Kinetics of Oxidation of L‐Cysteine by trans‐ and cis‐CoIII and FeIII Complexes based on α‐ and γ‐Diimine Schiff Base Ligands

Kinetics of oxidation of L ‐cysteine by Co^III and Fe^III complexes based on α‐ and γ‐diimine Schiff base ligands were studied in aqueous solution. Pairs of trans and cis isomers of the metal complexes were used in the studies. Kinetic measurements were performed at 25 °C and constant pH and ionic strength under pseudo‐first order condition, in which the concentration of cysteine was around two orders of magnitude greater than that of the metal complex. The observed rate constant was obtained by following the change in absorbance of the reaction mixture with time at a predetermined wavelength. The overall rate constant and order of the reaction with respect to cysteine and metal complex were determined. For both metal ions studied, the oxidation rate constant for the trans isomer was higher than that for the cis isomer. This was attributed to the contribution of the steric factor and the trans effect. The effects of substituents and the nature of the metal ion on the reaction rate are discussed.     

Intercalation of water and guest molecules within Ca<Superscript>2+</Superscript>–Montmorillonite

The high potential for intercalations by water and various guest molecules is induced by the exchangeable cation inside Ca²⁺–Montmorillonite gallery. XRD peak for Mon at 2θ = 6.04° (d ₀₀₁ = 1.462 nm) shows the structural effect on the clay gallery influenced by the intercalated water layers. Further increases in the gallery height are observed with the intercalation of octadecyl ammonium cations in OMON (d ₀₀₁ = 1.840 nm) and ENR-50 matrix chains in CENR-50 (d ₀₀₁ = 1.954 nm). DSC studies on the other hand reveal the thermal behaviors of intercalated molecules that are linked to the exchangeable cations. The endothermic of Ca²⁺–Montmorillonite (H _Mon = 356.3 J/g) in low temperature range (30–100 °C) indicates the removal of free water and hydrogen bonded water molecules, while the endothermic around 150 °C is related to the induced skeletal layer of water within Ca²⁺–Montmorillonite. The OMON endothermic (H _OMON = 47.0 J/g, T _m = 36.94 °C) tells that cation exchange had modified the water structures and content inside the renewed clay. The intercalation of ENR-50 chains into OMON gallery reveals two endothermic with the T _m1 and T _m2 are at 86.24 and 113.80 °C, respectively. These T _ms confirm that the alkyl chain segment on octadecyl ammonium cation occupy the OMON interlayer space.     

Determination of the health hazards due to background radiation sources in the city of Adapazari, Northwestern Turkey

Human body is exposed to ionising radiations both internally and externally by mainly high-energy cosmic ray particles incident on the earth's atmosphere and radioactive nuclides that originated in the earth's crust. The main objective of this study is to assess the health hazards due to environmental radiation sources in the city of Adapazari, one of the most important industrial cities of the country, Northwestern Turkey. For this purpose, natural radiation sources, external terrestrial radiations, cosmic radiations, and inhalation exposures have been investigated. The annual average external terrestrial radiation doses were determined as 0.08 and 0.35 mSv at outdoor and indoor atmospheres, respectively. The annual average cosmic radiation doses were found to be 0.08 and 0.05 mSv for directly ionising photon components and neutron components, respectively. The annual average inhalation exposure doses due to radon and thoron were obtained as 1.42 and 0.19 mSv, respectively, in the region. The annual average effective dose due to natural radiation sources was determined as a total of 2.35 mSv with the predetermined ingestion radiation dose. The lifetime cancer risk due to the background ionising radiations has been determined as 0.9×10(-2) for the residents of the Adapazari city, with the average lifespan of 70 years. The results of the effective doses due to background radiation sources in the region and the worldwide averages were discussed.     

Search for a standard model Higgs boson in the H→ZZ→ℓ(+)ℓ(-)νν decay channel with the ATLAS detector

A search for a heavy standard model Higgs boson decaying via H→ZZ→→?(+)?(-)νν, where ?=e, μ, is presented. It is based on proton-proton collision data at √s=7 TeV, collected by the ATLAS experiment at the LHC in the first half of 2011 and corresponding to an integrated luminosity of 1.04 fb(-1). The data are compared to the expected standard model backgrounds. The data and the background expectations are found to be in agreement and upper limits are placed on the Higgs boson production cross section over the entire mass window considered; in particular, the production of a standard model Higgs boson is excluded in the region 340相似文献   

CO adsorption on MgO, CaO and SrO crystals periodic Hartree-Fock calculations

The adsorption of carbon monoxide at the defect-free (1 0 0), (1 1 0) and (2 1 0) five-atomic layer slab of the three oxides: MgO, CaO, and SrO has been investigated using the periodic Hartree-Fock level of ab initio theory, together with the 1 × 1 supercell model. All the calculated CO/oxide interaction energies exhibit exothermic character. The HF interaction energies increase monotonically in the order MgO < CaO < SrO. The surface morphology of adsorbate/substrate interaction is confirmed by considering relaxation energies, Mulliken population analysis, charge density contours, and electrostatic potential maps.     

