从精细电子印刷看网印制版技术进展

网版印刷模版简称网版,它是影响网版印刷质量的最重要的因素之一。对于高精度的网版印刷作业而言,高精度的网版就显得尤为关键,从这一个层面上讲,网版质量的好坏、     

Multicomposition analysis and pattern recognition of Chinese geographical indication product: vinegar

Multicomposition fingerprints with several chemical compositions containing inorganic elements and organic compounds (amino acids, polyhydric alcohols, organic acids) were measured to distinguish two geographical indication-protected vinegars (GIs) from general vinegars (nGIs). The two of GIs were named Shanxi extra aged vinegar and Zhenjiang vinegar from Shanxi and Jiangsu province, respectively. Principal component analysis and Fisher linear discriminant methods were applied for the pattern recognition and classification of GI product. It was not suitable by simply using one kind of composition to make a distinction between GIs and nGIs. However, by using multicomposition to build a classify model, the classification of SXVs was described by Co, As, Al, Mg, Ca, erythritol, arabitol, sorbitol, proline, lysine and pyruvic acid, while ZJVs classification was described by threonine, serine, glycine, lysine, Ba, erythritol, xylitol and lactic acid. The GI samples can be classified with high accuracy according to the discriminant model, of which the false rate is 3.88 % in SXVs model and 10.85 % in ZJVs model. This method can be a useful method for protecting the geographical indication vinegars from the fake or adulterate vinegar commodities.     

聚甲醛纤维的染色性能

采用分散蓝2BLN、分散大红3B和分散黄棕S-2RFL染料对聚甲醛(POM)纤维进行染色.考察了染色温度和染色时间对染料上染率和纤维透染性的影响.结果表明,三只分散染料对POM纤维的上染性能相似,其上染平衡温度分别为100℃、110℃和110℃.分散蓝2BLN的最大上染率较低,为80％左右;分散大红3B和分散黄棕S-2RFL的最高上染率均可达90％以上.POM纤维在110℃上染30 min后,无白芯,纤维被透染.     

Heat acclimation and the role of RpoS in prolonged heat shock of Escherichia coli O157

Escherichia coli, a commensal mesophile that primarily inhabits the gastro-intestinal tract, responds to temperature up-shifts with transient expression of stress-response proteins. The goal of this study was to identify adaptive proteins of E. coli O157 crucial for growth resumption of this human pathogen after heat shock, with specific focus on the role of the RpoS sigma factor. Using the comparative proteomic analysis of hyper-thermally acclimatized wild-type strain B-1 and rpoS-mutant strain SV521, we identified 39 proteins that underwent significantly-different induction upon temperature shock at 45°C or rpoS mutation. All identified proteins of the heat post-acclimation stimulon fell into two large sub-groups: (i) stress proteins, including molecular chaperons, proteases, DNA/RNA stabilizing enzymes, and anti-oxidant proteins, and (ii) housekeeping proteins. It was found that in the heat stress stimulon RpoS has significantly (P=0.012) limited control over the key stress proteins involved in translation, translational elongation, protein folding and refolding. However, RpoS showed a significant (P=0.035) control over the cellular metabolic processes that included NADPH regeneration, pentose-phosphate shunt, nicotinamide nucleotide and NADP metabolic processes, reflecting its specific importance in promoting resource utilization (energy, protein synthesis etc.) during proliferation of hyperthermally-adapted cells. Pathogenic strains, like E. coli O157, have the ability to survive a variety of harsh stress conditions, leading to their entry into the food chain, and subsequent pathogenesis. This research offers insights into the physiological response of this pathogen during the critical period following adaptation to thermal stress and subsequent resumption of growth.     

