Modification of magnetic anisotropy in metallic glasses using high-energy ion beam irradiation

Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe₄₀Ni₄₀B₂₀ and Fe₄₀Ni₃₈Mo₄B₁₈ metallic glass ribbons. 90 MeV ¹²⁷I beam was used for the irradiations. Irradiation doses were 5×10¹³ and 7.5×10¹³ ions/cm². The relative intensity ratios D ₂₃ of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy.     

Diverted total synthesis of falcitidin acyl tetrapeptides as new antimalarial leads

We report not only the convergent total synthesis of falcitidin, a natural inhibitor of falcipain-2 from myxobacterium Chitinophaga, but also its diversification into a new antimalarial class of N-acyl tetrapeptides (Acyl-His-Ile-Val-Pro-NH₂). Despite the lack of whole-cell activity of falcitidin itself, our study led to the identification of a trifluoromethyl (CF₃) analogue displaying sub-micromolar IC₅₀ activity against Plasmodium falciparum 3D7 in a standard blood-cell assay, but only when N-tritylated on its histidine (imidazole) residue.     

Low frequency multiphonon absorption in InP:Fe

Far infrared transmission measurements have been made on iron doped crystals of InP in the 20–250 cm^?1 region at temperatures between 6 and 300 K. New weak bands were observed at 42, 83 and 113 cm^?1. The frequencies and temperature dependences of these bands indicate that they arise from two-phonon difference processes and appropriate assignments are given. Another new band observed at 65 cm^?1 is one-phonon like.     

Modified soybean oil as a reactive diluent: Synthesis and characterization

Soybean oil was modified in two steps: (1) conjugation of soybean oil and (2) Diels‐Alder addition with 3‐(trimethoxysilyl)propyl methacrylate, 2,2,2‐trifluoroethyl methacrylate and triallyl ether acrylate. The structures were characterized using ¹H NMR, ¹³C NMR, ¹³C‐¹H gradient heteronuclear single quantum coherence (gHSQC) NMR spectroscopy, and MALDI‐TOF mass spectrometry. The ¹³C‐¹H gHSQC NMR spectra helped confirm the formation of a cyclohexene ring in all reactions, indicating a Diels‐Alder addition. The diluent efficiency of modified soybean oil was evaluated in long oil alkyd formulation. Triallyl ether functionalized soybean oil resulted in the highest reduction in the viscosity of the alkyd formulations. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3045–3059     

Synthetic magnetic opals

We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there exists no report in literature on any BiNi compound which is magnetic.     

Magnetization curves for general cylindrical samples in a transverse field

Using the recent results for the surface current density on cylindrical surfaces of arbitrary cross-section producing uniform interior magnetic field we propose a method for obtaining solutions of Bean’s critical state model for general cylindrical samples. The method uses the technique of conformal mapping to express the sample surface and the flux-fronts in terms of a set of coefficients that depend on a parameter. The flux-fronts are to be determined by solving a system of nonlinear ordinary differential equations for the coefficients. Retaining only a certain finite number of leading coefficients we get an approximate solution. The procedure is illustrated by considering two cyclindrical samples — one with an elliptical cross-section and the other with a non-elliptical cross-section. The virgin curve and small and large magnetization hysteresis loops for the two samples are obtained.     

Low-field vortex dynamics in various high-T c thin films

We present a novel ac susceptibility technique for the study of vortex creep in superconducting thin films. With this technique we study the dynamics of dilute vortices in c-axis oriented Y-123, Hg-1212, and Tl-1212 thin films, as well as a axis oriented Hg-1212 thin films. Results on the Hg-1212 and Tl-1212 thin films indicate that dislocation-mediated plastic flux creep of single vortices dominates at low temperatures and fields. As the temperature (or the field) is increased, the increasing vortex-vortex interactions promote a collective behavior, which can be characterized by elastic creep with a non-zero μ exponent. Also, in some of these samples effects of thermally assisted quantum creep are visible up to 45 K in some of these samples. In Y-123 thin films, creep is found to be collective down to the lowest temperatures and fields investigated, while the quantum creep persists only up to 10–11 K.     

Synthesis and characterization of cobalt(II), nickel(II), copper(II) and zinc(II) complexes of 2-nitrobenzoic acid with methyl carbazate as ancillary ligand. Crystal structure of the copper(II) complex

Divalent metal complexes of general formula [M(2-nb)₂(mc)₂].2(2-nbH), where M = Co(II), Ni(II), Cu(II) or Zn(II), 2-nbH = 2-nitrobenzoic acid and mc = methyl carbazate (NH₂NHCOOCH₃), have been prepared and characterized by physicochemical and spectroscopic methods. Single-crystal X-ray study of the Cu(II) complex revealed that the molecule is centrosymmetric, with two N,O-chelating mc ligands in equatorial positions and a pair of monodentate 2-nb anions in the axial positions. The lattice 2-nbH molecules help to establish the packing of monomers through hydrogen-bonding interactions. Thermal stability and reactivity of the complexes were studied by TG–DTA. Emission studies show that these complexes are fluorescent.     

A non‐gassing electroosmotic pump with sandwich of poly(2‐ethyl aniline)‐Prussian blue nanocomposite and PVDF membrane

Low voltage, non‐gassing electroosmotic pump (EOP) was assembled with poly(2‐ethyl aniline) (EPANI)‐Prussian blue nanocomposite electrode and commercially available hydrophilic PVDF membranes. The nanocomposite material combines excellent oxidation/reduction capacity of EPANI with exceptional stability by shuttling of proton between Prussian blue nanoparticles and EPANI redox matrix. The flow rate was highly dependent on the electrode composition but it was linear with applied voltage. The flow rate at 5 V for different nanocomposite, EPANI, EPANI‐A, EPANI‐B, and EPANI‐C were 127.29, 187.41, 148.51, and 95.47 µL/min cm², respectively, which increases substantially with increase in the Prussian blue content. The obtained best electro osmotic flux was 43 µL/min/V/cm² for EPANI‐A. It was higher than most of the EOP assembled using polyquinone and polyanthraquinone redox polymers. The assembled EOP remained exceptionally stable until the electrode charge capacity was fully utilized. The best EOP produces a maximum stall pressure of 1.2 kPa at 2 V. These characteristics make it suitable for a variety of microfluidic/device applications.     

Naravelia zeylanica [corrected] occurrence of primary benzamides in flowering plants

Extract of Naravelia zeylanica (Ranunculaceae) yielded three simple benzamides, 3,4-methylenedioxybenzamide, 4-methoxybenzamide and 4-hydroxy-3-methoxybenzamide. These simple C6C1 metabolites have been encountered as natural products for the first time. The compounds were identified by direct comparison of their spectral (1H- and 13C-NMR) and chromatographic (GCMS) data with those of authentic samples. Authentic 4-hydroxy-3-methoxybenzamide was synthesized in one step by treatment of 4-hydroxy-3-methoxybenzonitrile with sodium perborate. Authentic 3,4-methylenedioxybenzamide was synthesized from the corresponding acid.