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排序方式: 共有144条查询结果,搜索用时 31 毫秒
31.
Akhilesh Kumar Shakya Ashok Kumar Kutty Selva Nandakumar 《Journal of the Royal Society Interface》2011,8(65):1748-1759
To evaluate the thermo-responsive poly(N-isopropylacrylamide) (PNiPAAm) polymer as an adjuvant, we synthesized PNiPAAm through free radical polymerization and characterized it both in vitro and in vivo. The polymer when mixed with collagen type II (CII) induced antigen-specific autoimmunity and arthritis. Mice immunized with PNiPAAm–CII developed significant levels of CII-specific IgG response comprising major IgG subclasses. Antigen-specific cellular recall response was also enhanced in these mice, while negligible level of IFN-γ was detected in splenocyte cultures, in vitro. PNiPAAm–CII-immunized arthritic mouse paws showed massive infiltration of immune cells and extensive damage to cartilage and bone. As determined by immunostaining, most of the CII protein retained its native configuration after injecting it with PNiPAAm in naive mice. Physical adsorption of CII and the high-molecular-weight form of moderately hydrophobic PNiPAAm induced a significant anti-CII antibody response. Similar to CII, mice immunized with PNiPAAm and ovalbumin (PNiPAAm–Ova) induced significant anti-ovalbumin antibody response. Comparable levels of serum IFN-γ, IL-1β and IL-17 were observed in ovalbumin-immunized mice with complete Freund, incomplete Freund (CFA and IFA) or PNiPAAm adjuvants. However, serum IL-4 levels were significantly higher in PNiPAAm–Ova and CFA–Ova groups compared with the IFA–Ova group. Thus, we show for the first time, biocompatible and biodegradable thermo-responsive PNiPAAm can be used as an adjuvant in several immunological applications as well as in better understanding of the autoimmune responses against self-proteins. 相似文献
32.
Yun Bai Uttandaraman Sundararaj Krishnaswamy Nandakumar 《American Institute of Chemical Engineers》2011,57(10):2657-2669
A nonisothermal transient process of temperature increase due to viscous heating was simulated for a 69 cm3 internal batch mixer (BM) using a computational fluid dynamics (CFD) software, Polyflow 3.9 form ANSYS, Inc., to obtain the temporal temperature distribution and characterize the heat transfer between polymer melt and mixer wall. The melt temperature obtained from simulation was verified with experiments. Starting from a uniform temperature of 463 K, when a rotation speed of 5.24 rad/s is imposed, viscous heating caused a maximum temperature rise of 3 K for a polyethylene (PE) resin, and 6 K for a polystyrene (PS) resin. The transient flow fields inside the batch mixer were characterized with velocity profiles and a mixing index parameter, which show that laminar flow dominates inside the mixer while a small percentage of elongational flow, converging flow, and recirculation flow is also present. © 2010 American Institute of Chemical Engineers AIChE J, 2011 相似文献
33.
C. Ahmed Basha R. Saravanathamizhan V. Nandakumar K. Chitra Chang Woo Lee 《Chemical Engineering Research and Design》2013
Electrochemical treatment of real acidic effluent of copper phthalocyanine dye manufacturing plant with a view to explore the feasibility of the simultaneous removal of copper and phthalocyanine using a bipolar disc electrochemical reactor has been investigated. Experiments were conducted in a bipolar capillary gap disc stack electrochemical reactor under batch recirculation mode. Electrodes were RuO2 and IrO2 coated on titanium as anode and titanium as cathode. Effects of current density, electrolysis time and effluent flow rate on copper recovery and simultaneous COD removal and energy consumption were critically examined. The current density of 2.5 A dm−2 and flow rate of 20 L h−1 achieved 91.1% COD removal and 90.1% copper recovery with the energy consumption of 50.86 kWh kg−1 for COD removal and simultaneous recovery of copper in a bipolar disc stack reactor. 相似文献
34.
M. Venkatachalam M.D. Kannan S. Jayakumar R. Balasundaraprabhu A.K. Nandakumar N. Muthukumarasamy 《Solar Energy Materials & Solar Cells》2008,92(5):571-575
CuInxGa1−xSe2 bulk compound of three different compositions x=0.75, 0.80 and 0.85 have been prepared using individual elements of copper, indium, gallium and selenium. Thin films of CuInxGa1−xSe2 have been deposited using the prepared bulk by electron beam evaporation method. The structural studies carried on the deposited films revealed that films annealed at 400 °C are crystalline in nature exhibiting chalcopyrite phase. The position of the (1 1 2) peak in the X-ray diffractogram corresponding to the chalcopyrite phase has been found to be dependent on the percentage of gallium in the films. The composition of the prepared bulk and thin films has been identified using energy dispersive X-ray analysis. The photoluminescence spectra of the CuInxGa1−xSe2 films exhibited sharp luminescence peaks corresponding to the band gap of the material. 相似文献
35.
Unni Santhosh Yasser Gowayed Greg Ojard Imelda Smyth Sujith Kalarikkal George Jefferson 《Journal of Nondestructive Evaluation》2018,37(2):37
Thermography is one of the Non-Destructive Evaluation methods used to qualitatively estimate the amount of porosity in as-manufactured ceramic matrix composite (CMC) parts. Through-transmission (TT) thermography allows for comparison of thermal diffusivity caused by differences in material density and porosity at different locations in the part. In this study, volume fraction of pores and its distribution in CMC samples containing different amounts of porosity was quantified using optical microscopy and X-ray computed tomography scans. TT thermography was done on the same specimens and images were analyzed to determine the distribution of thermal diffusivity. Comparison of porosity measurements and thermal diffusivity images shows an inverse correlation. A simple two-phase analytical model describing this relationship is derived for composites and its solution is shown to compare favorably with experimental data. In the absence of porosity data, the model can be used to estimate porosity directly from thermal diffusivity data. 相似文献
36.
