微机控制变频调速系统SPWM序列的一种新算法

本文介绍了计算机控制的交流电动机变频调速系统SPWM序列的一种新算法。该算法改进了规则采样法。     

一种新的氨基酸描述符SVHEHS在生物活性肽QSAR中的应用研究

对20种氨基酸的457种性质参数按疏水性质、电性特征、氢键贡献和立体特征进行分类后,并各自进行主成分分析(PCA),得到一种新的氨基酸结构描述符SVHEHS(score vector of hydrophilicity, electronic, hydrogen bond contribution and steric properties)。用该描述符分别对一系列血管紧张素转化酶抑制二肽以及苦味二肽进行序列表征,并用来与生物活性建立多元线性回归模型。血管紧张素转化酶抑制二肽、苦味二肽模型的相关系数、交叉验证相关系数、均方根误差分别为0.936、0.854、0.259和0.949、0.886、0.136,同时还对所得模型进行了外部验证。结果表明,该描述符建立的模型具有较好的拟合与预测能力,用于生物活性肽的定量构效关系研究是理想的。     

一种大跨距管道的施工方法与应用

对某蒸汽管道跨河工程的设计方案进行了筛选,选定拱管+自然补偿架空敷设方案.对自然补偿量进行了应力验算,可满足设计要求.采用拱管支架,解决了架空管道跨距大的问题,设计跨度满足理论计算结果.     

一种新的酶载体的制备及其在脂肪酶固定化中的应用

聚乙二醇(PEG)是一种用途极为广泛的聚醚高分子化合物,它可应用于医药、卫生、食品、化工等众多领域.研究合成末端含有环氧基的聚乙二醇(环氧聚醚)的过程,讨论了反应物配比、反应时间、反应温度、分子量等因素对环氧聚醚的影响,结果表明,该反应的最佳反应条件:分子量为1000,在-OHmol:ECHmol:OH-mol=1:5:2,60%的条件下,反应5h,所得产物的转化率可达95%;并用该环氧聚醚作为接枝链,以壳聚糖为栽体,对脂肪酶进行固定化,得到活力较高的固定化脂肪酶,酶活力回收率约为36.5%,最适反应温度由游离酶的36℃上升至55℃,最适pH由8.0升至8.5,固定化酶的Km值由游离酶的51me/mL下降至45mg/mLo环氧聚醚接枝壳聚糖后固定化脂肪酶在较宽的温度和pH范围内稳定性高.     

一种新的酶载体的制备及其在脂肪酶固定化中的应用

聚乙二醇（PEG）是一种用途极为广泛的聚醚高分子化合物,它可应用于医药、卫生、食品、化工等众多领域。研究合成末端含有环氧基的聚乙二醇（环氧聚醚）的过程,讨论了反应物配比、反应时间、反应温度、分子量等因素对环氧聚醚的影响,结果表明,该反应的最佳反应条件:分子量为1000,在-OHmol:ECHmol:OHm-ol=1:5:2,60℃的条件下,反应5h,所得产物的转化率可达95%;并用该环氧聚醚作为接枝链,以壳聚糖为载体,对脂肪酶进行固定化,得到活力较高的固定化脂肪酶,酶活力回收率约为36.5%,最适反应温度由游离酶的36℃上升至55℃,最适pH由8.0升至8.5,固定化酶的Km值由游离酶的51mg/mL下降至45mg/mL。环氧聚醚接枝壳聚糖后固定化脂肪酶在较宽的温度和pH范围内稳定性高。      

