Multifunctional graphene/platinum/Nafion hybrids via ice templating

We report the synthesis of multifunctional hybrids in both films and bulk form, combining electrical and ionic conductivity with porosity and catalytic activity. The hybrids are synthesized by a two-step process: (a) ice templation of an aqueous suspension comprised of Nafion, graphite oxide, and chloroplatinic acid to form a microcellular porous network and (b) mild reduction in hydrazine or monosodium citrate which leads to graphene-supported Pt nanoparticles on a Nafion scaffold.     

Brittle fracture of entangled polymers

A stochastic model is presented to calculate the number of chain segments entangled about a unit plane when the segment length is a stochastic variable. This crossing density to which the brittle fracture energy and the critical strength of entangled polymers scale is a function of the number of moles of entanglement network strands per unit volume and the mesh size of the entanglement network. Experimental results of the molecular weight dependence of the fracture energy and strength validate the theoretical predictions.     

New gradient high-performance liquid chromatography method for determination of donepezil hydrochloride assay and impurities content in oral pharmaceutical formulation

A new gradient HPLC method has been developed and validated for the determination of both assay and related substances of donepezil hydrochloride in oral pharmaceutical formulation. Different kinds of columns and gradient elution programs were tested in order to achieve satisfactory separation between the active substance, four impurities and an interfering excipient used in the formulation. The best results were obtained using an Uptisphere ODB C-18 column 250 mm x 4.6 mm, 5 microm, UV detection at 270 nm and a gradient elution of phosphate buffer (0.005 M, pH 3.67) and methanol as the mobile phase. The method was validated with respect to linearity, precision, accuracy, specificity and robustness. It was also found to be stability indicating, and therefore suitable for the routine analysis of donepezil hydrochloride and related substances in the pharmaceutical formulation.     

Studies on the selenoproteome in the cultured cells of lung and trachea by gel electrophoretic techniques

In the present studies radiotracer techniques have been combined with biochemical separation procedures to investigate the selenium-containing proteins in the culture cells of the lung, trachea and their subcellular fractions. Subcellular separation of the lung and trachea tissues has been achieved by differential ultracentrifugation. The selenium-containing proteins in these compartments have been investigated by labeling of lung and trachea cultured cells in vitro with Se-75, gel electrophoretic separation of the proteins and autoradiographic detection of the tracer. The protein separation by gel electrophoresis using mono-dimensional (1D)- and two-dimensional (2D)-SDS-PAGE has been successfully applied for the selenium research. It has resulted in the detection of a large number of selenium-containing proteins. Two-dimensional gel electrophoresis (2-DE) was also helpful in the identification of the proteins of interest according to their molecular mass and isoelectric point. In this way more than 30 selenium-containing proteins could be distinguished in the lung and trachea samples. Some of them such as Gpx1, Trx1, SelP, SelT and Sel15 could be identified by means of immunoassays, their molecular weight and pI values and localized in the cellular compartments.     

Synthesis of 2D Germanane (GeH): a New,Fast, and Facile Approach

Germanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a β‐CaGe₂ layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (E_g) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells.     

Palladium(ii)-catalysed tandem cyclisation of electron-deficient aromatic enynes

A novel palladium(ii) catalysed tandem cyclisation of substituted 2-alkenylphenyl alkynones gives substituted 2-vinyl indenones and 6,5,6-fused tricyclic lactone skeletons (pyrones), in one-pot. Wagner-Meerwein-like rearrangements were observed which occur preferentially to conventional chloride-mediated chloropalladations of enynes.     

Ground- and triplet excited-state properties correlation: a computational CASSCF/CASPT2 approach based on the photodissociation of allylsilanes

Excited-state properties, although extremely useful, are hardly accessible. One indirect way would be to derive them from relationships to ground-state properties which are usually more readily available. Herewith, we present quantitative correlations between triplet excited-state (T?) properties (bond dissociation energy, D?(T?), homolytic activation energy, E(a)(T?), and rate constant, k(r)) and the ground-state bond dissociation energy (D?), taking as an example the photodissociation of the C-Si bond of simple substituted allylsilanes CH?=CHC(R1R2)-SiH? (R1 and R2 = H, Me, and Et). By applying the complete-active-space self-consistent field CASSCF(6,6) and CASPT2(6,6) quantum chemical methodologies, we have found that the consecutive introduction of Me/Et groups has little effect on the geometry and energy of the T? state; however, it reduces the magnitudes of D?, D?(T?) and E(a)(T?). Moreover, these energetic parameters have been plotted giving good linear correlations: D?(T?) = α? + β? · D?, E(a)(T?) = α? + β? · D?(T?), and E(a)(T?) = α? + β? · D? (α and β being constants), while k(r) correlates very well to E(a)(T?). The key factor behind these useful correlations is the validity of the Evans-Polanyi-Semenov relation (second equation) and its extended form (third equation) applied for excited systems. Additionally, the unexpectedly high values obtained for E(a)(T?) demonstrate a new application of the principle of nonperfect synchronization (PNS) in excited-state chemistry issues.