Magnetic,Spectral, Thermal,and Electrical Properties of Coordination Polymers Derived from Terpolymers

Coordination polymers of Cu(II), Ni(II), Co(II), zinc(II), chromium(IU), iron(IU), oxovanadium(N), and dioxouranium-(VI) with p-hydroxybenzoic acid (PHB)-thiourea (T)-trioxane (T) (PHBTT) polymer were prepared. The analytical data agree with 1:1 metal-ligand stoichiometry. Magnetic susceptibility, visible and IR spectra, and thermal and electrical conductivities of the chelates have been studied and probable structures assigned to the chelates.     

Spectral Characteristics of Bicalutamide Drug in Different Solvents and β-Cyclodextrin

Absorption and fluorescence spectra of bicalutamide (BCA) in different solvents and aqueous β-cyclodextrin (β-CD) solutions are reported. The solid inclusion complex of BCA with β-CD is prepared and investigated by FT-IR, ¹H NMR, differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). The Stokes shift of BCA is correlated with various solvent polarity scales like E _T(30), BK and f(D,n). β-CD studies show that (i) the absorption and emission maxima of BCA are shifted to red, (ii) the absorbance is slightly decreased whereas emission intensity is increased largely with an increasing β-CD concentration, (iii) BCA forms 1:1 inclusion complex with β-CD and (iv) intramolecular charge transfer (ICT) emission is present in the excited state.     

An improved HPLC method with the aid of a chemometric protocol: simultaneous analysis of amlodipine and atorvastatin in pharmaceutical formulations

Statistical experimental design and Derringer's desirability function were applied to develop an improved RP-HPLC method for the simultaneous analysis of amlodipine and atorvastatin in pharmaceutical formulations. Four independent factors were considered: acetonitrile content in the mobile phase; buffer pH; buffer concentration; and flow rate. The preliminary screening step was carried out, according to a 2(4-1) fractional factorial design, to identify the significant factors affecting the analysis time response. Then central composite design was applied for a response surface study, in order to examine in depth the effects of the most important factors. Subsequently, Derringer's desirability function was employed to simultaneously optimize the six responses: retention factor of first peak; two resolutions; and three retention times, each having a different target. This procedure allowed deduction of two separate optimum conditions, intended for the analysis of quality control and plasma samples, within the experimental domain. The predicted optimum for the quality control samples was: methanol-acetonitrile-15 mM K(2)HPO(4) buffer (pH 5.33) (10:42.08:47.92, v/v/v) as the mobile phase and 1.12 mL/min as the flow rate. The method using this optimized condition showed higher sensitivity and shorter analysis time than the previously published reports. The optimized assay condition was validated according to International Conference on Harmonization guidelines.     

Brain site-specific proteome changes in aging-related dementia

This study is aimed at gaining insights into the brain site-specific proteomic senescence signature while comparing physiologically aged brains with aging-related dementia brains (for example, Alzheimer''s disease (AD)). Our study of proteomic differences within the hippocampus (Hp), parietal cortex (pCx) and cerebellum (Cb) could provide conceptual insights into the molecular mechanisms involved in aging-related neurodegeneration. Using an isobaric tag for relative and absolute quantitation (iTRAQ)-based two-dimensional liquid chromatography coupled with tandem mass spectrometry (2D-LC-MS/MS) brain site-specific proteomic strategy, we identified 950 proteins in the Hp, pCx and Cb of AD brains. Of these proteins, 31 were significantly altered. Most of the differentially regulated proteins are involved in molecular transport, nervous system development, synaptic plasticity and apoptosis. Particularly, proteins such as Gelsolin (GSN), Tenascin-R (TNR) and AHNAK could potentially act as novel biomarkers of aging-related neurodegeneration. Importantly, our Ingenuity Pathway Analysis (IPA)-based network analysis further revealed ubiquitin C (UBC) as a pivotal protein to interact with diverse AD-associated pathophysiological molecular factors and suggests the reduced ubiquitin proteasome degradation system (UPS) as one of the causative factors of AD.     

Synthesis and characterization of Li<Subscript>1-x</Subscript>Tb<Subscript>x</Subscript>NiPO<Subscript>4</Subscript> solid solution as cathode materials for lithium ion battery application

Modified Pechini-type polymerizable precursor method has been used to prepare nanosized Li_1-xTb_xNiPO₄ (x = 0, 0.03, 0.05, and 0.07) solid solutions to obtain homogeneous with controlled stoichiometry and smaller particle size. The reaction temperature was determined by thermogravimetric (TG/DTA) analysis. X-ray diffraction analysis reveals the formation of orthorhombic structure and the calculated crystallite sizes are found to be in the range of 75–89 nm. Morphological, compositional, and vibrational properties were performed by SEM, EDAX, and FTIR, respectively. Conductivity measurements were carried out at room temperature by AC impedance analysis. The Li_0.97Tb_0.03Ni_0.99PO₄ sample shows one order of higher conductivity than pure LiNiPO₄. Higher concentration of terbium samples such as Li_0.95Tb_0.05Ni_0.99PO₄ and Li_0.93Tb_0.07Ni_0.99PO₄ lead to decrease of conductivity. The frequency dependency of dielectric permittivity, dielectric loss, and electric modulus of Li_1-x Tb_xNiPO₄ solid solutions are studied. The frequency-dependent plot of modulus reveals that the conductivity relaxation is of non-Debye type.     

