Study of pure and semileptonic decays of D_s meson within R-parity violating supersymmetric model

We present the comaprative study of semileptonic and leptonic decays of D_s,D^± and D⁰ meson ( D→ M l_α ⁺l_β^-,D→l_α⁺l_β^-,D→l_α⁺v_α ;α,β=e,μ) within the framework of R-parity violating the (R_p) Minimal Supersymmetric Standard Model (MSSM). The comparison shows that combination and product couplings, (λ_βiαλ''_ijq^* or λ''_βqk^*λ''_{α jk}^*) contribution to the branching fractions of the said processes (under consideration) is consistent with or comparable to the experimental measurements in most of the cases. However, some cases exist where these contributions are highly suppressed. We identify such cases in our analysis and single out the important ones suitable for exploring in the future and current experiments.     

Kaluza–Klein cosmology with modified holographic dark energy

We investigate the compact Kaluza–Klein cosmology in which modified holographic dark energy is interacting with dark matter. Using this scenario, we evaluate equation of state parameter as well as equation of evolution of the modified holographic dark energy. Further, it is shown that the generalized second law of thermodynamics holds without any constraint.     

K6[Fe8.27(HPO3)12]: a new mixed‐valence iron phosphite

The title compound, hexapotassium octairon(II,III) dodecaphosphonate, exhibiting a two‐dimensional structure, is a new mixed alkali/3d metal phosphite. It crystallizes in the space group Rm, with two crystallographically independent Fe atoms occupying sites of m (Fe1) and 3m (Fe2) symmetry. The Fe2 site is fully occupied, whereas the Fe1 site presents an occupancy factor of 0.757 (3). The three independent O atoms, one of which is disordered, are situated on a mirror and all other atoms are located on special positions with 3m symmetry. Layers of formula [Fe₃(HPO₃)₄]²⁻ are observed in the structure, formed by linear Fe₃O₁₂ trimer units, which contain face‐sharing FeO₆ octahedra interconnected by (HPO₃)²⁻ phosphite oxoanions. The partial occupancy of the Fe1 site might be described by the formation of two [Fe(HPO₃)₂]⁻ layers derived from the [Fe₃(HPO₃)₄]²⁻ layer when the Fe1 atom is absent. Fe²⁺ is localized at the Fe1 and Fe2 sites of the [Fe₃(HPO₃)₄]²⁻ sheets, whereas Fe³⁺ is found at the Fe2 sites of the [Fe(HPO₃)₂]⁻ sheets, according to bond‐valence calculations. The K⁺ cations are located in the interlayer spaces, between the [Fe₃(HPO₃)₄]²⁻ layers, and between the [Fe₃(HPO₃)₄]²⁻ and [Fe(HPO₃)₂]⁻ layers.     

Ammoxidation of ethylene to acetonitrile over chromium or cobalt alumina catalysts prepared by sol–gel method

A series of Cr/Al₂O₃ and Co/Al₂O₃ catalysts were tested in the selective ammoxidation of ethylene to acetonitrile. Catalysts were prepared either by sol–gel method or by impregnation with chromium or cobalt acetylacetonate salts. Physicochemical properties of catalysts were accomplished by several techniques such as chemical analysis, physisorption of N₂, X-ray diffraction (XRD), ²⁷Al MAS NMR, UV–Visible diffuse reflectance (DRS) and Raman spectroscopy and temperature programmed reduction of H₂ (H₂–TPR). Textural analysis reveals that mesoporous materials with pronounced surface areas were obtained using sol–gel procedure while impregnation of the support produces a moderate decrease of its surface area and pore volume. XRD analysis confirms the presence of highly dispersed metal species which reside essentially on the surface and measure less than 4 nm. Furthermore, ²⁷Al MAS NMR shows that for xerogels, part of metal species occupies sites on/in A1₂O₃ in close vicinity of octahedral ²⁷Al. This, apparently, is not the case for aerogels. For Cr/Al₂O₃ catalysts, isolated Cr⁶⁺, mono and polychromate species were identified using DRS, Raman Spectroscopy and H₂–TPR which seem to play a key role in the ammoxidation of ethylene. Furthermore, for cobalt doped catalysts, CoAl₂O₄ was identified as active phase on the basis of DRS and H₂–TPR results. From the supercritical drying, it results generally better catalysts than catalysts calcined by ordinary procedure which leads to inactive agglomerated Co₃O₄ and CoO–Al₂O₃ phase.     

