THE CHEMICAL COMPOSITIONS OF MINERALS IN QINGZHEN METEORITE AND ITS GEOCHEMISTRY SIGNIFICANCE

The chemical compositions of silicate minerals, sulphide minerals and metal Fe-Ni in theQingzhen meteorite were measured by the microprobe analyses. Based upon these chemicalcompositions, the cosmochemical behaviour and characteristics of the existing forms of themajor elements in the Qinzhen meteorite have been discussed. These characteristics show thatunder the S-rich, O-poor, and strongly reducing conditions, the light metal elements, such asCa, Mg, K, Na may form sulphide, and metal Fe-Ni may contain Si and P. However, we con-sider that the light metal-sulphide can be stable in the lower mantle and there are some Siand P in the Fe-Ni core. Finally, an earth core-mantle model is established, where the Fe-Ni core contains some Si and P; the lower mantle is composed of Mg-rich silicate, SiO_2 andsulphide; the upper mantle, of silicate and oxide.     

A limit on the lepton-family number violating process π → μe

A FNAL E799 Collaboration has carried out a search for the lepton-family number violating decay π⁰ → μ^±e using π⁰'s produced from K_L → π⁰π⁰π⁰ decays in flight. No events were observed. Assuming that lepton-family number violation is charge independent, the 90% confidence level upper limit on

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was determined to be 8.6 × 10⁻⁹.     

The Imaginary Point Spectrum and Hypercyclicity

Let A be a generator of a C₀-semigroup T(·) on a separable Banach space. Under suitable conditions on the imaginary point spectrum of A, we show that T(·) is hypercyclic.     

DC electrical resistivity for CoxNi5/3−xSb1/3Fe1O4 ferrites

The DC electrical resistivity (p) was studied for Co substituted SbNi ferrites as a function of temperature and composition. The experimental results showed that DC resistivity, Curie temperature and activation energies for electrical conduction increase as Co-ion substitution decreases. The DC electrical conductivity increases as temperature increases. The real part of dielectric constant (e') was found to be inversely proportional to the root mean square value of the electrical resistivity.     

Effect of Microalgae Polysaccharides on Biochemical and Metabolomics Pathways Related to Plant Defense in Solanum lycopersicum

Applied Biochemistry and Biotechnology - Microalgae are photosynthetic microorganisms that produce several bioactive molecules that have received considerable attention in scientific and industrial...     

Search for lepton-flavor-violating decays of the neutral kaon

The Fermilab KTeV experiment has searched for lepton-flavor-violating decays of the K(L) meson in three decay modes. We observe no events in the signal region for any of the modes studied, and we set the following upper limits for their branching ratios at the 90% C.L.: BR(K(L) --> pi(0) micro(+/-) e(-/+)) <7.6 x 10(-11); BR(K(L) --> pi(0)pi(0) micro(+/-) e(-/+)) <1.7 x 10(-10); BR(pi(0) --> micro(+/-) e(-/+)) <3.6 x 10(-10). This result represents a factor of 82 improvement in the branching ratio limit for K(L) --> pi(0) micro(+/-) e(-/+) and is the first reported limit for K(L) --> pi(0)pi(0) micro(+/-) e(-/+).     

Synthetic and mechanistic aspects of a new method for ruthenium-metalation of porphyrins and Schiff-bases

A new method is presented for metalation of a wide range of free-base, neutral, cationic, and anionic porphyrins in refluxing dimethylformamide (DMF) using an easily prepared [Ru(DMF) 6](OTf) 3 complex, and comparisons are made with the more familiar metalation procedure using Ru 3(CO) 12. Both procedures generate Ru (II)(porp)(CO)L complexes (L = solvent); use of the Ru (III)-triflate precursor gives yields comparable to, or greater than, those obtained with the carbonyl, and generates no Ru-chlorin impurities. Mechanistic studies on the meso-tetraphenylporphyrin system reveal that the DMF furnishes the CO, which in the presence of essential water reduces the metal, and metalation likely occurs via a Ru (II)-CO species. Corresponding metalation of tetradentate Schiff-bases gives trans-[Ru (III)(Schiff- base)(DMF) 2]OTf complexes in yields of approximately 50%, a limitation being the accompanying hydrolysis of the Schiff-base through the presence of trace water.     

