Some N¬-acyl-N'-aryl thiourea derivatives 4(a-f) have been prepared by the reaction of acyl halides ammonium thiocyanate and aryl amines. The structures of synthesized compounds have been characterized by IR, 1HNMR spectral studies. The synthesized compounds 5(a-f) have been screened for antibacterial activity. The effect of the structure of the investigated compounds on the antibacterial activ...

Optical material properties have been studied in a wide wavelength range. The aim is future use of spectral design for camouflage. The main characterization techniques used in this work are Reflection Spectroscopy, Scatterometry (BRDF) and Mueller Matrix Ellipsometry. Six camouflage evaluation criteria based on reflection, emissivity, polarization, gloss, dynamic coloring and broad band propert...

Let A = ( H1 E ∗ E H2 ) and à = ( H1 O O H2 ) be Hermitian matrices with eigenvalues λ1 ≥ · · · ≥ λk and λ̃1 ≥ · · · ≥ λ̃k, respectively. Denote by ‖E‖ the spectral norm of the matrix E, and η the spectral gap between the spectra of H1 and H2. It is shown that |λi − λ̃i| ≤ 2‖E‖ η + √ η2 + 4‖E‖2 , which improves all the existing results. Similar bounds are obtained for singular values of matrices u...

The interaction of concanavalin A, the phytohemagglutinin of the jack bean, with a variety of glycosides has been studied by the technique of ultraviolet difference spectroscopy. Whereas methyl a-D-glUC0and manno-pyranoside gave rise to relatively low intensity difference spectra, p-nitrophenyl a-D-mannopyranoside and a-D-glucopyranoside yielded large difference spectra upon interaction with co...

Four new minor diterpene glycosides with a rare α-glucosyl linkage were isolated from a cyclodextrin glycosyltransferase glucosylated stevia extract containing more than 98% steviol glycosides. The new compounds were identified as 13-[(2-O-β-D-glucopyranosyl-3-O-(4-O-α-D-glucopyranosyl)-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-[(4-O-α-D-glucopyranosyl-β-D-glucopyran...

Measurements of polarization-dependent soft x-ray absorption reveal that the electronic states determining the low-energy excitations of NaxCoO2 have predominantly a(1g) symmetry with significant O 2p character. In contrast to the prediction of band theory, doping-dependent O 1s x-ray absorption shows a large transfer of spectral weight, providing spectral evidence for strong electron correlati...

We consider the numerical solution of an unsteady convection-diffusion equation using high order polynomial approximations both in space and time. General boundary conditions and initial conditions can be imposed. The method is fully implicit and enjoys exponential convergence in time and space for analytic solutions. This is confirmed by numerical experiments (in one space dimension) using a s...

This paper considers the problem of estimating the spectrum of real-valued signals. We propose real-valued versions of the Capon and the APES spectral estimators. The estimators are derived as members of the Matched-Filterbank (MAFI) estimator class as introduced in [1]. Furthermore, we show that the real-valued estimators will be unbiased, whereas the complex-valued estimators will have a (sli...

We show that Laplacian and symmetric diagonally dominant (SDD) matrices can be well approximated by linear-sized sparse Cholesky factorizations. Specifically, n × n matrices of these types have constant-factor approximations of the form LL , where L is a lowertriangular matrix with O(n) non-zero entries. This factorization allows us to solve linear systems in such matrices in O(n) work and O(lo...