Electrochemical oxidation of boron containing compounds on titanium carbide and its implications to direct fuel cells

Electrochemical oxidation of sodium borohydride (NaBH₄) and ammonia borane (NH₃BH₃) (AB) have been studied on titanium carbide electrode. The oxidation is followed by using cyclic voltammetry, chronoamperometry and polarization measurements. A fuel cell with TiC as anode and 40 wt% Pt/C as cathode is constructed and the polarization behaviour is studied with NaBH₄ as anodic fuel and hydrogen peroxide as catholyte. A maximum power density of 65 mW cm⁻² at a load current density of 83 mA cm⁻² is obtained at 343 K in the case of borhydride-based fuel cell and a value of 85 mW cm⁻² at 105 mA cm⁻² is obtained in the case of AB-based fuel cell at 353 K.     

Solvothermal synthesis and characterization of acicular α-Fe2O3 nanoparticles

Nanometer-sized α-Fe₂O₃ particles have been prepared by a simple solvothermal method using ferric acetylacetonate as a precursor. The products were characterized by X-ray diffraction (XRD), energy dispersive X-ray microanalysis (EDAX), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transition electron microscopy (TEM), infrared spectroscopy (IR) and thermal analysis (TG-DTA). XRD indicates that the product is single-phase α-Fe₂O₃ with rhombohedral structure. Bundles of acicular shaped nanoparticles are seen in TEM images with an aspect ratio ～ 12; typically 8–12 nm wide and over 150 nm long. The α-Fe₂O₃ nanoparticles posses a high thermal stability, as observed on thermal analysis traces.     

Biomimetic Multienzyme Complexes Based on Nanoscale Platforms

Inspired by the widely present multienzyme complexes in nature that enable highly cooperative catalytic mechanisms, we designed a biomimetic dual‐functionalized nanoparticle‐based platform for colocalizing multiple enzymes. The use of nanoscale materials together with a novel sequential colocalization approach with two model enzymes [glucose oxidase (GOX) and horseradish peroxidase] resulted in a 100% increase in the overall conversion rate compared to the equivalent amount of free enzymes in solution and a physical mixture of individual immobilized enzymes on nanoparticles. GOX is an important enzyme used in glucose biosensors for diagnostics. Colocalizing GOX with peroxidase allows for colorimetric visualization of the peroxide formed that enables monitoring glucose levels in solution. This platform can be readily applicable to other multienzyme systems as well. © 2012 American Institute of Chemical Engineers AIChE J, 59: 355–360, 2013     

Effect of surface radiation on RBC in cavities heated from below

Numerical investigations of combined free convection and surface radiation in enclosures for Rayleigh–Benard configuration of air are carried out using FLUENT 6.3, with a view to determine the onset of convection and to propose correlations for convection and radiation Nusselt numbers based on a detailed parametric study. The onset of Rayleigh–Benard convection is delayed with an increase in the emissivity of the sidewalls. The effect of surface radiation on the onset of convection however diminishes with aspect ratio (AR) and for AR = 8, the effect of surface radiation ceases. Post-onset, the effect of surface radiation on the convection heat transfer becomes insignificant beyond an aspect ratio of 5.     

A correlation for dispersed phase axial mixing coefficients in rotating disc contactors

A correlation for the estimation of dispersed phase axial mixing coefficients in terms of all the operating and fundamental variables was established. The proposed correlations are found to be a good representation of the present data (260 data points) obtained using four liquid‐liquid systems from two different sources. Copyright © 2005 Society of Chemical Industry     

Regression Model for Daily Maximum Stream Temperature

An empirical model is developed to predict daily maximum stream temperatures for the summer period. The model is created using a stepwise linear regression procedure to select significant predictors. The predictive model includes a prediction confidence interval to quantify the uncertainty. The methodology is applied to the Truckee River in California and Nevada. The stepwise procedure selects daily maximum air temperature and average daily flow as the variables to predict maximum daily stream temperature at Reno, Nev. The model is shown to work in a predictive mode by validation using three years of historical data. Using the uncertainty quantification, the amount of required additional flow to meet a target stream temperature with a desired level of confidence is determined.     

Interleukin-2 mutants with enhanced {alpha}-receptor subunit binding affinity

Stimulation of T-cells by IL-2 has been exploited for treatmentof metastatic renal carcinoma and melanoma. However, a narrowtherapeutic window delimited by negligible stimulation of T-cellsat low picomolar concentrations and undesirable stimulationof NK cells at nanomolar concentrations hampers IL-2-based therapies.We hypothesized that increasing the affinity of IL-2 for IL-2R     

Fault-tolerant systems

Two mishaps early this year forcefully reminded the authors how important computer systems' reliability has become to human well-being in this last decade of the 20th century. In January, large parts of AT&T's long-distance telephone switching networks failed because of a software problem. Then, in February, a `fly by wire' Airbus A320 aircraft crashed in Bangalore, India. While a definitive cause for the accident has yet to be established (preliminary investigations suggest that the control computers might well have performed to specifications), the fact that the A320 employs a fully electronic cockpit with no mechanical backup for control has raised much speculation about the computers' role in the crash. The authors stress that the basic idea behind building in a fault tolerant capability is to provide the system with extra (redundant) resources     

Detection of wave groups from the motion behaviour of a discus buoy

A scale modeled discus data buoy was tested for its motion characteristics under the action of wave groups of different frequencies in a wave tank. The wave groups were theoretically simulated based on the methodology of Xu et al., (1993, Statistical simulation of wave groups, Applied Ocean Research, 15, 217–226) and then converted to paddle displacement signals to drive the wave maker. The motion responses of the buoy model were measured using potentiometers as well as with a non-contact motion tracking camera system. The details of the model, instrumentation, testing conditions and the analysis are presented. The displacement and wave elevation time histories were analysed through statistical, envelope, wavelet transform and phase-time approaches to detect the wave groupiness. The effect of groupiness parameters on the surge, heave and pitch motions of the buoy are detailed in this paper.     

Enhanced near-infrared to green upconversion from Er3+-doped oxyfluoride glass and glass ceramics containing BaGdF5 nanocrystals

In this work, effect of glass composition as well as ceramization on visible and near-infrared (NIR) luminescence properties along with their decay dynamics of Er³⁺ ions has been compared considering two different oxyfluoride glasses yielding BaF₂ and BaGdF₅ nanocrystals. Both the glass systems have exhibited an intense normal and upconversion green emission under ultraviolet (378 nm) and NIR (978 nm) excitations, respectively. A remarkable enhancement of these emission intensities is observed for gadolinium-(Gd) containing glasses. Interestingly, NIR fluorescence intensity from Er³⁺ ions at 1540 nm has showed marginal decrease in gadolinium-containing glass which is attributed to occurrence of strong excited-state absorption (ESA) due to higher fluorine content ensuing an augmentation of upconversion green emission with a concomitant decrease in NIR emission. The quadratic dependence of upconversion green emission intensity on its pump power for all the samples revealed biphotonic absorption process from ground-state ⁴I_15/2 to the excited-state ⁴I_11/2 followed by ESA of second photon to the ⁴F_7/2 level. The intense green upconversion emission as well as enhanced NIR fluorescence lifetimes indicate the suitability of these glass/glass ceramics for upconversion lasers and amplification in the third telecom window.