Development and Verification of a Weld Simulation Capability for VAST

DTIC Science & Technology

2012-06-01

midsurface -aligned and not contain any offsets (i.e., thickness is symmetric on either side of the midsurface ). Furthermore, for a given element...both above and below the midsurface – i.e., NT /2 elements representing half the thickness both above and below (Figure 35). This operation is easy for

Decay of the zincate concentration gradient at an alkaline zinc cathode after charging

NASA Technical Reports Server (NTRS)

Kautz, H. E.; May, C. E.

1979-01-01

The transport of the zincate ion to the alkaline zinc cathode was studied by observing the decay of the zincate concentration gradient at a horizontal zinc cathode after charging. This decay was found to approximate first order kinetics as expected from a proposed boundary layer model. The concentrations were calculated from polarization voltages. The decay half life was shown to be a linear function of the thickness of porous zinc deposit on the cathode indicating a very rapid transport of zincate through porous zinc metal. The rapid transport is attributed to an electrochemical mechanism. From the linear dependence of the half life on the thickness the boundary layer thickness was found to be about 0.010 cm when the cathode was at the bottom of the cell. No significant dependence of the boundary layer thickness on the viscosity of electrolyte was observed. The data also indicated a relatively sharp transition between the diffusion and convection transport regions. When the cathode was at the top of the cell, the boundary layer thickness was found to be roughly 0.080 cm. The diffusion of zincate ion through asbestos submerged in alkaline electrolyte was shown to be comparable with that predicted from the bulk diffusion coefficient of the zincate ion in alkali.

Thermal Cycling of Thin and Thick Ply Composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tompkins, S.S.; Shen, J.Y.; Lavoie, A.J.

1994-01-01

An experimental study was conducted to determine the effects of ply thickness in composite laminates on thermally induced cracking and changes in the coefficient of thermal expansion (CTE). After a few thermal cycles, laminates with thick-plies cracked, resulting in large changes in CTE. CTE`s of the thin-ply laminates were unaffected by microcracking during the first 500 thermal cycles, whereas, the CTE`s of the thick-ply laminates changed significantly. After about 1500 cycles, microdamage had also reduced the CTE of the thin-ply laminates to a value of about half of their initial value.

Ultralow Damping in Nanometer-Thick Epitaxial Spinel Ferrite Thin Films.

PubMed

Emori, Satoru; Yi, Di; Crossley, Sam; Wisser, Jacob J; Balakrishnan, Purnima P; Khodadadi, Behrouz; Shafer, Padraic; Klewe, Christoph; N'Diaye, Alpha T; Urwin, Brittany T; Mahalingam, Krishnamurthy; Howe, Brandon M; Hwang, Harold Y; Arenholz, Elke; Suzuki, Yuri

2018-06-08

Pure spin currents, unaccompanied by dissipative charge flow, are essential for realizing energy-efficient nanomagnetic information and communications devices. Thin-film magnetic insulators have been identified as promising materials for spin-current technology because they are thought to exhibit lower damping compared with their metallic counterparts. However, insulating behavior is not a sufficient requirement for low damping, as evidenced by the very limited options for low-damping insulators. Here, we demonstrate a new class of nanometer-thick ultralow-damping insulating thin films based on design criteria that minimize orbital angular momentum and structural disorder. Specifically, we show ultralow damping in <20 nm thick spinel-structure magnesium aluminum ferrite (MAFO), in which magnetization arises from Fe 3+ ions with zero orbital angular momentum. These epitaxial MAFO thin films exhibit a Gilbert damping parameter of ∼0.0015 and negligible inhomogeneous linewidth broadening, resulting in narrow half width at half-maximum linewidths of ∼0.6 mT around 10 GHz. Our findings offer an attractive thin-film platform for enabling integrated insulating spintronics.

Sex differences in association of race performance, skin-fold thicknesses, and training variables for recreational half-marathon runners.

PubMed

Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas; Senn, Oliver

2010-12-01

The purpose of this study was to investigate the association between selected skin-fold thicknesses and training variables with a half-marathon race time, for both male and female recreational runners, using bi- and multivariate analysis. In 52 men, two skin-fold thicknesses (abdominal and calf) were significantly and positively correlated with race time; whereas in 15 women, five (pectoral, mid-axilla, subscapular, abdominal, and suprailiac) showed positive and significant relations with total race time. In men, the mean weekly running distance, minimum distance run per week, maximum distance run per week, mean weekly hours of running, number of running training sessions per week, and mean speed of the training sessions were significantly and negatively related to total race time, but not in women. Interaction analyses suggested that race time was more strongly associated with anthropometry in women than men. Race time for the women was independently associated with the sum of eight skin-folds; but for the men, only the mean speed during training sessions was independently associated. Skin-fold thicknesses and training variables in these groups were differently related to race time according to their sex.

Dynamic Harris current sheet thickness from Cluster current density and plasma measurements

NASA Technical Reports Server (NTRS)

Thompson, S. M.; Kivelson, M. G.; Khurana, K. K.; McPherron, R. L.; Weygand, J. M.; Balogh, A.; Reme, H.; Kistler, L. M.

2005-01-01

We use the first accurate measurements of current densities in the plasma sheet to calculate the half-thickness and position of the current sheet as a function of time. Our technique assumes a Harris current sheet model, which is parameterized by lobe magnetic field B(o), current sheet half-thickness h, and current sheet position z(sub o). Cluster measurements of magnetic field, current density, and plasma pressure are used to infer the three parameters as a function of time. We find that most long timescale (6-12 hours) current sheet crossings observed by Cluster cannot be described by a static Harris current sheet with a single set of parameters B(sub o), h, and z(sub o). Noting the presence of high-frequency fluctuations that appear to be superimposed on lower frequency variations, we average over running 6-min intervals and use the smoothed data to infer the parameters h(t) and z(sub o)(t), constrained by the pressure balance lobe magnetic field B(sub o)(t). Whereas this approach has been used in previous studies, the spatial gnuhen& now provided by the Cluster magnetometers were unavailable or not well constrained in earlier studies. We place the calculated hdf&cknessa in a magnetospheric context by examining the change in thickness with substorm phase for three case study events and 21 events in a superposed epoch analysis. We find that the inferred half-thickness in many cases reflects the nominal changes experienced by the plasma sheet during substorms (i.e., thinning during growth phase, thickening following substorm onset). We conclude with an analysis of the relative contribution of (Delta)B(sub z)/(Delta)X to the cross-tail current density during substorms. We find that (Delta)B(sub z)/(Delta)X can contribute a significant portion of the cross-tail c m n t around substorm onset.

Strength of bolted wood joints with various ratios of member thicknesses

Treesearch

Thomas Lee Wilkinson

1978-01-01

Procedures have been recommended–such as in the National Design Specification–for design of bolted joints in wood members where the side members are thicker or thinner than half the main member thickness. However, these recommendations have had no experimental verification up to now. The same is true for joints with other than three members. This study experimentally...

Collective Cell Behavior in Mechanosensing of Substrate Thickness.

PubMed

Tusan, Camelia G; Man, Yu-Hin; Zarkoob, Hoda; Johnston, David A; Andriotis, Orestis G; Thurner, Philipp J; Yang, Shoufeng; Sander, Edward A; Gentleman, Eileen; Sengers, Bram G; Evans, Nicholas D

2018-06-05

Extracellular matrix stiffness has a profound effect on the behavior of many cell types. Adherent cells apply contractile forces to the material on which they adhere and sense the resistance of the material to deformation-its stiffness. This is dependent on both the elastic modulus and the thickness of the material, with the corollary that single cells are able to sense underlying stiff materials through soft hydrogel materials at low (<10 μm) thicknesses. Here, we hypothesized that cohesive colonies of cells exert more force and create more hydrogel deformation than single cells, therefore enabling them to mechanosense more deeply into underlying materials than single cells. To test this, we modulated the thickness of soft (1 kPa) elastic extracellular-matrix-functionalized polyacrylamide hydrogels adhered to glass substrates and allowed colonies of MG63 cells to form on their surfaces. Cell morphology and deformations of fluorescent fiducial-marker-labeled hydrogels were quantified by time-lapse fluorescence microscopy imaging. Single-cell spreading increased with respect to decreasing hydrogel thickness, with data fitting to an exponential model with half-maximal response at a thickness of 3.2 μm. By quantifying cell area within colonies of defined area, we similarly found that colony-cell spreading increased with decreasing hydrogel thickness but with a greater half-maximal response at 54 μm. Depth-sensing was dependent on Rho-associated protein kinase-mediated cellular contractility. Surface hydrogel deformations were significantly greater on thick hydrogels compared to thin hydrogels. In addition, deformations extended greater distances from the periphery of colonies on thick hydrogels compared to thin hydrogels. Our data suggest that by acting collectively, cells mechanosense rigid materials beneath elastic hydrogels at greater depths than individual cells. This raises the possibility that the collective action of cells in colonies or sheets may allow cells to sense structures of differing material properties at comparatively large distances. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Imaging the midcontinent rift beneath Lake Superior using large aperture seismic data

USGS Publications Warehouse

Tréhu, Anne M.; Morel-a-l'Huissier, Patrick; Meyer, R.; Hajnal, Z.; Karl, J.; Mereu, R.F.; Sexton, John L.; Shay, J.; Chan, W. K.; Epili, D.; Jefferson, T.; Shih, X. R.; Wendling, S.; Milkereit, B.; Green, A.; Hutchinson, Deborah R.

1991-01-01

We present a detailed velocity model across the 1.1 billion year old Midcontinent Rift System (MRS) in central Lake Superior. The model was derived primarily from onshore-offshore large-aperture seismic and gravity data. High velocities obtained within a highly reflective half-graben that was imaged on coincident seismic reflection data demonstrate the dominantly mafic composition of the graben fill and constrain its total thickness to be at least 30km. Strong wide-angle reflections are observed from the lower crust and Moho, indicating that the crust is thickest (55–60km) beneath the axis of the graben. The total crustal thickness decreases rapidly to about 40 km beneath the south shore of the lake and decreases more gradually to the north. Above the Moho is a high-velocity lower crust interpreted to result from syn-rift basaltic intrusion into and/or underplating beneath the Archean lower crust. The lower crust is thickest beneath the axis of the main rift half-graben. A second region of thick lower crust is found approximately 100km north of the axis of the rift beneath a smaller half graben that is interpreted to reflect an earlier stage of rifting. The crustal model presented here resembles recent models of some passive continental margins and is in marked contrast to many models of both active and extinct Phanerozoic continental rift zones. It demonstrates that the Moho is a dynamic feature, since the pre-rift Moho is probably within or above the high-velocity lower crust, whereas the post-rift Moho is defined as the base of this layer. In the absence of major tectonic activity, however, the Moho is very stable, since the large, abrupt variations in crustal thickness beneath the MRS have been preserved for at least a billion years.

49 CFR 178.60 - Specification 8AL steel cylinders with porous fillings for acetylene.

Code of Federal Regulations, 2011 CFR

2011-10-01

... thickness; wall stress. The wall thickness/wall stress of the cylinder must conform to the following: (1) The calculated wall stress at 750 psi may not exceed 35,000 psi, or one-half of the minimum ultimate... stress must be made by the formula: S = [P(1.3D2 + 0.4d2)] / (D2 − d2) Where: S = wall stress in pounds...

An Investigation of Four Wings of Square Plan Form at a Mach Number of 6.9 in the Langley 11-inch Hypersonic Tunnel

NASA Technical Reports Server (NTRS)

Mclellan, Charles H; Bertram, Mitchel H; Moore, John A

1957-01-01

The results of pressure-distribution and force tests of four wings at a Mach number of about 6.9 and a Reynolds number of 0.98 x 10(6) in the Langley 11-inch hypersonic tunnel are presented. The wings had a square plan form, a 5-percent-chord maximum thickness, and diamond, half-diamond, wedge, and half-circular sections.

Exterior structural composite panels with southern pine veneer faces and cores of southern hardwood flakes

Treesearch

C. -Y. Hse

1976-01-01

One-half-inch-thick, 8tructural exterior composite panels of various constructions were made in a one-step process, with faces of eouthern pine veneer and corea of mixed southern hardwood flakes. The flakes were precisely machined to be 3/8-inch wide, 3 inches long and 0.015 inch thick. Two veneer, cross-laminated on each face over an oriented flake core, yielded the...

Mathematical models for the reflection coefficients of dielectric half-spaces

NASA Technical Reports Server (NTRS)

Evans, D. D.

1973-01-01

The reflection coefficients at normal incidence are found for a large class of one-dimensionally inhomogeneous or stratified half-spaces, which contain a homogeneous half-space. The formulation of the problem involves a combination of the classical boundary value technique, and the nonclassical principle of invariant imbedding. Solutions are in closed form and expressible in terms of Bessel functions. All results are given in terms of the ratio of the distance between free space and the homogeneous half-space to the wavelength in vacuo. One special case is that of an arbitrary number of layers lying on a homogeneous half-space where the dielectric constant of each layer has a constant gradient. A number of other special cases, limiting cases, and generalizations are developed including one in which the thickness of the top layer obeys a probability distribution.

Axial arrangement of the myosin rod in vertebrate thick filaments: immunoelectron microscopy with a monoclonal antibody to light meromyosin

PubMed Central

1985-01-01

A monoclonal antibody, MF20, which has been shown previously to bind the myosin heavy chain of vertebrate striated muscle, has been proven to bind the light meromyosin (LMM) fragment by solid phase radioimmune assay with alpha-chymotryptic digests of purified myosin. Epitope mapping by electron microscopy of rotary-shadowed, myosin-antibody complexes has localized the antibody binding site to LMM at a point approximately 92 nm from the C-terminus of the myosin heavy chain. Since this epitope in native thick filaments is accessible to monoclonal antibodies, we used this antibody as a high affinity ligand to analyze the packing of LMM along the backbone of the thick filament. By immunofluorescence microscopy, MF20 was shown to bind along the entire A-band of chicken pectoralis myofibrils, although the epitope accessibility was greater near the ends than at the center of the A- bands. Thin-section, transmission electron microscopy of myofibrils decorated with MF20 revealed 50 regularly spaced, cross-striations in each half A-band, with a repeat distance of approximately 13 nm. These were numbered consecutively, 1-50, from the A-band to the last stripe, approximately 68 nm from the filament tips. These same striations could be visualized by negative staining of native thick filaments labeled with MF20. All 50 striations were of a consecutive, uninterrupted repeat which approximated the 14-15-nm axial translation of cross- bridges. Each half M-region contained five MF20 striations (approximately 13 nm apart) with a distance between stripes 1 and 1', on each half of the bare zone, of approximately 18 nm. This is compatible with a packing model with full, antiparallel overlap of the myosin rods in the bare zone region. Differences in the spacings measured with negatively stained myofilaments and thin-sectioned myofibrils have been shown to arise from specimen shrinkage in the fixed and embedded preparations. These observations provide strong support for Huxley's original proposal for myosin packing in thick filaments of vertebrate muscle (Huxley, H. E., 1963, J. Mol. Biol., 7:281-308) and, for the first time, directly demonstrate that the 14-15- nm axial translation of LMM in the thick filament backbone corresponds to the cross-bridge repeat detected with x-ray diffraction of living muscle. PMID:3897243

Cartilage can be thicker in advanced osteoarthritic knees: a tridimensional quantitative analysis of cartilage thickness at posterior aspect of femoral condyles.

PubMed

Omoumi, Patrick; Babel, Hugo; Jolles, Brigitte M; Favre, Julien

2018-04-16

To test, through tridimensional analysis, whether (1) cartilage thickness at the posterior aspect of femoral condyles differs in knees with medial femorotibial osteoarthritis (OA) compared to non-OA knees; (2) the location of the thickest cartilage at the posterior aspect of femoral condyles differs between OA and non-OA knees. CT arthrograms of knees without radiographic OA (n = 30) and with severe medial femorotibial OA (n = 30) were selected retrospectively from patients over 50 years of age. The groups did not differ in gender, age and femoral size. CT arthrograms were segmented to measure the mean cartilage thickness, the maximal cartilage thickness and its location in a region of interest at the posterior aspect of condyles. For the medial condyle, mean and maximum cartilage thicknesses were statistically significantly higher in OA knees compared to non-OA knees [1.66 vs 1.46 mm (p = 0.03) and 2.56 vs 2.14 mm (p = 0.003), respectively]. The thickest cartilage was located in the half most medial aspect of the posterior medial condyle for both groups, without significant difference between groups. For the lateral condyle, no statistically significant difference between non-OA and OA knees was found (p ≥ 0.17). Cartilage at the posterior aspect of the medial condyle, but not the lateral condyle, is statistically significantly thicker in advanced medial femorotibial OA knees compared to non-OA knees. The thickest cartilage was located in the half most medial aspect of the posterior medial condyle. These results will serve as the basis for future research to determine the histobiological processes involved in this thicker cartilage. Advances in knowledge: This study, through a quantitative tridimensional approach, shows that cartilage at the posterior aspect of the medial condyles is thicker in severe femorotibial osteoarthritic knees compared to non-OA knees. In the posterior aspect of the medial condyle, the thickest cartilage is located in the vicinity of the center of the half most medial aspect of the posterior medial condyle. These results will serve as the basis for future research to determine the histobiological processes involved in this thicker cartilage.

Platelet growth factors from allogeneic platelet-rich plasma for clinical improvement in split-thickness skin graft.

PubMed

Sonker, Atul; Dubey, Anju; Bhatnagar, Ankur; Chaudhary, Rajendra

2015-01-01

Platelets are a source of numerous growth factors which facilitate repair and healing. Thus platelet rich plasma has been increasingly used as a treatment modality in the field of reconstructive surgeries for wound healing. This preliminary study was carried out to explore whether platelet growth factors from platelet rich plasma could be used for enhancement of split thickness skin graft survival. Twenty patients (13 males and 7 females) requiring split thickness skin graft for various clinical reasons were enrolled in the study. Platelet rich plasma was collected by apheresis and frozen at -80° C. It was thawed at room temperature immediately before its intended application. PRP was applied only on one half of the wound, while another half served as control. Patient was followed for 6 weeks. The effect was assessed at first dressing in terms of graft uptake and subsequently as time taken for complete healing. There was 100% uptake of the graft in the area where platelet rich plasma was applied. In the control area, there was complete graft loss in 4 cases, partial loss in 7 cases and complete uptake in 9 cases. This study demonstrated promising results on application of PRP to split thickness skin grafts. Further randomized studies with greater sample size may be undertaken to establish platelet rich plasma as a validated treatment modality.

