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The effect of the trace metals Cu, K, Na, and Ca, separately or in mixture, on fermentation time, ethanol production rate, and cell growth in the fermentation of synthetic media containing sucrose is discussed. The results are related to the range of contents found in raw materials, molasses and raisins, in order to determine their optimum concentrations for alcohol production.  相似文献   
钾助剂对硼铝酸铜催化脱氢环化性能的影响   总被引:1,自引:0,他引:1       下载免费PDF全文
通过添加不同含量的K,考察了钾助剂对硼铝酸铜催化邻乙基苯胺脱氢环化制备吲哚的影响,并通过XRD、TPD、TPR、TG对催化剂进行了表征.结果表明,K助剂的加入中和了部分催化剂强酸中心,在一定程度上降低了催化剂表面酸性,但对催化剂表面积炭没有明显改善.钾助剂的添加提高了催化剂晶粒的分散度,并且与活性组分发生协同作用,改善了催化剂的脱氢反应性能.在空速为0.1 h-1、水油摩尔比为10:1条件下,未添加K的催化剂上,邻乙基苯胺的转化率为45%左右,而添加了6.05%K的催化剂上,邻乙基苯胺的转化率提高到了60%以上.同时,钾助剂的添加延缓了铜氧化物的还原,减慢了催化剂失活的速度:未添加K的硼铝酸铜,反应80 h后,邻乙基苯胺的转化率由50%降至41.3%,而对应的修饰了6.05%K的催化剂,转化率却基本维持不变.  相似文献   
Phosphors CaYBO4:RE3+ (RE=Eu, Gd, Tb, Ce) were synthesized with the method of solid-state reaction at high temperature, and their vacuum ultraviolet (VUV)-visible luminescent properties in VUV-visible region were studied at 20 K. In CaYBO4, it is confirmed that there are two types of lattice sites that can be substituted by rare-earth ions. The host excitation and emission peaks of undoped CaYBO4 are very weak, which locate at about 175 and 350-360 nm, respectively. The existence of Gd3+ can efficiently enhance the utilization of host absorption energy and result in a strong emission line at 314 nm. In CaYBO4, Eu3+ has typical red emission with the strongest peak at 610 nm; Tb3+ shows characteristic green emission, of which the maximum emission peak is located at 542 nm. The charge transfer band of CaYBO4:Eu3+ was observed at 228 nm; the co-doping of Gd3+ and Eu3+ can obviously sensitize the red emission of Eu3+. The fluorescent spectra of CaYBO4:Ce3+ is very weak due to photoionization; the co-addition of Ce3+-Tb3+ can obviously quench the luminescence of Tb3+.  相似文献   
Non‐C5‐units terpenoids (norisoprenoids) with an acetonyl group are widely distributed in nature. However, studies on the biosynthesis of norisoprenoids are scarce. Now, the C33 norisoprenoid, (all‐E)‐farnesylfarnesylacetone, was identified from Bacillus spp. and it was elucidated for the first time that superoxide mediates the cleavage of menaquinones (vitamin K) to form norisoprenoids in saponification treatment. From in vivo experiments using gene‐disrupted Bacillus subtilis strains targeted for enzymes responsible for menaquinone biosynthesis and for superoxide dismutase, it was suggested that the non‐enzymatic cleavage (autoxidation) of menaquinone with superoxide resulted in norisoprenoid synthesis in Bacillus cells. Furthermore, the bioactive norisoprenoids, farnesylacetone and phytone, were produced in Bacillus cells by this novel synthesis system.  相似文献   
电荷补偿对Sr2SiO4:Dy3+材料发射光谱的影响   总被引:2,自引:1,他引:1  
采用高温固相反应方法在空气中制备了Sr2SiO4:Dy3+发光材料.在365 nm紫外光激发下,测得Sr2SiO4:Dy3+材料的发射光谱为一多峰宽谱,发射峰分别位于486,575和665 nm处.研究了电荷补偿剂Li+,Na+和K+对Sr2SiO4:Dy3+材料发射光谱强度的影响,结果显示,不同电荷补偿剂下,随电荷补偿剂掺杂浓度的增大,Sr2SiO4:Dy3+材料发射光谱强度的演化趋势相同,即,Sr2SiO4:Dy3+材料发射峰强度先增大后减小,但不同电荷补偿剂下,材料发射峰强度最大处对应的补偿剂浓度不同,对应Li,Na+和K+时,浓度分别为4 mol%,3 mol%和3 mol%.同时,对研究结果进行了理论分析.  相似文献   
