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Core Diameter (core + diameter)
Selected AbstractsPBG Fibers for Gas Concentration MeasurementPLASMA PROCESSES AND POLYMERS, Issue 7-8 2007Joanna Paw Abstract The idea of a high-sensitivity gas concentration measuring system based on a photonic bandgap fiber (PBG fiber) is studied. Several types of PBG fibers of various parameters have been designed. Core diameters range from 10.9 to 26.25 µm. The capillary gas flow rate within the fiber has been simulated and measured. The attenuation of newly produced fibers is investigated and the concentration of ammonia gas is measured using a proposed sensing system. A new method for cutting the fiber using an Ar ion beam in a vacuumed chamber is tested to obtain the required angle of the fiber's end, and to avoid the destruction of the cladding structure. [source] Nanoparticle-Structured Ligand Framework as Electrode InterfacesELECTROANALYSIS, Issue 1-2 2004Nancy Abstract Nanostructured thin film assemblies derived from metal or oxide nanocrystal cores and functionalized molecular shells provide large surface-to-volume ratio and three-dimensional ligand frameworks. In this article, we report results of an investigation of the nanostructured materials for electroanalysis. Monolayer-capped gold nanoparticles of 2-nm core diameter and carboxylic acid-functionalized alkyl thiols were assembled on electrode surfaces via an exchange-crosslinking-precipitation reaction route, and were studied as a model system. The network assemblies exhibit open frameworks in which the void space forms channels with the nanometer sized cores defining its size and the shell structures defining its chemical specificity. Such nanostructures were exploited to demonstrate the viability of responsive materials for interfacial incorporation and fluxes of ionic species. The nanomaterials were characterized by an array of techniques, including cyclic voltammetry, electrochemical quartz-crystal nanobalance, flow injection analysis, and surface infrared reflection spectroscopy. The current responses and mass loading as a result of the incorporation of ionic species into the nanostructure have been analyzed. The potential application of the nanostructured thin films for electrochemical detection in microfluidic systems is also discussed. [source] Synthesis of Core,Shell Inorganic NanotubesADVANCED FUNCTIONAL MATERIALS, Issue 15 2010Ronen Kreizman Abstract New materials and techniques pertaining to the synthesis of inorganic nanotubes have been ever increasing since the initiation of the field in 1992. Recently, WS2 nanotubes, which are produced now in large amounts, were filled with molten lead iodide salt by a capillary wetting process, resulting in PbI2@WS2 core,shell nanotubes. This work features progress in the synthesis of new core,shell nanotubes, including BiI3@WS2 nanotubes produced in a similar same manner. In addition, two new techniques for obtaining core,shell nanotubes are presented. The first is via electron-beam irradiation, i.e., in situ synthesis within a transmission electron microscope. This synthesis results in SbI3 nanotubes, observed either in a hollow core of WS2 ones (SbI3@WS2 nanotubes), or atop of them (WS2@SbI3 nanotubes). The second technique involves a gaseous phase reaction, where the layered product employs WS2 nanotubes as nucleation sites. In this case, the MoS2 layers most often cover the WS2 nanotube, resulting in WS2@MoS2 core,shell nanotubes. Notably, superstructures of the form MoS2@WS2@MoS2 are occasionally obtained. Using a semi-empirical model, it is shown that the PbI2 nanotubes become stable within the core of MoS2 nanotubes only above a critical core diameter of the host (>12,nm); below this diameter the PbI2 crystallizes as nanowires. These model calculations are in agreement with the current experimental observations, providing further support to the growth mechanism of such core,shell nanotubes. [source] Facile and Scalable Synthesis of Tailored Silica "Nanorattle" StructuresADVANCED MATERIALS, Issue 37 2009Dong Chen Silica "nanorattles" are fabricated by means of selective etching of ingeniously designed organic,inorganic hybrid silica spheres with a three-layer "sandwich" structure. The size (95,645,nm), shell thickness, and core diameter of the monodisperse nanorattles can be precisely controlled, even in gram-scale production. This method is also shown to be promising for development as a general method for synthesis of rattle-type functional nanomaterials. [source] In vitro evaluation of the effect of core diameter for removing radicular post with ultrasoundJOURNAL OF ORAL REHABILITATION, Issue 6 2004E. Alfredo summary, The removal of radicular posts for endodontic reasons as well as their replacement is a common procedure in dental practice. The use of ultrasound is becoming a standard practice since it reduces the stress to displace the core from the canal minimizing the risks of root fractures, perforations and further wearing of dental structure. Thus, the objective of this study was to evaluate the effect of a reduction in the core diameter when removing radicular posts with ultrasound. Twenty-four teeth were divided in