The effect of cation concentration on the nitrogen splitting constant of nitroxide free radicals

1990 ◽  
Vol 55 (10) ◽  
pp. 2377-2380
Author(s):  
Hamza A. Hussain
Keyword(s):  
Hydrogen Peroxide ◽  
Hydrogen Bonding ◽  
Free Radicals ◽  
Esr Spectroscopy ◽  
The Other ◽  
Tetraethylammonium Bromide ◽  
Splitting Constant ◽  
The One ◽  
Positively Charged ◽  
Two Equilibria

Nitroxide free radicals prepared from diethylamine, piperidine and pyrrolidine by oxidation with hydrogen peroxide were studied by ESR spectroscopy. The changes in the 14N splitting constant (aN) caused by the addition of KBr or tetraethylammonium bromide were measured in dependence on the concentration of the ions. For diethylamine nitroxide and piperidine nitroxide, the results are discussed in terms of two equilibria: the one, involving the anion, is associated with a gain or loss of hydrogen bonds to the nitroxide oxygen atom, the other is associated with the formation of solvent shared units involving the cation, which results in changes in the hydrogen bonding strenght. The large increase in the aN value in the case of pyrrolidine nitroxide is explained in terms of an interaction from one side of the positively charged N atom; the increase in aN in the case of diethylamine and piperidine nitroxides is explained in terms of interactions with both sides of the positively charged N atom.

Structural Variety of Copper(II)-Peroxide Adducts and Its Relevance to DNA Cleavage

1999 ◽  
Vol 54 (1-2) ◽  
pp. 94-99 ◽  
Author(s):  
Satoshi Nishino ◽  
Teruyuki Kobayashi ◽  
Mami Kunita ◽  
Sayo Ito ◽  
Yuzo Nishida
Keyword(s):  
Hydrogen Peroxide ◽  
High Activity ◽  
Dna Cleavage ◽  
Esr Spectroscopy ◽  
Spin Trapping ◽  
The Other ◽  
Experimental Conditions ◽  
Structural Variety ◽  
Supercoiled Form ◽  
Tetradentate Ligands

The reactivity of copper(II) compounds with several tetradentate ligands towards some spin-trapping reagents was studied in the presence of hydrogen peroxide. The compounds used in this study are roughly divided into two groups based on the reactivity towards 2 ,2 ,6 ,6 -tetramethyl-4-piperidinol(and also 2,2,6,6-tetramethyl-4-piperidone), which are trapping agents for singlet oxygen, 1O2 (1Δg); The A-group compounds exhibited a high activity to form the corresponding nitrone radical, which was detected by ESR spectroscopy, but corresponding activity of the B-group compounds was very low. The A-group compounds defined as above exhibited high activity for cleavage of DNA(supercoiled Form I) in the presence of hydrogen peroxide, yielding DNA Form II (relaxed circular) or Form III (linear duplex) under our experimental conditions ([Cu(II)]=0.1~0.5 mᴍ). On the other hand, the B-group compounds effected complete degradation of the DNA (double-strand scission) under the same experimental conditions, formation of Form II or Form III DNA was negligible. Two different DNA cleavage patterns observed for A-and B-group compounds were elucidated by the different structural property of the copper(II)-peroxide adducts, which is controlled by the interaction through both DNA and the peripheral group of the ligand system

scholarly journals Oxidative Stress in Dog with Heart Failure: The Role of Dietary Fatty Acids and Antioxidants

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Emmanuelle Sagols ◽  
Nathalie Priymenko
Keyword(s):  
Oxidative Stress ◽  
Heart Failure ◽  
Fatty Acids ◽  
Free Radicals ◽  
Vitamin E ◽  
Essential Fatty Acids ◽  
Dietary Fatty Acids ◽  
The Other ◽  
The One

In dogs with heart failure, cell oxygenation and cellular metabolism do not work properly, leading to the production of a large amount of free radicals. In the organism, these free radicals are responsible of major cellular damages: this is oxidative stress. However, a suitable food intake plays an important role in limiting this phenomenon: on the one hand, the presence of essential fatty acids in the composition of membranes decreases sensitivity of cells to free radicals and constitutes a first protection against the oxidative stress; on the other hand, coenzyme Q10, vitamin E, and polyphenols are antioxidant molecules which can help cells to neutralize these free radicals.