Diffusion studies in confined nematic liquid crystals by MAS PFG NMR

Pulsed field gradient (PFG) NMR and magic-angle spinning (MAS) NMR have been combined in order to measure the diffusion coefficients of liquid crystals in confined geometry. Combination of MAS NMR with PFG NMR has a higher spectroscopic resolution in comparison with conventional PFG NMR and improves the application of NMR diffusometry to liquid crystals. It is found that the confinement of the liquid crystal 5CB in porous glasses with mean pore diameters of 30 and 200 nm does not notably change its diffusion behavior in comparison with the bulk state.     

Untersuchungen an Polyhalogeniden. XXIII. Kristallstrukturen der N-Alkylurotropiniumtriiodide UrRI3 mit R = Methyl,Ethyl, n-Propyl und n-Butyl

Studies on Polyhalides. 23. Crystal Structures of N-Alkylurotropinium Triiodides UrRI₃ with R = Methyl, Ethyl, n-Propyl, and n-Butyl The salts UrRI₃ may be prepared by the reaction of N-alkylurotropinium iodides UrRI with iodine I₂ at room temperature from aqueous solution. N-methylurotropinium triiodide C₇H₁₅N₄I₃ crystallizes monoclinically in P2₁/c with a = 1300.8(2) pm, b = 1276.0(3) pm, c = 859.3(2) pm, β = 94.75(2)° and Z = 4. The crystal structure is built up from layers of cations UrMe⁺ and of linear symmetric triiodide ions I₃^? alternating along [100]. N-ethylurotropinium triiodide C₈H₁₇N₄I₃ crystallizes orthorhombically in Pnma with a = 1397.3(5) pm, b = 1221.3(2) pm, c = 886.2(2) pm and Z = 4. The cationic (UrEt⁺) and anionic (I₃^?) layers alternate along [0 10]. N-propylurotropinium triiodide C₉H₁₉N₄I₃ crystallizes monoclinically in P2₁/c with a = 1885.7(5) pm, b = 1657.1(5) pm, c = 1700.5(4) pm, β = 112.39(2)° and Z = 12. The three independent cations and anions are slightly, but differently distorted. N-butylurotropinium triiodide C₁₀H₂₁N₄I₃ crystallizes monoclinically in P2₁/m with a = 991.8(3) pm, b = 757.8(2) pm, c = 1128.2(2) pm, β = 90.73(2)° and Z = 2. The crystal structure is stacked by alternating cationic and anionic layers along [001]. The triiodide ion is asymmetric and linear.     

Nanoreactors based on amphiphilic uracilophanes: self-organization and reactivity study

New amphiphilic pyrimidinic macrocycles (APMs) with two (APM-1) and three (APM-2) decyl tails have been synthesized by quaternization of the bridged N. Complex examination of the APM-based systems with the help of tensiometry, conductometry, dynamic light scattering, and UV and NMR spectroscopy provides evidence for their aggregation. Calculations based on surface tension isotherms and on packing parameter considerations make it possible to assume a lamellar packing of macrocycles when aggregating. Marked differences in the aggregation behavior of APM-1 and APM-2 have been found. The additives of polyethylenimine (PEI) exert little influence on the critical micelle concentration (cmc) of APM-1, while in the APM-2/PEI systems there occurs a pronounced decrease in the cmc and also a ca. 2-fold decrease in the surface area per molecule. The APM-based assemblies are explored as nanoreactors for the hydrolysis of O-alkyl O-p-nitrophenyl (chloromethyl)phosphonates (alkyl = ethyl, hexyl). The kinetic study reveals a minor rate effect of the APM-1-based systems. In the APM-2-based systems an acceleration of the hydrolysis of both phosphonates occurs as compared to the uncatalyzed process. Within the APM-2 --> APM-2/PEI --> APM-2/PEI/La(III) series, due to the cooperative contributions of the supramolecular, polymer, and homogeneous catalysis, an increase in the catalytic effect is observed from 30 times to 3 orders of magnitude as compared to that of the basic hydrolysis of the substrates.     

Chemical composition,antioxidant and antimicrobial activities of the edible medicinal Ononis natrix growing wild in Tunisia

Results showed that leaf methanolic extract of Ononis natrix has important total phenol (51 mg GAE/g DW) and flavonoid (14.76 CE/g DW) contents. The chemical composition of O. natrix leaf revealed the presence of quercitine (24.5%), amentoflavone (14.1%), flavones (11.3%) and kaempferol (10.5%). The leaf extract showed a high total antioxidant activity with 60.94 mg of GAE/g DW, displayed a high 2,2-diphenyl-1-picrylhydrazyl scavenging ability with low IC₅₀ value (29 μg/mL) and a great reducing power (EC₅₀ = 100 μg/mL). O. natrix leaf extract exhibited a significant broad spectrum activity against all tested microorganisms with bacterial inhibition zone sizes ranging from 8.5 to 17 mm in diameter.