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141.
Francesco dellIsola Emilio Turco Anil Misra Zacharias Vangelatos Costas Grigoropoulos Vasileia Melissinaki Maria Farsari 《Comptes Rendus Mecanique》2019,347(5):397-405
In this paper, we reveal that the mathematical discrete model of Hencky type, introduced in [1], is appropriate for describing the mechanical behavior of micro-metric pantographic elementary modules. This behavior does not differ remarkably from what has been observed for milli-metric modules, as we prove with suitably designed experiments. Therefore, we conclude that the concept of pantographic microstructure seems feasible for micro-metrically architected microstructured (meta)materials as well. These results are particularly indicative of the possibility of fabricating materials that can have an underlying pantographic microstructure at micrometric scale, so that its unique behavior can be exploited in a larger range of technological applications. 相似文献
142.
A comprehensive numerical study has been done to investigate two-dimensional, steady state, conjugate natural heat convection in the hemi spherical lower plenum of a fast breeder reactor under failed conditions. The continuity, momentum and energy equations are solved over the entire domain, using the corresponding properties for the solid and fluid regions. The control volume approach is employed in order to discretize the governing equations for their numerical solution. A parametric study has been done to study the variation of the velocity vectors and isotherms for different constant temperature of the heat source, simulating different heat generation rates. The actual problem in a nuclear reactor involves a volumetric heat generation in the debris falling over the heat shield plate under failed conditions of the reactor and heat is removed by a decay heat exchanger serving as a sink. In this study we have reduced this transient problem to a quasi-steady problem with a prescribed temperature on the heat shield plate. This makes the problem more tractable. The fluid flow pattern, variation of the temperature along the axis in and around the heat source are presented to show the overall heat transfer characteristics inside the plenum. 相似文献
143.
Kundan Tayade Amanpreet Kaur Sandesh Tetgure G. Krishana Chaitanya Narinder Singh Anil Kuwar 《Analytica chimica acta》2014
The (13E,19E)-N1′,N3′-bis[4-(diethylamino)-2-hydroxybenzylidene]malonohydrazide (L) has been developed for the detection of Th4+ ions using dual channel signalling system. The UV–vis absorbance and fluorescence spectroscopic data revealed the formation of L–Th4+ complex in 1:1 equilibrium. The density functional theory (DFT) also confirms the optimum binding cavity for the recognition of metal ion. The binding constant computed from different mathematical models for an assembly of L–Th4+. The detection limit of L for Th4+ recognition is to a concentration down to 0.1 μM (0.023 μg g−1). The present sensing system is also successfully applied for the detection of Th4+ ion present in soil near nuclear atomic plants. 相似文献
144.
K. Harsha Vardhan ReddyV. Prakash Reddy J. ShankarB. Madhav B.S.P. Anil KumarY.V.D. Nageswar 《Tetrahedron letters》2011,52(21):2679-2682
Recyclable copper oxide nanoparticles catalyzed simple and highly efficient protocol for the synthesis of symmetrical aryl sulfides was developed by the cross-coupling of aromatic halides with inexpensive and commercially available thiourea which was used as an effective sulfur surrogate. The present cross-coupling protocol of thiourea, via cascade reaction with various substituted aryl halides, producing desired aryl sulfides, has an added advantage of avoiding foul-smelling thiols. 相似文献
145.
Anil Kumar Sharma Abhilasha Singh R. K. Mehta Sudhanshu Sharma S. P. Bansal K. S. Gupta 《国际化学动力学杂志》2011,43(7):379-392
To understand the chemistry of Cu(II)–NH3–S(IV)–O2 system, the kinetics of the oxidation of sulfur(IV) catalyzed by amminecopper(II) complexes has been studied in the ammonia‐buffered solutions. Sulfur(IV) is oxidized to sulfate. The complexes, Cu(NH3)2+, Cu(NH3)22+, and Cu(NH3)2+3 appear to be equally reactive and Cu(NH3)42+ appears to be unreactive. The kinetics obey the rate law: where α1 and γ1 are the rate constants for O2‐dependent and O2‐independent pathways, respectively, for Cu(NH3)2+, Cu(NH3)2+2, and Cu(N H3)32+ complexes, which appear to be equally reactive. The values of α1 and γ1 were found to be (1.32 ± 0.21) × 106 L2 mol?2 s?1 (1.74 ± 0.40) × 109 L3 mol?3 s?1respectively at 30°C. The reaction rate is not influenced by the presence of ethanol—a free radical scavenger, so a nonradical mechanism has been proposed. The results of this study are useful in understanding the atmospheric chemistry of aqueous phase autoxidation of dissolved sulfur dioxide in copper(II)–ammonia–sulfur(IV)–oxygen system at high pH. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 379–392, 2011 相似文献
146.
Swapnil B. Ambade Rajaram S. Mane Anil V. Ghule Go-Woon Lee Ramphal Sharma Oh-shim Joo Rohan B. Ambade Soo-Hyoung Lee Sung-Hwan Han 《Journal of photochemistry and photobiology. A, Chemistry》2011,217(1):267-270
Enhanced photosensitization in presence of CdS nanoparticles is achieved in electrochemically deposited ZnO nanoplates and N3 loaded dye-sensitized solar cells. Chemically embedded CdS nanoparticles act as a sandwiching layer between ZnO nanoplates and dye molecules by overcoming current limiting serious Zn2+/dye insulating complex formation and CdS photo-corrosion issues. The X-ray diffraction and the scanning electron microscopy confirm the ZnO with vertically aligned nanoplates, perpendicular to the substrate surface. Amorphous CdS is monitored using electron dispersive X-ray analysis. The low and high resolution transmission electron microscope images confirm the presence of CdS nanoparticles over ZnO nanoplates which later is supported by an increase in optical absorbance and shift in band edge. About 400% increase in solar conversion efficiency with this cascade arrangement is achieved when compared with without CdS which could be fascinating while designing solid state solar cells in presence of suitable p-type layer. 相似文献
147.
