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321.
A direct synthesis of β-carbolines via a three-step one-pot domino approach with a bifunctional Pd/C/K-10 catalyst 总被引:1,自引:0,他引:1
A rapid, microwave-assisted synthesis of β-carbolines via a successive condensation/cyclization/dehydrogenation approach is described. This methodology involves the coupling of various tryptamines with aromatic aldehydes/glyoxals. The product imine undergoes a Pictet-Spengler cyclization followed by a final dehydrogenation to yield β-carbolines in a three-step domino reaction. The use of the bifunctional catalyst Pd/C/K-10 combined with microwave irradiation enabled the synthesis of β-carbolines in short reaction times and in good to excellent yields. 相似文献
322.
Lakshmikanta Aditya J. Nanda N. Venkataramani Shiva Prasad 《Journal of magnetism and magnetic materials》2009,321(20):3373-3379
A significant advance in the understanding of grain boundary contribution to magnetization in nanocrystalline ferrite thin films is demonstrated in this paper. RF-sputtered, room-temperature-deposited lithium-zinc ferrite thin films (Li0.5−x/2ZnxMn0.1Fe2.35−x/2O4, with x=0.0, 0.16, 0.32 and 0.48) have been thermally annealed ex-situ at 850 °C and the in-plane magnetic measurements have been performed using a vibrating sample magnetometer. The percentage deviation between bulk and film magnetization (δM) is observed to decrease with increasing Zn concentration, till x=0.32, and then it increases. Macro-texture measurements using X-ray orientation distribution function and micro-texture measurements using orientation imaging microscopy show reverse trend in the extent of crystallographic texturing and in the computed fraction of low-angle grain boundaries. This study brings out a correlation between low-angle grain boundary concentration and δM. 相似文献
323.
Cheng Chen Jasmine N. Tutol Longteng Tang Liangdong Zhu Whitney S. Y. Ong Sheel C. Dodani Chong Fang 《Chemical science》2021,12(34):11382
Natural and laboratory-guided evolution has created a rich diversity of fluorescent protein (FP)-based sensors for chloride (Cl−). To date, such sensors have been limited to the Aequorea victoria green fluorescent protein (avGFP) family, and fusions with other FPs have unlocked ratiometric imaging applications. Recently, we identified the yellow fluorescent protein from jellyfish Phialidium sp. (phiYFP) as a fluorescent turn-on, self-ratiometric Cl− sensor. To elucidate its working mechanism as a rare example of a single FP with this capability, we tracked the excited-state dynamics of phiYFP using femtosecond transient absorption (fs-TA) spectroscopy and target analysis. The photoexcited neutral chromophore undergoes bifurcated pathways with the twisting-motion-induced nonradiative decay and barrierless excited-state proton transfer. The latter pathway yields a weakly fluorescent anionic intermediate , followed by the formation of a red-shifted fluorescent state that enables the ratiometric response on the tens of picoseconds timescale. The redshift results from the optimized π–π stacking between chromophore Y66 and nearby Y203, an ultrafast molecular event. The anion binding leads to an increase of the chromophore pKa and ESPT population, and the hindrance of conversion. The interplay between these two effects determines the turn-on fluorescence response to halides such as Cl− but turn-off response to other anions such as nitrate as governed by different binding affinities. These deep mechanistic insights lay the foundation for guiding the targeted engineering of phiYFP and its derivatives for ratiometric imaging of cellular chloride with high selectivity.We discovered an interplay between proton transfer and conformational reorganization that powers a standalone fluorescent-protein-based excitation-ratiometric biosensor for chloride imaging. 相似文献
324.
Screening-Dependent Study of Superconductivity in 3d-Transition Metals Binary Alloys Superconductors
Aditya M. Vora 《理论物理通讯》2009,51(3):533-539
In the present article, we report the screening-dependent study of the superconducting state parameters (SSPs), viz. electron-phonon coupling strength A, Coulomb pseudopotential μ^*, transition temperature TC, isotope effect exponent a, and effective interaction strength No V of 3d-band transition metals binary alloys superconductors have been made extensively in the present work using a model potential formalism and employing the pseudo-alloy-atom (PAA) model for the first time. Five local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are used in the present investigation to study the screening influence on the aforesaid properties. The present results of the SSPs obtained from H-screening are found in qualitative agreement with the available experimental data wherever exist. 相似文献
325.
Aditya M. Vora 《理论物理通讯》2009,51(3):550-554
In the present article, we study the electrical resistivity ρ, the thermoelectric power (TEP) α, thermal conductivity σ, Knight-Shifts and temperature coefficient of the Knight-Shifts of the liquid Si and Ge using the well known model potential for the first time. The structure factor used in the present work is derived from the Percus-Yevick (PY) theory. Various local field correction functions are used to study the screening influence. The present results of resistivity are found in qualitative agreement with available experimental and theoretical whenever exists. 相似文献
326.
An easy, inexpensive, and accurate method for the analysis of synthetic dyes by means of ion-pair thin-layer chromatography (IPTLC) on mixed sorbent phases containing silica gel G and barium sulfate in an aqueous ethanol system is studied. The effect of the composition of the sorbent phases has a major effect on the hundred-fold relative migration rate, as also does the effect of the ion-pairing reagent as the impregnant. Compact and sharp spot application yields very good binary and ternary separations and enables their clear identification. IPTLC has better separations on mixed sorbent phases, which are not possible on plain mixed phases in thin-layer chromatography. The method can be applied for the trace analysis of synthetic dyes in various natural and synthetic samples. 相似文献
327.
328.
Dissociation constants of the 1,10-phenanthrolium ion in different aqueous ethanolic solutions have been determined spectrophotometrically and pH-metrically. Some aspects of the role of the solvent have been discussed. 相似文献
329.
Aditya Agrawal 《电子设计技术》2004,11(4):F013-F013,F015,F016
宽带无线互联网论坛网站(Broadband Wireless Internet Forum Web,www.bwif.org)不再继续了,最后一期新闻发布稿张贴于2001年10月18日.加入邮寄名单的订阅请求会带来"找不到网页"的错误信息.如果打电话到所列出的电话号码,电话则会被转给一位IEEE的员工,这位员工会委婉地告诉你该机构的努力已经"消退". 相似文献
330.
Aditya M. Vora 《Frontiers of Physics》2007,2(4):430-435
The theoretical investigation of the superconducting state parameters (SSP) viz. electron-phonon coupling strength λ, Coulomb pseudopotential μ*, transition temperature T c, isotope effect exponent α and effective interaction strength N 0 V of ten Cu C Zr100?C metallic glasses have been reported using Ashcroft’s empty core (EMC) model potential. Three local field correction functions proposed by Hartree (H), Taylor (T) and Ichimaru-Utsumi (IU) are used in the current investigation to study the screening influence on the aforesaid properties. It is observed that the electron-phonon coupling strength λ and the transition temperature T C are quite sensitive to the selection of the local field correction functions, whereas the Coulomb pseudopotential μ*, isotope effect exponent α and effective interaction strength N 0 V show weak dependences on local field correction functions. The T c obtained from IU-local field correction function are found an excellent agreement with available theoretical or experimental data. Also, the present results are found in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in metallic glasses. 相似文献