Anharmonicity and Hydrogen Bonding. The in-plane OH Bending and its Combination with the OH Stretching Vibration

1971 ◽  
Vol 49 (9) ◽  
pp. 1539-1544 ◽  
Author(s):  
M. Asselin ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bonding ◽  
The Other ◽  
Effect Of Temperature ◽  
Secondary Alcohols ◽  
Coupling Constant ◽  
Tertiary Alcohols ◽  
Anharmonicity Constant ◽  
Stretching Vibration ◽  
The One ◽  
Anharmonic Coupling

The infrared spectra of isopropanol, tert-butanol, and their deuterated homologues were measured between 1600 and 1160 cm−1 in a mixture of CCl3F and methylcyclohexane-d14 at temperatures ranging from 20 to −182 °C. The assignments of the in-plane OH deformation (δOH) bands of alcohols are confirmed by these low temperature measurements. An explanation is proposed for the great apparent differences between the δOH frequencies of primary and secondary alcohols on the one hand, and tertiary alcohols on the other. The effect of temperature on the δOH frequency of hydrogen bonded alcohols is found to be slight. Hydrogen bonding increases significantly the anharmonic coupling constant between νOH and δOH It remains, however, much smaller than the anharmonicity constant of νOH itself.

scholarly journals Flavonoids with Glutathione Antioxidant Synergy: Influence of Free Radicals Inflow

Antioxidants ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 695 ◽  
Author(s):  
Igor Ilyasov ◽  
Vladimir Beloborodov ◽  
Daniil Antonov ◽  
Anna Dubrovskaya ◽  
Roman Terekhov ◽  
...  
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Antioxidant Capacity ◽  
Sulfonic Acid ◽  
Lag Time ◽  
The Other ◽  
Molar Ratio ◽  
Different Types ◽  
Great Excess ◽  
The One

This report explores the antioxidant interaction of combinations of flavonoid–glutathione with different ratios. Two different 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid radical (ABTS•+)-based approaches were applied for the elucidation of the antioxidant capacity of the combinations. Despite using the same radical, the two approaches employ different free radical inflow systems: An instant, great excess of radicals in the end-point decolorization assay, and a steady inflow of radicals in the lag-time assay. As expected, the flavonoid–glutathione pairs showed contrasting results in these two approaches. All the examined combinations showed additive or light subadditive antioxidant capacity effects in the decolorization assay. This effect showed slight dilution dependence and did not change when the initial ABTS•+ concentration was two times as high or low. However, in the lag-time assay, different types of interaction were detected, from subadditivity to considerable synergy. Taxifolin–glutathione combinations demonstrated the greatest synergy, at up to 112%; quercetin and rutin, in combination with glutathione, revealed moderate synergy in the 30–70% range; while morin–glutathione appeared to be additive or subadditive. In general, this study demonstrated that, on the one hand, the effect of flavonoid–glutathione combinations depends both on the flavonoid structure and molar ratio; on the other hand, the manifestation of the synergy of the combination strongly depends on the mode of inflow of the free radicals.

Rubber, Polyisoprenes and Allied Compounds. II. The Molecule-Linking Capacity of Free Radicals and Its Bearing on the Mechanism of Vulcanization and Photo-Gelling Reactions

1943 ◽  
Vol 16 (3) ◽  
pp. 467-478
Author(s):  
Ernest Harold Farmer ◽  
Stephen E. Michael
Keyword(s):  
Experimental Investigation ◽  
Free Radicals ◽  
Benzoic Acid ◽  
Organic Acids ◽  
Benzoyl Peroxide ◽  
Chemical Nature ◽  
The Other ◽  
Benzenoid Hydrocarbons ◽  
The Subject ◽  
The One

Abstract Ostromislensky discovered that benzoyl peroxide when heated with rubber to 140° brought about a species of vulcanization of the rubber, the chemical nature of which has been the subject of much conjecture and experimental investigation. It was thought at first that the process was essentially one of oxidation and, indeed, free benzoic acid derived from the peroxide was isolated by Ostromislensky from the reaction product; but van Rossem, Dekker, and Prawirodipoero found that, although much benzoic acid was liberated during the reaction, some became united with the rubber, and could afterwards be freed by saponification. Van Rossem and his collaborators, however, were unable to correlate the accumulated observations with the previously published generalizations of Gelissen and Hermans concerning the nature of the reactions between benzoyl peroxide on the one hand and numerous substances, including alcohols, organic acids, and saturated and benzenoid hydrocarbons, on the other; nevertheless, they agreed with Gelissen and Hermans on one point, viz., that to some extent cleavage of the peroxide with formation of benzoic acid probably occurred, and they suggested that the concomitant reaction was a dehydrogenation of the rubber, the latter possibly becoming cross-linked as a result (2C5H8+PhCO·O·O·COPh→—C5H7·C5·H7—+2PhCO2H). Subsequently, Ostromislensky, following useful observations by Bock, made a new examination of the reaction, and concluded that it proceeded according to the equation:

scholarly journals The effect of Hydrogen Peroxide on the viability of Beauveria bassiana and their ability for radial growth on Chitin Agar

