Gel growth of α and γ glycine and their characterization

The microbial free single crystals of α and γ glycine were grown from gel at room temperature in a new chemical route. These crystals showed a superior quality than the solution grown crystals. The metastable α-form and the stable γ-form of glycine were crystallized in silica gel by solubility reduction method. The form of crystallization is confirmed by single crystal and powder X-ray diffraction analyses. The crystals of α and γ glycine were found to crystallize in monoclinic and hexagonal crystal systems, respectively. For analyzing the functional group and thermal stability of α and γ glycine crystals, spectroscopic and thermal analyses have been carried out. The dielectric studies were performed to find the dielectric constant of the grown crystals and the results are discussed. Second harmonic generation efficiency of the crystal was measured by Kurtz’s powder method using Nd:YAG laser and it was found to be 2.68 times that of potassium dihydrogen phosphate crystals.     

Computing Cartograms with Optimal Complexity

In a rectilinear dual of a planar graph vertices are represented by simple rectilinear polygons, while edges are represented by side-contact between the corresponding polygons. A rectilinear dual is called a cartogram if the area of each region is equal to a pre-specified weight. The complexity of a cartogram is determined by the maximum number of corners (or sides) required for any polygon. In a series of papers the polygonal complexity of such representations for maximal planar graphs has been reduced from the initial 40 to 34, then to 12 and very recently to the currently best known 10. Here we describe a construction with 8-sided polygons, which is optimal in terms of polygonal complexity as 8-sided polygons are sometimes necessary. Specifically, we show how to compute the combinatorial structure and how to refine it into an area-universal rectangular layout in linear time. The exact cartogram can be computed from the area-universal layout with numerical iteration, or can be approximated with a hill-climbing heuristic. We also describe an alternative construction of cartograms for Hamiltonian maximal planar graphs, which allows us to directly compute the cartograms in linear time. Moreover, we prove that even for Hamiltonian graphs 8-sided rectilinear polygons are necessary, by constructing a non-trivial lower bound example. The complexity of the cartograms can be reduced to 6 if the Hamiltonian path has the extra property that it is one-legged, as in outer-planar graphs. Thus, we have optimal representations (in terms of both polygonal complexity and running time) for Hamiltonian maximal planar and maximal outer-planar graphs. Finally we address the problem of constructing small-complexity cartograms for 4-connected graphs (which are Hamiltonian). We first disprove a conjecture, posed by two set of authors, that any 4-connected maximal planar graph has a one-legged Hamiltonian cycle, thereby invalidating an attempt to achieve a polygonal complexity 6 in cartograms for this graph class. We also prove that it is NP-hard to decide whether a given 4-connected plane graph admits a cartogram with respect to a given weight function.     

Effects of bi-kappa distributed electrons on dust-ion-acoustic shock waves in dusty superthermal plasmas

The basic properties of dust-ion-acoustic （DIA） shock waves in an unmagnetized dusty plasma （containing inertial ions, kappa distributed electrons with two distinct temperatures, and negatively charged immobile dust grains） are investi- gated both numerically and analytically. The hydrodynamic equation for inertial ions has been used to derive the Burgers equation. The effects of superthermal bi-kappa electrons and ion kinematic viscosity, which are found to modify the basic features of DIA shock waves significantly, are briefly discussed.     

Electron impact ionisation cross section for organoplatinum compounds

This article reports electron impact ionisation cross sections for platinum-based drugs viz., cisplatin (H₆N₂Cl₂Pt), carboplatin (C₆H₁₂N₂O₄Pt), oxaliplatin (C₈H₁₄N₂O₄Pt), nedaplatin (C₂H₈N₂O₃Pt) and satraplatin (C₁₀H₂₂ClN₂O₄Pt) complexes used in the cancer chemotherapy. The multi-scattering centre spherical complex optical potential formalism is used to obtain the inelastic cross section for these large molecules upon electron impact. The ionisation cross section is derived from the inelastic cross section employing complex scattering potential–ionisation contribution method. Comparison is made with previous results, where ever available and overall a reasonable agreement is observed. This is the first attempt to report total ionisation cross sections for nedaplatin and satraplatin complexes.     

