Carbon fiber‐based deca‐port multiple‐input‐multiple‐output antenna with pattern diversity and high inter‐element isolation

In this article, a deca‐port carbon fiber‐based multiple‐input‐multiple‐output (MIMO) antenna with pattern diversity is presented. The radiating elements of the proposed antenna consist of low cost, light weight, environmental friendly graphite material. The 10 radiating elements of the MIMO antenna are arranged in a group of two (termed as sub‐MIMO structure), in a cubical manner to cover all the propagating directions. Furthermore, the two carbon fiber‐based radiating elements of the sub‐MIMO structure are placed in an orthogonal arrangement to generate different radiation patterns. The antenna exhibits high inter‐element isolation and low envelope correlation coefficient due to orthogonal placement of the radiating elements. The antenna is fabricated and the measured results confirm that the proposed MIMO/diversity antenna may be useful for vehicle‐to‐network applications. The MIMO performance parameters such as diversity gain, total active reflection coefficient, mean effective gain, channel capacity loss are evaluated and found within suitable limits. The three‐dimensional pattern diversity helps to communicate in all directions.     

Comparison of the properties of porous silicon films with different back contacts (Ag, Al) for possible photovoltaic applications

In this work, porous silicon (PS) films were prepared by anodization on polished substrates of (1 0 0) Si for a fixed current density (I_d)20 mA cm⁻² and for a fixed anodization time of 30 min using different screen-printed (SP) back contacts, namely Ag and Al. The properties of PS formed using Ag as the back contact were found to be superior compared to the corresponding film using Al as the back contact. The PS formed with Ag-back contact exhibits higher porosity, negligible photoluminescence (PL) decay, better adherence to the substrate and smooth surface morphology compared to that formed with Al as the back contact for the same current density and time of anodization. Fourier transform infrared (FTIR) studies indicated significant presence of Si–O related features at 1050–1150 cm⁻¹ for PS films formed with Al as back contact, which could be responsible for traps and interface (PS–Si) defect densities as compared to corresponding PS films with Ag as the back contact. Measurements of capacitance–voltage (C–V) and current–voltage (I–V) were used for the investigation of the electrical properties of PS films with different back contacts. The frequency-dependent C–V characteristics were analysed to understand the effects of interface states and traps on the properties of PS films. The results have been analysed in terms of eutectic temperature and back surface field (BSF) across the metal–silicon interface.     

Copper remediation by Eichhornia spp. and sulphate-reducing bacteria

Eichhornia spp. biomass was collected from Chandola Lake, Ahmedabad, Gujarat, India. Point of zero charge of the biomass was pH 7.3. Flask study showed pH 5 and 2–3 h contact time as optimum conditions for copper sorption with 67.25% copper removal. At the end of 24 h of contact time, copper removal reached to 85.0%, from 100 ppm copper containing solution. Copper loading capacity of the biomass ranged between 9.9 and 28.5 mg g^?1 of biomass. To understand the interaction among pH, temperature, presence of nickel and zinc in the system, 2⁴ factorial experiment was performed. Under the experimental conditions pH and interactions between pH–nickel, temperature–pH and temperature–pH–nickel–zinc were found to be significant with 60–74.7% copper removal. Langmuir isotherm was better fit as compared to Freundlich isotherm and pseudo-second order equation gave R² of 0.999 for biosorption kinetic of Eichhornia biomass. Reactor study showed 90% overall copper removal from 24 L of copper containing waste studied and sulphate-reducing bacteria played a significant role. SEMquant element analysis showed increase from 41.66% to 53.93%, 1.02–19.73% and 0.0–12.39% of chloride, aluminium and copper respectively in the loaded biomass as compare to unexposed biomass.     

Oxidative cyanide-free cyanation on arylboronic acid derivatives using aryl/heteroaryl thiocyanate using novel IL-PdCl4 catalyst under mild condition

An efficient and simple method is reported for the cyanation on arylboronic acid using various simple/indole thiocyanates using a new IL-PdCl₄ catalyst. The cascade process involves a coupling reaction without any additive to give a wide range of cyanide derivatives. Cyanation on various arylboronic acids underwent smoothly affording the corresponding arylnitriles in good to high yields.     

Case study of a dust storm over Hyderabad area, India: its impact on solar radiation using satellite data and ground measurements

According to the Earth Observatory dust outbreaks are considered as natural hazards, which affect the ecosystems and human life. The main objective of this study is to assess and monitor the movement of aerosols and pollutants from local or other sources, both natural and anthropogenic, using a combination of ground-based monitoring and satellite data. The turbid and polluted atmosphere in the densely-populated area of Hyderabad, India is further degradated from dust outbreaks originated from Thar desert. A dust event occurred during 10th to 11th April 2006 in the northwest region of India; its plume substantially spreaded across the downwind direction affecting the study region. Using both irradiance measurements and satellite data this dust event is investigated. The analysis shows a significant change in Aerosol Optical Depth (AOD), Aerosol Index (AI) and aerosol-particle size during the dust event. The Aerosol Optical Depth in the dusty day is about 0.2 higher than the previous non-dusty days, while the Angstr?m exponent rapidly decreases when the dust plume affected the study area. The surface PM concentrations show enhanced values during the dusty day directly influenced by the dust deposition. There is also a remarkable decrease in ground-reaching global radiation, UV erythemal (UV(ery)) and other irradiance components. The analysis suggested that the use of the diffuse-to-direct-beam ratio is the most appropriate parameter for the dust monitoring since its values at the longer wavelengths are not affected by the solar zenith angle.     

