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31.
Hydrolysis of olive oil, soybean oil, mink fat, lard, palm oil, coconut oil, and a hydrogenated, hardened oil with lipase
from anAspergillus sp. has been studied. The lipase had high specific activity (60,000 U/g) and did not show any positional specificity. The
lipase proved to be a more effective catalyst than Lipolase fromA. oryzae, with an optimal activity at 37°C and pH 6.5–7.0. It was activated by Ca2+ but inactivated by organic solvents such as isopropanol and propanone. All substrates examined could be hydrolyzed to corresponding
fatty acids with this enzyme at concentrations of 5–30 U/meq with yields of 90–99% in 2–24 h. The degree of hydrolysis was
almost logarithmically linear with reaction time and occurred in two stages. The lipase was stable and could be repeatedly
recycled for hydrolysis. 相似文献
32.
In model, pot and field trials the effect of C reduced slurries and different application techniques on N losses and N immobilization were investigated. The C reduced slurries were produced by mechanical separation. Ammonia losses from surface-applied and injected cattle slurry were measured under field conditions using a wind tunnel system. Injection of slurry was the most efficient way to reduce volatilization of ammonia. After 6 days the total loss from the injected slurry was only 9% of that from surface band application. Furthermore, additional losses of N may occur through denitrification, specially after injection of slurry which may create an anaerobic environment abundant in readily oxidizable C. Therefore denitrification measurements by the acetylene inhibition technique were conducted. Until 100 days after application the loss from the injected slurry was 7.3 kg compared to 4.5 kg N ha–1 from surface band applied slurry. After injection, denitrification was only 4.1 kg N ha–1 for C reduced compared to 6.5 kg N ha–1 for normal slurry. In pot trials the ammonium-15N of normal slurry and C-reduced slurry was utilized by oats between 52 and 60%, the ammonium sulfate by 67%. The increased biomass C confirmed a greater immobilization of the NH4-N of the normal slurry resulting in a lower initial efficiency.Dedicated to Prof. Dr. A. Amberger on his 75th birthday 相似文献
33.
Lewis R. Blackburn Shi-Kuan Sun Laura J. Gardner Ewan R. Maddrell Martin C. Stennett Claire L. Corkhill Neil C. Hyatt 《Journal of the American Ceramic Society》2021,104(7):2937-2951
A series of zirconolite ceramics with composition CaZr1-xThxTi2O7 (Δx = 0.10) were reactively sintered at 1350°C for 20 h, in air (0 ≤ x ≤ 0.60) and 5% H2/N2 (0 ≤ x ≤ 0.40). A sample with composition corresponding to x = 0.20 was also produced by hot isostatic pressing (HIP) at 1300°C and 100 MPa for 4 hours. Th4+ immobilization was most readily achieved under oxidizing conditions, with Th4+ preferentially incorporated within a pyrochlore-structured phase in the range 0.10 ≤ x ≤ 0.50, yet formation of the zirconolite-4M polytype was not observed. We report the novel synthesis of single-phase pyrochlore with nominal composition CaZr0.40Th0.60Ti2O7 when targeting x = 0.60. Th4+ incorporation under reducing conditions produced a secondary Th-bearing perovskite, comprising 24.2 ± 0.6 wt% of the phase assemblage when targeting x = 0.40, alongside 8.8 ± 0.3 wt% undigested ThO2. Under reducing conditions, powder XRD data were consistent with zirconolite adopting the 3T polytype structure. The sample produced by HIP presented a nonequilibrium phase assemblage, yielding a major phase of zirconolite-2M alongside accessory Th4+-bearing phases ThTi2O6, ThO2, and perovskite. These data highlight the efficacy of Th4+ as a Pu4+ surrogate, with implications for the formation of Zr-stabilized Th-pyrochlore phases as matrices for waste with elevated Th4+ content. 相似文献
34.
生化需氧量(BOD)是表征水中有机污染物含量的重要指标,对水质监测和生化过程控制具有重要意义.总结了构成BOD检测系统的各环节,阐述了BOD微生物传感器中微生物选取、固定化以及换能器等关键技术,分析了不同方法的特点,讨论了目前BOD微生物传感器在研究中遇到的主要问题,并对其发展方向进行了展望. 相似文献
35.
