Structural and electrical properties of doped polypyrrole and its composite with montmorillonite clay

Polypyrrole is synthesized and doped with Dodecylbenzenesulphonic acid. The doped Polypyrrole with Dodecylbenzenesulphonic acid is intercalated into the layers of Montmorillonite clay successfully by in situ polymerization. The structural properties of synthesized doped Polypyrrole and intercalated doped Polypyrrole were studied by XRD analysis. The crystallinity of intercalated doped Polypyrrole into the layers of Montmorillonite clay is confirmed by means of X-rays diffraction studies, which is more than the doped Polypyrrole. Enhanced d-spacing of Montmorillonite confirmed that doped Polypyrrole is interclated into the layers of Montmorillonite clay at nanoscale. The scanning electron micrographs also confirm the formation of dual phase of platelet as well as of flaky structure of intercalated doped Polypyrrole. Temperature dependant conductivity showed three dimensional variable ranges hopping model. Activation energy, density of states and hopping length are calculated and found to be influenced by intercalating Doped Polypyrole into the layers of Montmorillonite clay.     

Zinc and iron determination in serum and urine samples of thyroid patients using cloud point extraction

A simple and rapid cloud point extraction method was applied for preconcentration of trace quantities of zinc (Zn) and iron (Fe) in biological samples (serum and urine) of thyroid patients prior to determination by flame atomic absorption spectrometry. The metals in serum and urine samples were complexed with 1-(2-thiazolylazo)-2-naphthol and entrapped in the surfactant octylphenoxypolyethoxyethanol (Triton X-114). After centrifugation, the surfactant-rich phase was diluted with 0.1 M HNO3 in methanol. For optimum recovery of analytes, the influences of the analytical parameters, including pH and amounts of complexing and surfactant reagents, were investigated. Enrichment factors of 66.4 and 70.2 were obtained for the preconcentration of Zn(II) and Fe(III), respectively. The obtained results showed sufficient recoveries (>98%) for Zn(II) and Fe(III) in certified reference materials (CRMs). The proposed method was applied to the determination of Zn(II) and Fe(III) in biological (serum and urine) samples and CRMs.     

Iodobenzene diacetate (IBD) catalyzed an quick oxidative aromatization of Hantzsch-1,4-dihydropyridines to pyridines under ultrasonic irradiation

This project was undertaken to demonstrate the potential of iodobenzene diacetate for the oxidative aromatization of Hantzch-1,4-dihydropyridines under ultrasonic irradiation. All reactions were carried out under ultrasonic irradiation and results were compared with traditional method. Sonochemical switching was observed in case of oxidative aromatization of 4-n-alkyl substituted 1,4-DHP. Without sonication, dealkylation occurred in case of n-alkyl substituted 1,4-DHP (ionic mechanism) but under ultrasonic irradiation, n-alkyl group was not expelled (radical mechanism). However, secondary alkyl (isopropyl) and benzyl group were expelled under both conditions.     

An analytic framework to develop policies for testing, prevention, and treatment of two-stage contagious diseases

In this paper we consider healthcare policy issues for trading off resources in testing, prevention, and cure of two-stage contagious diseases. An individual that has contracted the two-stage contagious disease will initially show no symptoms of the disease but is capable of spreading it. If the initial stages are not detected which could lead to complications eventually, then symptoms start appearing in the latter stage when it would be necessary to perform expensive treatment. Under a constrained budget situation, policymakers are faced with the decision of how to allocate budget for prevention (via vaccinations), subsidizing treatment, and examination to detect the presence of initial stages of the contagious disease. These decisions need to be performed in each period of a given time horizon. To aid this decision-making exercise, we formulate a stochastic dynamic optimal control problem with feedback which can be modeled as a Markov decision process (MDP). However, solving the MDP is computationally intractable due to the large state space as the embedded stochastic network cannot be decomposed. Hence we propose an asymptotically optimal solution based on a fluid model of the dynamics in the stochastic network. We heuristically fine-tune the asymptotically optimal solution for the non-asymptotic case, and test it extensively for several numerical cases. In particular we investigate the effect of budget, length of planning horizon, type of disease, population size, and ratio of costs on the policy for budget allocation.     

Synthesis,structure determination and chemoselective catalytic studies of amino acids complexes of osmium(II)

The two new half sandwich amino acids complexes of osmium, i.e. [Os(η6‐p‐cymene)(κ1‐N‐(rac)‐phenylglycine methylester)Cl₂] ( A ) and [Os(η6‐p‐cymene)(κ1‐N,N′‐(S)‐phenylalanineamido)Cl] ( B ) have been synthesized and employed for chemoselective reduction of ketones (nine α,β‐unsaturated ketones and three saturated ketones). The complexes were characterized by spectroscopic as well as analytical methods; their solid structures were confirmed by single‐crystal X‐ray analysis. Both of the osmium complexes catalyze the reduction of α,β‐unsaturated ketones to saturated ketones via isomerization of the initially produced allylic alcohols. The reducible substrates were studied to obtain information on the steric and electronic factors which may affect the interaction of the substrate with the metal center and, thus, control the selectivity of the hydrogen‐transfer reductions. Copyright © 2008 John Wiley & Sons, Ltd.     

Facile Synthesis of Pyrazoline Derivatized Amides via Sydnone Ring Cleavage

In the present investigation, we have utilized 3‐[3′‐(5″‐aryl‐2″‐pyrazolin‐3″‐yl)]phenylsydnones 1a–c to couple two biodynamic moieties in amide derivatives 7 , 8 , 9 , 10 . The compounds 1a–c were brominated to 4‐bromo‐3‐[3′‐(5″‐aryl‐2″‐pyrazolin‐3″‐yl)]phenylsydnone 2 , which were further reacted with secondary amines to form the title compounds. These novel molecules were subjected to antitubercular activity against Mycobacterium tuberculae (H₃₇R_v) and antioxidant activity assay.     

Effective attenuation lengths for photoelectrons in thin films of silicon oxynitride and hafnium oxynitride on silicon

We have used the National Institute of Standards and Technology Database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to simulate photoelectron intensities for thin films of SiO_1.6N_0.4 and HfO_1.9N_0.1 on silicon with excitation by Al Kα X‐rays. We considered Si 2p_3/2 photoelectrons from SiO_1.6N_0.4 and the substrate and Hf 4f_7/2 photoelectrons from HfO_1.9N_0.1. The simulations were performed for ranges of film thicknesses and photoelectron emission angles and for two common configurations for X‐ray photoelectron spectroscopy (XPS), the sample‐tilting configuration and the Theta Probe configuration. We determined photoelectron effective attenuation lengths (EALs) by two methods, one by analyzing photoelectron intensities as a function of film thickness for each emission angle (Method 1) and the other by analyzing photoelectron intensities as a function of emission angle for each film thickness (Method 2). Our analyses were made with simple expressions that had been derived with the assumption that elastic‐scattering effects were negligible. We found that EALs from both methods were systematically larger for the Theta Probe configuration, by amounts varying between 1% and 5%, than those for the sample‐tilting configuration. These differences were attributed to anisotropy effects in the photoionization cross section that are expected to occur in the former configuration. Generally, similar EALs were found by each method for each film material although larger EALs were found from Method 2 for film thicknesses less than 1.5 nm. SESSA is a useful tool for showing how elastic scattering of photoelectrons modifies EALs for particular materials, film thicknesses, and XPS configurations. Copyright © 2012 John Wiley & Sons, Ltd.