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591.
N. K. Karan R. S. Katiyar T. Maiti R. Guo A. S. Bhalla 《Journal of Raman spectroscopy : JRS》2009,40(4):370-375
This paper reports a systematic study of the composition and the temperature‐dependent‐Raman spectra of Zr4+‐rich BaZrxTi1−xO3 (BZT) ceramic compositions (0.50⩽x⩽1.00). On the basis of the dielectric behavior of Zr rich BZT ceramics, the observed relaxor behavior has been hypothesized as a result of increasing long‐range interactions of nanosized, Ti4+‐rich polar regions in a Zr4+‐rich nonpolar matrix. Beyond an optimum concentration of BaTiO3 (BT) in the nonpolar matrix of BaZrO3 (x⩽0.75), a critical size and density of the polar regions is reached when the polar clusters start showing the relaxor like behavior, which finally show classical relaxor behavior for compositions with x = 0.5 and 0.6. This hypothesis is strongly supported from the Raman data on Zr‐rich BZT presented in this paper. Well‐defined BT Raman spectra for 5% BT in BZT composition were recorded, which followed completely up to the 50% Ti addition in the BZT samples. The temperature‐dependent Raman spectra collected on the BZT ceramics far beyond the dielectric transition temperatures supported the existence of the nano‐polar BT regions, like in typical relaxor samples. The full width at half‐maximum (FWHM), integrated intensity of the peaks in the Raman spectra has been analyzed to further support the conclusions. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
592.
Santanu K. Maiti 《Physics letters. A》2009,373(48):4470-4474
We explore AND gate response in a double quantum ring where each ring is threaded by a magnetic flux ?. The double quantum ring is attached symmetrically to two semi-infinite one-dimensional metallic electrodes and two gate voltages, namely, Va and Vb, are applied, respectively, in the lower arms of the two rings which are treated as two inputs of the AND gate. The system is described in the tight-binding framework and the calculations are done using the Green's function formalism. Here we numerically compute the conductance-energy and current-voltage characteristics as functions of the ring-to-electrode coupling strengths, magnetic flux and gate voltages. Our study suggests that, for a typical value of the magnetic flux ?=?0/2 (?0=ch/e, the elementary flux-quantum) a high output current (1) (in the logical sense) appears only if both the two inputs to the gate are high (1), while if neither or only one input to the gate is high (1), a low output current (0) results. It clearly demonstrates the AND gate behavior and this aspect may be utilized in designing an electronic logic gate. 相似文献
593.
Dr. Sourav Maiti Pranav Anand Farazuddin Azlan Dr. Jayanta Dana Prof. Dr. Hirendra N. Ghosh 《Chemphyschem》2019,20(20):2662-2667
In this paper, we have investigated the possibility of utilizing CdZnS and CdZnSe alloy nanocrystals (NCs) as sensitizers in quantum-dot solar cells (QDSCs). The alloy NCs were synthesized by a high-temperature hot injection method and subsequently characterized through high photoluminescence quantum yield, along with larger size compared to binary NCs. Femtosecond transient absorption measurements revealed long-lived charge carriers in the alloy structure due to more structural rigidity and less defect states. Finally, the solar-cell efficiencies of the CdZnS (CdZnSe) NCs were found to be 3.05 % (3.69 %) as compared to 1.23 % (3.12 %) efficiencies for CdS (CdSe) NCs. Thus, common anion ternary NCs have been successfully utilized for solar-cell assembly and can be helpful for constructing tandem solar cells to harvest the high-energy portion of solar radiation. 相似文献
594.
Tapas Kumar Achar Xinglong Zhang Rahul Mondal M. S. Shanavas Siddhartha Maiti Sabyasachi Maity Nityananda Pal Robert S. Paton Debabrata Maiti 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10461-10468
Palladium(II)‐catalyzed meta‐selective C?H allylation of arenes has been developed utilizing synthetically inert unactivated acyclic internal olefins as allylic surrogates. The strong σ‐donating and π‐accepting ability of pyrimidine‐based directing group facilitates the olefin insertion by overcoming inertness of the typical unactivated internal olefins. Exclusive allyl over styrenyl product selectivity as well as E stereoselectivity were achieved with broad substrate scope, wide functional‐group tolerance, and good to excellent yields. Late‐stage functionalisations of pharmaceuticals were demonstrated. Experimental and computational studies shed light on the mechanism and point to key steric control in the palladacycle, thus determining product selectivities. 相似文献
595.
