HOT ATOM REACTIONS AND RADIATION-INDUCED EFFECTS IN THE REACTIONS OF RECOIL TRITIUM WITH CYCLOPROPANE

1960 ◽  
Vol 38 (10) ◽  
pp. 1756-1768 ◽  
Author(s):  
J. K. Lee ◽  
Burdon Musgrave ◽  
F. S. Rowland
Keyword(s):  
Free Radical ◽  
Kinetic Energy ◽  
Strong Dependence ◽  
Single Step ◽  
Free Radical Scavengers ◽  
Recoil Energy ◽  
Hydrogen Atoms ◽  
Experimental Conditions ◽  
High Kinetic Energy ◽  
Hot Products

Recoil He3 (n, p) tritium atoms have been reacted with cyclopropane in the gas phase under a variety of experimental conditions. The labeled hydrocarbon and molecular hydrogen products have been separated by gas chromatography and assayed by gas proportional counting.The observed products show a strong dependence upon irradiation dose—cyclopropane is very inert toward reactions with hydrogen atoms and organic radicals, and the labeled olefinic products react preferentially, in effect as scavengers, with the reactive species from radiolysis of the parent molecule.Energetic tritium atoms are able to react with cyclopropane to give labeled cyclopropane as a product without causing isomerization or decomposition of the molecule. The relative yields of cyclopropane and propylene are dependent upon the average collisional de-excitation times, indicating that a fraction of the labeled cyclopropane molecules are decomposing in times of approximately 10−9 seconds. Cyclopropane, propylene, ethylene, hydrogen, and small amounts of allene and methylacetylene are observed as "hot" products in the presence of gaseous free radical scavengers. Many additional compounds are found as the result of free radical and/or radiolysis reactions in the absence of scavengers.The "hot" reactions are explained in terms of the single-step interactions of high kinetic energy tritium atoms with the cyclopropane molecules—the energy for endothermic and high activation energy processes is obtained from the recoil energy. The kinetic energy of the recoil atom at reaction is estimated to be of the order of 130 kcal/mole for some of the observed labeled compounds.

Collisional Interaction of Ionized Pyridine N-Oxides with Various Targets in a New Hybrid Mass Spectrometer

2000 ◽  
Vol 6 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Robert Flammang ◽  
Virginie Henrotte ◽  
Pascal Gerbaux ◽  
Minh Tho Nguyen
Keyword(s):  
Nitric Oxide ◽  
Kinetic Energy ◽  
Molecular Ions ◽  
Translational Energy ◽  
Experimental Conditions ◽  
Hybrid Mass Spectrometer ◽  
High Kinetic Energy ◽  
Target Molecules ◽  
Ion Molecule Complexes ◽  
Oxide Ions

Upon collisional activation at high kinetic energy (8 keV), the molecular ions of pyridine N-oxides 1–5 undergo an unexpected loss of 16 mass units (oxygen) provided molecular oxygen or nitric oxide is used as the target gas instead of helium. Molecular ions of pyridines are produced in the former experiments. This peculiar behavior seems to be correlated with the high multiplicity of the target molecules (triplet ground state for O2 and doublet for NO). Ab initio calculations suggest that a lower-lying quartet state of pyridine N-oxide ions might be involved in the oxygen-loss process. In the low-translational-energy regime ( c. 20–30 eV), a loss of oxygen is also detected whatever the nature of the collision gas (argon, oxygen or nitric oxide) and the relative intensity of this reaction increases with the kinetic energy of the ions. At near thermal energies ( c. 5 eV), the molecular ions of the pyridine N-oxides react with nitric oxide apparently generating two different ion–molecule complexes or intermediates responsible for the production of [M + NO]+ and [M – O]•+ ions. The deoxygenation mechanism appears therefore highly dependent upon the experimental conditions including target gas and kinetic energy.

