Electronic, optical, and thermoelectric characteristics of (Ae)xFBiS2 (Ae=Sr, Ba, and x=1.7) layered materials useful in optical modulator devices.

The recent discovery of superconductivity behavior in the mother BiS2-layered compounds has captivated the attention of several physicists. The crystal structure of superconductors with alternate layers of BiS2 is homologous to that of cuprates and Fe-based superconductors. The full-potential linearized augmented plane-wave (FP-LAPW) technique was utilized to investigate the electronic structures and density of states in the vicinity of the Fermi energy of SrFBiS2 and BaFBiS2 compounds under the electron carriers doping. The introduction of electron doping (carries doping) reveals that the host compounds SrFBiS2 and BaFBiS2 exhibit features indicative of superconductivity. This carrier doping of SrFBiS2 and BaFBiS2 compounds (electron-doped) has a significant impact on the lowest conduction states near the Fermi level for the emergence of the superconducting aspect. The electron doping modifies and induces changes in the electronic structures with superconducting behavior in (Ae)1.7FBiS2(Ae=Sr,Ba) compounds. A Fermi surface nesting occurred under the modification of electrons (carriers) doping in the host compounds SrFBiS2 and BaFBiS2. Furthermore, the optical characteristics of the carrier-doped SrFBiS2 and BaFBiS2 compounds are simulated. Due to the anisotropic behavior, the optical properties of these materials based on BiS2 demonstrate a pronounced polarization dependency. The starting point at zero photon energy in the infrared region is elucidated by considering the Drude features in the optical conductivity spectra of SrFBiS2 and BaFBiS2 compounds, when the electron carriers doping is applied. It was clearly noticed that the spin-orbit coupling (SOC) influences the electronic band structures, density of states, Femi surface, and optical features because of the heavy Bismuth atom, which may disclose fascinating aspects. Further, we conducted simulations to assess the thermoelectric properties of these mother compounds. The two BiS2-layered compounds could be suitable for practical thermoelectric purposes and are highlighted through assessment of electrical conductivity, thermal conductivity, Seebeck coefficient, and power factor. As a result, we propose that the mechanisms of superconducting behavior in BiS2 family may pave new avenues for investigating the field of unconventional superconductivity. It may also provide new insights into the origin of high-Tc superconductivity nature.

Analysis of phase stability, elastic, electronic, thermal, and optical properties of Sc1-xYxN via ab initio methods.

Understanding the physical properties of a material is crucial to know its applicability for practical applications. In this study, we investigate the phase stability, elastic, electronic, thermal, and optical properties of the ternary alloying of the scandium and yttrium nitrides (Sc1-xYxN) for different compositions. To do so, we apply a "density functional theory (DFT)" based scheme of calculations named as "full potential (FP) linearized (L) augmented plane wave plus local orbitals (APW + lo) method" realized in the WIEN2k computational package. At first, the phase stability of the investigated compositions of the mentioned alloy is determined. The analysis of our calculations shows that Sc1-xYxN alloy is stable in rock salt crystal structure for all investigated compositions. Next to that, the elastic properties of the rock-salt phase of the studied ternary alloy Sc1-xYxN at all above said compositions were done at the level of "Wu-Cohen generalized gradient approximation (Wu-GGA)" within DFT. However, Trans-Blaha (TB) approximation of the "modified Becke-Johson (mBJ)" potential is also used in combination with Wu-GGA where the thermal properties are calculated at the level of the "quasi-harmonic Debye model." The obtained results for the absorption coefficients, and optical bandgap, represent that the title alloy may be a suitable candidate for the applications in optoelectronic devices.

Phosphide in gallium bismuth: structural, electronic, elastic, and optical properties of GaPxBi1-x alloys.

The structural, electronic, elastic, and optical properties of ternary alloys GaPxBi1-x as a function of phosphorus concentration were studied using ab initio calculations. We have used the full-potential linearized augmented plane wave method-based density functional theory. The potentials have been described by the generalized gradient and modified Becke-Johnson approximations. Results on lattice parameters, energy band gap, bulk modulus, elastic, and optical properties are reported. They are in good agreement with available theoretical and experimental data. Moreover, the dependence of structural and electronic properties on the composition has been analyzed. A deviation from linearity is observed for the lattice constant and the bulk modulus. In addition, the elastic constants and moduli were calculated and used to examine the mechanical stability. Both parts of dielectric-function and other optical parameters have been analyzed.

Phase stability and optoelectronic characteristics of Ba1-xBexS: a DFT-based simulation.