two groups. Group I received posts with the dowel and core of the same diameter (1·7 mm) and group II received posts with the dowel diameter 2 mm larger (3·7 mm) than the core diameter. Zinc phosphate cement was used to cement the posts in all groups. Half of the samples of each group received ultrasonic energy for 8, 2 min for each face. All samples were submitted to traction on an Instron machine (model 4444). Data were analysed statistically with anova and the Tukey test, revealing significant differences (P < 0·05) between groups. The authors concluded that the mean tension necessary to displace the posts from the roots was reduced by 26% when ultrasound was applied. The reduction of the post-diameter reduced the necessary tension to remove them by 24% compared with larger posts. [source] Actively Q-switched, diode pumped thulium laserLASER PHYSICS LETTERS, Issue 12 2007J.K. Jabczynski Abstract 6 W of output power and near 50% slope efficiency with respect to absorbed pump power was demonstrated in freerunning mode for a short, 40-mm long resonator. The uncoated, with 3.5% dopant of thulium YLF rod of.3× 8 mm size wrapped with indium foil was mounted in copper heat-sink maintaining 293 K temperature of coolant water and inserted in a short, 40-mm long resonator. For pumping the fiber coupled (0.4 mm core diameter) laser diode bar at 792-nm wavelength was deployed. The fused silica acousto-optic modulator with above 80% diffraction efficiency for 25-W power of RF was taken as the Q-switch for such a laser. In the best case of Qswitching mode up to 2-mJ output energy with 20-ns pulse duration corresponding to 100-kW peak power was demonstrated for rep. rate of a few Hz. Emission wavelength was around 1904 nm for both free-running and Q-switching regimes. (© 2007 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Large-core-area hollow photonic-crystal fibersLASER PHYSICS LETTERS, Issue 11 2004S.O. Konorov Abstract We demonstrate hollow-core photonic-crystal fibers (PCFs) with a core diameter of 45 ,m and a period of the photonic-crystal cladding of 7 ,m. These fibers are shown to allow a waveguide delivery of 4-mJ 15-ns pulses of 1.06- ,m radiation of a Q -switched Nd: YAG laser. Hollow PCFs reported in this work help to bridge the gap between standard, solid-cladding hollow fibers and hollow PCFs in terms of effective guided-mode areas, offering attractive solutions for high-field physics, laser technologies, and ultrafast photonics. (© 2004 by ASTRO, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Coupled-mode analysis of nonlinear fiber couplers with different core parametersMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2007Min Liu Abstract A nonlinear two-core fiber coupler with unequal cores (phase-mismatched) is analyzed by using coupled-mode theory. Based on the solutions of the coupled-mode equations, it is demonstrated that even though there is a difference in core diameter, the unequal-core fiber coupler (phase-mismatched) can function as a twin-core fiber coupler (phase-matched) by increasing the refractive index of the small core. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49:1051,1053, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22350 [source] Influence of stability on the acute toxicity of CdSe/ZnS nanocrystals to Daphnia magnaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2010Heather E. Pace Abstract The acute toxicity of polymer-coated CdSe/ZnS quantum dots (QDs) to Daphnia magna was investigated using 48-h exposure studies. The principal objective was to relate the toxicity of QDs to specific physical and chemical aspects of the QD. As such, two different CdSe core diameters, 2,nm QDs (green-emitting) and 5,nm QDs (red-emitting), and two different surface coatings, polyethylene oxide (PEO) and 11-mercaptoundecanoic acid (MUA) were studied. The QDs were characterized before and after the 48-h exposure using fluorescence, ultrafiltrations (3 kDa), and inductively coupled plasma-atomic emission spectrometry (ICP-AES) metal analysis. In addition, flow field flow fractionation-inductively coupled plasma-mass spectrometry (Fl FFF-ICP-MS) was used as a more extensive characterization technique to determine particle size and composition as well as identify other potential constituents in the QD solutions. The more stable QDs (PEO) were found to be less acutely toxic than the QDs with accelerated dissolution (MUA), suggesting QD stability has significant impact on the nanoparticles' short-term toxicity. The emergence of dissolved Cd2+ in solution indicates that the toxicity of the MUA QDs is likely due to Cd poisoning, and a mass-based dose response occurred as a consequence of this mode of action. Alternatively, the PEO QDs caused acute toxicity without observed particle dissolution (i.e., no detectable metals were solubilized), suggesting an alternative mode of toxic action for these nanoparticles. Results of the present study suggest that using particle number, instead of mass, as a dose metric for the PEO QDs, produces markedly different conclusions, in that smaller core size does not equate to greater toxicity. Environ. Toxicol. Chem. 2010;29:1338,1344. © 2010 SETAC [source] | ||||||||||