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排序方式: 共有816条查询结果,搜索用时 15 毫秒
31.
Upendra Nath Gupta Koteswara Rao Sivaram Pradhan Ratnesh Kumar Jha Harries Muthurajan Venkat Ravi 《International Journal of Applied Ceramic Technology》2008,5(1):101-104
Simple hydroxide precursors were used for the first time for the synthesis of a typical Aurivillius compound (SrBi2 Nb2 O9 (SBN)) at a low temperature. This method is very advantageous because it circumvents the use of SrCO3 in the case of conventional ceramics as well in the coprecipitation methods, thereby lowering the formation of the product phase. Commercially purchased strontium hydroxide is mixed thoroughly with freshly precipitated bismuth and niobium hydroxides in a stoichiometric ratio and heated at different temperatures ranging from 100°C to 750°C for 12 h. The sequence of the reaction and evolution of the product phase was monitored by X-ray diffraction (XRD) studies by recording the XRD for samples calcined at different temperatures. The incipient SBN phase begins to form at temperatures as low as 400°C, and phase formation was complete only at 650°C as revealed by the XRD observations. The differential thermal/thermogravimetric analyses) also corroborate this result. The morphology and average particle size of these powders were investigated by transmission electron microscopy studies. 相似文献
32.
Poly(ethylene oxide) (PEO)/2,6-bis (N-pyrazolyl) pyridine (BNPP) polymer electrolyte based photoelectrochemical cells have been fabricated with [cis-dithiocyanato-N, N-bis (2,2′ bipyridyl-4, 4′ dicarboxylic acid)ruthenium(II)] dihydrate (N3 dye) dye complex as the sensitizer and nanoporous TiO2 film as photo anode. The introduction of 2,6-bis (N-pyrazolyl) pyridine into the poly (ethylene oxide) matrix reduces the crystallinity of the polymer and enhances the mobility of I−/I3− redox couple resulting in an improved performance with a higher conversion efficiency of 8.8% in terms of light energy to electric energy when compared to that of the corresponding dye-sensitized nanocrystalline TiO2 solar cell. 相似文献
33.
Sajal Ghosh Rajesh Ganesan R. Sridharan T. Gnanasekaran 《Journal of Phase Equilibria and Diffusion》2018,39(6):916-932
The ternary phase diagram of LiCl-KCl-NdCl3 system has been investigated by differential thermal analysis (DTA), followed by characterization of the coexisting phases in the solid state by x-ray diffraction, in order to understand the interactions in the NdCl3-LiCl-KCl ternary system. The results of these experiments showed that LiCl and K2NdCl5 form a non binary join section. This divides the LiCl-KCl-NdCl3 system into two quasi-ternary sections, namely (1) LiCl-KCl-K2NdCl5 and (2) LiCl-K2NdCl5-NdCl3 systems. Both are simple eutectic ternary phase diagrams. The ternary eutectic temperatures and eutectic compositions are determined to be 316?±?3 °C and 53.9 mol.% LiCl-38.7 mol.% KCl-7.4 mol.% K2NdCl5 in the LiCl-KCl-K2NdCl5 quasi-ternary section, while the other eutectic temperature and composition are determined to be 376?±?9 °C and 46.2 mol.% LiCl-32.5 mol.% K2NdCl5-21.3 mol.% NdCl3 in the LiCl-K2NdCl5-NdCl3 quasi-ternary section. A quasi-ternary peritectic reaction is observed at 37.7 mol.% LiCl-36.2 mol.% KCl-26.1 mol.% K2NdCl5 at 445?±?1°C. The primary and secondary crystallization temperatures for the samples are deduced from the heating runs of DTA traces, and the phases responsible for the various thermal events are ascertained. Isothermal sections at chosen temperatures and polythermal liquidus projection with isothermal contours are drawn over the ternary phase field. 相似文献
34.
Venkat R. Donuru 《Polymer》2010,51(23):5359-5368
Novel near-Infrared emissive BODIPY polymeric dyes (polymers A and B) were prepared by Sonogashira cross-coupling reaction of 2,6-diiodo BODIPY dyes bearing one and two styryl groups at 3,5 positions (5, 6) with 2,6-diethynyl BODIPY dye, respectively. These polymeric dyes (A and B) display absorption maxima at 697 and 738 nm, and emission maxima at 715 and 760 nm, respectively. These polymeric dyes exhibit significant red shifts in absorption and emission maxima due to their extended π-conjugation systems compared with their BODIPY monomeric dyes. The thin films of polymers A and B display further red shift with emission maxima 764 and 810 nm, respectively. Near-infrared BODIPY copolymeric dye (C) was prepared by Sonogashira polymerization of 2,6-diiodo BODIPY dye bearing two styryl groups with 2,5-diethynyl-3-decylthiophene. For comparison in optical properties, deep-red and red emissive BODIPY copolymeric dyes (D and E) were prepared by Sonogashira polymerization of 2,6-diiodo BODIPY dye bearing monostyryl group and 2,6-diiodo BODIPY dye with 2,5-diethynyl-3-decylthiothene, respectively. These polymers display their absorption maxima at 649 nm and 634 nm, and emission maxima at 694 nm and 669 nm, respectively. All the polymers displayed good thermal stability and solubility in dichloromethane, and their lifetimes ranged from 0.7 to 3.4 ns. 相似文献
35.
