Electrical conductivity of liquid and film polymer composites filled with anion-radical salts in the presence of crown ethers

In the example of alkali metal tetracyanoquinodimethanides (M⁺TCQDM), a study has been made of the influence of resonance charge exchange on the conductivity () of polymer composites filled with anion-radical salts. When neutral molecules TCQDM⁰ are introduced into such systems, this leads to an increase in as a result of the lower activation energy of jumps between states TCQDM and TCQDM⁰. The addition of molecules of crown ethers has an analogous effect: They favor the appearance in the polymer matrix (the same as in solution) of TCQDM molecules in different charge states (TCQDM⁰, TCQDM) with migration of the cation within the limits of ternary associates (CE...M⁺...A) that are formed in systems for which the ratio of the crown ether cavity diameter to the cation diameter 1.4. Symbaticity has been found in the dependences of the electrical conductivity of films and the limiting mobility of solutions with the same composition on the parameter .Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 4, pp. 446–452, July–August, 1989.     

A study of the donor properties of the carbonyl group of pyridones

The donor properties of the CO group of pyridones have been examined by studying the IR spectra of their complexes with mercury-(II)-chloride and with hydroquinone. The complexes with mercury chloride are formed by a weak O?Hg donor-acceptor bond, while the others have the character of strongly H-bonded salts of hydroxypyridinium cations. The dipole moment of N-methyl-3-pyridone, not reported so far, has also been measured, (7·2 D). These results, and the agreement between the theoretical and the experimental dipole moments, support the prediction that the donor properties of the CO group are very similar for the three isomers.     

Acid-base properties of substituted tetraphenylmethylenediphosphine dioxides

Conclusions Some tetraphenylmethylenediphosphine dioxides, substituted in the methylene bridge, were subjected to potentiometric titration in nitromethane with perchloric acid. The obtained values of the pK _a basicity constants (CH₃NO₂) obey a linear relationship with the ^* constants of the substituents.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 199–201, January, 1972.     

Examination of the swelling of heat protective hydrocolloids by DSC

While the basic fermented (sour) milk products, such as yogurt and kefir can be produced only in live flora version, the post heat-treatment is preferred in their flavored variations to increase the storage time. Casein being in sour coagulum precipitates during heat-treatment; therefore protective colloids surrounding the protein should be used to prevent it. Protective colloids are plant extracts, the most known of them are pectin and amylopectin. Basic requirement of protective colloid effect is the lower swelling temperature of hydrocolloid than the temperature of precipitation of sour coagulum. In this work we have examined the precipitation of sour coagulum as a function of the type of lactic acid bacteria cultures applied during fermentation as well as the swelling of heat protective plant hydrocolloids as a function of the composition (mainly of sugar content) of medium. To investigate the precipitation of fermented coagulum skimmed milk was fermented with mesophilic butter culture, thermophilic yogurt culture as well as with exopolysaccharide (EPS)-producing Prebiolact-2 culture. Precipitation was indicated in the increase of great extent of viscosity. Amylopectin was dispersed into aqueous solution of pH 4.5, the saccharose concentration of which was changed during the investigation of the swelling of heat protective hydrocolloids. A definite exothermic peak was assigned to the swelling of hydrocolloids during the DSC experiments. We could conclude that the precipitation temperature was increasing in the mesophilic-thermophilic-EPS producing microbes line, i.e. the heat stability and swelling temperature of hydrocolloids depend on the saccharose content of aqueous medium and they increase with rising the concentration of saccharose.     

Possible Shubnikov's formulas of chemical compounds

M. V. Lomonosov Moscow State University. Translated fromZhumal Struktumoi Khimii, Vol. 36, No. 4, pp. 760–763, July–August, 1995     

Reaction of Β-arylacryloxiranes with phenyl azide. Synthesis and chemical transformations of Β-phenylamino-Β-arylacrylyloxiranes

The reaction of -arylacrylyloxiranes with phenyl azide by refluxing in dioxane or toluene leads to -phenylamino--aryl-acrylyloxiranes. Epoxypropionyl- and -hydroxypropionyltriazoles are also isolated when the reaction is carried out in the dark without heating. It is shown that -phenylamino--arylacrylyloxiranes undergo cyclization to 3(2H)-furanones in an acidic medium, whereas they are converted to 2,3-dihydro-4-pyridones under basic-catalysis conditions.Translated from Khimiya Geterotsiklicheskikh Soedineii, No. 8, pp. 1022–1027, August, 1988.     

