803 research outputs found
Vibron and roton bands in the first overtone of solid and liquid parahydrogen
No full textThe infrared spectrum of the rotovibrational band v=0→2 of parahydrogen has been observed in the condensed phases down to T=2 K. In the solid, phonon and roton sidebands exhibit peaks corresponding to those observed in the fundamental. Contributions arising from the reorientation of ortho-H2 impurities have been detected. The Q1(0)+S1(0) band has been resolved into an asymmetric doublet, and the origin of this latter is discussed. In the liquid phase the observed line shapes include strong translational contributions, and are accounted for by assuming that at short times the excited molecule is encapsulated in the cage of nearest neighbors. © 1994 The American Physical Society
Consequences of Hunter Harvest, Winter Weather, and Increasing Population Size on Survival of Non-Migratory Canada Geese in Connecticut
No full textConover, M. R., J. B. Dinkins, and R. E. Ruzicka. 2015. Consequences of hunter harvest, winter weather, and increasing population size on survival of non-migratory Canada geese in Connecticut. Journal of Wildlife Management 79: 1239-1245
Routes to gelation in a clay suspension
No full textThe gelation of water suspension of a synthetic clay (Laponite) has been studied by dynamic light scattering in a wide range of clay weight concentration (C-w=0.003-0.031). At variance with previous determination, indicating a stable liquid phase for C-w<C(w)(*)approximate to0.015-0.018, we find that gelation actually takes place in the whole examined C-w range. We find also that C-w(*) marks the transition between two different routes to gelation. We hypothesize that at low concentration Laponite suspension behaves as an attractive colloid and that the slowing down of the dynamics is attained by the formation of larger and larger clusters while at high concentration the basic units of the arrested phase could be the Debye Huckel spheres associated with single Laponite plates
About the formation of C60 fine particles with reprecipitation method in ethanol/carbon disulfide mixture.
No full textTRANSLATIONAL AND ROTATIONAL SPECTRA IN THE FUNDAMENTAL INFRARED BAND OF LIQUID AND SOLID PARAHYDROGEN
No full textThe Q1(0) and Q1(0)+S0(0) infrared bands have been studied in liquid and solid para-H-2 with particular regard to their translational sidebands. In the liquid, their line shapes are well fitted by a model in which the excited particle is encapsulated. In the solid, the phonon sidebands reproduce the main features of the density of states (DOS), as extracted from neutron scattering. The S1(0)+S0(0) band shows a pure rotonic line shape which is well described by recent DOS calculations
Swelling of responsive-microgels: experiments versus models
No full textInterpenetrated Polymer Network (IPN) microgels of PNIPAM and PAAc have been investigated and the experimental data have been compared with theoretical models from the Flory–Rehner theory. We confirm that the swelling behavior of PNIPAM microgels is well described by this theory by considering the second order approximation for the volume fraction φ dependence of the Flory parameter χ(φ). Indeed the Volume-Phase Transition (VPT) of the PNIPAM-PAAc IPN microgel at neutral conditions and in D2O solvents can be well described only considering a third-order approximation. Interestingly we empirically find that sharper is the transition higher is the order of the χ(φ) relation which has to be considered. Moreover the VPT can be experimentally controlled by tuning the polymer/solvent interactions through pH and solvent allowing to directly modify the delicate balance between energetic and entropic contributions and to explore the swelling behavior in a wide range of environmental conditions. In particular we find that the most advantageous condition for swelling is in water at acidic pH
Dynamics of Laponite solutions: An interpretation within the coupling model scheme
No full textThe basic predictions of the coupling model (1) have been tested on Laponite suspensions at different clay and salt concentrations. In spite of parameters obtained through a fit analysis slightly different from that predicted by the coupling model, several interesting results consistent with the model have been found. These findings can open a new route to the interpretation of the intriguing dynamical behavior of this widely studied and discussed charged colloidal system. (C) 2007 Elsevier B.V. All rights reserved
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