Spray damage and residue levels in tobacco treated with various concentrations of 2,4-D at different stages of growth

1973 ◽  
Vol 13 (62) ◽  
pp. 328 ◽  
Author(s):  
KH Fung ◽  
RS Belcher ◽  
DM Whitfield
Keyword(s):  
Irrigation Water ◽  
Chemical Method ◽  
Accurate Determination ◽  
Obvious Effect ◽  
Herbicide Residues ◽  
Stages Of Growth ◽  
Residue Levels ◽  
High Concentrations ◽  
Considerable Damage

The effects of 2,4-D on tobacco at various stages of growth were investigated. Symptoms of damage were recorded and illustrated. The herbicide had no obvious effect on mature plants at any concentration used, but it caused considerable damage to plants at other phases of growth at moderate and high concentrations. A chemical method was developed for accurate determination of 2,4-D residues in tobacco. Investigation of the herbicide residues in irrigation water was necessary following the discovery of 2,4-D residues in control plants.

La formation des liaisons éthériques lors de la production du polytéréphthalate d'éthylène glycol

1978 ◽  
Vol 56 (21) ◽  
pp. 2703-2706 ◽  
Author(s):  
Vladimir Hornof ◽  
Leoš Zeman
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ethylene Glycol ◽  
Chemical Method ◽  
Periodic Acid ◽  
Accurate Determination ◽  
Physical And Mechanical Properties ◽  
Resistance To Oxidation ◽  
By Products

Ether-type linkages are formed as by-products during the preparation of polyethylene terephthalate from dimethyl terephthalate and ethylene glycol. Incorporated in the polymer, these linkages affect its physical and mechanical properties such as tensile strength, melting point, and resistance to oxidation. An improved chemical method of analysis has been developed allowing an accurate determination of ether bonds in polyester fibres. The method is based on the selective oxidation of ethylene glycol with periodic acid and takes advantage of hydrolysis with water under pressure to decompose the polymer. The method has been employed to study the effect of the concentration of polycondensation catalyst on the formation of ethers.

scholarly journals Distribution, source apportionment and health risk assessment of organochlorine pesticides in drinking groundwater

2021 ◽  
Author(s):  
John A. O. Oyekunle ◽  
Abiodun O. Adegunwa ◽  
Odunayo T. Ore
Keyword(s):  
Risk Assessment ◽  
Health Risk ◽  
Organochlorine Pesticides ◽  
Health Risk Assessment ◽  
The European Union ◽  
Groundwater Samples ◽  
Maximum Residue Levels ◽  
Residue Levels ◽  
High Concentrations

Abstract Groundwater samples of Ile-Ife, Osun State, Nigeria were investigated for their organochlorine pesticides (OCPs) levels. Probable sources of the OCPs and health risks associated with their consumption along with the water were determined in order to establish the potability of the groundwater samples. Quantitative determination of the OCPs was carried out by Gas Chromatography coupled with Electron Capture Detector (GC-ECD) after liquid-liquid extraction with dichloromethane (DCM). Results indicated that all the analyzed OCPs except p,p'-dichlorodiphenylethane were detected with high concentrations in the groundwater. Heptachlor (14.60±3.60 µg L-1) and methoxychlor (12.60±2.20 µg L-1) showed dominant concentrations that were higher than 0.02 ng L-1 maximum residue levels (MRLs) recommended by the European Union. Levels of the OCPs in the samples followed the decreasing trend: cyclodienes > diclorophehylethanes > chlorinated cyclohexanes, while the predominant source of the analyzed pesticides could be ascribed to aerial transportation from fresh applications in homes within the community. The carcinogenic health risk assessment also revealed consistent higher values of HQ and CR in children as opposed to adults, indicating that children are the more vulnerable population to the analyzed environmental contaminants.

scholarly journals Distribution, source apportionment and health risk assessment of organochlorine pesticides in drinking groundwater

2021 ◽  
Author(s):  
John A. O. Oyekunle ◽  
Abiodun O. Adegunwa ◽  
Odunayo T. Ore
Keyword(s):  
Risk Assessment ◽  
Health Risk ◽  
Organochlorine Pesticides ◽  
Health Risk Assessment ◽  
The European Union ◽  
Groundwater Samples ◽  
Maximum Residue Levels ◽  
Residue Levels ◽  
High Concentrations

Abstract Groundwater samples of Ile-Ife, Osun State, Nigeria were investigated for their organochlorine pesticides (OCPs) levels. Probable sources of the OCPs and health risks associated with their consumption along with the water were determined in order to establish the potability of the groundwater samples. Quantitative determination of the OCPs was carried out by Gas Chromatography coupled with Electron Capture Detector (GC-ECD) after liquid-liquid extraction with dichloromethane (DCM). Results indicated that all the analyzed OCPs except p,p'-dichlorodiphenylethane were detected with high concentrations in the groundwater. Heptachlor (14.60±3.60 µg L-1) and methoxychlor (12.60±2.20 µg L-1) showed dominant concentrations that were higher than 0.02 ng L-1 maximum residue levels (MRLs) recommended by the European Union. Levels of the OCPs in the samples followed the decreasing trend: cyclodienes > diclorophehylethanes > chlorinated cyclohexanes, while the predominant source of the analyzed pesticides could be ascribed to aerial transportation from fresh applications in homes within the community. The carcinogenic health risk assessment also revealed consistent higher values of HQ and CR in children as opposed to adults, indicating that children are the more vulnerable population to the analyzed environmental contaminants.