Chemical investigation of the sponge Ircinia formosana resulted in the isolation of seven new linear C22‐sesterterpenoids, irciformonins E–K ( 1 – 7 ) in addition to irciformonin A ( 8 ), a previously isolated furanosesterterpenoid (=a furan‐moiety‐containing sesterterpenoid) from the same species. The structures were determined by interpretation of HR‐ESI‐MS and 2D‐NMR spectra. The structure of irciformonin A ( 8 ) was revised. Compound 5 exhibited significant inhibition of peripheral blood mononuclear cell proliferation induced by phytohemaglutinin.  相似文献   
养分亏缺是作物产量和质量提升的重要限制因子。我国砖红壤植胶区钾、镁缺乏及其低的有效性长期制约天然橡胶的产、质量。以“热研7-33-97”橡胶幼苗为研究对象,利用傅里叶变换红外光谱(FTIR)对钾、镁胁迫下橡胶树叶片物质组成特征进行研究,分析不同钾、镁胁迫条件下叶片红外光谱图谱特征峰的变化及其差异,探讨钾、镁胁迫对叶片物质成分和结构的影响,以期为钾镁缺乏影响橡胶树生长与生理代谢的机理研究提供参考。结果表明:(1)缺钾条件下,1 554,1 519和1 075 cm-1处的吸收峰缺失,表明橡胶叶片中蛋白质酰胺Ⅱ带、酚类物质、碳水化合物的化学结构受到破坏,并且其他特征峰吸光度与正常处理相比均有不同程度的升高,表明缺钾造成蛋白质、碳水化合物等物质在叶片中大量积累,物质转运效率降低;(2)缺镁条件下,1 554 cm-1处吸收峰向高频方向位移了6 cm-1,说明缺镁造成蛋白质酰胺Ⅱ带的结构发生改变,同时,1 550~1 350 cm-1波数范围内吸收峰相对吸光度明显下降,说明缺镁降低了细胞壁多糖以及含油脂化合物的含量,且该波数范围内的三个吸收峰较其他吸收峰变化敏感,表明该波段可以较好地指示橡胶叶片镁营养状况;(3)钾镁同时缺乏条件下,各吸收峰的相对吸光度和强度明显减弱,1 554,1 519和1 075 cm-1处的吸收峰缺失,说明蛋白质酰胺Ⅱ带、酚类物质、碳水化合物的化学结构受到破坏,1 057 cm-1处吸收峰向高频方向位移了11 cm-1,表明橡胶叶片中果胶类多糖分子结构发生了变化。综上所述,缺钾造成橡胶叶片蛋白质、糖类物质的含量的大量积累,缺镁造成叶片细胞壁多糖和油脂化合物下降,而钾镁同时缺乏时蛋白质、脂类、糖类物质等物质含量均明显下降。研究表明,使用FTIR技术对养分缺乏下的橡胶叶片物质成分定性分析具有一定的可行性,同时可为橡胶钾、镁营养生理代谢的机制研究提供新的思路和方法。  相似文献   
利用电感耦合等离子体-原子发射光谱法(ICP-AES)测定不同采收时间(5、6、7、8月和9月)野生羌活药材中K、Na、Al 3种金属元素的含量,应用SPSS16.0分析软件对结果进行统计分析。研究结果表明,5—9月野生羌活药材中均以K元素含量最高;K和Na、Na和Al的含量呈负相关,K和Al的含量呈正相关;K元素的含量在5月到6月增加,6月到8月呈下降趋势,8月到9月急剧升高;Na元素的含量呈先上升(5—6月)后下降(6—9月)的趋势;Al元素的含量呈先降低(5—6月)再升高(6—9月)的趋势。  相似文献   
Steady-state spectroscopic studies of two ortho (-OCH3 and -OH) derivatives of methyl p-dimethylaminobenzoate have been performed. The absorption spectra of molecules under study are analyzed taking into consideration results of quantum chemical semiempirical calculations. The fluorescence spectra of these molecules possess in polar solvents two bands, i.e., the locally excited and intramolecular charge transfer (ICT) fluorescence band. Their intensity ratio as well as the fluorescence/phosphorescence intensity ratio determined at 77 K depends on the solvent polarity. Theoretical studies of the TICT phenomenon have been made in order to explain the dual emission of molecules under study. Calculated electric dipole moments of these molecules in the ground, S0, and excited, S1(LE) and S1(ICT) states, have been compared with experimentally determined data. Theoretically determined transition energies, ΔEi, oscillator strengths, fi, and electric dipole moments μS0, μS1(LE) and μS1(ICT) of the planar donor-acceptor (D/A) conformer agree with experimental data. According to Marcus theory inner- and outer-solvatation sphere reorganization energies (λout, λin) are calculated using the determined spectroscopic properties of molecules under study.  相似文献   
Completely amorphous Fe-Si layers are formed by Fe implantation into Si substrate at a dosage of 5×1015 cm−2 using a metal vapor vacuum arc (MEVVA) ion source under 80 kV extraction voltage and cryogenic temperature. After thermal annealing, β-FeSi2 precipitates are formed in Si matrix. The influence of impurities in these amorphous Fe-Si layers on the photoluminescence (PL) from β-FeSi2 precipitates is investigated. PL is found to be significantly enhanced by optimizing the impurity concentration and annealing scheme. After 60 s of rapid thermal annealing (RTA) at 900 °C, β-FeSi2 precipitates in medium boron-doped Si substrate give the strongest PL intensity without boron out-diffusion from them.  相似文献   
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