4-Hydroxy-2-quinolones. 46. Esters of 1H-2-Oxo-4-hydroxy-3-quinolineacetic Acid

Different methods of synthesizing esters of 1H-2-oxo-4-hydroxy-3-quinolineacetic acid were studied. Results are given for tests of the anti-inflammatory activity of these products.     

Electrostatic Complementarity Drives Amyloid/Nucleic Acid Co-Assembly

Proteinaceous plaques associated with neurodegenerative diseases contain many biopolymers including the polyanions glycosaminoglycans and nucleic acids. Polyanion-induced amyloid fibrillation has been implicated in disease etiology, but structural models for amyloid/nucleic acid co-assemblies remain limited. Here we constrain nucleic acid/peptide interactions with model peptides that exploit electrostatic complementarity and define a novel amyloid/nucleic acid co-assembly. The structure provides a model for nucleic acid/amyloid co-assembly as well as insight into the energetic determinants involved in templating amyloid assembly.     

A concise review of nanoscopic aspects of bioleaching bacteria–mineral interactions

Bioleaching is a technology for the recovery of metals from minerals by means of microorganisms, which accelerate the oxidative dissolution of the mineral by regenerating ferric ions. Bioleaching processes take place at the interface of bacteria, sulfide mineral and leaching solution. The fundamental forces between a bioleaching bacterium and mineral surface are central to understanding the intricacies of interfacial phenomena, such as bacterial adhesion or detachment from minerals and the mineral dissolution. This review focuses on the current state of knowledge in the colloidal aspect of bacteria–mineral interactions, particularly for bioleaching bacteria. Special consideration is given to the microscopic structure of bacterial cells and the atomic force microscopy technique used in the quantification of fundamental interaction forces at nanoscale.     

Quantum effects in the kinetics of the initiation of detonation condensation waves

The features of the kinetics of the initiation of detonation condensation waves in carbon suboxide and acetylene have been experimentally studied at high pressures near the low-temperature limits. The role of quantum effects in the expansion of detonation limits has been analyzed. Quantum corrections to the endothermic reaction rates, which are caused by an increase in the high-energy tails of the momentum distribution functions at high pressures due to the manifestation of the uncertainty principle for the energy of colliding particles at a high collision frequency, have been quantitatively estimated. It has been shown that experimentally observed deviations in Arrhenius dependences of the induction periods of the initiation of detonation condensation waves are well described by the proposed quantum corrections.     

Transition‐Metal‐Free Carbon Isotope Exchange of Phenyl Acetic Acids

A transition‐metal‐free carbon isotope exchange procedure on phenyl acetic acids is described. Utilizing the universal precursor CO₂, this protocol allows the carbon isotope to be inserted into the carboxylic acid position, with no need of precursor synthesis. This procedure enabled the labeling of 15 pharmaceuticals and was compatible with carbon isotopes [¹⁴C] and [¹³C]. A proof of concept with [¹¹C] was also obtained with low molar activity valuable for distribution studies.     

Effect of cetyltrimethylammonium bromide micelles on the ionic equilibrium and the reactivity of hydrogen peroxide toward electrophilic substrates

The acid-base equilibrium of hydrogen peroxide in aqueous solutions of CTAB and the reactivity of the peroxide anion toward 4-nitrophenyl diethylphosphate and 4-toluenesulfonate were studied. It was shown that the acid ionization rate constant of hydrogen peroxide is increased by three times with increase in the CTAB concentration from 0 to 0.03 M. This makes it possible to realize the decomposition of the substrates by their reaction with the peroxide anion at lower pH values in micellar cationic systems than in aqueous solutions. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 2, pp. 83–89, March–April, 2008.     

Strain‐Promoted 1,3‐Dithiolium‐4‐olates–Alkyne Cycloaddition

Reported here is the reactivity of mesoionic 1,3‐dithiolium‐4‐olates towards strained alkynes, leading to thiophene cycloaddition products. In the process, the potential of these dipoles towards orthogonal reaction with azides, allowing efficient double ligation reactions, was discovered. A versatile process to access benzo[c]thiophenes, in an unprecedented divergent fashion, was developed and provides a new entry to unconventional polyaromatic thiophenes.     

Simulation of Fission Product Release from Microfuel Particles Taking into Account the Effects of Trapped Fraction and Concentration Jumps at the Interfaces

A modification of the FP Kinetics code [1] has been performed to calculate the fission product release from HTGR microfuel particles, allowing for chemical binding, limited solubility effects, and component concentration jumps at the interfaces of the coating layers. A comparison is made of the release curves of Cs from microfuel particles calculated using the FP Kinetics and PARFUME codes [2]. It is shown that taking into account the concentration jumps at the interfaces of the silicon carbide layer makes it possible to give a noncontradictory explanation of the experimental data obtained for Cs release in post-reactor thermal testing. The need for performing experiments to determine the limits of solubility in coating materials is noted.