Determination of the antioxidant propyl gallate in meat by using a screen-printed electrode modified with CoSe<Subscript>2</Subscript> nanoparticles and reduced graphene oxide

A voltammetric sensor is described for the quantitation of propyl gallate (PG). A screen-printed carbon electrode (SPCE) was modified with reduced graphene sheets that were decorated with cobalt diselenide nanoparticles (CoSe₂@rGO). The material was hydrothermally prepared and characterized by several spectroscopic techniques. The modified SPCE displays excellent electrocatalytic ability towards PG. Differential pulse voltammetry, with a peak voltage at 0.34 V (vs. Ag/AgCl) has a sensitivity of 12.84 μA·μM^?1·cm^?2 and a detection limit as low as 16 nM. The method is reproducible, selective, and practical. This method was applied to the determination of PG in spiked meat samples, and the result showed an adequate recovery.

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Graphical abstract Schematic of a new method for fast and sensitive electrochemical determination of the food additive propyl gallate in meat

     

Synthesis and Study of Tercopolymers

Tercopolymers have been prepared by condensing a mixture of salicylic acid, thiourea, and any one of such comonomers as o-cresol, p-cresol, o-chlorophenol, and p-chlorophenol with trioxane in the presence of 2 M HCl as catalyst. The tercopolymers were characterized by elemental analyses. Their M[Mbar]_n was determined by nonaqueous conductometric titration both against standard sodium methoxide and tetra-n-butyl ammonium hydroxide and also by the VPO method. Also made were an IR spectral study, a viscometric study in dimethylformamide (DMF), and a thermal study based on TGA. Chelation ion-exchanging properties of selected tercopolymer samples were also studied by employing the batch equilibration method.     

Sensitive LC‐MS/MS‐ESI method for simultaneous determination of montelukast and fexofenadine in human plasma: application to a bioequivalence study

A rapid, simple, sensitive and selective LC‐MS/MS method was developed and validated for simultaneous quantification of montelukast (MT) and fexofenadine (FF) in human plasma (200 μL) using montelukast‐d₆ (MT‐d₆) and fexofenadine‐d₁₀ (FF‐d₁₀), respectively as an internal standard (IS) as per the US Food and Drug Administration guidelines. The chromatographic resolution was achieved on a Chromolith RP_18e column using an isocratic mobile phase consisting of 20 mm ammonium formate–acetonitrile (20:80, v/v) at flow rate of 1.2 mL/min. The LC‐MS/MS was operated under the multiple‐reaction monitoring mode using electrospray ionization. The total run time of analysis was 4 min and elution of MT, FF, MT‐d₆ and FF‐d₁₀ occurred at 2.5, 1.2, 2.4 and 1.2 min, respectively. The standard curve found to be linear in the range 2.00–1000 ng/mL with a coefficient of correlation of ≥0.99 for both the drugs. The intra‐ and inter‐day accuracy and precision values for MT and FF met the acceptance as per FDA guidelines. MT and FF were found to be stable in a battery of stability studies viz., bench‐top, auto‐sampler and repeated freeze‐thaw cycles. The validated assay was applied to an oral bioequivalence study in humans. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis of N‐Protected/Free Indole‐7‐Carboxaldehyde

A direct method for the preparation of N‐protected/free indole‐7‐carboxaldehyde is reported from the corresponding N‐protected 7‐bromomethylindoles using three different conditions.     

Intramolecular Charge Transfer Effects on Flutamide Drug

Spectral characteristics of flutamide drug have been studied in various solvents and β-cyclodextrin (β-CD). The inclusion complex of flutamide with β-CD is analysed by UV-visible, fluorimetry, FT-IR, 1H NMR, SEM, DSC and AM1 methods. In all solvents, flutamide exhibits a dual fluorescence. The longer wavelength emission (A band ∼380 nm) is due to intramolecular charge transfer state (ICT) and the shorter wavelength emission (B band ∼285 nm) originates from a locally excited state. In β-CD, the increase in the fluorescence intensity of ‘A’ band indicates ICT emission enhanced in the β-CD medium. β-CD studies shows isopropyl group is present in the interior part of the β-CD cavity whereas amino and CF₃ groups are present in the outside of the β-CD cavity. A mechanism is proposed to explain the 1:1 inclusion process.