THE DETECTION OF FREE RADICALS IN HYDROGEN ATOM REACTIONS WITH ORGANIC MOLECULES

1948 ◽  
Vol 26b (3) ◽  
pp. 343-355 ◽  
Author(s):  
G. M. Harris ◽  
A. W. Tickner
Keyword(s):  
Free Radical ◽  
Hydrogen Atom ◽  
Specific Activity ◽  
Reaction System ◽  
Radical Mechanism ◽  
Hydrogen Atoms ◽  
Experimental Conditions ◽  
Alkyl Radicals ◽  
Free Radical Mechanism ◽  
Positive Results

The Paneth–Rice free radical detection technique has been applied to the study of reactions of hydrogen atoms, produced by the discharge tube method, with two compounds, acetone and dimethyl mercury. Bismuth has been demonstrated to be a satisfactorily stable 'mirror metal' for the purpose, although some evidence was noted for the formation of a short-lived hydride of this metal under the adopted experimental conditions. A method has been devised for the preparation of radioactive bismuth mirrors of known specific activity, utilizing Bi210 ('Radium E'), obtained from uranium extraction residues, as the tracer. The hydrogen atom – acetone reaction system gave no evidence in the present work for the formerly postulated existence of free alkyl radicals. However, conclusive positive results were obtained in the case of the dimethyl mercury reaction. Studies in which the methane–ethane ratio in the products of the latter reaction was compared in presence and absence of the radical-sensitive mirror have further supported a previously proposed free radical mechanism.

scholarly journals High Voltage Electric Discharge for Recovery of Chlorogenic Acid from Tobacco Waste

2021 ◽  
Vol 13 (8) ◽  
pp. 4481
Author(s):  
Marija Banožić ◽  
Antun Jozinović ◽  
Jovana Grgić ◽  
Borislav Miličević ◽  
Stela Jokić
Keyword(s):  
Chlorogenic Acid ◽  
Process Parameters ◽  
Electric Discharge ◽  
High Voltage ◽  
Treatment Time ◽  
Strong Dependence ◽  
Extraction Procedure ◽  
Polynomial Equation ◽  
Experimental Conditions ◽  
Tobacco Waste

Three fractions of tobacco waste (scrap, dust and midrib) were subjected to a high voltage electric discharge (HVED) assisted extraction procedure under different experimental conditions: solvent:solid ratio (300, 500, 700 mL/g), frequency (40, 70, 100 Hz) and treatment time (15, 30, 45 min), in order to study the influence of these conditions on the content of chlorogenic acid. The content of chlorogenic acid ranged from 1.54 to 3.66 mg/100 g for scrap, from 1.90 to 2.97 mg/100 g for dust, and from 2.30 to 3.38 mg/100 g for midrib extract, showing a strong dependence on the applied process parameters. The temperature change and the change in pH and electrical conductivity of the extracts after high voltage discharge treatment were also observed. The studied process parameters showed a statistically significant effect on the chemical and physical properties of the extracts from tobacco waste as well as on the content of chlorogenic acid, indicating the potential of HVED assisted processes in the separation of chlorogenic acid from tobacco industry waste. Multiple regression analysis was used to fit the results for the chlorogenic acid to a second order polynomial equation and the optimum conditions were determined.

scholarly journals Oxidative hemolysis of erythrocytes and its inhibition by free radical scavengers.

1988 ◽  
Vol 263 (36) ◽  
pp. 19809-19814
Author(s):  
E Niki ◽  
E Komuro ◽  
M Takahashi ◽  
S Urano ◽  
E Ito ◽  
...  
Keyword(s):  
Free Radical ◽  
Free Radical Scavengers ◽  
Radical Scavengers ◽  
Oxidative Hemolysis

Novel C-9, 9'-O-acyl Esters of (-)-Carinol as Free-radical Scavengers and Xanthine Oxidase Enzyme Inhibitors: Synthesis and Biological Evaluation

2013 ◽  
Vol 9 (1) ◽  
pp. 100-103 ◽  
Author(s):  
Praveen Kumar Suryadevara ◽  
Hari Babu Tatipaka ◽  
Rama Subba Rao Vidadala ◽  
Ashok k Tiwari ◽  
Janaswamy Madhusudana Rao ◽  
...  
Keyword(s):  
Free Radical ◽  
Xanthine Oxidase ◽  
Enzyme Inhibitors ◽  
Biological Evaluation ◽  
Free Radical Scavengers ◽  
Radical Scavengers ◽  
Oxidase Enzyme ◽  
Synthesis And Biological Evaluation

scholarly journals Alternative Mitochondrial Electron Transfer as a Novel Strategy for Neuroprotection

