Covalent immobilization of naringinase for the transformation of a flavonoid

Naringinase (EC 3.2.1.40) from Penicillium sp was immobilized by covalent binding to woodchips to improve its catalytic activity. The immobilization of naringinase on glutaraldehyde‐coated woodchips (600 mg woodchips, 10 U naringinase, 45 °C, pH 4.0 and 12h) through 1% glutaraldehyde cross‐linking was optimized. The pH–activity curve of the immobilized enzyme shifted toward a lower pH compared with that of the soluble enzyme. The immobilization caused a marked increase in thermal stability of the enzyme. The immobilized naringinase was stable during storage at 4 °C. No loss of activity was observed when the immobilized enzyme was used for seven consecutive cycles of operations. The efficiency of immobilization was 120%, while soluble naringinase afforded 82% efficacy for the hydrolysis of standard naringin under optimal conditions. Its applicability for debittering kinnow mandarin juice afforded 76% debittering efficiency. Copyright © 2005 Society of Chemical Industry     

Purification and characterisation of basic ascorbate oxidase from satsuma mandarin (Citrus unshiu Marc)

Basic ascorbate oxidase of the multiple enzyme forms existing in young fruit of satsuma mandarin (Citrus unshiu Marc) has been separated and subsequently purified to electrophoretic homogeneity through (NH₄)₂SO₄ fractionation and chromatographies on DEAE-Toyopearl 650M, CM-Sephadex C-50 and Sephadex G-100. The native molecular weight was estimated to be 141 kDa by gel filtration and composed of two non-identical subunits with an apparent mass of 74 kDa and 62 kDa. The optimum pH was found to be 5.5 with reasonable stability between pH 5 and 8. The enzyme had an optimum temperature at 45°C and was stable up to 50°C upon heat treatment for 5 min. The presence of sodium diethyldithiocarbamate, metabisulphite and potassium cyanide completely inhibited the enzyme activity. Fluoride also inhibited the activity substantially at higher concentrations. Other tnonovalent and divalent metal ions did not have inhibitory effects.     

基于层级策略的连续数字串识别的研究

在分析汉语数字串语音特点的基础上,设计出了基于层级策略的连续数字串识别系统。该系统先对连续数字串进行确定性的预分割,再用LevelBuilding算法对每个分割段进行基于模板模糊分组的识别,在该识别结果的基础上利用加权矩阵识别算法进一步区分易混淆语音对。该系统在计算时间减少到原来的35.2%的同时识别率提高到94.08%。     

普通话语音情感识别的特征选择技术

谢波，陈岭，陈根才，陈纯针对情感声学特征在语音情感识别中的重要性问题，运用优先选择、序列前向、序列后向和逐步判别分析进行了特征选择.对说话人和文本均无关、说话人相关2组普通话情感语音进行特征选择，然后利用线性判别分析和支持向量机进行实际识别效果的分析比较.特征选择结果表明，基频、对数能量、语速和第一共振峰均值对普通话情感语音具有较强的判别能力，但情感声学特征的判别力随着说话人的不同而有所差异.特征选择方法比较实验表明，逐步判别分析比其他3种方法具有更高的平均准确率，当特征个数为9~12时分类器的平均准确率最高.效用分析表明，特征选择在小样本时更加有效.     

基于遗传算法数据降维的汉语数字语音识别

针对语音信号特征参数LPCC和MFCC相结合后数据维数过高,导致识别器性能下降的问题,提出采用遗传算法对初始特征参数进行降维,来提高识别性能.首先提取语音信号的LPCC和MFCC,然后采用遗传算法对其进行特征降维,最后将得到的低维数据送入支持向量机进行识别.仿真实验结果表明,采用遗传算法进行特征降维与传统的PCA降维相比,识别率提高了12.2%,和初始特征相比识别率降低了1.23%,但是识别时间提高了4.5倍.     

基于韵律信息的连续语流调型评测研究

汉语连续语流中的调型评测是汉语语音评测的一个重要环节,利用连续语流中韵律耦合效应和韵律结构紧密相关这一特性,以韵律词为基本建模单元,建立基于多空间概率分布的HMM调型模型(MSD-HMM),使得汉语普通话水平评测系统针对标准连续语流的调型识别率从82.0% 提升至84.6%;针对有方言背景的非标准发音,机器评分与专家评分的相关度绝对提升超过3.0%。     

鳜鱼致敏蛋白的识别及酶法水解的脱敏分析

试验采用聚丙烯酰胺凝胶电泳对鳜鱼蛋白提取液中不同分子质量的蛋白组分进行分离,在阳性血清池建立的基础上,运用转移电泳、免疫印迹以及免疫印迹抑制试验识别特异性吸附蛋白条带。进而采取不同来源的6种食品级蛋白酶对鳜鱼蛋白水解脱敏,将中性甲醛电位滴定法和间接酶联免疫吸附法测定的水解度和抗原降低率作为评判指标优选出最佳水解酶。最终得到分子质量为60、50、34 ku和17 ku的4条蛋白条带可以与IgE阳性结合,最佳水解酶为木瓜蛋白酶。     

安徽名菜"腌鲜鳜鱼"化学工艺参数研究

对在室温(25±20℃)下经淡盐水(1%、2%、3%)腌制的鳜鱼进行鱼肉浸出物游离氨基酸总量、氨基酸的半定量测定和亚硝酸盐含量的测定及丙二醛(MDA)的测定,比较腌制前后的变化,判定其污染程度及可食性.结果表明,鲜活的鳜鱼肌肉游离氨基酸含量为0.189%,几乎不含亚硝酸盐;腌制期间以上两项指标均随着腌制时间的延长而增加,而腌制90h后游离氨基酸总量最大达到0.68%,亚硝酸盐含量达到30.43mg/kg,此时鱼肉腐败变质,不再具食用价值.     

评价室内汉语清晰度中STI计权方法适用性检验

为检验评价室内汉语（普通话）清晰度中不同语言传输指数（STI）计权方法的适用性,通过在一系列不同听音条件下的主观听音试验与声场测量,研究了4种典型计权方法下的STI与汉语清晰度得分（SI）之间的相关性.回归分析表明这4种计权方法对应的STI与SI间呈现了良好的正相关关系.相比于在计权因子变化时STI与SI间三次多项式回归标准偏差可能达到的最小值与最大值,这4种STI对应的回归标准偏差接近最大值而远离最小值,显示了它们在评价室内汉语清晰度时的良好性质.与其他涉及不同客观参量与语种的同类研究结果的对比也表明,这4种STI评价室内汉语清晰度的精度处于一个较好的范围内.