Low temperature 151Eu and 57Fe Mössbauer study of mechanically alloyed EuFeO3

Low temperature ⁵⁷Fe Mössbauer spectra of mechanically alloyed EuFeO₃ prepared by mechanical alloying depicts an interesting transformation in its hyperfine magnetic state, from a triple phase magnetic system at room temperature to a single phase ferromagnetic state at 20 K. The hyperfine magnetic field increased by 12% at 20 K from its room temperature. The isomer shift and quadrupole splitting values exhibit a peak around 200 K. Low temperature ¹⁵¹Eu Mössbauer measurements show that the line-width increased to its maximum value at 80 K which is 45% compared to its room temperature value not enough to suggest splitting.     

Preparation of nitropyridines by nitration of pyridines with nitric acid

Nitration of pyridines 1a-o with nitric acid in trifluoroacetic anhydride, gave the corresponding 3-nitropyridines 6a-n in yields of 10-83%.     

Axisymmetric shrink fit problems of the elastic cylinder of finite length

The general case of the axisymmetric shrink fit problems of a solid elastic cylinder whose ends are free from tractions is formulated in terms of the Fredholm integral equation of the second kind. This is accomplished by the use of Papkovich-Fadle eigenfunction and the calculus of residues. Indentation by three types of sleeve is considered; (i) Edge Sleeve, (ii) Symmetrical central Sleeve and, (iii) Two identical edge sleeves. For each case, numerical results of effective resistance and contact pressure are reported for various values of the Poisson's ratio, radius of the cylinder and the sleeve width.

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Zusammenfassung Der allgemeingültige Fall achsensymmetrischer Schrumpf-Anpassungs probleme eines elastischen Festzylinders dessen Enden zugkraftfrei sind wird in der Form der zweiten Integral-gleichung von Fredholm ausgedrückt. Dies wird durch die Anwendung der Papkovich-Fadle Eigenfunktion und der Residuenrechung erreicht. Drei Arten von Manteleinkerbungen werden untersucht: (i) einseitige Endeinkerbung, (ii) symmetrische Zentraleinkerbung, (iii) zweiseitige Endeinkerbung. Für jeden Testfall werden die Zahlenergbnisse des effektiven Winderstandes und des Berührungsdruckes für verschieden Werter der Poisson Ratio, des Zylinderradius und der Mantelkerbweite berichtet.

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The present results were obtained in the course of research supported by NSF Grand GK-25604.     

O,O′-Dimethyl diphenyldithiophosphates of titanium(IV): synthesis,spectroscopic, DFT and biological studies

Dimethyl diphenyldithiophosphate complexes of titanium(IV), [(C₅H₅)₂Ti{S₂P(OAr)₂}_nCl_2-n] (Ar?= 2,4-(CH₃)C₆H₃, 2,5-(CH₃)C₆H₃, 3,4-(CH₃)C₆H_3, 3,5-(CH₃)C₆H_3, 3-CH₃-4-Cl-C₆H₃O; n?=?1 and 2) have been synthesised and characterised by various physicochemical techniques along with computational analysis of the complexes (2), (9) and (10) using density functional theory (DFT) and time-dependent DFT (TDDFT). Comparison of antimicrobial activity of the free ligands and complexes has shown that the complexes are more effective than the free ligands. The in vitro cytotoxic by using a MTT staining method with RAW 264.7 cells (mouse macrophages) have been investigated. On the basis of analytical and DFT data, a distorted trigonal bipyramidal around titanium(IV) may be assigned to the complexes (1–5) and distorted octahedral geometries for the complexes (6–10).     

Chemoenzymatic asymmetric synthesis of fluoxetine,atomoxetine, nisoxetine,and duloxetine

The asymmetric synthesis of two well-known anti-depressant drugs, fluoxetine and duloxetine has been accomplished in a chemoenzymatic manner. The main highlight of the synthesis is the enantioselective cyanohydrin formation by a plant (R)-HNL (hydroxynitrile lyase). The enantiopure cyanohydrins are then synthetically manipulated into the above two drug molecules and two of their structural analogues, atomoxetine and nisoxetine.     

Processing and characterization of oriented electrospun poly(vinylidene fluoride) mats

Mats of highly oriented poly(vinylidene fluoride) nanofibers were electrospun by means of a conventional electrospinning equipment; the orientation, however, was obtained using a disk collector rotating at a speed of 4000 rpm and a device that reduced the influence of air displacement during nanofiber orientation. Thermal transitions of the mats were determined by differential scanning calorimetry, the predominant crystalline phase by Fourier transform infrared spectroscopy and wide‐angle X‐ray scattering and the nanofiber orientation and morphology by scanning electron microscopy. Relative permittivity, loss index, stable remnant polarization, and coercive field of the mats were also determined and compared with those obtained for a mat electrospun at 2000 rpm and an oriented commercial film. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 000: 000–000, 2012     

Nanocomposite Made of an Oligo(p‐phenylenevinylene)‐Based Trihybrid Thixotropic Metallo(organo)gel Comprising Nanoscale Metal–Organic Particles,Carbon Nanohorns,and Silver Nanoparticles

A silver ion (Ag⁺)‐triggered thixotropic metallo(organo)gel of p‐pyridyl‐appended oligo(p‐phenylenevinylene) derivatives (OPVs) is reported for the first time. Solubilization of single‐walled carbon nanohorns (SWCNHs) in solutions of the pure OPVs as well as in the metallogels mediated by π–π interactions has also been achieved. In situ fabrication of silver nanoparticles (AgNPs) in the SWCNH‐doped dihybrid gel leads to the formation of a trihybrid metallogel. The mechanical strength of the metallogels could be increased stepwise in the order: freshly prepared gel<dihybrid gel<trihybrid gel. Microscopic studies of the trihybrid gel indicate the formation of three distinct morphologies, that is, nanoscale metal–organic particles (NMOPs), flowerlike aggregates of SWCNHs and AgNPs, and also their integration with each other. Detailed studies suggest lamellar organizations of the linear metal–ligand complexes in the NMOPs, which upon association create a three‐dimensional network that eventually immobilizes the solvent molecules.