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Now showing items 17 - 21 of 21

  • Computer-based formulation design and optimization using Hansen solubility parameters to enhance the delivery of ibuprofen through the skin

    Jameel, Bshaer M.   Huynh, An   Chadha, Aastha   Pandey, Sujata   Duncan, Jacalyn   Chandler, Mark   Baki, Gabriella  

    Trial-and-error approach to formulation development is long and costly. With growing time and cost pressures in the pharmaceutical industry, the need for computer-based formulation design is greater than ever. In this project, emulgels were designed and optimized using Formulating for Efficacy (TM) (FFE) for the topical delivery of ibuprofen. FFE helped select penetration enhancers, design and optimize emulgels and simulate skin penetration studies. pH, viscosity, spreadability, droplet size and stability of emulgels were evaluated. Franz cell studies were performed to test in vitro drug release on regenerated cellulose membrane, drug permeation in vitro on Strat-M (R) membrane and ex vivo on porcine ear skin, a marketed ibuprofen gel served as control. Emulgels had skin compatible pH, viscosity and spreadability comparable to a marketed emulgel, were opaque and stable at 25 degrees C for 6 months. Oleyl alcohol (OA), combined with either dimethyl isosorbide (DMI) or diethylene glycol monoethyl ether (DGME) provided the highest permeation in 24 h in vitro, which was significantly higher than the marketed product (p < 0.01). OA + DGME significantly outperformed OA ex vivo (p < 0.05). The computer predictions, in vitro and ex vivo penetration results correlated well. FFE was a fast, valuable and reliable tool for aiding in topical product design for ibuprofen.
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  • Optimization of organic light emitting diode for HAT-CN based nano-structured device by study of injection characteristics at anode/organic interface

    Jain, Neha   Sinha, O. P.   Pandey, Sujata  

    To increase the current density of the hole only device, 1, 4, 5, 8, 9, 11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) material has been inserted in the device at the indium tin oxide (ITO)/organic interface. Since HAT-CN molecule can withdraw electrons, it can alter electronic properties of the electrodes and hence inserted between the organic/metal interfaces. This paper deals with the optimization of the thickness of organic-metal layers to enhance the efficiency. Also, efforts have been made to increase the current density and reduce the operating voltage of the device. The material 2, 7-bis [N, N-bis (4-methoxy-phenyl) amino]-9, 9-spirobifluorene (Meo-Spiro-TPD) is used to simulate the hole only device because it is a thermally stable hole transport material. Simulated results shows that better current density values can be achieved compared to fabricated one by optimizing the organic metal layer thickness. The best optimized layer thickness of 22 nm for Alq(3), 25 nm for CBP* doped with Ir(ppy)(3), 9 nm for Meo-Spiro TPD and 4 nm for HAT-CN which results in current density of 0.12 A/cm(2) with a reduction in operating voltage by approximately 2 V.
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  • Green's function approach for modeling of electrostatic effects in nanoscale fully depleted double-gate silicon-on-insulator metal-oxide-semiconductor field-effect transistors

    Sharma, Rajiv   Pandey, Sujata   Jain, Shail Bala  

    Exact solution of two-dimensional (2D) Poisson's equation for fully depleted double-gate silicon-on-insulator metal-oxide-semiconductor field-effect transistor is derived using three-zone Green's function solution technique. Framework consists of consideration of source-drain junction curvature. 2D potential profile obtained forms the basis for estimation of threshold voltage. Temperature dependence of front surface potential distribution, back surface potential distribution and front-gate threshold voltage are modeled using temperature sensitive parameters. Applying newly developed model, surface potential and threshold voltage sensitivities to gate oxide thickness have been comprehensively investigated. Device simulation is performed using ATLAS 2D (SILVACO, 4701 Patrick Henry Drive, Bldg. Santa Clara, CA 95054 USA) device simulator, and the results obtained are compared with the proposed 2D model. The model results are found to be in good agreement with the simulated data. Copyright (c) 2013 John Wiley & Sons, Ltd.
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  • A new two-dimensional C-V model for prediction of maximum frequency of oscillation (f(max)) of deep submicron AlGaN/GaN HEMT for microwave and millimeter wave applications

    Tyagi, Rajesh K.   Ahlawat, Anil   Pandey, Manoj   Pandey, Sujata  

    An analytical two-dimensional capacitance-voltage model for AlGaN/GaN high electron mobility transistor (HEMTs) is developed, which is valid from a linear to saturation region. The gate source and gate drain capacitances are calculated for 120nm gate length including the effects of fringing field capacitances. We obtain a cut-off frequency (f(T)) of 120 GHz and maximum frequency of oscillations (f(max)) of 160 GHz. The model is very useful for microwave circuit design and analysis. Additionally, these devices allow a high operating voltage V(DS), which is demonstrated in the present analysis. These results show an excellent agreement when compared with the experimental data. (c) 2008 Elsevier Ltd. All rights reserved.
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  • Capacitance modeling of 120nm AlGaN/GaN HEMT for microwave and high speed circuit applications

    Gupta, R. S.   Haldar, Subhasis   Pandey, Sujata   Kaur, Ravneet   Gupta, Mridula   Gangwani, Parvesh  

    The capacitance-voltage(C-V) and switching characteristics of AlGaN/GaN HEMT has been calculated analytically. The device capacitances and switching parameters; which have been calculated; depends on the basic device parameters and terminal voltages which determine the microwave behavior of a device. The nonvariant nature of this device with drain voltage leads to better device choice for high power microwave frequency.
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