Structural Evolution of Low-Molecular-Weight Poly(ethylene oxide)-block-polystyrene Diblock Copolymer Thin Film

PubMed Central

Huang, Xiaohua

2013-01-01

The structural evolution of low-molecular-weight poly(ethylene oxide)-block-polystyrene (PEO-b-PS) diblock copolymer thin film with various initial film thicknesses on silicon substrate under thermal annealing was investigated by atomic force microscopy, optical microscopy, and contact angle measurement. At film thickness below half of the interlamellar spacing of the diblock copolymer (6.2 nm), the entire silicon is covered by a polymer brush with PEO blocks anchored on the Si substrate due to the substrate-induced effect. When the film is thicker than 6.2 nm, a dense polymer brush which is equal to half of an interlamellar layer was formed on the silicon, while the excess material dewet this layer to form droplets. The droplet surface was rich with PS block and the PEO block crystallized inside the bigger droplet to form spherulite. PMID:24302862

Observation of partial relaxation mechanisms via anisotropic strain relief on epitaxial islands using semiconductor nanomembranes

NASA Astrophysics Data System (ADS)

Rosa, Barbara L. T.; Marçal, Lucas A. B.; Ribeiro Andrade, Rodrigo; Dornellas Pinto, Luciana; Rodrigues, Wagner N.; Lustoza Souza, Patrícia; Pamplona Pires, Mauricio; Wagner Nunes, Ricardo; Malachias, Angelo

2017-07-01

In this work we attempt to directly observe anisotropic partial relaxation of epitaxial InAs islands using transmission electron microscopy (TEM) and synchrotron x-ray diffraction on a 15 nm thick InAs:GaAs nanomembrane. We show that under such conditions TEM provides improved real-space statistics, allowing the observation of partial relaxation processes that were not previously detected by other techniques or by usual TEM cross section images. Besides the fully coherent and fully relaxed islands that are known to exist above previously established critical thickness, we prove the existence of partially relaxed islands, where incomplete 60° half-loop misfit dislocations lead to a lattice relaxation along one of the <110> directions, keeping a strained lattice in the perpendicular direction. Although individual defects cannot be directly observed, their implications to the resulting island registry are identified and discussed within the frame of half-loops propagations.

Observation of partial relaxation mechanisms via anisotropic strain relief on epitaxial islands using semiconductor nanomembranes.

PubMed

Rosa, Barbara L T; Marçal, Lucas A B; Andrade, Rodrigo Ribeiro; Pinto, Luciana Dornellas; Rodrigues, Wagner N; Souza, Patrícia Lustoza; Pires, Mauricio Pamplona; Nunes, Ricardo Wagner; Malachias, Angelo

2017-07-28

In this work we attempt to directly observe anisotropic partial relaxation of epitaxial InAs islands using transmission electron microscopy (TEM) and synchrotron x-ray diffraction on a 15 nm thick InAs:GaAs nanomembrane. We show that under such conditions TEM provides improved real-space statistics, allowing the observation of partial relaxation processes that were not previously detected by other techniques or by usual TEM cross section images. Besides the fully coherent and fully relaxed islands that are known to exist above previously established critical thickness, we prove the existence of partially relaxed islands, where incomplete 60° half-loop misfit dislocations lead to a lattice relaxation along one of the 〈110〉 directions, keeping a strained lattice in the perpendicular direction. Although individual defects cannot be directly observed, their implications to the resulting island registry are identified and discussed within the frame of half-loops propagations.

Bony eminence on the middle cranial fossa corresponding to the temporomandibular joint.

PubMed

Tsunoda, Atsunobu; Sumi, Takuro; Shirakura, Satoshi; Kishimoto, Seiji; Akita, Keiichi

2007-07-01

We report a nameless bony eminence over the temporomandibular joint (TMJ) and its possible clinical significance. Forty-two half heads of 21 UK Caucasian cadavers (61-95 years old, mean 84.3 +/- 8.2 years, male:female = 11:10) were used to investigate the surface of the middle cranial fossa (MCF) over the TMJ. The thickness of the bony roof of the glenoid fossa was also measured. A bony eminence over the glenoid fossa was observed in half of the specimens. Some showed a complete oval bulge, which completely reflected the contour of the glenoid fossa. The others showed a bony bulge, which partially reflected that contour. The mean (+/-SD) thickness of the bone in the roof of glenoid fossa was 1.5 +/- 1.2 mm. The mean bony thickness of specimens showing the eminence was 0.8 +/- 0.5 mm, whereas it was 2.3 +/- 1.2 mm in specimens without an eminence. These differences were statistically significant (P < 0.01). The osteological features we describe may be relevant to certain clinical problems. Traumatic dislocation of mandibular condyle, for example, might relate to a weakness of the glenoid fossa. Copyright 2006 Wiley-Liss, Inc.

Effect of Environment on the Fidelity of Control and Measurements of Solid-State Quantum Devices

DTIC Science & Technology

2013-07-22

space vs. thickness of the film a for a DQD charge qubit in one dimension with dot geometry d = 30 nm and l = 60 nm at 0 K...constitute a conducting half- space , rather than the more sparse gate geometry used in [134]. It is also instructive to compare our results with the ...40 ms [134]. However, it must be kept in mind that we have so far considered the simpler top gate geometry of a conducting half-

Influence of target thickness on the release of radioactive atoms

NASA Astrophysics Data System (ADS)

Guillot, Julien; Roussière, Brigitte; Tusseau-Nenez, Sandrine; Barré-Boscher, Nicole; Borg, Elie; Martin, Julien

2017-03-01

Nowadays, intense exotic beams are needed in order to study nuclei with very short half-life. To increase the release efficiency of the fission products, all the target characteristics involved must be improved (e.g. chemical composition, dimensions, physicochemical properties such as grain size, porosity, density…). In this article, we study the impact of the target thickness. Released fractions measured from graphite and uranium carbide pellets are presented as well as Monte-Carlo simulations of the Brownian motion.

Population-based evaluation of retinal nerve fiber layer, retinal ganglion cell layer, and inner plexiform layer as a diagnostic tool for glaucoma.

PubMed

Springelkamp, Henriët; Lee, Kyungmoo; Wolfs, Roger C W; Buitendijk, Gabriëlle H S; Ramdas, Wishal D; Hofman, Albert; Vingerling, Johannes R; Klaver, Caroline C W; Abràmoff, Michael D; Jansonius, Nomdo M

2014-11-20

We determined the glaucoma screening performance of regional optical coherence tomography (OCT) layer thickness measurements in the peripapillary and macular region, in a population-based setting. Subjects (n = 1224) in the Rotterdam Study underwent visual field testing (Humphrey Field Analyzer) and OCT of the macula and optic nerve head (Topcon 3-D OCT-1000). We determined the mean thicknesses of the retinal nerve fiber layer (RNFL), retinal ganglion cell layer (RGCL), and inner plexiform layer for regions-of-interest; thus, defining a series of OCT parameters, using the Iowa Reference Algorithms. Reference standard was the presence of glaucomatous visual field loss (GVFL); controls were subjects without GVFL, an intraocular pressure (IOP) of 21 mm Hg or less, and no positive family history for glaucoma. We calculated the area under the receiver operating characteristics curve (AUCs) and the sensitivity at 97.5% specificity for each parameter. After excluding 23 subjects with an IOP > 21 mm Hg and 73 subjects with a positive family history for glaucoma, there were 1087 controls and 41 glaucoma cases. Mean RGCL thickness in the inferior half of the macular region showed the highest AUC (0.85; 95% confidence interval [CI] 0.77-0.92) and sensitivity (53.7%; 95% CI, 38.7-68.0%). The mean thickness of the peripapillary RNFL had an AUC of 0.77 (95% CI, 0.69-0.85) and a sensitivity of 24.4% (95% CI, 13.7-39.5%). Macular RGCL loss is at least as common as peripapillary RNFL abnormalities in population-based glaucoma cases. Screening for glaucoma using OCT-derived regional thickness identifies approximately half of those cases of glaucoma as diagnosed by perimetry. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Photoreceptor Layer Thickness Changes During Dark Adaptation Observed With Ultrahigh-Resolution Optical Coherence Tomography.

PubMed

Lu, Chen D; Lee, ByungKun; Schottenhamml, Julia; Maier, Andreas; Pugh, Edward N; Fujimoto, James G

2017-09-01

To examine outer retinal band changes after flash stimulus and subsequent dark adaptation with ultrahigh-resolution optical coherence tomography (UHR-OCT). Five dark-adapted left eyes of five normal subjects were imaged with 3-μm axial-resolution UHR-OCT during 30 minutes of dark adaptation following 96%, 54%, 23%, and 0% full-field and 54% half-field rhodopsin bleach. We identified the ellipsoid zone inner segment/outer segment (EZ[IS/OS]), cone interdigitation zone (CIZ), rod interdigitation zone (RIZ), retinal pigment epithelium (RPE), and Bruch's membrane (BM) axial positions and generated two-dimensional thickness maps of the EZ(IS/OS) to the four bands. The average thickness over an area of the thickness map was compared against that of the dark-adapted baselines. The time-dependent thickness changes (photoresponses) were statistically compared against 0% bleach. Dark adaptometry was performed with the same bleaching protocol. The EZ(IS/OS)-CIZ photoresponse was significantly different at 96% (P < 0.0001) and 54% (P = 0.006) bleach. At all three bleaching levels, the EZ(IS/OS)-RIZ, -RPE, and -BM responses were significantly different (P < 0.0001). The EZ(IS/OS)-CIZ and EZ(IS/OS)-RIZ time courses were similar to the recovery of rod- and cone-mediated sensitivity, respectively, measured with dark adaptometry. The maximal EZ(IS/OS)-CIZ and EZ(IS/OS)-RIZ response magnitudes doubled from 54% to 96% bleach. Both EZ(IS/OS)-RPE and EZ(IS/OS)-BM responses resembled dampened oscillations that were graded in amplitude and duration with bleaching intensity. Half-field photoresponses were localized to the stimulated retina. With noninvasive, near-infrared UHR-OCT, we characterized three distinct, spatially localized photoresponses in the outer retinal bands. These photoresponses have potential value as physical correlates of photoreceptor function.

Additive-free thick graphene film as an anode material for flexible lithium-ion batteries

NASA Astrophysics Data System (ADS)

Rana, Kuldeep; Kim, Seong Dae; Ahn, Jong-Hyun

2015-04-01

This work demonstrates a simple route to develop mechanically flexible electrodes for Li-ion batteries (LIBs) that are usable as lightweight effective conducting networks for both cathodes and anodes. Removing electrochemically dead elements, such as binders, conducting agents and metallic current collectors, from the battery components will allow remarkable progress in this area. To investigate the feasibility of using thick, additive-free graphene films as anodes for flexible LIBs, we have synthesized and tested thick, additive-free, freestanding graphene films as anodes, first in a coin cell and further in a flexible full cell. As an anode material in a half cell, it showed a discharge capacity of about 350 mA h g-1 and maintained nearly this capacity over 50 cycles at various current rates. This film was also tested as an anode material in a full cell with a LiCoO2 cathode and showed good electrochemical performance. Because the graphene-based flexible film showed good performance in half- and full coin cells, we used this film as a flexible anode for flexible LIBs. No conducting agent or binder was used in the anode side, which helped in realizing the flexible LIBs. Using this, we demonstrate a thin, lightweight and flexible lithium ion battery with good electrochemical performance in both its flat and bent states.This work demonstrates a simple route to develop mechanically flexible electrodes for Li-ion batteries (LIBs) that are usable as lightweight effective conducting networks for both cathodes and anodes. Removing electrochemically dead elements, such as binders, conducting agents and metallic current collectors, from the battery components will allow remarkable progress in this area. To investigate the feasibility of using thick, additive-free graphene films as anodes for flexible LIBs, we have synthesized and tested thick, additive-free, freestanding graphene films as anodes, first in a coin cell and further in a flexible full cell. As an anode material in a half cell, it showed a discharge capacity of about 350 mA h g-1 and maintained nearly this capacity over 50 cycles at various current rates. This film was also tested as an anode material in a full cell with a LiCoO2 cathode and showed good electrochemical performance. Because the graphene-based flexible film showed good performance in half- and full coin cells, we used this film as a flexible anode for flexible LIBs. No conducting agent or binder was used in the anode side, which helped in realizing the flexible LIBs. Using this, we demonstrate a thin, lightweight and flexible lithium ion battery with good electrochemical performance in both its flat and bent states. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06082b

Thickness of the Magnetic Crust of Mars from Magneto-Spectral Analysis

NASA Technical Reports Server (NTRS)

Voorhies, Coerte V.

2006-01-01

Previous analysis of the magnetic spectrum of Mars showed only a crustal source field. The observational spectrum was fairly well fitted by the spectrum expected from random dipolar sources scattered on a spherical shell about 46 plus or minus 10 km below Mars' 3389.5 km mean radius. This de-correlation depth overestimates the typical depth of extended magnetized structures, and so was judged closer to mean source layer thickness than twice its value. To better estimate the thickness of the magnetic crust of Mars, six different magnetic spectra were fitted with the theoretical spectrum expected from a novel, bimodal distribution of magnetic sources. This theoretical spectrum represents both compact and extended, laterally correlated sources, so source shell depth is doubled to obtain layer thickness. The typical magnetic crustal thickness is put at 47.8 plus or minus 8.2 km. The extended sources are enormous, typically 650 km across, and account for over half the magnetic energy at low degrees. How did such vast regions form?

The use of short spreader grafts in rhinoplasty for patients with thick nasal skin.

PubMed

Grigoryants, Vladimir; Baroni, Arpa

2013-06-01

Thick nasal skin presents a challenge in rhinoplasty. Conventional spreader grafts in patients with thick nasal skin may result in an undesirable widening of the lower half of the nose where the nasal skin is thick. The use of short spreader grafts was evaluated in patients with thick nasal skin. For this study, 32 patients underwent closed rhinoplasty in which short spreader grafts were used. The spreader graft was 1 to 2 cm long and extended only to the transition of thin and thick nasal skin. The patients were followed for more than 1 year postoperatively. Aesthetic improvement was observed in all the patients. Nasal airway patency was improved or maintained in 94 % of the patients. Short spreader grafts effectively restore or maintain the internal nasal valve area after dorsal hump reduction while allowing for more aggressive narrowing of the lower part of the nose where nasal skin is thick. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Extraction efficiency and implications for absolute quantitation of propranolol in mouse brain, liver and kidney thin tissue sections using droplet-based liquid microjunction surface sampling-HPLC ESI-MS/MS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kertesz, Vilmos; Weiskittel, Taylor M.; Vavek, Marissa

Currently, absolute quantitation aspects of droplet-based surface sampling for thin tissue analysis using a fully automated autosampler/HPLC-ESI-MS/MS system are not fully evaluated. Knowledge of extraction efficiency and its reproducibility is required to judge the potential of the method for absolute quantitation of analytes from thin tissue sections. Methods: Adjacent thin tissue sections of propranolol dosed mouse brain (10- μm-thick), kidney (10- μm-thick) and liver (8-, 10-, 16- and 24- μm-thick) were obtained. Absolute concentration of propranolol was determined in tissue punches from serial sections using standard bulk tissue extraction protocols and subsequent HPLC separations and tandem mass spectrometric analysis. Thesemore » values were used to determine propranolol extraction efficiency from the tissues with the droplet-based surface sampling approach. Results: Extraction efficiency of propranolol using 10- μm-thick brain, kidney and liver thin tissues using droplet-based surface sampling varied between ~45-63%. Extraction efficiency decreased from ~65% to ~36% with liver thickness increasing from 8 μm to 24 μm. Randomly selecting half of the samples as standards, precision and accuracy of propranolol concentrations obtained for the other half of samples as quality control metrics were determined. Resulting precision ( ±15%) and accuracy ( ±3%) values, respectively, were within acceptable limits. In conclusion, comparative quantitation of adjacent mouse thin tissue sections of different organs and of various thicknesses by droplet-based surface sampling and by bulk extraction of tissue punches showed that extraction efficiency was incomplete using the former method, and that it depended on the organ and tissue thickness. However, once extraction efficiency was determined and applied, the droplet-based approach provided the required quantitation accuracy and precision for assay validations. Furthermore, this means that once the extraction efficiency was calibrated for a given tissue type and drug, the droplet-based approach provides a non-labor intensive and high-throughput means to acquire spatially resolved quantitative analysis of multiple samples of the same type.« less

Extraction efficiency and implications for absolute quantitation of propranolol in mouse brain, liver and kidney thin tissue sections using droplet-based liquid microjunction surface sampling-HPLC ESI-MS/MS

DOE PAGES

Kertesz, Vilmos; Weiskittel, Taylor M.; Vavek, Marissa; ...

