排序方式: 共有88条查询结果,搜索用时 31 毫秒
31.
A novel, biochemical, and eco-friendly method has been developed for the synthesis of Ag nanopar-ticles using an aqueous leaf extract of readily accessibleCinnamomum tamala as reducing and stabi-lizing agents. These Ag nanoparticles were used to catalyze the synthesis of pyranopyrazoles. The green nature and ease of recovery and reusability of the catalyst, together with high yields of prod-ucts, make this protocol attractive and useful. 相似文献
32.
The properties of the d-band structure of the transition metal atom in cubic LaBO(3) and SrBO(3) perovskites (where B = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) and their dependence on strain, d-band filling, and oxidation state were investigated using density functional theory calculations and atom-projected density of states. The strain dependence of the d-band width is shown to depend systematically on the size of the B atom. We show that the transition metal d-band width and center are linearly correlated with each other in agreement with a rectangular band model. A simple matrix element formalism based on the solid state table can readily predict the strain dependence of the d-band width. 相似文献
33.
Mustafa D Breynaert E Bajpe SR Martens JA Kirschhock CE 《Chemical communications (Cambridge, England)》2011,47(28):8037-8039
Cu(3)(BTC)(2) with an incorporated Keggin polyoxometalate was demonstrated to be stable under steaming conditions up to 483 K, while the isostructural HKUST-1 degrades and transforms into [Cu(2)OH(BTC)(H(2)O)](n)·2nH(2)O from 343 K onwards. 相似文献
34.
The persistence of shear stress fluctuations in viscous liquids is a direct consequence of the non-zero shear stress of the local potential minima which couples stress relaxation to transitions between inherent structures. In simulations of 2D and 3D glass forming mixtures, we calculate the distribution of this inherent shear stress and demonstrate that the variance is independent of temperature and obeys a power law in density. The inherent stress is shown to involve only long wavelength fluctuations, evidence of the central role of the static boundary conditions in determining the residual stress left after the minimization of the potential energy. A temperature T(η) is defined to characterise the crossover from stress relaxation governed by binary collisions at high temperatures to low temperature relaxation dominated by the relaxation of the inherent stress. T(η) is found to coincide with the breakdown of the Stokes-Einstein scaling of diffusion and viscosity. 相似文献
35.
Deodatta Phase Ram Janay Choudhary V. Ganesan V. Raghvendra Reddy Ajay Gupta N. Selvi Sneha Kulkarni Satishchandra Ogale 《Solid State Communications》2009,149(7-8):277-280
Dense nanodonut and nanotip type morphologies are shown to self-evolve in ultrathin cobalt films during growth under vacuum, depending on the level of oxygen incorporation and temperature. The nanodonut morphology forms at room temperature and the corresponding magnetic hysteresis shows exchange bias (~35 Oe shift along the field axis), which is attributed to the presence of CoO and its exchange coupling with cobalt. The morphology evolves into nanotip features with increase of growth temperature, with concurrent elimination of the oxide component and exchange bias. 相似文献
36.
37.
Jain Ankita P. Hamrapurkar Purnima D. Parate Abhijeet N. Labana Sneha M. Madrewar Dnyanoba M. Sonandkar Abhijeet A. 《平面色谱法杂志一现代薄层色谱法》2014,27(3):181-185
JPC – Journal of Planar Chromatography – Modern TLC - A simple, rapid, selective, and quantitative high-performance thinlayer chromatographic (HPTLC) method has been developed for the... 相似文献
38.
Farah Benyettou Nawel Kaddour Thirumurugan Prakasam Gobinda Das Sudhir Kumar Sharma Sneha Ann Thomas Fadia Bekhti-Sari Jamie Whelan Mohammed A. Alkhalifah Mostafa Khair Hassan Traboulsi Renu Pasricha Ramesh Jagannathan Nassima Mokhtari-Soulimane Felipe Gndara Ali Trabolsi 《Chemical science》2021,12(17):6037
With diabetes being the 7th leading cause of death worldwide, overcoming issues limiting the oral administration of insulin is of global significance. The development of imine-linked-covalent organic framework (nCOF) nanoparticles for oral insulin delivery to overcome these delivery barriers is herein reported. A gastro-resistant nCOF was prepared from layered nanosheets with insulin loaded between the nanosheet layers. The insulin-loaded nCOF exhibited insulin protection in digestive fluids in vitro as well as glucose-responsive release, and this hyperglycemia-induced release was confirmed in vivo in diabetic rats without noticeable toxic effects. This is strong evidence that nCOF-based oral insulin delivery systems could replace traditional subcutaneous injections easing insulin therapy.We report the successful use of a gastro-resistant covalent organic framework for in vivo oral delivery of insulin. 相似文献
39.
Padmakar V. Khadikar Prabhakar P. Kale Narian V. Deshpande Sneha Karmarkar Vijay K. Agrawal 《Journal of mathematical chemistry》2001,29(2):143-150
Problems don't hung on trees. Formulation of a good problem is often the most important part of a (theoretical) research. New problems usually arise when you try to solve old problems. Ivan Gutman, June 27, 1995.The Padmakar–Ivan (PI) index of hexagonal chains (i.e., the molecular graphs of unbranched catacondensed benzenoid hydrocarbons) is examined. The index PI is a graph invariant defined as the summation of the sums of edges of n
eu and n
ev over all the edges of connected graph G, where n
eu is the number of edges of G lying closer to u than to v and n
ev is the number of edges of G lying closer to v than to u. An efficient calculation of formula for PI for hexagonal chains are put forward. 相似文献
40.
Luke Lewis-Borrell Mahima Sneha Aditi Bhattacherjee Ian P. Clark Andrew J. Orr-Ewing 《Chemical science》2020,11(17):4475
The rapid development of new applications of photoredox catalysis has so far outpaced the mechanistic studies important for rational design of new classes of catalysts. Here, we report the use of ultrafast transient absorption spectroscopic methods to reveal both mechanistic and kinetic details of multiple sequential steps involved in an organocatalyzed atom transfer radical polymerization reaction. The polymerization system studied involves a N,N-diaryl dihydrophenazine photocatalyst, a radical initiator (methyl 2-bromopropionate) and a monomer (isoprene). Time-resolved spectroscopic measurements spanning sub-picosecond to microseconds (i.e., almost 8 orders of magnitude of time) track the formation and loss of key reactive intermediates. These measurements identify both the excited state of the photocatalyst responsible for electron transfer and the radical intermediates participating in propagation reactions, as well as quantifying their lifetimes. The outcomes connect the properties of N,N-diaryl dihydrophenazine organic photocatalysts with the rates of sequential steps in the catalytic cycle.Short-lived intermediates are tracked in real-time by transient absorption spectroscopy during a multi-step photoredox catalysed polymerization reaction. 相似文献