血浆中85种有毒生物碱快速筛查方法的建立及其应用

目的 利用超高效液相色谱-四级杆/静电场轨道阱高分辨质谱建立血浆中85种有毒生物碱快速筛查方法。方法 构建85种生物碱高分辨数据库；血浆经乙腈沉淀蛋白进行预处理，采用Acquity Waters BEH C₁₈色谱柱（100 mm×2.1 mm，1.7 μm），以5 mmol/L甲酸铵（含0.1%甲酸）和乙腈为流动相进行梯度洗脱，对比了3种数据采集方式下（Full mass/dd-MS²、Full mass/AIF、Full mass/DIA）加标血浆中85种有毒生物碱筛查情况。结果 血浆在5、50和250 ng/mL 3个浓度添加水平下，Full mass/DIA模式下的筛选准确率均为最高。利用生物碱数据库，选择Full mass/DIA模式采集样品数据信息，建立了血浆中85种有毒生物碱快速筛查方法。80%以上生物碱在血浆中的检出限低于10 ng/mL。利用该方法成功在滇乌头碱毒物代谢动力学实验获得的3份Wistar大鼠血浆中筛选到了目标物滇乌头碱及其可能的代谢产物脱氧乌头碱及印乌头碱。结论 该方法快速、高效，可以在无标准品情况下实现突发性有毒生物碱中毒血浆的快速筛查。     

一种新的金刚石绳锯系统的开发及其在建筑施工中的应用效果

根据绳锯系统的开发及其在建筑施工中的应用,着重对该资料在设备开发、绳锯系统的改进设计、新绳锯的试验及其应用效果等方面作详细介绍。研究指出,新的绳锯系统具有设备重量轻、体积小、便于操作且绳锯消耗低、噪音小、污染少的优势。     

一种造纸法再造烟叶填料的制备方法及其应用

①技术领域[0001]本发明属于造纸法再造烟叶技术领域,具体涉及一种碳酸钙表面包覆技术提高造纸法再造烟叶片基碳酸钙留着率的方法。②背景技术[0002]在卷烟中掺配造纸法再造烟叶,对于提升卷烟品牌价值、减害降焦、产品质量安全等具有重要作用。在造纸法再造烟叶生产过程中通常要添加一定量的填料以改善产品的理     

一种绿色易降解的植物纤维面膜及其制备方法与应用

<正>申请公布号：CN 114983904 A发明人：王斌陈浩莹李金鹏陈克复丁霞申请人：华南理工大学;中纸科技文化发展（江苏）有限公司近年来,随着社会经济的迅速腾飞和生活水平的不断提高,护肤品消费呈增长趋势。其中,面膜的人均消费量更是逐年递增。目前面膜消费主体还是以贴片面膜为主,而贴片面膜所用到的面膜基布消耗量也逐年递增。     

一种水包油包胶型乳液的制备及其在乳化肠中的应用

以结冷胶和无水氯化钙为内水相凝固剂,酪蛋白酸钠为外水相乳化剂,制备一种水包油包胶（S/O/W）型 乳液。以多重乳液粒径和分布为指标,研究酪蛋白酸钠添加量对S/O/W型多重乳液加工适应性的影响。结果表明： 正交试验得到S/O型单重乳液最佳制备条件为：内水相中结冷胶添加量0.2%、无水氯化钙添加量0.5%;内水相乳化 剂聚甘油蓖麻醇酯添加量2.5%;油相为精炼猪油,油水体积比3∶2;剪切速率17 500 r/min,剪切时间1.5 min。将制 得的S/O型单重乳液与不同添加量酪蛋白酸钠混合制得S/O/W型多重乳液。当酪蛋白酸钠添加量0.1%时,S/O/W型 多重乳液粒径符合加工要求,且贮藏、热处理、剪切稳定性较好。以多重乳液替代猪脂肪制备的低脂乳化肠与高脂 （精炼猪油含量20%）乳化肠外观不存在明显差异;微观结构观察结果表明,多重乳液在乳化肠中包裹良好、分布 均匀。     