2016-06-22

Currently, absolute quantitation aspects of droplet-based surface sampling for thin tissue analysis using a fully automated autosampler/HPLC-ESI-MS/MS system are not fully evaluated. Knowledge of extraction efficiency and its reproducibility is required to judge the potential of the method for absolute quantitation of analytes from thin tissue sections. Methods: Adjacent thin tissue sections of propranolol dosed mouse brain (10- μm-thick), kidney (10- μm-thick) and liver (8-, 10-, 16- and 24- μm-thick) were obtained. Absolute concentration of propranolol was determined in tissue punches from serial sections using standard bulk tissue extraction protocols and subsequent HPLC separations and tandem mass spectrometric analysis. Thesemore » values were used to determine propranolol extraction efficiency from the tissues with the droplet-based surface sampling approach. Results: Extraction efficiency of propranolol using 10- μm-thick brain, kidney and liver thin tissues using droplet-based surface sampling varied between ~45-63%. Extraction efficiency decreased from ~65% to ~36% with liver thickness increasing from 8 μm to 24 μm. Randomly selecting half of the samples as standards, precision and accuracy of propranolol concentrations obtained for the other half of samples as quality control metrics were determined. Resulting precision ( ±15%) and accuracy ( ±3%) values, respectively, were within acceptable limits. In conclusion, comparative quantitation of adjacent mouse thin tissue sections of different organs and of various thicknesses by droplet-based surface sampling and by bulk extraction of tissue punches showed that extraction efficiency was incomplete using the former method, and that it depended on the organ and tissue thickness. However, once extraction efficiency was determined and applied, the droplet-based approach provided the required quantitation accuracy and precision for assay validations. Furthermore, this means that once the extraction efficiency was calibrated for a given tissue type and drug, the droplet-based approach provides a non-labor intensive and high-throughput means to acquire spatially resolved quantitative analysis of multiple samples of the same type.« less

Evaluation of the strength of cement-treated aggregate for pavement bases.

DOT National Transportation Integrated Search

2006-01-01

Cement-treated aggregate (CTA) is commonly used to provide a stable base for pavements that are placed over weak soil subgrades. Because CTA reduces the thickness of the aggregate required to provide a durable base by approximately one-half, using it...

Dual Ion Species Plasma Expansion from Isotopically Layered Cryogenic Targets

NASA Astrophysics Data System (ADS)

Scott, G. G.; Carroll, D. C.; Astbury, S.; Clarke, R. J.; Hernandez-Gomez, C.; King, M.; Alejo, A.; Arteaga, I. Y.; Dance, R. J.; Higginson, A.; Hook, S.; Liao, G.; Liu, H.; Mirfayzi, S. R.; Rusby, D. R.; Selwood, M. P.; Spindloe, C.; Tolley, M. K.; Wagner, F.; Zemaityte, E.; Borghesi, M.; Kar, S.; Li, Y.; Roth, M.; McKenna, P.; Neely, D.

2018-05-01

A dual ion species plasma expansion scheme from a novel target structure is introduced, in which a nanometer-thick layer of pure deuterium exists as a buffer species at the target-vacuum interface of a hydrogen plasma. Modeling shows that by controlling the deuterium layer thickness, a composite H+/D+ ion beam can be produced by target normal sheath acceleration (TNSA), with an adjustable ratio of ion densities, as high energy proton acceleration is suppressed by the acceleration of a spectrally peaked deuteron beam. Particle in cell modeling shows that a (4.3 ±0.7 ) MeV per nucleon deuteron beam is accelerated, in a directional cone of half angle 9°. Experimentally, this was investigated using state of the art cryogenic targetry and a spectrally peaked deuteron beam of (3.4 ±0.7 ) MeV per nucleon was measured in a cone of half angle 7°-9°, while maintaining a significant TNSA proton component.

Spin-flop coupling and exchange anisotropy in ferromagnetic/antiferromagnetic bilayers

NASA Astrophysics Data System (ADS)

Xu, Xiao-Yong; Hu, Jing-Guo

2009-03-01

By investigating the antiferromagnetic spin configuration, the exchange anisotropy and the interfacial spin-flop coupling in ferromagnetic/antiferromagnetic (FM/AF) bilayers have been discussed in detail. The results show that there are four possible cases for the AF spins, namely the reversible recovering case, irreversible half-rotating case, irreversible reversing and irreversible half-reversing cases. Moreover, the realization of the cases strongly depends on interface quadratic coupling, interface spin-flop (biquadratic) coupling and AF thickness. The magnetic phase diagram in terms of the AF thickness tAF, the interfacial bilinear coupling J1 and the spin-flop coupling J2 has been constructed. The corresponding critical parameters in which the exchange bias will occur or approach saturation have been also presented. Specially, the small spin-flop exchange coupling may result in an exchange bias without the interfacial bilinear exchange coupling. However, in general, the spin-flop exchange coupling can weaken or eliminate the exchange bias, but always enhances the coercivity greatly.

Multiple secondary islands formation in nonlinear evolution of double tearing mode simulations

NASA Astrophysics Data System (ADS)

Guo, W.; Ma, J.; Yu, Z.

2017-03-01

A new numerical code solving the conservative perturbed resistive magnetohydrodynamic (MHD) model is developed. Numerical tests of the ideal Kelvin-Helmholtz instability and the resistive double tearing mode (DTM) show its capability in solving linear and nonlinear MHD instabilities. The nonlinear DTM evolution in 2D geometry is numerically investigated with low guiding field B z 0 , short half-distance y 0 between the equilibrium current sheets, and small resistivity η. The interaction of islands on the two initial current sheets may generate an unstable flow driven current sheet with a high length-to-thickness aspect ratio (α), and multiple secondary islands can form. In general, the length-to-thickness aspect ratio α and the number of secondary islands increase with decreasing guide field B z 0 , decreasing half-distance y 0 , and increasing Lundquist number of the flow driven current sheet S L although the dependence may be non-monotonic. The reconnection rate dependence on S L , B z 0 , and y 0 is also investigated.

A MODEL FOR THE TEAR FILM AND OCULAR SURFACE TEMPERATURE FOR PARTIAL BLINKS

PubMed Central

Deng, Quan; Braun, R. J.; Driscoll, T. A.; King-Smith, P. E.

2015-01-01

In this paper, we investigate the dynamics of tear film and the associated temperature variation for partial blinks. We investigate the mechanism of fluid supply during partial blink cycles, and compare the film thickness with observation in vivo. We find that varying the thickness of the fluid layer beneath the moving upper lid improves the agreement for the in vivo measurement of tear film thickness after a half blink. By examining the flux of the fluid, we provide an explanation of this assumption. We also investigate the temperature dynamics both at the ocular surface and inside the simulated anterior chamber. Our simulation results suggest that the ocular surface temperature readjusts rapidly to normal temperature distribution after partial blinks. PMID:25635242

Spontaneous formation and dynamics of half-skyrmions in a chiral liquid-crystal film

NASA Astrophysics Data System (ADS)

Nych, Andriy; Fukuda, Jun-Ichi; Ognysta, Uliana; Žumer, Slobodan; Muševič, Igor

2017-12-01

Skyrmions are coreless vortex-like excitations emerging in diverse condensed-matter systems, and real-time observation of their dynamics is still challenging. Here we report the first direct optical observation of the spontaneous formation of half-skyrmions. In a thin film of a chiral liquid crystal, depending on experimental conditions including film thickness, they form a hexagonal lattice whose lattice constant is a few hundred nanometres, or appear as isolated entities with topological defects compensating their charge. These half-skyrmions exhibit intriguing dynamical behaviour driven by thermal fluctuations. Numerical calculations of real-space images successfully corroborate the experimental observations despite the challenge because of the characteristic scale of the structures close to the optical resolution limit. A thin film of a chiral liquid crystal thus offers an intriguing platform that facilitates a direct investigation of the dynamics of topological excitations such as half-skyrmions and their manipulation with optical techniques.

Equivalent strike-slip earthquake cycles in half-space and lithosphere-asthenosphere earth models

USGS Publications Warehouse

Savage, J.C.

1990-01-01

By virtue of the images used in the dislocation solution, the deformation at the free surface produced throughout the earthquake cycle by slippage on a long strike-slip fault in an Earth model consisting of an elastic plate (lithosphere) overlying a viscoelastic half-space (asthenosphere) can be duplicated by prescribed slip on a vertical fault embedded in an elastic half-space. Inversion of 1973-1988 geodetic measurements of deformation across the segment of the San Andreas fault in the Transverse Ranges north of Los Angeles for the half-space equivalent slip distribution suggests no significant slip on the fault above 30 km and a uniform slip rate of 36 mm/yr below 30 km. One equivalent lithosphere-asthenosphere model would have a 30-km thick lithosphere and an asthenosphere relaxation time greater than 33 years, but other models are possible. -from Author

Free and Forced Vibrations of Thick-Walled Anisotropic Cylindrical Shells

NASA Astrophysics Data System (ADS)

Marchuk, A. V.; Gnedash, S. V.; Levkovskii, S. A.

2017-03-01

Two approaches to studying the free and forced axisymmetric vibrations of cylindrical shell are proposed. They are based on the three-dimensional theory of elasticity and division of the original cylindrical shell with concentric cross-sectional circles into several coaxial cylindrical shells. One approach uses linear polynomials to approximate functions defined in plan and across the thickness. The other approach also uses linear polynomials to approximate functions defined in plan, but their variation with thickness is described by the analytical solution of a system of differential equations. Both approaches have approximation and arithmetic errors. When determining the natural frequencies by the semi-analytical finite-element method in combination with the divide and conqure method, it is convenient to find the initial frequencies by the finite-element method. The behavior of the shell during free and forced vibrations is analyzed in the case where the loading area is half the shell thickness

Modeling thermal performance of exterior walls retrofitted from insulation and modified laterite based bricks materials

NASA Astrophysics Data System (ADS)

Wati, Elvis; Meukam, Pierre; Damfeu, Jean Claude

2017-12-01

Uninsulated concrete block walls commonly found in tropical region have to be retrofitted to save energy. The thickness of insulation layer used can be reduced with the help of modified laterite based bricks layer (with the considerably lower thermal conductivity than that of concrete block layer) during the retrofit building fabrics. The aim of this study is to determine the optimum location and distribution of different materials. The investigation is carried out under steady periodic conditions under the climatic conditions of Garoua in Cameroon using a Simulink model constructed from H-Tools (the library of Simulink models). Results showed that for the continuous air-conditioned space, the best wall configuration from the maximum time lag, minimum decrement factor and peak cooling transmission load perspective, is dividing the insulation layer into two layers and placing one at the exterior surface and the other layer between the two different massive layers with the modified laterite based bricks layer at the interior surface. For intermittent cooling space, the best wall configuration from the minimum energy consumption depends on total insulation thickness. For the total insulation thickness less than 8 cm approximately, the best wall configuration is placing the half layer of insulation material at the interior surface and the other half between the two different massive layers with the modified earthen material at the exterior surface. Results also showed that, the optimum insulation thickness calculated from the yearly cooling transmission (estimated only during the occupied period) and some economic considerations slightly depends on the location of that insulation.

46 CFR 64.5 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., excluding the allowance for corrosion and the thickness for loadings other than pressure, as provided for in the ASME Code. (e) Test pressure means a hydrostatic pressure of at least one and one-half times the maximum allowable working pressure. (f) Dynamic loading conditions means the following: (1) A loading in...

46 CFR 64.5 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., excluding the allowance for corrosion and the thickness for loadings other than pressure, as provided for in the ASME Code. (e) Test pressure means a hydrostatic pressure of at least one and one-half times the maximum allowable working pressure. (f) Dynamic loading conditions means the following: (1) A loading in...

46 CFR 64.5 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., excluding the allowance for corrosion and the thickness for loadings other than pressure, as provided for in the ASME Code. (e) Test pressure means a hydrostatic pressure of at least one and one-half times the maximum allowable working pressure. (f) Dynamic loading conditions means the following: (1) A loading in...

46 CFR 64.5 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., excluding the allowance for corrosion and the thickness for loadings other than pressure, as provided for in the ASME Code. (e) Test pressure means a hydrostatic pressure of at least one and one-half times the maximum allowable working pressure. (f) Dynamic loading conditions means the following: (1) A loading in...

46 CFR 151.15-10 - Cargo gauging devices.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., sonic depth gauge (without penetration of tank shell), pipe flow meter. (e) All gauging devices and... shall be designed for the pressure and temperature of the cargo in accordance with the requirements of... the operating temperatures, of not less than one-half inch in thickness and adequately protected by a...

46 CFR 151.15-10 - Cargo gauging devices.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., sonic depth gauge (without penetration of tank shell), pipe flow meter. (e) All gauging devices and... shall be designed for the pressure and temperature of the cargo in accordance with the requirements of... the operating temperatures, of not less than one-half inch in thickness and adequately protected by a...

46 CFR 151.15-10 - Cargo gauging devices.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., sonic depth gauge (without penetration of tank shell), pipe flow meter. (e) All gauging devices and... shall be designed for the pressure and temperature of the cargo in accordance with the requirements of... the operating temperatures, of not less than one-half inch in thickness and adequately protected by a...

46 CFR 151.15-10 - Cargo gauging devices.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., sonic depth gauge (without penetration of tank shell), pipe flow meter. (e) All gauging devices and... shall be designed for the pressure and temperature of the cargo in accordance with the requirements of... the operating temperatures, of not less than one-half inch in thickness and adequately protected by a...

Effect of Target Thickness on Cratering and Penetration of Projectiles Impacting at Velocities to 13,000 Feet Per Second

NASA Technical Reports Server (NTRS)

Kinard, William H.; Lambert, C. H., Jr.; Schryer, David R.; Casey, Francis W., Jr.

1958-01-01

In order to determine the effects of target thickness on the penetration and cratering of a target resulting from impacts by high-velocity projectiles, a series of experimental tests have been run. The projectile-target material combinations investigated were aluminum projectiles impacting aluminum targets and steel projectiles impacting aluminum and copper targets. The velocity spectrum ranged from 4,000 ft/sec to 13,000 ft/sec. It has been found that the penetration is a function of target thickness provided that the penetration is greater than 20 percent of the target thickness. Targets of a thickness such that the penetration amounts to less than 20 percent of the thickness may be regarded as quasi-infinite. An empirical formula has been established relating the penetration to the target thickness and to the penetration of a projectile of the same mass, configuration, and velocity into a quasi- infinite target. In particular, it has been found that a projectile can completely penetrate a target whose thickness is approximately one and one-half times as great as the penetration of a similar projectile into a quasi-infinite target. The diameter of a crater has also been found to be a function of the target thickness provided that the target thickness is not greater than the projectile length in the case of cylindrical projectiles and not greater than two to three times the projectile diameter in the case of spherical projectiles.

Structural and magnetic properties of ultra-thin Fe films on metal-organic chemical vapour deposited GaN(0001)

NASA Astrophysics Data System (ADS)

Kim, Jun-Young; Ionescu, Adrian; Mansell, Rhodri; Farrer, Ian; Oehler, Fabrice; Kinane, Christy J.; Cooper, Joshaniel F. K.; Steinke, Nina-Juliane; Langridge, Sean; Stankiewicz, Romuald; Humphreys, Colin J.; Cowburn, Russell P.; Holmes, Stuart N.; Barnes, Crispin H. W.

2017-01-01

Structural and magnetic properties of 1-10 nm thick Fe films deposited on GaN(0001) were investigated. In-situ reflecting high energy electron diffraction images indicated a α-Fe(110)/GaN(0001) growth of the 3D Volmer-Weber type. The α-Fe(110) X-ray diffraction peak showed a 1° full-width at half-maximum, indicating ≈20 nm grain sizes. A significant reduction in Fe atomic moment from its bulk value was observed for films thinner than 4 nm. Both GaN/Fe interface roughness and Fe film coercivity increased with Fe thickness, indicating a possible deterioration of Fe crystalline quality. Magnetic anisotropy was mainly uniaxial for all films while hexagonal anisotropies appeared for thicknesses higher than 3.7 nm.

Downwash in Vortex Region Behind Rectangular Half-wing at Mach Number 1.91

NASA Technical Reports Server (NTRS)

Cummings, John L; Haefeli, Rudolph C

1950-01-01

Results of an experimental investigation to determine downwash and wake characteristics in region of trailing vortex system behind a rectangular half-wing at Mach number 1.91 are presented. The wing had a 5-percent thick symmetric diamond cross section beveled to a knife edge at the tip. At small angles of attack, downwash angles were in close agreement with predictions of linearized theory based on the assumption of an undistorted vortex sheet. At higher angles of attack, the flow was greatly influenced by the rolling up of the vortex sheet.

Analysis of a Generally Oriented Crack in a Functionally Graded Strip Sandwiched Between Two Homogeneous Half Planes

NASA Technical Reports Server (NTRS)

Shbeeb, N.; Binienda, W. K.; Kreider, K.

1999-01-01

The driving forces for a generally oriented crack embedded in a Functionally Graded strip sandwiched between two half planes are analyzed using singular integral equations with Cauchy kernels, and integrated using Lobatto-Chebyshev collocation. Mixed-mode Stress Intensity Factors (SIF) and Strain Energy Release Rates (SERR) are calculated. The Stress Intensity Factors are compared for accuracy with previously published results. Parametric studies are conducted for various nonhomogeneity ratios, crack lengths. crack orientation and thickness of the strip. It is shown that the SERR is more complete and should be used for crack propagation analysis.

Penny-shaped interface crack between an elastic layer and a half space.

NASA Technical Reports Server (NTRS)

Erdogan, F.; Arin, K.

1972-01-01

The axially symmetric elastostatic problem for a layer bonded to a half space with different material properties is considered. It is assumed that the bi-material interface contains a penny-shaped crack the surfaces of which are subjected to known tractions. The solution of the problem is reduced to that of a system of singular integral equations of the second kind. A numerical example for an aluminum-epoxy material combination is given. The stress intensity factors and the strain energy release rate are calculated and are given as functions of layer thickness-to-crack radius ratio.

Failure Analysis of a Service Tube

NASA Astrophysics Data System (ADS)

Xie, Zhongdong; Cai, Weiguo; Li, Zhenxing; Guan, YiMing; Zhang, Baocheng; Yang, XiaoTong

2017-12-01

One tube was cracked used in the primary reformer furnace in a fertilizer plant for two and half years. In order to find out the causes of cracking, the methods for chemical composition analysis, macro- and microstructure analysis, penetrant testing, weld analysis, crack and surface damage analysis, mechanics property analysis, high temperature endurance performance analysis, stress and wall thickness calculation were adopted. The integrated assessment results showed that the carbon content of the tube was in the lower limit of the standard range; the tube effective wall thickness was too small; local overheating leads to tube cracking in use process.

