脲酶测定法判定豆浆抗营养因子热失活情况研究

大豆抗营养因子的主要成分是胰蛋白酶抑制剂,在大豆制品加工过程中,通常采用高温加热钝化的方法使胰蛋白酶抑制剂失去活性。豆浆是人们日常生活中喜欢的饮品之一,因为脲酶测定方法比较简单,目前多以加热钝化后豆浆脲酶活性来表示抗营养因子的去除情况。本研究通过测定豆浆中胰蛋白酶抑制剂和脲酶的活性研究豆浆加热过程中二者失活是否具有一致性,判定以脲酶活性来体现豆浆安全的科学性,同时通过豆浆加热程度与胰蛋白酶抑制剂失活情况的关系,对家庭豆浆制作提供一种安全的加热模式。     

Thermal deactivation of high-affinity H2 uptake activity in soils

Soils are the most important sink for atmospheric hydrogen, which is assumed to be oxidized by abiontic soil hydrogenases or by putative high-affinity hydrogenases of microbial origin. The activity of soil hydrogenases has been found to change with soil temperature as it changes during the day and the season. However, it is unclear whether and to which extent the soil hydrogenases are deactivated by increased temperature. Therefore, we incubated soils from different climates and different ecosystems (forest, agricultural, arid, hyper-arid, paddy, peat) at elevated temperature and measured the residual activity at 25 °C after different incubation times. We found that at least part of the soil hydrogenase is deactivated irreversibly already at relatively low temperatures (>30 °C) and short exposure times (>10 min) and that the deactivation was more pronounced in soil from cold versus hot climate. The deactivation kinetics could be fitted to a biexponential model, but were complex with respect to soil type and deactivation temperature. The results show that new hydrogenase activity has to be generated in the soil to compensate for activity loss by diurnal and seasonally increased temperature.     

灭酶方法对燕麦淀粉和蛋白质体外消化特性的影响

为了解灭酶方法对燕麦淀粉和蛋白质体外消化特性的影响,采用炒制、常压蒸制和远红外烘烤三种灭酶方法处理燕麦籽粒,分析了燕麦全粉的营养成分、黏度特性及淀粉和蛋白质体外消化特性的变化。结果表明,炒制灭酶后燕麦全粉粗脂肪含量提高,而β葡聚糖和总淀粉含量降低(P<0.05);常压蒸制灭酶导致燕麦全粉中蛋白质、粗脂肪、总淀粉含量降低(P<0.05);远红外烘烤灭酶对燕麦营养成分影响不大(P>0.05)。灭酶处理后燕麦全粉的糊化温度均降低,常压蒸制和远红外烘烤提高了燕麦全粉的峰值黏度和最终黏度(P<0.05)。灭酶处理使燕麦全粉中抗性淀粉含量显著增加(P<0.05),对慢速消化淀粉的影响不大(P>0.05)。在蛋白质体外消化中,远红外烘烤后燕麦蛋白体外消化率最高,达到70.05%,而常压蒸制灭酶燕麦的蛋白质消化率最低,为62.80%。说明远红外烘烤灭酶处理对燕麦营养组分影响不大,更加有利于消化。     

车用发动机停缸模式下转速波动仿真

停缸技术可明显改善车用发动机的燃油经济性,但对其动力输出产生影响.通过建立发动机曲柄连杆多体模型,基于示功图和经验公式,分析了模型边界计算方法,仿真了发动机多种停缸模式的转速波动特性.结果表明,停缸工作模式的转速波动主要受发火间隔角的影响,减小工作缸负荷可降低转速波动.     

微波处理对香蕉多酚氧化酶活性的影响

微波辐射可有效抑制或钝化香蕉多酚氧化酶的活性。同功率微波条件下等质量不同厚度香蕉片多酚氧化酶的钝化速度、效果相同;在微波400 W的处理下,等质量不同厚度香蕉片该酶完全钝化的时间为45 s。     

