Investigation of the surface properties of heat treated electroless Ni–P coating

Electroless nickel phosphorus (Ni–P) coatings were synthesised from an acid chloride electrolyte. The synthesised coatings were heat treated at different temperatures, and the surfaces of the heat treated coating were characterised using scanning electron microscopy and X-ray diffraction. Adhesion, wettability, hardness and corrosion behaviour of the coatings were measured. The surface morphology showed the formation of a nano crystalline nickel matrix under heat treated condition. X-ray diffraction analysis of the heat treated samples revealed the recrystallisation of nickel and formation of Ni₃P phase in the coatings. The wettabilty study showed that the as-deposited Ni–P coating is hydrophobic and wettability increases to a maximum of 70.8° contact angle for heat treated temperature of 400°C due to nano crystalline formation. The Rockwell C adhesion test revealed the presence of micro cracks with increase in heat treatment temperature, however the failure is within the acceptability limit. The micro hardness of the Ni–P coating increased with increase in heat treatment temperature. Corrosion potential of the Ni–P coating shifted to a positive potential under heat treated conditions owing to oxidation and precipitation of Ni₃P phase. Decreased corrosion rate and corrosion current density (7.37–0.21?µA?cm^?2) is attributed to heat treatment at 400°C.     

Performance of cold sprayed Ni‐20Cr and Ni‐50Cr coatings on SA 516 steel in actual industrial environment of a coal fired boiler

Power plants are one of the major industries suffering from severe erosion–corrosion (E‐C) problems resulting in substantial losses. One way of tackling this problem is by the use of thermal spray coatings. In the current investigation a new emerging technique i.e. cold spray coating process was used to deposit Ni‐20Cr and Ni‐50Cr powder on SA 516 (grade 70) boiler steel. The bare as well as the coated steels were subjected to cyclic experimental studies, in the superheater zone of a coal fired boiler. Weight change, thickness loss, XRD, FE‐SEM/EDS and X‐ray mapping techniques were used to analyse the eroded‐corroded specimens. The uncoated steel showed weight gain after exposure in the actual boiler environment, whereas, for the coated steels there was initial weight loss followed by negligible weight change. Based upon thickness loss data the cold‐sprayed Ni‐50Cr coating was found to provide better E‐C resistance than the Ni‐20Cr coating.     

A new weighted‐sum‐of‐gray‐gases model for oxy‐combustion scenarios

A new weighted‐sum‐of‐gray gases (WSGG) model that is based on the statistical narrow band model (SNB) RADCAL is proposed for use in computational fluid dynamic (CFD) simulations of air and oxy‐combustion. When employed in conjunction with the discrete ordinates (DO) method, the model predictions compare well against line‐by‐line benchmark data that have been made available recently that are based on the latest spectroscopic databases. Furthermore, the model compares well against the EM2C SNB model calculations that have served as benchmark data in three‐dimensional geometries. Radiative transfer calculations in these prototypical problems therefore confirm recent experimental observations that SNB RADCAL and EM2C SNB serve as good model databases to develop approximate radiative property models. To achieve an optimum balance of speed and accuracy in computationally intensive CFD simulations, non‐gray formulations of the WSGG model are also employed with the P1 model and solutions are compared against those generated by the DO model. While the P1 model gave favorable comparisons when cold, black walls were present, the errors in the surface incident radiative flux predictions increased in the presence of hot, reflecting walls. Finally, in fully coupled simulations of natural gas combustion under air‐firing and oxy‐firing modes, the predicted incident radiative flux profiles were distinctly different between the gray and non‐gray calculations at regions of high temperature gradients, while the centerline temperature predictions were comparatively unaffected. The effects of turbulence radiation interactions were also accounted for through the temperature self‐correlation term. However, the magnitudes of the temperature fluctuations were small and localized within this furnace and did not significantly alter our predictions. Copyright © 2012 John Wiley & Sons, Ltd.     

Dye-tolerant marine Acinetobacter baumannii-mediated biodegradation of reactive red

The objective of this study was to isolate a potent dye-degrading microbe that can be used to reduce the pollution caused by industrial dyes.Reactive red 198 is an extensively used textile dye and is a major environmental pollutant in water bodies. In this study, a bacterial strain was isolated from sea sediments and identified as Acinetobacter baumannii with 16S rRNA sequencing. The isolated bacteria were immobilized in calcium alginate and decolorization studies were carried out to determine the optimum pH, temperature, dye concentration, inoculum volume,and static/agitated condition using the one factor at a time(OFAT) approach. The Box-Behnken design, a type of response surface methodology,was adopted to improve the degradation efficiency. At 37℃ using an inoculum volume of six beads, 96.20% decolorization was observed in 500 mg/L of reactive red 198 after 72 h. Dye degradation was confirmed with UV-visible spectroscopy and Fourier-transform infrared(FTIR)spectroscopy studies of the dye and degraded metabolites. Microbial toxicity studies using Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa and phytotoxicity studies using Vigna radiata proved that the toxicity of the dye was significantly reduced after degradation. We can conclude that the isolated A. baumannii strain is an efficient dye-degrading microbe that can be used to reduce the pollution caused by industrial dyes.     