2014 ◽  
Vol 8 (1) ◽  
pp. 27-32
Author(s):  
Hussein Magtoff Diwan ◽  
Husein Neayma Keshmer ◽  
Majed Ibrahim Abdela ◽  
Belasim Ahmed Abas
Keyword(s):  
Hydrogen Peroxide ◽  
Beauveria Bassiana ◽  
Radial Growth ◽  
Date Palm ◽  
Agar Medium ◽  
Fungal Spores ◽  
Petri Dish ◽  
The Other ◽  
Control Group ◽  
The One

This study aimed to evaluate the effects of five concentrations of hydrogen peroxide (50, 100,200,300,400) ppm on the viability of Beauveria bassiana spores after 1,2,3,4 days of exposure at 28 ± 1C° and on the radial growth ability of the fungus on chitin agar medium after 11 days of incubation at 26 ± 1C°.This fungus was also used to control the Date palm dubas Ommatissus lybicus. The results showed that the viability of B. bassiana spores of control (distill water with fungal spores) of a rate ranged between 157 – 257 colony/ petri dish on potato dextrose agar and the rate 257 colony/petri dish was higher than those of other treatments, while the rate 91.7 colony/petri dish at 50ppm concentration of hydrogen peroxide was the best p= 0.05 in comparison with the viability rate of other treatments in which the spores were exposed to highest concentrations of hydrogen peroxide. It was also seen that spores lost their viability after exposure to 400 ppm of hydrogen peroxide. On the other hand, the results showed that the rate of radial growth 3.46cm in control group after 4 days of incubation in comparison with this in the other group was higher. The fungus showed lowest rate of radial growth 0.43cm after one day of incubation p= 0.05, while the one day exposure of spores to each of 50,100 ppm of hydrogen peroxide showed 3.47,3.5cm respectively which were significantly higher p= 0.05 in comparison with other concentrations, improving which the higher concentration the lower activity of fungal degrade chitin.

Electrostatics of two charged conducting spheres

2012 ◽  
Vol 468 (2145) ◽  
pp. 2829-2848 ◽  
Author(s):  
John Lekner
Keyword(s):  
Surface Charge ◽  
Close Approach ◽  
The Other ◽  
Charge Ratio ◽  
Electrostatic Energy ◽  
Charge Densities ◽  
Conducting Spheres ◽  
The One ◽  
Positively Charged ◽  
Charged Spheres

We prove that two charged conducting spheres will almost always attract each other at close approach, even when they have like charges. The one exception is when the two spheres have the same charge ratio that they would obtain by being brought into contact. In this case, they repel, and we derive an analytical expression for the force at contact, for any size ratio, generalizing a force formula for equal spheres obtained by Kelvin in 1853. We also give the electrostatic energy of two arbitrarily charged spheres, and its analytical forms at large and small separations. Expressions are derived for the surface charge densities of the two spheres. Attraction occurs between two positively charged spheres because of mutual polarization: one of the spheres obtains a negatively charged region (neighbouring the other sphere).

scholarly journals Operational and technical considerations for microbial electrosynthesis

2012 ◽  
Vol 40 (6) ◽  
pp. 1233-1238 ◽  
Author(s):  
Joachim Desloover ◽  
Jan B.A. Arends ◽  
Tom Hennebel ◽  
Korneel Rabaey
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transfer ◽  
Industrial Process ◽  
The Other ◽  
Extracellular Electron Transfer ◽  
Electrode Design ◽  
Product Removal ◽  
The One ◽  
Biofilm Development ◽  
Technical Considerations

Extracellular electron transfer has, in one decade, emerged from an environmental phenomenon to an industrial process driver. On the one hand, electron transfer towards anodes leads to production of power or chemicals such as hydrogen, caustic soda and hydrogen peroxide. On the other hand, electron transfer from cathodes enables bioremediation and bioproduction. Although the microbiology of extracellular electron transfer is increasingly being understood, bringing the processes to application requires a number of considerations that are both operational and technical. In the present paper, we investigate the key applied aspects related to electricity-driven bioproduction, including biofilm development, reactor and electrode design, substrate fluxes, surface chemistry, hydrodynamics and electrochemistry, and finally end-product removal/toxicity. Each of these aspects will be critical for the full exploitation of the intriguing physiological feat that extracellular electron transfer is today.

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

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