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A large-mode-area single-mode optical fiber based on leaky-mode filtering was prepared by a modified chemical vapor deposition (MCVD) technique. The fiber has a leaky cladding that discriminates the fundamental mode from higher-order modes. A preliminary version has a 25 μm core diameter and 0.11 numerical aperture. A Gaussian-like mode with 22 μm mode field diameter was observed after 3 m propagation, in agreement with modeling. 相似文献
65.
The fatigue behaviors of two SiC/[SiC+Si3N4] ceramic matrix composites (CMC) were investigated at 1,300°C in laboratory air and in steam. Composites consisted of a crystalline
[SiC+Si3N4] matrix reinforced with either Sylramic™ or Sylramic-iBN fibers (treated Sylramic™ fibers that possess an in situ BN coating)
woven in a five-harness satin weave fabric and coated with a proprietary boron-containing dual-layer interphase. The tensile
stress–strain behaviors were investigated and the tensile properties measured at 1,300°C. Tension–tension fatigue behaviors
of both CMCs were studied for fatigue stresses ranging from 100 to 180 MPa. The fatigue limit (based on a run-out condition
of 2 × 105 cycles) in both air and steam was 100 MPa for the CMC containing Sylramic™ fibers and 140 MPa for the CMC reinforced with
Sylramic-iBN fibers. At higher fatigue stresses, the presence of steam caused noticeable degradation in fatigue performance
of both composites. The retained strength and modulus of all run-out specimens were characterized. The materials tested in
air retained 100% of their tensile strength, while the materials tested in steam retained only about 90% of their tensile
strength. 相似文献
66.
Vipul KumthekarSuresh Kolekar 《Progress in Organic Coatings》2011,72(3):380-386
This article explores the influence of process variation and neutralization of itaconic acid (IA) on polymer properties and paint performance. The study elaborated how the reaction pathway changes the acid distribution in the latexes. The study also investigated the influence on paint performance of degree of neutralization of IA before its incorporation into emulsion. The acid distribution study was done through the conductometric titration method. Latex film properties were studied through differential scanning calorimeter (DSC) and minimum film forming temperature (MFFT). These latexes were formulated in the corresponding paint and study was done using scanning electron microscopy (SEM), which was further correlated with the performance properties of the paint such as scrub, gloss, whiteness and contrast ratio. 相似文献
67.
The article presents an analytical theory for multilayered composite beams subjected to transverse uniformly distributed loads. The formulation is based on a layerwise model characterized by third-order approximation of the axial displacements and fourth-order approximation of the transverse displacements. The layerwise kinematical model is rewritten in terms of generalized variables. The beam equilibrium equations, expressed in terms of stress resultant, allow writing the boundary value governing problem. The layerwise fields are obtained by postprocessing steps. The main advantage is to ensure the accuracy level associated to the layerwise formulations preserving the computational efficiency of the equivalent-single-layer theories. 相似文献
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69.
Templated synthesis of single-component polymer capsules and their application in drug delivery 总被引:1,自引:0,他引:1
We report a general and facile approach for the fabrication of a new class of monodispersed, single-component and thick-walled polymer nanocapsules via the single-step assembly of macromolecules in solid core/mesoporous shell (SC/MS) silica particle templates, followed by cross-linking of the macromolecules and removal of the SC/MS templates. The general applicability of this approach is demonstrated by the preparation of nanocapsules using various polymers, including synthetic polyelectrolytes, polypeptides, and polypeptide-drug conjugates. The potential of doxorubicin (Dox)-loaded poly(L-glutamic acid) nanocapsules in tumor therapy applications is demonstrated via in vitro degradation experiments, which show a near-linear release of the Dox in the presence of a lysosomal hydrolase, nanocapsule uptake by human colorectal tumor cells, and delivery of the anticancer drug into the tumor cells, leading to tumor cell death. 相似文献
70.
Residues of clopyralide in strawberries treated with herbicide preparation Lontrel 300 were determined using gas chromatographic method. The decrease of clopyralide content during the processing of contaminated fruits was observed. The rate of decomposition of this compound in model solutions (held at 75 degrees C, pH 3.6) followed first-order kinetics. 2,5-dicloropyridine was proved to originate under these conditions from parent compound. 相似文献