Neglect of mowing and manuring leads to slower nitrogen cycling in subalpine grasslands

Nitrogen (N) availability in grasslands varies with agricultural land use. Traditional management regimes of mowing for hay and manuring in subalpine meadows maintain plant communities with exploitative functional strategies suited to fertile soils with fast turnover of nutrients. We investigated whether the neglect of traditional practices has led to a reduction in N availability in two parallel ecosystems (terraced and unterraced fields). Soil nitrate and ammonium contents were assessed using soil cores and ion exchange resins over a 1-year period, and assays of microbial nitrifying and denitrifying enzyme activities, made early in the growing season. A large difference in pH between the two ecosystems, caused by historical ploughing, facilitated greater N availability in terraced than unterraced fields. Abandonment of manuring and mowing caused a reduction in N availability and N transformation processes, which correlated with a shift in the plant community towards more-conservative functional strategies and greater dominance by grasses. We propose that positive feedback between the grassland management regime and dominant plant functional strategy maintained high N availability in these managed subalpine grasslands. When traditional practices of mowing and manuring are neglected, direct management effects combined with the spread of grass species with conservative strategies force down N availability in the soil, reduce microbial activity, change the pH, and lead to a long-term loss of characteristic herbaceous subalpine-meadow species.     

Effects of gamma irradiation on some mechanical properties of novoloid fibers

Novoloid fibers have high chemical, flame and thermal resistance; however they have low tensile properties. Effects of gamma irradiation on the tensile properties of novoloid fibers have been investigated. Loop and knot resistance have also been examined. Maximum tenacity of the single fiber increased with an increase of the radiation dose applied. According to the loop and knot tenacity results it is found that brittleness has been also affected by the amount of radiation dose.     

An evaluation of MES (2(N‐Morpholino)ethanesulfonic acid) and amberlite IRC‐50 as pH buffers for nutrient solution studies ∗

All buffering agents used to stabilize pH in hydroponic research have disadvantages. Inorganic buffers are absorbed and may become phytotoxic. Solid carbonate salts temporarily mitigate decreasing pH but provide almost no protection against increasing pH, and they alter nutrient absorption. Exchange resins are more effective, but we find that they remove magnesium and manganese from solution. We have tested 2(N‐Morpholino)ethanesulfonic acid (MES) as a buffering agent at concentrations of 1 and 10 mol m^‐3 (1 and 10 mM) with beans, corn, lettuce, tomatoes, and wheat. MES appears to be biologically inert and does not interact significantly with other solution ions. Relative growth rates among controls and MES treatments were nearly identical for each species during the trial period. The pH was stabilized by 1 mol m^‐3 MES. This buffer warrants further consideration in nutrient research.     

大孔树脂纯化山竹壳原花青素的研究

研究比较了10种大孔吸附树脂对山竹壳原花青素的吸附和解吸性能,筛选出最适的大孔吸附树脂,并对该树脂的静态和动态吸附条件进行研究.结果表明,大孔吸附树脂XDA-7对山竹壳原花青素有很好的吸附和解吸性能,最佳吸附和解吸条件为:吸附流速为2 BV/h,解吸液乙醇浓度为60％,解吸流速为2 BV/h,解吸液体积为6 BV.得到纯化的原花青素纯度为66.20％.     

Release Kinetics of Some Nutrients from a Sandy Loam Soil Treated with Different Organic Amendments

ABSTRACT

An incubation study was undertaken to examine the periodic release of some macronutrients and micronutrients in a sandy loam treated with different organic amendments (farmyard manure, mushroom compost, poultry manure, vermicompost, biogas slurry, and biochar of Lantana weed) added @ 15 t ha^?1 for 120 d through entrapment of released nutrients on ion exchange resins. Among organic amendments, the highest total contents were recorded for Ca, Mg, and S in farmyard manure, for K, Fe, and Mn in mushroom compost, for P, Zn, and Cu in biogas slurry, for B in biochar. The highest average release was recorded for P, Zn, Mn, and B from poultry manure, for Cu from biogas slurry, for Fe from vermicompost, for Ca, Mg, and S from mushroom compost, and for K from farmyard manure. The kinetics of mineralization and release of these nutrients conformed well to the zero-order kinetics and also to a power function equation. The initial release amount and release rate coefficient estimated by the power function equations were correlated significantly to the general properties of organic amendments and also to the type of C species present in organic amendment. Organic amendments having relatively higher content of water soluble C or fulvic or humic acids are likely to release nutrients through an early mineralization/solubilization from soil reserve.     

