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981.
Friedrich-Rust M Romenski O Meyer G Dauth N Holzer K Grünwald F Kriener S Herrmann E Zeuzem S Bojunga J 《Ultrasonics》2012,52(1):69-74
Purpose
Real-time tissue elastography, a qualitative elastography method, has shown promising results in the diagnostic work up of thyroid nodules. However, to our knowledge no study has evaluated a quantitative elastography method in the thyroid gland. The present study is a feasibility study evaluating Acoustic Radiation Force Impulse-Imaging, a novel quantitative elastography method in the thyroid gland.Methods
ARFI-imaging involves the mechanical excitation of tissue using short-duration acoustic pulses to generate localized displacements in tissue. The displacements induce a lateral shear-wave propagation which is tracked using multiple laterally positioned ultrasound “tracking“ beams. Inclusion criteria were: thyroid nodules ?1 cm, non-functioning or hypo-functioning on radionuclide scanning, and cytological/histological assessment of thyroid nodule as reference method. All patients received conventional ultrasound, and examination of the thyroid gland including Power Doppler Ultrasound using a 9 MHz linear transducer, in addition real-time elastography (RTE) was performed at 9 MHz frequency and ARFI-imaging was performed at 4 MHz using Siemens (ACUSON S2000) B-mode-ARFI combination transducer.Results
Sixty nodules in 55 patients were analyzed. Three nodules were papillary carcinoma. The stiffer the tissue the faster the shear wave propagates. The results obtained indicated that the shear wave velocity in thyroid lobes ranged between 0.5 and 4.9 m/s. The median velocity of ARFI-imaging in the healthy nodule-free thyroid gland, as well as in benign and malignant thyroid nodules was 1.98 m/s (range: 1.20-3.63 m/s), 2.02 m/s (range: 0.92-3.97 m/s), and 4.30 m/s (range: 2.40-4.50 m/s), respectively. While no significant difference in median velocity was found between healthy thyroid tissue and benign thyroid nodules, a significant difference was found between malignant thyroid nodules on the one hand and healthy thyroid tissue (p = 0.018) or benign thyroid nodules (p = 0.014) on the other hand. Specificity of ARFI-imaging for the differentiation of benign and malignant thyroid nodules was comparable with RTE (91-95%).Conclusions
ARFI can be performed in the thyroid tissue with reliable results. 相似文献982.
We predict that a photonic crystal fiber whose strands are filled with a defocusing nonlinear medium can support stable bright solitons and also vortex solitons if the strength of the defocusing nonlinearity grows toward the periphery of the fiber. The domains of soliton existence depend on the transverse growth rate of the filling nonlinearity and nonlinearity of the core. Remarkably, solitons exist even when the core material is linear. 相似文献
983.
The behavior of scalar beams with nonuniform correlations in isotropic random media is investigated. An example illustrates the fact that the off-axis intensity maximum formed in the transverse cross section of a nonuniformly correlated beam on propagation in free space is suppressed when it passes at sufficiently large distances from its source through the isotropic turbulent atmosphere. 相似文献
984.
We study how the orientation of the optic axis affects single-scattering properties for small, birefringent calcite particles simulated using DDSCAT 7.1.1. We consider two irregular model particles, a flake and a rhomboid, in either a (i)?fixed or (ii)?random orientation. Simulations are performed for three volume-equivalent radii of 0.1, 0.45, and 1.0?μm. For each target, we repeat the computations for three sets of orientations of the optic axis. When a fixed spatial orientation of the target is considered, the simulations are significantly affected by the orientation of the optic axis. However, the effect is considerably weaker when assuming the same targets in random spatial orientation. 相似文献
985.
