Precipitation of yellowcake from pregnant regenerate by various reagents

Journal of Radioanalytical and Nuclear Chemistry - In the present paper the development and application of a novel somatostatin radioimmunoassay are described. 125I-labeling of...     

Synthesis,structure and properties of N-aminosaccharin – A selective inhibitor of human carbonic anhydrase I

Previously unknown N-aminosaccharin was prepared in good yield via the one-step direct amination of saccharin sodium salt with hydroxylamine-O-mesitylenesulfonic acid (MSH) and its reactivity investigated. N-aminosaccharin and its derivatives were tested against hCA isoforms and the parent compound was identified to be a selective, low micromolar inhibitor (K_i = 8.8 μM) of hCA I. These findings provide a ligand-efficient starting point for the design of potent hCA I inhibitors – a promising drug target for retinal/cerebral edema treatment.     

Kinetics of a bimolecular chemical reaction in the liquid phase with association of both reactants

Mathematical modeling of a bimolecular chemical reaction in the liquid phase was carried out taking account of association of both reactants. The formally simple chemical reaction is thus transformed into a multistage process, which results in the formation of temporal dissipative structures. It was found that, apart from the usual dynamic modes, there appear oscillations of the concentrations of intermediates, characterized by two considerably differing periods.     

Heat capacity of the white pine biocarbon preform and the related biocarbon/copper composite

This paper reports on measurements in the 80–300-K temperature interval of the heat capacity at constant pressure C _p (T) of high-porosity amorphous white pine carbon preforms (biocarbon) prepared by pyrolysis (carbonization) at T _carb = 1000 and 2400°C in an argon flow. The dependences C _p (T) for biocarbon/copper composites based on the carbon preforms obtained have also been determined. It is shown that the mixture rule holds for the composites, i.e., that C _p (T) of the composite is a sum of the heat capacities of the constituent materials taken in the corresponding ratios. Phonon mean free paths for the white pine carbon preforms prepared at T _carb = 1000 and 2400°C have been calculated and used to estimate the size of the nanocrystallites contributing to formation of the carbon frameworks of these preforms.     

A Novel and Simple Synthesis of 2-(Trifluoromethyl)-4H-thiochromen-4-ones

Abstract

Alkyl 2-mercaptophenyl ketones react with trifluoroacetic anhydride in the presence of triethylamine to give 2-(trifluoromethyl)-4H-thiochromen-4-ones, which are transformed into the corresponding pyrazoles by treatment with hydrazine hydrate and into 1,1-dioxides by oxidation with H₂O₂ in AcOH.     

A library of spectral patterns as a tool for the rapid and reliable identification of highly toxic O-alkyl-S-2-(N,N-dialkylamino)ethyl alkyl thiophosphonates based on electron-ionization mass spectra

A rapid and reliable method for group identification based on the fragmentation of highly toxic O-alkyl-S-2-(N,N-dialkylamino)ethyl alkyl thiophosphonates using electron-ionization mass spectra was proposed. This method makes it possible to relate a test substance to one of the four groups of compounds containing two identical alkyl substituents at the nitrogen atom (methyl, ethyl, propyl, or isopropyl). The essence of this method is that the mass spectrum of the test substance is compared with the generalized mass-spectrometric patterns of each of the four groups of this class with the aid of a standard procedure utilized in the NIST information retrieval program.     

An effect of heat processing on catalytic activity of a system MnO x ,SiO2/TiO2/Ti

An effect of annealing in air at temperatures 250, 350, 500, and 700°C on composition, surface structure, and catalytic activity in CO oxidation of a system MnO _x ,SiO₂/TiO₂/Ti formed by combining methods of plasma electrolytic oxidation and impregnation was examined.     

Fully Protected Glycosylated Zinc (II) Phthalocyanine Shows High Uptake and Photodynamic Cytotoxicity in MCF‐7 Cancer Cells

Phthalocyanine photosensitizers are effective in anticancer photodynamic therapy (PDT) but suffer from limited solubility, limited cellular uptake and limited selectivity for cancer cells. To improve these characteristics, we synthesized isopropylidene‐protected and partially deprotected tetra β‐glycosylated zinc (II) phthalocyanines and compared their uptake and accumulation kinetics, subcellular localization, in vitro photocytotoxicity and reactive oxygen species generation with those of disulfonated aluminum phthalocyanine. In MCF‐7 cancer cells, one of the compounds, zinc phthalocyanine {4}, demonstrated 10‐fold higher uptake, 5‐fold greater PDT‐induced cellular reactive oxygen species concentration and 2‐fold greater phototoxicity than equimolar (9 μm ) disulfonated aluminum phthalocyanine. Thus, isopropylidene‐protected β‐glycosylation of phthalocyanines provides a simple method of improving the efficacy of PDT.     

Pyrazole‐substituted Near‐infrared Cyanine Dyes Exhibit pH‐dependent Fluorescence Lifetime Properties

Near‐infrared heptamethine cyanine dye is functionalized with pyrazole derivatives at the meso‐position to induce pH‐dependent photophysical properties. The presence of pyrazole unsubstituted at ¹N‐position is essential to induce pH‐dependent fluorescence intensity and lifetime changes in these dyes. Replacement of meso‐chloro group of cyanine dye IR820 with ¹N‐unsubstituted pyrazole resulted in the pH‐dependent fluorescence lifetime changes from 0.93 ns in neutral media to 1.27 ns in acidic media in DMSO. Time‐resolved emission spectra (TRES) revealed that at lower pH, the pyrazole consists of fluorophores with two distinct lifetimes, which cor‐responds to pH‐sensitive and non‐pH‐sensitive species. In contrast, ¹N‐substituted pyrazoles do not exhibit pH response, suggesting excited state electron transfer as the mechanism of pH‐dependent fluorescence lifetime sensitivity for this class of compounds.