Synthesis of α-diazo-β-hydroxy esters using nanocrystalline MgO

Nanocrystalline magnesium oxide (NAP-MgO) has been found to be an effective heterogeneous, solid base catalyst for the direct aldol type reaction of ethyl diazoacetate and various aldehydes to afford the corresponding α-diazo-β-hydroxy esters in excellent yields with high selectivity under mild conditions.     

Orthogonal polynomial approach to discrete Lax pairs for initial boundary-value problems of the QD algorithm

Using orthogonal polynomial theory, we construct the Lax pair for the quotient-difference algorithm in the natural Rutishauser variables. We start by considering the family of orthogonal polynomials corresponding to a given linear form. Shifts on the linear form give rise to adjacent families. A compatible set of linear problems is made up from two relations connecting adjacent and original polynomials. Lax pairs for several initial boundary-value problems are derived and we recover the discrete-time Toda chain equations of Hirota and of Suris. This approach allows us to derive a Bäcklund transform that relates these two different discrete-time Toda systems. We also show that they yield the same bilinear equation up to a gauge transformation. The singularity confinement property is discussed as well.     

Schlesinger Transformations for Linearisable Equations

A simple axiomatic characterization of the noncommutative Itô algebra is given and a pseudo-Euclidean fundamental representation for such algebra is described. It is proved that every Itô algebra with a quotient identity has a faithful representation in a Minkowski space and is canonically decomposed into the orthogonal sum of quantum Brownian (Wiener) algebra and quantum Lévy (Poisson) algebra. In particular, every quantum thermal noise of a finite number of degrees of freedom is the orthogonal sum of a quantum Wiener noise and a quantum Poisson noise as it is stated by the Lévy–Khinchin Theorem in the classical case. Two basic examples of noncommutative Itô finite group algebras are considered.     

Simplified analytical expressions for classical turning points of molecular oscillators

Simplified analytical expressions for classical turning ppoints (r_1,2) are derived by expanding the empirical potential function of Dunham and Morse in series forms. These expressions are equivalent to those obtained by Rees when the energy (E) is quadratic in the vibrational quantum number. Our first approximation approach is also found to be equivalent to Jarmain's factor f/r_e.     

Frequency distribution function and critical points for phonons in graphite

A molecular force field for the study of the dynamics of graphite has been reported earlier (Mani and Ramani 1974). In the present paper we present calculations of the single phonon density of states and the lattice specific heat. Most of the peaks in the frequency distribution function have been identified and classified using symmetry-required critical points. The validity of the force field used has also been discussed.     

Computation of scattering from N spheres using multipole reexpansion

A computational technique for the solution of problems of wave scattering from multiple spheres is developed. This technique, based on the T-matrix method, uses the theory for the translation and reexpansion of multipole solutions of the Helmholtz equation for fast and exact recursive computation of the matrix elements. The spheres can have prescribed radii, impedances, and locations. Results are validated by comparison with boundary element calculations, and by convergence analyses. The method is much faster than numerical methods based on discretization of space, or of the sphere surfaces. An even faster method is presented for the case when the spheres are aligned coaxially.     

Bacterial cellulose-reinforced hydroxyapatite functionalized graphene oxide: a potential osteoinductive composite

Bacterial cellulose (BC) is a nanofibrous biocompatible scaffold used in bone tissue engineering. Graphene oxide/hydroxyapatite (GOHA) composite supports the adhesion of osteoblast cells with good viability. In the present study, GOHA was prepared by the wet chemical precipitation method, and BC obtained from Acetobacter aceti was added to the aqueous suspension of GOHA to prepare GOHABC. The scanning electron microscopic image of GOHABC showed uniform adsorption of GOHA on the surface of BC. The osteoinductive potential of the GOHABC scaffold was analyzed by alkaline phosphatase (ALP) activity assay using MG-63 cells, and its biocompatibility nature was studied by using both MG-63 and NIH-3T3 cells. The ALP activity and biocompatibility studies showed that GOHABC is a potential osteoinductive material in vitro and may be tried in the future for in vivo studies.     

Biowaste-Derived,Highly Efficient,Reusable Carbon Nanospheres for Speedy Removal of Organic Dyes from Aqueous Solutions

The current work explores the adsorptive efficiency of carbon nanospheres (CNSs) derived from oil palm leaves (OPL) that are a source of biowaste. CNSs were synthesized at 400, 600, 800 and 1000 °C, and those obtained at 1000 °C demonstrated maximum removal efficiency of ~91% for malachite green (MG). Physicochemical and microscopic characteristics were analysed by FESEM, TEM, FTIR, Raman, TGA and XPS studies. The presence of surface oxygen sites and the porosity of CNSs synergistically influenced the speed of removal of MG, brilliant green (BG) and Congo red (CR) dyes. With a minimal adsorbent dosage (1 mg) and minimum contact time (10 min), and under different pH conditions, adsorption was efficient and cost-effective (nearly 99, 91 and 88% for BG, MG and CR, respectively). The maximum adsorption capacities of OPL-based CNSs for BG were 500 and 104.16 mg/g for MG and 25.77 mg/g for CR. Adsorption isotherms (Freundlich, Langmuir and Temkin) and kinetics models (pseudo-first-order, pseudo-second-order and Elovich) for the adsorption processes of all three dyes on the CNSs were explored in detail. BG and CR adsorption the Freundlich isotherm best, while MG showed a best fit to the Temkin model. Adsorption kinetics of all three dyes followed a pseudo-second-order model. A reusability study was conducted to evaluate the effectiveness of CNSs in removing the MG dye and showed ~92% efficiency even after several cycles. Highly efficient CNSs with surface oxygen groups and speedy removal of organic dyes within 10 min by CNSs are highlighted in this paper.     

Preliminary investigations on the antibacterial activity of zinc oxide nanostructures

We have fabricated electroactive multilayer thin films containing ferritin protein cages. The multilayer thin films were prepared on a solid substrate by the alternate electrostatic adsorption of (apo)ferritin and poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide) (NIPAAm-co-CIPAAm) in pH 3.5 acetate buffer solution. The assembly process was monitored using a quartz crystal microbalance. The (apo)ferritin/poly(NIPAAm-co-CIPAAm) multilayer thin films were then cross-linked using a water-soluble carbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide. The cross-linked films were stable under a variety of conditions. The surface morphology and thickness of the multilayer thin films were characterized by atomic force microscopy, and the ferritin iron cores were observed by scanning electron microscopy to confirm the assembly mechanism. Cyclic voltammetry measurements showed different electrochemical properties for the cross-linked ferritin and apoferritin multilayer thin films, and the effect of stability of the multilayer film on its electrochemical properties was also examined. Our method for constructing multilayer films containing protein cages is expected to be useful in building more complex functional inorganic nanostructures.