中国卤虫卵孵化特性的研究

本文对山东埕口盐场、海南岛莺歌海盐场及青海柯柯盐湖天然采集的卤虫卵进行了孵化特性研究。埕口、莺歌海及柯柯的虫卵壳厚分别为9.7,11.4及13.2μm。在放入海水中进行孵化前上述三品系的卤虫卵分别在自来水中浸泡2,3及4小时能获得最佳孵化率。它们的最适孵化温度分别为25.6～28.5℃,27.0～30.0℃及27.0～33.0℃。最适孵化盐度分别为30,20及35％。孵化的同步性以“莺歌海”为最好,为6.4小时,“埕口”次之,为6.5小时,“柯柯”为7.4小时。 实验室内培养产卵后24小时内收集的虫卵用下列方法处理能终止虫卵的滞育状态:(1)埕口卤虫卵:浸泡于粗盐饱和溶液中2～3个月,孵化率可达91～94％。(2)莺歌海卤虫卵:浸泡于粗盐饱和溶液中2～5个月,孵化率可达80～91％。(3)柯柯卤虫卵:置于5℃2～3个月孵化率可达96～98％。用3％H_2O_2及3％甲醛溶液处理对终止滞育状态没有作用。天然采集的三个品系的卤虫卵用3％H_2O_2或3％甲醛溶液或用去壳溶液处理均可以提高孵化率。     

抗营养因子及其钝化方法

抗营养因子(ANF)是植物代谢产生的一些物质,它能破坏或阻碍营养物质的消化利用,并对动物健康和生长性能产生不良影响.本文对饲料中的几种重要的抗营养因子的作用机理及其钝化处理方法进行了综述.     

Paraquat and sustainable agriculture

Sustainable agriculture is essential for man's survival, especially given our rapidly increasing population. Expansion of agriculture into remaining areas of natural vegetation is undesirable, as this would reduce biodiversity on the planet. Maintaining or indeed improving crop yields on existing farmed land, whether on a smallholder scale or on larger farms, is thus necessary. One of the limiting factors is often weed control; biological control of weeds is generally of limited use and mechanical control is either often difficult with machinery or very laborious by hand. Thus the use of herbicides has become very important. Minimum cultivation can also be important, as it reduces the power required to work the soil, limits erosion and helps to maintain the organic matter content of the soil. This last aspect helps preserve both the structure of soil and its populations of organisms, and also sustains the Earth's soil as a massive sink for carbon, an important consideration in the light of global warming. The introduction of the bipyridinium herbicide paraquat in the early 1960s greatly facilitated weed control in many crops. Paraquat has the unusual property of being active only by direct spray onto plants and not by uptake from soil in which strong binding deactivates it. Together with its rapid action in light in killing green plant tissue, such properties allow paraquat to be used in many crops, including those grown by low-tillage methods. This paper reviews the ways in which agricultural systems have been and are being developed to make use of these properties, and provides a risk/benefit analysis of the world-wide use of paraquat over nearly 40 years.     

两种卤虫休眠卵的终止滞育及休眠卵的诱导发生

诱导大盐湖卤虫（Artemia.francisana)和东营卤虫（Artemia.sinina)产休眠卵，作为研究对象探讨了最适终止滞育的方法，结果表明：用20℃冰冻20d，3%的H2O215min处理对大盐湖卤虫休眠卵最有效，而4℃下饱和卤水浸泡25d对东营卤虫休眠卵最有效，研究还发现在不同盐度和温度的组合培养条件下得到的休眠卵，用同一种终止滞育方法处理后，其孵化育不同。     

生物炭配施微肥对菜园土壤有效态重金属含量的影响

【目的】研究生物炭配施微肥对土壤有效态重金属含量的影响。【方法】采用室内模拟试验,向重金属污染的菜园土壤中添加皇竹草生物炭、咖啡渣生物炭、花生壳生物炭和微肥(铁肥、锰肥和硅肥),分别在处理14和28 d时测定土壤中5种重金属(Cu、Pb、Zn、Cd和Ni)的有效态含量。【结果】添加了生物炭或微肥土壤中的有效态重金属含量均比对照组低。其中单一钝化剂处理中,皇竹草生物炭和硅肥的钝化效果较好。在复配试验中,皇竹草生物炭+铁肥对土壤重金属Cu、Pb和Cd的钝化效果较好,处理14 d后其有效态含量的降幅分别达32.94%、31.26%和21.21%,对土壤有效态Zn含量的降幅为6.82%,但对土壤Ni的钝化效果不明显;处理14 d后咖啡渣生物炭+铁肥对土壤重金属Ni和Zn有效态含量的降幅也分别达22.64%和10.35%,钝化效果显著;处理28 d后,花生壳生物炭+铁肥对土壤重金属Cu钝化效果最好,有效态Cu含量降幅达49.06%;咖啡渣生物炭+硅肥对土壤Ni和Zn钝化效果最好,有效态含量降幅分别达23.73%和9.72%。【结论】生物炭配施微肥对土壤有效态重金属含量降低的效果优于单施生物炭或单施微肥,其中,皇竹草生物炭配施铁肥可用于土壤重金属Cu、Pb、Zn和Cd复合污染的钝化。