GC-MS测定4类食品接触材料中多环芳烃类化合物的溶出暴露水平

建立了食品接触材料中16种多环芳烃类化合物溶出暴露的气相色谱质谱联用(GC-MS)分析方法。样品以异辛烷为模拟物,按实际使用情况进行模拟浸泡实验,所得浸泡液用GC-MS进行分析。结果表明,食品接触材料中4种多环芳烃类化合物(萘、菲、荧蒽和芘)存在一定程度的溶出暴露水平,检出率分别为萘24.3%、菲77.1%、荧蒽48.6%、芘44.3%。其中部分食品用容器多环芳烃的溶出水平最高达33545 ng/kg(萘)、46296 ng/kg(菲)、17739 ng/kg(荧蒽)、15594 ng/kg(芘),并发现常规项目蒸发残渣(正己烷)的溶出与多环芳烃的溶出存在一定的正相关关系。萘、菲、荧蒽、芘等四项多环芳烃的方法平均回收率为76.5%~100.7%,相对标准偏差为1.0%~3.5%,本研究方法具有较好的准确度和精密度。     

Rheological investigation of alginate chain interactions induced by concentrating calcium cations

Chain interactions of sodium alginate during its gelation were investigated by a new gelation method which was based on a Ca²⁺-concentrating gelling process (CCGP) produced by water evaporation of an alginate solution containing CaCl₂. For two commercially available sodium alginate samples (low viscosity (LA) and medium viscosity (MA)) having different molecular weight distributions but the same G/M blocks, the critical Ca²⁺ concentrations for their gelation were found to be 4.6 (for LA) and 4.5 (for MA) μmol/mL after evaporating water from 1% of alginate solutions containing 4 μmol/mL of CaCl₂. The CCGP gelation method for alginate under the above conditions were confirmed by rheological measurements and the observed highly ordered and uniform mesh structure of the CCGP-formed alginate gels shown in cryo-SEM images. Combinations of LA and MA at different ratios (0:4, 1:3, 2:2, 3:1, 4:0 on weight basis) were studied using the CCGP gelation method to further the understanding of the alginate chain interactions during gelation. Different LA/MA mixtures exhibited different rheological properties in either non-gelled or gelled systems, indicating that the molecular weight distributions of the sodium alginates influence the alginate chain interactions mediated by Ca²⁺. Thus, an appropriate combination of LA and MA is required for a strong alginate interchain interaction during CCGP, and alginate products with desirable characteristics can be produced by manipulating the mixing ratios of sodium alginates having different molecular weight distributions even at the same total composition and distribution of G/M blocks.     

二级复合间接蒸发冷却技术在纺织空调的应用

通过对纺织厂细纱车间空调回风问题的分析,认为在细纱车间空调中采用二级复合式间接蒸发冷却技术,并对温度较高的工艺排风进行预处理后回用,可以较小的代价取得良好的冷却效果,为减少车间空调系统需冷量、改善纺织车间工作条件、纺织厂空调节能设计和改造提供技术依据.     

超声波防除麦草亚铵废液蒸发器积垢的研究

以亚铵法制浆废液为实验工质,对超声波防除制浆废液蒸发器积垢进行了研究。结果表明,超声波处理具有明显的阻垢功效,可降低废液积垢的生成速率,提高废液蒸发器的蒸发强度和传热系数。     

己内酰胺回收影响因素分析

根据化工蒸发原理,分析了消泡剂、原蒸汽压力、浓缩液排放温度、排放速度、换热效率对己内酰胺蒸发回收的影响因素,提出了生产控制的要点。     

热泵供热及烘缸干燥强度的研究

通过典型的纸机运行实例研究,证明采用自行研制的可调节式热泵供热系统用于造纸机干燥部,可明显提高纸机烘缸有效面积干燥强度、纸机车速和产量。     

基于模糊控制技术的糖厂蒸发过程液位自动控制系统研发

针对甘蔗糖厂蒸发工段的工艺和热力需求,运用模糊控制技术设计了低液面五效蒸发过程液位自动控制系统。文章分析了液位自动控制的难点,重点介绍了系统的硬件构建方案及应用软件中模糊控制器的设计思路和方法。     

多效蒸发真空系统的比较和分析

本文就多效蒸发几种不同的主真空系统和辅助真空系统的原理、形式做了介绍,同时对不同真空系统的优缺点和适用范围做了比较和分析,为企业和设计人员选择适合的真空系统提供了参考.     

回收利用味精生产的低压蒸汽

味精生产大部分能耗是来自汽耗,而耗汽单元操作排出的大量低压蒸汽（二次蒸汽）,目前基本上是采用水冷回收热量或直排大气.拟采用先进的蒸汽喷射压缩等工艺大力回收利用低压蒸汽用于生产,将较大幅度降低生产能耗.