Synthesis of sub-5 nm Co-doped SnO2_2 nanoparticles and their structural, microstructural, optical and photocatalytic properties

A swift chemical route to synthesize Co-doped SnO$_2$ nanopowders is described. Pure and highly stable Sn$_{1-x}$Co$_x$O$_{2-\delta}$ (0 $\le$ x $\le$ 0.15) crystalline nanoparticles were synthesized, with mean grain sizes < 5 nm and the dopant element homogeneously distributed in substitutional sites of the SnO$_2$ matrix. The UV-visible diffuse reflectance spectra of the Sn$_{1-x}$Co$_x$O$_{2-\delta}$ samples reveal red shifts, the optical bandgap energies decreasing with increasing Co concentration. The Urbach energies of the samples were calculated and correlated with their bandgap energies. The photocatalytic activity of the Sn$_{1-x}$Co$_x$O$_{2-\delta}$ samples was investigated for the 4-hydroxylbenzoic acid (4-HBA) degradation process. A complete photodegradation of a 10 ppm 4-HBA solution was achieved using 0.02% (w/w) of Sn$_{0.95}$Co$_{0.05}$O$_{2-\delta}$ nanoparticles in 60 min of irradiation.Comment: 29 pages, 2 tables, 10 figure

Pulmonary function in young females of Kolkata, India – Revisited

Rapid economic and industrial growths imposed significant impact on human health including the pulmonary health. Questions were raised regarding the validity of the existing prediction norms of pulmonary function tests (PFTs) in a particular population. The present study was conducted to investigate the applicability of the existing norms for PFTs in young healthy non-smoking female university students of Kolkata, India. Significant difference was noted in vital capacity (VC), forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1) when the present data were compared with the earlier study in similar population. Correlation statistic revealed significant relationship of age and body height with all the PFT parameters. Body mass had significant correlation with VC, FVC, FEV1 as a percentage of FVC (FEV1%), and peak expiratory flow rate (PEFR). Regression equations have been computed for predicting PFTs from age and body height. There has been a change of PFTs in the studied population for the last couple of decades due to increased environmental pollution in the course of economical and industrial developments. Regression equations computed in this study are not only recommended to predict PFT parameters in the studied population, but they are also considered more reliable owing to their substantially smaller standard error of estimate than those proposed in the previous study

Structural, electrical and magnetic studies of Co:SnO2 and (Co,Mo):SnO2 films prepared by pulsed laser deposition

Here we report on the structural, optical, electrical and magnetic properties of Co-doped and (Co,Mo)-codoped SnO2 thin films deposited on r-cut sapphire substrates by pulsed laser deposition. Substrate temperature during deposition was kept at 500 degrees C. X-ray diffraction analysis showed that the undoped and doped films are crystalline with predominant orientation along the [1 0 1] direction regardless of the doping concentration and doping element. Optical studies revealed that the presence of Mo reverts the blue shift trend observed for the Co-doped films. For the Co and Mo doping concentrations studied, the incorporation of Mo did not contribute to increase the conductivity of the films or to enhance the ferromagnetic order of the Co-doped films. (C) 2012 Elsevier B.V. All rights reserved

Phase growth control in low temperature PLD Co: TiO2 films by pressure

This paper reports on the structural and optical properties of Co-doped TiO2 thin films grown onto (0001)Al2O3 substrates by non-reactive pulsed laser deposition (PLD) using argon as buffer gas. It is shown that by keeping constant the substrate temperature at as low as 310 degrees C and varying only the background gas pressure between 7 Pa and 70 Pa, it is possible to grow either epitaxial rutile or pure anatase thin films, as well as films with a mixture of both polymorphs. The optical band gaps of the films are red shifted in comparison with the values usually reported for undoped TiO2, which is consistent with n-type doping of the TiO2 matrix. Such band gap red shift brings the absorption edge of the Co-doped TiO2 films into the visible region, which might favour their photocatalytic activity. Furthermore, the band gap red shift depends on the films' phase composition, increasing with the increase of the Urbach energy for increasing rutile content. (C) 2012 Elsevier B.V. All rights reserved

Mental health status and perceived burden in caregiving spouses of persons with psychotic illness (a study from India)