Selin Sagbas Suner Subhra Mohapatra Ramesh S. Ayyala Venkat R. Brethanabotla Nurettin Sahiner 《应用聚合物科学杂志》2021,138(24):50576
Catechin (CAT) was crosslinked with trimethylolpropane triglycidyl ether (TMPTGE) to obtain degradable poly(CAT) particles in a single step. Spherical p(CAT) particles with tens of micrometer size range and an isoelectronic point at pH 1.2 were obtained. The hydrolytic degradation of p(CAT) particles provided sustainable and extended release with 264 mg/g CAT release within 10 days at pH 7.4. The antioxidant capacity of 55.0 ± 0.9 μg/ml gallic acid equivalent in terms of total phenol content, and 0.88 ± 0.3 μmol/g trolox equivalent were estimated for p(CAT) particles displaying strong radical scavenging capability. Blood clotting and hemolysis assays demonstrated dose-dependent blood compatibility revealing higher blood compatibility for p(CAT) particles up to 10 μg/ml concentration. The cytotoxicity results show that p(CAT) particles have almost no toxicity for CCD841 normal colon cells at 250 μg/ml concentration in 24 h incubation time giving ~97% cell viability, whereas CAT molecules only provide ~34% cell viability. 相似文献
36.
Ganeriwal S. Tsigkogiannis I. Shim H. Tsiatsis V. Srivastava M.B. Ganesan D. 《Networking, IEEE/ACM Transactions on》2009,17(3):843-856
Radio duty cycling has received significant attention in sensor networking literature, particularly in the form of protocols for medium access control and topology management. While many protocols have claimed to achieve significant duty-cycling benefits in theory and simulation, these benefits have often not translated into practice. The dominant factor that prevents the optimal usage of the radio in real deployment settings is time uncertainty between sensor nodes which results in overhead in the form of long packet preambles, guard bands, and excessive control packets for synchronization. This paper proposes an uncertainty-driven approach to duty-cycling, where a model of long-term clock drift is used to minimize the duty-cycling overhead. First, we use long-term empirical measurements to evaluate and analyze in-depth the interplay between three key parameters that influence long-term synchronization: synchronization rate, history of past synchronization beacons, and the estimation scheme. Second, we use this measurement-based study to design a rate-adaptive, energy-efficient long-term time synchronization algorithm that can adapt to changing clock drift and environmental conditions, while achieving application-specific precision with very high probability. Finally, we integrate our uncertainty-driven time synchronization scheme with the BMAC medium access control protocol, and demonstrate one to two orders of magnitude reduction in transmission energy consumption with negligible impact on packet loss rate. 相似文献
37.
Ramnath Ganesan Anthony Griffo Randall M. German 《Metallurgical and Materials Transactions A》1998,29(2):659-664
Liquid phase sintering (LPS) is a common technique to consolidate materials that are difficult to process by fusion techniques,
such as tungsten heavy alloys. One of the major processing difficulties associated with liquid phase sintered alloys is component
distortion and loss of component shape. In LPS, this distortion is the result of viscous flow driven by curvature effects
and gravity. A finite element model is developed for viscous flow of the semisolid sintering structure using Stokes equations.
This model considers solid volume fraction and effective viscosity of the solid-liquid mixture. The simulation predictions
are compared to distortion results for microgravity and ground-based sintering experiments, and they show good agreement.
The model results indicate that the effective semisolid viscosity is significantly greater than the liquid metal viscosity.
Hence, future work needs to quantitatively examine the factors controlling viscosity and the benefits from such high viscosities
in liquid phase sintered systems. 相似文献
38.
39.
We describe twin girls with bilateral cerebrovascular disease. In one child, a diagnosis of moyamoya disease was made after presentation in infancy with an acute hemiparesis; her asymptomatic sibling was found to have significant bilateral cerebrovascular disease after neuropsychological evaluation and assessment with transcranial Doppler ultrasound. Both subjects showed a discrepancy between verbal and performance IQ and deficits on a test of frontal-lobe function suggesting that these domains should be targeted in cognitive assessment. Family members of subjects with moyamoya are at risk of cerebrovascular disease. Clinical symptoms do not reliably predict disease and those at risk should be offered screening with non-invasive vascular imaging. 相似文献
40.
Sun Young Lee Palanivel Ganesan Joungjwa Ahn Hae-Soo Kwak 《Food science and biotechnology》2011,20(4):927-932
This study was carried out to find the possibility of fermenting yam (Dioscorea opposita Thunb.) with Lactobacillus acidophilus and the protective role on stomach lesion of rats. The solutions of raw and extracted yam used were 2 and 6%, and they were
fermented by L. acidophilus at 37°C for 0, 12, 24, and 36 h. At intervals (0, 12, 24, and 36 h), viscosity, titratable acidity (TA), allantoin, and diosgenin
were examined. In the results, it was observed the most desirable data at 12 h with 6% fermented raw yam (FRY) without any
change in the content of allantoin and diosgenin. In the animal study by rats (Sprague-Dawley), the inhibition ratios on gastric
lesion were 53.41% in FRY. Based on these data, it confirmed that raw yam powder fermented by L. acidophilus would be a functional food with the supplement of viable cells and nutraceutical component of allantoin and diosgenin. 相似文献