海藻糖快速检测方法的建立与初步应用

海藻糖是生物体合成的、具有抗逆保护作用的天然二糖,在食品加工与贮藏、微生物发酵过程具有重要作用。该文采用前期获得的专一性海藻糖酶,建立了一种定量测定海藻糖的快速方法。该方法对海藻糖的检测限为0. 019 mg/m L,定量限为0. 1 mg/m L;海藻糖的线性检测范围为0. 1 mg/m L～150. 0 mg/m L,回收率为98. 80%～101. 33%。该方法操作简便快捷、特异性高、重复性好,在菌种改良与食品原料营养筛查等海藻糖快速定量检测中具有良好的应用前景。     

食品安全监督抽检抽样工作中存在的问题 及其改进建议

食品是人类赖以生存和发展的基本物质之一[1],食品安全问题事关人民群众身体健康和国计民生。近些年来,我国食品安全事故时有发生,频频曝光的食品安全事件屡次刺痛国人"脆弱"的神经,食品安全问题也反复被推至舆论的风口浪尖。食品安全监督抽检是有效防范和及时化解食品安全风险隐患的主要手段,食品安全抽样工作是食品安全抽样检验工作的重要前提和关键性基础。本文结合笔者多年从事食品安全抽样工作经验,梳理了食品安全监督抽检抽样工作中存在的主要问题,并提出相应的改进建议,旨在提高食品安全抽样工作质量。     

一种基于交叉采样技术的高速数据采集方法

介绍了一种基于交叉采样原理的高速数据采集系统的实现方法，运用了存贮器芯片之间并行交叉写入及多通道交叉采样数据信号技术，并应用硬件控制时序逻辑，达到了较高的采样速率。     

工业蛋白水解酶快速检测方法的建立与初步应用

蛋白水解酶是一类重要的工业酶制剂,快速检测蛋白水解酶活力对新蛋白酶的发现、生产与应用极为重要。基于荧光共振能量转移原理,用氟硼荧荧光素标记大豆分离蛋白,以此为底物建立了一种快速检测蛋白水解酶活力的新方法。运用此方法检测5种工业蛋白酶,酶活在0. 025～0. 4 U/m L与荧光值呈现良好的线性关系,检测限范围为1. 1×10~(-4)～1. 4×10~(-4)U/m L,定量限范围为3. 7×10~(-4)～4. 5×10~(-4)U/m L,相比国标福林法灵敏度提高20 000倍以上。该方法灵敏度高、操作简便,在蛋白水解酶快速、微量检测及新型蛋白水解酶开发中具有应用潜力。     

Physiologically based pharmacokinetic model for quinocetone in pigs and extrapolation to mequindox

ABSTRACT

Physiologically based pharmacokinetic (PBPK) models are scientific methods used to predict veterinary drug residues that may occur in food-producing animals, and which have powerful extrapolation ability. Quinocetone (QCT) and mequindox (MEQ) are widely used in China for the prevention of bacterial infections and promoting animal growth, but their abuse causes a potential threat to human health. In this study, a flow-limited PBPK model was developed to simulate simultaneously residue depletion of QCT and its marker residue dideoxyquinocetone (DQCT) in pigs. The model included compartments for blood, liver, kidney, muscle and fat and an extra compartment representing the other tissues. Physiological parameters were obtained from the literature. Plasma protein binding rates, renal clearances and tissue/plasma partition coefficients were determined by in vitro and in vivo experiments. The model was calibrated and validated with several pharmacokinetic and residue-depletion datasets from the literature. Sensitivity analysis and Monte Carlo simulations were incorporated into the PBPK model to estimate individual variation of residual concentrations. The PBPK model for MEQ, the congener compound of QCT, was built through cross-compound extrapolation based on the model for QCT. The QCT model accurately predicted the concentrations of QCT and DQCT in various tissues at most time points, especially the later time points. Correlation coefficients between predicted and measured values for all tissues were greater than 0.9. Monte Carlo simulations showed excellent consistency between estimated concentration distributions and measured data points. The extrapolation model also showed good predictive power. The present models contribute to improve the residue monitoring systems of QCT and MEQ, and provide evidence of the usefulness of PBPK model extrapolation for the same kinds of compounds.     

