for the A/H/A tunnel barrier. Further, the Co-nanocrystal memory capacitor with the A/H/A tunnel barrier exhibits a memory window as large as 4.1V for 100 mu s program/erase at a low voltage of +/- 7V, which is due to fast charge injection rates, i. e., about 2.4 x 10(16) cm(-2) s(-1) for electrons and 1.9 x 10(16) cm(-2) s(-1) for holes.
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| 7. |
- Wang, Weilong, 1978-, et al.
(författare)
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Enhanced thermal conductivity and thermal performance of form-stable composite phase change materials by using beta-Aluminum nitride
- 2009
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 86:7-8, s. 1196-1200
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Tidskriftsartikel (refereegranskat)abstract
- beta-Aluminum nitride powder is a promising additive due to its great conductivity value, which can enhance the thermal conductivity of organic phase change materials. In this paper, a high conductivity form-stable phase change material was prepared by blending polyethylene glycol, silica gel, and P-Aluminum nitride powder. The conductivity value of the composite PCMs was determined using the Hotdisk thermal analyzer, which is based on the transient plane source technique. Experiment of heat storage and release performance was carried out to investigate heat efficiencies of TES system. The results showed that thermal conductivity of composite PCMs increased with an increase in beta-Aluminum nitride content, but the value of latent heat decreased correspondingly. There was no change on the melting temperature while different ratios of composites. The value of thermal conductivity changed from 0.3847 W m(-1) K-1 to 0.7661 W m(-1) K-1 with the increase of mass ratio of beta-Aluminum nitride from 5% to 30%. The heat storage and release rate of the composite PCMs was higher than that of pure polyethylene glycol. Crown
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| 8. |
- Wang, Weilong, 1978-, et al.
(författare)
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Preparation and thermal properties of polyethylene glycol/expanded graphite blends for energy storage
- 2009
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 86:9, s. 1479-1483
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Tidskriftsartikel (refereegranskat)abstract
- Expanded graphite is a promising heat transfer promoter due to its high conductivity, which improves the thermal conductivity of organic phase change materials. Moreover, it can also serve as supporting materials to keep the shape of the blends stable during the phase transition. After various investigation, the results showed that the maximum weight percentage of polyethylene glycol was as high as 90% in this paper without any leakage during the melting period, with the latent heat of 161.2 J g(-1) and the melting point of 61.46 degrees C. It was found that the value of the latent heat was related to the polyethylene glycol portion, increased with the increase in polyethylene glycol content. Moreover, the measured enthalpy of the composite phase change materials was proportional to the mass ratio of the polyethylene glycol component. The melting temperatures were almost the same with different ratios of composites. The conductivity of blends was improved significantly with the high value of 1.324 W m(-1) K-1 compared to the pure polyethylene glycol conductivity of 0.2985 W m(-1) K-1.
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