超临界CO_2处理腐生酵母菌细胞内外pH值的变化

超临界CO2作为一种新型的非热杀菌技术受到普遍关注,但其杀菌机理尚未揭示清楚。文中研究了腐生酵母菌经超临界CO2杀菌处理后,细胞内外pH值的变化,并探讨了细胞内外pH值的变化与菌体死亡的关系。结果表明:经过10 MPa、37℃的超临界CO2处理,细胞外的pH值逐渐降低,细胞内pH值呈现先下降,后上升,又略微下降的趋势。在超临界CO2处理过程中,细胞外pH值的降低并不是导致细胞死亡的直接因素,但可以间接提高杀菌效果;胞内pH值的变化,扰乱了细胞的正常代谢功能,是导致细胞死亡的重要因素。     

Opportunities for improving plantation productivity. How much? How quickly? How realistic?

Biomass production may be increased through greater utilization of existing resources, planting more area, and by implementing intensive silvicultural practices. This paper reviews the potential of intensive silviculture to increase productivity of short and longer rotation hardwood and conifer plantations. Some silvicultural treatments produced long-term growth and site improvements: species and provenance choice, tree breeding, improving rooting volume, applying high rates of fertilizers, and irrigation, all showed this potential. Short-term gains resulted from changes to stocking rates, rotation length, planting practices, tillage, weed control, and applying starter doses of fertilizer or nitrogenous fertilizer to pole stands.The largest gains came from site selection, species and provenance choice, draining wet sites and correcting nutrient deficiencies, followed by tree breeding and irrigation. Choice of stocking level and rotation length, planting practices, weed control, and fertilizing pole stands gave potentially large benefits (>25% gains) for short-rotation crops (<12–15 years). They produced lower benefits for longer rotation plantations. Starter fertilizers, tillage and utilizing thinnings had relatively low gains. Disease and insect control were difficult to assess.Managers should consider their current management level and practices, costs and benefits, social and environmental factors, practicality, and the time required for the benefits to be achieved. Further, growth improvements measured in research studies typically are not achieved in the field, with 15–25% reductions being commonly experienced. Quality control could reduce these losses.     

Pt–free counter electrodes based on modified screen–printed PEDOT:PSS catalytic layers for dye–sensitized solar cells

One of the most highlighted advantages of dye-sensitized solar cells (DSSCs) consists in the possibility to apply simple and low-cost printing techniques and solution processable materials for their assembling. Here, we report on screen-printed Pt–free counter electrodes (CEs) based on poly(3,4–ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) dispersions with different content of rheological agent – hydroxyethyl cellulose (HEC). These PEDOT:PSS dispersions, having measured pseudoplastic and thixotropic rheological behaviour, were screen–printed onto FTO glasses. The content of rheological agent in PEDOT:PSS catalytic layers showed an effect on measured thickness, electrochemical properties, specific conductivity and subsequently on the evaluated photovoltaic performance of DSSCs. The PEDOT:PSS CE with the 0.03 wt% of HEC achieved the best electrochemical performance and specific conductivity (80 S cm⁻¹), the lowest thickness of 200 nm and transparency in VIS light spectrum over 60%. DSSCs based on this PEDOT:PSS CE reached the highest conversion efficiency of 4.2% which is only approximately 40% lower value than η=6.9% evaluated for Pt CE.     

1-MCP联合CA对梨冷藏期间褐变的影响

为探讨1-MCP处理对梨果实CO2敏感性的影响,以及为经过1-甲基环丙烯(1-MCP)处理的梨果实的贮藏提供技术参考,以莱阳梨果实为试材,研究了1-MCP单独或联合气调(CA)对梨果实常规冷藏及在0.7%和1.4%CO2条件下冷藏期间果心和果肉褐变的影响。结果表明:0.5μL/L 1-MCP以及0.5μL/L 1-MCP结合0.7%的CO2处理,可以延缓和降低冷藏和货架期间的果肉白度下降和果心褐变,且2个处理差别不显著(α0.05),其原因可能与抑制了果实多酚氧化酶活性,减少了果实多酚氧化有关。结论:适宜的1-MCP与CA组合可延缓冷藏莱阳梨果实果肉和果心褐变。     

辐照对峰甘板栗货架品质的影响

研究~(60)Co-γ射线辐照对真空包装峰甘板栗货架期指标的影响及其机制,初步确定延长货架期的最佳辐照剂量。通过~(60)Co-γ射线以0、0.5、1.0、3.0、3.5、4.0、4.5、5.0 kGy剂量辐照峰甘板栗,分别在贮存0、10、15、20、30 d时检测样品的微生物指标(菌落总数、霉菌及酵母数、大肠菌数、沙门氏菌数)、感官指标和理化指标。结果表明:辐照处理对峰甘板栗能够起到很好的杀菌作用;结合峰甘板栗感官品质评定及生理生化数据分析,辐照剂量为4.0 kGy时,可改善峰甘板栗感官质量并保持理化营养指标。初步认为,在4℃条件下,辐照剂量为4.0 kGy时,在微生物安全限量方面,使货架期延长至少20 d。     