Preethy Augustine Narayana Yerol Nandakumar Kalarikkal B. Raneesh M.T. Rahul Sobi K. Chacko 《Ceramics International》2021,47(11):15267-15276
The novel functionalities of multiferroic magneto-electric nanocomposites have spawned substantial scope for fast-paced memory devices and sensor applications. Following this, herein we report the development of nanocomposites with soft ferromagnetic MnFe2O4 and ferroelectric BiFeO3 to fabricate a system with engineered multiferroic properties. A modified sol-gel route called Pechini method is demonstrated for the preparation of the (1-x) BiFeO3-x MnFe2O4 (x = 10%, 30%, 50%, 70%) nanocomposites. The crystallographic phase, structure, and morphology are characterized by XRD, FESEM, and HRTEM. The accurate crystallite size and lattice strain are determined by Williamson-Hall plot method and a comparative study with Scherer's equation is carried out. TEM image evidences the interface between BiFeO3 and MnFe2O4 nanoparticles in the composite. The room temperature magnetic response reveals the strong dependence of magnetic saturation, remanent magnetization, and coercivity of the nanocomposites on MnFe2O4 addition. The dielectric response and impedance analysis of the prepared nanocomposites are observed. The electrical performance of the composite is affected by grain, grain boundaries, and oxygen vacancies. The unsaturated P-E loops exhibit the leaky ferroelectric behavior for the nanocomposite. The intrinsic magnetoelectric coupling between ferroelectric BiFeO3 and ferromagnetic MnFe2O4 has been determined by varying Hdc/Hac and its maximum coupling coefficient (α) is found to be 25.39 mV/cmOe for 70% BiFeO3 -30% MnFe2O4 nanocomposite. These distinctive and achievable characteristics of the nanocomposite would enable the designing of magnetic field sensors, spintronic devices, and multiferroic memory devices. 相似文献
37.
Wai Lee Landman P.E. Barton B. Abiko S. Takahashi H. Mizuno H. Muramatsu S. Tashiro K. Fusumada M. Luat Pham Boutaud F. Ego E. Gallo G. Hiep Tran Lemonds C. Shih A. Nandakumar M. Eklund R.H. Ih-Chin Chen 《Solid-State Circuits, IEEE Journal of》1997,32(11):1766-1776
In an effort to extend battery life, the manufacturers of portable consumer electronics are continually driving down the supply voltages of their systems. For example, next-generation cellular phones are expected to utilize a 1-V power supply for their digital component. To address this market, an energy-efficient, programmable digital signal processing (DSP) chip that operates from a 1-V supply has been designed, fabricated, and tested. The DSP features an instruction set and micro-architecture that are specifically targeted at wireless communication applications and that have been carefully optimized to minimize power consumption without sacrificing performance. The design utilizes a 0.35-μm dual-Vt technology with 0.25-μm minimum gate lengths that enables good performance at 1 V. Specifically, the chip dissipates 17 mW at 1 V, achieving 63-MHz operation with a power-performance metric of 0.21 mW/MHz 相似文献
38.
In this study mixed convection heat transfer in a homogeneous porous duct of square cross section in a horizontal orientation is examined. Results from a generalized Forchheimer model are compared with that from the Darcy model. The heat transfer rate and the flow behavior depend on the following parameters: Grashof number, Gr = Q'gβKa/kv2, an axial flow pressure drop parameter, ζ = (aK/vμ)dp'/dz', an inertial parameter ξ = mK/a, appearing in the Forccheimer model and the Prandtl number, Pr = Cpμ/k. In the Darcy limit, ξ → 0, the role of the axial flow parameter, λ is reduced to a mere scale factor and the flow behavior is determined by a single parameter, λ = Gr · Pr. Both the Darcy and the Forchheimer models exhibit dual solutions and a hysteresis behavior over a certain range of Gr. Such parametric dependence can be used as an additional tool along with carefully designed experiments to determine the importance of inertial and Prandtl number effects on convective heat transfer in porous media. 相似文献
39.
A technique for determining the size and wavelength-dependent refractive indices of a droplet coated with a thin layer is presented. The existence of a layer on the droplet is identified by a procedure that involves separate alignments of independently measured TE- and TM-mode resonances with computed homogeneous-sphere resonances. The procedure also yields the mode and the order numbers associated with the measured resonances. The observed resonances are then aligned with layered-sphere resonances of the same mode and order numbers to determine the core radius, layer thickness, and constants of core and shell dispersion formulas that minimize the difference between the observed and the calculated positions of resonances. The technique has been tested with synthetic data with various levels of random errors as well as with experimental data from two droplets under identical conditions. The results show that the core radius, layer thickness, and core and layer refractive indices can be determined with relative errors of 3.5 × 10(-4), 4.5 × 10(-2), 2.3 × 10(-4), and 4.4 × 10(-3), respectively, with the technique. 相似文献
40.
Nandakumar S. Sai Bharadwaj G. V. S. Srivastava Divyanshu 《Wireless Personal Communications》2019,108(1):203-212
Wireless Personal Communications - Cognitive radio networks can achieve high spectrum efficiency through dynamic spectrum allocation to the secondary users (SU) by way of using primary user (PU)... 相似文献