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991.
The first catalytic enantioselective Michael addition of deconjugated butyrolactams to N-arylmaleimides is developed with the help of a bifunctional tertiary aminosquaramide catalyst. Unlike the widely explored and structurally related vinylogous nucleophile – deconjugated butenolides, deconjugated butyrolactams are found to be exclusively α-selective. The resulting highly substituted and densely functionalized products, bearing contiguous all-carbon quaternary and tertiary stereocenters, are formed in good yields with moderate diastereoselectivity and good to excellent enantioselectivity (up to 99:1 er). 相似文献
992.
Chiradeep Mukherjee Saradindu Panda Asish Kumar Mukhopadhyay Bansibadan Maji 《International Journal of Theoretical Physics》2018,57(7):2068-2092
The Quantum-dot Cellular Automata (QCA) is the prominent paradigm of nanotechnology considered to continue the computation at deep sub-micron regime. The QCA realizations of several multilevel circuit of arithmetic logic unit have been introduced in the recent years. However, as high fan-in Binary to Gray (B2G) and Gray to Binary (G2B) Converters exist in the processor based architecture, no attention has been paid towards the QCA instantiation of the Gray Code Converters which are anticipated to be used in 8-bit, 16-bit, 32-bit or even more bit addressable machines of Gray Code Addressing schemes. In this work the two-input Layered T module is presented to exploit the operation of an Exclusive-OR Gate (namely LTEx module) as an elemental block. The “defect-tolerant analysis” of the two-input LTEx module has been analyzed to establish the scalability and reproducibility of the LTEx module in the complex circuits. The novel formulations exploiting the operability of the LTEx module have been proposed to instantiate area-delay efficient B2G and G2B Converters which can be exclusively used in Gray Code Addressing schemes. Moreover this work formulates the QCA design metrics such as O-Cost, Effective area, Delay and Cost α for the n-bit converter layouts. 相似文献
993.
994.
A.K. Mukherjee 《Applied Surface Science》2009,255(12):6168-6172
The effect of periodic variation of external pressure on the catalytic oxidation of CO is simulated for a modified Ziff-Gulari-Barshad (ZGB) model including the Eley-Rideal (ER) step. The external CO partial pressure is periodically varied between its values in reactive and CO poisoned states. The results show different amplitudes of such perturbation significantly influence the CO2 production rate. Latter also changes with the period of such oscillations, especially for perturbations with larger amplitudes. However, for a given period there is a critical value of the amplitude above which, the catalyst surface becomes irreversibly poisoned. 相似文献
995.
J.M.B. Shorto P.R.S. Gomes J. Lubian L.F. Canto S. Mukherjee L.C. Chamon 《Physics letters. [Part B]》2009
We propose a new technique to analyze total reaction cross sections. In this technique, which has been previously applied to fusion reactions, the experimental data are used to build a dimensionless reaction function, which does not depend on the system size or details of the optical potential. In this way, total reaction cross sections for different systems can be directly compared. We employ this technique to perform a systematic study of reaction cross sections of weakly bound systems in different mass ranges, and compare their reaction functions with the ones of tightly bound systems with similar masses. We show that breakup reactions and neutron transfers in halo systems lead to large reaction functions, well above the ones of typical tightly or weakly bound stable systems. 相似文献
996.
Rabin Banerjee Biswajit Chakraborty Subir Ghosh Pradip Mukherjee Saurav Samanta 《Foundations of Physics》2009,39(12):1297-1345
In this review article we discuss some of the applications of noncommutative geometry in physics that are of recent interest,
such as noncommutative many-body systems, noncommutative extension of Special Theory of Relativity kinematics, twisted gauge
theories and noncommutative gravity. 相似文献
997.
998.
Rick Mukherjee 《Physics letters. A》2008,372(42):6347-6362
We provide a general scheme for mapping integrable nonlinear partial differential equations of real functions to moving space curves using an approach different from the one proposed by Lamb. We apply our method to the sine-Gordon equation and obtain links to five new classes of space curves, in addition to the two found by Lamb. For each class, we display the rich variety of moving curves associated with the one-soliton, the breather, the two-soliton and the soliton-antisoliton solutions, and suggest possible applications. Our results also provide new insights with regard to the two-soliton (soliton-antisoliton) scattering process. 相似文献
999.
Xu D Cunningham CH Chen AP Li Y Kelley DA Mukherjee P Pauly JM Nelson SJ Vigneron DB 《Magnetic resonance imaging》2008,26(9):1201-1206
Ultra-high-field 7 T magnetic resonance (MR) scanners offer the potential for greatly improved MR spectroscopic imaging due to increased sensitivity and spectral resolution. Prior 7 T human single-voxel MR Spectroscopy (MRS) studies have shown significant increases in signal-to-noise ratio (SNR) and spectral resolution as compared to lower magnetic fields but have not demonstrated the increase in spatial resolution and multivoxel coverage possible with 7 T MR spectroscopic imaging. The goal of this study was to develop specialized radiofrequency (RF) pulses and sequences for three-dimensional (3D) MR spectroscopic imaging (MRSI) at 7 T to address the challenges of increased chemical shift misregistration, B1 power limitations, and increased spectral bandwidth. The new 7 T MRSI sequence was tested in volunteer studies and demonstrated the feasibility of obtaining high-SNR phased-array 3D MRSI from the human brain. 相似文献
1000.
Rauth C Ackermann D Blaum K Block M Chaudhuri A Di Z Eliseev S Ferrer R Habs D Herfurth F Hessberger FP Hofmann S Kluge HJ Maero G Martín A Marx G Mukherjee M Neumayr JB Plass WR Rahaman S Rodríguez D Scheidenberger C Schweikhard L Thirolf PG Vorobjev G Weber C 《Physical review letters》2008,100(1):012501
The masses of six neutron-deficient rare holmium and thulium isotopes close to the proton drip line were determined with the SHIPTRAP Penning trap mass spectrometer. For the first time the masses of the proton-unbound isotopes 144,145Ho and 147,148Tm were directly measured. The proton separation energies were derived from the measured mass values and compared to predictions from mass formulas. The new values of the proton separation energies are used to determine the location of the proton drip line for holmium and thulium more accurately. 相似文献