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排序方式: 共有388条查询结果,搜索用时 15 毫秒
41.
Daisuke Yasokawa Satomi Murata Yumiko Iwahashi Emiko Kitagawa Katsuyuki Kishi Yukihiro Okumura Hitoshi Iwahashi 《Journal of Bioscience and Bioengineering》2010,109(5):479-486
Zinc pyrithione has been used in anti-dandruff shampoos and in anti-fouling paint on ships. However, little is known of its mode of action. We characterized the effects of sub-lethal concentrations of zinc pyrithione (Zpt) on Saccharomyces cerevisiae using DNA microarrays. The majority of the strongly upregulated genes are related to iron transport, and many of the strongly downregulated genes are related to the biosynthesis of cytochrome (heme). These data suggest that Zpt induces severe iron starvation. To confirm the DNA microarray data, we supplemented cultures containing Zpt with iron, and the growth of the yeast was restored significantly. From these results, we propose that the principal toxicity of zinc pyrithione arises from iron starvation. 相似文献
42.
本文主要研究竹子和桉木两种原料的MWL、LCC及LCC-AcOH,利用13C-NMR,31P-NMR及红外光谱分别表征其结构,并分析比较两种原料的木素样品的结构不同之处。结果表明:桉木和竹子的MWL及LCC-AcOH的木素结构以愈创木基型为主,LCC的木素结构以紫丁香基型为主;桉木和竹子的MWL的侧链结构以β-β和β-O-4结构为主;LCC中包含的碳水化合物主要是α-木糖,β-木糖,α-葡萄糖,β-葡萄糖,α-半乳糖,α-甘露糖和β-甘露糖;LCC-AcOH中包含的碳水化合物主要是木糖,α-葡萄糖,β-葡萄糖,α-木糖,β-木糖。其不同点就在于竹子MWL的木素结构中所包含的5-5结构,肉桂醛和肉桂醇要比桉木多,而桉木MWL侧链中包含的β-O-4结构以及β-1和α-O-4结构比竹子略多。两种原料的LCC-AcOH中桉木含有的愈创木基和紫丁香基要比竹子多,并且桉木LCC-AcOH的碳水化合物的组成部分还包括α-甘露糖和α-半乳糖。 相似文献
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In this work, polysaccharide nanocrystals—rodlike cellulose whiskers (CWs)—were surface‐grafted with polycaprolactone (PCL) via microwave‐assisted ring‐opening polymerization, and filaceous cellulose whisker‐graft‐polycaprolactone (CW‐g‐PCL) nanoparticles were produced. Moreover, the resultant nanoparticles were incorporated into poly(lactic acid) (PLA) as a matrix, and they showed superior function for enhancing the mechanical performance of PLA‐based materials in comparison with platelet‐like nanoparticles of starch nanocrystal‐graft‐PCL. The optimal loading level of CW‐g‐PCL was 8 wt %, and this resulted in simultaneous enhancements of the strength and elongation of approximately 1.9‐ and 10.7‐fold, respectively, over those of the neat PLA material. In this case, the rigid CW nanoparticles contributed to the endurance of higher stress, whereas the grafted PCL chains improved the association between the PLA matrix and the CW‐g‐PCL filler and hence facilitated the transfer of stress to the rigid CW nanoparticles. Furthermore, such a fully biodegradable PLA‐based nanocomposite shows great potential for environmentally friendly materials because of its high mechanical performance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
44.
β-O-4木素模型物的合成与鉴定 总被引:1,自引:0,他引:1
通过多步骤合成了β-O-4木素模型物,并利用红外光谱和核磁共振谱等手段分析和确认了合成过程的中间产物和目标产物的化学结构,用凝胶渗透色谱法测定了目标产物的相对分子质量。实验结果表明,以二甲基甲酰胺为溶剂,以氯化亚铜为催化剂,可简化紫丁香酮的合成反应条件;在紫丁香酮合成后处理过程中,可采用冰水处理和乙酸乙酯萃取的方法。 相似文献
45.
《Fuel Processing Technology》2004,85(1):31-42
Coal–water slurry (CWS) holds promise to offer a long-term alternative to fuel oil, and also it is being conceived as an attractive fuel for power generation industry in India. The essential requirements of the CWS technology, viz., the additive package, concentration of additives, particle size distribution (PSD) of coal, solids loading, methodology for CWS formulation and its rheological properties, have been discussed and reported here. The effect of the two newly developed anionic additives in the formulation of CWS has been studied. The basic parameters were established taking beneficiated Ledo coal samples with 9.7% ash content. Ball milling of the coal samples in a wet grinding process could produce particle size distributions most suited for highly loaded CWS. Coal loadings to the extent of 70% in the CWS have been achieved using a concentration of 0.8 wt.% (on coal charge) of the naphthalene-based additive referred to as ‘P’. Using 0.9 wt.% of the naphthalene-toluene-based additive denoted as ‘R’, a coal loading of 69% has been achieved. The viscosities of the slurries were found to be below 1000 mPa s. The shelf lives of slurries were found to be 22 and 20 days with the use of additives P and R, respectively, in the CWS formulation. The two additives functioned well in CWS formulation with Sirka coal having relatively higher ash content (14.4%). Using the specified concentration of the additives P and R, the solid loadings of 67% and 65%, respectively, could be obtained under the established parameters. The lower values of solids loading from Sirka coal than that from Ledo coal in CWS formulation may be attributed to the higher percentages of oxygen-containing functional groups (OOH and OCOOH), ash content and higher O/C ratio of Sirka coal. 相似文献
46.
47.
《Biomass & bioenergy》2002,22(4):295-304
We studied the production of furfural by acid hydrolysis of olive stones, which in Spain are an abundant lignocellulosic residue derived from the production of olive oil. We focused on the hydrolysis in dilute sulfuric acid (0.05 to ), at high temperature (220–240°C), and short reaction times, of a few minutes at the most. The experimental study was performed in a tubing-bomb reactor system that approximately reproduces the temperature profiles obtained in a continuous tubular reactor. We obtained maximum furfural yields ranging from 50% to 65% of the potential depending on acid concentration and temperature. 相似文献
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Natural fiber reinforced composites have attracted interest due to their numerous advantages such as biodegradability, dermal non-toxicity and with promising mechanical strength. The desire to mitigate climate change due to greenhouse gas emissions, biodegradable resins are explored as the best forms of polymers for composites apart from their synthetic counterparts which are non-renewable. In this study biodegradable bark cloth reinforced green epoxy composites are developed with view of application to automotive instrument panels. The optimum curing temperature of green epoxy was shown to be 120 °C. The static properties showed a tensile strength of 33 MPa and flexural strength of 207 MPa. The dynamic mechanical properties, frequency sweep showed excellent fiber-matrix bonding of the alkali treated fabric with the green epoxy polymer with glass transition temperature in the range of 160 °C–180 °C. Treatment of the fabric with alkali positively influenced the mechanical properties of the fabric reinforced biocomposites. 相似文献