Radiation Chemical Studies of Methionine in Aqueous Solution: Understanding the Role of Molecular Oxygen

2010 ◽  
Vol 23 (1) ◽  
pp. 258-263 ◽  
Author(s):  
Sebastián Barata-Vallejo ◽  
Carla Ferreri ◽  
Al Postigo ◽  
Chryssostomos Chatgilialoglu
Keyword(s):  
Aqueous Solution ◽  
Molecular Oxygen ◽  
Radiation Chemical ◽  
Chemical Studies

Radiation Chemical Studies of Azodicarbonamide in Aqueous Solution

1977 ◽  
Vol 70 (2) ◽  
pp. 325 ◽  
Author(s):  
P. Neta ◽  
D. W. Whillans
Keyword(s):  
Aqueous Solution ◽  
Radiation Chemical ◽  
Chemical Studies

scholarly journals Radiation chemical studies of Gly-Met-Gly in aqueous solution

2016 ◽  
Vol 50 (sup1) ◽  
pp. S24-S39 ◽  
Author(s):  
Sebastian Barata-Vallejo ◽  
Carla Ferreri ◽  
Tao Zhang ◽  
Hjalmar Permentier ◽  
Rainer Bischoff ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Radiation Chemical ◽  
Chemical Studies

Role of the exosporial membrane in attachment and germination of C. sporogenes

1993 ◽  
Vol 51 ◽  
pp. 38-39
Author(s):  
B.J. Panessa-Warren ◽  
G.T. Tortora ◽  
J.B. Warren
Keyword(s):  
Enzymatic Degradation ◽  
Light Transmission ◽  
Extended Period ◽  
Growth Conditions ◽  
Clostridium Sporogenes ◽  
Radiation Chemical ◽  
Physical Trauma ◽  
Extended Contact ◽  
Cold Pressure

Some bacteria are capable of forming highly resistant spores when environmental conditions are not adequate for growth. Depending on the genus and species of the bacterium, these endospores are resistant in varying degrees to heat, cold, pressure, enzymatic degradation, ionizing radiation, chemical sterilants,physical trauma and organic solvents. The genus Clostridium, responsible for botulism poisoning, tetanus, gas gangrene and diarrhea in man, produces endospores which are highly resistant. Although some sporocides can kill Clostridial spores, the spores require extended contact with a sporocidal agent to achieve spore death. In most clinical situations, this extended period of treatment is not possible nor practical. This investigation examines Clostridium sporogenes endospores by light, transmission and scanning electron microscopy under various dormant and growth conditions, cataloging each stage in the germination and outgrowth process, and analyzing the role played by the exosporial membrane in the attachment and germination of the spore.

scholarly journals Quantum-Chemical Search for Keto Tautomers of Azulenols in Vacuo and Aqueous Solution

Symmetry ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 497
Author(s):  
Ewa D. Raczyńska
Keyword(s):  
Aqueous Solution ◽  
Quantum Chemical ◽  
Biologically Active ◽  
Deprotonation Reaction ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Scanty Information ◽  
Derivatives Of ◽  
Common Anion ◽  
Tautomeric Mixture

Keto-enol prototropic conversions for carbonyl compounds and phenols have been extensively studied, and many interesting review articles and even books appeared in the last 50 years. Quite a different situation takes place for derivatives of biologically active azulene, for which only scanty information on this phenomenon can be found in the literature. In this work, quantum-chemical studies have been undertaken for symmetrically and unsymmetrically substituted azulenols (constitutional isomers of naphthols). Stabilities of two enol (OH) rotamers and all possible keto (CH) tautomers have been analyzed in the gas phase {DFT(B3LYP)/6-311+G(d,p)} and also in aqueous solution {PCM(water)//DFT(B3LYP)/6-311+G(d,p)}. Contrary to naphthols, for which the keto forms can be neglected, at least one keto isomer (C1H, C2H, and/or C3H) contributes significantly to the tautomeric mixture of each azulenol to a higher degree in vacuo (non-polar environment) than in water (polar amphoteric solvent). The highest amounts of the CH forms have been found for 2- and 5-hydroxyazulenes, and the smallest ones for 1- and 6-hydroxy derivatives. The keto tautomer(s), together with the enol rotamers, can also participate in deprotonation reaction leading to a common anion and influence its acid-base properties. The strongest acidity in vacuo exhibits 6-hydroxyazulene, and the weakest one displays 1-hydroxyazulene, but all azulenols are stronger acids than phenol and naphthols. Bond length alternation in all DFT-optimized structures has been measured using the harmonic oscillator model of electron delocalization (HOMED) index. Generally, the HOMED values decrease for the keto tautomers, particularly for the ring containing the labile proton. Even for the keto tautomers possessing energetic parameters close to those of the enol isomers, the HOMED indices are low. However, some kind of parallelism exists for the keto forms between their relative energies and HOMEDs estimated for the entire molecules.

Directing the Growth of Semiconductor Nanocrystals in Aqueous Solution: Role of Electrostatics

ChemPhysChem ◽  
2008 ◽  
Vol 9 (9) ◽  
pp. 1309-1316 ◽  
Author(s):  
Hao Zhang ◽  
Yi Liu ◽  
Chunlei Wang ◽  
Junhu Zhang ◽  
Haizhu Sun ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Semiconductor Nanocrystals
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