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991.
A group code defined over a group G is a subset of Gn which forms a group under componentwise group operation. The well known matrix characterization of MDS (Maximum Distance
Separable) linear codes over finite fields is generalized to MDS group codes over abelian groups, using the notion of quasideterminants
defined for matrices over non-commutative rings. 相似文献
992.
Nanoparticles of Cr2O3 are prepared through hydrothermal synthesis process using CrO3/PVA in aqueous solution using sucrose as a reducing agent. The calcination temperature is taken 300 and 350 °C. XRD and SEM of the powdered Cr2O3 particles are done for the characterization. The average particle size is found 30–80 nm. It is found that average particle size increases with calcination temperature. The UV–visible absorption spectra are taken for the study of photo-physical properties of ferrofluids. Ultrasonic velocity and absorption measurements are performed in Cr2O3 ferrofluid using variable path interferometer and pulse-echo techniques, respectively. The achieved results are discussed in correlation with the magnetic and other physical properties of Cr2O3. 相似文献
993.
Investigating structural aspects to understand the putative/claimed non‐toxicity of the Hg‐based Ayurvedic drug Rasasindura using XAFS 下载免费PDF全文
Nitya Ramanan Debdutta Lahiri Parasmani Rajput Ramesh Chandra Varma A. Arun T. S. Muraleedharan K. K. Pandey Nandita Maiti S. N. Jha Surinder M. Sharma 《Journal of synchrotron radiation》2015,22(5):1233-1241
XANES‐ and EXAFS‐based analysis of the Ayurvedic Hg‐based nano‐drug Rasasindura has been performed to seek evidence of its non‐toxicity. Rasasindura is determined to be composed of single‐phase α‐HgS nanoparticles (size ~24 nm), free of Hg0 or organic molecules; its structure is determined to be robust (<3% defects). The non‐existence of Hg0 implies the absence of Hg‐based toxicity and establishes that chemical form, rather than content of heavy metals, is the correct parameter for evaluating the toxicity in these drugs. The stable α‐HgS form (strong Hg—S covalent bond and robust particle character) ensures the integrity of the drug during delivery and prevention of its reduction to Hg0 within the human body. Further, these comparative studies establish that structural parameters (size dispersion, coordination configuration) are better controlled in Rasasindura. This places the Ayurvedic synthesis method on par with contemporary techniques of nanoparticle synthesis. 相似文献
994.
Brown AT Ou X James LP Jambhekar K Pandey T McCullough S Chaudhuri S Borrelli MJ 《Magnetic resonance imaging》2012,30(2):283-289
Acetaminophen (APAP) toxicity is responsible for approximately half of all cases of acute liver failure in the United States. The mouse model of APAP toxicity is widely used to examine mechanisms of APAP toxicity. Noninvasive approaches would allow for serial measurements in a single animal to study the effects of experimental interventions on the development and resolution of hepatocellular necrosis. The following study examined the time course of hepatic necrosis using small animal magnetic resonance imaging (MRI) following the administration of 200 mg/kg ip APAP given to B6C3F1 male mice. Mice treated with saline served as controls (CON). Other mice received treatment with the clinical antidote N-acetylcysteine (APAP+NAC). Mouse liver pathology was characterized using T1- and T2-weighted sequences at 2, 4, 8 and 24 h following APAP administration. Standard assays for APAP toxicity [serum alanine aminotransaminase (ALT) levels and hematoxylin and eosin (H&E) staining of liver sections] were examined relative to MRI findings. Overall, T2 sequences had a greater sensitivity for necrosis and hemorrhage than T1 (FLASH) images. Liver injury severity scoring of MR images demonstrated increased scores in the APAP mice at 4, 8 and 24 h compared to the CON mice. APAP+NAC mice had MRI scores similar to the CON mice. Semiquantitative analysis of hepatic hemorrhage strongly correlated with serum ALT. Small animal MRI can be used to monitor the evolution of APAP toxicity over time and to evaluate the response to therapy. 相似文献
995.
