Fatty acids of the lipids of murrels

The fatty acid composition of the body, liver and visceral lipids of four species of murrel, has been determined by argentation column fractionation and gas-liquid chromatography (g.l.c.). Levels of 20:4ω6 (ca 7–22%) unusually high for fish, occur in the majority of lipids analysed. Other predominant components were 16:0, 18:0, 18:1, 18:2ω6, 18:3ω3, 22:4ω6, 22:5ω6, 22:5ω3 and 22:6ω3.     

Ultrafiltration of Banana (Musa acuminata) Juice Using Hollow Fibers for Enhanced Shelf Life

Banana juice was clarified by cross flow ultrafiltration using a hollow fiber module under total recycle mode. Three surface-modified polysulfone-based membrane cartridges with molecular weight cut-offs 10, 27, and 44 kDa were used to identify the most suitable membrane. The effects of operating conditions—namely, transmembrane pressure drop and cross flow rate on the permeate flux and permeate quality, have been investigated. The quality of the clarified juice was evaluated in terms of viscosity, clarity, color, alcohol insoluble solids, total soluble sugar, pH, protein, and polyphenol content. The results showed that the membrane of molecular weight cut-off 27 kDa was suitable. The permeate flux depended strongly on the transmembrane pressure drop, but its variation on cross flow rate was insignificant. The clarified juice had high clarity and no pectineous materials (in terms of alcohol insoluble solids). It contained significant amount of polyphenol and protein. The storage study indicated that the juice could be successfully stored for 1 month without any additive and preservative, keeping its natural nutritional qualities, taste, and flavor intact.     

Effects of nucleating agents on crystallization and microstructure of fluorophlogopite mica-containing glass–ceramics

The alteration of crystallization behavior, microstructure, and thermal properties of fluorophlogopite mica-containing glass–ceramics by nucleating agent is systematically studied. TiO₂, TiO₂ + ZrO₂, and ZrO₂ have been doped as the nucleating agents in the SiO₂–MgO–Al₂O₃–B₂O₃–K₂O–MgF₂ (BMAPS) glass system and prepared by the melt-quench technique. The glass without nucleating agent is also prepared to ascertain the influence of nucleating agent. Addition of nucleating agents effectively increases the softening as well as glass transition temperatures. From the DSC study, it is found that the fluorophlogopite mica crystallization exotherm exhibited in the temperature range 800–850 °C and the activation energy varies in the range 167–182 kJ/mol. The opaque mica glass–ceramics are derived from these BMAPS glasses by a controlled heat treatment process and heat treatment at 1050 °C is found to be optimum. The mica crystals were identified as fluorophlogopite for all the four BMAPS glasses by X-ray powder diffraction (XRD) and subsequently confirmed by FTIR spectroscopy. Excellent matching with fluorophlogopite crystal was obtained in Zirconia-containing glass–ceramic as perceived from the XRD and FTIR studies. The microstructure of interlocked card-like mica flake crystals is found to form as seen from scanning electron microscopy, and such microstructure is obtained when ZrO₂ has been used as nucleating agent. Glass–ceramic without nucleating agent possesses Vickers hardness value 4.58 Gpa and it is increased with addition of the nucleating agent (5.67–6.56 GPa), ZrO₂-containing glass–ceramic possess lower hardness (5.67 GPa) and better machinability. Therefore, ZrO₂ is the most efficient nucleating agent to generate fluorophlogopite mica in these glass–ceramics useable for SOFC applications.     

Implementation of Six Bit ADC and DAC Using Quantum Dot Gate Non-Volatile Memory

This paper presents the implementation of six-bit analog to digital converters (ADCs) and digital-to-analog converters (DACs) using quantum dot gate non-volatile memory (QDNVM). The charge accumulation in the gate region varies the threshold voltage of QDNVM which can be used as a reference voltage source in a comparator circuit. A simplified comparator circuit can be implemented using the quantum dot gate non-volatile memory (QDNVM). In this work, we discuss the use of QDNVM based comparators in designing 6-bit Analog-to-Digital Converters (ADCs) and Digital-to-Analog Converters (DACs).     