Plasma Spraying of Lanthanum Chromite Films for Solid Oxide Fuel Cell Interconnection Application

This paper discusses a novel plasma-spraying process for depositing dense LaCrO₃-based interconnection for solid oxide fuel cells (SOFCs). Calcium aluminate was mixed with LaCrO₃ in a slurry containing PVA binder and spray dried to form free-flowing agglomerates. These free-flowing agglomerates were plasma sprayed onto a porous substrate of doped LaMnO₃ and then heat-treated to form a gas-tight and electrically conducting interconnection. Samples of the plasma-sprayed interconnection were characterized for morphology, phase constituents, and coefficient of thermal expansion, as well as electrical resistivity and oxygen nonstoichiometry at 1000°C in the P O₂ range from 1 to} 1× 10^-16 atm. The calcium aluminate additive was found to facilitate densification of the interconnection, most likely through the formation of low-temperature melting phase(s) in the system Ca–Cr–Al–O. A SOFC with such a plasma-sprayed interconnection was fabricated and electrically tested. This cell exhibited good electrical performance, and the interconnection was stable under fuel cell operation conditions.     

Design and implementation of all MOS micro-power voltage reference circuit

In this work we are proposing the all MOST based reference voltage generating circuit, which utilizes the classical principle of addition of two voltages with opposite temperature coefficients. The targeted application of the proposed circuit is a low-dropout regulator which is used in a RF energy harvesting system. The proposed voltage reference circuit is implemented using a standard 0.18 μm CMOS technology. It generates the average reference voltage of 543.658 mV with an average temperature coefficient of 17.43 ppm/°C in the temperature range of ?40 to +85 °C, for the operating supply voltage ranging from 1.25 to 2 V. The maximum power consumption of the proposed architecture is ≈1.5 μW, including power dissipation in bias circuitry and the reference voltage generating core at 2 V supply voltage. The averaged measured line regulation is 1.642 mV/V. The measured power-supply rejection ratio without any filtering capacitor at 100 Hz and 1 MHz are ?62.24 and ?18.94 dB, respectively. Additionally, the measured noise density without any filtering capacitor at 10 Hz and 100 KHz is 20.54 and \(0.30\,\upmu \hbox {V}/\sqrt{\hbox{Hz}}\) , respectively. The proposed circuit has silicon area of ≈0.007 mm².     

“Effect of nano-ZnO particles on the corrosion behavior of alkyd-based waterborne coatings”

A nano-composite was formed by incorporating nano-ZnO in a specially developed alkyd-based waterborne coating to different loading levels. The nano-ZnO based composite coatings were applied on mild steel substrate by dipping. The coated panels were subjected to various test environments like salt-spray, humidity, UV and mechanical tests like scratch and abrasion. The improvement in electrochemical performance and mechanical properties of the composite coatings were evaluated using various analytical techniques. FTIR technique was used to investigate the interaction between nano-ZnO particles and the polymer functionalities. Differential scanning calorimetry (DSC) was done to study the curing behavior of nano-composite coatings. SEM and AFM were used to investigate dispersion of nano-ZnO particles and the changes in the surface behavior of the coatings before and after exposure to the test environment. The result showed that, with increase in the concentration of nano-ZnO there was an improvement in the corrosion resistance, UV resistance and mechanical properties of the coatings indicating the positive effect of addition of nano-ZnO particles in the coatings.     

Study on electrochemical behavior of Nano‐ZnO modified alkyd‐based waterborne coatings

A nano‐composite coating was formed using nano‐ZnO as pigment in different concentrations, to a specially developed alkyd‐based waterborne coating. The nano‐ZnO modified composite coatings were applied on mild steel substrate by dipping. The dispersion of nano‐ZnO particles in coating system was investigated by scanning electron microscopic and atomic force microscopic techniques. The effect of the addition of these nano‐pigments on the electrochemical behavior of the coating was investigated in 3.5% NaCl solution, using electrochemical impedance spectroscopy. Coating modified with higher concentration of nano‐ZnO particles showed comparatively better performance as was evident from the pore resistance (R_po) and coating capacitance (C_c) values after 30 days of exposure. In general, the study showed an improvement in the corrosion resistance of the nano‐particle modified coatings as compared with the neat coating, confirming the positive effect of nano‐particle addition in coatings. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009