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排序方式: 共有343条查询结果,搜索用时 31 毫秒
1.
Kedong Xia Shuoshuo Yu Yunling Li Huijuan Han Lingyao Duan Zhenyu Hou Xiao Liu 《Journal of the European Ceramic Society》2021,41(4):2375-2385
In this study, C/SiOC and C/SiO2 composites were prepared by using carbonaceous microspheres with different surface functional groups. Carbonaceous microspheres based on hydrothermal reaction of glucose contains hydroxyl group, while the surface carboxyl group increases after NaOH etching. The hydroxyl group increases the oxygen-enriched structural units of SiOC ceramics, and the C spheres are closely enwrapped in SiOC matrix after pyrolysis at 900 °C. However, the interfacial reaction of surface carboxyl with Si–OH results in the formation of cristobalite SiO2, and C spheres are not only encased inside the SiOC matrix, but also dispersed outside of SiOC ceramics. After removal of C via calcination at 500 °C for 5 h, C/SiOC and C/SiO2 composites are transformed into amorphous SiO2 and cristobalite SiO2, respectively. The thermogravimetric analysis indicates the oxidation resistance of SiOC is superior to that of C and SiO2. 相似文献
2.
为了促进油茶产业的发展以及开发新的蛋白胶黏剂,以油茶籽蛋白为原料(蛋白质含量36%,纤维含量15%),采用碱(NaOH)对其进行降解处理,并与交联剂混合作为胶黏剂应用于胶合板的热压中。考察了NaOH加量对油茶籽蛋白水解度和降解液甲醛反应能力、黏度和胶黏剂胶合性能的影响,并对降解前后油茶籽蛋白进行了红外表征。结果表明:NaOH可使油茶籽蛋白有效降解,并产生活性基团和活性点;随着NaOH加量的增加,油茶籽蛋白水解度和降解液甲醛反应能力呈先急剧增加后缓慢增加的趋势,降解液黏度呈先增加后急剧减小再缓慢减小的趋势;所制备的胶合板的湿状胶合强度总体呈先增加后减小的变化趋势。NaOH加量为7%时,油茶籽蛋白降解液具有较高的反应活性、较大的内聚强度、较好的施胶性能和优良的胶合性能。 相似文献
3.
为研究NaOH溶液处理对鸡肉品质的影响,选取市售黄羽肉鸡60 只,随机分为对照组和NaOH溶液浸泡组(pH 9组、pH 11组和pH 13组,每组15 只),并对其进行肉品质和微生物指标检测。结果表明:NaOH溶液浸泡可以显著增加鸡肉的质量和腐败指标(总挥发性盐基氮、组胺、酪胺和亚精胺)含量(P<0.05),显著降低剪切力、风味营养物质(蛋白质、肌内脂肪、肌苷酸和氨基酸)含量(P<0.05);低pH值NaOH溶液浸泡的鸡肉,其菌落总数和大肠菌群数明显升高,而高pH值NaOH溶液具有一定的杀菌效果。 相似文献
4.
以玉米秸秆为原料,通过碳化-磺化法制备了碳基固体酸(CSA),采用XRD、FTIR、XPS、SEM、阳离子交换与返滴定法等手段对其结构形貌进行表征,并考察了制备条件对固体酸表面活性基团含量与催化活性的影响。以NaOH/尿素冻融预处理后的纤维素为底物,研究了CSA催化纤维素水解糖化的效果与条件。结果表明:NaOH/尿素冻融预处理能够有效辅助固体酸催化纤维素水解,在350℃碳化2h、100℃磺化5h条件下制备的CSA催化性能最好,其酸量达3.94mmol/g,其中磺酸基、羧基、酚羟基含量分别为1.09mmol/g、1.36mmol/g、1.49mmol/g。在m(CSA)∶m(纤维素)=3∶1、水解温度200℃、水解时间为0.5h的条件下,纤维素水解还原糖得率与转化率分别为47.1%和63%。CSA循环利用3次催化活性下降不大。本研究可为废弃生物质原料制备的固体酸催化纤维素水解转化利用提供科学参考。 相似文献
5.