Compression response of thick layer composite laminates with through-the-thickness reinforcement

NASA Technical Reports Server (NTRS)

Farley, Gary L.; Smith, Barry T.; Maiden, Janice

1992-01-01

Compression and compression-after-impact (CAI) tests were conducted on seven different AS4-3501-6 (0/90) 0.64-cm thick composite laminates. Four of the seven laminates had through-the-thickness (TTT) reinforcement fibers. Two TTT reinforcement methods, stitching and integral weaving, and two reinforcement fibers, Kevlar and carbon, were used. The remaining three laminates were made without TTT reinforcements and were tested to establish a baseline for comparison with the laminates having TTT reinforcement. Six of the seven laminates consisted of nine thick layers whereas the seventh material was composed of 46 thin plies. The use of thick-layer material has the potential for reducing structural part cost because of the reduced part count (layers of material). The compression strengths of the TTT reinforced laminates were approximately one half those of the materials without TTT reinforcements. However, the CAI strengths of the TTT reinforced materials were approximately twice those of materials without TTT reinforcements. The improvement in CAI strength is due to an increase in interlaminar strength produced by the TTT reinforcement. Stitched laminates had slightly higher compression and CAI strengths than the integrally woven laminates.

Structured light generation by magnetic metamaterial half-wave plates at visible wavelength

NASA Astrophysics Data System (ADS)

Zeng, Jinwei; Luk, Ting S.; Gao, Jie; Yang, Xiaodong

2017-12-01

Metamaterial or metasurface unit cells functioning as half-wave plates play an essential role for realizing ideal Pancharatnam-Berry phase optical elements capable of tailoring light phase and polarization as desired. Complex light beam manipulation through these metamaterials or metasurfaces unveils new dimensions of light-matter interactions for many advances in diffraction engineering, beam shaping, structuring light, and holography. However, the realization of metamaterial or metasurface half-wave plates in visible spectrum range is still challenging mainly due to its specific requirements of strong phase anisotropy with amplitude isotropy in subwavelength scale. Here, we propose magnetic metamaterial structures which can simultaneously exploit the electric field and magnetic field of light for achieving the nanoscale half-wave plates at visible wavelength. We design and demonstrate the magnetic metamaterial half-wave plates in linear grating patterns with high polarization conversion purity in a deep subwavelength thickness. Then, we characterize the equivalent magnetic metamaterial half-wave plates in cylindrical coordinate as concentric-ring grating patterns, which act like an azimuthal half-wave plate and accordingly exhibit spatially inhomogeneous polarization and phase manipulations including spin-to-orbital angular momentum conversion and vector beam generation. Our results show potentials for realizing on-chip beam converters, compact holograms, and many other metamaterial devices for structured light beam generation, polarization control, and wavefront manipulation.

The Accuracy of Al and Cu Film Thickness Determinations and the Implications for Electron Probe Microanalysis.

PubMed

Matthews, Mike B; Kearns, Stuart L; Buse, Ben

2018-04-01

The accuracy to which Cu and Al coatings can be determined, and the effect this has on the quantification of the substrate, is investigated. Cu and Al coatings of nominally 5, 10, 15, and 20 nm were sputter coated onto polished Bi using two configurations of coater: One with the film thickness monitor (FTM) sensor colocated with the samples, and one where the sensor is located to one side. The FTM thicknesses are compared against those calculated from measured Cu Lα and Al Kα k-ratios using PENEPMA, GMRFilm, and DTSA-II. Selected samples were also cross-sectioned using focused ion beam. Both systems produced repeatable coatings, the thickest coating being approximately four times the thinnest coating. The side-located FTM sensor indicated thicknesses less than half those of the software modeled results, propagating on to 70% errors in substrate quantification at 5 kV. The colocated FTM sensor produced errors in film thickness and substrate quantification of 10-20%. Over the range of film thicknesses and accelerating voltages modeled both the substrate and coating k-ratios can be approximated by linear trends as functions of film thickness. The Al films were found to have a reduced density of ~2 g/cm2.

Dynamic histomorphometric evaluation of human fetal bone formation.

PubMed

Glorieux, F H; Salle, B L; Travers, R; Audra, P H

1991-01-01

We have evaluated dynamic and static parameters of bone formation in femoral metaphyses collected from two human fetuses at 19 weeks of gestation. Tetracycline was administered to the mother at set intervals (2-5-2 day schedule) before interruption of pregnancy. Labels were distinct and sharply linear, suggesting a well organized calcification front at this early stage of mineralization. Mineral apposition rate (MAR) was fastest (4.1 +/- 0.3 microns/d) in the periosteal (Ps) envelope, and about half that value in the endosteal envelopes (endocortical: 2.5 +/- 0.1, cancellous 2.1 +/- 0.1 microns/d). Because cellular activities may vary throughout the metaphyseal area, sections were arbitrarily separated in 0.75 mm layers starting from the growth plate. Three measured parameters decreased rapidly with increasing distance from the physis: Ps MAR: 4.9 to 2.3 microns/d, trabecular osteoid thickness: 5.9 to 1.2 microns, and cartilage volume (CgV/TV): 5.4% to 1.2%. Others did not vary significantly along the metaphysis. Comparison of several static parameters with those measured in five autopsy specimens from full-term infants showed that bone and cartilage volume, and trabecular thickness increased while osteoid thickness and parameters of resorption decreased in the second half of the gestation period. The study indicates that fetal bone matrix mineralization is already highly organized at mid-gestation, and validates the use of histomorphometry to assess bone maturation during early skeletal development.

Additive-free thick graphene film as an anode material for flexible lithium-ion batteries.

PubMed

Rana, Kuldeep; Kim, Seong Dae; Ahn, Jong-Hyun

2015-04-28

This work demonstrates a simple route to develop mechanically flexible electrodes for Li-ion batteries (LIBs) that are usable as lightweight effective conducting networks for both cathodes and anodes. Removing electrochemically dead elements, such as binders, conducting agents and metallic current collectors, from the battery components will allow remarkable progress in this area. To investigate the feasibility of using thick, additive-free graphene films as anodes for flexible LIBs, we have synthesized and tested thick, additive-free, freestanding graphene films as anodes, first in a coin cell and further in a flexible full cell. As an anode material in a half cell, it showed a discharge capacity of about 350 mA h g(-1) and maintained nearly this capacity over 50 cycles at various current rates. This film was also tested as an anode material in a full cell with a LiCoO2 cathode and showed good electrochemical performance. Because the graphene-based flexible film showed good performance in half- and full coin cells, we used this film as a flexible anode for flexible LIBs. No conducting agent or binder was used in the anode side, which helped in realizing the flexible LIBs. Using this, we demonstrate a thin, lightweight and flexible lithium ion battery with good electrochemical performance in both its flat and bent states.

Beam response analysis of moving vehicle with half car modeling

NASA Astrophysics Data System (ADS)

Badriyah, A. N.; Arifianto, D.; Susatio, Y.

2016-11-01

There were several tragedies concerning damages of bridge which seem to be sooner than the predicted period. One of hypothesis in this situation is an addition of vibration caused by long vehicle such as super long truck which has huge force transferred into the bridge and its long body causes more vibration due to phase difference of front and rear tire. The selected method which is used in this problem is using a simulation for modeling a bridge- vehicle system using half car vehicle model. The simulation is done using ANSYS Workbench 15.0 with some variation such us the thickness of beam and its supports. There are 3 kind of variation used in the thickness variety which are 2 m, 1 m, and 0.5 m. While in supports variation, we have fixed support, knife-edge support, and slider support. The results show that there is addition of vibration caused by long vehicle. It is proved by an oscillation which is showed in every response of beam's total deformation. Highest total deformation is achieved in slider support beam of 0.5 thicknesses, 1.08 mm in 1.12 second. First ripple seen in responses is at 0.84 second. Meanwhile, response of knife-edge and fixed support beam show a similarity. The ripple in this situation is caused by beat modulation from the front and rear tire.

Photoreceptor Layer Thickness Changes During Dark Adaptation Observed With Ultrahigh-Resolution Optical Coherence Tomography

PubMed Central

Lu, Chen D.; Lee, ByungKun; Schottenhamml, Julia; Maier, Andreas; Pugh, Edward N.; Fujimoto, James G.

2017-01-01

Purpose To examine outer retinal band changes after flash stimulus and subsequent dark adaptation with ultrahigh-resolution optical coherence tomography (UHR-OCT). Methods Five dark-adapted left eyes of five normal subjects were imaged with 3-μm axial-resolution UHR-OCT during 30 minutes of dark adaptation following 96%, 54%, 23%, and 0% full-field and 54% half-field rhodopsin bleach. We identified the ellipsoid zone inner segment/outer segment (EZ[IS/OS]), cone interdigitation zone (CIZ), rod interdigitation zone (RIZ), retinal pigment epithelium (RPE), and Bruch's membrane (BM) axial positions and generated two-dimensional thickness maps of the EZ(IS/OS) to the four bands. The average thickness over an area of the thickness map was compared against that of the dark-adapted baselines. The time-dependent thickness changes (photoresponses) were statistically compared against 0% bleach. Dark adaptometry was performed with the same bleaching protocol. Results The EZ(IS/OS)-CIZ photoresponse was significantly different at 96% (P < 0.0001) and 54% (P = 0.006) bleach. At all three bleaching levels, the EZ(IS/OS)-RIZ, -RPE, and -BM responses were significantly different (P < 0.0001). The EZ(IS/OS)-CIZ and EZ(IS/OS)-RIZ time courses were similar to the recovery of rod- and cone-mediated sensitivity, respectively, measured with dark adaptometry. The maximal EZ(IS/OS)-CIZ and EZ(IS/OS)-RIZ response magnitudes doubled from 54% to 96% bleach. Both EZ(IS/OS)-RPE and EZ(IS/OS)-BM responses resembled dampened oscillations that were graded in amplitude and duration with bleaching intensity. Half-field photoresponses were localized to the stimulated retina. Conclusions With noninvasive, near-infrared UHR-OCT, we characterized three distinct, spatially localized photoresponses in the outer retinal bands. These photoresponses have potential value as physical correlates of photoreceptor function. PMID:28898357

Two-stage rifting in the Kenya rift: implications for half-graben models

NASA Astrophysics Data System (ADS)

Mugisha, F.; Ebinger, C. J.; Strecker, M.; Pope, D.

1997-09-01

The Kerio sub-basin in the northern Kenya rift is a transitional area between the southern Kenya rift, where crustal thickness is 30 km, and the northern Kenya rift, where crustal thickness is 20 km. The lack of data on the shallow crustal structure, geometry of rift-bounding faults, and rift evolution makes it difficult to determine if the crustal thickness variations are due to pre-rift structure, or along-axis variations in crustal stretching. We reprocessed reflection seismic data acquired for the National Oil Corporation of Kenya, and integrated results with field and gravity observations to (1) delineate the sub-surface geometry of the Kerio sub-basin, (2) correlate seismic stratigraphic sequences with dated strata exposed along the basin margins, and (3) use new and existing results to propose a two-stage rifting model for the central Kenya rift. Although a classic half-graben form previously had been inferred from the attitude of uppermost strata, new seismic data show a more complex form in the deeper basin: a narrow full-graben bounded by steep faults. We suggest that the complex basin form and the northwards increase in crustal thinning are caused by the superposition of two or more rifting events. The first rifting stage may have occurred during Palaeogene time contemporaneous with sedimentation and rifting in northwestern Kenya and southern Sudan. The distribution of seismic sequences suggests that a phase of regional thermal subsidence occurred prior to renewed faulting and subsidence at about 12 Ma after the eruption of flood phonolites throughout the central Kenya rift. A new border fault developed during the second rifting stage, effectively widening the basin. Gravity and seismic data indicate sedimentary and volcanic strata filling the basin are 6 km thick, with up to 4 km deposited during the first rifting stage.

Beam hardening and partial beam hardening of the bowtie filter: Effects on dosimetric applications in CT

NASA Astrophysics Data System (ADS)

Lopez-Rendon, X.; Zhang, G.; Bosmans, H.; Oyen, R.; Zanca, F.

2014-03-01

Purpose: To estimate the consequences on dosimetric applications when a CT bowtie filter is modeled by means of full beam hardening versus partial beam hardening. Method: A model of source and filtration for a CT scanner as developed by Turner et. al. [1] was implemented. Specific exposures were measured with the stationary CT X-ray tube in order to assess the equivalent thickness of Al of the bowtie filter as a function of the fan angle. Using these thicknesses, the primary beam attenuation factors were calculated from the energy dependent photon mass attenuation coefficients and used to include beam hardening in the spectrum. This was compared to a potentially less computationally intensive approach, which accounts only partially for beam hardening, by giving the photon spectrum a global (energy independent) fan angle specific weighting factor. Percentage differences between the two methods were quantified by calculating the dose in air after passing several water equivalent thicknesses representative for patients having different BMI. Specifically, the maximum water equivalent thickness of the lateral and anterior-posterior dimension and of the corresponding (half) effective diameter were assessed. Results: The largest percentage differences were found for the thickest part of the bowtie filter and they increased with patient size. For a normal size patient they ranged from 5.5% at half effective diameter to 16.1% for the lateral dimension; for the most obese patient they ranged from 7.7% to 19.3%, respectively. For a complete simulation of one rotation of the x-ray tube, the proposed method was 12% faster than the complete simulation of the bowtie filter. Conclusion: The need for simulating the beam hardening of the bow tie filter in Monte Carlo platforms for CT dosimetry will depend on the required accuracy.

Synthesis of half-sphere/half-funnel-shaped silica structures by reagent localization and the role of water in shape control

DOE PAGES

Datskos, Panos; Polizos, Georgios; Cullen, David A.; ...

2016-11-11

Role of water and ammonium hydroxide is investigated in evolution of shape of silica structures in the polyvinylpyrrolidone-pentanol emulsion droplet system. Shape control of silica structures is demonstrated by localization of the reagents. A uniform dispersion of reagents provided straight silica rods, while localization of the reagents at the emulsion droplet periphery provided a new type of structures half sphere-half funnel. The absence of water in the initial stages prompted a different nucleation process for the structure growth compared to when water was present in the intial stages. Effect of effective water concentration appeared to be related to the easemore » of diffusion of silica percursor inside the emulsion droplet,i.e., the higher the water concentration, the lower the silica precursor diffusion. Additionally, mixing the reagents in different combinations before adding to the reaction mixture also affected the silica structure thickness, length, and shape.« less

Synthesis of half-sphere/half-funnel-shaped silica structures by reagent localization and the role of water in shape control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Datskos, Panos; Polizos, Georgios; Cullen, David A.

Role of water and ammonium hydroxide is investigated in evolution of shape of silica structures in the polyvinylpyrrolidone-pentanol emulsion droplet system. Shape control of silica structures is demonstrated by localization of the reagents. A uniform dispersion of reagents provided straight silica rods, while localization of the reagents at the emulsion droplet periphery provided a new type of structures half sphere-half funnel. The absence of water in the initial stages prompted a different nucleation process for the structure growth compared to when water was present in the intial stages. Effect of effective water concentration appeared to be related to the easemore » of diffusion of silica percursor inside the emulsion droplet,i.e., the higher the water concentration, the lower the silica precursor diffusion. Additionally, mixing the reagents in different combinations before adding to the reaction mixture also affected the silica structure thickness, length, and shape.« less

Microstructure of room temperature ionic liquids at stepped graphite electrodes

DOE PAGES

Feng, Guang; Li, Song; Zhao, Wei; ...

2015-07-14

Molecular dynamics simulations of room temperature ionic liquid (RTIL) [emim][TFSI] at stepped graphite electrodes were performed to investigate the influence of the thickness of the electrode surface step on the microstructure of interfacial RTILs. A strong correlation was observed between the interfacial RTIL structure and the step thickness in electrode surface as well as the ion size. Specifically, when the step thickness is commensurate with ion size, the interfacial layering of cation/anion is more evident; whereas, the layering tends to be less defined when the step thickness is close to the half of ion size. Furthermore, two-dimensional microstructure of ionmore » layers exhibits different patterns and alignments of counter-ion/co-ion lattice at neutral and charged electrodes. As the cation/anion layering could impose considerable effects on ion diffusion, the detailed information of interfacial RTILs at stepped graphite presented here would help to understand the molecular mechanism of RTIL-electrode interfaces in supercapacitors.« less

Modeling guided wave propagation in curved thick composites with ply drops and marcelling

NASA Astrophysics Data System (ADS)

Hakoda, Christopher; Choi, Gloria; Lissenden, Clifford

2018-04-01

Setting the process parameters for fabrication of thick composites having complex geometries is a challenging endeavor, with the best result being a high-quality part and less desirable results being parts that contain voids or fiber marcelling. An equal challenge is the nondestructive testing of these parts. Consider a U-shaped portion of a more complex part. The straight segments of the U-shape are approximately 10-mm thick, but a series of ply-drops reduce the thickness by one half at the center portion. Ultrasonic guided waves that have the potential to nondestructively test this part can be actuated by coupling transducers to the straight segments if and only if wave modes that are sensitive to the defects of interest can propagate through the ply drops, the curve, and the attenuation due to internal damping. A frequency domain finite element approach proposed in recent years for guided wave analysis is applied to this inhomogeneous waveguide problem in order to select modes and frequencies that are sensitive to marcelling.

Sensitivity of Heterointerfaces on Emission Wavelength in Quantum Cascade Lasers

DTIC Science & Technology

2016-08-18

sharp satellite peaks and highly resolved thickness interference fringes. The full-width at 4 half-maximum of the n=0 peak is nominally similar... Watanabe , M. Sugiyama, and Y. Nakano, "Effect of hetero-interfaces on in situ wafer curvature behavior in InGaAs/GaAsP strain-balanced MQWs

Sensitivity of Heterointerfaces on Emission Wavelength in Quantum Cascade Lasers

DTIC Science & Technology

2016-10-31

as expected, and all scans exhibit sharp satellite peaks and highly resolved thickness interference fringes. The full- width at half-maximum of the n...K. Watanabe , M. Sugiyama, and Y. Nakano, "Effect of hetero-interfaces on in situ wafer curvature behavior in InGaAs/GaAsP strain-balanced MQWs

Extended depth measurement for a Stokes sample imaging polarimeter

NASA Astrophysics Data System (ADS)

Dixon, Alexander W.; Taberner, Andrew J.; Nash, Martyn P.; Nielsen, Poul M. F.

