An observational study on precipitation chemistry data as a function of surface wind direction

Precipitation chemistry data were collected at 8 sites in the western part of the Netherlands over a period of 151/2 yr. Using specially-designed wind direction-dependent rain collectors, it is demonstrated that levels of ion constituents in rain water vary with wind direction, which can be assigned to different sources of contamination. The strongest variation was measured for Na⁺. As expected, trajectories over sea contributed most. Continental sources slightly reduced the variation for Cl^? and Mg²⁺. For both NH _inf4 ^sup+ and excess SO _inf4 ^sup2? , maxima were found in southeasterly rainfall. It is assumed that polluted air from the large industrial Ruhr Area crosses a region with strong NH₃ emissions in the Southeast of the Netherlands. The presence of ammonium sulfate was suggested. Minor variations were measured for NO _inf3 ^sup? (due to diffusely-spread emissions and possible sampling artefact) and for H⁺ and Ca²⁺ (dry-deposition effects). Over the period 1973–1987 excess-SO _inf4 ^sup2? levels decreased significantly (?3.3% yr^?1, p<0.01) which is consistent with reduced S emission in Western Europe. Over the last decade an upward trend in NO _inf3 ^sup? levels has been observed (3.2% yr^?1, p<0.05) which is possibly related to the increased usage of cars.     

Amino sugar determination in organic soils by capillary gas chromatography using a nitrogen-selective detector

A method is described for the analysis of amino sugars in humus layers by capillary gas liquid chromatography. After acid hydrolysis and reduction, amino sugar alcohols are baseline separated as their trifluoroacetates. Hexosamines are selectively detected using a nitrogen-specific, flameless thermoionic detector and quantified with p-aminophenol HCl as internal standard. This procedure is applied to determine the amino sugar contents and hence to characterize the relative role of fungi and bacteria in the decomposition process in a Lithic Borofolist.     

Atmospheric deposition in acid sensitive areas of Ireland — The influence of wind direction and a new coal burning electricity generation station on precipitation quality

Greater acidity and substantially higher annual deposition of the major ions, were recorded in the precipitation at Glencree (Co. Wicklow) on the east coast of Ireland compared to those recorded at the west coast sampling stations. The daily average deposition of hydrogen ions, non-marine sulphate and oxidized nitrogen was higher at all sampling locations when associated with air masses arriving from the east compared with those from the west, particularly at Glencree. The impact of emissions from the coal-fired power station at Moneypoint (Co.Clare) on the precipitation was negligible at all sampling locations except at Gortglass, a point 19 km to its east. At this sampling point the higher concentrations and deposition for hydrogen ion and non-marine sulphate were associated with air masses expected to show the influence of the Moneypoint power station.     

Comparison of stirring and vortex mixing for the extraction of available nutrients from soil using a laboratory robot

Abstract

We investigated the efficiency with which a laboratory robot is able to extract available nutrients from soil contained in tubes. We have shown that for vortex mixing, the volume of soil and extractant are of critical importance. In cases where the soil/extractant volumes are small (e.g. 2 mL soil: 10 mL extractant), extraction of all the nutrients investigated was good. However, keeping the ratio the same, but increasing the volumes to 6 mL soil:30 mL extractant leads to an overall decrease in extracting efficiency. Using a paddle stirrer to mix the soil and extractant together results in the same extraction efficiency across the range of soil/ extractant volumes.     

