Pressure induced electronic topological transition in Sb2S3

Pressure induced electronic topological transitions in the wide band gap semiconductor Sb2S3 (Eg = 1.7-1.8 eV) with similar crystal symmetry (SG: Pnma) to its illustrious analog, Sb2Se3, has been studied using Raman spectroscopy, resistivity and the available literature on the x-ray diffraction studies. In this report, the vibrational and the transport properties of Sb2S3 have been studied up to 22 GPa and 11 GPa, respectively. We observed the softening of phonon modes Ag(2), Ag(3) and B2g and a sharp anomaly in their line widths at 4 GPa. The resistivity studies also shows an anomaly around this pressure. The changes in resistivity as well as Raman line widths can be ascribed to the changes in the topology of the Fermi surface which induces the electron-phonon and the strong phonon-phonon coupling, indicating a clear evidence of the electronic topological transition (ETT) in Sb2S3. The pressure dependence of a/c ratio plot obtained from the literature showed a minimum at ~ 5 GPa, which is consistent with our high pressure Raman and resistivity results. Finally, we give the plausible reasons for the non-existence of a non-trivial topological state in Sb2S3 at high pressures.Comment: 24 pages, 6 Figures, 2 tables submitted for publicatio

Lidar observations of sporadic Na layers over Gadanki (13.5° N, 79.2° E)

International audienceWe studied the characteristics of sporadic sodium layers (SSLs) observed with the sodium (Na) resonance scattering lidar at Gadanki (13.5° N, 79.2° E). The SSLs were observed on a total of 63 occasions during 464 h of Na lidar observations from January 2005 to February 2006. The observations showed that one SSL event occurred, on average, every 7 h. The most prominent sporadic layer, which formed on 12 February 2005, exhibited a peak density of 60 722 Na atoms/cm³ around 92 km and it was nearly twice the peak density reported from elsewhere using ground-based observations. In general, the SSLs exhibited the following characteristics: (1) they developed at heights between 88 and 98 km with an average height around 94 km; (2) maximum density occurred during the early morning hours between 02:00 and 05:00 IST; (3) the ratio of the maximum peak Na density to the average density was normally around 3 to 5 and it exceeded even 10 in some cases; (4) the events lasted from a few minutes to several hours. The formation period of the SSLs was longer compared to the decay period of the SSLs. Most of the SSL events showed downward motions

ASSESSMENT OF PHARMACEUTICAL CARE SERVICES ON HEALTH RELATED QOL IN PATIENTS WITH TYPE 2 DIABETES MELLITUS – A PROSPECTIVE INTERVENTIONAL STUDY

Background: In the last three decades role of pharmacist has changed dramatically. Patient counselling by pharmacist deals with providing information to the patients regarding the disease, Medications and lifestyle modifications. Diabetes mellitus (DM) is a severe medical and social problem that affects patient's general wellbeing. Despite of the advances in understanding the disease and its management, the morbidity and mortality rate are in rise. Objective: To study the impact of pharmaceutical care services on quality of life in type 2 diabetes mellitus. To improve the knowledge, practice abd attitude, Quality of life of patients towards disease management. Methods: This is a prospective intervention study. It was carried out to determine the quality of life, based on which patients were counselled regarding disease, medication, nutrition, exercise, insulin, foot care, eye care, personal hygiene, self monitoring of glucose and self care. Out of 80 patients, who are having diabetes mellitus and given patient counseling again collected after 1st and 2nd month. The paired t-test in Graph Pad InStat was used for statistical calculation. Results: The overall KAP scores for diabetes patients between test of baseline and final follow up was statistically significant (P< 0.001). The test group has shown increased medication adherence than control which shows the importance of patient counseling. Conclusion: The study concluded that pharmacist mediated patient counseling and the disease, medications and lifestyle modifications will improve the knowledge, attitude and practice, Quality of life and Glycemic control

Switching of the topologically trivial and non-trivial quantum phase transitions in compressed 1T-TiTe2: Experiments and Theory

We report the structural, vibrational and electrical transport properties up to 16 GPa of the 1T-TiTe2, a prominent layered 2D system, which is predicted to show a series of topologically trivial - nontrivial transitions under hydrostatic compression. We clearly show signatures of two iso-structural transition at 2 GPa and 4 GPa obtained from the minima in c/a ratio concomitant with the phonon linewidth anomalies of Eg and A1g modes at around the same pressures, providing strong indication of unusual electron-phonon coupling associated to these transitions. Resistivity presents nonlinear behavior over similar pressure ranges providing a strong indication of the electronic origin of these pressure driven isostructural transitions. Our data thus provide clear evidences of topological changes at A and L point of the Brillouin zone predicted to be present in the compressed 1T-TiTe2. Between 4 GPa and 8 GPa, the c/a ratio shows a plateau suggesting a transformation from an anisotropic 2D layer to a quasi 3D crystal network. First principles calculations suggest that the 2D to quasi 3D evolution without any structural phase transitions is mainly due to the increased interlayer Te-Te interactions (bridging) via the charge density overlap. In addition to the pressure dependent isostructural phase transitions, our data also evidences the occurrence of a first order structural phase transition from the trigonal (P-3m1) phase at higher pressures. We estimate the start of this structural phase transition to be 8 GPa and the symmetric of the new high-pressure phase to be monoclinic (C2/m).Comment: 22 pages, 11 Figures, 2 Table

COUROUPITA GUIANENSIS LEAF CALLUS EXTRACT MEDIATED SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES.

