Evolution of Quality Characteristics of Minimally Processed Asparagus During Storage in Different Lighting Conditions

ABSTRACT:  The effect of different types of lighting (white, green, red, and blue light) on minimally processed asparagus during storage at 4 °C was studied. The gas concentrations in the packages, pH, mesophilic counts, and weight loss were also determined. Lighting caused an increase in physiological activity. Asparagus stored under lighting achieved atmospheres with higher CO₂ and lower O₂ content than samples kept in the dark. This activity increase explains the greater deterioration experienced by samples stored under lighting, which clearly affected texture and especially color, accelerating the appearance of greenish hues in the tips and reddish-brown hues in the spears. Exposure to light had a negative effect on the quality parameters of the asparagus and it caused a significant reduction in shelf life. Hence, the 11 d shelf life of samples kept in the dark was reduced to only 3 d in samples kept under red and green light, and to 7 d in those kept under white and blue light. However, quality indicators such as the color of the tips and texture showed significantly better behavior under blue light than with white light, which allows us to state that it is better to use this type of light or blue-tinted packaging film for the display of minimally processed asparagus to consumers.     

基于数控加工的工艺分析

数控加工前对工件进行工艺设计是必不可少的准备工作,合理的工艺设计方案是编制加工程序的依据,对数控加工零件的工艺性分析,主要包括产品的零件图样分析和结构工艺性分析两部分.     

汽车用铝合金型材的性能改进

指出铝合金型材以其重量轻、性能优良、美观等特点,在汽车生产中用量日益增大。但对于后期还需要进行深(压力)加工的型材,如车门窗用型材,在性能方面则有一些特殊的要求。为此,笔者对该类型材的性能改进过程进行了阐述,其生产技术极具推广应用价值。     

气相色谱法测定焦麦芽中单糖的组成

建立了炮制中药焦麦芽中单糖组成测定的衍生气相色谱法。样品经水提取,三氟乙酸水解,糖腈乙酰化衍生后,用5%OV-17填充柱分离,FID检测器检测,内标法定量。鼠李糖、木糖、甘露糖和葡萄糖的检出限分别为1.21、1.08、2.14和2.40μg·mL-1(S/N=3),回收率均在80.0%以上,RSD不高于4.9%。在焦麦芽样品中检测出的单糖葡萄糖含量最大。     

Influence of an applied magnetic field on shielding current paths in a high TC superconductor

The influence of an applied magnetic field on shielding current paths in a bulk high T_c superconductor was investigated. This issue is very important for the quantitative analysis of levitation force, since the distortion and localization of the current paths have been found to be a major source of discrepancy between computed and experimental results. Furthermore, it has been speculated that the current paths vary, depending on the applied magnetic field. The magnetic field due to superconducting currents was measured by a Hall sensor when a permanent magnet was positioned at different gaps from a superconductor. The current paths were then reconstructed from the measured field data by an inverse analysis. A genetic algorithm, which is a robust probabilistic optimizing method, was used for the inverse analysis. It was found that the current paths merged into larger loops as the permanent magnet was retreating from the superconductor. It implies that a stronger applied magnetic field locally degrades the current density (J_c) and the shielding current paths are localized by these low-J_c areas which act as insulating boundaries.     

序批式活性污泥法-混凝工艺处理屠宰废水的试验研究

采用序批式活性污泥法（SBR）和混凝方法相结合的工艺处理屠宰废水，以肉鸡加工废水为处理对象的试验结果表明，SBR系统运行参数为：进水0.5h，曝气6.0h，沉淀1.0h，排水0.5h；进水COD800-1000mg/L，COD去除率为91％左右。再将出水进行混凝沉淀处理，其去除率75％左右，最终出水COD在30mg/L以下，达到回用水标准。