The structural stability and optoelectronic properties of the ternary Ba1-xBexS alloys along with the pure binary compounds BaS and BeS in the rock-salt (B1) and zinc-blende (B3) phases were investigated by the density functional theory (DFT) within the full-potential linearized augmented plane wave (FP-LAPW) method implemented in the Wien2k package. The generalized gradient approximation of Wu and Cohen (WC-GGA) was used for the exchange-correlation potential (Vxc) to compute the equilibrium structural parameters, lattice constant (a), and bulk modulus (B). In addition to the GGA approach, the modified Becke-Johnson potential of Tran and Blaha (TB-mBJ) scheme coupled with the spin-orbit interaction was used to calculate the band gap energies. Results reveal that BaS, Ba0.75Be0.25S, and Ba0.5Be0.5S compounds are stable in the rock-salt phase, while Ba0.25Be0.75S and BeS are found to be stable in the zinc-blende phase. The computed results for the band structures and optical constants are compared with other available theoretical calculations and experimental measurements.

Study of structural, elastic, electronic, and vibrational properties of MRh2O4 (M = Cd and Zn) spinels: DFT-based calculations.

Solar-assisted water splitting using photoelectrochemical cells (PECs) is one of the promising ways for the production of hydrogen to store renewable energy. Semiconducting materials are used as a key factor which controls the overall energy conversion efficiency in PECs. However, finding new semiconductors with appropriate properties (stability, efficient charge separation and transport, abundant and visible light absorption) is still a challenge for developing new materials for solar water splitting. Spinel-type structures which have suitable band gaps for visible light harvesting are promising candidates for PEC applications. In this study, first principles method within density functional theory (DFT) have been used to study the structural, elastic, electronic, and vibrational properties of MRh2O4 (M = Cd and Zn) for cubic spinel phase. Present study reveals that the CdRh2O4 and ZnRh2O4 in spinel structure are semiconducting in nature and they also satisfy the stability criterion. Thus, studied spinels can be used as semiconductors in PEC applications.

First principles investigations of the structural, elastic, vibrational, and thermodynamic properties of TiMg2O4 oxide spinels: cubic and tetragonal phases.

In the present study ab initio methology under density functional theory with generalized gradient approximation is used to study the structural, elastic, and vibrational properties of TiMg2O4 with cubic and tetragonal phases with space groups (Fd[Formula: see text]m) and P4_122, respectively. The present study shows that the studied compound TiMg2O4 is mechanically stable in both phases. Both phases have ductile nature and strong anisotropic properties, and it is also observed that the tetragonal phase has more anisotropic properties compared to the cubic phase. Obtained structural parameters are in good agreement with related literature.

Argyrophilic nucleolar organizer regions: their value and correlation with clinical prognostic factors in breast carcinoma.

BACKGROUND AND OBJECTIVES: Argyrophilic nucleolar organizer regions (AgNORs) have been recently identified as a marker of proliferative index in various tumors. These were evaluated in 46 patients with primary breast carcinoma and were correlated with clinical prognostic parameters of breast cancer. Ten patients with benign breast tumors served as controls in the study. METHODS: AgNORs were stained in paraffin sections of the tissues using Ploton's silver technique. For each specimen, the number of AgNORs, within the nuclei of 100 tumor cells were calculated. The average number of AgNORs per nucleus was calculated and the results expressed as mean +/- S.D. RESULTS: AgNOR count was significantly higher in breast carcinoma (6.61 +/- 1.75) than in benign breast tumors (1.88 +/- 0.19). Further, the AgNOR count in breast carcinoma showed a statistically significant increase in correlation with the increase in the size of the tumor, stage of the cancer, number of metastatic lymph nodes, and tumor recurrence at various sites. However, the differences in AgNOR count at different lymph node levels and histologic grading were not statistically significant. CONCLUSIONS: These results indicate that breast tumors with a higher AgNOR count, even at the initial stage, have a poor prognosis and require aggressive treatment for better control of the disease. Further, it is suggested that the patients with a benign tumor and more than three AgNORs per nucleus need careful surveillance.

Endoscopic diagnosis of segmental colonic tuberculosis.

We report colonoscopic findings in 29 proven cases of segmental colonic tuberculosis. The colonoscopic appearances of tuberculosis included: mucosal nodules and ulcers, stricture with nodules and ulcerations, and mucosal nodules with or without pseudopolypoid folds. In 12 (41%) of 29 patients colonoscopy biopsies enabled a histologic diagnosis to be made on the basis of typical granulomas. Culture of biopsy tissue on Lowenstein Jensen media isolated Mycobacterium tuberculosis in six (40%) of 15 patients. Combined histologic and bacteriologic evaluation established the diagnosis in 60% of patients. We conclude that even though target biopsy is an effective method of diagnosis, anti-tuberculous chemotherapy may be started on the basis of the endoscopic appearance if there is a high clinical suspicion of tuberculosis.

