Synthesis,spectral investigation and biological interphase of drug‐based cytotoxic square pyramidal coordination compounds

We have synthesized ciprofloxacin‐based metal complexes of bipyridine derivatives [Cu(CFL)(Aⁿ)Cl].2H₂O (where CFL = ciprofloxacin and A = bipyridines e.g. A¹ = 4‐(4‐fluorophenyl)‐6‐p‐tolyl‐2,2′‐bipyridine, A⁶ = 4‐(4‐(benzyloxy)phenyl)‐6‐(4‐bromophenyl)‐2,2′‐bipyridine, etc.). The ligands and complexes were characterized using analytical (C, H, N elemental analysis, TGA and magnetic measurement) and spectroscopic methods (¹H and ¹³C NMR, FT‐IR, fast atom bombardment mass and reflectance spectroscopy). The products were evaluated by screening for DNA interaction activity on herring sperm DNA and studies suggest intercalative mode of DNA binding. The antimicrobial activity was determined in terms of minimum inhibitory concentration. Superoxide dismutase mimic studies were performed using the NADH/PMS/NBT system. The brine shrimp bioassay was also carried out to study the in vitro cytotoxic properties of the synthesized metal complexes. Copyright © 2012 John Wiley & Sons, Ltd.     

Generation of surface-voltage by charged crystal defects and applications

Abstract

Working mainly on quartz crystals it has been found that crystal defects present inherently or generated deliberately on the surface and in the bulk give rise to surface voltage (called by us self-voltage) due to charged electron and hole traps produced by the defects, the self-voltage thus forming monitor of presenceof crystal defects. The self-voltage could be measured by FET instrumentation.

Based on the above the crystal defects (and hence self-voltage) were reduced or practically eleminated by combination of processes of etching and annealing of the quartz, allthis reseulting in improvements of electronic characteristics of quartz crystals such as resistivity and frequency stability.     

Synthesis,Spectral Characterization,and Antimicrobial Evaluation of N,N′-(1,4-Phenylene)diurea Derivatives

Russian Journal of Organic Chemistry - A series of new 1,1′-(1,4-phenylene)diurea derivatives were synthesized by reacting 1,4-diiso­cyanato­benzene with various biologically...     

p-almost Hadamard matrices and $$\lambda $$ λ -planes

Journal of Algebraic Combinatorics - In this work, we consider the p-almost Hadamard matrices and discuss about its connection with the orthogonal matrices corresponding to the finite projective...     

Synthesis and Supramolecular Studies of Chiral Boronated Platinum(II) Complexes: Insights into the Molecular Recognition of Carboranes by β‐Cyclodextrin

The synthesis and characterisation of a novel isomeric family of closo‐carborane‐containing Pt^II complexes ((R/S)‐( 1 – 4 )?2 NO₃) are reported. Related complexes ( 5 ?NO₃ and 6 ?NO₃) that contain the 7,8‐nido‐carborane cluster were obtained from the selective deboronation of the 1,2‐closo‐carborane analogues. The corresponding water‐soluble supramolecular 1:1 host–guest β‐cyclodextrin (β‐CD) adducts ((R/S)‐( 1 – 4 ) ? β‐CD?2 NO₃) were also prepared and fully characterised. HR‐ESI‐MS experiments confirmed the presence of the host–guest adducts, and 2D‐¹H{¹¹B} ROESY NMR studies showed that the boron clusters enter the β‐CD from the side of the wider annulus. Isothermal titration calorimetry (ITC) experiments revealed enthalpically driven 1:1 and higher‐order supramolecular interactions between β‐CD and (R/S)‐( 1 – 4 )?2 NO₃ in aqueous solution. A comparison of the predominate 1:1 binding mode established that the affinity of β‐CD for the guest molecule is mainly influenced by the pyridyl ring substitution pattern and chirality of the host, whilst the nature of the closo‐carborane isomer also plays some role, with the most favourable structural features for β‐CD binding being the presence of the 4‐pyridyl ring, 1,12‐closo‐carborane, and an S configuration. The results reported here represent the first comprehensive calorimetric study of the supramolecular interactions between closo‐carborane compounds and β‐CD, and it provides fascinating insights into the structural features influencing the thermodynamics of this phenomenon.     

Enhanced vacuum-photoconductivity of chemically synthesized ZnO nanostructures

We report on the enhanced ultraviolet (UV) photoconductivity of zinc oxide (ZnO) nanostructures in vacuum. Nanoparticles and nanorods of ZnO were fabricated using a simple cost-effective solid state grinding method. Morphology of the nanostructures was studied using transmission electron microscopy, while the optical properties were investigated using UV–visible absorption and photoluminescence spectroscopy. The emission spectra of the nanostructures revealed the existence of various native defect states of ZnO and also indicated the presence of surface adsorbed water molecules. In the photoconductivity measurements, although the ZnO nanoparticles exhibited lower photoconductivity in comparison to the nanorods, a similar trend of photoresponse was observed for both the cases. An initial decrease in the photoconductivity followed by a large enhancement was observed in vacuum compared to that in ambient condition. Such unusually increased photoconductivity has been correlated to the desorption of physisorbed water molecules from nanostructure surfaces under vacuum. This desorption is responsible for the rise in dark current and an initial decrease in photoconductivity. Continual UV irradiation in vacuum leads to the desorption of chemisorbed water molecules from the defect sites of the nanostructures, resulting in the occurrence of high photoconductivity.     

Hilbert scheme components in characteristic 2

We study the deformations of restrictions to P ₃ and P ₄ of Tango's rank 2 bundle on P ₅ (which exists in characteristic 2). Using this, we construct an example of a family of rank two bundles on P ₃ (in characteristic 2) with changing α-invariant and an example of a component of the Hilbert scheme of smooth surfaces in P ₄ which exists in characteristic 2 but not in anv other characteristic.     

Pyrophoricity of nano-sized aluminum particles

The temperature histories are calculated for spherical nano-sized aluminum particles with no protective oxide shell inserted in air at 300 K. In calculations, initial particle temperatures varied and the minimum initial temperature leading to the particle ignition was determined. The particle, initially without any oxide coating, was assumed to react adiabatically forming a monomolecular oxide coverage; the following oxidation was assumed to be governed by the Cabrera–Mott reaction mechanism. Convection and radiation heat losses were considered. Convection was accounted for using a transition regime heat transfer model by Fuchs. Aluminum particles with diameters less than about 68 nm are predicted to be pyrophoric, e.g., ignite without appreciable initial pre-heating.     

Wavelength Converter Using Semiconductor Optical Amplifier Mach-Zehnder Interferometer Based on XPM at 40 Gb/s for Future Transport Networks

Abstract

We have simulated, for the first time, wavelength converter for future broadcast networks at 40 Gb/s using low-cost semiconductor optical amplifiers. The performance analysis is carried out for an all-optical frequency converter based on cross-phase modulation in two semiconductor optical amplifiers arranged in a Mach-Zehnder interferometer configuration to evaluate the efficiency of conversion. The results, evaluated analytically for input, return to zero signal at a bit rate of 40 Gb/s show that conversion is possible over a wavelength separation of 1 nm between the pump and the input wavelength. Increasing the driving current can decrease the cross-phase modulation effect. The cross gain modulation scheme shows extinction ratio degradation for conversion to longer wavelengths.