2018-02-01

A non-destructive imaging technique is required for quantifying the anisotropic and heterogeneous structural arrangement of collagen in soft tissue membranes, such as bovine pericardium, which are used in the construction of bioprosthetic heart valves. Previously, our group developed a Stokes imaging polarimeter that measures the linear birefringence of samples in a transmission arrangement. With this device, linear retardance and optic axis orientation; can be estimated over a sample using simple vector algebra on Stokes vectors in the Poincaré sphere. However, this method is limited to a single path retardation of a half-wave, limiting the thickness of samples that can be imaged. The polarimeter has been extended to allow illumination of narrow bandwidth light of controllable wavelength through achromatic lenses and polarization optics. We can now take advantage of the wavelength dependence of relative retardation to remove ambiguities that arise when samples have a single path retardation of a half-wave to full-wave. This effectively doubles the imaging depth of this method. The method has been validated using films of cellulose of varied thickness, and applied to samples of bovine pericardium.

Seyfert galaxy ultraviolet emission-line intensities and variability - A self-consistent photoionization analysis applied to broad-line-emitting gas in NGC 3783

NASA Technical Reports Server (NTRS)

Koratkar, Anuradha P.; Macalpine, Gordon M.

1992-01-01

Well-constrained photoionization models for the Seyfert I galaxy NGC 3783 are developed. Both cross-correlation analyses and line variability trends with varying ionizing radiation flux require a multicomponent picture. All the data for He II 1640 A, C IV 1549 A, and semiforbidden C III 1909 A can be reasonably well reproduced by two cloud components. One has a source-cloud distance of 24 lt-days, gas density around 3 x 10 exp 10/cu cm, ionization parameter range of 0.04-0.2, and cloud thickness such that about half of the carbon is doubly ionized and about half is triply ionized. The other component is located approximately 96 lt-days from the source, is shielded from the source by the inner cloud, has a density about 3 x 10 to the 9th/cu cm, and is characterized by an ionization parameter range of 0.001-0.03, The cloud thickness is such that about 45 percent carbon is doubly ionized and about 55 percent is singly ionized.

Non-polar a-plane ZnO films grown on r-Al2O3 substrates using GaN buffer layers

NASA Astrophysics Data System (ADS)

Xu, C. X.; Chen, W.; Pan, X. H.; Chen, S. S.; Ye, Z. Z.; Huang, J. Y.

2016-09-01

In this work, GaN buffer layer has been used to grow non-polar a-plane ZnO films by laser-assisted and plasma-assisted molecular beam epitaxy. The thickness of GaN buffer layer ranges from ∼3 to 12 nm. The GaN buffer thickness effect on the properties of a-plane ZnO thin films is carefully investigated. The results show that the surface morphology, crystal quality and optical properties of a-plane ZnO films are strongly correlated with the thickness of GaN buffer layer. It was found that with 6 nm GaN buffer layer, a-plane ZnO films display the best crystal quality with X-ray diffraction rocking curve full-width at half-maximum of only 161 arcsec for the (101) reflection.

Monte Carlo simulations of nematic and chiral nematic shells

NASA Astrophysics Data System (ADS)

Wand, Charlie R.; Bates, Martin A.

2015-01-01

We present a systematic Monte Carlo simulation study of thin nematic and cholesteric shells with planar anchoring using an off-lattice model. The results obtained using the simple model correspond with previously published results for lattice-based systems, with the number, type, and position of defects observed dependent on the shell thickness with four half-strength defects in a tetrahedral arrangement found in very thin shells and a pair of defects in a bipolar (boojum) configuration observed in thicker shells. A third intermediate defect configuration is occasionally observed for intermediate thickness shells, which is stabilized in noncentrosymmetric shells of nonuniform thickness. Chiral nematic (cholesteric) shells are investigated by including a chiral term in the potential. Decreasing the pitch of the chiral nematic leads to a twisted bipolar (chiral boojum) configuration with the director twist increasing from the inner to the outer surface.

Fiber-coupled dielectric-loaded plasmonic waveguides.

PubMed

Gosciniak, Jacek; Volkov, Valentyn S; Bozhevolnyi, Sergey I; Markey, Laurent; Massenot, Sébastien; Dereux, Alain

2010-03-01

Fiber in- and out-coupling of radiation guided by dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs) is realized using intermediate tapered dielectric waveguides. The waveguide structures fabricated by large-scale UV-lithography consist of 1-microm-thick polymer ridges tapered from 10-microm-wide ridges deposited directly on a magnesium fluoride substrate to 1-microm-wide ridges placed on a 50-nm-thick and 100-microm-wide gold stripe. Using fiber-to-fiber transmission measurements at telecom wavelengths, the performance of straight and bent DLSPPWs is characterized demonstrating the overall insertion loss below 24 dB, half of which is attributed to the DLSPPW loss of propagation over the 100-microm-long distance.

Stress measurement in thick plates using nonlinear ultrasonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abbasi, Zeynab, E-mail: zabbas5@uic.edu, E-mail: dozevin@uic.edu; Ozevin, Didem, E-mail: zabbas5@uic.edu, E-mail: dozevin@uic.edu

2015-03-31

In this paper the interaction between nonlinear ultrasonic characteristics and stress state of complex loaded thick steel plates using fundamental theory of nonlinear ultrasonics is investigated in order to measure the stress state at a given cross section. The measurement concept is based on phased array placement of ultrasonic transmitter-receiver to scan three angles of a given cross section using Rayleigh waves. The change in the ultrasonic data in thick steel plates is influenced by normal and shear stresses; therefore, three measurements are needed to solve the equations simultaneously. Different thickness plates are studied in order to understand the interactionmore » of Rayleigh wave penetration depth and shear stress. The purpose is that as the thickness becomes smaller, the shear stress becomes negligible at the angled measurement. For thicker cross section, shear stress becomes influential if the depth of penetration of Rayleigh wave is greater than the half of the thickness. The influences of plate thickness and ultrasonic frequency on the identification of stress tensor are numerically studied in 3D structural geometry and Murnaghan material model. The experimental component of this study includes uniaxial loading of the plate while measuring ultrasonic wave at three directions (perpendicular, parallel and angled to the loading direction). Instead of rotating transmitter-receiver pair for each test, a device capable of measuring the three angles is designed.« less

Studies of x-ray localization and thickness dependence in atomic-scale elemental mapping by STEM energy-dispersive x-ray spectroscopy using single-frame scanning method

DOE PAGES

Lu, Ping; Moya, Jaime M.; Yuan, Renliang; ...

2018-03-01

The delocalization of x-ray signals limits the spatial resolution in atomic-scale elemental mapping by scanning transmission electron microscopy (STEM) using energy-dispersive x-ray spectroscopy (EDS). In this study, using a SrTiO 3 [001] single crystal, we show that the x-ray localization to atomic columns is strongly dependent on crystal thickness, and a thin crystal is critical for improving the spatial resolution in atomic-scale EDS mapping. A single-frame scanning technique is used in this study instead of the multiple-frame technique to avoid peak broadening due to tracking error. The strong thickness dependence is realized by measuring the full width at half maximamore » (FWHM) as well as the peak-to-valley (P/V) ratio of the EDS profiles for Ti K and Sr K+L, obtained at several crystal thicknesses. A FWHM of about 0.16 nm and a P/V ratio of greater than 7.0 are obtained for Ti K for a crystal thickness of less than 20 nm. In conclusion, with increasing crystal thickness, the FWHM and P/V ratio increases and decreases, respectively, indicating the advantage of using a thin crystal for high-resolution EDS mapping.« less

AFM Investigation of Liquid-Filled Polymer Microcapsules Elasticity.

PubMed

Sarrazin, Baptiste; Tsapis, Nicolas; Mousnier, Ludivine; Taulier, Nicolas; Urbach, Wladimir; Guenoun, Patrick

2016-05-10

Elasticity of polymer microcapsules (MCs) filled with a liquid fluorinated core is studied by atomic force microscopy (AFM). Accurately characterized spherical tips are employed to obtain the Young's moduli of MCs having four different shell thicknesses. We show that those moduli are effective ones because the samples are composites. The strong decrease of the effective MC elasticity (from 3.0 to 0.1 GPa) as the shell thickness decreases (from 200 to 10 nm) is analyzed using a novel numerical approach. This model describes the evolution of the elasticity of a coated half-space according to the contact radius, the thickness of the film, and the elastic moduli of bulk materials. This numerical model is consistent with the experimental data and allows simulating the elastic behavior of MCs at high frequencies (5 MHz). While the quasi-static elasticity of the MCs is found to be very dependent on the shell thickness, the high frequency (5 MHz) elastic behavior of the core leads to a stable behavior of the MCs (from 2.5 to 3 GPa according to the shell thickness). Finally, the effect of thermal annealing on the MCs elasticity is investigated. The Young's modulus is found to decrease because of the reduction of the shell thickness due to the loss of the polymer.

Studies of x-ray localization and thickness dependence in atomic-scale elemental mapping by STEM energy-dispersive x-ray spectroscopy using single-frame scanning method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Ping; Moya, Jaime M.; Yuan, Renliang

The delocalization of x-ray signals limits the spatial resolution in atomic-scale elemental mapping by scanning transmission electron microscopy (STEM) using energy-dispersive x-ray spectroscopy (EDS). In this study, using a SrTiO 3 [001] single crystal, we show that the x-ray localization to atomic columns is strongly dependent on crystal thickness, and a thin crystal is critical for improving the spatial resolution in atomic-scale EDS mapping. A single-frame scanning technique is used in this study instead of the multiple-frame technique to avoid peak broadening due to tracking error. The strong thickness dependence is realized by measuring the full width at half maximamore » (FWHM) as well as the peak-to-valley (P/V) ratio of the EDS profiles for Ti K and Sr K+L, obtained at several crystal thicknesses. A FWHM of about 0.16 nm and a P/V ratio of greater than 7.0 are obtained for Ti K for a crystal thickness of less than 20 nm. In conclusion, with increasing crystal thickness, the FWHM and P/V ratio increases and decreases, respectively, indicating the advantage of using a thin crystal for high-resolution EDS mapping.« less

Studies of x-ray localization and thickness dependence in atomic-scale elemental mapping by STEM energy-dispersive x-ray spectroscopy using single-frame scanning method.

PubMed

Lu, Ping; Moya, Jaime M; Yuan, Renliang; Zuo, Jian Min

2018-03-01

The delocalization of x-ray signals limits the spatial resolution in atomic-scale elemental mapping by scanning transmission electron microscopy (STEM) using energy-dispersive x-ray spectroscopy (EDS). In this study, using a SrTiO 3 [001] single crystal, we show that the x-ray localization to atomic columns is strongly dependent on crystal thickness, and a thin crystal is critical for improving the spatial resolution in atomic-scale EDS mapping. A single-frame scanning technique is used in this study instead of the multiple-frame technique to avoid peak broadening due to tracking error. The strong thickness dependence is realized by measuring the full width at half maxima (FWHM) as well as the peak-to-valley (P/V) ratio of the EDS profiles for Ti K and Sr K + L, obtained at several crystal thicknesses. A FWHM of about 0.16 nm and a P/V ratio of greater than 7.0 are obtained for Ti K for a crystal thickness of less than 20 nm. With increasing crystal thickness, the FWHM and P/V ratio increases and decreases, respectively, indicating the advantage of using a thin crystal for high-resolution EDS mapping. Published by Elsevier B.V.

Cyclotron production for the radiometal Zirconium-89 with an IBA cyclone 18/9 and COSTIS solid target system (STS)

NASA Astrophysics Data System (ADS)

Dabkowski, A. M.; Probst, K.; Marshall, C.

2012-12-01

The development of biological targeting agents such as proteins, peptides, antibodies and nanoparticles with a range of biological half-lives demands the production of new radionuclides with half-lives (physical) complementary to these biological properties. Zirconium-89 (89Zr) is a promising radionuclide for development of new immuno-PET agents due to its convenient half-life of 78.4 h, β+ emission rate of 23%, low maximum energy of 0.9 MeV resulting in good spatial resolution, stable daughter isotope of Yttrium-89 (89Y) and favorable imaging characteristics, with only one significant γ-line of 909 keV emitted during decay alongside the 511 keV positron photons. Our aim was to prove that isotopically pure 89Zr could be produced in an IBA Cyclone 18/9 cyclotron equipped with a COSTIS STS using the 89Y(p,n)89Zr reaction and optimise the yield by reducing the beam degrader thickness without producing either 88Zr or 88Y. The degradation of the beam energy with 400 and 500 μm thick Niobium foils were achieved without overheating problems with 2-3 hours long irradiation times. From repeated measurements of activity, it was clear that there is a bi-exponential decay of radioactivity due to the short lived 89mZr and 89Zr. The measured half-life of the longer lived radionulide was consistent with value for 89Zr. The energy spectrum from 89Zr had energy peaks at 511 keV and 909 keV and was consistent with 89Zr. Production of 89Zr with 500 μm thick Niobium beam degrader (Ep = 9.8MeV) was achieved, without producing either 88Zr or 88Y. It was necessary to wait at least 4 hours before measuring the activity and decay correct in order to calculate the 89gZr activity at the end of cyclotron production. Degrading the proton beam to 10 MeV produces radionuclidically pure 89Zr with yields from 8 to 9 MBq/μAh. Whilst this is enough for pre-clinical use, the yield is not enough for either clinical use or commercial supply. Using thinner beam degraders to increase the proton beam energy increases the radionuclidic yield but it is not yet possible to exclude the presence of radionuclidic impurities.

Dominance of layer-specific microvessel dilation in contrast-enhanced high-resolution fMRI: Comparison between hemodynamic spread and vascular architecture with CLARITY.

PubMed

Poplawsky, Alexander John; Fukuda, Mitsuhiro; Kang, Bok-Man; Kim, Jae Hwan; Suh, Minah; Kim, Seong-Gi

2017-08-16

Contrast-enhanced cerebral blood volume-weighted (CBVw) fMRI response peaks are specific to the layer of evoked synaptic activity (Poplawsky et al., 2015), but the spatial resolution limit of CBVw fMRI is unknown. In this study, we measured the laminar spread of the CBVw fMRI evoked response in the external plexiform layer (EPL, 265 ± 65 μm anatomical thickness, mean ± SD, n = 30 locations from 5 rats) of the rat olfactory bulb during electrical stimulation of the lateral olfactory tract and examined its potential vascular source. First, we obtained the evoked CBVw fMRI responses with a 55 × 55 μm 2 in-plane resolution and a 500-μm thickness at 9.4 T, and found that the fMRI signal peaked predominantly in the inner half of EPL (136 ± 54 μm anatomical thickness). The mean full-width at half-maximum of these fMRI peaks was 347 ± 102 μm and the functional spread was approximately 100 or 200 μm when the effects of the laminar thicknesses of EPL or inner EPL were removed, respectively. Second, we visualized the vascular architecture of EPL from a different rat using a Clear Lipid-exchanged Anatomically Rigid Imaging/immunostaining-compatible Tissue hYdrogel (CLARITY)-based tissue preparation method and confocal microscopy. Microvascular segments with an outer diameter of <11 μm accounted for 64.3% of the total vascular volume within EPL and had a mean segment length of 55 ± 40 μm (n = 472). Additionally, vessels that crossed the EPL border had a mean segment length outside of EPL equal to 73 ± 61 μm (n = 28), which is comparable to half of the functional spread (50-100 μm). Therefore, we conclude that dilation of these microvessels, including capillaries, likely dominate the CBVw fMRI response and that the biological limit of the fMRI spatial resolution is approximately the average length of 1-2 microvessel segments, which may be sufficient for examining sublaminar circuits. Copyright © 2017 Elsevier Inc. All rights reserved.

There Could Be a Dinosaur in Your Life!

ERIC Educational Resources Information Center

Jacob, Beth; Dempsey, Bill

This booklet describes how to make large two-dimensional models of dinosaur skeletons which can be effective teaching tools. Small laminated wood dinosaur models are enlarged, traced, and transferred to tri-wall cardboard (one-half inch thick) and cut out with a saber saw. Parts are then slotted and numbered for easy assembly. The result is a kit…

16 CFR 304.5 - Marking requirements for imitation political items.

Code of Federal Regulations, 2011 CFR

2011-01-01

...-serif numerals. Each numeral shall have a vertical dimension of not less than two millimeters (2.0 mm) and a minimum depth of three-tenths of one millimeter (0.3 mm) or one-half (1/2) the thickness of the... the calendar year shall be six millimeters (6.0 mm). (4) An imitation political button, poster...

Initial and steady-state Ru growth by atomic layer deposition studied by in situ Angle Resolved X-ray Photoelectron Spectroscopy

NASA Astrophysics Data System (ADS)

Egorov, Konstantin V.; Lebedinskii, Yury Yu.; Soloviev, Anatoly A.; Chouprik, Anastasia A.; Azarov, Alexander Yu.; Markeev, Andrey M.

2017-10-01

The clear substrate-dependent growth and delayed film continuity are essential challenges of Ru atomic layer deposition (ALD) demanding adequate and versatile approaches for their study. Here, we report on the application of in situ Angle Resolved X-ray Phototelectron Spectroscopy (ARXPS) for investigation of initial and steady-state ALD growth of Ru using Ru(EtCp)2 and O2 as precursors. Using ARXPS surface analysis technique we determine such parameters of Ru ALD initial growth as incubation period, fractional coverage and the thickness of islands/film depending on the substrate chemical state, governed by the presence/absence of NH3/Ar plasma pretreatment. It was demonstrated that NH3/Ar plasma pretreatment allows to obtain the lowest incubation period (∼7 ALD cycles) resulting in a continuous ultrathin (∼20 Å) and smooth Ru films after 70 ALD cycles. In situ XPS at UHV was used at steady state Ru growth for analysis of half-cycle reactions that revealed formation of RuOx (x ≈ 2) layer with thickness of ∼8 Å after O2 pulse (first half-cycle). It was also shown that oxygen of RuOx layer combusts Ru(EtCp)2 ligands in the second half-cycle reaction and the observed Ru growth of ∼0.34 Å per cycle is in a good agreement with the amount of oxygen in the RuOx layer.