2011 ◽  
Vol 286 (18) ◽  
pp. 16504-16515 ◽  
Author(s):  
Yi Wen ◽  
Wenjun Li ◽  
Ethan C. Poteet ◽  
Luokun Xie ◽  
Cong Tan ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Free Radical ◽  
Cerebral Ischemia ◽  
Complex I ◽  
Focal Cerebral Ischemia ◽  
Neurological Diseases ◽  
Ischemia Reperfusion ◽  
Free Radical Scavengers ◽  
Mitochondrial Complex ◽  
Novel Strategy

Neuroprotective strategies, including free radical scavengers, ion channel modulators, and anti-inflammatory agents, have been extensively explored in the last 2 decades for the treatment of neurological diseases. Unfortunately, none of the neuroprotectants has been proved effective in clinical trails. In the current study, we demonstrated that methylene blue (MB) functions as an alternative electron carrier, which accepts electrons from NADH and transfers them to cytochrome c and bypasses complex I/III blockage. A de novo synthesized MB derivative, with the redox center disabled by N-acetylation, had no effect on mitochondrial complex activities. MB increases cellular oxygen consumption rates and reduces anaerobic glycolysis in cultured neuronal cells. MB is protective against various insults in vitro at low nanomolar concentrations. Our data indicate that MB has a unique mechanism and is fundamentally different from traditional antioxidants. We examined the effects of MB in two animal models of neurological diseases. MB dramatically attenuates behavioral, neurochemical, and neuropathological impairment in a Parkinson disease model. Rotenone caused severe dopamine depletion in the striatum, which was almost completely rescued by MB. MB rescued the effects of rotenone on mitochondrial complex I-III inhibition and free radical overproduction. Rotenone induced a severe loss of nigral dopaminergic neurons, which was dramatically attenuated by MB. In addition, MB significantly reduced cerebral ischemia reperfusion damage in a transient focal cerebral ischemia model. The present study indicates that rerouting mitochondrial electron transfer by MB or similar molecules provides a novel strategy for neuroprotection against both chronic and acute neurological diseases involving mitochondrial dysfunction.

scholarly journals Mechanistic Insight into Antimicrobial and Antioxidant Potential of Jasminum Species: A Herbal Approach for Disease Management

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1089
Author(s):  
Acharya Balkrishna ◽  
Akansha Rohela ◽  
Abhishek Kumar ◽  
Ashwani Kumar ◽  
Vedpriya Arya ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Drug Resistance ◽  
Free Radicals ◽  
Free Radical ◽  
Microbial Pathogens ◽  
Free Radical Scavengers ◽  
Bioactive Constituents ◽  
Global Issues ◽  
Iridoid Glucosides ◽  
Insight Into

Drug resistance among microbial pathogens and oxidative stress caused by reactive oxygen species are two of the most challenging global issues. Firstly, drug-resistant pathogens cause several fatalities every year. Secondly aging and a variety of diseases, such as cardiovascular disease and cancer, are associated with free radical generated oxidative stress. The treatments currently available are limited, ineffective, or less efficient, so there is an immediate need to tackle these issues by looking for new therapies to resolve resistance and neutralize the harmful effects of free radicals. In the 21st century, the best way to save humans from them could be by using plants as well as their bioactive constituents. In this specific context, Jasminum is a major plant genus that is used in the Ayurvedic system of medicine to treat a variety of ailments. The information in this review was gathered from a variety of sources, including books, websites, and databases such as Science Direct, PubMed, and Google Scholar. In this review, a total of 14 species of Jasminum have been found to be efficient and effective against a wide variety of microbial pathogens. In addition, 14 species were found to be active free radical scavengers. The review is also focused on the disorders related to oxidative stress, and it was concluded that Jasminum grandiflorum and J. sambac normalized various parameters that were elevated by free radical generation. Alkaloids, flavonoids (rutoside), terpenes, phenols, and iridoid glucosides are among the main phytoconstituents found in various Jasminum species. Furthermore, this review also provides insight into the mechanistic basis of drug resistance, the generation of free radicals, and the role of Jasminum plants in combating resistance and neutralizing free radicals.

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