苯乙醇胺A及其残留检测方法研究进展

苯乙醇胺A作为一种新型的β-兴奋剂,具有促进动物蛋白质合成、提高饲料转化率的作用,但其在动物性食品中的残留物对人体健康构成威胁,故近年来引起各界学者的广泛关注。因此建立便捷高效的检测方法至关重要。主要介绍了苯乙醇胺A的理化性质、药理作用、代谢规律、毒理研究以及其在不同样品基质中残留检测的方法,对研究方法的开发与研究提供有益帮助。     

Effects of the amount and type of fatty acids present in millets on their in vitro starch digestibility and expected glycemic index (eGI)

This study investigated whether the amounts and types of fatty acids present in millet plays a role in its known hypoglycemic properties. In a two part study, the first part involved complexing excess amount (2 mmol/g of starch) of palmitic, oleic and linoleic acids to cooked pearl, finger, proso and foxtail millet starches, subjecting the complexes to in vitro starch digestibility and calculating their expected glycemic index (eGI). The second part of the study consisted of complexing the millet starches with the fatty acids in the amounts present in their respective millet flours. Elaidic acid in equal amounts to oleic acid was also used to ascertain the effects of the cis or trans configuration of the fatty acid on millet starch digestibility. The complex index (CI) of the fatty acids with millet starch increased with increasing level of unsaturation. Significant (p < 0.05) reductions in the in vitro starch digestibility and eGI of the millet starch-fatty acid complexes were observed. Reductions in the starch hydrolysis of the samples were found to be significantly linked to the amounts of the fatty acids added. The presence of unsaturated fatty acids generally resulted in less starch being hydrolyzed. Oleic acid seemed to be a very effective fatty acid in reducing the amount of starch hydrolyzed. Trans oleic acid (elaidic acid) showed to be less efficacious compared to oleic acid in cis configuration. The amount and type of fatty acids interacting with starch plays a significant role in the hypoglycemic property of millet.     

预喷射控制柴油机NOx和烟度排放作用的试验研究

以某四缸电控高压共轨柴油机为对象,试验研究了预喷射在控制柴油机NOx和烟度排放中的作用。通过优化预喷射量、预喷与主喷间隔,寻求最佳的控制NOx和烟度的预喷参数。试验结果表明,预喷射在全工况范围内都能降低NOx的排放,但对降低NOx有力的措施却无法有效降低烟度;较大的主预喷间隔、较大的预喷量,NOx排放较低;适当的主预喷间隔、较大的预喷量有利于降低烟度;预喷射虽不能从根本上解决NOx和炭烟排放中的矛盾,但适当的主预喷间隔和预喷量可在烟度基本不变的情况下,大幅度降低NOx排放量。     

发酵安梨果酒实用加工技术

安梨果皮粗糙,鲜食价值较低,且加工工艺困难,严重限制了安梨的产业化发展和市场开拓。从原料选择、酶解、发酵、澄清和陈酿等方面介绍了安梨果酒的酿造加工工艺。     

香椿提取物对痛风抑制作用的初步研究

研究了香椿老叶提取物对痛风治疗过程中2种关键性酶(黄嘌呤氧化酶和环氧合酶-2)的抑制作用。结果表明,香椿提取物对黄嘌呤氧化酶有显著抑制功效,且呈剂量效应关系,其IC50为151.6μg/mL;香椿提取物对环氧合酶-2有明显的抑制作用(p<0.01),其IC50为2.66μg/mL,效果优于阳性对照。香椿提取物可有效降低尿酸水平,抑制环氧合酶-2的活性;香椿提取物具有较强的抗炎、抗痛风作用。     

基于热弹性流体动力润滑理论的内燃机主轴承油槽设计

建立了内燃机(ICE)主轴承热弹性流体动力润滑模型。预开设不同的油槽,计算研究了主轴承油槽的宽度、开设角度和位置对主轴承润滑性能的影响。结果表明,油槽的宽度对主轴承润滑性能有较大的影响,使主轴承处于最佳流体动力润滑状态的最佳油槽宽度只存在于一个较小的范围内,大约在(0.03～0.15)B(B为轴承宽度)之间;油槽开设的角度和位置同样影响主轴承的润滑性能;主轴承适合开设周向油槽,且油槽的角度取0°～90°或270°～90°时主轴承润滑性能较好。     

干旱条件下水肥耦合作用机理和效应

干旱问题是制约农业发展的主要逆境因素之一。发展节水农业是农业现代化的必然趋势,是解决农业水资源短缺,保证农业可持续发展的根本出路。而水肥耦合研究一直是节水技术研究的一个重要方面。概述了国内外水肥耦合研究的现状,从水肥耦合作用的机理和效应两方面来阐述,包括水分对植物养分转化、吸收及代谢的影响、养分对植物水分利用的影响、生物学效应、生态学效应和对生理指标的影响。并指出今后水肥耦合研究应该加强施肥对农产品品质和生态环境的影响的研究,同时注重构建通用性的水肥耦合模型。     

Hemicelluloses prior to aspen chemithermomechanical pulping: pre-extraction, separation, and characterization

A portion of hemicelluloses and acetic acid can be pre-extracted with dilute sulfuric acid prior to the aspen chemithermomechanical pulp process. The streams collected from the second press-impregnation stage after acid pre-extraction contain a significant amount of acid pre-extracted hemicelluloses. Most of the total sugars obtained from the pressate were xylan, in which xylan was further hydrolyzed to sugar monomers under the acid pre-extraction condition. To fully understand the characteristics of hemicelluloses yielded prior to pulping, the pre-extracted hemicelluloses were separated and characterized by FT-IR, (1)H NMR, and thermogravimetric analysis in this study. Most of the FT-IR bonds from the hemicelluloses agreed well with the other two spectra of birch xylan and CA0050 xylan, except a new absorption at 1734 cm(-1) contributed to acetyl groups. The hemicelluloses obtained from acid pre-extraction began to decompose significantly at about 225 °C, slightly lower in comparison with organosolv and alkaline hemicelluloses reported in the literature.     

排水暗管间距对滨海盐土淋洗脱盐效果的影响

为合理设计盐碱土灌排改良工程,提高盐碱土改良效果,该文通过田间试验,研究了排水暗管间距对滨海盐土淋洗脱盐效果的影响。结果表明,漫灌淋洗期间,吸水管间距埋设越小,小区暗管系统稳定排水流量越大,淋洗初期的排水矿化度也越大,排水排盐效率越高;相同淋洗用水量下,3m间距小区田间各点土壤脱盐比较均一,6、9m间距小区田间各点土壤脱盐效率相差较大,3次淋洗后3个小区田间各点0~1m深土体土壤脱盐率分别在70.93%～73.40%、64.68%～77.47%、56.54%～78.78%;利用暗管工程技术参数估算方法预测了淋洗改良后田间各点土壤含盐量,不同间距吸水管上方0~1m深土体土壤含盐量预测值与实测值差异较大,其他各点差异较小,预测误差率在±10%左右。排水暗管间距对田面各点土壤脱盐效果影响很大,盐碱土灌排改良应合理设计暗管间距和采取有效的淋洗措施。