91 research outputs found
OUR EXPERIENCE IN TREATMENT OF CHILDISH ALLERGIC RHINOSINUITIS WITH HYDROCORTIS0N-PHON0PH0RESIS
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Enhanced Raman Microprobe Imaging of Single-Wall Carbon Nanotubes
We explore Raman microprobe capabilities to visualize single wall carbon nanotubes (SWCNTs). Although this technique is limited to a micron scale, we demonstrate that images of individual SWCNTs, bundles or their agglomerates can be generated by mapping Raman active elementary excitations. We measured the Raman response from carbon vibrations in SWCNTs excited by confocal scanning of a focused laser beam. Carbon vibrations reveal key characteristics of SWCNTs as nanotube diameter distribution (radial breathing modes, RBM, 100-300 cm(exp -1)), presence of defects and functional groups (D-mode, 1300-1350 cm(exp -1)), strain and oxidation states of SWCNTs, as well as metallic or semiconducting character of the tubes encoded in the lineshape of the G-modes at 1520-1600 cm(exp - 1). In addition, SWCNTs are highly anisotropic scatterers. The Raman response from a SWCNT is maximal for incident light polarization parallel to the tube axis and vanishing for perpendicular directions. We show that the SWCNT bundle shape or direction can be determined, with some limitations, from a set of Raman images taken at two orthogonal directions of the incident light polarization
Raman scattering study of (KSr)FeAs ( = 0.0, 0.4)
Polarized Raman spectra of non-superconducting SrFeAs and
superconducting KSrFeAs ( K) are reported.
All four phonon modes (A + B + 2E) allowed by symmetry, are
found and identified. Shell model gives reasonable description of the spectra.
No detectable anomalies are observed near the tetragonal-to-orthorhombic
transition in SrFeAs or the superconducting transition in
KSrFeAs.Comment: 4 pages, 4 figures, 2 table
Comment on "Raman spectroscopy study of NaxCoO2 and superconducting NaxCoO2 yH2O"
The effect of surface degradation of the thermolectric cobaltite on Raman
spectra is discussed and compared to experimental results from Co3O4 single
crystals. We conclude that on NaCl flux grown NaxCoO2 crystals a surface layer
of Co3O4 easily forms that leads to the observation of an intense phonon around
700 cm-1 [Phys. Rev. B 70, 052502 (2004)]. Raman spectra on freshly cleaved
crystals from optical floating zone ovens do not show such effects and have a
high frequency phonon cut-off at approximately 600 cm -1 [Phys. Rev. Lett 96,
167204 (2006)]. We discuss the relation of structural dimensionality,
electronic correlations and the high frequency phonon cut-off of the
thermolectric cobaltite.Comment: 2 pages, 1 figure, to be published in Phys. Rev. B (2007
Co-digestion of waste activated sludge and silaged mix of chicken litter and fodder beet
In order to determine the yield of methane in a Co-degradation study with different substrates. The study involved the following substrates : WAS only; WAS+silage
2:1; WAS+silage 1:1; WAS+silage 1:2. Studieed is the contents of the macro and micronutrient in the tested substrates and biogas yield after methane fermentation.
It was found that major disadvantage of the BMP test is the fact that it does not provide short-term results because of it s duration, methane yield during a shorter period could be predicted by evaluating the reaction rate provided by the rate constant
Phonon and magnon scattering of antiferromagnetic Bi2Fe4O9
The phonon structure of antiferromagnetic Bi2Fe4O9 (space group Pbnm No. 55, TN≈240 K) was studied theoretically by calculations of lattice dynamics and experimentally between 10 and 300 K by polarized Raman spectroscopy. Most of the 12Ag+12B1g+9B2g+9B3g Raman modes were unambiguously identified. Strong second-order scattering was observed for ab-plane-confined incident and scattered light polarizations. In addition to the phonon-scattering, broad Raman bands with typical characteristics of magnon scattering appear below TN. The magnon bands are analyzed on the basis of magnetic structure of Bi2Fe4O9 and attributed to two- magnon excitations
Charge transfer fluctuation, wave superconductivity, and the Raman phonon in the Cuprates: A detailed analysis
The Raman spectrum of the phonon in the superconducting cuprate
materials is investigated theoretically in detail in both the normal and
superconducting phases, and is contrasted with that of the phonon. A
mechanism involving the charge transfer fluctuation between the two oxygen ions
in the CuO plane coupled to the crystal field perpendicular to the plane is
discussed and the resulting electron-phonon coupling is evaluated. Depending on
the symmetry of the phonon the weight of different parts of the Fermi surface
in the coupling is different. This provides the opportunity to obtain
information on the superconducting gap function at certain parts of the Fermi
surface. The lineshape of the phonon is then analyzed in detail both in the
normal and superconducting states. The Fano lineshape is calculated in the
normal state and the change of the linewidth with temperature below T is
investigated for a pairing symmetry. Excellent agreement is
obtained for the phonon lineshape in YBaCuO. These
experiments, however, can not distinguish between and a
highly anisotropic -wave pairing.Comment: Revtex, 21 pages + 4 postscript figures appended, tp
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