Heavy Heparin: A Stable Isotope‐Enriched,Chemoenzymatically‐Synthesized,Poly‐Component Drug

Heparin is a highly sulfated, complex polysaccharide and widely used anticoagulant pharmaceutical. In this work, we chemoenzymatically synthesized perdeuteroheparin from biosynthetically enriched heparosan precursor obtained from microbial culture in deuterated medium. Chemical de‐N‐acetylation, chemical N‐sulfation, enzymatic epimerization, and enzymatic sulfation with recombinant heparin biosynthetic enzymes afforded perdeuteroheparin comparable to pharmaceutical heparin. A series of applications for heavy heparin and its heavy biosynthetic intermediates are demonstrated, including generation of stable isotope labeled disaccharide standards, development of a non‐radioactive NMR assay for glucuronosyl‐C5‐epimerase, and background‐free quantification of in vivo half‐life following administration to rabbits. We anticipate that this approach can be extended to produce other isotope‐enriched glycosaminoglycans.     

Luminescence studies and formation mechanism of symmetrically dispersed ZnO quantum dots embedded in SiO2 matrix

Surface effects significantly influence the functionality of semiconductor nanocrystals. In the current work we present synthesis of ZnO quantum dots (QD) vis-a-vis symmetrically dispersed ZnO quantum dots embedded in SiO₂ matrix and discussed their optical properties to understand the role of the surface effects. These nanomaterials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared (FTIR), absorption (UV-visible) and photoluminescence (PL) spectroscopy. TEM studies confirm the formation of ZnO nanophosphors inside the SiO₂ matrix in highly symmetrical manner. These symmetrically dispersed ZnO@SiO₂ nanophosphors exhibited enhanced stable emission over uncoated sample and would permit the conjugation of the nanocrystals to biological entities after functionalization. Furthermore, the mechanism behind the formation of symmetrically dispersed ZnO quantum dots embedded in SiO₂ matrix was discussed in detail.     

Effect of curvature of the boundary on the modal dispersion of a single-mode dielectric waveguide of core cross-section bounded by involuted spirals

In this paper, we are presenting an analytical study of the effect of curvature of the spiral shape on the modal dispersion characteristics of the waveguide whose core cross-section is bounded by two involuted spirals of the form 1/r=ξθ, where ξ is a constant and represents the curvature of the spiral taken to design the waveguide into consideration. This study has been done under the weak guidance approximation. Analyzing the dispersion curves for different curvature we found that this waveguide supports only the single mode, and their cutoff value decreases as the the curvature of the spiral increases.     

An ultrasonic characterization of ferrofluid

Nanoparticles of Cr₂O₃ are prepared through hydrothermal synthesis process using CrO₃/PVA in aqueous solution using sucrose as a reducing agent. The calcination temperature is taken 300 and 350 °C. XRD and SEM of the powdered Cr₂O₃ particles are done for the characterization. The average particle size is found 30–80 nm. It is found that average particle size increases with calcination temperature. The UV–visible absorption spectra are taken for the study of photo-physical properties of ferrofluids. Ultrasonic velocity and absorption measurements are performed in Cr₂O₃ ferrofluid using variable path interferometer and pulse-echo techniques, respectively. The achieved results are discussed in correlation with the magnetic and other physical properties of Cr₂O₃.     

Ionic conductivity and structural properties of MnO-doped Bi4V2O11 system

Bi₄V₂O₁₁ exists in three phases viz. α, β, and γ. High temperature γ-phase can be stabilized to room temperature owing to its higher conductivity by the partial substitution of metallic cations for vanadium in Bi₄V₂O₁₁. Phase transitions from α → β and β → γ are composition and temperature-dependent. Mn²⁺-doped compounds Bi₄V_2−x Mn _x O_{11− δ} (0 ≤ x ≤ 0.4) have been synthesized by solid state reaction technique and investigated by X-ray diffraction and ionic conductivity measurement. High ionic conducting γ-phase is stabilized for x ≥ 0.2. The ionic conductivity of the series of Bi₄V_2−x Mn _x O_{11− δ} samples has been measured by using ac impedance spectroscopy technique. The conductivity data do show departure from its simple Arrhenius behavior for all of the compositions. The highest conductivity observed for x = 0.2 sample can be attributed to lower activation energy.     

Absolute frequency determination of the 5P3/2-->7S1/2 transition in 87Rb

We report the absolute frequency of the important 5S(1/2)-->7S(1/2) two-photon transition in (87)Rb. We access the upper state using two dipole-allowed transitions via the intermediate 5P(3/2) state. This allows us to use much lower laser intensities compared to directly driving the two-photon transition, thereby avoiding potential errors due to the AC Stark shift. Collisional shifts are also minimized because the atomic density required is several orders of magnitude smaller. Our values are consistent with earlier frequency-comb measurements.     

AFM and electronic transport studies of swift heavy ion irradiated Mn/p-Si bilayer structure

Mn/p-Si structures have been realised by electron beam evaporation of manganese on etched and cleaned p-Si wafers. Bilayer structures have been irradiated by swift heavy ions (of 100 MeV Fe⁷⁺ having a fluence of 1 × 10¹³ ions/cm²). The electronic transport features across the bilayer of the structure (i.e. I–V characteristics across the Mn/p-Si interface) show a significant increase of current (by two orders of magnitude) for the irradiated ones as compared to un-irradiated ones. I–V characteristics across the interface has also been recorded in presence of in-plane (i.e., along the plane of the interface) magnetic field which show a significant magnetic field sensitivity for the irradiated ones. The surface morphological studies from AFM show a granular structure with open face having micro-particles in it, prior to the irradiation and round shaped embedded granular structure after the irradiation. XRD data show the formation of manganese silicide (Mn₅Si₂). The results are understood in the realm of interfacial intermixing which is tailored by the swift heavy ion irradiation.     

Certain class of generalized isotropic perturbations of thes-wave three-dimensional harmonic oscillator

In this paper we study a certain class of generalized perturbation problem for the isotropic three dimensional harmonic oscillator, forl=0 states only, for all excited states. The efficacy of our formalism is tested by studying the Killingbeck potential in detail. We also briefly present our results using the diagonal Padé approximants.     

Nondestructive evaluation of physico-mechanical properties of polypropylene copolymer by infra-red spectroscopy

We present a novel approach to nondestructive evaluation of various physico-mechanical properties of polypropylene copolymer (PPCP) by a single step measurement of infra-red spectrum followed by chemometric operation of the predetermined characteristic region of spectrum through an inbuilt software to obtain various properties/parameters i.e. average melt flow index (av. MFI), izod impact, and flexural modulus, required for quality evaluation of the copolymer. This method is simple, fast, and direct, involving only a single step measurement on the film (sample) as against the standard ASTM methods for the evaluation of these properties, which involve multi-steps and multi-instruments and are quite cumbersome. This method has been tested on a fairly large number of samples produced in a commercial plant, over a period of time and compared well with the corresponding values (properties) determined by the ASTM methods.     

An effective molecular orbital basis selection scheme to calculate resonant frequency-dependent polarizabilities and polarizability derivatives by time-dependent Hartee—Fock theory

A non-iterative method for calculating frequency-dependent polarizabilities is developed using time-dependent Hartrec—Fock theory. A simple procedure for selecting molecular orbitals and two-electron integrals in this method is proposed and shown to be effective in reducing computational effort.