Structural characterization, thermoluminescence studies and kinetic parameters of SrSO4:Eu nanophosphors under X-ray and gamma excitations.

Nanostructured SrSO4:Eu phosphors with high thermoluminescence (TL) emission temperatures have been synthesized through a controlled chemical precipitation method. Structural analysis and TL studies under both γ-ray and X-ray excitations were done. The phosphors were characterized using Powder X-ray diffraction, X-ray photoelectron spectroscopy, SEM, TEM, thermogravimetry, UV-VIS and photoluminescence studies. The average crystallite size estimated using PXRD data is found to be around 40nm. XPS and PL studies reveal that Eu(2+) ions are the luminescence emission centres in the phosphor. The phosphor is found to be highly TL sensitive to both γ-rays and X-rays with very high emission temperature which is not reported so far. The emission behaviour is suitable for environmental radiation dosimetry applications. The TL glow curve shows well-defined isolated high temperature emission peak at 312°C under 2Gy γ-excitation and 284°C for low energy diagnostic X-ray irradiation and 271°C for high energy therapeutic X-rays. Chen's peak shape method is applied to obtain the kinetic parameters behind the TL emission. The TL mechanism is found to follow second order kinetics, suggesting the probability of re-trapping of charge carriers.

Growth and characterisation of a new polymorph of barium maleate: a metal organic framework.

A new polymorph of barium maleate (BM) with chemical formula C24H14O24Ba5⋅7H2O is grown by modified gel method. Transparent plate like crystals of dimensions 9×4×1 mm(3) were obtained. Single crystal X-ray Diffraction analysis was done to determine the structure and the crystal belongs to triclinic system, P-1 space group with cell dimensions a=7.2929(3) Å, b=10.5454(4) Å, c=14.2837(6) Å, α=102.0350(10)°, ß=99.1580(10)°, γ=102.9170(10)°. Hydrogen bonding stabilises the two dimensional polymeric crystal structure. Fourier Transform Infrared spectroscopic method was utilised for the analysis of various functional groups present in the complex. Elemental analysis confirmed the stoichiometry of the complex. Thermal properties of the crystal were studied by TGA/DTA. The material melts at 368°C. The optical transparency of the crystal was studied using UV-Visible absorption spectra. The optical band gap is found to be 3.35 eV.

Growth and characterisation of crystals of a new organic complex of thiourea with quinine sulphate dihydrate: an NLO material.

An organic complex of thiourea and quinine sulphate dihydrate (TQS) has been grown for the first time by gel method. The structure determination was done by the single crystal XRD technique. The crystal belongs to monoclinic system, P21 space group with cell dimensions a=6.228 (3) Å, b=20.4051 (4) Å, c=11.0600 (6) Å, ß=101.9811(2)°. The crystal structure is stabilized by the hydrogen bonding. The functional groups present in the complex were analysed by the Fourier Transform Infrared spectroscopic method. The stoichiometry of the complex was confirmed by the elemental analysis. Thermal properties of the complex were determined by TGA and DTA methods and the complex melts at 222.53°C. The optical transparency of the crystal was studied using UV-Visible absorption spectra. The optical band gap is found to be 2.5 eV. The SHG conversion efficiency of TQS was investigated using Kurtz and Perry method and found to be higher than that of the reference material, potassium dihydrogen phosphate (KDP).

Crystal structure, spectral, thermal and dielectric studies of a new zinc benzoate single crystal.

Single crystals of zinc benzoate with a novel structure were grown in gel media. Sodium metasilicate of gel density 1.04 g/cc at pH 6 was employed to yield transparent single crystals. The crystal structure of the compound was ascertained by single crystal X-ray diffractometry. It was noted that the crystal belongs to monoclinic system with space group P2(1)/c with unit cell parameters a=10.669(1)Å, b=12.995(5)Å, c=19.119(3)Å, and ß=94.926(3)°. The crystal was seen to possess a linear polymeric structure along b-axis; with no presence of coordinated or lattice water. CHN analysis established the stoichiometric composition of the crystal. The existence of functional groups present in the single crystal system was confirmed by FT-IR studies. The thermal characteristic of the sample was analysed by TGA-DTA techniques, and the sample was found to be thermally stable up to 280°C. The kinetic and thermodynamic parameters were also determined. UV-Vis spectroscopy corroborated the transparency of the crystal and revealed the optical band gap to be 4 eV. Dielectric studies showed decrease in the dielectric constant of the sample with increase in frequency.