Quantitation of clovamide-type phenylpropenoic acid amides in cells and plasma using high-performance liquid chromatography with a coulometric electrochemical detector

A high-performance liquid chromatography (HPLC) method was developed for measuring the concentrations of clovamide-type phenylpropenoic acid amides (N-caffeoyldopamine and N-caffeoyltyramine) in cell and plasma samples. The separation was performed on a Nova-Pak C18 column using an isocratic buffer with a coulometric electrochemical detector with four electrode channels. Using the HPLC method, N-caffeoyldopamine and N-caffeoyltyramine could be detected with good peak resolutions at respective retention times (4 and 6.4 min). The calibration curves were linear over the ranges (0.1 and 100 microM), and their lower limit of detection was as little as 100 fmol. For quantifying N-caffeoyldopamine and N-caffeoyltyramine in cell and plasma samples, the samples were extracted by extraction methods with more than 95% recoveries. After extraction, the amides were detected with the same sensitivity, peak resolutions, and retention times. Using this method, plasma concentrations of N-caffeoyltyramine were determined in blood samples collected at 12, 24, 30, 36, 48, 60, and 75 min after the oral administrations of N-caffeoyltyramine (0.5 mg and 2 mg/30 g body weight). This HPLC method with an electrochemical detector is the first reported method able to quantify N-caffeoyldopamine and N-caffeoyltyramine in biological samples with excellent detection limits, peak resolutions, discrete retention times, and consistent reproducibility.     

Determination of acidic herbicides and related compounds in water and soil by capillary gas chromatography using a nitrogen-phosphorus detector

Methods are described for the determination of acidic herbicides and related compounds in water and soil. Eight acidic herbicides and related compounds were extracted from water using either dichloromethane or an XAD-2 resin column. The acidic moieties were derivatized with 2-cyanoethyldimethyl(diethyl)aminosilane. The derivatized compounds were separated using capillary gas chromatography and quantitated using a nitrogen-phosphorus detector. Extraction from water using dichloromethane or an XAD-2 resin column resulted in recoveries greater than 90% at 0.1 ppb with an average coefficient of variation (CV) of 6%. In soils extracted with aqueous acetonitrile-acetic acid and partitioned into dichloromethane, recoveries at 500 ppb were greater than 75% with an average CV of 3.3%. The methods are rapid and there are few interferences.     

保护性措施对农田土壤风蚀影响的室内风洞模拟

为寻求合理的保护性耕作措施,试验设计了砾石覆盖、秸秆覆盖、覆盖与留茬组合的措施和4个风速等变量,研究风速、覆盖物和覆盖度与风蚀量、抗风蚀效率、风沙流结构的关系,比较多种措施之间的抗风蚀效果优劣.结果表明:1)4个设定风速下30％ ～ 90％覆盖度的秸秆覆盖的抗风蚀效率在54％ ～ 92％之间,砾石覆盖为26％～72％,30％的砾石覆盖或30％的秸秆覆盖与3种留茬高度的组合措施下,平均抗风蚀效率均在70％ ～ 78％之间;2)随着覆盖度的增加,砾石覆盖措施最小可抑制的有效风速值从8.0 m/s逐渐增大到12.5 m/s,秸秆覆盖措施从10.1m/s增加到了14.3 m/s;3)覆盖处理下0～62 cm高度内的输沙量大部分集中在0～26 cm;4)覆盖与留茬组合措施的输沙量多集中在60 cm以内.     

Three-dimensional computer-aided human factors engineering analysis of a grafting robot

The objective of this research was to conduct a human factors engineering analysis of a grafting robot design using computer-aided 3D simulation technology. A prototype tubing-type grafting robot for fruits and vegetables was the subject of a series of case studies. To facilitate the incorporation of human models into the operating environment of the grafting robot, I-DEAS graphic software was applied to establish individual models of the grafting robot in line with Jack ergonomic analysis. Six human models (95th percentile, 50th percentile, and 5th percentile by height for both males and females) were employed to simulate the operating conditions and working postures in a real operating environment. The lower back and upper limb stresses of the operators were analyzed using the lower back analysis (LBA) and rapid upper limb assessment (RULA) functions in Jack. The experimental results showed that if a leg space is introduced under the robot, the operator can sit closer to the robot, which reduces the operator's level of lower back and upper limbs stress. The proper environmental layout for Taiwanese operators for minimum levels of lower back and upper limb stress are to set the grafting operation at 23.2 cm away from the operator at a height of 85 cm and with 45 cm between the rootstock and scion units.     

