scholarly journals Stability of Pyruvic Acid Adsorbed Onto Clays and Exposed to Ionizing Radiation: Relevance in Chemical Evolution

2020 ◽  
Vol 7 (2) ◽  
pp. 97-101
Author(s):  
R. C Acosta-Fernández ◽  
A. Heredia-Barbero ◽  
A. Negrón-Mendoza
Keyword(s):  
Ionizing Radiation ◽  
Chemical Evolution ◽  
Pyruvic Acid ◽  
Solid Phase ◽  
Main Reaction ◽  
Exchangeable Cation ◽  
Keto Acid ◽  
Sodium Montmorillonite ◽  
Cation Type ◽  
Insight Into

Chemical evolution studies focus on the synthesis and stability of organic molecules during various transformative physicochemical processes. Gaining insight into the possible mechanisms behind these processes requires the use of various energy sources and catalysts that can produce such transformations. In this work, ionizing radiation (60Co) was used as a source of energy, and two clays with different exchangeable cations-sodium and iron (III)-were combined with pyruvic acid, a key alpha keto acid in metabolism. The samples of pyruvic acid were prepared at a concentration of 0.01 M; then, adsorption experiments were carried out by combining sodium or iron montmorillonite at different times. The amount that adsorbed onto iron montmorillonite was greater than the amount that adsorbed onto sodium montmorillonite. Samples of alpha keto acid at the same concentration were irradiated-in the absence of clay-at 0 to 146.1 kGy and at two pHs (6.7 and 2.0). The suspended samples with sodium and iron clay were then irradiated at the same doses. The results show that keto acid decomposes more quickly at more acidic pHs. The main reaction to irradiation without clay involves the dimerization of pyruvic acid, and 2,3-dimethyltartaric acid is the majority product. When irradiated in the presence of clay, the main reaction is decarboxylation, and acetic acid is the majority product. The exchangeable cation type modifies the interactions between the organic molecule and the solid phase. The percentage of recovered pyruvic acid is higher for iron montmorillonite than for sodium montmorillonite.

Globular clusters and their link with stellar populations in the Milky Way

2019 ◽  
Vol 14 (S351) ◽  
pp. 19-23
Author(s):  
David Yong
Keyword(s):  
Chemical Evolution ◽  
Globular Clusters ◽  
Milky Way ◽  
Star Clusters ◽  
Stellar Populations ◽  
Chemical Compositions ◽  
Chemical Abundance ◽  
Chemical Enrichment ◽  
Similarities And Differences ◽  
Insight Into

AbstractObservations of stellar chemical compositions enable us to identify connections between globular clusters and stellar populations in the Milky Way. In particular, chemical abundance ratios provide detailed insight into the chemical enrichment histories of star clusters and the field populations. For some elements, there are striking differences between field and cluster stars which reflect different nucleosynthetic processes and/or chemical evolution. The goal of this talk was to provide an overview of similarities and differences in chemical compositions between globular clusters and the Milky Way as well as highlighting a few areas for further examination.

Dissolution of wood in α-keto acid and aldehydic carboxylic acids and fractionation at room temperature

2014 ◽  
Vol 16 (7) ◽  
pp. 3569-3579 ◽  
Author(s):  
Yuri Nishiwaki-Akine ◽  
Takashi Watanabe
Keyword(s):  
Formic Acid ◽  
Carboxylic Acids ◽  
Pyruvic Acid ◽  
Ball Mill ◽  
Room Temperature ◽  
Glyoxylic Acid ◽  
Keto Acid

Wood pulverised using a ball mill was dissolved in an α-keto acid, pyruvic acid, and two aldehydic carboxylic acids, namely glyoxylic acid and formic acid, at room temperature.

