茶用香花珠兰的香气成分分析

用水蒸气蒸馏法提取珠兰挥发油,并用气相色谱-质谱联用仪对珠兰挥发油的化学成分进行了分离和鉴定,分离并鉴定出27个组分,占峰面积的85.89%,并用峰面积归一化法测定了各成分的质量分数。其主要挥发性成分为:w(反-罗勒烯)=5.71%、w(3,6二-甲基-4,5二-乙基-3,5-辛二烯)=4.61%,w〔1-(1,4二-甲基-3环-己烯基)乙酮〕=3.53%、w(2,6二-甲基-2,4,6辛-三烯)=1.45%、w(大根香叶烯B)=1.44%、w(顺-罗勒烯)=1.43%、w(大根香叶烯D)=1.40%、w(3蒈-烯)=1.25%、w(杜松醇)=1.02%。     

基于TACNN的玉露香梨叶虫害识别

为了解决玉露香梨叶虫害种类多、扩散速度快、人工识别梨叶虫害耗时长的问题,提出了能够在自然环境下对玉露香梨叶虫害图像自动识别的Tiny-Alexnet卷积神经网络（Tiny-Alexnet Convolution Neural Network,TACNN）的虫害识别模型。分析了Alexnet模型的网络结构,并将实地采集的玉露香叶片虫害图像进行统一处理,为避免全连接层卷积核参数过大而产生的过拟合现象,通过优化全连接层,设置不同神经元节点和实验参数,得出了Mid-Alexnet、TACNN两种虫害识别模型。实验结果表明：TACNN较Alexnet和Mid-Alexnet模型有较高的识别准确率,该模型能够有效地提取梨叶虫害特征,类别平均准确率为81.18%,实现了对金龟子、梨木虱、梨瘿蚊三种虫害的准确区分。该模型在玉露香梨叶虫害识别方面具有良好的性能,可实现自然环境下玉露香梨叶虫害的精准识别。     

异菌脲在梨和土壤中残留量的测定方法

建立了异菌脲在梨和土壤中气相色谱分析方法。梨、土壤样品用乙腈提取,Florisil固相萃取小柱净化,淋出液浓缩后用正己烷定容,气相色谱仪电子捕获器检测。试验结果表明,异菌脲的含量与峰面积之间呈线性关系,异菌脲的最小检出量为0.005ng。对于梨样本,异菌脲最低检测量为0.01mg/kg,添加平均回收率为94%～107%,变异系数为3.2%～6.5%;对于土壤样本,异菌脲最低检测量为0.01mg/kg,添加平均回收率为98%～110%,变异系数为4.0%～10.5%。结果表明该残留分析方法的灵敏度、准确度、精密度等均符合农药残留检测的要求。     

Experimental study on drying of pear slices in a convective dryer

The experiments were conducted on pear slices with thickness of 5 mm at temperatures of 50, 57, 64 and 71 °C with an air velocity of 2.0 m s^?1. Prior to drying, pear slices were pretreated with citric acid solution (0.5% w/w, 1 min, 20 °C) or blanched in hot water (1 min, 85 °C). Also, the untreated samples were dried as control. The shortest drying time of pear slices was obtained with pretreatment with citric acid solution. It was observed that whole drying process of pear slices took place in a falling rate period. Four mathematical models were tested to fit drying data of pear slices. According to the statistical criteria (R², χ² and RMSE), the Midilli et al. model was found to be the best model to describe the drying behaviour of pear slices. The effective diffusivity of moisture transfer during drying process varied between 8.56 × 10^?11 and 2.25 × 10^?10 m² s^?1, while the activation energy of moisture diffusion in pear slices was found to be 34.95–41.00 kJ mol^?1.     

用红外光谱技术研究打蜡梨的红外光谱特性

采用CCD阵列光谱仪研究了打蜡梨的红外光谱特性。经分析,在655~660 nm波段,经过打蜡处理后的梨会出现吸收峰,而未经打蜡处理的梨则没有出现吸收峰;在610~620 nm波段,打过石蜡梨的红外图谱吸收峰峰高和未打蜡梨的红外图谱吸收峰峰高相当,而打过果蜡梨的红外图谱吸收峰远远低于未打蜡梨的红外图谱吸收峰。该结果表明红外光谱技术在打蜡梨检测中具有一定的可行性,同时也为进一步研究针对打蜡梨的智能化无损检测技术提供了参考依据。     

梨膏的流变学特性及其影响因素

目的 考察人为加糖、加胶后梨膏触变性及黏度的变化。方法 以鸭梨为实验材料,通过真空浓缩方式制备鸭梨膏,采用HR-10型流变仪对其流体类型、黏度、触变性进行测定。结果 鸭梨膏属于非牛顿流体,具体细分为无限接近牛顿流体的假塑性流体,具有剪切稀化特性和正触变特性;损耗模量G″总是大于储能模量G’,表现出液体黏性性质;剪切速率与剪切力变化关系符合PowerLaw方程,拟合效果良好(r2>0.99);温度显著影响梨膏黏度,黏度随温度升高而降低,二者关系符合Arrhenius方程,拟合效果良好(r2>0.99);可溶性固形物含量(solublesolidscontent,SSC)对黏度的影响符合指数函数关系,模型拟合效果良好(r2>0.99);SSC以及人为加糖、加胶处理对梨膏触变性、黏度影响显著(P<0.05),黏度随SSC的升高而增强,人为加胶、加糖加胶会导致梨膏黏度显著升高(P<0.05);触变性随SSC的升高而增强,同时人为加糖、加胶、加糖加胶处理会导致梨膏触变性显著减弱(P<0.05)。结论 人为添加糖、胶会导致梨膏的流变学特性发生改变。本研究可为工业...     

Biosorption of chromium (VI) from aqueous solution by seed powder of prickly pear (Opuntia ficus indica L.) fruits

ABSTRACT

The solid residue of the cold press oil extraction from prickly pear (Opuntia ficus indica L.) fruit seeds was evaluated as a low-cost biosorbent for biosorption of Cr(VI) from aqueous solutions. Batch experiments were conducted as a function of initial pH, contact time, biosorbent dose, initial Cr(VI) concentration, and temperature. Biosorption was highly pH-dependent and found to be maximum at pH 1.0. Langmuir and Freundlich equations fitted very well with experimental data. The maximum monolayer adsorption capacity was 19.61 mg/g at 298 K and pH 1.0. Biosorption kinetics was controlled by the pseudo-second-order model. Thermodynamic parameters indicated that biosorption of Cr(VI) was a spontaneous, favorable and endothermic process. The activation energy was found to be 40.68 kJ.mol^?1.     

红外光谱在基础有机化学实验中的应用（Ⅱ）——芳香类化合物的解析

红外光谱是一种现代分析技术,它已经成为有机化学及其相关领域研究中不可缺少的工具。在教学中,用红外光谱检测基础有机化学实验中的芳香族产品,能使理论教学与实践教学联系起来,取得了很好的教学效果。     

菊酯类农药在梨中的多残留测定方法研究

采用气相色谱法(带有电子捕获检测器ECD),以正己烷、丙酮、石油醚等多种有机溶剂及其混合液为提取溶剂,以氟罗里硅土(Florisil)柱净化法,对梨果实中的3种常用菊酯类农药进行了多残留检测。结果表明以正己烷与丙酮的混合提取剂的提取效果好,其平均回收率范围为74.14%~99.14%,变异系数(CV)范围为1.36%~7.60%,在程序升温的条件下,3种农药可很好地分离,检出限范围为0.0006~0.006mg/kg。其准确度和精确度均达到了农药残留分析的要求。