A novel pH‐sensitive hydrogels for potential colon‐specific drug delivery: Characterization and in vitro release studies

Stimuli‐responsive hydrogels are extensively investigated to implement new biomedical and pharmaceutical approaches. In this work, novel pH‐sensitive semi‐interpenetrating polymer network (semi‐IPN) hydrogels based on starch and poly(aspartic acid) (PAsp) with potential applicability in the field of pharmaceutics were prepared and characterized. The goal was to obtain a colon specific drug delivery system and to exploit the pH‐sensitive behavior of the hydrogels. The obtained hydrogels were characterized by FTIR, thermogravimetric analysis (TGA), DSC, and SEM. The swelling behavior of the hydrogels with a suitable ratio of starch and poly(aspartic acid) was investigated in gastrointestinal simulated conditions. Moreover, the drug release studies were carried out using 5‐Flurouracil as a model of anticancer drug in enzyme free simulated gastrointestinal conditions and simulated intestinal conditions containing α‐amylase, respectively. The obtained hydrogels, due to their excellent pH‐sensitive release property, could be potentially used as drug delivery systems for the oral treatment of colonic cancer.     

A novel method for the determination of some pesticides in vegetable oils based on dissociation extraction followed by gas chromatography-mass spectrometry

The distribution of 40 pesticides of basic nature in different extraction systems was studied at 20 ± 1°C. The distribution constants (P) and distribution ratios (D) between n-hexane and polar phases are calculated. It was found that the studied pesticides are most fully and selectively extracted from hexane and vegetable oils by solutions of perchloric acid in acetonitrile. In particular, the acidification of acetonitrile decreases the D-value of fenpropimorph by 29,000 times. This phenomenon was used for the development of an improved technique for the quantitative analysis of widely used pesticides of basic nature in rapeseed, linseed, sunflower and olive oils by GC-MS. The proposed approach allows obtaining much purer sample extracts, compared with the use of standard solvent extraction with further purification by the freezing-out technique. This approach expands the range of pesticides (flutriafol, fenpropidine, metazachlor, cyprodinil and others) that can be determined by GC-MS. The recovery values of the studied pesticides from vegetable oils were between 85% and 115% with RSD values below 10%. The obtained limits of detection ranged from 0.001 to 0.1 mg kg^–1, and are below or equal to the maximum residue levels (MRLs) set by the European Union for the corresponding pesticides.     

叶黄素的化学降解产物及机理研究

研究了叶黄素在Ａｇ＋催化作用下经空气氧化降解的机理。其降解产物经ＧＣ／ＭＳ分析，并用作烟用香料。     

新型混菌发酵制备丙酸工艺及其优化

以产酸丙酸杆菌和酵母菌为菌种,进行混菌发酵制备丙酸的工艺研究,并探索最优工艺条件。通过单因素实验和正交优化实验确定了最优发酵工艺条件为:酿酒酵母为辅助菌,接种比例为Pa∶Sc=2.5∶1,接种间隔时间为8h,发酵温度为30℃,以NaOH(2mol/L)溶液为中和剂,采用自动流加方式,发酵时间为180h。优化后的混菌发酵工艺能有效提高丙酸产量,丙酸产量达24.16g/L,与纯菌发酵相比提高46.34%。      

水性环氧树脂碳纤维上浆剂的研制与性能分析

通过对环氧树脂进行亲水化改性,使其具有水溶性,再分散制成合适浓度的水性环氧树脂上浆剂,对聚丙烯腈基碳纤维进行上浆.测试上浆剂的性能,观察碳纤维上浆前后纤维的表面形态,并测试纤维的耐磨性、毛丝量及界面剪切强度的变化.结果表明:使用该水性环氧树脂上浆剂上浆后,碳纤维表面形成柔韧光滑的浆膜,耐磨性能提高91.6%,毛丝量减少...