疏水增强型淀粉/PVA生物降解膜的性能

以烷基烯酮二聚体为疏水化组分,环氧改性聚酰胺为增强交联组分制备了疏水增强型淀粉/聚乙烯醇膜。动态接触角和吸水率测试表明,烷基烯酮二聚体能大幅度提高膜的疏水性能,较佳的烷基烯酮二聚体含量为3.30%,疏水增强型淀粉/聚乙烯醇膜接触角可达90°,吸水率低至15.44%。环氧改性聚酰胺能明显改善膜的拉伸强度,但环氧改性聚酰胺含量过高对断裂伸长率不利。X-射线衍射表明烷基烯酮二聚体的内增塑作用和环氧改性聚酰胺的交联特性可增加膜的相容性。生物降解测试显示,疏水增强型淀粉/聚乙烯醇膜具有一定的生物降解性,但环氧改性聚酰胺使膜的生物降解性能下降。     

论烟草良好农业规范的基本要素

烟草良好农业规范(GAP)是保证烟叶安全质量的全生产过程操作规范,其基本要素包括自然条件评价和生产风险评估、保护自然资源、经济利用和管理设施设备、关注员工培养和健康福利、严格化学投入品管理、减少农药残留危害、规范烟叶种植和初加工管理、控制非烟物质、实现烟叶生产的信息化管理和质量追溯等。     

七叶树叶提取物抗氧化性能的研究

采用不同溶剂从七叶树叶中提取有效成分，并用乙酸乙酯萃取，将所制得提取物干品定量加入油脂中，通过对强化保存期间过氧化值（ＰＯＶ）的测定表明，以体积分数７０％乙醇为溶剂的提取物的抗氧化性能最优，在油脂中的添加量为０．０８％时效果最佳，且超过０．０２％的ＢＨＴ。化学预试法和薄板层析法初步鉴定出：体积分数７０％乙醇提取物中含有酚类及鞣质、有机酸、黄酮类化合物、植物甾醇等活性成分。     

Effects of hydrophobic and hydrophilic organic matter on the water repellency of model sandy soils

Soil water repellency affects the hydrological functions of soil systems. Water repellency is associated with the content and the composition of soil organic matter. In the present study, we examined the effects of hydrophobic and hydrophilic organic matter contents, the hydrophobic/hydrophilic organic matter ratio and the total organic matter content on water repellency using model sandy soils. Stearic acid and guar gum were used as the hydrophobic and hydrophilic organic compounds, respectively. Water repellency was estimated using the sessile drop method. Hydrophobic organic matter content was found to be the dominant factor affecting soil water repellency. Hydrophilic organic matter was found to increase the contact angle to some extent without the presence of hydrophobic organic matter. With the presence of both hydrophobic and hydrophilic organic matter, the effects of the hydrophilic organic matter content on contact angle were found to be dependent on the hydrophobic organic matter content of the soil. This relationship was explained by the differences in the surface free energies of different organic matter and mineral surfaces. The contact angle increased with increasing hydrophobic/hydrophilic organic matter ratio when the hydrophilic organic matter content was constant. When the hydrophobic organic matter content was constant, contact angles were roughly comparable, irrespective of the hydrophobic/hydrophilic organic matter ratio. The contact angles were not comparable at each total organic matter content. Accordingly, the hydrophobic/hydrophilic organic matter ratio and the total organic matter content in soil may not provide satisfactory information about soil water repellency.     

Nitrogenous constituents in nest soils of harvester ants (messov ebeninus) and their influence on plant growth

Abstract

As a corollary of a detailed study on the ecology of the Harvester ants in soils of semi‐arid natural pastures, samples from a loessial Arid Brown soil were analyzed for the content of nitrogenous constituents (humic compounds, amino acids, nitrates, ammonia) as well as phenols and carbohydrates and the nutrient status of the soil.

While there was a significant increase in fulvic and humic acids in the ant nests, the simultaneous decrease in amino acids ‐ in relation to the surrounding soil ‐ indicates that the humic substances have been synthesized from amino acids and the abundantly present phenols and possibly carbohydrates.

The much higher concentration of nitrogen compounds in the ant mounds supports the idea that the soil mixing activity of the Harvester ants enhances microbiological processes and in turn the fertility of the mounds, as evident in the better growth of the pasture plants.     

Physiological Effects of Salicylic Acid and Thiourea on Growth and Productivity of Maize Plants in Sandy Soil

This study aimed to investigate the response of vegetative growth, yield, and some metabolic constituents of maize grains cv. Single Cross 124 to foliar applications of salicylic acid (SA; 100, 200, and 400 mg L^?1) and thiourea (TU; 500, 1000, and 1500 mgL^?1), two bioregulators, either alone or in combination. The foliar application of SA and TU alone significantly increased stem diameter, number of leaves?/?plant, leaf area, total dry weight?/?plant, leaf area index, net assimilation rate, specific leaf weight, and yield (i.e., ear length, ear diameter, number of grains?/?row, number of rows?/?ear, 100-grain weight, grain yield?/?plant, grain yield?/?fed (1 feddan = 4200 m²), harvest index, and shelling percentage) by increasing SA or TU concentrations up to 200 and 1500 mg L^?1, respectively. Salicylic acid and TU, when applied alone, significantly improved the nutritional value and quality of maize grains by increasing crude protein, total soluble sugars, total free amino acids, and total soluble phenols.     

