Optimization of salt concentration and explanation of two peak percolation in blend solid polymer nanocomposite films

The present paper is focused toward the preparation of the flexible and free-standing blend solid polymer electrolyte films based on PEO-PVP complexed with NaPF₆ by the solution cast technique. The structural/morphological features of the synthesized polymer nanocomposite films have been investigated in detail using X-ray diffraction, Fourier transform infra-red spectroscopy, Field emission scanning electron microscope, and Atomic force microscopy techniques. The film PEO-PVP?+?NaPF₆ (\( \ddot{\mathrm{O}}/{\mathrm{Na}}^{+}= \)8) exhibits highest ionic conductivity ~?5.92?×?10^?6 S cm^?1 at 40 °C and ~?2.46?×?10^?4 S cm^?1 at 100 °C. The temperature-dependent conductivity shows an Arrhenius type behavior and activation energy decreases with the addition of salt. The high temperature (100 °C) conductivity monitoring is done for the optimized PEO-PVP?+?NaPF₆ (\( \ddot{\mathrm{O}}/{\mathrm{Na}}^{+}= \)8) highly conductive system and the conductivity is still maintained stable up to 160 h (approx. 7 days). The thermal transitions parameters were measured by the differential scanning calorimetry (DSC) measurements. The prepared polymer electrolyte film displays the smoother surface on addition of salt and a thermal stability up to 300 °C. The ion transference number (t_ion) for the highest conducting sample is found to be 0.997 and evidence that the present system is ion dominating with negligible electron contribution. Both linear sweep voltammetry and cyclic voltammetry supports the use of prepared polymer electrolyte with long-term cycle stability and thermal stability for the solid-state sodium ion batteries. Finally, a two peak percolation mechanism has been proposed on the basis of experimental findings.

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Graphical abstract A plot of free ion & ion pair area against salt content and AFM image of optimised system

     

Small Molecules Targeting Mycobacterium tuberculosis Type II NADH Dehydrogenase Exhibit Antimycobacterial Activity

The generation of ATP through oxidative phosphorylation is an essential metabolic function for Mycobaterium tuberculosis (Mtb), regardless of the growth environment. The type II NADH dehydrogenase (Ndh‐2) is the conduit for electrons into the pathway, and is absent in the mammalian genome, thus making it a potential drug target. Herein, we report the identification of two types of small molecules as selective inhibitors for Ndh‐2 through a multicomponent high‐throughput screen. Both compounds block ATP synthesis, lead to effects consistent with loss of NADH turnover, and importantly, exert bactericidal activity against Mtb. Extensive medicinal chemistry optimization afforded the best analogue with an MIC of 90 nm against Mtb. Moreover, the two scaffolds have differential inhibitory activities against the two homologous Ndh‐2 enzymes in Mtb, which will allow precise control over Ndh‐2 function in Mtb to facilitate the assessment of this anti‐TB drug target.     

A study of\bar np annihilations between 0.5 and 0.8 GeV/c

A study of \(\bar np\) annihilations with \(\bar n\) momentum between 0.5 and 0.8 GeV/c is presented. The search fors-channel resonances in \(\bar np\) annihilations reveal possibly two narrow structures in the odd pions final state. Inclusiveρ ⁰ andf ⁰ cross sections in \(\bar np\) annihilations have been estimated to be 9.0±0.6 mb and 3.4±0.6 mb respectively. Longitudinal and transverse momentum distributions for inclusiveρ ⁰ production have been presented. A study of resonance production in exclusive final state revealsρ ⁰ production to be dominant in the odd pion final states andρ ⁺,ω ⁰ productions are most important for the even pion final states. Theπ ⁺ π ^? effective mass spectra in the backward and the forward directions in the \(\bar np\) c.m. system have been examined for a possible ?-ω interference effect.     

