Atrazine in mineral soil: chemical species and catalysed hydrolysis

1992 ◽  
Vol 70 (6) ◽  
pp. 1597-1603 ◽  
Author(s):  
Donald S. Gamble ◽  
Shahamat U. Khan
Keyword(s):  
Mineral Soil ◽  
Chemical Species ◽  
Organic Soil ◽  
Kinetics Parameters ◽  
Equilibrium Function ◽  
Data Scatter ◽  
Acidic Sites ◽  
Equilibrium And Kinetics ◽  
Relationship Of ◽  
The Relationship

Equilibrium and kinetics parameters have been evaluated at 25.0 °C for the heterogeneous catalysis of atrazine hydrolysis in slurries of a chemically characterized mineral soil. The fraction of acidic sites that accounts for sorption capacity, and the sorption equilibrium function resemble those for humic acid and organic soil. Sorption and desorption half-lives increased with increasing coverage of sorption sites. The sorption half-lives ranged from 3.6 to 735 days. The desorption half-lives ranged from 1 to 11 days. The hydrolysis half-lives ranged from 9.6 to 168 days and are consistent with Brönsted acid catalysis theory. The relationship of independent variables to data scatter has been analyzed. The information obtained should be useful for water and solute transport models.

Atrazine in mineral soil: the analytical chemistry of speciation

1992 ◽  
Vol 70 (6) ◽  
pp. 1590-1596 ◽  
Author(s):  
Donald S. Gamble ◽  
L. Ali Ismaily
Keyword(s):  
Analytical Chemistry ◽  
Chemical Kinetics ◽  
Sorption Capacity ◽  
Mineral Soil ◽  
Chemical Species ◽  
Organic Soil ◽  
Chemical Data ◽  
Heterogeneous Chemical ◽  
Conventional Methods

The HPLC–microfiltration method previously described for determining atrazine and hydroxyatrazine species in organic soil has been adapted to a mineral soil. The method was able to monitor atrazine concentrations of less than 1.0 × 10−6 M, which is over 40 times lower than the atrazine concentrations measured in the earlier organic soil experiments. During kinetics.experiments, it also monitored four free and sorbed chemical species instead of only one. Measurements were obtained with much better accuracy and productivity than can be obtained by conventional methods. The atrazine sorption capacity of the mineral soil was also measured. The analytical chemical data produced can support heterogeneous chemical kinetics calculations.

scholarly journals Verification and application of SuperMC3.3 to lead-bismuth-cooled fast reactor

2019 ◽  
Vol 34 (2) ◽  
pp. 122-128
Author(s):  
Hui Ding ◽  
Quan Gan ◽  
Lijuan Hao ◽  
Jing Song ◽  
Yican Wu
Keyword(s):  
Fast Reactor ◽  
Large Scale ◽  
Bench Mark ◽  
Fast Reactors ◽  
Reactor Physics ◽  
Kinetics Parameters ◽  
Power Profile ◽  
Integrated Software ◽  
Relationship Of ◽  
The Relationship

Lead-cooled fast reactors have multilayered designs and large internal temperature differences, which cause challenges in simulating reactor physics. SuperMC, a large-scale integrated software system for neutronics design, is inherently able to address complex geometries and multi-temperature problems. The purpose of this study is to verify the applicability of SuperMC to the lead-bismuth-cooled fast reactor RBEC-M. The multi-temperature cross-section generation function of SuperMC was employed and showed good performance. Based on the ENDF/B-VII.1 library, the effective multiplication factor keff obtained by SuperMC showed good agreement with those from previous works. The relationship of keff and 15N enrichment applied to the fuel material was also studied, with the results showing that in creased 15N could significantly improve keff. The axial power profile and kinetics parameters for the bench mark were then calculated and analyzed. This work thus verified the applicability of SuperMC for comprehensive neutronics simulations for lead-bismuth-cooled fast reactors.

THE RELATIONSHIP OF SOIL AND PHYSIOGRAPHIC ATTRIBUTES TO AN ECOLOGICAL CLASSIFICATION SYSTEM

1983 ◽  
Vol 63 (1) ◽  
pp. 97-112
Author(s):  
M. W. SONDHEIM ◽  
K. KLINKA
Keyword(s):  
Classification System ◽  
Variance Components ◽  
Mineral Soil ◽  
The Other ◽  
Ecological Classification ◽  
Approximation Techniques ◽  
The One ◽  
Relationship Of ◽  
The Relationship

The ability of a phytosociologically based, ecological classification system to explain the variability of soil and physiographic properties is tested. Sixty stands from a research forest in southwestern British Columbia are defined in terms of three categorical levels of the ecosystem taxonomy of V. J. Krajina. The stands belong to 14 associations, eight alliances, and three orders. Using these taxa, nested and one-way analyses of variance are performed on 40 soil and physiographic properties of the included ecosystems. Because the hierarchy tested is unbalanced and the samples are of unequal size, the estimates and significance of the variance components for both analyses are determined by approximation techniques. The results from the one-way analyses show that for mineral soil pH and for most physiographic factors between one-half and two-thirds of the variability can be explained by the classification of the ecosystems into associations. For the other properties and for the alliances and orders, this proportion is typically much lower. The study suggests that for general pedologic and environmental characterization there may be little justification for using the alliance and order categories. Key words: Soil-plant relationships, taxonomy, biogeocoenose, integrated classification

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Studies on Leukemogenic and Sarcomagenic Viruses

1970 ◽  
Vol 28 ◽  
pp. 156-157
Author(s):  
Leon Dmochowski
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Morphological Properties ◽  
Mode Of Development ◽  
Relationship Of ◽  
The Relationship

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.

The relationship of IGE receptor topography to signaling activity in RBL-2H3 mast cells

1991 ◽  
Vol 49 ◽  
pp. 236-237
Author(s):  
J.R. Pfeiffer ◽  
J.C. Seagrave ◽  
C. Wofsy ◽  
J.M. Oliver
Keyword(s):  
Mast Cells ◽  
Protein A ◽  
Scattered Electron ◽  
Ige Receptor ◽  
Receptor Complexes ◽  
Ige Binding ◽  
Electron Imaging ◽  
Small Clusters ◽  
Relationship Of ◽  
The Relationship

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.

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