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Various Diameters (various + diameter)
Selected AbstractsShape-Memory Stapes Prosthesis for Otosclerosis SurgeryTHE LARYNGOSCOPE, Issue 8 2005Glenn W. Knox MD Abstract Objectives: The aim of this study was to determine the efficacy of a shape-memory alloy, Nitinol, as a component of an improved stapes prosthesis. Study Design: Prospective laboratory and clinical study to develop a Nitinol stapes prosthesis. Methods: Various diameters of Nitinol wire and temperature transition variants were analyzed with regard to ease of deformation, response to heating, and strength. The size and geometry of the closed hook was determined by measurement of 50 incus cadaver bones. Several heat sources for activating the shape memory were evaluated, including electrocautery, lasers, and warm water. Trial surgeries were then performed on human temporal bones in the laboratory. The closure characteristics of the Nitinol loop were studied. Magnetic resonance imaging (MRI) testing at 1.5 Tesla was performed to determine safety during MRI studies. Preliminary human subject trials were then instituted. Results: In all cases, a low heat condition was ample to activate the shape memory characteristics of the hook and return it to a closed position after it had been opened. Laser power was generally set well below the power needed for removing bone. The Nitinol loop closed snugly around the incus with application to the top of the hook with a low temperature laser setting. Almost any heat source was effective. MRI testing at 1.5 Tesla showed no movement of the prosthesis. Preliminary results in human subjects showed excellent air-bone closure. The Nitinol loop holds uniform contact around the incus. Conclusions: The Nitinol piston greatly simplifies the stapedectomy procedure by taking the need for a hand operated instrument out of the surgeon's hands. Because of the nature of the Nitinol wire, it can never over-crimp. All these characteristics make the prosthesis advantageous for otosclerosis surgery. [source] Volume of a liquid drop detaching from a sphereHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 6 2010Kenji Katoh Abstract A theoretical and experimental study is conducted to investigate the detached volume from a pendant drop on the surface of a sphere. Observation of drop detachment by high-speed video camera reveals that the movement of the upper part of the neck of the drop is quite slow compared to that of the detaching lower part. The surface profile of the upper part was calculated approximately as a static problem using the axisymmetric Laplace equation. Using the drop profile, the system energy, including the work done by the solid,liquid wetting behavior, was calculated. Based on the condition of minimum energy, the volume of the detached part V was calculated. The volume V increases with the sphere diameter and approaches the value for the pendant drop attached to a plate. In addition, V is strongly dependent on the wettability between the sphere and the liquid and decreases with the receding contact angle. The detached volume of the water drop was measured for spheres of porous brick of various diameters. The experimental and theoretical results were found to be in good agreement. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/htj.20305 [source] Fabrication of Low-Temperature Co-Fired Ceramics Micro-Fluidic Devices Using Sacrificial Carbon LayersINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2005H. Birol Ease of fabrication and design flexibility are two attractive features of low-temperature co-fired ceramics (LTCC) technology for fabrication of complex micro-fluidic devices. Such structures are designed and processed using different shaping methods, the extent and complexity of which depends on the final device specifications (dimensions, and mechanical and functional properties). In this work, we propose a sacrificial layer method based on carbon-black paste, which burns out during the LTCC firing stage. The article will summarize the preparation of the paste, influence of processing conditions on the final dimensions, and demonstrate the mechanically integrated structures obtained using this technique. Some of these are membranes of various diameters (7,12 mm) with a thickness of 40 ,m and a variety of internal spacing (15,60 ,m), free-hanging thick-film resistor bridges on LTCC for heating micro-volumes. The main methods of the study will be thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and dilatometry in addition to electronic instruments for device characterization. [source] A case of erythema elevatum diutinum associated with breast carcinomaINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 