黑曲霉β-葡萄糖苷酶的活性位点和耐热结构预测

以黑曲霉3.316基因组DNA扩增得到大小为2 080 bp的β-葡萄糖苷酶基因为研究对象,通过生物分析软件分析得出其可能含860个氨基酸残基,存在4个主要疏水区;其二级结构可能含有63.26%无规则卷曲、20.58%α-螺旋、16.16%β-折叠;发现其结构域具有(β/α)8 TIM桶域和(β/α)6夹层三明治域及纤维连接蛋白的Ⅲ-like域;根据β-葡萄糖苷酶相关结构预测其活性位点和耐热机理,发现其活性位点可能是(β/α)8 TIM桶域的Asp280和(β/α)6夹层三明治域的Glu509;211个位于疏水区的氨基酸残基、48个脯氨酸残基和α-螺旋可能与其热稳定性相关。     

Anti-inflammatory effects of phytochemicals from fruits,vegetables, and food legumes: A review

Inflammation is the first biological response of the immune system to infection, injury or irritation. Evidence suggests that the anti-inflammatory effect is mediated through the regulation of various inflammatory cytokines, such as nitric oxide, interleukins, tumor necrosis factor alpha-α, interferon gamma-γ as well as noncytokine mediator, prostaglandin E₂. Fruits, vegetables, and food legumes contain high levels of phytochemicals that show anti-inflammatory effect, but their mechanisms of actions have not been completely identified. The aim of this paper was to summarize the recent investigations and findings regarding in vitro and animal model studies on the anti-inflammatory effects of fruits, vegetables, and food legumes. Specific cytokines released for specific type of physiological event might shed some light on the specific use of each source of phytochemicals that can benefit to counter the inflammatory response. As natural modulators of proinflammatory gene expressions, phytochemical from fruits, vegetables, and food legumes could be incorporated into novel bioactive anti-inflammatory formulations of various nutraceuticals and pharmaceuticals. Finally, these phytochemicals are discussed as the natural promotion strategy for the improvement of human health status. The phenolics and triterpenoids in fruits and vegetables showed higher anti-inflammatory activity than other compounds. In food legumes, lectins and peptides had anti-inflammatory activity in most cases. However, there are lack of human study data on the anti-inflammatory activity of phytochemicals from fruits, vegetables, and food legumes.     

转金属硫蛋白基因平菇对初成年、衰老和铅中毒小鼠学习记忆能力的影响

本文研究了转金属硫蛋白基因平菇对不同模型小鼠学习记忆能力的影响。结果表明:在小鼠饲料中掺入1%转金属硫蛋白基因平菇干粉(相当于50～60kg体重的人每日摄食鲜菇1kg)可明显提高初成年小鼠和铅中毒小鼠的学习能力;增加剂量对成绩提高无进一步的作用。3.16%的掺入量对提高初成年小鼠的记忆能力有显著作用。但1%和3.16%两个剂量对D-半乳糖致衰老小鼠的学习记忆能力均未见有促进作用。     

预处理对欧李酒品质及抗氧化的影响

以欧李为原料,分别对欧李进行水浴和超声波预处理,采用分光光度法、pH值示差法、福林酚法分别测定不同预处理对欧李酒色调、色度、花色苷含量、多酚含量的影响,采用DPPH法和ABTS法研究抗氧化活性的变化,并探讨对应的欧李酒发酵过程中多酚含量和抗氧化活性的变化规律。结果表明,不同处理方式下的欧李酒在发酵过程中,色度、色调均呈下降趋势,发酵第12天时水浴组和超声波组与对照组相比无显著性差异(P>0.05);超声波组和水浴组花色苷含量显著高于对照组(P<0.05);多酚含量呈先升高后降低的趋势,发酵第12天时超声波组显著高于对照组(P<0.05);DPPH自由基、ABTS+自由基清除能力均在88%以上,具有较强的抗氧化性。相关性分析表明,欧李酒中的多酚含量与DPPH自由基、ABTS+自由基清除能力具有显著相关性(P<0.01)。     

Effect of high pressure processing on gastrointestinal fate of carotenoids in mango juice: Insights obtained from macroscopic to microscopic scales

High hydrostatic pressure (HHP) and high-pressure homogenization (HPH) were applied to mango juice to explore their effects on gastric retention rate (G-CRR), bioaccessibility (BAC) of total and individual carotenoids, and the corresponding mechanisms from macroscopic to microscopic scales. Compared to the control, both HHP and HPH at 50 MPa had no significant effect on BAC and G-CRR, whereas HPH at 100 MPa significantly increased BAC by 44.33% and G-CRR by 11.84%. Further HHP treatments (particularly at 400 MPa) on the 100 MPa-HPH-pretreated samples significantly increased BAC by 71.37% and G-CRR by 24.24%. Violaxanthins/esters were less stable than carotenes in the stomach, resulting in lower bioaccessibility of violaxanthins/esters. G-CRR and BAC were negatively correlated with the viscosity and particle size of juice, whereas they were positively correlated with the solubility/dispersibility of carotenoids. In addition, pectin-carotenoid interactions may also be an important factor affecting the digestive fate of carotenoids in juice.Industrial relevanceHigh pressure processing (High hydrostatic pressure, HHP, and high pressure homogenization, HPH) is a non-thermal technique and its effect on the bioaccessibility of carotenoids in fruits and vegetables have attracted attention from researchers. Our research found that HPH and HHP combined treatment could decrease the particle size of mango juice, and increase the viscosity and turbidity as well as the bioaccessibility of carotenoids therein. This technology can be used to preserve the physical stability of mango juice and improve the nutritional value.