超声辅助提取荔枝核黄酮工艺的响应面优化及抗氧化性研究

研究了超声波辅助乙醇溶剂法萃取荔枝核黄酮的工艺条件。在单因素试验基础上,采用BoxBehnken设计进行响应面优化分析,建立回归方程模型,模型决定系数R2=0.985 0。结果表明,优化的最佳工艺参数为:液料比12.7∶1(g/g),超声时间14.7 min,提取时间120 min,超声波功率174 W,乙醇体积分数55%。该工艺条件下,荔枝核黄酮提取实际得率均值为6.565 6%。荔枝核黄酮具有较强的自由基清除能力,其清除·OH和DPPH·的IC50分别为5.938μg·m L~(-1)和8.571μg·m L~(-1)。     

纳米TiO2在果蔬包装中的应用研究进展

统计归纳了纳米TiO_2在食品保鲜中的应用及研究热点,分析了纳米TiO_2的抑菌机制及作用,综述了纳米TiO_2在水果、蔬菜、食用菌保鲜中的应用研究进展,展望了纳米TiO_2在食品保鲜领域未来的研究方向,以期为纳米TiO_2在果蔬贮藏保鲜中的产业化应用提供理论基础和技术参考。     

超声波提取茄子皮天然红色素工艺研究

通过单因素试验确定了提取溶剂种类、提取剂浓度、料液比、提取温度、浸提时间及超声波功率的适用范围,再利用正交试验法进行工艺优化,得出超声波提取茄子皮天然红色素的最佳工艺条件。试验结果表明,影响因素主次顺序为：料液比〉提取时间〉提取温度。用酸性无水乙醇溶液超声波提取茄子天然红色素的最佳工艺条件为料液比1：6、浸提温度70℃、浸提时间30min、功率160W。     

万寿菊花中α-三连噻吩的提取研究

以万寿菊花为原料,用氯仿提取其中光活化杀虫物质α-三连噻吩,并利用气相色谱测定所提取液中α-三连噻吩的含量。通过单因素实验和正交实验研究了料液比、提取时间和提取温度等因素对α-三连噻吩得率的影响。实验表明,最佳提取工艺参数为:料液比为1∶20,提取时间为5h,提取温度为85℃,提取率达到1.5042%。     

Performance of DSSAT-Nwheat across a wide range of current and future growing conditions

Crop models are widely used in agricultural impact studies. However, many studies have reported large uncertainties from single-model-based simulation analyses, suggesting the need for multi-model simulation capabilities. In this study, the APSIM-Nwheat model was integrated into the Decision Support System for Agro-technology (DSSAT), which already includes two wheat models, to create multi-model simulation capabilities for wheat cropping systems analysis. The new model in DSSAT (DSSAT-Nwheat) was evaluated using more than 1000 observations from field experiments of 65 treatments, which included a wide range of nitrogen fertilizer applications, water supply (irrigation and rainout shelter), planting dates, elevated atmospheric CO₂ concentrations, temperature variations, cultivars, and soil types in diverse climatic regions that represented the main wheat growing areas of the world.DSSAT-Nwheat reproduced the observed grain yields well with an overall root mean square deviation (RMSD) of 0.89 t/ha (13%). Nitrogen applications, water supply, and planting dates had large effects on observed biomass and grain yields, and the model reproduced these crop responses well. Crop total biomass and nitrogen uptake were reproduced well despite relatively poor simulations of observed leaf area measurements during the growing season. The low sensitivity of biomass simulations to poor simulations of leaf area index (LAI) were due to little changes in intercepted solar radiation at LAI >3 and water and nitrogen stress often limiting photosynthesis and growth rather than light interception at low LAI.The responses of DSSAT-Nwheat to temperature variations and elevated atmospheric CO₂ concentrations were close to observed responses. When compared with the two other DSSAT-wheat models (CERES and CROPSIM), these responses were similar, except for the responses to hot environments, due to different approaches in modeling heat stress effects.The comprehensive evaluation of the DSSAT-Nwheat model with field measurements, including a comparison with two other DSSAT-wheat models, created a multi-model simulation platform that allows the quantification of model uncertainties in wheat impact assessments.     

进口大豆粉碎细度对索氏抽提法测粗脂肪含量的影响

以进口大豆为研究对象,采用高效粉碎机和脂肪测定仪进行粉碎和抽提,研究其粉碎细度对索氏抽提法测粗脂肪含量的影响。结果表明,大豆粉碎细度越小,其粗脂肪含量测得越高。     

不同发育时期菊芋块茎DNA提取效果比较研究

为筛选菊芋块茎DNA提取的适宜生育时期,以“青芋1号”菊芋品种为试材,用改良CTAB法对不同发育时期菊芋块茎DNA进行提取,经琼脂糖凝胶电泳及全波长分光光度计检测总DNA的纯度、浓度及质量,选用4条ISSR引物进行PCR验证.结果表明:不同发育时期提取菊芋块茎DNA效果较好,DNA浓度呈现单峰曲线变化,峰值出现在第9周,与琼脂糖凝胶电泳检测呈现的亮度结果一致,PCR验证结果显示,提取的DNA能够满足后续相关分子生物学的要求.     

微波辅助提取花生红衣中白藜芦醇工艺的研究

对微波辅助提取花生红衣中白藜芦醇的工艺进行研究,从4种常用试剂中选择乙醇作为提取剂,并在单因素试验的基础上,通过正交试验优化白藜芦醇的提取条件。确定花生红衣白藜芦醇微波辅助提取的最佳工艺为:提取时间210s,微波功率480W,料液比为1∶20,乙醇体积分数为70%,此条件的花生红衣白藜芦醇得率为0.038%。     

A method of production data analysis for multi-fractured horizontal well in shale gas reservoir

Production data analysis is an effective method of evaluating gas in place, parameters of reservoir and hydraulic fractures. Current model of production data analysis fails to make sense because of the existence of absorption, multi-fracturing, and stimulated reservoir volume (SRV). Considering the effect of desorption, fracture interacting and closed boundary, the authors calculate the productivity of multi-fractured horizontal well in shale gas by Laplace transform and pressure superposition principle. Then theoretical charts of Agarwal-Gardner production decline curves are presented by employing new definition of dimensionless material balance time and dimensionless production, which is based on asymptotic approximations. The result shows that Agarwal-Gardner curves can be divided into two parts where they are scattered in early transient period, and where their shape was influenced by parameters relevant to adsorption, position of each fracture and reservoir geometry, and then drawn to Arps harmonious decline in pseudo steady state period. Reservoir parameters, hydraulic fracture characteristics and gas in place are evaluated by using the type curve matching with actual production data.     

Lossless data hiding with ranks transform

For taking full advantage of carrier image's pixel correlation, a lossless data hiding algorithm with ranks transform (LDHA_RT) is proposed. Along with three directions of column, row and diagonal, the pixel difference images and their histograms are calculated one after another. The obtained pixel difference histograms are shifted to construct the redundancy spaces, so that the hiding information could be embedded in a designated position. After the hiding data is extracted, the carrier image could be recovered reversibly without any additional information. The experiments demonstrate that the PSNR/bits of the LDHA_RT is the lowest or close to the lowest, compard with these algorithms mentioned in the references. This implies that the LDHA_RT has large capacity of hiding data under a good image quality.