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101.
Sm4Bi3 has the anti-Th3P4 (cubic) structure with three Sm2+ ions and one Sm3+ ion. The compound undergoes a first-order, isostructural transition at about 26 kbar. The resistance abruptly decreases by a factor of three and the volume by about 10%. The Sm2+ ions undergo a change towards the 3+ state in the transition and the material goes from semimetallic to a metallic state. The behavior of the resistance anomaly suggests termination of the phase boundary at a critical point. 相似文献
102.
We report the existence of a volume collapsed strongly mixed valent state at pressures above 65 K bars in the prototype “concentrated Kondo” system CeAl2 and discuss the relevant energy scales and general phase diagram of CeAl2. To our knowledge this is the first demonstrated example of what should be a large class of systems exhibiting the full diversity of ground states of an Anderson lattice. 相似文献
103.
104.
The unsteady dispersion of a solute, when the fluid is driven through a curved channel with absorbing walls by an imposed
pulsatile pressure gradient, is studied using the method of moments. The study examines the effect of oscillatory Reynolds
number, amplitude/frequency of the pressure pulsation and boundary absorption on the longitudinal dispersion. The methodology
involves a set of unsteady integral moment equations obtained by applying the Aris-Barton method of moments on the convective-diffusion
equation for a curved channel. Central moments are obtained from the moment equations which are solved by a finite-difference
implicit scheme. The effect of curvature and boundary absorption on the effective dispersion coefficient from the initial
to the stationary stage of the oscillatory flow is studied. Amplitude of the effective dispersion coefficient is found to
increase with curvature and decrease with frequency of the pressure pulsation. For large Peclet number and Schmidt number,
the amplitude of the dispersion coefficient can be 1.6 times that in a straight channel at large times. Also, for large times,
the amplitude of the dispersion coefficient is twice the amplitude of the dispersion coefficient as α, the frequency parameter
changes from 0.5 to 1.0. The axial distributions of mean concentration are determined from the first four central moments
by using the Hermite polynomial representation. The effect of curvature is to delay the stationary state and also the approach
to normality of the concentration distribution. The study has importance in understanding the spreading of pollutants in tidal
basins and natural current fields. 相似文献
105.
Noor Shahina Begum D. E. Vasundhara C. R. Girija G. D. Kolavi V. S. Hegde I. M. Khazi 《Journal of chemical crystallography》2007,37(8):561-565
The crystal structure of the title compound has been determined. The compound crystallizes in the monoclinic space group P21/c with a = 5.9885(2) Å, b = 14.7345(4) Å, c = 12.3719(4) Å, β = 96.655(5)°, V = 1084.31(8) Å3, z = 4. An intramolecular N–H···N hydrogen bond forms a pseudo-six-membered ring with graph set S 1 1(6). The crystal structure is stabilized by intermolecular interactions of the type N–H···N and C–H···N. The packing motifs in accordance with Etter’s analysis are R 2 2(8) corresponding to N–H···N dimer and that generated by the chain is C(7). 相似文献
106.
Barry C. Pemberton Ramya Raghunathan Sabine Volla Jayaraman Sivaguru 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(39):12178-12190
Cucurbiturils are a family of molecular container compounds with superior molecular recognition properties. The use of cucurbiturils for supramolecular catalysis is highlighted in this concept. Both photochemical reactions as well as thermal transformations are reviewed with an eye towards tailoring substrates for supramolecular catalysis mediated by cucurbiturils. 相似文献
107.
A. Sree Rama Murthy Dhruv Pathak Gautam Sharma K.I. Gnanasekar V. Jayaraman A.M. Umarji T. Gnanasekaran 《Analytica chimica acta》2015
The transient changes in resistances of Cr0.8Fe0.2NbO4 thick film sensors towards specified concentrations of H2, NH3, acetonitrile, acetone, alcohol, cyclohexane and petroleum gas at different operating temperatures were recorded. The analyte-specific characteristics such as slopes of the response and retrace curves, area under the curve and sensitivity deduced from the transient curve of the respective analyte gas have been used to construct a data matrix. Principal component analysis (PCA) was applied to this data and the score plot was obtained. Distinguishing one reducing gas from the other is demonstrated based on this approach, which otherwise is not possible by measuring relative changes in conductivity. This methodology is extended for three Cr0.8Fe0.2NbO4 thick film sensor array operated at different temperatures. 相似文献
108.
Photoreactions with a Twist: Atropisomerism‐Driven Divergent Reactivity of Enones with UV and Visible Light
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Nandini Vallavoju Avadakkam Sreenithya Anoklase J.‐L. Ayitou Dr. Steffen Jockusch Prof. Dr. Raghavan B. Sunoj Prof. Dr. Jayaraman Sivaguru 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(32):11339-11348
Light‐induced transformation of atropisomeric and achiral enones displays divergent reactivity. Photocyclization leading to 3,4‐dihydroquinolin‐2‐one was observed with achiral enone carboxamide, whereas the atropisomeric enone carboxamides underwent hydrogen abstraction leading to spiro‐β‐lactams. Detailed photochemical, photophysical, and theoretical investigations have provided insight into this divergent reactivity and selectivity. 相似文献
109.
Arthi Jayaraman 《Journal of polymer science. Part A, Polymer chemistry》2013,51(7):524-534
Macroscopic properties of polymer nanocomposites depend on the microscopic composite morphology of the constituent nanoparticles and polymer matrix. One way to control the spatial arrangement of the nanoparticles in the polymer matrix is by grafting the nanoparticle surfaces with polymers that can tune the effective interparticle interactions in the polymer matrix. A fundamental understanding of how graft and matrix polymer chemistries and molecular weight, grafting density, and nanoparticle size, and chemistry affect interparticle interactions is needed to design the appropriate polymer ligands to achieve the target morphology. Theory and simulations have proven to be useful tools in this regard due to their ability to link molecular level interactions to the morphology. In this feature article, we present our recent theory and simulation studies of polymer grafted nanoparticles with chemical and physical heterogeneity in grafts to calculate the effective interactions and morphology as a function of chemistry, molecular weights, grafting densities, and so forth. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013 相似文献
110.
Quench collection of nano-aluminium agglomerates from combustion of sandwiches and propellants 总被引:1,自引:0,他引:1
K. Jayaraman S.R. Chakravarthy R. Sarathi 《Proceedings of the Combustion Institute》2011,33(2):1941-1947
An experimental investigation has been carried out to measure the size of nano-aluminium agglomerates emerging from the combustion of nano-aluminized sandwiches and composite solid propellants. Nano-aluminium of median size of 50 nm produced in-house by the electrical wire explosion method is used in these samples. Propellants with different sizes of coarse and fine ammonium perchlorate are considered. Surface features of sandwiches and a propellant whose burning was interrupted by rapid depressurization are examined in a scanning electron microscope. The combustion products of the sandwiches and propellants are quenched close to the burning surface and collected in a quench collection set-up. The surface features of rapid-depressurization quenched sandwiches exhibit relatively large nano-aluminium clusters—of the order a few micrometres—particularly in the binder lamina. Quench-collected nano-aluminium exhibits significant agglomeration, but only a small fraction of the agglomerates are in the 1–3 μm range, except for both the coarse and fine AP particles used in the formulation being large, but even there they do not exceed ∼5 μm in size. This is expected to be benign for reduced smoke propellant applications from exhaust signature point of view, and to decrease the specific impulse losses without sacrificing the energetics of the propellant. 相似文献