Prashant K. Sharma Ranu K. Dutta Prashant K. Singh Avinash C. Pandey 《Journal of luminescence》2009,129(6):605-950
Surface effects significantly influence the functionality of semiconductor nanocrystals. In the current work we present synthesis of ZnO quantum dots (QD) vis-a-vis symmetrically dispersed ZnO quantum dots embedded in SiO2 matrix and discussed their optical properties to understand the role of the surface effects. These nanomaterials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared (FTIR), absorption (UV-visible) and photoluminescence (PL) spectroscopy. TEM studies confirm the formation of ZnO nanophosphors inside the SiO2 matrix in highly symmetrical manner. These symmetrically dispersed ZnO@SiO2 nanophosphors exhibited enhanced stable emission over uncoated sample and would permit the conjugation of the nanocrystals to biological entities after functionalization. Furthermore, the mechanism behind the formation of symmetrically dispersed ZnO quantum dots embedded in SiO2 matrix was discussed in detail. 相似文献
996.
Non‐fragile synchronization control for complex networks with additive time‐varying delays 下载免费PDF全文
In this article, a synchronization problem for complex dynamical networks with additive time‐varying coupling delays via non‐fragile control is investigated. A new class of Lyapunov–Krasovskii functional with triple integral terms is constructed and using reciprocally convex approach, some new delay‐dependent synchronization criteria are derived in terms of linear matrix inequalities (LMIs). When applying Jensen's inequality to partition double integral terms in the derivation of LMI conditions, a new kind of linear combination of positive functions weighted by the inverses of squared convex parameters appears. To handle such a combination, an effective method is introduced by extending the lower bound lemma. Then, a sufficient condition for designing the non‐fragile synchronization controller is introduced. Finally, a numerical example is given to show the advantages of the proposed techniques. © 2014 Wiley Periodicals, Inc. Complexity 21: 296–321, 2015 相似文献
997.
Electromagnetic study of organic photovoltaic cells design shows that electrical parameters depend drastically on the active area geometry: we theoretically show that electrical parameters are altered when the cell length becomes greater than one centimeter. Experimental verification is provided with simple molecular heterojunction cells with areas from 0.03 to 0.78 cm2. 相似文献
998.
Prashant K. Sharma Manvendra Kumar Avinash C. Pandey 《Journal of nanoparticle research》2011,13(4):1629-1637
Copper doped ZnO nanoparticles were synthesized by a chemical technique based on a hydrothermal method. The crystallite sizes,
estimated by XRD and TEM/SEM for different doping percentage of Cu2+ (1–10%), were found to be in the range of ~10–15 nm. TEM/SEM images showed formation of uniform nanorods, the aspect ratio
of which varied with doping percentage. Photoluminescence (PL) measurement showed strong green visible emission and PL intensity
was found enhanced with increase in doping percentage. The increase in the PL intensity was mainly due to Cu incorporation
in ZnO lattice. Currently, light-emitting diodes (LEDs) giving ultraviolet emission have been combined with broad-band visible
green phosphors to make white-light LEDs. Thus, green luminescent ZnO:Cu2+ nanoparticles are seen as necessary and condemnatory constituent for white-light generation from UV LEDs, underlying the
importance of the current work. 相似文献
999.
Location coverage models with demand originating from nodes and paths: Application to cellular network design 总被引:3,自引:0,他引:3
Elif Tokar Erdemir Rajan Batta Seth Spielman Peter A. Rogerson Alan Blatt Marie Flanigan 《European Journal of Operational Research》2008,190(3):610-632
Location covering problems, though well studied in the literature, typically consider only nodal (i.e. point) demand coverage. In contrast, we assume that demand occurs from both nodes and paths. We develop two separate models – one that handles the situation explicitly and one which handles it implicitly. The explicit model is formulated as a Quadratic Maximal Covering Location Problem – a greedy heuristic supported by simulated annealing (SA) that locates facilities in a paired fashion at each stage is developed for its solution. The implicit model focuses on systems with network structure – a heuristic algorithm based on geometrical concepts is developed. A set of computational experiments analyzes the performance of the algorithms, for both models. We show, through a case study for locating cellular base stations in Erie County, New York State, USA, how the model can be used for capturing demand from both stationary cell phone users as well as cell phone users who are in moving vehicles. 相似文献
1000.
Jyoti Pandey 《Tetrahedron》2009,65(45):9350-84
An organocatalytic multicomponent reaction involving 3,4-dihydro-(2H)-pyran, aromatic aldehydes, and urea/thiourea as substrates and l-proline/TFA as catalyst afforded hexahydropyrano pyrimidinones (thiones) in good yields. The method is simple, economical, and ecofriendly to generate hexahydropyrano pyrimidinones as precursors for many biologically active molecules and fused oxazines (PA-824), the lead molecules for tuberculosis chemotherapy. 相似文献