Electron-rich heteroaromatic conjugated bipyridine based ruthenium sensitizer for efficient dye-sensitized solar cells

A novel heteroleptic ruthenium complex carrying a heteroaromatic-4,4'-pi-conjugated 2,2'-bipyridine [Ru(II)LL'(NCS)(2)] (L = 4,4'-bis[(E)-2-(3,4-ethylenedioxythien-2-yl)vinyl]-2,2'-bipyridine, L' = 4,4'-(dicarboxylic acid)-2,2'-bipyridine) was synthesized and used in dye-sensitized solar cells, yielding photovoltaic efficiencies of 9.1% under standard global AM 1.5 sunlight.     

Molecular basis of drug resistance in aurora kinases

Aurora kinases have emerged as potential targets in cancer therapy, and several drugs are currently undergoing preclinical and clinical validation. Whether clinical resistance to these drugs can arise is unclear. We exploited a hypermutagenic cancer cell line to select mutations conferring resistance to a well-studied Aurora inhibitor, ZM447439. All resistant clones contained dominant point mutations in Aurora B. Three mutations map to residues in the ATP-binding pocket that are distinct from the "gatekeeper" residue. The mutants retain wild-type catalytic activity and were resistant to all of the Aurora inhibitors tested. Our studies predict that drug-resistant Aurora B mutants are likely to arise during clinical treatment. Furthermore, because the plasticity of the ATP-binding pocket renders Aurora B insensitive to multiple inhibitors, our observations indicate that the drug-resistant Aurora B mutants should be exploited as novel drug targets.     

CuO based catalysts on modified acidic silica supports tested in the de-NOx reduction

A series of dispersed CuO catalysts supported on modified silica supports with Al2O3 (SA), TiO2 (ST), and ZrO2 (SZ) were prepared optimising the adsorption method of copper deposition assisted by ultrasound treatment, already reported in a previous paper (S. Bennici, A. Gervasini, V. Ragaini, Ultrason. Sonochem. 10 (2003) 61). The obtained catalysts were characterized in their bulk (atomic absorption, X-ray diffraction, temperature programmed reduction) and surface (N2 adsorption, X-ray photoelectron spectroscopy, scanning electron microscopy) properties. The morphology of the finished materials was not deeply modified compared with that of the relevant supports. The employed complemented techniques evidenced a well dispersed CuO phase with a copper-support interaction on the most acidic supports (SA and SZ). The catalyst performances were studied in the reaction of selective catalytic reduction of NOx with ethene in oxidizing atmosphere in a flow apparatus under variable times (0.360-0.072 s) and temperatures (200-450 degrees C). The catalysts prepared on the most acidic supports (SA and SZ) were the most active and selective towards N2 formation. They showed a particular interesting activity in the reaction of NO2 reduction besides that of NO reduction.     

A convenient route to dinuclear chloro-bridged platinum(II) derivatives via nitrile complexes

The syntheses of the complexes [PtCl(2)(NCR)L] [R = Me, Et; L = PPh(3); R = Et, L = Py, CO] and [PtCl{(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}(NCEt)] are described starting from the easily available [PtCl(2)(NCR)(2)]. The stability of the products under different experimental conditions is discussed as well as their use as precursors to dinuclear complexes [Pt(μ-Cl)ClL](2). The crystal and molecular structures of cis-[PtCl(2)(NCEt)(PPh(3))], [SP-4-2]-[PtCl{(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}(NCEt)] and trans-[Pt(μ-Cl){(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}](2) are reported.     