Gross signs and histopathology of branchiostegal blister disease (balloon disease): an idiopathic disease of farmed Macrobrachium rosenbergii (De Man).

The giant freshwater prawn, Macrobrachium rosenbergii, is facing increased threat due to disease as its culture becomes more widespread. A disease characterized by the swelling of the branchiostegal region and deformities of the appendages, named balloon disease by farmers, has caused considerable economic loss in the Nellore region of Andhra Pradesh, India. Clinical signs of diseased animals include a voluminous hypertrophy of some gill filaments and the inner area of the branchiostegite. By histology, hypertrophied areas at the level of the gill filaments or branchiostegite had an identical structure corresponding to a large cyst filled with a fluid containing a few free haemocytes, limited on one side by the cuticle and on the other by the subcuticular epithelial layer. Analysis of the diseased prawns did not reveal any pathogenic agent leading us to conclude that the disease is idiopathic, probably due to suboptimal water quality conditions.

A novel conformation of valinomycin in its barium complex.

Knowledge of the molecular mechanisms involved in ionophore-mediated cation transport would be valuable for understanding many essential functions of biological membranes. Cations are transported in several stages, such as formation of the ionophore-cation complex, diffusion across the cell membrane and subsequent release of the cation. Several conformational rearrangements are involved in this process, and so a detailed understanding of all the conformational possibilities of the ionophore seems to be essential for elucidating the molecular mechanism of ion transport. We are carrying out spectroscopic and crystallographic studies to explore the possible conformational stages of ionophores by complexing them, in different solvents, with cations of various sizes and charges. We report here a novel conformation of the ionophore valinomycin in its barium complex. It can be described as an extended depsipeptide chain, without interval hydrogen bonds, wound in the form of an ellipse with the two barium ions located at the foci.

Experimental infection of animals with influenzavirus types A and B.

The knowledge that domestic cats were susceptible to infection with freshly isolated A/Hong Kong/68 influenzavirus led to studies on the susceptibility of some other animal species to this virus, as well as to studies on the ability of egg-passaged Hong Kong virus and an Asian virus to infect cats. The ability of a recent isolate of influenzavirus B to infect these animals was also studied. Macaca radiata monkeys could be infected with fresh isolates of A/Hong Kong virus by intranasal instillation or by contact with infected animals. They could also be infected with influenzavirus B by intranasal challenge, but contact transmission was not demonstrated. Mongrel dogs were found to be susceptible to A/Hong Kong/68 virus by intranasal instillation, but not to type B virus. Domestic cats could be infected with A/Hong Kong/68 virus passaged 6 times in eggs. They were also susceptible to infection with an established laboratory strain of Asian virus. Cats could be infected with influenzavirus B either by intranasal challenge or by contact with infected animals. In no case was clinical illness found following infection, but the infected animals shed virus from the throat and developed haemagglutination inhibiting antibodies.

Infection with A2 Hong Kong influenza virus in domestic cats.

The antigenic relationship of A2 Hong Kong influenza virus with equine influenza virus, and its ability to infect horses and baboons, have led to studies on the susceptibility of domestic animals to the virus.In this study it was found that cats could be infected with A2 Hong Kong influenza virus by intranasal inoculation or by contact with an infected cat or with a human influenza patient. There was no clinical illness, but infected animals shed the virus from the throat for 1 week and developed haemagglutination-inhibiting antibodies. A survey of normal cat sera showed that 6 out of 28 sera inhibited haemagglutination by A2 Hong Kong influenza virus.The results suggest that domestic cats may act as vectors in the transmission of influenza virus. Experimental infection in cats may be used as a laboratory model for influenza.