Synthesis of CdS nanoparticles in colloidal state and its possible interaction with tyrosine

The basic objective is to develop a simpler method of preparation of the colloidal CdS nanoparticles with greater stability and to study interaction with tyrosine molecules. Average size of the particles in the colloid is found to be about 3 nm as probed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. Effect of both sulfide enriched CdS as well as Cd(2+) enriched CdS on tyrosine is investigated both through absorbance and emission spectroscopy. Quenching of tyrosine emission followed Stern-Volmer relation and was found to be independent of temperature, indicating possible static quenching. However, Forster transfer between tyrosine and CdS can be suspected to mimic static quenching in addition to the charge transfer complexes. In the presence of Cd(2+) enriched CdS nanoparticles, the emission of tyrosine in phosphate buffer shows typical spectral broadening and a long wavelength increase in fluorescence emission. This may be attributed to the sensitized emission of CdS itself.     

Analysis of some phenolic copolymer mixtures by electrometric titration techniques

Some two-, three- and four-component phenolic copolymers have been characterized, and mixed in definite stoichiometric proportions. The total amount of acidic and basic functional groups in a given weight of the copolymer mixture have been calculated from the characteristic parameters of the polymer components. Analysis of these copolymer mixtures by electrometric titration techniques revealed an excellent correlation between the calculated and observed values of functional groups.     

Ancient biodeterioration: an FT–Raman spectroscopic study of mammoth and elephant ivory

Raman spectra of mammoth ivory specimens have been recorded using near-infrared excitation, and comparisons made with modern Asian and African elephant ivories. Whereas the most ancient mammoth ivory (60–65 ky) showed no evidence for an organic collagen component, more recent samples of mammoth ivory indicated that some preservation had occurred, although with biodeterioration of the protein structure exhibited by the amide I and III bands in the 1200–1700 cm⁻¹ region of the Raman spectrum. The consequent difficulties encountered when applying chemometrics methods to ancient ivory analysis (which are successful for modern specimens) are noted. In the most ancient mammoth ivory specimens, which are extensively fragmented, evidence of mineralization is seen, with the production of gypsum, calcite and limonite; Raman microscopic analysis of crystalline material inside the fissures of the mammoth ivory shows the presence of gypsum as well as cyanobacterial colonisation. The application of Raman spectroscopy to the nondestructive analysis of archaeological materials in order to gain information of relevance to their preservation or restoration is highlighted.     

Elemental uptake of radish grown near a Municipal Solid Waste dumping site by EDXRF

Radish plant was collected along with root and soil from the nearby area of a Municipal Solid Waste dumping site of the metropolitan city of Kolkata, West Bengal, India and analyzed for a wide range of elements using the EDXRF technique with a ¹⁰⁹Cd point source and a Si(Li) detector. The samples comprized of the root-soil, root and leaves. For quality control purposes, NIST standard reference material (SRM) 1648 Urban Particulate Matter had also been analyzed using the same procedure as for the samples. Concentrations of elements with X-ray energies in the range of 3–20 keV in the soil around the root and their uptake pattern by the root and the leaves have been estimated.     

Facile one pot microwave induced solvent-free synthesis and antifungal, antitubercular screening of spiro [1,5]-benzothiazepin-2,3'[3'H]indol-2[1'H]-ones

Microwave activation coupled with dry media technique as a green chemistry procedure has been applied to synthesis of a series of some new title compounds. They have been obtained by the reaction of in situ synthesized 1,3-dihydro-3-[2-(phenyl/4-fluorophenyl)-2-oxoethylidene)-indol-2(1H)-one (4a, b) with substituted aminobenzenethiols (5a-d). The key intermediates 4a, b were also prepared in one step by this improved technique by reacting isatin and substituted acetophenones (2a, b). The results obtained under microwave irradiation when compared with that following conventional method demonstrate the versatility of the process. The title compounds 7a-e have also been screened for their antifungal and antitubercular activity, 7a and 7e showing maximum inhibition of growth of Alternaria alternata and Fusarium oxysporium and 7b, c, e revealing significant antitubercular activity.