Specific features of depth distribution profiles of implanted cobalt ions in rutile TiO<Subscript>2</Subscript>

This paper reports on the results of the calculation of the depth distribution profiles of the concentration of the impurity implanted into an anisotropic crystalline material. The sputtering of the irradiated material, fast one-dimensional diffusion of the impurity along structural channels, and accumulation of the implanted impurity at different depths have been taken into account. The results of the calculations have been compared with the experimental distribution profiles of cobalt ions implanted into the crystal structure of rutile TiO₂ along and across structural channels at different temperatures of the irradiated substrate. A comparison of the model and experimental profiles has made it possible to evaluate the precipitation rate of cobalt in the TiO₂ matrix on different precipitation centers. A model has been proposed for explaining the unusual shift in the peak of the concentration distribution of implanted ions deep into the sample with an increase in the temperature of the irradiated substrate. The model has allowed one to separate the contributions from different phases of the impurity (nanoparticles and solid solution) to the magnetism of the Co: TiO₂ system.     

Cholinesterase sensors based on screen-printed electrodes for detection of organophosphorus and carbamic pesticides

Cholinesterase sensors based on screen-printed electrodes modified with polyaniline, 7,7,8,8-tetracyanoquinodimethane (TCNQ), and Prussian blue have been developed and tested for detection of anticholinesterase pesticides in aqueous solution and in spiked grape juice. The influence of enzyme source and detection mode on biosensor performance was explored. It was shown that modification of the electrodes results in significant improvement of their analytical characteristics for pesticide determination. Thus, the slopes of the calibration curves obtained with modified electrodes were increased twofold and the detection limits of the pesticides were reduced by factors of 1.6 to 1.8 in comparison with the use of unmodified transducers. The biosensors developed make it possible to detect down to 2×10^–8 mol L^–1 chloropyrifos-methyl, 5×10^–8 mol L^–1 coumaphos, and 8×10^–9 mol L^–1 carbofuran in aqueous solution and grape juice. The optimal conditions for grape juice pretreatment were determined to diminish interference from the sample matrix.Abbreviations ChE Cholinesterase - TCNQ 7,7,8,8-Tetracyanoquinodimethane - ChO Choline oxidase - AChE Acetylcholinesterase - BChE Butyrylcholinesterase - BSA Bovine serum albumin - 2-PAM 2-Pyridine aldoxime methiodide     

Dichroism of absorption and polarization of phosphorescence of closed form of nitro-substituted indoline spiropyrans

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 5, pp. 768–773, May, 1990.     

Biosensors based on cholinesterase inhibition for insecticides, nerve agents and aflatoxin B1 detection (review)

The present review reports the research carried out during last 9 years on biosensors based on cholinesterase inhibition for nerve agents, organophosphorus and carbammic insecticides, and aflatoxin B₁ detection. Relative applications in environmental and food areas are also reported. Special attention is paid to the optimization of parameters such as enzyme immobilization, substrate concentration, and incubation time in the case of reversible inhibition by aflatoxin B₁ or irreversible inhibition by organophosphorus and carbamic insecticides, and nerve agents in order to optimize and improve the analytical performances of the biosensor. Evaluation of selectivity of the system is also discussed.     

Extraction products from <Emphasis Type="Italic">Miscanthus</Emphasis> var. ‘Soranovskii’

The chemical structures of Miscanthus var. ‘Soranovskii’ lignin fractions released via extraction of lignin from the lignocellulosic feedstock using moderately heated acetone under atmospheric pressure, without acidic and alkaline catalysts, were studied. A blend of Miscanthus stems and leaves was pretreated with water under thermobaric conditions. The acetone organosolv process subsequently afforded a substance related to a lignin-like matter-acetone organosolv Miscanthus lignin (AOML). Non-destructive analytical techniques such as FTIR spectroscopy, gas chromatography-mass spectrometry, size-exclusion chromatography, and 2D NMR were used. The IR and NMR spectroscopies revealed the AOML structure to comprise all the three major types of phenylpropane units: guaiacyl (G), syringyl (S), and p-hydroxyphenyl (H). The resultant acetone-organosolv lignin exhibits good solubility in polar solvents, moderate solubility in aromatic chemicals, and is insoluble in non-polar solvents, exhibiting the physicochemical properties of a thermoplastic polymer with a softening point of 67.0°C (onset 33.0°C, endset 81.5°C).     

Complexation of the thermally induced colored form of 6-nitrospiropyrans in a polar solvent

Conclusions Thermally induced formation of colored complexes which result in the amorphous and crystalline states of solid compounds takes place in a concentrated solution of 6-nitrospiropyrans in a polar solvent.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1984–1986, September, 1984.