Mental illness poses a great deal of burden on other family members, particularly the primary caregiver. In the Indian context for a married person with mental illness, the caregiving burden is usually experienced by the spouse, who is considered to be the ‘natural’ option. This quantitative study used survey methodology to assess caregiving burden in fifty spouses of persons diagnosed with a psychotic illness. Data was collected at a neuro-psychiatric facility in Tiruchirappalli, India. The Depression, Anxiety and Stress Scale and the Burden Assessment Schedule were the instruments administered to assess the mental health status of the spouse and their perceived burden. Findings revealed that the majority of spouses were classified as experiencing ‘severe’ and ‘extremely severe’ in terms of their depression, anxiety and stress levels and ‘high’ in terms of perceived burden. The specific ‘type’ of clinical diagnosis, however, did not differentiate the spouses on the key variables studied. The correlation of these key variables with other background variables has also been examined. The implications of the results of this study for psychosocial intervention have also been discussed in this article

ANTHROPOMETRIC PROFILE, BODY COMPOSITION AND VERTICAL JUMP SCORE IN BOXERS AND SWIMMERS

Background. Vertical jump test (VJT) is used in some sport disciplines to evaluate an individual’s lower extremity power. However, VJT data is unavailable in young Indian boxers and swimmers.Objective. The given study was aimed to evaluate the VJT, anthropometric profile and body composition in young male Indian swimmers and boxers and compare the data with sedentary control group. The study also explored the relationship of VJT with anthropometric parameters and different components of body composition in the studied groups.Methods. Male boxers (n=40), swimmers (n=40) and sedentary subjects (n=40) with similar socio-economic background with age ranging between 21 and 25 years were sampled for the study from Kolkata, India. Body composition was determined by skinfold measurements and VJT was evaluated by Sargent Jump Test.Results. One way ANOVA shows significant (p&lt;0.001) difference in body mass, %fat, total body fat (TF), lean body mass (LBM) and VJT score in boxers, swimmers and sedentary groups. Significant positive correlation of LBM with VJT score was associated with a greater jumping height in swimmers. On the other hand, VJT had significant negative (p&lt;0.05) correlation with sum of all the skinfolds, individual skinfold and total fat in both athlete group as well as in the sedentary group.Conclusion. Significant intergroup difference was found in the studied parameters. VJT scores obtained in all the groups were well comparable. Higher value of body %fat imposed the unfavourable effect towards achieving higher jumping height mainly in sedentary group.KEY WORDS: VJT, boxers, swimmers, %fat, LBM

Mechanical characteristics of microwave sintered silicon carbide

The present work deals with the sintering of SIC with a low melting additive by microwave technique, The mechanical characteristics of the products were compared with that of conventionally sintered products. The failure stress of the microwave sintered products, in biaxial flexure, was superior to that of the products made by conventional sintering route in ambient condition. In firing of products by conventionally sintered process, SiC grain gets oxidized producing SiO2 (-32 wt%) and deteriorates the quality of the product substantially. Partially sintered silicon carbide by such a method is a useful material for a varieties of applications ranging from kiln furniture to membrane material

Mechanical characterization of microwave sintered zinc oxide

The mechanical characterization of microwave sintered zinc oxide disks is reported. The microwave sintering was done with a specially designed applicator placed in a domestic microwave oven operating at a frequency of 2.45 GHz to a maximum power output of 800 Watt, These samples with a wide variation of density and hence, of open pore volume percentage, were characterized in terms of its elastic modulus determination by ultrasonic time of flight measurement using a 15 MHz transducer, In addition, the load dependence of the microhardness was examined for the range of loads 0.1-20 N, Finally, the fracture toughness data (K-IC) was obtained using the indentation techniqu

Unconventional topological phase transition from semimetal to insulator in SnBi2Te4: Role of anomalous thermal expansion

We propose SnBi2Te4 to be a novel candidate material exhibiting temperature (T) mediated transitions between rich topological phases. From a combined theoretical and experimental studies, we find that SnBi2Te4 goes from a low-T topological semimetallic phase to a high-T (room temperature) topological insulating phase via an intermediate topological metallic phase. Single crystals of SnBi2Te4 are characterized by various experimental probes including Synchrotron based X-ray diffraction, magnetoresistance, Hall effect, Seebeck coefficient, magnetization and angle-resolved photoemission spectroscopy (ARPES). X-ray diffraction data confirms an anomalous thermal expansion of the unit cell volume below 100 K, which significantly affects the bulk band structure and hence the transport properties, as confirmed by our density functional theory calculations. Simulated surface states at 15 K agree fairly well with our ARPES data and are found to be robust with varying T. This indirectly supports the experimentally observed paramagnetic singularity in the entire T-range. The proposed coexistence of rich topological phases is a rare occurrence, yet paves a fertile ground to tune various topological phases in a material driven by structural distortion.pages 7, 3 figure