Equatorial Precession Drove Mid-Latitude Changes in ENSO-Scale Variation in the Earliest Miocene

NASA Astrophysics Data System (ADS)

Fox, B.; D'Andrea, W. J.; Lee, D. E.; Wilson, G. S.

2014-12-01

Foulden Maar is an annually laminated lacustrine diatomite deposit from the South Island of New Zealand. The deposit was laid down over ~100 kyr of the latest Oligocene and earliest Miocene, during the peak and deglaciation phase of the Mi-1 Antarctic glaciation event. At this time, New Zealand was located at approximately the same latitude as today (~45°S). Evidence from organic geochemical proxies (δD, δ13C) and physical properties (density, colour) indicates the presence of an 11-kyr cycle at the site. Although it is known that 11-kyr insolation (half-precession) cycles occur between the Tropics, this cycle is rarely seen in sedimentary archives deposited outside the immediate vicinity of the Equator. Records from Foulden Maar correlate well with the amplitude and phase of the modelled equatorial half-precession cycle for the earliest Miocene. High-resolution (50 µm) colour intensity measurements and lamina thickness measurements both indicate the presence of significant ENSO-like (2-8 year) variation in the Foulden Maar sediments. Early results from targeted lamina thickness measurements suggest that ENSO-band variation is modulated by the 11-kyr cycle, with power in the ENSO band increasing during periods of increased insolation at the Equator. This implies that equatorial half-precession had a significant effect on ENSO-like variation in the early Miocene, and that this effect was felt as far afield as the mid-latitudes of the Southern Hemisphere.

Rheology of the lithosphere inferred from postseismic uplift following the 1959 Hebgen Lake earthquake

USGS Publications Warehouse

Nishimura, T.; Thatcher, W.

2003-01-01

We have modeled the broad postseismic uplift measured by geodetic leveling in the epicentral area of the 1959 Mw = 7.3 Hebgen Lake, Montana earthquake, a normal faulting event in the northern Basin and Range province. To fit the observed uplift we calculate synthetic postseismic deformation using the relaxation response of a gravitational viscoelastic Earth to the earthquake. For a model with an elastic plate overlying a viscoelastic half-space, we find that the elastic thickness is 38 ?? 8 km, which isclose to the local crustal thickness. The half-space viscosity is estimated at 4 ?? 1018??0.5 Pa s. The leveling data do not require a viscous lower crust but permit a lower bound viscosity of 1020 Pa s. The observed broad uplift cannot be explained by physically plausible afterslip on and below the coseismic fault. However, local deformation across the coseismic surface rupture requires shallow afterslip reaching the surface. The postseismic deformation induced by the estimated viscoelastic structure decays exponentially with a time constant of ???15 years. Because of coupling between the elastic layer and the viscoelastic substrate, this relaxation time is significantly longer than the 2 year Maxwell relaxation time of the viscous half-space itself. Our result suggests the importance of postseismic relaxation in interpreting high-precision global positioning system velocities. For example, our model results suggest that postseismic transient velocities from both the 1959 Hebgen Lake and the 1983 Mw = 6.9 Borah Peak earthquakes are currently as large as 1-2 mm/yr.

Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: An Expanding Shell Model of Monomer Distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richter, Andrew; Dergunov, Sergey; Ganus, Bill

2011-01-01

Hydrophobic monomers partially phase separate from saturated lipids when loaded into lipid bilayers in amounts exceeding a 1:1 monomer/lipid molar ratio. This conclusion is based on the agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in an increase in bilayer thickness and a slight increase in the diameter of liposomes. A homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to an increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small-angle neutron scatteringmore » (SANS) and small-angle X-ray scattering (SAXS), was approximately half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was intermediate between values predicted for a homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at a 1.2 monomer/lipid ratio approximately half of the monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for the directed covalent assembly of organic nanomaterials. In particular, the partial phase separation of monomers from lipids corroborates the successful creation of nanothin polymer materials with uniform imprinted nanopores. Pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.« less

Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: An Expanding Shell Model of Monomer Distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richter, Andrew G.; Dergunov, Sergey A.; Ganus, Bill

2011-03-10

Hydrophobic monomers partially phase separate from saturated lipids when loaded into lipid bilayers in amounts exceeding a 1:1 monomer/lipid molar ratio. This conclusion is based on the agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in an increase in bilayer thickness and a slight increase in the diameter of liposomes. A homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to an increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small-angle neutron scatteringmore » (SANS) and small-angle X-ray scattering (SAXS), was approximately half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was intermediate between values predicted for a homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at a 1.2 monomer/lipid ratio approximately half of the monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for the directed covalent assembly of organic nanomaterials. In particular, the partial phase separation of monomers from lipids corroborates the successful creation of nanothin polymer materials with uniform imprinted nanopores. Finally, pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.« less

Direct Observation of the BCC (100) Plane in Thin Films of Sphere-forming Diblock Copolymers

NASA Astrophysics Data System (ADS)

Ji, Shengxiang; Nagpal, Umang; Liao, Wen; de Pablo, Juan; Nealey, Paul

2010-03-01

In sphere-forming diblock copolymers, periodic arrays of spheres are arranged in a body-centred cubic (BCC) lattice structure in bulk. However, in thin films different surface morphologies were observed as a function of the film thickness, and the transition from the hexagonal array to the BCC (110) arrangement of spheres on film surfaces was located with respect to the increase of the film thickness. Here we report the first direct observation of the BCC (100) plane in thin films of poly (styrene-b-methyl methacrylate) diblock copolymers on homogeneous substrates. By balancing the surface energies of both blocks, the lower energy BCC (100) plane corresponding to a square arrangement of half spheres, formed on film surfaces when the film thickness was commensurate with the spacing, L100, between (100) planes or greater than 2 L100. A hexagonal arrangement of spheres was only observed when the thickness was less than 2 L100 and incommensurate with 1 L100. Monte Carlo (MC) simulation confirmed our experimental observation and was used to investigate the transition of the arrangement of spheres as a function of the film thickness.

Impact of compressed breast thickness and dose on lesion detectability in digital mammography: FROC study with simulated lesions in real mammograms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salvagnini, Elena, E-mail: elena.salvagnini@gmail.

Purpose: The aim of this work was twofold: (1) to examine whether, with standard automatic exposure control (AEC) settings that maintain pixel values in the detector constant, lesion detectability in clinical images decreases as a function of breast thickness and (2) to verify whether a new AEC setup can increase lesion detectability at larger breast thicknesses. Methods: Screening patient images, acquired on two identical digital mammography systems, were collected over a period of 2 yr. Mammograms were acquired under standard AEC conditions (part 1) and subsequently with a new AEC setup (part 2), programmed to use the standard AEC settingsmore » for compressed breast thicknesses ≤49 mm, while a relative dose increase was applied above this thickness. The images were divided into four thickness groups: T1 ≤ 29 mm, T2 = 30–49 mm, T3 = 50–69 mm, and T4 ≥ 70 mm, with each thickness group containing 130 randomly selected craniocaudal lesion-free images. Two measures of density were obtained for every image: a BI-RADS score and a map of volumetric breast density created with a software application (VolparaDensity, Matakina, NZ). This information was used to select subsets of four images, containing one image from each thickness group, matched to a (global) BI-RADS score and containing a region with the same (local) VOLPARA volumetric density value. One selected lesion (a microcalcification cluster or a mass) was simulated into each of the four images. This process was repeated so that, for a given thickness group, half the images contained a single lesion and half were lesion-free. The lesion templates created and inserted in groups T3 and T4 for the first part of the study were then inserted into the images of thickness groups T3 and T4 acquired with higher dose settings. Finally, all images were visualized using the ViewDEX software and scored by four radiologists performing a free search study. A statistical jackknife-alternative free-response receiver operating characteristic analysis was applied. Results: For part 1, the alternative free-response receiver operating characteristic curves for the four readers were 0.80, 0.65, 0.55 and 0.56 in going from T1 to T4, indicating a decrease in detectability with increasing breast thickness. P-values and the 95% confidence interval showed no significant difference for the T3-T4 comparison (p = 0.78) while all the other differences were significant (p < 0.05). Separate analysis of microcalcification clusters presented the same results while for mass detection, the only significant difference came when comparing T1 to the other thickness groups. Comparing the scores of part 1 and part 2, results for the T3 group acquired with the new AEC setup and T3 group at standard AEC doses were significantly different (p = 0.0004), indicating improved detection. For this group a subanalysis for microcalcification detection gave the same results while no significant difference was found for mass detection. Conclusions: These data using clinical images confirm results found in simple QA tests for many mammography systems that detectability falls as breast thickness increases. Results obtained with the AEC setup for constant detectability above 49 mm showed an increase in lesion detection with compressed breast thickness, bringing detectability of lesions to the same level.« less

AXIALLY ORIENTED SECTIONS OF NUMMULITIDS: A TOOL TO INTERPRET LARGER BENTHIC FORAMINIFERAL DEPOSITS

PubMed Central

Hohenegger, Johann; Briguglio, Antonino

2015-01-01

The “critical shear velocity” and “settling velocity” of foraminiferal shells are important parameters for determining hydrodynamic conditions during deposition of Nummulites banks. These can be estimated by determining the size, shape, and density of nummulitid shells examined in axial sections cut perpendicular to the bedding plane. Shell size and shape can be determined directly from the shell diameter and thickness, but density must be calculated indirectly from the thin section. Calculations using the half-tori method approximate shell densities by equalizing the chamber volume of each half whorl, based on the half whorl’s lumen area and its center of gravity. Results from this method yield the same lumen volumes produced empirically by micro-computed tomography. The derived hydrodynamic parameters help estimate the minimum flow velocities needed to entrain nummulitid tests and provide a potential tool to account for the nature of their accumulations. PMID:26166914

AXIALLY ORIENTED SECTIONS OF NUMMULITIDS: A TOOL TO INTERPRET LARGER BENTHIC FORAMINIFERAL DEPOSITS.

PubMed

Hohenegger, Johann; Briguglio, Antonino

2012-04-01

The "critical shear velocity" and "settling velocity" of foraminiferal shells are important parameters for determining hydrodynamic conditions during deposition of Nummulites banks. These can be estimated by determining the size, shape, and density of nummulitid shells examined in axial sections cut perpendicular to the bedding plane. Shell size and shape can be determined directly from the shell diameter and thickness, but density must be calculated indirectly from the thin section. Calculations using the half-tori method approximate shell densities by equalizing the chamber volume of each half whorl, based on the half whorl's lumen area and its center of gravity. Results from this method yield the same lumen volumes produced empirically by micro-computed tomography. The derived hydrodynamic parameters help estimate the minimum flow velocities needed to entrain nummulitid tests and provide a potential tool to account for the nature of their accumulations.

Tuning electronic and magnetic properties of GaN nanosheets by surface modifications and nanosheet thickness.

PubMed

Xiao, Meixia; Yao, Tingzhen; Ao, Zhimin; Wei, Peng; Wang, Danghui; Song, Haiyang

2015-04-14

Density-functional theory calculations are performed to investigate the effects of surface modifications and nanosheet thickness on the electronic and magnetic properties of gallium nitride (GaN) nanosheets (NSs). Unlike the bare GaN NSs terminating with polar surfaces, the systems with hydrogenated Ga (H-GaN), fluorinated Ga (F-GaN), and chlorinated Ga (Cl-GaN) preserve their initial wurtzite structures and exhibit ferromagnetic states. The abovementioned three different decorations on Ga atoms are energetically more favorable for thicker GaN NSs. Moreover, as the thickness increases, H-GaN and F-GaN NSs undergo semiconductor to metal and half-metal to metal transition, respectively, while Cl-GaN NSs remain completely metallic. The predicted diverse and tunable electronic and magnetic properties highlight the potential of GaN NSs for novel electronic and spintronic nanodevices.

Trends in (LaMnO3)n/(SrTiO3)m superlattices with varying layer thicknesses

PubMed Central

Jilili, J.; Cossu, F.; Schwingenschlögl, U.

2015-01-01

We investigate the thickness dependence of the structural, electronic, and magnetic properties of (LaMnO3)n/(SrTiO3)m (n, m = 2, 4, 6, 8) superlattices using density functional theory. The electronic structure turns out to be highly sensitive to the onsite Coulomb interaction. In contrast to bulk SrTiO3, strongly distorted O octahedra are observed in the SrTiO3 layers with a systematic off centering of the Ti atoms. The systems favour ferromagnetic spin ordering rather than the antiferromagnetic spin ordering of bulk LaMnO3 and all show half-metallicity, while a systematic reduction of the minority spin band gaps as a function of the LaMnO3 and SrTiO3 layer thicknesses originates from modifications of the Ti dxy states. PMID:26323361

Ellipsometry of single-layer antireflection coatings on transparent substrates

NASA Astrophysics Data System (ADS)

Azzam, R. M. A.

2017-11-01

The complex reflection coefficients of p- and s-polarized light and ellipsometric parameters of a transparent substrate of refractive index n2, which is coated by a transparent thin film whose refractive index n1 =√{n2 } satisfies the anti-reflection condition at normal incidence, are considered as functions of film thickness d and angle of incidence ϕ. A unique coated surface, with n1 =√{n2 } and film thickness d equal to half of the film-thickness period Dϕ at angle ϕ and wavelength λ, reflects light of the same wavelength without change of polarization for all incident polarization states. (The reflection Jones matrix of such coated surface is the 2 × 2 identity matrix pre-multiplied by a scalar, hence tanΨ = 1,Δ = 0.) To monitor the deposition of an antireflection coating, the normalized Stokes parameters of obliquely reflected light (e.g. at ϕ =70∘) are measured until predetermined target values of those parameters are detected. This provides a more accurate means of film thickness control than is possible using a micro-balance technique or an intensity reflectance method.

Structural and optical properties of ZnO nanorods on Mg0.2Zn0.8O seed layers grown by hydrothermal method.

PubMed

Kim, Min Su; Kim, Do Yeob; Kim, Sung-O; Leem, Jae-Young

2013-05-01

ZnO nanorods were grown on the Mg0.2Zn0.8O seed layers with different thickness by hydrothermal method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) were carried out to investigate the effects of the Mg0.2Zn0.8O seed layer thickness on the structural and the optical properties of the ZnO nanorods. The residual stress in the Mg0.2Zn0.8O seed layers was depended on the thickness while the texture coefficient of the Mg0.2Zn0.8O seed layers was not affected significantly. The smaller full width at half maximum (FWHM) of the ZnO (002) diffraction and near-band-edge emission (NBE) peak and the larger average grain size were observed from the ZnO nanorods grown on the Mg0.2Zn0.8O seed layers with 5 layers (thickness of 350 nm), which indicate the enhancement the structural and the optical properties of the ZnO nanorods.

A half millimeter thick coplanar flexible battery with wireless recharging capability.

PubMed

Kim, Joo-Seong; Ko, Dongah; Yoo, Dong-Joo; Jung, Dae Soo; Yavuz, Cafer T; Kim, Nam-In; Choi, In-Suk; Song, Jae Yong; Choi, Jang Wook

2015-04-08

Most of the existing flexible lithium ion batteries (LIBs) adopt the conventional cofacial cell configuration where anode, separator, and cathode are sequentially stacked and so have difficulty in the integration with emerging thin LIB applications, such as smart cards and medical patches. In order to overcome this shortcoming, herein, we report a coplanar cell structure in which anodes and cathodes are interdigitatedly positioned on the same plane. The coplanar electrode design brings advantages of enhanced bending tolerance and capability of increasing the cell voltage by in series-connection of multiple single-cells in addition to its suitability for the thickness reduction. On the basis of these structural benefits, we develop a coplanar flexible LIB that delivers 7.4 V with an entire cell thickness below 0.5 mm while preserving stable electrochemical performance throughout 5000 (un)bending cycles (bending radius = 5 mm). Also, even the pouch case serves as barriers between anodes and cathodes to prevent Li dendrite growth and short-circuit formation while saving the thickness. Furthermore, for convenient practical use wireless charging via inductive electromagnetic energy transfer and solar cell integration is demonstrated.

[Alveolar bone thickness in A point area : how to avoid periodontal failures in front of upper incisors].

PubMed

Chevalier, Émilie; Philip-Alliez, Camille; Le Gall, Michel

2016-03-01

Studies on orthodontic-periodontics relationships are numerous but few have benefited from the contribution of new 3D imaging techniques that emphasize iatrogenic effects that orthodontics may have on the periodontium. Periodontal risk in terms of fenestration, bone dehiscences next maxillary incisors are real during or after orthodontic treatment. The accurate assessment of the initial situation in terms of bone quantity in this dental arch anterior segment is thus very important. Our study aimed to evaluate the reliability of conventional lateral cephalograms to quantify alveolar bone thickness in relation to the maxillary incisors by comparing it with data from CT scans. The second objective was to identify an at risk patient profile by assessing possible correlations between this thickness and dysmorphia components. The results revealed a half of assessment error in the estimation of bone thickness and increased risk in case of hyperdivergence typology, Class III skeletal relationships and dento-alveolar protrusion. Finally, in view of these data, we discussed the clinical procedures to avoid such periodontal failures in this anterior segment of the dental arch. © EDP Sciences, SFODF, 2016.

Characteristics of nuclepore filters with large pore size—I. Physical properties

NASA Astrophysics Data System (ADS)

John, W.; Hering, S.; Reischl, G.; Sasaki, G.; Goren, S.

Measurements of pore diameter, pore density and filter thickness have been made on Nuclepore filters of 5, 8 and 12 μm pore size. The areal distribution of the pores is random, as verified by total hole counts and by counts of overlapping holes. Filter thicknesses decrease with increasing pore diameter. The Hagen-Poiseuille formula accounts for less than half of the measured pressure drop across 12 μm pore size filters. A new calculation, including a term for the pressure drop external to the filter, accounts quantitatively for the observations. There are sufficient variations among filter batches to require knowledge of the filter parameters for each batch to ensure accurate measurements using these filters.

