不同形态芡实产品的吸湿特性及其数学模拟分析

研究了不同形态芡实产品在不同相对湿度下的吸湿特性。吸湿率结果表明,干燥芡实产品具有很强的吸湿性。在相对湿度90%的环境中,经30d,带壳芡实、整芡仁、碎芡仁和芡实粉的含水率分别从吸湿前的10.20%、4.83%、3.93%和0.99%增加到19.78%、20.80%、20.66%和21.27%。对芡实产品吸湿率数据进行一元非线性回归,建立了2个吸湿率数学模型,分别为:幂函数模型W=a.tb,负指数函数模型W=aExp(b/t)。得到了不同芡实产品在不同相对湿度下的吸湿率模型参数,所得吸湿率数学模型均具有较理想的拟合效果。其中,负指数函数模型结构简单且拟合准确度较高,可用于不同芡实产品在不同湿度环境中的吸湿率预测。      

福堂水电站引水隧洞工程中的监理控制

福堂水电站引水隧洞工程是目前国内最长的大型水工压力隧洞,工程难度大,施工方法具有代表性。在分析工程施工特点和难点的基础上,介绍了监理工程师所采取的控制措施及所取得的效果。     

芡种壳提取物抗氧化、抑菌活性及其组分分析

为了解芡种壳提取物主要生理活性和化学组成,采用体外抗氧化分析方法分析了提取物的总还原力、清除NO2-和DPPH·活性以及抗脂质过氧化性质;采用微生物培养法对其抑菌活性进行了分析;采用高效液相色谱法对其主要组分进行了分析。结果表明4种芡种壳提取物中总酚含量很高（387.62⁷63.65 mg/g）,并显示出较强的总还原力、较强的DPPH·清除作用和脂质过氧化抑制活性以及中等强度的NO2-清除活性。4种提取物对大肠杆菌O157、阪崎肠杆菌、单增李斯特菌等显示较强的抑菌活性。高效液相色谱分析结果表明,提取物中含有芦丁、没食子酸、绿原酸和儿茶素等活性组分。芡种壳提取物具有很强的抗氧化活性和一定的抑菌活性,与其中丰富的多酚物质密切相关,作为天然抗氧化剂具有一定开发潜力。      

紫铜换热管与不锈钢管板接头的TIG焊

通过焊接工艺评定试验及生产实践,确定了紫铜T2与不锈钢0Cr18Ni10Ti相焊时,采用与不锈钢、紫铜无限固溶的镍基焊接材料进行手工钨极氩孤焊的方法,用制定的工艺规范参数进行施焊,有效地改善了焊缝金属的力学性能,避免了铜的渗透裂纹的出现,获得了满意的焊接接头质量.证明所确定的焊接材料及焊接工艺是合理、可靠的.     

开关磁阻电机数字控制系统的研究和实现

该文介绍了以数字信号处理器(DSP)芯片TMS320F240为核心并结合现场可编程门阵列(FPGA)的开关磁阻电机调速系统(SRD)的数字化控制系统的设计。该文设计了硬件电路和软件控制策略,控制策略采用模糊算法,硬件设计采用DSP和FPGA为核心实现了开关磁阻电机调速系统的全数字化。仿真与试验均表明,本文设计的开关磁阻电机调速系统具有高效、实时、动态性能好、噪声低、转矩脉动明显减少等优点。     

芡实多酚提取条件分析

芡实是水生植物芡的种仁,营养丰富,是一种珍贵的天然补品和中药原料.采用溶剂浸提法对芡实中多酚物质的提取条件进行分析和优化.结果表明:溶剂、料液比、pH值、温度和提取时间等条件均会影响芡实中可提取总酚的含量.经优化后的提取条件是:采用pH值为1.49的50%(体积分数)丙酮水溶液,在料液比为1:15(g/mL),于40℃水浴中提取1h,重复提取3次.在此条件下,芡实中可提取总酚含量为0.261 mg/g.     

Semisolid die forging process,microstructures and properties of AZ31 magnesium alloy mobile telephone shells

A semisolid slurry of AZ31 magnesium alloy was prepared by vibrating wavelike sloping plate process,and the semisolid die forging process,microstructures,and properties of the magnesium alloy mobile telephone shell were investigated.The semisolid forging process was performed on a YA32-315 four-column universal hydraulic press.The microstructures were observed by optical microscopy,the hardness was analyzed with a model 450SVD Vickers hardometer,the mechanical properties was measured with a CMT5105 tensile ...     

Ca、Mn对镁合金凝固组织的影响

通过对镁合金铸锭后显微组织的观察,结合SEM能谱分析,研究了Ca、Mn元素对镁合金组织的影响.通过研究,发现Mg-2.0Mn的显微组织是由基体组织(α-Mg)和点状析出的组织(α-Mn)组成;Mg-0.5Ca的显微组织是由(α-Mg)基体组织和非平衡结晶形成的Mg2Ca相组成.Ca、Mn对镁合金的组织均有细化作用,当同时加入Ca、Mn合金元素时,镁合金的显微组织会更加细小,晶粒趋于均匀圆整,同时第二相颗粒减少.其原因是:Ca提高了Mn与镁合金的润湿性,提高了Mn的溶解与扩散能力,温度降低Mn原子从合金中析出,为合金凝固提供了大量的晶核.     

Intradermal tophi in gout: a case-control study

OBJECTIVE: To describe the characteristics of intradermal tophi in patients with gout and search for factors associated with their development. METHODS: This is a case-control study of patients with gout: cases (Group A, n = 21) had intradermal (not subcutaneous) plaques of monosodium urate (MSU) crystals located in sites distant to articular or paraarticular structures, and controls (Group B, n = 42) had gout but no intradermal tophi. Both Group A and Group B were paired by sex, age (+/-5 years), and duration of the disease (+/-3 years). Analysis included serum and urinary uric acid levels at first visit, radiographic stage of gout, the presence of associated diseases, and previous therapy, specifically, chronic glucocorticoid and diuretic usage. RESULTS: Intradermal tophi were located in the legs, forearms, buttocks, thighs, arms, and abdominal wall. Patients in Group A had a greater number of nonintradermal tophi in common sites (11.9+/-12.5 vs. 4.2+/-7.9, mean +/- SD; p = 0.018), decreased glomerular filtration rate (46.74+/-25.11 vs. 70.87+/-30.18 ml/min; p = 0.042), advanced radiographic changes (57.2 vs. 7.1%; p = 0.0001), and longterm glucocorticoid self-medication (76 vs. 36%; p = 0.006). We found no differences in other associated diseases between groups. CONCLUSION: Intradermal tophi were commonly found in the legs and forearms, and less frequently in the buttocks, thighs, and abdominal wall of gouty patients, and were associated with longterm self-prescribed glucocorticoids and chronic renal failure. The occurrence of intradermal tophi in these patients appeared to correlate with advanced disease.     

白酒中风味物质分析研究进展

白酒是我国传统而又独具特色的蒸馏酒,也是世界六大蒸馏酒之一。白酒中含有多种风味化合物,包括酯类、醇类、酮类、醛类、酸类、萜烯类、含硫化合物等,这些风味物质虽然含量很低,但风味物质的组成及含量对白酒口感和香味的贡献很大,是形成不同酒类风格的重要因素。该文主要对近年来白酒中风味物质种类、风味物质分析前处理技术、风味物质测定方法及功能性风味成分相关研究进行了综述,以期为白酒中风味物质分析与鉴定提供一定的参考。