HPLC determination of majdine in Vinca herbacea

A reliable HPLC method coupled with DAD detection was developed and validated for determination of majdine in Vinca herbacea. The chromatographic separation was carried out on a Symmetry C18 column (250 mm x 4.6 mm, 5 microm, Waters) with an isocratic solvent system of 25 mM potassium phosphate buffer (pH = 3.0)-acetonitrile. UV detection was performed at 225 nm. Good linear behavior over the investigated concentration range was observed with the value of r2 > 0.9978. The method was reproducible with intra- and inter-day variations of less than 4.38%. The proposed method was linear, accurate, precise and specific. The validated method was successfully applied to quantify majdine in various parts of V. herbacea, which was collected during the flowering months of April and May. The results indicated that the developed HPLC method could be used for the quality control of V. herbacea and for the standardization of its extracts in majdine.     

The asymptotic distribution of traces of Maass–Poincaré series

We establish an asymptotic formula with a power savings in the error term for traces of CM values of a family of Maass–Poincaré series which contains the modular j-function as a special case. By work of Borcherds (1998) [2], Zagier (2002) [31], and Bringmann and Ono (2007) [4], these traces are Fourier coefficients of half-integral weight weakly holomorphic modular forms and Maass forms.     

Antiplasmodial activity of three bisbenzylisoquinoline alkaloids from the tuber of Stephania rotunda

Three bisbenzylisoquinoline alkaloids were isolated for the first time from Stephania rotunda tuber. Their structures were elucidated by spectroscopic methods and their antiplasmodial activity was investigated in vitro on chloroquine resistant Plasmodium falciparum strain W2. These alkaloids were identified as 2-norcepharanthine (1), cepharanoline (2) and fangchinoline (3). In vitro, they displayed significant antiplasmodial activity with inhibitory concentration 50 values of 0.3, 0.2 and 0.3 μM.     

Nonvanishing of Hecke <Emphasis Type="Italic">L</Emphasis>-functions and the Bloch–Kato conjecture

In this paper we study the central values of L-functions associated to a large class of algebraic Hecke characters of imaginary quadratic fields. When these central values are nonzero, the Bloch–Kato conjecture predicts an exact formula for the algebraic parts of the central values in terms of periods and arithmetic data, most notably the Selmer groups corresponding to the Hecke characters. We investigate the nonvanishing of these central values, and prove the p-part of the Bloch–Kato conjecture in these cases for primes p which split in K.     

Guided mode resonance in subwavelength metallodielectric free-standing grating for bandpass filtering

We present the experimental study of a free-standing metallic guided-mode resonant structure, for bandpass filtering applications in the mid-IR wavelength range. Structure consists of a subwavelength gold grating with narrow slits deposited on a silicon nitride membrane. High optical transmission is measured with up to 78% transmission at resonance. Angularly resolved spectra are presented revealing Fano-type resonance.     

Determination of Fluoroquinolone Antibiotics in Industrial Wastewater by High-Pressure Liquid Chromatography and Thin-Layer Chromatography—Densitometric Methods

JPC – Journal of Planar Chromatography – Modern TLC - Two methods were described for the simultaneous determination of ciprofloxacin HCl (CIP) and moxifloxacin HCl (MOX) in their binary...     

Simultaneous Determination of Sulphadiazine Sodium and Trimethoprim in Medicated Fish Feed,Fish Tissues and in Their Veterinary Pharmaceutical Formulation by Thin-Layer Chromatography—Densitometry

JPC – Journal of Planar Chromatography – Modern TLC - A specific, precise, and accurate thin-layer chromatographic method for the simultaneous estimation of sulphadiazine sodium (SDZ)...     

Reduced scattering-matrix algorithm for high-density plasmonic structures

We describe a method to compute S-matrix interface terms using a selection of eigenmodes. When solving the modal equation, the computation of left and right eigenvectors leads to rectangular eigenmodes matrices. Expressions of S-matrix interface terms are then expressed so as to allow for a significant reduction of the computation cost. The reduction is even further decreased in the case of the B-spline modal method, which deals with sparse matrices. Its convergence is illustrated on a high-density plasmonic structure and compared to a full modal method.