Soumitra Agasti Tapas Pal Tapas Kumar Achar Siddhartha Maiti Debasis Pal Smita Mandal Kishan Daud Goutam Kumar Lahiri Debabrata Maiti 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(32):11155-11159
α,β‐Alkenyl carboxylic acids undergo CuII‐mediated decarboxylative annulation reactions with aliphatic cyclic ketones to provide synthetically valuable di‐heterocycles. The annulation process tolerates a variety of aliphatic ketones and heterocyclic alkenyl carboxylic acids, producing substituted fused furan derivatives with complete regioselectivity. The current protocol offers a synthetically applicable pathway to construct a variety of oligo‐heterocycles through Cu‐mediated single‐electron transfer and decarboxylation. Notably, synthesis of relatively inaccessible di‐heterocycles has been achieved successfully using this protocol. 相似文献
596.
Using UV melting and CD spectroscopy, we show that alpha-l-LNA-modified oligonucleotides possess the ability to form triplexes at pH 6.8 with significantly increased thermostability relative to DNA triplexes. 相似文献
597.
Theory of growth and mechanical properties of nanotubes 总被引:1,自引:0,他引:1
J. Bernholc C. Brabec M. Buongiorno Nardelli A. Maiti C. Roland B.I. Yakobson 《Applied Physics A: Materials Science & Processing》1998,67(1):39-46
Received: 11 January 1998 相似文献
598.
Manoj K. Maiti 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1965,16(5):594-598
Zusammenfassung Mit Hilfe von Ähnlichkeitsbetrachtungen wird in der Gegend eines Staupunktes die rotationssymmetrische Strömung einer nicht Newtonschen Flüssigkeit mit Potenzgesetz diskutiert. Es zeigt sich, dass im Gegensatz zu der Newtonschen Flüssigkeit die Dicke der Grenzschicht mit dem Abstand vom Staupunkt variiert. Die Bewegungsdifferentialgleichungen werden mittels der Kármán-Pohlhausen-Methode integriert. Es stellt sich heraus, dass die Schubspannung an der Platte mitn, dem charakteristischen Index der Flüssigkeit, zunimmt. 相似文献
599.
Tobacco plants can be used for the production of proteins for pharmaceutical applications. One of the most difficult and expensive
tasks associated with this technology is isolating the product of interest from the hundreds of other chemicals found in tobacco.
We describe a new recovery strategy in which the protein of interest is “tagged” with a histidine structure, which forms a
complex with metal ions and a surfactant that will accumulate in the foamate of a foam fractionation step. His-gus, a histidine-tagged
enzyme, was selectively recovered in the presence of two different surfactants and two different metal ions. The foam fractionation
with N-∈-dodecylamido-N-α, N-α,-bis(carboxymethyl)-l-lysine surfactant and Ni2+ ions resulted in an average His-gus activity recovery value of 88% and an activity enrichment of 2.27. The performance of
the recovery strategy without tobacco extract resulted in an average activity recovery value of 63.32% and an average activity
enrichment value of 5.16, utilizing lauroylethylenediaminetriacetate surfactant and Ni2+ ions. It was shown that even though a majority of the native tobacco proteins are removed during the prefoaming step, the
presence of tobacco extract does affect the recovery of His-gus. 相似文献
600.
[reaction: see text] The formation of nitrone (a water exclusion reaction) in aqueous media using surfactant and subsequent cycloaddition in the same pot, a new example of green chemistry, is reported. The control of regioselectivity favors the formation of trans-5-substituted isoxazolidine. This work not only may lead to an environmentally benign system but also will provide a new aspect of reactions in water. 相似文献