Influence of terminal substituent on non-linear S-shaped oligomers consisting of azobenzene moieties at the peripheral arm: Synthesis,characterisation and phase transition behaviour

A series of symmetrical S-shaped mesogens based on 4,4′-bis-(6-bromohexyloxy)biphenyl as a central unit containing two 2-{6-[4-(4-substitutedphenylazo)phenoxy]hexyloxy}phenol as side-chain groups has been successfully synthesised. The terminal substituent was varied from halogen (X = F, Cl, Br and I) to non-halogen (X = C₂H₅ and OC₂H₅). The oligomers with C₂H₅ and OC₂H₅ substituents exhibit predominantly the monotropic nematic (N) phase. The OC₂H₅-containing derivatives possess long-range stability of N phase than its C₂H₅-containing analogue in which it has small range of N phase stability. As for halogen-containing analogues, oligomer with F exhibits monotropic N phase whilst oligomers with Cl and Br exhibit monotropic N and smectic A (SmA) phases. In addition, homologue with Br shows additional phase which is smectic B (SmB) phase upon further cooling. However, the oligomers in which F, Cl and Br were substituted by I exhibits purely monotropic SmA and SmB phases. X-ray diffraction measurements reveal that the smectic phase is inclined to the monolayer structure.     

Transport of Carbamazepine,Ciprofloxacin and Sulfamethoxazole in Activated Carbon: Solubility and Relationships between Structure and Diffusional Parameters

The transport of carbamazepine, ciprofloxacin and sulfamethoxazole in the different pores of activated carbon in an aqueous solution is a dynamic process that is entirely dependent on the intrinsic parameters of these molecules and of the adsorbent. The macroscopic processes that take place are analyzed by interfacial diffusion and reaction models. Modeling of the experimental kinetic curves obtained following batch treatment of each solute at 2 µg/L in tap water showed (i) that the transport and sorption rates were controlled by external diffusion and intraparticle diffusion and (ii) that the effective diffusion coefficient for each solute, with the surface and pore diffusion coefficients, were linked by a linear relationship. A statistical analysis of the experimental data established correlations between the diffusional parameters and some geometrical parameters of these three molecules. Given the major discontinuities observed in the adsorption kinetics, the modeling of the experimental data required the use of traditional kinetic models, as well as a new kinetic model composed of the pseudo first or second order model and a sigmoidal expression. The predictions of this model were excellent. The solubility of each molecule below 60 °C was formulated by an empirical expression.     

Pulsed KrF excimer laser induced degradation of cellulose based insulating paper

We report on the accelerated ageing of cellulose based insulating paper by means of pulsed UV laser irradiation (λ = 248 nm) under various experimental conditions including paper composition, background gas (He, N₂ and air) and moisture content of the paper. The temperature reached by the paper samples during their laser irradiation was monitored by means of real-time IR imaging. It is shown that the equilibrium temperature (T _eq) reached by the paper increases from ~30 to ~270 °C when the laser energy density was raised from 15 to 550 mJ cm⁻². The laser irradiated samples were systematically characterized by means of scanning electron microscopy (SEM) observations and degree of polymerization (DP_v) measurements. Interestingly, it is found that, for a given moisture content, the degradation level of the cellulose is mainly triggered by the T _eq value reached during the laser irradiation. Moreover, their moisture content was found to influence significantly the number of laser produced bond scissions (it doubles when the moisture content is increased from 0.5 to 6%); the paper degradation is apparently not affected by the presence of oxygen as the background gas. These results suggest that the laser induced cellulose degradation occurs through a direct photolysis (i.e. direct breakage of C–C, C–O and C–H bonds), leading to radicals formation, which, in turn, are believed to induce the acid hydrolysis degradation mechanism, the latter being moisture dependent. The activation energy (E _a) of each gaseous species collected after the laser degradation was estimated. Their E _a values were found to be in good agreement with the one associated to the laser depolymerisation of cellulose (i.e. ~56 kJ mol⁻¹), suggesting thereby a direct correlation between the cellulose degradation and the formation of the detected gaseous species. Finally, the pulsed laser irradiation can be seen as an attractive tool to identify primarily generated molecules, on a very short time scale, that can be used as relevant chemical markers for the monitoring of the ageing of transformers materials with cellulose.