Evaluation of enzyme-linked immunosorbent assay using mycobacterial saline-extracted antigen for the serodiagnosis of abdominal tuberculosis.

The efficacy of enzyme-linked immunosorbent assay (ELISA) was evaluated in the sera of 215 individuals as a diagnostic aid in abdominal tuberculosis. The subjects had abdominal tuberculosis (group 1), intestinal disorders other than tuberculosis (group 2), cirrhosis of the liver (group 3), and peritoneal malignancy (group 4). Sera from patients of pulmonary tuberculosis and healthy volunteers (group 5) were also analyzed for enzyme activity and served as positive and negative controls. In patients with abdominal tuberculosis, the absorbance (OD) values were significantly higher than for the other groups and healthy volunteers (p less than 0.001). OD values were similar in abdominal and pulmonary tuberculosis (p greater than 0.05). Level above 0.7 (OD) in serum suggests tuberculosis with a sensitivity of 81%, specificity of 88%, and a diagnostic accuracy of 84%. These results suggest that ELISA may be used for the diagnosis of abdominal tuberculosis and in differentiating it from other nontuberculous abdominal diseases.

Peritoneal tuberculosis: laparoscopic patterns and its diagnostic accuracy.

We report laparoscopic findings in 38 proven cases of peritoneal tuberculosis. The laparoscopic appearances can be classified into three types: thickened peritoneum with miliary yellowish white tubercles with or without adhesions (n = 25), only thickened peritoneum with or without adhesions (n = 8), and fibroadhesive pattern (n = 5). Biopsies were avoided from fibroadhesive lesions due to risk of complications. Visual diagnosis was accurate in 95% of patients. In comparison, in 27 (82%) of 33 patients, the examination enabled a histologic diagnosis to be made on the basis of typical granulomas. The combined use of guinea pig inoculation and culture isolated Mycobacterium tuberculosis in six (37.5%) of 16 patients. Mycobacteria were scarcely (3%) seen on histological sections. We conclude that, although target biopsy is an effective method of obtaining an early diagnosis of peritoneal tuberculosis, chemotherapy may be started on the basis of visual laparoscopic appearances alone.

Adenosine deaminase (ADA) in peritoneal tuberculosis: diagnostic value in ascitic fluid and serum.

Simultaneous determination of ascitic fluid and serum adenosine deaminase (ADA) activity was evaluated as a diagnostic aid in peritoneal tuberculosis. The ascites was due to peritoneal tuberculosis (group 1), cirrhosis of the liver (group 2), cirrhosis of the liver with spontaneous bacterial peritonitis (group 3), peritoneal malignancy (group 4), Budd-Chiari Syndrome (group 5) and miscellaneous conditions (group 6). Serum from patients of pulmonary tuberculosis and healthy volunteers was analysed for enzyme activity. In patients with peritoneal tuberculosis the ascitic fluid and serum ADA activity was significantly higher than for the other groups (P less than 0.001). Levels above 36 u/l in ascitic fluid and above 54 u/l in the serum suggest tuberculosis. The ascitic fluid/serum ADA ratio was also higher in patients with peritoneal tuberculosis than with other causes of ascites (P less than 0.01). A ratio of more than 0.984 was suggestive of tuberculosis.

Chronic effect of datura (seed) extract on the brain of albino rats.

The effect of chronic treatment with datura (seed) extract was studied to investigate its effect on the energy metabolism and peroxidative activities in the brain of rats. Datura treatment was found to cause an increase in the activity of brain lipid peroxidase and catalase, while it caused a decrease in the activity of fructose diphosphate aldolase and glucose 6-phosphate dehydrogenase enzyme. A marked reduction was noted in the protein, DNA and RNA contents of datura administered rats.

Effect of Datura (seed) on rat brain and urinary metabolites.

The effect of Datura alba (seed) extract on the brain and urinary metabolites of rats was studied. Treatment with Datura brought about a decrease in the activity of brain lipid peroxidase and catalase while an increase in the activity of fructose diphosphate aldolase and glucose 6-phosphate dehydrogenase was observed. An increase in the DNA and RNA contents of brain was noted after the treatment with Datura. The study also showed a marked decrease in the excretion of 5-hydroxyindole acetic acid and vanillyl mandelic acid in the urine of rats given Datura extract.