不同斥水剂作用下土壤斥水度测定及其变化规律

为获得不同斥水剂作用下土壤斥水度的变化规律,分别采用十二烷基硫酸钠、硅烷偶联剂KH-550与二氯二甲基硅烷改性砂土和十八烷基伯胺改性黏土,获得了不同斥水程度的改性土壤,并采用滴水穿透时间法、酒精溶液入渗法和接触角测定法获得了改性后土壤的斥水度及其随时间变化规律。结果表明:1)二氯二甲基硅烷改性砂土表现为极度斥水等级,且斥水性长期稳定,可作为制备斥水砂土的优选;硅烷偶联剂改性砂土的斥水性初期不明显,随着时间增长明显增强,最终可达极度斥水等级;但此类改性砂土易结块,均匀性及分散性较差,不推荐作为制备斥水砂土的优选;十二烷基硫酸钠改性砂土的斥水性不明显,且改性方法复杂耗时,不宜用来制备斥水砂土。2)当十八胺含量分别为0.2%、0.3%和0.6%时,改性黏土分别可达中等、严重和极度斥水等级,斥水性长期稳定,可作为制备斥水黏土的优选。3)将十八胺含量为0.5%的改性黏土掺入天然砂土混合制得的改性混合土,亦有不同程度的斥水性。当改性黏土含量为1%~3%时,改性混合土尚无明显斥水性;当改性黏土含量为3%~10%时,改性混合土斥水等级为中度;当改性黏土含量为10%~50%时,改性混合土斥水等级可达到严重。该成果可为深入研究土壤斥水性及其工程应用提供参考。     

Repellancy and contact toxicity of clove bud oil and its constituents against German cockroaches,Blatella germanica (Dictyoptera: Blattellidae), under laboratory conditions

Abstract

The German cockroach, Blattella germanica L. (Dictyoptera: Blattellidae), an invasive pest of human habitats, is distributed throughout the world, except in Antarctica. They have developed resistance against chemical pesticides used for the management of their populations. Numerous essential oils and their constituents have been tested; however, the insecticidal activities of clove bud powder, oil, and their constituents have not yet been tested against the German cockroaches. Thus, in this study, clove bud powder, oil, and their major constituents, eugenol and eugenol acetate, were evaluated for their contact toxicity and repellancy against adult German cockroaches under laboratory conditions. The clove bud powder applied at 30?mg/cm² killed 92% of German cockroaches at 6?hours after treatment (HAT). Similarly, clove bud oil, eugenol and eugenol acetate applied at 4.00?ml/cm² provided 95%, 85%, and 87% German cockroach mortality at 24, 6, and 24 HAT, respectively. At 2.0?ml/cm², clove bud oil repelled 80% of German cockroaches within 30?min. In contrast, eugenol and eugenol acetate repelled 85% at 1.0?ml/cm² and 2.5?ml/cm², respectively, at 0.5 HAT. Based on this study, clove bud powder, oil, eugenol, and eugenol acetate could be environmentally friendly tools for the management of German cockroaches.     

脱水热处理改善鱼皮明胶可食膜的性能

为了改良鱼皮明胶可食膜的性能,拓宽可食膜的资源,以罗非鱼皮为原料提取明胶制备可食膜,考察了脱水热处理对其理化性质的影响。结果发现罗非鱼皮明胶中亚氨基酸含量为19.3%,主要由β链和α链组成,制备的可食膜其抗拉伸强度（tensile strength,TS）达37.5 MPa。80℃热处理对明胶膜的理化性质无明显的影响。当热处理温度提高到100℃或120℃时,伴随热处理明胶膜的TS逐渐增大而溶解性逐渐降低。在热处理过程中,膜的颜色略微变黄,但断裂延伸率和透明度却无明显的变化。SDS-PAGE 图谱和明胶膜在蛋白变性剂中的溶解性结果显示,高于100℃的热处理使明胶α链和β链发生交联,增强疏水相互作用和共价键在明胶膜中的贡献,使膜的玻璃化转变温度得到提高。以上结果表明,脱水热处理可改善鱼皮明胶膜的机械性能、耐水性能和热稳定性,有利于拓宽可食膜的资源和鱼皮明胶膜的应用。     

白车轴草挥发油化学成分研究

本文利用ＧＣ－ＭＳ－ＤＳ联用技术对白车轴草挥发油的化学成分进行了研究，在已分离的８２个成分中，鉴定了其中的６９个化合物，占总含量的９２．７１％。δ－杜松醇（１３．４４％），正十八醛（１２．８７％），香叶醇（１１．９６％），十八碳二炔－９．１１－酸甲酯（７．４８％）和表毕澄茄稀醇（５．１１％），为该挥发油的主要成分。