Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method

The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG) powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC) was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h) with high terminal pH value (>7.80) resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders.     

Molecular dynamics simulations of unfolding and refolding of a β-hairpin fragment of protein G

We have studied the unfolding and refolding pathway of a beta-hairpin fragment of protein G by using molecular dynamics. Although this fragment is small, it possesses several of the qualities ascribed to small proteins: cooperatively formed beta-sheet secondary structure and a hydrophobic "core" of packed side chains. At high temperatures, we find that the beta-hairpin unfolds through a series of sudden, discrete conformational changes. These changes occur between states that are identified with the folded state, a pair of partially unfolded kinetic intermediates, and the unfolded state. To study refolding at low temperatures, we perform a series of short simulations starting from the transition states of the discrete transitions determined by the unfolding simulations.     

Domestic cooking fuel and lung functions in healthy non-smoking women

OBJECTIVE: The objective of this study was to compare the pulmonary functions in healthy non-smoking women who used either biomass or liquified petroleum gas (LPG) as their sole cooking fuel. The effects of passive smoking, ventilation, over crowding and cooking index were also taken into account. METHODOLOGY: The study was conducted over a period of two years from January 1994. One hundred healthy non-smoking women were included 50 cooked solely with biomass and 50 cooked with LPG. A standardised respiratory symptoms questionnaire was administered to all the subjects and spirometry was carried out. RESULTS: Passive smoking showed no significant difference between the two groups. No statistically significant differences was found in lung functions in the two groups except for the PEFR, which was significantly lower (P < 0.01) in women using biomass. No correlation was observed between different variables and pulmonary functions. The step-wise multivariate linear regression analysis showed no correlation between cooking fuel and the pulmonary functions. CONCLUSION: The absence of the expected adverse effects of biomass on pulmonary functions was possibly due to better ventilation in the kitchens of subjects in the biomass group compared to previous studies.     

Respiratory pressures in normal Indian subjects

Regression equations for the prediction of maximum inspiratory pressures (MIP) in North Indian adults are reported, based on observations in 120 females and 153 males. Age and sex were the only significant predictor variables. MIP was significantly related to vital capacity, FEV1 and peak flow rate. The MIP observed in the present study are similar to those reported earlier in Caucasians and Chinese. The lower lung volumes and flow rates in Indians are not explained by differences in MIP.     

Indirect assessment of lung compliance in chronic lung diseases

The slope of the flow volume curves was analysed in 20 normal subjects 28 patients with irreversible chronic airway obstruction, 24 patients with bronchial asthma, 8 patients with diffuse interstitial fibrosis and 7 patients with extensive bronchiectasis. Time constant of the system was taken as the slope of the curve between 50 and 25% of the vital capacity. When considered along with plethysmographically obtained airway resistance, an indirect estimate of the lung compliance was obtained. Significant differences in the estimated lung compliance in the normal subjects, patients with obstructive lung disease or diffuse interstitial fibrosis were demonstrated.     

Peripheral chemoreceptor insensitivity in chronic severe anaemia

Ventilatory response to central and peripheral chemoreceptor stimulation by carbon dioxide was assessed in 15 severely and chronically anaemic subjects before and after the correction of anaemia. Whereas the central CO2 responsiveness was found to be normal in the anaemic state, the peripheral response to CO2 was remarkably depressed. This blunted peripheral response to CO2 was restored to normal with the correction of anaemia.