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Urease-producing bacteria can precipitate calcite nano-crystals by producing urease in the presence of urea and calcium. Calcite precipitation resulting from microbial activity is a process which causes cementation of soil particles in nature. The purpose of this study was to isolate urease-producing halophilic bacteria in order to precipitate calcite in saline soil. Natural samples, including soil and saline waters, were selected for this purpose. At First, halophilic bacteria were isolated by salt-containing TSB medium. Then, a selective medium containing phenol red and urea facilitated the isolation of urease-producing bacteria. Hydrolysis of urea by urease causes alkalization of the medium and the formation of pink halo around colonies. Finally, the best isolate was selected for further study by measuring the release of ammonium by the Nessler method. The ability or inability of isolates to produce calcite was investigated by culturing the isolates on sedimentary medium with different salt concentrations for 10 days. In total, 110 halophilic isolates were isolated, among which 58 isolates had the ability of urease production. The microscopic studies of colonies showed that only 6 isolates were able to produce crystals on precipitation medium. Isolate 6 was selected for further study and then analyzed by X-ray diffraction crystals on precipitation medium. Isolate 6 was selected for further study and then analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) detector. Studies of urease activity showed that this strain released 20.86 mM ammonium after 18 hours. This bacterium was identified by biochemical and molecular analyses and the comparison of its 16S rRNA gene sequence showed 99.92% similarity with the similar gene sequence in Staphylococcus xylosus and then this sequence was submitted in NCBI database with the accession number MG655155. This isolate was able to produce calcite in free salt medium, with salinity up to 10%. Nowadays, many efforts have been made to produce environmental-friendly cements, and therefore, the use of urease-producing halophilic bacteria is an appropriate candidate for bio-cementing in saline environments.

Titanium dioxide nanoparticles (TiO2) are known as a widely used photocatalyst. In order to improve the performance of these nanoparticles, the recombination of the electron-cavity pair must be reduced and the absorption rate of the visible region should be expanded. One way to increase the performance of these nanoparticles is using cerium doped TiO2. In the present study, pure and doped titanium dioxide nanoparticles were made by the electrical discharge method. The effect of cerium dopants on the structural, morphological and optical properties were studied by x-ray diffraction (XRD), scanning electron microscopy (FESEM), diffused reflection spectroscopy (DRS), photoluminescence (PL) and infrared fourier transform (FTIR) spectroscopy analyses. XRD analysis revealed that the size of TiO2 nanocrystals was decreased to 7.7 nm. The FESEM morphology of the samples also showed that the uniformity of the Ce doped TiO2 was decreased. Further, the DRS results indicated that the band gap energy of Ce-TiO2 was decreased to 2.24 eV. The photoluminescence results demonstrated that the intensity of PL was reduced for the Ce-TiO2 sample, which reduced the recombination of the electron-hole coupling and increased the photocatalytic activity in the doped sample.

In this research work, different terbium doped lutetium aluminium garnet nano crystalline powders were prepared by the co-precipitation method in different sizes at different annealing temperatures. The structural properties and size of the different nano crystalline powders prepared at different temperatures were investigated by the X-ray diffraction pattern and TEM. Also, the atomic structure of different nano crystals in garnet forming was studied by Fourier Trans from Infrared (FTIR) method. The impact of different crystallite sizes on the absorption energy was investigated by the UV-visible spectroscopy. The emission and excitation spectra of terbium doped lutetium aluminium garnet nano-structure powders were measured at room temperature. The decay time of different nano crystalline with different sizes was examined at room temperature. The change of nanocrystalline size affects the decay time. Also, the investigation of terbium doped garnet emission spectra showed that this material can be used as an appropriate scintillator for detection systems such as medical diagnostic and therapeutic.

Introduction: Recent studies have indicated that titanium dioxide nanoparticles (TiO2 NPs) are toxic for human. Silymarin is a well-known hepatoprotective drug. In this study, the nanoprecipitation technique was used for nanocrystals to improve the solubility of silymarin. The aim of this study was to analyze the protective role of silymarin and its nanocrystal on liver damage due to TiO2 NPs in rat. Methods: In this experimental study, rats were divided to five groups in separate cages: Control, vehicle, toxic group (150 mg/kg TiO2 NPs for three weeks orally) as well as silymarin and silymarin NPs groups (100 mg/kg for three weeks orally after TiO2 NPs administration). Then, the serum level of aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP) as well as the liver histological changes were investigated. Results: Oral administration of Tio2 NPs resulted in significantly elevated levels of ALT, AST and ALP of serum and significantly increased the core diameter of hepatocytes (P < 0.05). Silymarin and its nanocrystal reduced the elevated liver enzyme levels and also decreased the core diameter of hepatocytes in toxic rats (P < 0.001). Conclusion: : The results from the present study indicated that silymarin and its nanocrystal probably due to antioxidant effects cause hepatoprotective against TiO2 NPs-induced liver injury.

Titanium dioxide nanoparticles (TiO2) are known as a widely used photocatalyst. In order to improve the performance of these nanoparticles, the recombination of the electron-cavity pair must be reduced and the absorption rate of the visible region should be expanded. One way to increase the performance of these nanoparticles is using cerium doped TiO2. In the present study, pure and doped titanium dioxide nanoparticles were made by the electrical discharge method. The effect of cerium dopants on the structural, morphological and optical properties were studied by x-ray diffraction (XRD), scanning electron microscopy (FESEM), diffused reflection spectroscopy (DRS), photoluminescence (PL) and infrared fourier transform (FTIR) spectroscopy analyses. XRD analysis revealed that the size of TiO2 nanocrystals was decreased to 7.7 nm. The FESEM morphology of the samples also showed that the uniformity of the Ce doped TiO2 was decreased. Further, the DRS results indicated that the band gap energy of Ce-TiO2 was decreased to 2.24 eV. The photoluminescence results demonstrated that the intensity of PL was reduced for the Ce-TiO2 sample, which reduced the recombination of the electron-hole coupling and increased the photocatalytic activity in the doped sample. [ABSTRACT FROM AUTHOR]