Metal complexes with ligands—organic phosphites as polyolefin antioxidants. III. Kinetics and mechanism of the inhibiting action of individual stable Cu(i)-complexes with phosphites

The general features of behavior of kinetically labile complexes (metal phosphite) revealed earlier ^1,2 provide the basis for the prediction of the activity of a new class of oxidation inhibitors. These are individual, stable metal complexes with organic phosphites as main ligands. The remarkable feature of these complexes, as shown as in this article on Cu(I) complexes, is the significant increase in the stoichiometric coefficient of inhibition f due to the suppression of the additional chain consumption of phosphite in the complex. The study of the initiated oxidation of styrene and solid isotactic polypropylene has proved that the phosphite complexes with Cu(I) ion are more effective than free, noncoordinated phosphites; quantitative characteristics of the inhibiting action of these complexes have been calculated. It is proved that termination of oxidation kinetic chains on the inhibitor molecules includes oxidation of coordinated phosphite without changing the oxidation degree of the central ion of metal. During inhibition of the oxidation of the substrate with mixtures of phosphite complexes of Cu(I) and phosphites (in styrene) or with aromatic amines (in polypropylene), the phenomenon of nonadditive strengthening (synergism) was discovered and the mechanism and kinetic regularities of synergism were revealed. This investigation of the phosphite complexes of the ions of Cu(I) presents new opportunities for controlled stabilization of polymers in uncontrolled conditions.     

Manganese-depleted/reconstituted photosystem II core complexes in solution and liposomes

Chlorophyll fluorescence transients measurements were employed to study the functioning of spinach photosystem II (PS II) core complexes in solution or reconstituted into liposomes. Lipid vesicles were prepared from soybean phospholipids (asolectine) or a mixture of spinach thylakoid lipids. In comparison with intact PS II core complexes comprising two distinct fluorescence phases, designated as O-J and J-P, complete suppression of the latter phase in Mn-depleted samples was observed. An increase of magnitude of the J-P phase in the presence of exogenous MnCl(2) (4 Mn/RC) indicate in favor of partial restoring of oxygen-evolution activity of PS II. The J-P phase observed in PS II in solution was characterized by a lifetime of ~320 ms, while in liposome-reconstituted samples this phase was accelerated up to ~20 ms in case of asolectine and up to ~9 ms in case of a mixture of thylakoid lipids. These data clearly suggest that lipid environment stimulates the steady-state rate of oxygen evolution. The effect of lipids is likely based on keeping the embedded proteins in optimal structure for efficient functioning.     

Phase operator properties in quantum optics

Eigenstate properties of the phase variables of quantum optics fields are investigated. Arbitrary states are expanded in them. The statistics of these states are determined. The normalformof the corresponding phase operator is found.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 44–48, December, 1972.     

On the temperature of nonequilibrium optical fields

The dependence of the temperature of single-mode optical radiation on the relative dispersion of the number of photons is investigated. It is shown that the amplitude-stabilized field oscillator has a temperature twice as high as the oscillator excited by a heat source for the same mean energy. Further increase in the temperature of the stationary radiation field is possible by transition to nonclassical states not described by a positive definite quasi-probability function P().Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 7–13, June, 1972.     

Ions and ion pairs in anionic activated polymerization of ϵ-caprolactam

The effect of concentration of the catalytic system on the initial rate of the anionic activated polymerization of ?-caprolactam (AAPC) has been studied. It is shown that the data can be rationalized only by considering (along with side reactions such as Claisen condensation) the fact that chain growth involves both free anions and ion pairs. The possibility of formation of various associates is discussed. Quantum-chemical calculations suggest that, in the alkali metal lactamate molecule, negative charge is delocalized among the O and N heteroatoms. A possible structure for the ion pair of catalyst is suggested. The states of the Li, Na and K lactamate molecules under the conditions for AAPC are determined from conductivity measurements. Kinetic studies of AAPC with various counter ions are also described. For the Li salt, the kinetic data conflict with the results of conductometric measurements. Suppression of the dissociation of sodium caprolactamate by addition of a neutral electrolyte, sodium tetraphenylborate, results in a drastic decrease in the initial rate of polymerization, suggesting that AAPC proceeds through both free anions and ion pairs. The possibility of polymerization through the ion-coordinative mechanism is considered.     