11 2005Fikriye Yilmaz MD A 53-year-old woman diagnosed with invasive ductal-type breast carcinoma was referred to our clinic with red,purple lesions on the hands and legs. She had neither pruritus nor pain. The first lesion developed on the dorsal hand. In the following days, new lesions appeared on the extensor surface of the legs. The patient had been treated with modified radical mastectomy and three courses of cyclophosphamide, adriamycin, and fluorouracil chemotherapy. Dermatologic examination revealed reddish-violaceous papules and plaques ranging from a few millimeters to 2 cm in diameter, bilaterally located on the dorsal hands, especially over the metacarpophalangeal and interphalangeal joints (Fig. 1). Multiple red,purple, circumscribed papules and plaques of various diameters were observed bilaterally over the shins (Fig. 2). The largest of these plaques showed an annular configuration. The nails showed distal subungual keratosis and yellow discoloration. The rest of the physical examination was normal. Figure 1. Violaceous papules and plaques on the dorsal hands Figure 2. Red,purple, circumscribed, papules and plaques over the shins A biopsy taken from the medial side of the shin revealed a predominantly neutrophilic infiltrate and nuclear dust around the dermal vessels and orthokeratotic stratum corneum (Fig. 3). Figure 3. Predominantly neutrophilic infiltrate and nuclear dust around the dermal vessels and orthokeratotic stratum corneum (hematoxylin and eosin stain, ×100) Complete blood count, routine biochemical tests and fasting lipids, serologic tests of bacterial and viral agents, serum electrophoresis, and serologic profiles for autoimmune connective tissue diseases revealed normal results. Mycologic examination of nail clippings did not show any evidence of fungal infection. In the light of our clinical and histopathologic findings, a diagnosis of erythema elevatum diutinum was made, and the patient was given topical clobetasol propionate therapy. Complete clearance was achieved in 3 weeks (Fig. 4). After six courses of cyclophosphamide, adriamycin, and fluorouracil chemotherapy, and radiotherapy, no recurrence of erythema elevatum diutinum lesions was observed. Figure 4. Healed lesion 3 weeks after high-potency topical glucocorticoids [source] Cover Picture: Nanostructured Electrodes and the Low-Temperature Performance of Li-Ion Batteries (Adv. Mater.ADVANCED MATERIALS, Issue 1 20051/2005) Abstract The cover image shows a scanning electron micrograph of a commercially available track-etch polycarbonate filter. This porous membrane serves as the host for the template-synthesis of V2O5 nanowires of various diameters. Nanowires that are 70,nm in diameter are shown in the inset. Because V2O5 reversibly intercalates Li-ions, it has potential for use as a cathode material in Li-ion batteries. On p.,125, Sides and Martin report the use of these V2O5 nanowires as tools to investigate the poor low-temperature performance of Li-ion batteries. [source] Accuracy of LED and Halogen Radiometers Using Different Light SourcesJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 4 2006Howard W. Roberts dmd ABSTRACT Purpose:, To determine the accuracy of commercially available, handheld light-emitting diode (LED) and halogen-based radiometers using LED and quartz-tungsten-halogen (QTH) curing lights with light guides of various diameters. Methods:, The irradiance of an LED curing light (L.E.Demetron 1, SDS/Kerr, Orange, CA, USA) and a QTH curing light (Optilux 501, SDS/Kerr) were measured using multiple units of an LED (Demetron L.E.D. Radiometer, SDS/Kerr) and a halogen radiometer (Demetron 100, SDS/Kerr) and compared with each other and to a laboratory-grade power meter (control). Measurements were made using five light guides with distal light guide diameters of 4, 7, 8, 10, and 12.5 mm. For each light guide, five readings were made with each of three radiometers of each radiometer type. Data were analyzed with two-way analysis of variance/Tukey; ,=0.05. Results:, In general, both handheld radiometer types exhibited significantly different irradiance readings compared with the control meter. Additionally, readings between radiometer types were found to differ slightly, but were correlated. In general, the LED radiometer provided slightly lower irradiance readings than the halogen radiometer, irrespective of light source. With both types of handheld radiometers, the use of the larger-diameter light guides tended to overestimate the irradiance values as seen in the control, while smaller-diameter light guides tended to underestimate. CLINICAL SIGNIFICANCE The evaluated LED or halogen handheld radiometers may be used interchangeably to determine the irradiance