Experimental evidence of surface-plasmon coupling in anisotropic hollow nanoparticles

We report on the investigation of surface-plasmon excitation of anisotropic WS(2) hollow nanoparticles in a near-field geometry by means of a scanning transmission electron microscope. The shell thickness influence on the electron-energy-loss-spectroscopy spectra is experimentally observed and is analyzed within a classical dielectric formalism. As for the isotropic case, we evidence one symmetric (tangential) and one antisymmetric (radial) mode. We point out the intriguing fact that, for the anisotropic case, one can relate these modes to the interband transition of the in-plane component of the dielectric tensor and to the bulk-plasmon energy of the out-of-plane component.     

On n-Hamiltonian line graphs

With each nonempty graph G one can associate a graph L(G), called the line graph of G, with the property that there exists a one-to-one correspondence between E(G) and V(L(G)) such that two vertices of L(G) are adjacent if and only if the corresponding edges of G are adjacent. For integers m ≥ 2, the mth iterated line graph L^m(G) of G is defined to be L(L^m-1(G)). A graph G of order p ≥ 3 is n-Hamiltonian, 0 ≤ n ≤ p ? 3, if the removal of any k vertices, 0 ≤ k ≤ n, results in a Hamiltonian graph. It is shown that if G is a connected graph with δ(G) ≥ 3, where δ(G) denotes the minimum degree of G, then L²(G) is (δ(G) ? 3)-Hamiltonian. Furthermore, if G is 2-connected and δ(G) ≥ 4, then L²(G) is (2δ(G) ? 4)-Hamiltonian. For a connected graph G which is neither a path, a cycle, nor the graph K(1, 3) and for any positive integer n, the existence of an integer k such that L^m(G) is n-Hamiltonian for every m ≥ k is exhibited. Then, for the special case n = 1, bounds on (and, in some cases, the exact value of) the smallest such integer k are determined for various classes of graphs.     

Long-term trend in CHF2Cl (HCFC-22) from high spectral resolution infrared solar absorption measurements and comparison with in situ measurements

The average tropospheric volume mixing ratio of CHF₂Cl (HCFC-22) has been retrieved from a time series of high spectral resolution ground-based infrared solar absorption spectra recorded with the McMath Fourier transform spectrometer located at the U.S. National Solar Observatory facility on Kitt Peak in southern Arizona (31.9°N, 111.6°W, 2.09 km altitude) for the time period October 1987–November 2002. The retrievals are based on fits to the well-isolated, unresolved 2ν₆ Q branch at 829.05 cm⁻¹ and the SFIT2 retrieval algorithm. The measured daily averages show a near linear rise per year in the mean tropospheric volume mixing ratio as a function of time with a best fit yielding an average increase rate of (5.66±0.15) parts per trillion (10⁻¹²) by volume per year, corresponding to (6.47±0.17)%yr⁻¹, 1 sigma, at the beginning of the time series. The tropospheric mixing ratios retrieved from the solar spectra have been compared with monthly average surface flask sampling measurements from the Climate Monitoring and Diagnostic Laboratory (CMDL) station at Niwot Ridge, Colorado (40.0°N, 105.5°W, 3013 m altitude), archived measurement from the same location, and early CMDL northern hemisphere Pacific cruise measurements. The average ratio of the retrieved tropospheric mixing ratio relative to the CMDL surface mixing ratio is 1.053 for the overlapping 1987 to 2002 time period. The retrieved mean tropospheric mixing ratio is consistent with the surface measurements within the errors estimated for the remote sensing observations.     

Convergence and finite determination of formal CR mappings

It is shown that a formal mapping between two real-analytic hypersurfaces in complex space is convergent provided that neither hypersurface contains a nontrivial holomorphic variety. For higher codimensional generic submanifolds, convergence is proved e.g. under the assumption that the source is of finite type, the target does not contain a nontrivial holomorphic variety, and the mapping is finite. Finite determination (by jets of a predetermined order) of formal mappings between smooth generic submanifolds is also established.

     

Affine Approximation of Lipschitz Functions and Nonlinear Quotients

New concepts related to approximating a Lipschitz function between Banach spaces by affine functions are introduced. Results which clarify when such approximations are possible are proved and in some cases a complete characterization of the spaces X, Y for which any Lipschitz function from X to Y can be so approximated is obtained. This is applied to the study of Lipschitz and uniform quotient mappings between Banach spaces. It is proved, in particular, that any Banach space which is a uniform quotient of L _p , 1 < p < , is already isomorphic to a linear quotient of L _p . Submitted: June 1998, revised: December 1998.     

Impulsive loading of ideal fibre-reinforced rigid-plastic beams—III Cantilever beam

The theory outlined in Part I is applied to the problem of a cantilever beam struck transversely at any point by a mass which subsequently adheres to the beam. In the subsequent motion, slope and velocity discontinuities propagate outwards from the point of impact. Solutions for the velocity and deflection of the various segments of the beam are obtained for the case of linear strain-hardening, and simpler approximate solutions are derived for the case of low impact velocity and/or slight strain-hardening. The discontinuity propagating towards the free end of the beam always comes to rest before it reaches this end, but for sufficiently high values of impact mass and velocity, and a strain-hardening parameter, one or more reflections of the discontinuity may occur at the fixed end of the beam and at the point of impact.     

First measurements of the HCFC-142b trend from atmospheric chemistry experiment (ACE) solar occultation spectra

The first measurement of the HCFC-142b (CH₃CClF₂) trend near the tropopause has been derived from volume mixing ratio (VMR) measurements at northern and southern hemisphere mid-latitudes for the 2004–2008 time period from spaceborne solar occultation observations recorded at 0.02 cm⁻¹ resolution with the ACE (atmospheric chemistry experiment) Fourier transform spectrometer. The HCFC-142b molecule is currently the third most abundant HCFC (hydrochlorofluorocarbon) in the atmosphere and ACE measurements over this time span show a continuous rise in its volume mixing ratio. Monthly average measurements at northern and southern hemisphere mid-latitudes have similar increase rates that are consistent with surface trend measurements for a similar time span. A mean northern hemisphere profile for the time span shows a near constant VMR at 8–20 km altitude range, consistent on average for the same time span with in situ results. The nearly constant vertical VMR profile also agrees with model predictions of a long lifetime in the lower atmosphere.     

Reversed-phase poly(styrene-divinylbenzene) materials optimised for large scale preparative and process purification of synthetic peptides and recombinant proteins

Rigid macroporous copolymers of styrene and divinylbenzene have been designed for large-scale preparative and process-scale purification of synthetic peptides and recombinant proteins. The polymeric particles are mechanically stable and hence able to operate at the required high linear velocities. The pore size and pore morphology has been optimised to enable unhindered solute diffusion whilst providing maximum available surface area to enhance loading capacity. A 100 A pore size has been developed for synthetic peptides and a 300 A pore size for recombinant proteins. Precise control of particle size, within the range 10 to 20 microm, is possible which together with the very narrow particle size distribution enables maximum resolution/loading to be obtained within the pressure limits of the instrumentation being used. The chemical stability of the polymer enables cleaning in place with 1 M sodium hydroxide without particle dissolution or a deterioration in selectivity. These materials can be packed into compression hardware and are manufactured as single lots up to 100 kg (300 l) batch size.     

A dithienylethene-tethered beta-cyclodextrin dimer as a photoswitchable host

The binding of TSPP by a dithienylethene-tethered beta-cyclodextrin dimer can be altered reversibly by irradiation with light.