超高分子量聚乙烯纤维的表面改性研究

针对超高分子量聚乙烯纤维表面黏结性差的缺点,采用超声下铬酸溶液处理纤维表面。根据正交试验,分析了处理过程中影响纤维性能的因素,并对各单独因素进行了探讨。通过SEM和FTIR分析了处理前后纤维的结构变化,并用自制的单丝抽拔装置对纤维黏结性进行了表征。结果表明:温度是影响处理纤维效果的最主要因素,低于60℃时,对纤维表面仅进行了刻蚀;温度达到60℃时,在纤维表面产生了极性基团,且表面刻蚀和产生极性基团都提高了纤维的黏结性。     

Chicken muscle homogenate gelation properties: effect of pH and muscle fiber type

Gelation properties of chicken breast and thigh muscle homogenates at a protein concentration of 4.5% under different pH conditions (5.80–6.60) and those of myofibrillar proteins at a protein concentration of 2% were compared to determine the influence of muscle fibre types on gelation. The optimal gelling pH for breast muscle homogenates (pH 6.30) was slightly higher than that for thigh muscle homogenates (pH 5.80–6.30), a similar trend was found for the isolated chicken myofibrillar proteins (pH 6.00 for breast and 5.50 for leg). Similarly, the pH values at which breast muscle homogenate gels were weaker (pH<6.20) or stronger (pH6.20) than thigh muscle homogenate gels were higher when compared with chicken breast and leg myofibrillar protein gels (pH<5.80 and pH>5.90, respectively).     

脱氧雪腐镰刀菌烯醇的生物降解研究进展

脱氧雪腐镰刀菌烯醇(deoxynivalenol)作为分布最广泛的镰刀霉毒素之一,不但给全球粮食产业造成巨大经济损失,也给人类健康带来潜在威胁。文中对清除脱氧雪腐镰刀菌烯醇的物理、化学和生物方法进行了综述,为在食品中有效控制其水平提供了思路。     

葡萄酒中赭曲霉素A测定方法的研究

采用固相萃取小柱对葡萄酒中的赭曲霉素A(OTA)进行浓缩处理,选择高效液相荧光法和超高效液相质谱联用法,分别测定葡萄酒中的OTA含量。采用HPLC-FLD法测定葡萄酒中OTA时,线性良好,R2=0.9997;经固相萃取小柱浓缩后,测定方法检出限可达到0.002μg/L;回收率为85.7%～102.6%;RSD(n=5)为4.5%。通过HPLC-FLD和UPLC-MS/MS测定OTA方法对比发现HPLC-FLD方法具有更好的灵敏度和检出限。     

Effect of Co γ-irradiation on postharvest quality and selected enzyme activities of Pleurotus nebrodensis

Freshly harvested Pleurotus nebrodensis fruit bodies were exposed to four different doses (0.8-2.0 kGy) of ⁶⁰Co γ-irradiation and various physiological changes associated with postharvest deterioration, as well as the activities of selected enzymes (proteinase, polyphenoloxidase, superoxide dismutase, catalase) thought to play a role in the process of deterioration, were monitored during 22 days of subsequent storage at 4 °C and 65-70% relative humidity. An irradiation dose of 1.2 kGy significantly delayed (by 6-9 days) the onset of fruit body softening, splitting and browning compared with non-irradiated controls and test samples subjected to lower or higher irradiation doses. Irradiation with 1.2 and 1.6 kGy also had a positive effect on other indicators of mushroom tissue senescence, resulting in smaller decreases in soluble protein levels and more protracted increases in proteinase activity. Peak levels of polyphenoloxidase activity, widely recognized as causing postharvest browning of mushroom tissue, were also significantly lower (P < 0.05) in fruit bodies exposed to 1.2 kGy compared with non-irradiated controls. Our data increase our understanding of the effects of γ-irradiation on the biochemical changes associated with postharvest deterioration in P. nebrodensis, and improve the prospects of more targeted strategies for extending the shelf life of both this and other mushrooms.     

武陵酒生产工艺创新剖析

湖南武陵酒是中国十七大名酒之一.是中国酱香型白酒三大代表之一,一度与茅台、郎酒齐名,是湘酒唯一的金牌白酒.武陵酒在秉承传统酱香型白酒的酿造工艺基础上大胆创新,赋予了武陵酒酱香馥郁、略带焦香、入口绵甜、优雅细腻的特有风格,深受消费者喜爱,具有很大的市场潜力.从中国酱香型白酒的发展前景、武陵酒发展以及其工艺创新等方面对湖南武陵酒进行了简要的剖析.