Landau damping of ion-acoustic waves with simultaneous effects of non-extensivity and non-thermality in the presence of hybrid Cairns-Tsallis distributed electrons

The dispersion properties and Landau damping rate of ion-acoustic waves (IAWs) with the hybrid Cairns-Tsallis distributed (CTD) electrons and Maxwellian ions are investigated using the plasma kinetic model based on Vlasov-Poisson's equations. For both super-extensive (q < 1) and sub-extensive (q > 1) plasmas, the dielectric response function, real frequency, and Landau damping rate of IAWs are derived. By taking the effect of θ_{i, e} (ion-to-electron temperature ratio) into account, it is found that with the increase of ion temperature, the real frequency and wave dispersion effects increase as well (for both super-extensive and sub-extensive cases). Exploring the properties of the Landau damping rate of IAWs with the simultaneous presence of non-thermal parameter α and non-extensive parameter q, a comparison of numerical and analytical results is presented. It is found that in different ranges of θ_{e, i} (electron-to-ion temperature ratio), on decreasing the values of the non-extensive parameter and increasing values of the non-thermal parameter, the weak damping rate is observed (vice versa) in super-extensive or super-thermal plasma, although the trend of the damping rate in sub-thermal plasma is similar (as in the case of super-thermal plasma) but is less weak. It is further revealed that the damping rate of IAWs in thermal plasmas (Maxwellian) is stronger than the damping rate of IAWs in the case of non-thermal plasmas (CTD). The current study is applicable to provide deep insight and further allow the exploration of electrostatic plasma modes in different space and laboratory plasma environments where the hybrid CTD plasma exists.     

Complexes of gold(I), silver(I), and copper(I) with pentaaryl[60]fullerides

Gold(I), silver(I), and copper(I) phosphine complexes of 6,9,12,15,18-pentaaryl[60]fullerides 1a and 1b, namely, [(4-MeC(6)H(4))(5)C(60)]Au(PPh(3)) (2a), [(4-t-BuC(6)H(4))(5)C(60)]Au(PPh(3)) (2b), [(4-MeC(6)H(4))(5)C(60)]Ag(PCy(3)) (3a), [(4-t-BuC(6)H(4))(5)C(60)]Ag(PPh(3)) (3b), [(4-t-BuC(6)H(4))(5)C(60)]Ag(PCy(3)) (3c), [(4-MeC(6)H(4))(5)C(60)]Cu(PPh(3)) (4a), and [(4-t-BuC(6)H(4))(5)C(60)]Cu(PPh(3)) (4b), have been synthesized and characterized spectroscopically. All complexes except for 3c were also characterized by single-crystal X-ray diffraction. Several coordination modes between the cyclopentadienyl ring embedded in the fullerene and the metal centers are observed, ranging from η(1) with a slight distortion toward η(3) in the case of gold(I), to η(2)/η(3) for silver(I), and η(5) for copper(I). Silver complexes 3a and 3b are rare examples of crystallographically characterized Ag(I) cyclopentadienyls whose preparation was possible thanks to the steric shielding provided by fullerides 1a and 1b, which stabilizes these complexes. Silver complexes 3a and 3b both display unexpected coordination of the cyclopentadienyl portion of the fulleride anion with Ag(I). DFT calculations on the model systems (H(5)C(60))M(PH(3)) and CpMPH(3) (M = Au, Ag, or Cu) were carried out to probe the geometries and electronic structures of these metal complexes.     

Synthesis, ion-exchange properties and analytical applications of stannic selenoarsenate: Comparison with other heteropolyacid salts

Summary Stannic selenoarsenate samples have been prepared by adding a mixture which is 0.05 M in sodium arsenate and 0.05 M in sodium selenite to a 0.05 M solution of stannic chloride in different volume ratios at pH 1. Its ion-exchange properties, pH titration curves and X-ray pattern were studied. Adsorption behaviour of 24 metal ions in different solvent systems has been examined. The analytical importance of this material has been demonstrated by achieving the following binary and ternary separations: Hg²⁺-Cd²⁺, Co²⁺-Fe³⁺, Cu²⁺-Fe³⁺, Hg²⁺-Zn²⁺-Al³⁺, Hg²⁺-Cu²⁺-Al³⁺, Hg²⁺-Ni²⁺-Al³⁺, Hg²⁺-Zn²⁺-Fe³⁺ and Hg²⁺-Ni²⁺-Fe³⁺. A comparison of the ion-exchange properties of this material has also been made with some other tin(IV) based ion-exchangers.

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Synthese, Ionenaustauscher-Eigenschaften und analytische Anwendungen von Zinn-Selenoarsenat: Vergleich mit anderen Heteropolysalzen

Zusammenfassung Zinn-Selenoarsenat wurde durch Mischen von 0,05 M Natriumarsenat-, 0,05 M Natriumselenitund 0,05 M Zinn(IV)-Chlorid-Lösungen bei pH 1 in verschiedenen Verhältnissen hergestellt. Die Ionenaustauscher-Eigenschaften, pH-Titrationskurven sowie Röntgendiagramme wurden untersucht und das Adsorptionsverhalten von 24 Metallionen in verschiedenen Lösungsmittelsystemen geprüft. Die analytische Verwertbarkeit wurde an Hand der folgenden Trennungsmöglichkeiten gezeigt: Hg²⁺-Cd²⁺, Co²⁺-Fe³⁺, Cu²⁺-Fe³⁺, Hg²⁺-Zn²⁺-Al³⁺, Hg²⁺-Cu²⁺-Al³⁺, Hg²⁺-Ni²⁺-Al³⁺, Hg²⁺-Zn²⁺-Fe³⁺, Hg²⁺-Ni²⁺-Fe³⁺. Vergleiche mit anderen Ionenaustauschern auf Zinn(IV)-Basis werden ebenfalls beschrieben.