Anisotropic magnetotransport near the quantum Hall state

We report experimental results on an anisotropic magnetotransport of a bilayer electron system at the Landau level filling factor under tilted magnetic fields. We find that the magnetoresistance changes when the direction of applied in-plane field B is changed with respect to the direction of the current while keeping the strength of B fixed. This anisotropy only appears at the ground state where interlayer electron tunneling is permitted. Therefore, this phenomenon indicates that bilayer systems at with interlayer tunneling inherently have a dissipation mechanism related to the direction of the in-plane field.     

Green synthesis of silver nanoparticles using green alga (Chlorella vulgaris) and its application for synthesis of quinolines derivatives

Nanoparticles have been used century ago but have regained their importance in recent years being simple, ecofriendly, pollutant free, nontoxic, low-cost approach, and due good atom economy. In this report, we have demonstrated the synthesis of silver nanoparticles using green algae (Chlorella vulgaris) which in turn was used for synthesis of biologically important quinolines. Algal extract was prepared and treated with silver nitrate solution for the synthesis of silver nanoparticles. Synthesized nanoparticles were characterized with the help of analytical tools like UV, FTIR, X-ray, and SEM and used as a catalyst for the synthesis of quinolines.     

Novel bio compactable silver nanowires and nanocubes: An effective treatment against carbapenem and vancomycin resistant strains isolated from cancer patients

Blood stream infections in the cancer patients are a critical problem which leads to considerable rate of mortality and morbidity. In view of this herein, we account the response of Poly Vinyl Pyrrolidone (PVP) coated silver nanowires (Ag-NWs) and silver nano cubes (Ag-NCs) towards carbapenem (Escherichia coli) and vancomycin (Staphylococcus aureus) resistant strains as well as to human epithelial cells. The prepared PVP capped silver nanomaterials were in the range of 80 nm (Ag-NC) and 25 nm (Ag-NW) as observed from Transmission Electron Microscopy (TEM). Though the selected strains were resistant to carbapenem and vancomycin, PVP capped Ag-NWs and Ag-NCs could inhibit the growth of these strains. These nanomaterials could break the cell wall and damage the genetic material of these strains as observed by death rate assay and alkaline comet assay. Furthermore, we have shown that toxicity of Ag-NWs and Ag-NCs precisely follows the dose retort pattern. Even though the resistant strains were susceptible to a concentration of 10 µg ml^?1 of silver nanomaterials the epithelial cells were not affected by the same concentration. It is also confirmed with live dead staining assay and observed that metabolic activities of epithelial cells were not affected by a concentration of 10 µg ml^?1. Overall, this work suggests that these nanomaterials can be utilized to treat the multiple drug resistant strains from cancer patients.     

Total cross-sections for electron scattering from iron at 10–5000 eV using a model optical potential

We report calculations on the total (elastic plus inelastic) electron-scattering cross sections in the energy range 10–5000 eV. A model complex optical potential, composed of static, exchange, polarisation and absorption terms, is employed to describe the collision system at each electron energy. The Iron atom is described by Dirac-Hartree-Fock-Slater self-consistent charge density. The complex phase shifts are computed in a variable phase approach. The absorption cross sections are compared with the experimental results. The experimental absorption cross sections are obtained by adding the experimental ionisation cross sections and available experimental excitation cross sections for electron impact of the allowed transitions a⁵ D → (x,y,z)⁵ D ⁰, (w,y,z)⁵ P ⁰. We have good qualitative agreement between our results and the experimental results available below 200 eV. The Born-Bethe parameters are also calculated. Elastic differential cross-sections with and without absorption are also reported at a few selected energies.     

Deracemisation of aryl substituted α-hydroxy esters using Candida parapsilosis ATCC 7330: effect of substrate structure and mechanism

Candida parapsilosis ATCC 7330 was found to be an efficient biocatalyst for the deracemisation of aryl α-hydroxy esters (65–85% yield and 90–99% ee). A variety of aryl and aryl substituted α-hydroxy esters were synthesized to reflect steric and electronic effects on biocatalytic deracemisation. The mechanism of this biocatalytic deracemisation was found to be stereoinversion.     

Synthesis, characterization and antitumour studies on N-salicyl-N′-thiobenzohydrazide and its copper(II) complex

Summary The new potential tetradentate ligand N-salicyl-N-thiobenzohydrazide (H₂SBTH) and its Cu complex, [Cu(SBTH)], have been prepared and characterized by physico-chemical studies. In vivo antitumour activity of [Cu(SBTH)] has been tested against breast tumour in C₃H/J strain mice; LD ₅₀ values were also calculated. The cytotoxicity and antitumour effect of [Cu(SBTH)] is a maximum at 100 mg kg^-1 body weight injected intraperitoneally in mice carrying breast tumour. In vitro results of the ligand and the complex on P-815 (murine mastocytoma) and K-562 (human erythroleukemia cells) indicate that these compounds show significant inhibition on ³H-thymidine and ³H-uridine incorporation in DNA and RNA in these tumour cells. Light microscopic study of the treated tumour mass demonstrated that certain cellular degradation, such as disappearance of mitotic figures, loss in cellular compactness, distortion of nucleus and disruption of cytoplasmic boundaries, take place in complex-treated mice with tumours.     

