Design and Analysis of a Performance-Optimized CMOS UWB Distributed LNA

In this paper, the systematic design and analysis of a CMOS performance-optimized distributed low-noise amplifier (DLNA) comprising bandwidth-enhanced cascode cells will be presented. Each cascode cell employs an inductor between the common-source and common-gate devices to enhance the bandwidth, while reducing the high-frequency input-referred noise. The noise analysis and optimization of the DLNA accurately accounts for the impact of thermal noise of line terminations and all device noise sources of each CMOS cascode cell including flicker noise, correlated gate-induced noise and channel thermal noise on the overall noise figure. A three-stage performance-optimized wideband DLNA has been designed and fabricated in a 0.18-mum SiGe process, where only MOS transistors were utilized. Measurements of the test chip show a flat noise figure of 2.9 dB, a forward gain of 8 dB, and input and output return losses below -12 dB and -10 dB, respectively, across the 7.5 GHz UWB band. The circuit exhibits an average IIP3 of -3.55 dBm. The 872 mum times 872 mum DLNA chip consumes 12 mA of current from a 1.8-V DC voltage.     

Integrated circuit transmission-line transformer power combiner for millimetre-wave applications

A new approach for power combining several low-voltage CMOS amplifiers using a new on-chip transmission line transformer structure is presented. The power combiner utilises the interconnection of short sections of integrated differential lines and has an efficiency independent of the transformation ratio. Full-wave electromagnetic simulation confirms the operation and low insertion loss of the transformer     

Empirical equations for electrical conductivity and density of Zn,Cd and Mn sulphate solutions in the range of electrowinning and electrorefining electrolytes

Electrical conductivities and densities of acidic zinc, cadmium and manganese sulphate solutions were measured. Empirical equations have been derived to represent the measured values with high accuracy. Electrical conductivity of solutions has been shown to be expressed as a logarithmic function of temperature, a second order polynomial function of sulphuric acid concentration and a linear function of metal ion concentration. It can be deduced that the density of solution can be described as a linear function of metal ion concentration, temperature and sulphuric acid concentration. These equations could be used to improve the electrowinning or electrorefining process conditions.     

Imprinted microspheres and nanoparticles with diclofenac sodium: effect of solvent on the morphology and recognition properties

To achieve suitable properties for specific applications, we synthesized diclofenac sodium (Ds) imprinted polymer beads with controllable size in the range of around 145 nm to 3 µm in diameter by the precipitation polymerization method using methacrylic acid as functional monomer, trimethylolpropane trimethacrylate as crosslinker and azobisisobutyronitrile as initiator. We analyzed the effect of the porogenic solvent on the morphology and recognition of particles. SEM analysis showed some dissimilarity in appearance of the imprinted polymers. The specific surface areas were 246 m² g^–1 and 260 m² g^–1 for imprinted polymers prepared in a mixture of tetrahydrofuran/acetonitrile (MIP1) and tetrahydrofuran/toluene (MIP2) respectively, which were in good agreement with the binding capacities of 150.4 mg g^–1 for MIP1 and 280.4 mg g^–1 for MIP2, but the imprinted nanoparticles with a specific selectivity factor of 1.5 had a better recognition property to Ds than the analog template meclofenamate sodium monohydrate (Ms) and also faster rebinding kinetics or greater accessibility of Ds. Finally the imprinted microspheres were successfully applied as a solid phase extraction sorbent for the extraction of Ds from human urine with limits of detection and quantification of 0.085 mg L^–1 and 0.227 mg L^–1, respectively. © 2013 Society of Chemical Industry     

Electrochemical studies of zinc–cobalt alloy coatings deposited from alkaline baths containing glycine as complexing agent

Co-deposition of Zn–Co alloy coatings that were electrodeposited from weakly alkaline glycine solutions has been studied by cyclic voltammetry. Scanning electron microscopy (SEM), energy depressive spectroscopy (EDS), and X-ray diffraction (XRD) analyses were used to study surface morphology, chemical composition, and phase structure of the coatings. Corrosion behavior of the coatings was also studied using potentiodynamic polarization tests in 3.5 wt% NaCl solution. Cyclic voltammetry results showed that in Zn–Co deposition from an alkaline bath in the presence of glycine, cobalt deposited at a potential near to that of zinc together with successful co-deposition of Co and Zn. It was also shown that reduction–oxidation (redox) reactions of Zn–Co alloy deposits were quasi-reversible and resulted in deviation of electrodeposited alloys from the equilibrium phase diagrams. The corrosion resistance of the deposits was also highly influenced by the composition and morphology of the coatings. Overall, Zn–Co deposit containing 0.89 wt% Co showed that the highest corrosion resistance among the coatings that was due to its single phase structure and fine morphology.     

Controlled release of drugs from gradient hydrogels for high-throughput analysis of cell-drug interactions

In this paper, we report a method to fabricate microengineered hydrogels that contain a concentration gradient of a drug for high-throughput analysis of cell-drug interactions. A microfluidic gradient generator was used to create a concentration gradient of okadaic acid (OA) as a model drug within poly(ethylene glycol) diacrylate hydrogels. These hydrogels were then incubated with MC3T3-E1 cell seeded glass slides to investigate the cell viability through the spatially controlled release of OA. The drug was released from the hydrogel in a gradient manner and induced a gradient of the cell viability. The drug concentration gradient containing hydrogels developed in this study have the potential to be used for drug discovery and diagnostics applications due to their ability to simultaneously test the effects of different concentrations of various chemicals.     

Status of biodiesel research and development in Pakistan

Performance of biodiesel in engines is well established and biodiesel is currently adjudged as a low carbon fuel with the most potential of replacing fossil fuels. The fossil fuel sources are dwindling in Pakistan resulting in importation of about 8.1 million tonnes at approximately US$ 9.4 billion per annum. In the ambit of this justification, augmenting the energy scarce resources in Pakistan through intense harnessing of the varied biodiesel sources can adequately address the deficiency and can ensure energy security. Towards this end, the progress attained in biodiesel related researches in Pakistan are evaluated and presented with the view of highlighting ways of achieving the target set by the Government. A feedstock that drew less attention is spent triglycerides, and the little work reported by some organizations appeared promising. Now the onus is upon organizations such as the Alternative Energy Development Board and Pakistan State Oil to harness the research results from several indigenous Universities and develop a full-scale biodiesel economy in Pakistan.     

Analytical approximate solution of competitive facilitated transport of acid gases through liquid membranes

An analytical approximate solution for the competitive facilitation factor of components A and E across a liquid membrane is developed in the case of instantaneous reactions inside the liquid membranes. This analytical solution solves the dimensionless, nonlinear diffusion-reaction transport problem governing the competitive facilitated transport of two gaseous components through liquid membranes. Prediction of the facilitation factors has been obtained for the equilibrium chemical reaction regime, considering the unequal complexes diffusivities and cases of zero and nonzero permeate side solute concentrations. This mathematical solution leads to analytical expressions for the concentration profiles of the species across the liquid membrane. In comparison with the present numerical solution and also numerical calculations and experimental data from the open literature, the difference between the analytical predictions and those obtained from the numerical solution were found to be in well agreement.