148.
The first examples of ring-closing metathesis (RCM) reactions of a series of terminal alkene-derived cyclic phosphazenes have been carried out. The tetrakis-, hexakis-, and octakis(allyloxy)cyclophosphazenes (NPPh(2))(NP(OCH(2)CH=CH(2))(2))(2) (1), N(3)P(3)(OCH(2)CH=CH(2))(6) (2), and N(4)P(4)(OCH(2)CH=CH(2))(8) (3) and the tetrakis(allyloxy)-S-phenylthionylphosphazene (NS(O)Ph)[NP(OCH(2)CH=CH(2))(2)](2) (4) were prepared by the reactions of CH(2)=CHCH(2)ONa with the cyclophosphazenes (NPPh(2))(NPCl(2))(2), N(3)P(3)Cl(6), and N(4)P(4)Cl(8) and the S-phenylthionylphosphazene (NS(O)Ph)(NPCl(2))(2). The reactions of 1-4 with Grubbs first-generation olefin metathesis catalyst Cl(2)Ru=CHPh(PCy(3))(2) resulted in the selective formation of seven-membered di-, tri-, and tetraspirocyclic phosphazene compounds (NPPh(2))[NP(OCH(2)CH=CHCH(2)O)](2) (5), N(3)P(3)(OCH(2)CH=CHCH(2)O)(3) (6), and N(4)P(4)(OCH(2)CH=CHCH(2)O)(4) (7) and the dispirocyclic S-phenylthionylphosphazene compound (NS(O)Ph)[NP(OCH(2)CH=CHCH(2)O)](2) (8). X-ray structural studies of 5-8 indicated that the double bond of the spiro-substituted cycloalkene units is in the cis orientation in these compounds. In contrast to the reactions of 1-4, RCM reactions of the homoallyloxy-derived cyclophosphazene and thionylphosphazene (NPPh(2))[NP(OCH(2)CH(2)CH=CH(2))(2)](2) (9) and (NS(O)Ph)[NP(OCH(2)CH(2)CH=CH(2))(2)](2) (10) with the same catalyst resulted in the formation of 11-membered diansa compounds NPPh(2)[NP(OCH(2)CH(2)CH=CHCH(2)CH(2)O)](2) (11) and (NS(O)Ph)[NP(OCH(2)CH(2)CH=CHCH(2)CH(2)O)](2) (13) and the intermolecular doubly bridged ansa-dibino-ansa compounds 12 and 14. The X-ray structural studies of compounds 11 and 13 indicated that the double bonds of the ansa-substituted cycloalkene units are in the trans orientation in these compounds. The geminal bis(homoallyloxy)tetraphenylcyclotriphosphazene [NPPh(2)](2)[NP(OCH(2)CH(2)CH=CH(2))(2)] (15) upon RCM with Grubbs first- and second-generation catalysts gave the spirocyclic product [NPPh(2)](2)[NP(OCH(2)CH(2)CH=CHCH(2)CH(2)O)] (16) along with the geminal dibino-substituted dimeric compound [NPPh(2)](2)[NP(OCH(2)CH(2)CH=CHCH(2)CH(2)O)(2)PN][NPPh(2)](2) (17) as the major product. The dibino compound 17, upon reaction with the Grubbs second-generation catalyst, was found to undergo a unique ring-opening metathesis reaction, opening up the bino bridges and partially converting to the spirocyclic compound 16. 相似文献
149.
Suresh Babu Meruva A. Raghunadh N. Anil Kumar U. K. Syam Kumar R. Vasu Dev P. K. Dubey 《Journal of heterocyclic chemistry》2011,48(3):540-548
A variety of 5‐aryl‐(20S)‐camptothecin derivatives were synthesized by the reaction of 5‐hydroxy‐(20S)‐camptothecin with aromatic hydrocarbons under Friedel‐Craft reaction conditions in moderate to good yield as diastereomeric pairs. The methodology was then extended for the synthesis of 5‐amido‐(20S)‐camptothecin derivatives by reacting 5‐hydroxy‐(20S)‐camptothecin with alkyl and aryl nitriles under Ritter type reaction conditions. The reaction is presumed to proceed through an iminium ion intermediate under Friedel Craft and Ritter type reaction condition, which is further trapped by nucleophile present in the reaction medium. J. Heterocyclic Chem., 00 , 00 (2011). 相似文献
150.
Schlamp S Weber B Naik AD Garcia Y 《Chemical communications (Cambridge, England)》2011,47(25):7152-7154
A novel iron(II) mononuclear spin transition complex [FeL(py)(2)] displays an abrupt spin transition around 225 K accompanied by a very wide thermal hysteresis loop (~50 K) that spreads out over 100 K. Crystal structure analysis in both low-spin and high-spin states reveals a lipid layer-like arrangement of the complex molecules and provides insights into the spin switching mechanism. 相似文献