Mass spectrometer with a multichannel ion detector based on microchannel plates

Position sensitive detectors based on microchannel plates were introduced in a mass spectrometer. With the help of this multichannel ion detector, the measurement time and errors are reduced significantly.     

Quantifying uncertainty in the measurement of arsenic in suspended particulate matter by Atomic Absorption Spectrometry with hydride generator

Arsenic is the toxic element, which creates several problems in human being specially when inhaled through air. So the accurate and precise measurement of arsenic in suspended particulate matter (SPM) is of prime importance as it gives information about the level of toxicity in the environment, and preventive measures could be taken in the effective areas. Quality assurance is equally important in the measurement of arsenic in SPM samples before making any decision. The quality and reliability of the data of such volatile elements depends upon the measurement of uncertainty of each step involved from sampling to analysis. The analytical results quantifying uncertainty gives a measure of the confidence level of the concerned laboratory. So the main objective of this study was to determine arsenic content in SPM samples with uncertainty budget and to find out various potential sources of uncertainty, which affects the results. Keeping these facts, we have selected seven diverse sites of Delhi (National Capital of India) for quantification of arsenic content in SPM samples with uncertainty budget following sampling by HVS to analysis by Atomic Absorption Spectrometer-Hydride Generator (AAS-HG). In the measurement of arsenic in SPM samples so many steps are involved from sampling to final result and we have considered various potential sources of uncertainties. The calculation of uncertainty is based on ISO/IEC17025: 2005 document and EURACHEM guideline. It has been found that the final results mostly depend on the uncertainty in measurement mainly due to repeatability, final volume prepared for analysis, weighing balance and sampling by HVS. After the analysis of data of seven diverse sites of Delhi, it has been concluded that during the period from 31^st Jan. 2008 to 7^th Feb. 2008 the arsenic concentration varies from 1.44 ± 0.25 to 5.58 ± 0.55 ng/m³ with 95% confidence level (k = 2).     

Evolution of crystallization structure during deep deformation and annealing of single crystals of austenitic carbon steel

The distribution of alloying elements, impurities, and secondary phases in axial and interaxial regions was studied for single crystals of the austenitic carbon steel, 04Kh17N14M3BG2, with the classical cross-shaped dendritic structure. It was shown that the interaxial regions are enriched with chromium, molybdenum, and carbon and contain precipitates of Cr₂₃C₆ and Mo₂C. The chemical and phase inhomogeneities, connected with dendritic crystallization, are stable with respect to the effect of deep deformation and annealing, and in the finished product evolve into bands with a different content of impurities and second phase particles.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 62–66, November, 1991.     

Photochemical properties of photosystem 1 immobilized in a mesoporous semiconductor matrix

The pigment-protein complex of photosystem 1 (PS1) isolated from cyanobacterium Synechocystis sp. PCC 6803 has been adsorbed on a solid mesoporous film made from TiO₂ nanoparticles. was on The TiO₂ film supported on a glass substrate with a surface area of 1 cm² adsorbs up to 0.045 nmol of PS1. PS1 molecules are distributed in the pores of the mesoporous support. Immobilization has an insignificant effect on the optical and photochemical properties of PS1. A reversible photoinduced EPR signal from the oxidized primary electron donor P700 of immobilized PS1 has been detected. It has been shown by photoelectrochemical methods that the photoexcitation of PS1 results in electron injection from PS1 to the conduction band of TiO₂.     

Structural characteristics of different types of nanoparticles synthesised in mesomorphic metal alkanoates

The class of thermotropic ionic liquid crystals (LCs) of the metal alkanoates possesses a number of unique properties, such as intrinsic ionic conductivity, high dissolving ability and ability to form time-stable mesomorphic glasses. These ionic LCs can be used as nanoreactors for the synthesis and stabilisation of different types of nanoparticles (NPs). Thus, some semiconductors, metals and core/shell NPs were chemically synthesised in the thermotropic ionic liquid crystalline phase (smectic A) of the cadmium octanoate (CdC₈) and of the cobalt octanoate (CoC₈). By applying the scanning electron microscopy, the cadmium and cobalt octanoate composites containing CdS, Au, Ag and core/shell Au/CdS NPs have been studied. NPs’ sizes and dispersion distribution of the NPs’ size in the nanocomposites have been obtained.