Optimization of Bio-Implantable Power Transmission Efficiency Based on Input Impedance

Recently, the inductive coupling link is the most robust method for powering implanted biomedical devices, such as micro-system stimulators, cochlear implants, and retinal implants. This research provides a novel theoretical and mathematical analysis to optimize the inductive coupling link efficiency driven by efficient proposed class-E power amplifiers using high and optimum input impedance. The design of the coupling link is based on two pairs of aligned, single-layer, planar spiral circular coils with a proposed geometric dimension, operating at a resonant frequency of 13.56 MHz. Both transmitter and receiver coils are small in size. Implanted device resistance varies from 200 Ω to 500 Ω with 50 Ω of stepes. When the conventional load resistance of power amplifiers is 50 Ω, the efficiency is 45%; when the optimum resonant load is 41.89 Ω with a coupling coefficient of 0.087, the efficiency increases to 49%. The efficiency optimization is reached by calculating the matching network for the external LC tank of the transmitter coil. The proposed design may be suitable for active implantable devices.     

Large-Volume Sample Staking of Rice Polyphenols Prior to Their Determination by Non-aqueous Capillary Electrophoresis

A rapid non-aqueous capillary electrophoretic (NACE) method for the separation of (?)-epicatechin (EPI), (+)-catechin (?CAT), kaempferol (KAE), quercetin (QUR), naringanin (NAR), ferulic acid (FA), and p-coumaric acid (p-CA) has been developed and applied to the determination of these compounds in different rice varieties. All seven compounds were separated on capillary of 50 μm?×?68 cm (60-cm effective length) using 20 mmol L^?1 borate buffer of pH 9.0 and 5 % acetonitrile in methanol. Large-volume sample stacking (LVSS) technique was optimized and used to preconcentrate non-detectable polyphenols of white polished rice. Rice extracts were concentrated on-line by LVSS prior to separation by non-aqueous capillary electrophoresis. An improvement of 10–55 times in detectability was achieved with injection at 50 mbar for 30 s followed by voltage inversion (?20 kV) for 5 s. Linear calibration range of 1–300 μg L^?1 and 0.01–60 μg L^?1 was observed for NACE and NACE-LVSS method respectively, with the detection limit of 0.33–2.0 and 0.006–0.19 μg L^?1. Good reproducibility with standard deviations of less than 5 % was achieved. Polyphenol contents of different rice varieties were determined using developed method.     

Selective, simple and economical lead sensor based on ibuprofen derived silver nanoparticles

Lead (Pb) assessment in the environment is highly demanded due to its extreme toxicity associated with many health problems. We synthesized ibuprofen derived silver nanoparticles (Ibu-AgNps) by a simpler method and applied them as excellent voltammetric Pb(II) sensor. Various optimized parameters include, the kind of electrode, concentration of electrolyte, number of drops, deposition potential, stirring rate, nitrogen purging time, initial potential and pH. The fabricated sensor is simple, highly selective, sensitive, stable and reproducible. The sensor works in linear range, 0.1-1500 ppb with lower detection limit (LDL) of 0.01 ppb (∼50 pM) and regression coefficient of 0.999 for Pb(II) ions. RSD of 1.5% was observed for 20 replicates of 1000 ppb Pb(II) solution which proves its excellent reproducibility. No interference was noticed for fabricated sensor by ions commonly found in water. Drinking, tap and river water samples were successfully analyzed for the estimation of Pb(II) ions by the developed sensor.     

Energy Conservation Using RR Algorithm in Dynamic Cluster Based WSN

Wireless Personal Communications - The energy consumption during the cluster head selection phase in a hierarchal and dynamic cluster based wireless sensor network had been considered insignificant...     

Simultaneous Determination of Quercetin,Rutin, Naringin,and Naringenin in Different Fruits by Capillary Zone Electrophoresis

A fast and reliable capillary zone electrophoretic (CZE) method has been developed for the simultaneous determination of four fruit flavonoids using photodiode array (PDA) detector. The effects of CE parameters including concentration and pH of the running buffer, voltage, and injection time were optimized. Under the optimized conditions, all flavonoids were well determined in a 10 mM borate buffer of pH 8.5 within 10 min at an applied voltage of 25 kV. Naringin, naringenin, and quercetin were found to have linear response in the range of 3.12–200 μg/mL whereas rutin’s response was linear from 6.25 to 200 μg/mL. LOD was found to be 0.406, 0.314, 0.582, and 0.333 μg/mL and LOQ 1.355, 1.046, 1.941, and 1.11, respectively. Relative standard deviations (RSD) were found to be less than 3 % for both migration time and peak height which shows long-term stability and good reproducibility of the developed method. The method was successfully applied for the simultaneous determination of flavonoids from various fruit juice samples.     

Microstructure of Continuous Cooled Niobium Steels

This study investigates the transformation behavior and microstructural variations through cooling rates for C-Mn steels with different niobium contents. The ferrite produced at low niobium concentration is quite different from that produced by increasing niobium concentration. The transformation temperature in carbon manganese steels containing niobium is strongly dependent on both the niobium taken into solution and the cooling rate. The maximum depression in transformation temperature is produced by an optimum amount of niobium. This is determined by steel chemistry, particularly the interstitial content of the steel.     

Austenite Grain Size in HSLA

This paper attempts to find a suitable technique for determining prior austenite grain size in mild steel such that it could be used over as wide a range of compositions and temperatures as possible. An effort is also made to trace the reasons behind the failure of any particular technique when applied beyond a specific temperature and composition range. Plain carbon steels, steels with Nb, V, Al, N additions, and steels containing a combination of two or more ofthese elements were studied between 900–1250°C. The investigated methods are applicable to determining austenite grain size developed in the absence of deformation.     

Synthesis and characterisation of hydroxy/fluoroapatite solid solution

Hydroxyapatite (HA) and fluoroapatite (FHA) have been widely investigated as bone substitute and replacement materials. We report here the preparation of hydroxy/fluoroapatite solid solution using wet chemical precipitation method via brushite hydrolysis. Various amounts of sodium fluoride (1–5 mol%) were added during the preparation of hydroxyapatite to form hydroxy/fluoroapatite solid solution. The various experimental techniques like XRD, DTA, TGA, FT-IR and Vicker's hardness measurements were used to characterize the synthesized powders. Thermal analysis of the samples shows only the decomposition reaction of residues formed and the corresponding weight loss due to these reactions. The XRD data of all the samples calcined at 900°C shows well defined peaks of hydroxyapatite and fluoroapatite. The merging of (211) and (112) peak of apatite lattice in the FHA pattern indicates the formation of hydroxy/fluoroapatite solid solution. The decrease in the a-axis of HA lattice parameter indicates the substitution of F^–ion in the OH^–site of HA lattice. The FT-IR spectroscopic studies of the samples confirms the substitution of the F^–ion in the OH^–site of the HA lattice. The Vicker's hardness measurement shows that the hardness value of hydroxy/fluoroapatite solid solution is greater than the hydroxyapatite.