Comparative rheological study of ionic semi-IPN composite hydrogels based on polyacrylamide and dextran sulphate and of polyacrylamide hydrogels

Ionic semi-interpenetrating polymer networks composite hydrogels were synthesized by free-radical polymerization using dextran sulphate (DxS), acrylamide as monomer and N,N′-methylene(bis)acrylamide as cross-linking agent. The viscoelastic properties of these composite hydrogels were investigated by oscillatory shear measurements under small deformation conditions comparative with those of polyacrylamide gels. Changes of the rheological properties of composite hydrogels have been studied in terms of polymerization temperature, cross-linker ratio, initial monomer concentration and molar mass of DxS. The results showed that the stability of the composite hydrogels obtained at room temperature (22?°C) was relatively low because the storage modulus (G′) was only eight times higher than the loss modulus (G″), while for those obtained by cryopolymerization (?18?°C), the stability was improved, the G′ values being about 30 times higher than those of G″. This behaviour indicated that, by conducting the synthesis of hydrogels below the freezing point of the reaction solutions, an enhancement of the hydrogels elasticity was achieved. The network parameters, i.e. the average molecular weight between two cross-links and the cross-link density of the composite hydrogels prepared at ?18?°C, were estimated from rheological data.     

Development of a sensitive method for simultaneous determination of fluticasone propionate and salmeterol in plasma samples by liquid chromatography-tandem mass spectrometry

A new method for the fast simultaneous quantification of fluticasone propionate and salmeterol from plasma samples by liquid chromatography–tandem mass spectrometry, with adequate sensitivity for pharmacokinetic applications, was developed and validated. The chromatographic separation and mass‐spectrometric parameters were optimized for the retention and detection of the two compounds, despite quite different structures and properties. Two columns connected in series were used, cation‐exchange (Zorbax 300‐SCX, 5 cm × 2.1 mm, 5 µm) and octadecyl (Discovery HSC₁₈, 10 cm × 2.1 mm, 5 µm). The mass‐spectrometric interface was operated in negative electrospray ionization mode; high sensitivity and lesser matrix effects were obtained, permitting smaller consumption of plasma. The sample preparation was based on supported liquid–liquid extraction in 96‐well format plates that provided clean samples with a simplified procedure that was suitable for automation. The method was validated according to regulatory guidelines, by assessing lower limits of quantification, selectivity, linearity, accuracy, precision, extraction recoveries and matrix effects. A comparison with two other methods for the separate determination of fluticasone propionate and salmeterol in plasma samples, previously developed by our group, is presented. The statistical evaluation of the results obtained with the three methods on a set of unknown samples from treated patients demonstrated good correlation (R² 0.987 for fluticasone propionate and 0.967 for salmeterol). Copyright © 2011 John Wiley & Sons, Ltd.     

Downstream Processing of Therapeutic Peptides by Means of Preparative Liquid Chromatography

The market of biomolecules with therapeutic scopes, including peptides, is continuously expanding. The interest towards this class of pharmaceuticals is stimulated by the broad range of bioactivities that peptides can trigger in the human body. The main production methods to obtain peptides are enzymatic hydrolysis, microbial fermentation, recombinant approach and, especially, chemical synthesis. None of these methods, however, produce exclusively the target product. Other species represent impurities that, for safety and pharmaceutical quality reasons, must be removed. The remarkable production volumes of peptide mixtures have generated a strong interest towards the purification procedures, particularly due to their relevant impact on the manufacturing costs. The purification method of choice is mainly preparative liquid chromatography, because of its flexibility, which allows one to choose case-by-case the experimental conditions that most suitably fit that particular purification problem. Different modes of chromatography that can cover almost every separation case are reviewed in this article. Additionally, an outlook to a very recent continuous chromatographic process (namely Multicolumn Countercurrent Solvent Gradient Purification, MCSGP) and future perspectives regarding purification strategies will be considered at the end of this review.     

Determination of thermophysical properties of high temperature alloy IN713LC by thermal analysis

The presented paper deals with the study of thermophysical properties of cast and complex alloyed nickel based on superalloy Inconel 713LC (IN713LC). In this work, the technique of Differential Thermal Analysis was selected for determination of the phase transformation temperatures and for the study of the effect of varying heating/cooling rate at these temperatures. The samples taken from as-received state of superalloy were analysed at heating and cooling rates of 1, 5, 10, 20 and 50?°C?min^?1 with the help of the experimental system Setaram SETSYS 18_TM. Moreover, the transformation temperatures at zero heating/cooling rate were calculated. The recommended values for IN713LC after correcting to a zero heating rate, are 1,205?°C (T _?á?,solvus), 1,250?°C (solidus) and 1,349?°C (liquidus). Influence of heating/cooling rate on shift of almost all temperatures of phase transformations was established from the DTA curves. Undercooling was observed at the cooling process. The samples before and after DTA analysis were also subjected to the phase analysis by scanning electron microscopy using the microscope JEOL JSM-6490LV equipped with an energy dispersive analyser EDAX (EDS INCA x-act). Documentation of the microstructure was made in the mode of secondary (SEI) and backscattered (BEI) electron imaging. On the basis of DTA analysis and phase analysis it may be stated that development of phase transformations of the alloy IN713LC will probably correspond to the following scheme: melting?????? phase; melting???????+?MC; melting????eutectics ??/?á?; melting???????+?minority phases (e.g. borides); and matrix ???????á?.     