(1)H-(13)C INEPT MAS NMR correlation experiments with (1)H-(1)H mediated magnetization exchange to probe organization in lipid biomembranes

Two-dimensional (1)H-(13)C INEPT MAS NMR experiments utilizing a (1)H-(1)H magnetization exchange mixing period are presented for characterization of lipid systems. The introduction of the exchange period allows for structural information to be obtained via (1)H-(1)H dipolar couplings but with (13)C chemical shift resolution. It is shown that utilizing a RFDR recoupling sequence with short mixing times in place of the more standard NOE cross-relaxation for magnetization exchange during the mixing period allowed for the identification and separation of close (1)H-(1)H dipolar contacts versus longer-range inter-molecular (1)H-(1)H dipolar cross-relaxation. These 2D INEPT experiments were used to address both intra- and inter-molecular contacts in lipid and lipid/cholesterol mixtures.     

Sonochemical synthesis, photocatalytic activity and optical properties of silica coated ZnO nanoparticles

In this paper, we report the synthesis of silica coated ZnO nanoparticles by ultrasound irradiation of a mixture of dispersion of ZnO, tetraethoxysilane (TEOS), and ammonia in an ethanol-water solution medium. The silica coating layer formed at the initial TEOS/ZnO loading of 0.8 for 60 min ultrasonic irradiation was uniform and extended up to 3 nm from the ZnO surface as revealed from HR-TEM images. Silica coated ZnO nanoparticles demonstrated a significant inhibition of photocatalytic activity against photodegradation of methylene blue dye in aqueous solution. The effects of silica coating on the UV blocking property of ZnO nanoparticles were also studied.     

In situ Raman monitoring of materials under irradiation: study of uranium dioxide alteration by water radiolysis

In situ Raman scattering studies allow following real‐time evolutions of volume or surface structures under extreme conditions. In nuclear materials sciences, ion irradiation‐induced atomic organization modification and water radiolysis are of a major interest. In order to better understand these phenomena, we have developed an in situ versatile portable Raman spectroscopy system coupled with a cyclotron accelerator, allowing monitoring of a solid/liquid interface under irradiation and thus giving access to effects of radiolysis. The different parts of the system and their improvements are described in details. The system efficiency is highlighted by a comparative study of the time dependence of UO₂ surface modification induced, on one hand by contact with water under irradiation by 5 MeV He²⁺ particles, and on the other hand by pure chemical alteration, through contact with a hydrogen peroxide solution. Copyright © 2012 John Wiley & Sons, Ltd.     

Search for Down-Type Fourth Generation Quarks with the ATLAS Detector in Events with One Lepton and Hadronically Decaying W Bosons

This Letter presents a search for pair production of heavy down-type quarks decaying via b^{'}→Wt in the lepton+jets channel, as b^{'}b[over ˉ]^{'}→W^{-}tW^{+}t[over ˉ]→bb[over ˉ]W^{+}W^{-}W^{+}W^{-}→l^{±}νbb[over ˉ]qq[over ˉ]qq[over ˉ]qq[over ˉ]. In addition to requiring exactly one lepton, large missing transverse momentum, and at least six jets, the invariant mass of nearby jet pairs is used to identify high transverse momentum W bosons. In data corresponding to an integrated luminosity of 1.04 fb^{-1} from pp collisions at sqrt[s]=7 TeV recorded with the ATLAS detector, a heavy down-type quark with mass less than 480?GeV can be excluded at the 95% confidence level.     

Compact and silicon-on-insulator-compatible hybrid plasmonic TE-pass polarizer

Hybrid plasmonic waveguides consisting of a metal plane separated from a high-index medium by a low-index spacer have recently attracted much interest. Here we show that, by suitably choosing the dimensions and material properties of the hybrid waveguide, a very compact and broadband TE-pass polarizer can be implemented. Finite-difference time-domain simulation indicates that the proposed device can provide large extinction ratio with low insertion loss for the TE mode.