Making High-Pass Filters For Submillimeter Waves

NASA Technical Reports Server (NTRS)

Siegel, Peter H.; Lichtenberger, John A.

1991-01-01

Micromachining-and-electroforming process makes rigid metal meshes with cells ranging in size from 0.002 in. to 0.05 in. square. Series of steps involving cutting, grinding, vapor deposition, and electroforming creates self-supporting, electrically thick mesh. Width of holes typically 1.2 times cutoff wavelength of dominant waveguide mode in hole. To obtain sharp frequency-cutoff characteristic, thickness of mesh made greater than one-half of guide wavelength of mode in hole. Meshes used as high-pass filters (dichroic plates) for submillimeter electromagnetic waves. Process not limited to square silicon wafers. Round wafers also used, with slightly more complication in grinding periphery. Grid in any pattern produced in electroforming mandrel. Any platable metal or alloy used for mesh.

Effect of boattail geometry on the acoustics of parallel baffles in ducts

NASA Technical Reports Server (NTRS)

Soderman, P. T.; Unnever, G.; Dudley, M. R.

1984-01-01

Sound attenuation and total pressure drop of parallel duct baffles incorporating certain boattail geometries were measured in the NASA Ames Research Center 7- by 10-Foot Wind Tunnel. The baseline baffles were 1.56 m long and 20 cm thick, on 45-cm center-to-center spacings, and spanned the test section from floor to ceiling. Four different boattails were evaluated: a short, smooth (nonacoustic) boattail; a longer, smooth boattail; and two boattails with perforated surfaces and sound-absorbent filler. Acoustic measurements showed the acoustic boattails improved the sound attenuation of the baffles at approximately half the rate to be expected from constant-thickness sections of the same length; that is, 1.5 dB/n, where n is the ratio of acoustic treatment length to duct passage width between baffles. The aerodynamic total pressure loss was somewhat sensitive to tail geometry. Lengthening the tails to reduce the diffusion half-angle from 11 to 5 degrees reduced the total pressure loss approximately 9%. Perforating the boattails, which increased the surface roughness, did not have a large effect on the total pressure loss. Aerodynamic results are compared with a published empirical method for predicting baffle total pressure drop.

Anatomy of the nasal profile

PubMed Central

Anderson, K J; Henneberg, M; Norris, R M

2008-01-01

There is a lack in the understanding of the variation within the thickness of the soft tissue structures (muscle, skin and fat) overlying the cartilaginous skeleton of the nose and their relationship to the dorsum shape. We examined such relationships by dissecting noses of six adult female and six adult male cadavers, comparing the internal anatomical structures to the external nasal profile. We found that the soft tissue structures differ in thickness along the dorsum and that these differences are individualized. Specifically, continuous presence of subcutaneous fat from root to tip was found in half the sample, one nose had fat only on the tip, another one only on the root, the four others at both positions. The nasalis muscle was identifiable in nine of the 12 noses, transversing the nose in half the sample, and in the remaining three, only the lateral section of the muscle was identified. The superior border of the septal cartilage does not form a linear extension of the profile contour of the nasal bones but angles downwards. The actual profile contour of the dorsum does not follow the profile of the nasal bones or the septal cartilage. These results may influence the current use of nasal guidelines in forensic facial approximation. PMID:19172735

A Comparison of Anthropometric and Training Characteristics between Female and Male Half-Marathoners and the Relationship to Race Time

PubMed Central

Friedrich, Miriam; Rüst, Christoph A.; Rosemann, Thomas; Knechtle, Patrizia; Barandun, Ursula; Lepers, Romuald; Knechtle, Beat

2013-01-01

Purpose Lower limb skin-fold thicknesses have been differentially associated with sex in elite runners. Front thigh and medial calf skin-fold appear to be related to 1,500m and 10,000m time in men but 400m time in women. The aim of the present study was to compare anthropometric and training characteristics in recreational female and male half-marathoners. Methods The association between both anthropometry and training characteristics and race time was investigated in 83 female and 147 male recreational half marathoners using bi- and multi-variate analyses. Results In men, body fat percentage (β=0.6), running speed during training (β=-3.7), and body mass index (β=1.9) were related to half-marathon race time after multi-variate analysis. After exclusion of body mass index, r2 decreased from 0.51 to 0.49, but body fat percentage (β=0.8) and running speed during training (β=-4.1) remained predictive. In women, body fat percentage (β=0.75) and speed during training (β=-6.5) were related to race time (r2=0.73). For women, the exclusion of body mass index had no consequence on the predictive variables for half-marathon race time. Conclusion To summarize, in both female and male recreational half-marathoners, both body fat percentage and running speed during training sessions were related to half-marathon race times when corrected with co-variates after multi-variate regression analyses. PMID:24868427

A Comparison of Anthropometric and Training Characteristics between Female and Male Half-Marathoners and the Relationship to Race Time.

PubMed

Friedrich, Miriam; Rüst, Christoph A; Rosemann, Thomas; Knechtle, Patrizia; Barandun, Ursula; Lepers, Romuald; Knechtle, Beat

2014-03-01

Lower limb skin-fold thicknesses have been differentially associated with sex in elite runners. Front thigh and medial calf skin-fold appear to be related to 1,500m and 10,000m time in men but 400m time in women. The aim of the present study was to compare anthropometric and training characteristics in recreational female and male half-marathoners. The association between both anthropometry and training characteristics and race time was investigated in 83 female and 147 male recreational half marathoners using bi- and multi-variate analyses. In men, body fat percentage (β=0.6), running speed during training (β=-3.7), and body mass index (β=1.9) were related to half-marathon race time after multi-variate analysis. After exclusion of body mass index, r (2) decreased from 0.51 to 0.49, but body fat percentage (β=0.8) and running speed during training (β=-4.1) remained predictive. In women, body fat percentage (β=0.75) and speed during training (β=-6.5) were related to race time (r (2) =0.73). For women, the exclusion of body mass index had no consequence on the predictive variables for half-marathon race time. To summarize, in both female and male recreational half-marathoners, both body fat percentage and running speed during training sessions were related to half-marathon race times when corrected with co-variates after multi-variate regression analyses.

Mining Existing Radar Altimetry for Sea Ice Freeboard and Thickness Estimates

NASA Astrophysics Data System (ADS)

Childers, V. A.; Brozena, J. M.

2007-12-01

Although satellites can easily monitor ice extent and a variety of ice attributes, they cannot directly measure ice thickness. As a result, very few ice thickness measurements exist to constrain models of Arctic climate change. We estimated sea ice freeboard and thickness from X-band radar altimeter measurements collected over seven field seasons between 1992 and 1999 as part of a Naval Research Lab (NRL)-sponsored airborne geophysical survey of gravity and magnetics over the Arctic Ocean. These freeboard and thickness estimates were compared with the SCICEX ice draft record and the observed thinning of the Arctic Ocean ice cover during the 1990's. Our initial calculations (shown here) suggest that retrieved profiles from this radar altimeter (with uncertainty of about 5 cm) are sensitive to openings in the ice cover. Thus, conversion of these profiles to ice thickness adds an invaluable dataset for assessment of recent and future changes of Arctic climate. And, snow loading is a minor issue here as all the airborne surveys were conducted during mid- to late-summer when the ice cover is mostly bare. The strengths of this dataset are its small antenna footprint of ~50 m and density of spatial coverage allows for detailed characterization of the field of ice thickness, and it provides surveys of regions not covered by SCICEX cruises. The entire survey covers more than half the Arctic Ocean. We find that the Canadian Basin sea ice behavior differs from that in the Eurasian Basin and ultimately affects mean sea ice thickness for each basin.

Asymmetric deformation structure of lava spine in Unzen Volcano, Japan

NASA Astrophysics Data System (ADS)

Miwa, T.; Okumura, S.; Matsushima, T.; Shimizu, H.

2013-12-01

Lava spine is commonly generated by effusive eruption of crystal-rich, dacitic-andesitic magmas. Especially, deformation rock on surface of lava spine has been related with processes of magma ascent, outgassing, and generation of volcanic earthquake (e.g., Cashman et al. 2008). To reveal the relationships and generation process of the spine, it is needed to understand a spatial distribution of the deformation rock. Here we show the spatial distribution of the deformation rock of lava spine in the Unzen volcano, Japan, to discuss the generation process of the spine. The lava spine in Unzen volcano is elongated in the E-W direction, showing a crest like shape with 150 long, 40 m wide and 50 m high. The lava spine is divided into following four parts: 1) Massive dacite part: Dense dacite with 30 m of maximum thickness, showing slickenside on the southern face; 2) Sheared dacite part: Flow band developed dacite with 1.0 m of maximum thickness; 3) Tuffisite part: Network of red colored vein develops in dacite with 0.5 m of maximum thickness; 4) Breccia part: Dacitic breccia with 10 m of maximum thickness. The Breccia part dominates in the northern part of the spine, and flops over Massive dacite part accross the Sheared dacite and Tuffisite parts. The slickenside on southern face of massive dacite demonstrates contact of solids. The slickenside breaks both of phenocryst and groundmass, demonstrating that the slickenside is formed after significant crystallization at the shallow conduit or on the ground surface. The lineation of the slickenside shows E-W direction with almost horizontal rake angle, which is consistent with the movement of the spine to an east before emplacement. Development of sub-vertical striation due to extrusion was observed on northern face of the spine (Hayashi, 1994). Therefore, we suggest that the spine just at extrusion consisted of Massive dacite, Sheared dacite, Tuffisite, Breccia, and Striation parts in the northern half of the spine. Such a variation of rock type is analogous to tectonic fault zone, suggesting that brittle failure of rigid magma due to contact with the conduit wall. Also similar variation is observed in the spine of Mt. St. Helens (Kendrick et al., 2012), which implies the existence of fault zone and brittle failure of magma are common features in the lava spine. The lava spine in Unzen volcano exhibits asymmetric deformation structure about direction of north and south. There is positive correlation between width and length in tectonic fault (Wells and Coppersmith, 1994). Therefore, development of fault zone (Sheared dacite, Tuffisite, and Breccia parts) in northern half may indicate that brittle failure starts at the deeper conduit for the northern half than the southern half of the spine. The asymmetry of magma ascent process is possible to result in asymmetries of outgassing path and location of volcanic earthquake in the conduit.

A pilot split-scalp study of combined fractional radiofrequency microneedling and 5% topical minoxidil in treating male pattern hair loss.

PubMed

Yu, A-J; Luo, Y-J; Xu, X-G; Bao, L-L; Tian, T; Li, Z-X; Dong, Y-X; Li, Y-H

2018-06-27

Various trials have been conducted on the management of male pattern hair loss (MPHL), but the outcomes often seem to be limited. Adjuvant therapies are urgently needed. To evaluate the efficacy and safety of combined fractional radiofrequency microneedling (FRM) and 5% topical minoxidil in the treatment of male pattern hair loss. In total, 19 Chinese men were enrolled in this randomized, controlled, split-scalp trial. Participants received monotherapy with 5% topical minoxidil twice daily to one half of the scalp, while on the other half of the scalp the treatment with twice-daily 5% topical minoxidil was combined with five sessions of FRM at 4-week intervals. Mean hair count and hair thickness, global assessment by the investigators, subject self-assessment and adverse effects were assessed. After 5 months of treatment, mean hair count increased from 44.12 ± 21.58 to 73.14 ± 25.45 on the combined-therapy side and from 46.22 ± 18.77 to 63.21 ± 19.22 on the monotherapy side, while mean hair thickness increased from 53 ± 13 μm to 71 ± 15 μm and from 52 ± 16 μm to 66 ± 14 μm, respectively. Compared with the monotherapy side, the combined-therapy side had a higher degree of improvement in both hair count (P = 0.01) and hair thickness (P = 0.02). Combined treatment with fractional radiofrequency microneedle and 5% topical minoxidil could be an effective and safe treatment option for male pattern hair loss. © 2018 British Association of Dermatologists.

The structure of epitaxial V2O3 films and their surfaces: A medium energy ion scattering study

NASA Astrophysics Data System (ADS)

Window, A. J.; Hentz, A.; Sheppard, D. C.; Parkinson, G. S.; Woodruff, D. P.; Unterberger, W.; Noakes, T. C. Q.; Bailey, P.; Ganduglia-Pirovano, M. V.; Sauer, J.

2012-11-01

Medium energy ion scattering, using 100 keV H+ incident ions, has been used to investigate the growth of epitaxial films, up to thicknesses of ~ 200 Å, of V2O3 on both Pd(111) and Au(111). Scattered-ion energy spectra provide a measure of the average film thickness and the variations in this thickness, and show that, with suitable annealing, the crystalline quality is good. Plots of the scattering yield as a function of scattering angle, so-called blocking curves, have been measured for two different incidence directions and have been used to determine the surface structure. Specifically, scattering simulations for a range of different model structures show poor agreement with experiment for half-metal (….V'O3V) and vanadyl (….V'O3V=O) terminations, with and without surface interlayer relaxations. However, good agreement with experiment is found for the modified oxygen-termination structure, first proposed by Kresse et al., in which a subsurface V half-metal layer is moved up into the outermost V buckled metal layer to produce a VO2 overlayer on the underlying V2O3, with an associated layer structure of ….O3VV''V 'O3. This result is consistent with the predictions of thermodynamic equilibrium at the surface under the surface preparation conditions, but is at variance with the conclusions of earlier studies of this system that have favoured the vanadyl termination. The results of these previous studies are re-evaluated in the light of the new result.

A method for the measurement of dispersion curves of circumferential guided waves radiating from curved shells: experimental validation and application to a femoral neck mimicking phantom

NASA Astrophysics Data System (ADS)

Nauleau, Pierre; Minonzio, Jean-Gabriel; Chekroun, Mathieu; Cassereau, Didier; Laugier, Pascal; Prada, Claire; Grimal, Quentin

2016-07-01

Our long-term goal is to develop an ultrasonic method to characterize the thickness, stiffness and porosity of the cortical shell of the femoral neck, which could enhance hip fracture risk prediction. To this purpose, we proposed to adapt a technique based on the measurement of guided waves. We previously evidenced the feasibility of measuring circumferential guided waves in a bone-mimicking phantom of a circular cross-section of even thickness. The goal of this study is to investigate the impact of the complex geometry of the femoral neck on the measurement of guided waves. Two phantoms of an elliptical cross-section and one phantom of a realistic cross-section were investigated. A 128-element array was used to record the inter-element response matrix of these waveguides. This experiment was simulated using a custom-made hybrid code. The response matrices were analyzed using a technique based on the physics of wave propagation. This method yields portions of dispersion curves of the waveguides which were compared to reference dispersion curves. For the elliptical phantoms, three portions of dispersion curves were determined with a good agreement between experiment, simulation and theory. The method was thus validated. The characteristic dimensions of the shell were found to influence the identification of the circumferential wave signals. The method was then applied to the signals backscattered by the superior half of constant thickness of the realistic phantom. A cut-off frequency and some portions of modes were measured, with a good agreement with the theoretical curves of a plate waveguide. We also observed that the method cannot be applied directly to the signals backscattered by the lower half of varying thicknesses of the phantom. The proposed approach could then be considered to evaluate the properties of the superior part of the femoral neck, which is known to be a clinically relevant site.

Joint cartilage thickness and automated determination of bone age and bone health in juvenile idiopathic arthritis.

PubMed

Twilt, Marinka; Pradsgaard, Dan; Spannow, Anne Helene; Horlyck, Arne; Heuck, Carsten; Herlin, Troels

2017-08-10

BoneXpert is an automated method to calculate bone maturation and bone health index (BHI) in children with juvenile idiopathic arthritis (JIA). Cartilage thickness can also be seen as an indicator for bone health and arthritis damage. The objective of this study was to evaluate the relation between cartilage thickness, bone maturation and bone health in patients with JIA. Patients with JIA diagnosed according ILAR criteria included in a previous ultrasonography (US) study were eligible if hand radiographs were taken at the same time as the US examination. Of the 95 patients 67 met the inclusion criteria. Decreased cartilage thickness was seen in 27% of the examined joints. Decreased BHI was seen in half of the JIA patient, and delayed bone maturation was seen in 33% of patients. A combination of decreased BHI and bone age was seen in 1 out of 5 JIA patients. Decreased cartilage thickness in the knee, wrist and MCP joint was negatively correlated with delayed bone maturation but not with bone health index. Delayed bone maturation and decreased BHI were not related to a thinner cartilage, but a thicker cartilage. No relation with JADAS 10 was found. The rheumatologist should remain aware of delayed bone maturation and BHI in JIA patients with cartilage changes, even in the biologic era.

Amended Results for Hard X-Ray Emission by Non-thermal Thick Target Recombination in Solar Flares

NASA Astrophysics Data System (ADS)

Reep, J. W.; Brown, J. C.

2016-06-01

Brown & Mallik and the corresponding corrigendum Brown et al. presented expressions for non-thermal recombination (NTR) in the collisionally thin- and thick-target regimes, claiming that the process could account for a substantial part of the hard X-ray continuum in solar flares usually attributed entirely to thermal and non-thermal bremsstrahlung (NTB). However, we have found the thick-target expression to become unphysical for low cut-offs in the injected electron energy spectrum. We trace this to an error in the derivation, derive a corrected version that is real-valued and continuous for all photon energies and cut-offs, and show that, for thick targets, Brown et al. overestimated NTR emission at small photon energies. The regime of small cut-offs and large spectral indices involve large (reducing) correction factors but in some other thick-target parameter regimes NTR/NTB can still be of the order of unity. We comment on the importance of these results to flare and microflare modeling and spectral fitting. An empirical fit to our results shows that the peak NTR contribution comprises over half of the hard X-ray signal if δ ≳ 6{≤ft(\\tfrac{{E}0c}{4{keV}}\\right)}0.4.

Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR) Applied to Study the Distribution of Ink Components in Printed Newspapers.

