Matrix-assisted laser desorption/ionization-post source decay fragmentation of cystine- containing amphibian peptides with novel cysteine tags

Long disulphide-containing peptides brevinins 1E and 2Ec from the skin secretion of the frog Rana ridibunda were reduced and alkylated with ten novel and three known derivatizing agents. Nine of novel reagents are maleimide derivatives. The peptides were also reduced with DTT directly onto the MALDI target without alkylation. Modified samples were subjected to MALDI-PSD study. Procedures, fragmentation patterns, fragment ion signal abundances and sequence coverage for two peptides modified with thirteen tags (or on-plate reduced) are described. The fast on-plate procedure for reduction/alkylation was applied to Rana ridibunda crude secretion, providing intensive signals of derivatized peptides. The corresponding ions may be used for the MS/MS sequencing procedure.     

To the problem of the intraday nutational motions of the earth pole

Based on celestial-mechanics concepts, we provide an amplitude–frequency analysis of the intraday Earth pole oscillations in terms of classical mechanics. An approximate analytical model for real trajectory measurements of the polar motion in a near-day time interval has been identified.     

Copolymers of 2-Deoxy-2-Methacrylamido-D-Glucose with Aminoacrylates and Allylamine Hydrochloride

New polyvinylsaccharides containing primary or tertiary amino groups were synthesized by radical copolymerization of 2-deoxy-2-methacrylamido-D-glucose (MAG) with 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl methacrylate (DEAEM), or allylamine hydrochloride. The reactivity ratios of comonomers were determined. The effect of copolymer composition on the conformational properties of macromolecules was detected. For MAG-DEAEM copolymers with DEAEM unit content more than 60 mol-% the increase of degree of ionization causes conformational transition at α = 0.3 to 0.7 from compact polymer coil to loose coil due to the electrostatic repulsion of charged amino groups. The increase of MAG content in copolymers is accompanied by a decrease of their cytotoxicity.     

Rheological and phase behavior of polyamidobenzimidazole solutions under the effect of temperature and deformation

The viscosities and phase stabilities of solutions of rigid-chain polyamidobenzimidazole and its copolymer with poly(p-phenylene terephthalamide) in dimethylacetamide are investigated during their flow within wide temperature and shear-rate ranges. These systems are characterized by amorphous separation with the lower critical temperature of mixing. In the range of the phase-separation temperature, viscosity passes through a minimum owing to the formation of a microemulsion followed by gelation of the reversible system accompanied by its blurring due to uncompleted phase separation. The temperatures of phase separation and the temperatures of minimum viscosity for the investigated solutions decline with an increase in the polymer concentration and increase with an increase in the shear rate.     

Thermochemical properties of gaseous and liquid polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and dibenzofurans

The analysis and systematization of the known and calculation of the unknown thermochemical characteristics (the standard enthalpy of formation, the standard entropy, the heat capacity, etc.) of widespread hazardous isomers of gaseous and liquid compounds of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans are carried out.     

Synthesis and Intramolecular Cyclization of ω-Haloalkyl Dithiophosporus Acid Esters

y -Haloalkyl dithiophosphorus acid esters undergo the thermal rearrangement resulting in the corresponding 2-oxo-1,3,2-dithiaphosphacyclanes.     

Annelated Pyrrolo[1,2‐a][1,4]diazepines in Mannich Reaction

New Mannich bases were synthesized through an interaction of fused pyrrolo[1,2‐a][1,4]diazepines with secondary amines and formaldehyde. The reaction appears to be regioselective, yielding the monosubstituted products bearing N,N‐dialkylaminomethyl group at position 2 of the pyrrolodiazepine moiety.     

Polymorphism and solvatomorphism of bicalutamide

Single crystals of the crystallosolvate [bicalutamide + DMSO] with 1:1 stoichiometry were grown, and their structures were solved by X-ray diffraction methods. Polymorphic modifications I and II, the amorphous state, and the DMSO crystallosolvate of bicalutamide were prepared and thermochemistry of fusion processes was studied by DSC technique. The temperature dependence of the saturated vapor pressure of polymorphic form I was obtained and the thermodynamic characteristics of the sublimation process including the crystal lattice energy were calculated. The solution enthalpies of the forms under consideration and the crystallosolvate were acquired by the solution calorimetry procedure. The phase transition enthalpies estimated for form I, form II, and the amorphous state followed the rank order: form I— > form II, form I— > amorphous state, and form II— > amorphous state. The crystal lattice energy of polymorphic form II was determined using the results of sublimation and solution calorimetric experiments. The difference between the crystal lattice energy of the crystallosolvate and unsolvated phases was observed. The dissolution kinetics of forms I, II, the amorphous state, and DMSO solvate in water were investigated.     

Concentration of neptunium from the ground waters of the Karachai Lake contamination area

Neptunium(V) sorption from simulated and natural ground waters, containing ammonium carbonates, acetates, oxalates and citrates, on multi-walled carbon nanotubes (MWCNT) «Taunit»^® was studied. It has been discovered that ammonium acetate and carbonate are not adsorbed on MWCNT «Taunit», but humic acid, oxalates and citrates are adsorbed quite efficiently. Neptunium is extracted from the ammonium carbonate solution by MWCNT «Taunit» with low sorption degrees. While conducting the sorption process from the ammonium carbonate solution with addition of organic substances, it has been revealed that the neptunium extraction degree is not dependent on addition of humic acid and acetate. At the same time, the extraction degree is substantially increased at addition of ammonium oxalate and citrate. It enables modifying MWCNT «Taunit» by means of related organic ligands and using them for the purpose of extraction and concentration of neptunium from contaminated natural waters.