Gas chromatography-electron ionization-mass spectrometry analysis of O,O'- dialkyl methylphosphonites for verification analysis of the Chemical Weapons Convention

Gas chromatography-mass spectrometry (GC-MS) analysis of O,O'-dialkyl methylphosphonites (DAMPs) was carried out with a view to developing a database and understanding the mechanism of fragmentation. DAMPs are included in the list of schedule 2B4 chemicals of the Chemical Weapons Convention. GC-MS analysis of DAMPs and their deuterated analogs revealed that their fragmentations were dominated by α-cleavages, alkenyl radical loss and hydrogen rearrangements. Based on fragment ions of deuterated analogs and density functional theory calculations, the fragmentation routes were rationalized.     

Composition of a monoterpenoid-rich essential oil from the rhizome of Zingiber officinale from north western Himalayas

The chemical composition of the essential oil from the rhizome of ginger (Zingiber officinale Roscoe), collected from Nahan, Himachal Pradesh, India, was determined by gas chromatography and GC-MS. Fifty-one compounds, representing 95.1% of the oil, were identified. The oil was characterized by relatively large amounts of the monoterpenoids 1,8-cineole (10.9%), linalool (4.8%), borneol (5.6%), alpha-terpineol (3.6%), neral (8.1%), geraniol (14.5%), geranial (9.5%), trans-dimethoxy citral (5.0%) and geranyl acetate (6.3%). Five compounds, namely trans-linalool oxide, trans-linalool oxide acetate, (Z)-dimethoxycitral, (E)-dimethoxy citral and epi-zingiberenol are reported for the first time in oil of ginger.     

Forward–Backward–Half Forward Dynamical Systems for Monotone Inclusion Problems with Application to v-GNE

Journal of Optimization Theory and Applications - In this paper, the first-order forward–backward–half forward dynamical systems associated with the inclusion problem consisting of...     

Improved Performance of an Amperometric Biosensor with Polydiaminonaphthalene on Electrochemically Deposited Au Nanoparticles

The performance of an enzyme sensor fabricated through covalent bond formation on the HRP‐bonded poly(1,8‐diaminonaphthalene) (polyDAN) layer with gold nanoparticles (AuNPs) was applied to catalyze the electrochemical reduction of H₂O₂. The surface characteristics of the sensor probe were studied using cyclic voltammetry, SEM, XPS, QCM, and impedance spectroscopy. The AuNP‐deposited surface resulted in higher conductivity and sensitivity for H₂O₂ detection in phosphate buffer solution. A linear calibration plot was obtained in the H₂O₂ concentration range between 10.0 μM and 25.0 mM with detection limit 5.0±1.25 μM. The lifetime of HRP/polyDAN/AuNP/GC probe was over 70 days without response loss.     

Ferrocenyl,Alkyl, and Aryl‐Pyrido[2,3‐d]Pyrimidines as Vasorelaxant of Smooth Muscle of Rat Aorta via cAMP Conservation Through Phosphodiesterase Inhibition

New pyrido[2,3‐d]pyrimidines 11 , 12 , 13 , and 21 have been synthesized. The vasorelaxant effect on smooth muscle isolated from rat aorta, via PDEs inhibition, of these compounds along with other pyrido[2,3‐d]pyrimidines 14 , 15 , 16 , 17 , 18 , 19 , 20 reported earlier by our group, has also been determined. These pyrido[2,3‐d]pyrimidines 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 were synthesized by the reaction of ferrocenyl‐ethynyl ketones ( 1 , 2 , 3 , 4 ) or α‐alkynyl ketones ( 5 , 6 , 7 , 8 , 9 , 10 ) with 6‐amino‐1,3‐dimethyluracil using [Ni(CN)₄]^?4 as an active catalytic species, formed in situ in a Ni(CN)₂/NaOH/H₂O/CO/KCN aqueous system. Evaluation of the vasorelaxant effect of compounds 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 demonstrated that all compounds relax the tissue in a concentration‐dependent manner. The structural changes do not alter the effectiveness; however, there are differences related to potency expressed as EC₅₀. Compounds 12 (7‐ferrocenyl‐1,3‐dimethyl‐5‐(m‐tolyl)‐pyrido[2,3‐d]pyrimidine) and 13 (7‐ferrocenyl‐1,3‐dipropyl‐5‐(4‐metoxyphenyl)‐pyrido[2,3‐d]pyrimidine) were the most potent compounds, even more than rolipram, reference drug; the EC₅₀ was 0.41 ± 0.02 μM and 0.81 ± 0.11 μM for 12 and 13 , correspondingly. The EC₅₀ of compounds 15 (7‐ferrocenyl‐1,3‐dimethyl‐5‐phenyl‐pyrido[2,3‐d]pyrimidine), 14 (7‐ferrocenyl‐5‐(3,5‐dimethoxyphenyl)‐1,3‐dimethylpyrido[2,3‐d]pyrimidine), and 19 (5‐n‐butyl‐7‐ethyl‐1,3‐dimethylpyrido[2,3‐d]pyrimidine) was similar to EC₅₀ of rolipram. Compounds 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 significantly induce concentration‐dependent vasorelaxation in endothelium‐intact aortic rings. In addition, the relaxation responses to each compound in either endothelium‐intact or endothelium denuded aortic rings were comparable, suggesting that removal of the functional endothelium has no significant influence on its intrinsic vasorelaxant activity. In vitro capability of conserving cyclic‐AMP or cyclic‐GMP (adenosine and guanosine 3′, 5′‐cyclic monophosphate) via PDE inhibition for compounds 12 , 13 , 14 , 15 and 19 was evaluated. Compounds 15 and 19 show the highest percent inhibition effect (94.83% and 83.98%, respectively) for the decomposition of c‐AMP. Docking studies showed that the compound 15 was selective for the inhibition of PDE‐4.     

