Crystal structures of 2‐ chloro cinnamoyl phenolate (I) and 3‐chloro cinnamanilide (II)

The title compounds (I) and (II) crystallize in the monoclinic space group P2₁/c and orthorhombic space group Pbca respectively. The inter‐planar angle between the two phenyl rings are 55° in I and 24.5(1)° in II. The molecular packing of the compounds I and II are stabilized by C‐H…O and C‐H…π, and N‐H…O, C‐H…O and C‐H…π interactions, respectively. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal Structure of 2‐methyl cinnamanilide and 2‐methoxy cinnamanilide

The crystal structures of two cinnamanilide derivatives 2‐methyl cinnamanilide (C₁₆ H₁₅ N O – compound I) and 2‐methoxy cinnamanilide (C₁₆ H₁₅ N O₂ – compound II) are reported. In both crystal structures, the cinnamamide group is almost planar. The inter‐planar angle between the two phenyl rings are 71.6(1)° for compound I and 7.5(1)° for compound II. The N‐H…O and C‐H…O type of hydrogen bond interactions between the amide group and the carbonyl group stabilizes the molecular packing as chains in the crystal lattice.     

Preparative solid state chemistry. Recent developments

A survey of recent developments in preparative solid state chemistry shows that, with a knowledge of structural chemistry and reactivity patterns of solids, it is possible to synthesize a variety of new solids possessing novel structures. A distinction is made between synthesis ofnew solids and synthesis of solids bynew methods. Three new routes to solid state synthesis are recognized: the precursor method, and topochemical methods involving redox and ion-exchange reactions. The low-temperature topochemical methods enable synthesis of metastable phases that are inaccessible by the high temperature route. Several illustrative examples of solid state synthesis from the recent literature are presented.     

A lognormal approximation of activity duration in PERT using two time estimates

The success behind effective project management lies in estimating the time for individual activities. In many cases, these activity times are non-deterministic. In such situations, the conventional method (project evaluation and review technique (PERT)) obtains three time estimates, which are then used to calculate the expected time. In practice, it is often difficult to get three accurate time estimates. A recent paper suggests using just two time estimates and an approximation of the normal distribution to obtain the expected time and variance for that activity. In this paper, we propose an alternate method that uses only two bits of information: the most-likely and either the optimistic or the pessimistic time. We use a lognormal approximation and experimental results to show that our method is not only better than the normal approximation, but also better than the conventional method when the underlying activity distributions are moderately or heavily right skewed.     

Simultaneous K plus L shell ionized atoms during heavy-ion collision process

The fraction of simultaneous K plus L shell ionized atoms is estimated in Fe, Co and Cu elements using carbon ions at different projectile energies. The present results indicate that the fraction of simultaneous K plus L shell ionization probability decreases with increase in projectile energy as well as with increase in the atomic number of the targets atoms.     

Correlations betweenT c andn s/m * (carrier density/ effective mass) in high-T c and organic superconductors

We update our muon spin relaxation studies of the magnetic field penetration depth which show the correlations betweenT _c and the relaxation rate σ αn _s/m ^* (carrier density/effective mass) of hole-doped high-T _c cuprate superconductors (La₂, Sr₃)CuO₄, YBa₂Cu₃O₇ (Y_1−xPr_x)Ba₂Cu₃O₇, and other double and triple layer systems. These studies are extended to the organic superconductor (BEDT-TTF)₂Cu(NCS)₂.     

Lamb wave characteristics of thickness-graded piezoelectric IDT

An equivalent single layer model of Lamb wave generation by thickness-graded piezoelectric IDT on host structure is developed. Various additional complexities, such as the coupling between the Lamb wave modes, complicated nature of the electro-mechanical excitation are considered. The model of infinite IDT is extended to deal with the finite IDT with edge discontinuities. The effects of electromechanical coupling and thickness gradation on the wavelength shifts are investigated. The problem of electrically driven instability within the IDT is analyzed. Numerical results are reported by considering Al2O3/PZT IDT as integral part of the host structure, which show that there are significant changes and improvements in the Lamb wave characteristics due to the graded configuration. Most important among these is the reduced dispersiveness of the Lamb wave modes, which is useful in launching a SAW that propagates with narrower pulse width and less attenuation.     

Overlapping Schwarz preconditioners for indefinite time harmonic Maxwell equations

Time harmonic Maxwell equations in lossless media lead to a second order differential equation for the electric field involving a differential operator that is neither elliptic nor definite. A Galerkin method using Nedelec spaces can be employed to get approximate solutions numerically. The problem of preconditioning the indefinite matrix arising from this method is discussed here. Specifically, two overlapping Schwarz methods will be shown to yield uniform preconditioners.

     

Studies on Some Ternary Oxides of AVO3 Composition

AVO₃ (A = Ba²⁺, Sr²⁺, La³⁺, Gd³⁺) oxides have been prepared by hydrogen reduction of suitable vanadium(V) ternary oxides. The oxidation state of vanadium in the reduction products seems to be controlled by the nature of other cations. In the presence of strongly basic alkaline-earth metal ions, Ba²⁺ and Sr²⁺ as in Ba₂V₂O₇ and Sr₂V₂O₇, vanadium is reduced to +4 state. But when A is a trivalent lanthanide ion as in LnVO₄ (Ln = La or Gd), the reduction of vanadium proceeds to +3 state to yield LnVO₃ phases. The products have been characterized by X-ray diffraction. BaVO₃ crystallizes in a hexagonal structure related to Ba₃V₂O₈ while SrVO₃, LaVO₃ and GdVO₃ crystallize in GdFeO₃ type structure. Electrical transport measurements indicate that BaVO₃, LaVO₃ and GdVO₃ are p-type semiconductors while SrVO₃ is metallic.     

Studies on the structural,thermal and optical behaviour of solution grown organic NLO material: 8‐hydroxyquinoline

Single crystal of 8‐hydroxyquinoline (8HQ) having chemical formula C₉H₇NO, an organic nonlinear optical (NLO) material has been successfully grown by slow evaporation solution growth technique at room temperature. The crystal system has been confirmed from the powder X‐ray diffraction (PXRD) analysis. The crystalline perfection was evaluated by high resolution X‐ray diffractometry (HRXRD). From this analysis we found that the quality of the crystal is quite good. However, a very low angle (tilt angle 14 arc sec) boundary was observed which might be due to entrapping of solvent molecules in the crystal during growth. Its optical behavior has been examined by UV‐Vis. analysis, which shows the absence of absorbance between the wavelengths ranging from 400 to 1200 nm. From the thermal analysis it was observed that the material exhibits single sharp weight loss starting at 113°C without any degradation. The laser damage threshold was measured at single shot mode and the SHG behavior has been tested using Nd:YAG laser as a source. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)