Centrifugally spun poly(ethylene oxide) fibers rival the properties of electrospun fibers

Centrifugal force spinning (CFS), also known as centrifugal spinning, forcespinning, or rotary jet spinning, provides considerably higher production rates than electrospinning (ES), but the more widespread use of CFS as an alternative depends on the ability to produce fibers with robust thermal and mechanical properties. Here, we report the CFS of poly(ethylene oxide) (PEO) fibers made using a spinning dope formulated with acetonitrile (AcN) as the volatile solvent, and we describe the thermal and mechanical properties of the centrifugally-spun fibers. Even though the formation, diameter, and morphology of electrospun and centrifugally-spun PEO fibers are relatively well-studied, the article presents three crucial contributions: the pioneering use of PEO solutions in AcN as spinning dope, characterization of crystallinity and mechanical properties of the centrifugally-spun PEO fibers, and a comparison with the corresponding properties of electrospun fibers. We find that fiber formation occurrs for the chosen CFS conditions if polymer concentration exceeds the entanglement concentration, determined from the measured specific viscosity. Most significantly, the centrifugally spun PEO fibers display crystallinity, modulus, elongation-at-break, and fiber diameter that rival the properties of electrospun PEO fibers reported in the literature.     

Bi- and tetranuclear ligational deeds of a polyaza macrocycle having four diazine (N2) bridging components headed for CoII, NiII, CuII and ZnII ions: An emphasis on electrochemistry of non-innocent ligand system

Novel bi- and tetranuclear Co^II, Ni^II, Cu^II and Zn^II complexes having diazine bridging units have been prepared and characterised on the basis of analytical and spectroscopic techniques. With the help of electronic spectra and magnetic moment measurements, it is predicted that the Co^II and Ni^II complexes have octahedral geometry while Cu^II and Zn^II complexes found to be square pyramidal. Present Zn^II and Cu^II complexes are binuclear in nature, where as Co^II and Ni^II complexes are tetranuclear with feeble antiferromagnetic exchange interactions. UV–visible spectral studies, in the range 275–425 nm, evidence the significant blue shift in π → π* transition which provide the ease of stabilization of bonding molecular orbitals in the complexes. All complexes are monomeric in nature. Ligand and all complexes were found to be electrochemically active compounds. One electron transfer process is observed in ligand similarly, there is no significant change in the cyclic voltammograms of Co^II and Zn^II complexes, while Cu^II and Ni^II complexes show one and two electron transfer redox behaviours, respectively in the present macrocyclic ligand field.     

Synthesis of dipeptidyl peptidase-4 inhibitors: a brief overview

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Bessel beams: Effects of polarization

An approximation to a Bessel beam produced by tightly focusing linearly polarized light is known to produce a smaller central lobe than focusing plane polarized light. This is because the plane polarized wave gives a broad central lobe caused mainly by a parasitic longitudinal field component. It is known that this problem can be overcome by focusing radially polarized light. Here we demonstrate that other polarization distributions based on a linear combination of transverse electric (TE1) and transverse magnetic (TM1) fields can give a beam even narrower than for the radially polarized case. Special cases of this combination are identified, corresponding to the smallest width (TE1), and the maximum peak intensity compared with the side lobes (electric dipole polarization). Axially-symmetric forms can be generated by illumination with elliptically polarized light. A particular case is azimuthal polarization with a phase singularity, which is equivalent to TE1. For a semi-angular aperture of 60°, the TE1 case gives a central lobe width 9% narrower than for radially polarized illumination, while for plane polarized illumination it is 12% wider than the radially polarized case.     

A 4/3-approximation for TSP on cubic 3-edge-connected graphs

For a 3-edge-connected cubic graph $G=(V,E)$, we give an algorithm to construct a connected Eulerian subgraph of $2G$ using at most $?4\left|V\right|∕3?$ edges.     

Novel synthesis of highly porous three-dimensional nickel cobaltite for supercapacitor application

Highly porous 3D nickel cobaltite nanoparticles were synthesized by combustion technique. X-ray diffraction study reveals the changes in phase, crystallinity, and particle size of the prepared samples with respect to calcination temperature. Typical porous 3D foam like morphology of the materials was identified from the FESEM and HRTEM images. BET measurement further confirms the mesoporous nature of the samples with high-surface area. Mixed valence state of ions was identified from XPS measurements. Electrochemical studies disclose the impact of calcination temperature on the electrodes capacitive performance. 3D porous morphology of the material allows the complete utilization of active material available for the electrolyte ions. NiCo₂O₄ calcined at 400 °C exhibited the maximum specific capacitance of 908 Fg⁻¹ at 5 mV/s scan rate among the prepared samples and 90 % capacitance retention at the end of 1000 cycles. Impedance study demonstrates the low resistance and facile diffusion of electrolyte ions within the material.

     

Alternate and Efficient Method for the Total Synthesis of Egonol via Sonogashira Coupling Reaction

Efficient method for the total synthesis of egonol in five steps via Sonogashira coupling reaction is reported.     

Development of a new all solid contact Cs<Superscript>+</Superscript> ion selective electrode

Studies were carried out to develop all solid contact cesium ion selective electrode with 25,27-bis(1-octyloxy)calix[4]arene-crown-6 as an ionophore. Polyaniline (PANI), deposited on Pt electrode by electrochemical method, was used as a transducer. Three different types of electrodes were made with variation in thickness of PANI film and gold nanoparticles doped PANI as transducers. The best response was observed with ISE having Au nanoparticles doped PANI as a transducer. The optimised ISE gave Nernstian response in the range 10^?7 to 10^?2 M with the slope of 55.0 ± 0.6 mV/decade of Cs⁺. The response of ISE for Cs⁺ is fairly constant above the pH 4. The developed ISE was successfully employed to determine Cs⁺ in simulated high level nuclear waste solutions and CsCl spiked tap water samples.     

Design,synthesis and MAO inhibitory activity of 2-(arylmethylidene)-2,3-dihydro-1-benzofuran-3-one derivatives

A series of 2-(arylmethylidene)-2,3-dihydro-1-benzofuran-3-one derivatives(aurones, 1–20) were synthesized and screened for their inhibitory activity against h MAO. Seventeen compounds(1–5, 7–17,19) were found to be selective towards h MAO-B, while two were non-selective(6 and 20) and one(18)selective towards h MAO-A. Compound 17(Ki = 0.10 0.01 mmol/L) was found to be equally potent and selective towards h MAO-B, when compared with the standard drug Selegiline(Ki = 0.12 0.01 mmol/L).Nature and position of substitution in aryl ring at 2nd position of benzofuranone influences h MAO-B inhibitory potency, while their structural bulkiness influences selectivity between h MAO-A and h MAO-B.Molecular docking simulation was also carried out to understand the interaction of inhibitor with the enzyme at molecular level, and we found the docking results were in good agreement with the experimental values. Comparison of the activity profile of the aurones with their corresponding flavones reported earlier by our group revealed that there exists no difference in potency as well as selectivity.