Growth and characterization of cadmium magnesium tetra thiocyanate crystals

Cadmium Magnesium Tetra Thiocyanate, CdMg(SCN)₄, [CMTC] belongs to bimetallic thiocyanate complexes. CMTC crystals has been grown by solution growth technique at room temperature. The morphologies of the grown crystals are identified by single crystal analysis. Also the Powder X‐ray Diffractogram of the crystal has been recorded and the various planes of reflection are identified. The title compound crystallizes under triclinic structure with lattice parameters a = 10.0976 Å, b = 7.5015 Å, c = 5.7720 Å and β = 90.2135°. The presence of magnesium and cadmium in the grown crystals were confirmed through Atomic Absorption Spectroscopy. The grown crystals are analysed qualitatively by Fourier Transform Infrared (FTIR) and Fourier Transform Raman spectral measurements. The transmittance spectrum of the crystal in the UV‐Visible region has been recorded and analysed. The dielectric measurements for the crystals were carried out in the microwave region. The thermal stabilities of the crystals were studied by using different thermal analyses like Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Multi-band phase shifter design using modified slotline configuration

In this paper, an analog multiband phase shifter using slotline configuration is proposed. To implement the design, a pair of modified Split Ring Resonator (SRR) is employed. The periodic property of SRR provides multiband characteristics, whether the coupling slot gives the phase variations over the bands. The operation is well explained with an equivalent circuit model and its characteristics have been studied both in simulation and measurement. The prototype operates in 1.77–2.16, 3.5–3.97, 5.08–5.33, 6.43–6.93, and 8.01–8.59 GHz frequency bands which can be utilized for GSM, GPS, WLAN, C-band, and X-band applications, respectively.     

Structural and superconducting properties of oxygen-deficient GdBaSrCu3Ox (6.5<x<7.0)

3 O_x with both orthorhombic and tetragonal structure were synthesized using different heat treatments. From each type, a series of oxygen-depleted samples, denoted as “O” and “T”, with oxygen contents 6.5<x<7.0 were prepared by annealing in argon at different temperatures in the range 300–550 °C. For O- and T-samples, superconductivity vanishes below x≈6.8 and x≈6.6, respectively. While T-samples show a continuous variation of both T_c and the unit-cell volume with x, O-samples show coinciding anomalies in these dependences. In all cases, the oxygen loss with respect to fully oxygenated samples was determined by both weight measurements (δ_w) and iodometric titration (δ_t) With T-samples, δ_w and δ_t are in good agreement, whereas with O-samples considerable discrepancies between these values were found. These disparities in the properties of O- and T-samples may be related to differences in the oxygen sublattice. Received: 25 February 1997/Accepted: 27 February 1997     

Spectroscopic characterization of indian standard sand

The characterization of Indian standard sand (IS650:1991 as per B.I.S. approval) was performed by X-ray diffraction, IR and Raman spectroscopy, and nuclear magnetic resonance techniques. The principal reflections occurring at the d-spacings of 4.2408, 3.3440, and 1.8292 ? confirm the presence of α-quartz crystalline structure in the sample. The calculated unit cell parameters are: a = 4.9294 ?, c = 5.4093 ?, and V = 113.832 ?³. Mid-IR spectrum shows the characteristic doublet for α-quartz at 797 and 778 cm^–1. The Al/Al+Si ratio has been calculated from the position of the absorption band at 1100 cm^–1. Raman spectrum of the sample has two strong peaks at 203 cm^–1 and at 462 cm^–1 for A1 vibrational mode characteristic of α-quartz. Two bands at 1410 and 1930 nm in near-IR spectrum indicate the presence of both molecular water and an OH group. A broad double band centered near 1210 nm and a weak band at 1050 nm attest the presence of Fe²⁺ and Fe³⁺ respectively in the sample. The signal near g ∼ 4 is characteristic of isolated Fe³⁺ ions in the distorted octahedral or tetrahedral crystalline field. ²⁹Si NMR spectrum shows a strong signal at –107 ppm corresponding to quartz.     

Synthesis,growth and characterization of non-linear optical material: l-Tryptophan p-nitrophenol (LTPNP) single crystal

A new nonlinear optical organic crystal l-tryptophan p-nitrophenol (LTPNP) of dimension 19 mm × 2 mm × 1.5 mm has been grown from an aqueous solution for the first time by slow evaporation technique at ambient temperature. The crystal structure of LTPNP was confirmed by single crystal X-ray diffraction. LTPNP crystallizes in non-centrosymmetric monoclinic system with space group P₂₁. The recorded FTIR spectrum confirms the presence of various functional groups in the grown crystal and confirms the formation of LTPNP. Thermal stability and melting temperature of the LTPNP crystal were identified from TG/DTA analysis. The optical absorption study confirms the suitability of the crystal for device applications. LTPNP exhibits SHG efficiency over 1.7 orders of magnitude higher than that of urea and 4 orders of magnitude higher than that of KDP.     

Identification and Characterization of Bile Salt Hydrolase Genes from the Genome of Lactobacillus fermentum MTCC 8711

Lactobacillus fermentum is a lactic acid bacterium of probiotic importance, which is found ubiquitously in fermented milk products. Bile salt hydrolase (BSH) has a significant role in affording probiotic properties to lactobacilli. In the present study, two bsh genes encoding BSH1 and BSH2 were identified from the draft genome sequence of L. fermentum MTCC 8711. Nucleotide comparison revealed no significant similarity between bsh1 and bsh2 genes, whereas the deduced amino acid sequences showed 26 % sequence similarity between both BSH1 and BSH2. Pfam analysis revealed the presence of cys-2 active site residues in the catalytic pocket of both BSH1 and BSH2 highly essential for catalysis. Phylogentic analysis of BSH1 and BSH2 revealed the possible independent origin of these proteins in Lactobacillus. We cloned these genes in pSLp111.3, a Lactobacillus expression vector with signal peptide A (slpA) and expressed in the native L. fermentum strain for overexpression and extracellular secretion. The bsh1 gene failed to express and to produce promising BSH activity. However, bsh2 gene was overexpressed and the recombinant strain showed improved BSH activity. Induction of the recombinant strain with an optimal 2 % xylose concentration secreted 0.5 U/ml of the BSH into extracellular medium. Furthermore, the recombinant strain was able to completely assimilate the 100-μg/ml cholesterol within 24 h, whereas the native strain took 72 h for the complete assimilation of cholesterol.