Tribocorrosion behavior and degradation mechanism of 316L stainless steel (SS) in alkaline solution were studied. The SS was worn in 0.1 mol/L NaOH solution with different potentials to investigate the synergism between wear and corrosion. The SS showed larger material loss at a cathodic potential of - 0.8 V and lower material loss at anodic potential when compared with that under pure wear condition. This was inverse when compared with that in other corrosive media, such as H2SO4 and NaCl solutions. The formation of tribo-films with different properties at different potentials played decisive role in the degradation process. Tribo-films were formed at cathodic potential (- 0.8 V) and anodic potentials (0 and 0.4 V). The tribo-film formed at - 0.8 V had the highest O content and was very brittle. It resulted in the easily peeling off of the film and then the acceleration of material degradation. By contrast, the tribo-films formed at anodic potentials were more complete and the O content was much lower. Such kind of ductile tribo-films could protect the SS from wear. The locally high concentration of OH- produced in the reduction reaction of oxygen at - 0.8 V could react with the tribo-film which consist of nano-particles (NPs) with high chemical activity and finally led to deep oxidation and embrittlement of the film. The passivation of the NPs at the anodic potentials could inhibit the oxidation of tribo-film to maintain its ductility. 相似文献
6.
7.
为了对比氢氧化钠/尿素法(NU法)和硫酸法在测定烟草中木质素含量(质量分数,下同)的差异性,采用NU法和硫酸法测定广东、四川、湖南、云南和贵州5个产区烟梗和烟叶的木质素含量,分析了两种方法在预处理过程的干扰物质去除率及酸解过程木质素含量和结构变化。结果表明:1与硫酸法相比,NU法预处理对干扰物质的去除率更高。2NU法采用稀酸酸解,减少了烟草中木质素的降解;选择在325 nm处测定酸溶木质素(ASL)的紫外吸光度,避免了蛋白质和糠醛对ASL的干扰,提高了烟草木质素测定结果的准确度和重现性。3与硫酸法相比,NU法分离得到的酸不溶木质素(AIL)的氧化程度低、结构变化小,因而更能反映烟草木质素的结构特征。NU法比硫酸法更加适用于烟草木质素的含量测定。 相似文献
8.
9.
Jiang Li Fenghui Sun Xiangzhen Li Zhiying Yan Yuexiang Yuan XiaoFeng Liu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(12):1687-1693
BACKGROUND: This work investigated the monokaryogenesis of dikaryon strains of Trametes hirsuta by protoplasts regeneration for extracellular ligninolytic enzyme production. Saccharification of corn straw was enhanced by alkali pretreatment combining crude ligninolytic enzymes. RESULTS: Effectiveness of alkali pretreatment of corn straw on delignification was evaluated under different concentrations. About 45% lignin loss was achieved at the concentration of 1.5% NaOH. In addition, 79.0% sugar yield was obtained after combined pretreatment with NaOH and crude ligninolytic enzyme produced from monokaryotic strains of Trametes hirsuta. Scanning electron microscopy (SEM) images showed that the porosity and surface area increased significantly after combined pretreatment. The FTIR spectra indicated that great intensity changes occurred at the 890–900 cm?1, 1509–1513 cm?1 and 1595 cm?1 bands. CONCLUSION: The proposed combined pretreatment removes lignin and enhances saccharification of corn straw effectively. Copyright © 2012 Society of Chemical Industry 相似文献
10.
以玉米秸秆纤维和稻草秸秆纤维作为脱硫石膏的增强材料,研究不同纤维掺量、碱处理浓度对农作物秸秆纤维增强脱硫石膏墙体材料物理力学性能、耐水性能和保温性能的影响.结果表明:玉米秸秆纤维掺量为3%时试样强度最高,抗折和抗压强度分别达到6.4 MPa和14.9 MPa,而掺稻草秸秆纤维的分别为6.2 MPa和14.3 MPa.农作物秸秆纤维经碱溶液处理后,与脱硫石膏之间胶结能力增强,5%碱溶液处理试样的抗折强度和抗压强度分别可提高到7.1 MPa和16.4 MPa.纤维能够阻止水分在墙体材料内部孔隙中迁移,提高其耐水性能,墙体材料吸水率最低为21.3%,软化系数最高可达0.56.掺加农作物秸秆纤维能够增加脱硫石膏墙体材料孔隙率,故降低其导热系数,导热系数最低可降至0.121 W/(m·K). 相似文献