Computer Systems Based on Silicon Photonic Interconnects

We present a computing microsystem that uniquely leverages the bandwidth, density, and latency advantages of silicon photonic interconnect to enable highly compact supercomputer-scale systems. We describe and justify single-node and multinode systems interconnected with wavelength-routed optical links, quantify their benefits vis-a-vis electrically connected systems, analyze the constituent optical component and system requirements, and provide an overview of the critical technologies needed to fulfill this system vision. This vision calls for more than a hundredfold reduction in energy to communicate an optical bit of information. We explore the power dissipation of a photonic link, suggest a roadmap to lower the energy-per-bit of silicon photonic interconnects, and identify the challenges that will be faced by device and circuit designers towards this goal.     

Application of combined temporal and spectral processing methods for speaker recognition under noisy,reverberant or multi-speaker environments

This paper presents an experimental evaluation of the combined temporal and spectral processing methods for speaker recognition task under noise, reverberation or multi-speaker environments. Automatic speaker recognition system gives good performance in controlled environments. Speech recorded in real environments by distant microphones is degraded by factors like background noise, reverberation and interfering speakers. This degradation strongly affects the performance of the speaker recognition system. Combined temporal and spectral processing (TSP) methods proposed in our earlier study are used for pre-processing to improve the speaker-specific features and hence the speaker recognition performance. Different types of degradation like background noise, reverberation and interfering speaker are considered for evaluation. The evaluation is carried out for the individual temporal processing, spectral processing and the combined TSP method. The experimental results show that the combined TSP methods give relatively higher recognition performance compared to either temporal or spectral processing alone.     

Daily intake of manganese by the adult population of Mumbai

The daily intake of manganese (Mn) estimated through air, water and duplicate dietary analysis is found to range from 0.67 to 4.99 mg with a mean value of 2.21 mg. Ingestion through food contributed to the predominant fraction of the intake. The turnover rate of Mn through blood is approximately 2 h, based on the mean concentration of Mn in blood of 1.54 microg l(-1). The average concentrations of Mn in water and air were approximately 1.42 microg l(-1) and 37 ng m(-3), respectively. The daily intake of Mn by the adult population of Mumbai is closer to the lower bound of the recommended limit of 2-5 mg. Electro Thermal Atomic Absorption Spectrophotometry (ET-AAS), has been used for the determination of Mn in a variety of environmental and human biological fluids. The detection limit of Mn for a volume injection of 20 microl is 2 pg absolute. The precision of the method is established by analyzing a synthetic mixture containing various elements in different quantities (0.5-10 ppm) and is found to be within +/- 8%. The reliability of estimation is further assessed through the analysis of Standard Reference Materials (SRMs) of soil, hay, milk powder and fish tissue obtained from IAEA.     

Optical receivers for optoelectronic VLSI

We describe our work on the design and testing of optical receivers for use in optoelectronic VLSI. The local nature of the optoelectronic VLSI system permits novel receiver designs, incorporating multiple optical beams and/or synchronous operation, while the requirement of realizing large numbers of receivers on a single chip severely constrains area and power consumption. We describe four different receiver designs, and their different operating modes. Results include 1-Gb/s high-impedance, two-beam diode-clamped FET-SEED receivers, single and dual-beam transimpedance receivers realized with a hybrid attachment of multiple-quantum well devices to 0.8-μm linewidth CMOS operating to 1 Gb/s, and synchronous sense-amplifier-based optical receivers with low (~1 mW) power consumption. Finally, we introduce a measure of receiver performance that includes area and power consumption     

Plasma amino acids and milk protein production by cows fed rumen-protected methionine and lysine

Eighteen Holstein cows in midlactation were used to study the effectiveness of encapsulated rumen-protected methionine and rumen-protected lysine to deliver methionine and lysine postruminally. The experimental design was a 2 X 2 factorial, a center point, and a control treatment run in a partially balanced, incomplete block design. Treatments were administered over three periods of 3 wk. Cows were fed a blended diet consisting of corn silage, corn, and soybean meal supplemented with five different amounts of rumen-protected methionine and lysine. The amounts of DL-methionine and L-lysine (g/d), respectively, supplied from the encapsulated rumen-protected preparations for the six treatments were 1) 0, 0; 2) 10.40, 18.00; 3) 4.52, 7.82; 4) 16.28, 7.82; 5) 16.28, 28.18; and 6) 4.52, 28.18. In vitro results indicate that amino acids in both of the encapsulated preparations were 94% stable at a pH (5.4), which simulated the rumen, and 94% released at a pH (2.9), which simulated the abomasal environment. A linear increase of plasma methionine and lysine was observed as the amount of methionine and lysine supplied postruminally increased. The concentrations (microgram/ml) of methionine and lysine in plasma for the six treatments were 1) 2.47, 9.05; 2) 3.73, 11.59; 3) 3.60, 11.86; 4) 6.09, 10.45; 5) 5.28, 13.43; and 6) 3.33, 13.27. Rumen-protected lysine increased feed intake, milk yield, and 4% fat-corrected milk production within the surface treatments but had no effect when compared with the unsupplemented control treatment. Rumen-protected methionine and lysine increased production of milk protein. Lysine appeared to improve the utilization of methionine.