Sample Volume Effect on the Determination of Nitrate-Nitrogen in the Soil Profile

1989 ◽  
Vol 32 (3) ◽  
pp. 0934-0938 ◽  
Author(s):  
D. G. Baker ◽  
R. S. Kanwar ◽  
J. L. Baker
Keyword(s):  
Soil Profile ◽  
Nitrate Nitrogen ◽  
Volume Effect ◽  
Sample Volume

Sample volume effect on determination of soil salinity

1987 ◽  
Vol 18 (5) ◽  
pp. 593-599 ◽  
Author(s):  
A. M. El‐Araby ◽  
A. W. Warrick ◽  
T. C. Tucker
Keyword(s):  
Soil Salinity ◽  
Volume Effect ◽  
Sample Volume

Comparison of the viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate)

1979 ◽  
Vol 44 (6) ◽  
pp. 1942-1948 ◽  
Author(s):  
Jaroslav Hrouz ◽  
Michal Ilavský ◽  
Ivan Havlíček ◽  
Karel Dušek
Keyword(s):  
Methyl Acrylate ◽  
Poisson Ratio ◽  
Young Modulus ◽  
Ethyl Acrylate ◽  
Sample Volume ◽  
Viscoelastic Behaviour ◽  
Tensile Behaviour ◽  
Temperature Superposition ◽  
Main Transition

The viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate) in the main transition region have been investigated. It was found that the time-temperature superposition could be carried out in the case of the penetration viscoelastic behaviour; the temperature dependence of the penetration and tensile shift factors was the same. The superimposed curves of the penetration and Young modulus allowed us to calculate the dependence of the Poisson ratio and thus to characterize the change in sample volume with deformation. It was demonstrated that the penetration method of determination of the viscoelastic behaviour is equivalent to the tensile method.

RUMEN GAS ANALYSIS BY GAS-SOLID CHROMATOGRAPHY

1961 ◽  
Vol 41 (2) ◽  
pp. 187-196 ◽  
Author(s):  
J. M. McArthur ◽  
J. E. Miltimore
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Hydrogen Sulphide ◽  
Sample Volume ◽  
Gas Analysis ◽  
Complete Analysis ◽  
Thermal Detector ◽  
Thermal Detection ◽  
Methane Carbon

Methods are described for sampling and analysing rumen gases. The analysis requires less than 15 minutes for the determination of hydrogen, oxygen, nitrogen, methane, carbon monoxide, carbon dioxide, and hydrogen sulphide, i.e., for all gases occurring in the rumen. The method is sensitive and requires only a small quantity of sample, and the sample volume need not be known. The presence of water or other vapours in the sample does not influence the results. Relative thermal detector responses have been determined for gases which occur in the rumen. These eliminate the necessity for the calibration of gas chromatographs using thermal detection. The first complete analysis of rumen gas is presented.

scholarly journals Nitrate-Nitrogen Leaching and Modeling in Intensive Agriculture Farmland in China

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Ligang Xu ◽  
Hailin Niu ◽  
Jin Xu ◽  
Xiaolong Wang
Keyword(s):  
Nitrate Leaching ◽  
Soil Profile ◽  
Nitrate Nitrogen ◽  
Initial Conditions ◽  
Simulated Data ◽  
Intensive Agriculture ◽  
Health Concern ◽  
N Leaching ◽  
And Migration ◽  
Leachm Model

Protecting water resources from nitrate-nitrogen (NO3-N) contamination is an important public health concern and a major national environmental issue in China. Loss of NO3-N in soils due to leaching is not only one of the most important problems in agriculture farming, but is also the main factor causing nitrogen pollution in aquatic environments. Three typical intensive agriculture farmlands in Jiangyin City in China are selected as a case study for NO3-N leaching and modeling in the soil profile. In this study, the transport and fate of NO3-N within the soil profile and nitrate leaching to drains were analyzed by comparing field data with the simulation results of the LEACHM model. Comparisons between measured and simulated data indicated that the NO3-N concentrations in the soil and nitrate leaching to drains are controlled by the fertilizer practice, the initial conditions and the rainfall depth and distribution. Moreover, the study reveals that the LEACHM model gives a fair description of the NO3-N dynamics in the soil and subsurface drainage at the field scale. It can also be concluded that the model after calibration is a useful tool to optimize as a function of the combination “climate-crop-soil-bottom boundary condition” the nitrogen application strategy resulting for the environment in an acceptable level of nitrate leaching. The findings in this paper help to demonstrate the distribution and migration of nitrogen in intensive agriculture farmlands, as well as to explore the mechanism of groundwater contamination resulting from agricultural activities.

