Oxygen transmission rates of packages at ambient,chill and freezing temperatures measured by the AOIR method

The ambient oxygen ingress rate (AOIR) method is an alternative or supplementary method to Ox‐Tran for measuring the oxygen transmission rate (OTR) of packages. The method has high capacity, requires relatively inexpensive equipment and measures OTR at different temperatures and humidity conditions. The aim of this study was, on the one hand, to study the effect of temperature on the OTR for packages produced from different polymer materials and laminates, and on the other hand to evaluate the suitability of the AOIR method at freezing temperature conditions. The OTR for 10 packages with different polymer compositions was measured at 23°C, 6°C and ?25°C. The AOIR method was shown to be a reliable test method for measuring OTR of packages at all the applied test conditions, also at frozen storage temperature. The OTR for the packages decreased with lower temperatures, especially for the packages with the highest OTR values at 23°C. In order to avoid higher packaging expenses than necessary to obtain the required shelf‐life for different food products, the OTR for alternative packages should be measured at the temperature and humidity conditions of intended use. Copyright © 2004 John Wiley & Sons, Ltd.     

Assessment of oxygen levels in convenience‐style muscle‐based sous vide products through optical means and impact on shelf‐life stability

An optical oxygen analyser was used in two small‐scale industrial trials to non‐destructively assess the quality of packaged convenience foods and packaging process. Beef lasagne packed under 70% vacuum and cooked under standard sous vide conditions was monitored for residual oxygen, using disposable sensors incorporated in each pack and a benchtop optical oxygen analyser. High levels of residual oxygen close to ambient were determined in the majority of packs after packaging, as opposed to anticipated levels of 4–5%. Residual oxygen was monitored over product shelf‐life (4 weeks at +4–10°C) along with measurement of microbial growth and lipid oxidation in food by conventional destructive methods. Oxygen levels in packs went down to almost zero between weeks 2 and 3 indicating deterioration of packaged product. Correlation between oxygen profiles and the rate of microbial growth and lipid oxidation was established. The optical oxygen sensor system was shown to provide valuable information about performance of the packaging process, product storage conditions and food quality in a convenient and cost‐efficient fashion and non‐destructively. Copyright © 2004 John Wiley & Sons, Ltd.     

稀土对鸡胚胎生物效应的影响

选用鸡胚作为实验对象,La、Eu、Y作稀土实验代表元素,对不同孵化期进行了跟踪性实验。结果发现不同稀土在各孵化期对胚胎平均体重的影响有较大差别,且孵化期与减重无线性关系,其中以Eu减重最多,La最少。稀土在胚胎中的含量,随孵化时间增加而增加,但不同稀土元素其屏障作用差别较大。     

氟化钕中杂质氧、氮的测定方法研究

研究了NdF3中杂质氧、氮的测定方法。针对NdF3高温易挥发、分解的特点和F2可能产生的腐蚀性，选择适宜的加热温度、使用镍助熔剂和适宜的浴料，选用标准坩埚进行试验，并在加热炉出口安装卤素陷阱，获得了满意的分析测定效果。对含氧0．57％，含氮0．022％的试样，分析精密度为氧5．9％，氮6．7％，加标回收率氧为95％～100％，氮为90％～1050%。该方法也可用于其他稀土氟化物分析。     

采用BOF-LF-CC工艺试制20MnVB钢

借鉴国内钢厂电炉工艺生产20MnVB钢的成功经验，设计出20MnVB钢的内控成分并强化转炉终点控制、LF加钛保硼工艺、低过热度浇注、合理的轧钢工艺等，实现了BOF-LF-CC工艺生产汽车用优质含硼钢。     

卧式连铸铜锭坯连接式分体炉

国内外卧式连铸铜锭坯，绝大多数生产厂家均采用熔化炉与保温炉分开的，在铜液体从熔化炉往保温炉倾注时，会从空气中吸收大量的氧。在连接式分体炉中，熔化炉与保温炉是连通整体式的，熔融铜液体与空气隔离，含氧量很少，可达无氧铜级。     

冶金企业需求管理多维数据模型

在冶金企业供应链管理流程创新过程中 ,为了提高用户满意度和计划精度 ,必须建立需求管理的多维数据分析平台。本文介绍了E R关系模型和多维数据模型的一些基本概念 ,着重介绍了需求管理的多维数据模型设计。     

排烟含氧量测量中的不确定度分析

排烟氧量测量的可靠性对炉窑的经济运行和环境保护具有重要意义，在影响测量结果可靠性的诸多因素中尤以取样系统的影响为最。本文着重闸述这一因素对测量过程和测量结果的影响，给出一种符合GB10184标准要求的新型取样系统，并对这一取样系统进行全面分析。     

话语重复功能新探

传统文体学和文本话语分析没有把话语重复放在动态的语境中来考察,随着心理学的发展和认知科学的兴起,话语生成的原因和意图得到更为科学合理的解释.基于重复是人类话语活动的普遍现象,本文试图以人为认知的主体,以语境为认知的本原,用动态的语境观从生理和人际关系方面来探讨话语重复的语用功能,推论话语重复是用来实现施为用意,达到交际者行为上的互动.     

氢、氧对TCA机械性能和表面质量的影响

钛合金由于其比重小、重量轻、耐腐蚀性能好，在航天、航空和军事领域应用广泛。空间相机大量采用TC4做结构件，相机在空间承受温度场的作用，应力状态会发生变化。另外钛化学活泼性极高，氢、氧元素在工件加工和使用时进入钛合金内部，并对其机械性能和表面质量产生影响。本文介绍了氢、氧对钛合金的机械性能和表面质量的影响规律。