Various skin impedance models based on physiological stratification

Transdermal drug delivery is a non‐invasive method of drug administration. However, to achieve this, the drug has to pass through the complicated structure of the skin. The complex structure of skin can be modelled by an electrical equivalent circuit to calculate its impedance. In this work, the transfer function of three electrical models of the human skin (Montague, Tregear and Lykken Model) based on physiological stratification are analysed. Sensitivity analysis of these models is carried out to consider the extent to which changes in system parameters (different types of R and C as described by different models) affect the behaviour of the model. Techniques like normal of derivative and Hausdorff Distance is also used to study and understand the different curves. Comparison is also made with CPE based model. As Montague Model is the most widely used model, Tregear and Lykken Model are compared with it. It can be commented that out of the above observations Tregear Model at Level 3 can be used for establishing the electrical equivalent of human skin due to its simplicity. However, fractional ordered CPE models provide a good approximation. Future prospect lies in developing a model that characterize both biological properties and physiological stratification.Inspec keywords: electric impedance measurement, transfer functions, biological techniquesOther keywords: skin impedance models, physiological stratification, transdermal drug delivery, noninvasive method, drug administration, electrical equivalent circuit, electrical models, human skin, Lykken models, sensitivity analyses, Montague model, Tregear model, CPE models, constant phase element‐based model, Hausdorff distance     

Synthesis of silver nanoparticles by oleylamine-oleic acid reduction and its use in making nanocable by coaxial electrospinning

In the present study, silver nanoparticles were produced by hydrazine hydrate and oleylamine/oleic acid systems in order to investigate the effects of reducing agents with different strengths on the reduction mechanism. Particle size and size distribution of silver particles produced by slow reducing system were studied in detail by using transmission electron microscopy (TEM), X-Ray Diffraction (XRD), photon correlation spectroscopy (PCS), and surface plasmon resonance spectroscopy (SPR). Finally, reduction mechanism by oleylamine and oleic acid system was clarified and particles with average diameter of 2.7 nm were produced. Nano-sized particles were then placed at the center of the polymer fibers by coaxial electrospinning and nanocable like structures were produced. SEM and TEM were used for the characterization of these cables.     

Commissioning of 3.7 GHz LHCD system on ADITYA tokamak and some initial results

To drive plasma current non-inductively, a lower hybrid current drive (LHCD) system has been designed, fabricated and successfully installed on ADITYA tokamak. The system is designed to launch 120 kW of RF power, at a frequency of 3.7 GHz. The system mainly consists of a high power CW klystron source, a long waveguide transmission line of about 100 m length, a UHV compatible modular waveguide line of about 2.65 m, and a conventional grill type antenna. Independent phase shifters, one each in the eight lines, are used to adjust the antenna phasing and also provides the flexibility to launch a composite spectrum. The antenna is designed to launch lower hybrid waves (LHW) with parallel refractive index (N_||), in the range, 1 < N_|| < 4.5, by appropriately phasing the antenna. Antenna is positioned in the shadow of the poloidal limiter and is provided with 100 mm radial movement to achieve optimum coupling conditions.The complete system development includes design, fabrication and testing of number of waveguide components, modular waveguide lines and their integration. Different cost effective fabrication techniques are adopted to achieve good RF performance. Special attention is paid on the flanged joint seals in the long transmission line to minimize the RF losses. The entire LHCD system is calibrated, especially, in terms of phase, insertion loss and return loss measurements.After the successful integration of the system on ADITYA tokamak, some initial experiments have been carried out to assess the system commissioning and its performance. The experiments were done with a plasma (hydrogen) density of 2-5 × 10¹² cm⁻³ at a toroidal magnetic field of 0.8 T with 10-25 kA of plasma current. Initial results indicate that, good coupling is achieved in the presence of proper edge density. Measurements obtained from second harmonic electron cyclotron emission (ECE) and hard X-ray diagnostics suggest generation of suprathermal electrons in the presence of LH pulse. Plasma current pulse elongation with LH power is observed but needs further investigation to derive conclusions.This paper presents the design, fabrication, testing and integration of the waveguide lines, waveguide components and UHV compatible modular transmission lines of the LHCD system on ADITYA tokamak and discusses some of the initial results.     

Debye temperature of metallic nanowires--an experimental determination from the resistance of metallic nanowires in the temperature range 4.2 K-300 K

We have studied the resistance of metallic nanowires (silver and copper) as a function of the wire diameter in the temperature range 4.2 K-300 K. The nanowires with an average diameter of 15 nm-200 nm and length 6 microm were electrochemically deposited using polycarbonate membranes as template from AgNO3 and CuSO4, respectively. The wires after growth were removed from the membranes by dissolving the polymer in dichloromethane and their crystalline nature confirmed by XRD and TEM studies. The TEM study establishes that the nanowires are single crystalline and can have twin in them. The resistivity data was fitted to Bloch-Gruneisen theorem with the values of Debye temperature and the electron-acoustic phonon coupling constant as the two fit variables. The value of the Debye temperature obtained for the Ag wires was seen to match well with that of the bulk while for Cu wires a significant reduction was observed. The observed increase in resistivity with a decrease in the wire diameter could be explained as due to diffuse surface scattering of the conduction electrons.     

