5,497 research outputs found
Production of superconductor/carbon bicomponent fibers
Certain materials are unable to be drawn or spun into fiber form due to their improper melting characteristics or brittleness. However, fibrous samples of such materials are often necessary for the fabrication of intricate shapes and composites. In response to this problem, a unique process, referred to as the piggyback process, was developed to prepare fibrous samples of a variety of nonspinnable ceramics. In this technique, specially produced C shaped carbon fibers serve as micromolds to hold the desired materials prior to sintering. Depending on the sintering atmosphere used, bicomponent or single component fibers result. While much has been shown worldwide concerning the YBa2Cu3O(7-x) superconductor, fabrication into unique forms has proven quite difficult. However, a variety of intricate shapes are necessary for rapid commercialization of the superconducting materials. The potential for producing fibrous samples of the YBa2Cu3O(7-x) compound by the piggyback process is being studied. Various organic and acrylic materials were studied to determine suspending ability, reactivity with the YBa2Cu3O(7-x) compound during long term storage, and burn out characteristics. While many questions were answered with respect to the interfacial reactions between YBa2Cu3O(7-x) and carbon, much work is still necessary to improve the quality of the sintered material if the fibers produced are to be incorporated into useful composite or cables
Production of superconductor/carbon bicomponent fibers
Certain materials are unable to be drawn or spun into fiber form due to their improper melting characteristics or brittleness. However, fibrous samples of such materials are often necessary for the fabrication of intricate shapes and composites. In response to this problem, a unique process, referred to as the piggyback process, was developed to prepare fibrous samples of a variety of nonspinnable ceramics. In this technique, specially produced C-shaped carbon fibers serve as micromolds to hold the desired materials prior to sintering. Depending on the sintering atmosphere used, bicomponent or single component fibers result. While much has been demonstrated worldwide concerning the YBa2Cu3O(7-x) superconductor, fabrication into unique forms has proven quite difficult. However, a variety of intricate shapes are necessary for rapid commercialization of the superconducting materials. The potential for producing fibrous samples of the YBa2Cu3O(7-x) compound by the piggyback process is being investigated. Various organic and acrylic materials were investigated to determine suspending ability, reactivity with the YBa2Cu3O(7-x) compound during long term storage, and burn out characteristics. While many questions were answered with respect to the interfacial reactions between YBa2Cu3O(7-x) and carbon, much work is still necessary to improve the quality of the sintered material if the fibers produced are to be incorporated into useful composites or cables. Additional research is necessary to evaluate quality of the barrier layer during long soakings at the peak temperature; adjust the firing schedule to avoid microcracking and improve densification; and increase the solids loading in the superconductive suspension to decrease porosity
Sumoylation silences the plasma membrane leak K+ channel K2P1.
Reversible, covalent modification with small ubiquitin-related modifier proteins (SUMOs) is known to mediate nuclear import/export and activity of transcription factors. Here, the SUMO pathway is shown to operate at the plasma membrane to control ion channel function. SUMO-conjugating enzyme is seen to be resident in plasma membrane, to assemble with K2P1, and to modify K2P1 lysine 274. K2P1 had not previously shown function despite mRNA expression in heart, brain, and kidney and sequence features like other two-P loop K+ leak (K2P) pores that control activity of excitable cells. Removal of the peptide adduct by SUMO protease reveals K2P1 to be a K+-selective, pH-sensitive, openly rectifying channel regulated by reversible peptide linkage
Evidence of Double Phonon Excitations in ^{16}O + ^{208}Pb Reaction
The fusion cross-sections for ^{16}O + ^{208}Pb, measured to high precision,
enable the extraction of the distribution of fusion barriers. This shows a
structure markedly different from the single-barrier which might be expected
for fusion of two doubly-closed shell nuclei. The results of exact coupled
channel calculations performed to understand the observations are presented.