Belfield KD Bondar MV Morales AR Yue X Luchita G Przhonska OV 《The journal of physical chemistry. C, Nanomaterials and interfaces》2012,116(20):11261-11271
The synthesis, linear photophysical properties, two-photon absorption (2PA), excited-state transient absorption, and gain spectroscopy of a new fluorene derivative tert-butyl 4,4'-(4,4' (1E,1'E)-2,2'-(9,9-bis(2- (2-ethoxyethoxy)ethyl)-9H-fluorene-2,7-diyl)bis(ethene-2,1-diyl)bis(4,1 phenylene)]dipiperazine-1-carboxylate (1) are reported. The steady-state linear absorption and fluorescence spectra, along with excitation anisotropy, fluorescence lifetimes, and photochemical stability of 1 were investigated in a number of organic solvents at room temperature. The 2PA spectra of 1 with a maximum cross-section of ~ 300 GM were obtained with a 1 kHz femtosecond laser system using open-aperture Z-scan and two-photon-induced fluorescence methods. The transient excited-state absorption (ESA) and gain kinetics of 1 were investigated by a femtosecond pump-probe methodology. Fast relaxation processes (~1-2 ps) in the gain and ESA spectra of 1 were revealed in ACN solution, attributable to symmetry-breaking effects in the first excited state. Efficient superfluorescence properties of 1 were observed in a nonpolar solvent under femtosecond excitation. One- and two-photon fluorescence microscopy imaging of HCT 116 cells incubated with probe 1 was accomplished, suggesting the potential of this new probe in two-photon fluorescence microscopy bioimaging. 相似文献
986.
987.
CB Liu RA Ferreira FA Almeida Paz A Cadiau LD Carlos LS Fu J Rocha FN Shi 《Chemical communications (Cambridge, England)》2012,48(64):7964-7966
Mixed zinc-lanthanide (Zn-Ln) metal-organic frameworks (MOFs) based on the 3,5-pyrazoledicarboxylate ligand exhibit an unusual three-dimensional (3D) inorganic subnetwork and display highly efficient photoluminescence. 相似文献
988.
Formation and characterization of phosphate-modified silicate materials derived from sol–gel process
Anastasia Epiphanova Oleg Magaev Olga Vodyankina 《Journal of Sol-Gel Science and Technology》2012,61(3):509-517
Phosphate-containing silicate materials prepared using sol–gel method from Si(OC2H5) were investigated at the variation of the amount of phosphate modifier from 5 to 50 wt% in term of P2O5. Chemical composition, textural and structural properties of these materials were characterized by FTIR-spectroscopy, TEM,
X-ray diffraction and nitrogen adsorption. It was shown that the materials posse monomodal pore size distribution of 5–20 nm
for the samples dried at 100 °C and 40–60 nm for the specimens calcined at 600 °C. The mean pore size and surface area depended
on the amount of phosphoric acid. Before the stage of high temperature treatment phosphoric acid, introduced into the structure
of the materials as a modifying agent, was uniformly distributed inside a porous space of the material and was not chemically
bonded with silicate. After high temperature treatment both chemical interaction of silicate with phosphate, providing the
formation of silicate-phosphate structures, as well as redistribution of free modifier from the bulk of granules to their
surface took place. The polyphosphate layer is formed on the material surface closing the internal porous space. However,
in this case a part of the phosphate modifier remains chemically unbound to SiO2 structure. 相似文献
989.
Igor Pritula Olga Bezkrovnaya Alexander Lopin Marina Kolybaeva Yuri Gurkalenko Viacheslav Puzikov Viacheslav Maslov Anna Plaksiy 《Journal of Sol-Gel Science and Technology》2012,63(3):389-394
SiO2 matrices with incorporated molecules of Rhodamine 6G and Rhodamine 800 laser dyes were synthesized by the sol?Cgel method. The spectral properties of the matrices were studied. It was found that the incorporation of Rhodamine 6G molecules into the xerogel network decreased their association. The influence of the molar ratio of water and formamide on the transparency of the samples was studied. Laser emission of SiO2 matrices activated with Rhodamine 800 was obtained in the near infrared spectral range. The values of laser spectrum halfwidth of SiO2 matrices with Rhodamine 6G and Rhodamine 800 are 2?C6?nm. A well-defined structure of the laser emission spectra of the matrices at microsecond pumping duration testifies to their relatively high optical quality. 相似文献
990.
Gensch T Rönnefahrt M Czerwonka R Jäger A Kataeva O Bauer I Knölker HJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(3):770-776
Pd(II) caught in the act: The diaryl Pd(II) intermediate of a Pd(II)-catalyzed oxidative biaryl bond formation proceeding via a double C-H bond activation has been isolated and fully characterized, including an X-ray crystal structure analysis. Stabilization due to chelation by adjacent pivaloyloxy and acetyl groups has allowed the isolation of this long-sought crucial intermediate. On gentle warming, the complex is transformed into a carbazole product, and the catalytically active Pd(II) species is regenerated by oxidation with Cu(II). 相似文献