Tautomerism in Salicylidene Benzylamine

The UV spectra of substituted salicylidene benzylamine schiff bases were studied in four solvents. It was found that substituents which increase the electronic effect and not the steric compression effect in these compounds increase the percentage of the keto form. The intensity (i.e. % keto) of the keto band which occurs at > 400 nm in the UV spectra increases in polar solvents.     

Development of a Dewaxing Protocol for Tissue-Engineered Models of the Oral Mucosa Used for Raman Spectroscopic Analysis

Abstract: We demonstrate that wax-embedded models of tissue-engineered oral mucosa can be effectively dewaxed using xylene for Raman spectroscopic analysis. Tissue sections of 20 μm thickness were cut and mounted onto glass slides. Sections were placed in xylene for increasing lengths from 2 to 45 min. Acquired Raman spectra revealed the wax contribution in the fingerprint region until 28-min treatment in xylene. Good quality and wax-free spectra were recorded at 30, 35, 40, and 45 min in xylene with no significant differences among them. It is essential to collect uncontaminated Raman spectra in order to achieve authentic results because the fingerprint region of biological tissues holds extremely vital information that is of diagnostic significance in cancer.     

Detection of explosives and latent fingerprint residues utilizing laser pointer–based Raman spectroscopy

A modular, compact Raman spectrometer, based on a green laser pointer, an air cooled intensified charged coupled device and a x, y motorized translation stage was developed and applied for point detection. Its performance was tested for measurements of Raman spectra of liquids, trace amounts of explosives and individual particles, as well as for locating individual particles of interest and for chemical imaging of residues of latent human fingerprints. This system was found to be highly sensitive, identifying masses as low as ~1 ng in short times. The point and real-time detection capabilities of the spectrometer, together with the portability that it offers, make it a potential candidate for replacing existing Raman microscopes and for field applications.     

Hodge Structures Associated to SU(p, 1)

Let A be an abelian variety over ? such that the semisimple part of the Hodge group of A is a product of copies of SU(p, 1) for some p > 1. We show that any effective Tate twist of a Hodge structure occurring in the cohomology of A is isomorphic to a Hodge structure in the cohomology of some abelian variety.     

An inverse source problem for a two dimensional time fractional diffusion equation with nonlocal boundary conditions

We consider the inverse source problem for a time fractional diffusion equation. The unknown source term is independent of the time variable, and the problem is considered in two dimensions. A biorthogonal system of functions consisting of two Riesz bases of the space L²[(0,1) × (0,1)], obtained from eigenfunctions and associated functions of the spectral problem and its adjoint problem, is used to represent the solution of the inverse problem. Using the properties of the biorthogonal system of functions, we show the existence and uniqueness of the solution of the inverse problem and its continuous dependence on the data. Copyright © 2012 John Wiley & Sons, Ltd.     

A Deterministic O(m \log {m}) Time Algorithm for the Reeb Graph

We present a deterministic algorithm to compute the Reeb graph of a PL real-valued function on a simplicial complex in $O(m \log {m})$ O ( m log m ) time, where $m$ m is the size of the 2-skeleton. The problem can be solved using dynamic graph connectivity. We obtain the running time by using offline graph connectivity which assumes that the deletion time of every arc inserted is known at the time of insertion. The algorithm is implemented and experimental results are given. In addition, we reduce the offline graph connectivity problem to computing the Reeb graph.     

Observation of transverse Anderson localization in an optical fiber

We utilize transverse Anderson localization as the waveguiding mechanism in optical fibers with random transverse refractive index profiles. Using experiments and numerical simulations, we show that the transverse localization results in an effective propagating beam diameter that is comparable to that of a typical index-guiding optical fiber.     

Rational development of a selection model for solvent gradients in single-step separation of ginsenosides from Panax ginseng using high-speed counter-current chromatography

A new model of solvent gradients selection was rationally developed for the preparative separation of target compounds. The solvent gradients were selected based on a three-stage screening process where stationary phase retention was ensured by introducing a new parameter termed as the phase ratio. The phase ratio was calculated after mixing the upper phase of a solvent system with the lower phase of a different solvent system (1:1, v/v). The developed model was applied to the one-step separation of eight ginsenosides from Panax ginseng. Three gradients were selected on the basis of new model and eight ginsenosides, Rb(1), Rb(2), Rc, Rd, Re, Rg(1), Rf, and Rh(1), were efficiently separated by high-speed counter-current chromatography coupled with evaporative light scattering detector. The structures of all compounds were characterized by electrospray-ionization mass spectrometry and nuclear magnetic resonance spectroscopy.     

Ixoroid: a new triterpenoid from the flowers of Ixora coccinea

A new natural terpenoid, ixoroid (1), was isolated from the flower of Ixora coccinea, along with the known constituents stigmast-5-en-3-O-beta-D-glucoside (2), 5-O-caffeoylquinic acid (3) and D-mannitol (4). The structure of ixoroid was elucidated on the basis of extensive 1D- and 2D-NMR studies and mass spectrometry as 21,23-epoxy-tirucall-7-en-3beta-ol (1).     

Seymour's Second Neighborhood Conjecture for Tournaments Missing a Generalized Star

Seymour's Second Neighborhood Conjecture asserts that every digraph (without digons) has a vertex whose first out‐neighborhood is at most as large as its second out‐neighborhood. We prove its weighted version for tournaments missing a generalized star. As a consequence the weighted version holds for tournaments missing a sun, star, or a complete graph. © 2011 Wiley Periodicals, Inc. J Graph Theory 71:89–94, 2012