Decoration of discretely immobilized cowpea mosaic virus with luminescent quantum dots

This report describes two related methods for decorating cowpea mosaic virus (CPMV) with luminescent semiconductor nanocrystals (quantum dots, QDs). Variants of CPMV are immobilized on a substrate functionalized with NeutrAvidin using modifications of biotin-avidin binding chemistry in combination with metal affinity coordination. For example, using CPMV mutants expressing available 6-histidine sequences inserted at loops on the viral coat protein, we show that these virus particles can be specifically immobilized on NeutrAvidin functionalized substrates in a controlled fashion via metal-affinity coordination. To accomplish this, a hetero-bifunctional biotin-NTA moiety, activated with nickel, is used as the linker for surface immobilization of CPMV (bridging the CPMVs' histidines to the NeutrAvidin). Two linking chemistries are then employed to achieve CPMV decoration with hydrophilic CdSe-ZnS core-shell QDs; they target the histidine or lysine residues on the exterior virus surface and utilize biotin-avidin interactions. In the first scheme, QDs are immobilized on the surface-tethered CPMV via electrostatic attachment to avidin previously bound to the virus particle. In the second strategy, the lysine residues common to each viral surface asymmetric unit are chemically functionalized with biotin groups and the biotinylated CPMV is discretely immobilized onto the substrate via NeutrAvidin-biotin interactions. The biotin units on the upper exposed surface of the immobilized CPMV then serve as capture sites for QDs conjugated with a mixture of avidin and a second protein, maltose binding protein, which is also used for QD-protein conjugate purification. Characterization of the assembled CPMV and QD structures is presented, and the potential uses for protein-coated QDs functionalized onto this symmetrical virion nanoscaffold are discussed.     

Dielectric Response of Bi4Ti3O12/PVDF Composite Electrodes for Energy Storage

This study is reporting the role of embedded ferroelectric ceramics Bi₄Ti₃O₁₂ (BTO = 1–5 wt%) into the polyvinylidene fluoride (PVDF) composites on its structural, bonding, surface morphology, and dielectric response. Especially lead free flexible composite electrodes have lot of attention due to its high dielectric permittivity and energy storage density. X-ray diffraction spectra confirms monophasic orthorhombic structure of composites, while Fourier transform infrared (FTIR) spectra confirms the bonding behavior. Scanning electron microscopy (SEM) images surface morphology of homogeneously distributed ceramic particles with interconnected network. Dielectric constant has been found to be improved from 9.56 to 13.73 for BTO_5%PVDF_95% composites at frequency of 1 kHz attributes promoted interfacial polarization of PVDF and effectively limited the charge leakage in the composites, implying promising applications in flexible electronic devices.     

Uranyl ion luminescence quenching with benzene derivatives and related compounds. Linear free energy relationship

Irradiation of uranyl ion with light of wavelength =345 nm to singlet state, through vibrational relaxation populates the lowest excited triplet state from where it emits luminescence emission at 486, 506, 535 nm. Elongation and weakening of uranium-oxygen multiple bonds is evident from the lower stretching frequency (701.15 cm^–1) in the excited state relative to the ground state (942.5 cm^–1). Series of aromatic molecules including benzene derivatives, aromatic hydrocarbons and heterocyclic molecules very efficiently quench uranyl ion luminescence through nonradiative donor-acceptor complex formation. Increasing inductive effect, resonance phenomena and extension of aromatic -electron cloud determine the order of Stern-Volmer constant to measure their quenching action.     

Studies of effect of heterocyclic dyes in photogalvanic cells for solar energy conversion and storage: NaLS-ascorbic acid system

The photogalvanic effect has been studied in three systems using photogalvanic cells and NaLS-ascorbic acid-azur A, NaLS-ascorbic acid-azur B, NaLS-ascorbic acid-azur C systems. The photopotential and photocurrent generated by these systems are 7700, 9710, 623·0 mV and 160·0, 185·0, 145·0 (μA respectively. The effects of different parameters on the electrical outputs of the cell have been observed and current-voltage characteristics of the cell studied, and a mechanism has been proposed for the generation of photocurrent in photogalvanic cells. The conversion efficiencies for azur A, azur B and azur C are 0·5461, 0·9646 and 0·4567% and storage capacity 110, 135 and 95 min respectively.