Accurate determination of rivaroxaban levels requires different calibrator sets but not addition of antithrombin

2012 ◽  
Vol 108 (07) ◽  
pp. 191-198 ◽  
Author(s):  
Gabriele Rohde ◽  
Gertrud Stratmann ◽  
Christian Hesse ◽  
Natalie Herth ◽  
Stephan Schwers ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Accurate Determination ◽  
Factor Xa ◽  
Plasma Samples ◽  
High Concentration ◽  
Wide Range ◽  
Blinded Study ◽  
Calibration Sets ◽  
High Concentrations

SummaryRivaroxaban is a direct factor Xa inhibitor, which can be monitored by anti-factor Xa chromogenic assays. This ex vivo study evaluated different assays for accurate determination of rivaroxaban levels. Eighty plasma samples from patients receiving rivaroxaban (Xarelto®) 10 mg once daily and 20 plasma samples from healthy volunteers were investigated using one anti-factor Xa assay with the addition of exogenous antithrombin and two assays without the addition of antithrombin. Two different lyophilised rivaroxaban calibration sets were used for each assay (low concentration set: 0, 14.5, 59.6 and 97.1 ng/ml; high concentration set: 0, 48.3, 101.3, 194.2 and 433.3 ng/ml). Using a blinded study design, the rivaroxaban concentrations determined by the assays were compared with concentrations measured by HPLC-MS/MS. All assays showed a linear relationship between the rivaroxaban concentrations measured by HPLC-MS/MS and the optical density of the anti-FXa assays. However, the assay with the addition of exogenous anti-thrombin detected falsely high concentrations of rivaroxaban even in plasma samples from controls who had not taken rivaroxaban (intercept values using the high calibrator set and the low calibrator set: +26.49 ng/ml and +13.71 ng/ml, respectively). Plasma samples, initially determined by the high calibrator setting and containing rivaroxaban concentrations <25 ng/ml, had to be re-run using the low calibrator setting for precise measurement. In conclusion, anti-factor Xa chromogenic assays that use rivaroxaban calibrators at different concentration levels can be used to measure accurately a wide range of rivaroxaban concentrations ex vivo. Assays including exogenous antithrombin are unsuitable for measurement of rivaroxaban.

scholarly journals Distribution, Source Apportionment and Health Risk Assessment of Organochlorine Pesticides in Drinking Groundwater

2021 ◽  
Author(s):  
John A. O. Oyekunle ◽  
Abiodun O. Adegunwa ◽  
Odunayo T. Ore
Keyword(s):  
Risk Assessment ◽  
Health Risk ◽  
Organochlorine Pesticides ◽  
Health Risk Assessment ◽  
The European Union ◽  
Groundwater Samples ◽  
Maximum Residue Levels ◽  
Residue Levels ◽  
High Concentrations

Abstract Groundwater samples of Ile-Ife, Osun State, Nigeria were investigated for their organochlorine pesticides (OCPs) levels. Probable sources of the OCPs and health risks associated with their consumption along with the water were determined in order to establish the potability of the groundwater samples. Quantitative determination of the OCPs was carried out by Gas Chromatography coupled with Electron Capture Detector (GC-ECD) after liquid-liquid extraction with dichloromethane (DCM). Results indicated that all the analyzed OCPs except p,p'-dichlorodiphenylethane were detected with high concentrations in the groundwater. Hepachlor (14.60±3.60 µg/L) and methoxychlor (12.60±2.20 µg/L) showed dominant concentrations that were higher than 0.02 ng/L maximum residue levels (MRLs) recommended by the European Union. Levels of the OCPs in the samples followed the decreasing trend: cyclodienes > diclorophehylethanes > chlorinated cyclohexanes, while the predominant source of the analyzed pesticides could be ascribed to aerial transportation from fresh applications in homes within the community. The carcinogenic health risk assessment also revealed consistent higher values of HQ and CR in children as opposed to adults, indicating that children are the more vulnerable population to the analyzed environmental contaminants.

The Accurate Determination of Major Constituents by X-Ray Fluorescent Analysis in the Presence of Large Interelement Effects

1963 ◽  
Vol 7 ◽  
pp. 523-541 ◽  
Author(s):  
J. Lucas-Tooth ◽  
C. Pyne
Keyword(s):  
Accurate Determination ◽  
Correction Method ◽  
High Alloy ◽  
Order Of Accuracy ◽  
X Ray ◽  
Routine Basis ◽  
Alloy Steels ◽  
High Concentrations ◽  
Chromium Determination

AbstractFluorescent X-ray spectrometers bave a high inherent reproducibility. It is possible to achieve results, on a routine basis, which have a coefficient of variation of less than 0.1%. Given extremely good chemical standards and the absence of interelemental effects, these readings can be interpreted into percentage concentrations with the same order of accuracy. Results, with this accuracy of analyses of copper in a straight brass will be given. With samples of greater complexity and more elements the interelement effects are large and have to be tackled. A correction method has been established and will be explained in detail.As an example of the method it was decided to tackle the determination of chromium at high concentrations (7-32 %) in high-alloy steels containing additions in the following ranges: Si, 0.2-2.4%; Al, 0,07-5%; Cu, 1,3-3.6%; W, 0.25-3%; V, 0.1-0.3%; Nb, 0.1-0.3%; Mo, 0.1-4.4%; Ti, 0.05-1%; Mn, 0.35-10%; Ni, 0.2-24%. These very wide alloy specifications were a severe test on the accuracy of the chromium determination & the correction for interelement effects.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

Computer-Assisted High-Re Solution TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 162-163
Author(s):  
F.A. Ponce ◽  
H. Hikashi
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Computer Software ◽  
Video Camera ◽  
Image Contrast ◽  
Objective Lens ◽  
Computer Assisted ◽  
Optical Parameters ◽  
Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

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