These calculations indicate that coupling to a double octupole phonon excited
state in ^{208}Pb is necessary to explain the experimental barrier
distributions.Comment: 6 pages, 2 figures, To be published in the Proceedings of the FUSION
97 Conference, South Durras, Australia, March 1997 (J. Phys. G
Dynamics of the DBI Spike Soliton
We compare oscillations of a fundamental string ending on a D3-brane in two
different settings: (1) a test-string radially threading the horizon of an
extremal black D3-brane and (2) the spike soliton of the DBI effective action
for a D3-brane. Previous work has shown that overall transverse modes of the
test-string appear as l=0 modes of the transverse scalar fields of the DBI
system. We identify DBI world-volume degrees of freedom that have dynamics
matching those of the test-string relative transverse modes. We show that there
is a map, resembling T-duality, between relative and overall transverse modes
for the test-string that interchanges Neumann and Dirichlet boundary conditions
and implies equality of the absorption coefficients for both modes. We give
general solutions to the overall and relative transverse parts of the DBI
coupled gauge and scalar system and calculate absorption coefficients for the
higher angular momentum modes in the low frequency limit. We find that there is
a nonzero amplitude for l>0 modes to travel out to infinity along the spike,
demonstrating that the spike remains effectively 3+1-dimensional.Comment: 15 pages, 1 figur
Applied Remote Sensing Program (ARSP)
There are no author-identified significant results in this report
Mixed Branes Interaction in Compact Spacetime
We present a general description of two mixed branes interactions. For this
we consider two mixed branes with dimensions p_1 and p_2, in external field
B_{\mu\nu} and arbitrary gauge fields A^1_{\alpha_1} and A^2_{\alpha_2} on the
world volume of them, in spacetime in which some of its directions are
compactified on circles with different radii. Some examples are considered to
clear these general interactions. Finally contribution of the massless states
on the interactions is extracted. Closed string with mixed boundary conditions
and boundary state formalism, provide useful tools for calculation of these
interactions.Comment: 22 pages, to appear in Nucl. Phys.
Reliability of recommended non-invasive chairside screening tests for diabetes-related peripheral neuropathy : a systematic review with meta-analyses
The objective is to determine, by systematic review, the reliability of testing methods for diagnosis of diabetes-related peripheral neuropathy (DPN) as recommended by the most recent guidelines from the International Diabetes Foundation, International Working Group on the Diabetic Foot and American Diabetes Association. Electronic searches of Cochrane Library, EBSCO Megafile Ultimate and EMBASE were performed to May 2021. Articles were included if they reported on the reliability of recommended chairside tests in diabetes cohorts. Quality appraisal was performed using a Quality Appraisal of Reliability Studies checklist and where possible, meta-analyses, with reliability reported as estimated Cohen's kappa (95% CI). Seventeen studies were eligible for inclusion. Pooled analysis found acceptable inter-rater reliability of vibration perception threshold (VPT) (κ=0.61 (0.50 to 0.73)) and ankle reflex testing (κ=0.60 (0.55 to 0.64)), but weak inter-rater reliability for pinprick (κ=0.45 (0.22 to 0.69)) and 128 Hz tuning fork (κ=0.42 (0.15 to 0.70)), though intra-rater reliability of the 128 Hz tuning fork was moderate (κ=0.54 (0.37 to 0.73)). Inter-rater reliability of the four-site monofilament was acceptable (κ=0.61 (0.45 to 0.77)). These results support the clinical use of VPT, ankle reflexes and four-site monofilament for screening and ongoing monitoring of DPN as recommended by the latest guidelines. The reliability of temperature perception, pinprick, proprioception, three-site monofilament and Ipswich touch test when performed in people with diabetes remains unclear
Development of superconducting YBa2Cu3O(x) wires with low resistance electrical contacts
Materials exhibiting superconductivity above liquid nitrogen temperatures (77 K) will enable new applications of this phenomena. One of the first commercial applications of this technology will be superconducting magnets for medical imaging. However, a large number of aerospace applications of the high temperature superconducting materials have also been identified. These include magnetic suspension and balance of models in wind tunnels and resistanceless leads to anemometers. The development of superconducting wires fabricated from the ceramic materials is critical for these applications. The progress in application of a patented fiber process developed by Clemson University for the fabrication of superconducting wires is reviewed. The effect of particle size and heat treatment on the quality of materials is discussed. Recent advances made at Christopher Newport College in the development of micro-ohm resistance electrical contacts which are capable of carrying the highest reported direct current to this material is presented
- …