Determination of D-chiro-Inositol in tartary buckwheat using high-performance liquid chromatography with an evaporative light-scattering detector

A simple method for rapid determination of d- chiro-inositol (DCI) (a potent mediator of insulin metabolism) contained in tartary buckwheat ( Fagopyrum tataricum L. Gaench) was developed on the basis of high-performance liquid chromatography coupled to an evaporative light scattering detector (ELSD). DCI was separated from an extract of tartary buckwheat on an Alltech Prevail Carbohydrates ES 5 mum column. During postcolumn detection, DCI was detected by ELSD. The detection limit was 100 ng. This method was sensitive enough for determining DCI in tartary buckwheat and its related products.     

染色体步移技术克隆已知序列侧翼启动子的研究进展

启动子是基因表达调控的关键顺式作用元件,也是基因工程表达载体的一个重要元件.对启动子结构和功能的阐释,有助于基因表达的时空控制.选择恰当方法克隆序列未知的启动子有着非常重要的意义和广阔的应用前景.随着PCR技术的问世,基于PCR扩增的染色体步移技术进行启动子克隆具有较好的可操作性,其在基因的分子生物学和基因工程研究方面也是一项重要的技术策略.本文讨论了近年来以PCR为基础的染色体步移技术克隆启动子的方法,主要包括反向PCR、接头介导PCR、半随机引物PCR三大类,归纳比较了其克隆原理和研究进展,为克隆己知序列旁侧未知启动子序列提供参考.     

Incorporation of wind roses in a statistical long-range pollution transport model

A modified version of the Ontario Ministry of the Environment Statistical Long-Range Transport (LRT) Model has been developed at the University of Waterloo. The model incorporates wind rose data at pollutant sources and receptors to reflect the percent of time that a source pollutant plume is affecting a down-wind receptor. Comparison of output to results generated by complex LRT models (i.e., the AES and MOE Lagrangian models) has demonstrated that the modified model results replicate complex model results fairly well. However, the model presented preserves the advantages of low execution costs and simple data input. This benefit permits the user to efficiently simulate a large number of LRT scenarios.     

Some aspects of frequency and stability wind roses in a tropical region

The frequency wind roses and stability wind roses based on meteorological data at Nairobi International Airport are calculated. The stability is estimated using a Pasquill-Gifford Scheme. The results show that in the tropics the winds have generally high speeds and are highly constant in direction throughout the year. The high wind speed in these regions has a great influence on the stability estimation scheme that is used. The high wind speeds and persistence in the tropics are viewed as favorable factors in the air pollution problem since the dispersive ability of the atmosphere is enhanced and, in terms of long term planning, the wind variability is much less than is the case with middle latitudes.     

Liquid chromatographic determination of naringin and neohesperidin as a detector of grapefruit juice in orange juice

Naringin/neohesperidin ratios can be used to differentiate orange juice which may contain added grapefruit juice from orange juice which may include juices from other naringin-containing cultivars. The naringin/neohesperidin ratios in juice vary from 14 to 83 in grapefruit (C. grandis) and from 1.3 to 2.5 in sour orange (C. aurantium) cultivars; the ratio is always less than 1 for the K-Early tangelo. Concentrations of both naringin and neohesperidin can be determined in orange juice by using a single liquid chromatographic isocratic reverse-phase system with a C-18 column. The detection limit for both compounds is 1 ppm with a linear working range to 500 ppm. Concentration relative standard deviations range from 0.47 to 1.06% for naringin and from 0.4 to 1.27% for neohesperidin. Naringin and neohesperidin recoveries ranged from 93 to 102% at concentrations of 5 and 50 ppm. Naringin values from blind duplicate samples of orange/grapefruit juice blends could be duplicated to +/- 3%.