Three-State Quantum Dot Gate FETs Using ZnS-ZnMgS Lattice-Matched Gate Insulator on Silicon

This paper presents the three-state behavior of quantum dot gate field-effect transistors (FETs). GeO _x -cladded Ge quantum dots (QDs) are site-specifically self-assembled over lattice-matched ZnS-ZnMgS high-κ gate insulator layers grown by metalorganic chemical vapor deposition (MOCVD) on silicon substrates. A model of three-state behavior manifested in the transfer characteristics due to the quantum dot gate is also presented. The model is based on the transfer of carriers from the inversion channel to two layers of cladded GeO _x -Ge quantum dots.     

Very small aperture terminal broadband shared‐aperture planar antennas

The design and development of a shared‐aperture dual‐band, dual‐polarized, dual‐aperture coupled rectangular microstrip patch antenna element is presented, which is suitable for portable very small aperture terminals. Detailed parametric studies of the locations of orthogonal coupling slots and their influences on the isolation and impedance bandwidth of the antenna element are performed. The experimental results are presented. The prototype dual‐band dual‐polarized antenna element achieves a 21% input impedance bandwidth at the S‐ and C‐bands. The design and development of a four‐element array with such an antenna element is also presented. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 180–193, 2003.     

Shorting strap tunable stacked patch PIFA

An oppositely shorted dual-band stacked patch planar inverted-F antenna (PIFA) is developed. RF switches are integrated to the shorting straps of the stacked patches to make a tunable PIFA. The L band switch yields 0.45-dB insertion loss and 10-dB isolation bandwidth (BW) of 108% at 1.8 GHz. The tunable PIFA yields 10% frequency tunability BW at 745 MHz when the number of upper radiating patch's shorting straps changes and 20% BW at 1137 MHz when the number of lower radiating patch's shorting straps changes. Independent lower and upper frequency tunings are achieved through this technique.     

Synthesis and characterization of low Tg As-S-I chalcohalide glass for processing of raw diamonds

As-S-I chalcohalide glass has been synthesized using elemental sulfur (S), arsenic (As), and iodine (I) in an evacuated sealed silica ampoule. DSC and dilatometry study revealed that the As-S-I glass has very low T_g of only about 50°C, deformation temperature of ~61°C, and high CTE ~68×10⁻⁶ K⁻¹ (40-60°C). Refractive index (n) has been found to vary in the range of 2.3-2.4 which is close to the n value of diamond. When defective diamond pieces are embedded in such glasses, the defects within diamond become visible, enabling the optimized processing of diamonds to get maximum yields.     

Circularly polarized aperture-coupled circular microstrip patchantennas for L-band applications

Circularly polarized aperture-coupled circular microstrip patch antennas are investigated with the goal of obtaining an 8% impedance and ellipticity bandwidth in the L-band. Three varieties-a single-feed patch with perturbation segments, a single-feed stacked patch with perturbation segments, and a dual-feed patch with a 3-dB branch line coupler as an external polarizer are considered to obtain the required performance. All the three investigated patch configurations meet the impedance bandwidth requirement, but only two varieties: the single-feed stacked patch and the dual-feed patch meet the required ellipticity bandwidth. These antennas feature more than 9-dBi gain. They use low-cost substrates and foam for bandwidth enhancement and, hence, they are attractive for applications where the production cost is of importance     

A two-ring circular phased-array antenna for mobile satellitecommunications

This paper presents the design and development of an L-band planar, multi-layer circular array for possible use with the Australian geostationary mobile-satellite-communications system, Mobilesat^TM . Twelve single-feed, stacked aperture-coupled microstrip patches, interleaved with low-cost dielectric foam and arranged in two rings, form the array. The beam-forming network is comprised of three-bit phase shifters, which are located under the antenna elements. Low-cost UHF-band switching diodes were used to minimize the developmental cost of these phase shifters. In order to make the diodes operational at L-band, an LC compensation technique was applied to the diodes to tune out parasitic reactance. Experimental results for individual antenna elements and phase shifters, followed by the results for the entire array, are presented. The indoor testing results for the manufactured antenna showed that the array satisfies the specifications of Mobilesat ^TM. This was also confirmed by outdoor field trials with a NEC S1 transceiver terminal