A potentiometric biosensor based on bovine serum albumin (BSA) embedded surface modified polypyrrole has been developed for the quantitative estimation of urea in aqueous solution. The enzyme, urease (Urs), was covalently linked to free amino groups present over the BSA embedded modified surface of the conducting polypyrrole film electrochemically deposited onto an indium–tin-oxide (ITO) coated glass plate. The biosensor has been characterized by UV–visible, infrared spectroscopy and SEM. Potentiometric and spectrophotometric response of the enzyme electrode (Urs/BSA-PPy/ITO) were measured as a function of urea concentration in Tris–HCl buffer (pH 7.0). It has been found that the electrode responds to low urea concentration with wider range of detection. The electrode showed a linear response range of 6.6 × 10−6 to 7.5 × 10−4 M urea. The response time is about 70–90 s reaching to a 95% steady-state potential value and 75% of the enzyme activity is retained for about 2 months. These results indicate an efficient covalent linkage of enzyme to free amino groups of the BSA molecules over the surface of polypyrrole film, which leads to high enzyme loading, an increased lifetime stability of the electrode and an improved wide range of detection of low urea concentration in aqueous solution. 相似文献
36.
以MCM-41分子筛为载体,采用浸渍法将酞菁钴负载到分子筛上以氙灯为光源降解甲基橙溶液。对负载型酞菁钴催化剂进行FT-IR、XRD、SEM表征,结果表明所制催化剂负载效果良好,且分子筛结构未发生改变。以甲基橙溶液为模拟处理对象,研究催化剂的催化性能,考察了光照、酞菁钴负载、催化剂用量等因素对催化效果的影响。结果表明,氧气充足时,在光照条件下、0.04g负载型酞菁钴催化剂处理200mL的0.05g/L甲基橙溶液能够有很好的处理效果,2h降解率能够达到98.3%,且重复利用4次后降解率仍能达到90%。 相似文献
37.
研究了米根霉固定化方法 ,考察了在该反应器中培养基及其它操作条件对 L-乳酸发酵的影响。实验结果表明 ,应用吸附法固定米根霉进行 L-乳酸发酵具有发酵速度快 ,L-乳酸得率高等优点 相似文献
38.
利用生物信息学快速准确鉴别酶、非酶蛋白及内含肽能极大提高实验效率,而测序数量的指数型增长使酶、非酶蛋白及内含肽的自动分类尤显重要。本文获取了同一性小于25%的序列共计3853条,采用Z标度的伪氨基酸组成和氨基酸组成分布提取序列特征值识别酶、非酶蛋白及内含肽。结果表明,该特征值提取方法经参数优化后,即当λ=5,w=0.15时,以支持向量机为分类器,其10倍交叉验证的精度可达81.3%,ROC曲线下面积为0.83;其精度高于其它方法0.5%到12.9%不等;独立样本测试的预测精度可达71.2%,ROC曲线下面积为0.782,其精度高于其它方法0.4%到6.4%不等,效果均优于其它常见的序列特征值方法。本文结果说明从序列出发判断其归属是可行的,3种不同功能的分子在序列特征上存在一定的差异,所建立的Z标度的伪氨基酸组成和氨基酸组成分布法可用于其它类似的生物信息学问题。建立了从序列出发预测酶、非酶蛋白及内含肽的新方法。 相似文献
39.
以CaCO3、Fe(OH)3、Ca(H2PO4)2、MgO为稳定试剂,模拟复合污染的沉积物进行稳定化处理,运用毒性浸出方法(TCLP)评价沉积物中重金属的稳定化效果.实验结果表明:4种稳定剂不同程度提高了沉积物中重金属的稳定化效率.其中,CaCO3对Cu的稳定效率最高达到50.01%,对Pb的稳定效率最高为42.21%;Ca(H2PO4)2对Pb的稳定效率最好,最高可达90%以上,但对Ni未见明显的稳定效果;Fe(OH)3对As具有较好的稳定效果,稳定效率可达68.44%;MgO对Cu和Pb最高稳定效率为80%以上. 相似文献
40.
Bioflocculant-producing bacteria Agrobacterium tumefaciens F2 and Bacillus sphaeicus F6 were immobilized onto mycelial pellets to investigate the bioflocculant-producing potential of this combined organism and the corresponding flocculating efficiency. The atomic force microscope (AFM) images of mycelial surface indicate that the mycelia pellet can immobilize bioflocculant-producing bacteria F2 and F6 as a biomass carrier. The flocculating efficiency of bioflocculant produced by this combined organism was studied under the optimum flocculating conditions obtained by Response Surface Methodology (RSM). The fermentation yield of the combined mycelial pellet is about 2.6 g/L, which is higher than that of the free bacteria (only 2.2 g/L). Flocculating efficiency of the combined mycelial pellet was comparable with that of bioflocculant generated by the free bacteria. The bioflocculant yield is enhanced and the flocculating efficiency of the co-culture is uninfluenced after immobilized with mycelial pellet as a carrier. In conclusion, the mycelial pellet is feasible as a biomass carrier for the immobilization of bioflocculant-producing bacteria. 相似文献