of both LED and QTH visible-light-curing units. Measured differences between the two radiometer types were small and probably not clinically significant. However, the diameter of light guides may affect the accuracy of the radiometers, with larger-diameter light guides overestimating and smaller-diameter guides underestimating the irradiance value measured by the control instrument. [source] Raman spectra of benzoic acid enhanced by the silver nanoparticles of various sizesJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2010K. H. Zheng Abstract Using sodium borohydride as the reducing agent and polyvinyl pyrrolidone (PVP, MW = 10 000) as the stabilizer, we obtained silver nanoparticles of various diameters (8,78 nm) from silver nitrate aqueous solutions in the concentration range from 0.001 to 0.1 M. The surface-enhanced Raman scattering (SERS) from benzoic acid's ring-breathing mode at 1003 cm,1 was detected from its dilute solutions (,10,2 M) doped with these silver nanoparticles under 488-nm laser excitation. The observed size dependences of SERS intensities fit quite well with those calculated by Schatz's theoretical model for spherical silver nanoparticles. The only exception occurred with the smallest particles (8 nm), possibly due to the failure of Maxwell's electromagnetic theory used in this model. Copyright © 2009 John Wiley & Sons, Ltd. [source] Use of recombinant rotavirus VP6 nanotubes as a multifunctional template for the synthesis of nanobiomaterials functionalized with metalsBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009Germán Plascencia-Villa Abstract The structural characteristics and predefined constant size and shape of viral assemblies make them useful tools for nanobiotechnology, in particular as scaffolds for constructing highly organized novel nanomaterials. In this work it is shown for the first time that nanotubes formed by recombinant rotavirus VP6 protein can be used as scaffolds for the synthesis of hybrid nanocomposites. Rotavirus VP6 was produced by the insect cell-baculovirus expression vector system. Nanotubes of several micrometers in length and various diameters in the nanometer range were functionalized with Ag, Au, Pt, and Pd through strong (sodium borohydride) or mild (sodium citrate) chemical reduction. The nanocomposites obtained were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM) with energy dispersive spectroscopy (EDS), dynamic light scattering, and their characteristic plasmon resonance. The outer surface of VP6 nanotubes had intrinsic affinity to metal deposition that allowed in situ synthesis of nanoparticles. Furthermore, the use of preassembled recombinant protein structures resulted in highly ordered integrated materials. It was possible to obtain different extents and characteristics of the metal coverage by manipulating the reaction conditions. TEM revealed either a continuous coverage with an electrodense thin film when using sodium citrate as reductant or a discrete coverage with well-dispersed metal nanoparticles of diameters between 2 and 9,nm when using sodium borohydride and short reaction times. At long reaction times and using sodium borohydride, the metal nanoparticles coalesced and resulted in a thick metal layer. HRTEM-EDS confirmed the identity of the metal nanoparticles. Compared to other non-recombinant viral scaffolds used until now, the recombinant VP6 nanotubes employed here have important advantages, including a longer axial dimension, a dynamic multifunctional hollow structure, and the possibility of producing them massively by a safe and efficient bioprocess. Such characteristics confer important potential applications in nanotechnology to the novel nanobiomaterials produced here. Biotechnol. Bioeng. 2009; 104: 871,881. © 2009 Wiley Periodicals, Inc. [source] A New Class of Boron NanotubeCHEMPHYSCHEM, Issue 17 2009Jing Wang Dr. Abstract The configurations, stability and electronic structures of a new class of boron sheet and related boron nanotubes are predicted within the framework of density functional theory. This boron sheet is sparser than those of recent proposals. Our theoretic results show that the stable boron sheet remains flat and is metallic. There are bands similar to the , - bands in graphite near the Fermi level. Stable nanotubes with various diameters and chiral vectors can be rolled from the sheet. Within our study, only the thin (8, 0) nanotube with a band gap of 0.44 eV is semiconducting, while all the other thicker boron nanotubes are metallic, independent of their chirality. It indicates the possibility, in the design of nanodevices, to control the electronic transport properties of the boron nanotube through the diameter. [source] | ||||||||||||||||