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排序方式: 共有217条查询结果,搜索用时 15 毫秒
101.
Gunderi Dhananjaya Prasanna Halepoojar Siddalingappa Jayanna Vishnu Prasad 《应用聚合物科学杂志》2011,120(5):2856-2862
Polyaniline/ZnFe2O4 nanocomposites were synthesized by a simple and inexpensive one‐step in situ polymerization method in the presence of ZnFe2O4 nanoparticles. The structural, morphological, and electrical properties of the samples were characterized by wide angle X‐ray diffraction (WAXD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). WAXD and SEM revealed the formation of polyaniline/ZnFe2O4 nanocomposites. Infrared spectroscopy indicated that there was some interaction between the ZnFe2O4 nanoparticles and polyaniline. The dc electrical conductivity measurements were carried in the temperature range of 80 to 300 K. With increase in the doping concentration of ZnFe2O4, the conductivity of the nanocomposites found to be decreasing from 5.15 to 0.92 Scm−1 and the temperature dependent resistivity follows ln ρ(T) ∼ T−1/2 behavior. The nanocomposites (80 wt % of ZnFe2O4) show a more negative magnetoresistance compared with that of pure polyaniline (PANI). These results suggest that the interaction between the polymer matrix PANI and zinc nanoparticles take place in these nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
102.
Biomass feedstocks available decentrally will be more commodious for localized biorefinery approach than the exhaustive large scale and centralized plants driven by cost intensive technology. Lichen is present in a wide range of habitats in a distributed manner. A maximum hydrolysis of 73%-76% for lichenan from Cetraria islandica, Usnea barbata and Parmelia sp. were obtained in 24 h using lichenase from an alkalothermophilic Thermomonospora sp. wherein the hydrolysis was 100% with commercial enzyme Accellerase™1000. The synergistic role of β-glucosidase in lichenan hydrolysis was demonstrated by the exogenous addition of β-glucosidase to Thermomonospora lichenase which resulted in complete hydrolysis. The hydrolysates of lichenan obtained using Accellerase or a cocktail of Thermomonospora lichenase and β-glucosidase when fermented with free cells of Saccharomyces at 40 °C produced an ethanol yield of 0.45 g/g-0.48 g/g with theoretical conversion efficiencies of 93%-96%. The Ca-alginate immobilized yeast cells were reused eight times at 40 °C with 100% fermentation efficiency. 相似文献
103.
Pei Wen Lau Ranjeet Utikar Vishnu Pareek Stuart Johnson Sandeep Kale Arvind Lali 《Chemical Engineering Research and Design》2013
A novel liquid–solid circulating fluidized bed (LSCFB) was modelled for protein recovery from the feed broth. A typical LSCFB system consists of downer and riser, integrating two different operations simultaneously. A general purpose, extensible, and dynamic model was written based on the tanks-in-series framework. The model allowed adjusting the degree of backmixing in each phase for both columns. The model was validated with previously published data on extraction of bovine serum albumin (BSA) as model protein. Detailed dynamic analysis was performed on the protein recovery operation. The interaction between the riser and downer were captured. Parametric studies on protein recovery in LSCFB system were carried out using the validated model to better understand the system behaviour. Simulation results have shown that both production rate and overall recovery increased with solids circulation rate, superficial liquid velocity in the downer and riser, and feed solution concentration. The model was flexible and could use various forms of ion exchange kinetics and could simulate different hydrodynamic behaviours. It was useful to gain insight into protein recovery processes. The general nature of the model made it useful to study other protein recovery operations for plant and animal proteins. It could also be useful for further multi-objective optimization studies to optimize the LSCFB system. 相似文献
104.