Studies on the Reaction between Thiocarbamylsulfenamides and Diebenzothiazyl Disulfide

1983 ◽  
Vol 56 (2) ◽  
pp. 327-336 ◽  
Author(s):  
Basudam Adhikari ◽  
Dhananjay Pal ◽  
Dipak Kumar Basu ◽  
Ajit Kumar Chaudhuri
Keyword(s):  
Free Radicals ◽  
Binary Systems ◽  
Solid Phase ◽  
Synergistic Activity ◽  
Reaction Products ◽  
Vulcanization Process ◽  
Insight Into ◽  
Accelerator System

Abstract The use of binary systems as accelerators in the vulcanization of rubber has received considerable attention, since many of them in suitable combinations, have been shown to provide efficient vulcanization systems. Dogadkin and co-workers and Skinner and Watson reported mutual activation with a number of popular accelerator combinations. It was suggested that the mutual activation occurs by the interaction of the accelerators to form intermediate complexes which decompose to produce free radicals responsible for initiating the various reactions involved in the vulcanization process. Recently Krymowski and Taylor studied the reaction between N-oxydiethylenethiocarbamyl-N′-oxydiethylenesulfenamide (OTOS) and N-oxydiethylene-2-benzothiazylsulfenamide (OBTS), a synergistic accelerator system, in tetrachloroethane at 142°C, and identified the various products formed. Many of these reaction products themselves are familiar as vulcanization accelerators and thus may contribute to the synergistic activity observed with the OTOS-OBTS system. In the present investigation, we have studied the reaction between thiocarbamylsulfenamides and dibenzothiazyl disulfide (MBTS) in the solid phase in order to get an insight into the mutual activity provided by this system in filled and gum vulcanizates of NR.

Radical yields in DNA exposed to ionizing radiation: Role of energy and charge transfer

1990 ◽  
Vol 68 (9) ◽  
pp. 962-966 ◽  
Author(s):  
John H. Miller ◽  
Charles E. Swenberg
Keyword(s):  
Charge Transfer ◽  
Ionizing Radiation ◽  
Mechanistic Model ◽  
Experimental Studies ◽  
High Mobility ◽  
Orientation Dependence ◽  
Model Calculations ◽  
Insight Into ◽  
High Linear Energy Transfer

Theoretical and experimental studies of free-radical yields in oriented DNA samples exposed to ionizing radiation with high linear energy transfer at 77 K are discussed. The dependence of radical yields on the orientation of DNA chains relative to the particle flux is being investigated to gain insight into the role of intramolecular energy and charge transfer processes in radical production and decay. Model calculations based on a thermal-spike approximation are presented and their limitations for predicting the orientation dependence of radical yields observed after neutron irradiation (see C. M. Arroyo et al. Int. J. Radiat. Biol. 50, 789 (1986)) are discussed. A more mechanistic model based on the high mobility of excess electrons in hydrated DNA (D. van Lith et al. J. Chem. Soc. Faraday Trans. 1, 82, 2933 (1986)) is outlined.

Ligand-exchange mechanism: new insight into solid-phase extraction of uranium based on a combined experimental and theoretical study

2015 ◽  
Vol 17 (11) ◽  
pp. 7214-7223 ◽  
Author(s):  
Yin Tian ◽  
Jia Fu ◽  
Yi Zhang ◽  
Kecheng Cao ◽  
Chiyao Bai ◽  
...  
Keyword(s):  
Solid Phase Extraction ◽  
Ligand Exchange ◽  
Theoretical Study ◽  
Solid Phase ◽  
Exchange Process ◽  
Water Molecules ◽  
Phase Extraction ◽  
Extraction Mechanism ◽  
Coordinated Water ◽  
Insight Into

The extraction mechanism is an exchange process between the ligands on Urea-GO and the coordinated water molecules of uranyl.

scholarly journals Ionizing Radiation, an Instrument in Chemical Evolution Studies: Scope and Perspectives

2012 ◽  
Vol 6 (1) ◽  
pp. 99-101 ◽  
Author(s):  
E Y Aguilar-Ovando ◽  
◽  
A Negron-Mendoza ◽  
M L Ramirez-Vazquez ◽  
R C Acosta-Fernandez ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Chemical Evolution

Salt sieving within clay soil aggregates

Soil Research ◽  
1976 ◽  
Vol 14 (2) ◽  
pp. 149 ◽  
Author(s):  
AV Blackmore
Keyword(s):  
Clay Soil ◽  
Soil Aggregates ◽  
Normal Activity ◽  
Exchangeable Cation ◽  
High Concentration ◽  
Sodium Cations ◽  
Heavy Clay ◽  
Anion Exclusion ◽  
Cation Type ◽  
Negative Adsorption

