Kinetics of Competitive Fixation of Potassium and Ammonium Ions by Silt Component of Soils from Different Agro-Climatic Regions

Potassium (K⁺) and nitrogen [N, as the form of ammonium (NH₄⁺)] are major nutrients for plant growth. Although there have been a number of studies on the kinetic fixation of potassium and ammonium ions in soils and clays, however, investigations on the kinetics of competitive fixation of these ions have been few, if any, especially by taking into account silt component of the soils. In this study, the kinetics of potassium and ammonium fixation were examined in the silt components of several soil samples. The results revealed that considerable amounts of K⁺ and in lesser amounts, NH₄⁺ ions were fixed by silt components of the soils. Potassium fixation was strongly preferred over ammonium. To describe the fixation kinetics, seven mathematically models were evaluated. A comparison of the models showed that pseudo-second-order equation properly described the fixation of these ions by the silt components.     

Human-altered and human-transported (HAHT) soils in the U.S. soil classification system

ABSTRACT

Human-altered and human-transported (HAHT) soils are widespread across the globe and are concentrated near where people live and work. Although some of the HAHT soils are significant because they can be hazardous to human, animal, and plant health, most are not mapped or classified to the same extent as agricultural soils. The purpose of this article is to discuss the occurrence, types, and importance of HAHT soils and to document the historical and proposed classification of HAHT soils in Soil Taxonomy. There are two main forms of materials that define HAHT soils: human-altered soils formed in human-altered materials (HAM) from the soil surface to 50 cm (or to bedrock if shallower) or more and human-transported soils formed in human-transported materials (HTM) from the soil surface to 50 cm (or to bedrock if shallower) or more. The HAHT soils mainly occur in urban areas, transportation corridors, mined lands, landfills, filled shallow water, and agricultural areas on anthropogenic landforms. Hazards include danger from radioactivity, pollution, content of hazardous artifacts, or presence on unstable landforms that may fail during heavy rains or earthquakes. The HAHT soils are extensive, and their extent is growing. In the past, few HAHT soils were described or classified adequately because the U.S. Soil Taxonomy system was established for agricultural and other naturally occurring soils. However, HAHT soils are now being recognized and classified in many soil classification systems at very high levels. A new soil order is proposed for U.S. Soil Taxonomy that would include the most obvious profoundly and intentionally altered HAHT soils. A discussion and justification is given for an unofficial proposal. Input will be collected from international groups of scientists, and modifications of the unofficial proposal are expected. The long-term result of establishing a new soil order will be to enable proper classification, allocation, and mapping of HAHT soils worldwide.     

基于高光谱苹果品种叶片铁含量估测模型

【目的】 在叶片水平上构建基于高光谱的苹果品种叶片铁素含量估测模型,为探寻实时、高效、无损的果树树体营养诊断提供技术途径。【方法】以苹果品种岩富10号为材料,测定岩富10号叶片光谱数据和铁素含量,采用光谱分析和相关分析法,筛选与叶片铁素含量相关性较强的光谱组合,利用偏最小二乘法构建苹果叶片铁素含量光谱估测模型。【结果】岩富10号苹果叶片一阶微分光谱与铁素含量的敏感波段为R′₉₉₀、R′_{1 113}、R′_{1 360}、R′_{1 408},相关系数最高为-0.698 9。对敏感波段两两进行加、减、乘、除运算,最优波段组合形式R′₉₉₀×R′_{1 048}与铁素含量相关系数为0.846 2。估测模型拟合度(R²)最高为0.827 5。【结论】苹果叶片一阶微分光谱组合与铁素含量显著相关(P<0.05),光谱组合能够明显提高其相关性,偏最小二乘法与逐步回归建模相比估算模型的精度更佳,可以用于苹果叶片铁素含量的光谱估算。     

钢筋混凝土框架柱计算长度设计方法研究

首先采用直接由材料本构关系形成单元M-N-Φ本构矩阵的方法推导出钢筋混凝土构件的单元刚度矩阵，编制了可以同时考虑材料和几何双重大量线性影响的有限元程序，与独立柱和框架柱的试验结果相比，计算结果吻合较好；然后，采用该分析程序对一榀二跨七层的规则框架算例进行分析，计算了各柱单元控制截面的二阶弯矩，并分析了二阶弯矩随各影响因素的变化规律；最后，以现行设计规范中标准柱偏心距增大系数的原型公式在本研究程序条件下修正公式为基点，分析了所选算例各柱单元的计算长度随各影响因素的变化规律。     

导数光谱在棉花农学参数测定中的作用探讨

通过大田和室内试验,测定了2个品种的棉花冠层、完全展开倒3叶在不同时期的高光谱反射率及对应叶片的叶绿素、类胡萝卜素含量,分析并证实了棉花导数光谱时消除测量背景影响及寻找特征波长方面的作用。将导数光谱用于棉花农学参数的测定,发现棉花冠层和叶片光谱都存在红边位移现象,并且红边参数(红边位置、红边幅值、红边面积)与叶面积指数、鲜叶重、干叶重和叶绿素含量有显著相关,从而证明用棉花导数光谱测定它的某些农学参数的可行性。     

对称偏导数

1　Symbols and DefinitionDefinition 1　 Suppose that the function　 y=f (x) is defined in an open interval (a,b) ,x∈(a,b) iflimΔx→ 0f (x +Δx) - f (x -Δx)2Δxexists,the limit is called the symmetric derivative of f(x) at point x,and denoted bydsfdx.Definition2　 Suppose that the function f(x,y) is defined for in a neighborhood of point M(x,y) .IflimΔx→ 0f (x +Δx,y) - f (x -Δx,y)2Δxexists,the limit is called the symmetric partial derivative of f (x,y) with respect to x at M,anddenote…     

一些关于广义伴随Stirling数的恒等式

利用发生函数的方法,给出了关于(广义的)伴随Stirling数以及(广义的)高阶Bernoulli数的一些恒等式.     

两种七阶收敛的牛顿迭代修正格式

提出了两种牛顿迭代修正格式,并给出了它们的收敛阶.数值实验表明这两种迭代格式具有一定的优势.     

抑制膳食相关酶活性的红曲霉菌株的选育

为弄清红曲霉在降脂减肥方面的作用,进一步开发红曲产物类药物应用于市场,以产红曲红色素的红曲霉菌株为出发菌株,经60Co诱变,对抑制与膳食相关的α-淀粉酶、胰蛋白酶和脂肪酶3种酶活性的红曲霉菌株进行了选育。结果表明:选育出1株能显著抑制3种与膳食相关酶的突变菌株M3-19,菌株M3-19液体发酵产物对α-淀粉酶、胰蛋白酶、脂肪酶有明显的抑制作用,抑制率分别为55.83%、25.4%和31.5%。经传代10代遗传稳定。     

青蒿素及其衍生物的作用机理及其对鸡球虫病的防治

对青蒿素及其衍生物的作用机理及近年来其在防治鸡球虫病的应用做了较详细的综述,以期为其在防治鸡球虫病中的应用提供参考。青蒿素被用于治疗疟疾已有几百年的历史,它还具有治疗血吸虫、腹泻及清热、镇静安神的作用,但其在兽医临床中的应用还是一个新领域。