scholarly journals Restoration of soil fertility of the southern chernozem in conditions of the reserve regime of the Orenburg State Nature Reserve

2018 ◽  
Vol 7 (2) ◽  
pp. 126-129
Author(s):  
Alexander Nikolaevich Tyurin
Keyword(s):  
Heavy Metals ◽  
Soil Profile ◽  
Nature Reserve ◽  
Specially Protected Natural Areas ◽  
Southern Chernozem ◽  
State Nature Reserve ◽  
Protected Natural Areas ◽  
Phosphorus And Potassium ◽  
State Nature

This paper presents a comparative-temporal ecological characterization of the southern chernozem under the regime of the Aituar steppe site command of the Orenburg State Nature Reserve. The degree of ecological rehabilitation of chernozems in specially protected natural areas is shown. Quantitative data are provided on the supply of soil with nitrogen, phosphorus and potassium, and the content of heavy metals in the soil. Determination of the content of heavy metals and trace elements in soil samples (according to the method of Krupsky and Aleksandrova in the modification of the Central Institute of Agrochemical Services for Agriculture) was conducted in accordance with GOST 50683-94. The determination of mobile compounds of phosphorus and potassium was carried out by the method of Machigin (GOST-26205-91), organic matter by the Tyurin method (GOST 26213-9), alkaline hydrolyzable nitrogen by Kornfield. The paper presents the results of a comparison of agrochemical and ecology-toxicological studies of southern chernozem in 1996-2016. The main morphogenetic characteristics of the soil profile of the chernozem of the southern carbonate low-humus low-mass medium loamy are given. Data of morphological, physical and agrochemical properties of soils were subjected to mathematical and statistical treatment. This allowed the authors to determine morphological parameters, qualitative and quantitative characteristics of the soil and their variation within the elementary soil areas, depending on the position in the landscape and the nature of use. The data obtained indicate a positive dynamics in the provision of soil with humus and elements of mineral nutrition of plants, as well as a significant reduction in the content of heavy metals throughout the soil profile. Thus, we can talk about the natural restoration of soil fertility in conditions of a protected regime in specially protected natural areas.

scholarly journals Development and validation of the method for the quantitative determination of methotrexate in a transport medium by HPLC-MS/MS

2021 ◽  
pp. 45-51
Author(s):  
P. Yu. Mylnikov ◽  
Yu. Tranova ◽  
A. V. Shchulkin ◽  
E. N. Yakusheva
Keyword(s):  
Quantitative Determination ◽  
Gradient Elution ◽  
Sample Volume ◽  
Transport Medium ◽  
Mass Selective Detector ◽  
Transporter Protein ◽  
Wide Range ◽  
Separation Temperature

Relevance. BCRP is an efflux transporter protein that plays an important role in the pharmacokinetics of a wide range of drugs. The BCRP activity in vitro experiments is assessed by the transport of transporter protein substrates (methotrexate, etc.) across the bilipid membrane of cells overexpressingBCRP, for example, Caco-2 cells. The aim is to develop and validate a method for the quantitative determination of the BCRP substrate, methotrexate, in the transport medium of Caco-2 cells by HPLC-MS/MS. Methods. The work was performed on an Ultimate 3000 HPLC chromatograph (ThermoFisher, USA) with a TSQ Fortis tandem mass-selective detector (ThermoFisher, USA). The conditions of chromatographic analysis were as follows: column UCT Selectra C18 4.6 mm * 100 mm 5um, 100A, Selectra C18 Guard Cartridges SLC-18GDC46-5UM, separation temperature 35 °С, flow rate 0.3 ml/min, injected sample volume - 2 μl, analysis time - 10 min. Used a gradient elution: the ratio of the solution of 0.1 % formic acid and acetonitrile was at 0 min 75 and 25 %; 0.4 min 60 and 40 %; 6 minutes 20 and 80 %; 8 minutes 75 and 25 %. Under these conditions, the retention time of methotrexate is 3.11 minutes. Detection conditions: methotrexate - positive ionization mode, 455.15 m / z → 308.125 m / z, collision energy 22.99 V, source fragmentation 5, CID gas pressure 2 mTorr. The extraction of methotrexate from the transport medium (Hanks solution with 25 mM Hepes and 1% dimethyl sulfoxide) after incubation with Caco-2 cells for 3 h was carried out with a mixture of methanol + water in a ratio of 1: 1. Results. The developed method was validated according to the following parameters: selectivity, linearity, accuracy, precision, limit of quantitative determination, sample transfer, sample stability. The confirmed analytical range of the method was 60 -10,000 nmol / L in the transport medium. Conclusions: a method for the quantitative determination of methotrexate in the transport medium of Caco-2 cells by HPLC-MS / MS was developed and validated.

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