Evaluation and differentiation of the Betulaceae birch bark species and their bioactive triterpene content using analytical FT-vibrational spectroscopy and GC-MS

A new simple, rapid and sensitive reversed-phase liquid chromatographic method was developed and validated for the simultaneous determination of sulpiride (SUL) and mebeverine Hydrochloride (MEB) in the presence of their impurities and degradation products. The separation of these compounds was achieved within 6 min on a 250 mm, 4.6 mm i.d., 5 m particle size Waters^?-C18 column using isocractic mobile phase containing a mixture of acetonitrile and 0.01 M dihydrogenphosphate buffer (45:55) at pH = 4.0. The analysis was performed at a flow rate of 1.0 mL/min with fluorescence-detection at excitation 300 nm and emission at 365 nm. The concentration-response relationship was linear over a concentration range of 10- 100 ng/mL for both MEB and SUL with a limit of detection 0.73 ng/mL and 0.85 ng/mL for MEB and SUL respectively. The proposed method was successfully applied for the analysis of both MEB and SUL in bulk with average recoveries of 100.22 ± 0.757% and 99.96 ± 0.625% respectively, and in commercial tablets with average recoveries of 100.04 ± 0.93% and 100.03 ± 0.376% for MEB and SUL respectively. The proposed method was successfully applied to the determination of MEB metabolite (veratic acid) in real plasma simultaneously with SUL. The mean% recoveries (n = 3) for both MEB metabolite (veratic acid) and SUL were 100.36 ± 2.92 and 99.06 ± 2.11 for spiked human plasma respectively. For real human plasma, the mean% recoveries (n = 3) were and respectively.     

Novel coordination frameworks incorporating the 4,4'-bipyrazolyl ditopic ligand

The reaction of the rigid spacer 4,4'-bipyrazole (H(2)BPZ) with late transition metals, either following conventional routes or under solvothermal conditions, afforded the coordination polymers [M(BPZ)]·Solv (M = Zn, 1; Co, 2; Cd, 3; Hg, 4; Cu, 5; Ni, 6; Pd, 7; Solv = DMF, 3; MeCN, 5 and 6; H(2)O, 7), [Cu(H(2)BPZ)(2)(NO(3))(2)] (8), and [Cd(H(2)BPZ)(CH(3)COO)(2)] (9). State-of-the-art laboratory powder diffraction methods allowed to disclose the isomorphous character of 1 and 2, as well as of 5 and 6, which feature 3D porous networks containing 1D channels of square and rhombic shape, respectively. 3, crystallizing in the relatively rare P6(1)22 space group, consists of homochiral helices of octahedral Cd(II) ions, packing in bundles mutually linked by "radial", nonplanar BPZ ligands. Finally, the dense species 8 and 9 contain parallel 2D layers of square and rectangular meshes, respectively. Thermogravimetric analyses witnessed the relevant thermal robustness of all the [M(BPZ)] materials [except the mercury(II) derivative], which are stable in air at least up to 300 °C, with the zinc(II) derivative decomposing only around 450 °C. Variable-temperature powder diffraction experiments highlighted the permanent porosity of 1-3, 5, and 6, retained along consecutive temperature cycles in all cases but 3. When probed with N(2) at 77 K, 1-3 and 5-7 showed Brunauer-Emmett-Teller and Langmuir specific surface areas in the ranges 314(2)-993(11) and 509(16)-1105(1) m(2)/g, respectively.