Damage characterization of repeatedly impacted glass fiber reinforced polyester‐armor steel composites with cone beam computed tomography technique

This article utilizes the characterization of single and repeated low velocity impact damage behavior of glass fiber reinforced polyester (GFRP) armor steel composite. Cone beam computed tomography technique (CBCT) was used for damage assessment. Impact energies, maximum loads and the permanent deflection of GFRP, armor steel composites are determined with instrumented drop weight impact test machine. The repeated impact performance and damage resistance were evaluated. On the other hand, preliminary single impact loading tests also performed in order to find the energy levels, which were ranged fully elastic energy level to perforation energy level for GFRP, armor steel composites. Additionally, CBCT was used to provide a novel, multiscale approach for assessing impact damage. Deformation areas of both single and repeatedly impacted GFRP, armor steel composites were assessed three‐dimensionally by CBCT. An innovative approach was used to visualize the internal damages. POLYM. COMPOS., 37:583–593, 2016. © 2014 Society of Plastics Engineers     

Long-term storage stability of biodiesel produced from Karanja oil

Biodiesel is an alternative diesel fuel made from vegetable oil or animal fat. It is more susceptible to oxidation or autoxidation during long-term storage than conventional petrodiesel. Karanja oil methyl ester (KOME) was prepared and stored for a period of 180 days under different storage conditions. The physicochemical parameters, peroxide value (PV) and viscosity (v) of samples were measured at regular interval of time under different storage conditions. The stability of Karanja oil methyl ester (KOME) was studied under different storage conditions. The stability of KOME was improved by adding different antioxidants Tert-Butylated Hydroxy toluene (BHT), Tert-Butylated Hydroxyanisole (BHA), Pyrogallol (PY), Propyl galate (PrG) and Tert-Butyl Hydroxyl Quinone (TBHQ). The effectiveness of three antioxidants BHT, BHA and PrG on Karanja oil methyl ester was examined at varying loading level during the storage period.     

Preparation and Characterization of the Newly Synthesized Metal‐Complexing‐Ligand N‐Methacryloylhistidine Having PHEMA Beads for Heavy Metal Removal from Aqueous Solutions

The aim of this study was to investigate in detail the performance for removal of heavy metal ions of beads composed of poly(2‐hydroxyethyl methacrylate) (pHEMA) to which N‐methacryloylhistidine (MAH) was copolymerized. The metal‐complexing ligand MAH was synthesized by using methacryloyl chloride and histidine. Spherical beads with an average size of 150–200 μm were obtained by the radical suspension polymerization of MAH and HEMA conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, p(HEMA‐MAH) beads had a specific surface area of 17.6 m²/g. The synthesized MAH monomer was characterized by NMR; p(HEMA‐MAH) beads were characterized by swelling studies, FTIR and elemental analysis. The p(HEMA‐MAH) beads with a swelling ratio of 65%, and containing 1.6 mmol MAH/g, were used in the adsorption/desorption experiments. Adsorption capacity of the beads for the selected metal ions, i. e., Cu(II), Cd(II), Cr(III), Hg(II) and Pb(II), were investigated in aqueous media containing different amounts of these ions (10–750 mg/L) and at different pH values (3.0–7.0). Adsorption equilibria were established in about 20 min. The maximum adsorption capacities of the p(HEMA‐MAH) beads were 122.7 mg/g for Cu(II), 468.8 mg/g for Cr(III), 639.4 mg/g for Cd(II), 714.1 mg/g for Pb(II) and 1 234.4 mg/g for Hg(II). pH significantly affected the adsorption capacity of MAH incorporated beads. The chelating beads can be easily regenerated by 0.1 M HNO₃ with high effectiveness. These features make p(HEMA‐MAH) beads a potential candidate for heavy metal removal at high capacity.     

Determination of optimum ejector operating pressures for anodic recirculation in SOFC systems

In this study, a numerical analysis of an ejector for micro combined heat and power system based on 18 kW Solid Oxide Fuel Cell (SOFC) using methane as fuel is presented. An ejector design, which reflects the real system conditions in the view of the flow characteristics, is provided and the ejector performance is numerically investigated for various methane pressure to exhaust pressure ratios and methane inlet temperatures. The results show that the fuel inlet temperature and the pressure ratio of the methane to exhaust significantly affect the steam to carbon ratio (STCR) and entrainment ratio. The higher pressure ratio and methane temperature allow a high entrainment ratio and STCR, but as pressure ratio and methane temperature increase, STCR and entrainment ratio remain unchanged after a specific value. 1140 different scenarios related with the inlet and outlet pressures of the ejector and methane temperature are created to determine the optimum operating conditions. The simulations show that the optimum methane inlet pressure is 7 bar and exhaust pressure is 1.159 bar for the ejector geometry of the interest. The entrainment ratio and STCR are determined as 2.05 and 0.92, respectively at this optimum scenario.