Vishnu Priya M. Ramesh K. Balasubramanian R. Anirbid Sircar 《Chemical Engineering Communications》2019,206(3):409-418
This research article investigates the extraction of bio-oil from Chlorella vulgaris algae which is then subjected to biodiesel production. To evaluate the maximum oil content, four different pretreatment methods and solvent systems were inspected. Among them, maximum oil yield was obtained from ultrasonic pretreated biomass followed by methanol and methyl tertiary butyl ether solvent extraction. Physico-chemical properties of the bio-oil were analyzed as per AOAC Official Methods. The experiments were then designed to determine how variation in different process parameters influences extraction. From these results, kinetic and thermodynamic parameters were also analyzed. The positive values of ΔS and ΔH and the negative value of ΔG indicate that this process is endothermic, irreversible and spontaneous, respectively. The extracted bio-oil was then subjected to acid catalyzed reaction for biodiesel production. A yield of 98.2?wt% biodiesel was obtained at the optimized condition. Fuel properties were analyzed as per ASTM methods. 相似文献
105.
Muddiyada Vishnu Muthamma Shivappa Gudennavar Bubbly Shivappa Bharamappa Gudennavar 《应用聚合物科学杂志》2020,137(44):49366
Epoxy resin filled with suitable high Z elements can be a potential shield for X-rays and γ-rays. In this work, we present the γ-ray attenuation properties of epoxy composites filled with (0–30 wt%) Tantalum pentoxide (Ta2O5) and Ta2O5-Bi2O3, which were prepared by open mold cast technique. X-ray diffraction patterns showed crystalline peaks of Ta2O5 and bismuth oxide (Bi2O3) in the prepared epoxy-Ta2O5 and epoxy-Ta2O5-Bi2O3 composites. Homogeneity of the samples at higher filler wt% was revealed by SEM images. Mechanical characterization showed the enhanced mechanical strength of epoxy-Ta2O5-Bi2O3 composites compared to epoxy-Ta2O5. Higher storage modulus and glass transition temperature of the epoxy-Ta2O5-Bi2O3 composites showed enhanced stiffness and thermal stability when compared to neat and epoxy-Ta2O5. Decrease in the value of tan(δ) at higher content of filler loadings indicated the good adhesion between filler and matrix. Mass attenuation coefficients of epoxy-Ta2O5 (30 wt%) composites at γ-ray energies 59.54 and 662 keV were found to be 0.876 cm2 g–1 and 0.084 cm2 g–1, while that of epoxy-Ta2O5-Bi2O3 (30 wt% Bi2O3) composite were 1.271 cm2 g–1 and 0.088 cm2 g–1, respectively. The epoxy-5% Ta2O5-30% Bi2O3 composites with higher μ/ρ value and tensile strength may be a potential γ-ray shield in various radiation environments. 相似文献
106.
Rai Vishnu Shankar Prajapati Dinesh Verma Manish Kumar Kumar Vinod Pandey Santosh Das Tapas Singh N. B. Mandal K. D. 《Journal of Materials Science: Materials in Electronics》2022,33(18):14868-14881
Journal of Materials Science: Materials in Electronics - Zn-doped and undoped BCTO ceramics (Bi2/3Cu3?xZnxTi4O12, where x?=?0, 0.05, 0.1, and 0.2) were prepared by semi-wet... 相似文献
107.
Emerging Role of the Band‐Structure Approach in Biohybrid Photovoltaics: A Path Beyond Bioelectrochemistry
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Sai Kishore Ravi Vishnu Saran Udayagiri Lakshmi Suresh Swee Ching Tan 《Advanced functional materials》2018,28(24)
Emulation of natural photosynthesis is central to modern photovoltaic research targeting sustainable and economic ways of solar energy harvesting. Natural photosynthetic systems have succeeded in efficiently harvesting solar energy which is key to the sustenance of life on earth. With numerous advances in understanding the structure and function of the natural photosystems, the last decade has witnessed new perspectives in developing bioinspired photovoltaics. Interestingly, organic photovoltaics (OPVs) adopting photosynthetic design principles and biophotovoltaics (BPVs) adopting solid‐state device architectures have now converged at a juncture. Several reports in recent years point to a new scope of improvement in OPVs and BPVs stemming from mutual inspiration. At this juncture, there are new perspectives by which a BPV can be designed that were previously limited only to conventional optoelectronics. Treating natural pigment–proteins as optically and electronically functional materials in any photovoltaic design, from the band‐theory viewpoint, is a promising direction for advancing BPVs beyond the boundaries of bioelectrochemistry. This article presents an overview of selected reports on BPVs in the last few years utilizing new design concepts based on band‐theory and its associated principles. In light of this, the scope of the band‐structure approach in BPVs is discussed, eliciting prospective research directions. 相似文献
108.