Objective: Synthesis of varied sized and morphologically distinct silver nanoparticles (AgNPs) using callus/callus extract, and their promising antibacterial and cytotoxicity was reported from very few plant systems. Here, we investigated silver nanoparticle synthetic potential of Couroupita guianensis leaf callus extract and their antibacterial activity.Methods: synthesis of callus mediated silver nanoparticles and characterisation of physical, chemical, and antibacterial activity of AgNPs.Results: Callus extract rapidly reduced silver ions and stabilized nanoparticles have displayed characteristic maximum UV absorbance at 410 nm. SEM and AFM images revealed their spherical morphology and size variation, which is ranged from 30.38 nm to 88.32 nm and were in small aggregates. Capping of AgNPs by the phenolic compounds and proteins revealed from FTIR spectral peaks. Silver nanoparticles displayed significantly high antimicrobial activity against both Gram positive and negative bacterial strains compared to silver ions and gentamicin. This enhanced antimicrobial activity of AgNPs may due their small size leading to efficient molecular contact with cell surface, and uptake and interaction with vital biomolecules.Conclusions: Stable AgNPs were synthesized through reduction and capping of silver ions by polyphenols and proteins present in callus extract. Theenhanced antimicrobial activity of AgNPs may due to their small size leading to efficient molecular contact with the cell surface, penetration, andinteraction, and inactivation of vital biomolecules.Â

Dietary intake of Po-210 and Pb-210 in the environment of Goa of south-west coast of India

This paper deals with the distribution and activity intake of Po-210 and Pb-210 in food, diet, and potable water samples of the Goa region and the estimated committed effective dose due to ingestion of these radionuclides. The activity concentrations of Po-210 and Pb-210 were determined in about 30 food and diet samples from different places of Goa in order to know the distribution and intake of these radionuclides. The activity concentration of Po-210 in fish and prawn samples were significantly higher than concentrations found in vegetable and rice samples. Higher concentrations of Po-210 and Ph-210 were observed in leafy vegetables than in non-leafy vegetables. Among the diet samples the activity concentrations of Po-210 and Ph-210 in non-vegetarian meal samples were relatively higher than in vegetarian meal and breakfast samples. The committed effective dose due to annual intake of Po-210 was found to be 94.6 mu Sv, 49.1 mu Sv, 10.5 mu Sv, and 2.2 mu Sv and that of Pb-210 found to be 81.6 mu Sv, 59.9 mu Sv, 14.6 mu Sv, and 2.0 mu Sv for the ingestion of non-vegetarian meal, vegetarian meal, breakfast, and potable water, respectively

Distribution and enrichment of 210Po in the environment of Kaiga in South India

Several soil and vegetation samples from the environment of Kaiga nuclear power plant site in the south western region of India were analysed for 210Po. The vertical profile, particle-size distribution, seasonal variation and the dry deposition rate of 210Po were measured employing the chemical method and α - counting technique. 210Po activity in soil varies from 17.1 to 228.2 Bq kg-1 with a mean value of 83.3 Bq kg-1. The activity of 210Po is higher in the surface soil (0-5 cm) and decreases as depth increases to 20 cm and remains nearly constant thereafter. The activity concentration is almost uniform in the grain sizes of 350-177 μm and below 177 μm. Pterobryopsis tumida (Hook.) Dix, a plant of the moss family, shows a very high level of 210Po activity - 2724 ± 13 Bq kg-1. Seasonal variation studies show elevated levels of 210Po in vegetation during winter. The annual dry deposition rate of 210Po was 53.4 Bq m-2 yr-1. (C) 2000 Elsevier Science Ltd

Cs-137 concentration in the environment of Kaiga of south west coast of India

This paper presents the results of Cs-137 activity in soil and vegetation obtained through a carefully planned pre-operational survey for the establishment of baseline data on background radiation level and distribution of radionuclides in the environment of Kaiga, in the south west coast of India, where two nuclear power reactors of 235 MWe each are under construction, The vertical profile in soil and the seasonal variation in the activity have been studied. Nine commonly available vegetation species of Kaiga region were analyzed for their Cs-137 activity, and the soil-to-plant transfer coefficients were evaluated. Measurements were made by gamma spectrometry method employing a 90 cc HpGe detector and a 3 x 3-inch well type NaI(TI) detector. Results show significant levels of Cs-137 activity in soil samples - ranging from below detection limit (BDL) to 65.4 Bq kg(-1). The mean value of activity observed in 0-5 cm soil profiles of Kaiga environs is significantly higher when compared to the reported values for other environs of India, Depth profile studies show that the Cs-137 activity decreases with the increasing soil depth, and it is below detection limit for depths more than 25 cm, The mean value of effective dose commitment due to the presence of Cs-137 in soil was 167.2 mu Sv. Vegetation samples of the region show elevated Levels of Cs-137 concentration. Epiphytic plants Cymbidium aloifolium (Lo.) Swartz, and Petrobryopsis tumida (Hook,) I)ix. have been identified as bio-indicators to monitor the fallout of this radionuclide in the environment of Kaiga, Seasonal variation studies indicate higher fallout of this radionuclide along with rain