Effect of annealing on the opto-electronic properties of Cu0.9In1.0Se2.0 films

The influence of annealing on the structure and opto-electronic properties of Cu_0.9In_1.0Se_2.0 films prepared by solution growth technique has been studied. The films annealed at 500–520°C in air, vacuum (10^?4 torr), In-vapour and Se-vapour show polycrystalline chalcopyrite structure with orientation perpendicular to the (220) plane. Films annealed in Se-vapour at 500°C for 30 min have maximum grain size (560 Å), minimum optical energy gap, maximum absorption coefficient, lowest resistivity, maximum photosensitivity and thus are suitable for photovoltaic applications. Annealing in In-vapour or in vacuum changesp-type CuInSe₂ inton-type which possibly arises due to the increase in Se vacancies.     

Diamond like carbon coated films for enzyme electrodes; characterization of biocompatibility and substrate diffusion limiting properties

The biocompatibility and substrate diffusion limiting properties for a range of diamond like carbon (DLC) coated microporous polycarbonate and DLC coated dialysis (haemodialysis) membranes have been studied. This characterisation builds upon previous findings where DLC coated membranes imparted enhanced enzyme electrode performance. In this study electrode linear ranges have been extended from 10 mM glucose for a 0.01 μm pore size membrane to 160 mM. These findings correlated with the duration of DLC deposition and associated reductions in permeability for glucose. Permeability coefficient ratios for both microporous and dialysis membranes were also found to be important with low glucose/O₂ permeability ratios imparting extensions in glucose linear response range. DLC coated membranes employed within enzyme electrodes have also been shown to exhibit enhanced haemocompatibility as determined by both sensitivity change and surface deposition of blood components examined by scanning electron microscopy. Correlations are made between the reduced losses in sensor response to biofouling/ working electrode passivation processes, and extended linear ranges that DLC coated membranes may impart to enzyme electrode performance. Particular reference is made to the determination of glucose levels within whole blood.     

Enzyme electrodes for continuous in-vivo monitoring

Blood metabolite levels can alter rapidly in the acutely ill patient and may need to be monitored continuously. Enzyme electrodes show promise as selective transducers for organic species and could provide the basis for practical monitoring systems.     

High-performance liquid chromatographic method for the simultaneous estimation of the key intermediates of duloxetine

A simple reversed-phase high-performance liquid chromatographic method employing C-18 column has been developed for simultaneous analysis of three intermediates in the synthesis of S-duloxetine, the antidepressant drug, viz., 2-acetyl thiophene (AT), N,N-dimethyl-3-keto-(2-thienyl)-propanamine (DKTP) and (S)-N,N-dimethyl-3-hydroxy-(2-thienyl)-propanamine (DHTP). Good separations were achieved by employing an isocratic system using acetonitrile and 0.05 M phosphate buffer (pH 7.0) containing 0.02% diethylamine. The detection was carried out at 241 nm. The method was validated for linearity, range, accuracy and precision. The developed method was applied for monitoring the progress of chemical synthesis of DKTP from AT followed by the biocatalytic reduction of DKTP to DHTP as the disappearance of the substrate and formation of the product can be monitored simultaneously by the present method.