Jinto Thomas Ajai Kumar Vishnu Chaudhari Kaushal PandyaRanjeet Singh 《Fusion Engineering and Design》2012,87(2):134-140
Five-channel interference filter polychromator is designed and fabricated for measuring electron temperature and density from Thomson scattered spectrum of SST-1 tokamak plasma. The instrument is designed for measuring electron temperature in the range of 20 eV-3 keV and electron density of 1018-1019 m−3. Optical ray tracing software, Zemax is used for simulating and optimizing the optical design. Each polychromator is a stand-alone unit with field programmable gate array (FPGA) based controller unit for easy operation, monitoring of the temperature variation of the instrument and communicating to a central personal computer (PC). The control unit also protects the avalanche photo diode (APD) detectors from damage due to high current flow, sets the slow channel gain and switches on the biasing power supply. Characteristics of the present polychromator design are relatively high signal throughput and variable bandwidth selection of filters combined with a stable, low cost and relatively simple configuration. Filter selection, arrangement order of filters, statistical error analysis, mechanical and optical design and estimation of electron temperature and density are discussed in this article. The fabricated filter polychromator is tested for its image quality, optical alignment, and integrated performance. 相似文献
109.
Vishnu Vardhan K. Mohammed S.K. Chockalingam A. Sundar Rajan B. 《Selected Areas in Communications, IEEE Journal on》2008,26(3):473-485
We consider large MIMO systems, where by 'large' we mean number of transmit and receive antennas of the order of tens to hundreds. Such large MIMO systems will be of immense interest because of the very high spectral efficiencies possible in such systems. We present a low-complexity detector which achieves uncoded near-exponential diversity performance for hundreds of antennas (i.e., achieves near SISO AWGN performance in a large MIMO fading environment) with an average per-bit complexity of just O(NtNr), where Nt and Nr denote the number of transmit and receive antennas, respectively. With an outer turbo code, the proposed detector achieves good coded bit error performance as well. For example, in a 600 transmit and 600 receive antennas V-BLAST system with a high spectral efficiency of 450 bps/Hz (using BPSK and rate-3/4 turbo code), our simulation results show that the proposed detector performs to within about 7 dB from capacity. This practical feasibility of the proposed high-performance, low-complexity detector could potentially trigger wide interest in the theory and implementation of large MIMO systems. We also illustrate the applicability of the proposed detector in the low-complexity detection of high-rate, non-orthogonal space-time block codes and large multicarrier CDMA (MC-CDMA) systems. In large MC-CDMA systems with hundreds of users, the proposed detector is shown to achieve near single-user performance at an average per-bit complexity linear in number of users, which is quite appealing for its use in practical CDMA systems. 相似文献
110.
Vishnu?PareekEmail author Vinod?K.?Srivastava Adesoji?A.?Adesina 《Korean Journal of Chemical Engineering》2003,20(2):328-333
A model has been proposed for the scavenging of NO2 in a falling raindrop. After absorption, aqueous NO, undergoes a second order reaction to form various ions such as NO
2
-
, NO
3
-
and H+. The model is based on the unsteady state convective diffusion equation, which was solved for given boundary conditions by
using implicit alternate direction (ADI) method. The circulation of fluid inside and outside the raindrop has been taken into
account to realistically describe the flow field in the numerical domain. The model predictions indicate that the pH of a
raindrop is a direct function of the drop size and bulk concentration of NO,. The model predicted a pH of about 4.9 for a
100-micron raindrop falling through a 20-ppb ambient concentration of NO2. For the same ambient concentration of NO2, a 10-micron raindrop would have a pH of about 4.75. The predictions also suggested that for all practical purposes the gas
phase resistance may be taken as the rate-controlling step. The predicted values of gas-side mass transfer coefficient compared
well with the estimated values using standard mass transfer correlations. 相似文献