ABSTRACT
In the present work, the three-dimensional ultra-fine platinum nanoflowers are directly deposited on carbon-coated gas diffusion layer electrode (C-GDL) by a single-step electrodeposition method towards the application of polymer electrolyte fuel cells. The surface morphology, particle size distribution, crystallinity, and chemical oxidation state of platinum nanoflowers are examined using various techniques. The morphological features of the Pt nanostructures are highly influenced by the difference in current density. Notabely, the Pt nanospheres converts into three-dimensional nanoflower with an increase in current density from -1.6 to -32 mA cm-2. Electrodeposited Pt catalyst on C-GDL as the cathode catalyst was fabricated and steady-state polarization studies were carried out. Mainly, the fuel cell performance is analysed considering the electrodeposited Pt morphology. Among the prepared electrocatalysts, the nanoflower shaped Pt catalyst exhibit a high peak power density of 660 mW cm-2 at 0.6 V in PEFC.
ABSTRACT
This study elucidates the importance of thermal reversibility as it pertains to the minimization of recombinant human Flt3 ligand aggregation and its potential role for determining solution conditions that can achieve the greatest long-term storage stability. Both thermal reversibility and Tm were evaluated as microcalorimetric parameters of stability within the range extending from pH 6 to 9, where the Tm was shown to plateau near 80 degrees C. Within this region, the reversibility was shown to decrease from 96. 6% to 15.2% while the pH was increased from 6 to 9, respectively. Accelerated stability studies conducted at 50 degrees C exhibited rates of aggregation augmented by pH that inversely correlated with the thermal reversibility data. Namely, high thermal reversibility at the Tm plateau correlated with slower rates of aggregation. Enthalpic calorimetric to van't Hoff ratios (DeltaH1/DeltaHv) yielded results close to unity within the plateau region, suggesting that the unfolding of rhFlt3 ligand was approximately two-state. Evidence that unfolding preceded the formation of the aggregate was provided by far-UV CD data of a soluble islolate of the aggregated product exhibiting a 28% loss of alpha-helix offset by a 31% gain in beta-sheet. This information combined with the thermal reversibility data provided compelling evidence that unfolding was a key event in the aggregation pathway at 50 degrees C. Minimization of aggregation was achieved at pH 6 and corroborated by evidence acquired from sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size exclusion data. Correspondingly, the bioactivity was found to be optimal at pH 6. The findings link thermal reversibility to the propensity of Flt3 ligand to aggregate once unfolded in the Tm plateau region and provide a basis for relating the reversibility of thermal denaturation to the prediction of long-term storage stability in aqueous solution.
Subject(s)
Membrane Proteins/chemistry , Membrane Proteins/genetics , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Temperature , Animals , Calorimetry, Differential Scanning , Cell Line , Circular Dichroism , Electrophoresis, Polyacrylamide Gel , Hot Temperature , Humans , Hydrogen-Ion Concentration , Ligands , Membrane Proteins/metabolism , Mice , Oxidation-Reduction , Protein Conformation , Protein Denaturation , Sodium Dodecyl SulfateABSTRACT
Three hundred and fifty three subjects among the rural population of Loni area admitted in the hospital, and 188 medical staff members working in the Rural Medical College and Hospital, Loni, were screened for the presence of HBsAg. Reveresed passive haemagglutination assay was used for screening; it showed an HBsAg positivity rate of 21.8% and 15.8% among hepatitis and non hepatitis cases respectively, and 1.2%, 0% and 4.2% among medical students, doctors and nursing staff respectively. A high HBsAg positivity rate has been observed in the rural population of Loni area.