D140型大孔树脂纯化荷叶总黄酮的研究

[目的]为荷叶总黄酮的开发利用提供依据。[方法]先采用静态吸附法对5种不同型号的大孔树脂进行筛选,再利用动态吸附法对筛选出的大孔树脂进行进一步考察。[结果]D140型大孔树脂能更有效地纯化荷叶黄酮。当上样浓度为1．012～4．048mg／ml,上样速率为3BV／h时,荷叶黄酮的回收率较高。上样体积为5．5BV时,树脂基本达到动态饱和吸附。当乙醇浓度为60％、洗脱速率为2BV／h时,洗脱率最大,产物纯度最高。[结论]D140型大孔树脂纯化荷叶总黄酮的最佳工艺：以浓度为4．048mg／ml的荷叶总黄酮上样,上样速率控制在3BV／h左右,上样体积为5．5BV,再用3BV60％乙醇以2BV／h的速率洗脱,获得的荷叶总黄酮纯度为49．4％。     

大孔吸附树脂对蓖麻变应原的分离纯化研究

为了提高蓖麻变应原的纯度,采用不同型号的大孔树脂对变应原进行了分离研究。通过静态吸附和解吸实验,对9种大孔树脂进行了筛选。结果表明：AB-8型大孔树脂表现出最好的吸附性能与解吸效果,是较好的分离、纯化蓖麻变应原的树脂;选择AB-8树脂柱层析,其较佳动态吸附条件为：蓖麻变应原提取液浓度2．0g／L,pH5．0,流速2．0mL／min;较佳洗脱条件为：乙醇浓度25％,洗脱流速1．8BV／h,洗脱体积9BV。     

黑青稞麸皮结合态酚类物质大孔树脂分离纯化工艺优化

为了筛选对黑青稞麸皮结合酚类物质具有良好吸附、解吸性能的树脂,并建立其分离纯化工艺,评价其体外抗氧化活性,提高黑青稞麸皮的加工利用价值。本研究通过静态吸附和解吸试验比较了10种大孔树脂对黑青稞麸皮结合酚中总酚和总黄酮的分离纯化效果,筛选出AB-8为最佳吸附树脂类型,其静态吸附4 h可达到饱和;优化的吸附和解吸工艺参数为：黑青稞麸皮结合酚提取液pH值为3.0,上样质量浓度1.5 mg/mL,上样速度为1.5 mL/min,60%乙醇溶液作为洗脱剂进行动态洗脱,洗脱流速为1.5 mL/min;优化工艺条件下,经LC/MS检测,AB-8大孔树脂能显著提高71.43%以上不同种类单体酚的含量,且阿魏酸、丁香酸、苯甲酸、鞣花酸、杨梅素和芦丁是纯化后黑青稞麸皮结合酚中的主要酚类物质;体外抗氧化活性表明,黑青稞麸皮结合酚粗提物和纯化物均具有较强的体外抗氧化活性,纯化后的黑青稞麸皮结合酚溶液清除DPPH·、ABTS·+自由基及FRAP铁离子还原能力均显著增强。研究结果表明AB-8大孔树脂对黑青稞麸皮结合酚中总酚和总黄酮有较好的分离纯化效果,具有潜在的工业应用前景。     

玉米浸渍水制备肌醇新工艺

[目的]提出了一种制备肌醇的新工艺,以优化肌醇生产方法。[方法]以玉米浸渍水为原料,采用连续离交法（ISEP）等工艺来制取肌醇。研究还对工艺中的主要控制参数进行了系统优化。[结果]以玉米浸渍水制取肌醇的新工艺过程主要包括：絮凝除杂,ISEP提取植酸钠,植酸钠溶液浓缩、水解、结晶、过滤（除去Na2HPO4,水解液脱色离交,离交液经浓缩、干燥、结晶得到肌醇产品。[结论]相比传统工艺,ISEP制取肌醇新工艺能显著提高产品收率,而且该生产工艺具有原料来源广泛、工艺简化、原辅料消耗低、产品纯度高等特点。     

利用响应曲面法优化脲醛树脂合成工艺

使用响应曲面法研究尿素添加次数和尿素添加时间间隔对脲醛树脂性能和其板材性能的影响,使用傅里叶红外光谱仪定性分析尿素添加次数和尿素添加时间间隔对脲醛树脂主要基团的影响。结果表明:尿素添加次数和尿素添加时间间隔对脲醛树脂的固体含量及固化时间影响不大,而对黏度、树脂中羟甲基含量、游离甲醛含量、各主要基团含量和板材的性能有很大影响。树脂合成工艺中2次添加尿素,间隔时间20min时,树脂和板材性能比较好。