The rates at which salt diffuses from the stable non-swelling aggregates of a heavy clay soil are studied in relation to both exchangeable cation type and free electrolyte content. Although the material is completely stable, it exposes a large clay surface of normal 'activity'. The results support a hypothesis that salt is constrained in some pores by salt-sieving within the aggregate; regions of anion exclusion, associated with surfaces in the narrower pores, restrict the cross section for diffusion from larger interior pores. It is shown that, when circumstances favour negative adsorption, that is with sodium cations and salt of relatively low concentration, salt is trapped within the microfabric; with calcium ions and salt of high concentration anion exclusion is suppressed and salt moves out of the aggregates much more easily. When the aggregates are in a saline sodic condition salt diffuses from them into saturated gypsum solution much more rapidly than it does into distilled water. This is in accord with the suggested model and implies that the ameliorative use of gypsum may involve a mechanism additional to those associated with swelling and flocculation. Application of the concept to soil in the field is briefly discussed.

Oncogenic HOXA9 Inhibits Cellular Apoptosis Induced by Ionizing Radiation (IR) in Transgenic Zebrafish

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5325-5325
Author(s):  
Ellen R Boyd ◽  
A. Michael Forrester ◽  
Clemens Grabher ◽  
Fui Boon Kai ◽  
Sahar Daas ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Caspase 3 ◽  
Transgenic Zebrafish ◽  
Zebrafish Embryos ◽  
Whole Mount ◽  
Caspase Cascade ◽  
Apoptotic Genes ◽  
Induced Apoptosis ◽  
Transgenic Embryos ◽  
Insight Into

Abstract Acute myeloid leukemia (AML) is characterized by the failure of terminal cellular differentiation of the myeloid lineage, and retains a significant rate of mortality despite aggressive therapy. One key oncogenic candidate, HOXA9 – belonging to the highly-conserved HOX family of developmental transcription factors – is frequently overexpressed in AML. In particular, this may result from the rare, but recurrent t(7;11)(p15;p15) chromosomal translocation, yielding the chimeric transcription factor NUP98-HOXA9. This translocation event is associated with a poor prognosis and elucidating the molecular activity of this fusion oncogene will enable the development of targeted therapeutics. Despite established mammalian models of AML, specific transcriptional targets of HOXA9 remain poorly defined. The zebrafish, Danio rerio, possesses orthologous blood cells to humans, making it a reliable model of vertebrate hematopoiesis and a promising tool for studying the molecular mechanisms underlying AML. The zebrafish has many advantages over traditional mouse models: chiefly, the ex utero development and transparency of zebrafish embryos allow for ease of manipulation, phenotypic analysis, and high throughput screening. We have demonstrated that ubiquitous overexpression of the human NUP98-HOXA9 oncogene in germline transgenic zebrafish embryos protects against apoptosis induced by ionizing radiation (IR) – a hallmark of oncogenesis. Acridine orange staining was indicative of decreased apoptosis in live transgenic embryos compared with wild type (WT) controls. Using whole mount immunofluorescent labeling, we similarly demonstrated that IR-treated transgenic embryos have a significant reduction in levels of activated caspase-3, a downstream effector protein in the conserved caspase cascade. By comparison, only a mild reduction in IR-induced apoptosis and activated caspase-3 was observed in a second transgenic zebrafish line overexpressing murine native Hoxa9, suggesting a gradient of impact on cell survival. Taken together, these findings implicate a block in caspase-3-dependent apoptosis as a mechanism underlying HOXA9-mediated oncogenesis in vivo and provide an opportunity to perform chemical modifier screens to identify agents that restore a WT phenotype. Whole mount RNA in situ hybridization for expression of pro-apoptotic genes, bad and puma, and anti-apoptotic genes, bcl2 and bcl-xL, will provide further insight into the effects of oncogenic HOXA9 on the caspase cascade. Similarly, rescue of caspase-3 activation and IR-induced apoptosis is underway via microinjection of bad and puma mRNA. To achieve robust and continuous myeloid-specific expression of oncogenic HOXA9 and partners, new transgenic strategies using both the Tol2 transposon-based Gateway cloning system and Cre/lox-induction are being employed. These lines will enable evaluation of myeloid-specific apoptosis, cell cycle regulation and cellular maturation to corroborate our findings in the ubiquitously-expressing lines, providing further insight into leukemogenic mechanisms and the potential to identify novel targeted therapies to improve the outcome in human AML.

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