Distribution of reaction products (theory). Investigation of an ab initio energy-surface for F + H2 ⇀ HF + H

Bender, O'Neil, Pearson and Schaefer (BOPS) have computed ab initio energies for 232 collinear configurations of FHH, using extensive configuration interaction. We have fitted these points using an LEPS-type function. Comparison with semi-empirical surfaces for FHH shows that the general form of these surfaces is in good accord with the ab initio findings. Evidence is presented which indicates that the BOPS ab initio surface exhibits too great a drop in energy along the favoured route into the exit valley.     

Rydberg fingerprint spectroscopy: a new spectroscopic tool with local and global structural sensitivity

Rydberg spectra are shown to provide a spectral fingerprint that is sensitive to molecular structure in unique ways. The concepts are demonstrated using a set of isomeric fluorophenols and a sequence of aliphatic diamines. In the fluorophenols, the sensitivity extends to the placement of a single hydrogen atom and can be traced to the molecular charge distributions associated with the locations of atoms and functional groups with respect to the charge center. Experiments on tetramethyl diamines demonstrate that the structural sensitivity encompasses the extended molecular structure, including parts of the molecule that are remote from the ionization center. This global structure sensitivity makes Rydberg fingerprint spectroscopy uniquely suited to characterize structures of large-scale molecular systems.     

Determination of Natural Vitamin E from Italian Hazelnut Leaves

A new potential source of natural vitamin E from thirteen samples of Corylus avellana L. leaves was screened: the major Italian cultivar — Tonda romana (collected from Latium and Sardinia localities); ten local genotypes from Sardinia — Moro seme, Suconcale, Moro, Sarda grossa, Sarda grossa seme, Sarda schiacciata, Coccoredda, Sarda lunga, Sarda piccola and Sarda tardiva; wild genotype — Selvatico from Latium. The determination was performed after optimizing the high-efficiency pressurized liquid extraction (PLE) conditions of α-tocopherol from Italian hazelnut tree green leaves. Moro from Sardinia showed the highest content of α-tocopherol (237.4±0.3 μg/g d.w). Leaves of this genotype may be considered as a potential new source for natural α-tocopherol. __________ Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 538–540, November–December, 2005.     

On-line filtration system for determining total chromium and chromium in the soluble fraction of industrial effluents by flow injection flame atomic absorption spectrometry

Two manifolds were assessed for the purpose of determining both the total chromium content and that present as a soluble form in industrial effluents by flow injection flame atomic absorption spectrometry (FI-FAAS). To determine the chromium content in the soluble fraction the samples were used without additional treatment, a 0.45 microm filter being included in the FI system. To determine the total chromium content, the samples were acidified with nitric acid 20% (v/v) and heated for 30 s in a microwave oven (temperatures of about 70 degrees C were reached). The problem posed by the very different concentration range in which total and soluble chromium are present was overcome by using programmed flow rate methodology and by only partially emptying the sample loop. A personal computer controlled both the rotation speed of a peristaltic pump and the volume of sample injected into the system, thus obtaining the dispersion degree required. Using the manifold proposed, the chromium content in the soluble fraction can be determined in the 0.5-20 microg mL(-1) range using a 10 microg mL(-1) single standard for calibration. To determine the total chromium content, a calibration line in the 20-200 microg mL(-1) range was obtained using a single 50 microg mL(-1) chromium standard solution. The reliability of the semi-automatic devices was verified by comparing the results obtained with those found by treating the samples and using both FAAS in a conventional way and a spectrophotometric method using diphenylcarbazide at the 95% confidence level (ANOVA test). The proposed procedures showed a RSD lower than +/-3%.