基于Fluent的温室热交换除湿器性能研究

利用Fluent软件,采用SIMPLE算法及标准k—ε湍流模型,对温室除湿器内不可压缩流体的流动情况进行三维数值模拟。通过分析叉排和顺排两种排管结构在同一平面上的压力分布、速度矢量和温度分布,确定叉排比顺排的换热效果好。根据实际情况,选取一系列的入口风速进行计算分析,得出入口风速为3.0m/s时的换热效果最佳。     

蔬菜中灭蝇胺残留的强阳离子交换固相萃取柱净化-液相色谱分析

建立了简单、快速测定蔬菜中灭蝇胺残留量的方法。蔬菜样品经乙酸胺-乙腈(1∶ 4,体积比)混合溶液提取,强阳离子交换固相萃取(SCX-SPE)柱净化后,采用高效液相色谱仪在波长215 nm处测定,所用色谱柱为Agilent NH2,流动相为乙腈-水溶液(97∶ 3,体积比),以1.0 mL/min的流速等梯度洗脱。结果表明,在浓度为0.02~2 mg/L范围内,线性相关系数为0.999 9。灭蝇 胺的添加浓度在0.05~0.4 mg/kg范围内,平均回收率为83.4%~104%,相对标准偏差为1.7%~8. 4%,均在农药残留测定所允许的范围内。该方法的最低检出限(LOD)为0.02 mg/kg,最低检测浓度(LOQ)为0.05 mg/kg。     

Preparation of shikonin by hydrolyzing ester derivatives using basic anion ion exchange resin as solid catalyst

An efficient catalytic hydrolysis approach was developed to prepare shikonin from its ester derivatives with anion exchange resins as solid catalyst. The performance of seven anion exchange resins including D290, D296, D261, D280, 201×7, D301-G and D301-R has been evaluated. The research results indicate that D290 resin is the most appropriate for preparation of shikonin. The reaction conditions such as reaction temperature, reaction time, catalyst amount and catalyst reuse have been studied. The maximum yield of shikonin reached 93.74 ± 2.99% under optimal conditions of hydrolysis temperature 20 °C, hydrolysis and desorption time both 30 min and resin amount 10% (w/v). HPLC chromatograms of samples, obtained after the new catalytic process, demonstrated that conversion of shikonin ester derivatives into shikonin performed well.     

持续干旱对侧柏和祁连圆柏叶片水分状况及光合作用的影响

以侧柏(Platycladus orientalis)和祁连圆柏(Juniperus przewalskii)2年生幼苗为材料,用盆栽实验比较持续干旱对两者叶片水分及光合生理特性的影响。研究发现:侧柏水势(ψ)、叶片相对含水量(RWC)、净光合速率(Pn)、最大光化学效率(Fv/Fm)、实际光化学效率(Φ_(PSII))、电子传递速率(ETR)和叶绿素含量(Chl a,Chl b,Chl a+b)的下降幅度均大于祁连圆柏,且游离脯氨酸含量(Pro)和叶绿素原初荧光值(Fo)上升幅度大于后者,但两者胞间CO_2浓度(Ci)和气孔限制值(Is)变化相反。这些结果表明,侧柏对干旱胁迫敏感度明显高于祁连圆柏,祁连圆柏对干旱胁迫的抵抗力更高;侧柏净光合速率的下降主要是叶绿素组分和光合器官功能的破坏等非气孔因素引起的,而祁连圆柏净光合速率的下降主要是气孔因素引起的。另外,持续干旱处理后祁连圆柏仍保持较高的瞬时水分利用效率(WUEi)和电子传递速率(ETR),表明它能够通过提高水分利用效率和光呼吸速率来减小干旱胁迫产生的伤害。这将为黄土高原区生态恢复中造林绿化树种的选择提供理论依据和实践指导。     

Thermodynamic Analysis of River Water Fouling on Constant Wall Temperature Tube of Small Diameter

In order to improve utilization of cold and heat source from river, turbulence theory and entropy generation theory were adopted to analyze the effect of fouling on convective heat transfer performance in small diameter tube of constant wall temperature.It is found that the entropy generation caused by conduction of fouling plays a more important role in total entropy generation of heat transfer process through a duct than that in cveast rate of caused by temperature difference.The entropy generation caused by viscous flow is more than the entropy generation caused by temperature difference in flow with bigger Reynolds and small radius.The increase rate of entropy generation monotonically increase with Reynolds and the generation process of fouling resistance.Thereafter, the effect of fouling resistance on the heat transfer performance of water source heat pump heat exchanger should be paid more attention, when river water are used as the cold and heat source of heat pump.     

发酵法生产丙酮酸钠提取工艺的研究

建立了发酵法生产丙酮酸钠的提取纯化工艺:发酵液经超滤膜过滤,滤液使用纳滤膜浓缩,浓缩液过HD-1树脂脱色除杂,收集流出液,流加NaOH溶液调pH至6.8,醇沉结晶,滤除母液后湿粉在46℃条件下真空干燥,粉碎成产品。经检验,提纯产品小样含量、水分等均符合质量标准。     

人民币汇率变动对就业影响的动态CGE研究

通过引入资本累积、金融资本累积以及劳动力市场的调整3种跨期链接将可计算一般均衡模型动态化,研究人民币汇率变动对中国就业的冲击影响研究结果表明：人民币升值将导致中国劳动力成本提高,使得很多劳动密集型企业丧失产品价格优势,进而使得失业人口增加;人民币升值对不同行业的影响各异,将导致劳动密集型行业和原材料出口型行业的就业形势严重恶化,人民币升值对以原料进口的行业具有正向作用,服务业也从人民币升值中受益,人民币升值对我国第一产业就业影响较为稳定.     

使用双币种期权的风险管理

以VaR作为风险度量的工具,研究固定汇率制度下使用双币种期权对冲进行的风险管理．研究表明,可以通过确定最优敲定价格减小VaR,并对获得的结论做了比较静态分析．     

离子交换层析纯化重组福安泰-03功能域的工艺条件研究

对阴离子交换树脂HiTrap DEAE Sepharose FF纯化重组福安泰-03功能域（rFAT-03）的合适条件进行了研究。通过试验,确定了柱层析的最佳操作条件,即在上样缓冲液为0.1mol/L Tris-HCl、洗脱缓冲液为1mol/L NaCl＋0.1mol/L Tris-HCl、pH为8.8的条件下,利用HiTrap DEAE SepharoseFF琼脂糖凝胶吸附柱,先用洗脱缓冲液从30%到60%洗脱3个柱床体积,再用洗脱缓冲液从60%到100%洗脱2个柱床体积。在此试验条件下,rFAT-03得率为35.97%,最终纯化的rFAT-03达电泳纯,纯度为99.5%。     

天然橡胶现货和期货市场比较分析

对天然橡胶现货和期货的销售过程、交易市场、交易所等进行比较,分析了我国天然橡胶现货和期货市场存在的问题并提出改进的方案,总结了国际天然橡胶定价中心成功因素。