Effect of storage temperature on phenolics stability in hawthorn (Crataegus pinnatifida var. major) fruits and a hawthorn drink

The stability of five major phenolics, namely (−)-epicatechin (EC), procyanidin B₂ (PC-B₂), chlorogenic acid (ChA), hyperoside (HP) and isoquercitrin (IQ), in hawthorn fruits and a canned hawthorn drink were evaluated during 6 months of storage in the dark at three different temperatures (4, 23 and 40 °C). HPLC with a diode-array detector was used to determine the contents of the individual compounds. The results showed that the studied phenolics in the hawthorn fruits and the drink were both stable at 4 °C and relatively unstable at 23 and 40 °C with varied extents of degradation. At room temperature (23 °C), marked degradations of EC and PC-B₂ were observed in both the fruits and the drink with around 50% and 30% decrease after a 6-month storage, respectively. A more significant decrease of the phenolics was observed at 40 °C, especially for EC and PC-B₂, which were almost completely degraded after a 6-month storage. HP, IQ and ChA were relatively stable at 23 °C, but unstable at 40 °C. Therefore, low-temperature storage is recommended for maintaining the quality and efficacy of hawthorn fruits and its preparations.     

Study on phase behavior–impact strength relationship of unsaturated polyester/polyurethane hybrid polymer network

The phase behavior of a hybrid polymer network (HPN) composed of poly[(propylene glycol maleate)-co-(propylene glycol phthalate)] crosslinked with styrene and polyester–urethane crosslinked with methylene-bis-ortho-chloroaniline was examined. The correlation between phase separation and impact strength of the HPNs is discussed. The composition of HPNs has an effect on their properties.     

Fishtail magnetization in single crystal Tl2Ba2CuO6

We report extensive magnetization measurements on single crystals of Tl₂Ba₂CuO₆ superconductors. The fishtail magnetization is found to disappear above a characteristic temperature (60 K), which corresponds to a crossover temperature in the temperature dependence of the irreversibility line. Since the low temperature irreversibility field can be modeled by a Josephson coupled layered system, we propose that the fishtail magnetization in the Tl₂Ba₂CuO₆ system is due to dimensional crossover.     

地电位升高对通信设备的影响及其防护

针对电力通信系统运行特点,着重对电力系统接地故障引起的地电位升高及其对通信设备的影响进行了分析,提出了相应的保护措施,并介绍了两种保护装置。     

合肥市西区城市副中心

引言改革开放以来,我国城市建设在经济的快速发展中取得了巨大的成就。但随着信息化水平的不断提高,文化情趣趋同、城市空间趋同、建筑造型趋同,城市出现了千篇一律、千城一面的尴尬局面。城市逐渐从自然中独立,割裂着人与自然之间千丝万缕的联系。     

炼油厂储罐喷铝内防腐效果分析

分析了炼油厂储罐内壁受到腐蚀的原因,简要介绍了喷铝加传统封闭涂料的防腐工艺及其应用效果,探讨了该防腐工艺的失效机理,并提出了改进措施。     

不对称盒形件落料拉伸复合工艺及其模具设计

通过工艺分析，对传统工艺进行了改进，采用了落料拉伸的复合结构应用于不对称的盒形零件的加工，解决了单工序模由于零件形状不规则而产生的定位不可靠、下料繁琐等问题。介绍了复合模具的结构设计及工作过程.经生产验证，该模具性能可靠，运行平稳，提高了产品质量和生产效率，降低了劳动强度和生产成本。     

单片图像压缩与USB高速传输技术应用

数字图像压缩与高速传输技术已经在工程中得到了广泛应用,然而随着飞行器的小型化,功耗、体积及重量的限制增大,不能直接应用。因此介绍一种实用的低功耗、小体积实时图像压缩与传输技术及其系统构成,并对单片JPEG2000芯片与USB2.0数据流传输技术应用进行分析,对系统配置及软件开发的主要步骤分别说明。采用该技术可以有效解决小型移动目标图像实时传输难题,与计算机接口兼容性好,可靠性高,具有较强的工程实用性。     

辅助气体对CO_2激光焊接光致等离子体屏蔽的影响

采用２０ｋＷＣＯ２激光加工系统焊接低碳钢，研究了辅助气体对等离子体屏蔽临界功率密度的影响。研究结果表明，辅助气体不同时等离子体屏蔽临界功率密度由小到大的排列顺序为：Ａｒ→Ｎ２→ＣＯ２→Ｈｅ。Ａｒ作为辅助气体时，等离子体屏蔽的临界功率密度可以低至１．８５×１０６Ｗ／ｃｍ２。辅助气体对等离子体屏蔽临界功率密度的影响主要取决于气体的导热性和解离能，相比而言，气体电离能的影响是次要的。采用Ａｒ作为辅助气体时，等离子体屏蔽临界功率密度低的原因主要在于Ａｒ的导热性能差，激光支持的燃烧波（Ｌａｓｅｒ－ｓｕｐｐｏｒｔｅｄＣｏｍｂｕｓｔｉｏｎＷａｖｅｓ—ＬＳＣ）波容易过热和扩展。