PubMed

Gómez, Nuria; Molleda, Cristina; Quintana, Ester; Carbajo, José M; Rodríguez, Alejandro; Villar, Juan C

2016-09-01

A new method was developed to study how the oil and cyan pigments of cold-set ink are distributed in newspaper thickness. The methodology involved laboratory printing followed by delamination of the printed paper. The unprinted side, printed side, and resulting layers were analyzed using attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR). Three commercial newspapers and black and cyan cold-set inks were chosen for the study. Attenuated total reflection Fourier transform infrared spectroscopy enabled the proportion of oil and cyan pigment on the printed surface and throughout the sheet thickness to be measured. Oil percentage was evaluated as the area increment of the region from 2800 cm(-1) to 3000 cm(-1) The relative amount of cyan pigment was determined as the area of the absorption band at 730 cm(-1) The ink oil was found mainly below half the paper thickness, whereas the pigment was detected at the layers closer to the printed surface, at a depth penetration of less than 15 µm (20% of thickness). Distribution of these two components in paper thickness depended on the type of cold-set ink, the amount of ink transferred, and the newspaper properties. © The Author(s) 2016.

XRD measurement of mean crystallite thickness of illite and illite/smectite: Reappraisal of the Kubler index and the Scherrer equation

USGS Publications Warehouse

Drits, Victor A.; Środoń, Jan; Eberl, D.D.

1997-01-01

The standard form of the Scherrer equation, which has been used to calculate the mean thickness of the coherent scattering domain (CSD) of illite crystals from X-ray diffraction (XRD) full width data at half maximum (FWHM) intensity, employs a constant, Ksh, of 0.89. Use of this constant is unjustified, even if swelling has no effect on peak broadening, because this constant is valid only if all CSDs have a single thickness. For different thickness distributions, the Scherrer “constant” has very different values.Analysis of fundamental particle thickness data (transmission electron microscopy, TEM) for samples of authigenic illite and illite/smectite from diagenetically altered pyroclastics and filamentous illites from sandstones reveals a unique family of lognormal thickness distributions for these clays. Experimental relations between the distributions' lognormal parameters and mean thicknesses are established. These relations then are used to calculate the mean thickness of CSDs for illitic samples from XRD FWHM, or from integral XRD peak widths (integrated intensity/maximum intensity).For mixed-layer illite/smectite, the measured thickness of the CSD corresponds to the mean thickness of the mixed-layer crystal. Using this measurement, the mean thickness of the fundamental particles that compose the mixed-layer crystals can be calculated after XRD determination of percent smectitic interlayers. The effect of mixed layering (swelling) on XRD peak width for these samples is eliminated by using the 003 reflection for glycolated samples, and the 001, 002 or 003 reflection for dehydrated, K-saturated samples. If this technique is applied to the 001 reflection of air-dried samples (Kubler index measurement), mean CSD thicknesses are underestimated due to the mixed-layering effect.The technique was calibrated using NEW MOD©-simulated XRD profiles of illite, and then tested on well-characterized illite and illite/smectite samples. The XRD measurements are in good agreement with estimates of the mean thickness of fundamental particles obtained both from TEM measurements and from fixed cations content, up to a mean value of 20 layers. Correction for instrumental broadening under the conditions employed here is unnecessary for this range of thicknesses.

Transport and spin transfer torques in Fe/MgO/Fe tunnel barriers.

NASA Astrophysics Data System (ADS)

Heiliger, Christian

2008-03-01

The prediction of very high tunneling magnetoresistance (TMR) ratios in crystalline Fe/MgO/Fe [1,2] tunnel junctions has been verified by a number of experiments [3,4]. The high TMR can be understood in terms of the electronic structure of the system. In MgO the δ1 states at the Brillouin zone center decay the most slowly and dominate the tunnelling current. For coherent interfaces, which are achievable due to the small lattice mismatch between Fe and MgO, these δ1 states at the Brillouin zone center are half-metallic in the Fe layers. The dominance of the δ1 states and their half-metallicity cause the high tunnelling magnetoresistance measured in Fe/MgO/Fe tunnel junctions [5]. For the spin transfer torque, we calculate the linear response for small currents and voltages. Our calculations show that the half metallicity of the Fe δ1 states leads to a strong localization of the spin transfer torque to the interface. As a result, the linear current dependence of the torque in the plane of the two magnetizations is independent of the free layer thickness for more than three monolayers of Fe. For perfect samples we also find a linear current dependence of the out-of-plane component. However, this linear piece oscillates rapidly with thickness and averages to zero in the presence of structural imperfections like thickness fluctuation, in agreement with experiment [6]. In this talk I discuss the bias dependence of the TMR and spin transfer torque effects mentioned above and the influence on them of the following factors: the interface structure Fe/MgO, the barrier thickness, and the structure of the leads [7]. This work has been supported in part by the NIST-CNST/UMD-NanoCenter Cooperative Agreement. [1] W. Butler, X.-G. Zhang, T. Schulthess, J. MacLaren, Phys. Rev. B 63 (2001) 054416. [2] J. Mathon, A. Umerski, Phys. Rev. B 63 (2001) 220403. [3] S. Yuasa, T. Nagahama, A. Fukushima, Y. Suzuki, K. Ando, Nature Materials 3 (2004) 868. [4] S.S.P. Parkin, C. Kaiser, A. Panchula, P.M. Rice, B. Hughes, M. Samant, S.-H. Yang Nature Materials 3 (2004) 862. [5] C. Heiliger, P. Zahn, I. Mertig, Materials Today 9 (2006) 46. [6] J. C. Sankey, P. M. Braganca, A. G. F. Garcia, I. N. Krivorotov, R. A. Buhrman, and D. C. Ralph, Phys. Rev. Lett. 96 (2006) 227601. [7] C. Heiliger, M.Gradhand, P. Zahn, I. Mertig, Phys. Rev. Lett. 99 (2007) 066804.

Bleaching and temporomandibular disorder using a half tray design: a clinical report.

PubMed

Robinson, F G; Haywood, V B

2000-05-01

A maxillary soft, custom-fitted tray was fabricated for a patient to perform nightguard vital bleaching. Treatment was interrupted after the patient experienced pain in the temporomandibular joint area shortly after wearing the bleaching prosthesis. The tray was trimmed so the labial, incisal and buccal cusps were covered and Sc) the patient had complete tooth-to-tooth contact in the maximum intercuspal position. The prosthesis proved to be retentive even without the presence of the bleaching material. The thick, sticky bleaching material was contained in the half tray design and the tray was held in place. The patient was able to continue the bleaching process for the 2-week duration necessary to achieve successful lightening of the teeth without further TMD symptoms.

Comparison of training and anthropometric characteristics between recreational male half-marathoners and marathoners.

PubMed

Zillmann, Teresa; Knechtle, Beat; Rüst, Christoph Alexander; Knechtle, Patrizia; Rosemann, Thomas; Lepers, Romuald

2013-06-30

Participation in endurance running such as half-marathon (21-km) and marathon (42-km) has increased over the last decades. We compared 147 recreational male half-marathoners and 126 recreational male marathoners to investigate similarities or differences in their anthropometric and training characteristics. The half-marathoners were heavier (P < 0.05), had longer legs (P < 0.001), thicker upper arms (P < 0.05), a thicker thigh (P < 0.01), a higher sum of skinfold thicknesses (P < 0.01), a higher body fat percentage (P < 0.05) and a higher skeletal muscle mass (P < 0.05) than the marathoners. They had fewer years of experience (P < 0.05), completed fewer weekly training kilometers (P < 0.001), and fewer weekly running hours (P < 0.01) compared to the marathoners. For half-marathoners, body mass index (P = 0.011), percent body fat (P = 0.036) and speed in running during training (P < 0.0001) were related to race time (r2 = 0.47). For marathoners, percent body fat (P = 0.001) and speed in running during training (P < 0.0001) were associated to race time (r2 = 0.47). When body mass index was excluded for the half-marathoners in the multi-variate analysis, r2 decreased to 0.45, therefore body mass index explained only 2% of the variance of half-marathon performance. Percent body fat was significantly and negatively related to running speed during training in both groups. To summarize, half-marathoners showed differences in both anthropometry and training characteristics compared to marathoners that could be related to their lower training volume, most probably due to the shorter race distance they intended to compete. Both groups of athletes seemed to profit from low body fat and a high running speed during training for fast race times.

Low-Speed Wind-Tunnel Investigation to Determine the Aerodynamic Characteristics of a Rectangular Wing Equipped with a Full-Span and an Inboard Half-Span Jet-Augmented Flap Deflected 55 deg

NASA Technical Reports Server (NTRS)

Gainer, Thomas G.

1959-01-01

An investigation to determine the aerodynamic characteristics of a rectangular wing equipped with a full-span and an inboard half-span jet-augmented flap has been made in the Langley 300 MPH 7- by 10-foot tunnel. The wing had an aspect ratio of 8.3 and a thickness-chord ratio of 0.167. A jet of air was blown backward through a small gap, tangentially to the upper surface of a round trailing edge, and was separated from the trailing edge by a very small flap at an angle of 55 deg with respect to the wing-chord plane. The results of the investigation showed that the ratio of total lift to jet-reaction lift for the wing was about 35 percent less for the half-span jet-augmented flap than for the full-span jet-augmented flap. The reduction of the span of the jet-augmented flap from full to half span reduced the maximum value of jet-circulation lift coefficient that could be produced from about 6.8 to a value of about 2.2. The half-span jet- augmented flap gave thrust recoveries considerably poorer than those obtained with the full-span jet-augmented flap. Large nose-down pitching- moment coefficients were produced by the half-span flap, with the greater part of these being the result of the larger jet reactions required to produce a given lift for the half-spin flap compared with that required for the full-span flap.

Origin of thickness dependence of structural phase transition temperatures in BiFeO 3 thin films

DOE PAGES

Yang, Yongsoo; Beekman, Christianne; Siemons, Wolter; ...

2016-03-28

In this study, two structural phase transitions are investigated in highly strained BiFeO 3 thin films grown on LaAlO 3 substrates, as a function of film thickness and temperature via synchrotron x-ray diffraction. Both transition temperatures (upon heating: monoclinic MC to monoclinic MA, and MA to tetragonal) decrease as the film becomes thinner. The existence of an interface layer at the film-substrate interface, deduced from half-order peak intensities, contributes to this behavior only for the thinnest samples; at larger thicknesses (above a few nanometers) the temperature dependence can be understood in terms of electrostatic considerations akin to size effects inmore » ferroelectric phase transitions, but observed here for structural phase transitions within the ferroelectric phase and related to the rearrangement rather than the formation of domains. For ultra-thin films, the tetragonal structure is stable at all investigated temperatures (down to 30 K).« less

Design study of an entry probe spectro-reflectometer

NASA Technical Reports Server (NTRS)

Sill, G. T.; Fink, U.

1986-01-01

A wind tunnel was built to simulate the rapid movement of an entry probe through the Jupiter atmosphere. Wind speeds range from 1 to 50 meters per second in a closed system. Wind velocity and temperature probes as well as a cryogenically cooled cold finger can be placed in the 6 inch diameter viewing section. The initial testing of the wind tunnel involved running sectional profiles through the observation port of air currents of 0.1 to 3.0 atmosphere. The velocity profile was very uniform throughout the cross section of the experimental port, with the exception of the wall effects. The deposition of cooled volatiles using the wind tunnel was not performed. However, measurements of the deposition of H2O ice on a cryogenically cooled thickness modulator were made under ambient conditions, namely room temperature and pressure. In the Frost Depositon Test Facility, ice deposition was measured at thicknesses of about a half millimeter and frost was produced whose thickness reflectivity could easily be measured by reflectance spectroscopy.

Au/ZnS core/shell nanocrystals as an efficient anode photocatalyst in direct methanol fuel cells.

PubMed

Chen, Wei-Ta; Lin, Yin-Kai; Yang, Ting-Ting; Pu, Ying-Chih; Hsu, Yung-Jung

2013-10-04

Au/ZnS core/shell nanocrystals with controllable shell thicknesses were synthesized using a cysteine-assisted hydrothermal method. Incorporating Au/ZnS nanocrystals into the traditional Pt-catalyzed half-cell reaction led to a 43.3% increase in methanol oxidation current under light illumination, demonstrating their promising potential for metal/semiconductor hybrid nanocrystals as the anode photocatalyst in direct methanol fuel cells.

49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., the fringes (“e”) are at least half the length of one bonded cell wall (“d”) (in the ribbon direction... width is 150 mm (5.9 in) ±6 mm (0.24 in), and the thickness is 25 mm (1 in) ±2 mm (0.08 in). The walls of incomplete cells around the edge of the sample are trimmed as follows (See Figure 3). In the width...

CMUTs with high-K atomic layer deposition dielectric material insulation layer.

PubMed

Xu, Toby; Tekes, Coskun; Degertekin, F

2014-12-01

Use of high-κ dielectric, atomic layer deposition (ALD) materials as an insulation layer material for capacitive micromachined ultrasonic transducers (CMUTs) is investigated. The effect of insulation layer material and thickness on CMUT performance is evaluated using a simple parallel plate model. The model shows that both high dielectric constant and the electrical breakdown strength are important for the dielectric material, and significant performance improvement can be achieved, especially as the vacuum gap thickness is reduced. In particular, ALD hafnium oxide (HfO2) is evaluated and used as an improvement over plasma-enhanced chemical vapor deposition (PECVD) silicon nitride (Six)Ny)) for CMUTs fabricated by a low-temperature, complementary metal oxide semiconductor transistor-compatible, sacrificial release method. Relevant properties of ALD HfO2) such as dielectric constant and breakdown strength are characterized to further guide CMUT design. Experiments are performed on parallel fabricated test CMUTs with 50-nm gap and 16.5-MHz center frequency to measure and compare pressure output and receive sensitivity for 200-nm PECVD Six)Ny) and 100-nm HfO2) insulation layers. Results for this particular design show a 6-dB improvement in receiver output with the collapse voltage reduced by one-half; while in transmit mode, half the input voltage is needed to achieve the same maximum output pressure.

A thickness-weighted average perspective of force balance in an idealized circumpolar current

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ringler, Todd Darwin; Saenz, Juan Antonio; Wolfram, Jr., Phillip Justin

The exact, three-dimensional thickness-weighted averaged (TWA) Boussinesq equations are used to diagnose eddy-mean flow interaction in an idealized circumpolar current (ICC). The force exerted by mesoscale eddies on the TWA velocity is expressed as the divergence of the Eliassen-Palm flux tensor. Consistent with previous findings, the analysis indicates that the dynamically relevant definition of the ocean surface layer is comprised of the set of buoyancy coordinates that ever reside at the ocean surface at a given horizontal position. The surface layer is found to be a physically distinct object with a diabatic- and force-balance that is largely isolated from themore » underlying adiabatic region in the interior. Within the ICC surface layer, the TWA meridional velocity is southward/northward in the top/bottom half, and has a value near zero at the bottom. In the top half of the surface layer, the zonal forces due to wind stress and meridional advection of potential vorticity act to accelerate the TWA zonal velocity; equilibrium is obtained by eddies decelerating the zonal flow via a downward flux of eastward momentum that increases with depth. In the bottom half of the surface layer, the accelerating force of the wind stress is balanced by the eddy force and meridional advection of potential vorticity. The bottom of the surface layer coincides with the location where the zonal eddy force, meridional advection of potential vorticity and zonal wind stress force are all zero. The net meridional transport, S f, within the surface layer is a small residual of its southward and northward TWA meridional flows. Furthermore, the mean meridional gradient of surface-layer buoyancy is advected by S f to balance the surface buoyancy fluxs.« less

A thickness-weighted average perspective of force balance in an idealized circumpolar current

DOE PAGES

Ringler, Todd Darwin; Saenz, Juan Antonio; Wolfram, Jr., Phillip Justin; ...

2016-11-22

The exact, three-dimensional thickness-weighted averaged (TWA) Boussinesq equations are used to diagnose eddy-mean flow interaction in an idealized circumpolar current (ICC). The force exerted by mesoscale eddies on the TWA velocity is expressed as the divergence of the Eliassen-Palm flux tensor. Consistent with previous findings, the analysis indicates that the dynamically relevant definition of the ocean surface layer is comprised of the set of buoyancy coordinates that ever reside at the ocean surface at a given horizontal position. The surface layer is found to be a physically distinct object with a diabatic- and force-balance that is largely isolated from themore » underlying adiabatic region in the interior. Within the ICC surface layer, the TWA meridional velocity is southward/northward in the top/bottom half, and has a value near zero at the bottom. In the top half of the surface layer, the zonal forces due to wind stress and meridional advection of potential vorticity act to accelerate the TWA zonal velocity; equilibrium is obtained by eddies decelerating the zonal flow via a downward flux of eastward momentum that increases with depth. In the bottom half of the surface layer, the accelerating force of the wind stress is balanced by the eddy force and meridional advection of potential vorticity. The bottom of the surface layer coincides with the location where the zonal eddy force, meridional advection of potential vorticity and zonal wind stress force are all zero. The net meridional transport, S f, within the surface layer is a small residual of its southward and northward TWA meridional flows. Furthermore, the mean meridional gradient of surface-layer buoyancy is advected by S f to balance the surface buoyancy fluxs.« less

PREPARATION, IN VITRO AND IN VIVO CHARACTERIZATION OF HYDROPHOBIC PATCHES OF A HIGHLY WATER SOLUBLE DRUG FOR PROLONGED PLASMA HALF LIFE: EFFECT OF PERMEATION ENHANCERS.

PubMed

Yaqoob, Ayesha; Ahmad, Mahmood; Mahmood, Asif; Sarfraz, Rai Muhammad

2016-11-01

Aim of present study was to develop metoprolol matrix patches using different enhancers. Combination of two hydrophobic polymers, ethyl cellulose and eudragit RL 100 (8 : 2) were used for preparation of unilaminated matrix patch. 10% w/w of isopropyl myristate (IPM), dimethyl sulfoxide (DMSO), span (20 (S20), Tween 20 (T20) and eucalyptus oil as enhancers and 40% of dibutyl phthalate as plasticizer were used. Prepared patches were evaluated for physical appearance, weight uniformity and thickness. FTIR studies were performed to assess compatibility among ingredients and developed formulation. Dissolution and permeation studies were performed to compare effects of enhancers. Surface morphology after release was examined by scanning electron microscopy. Selected formulation was subjected to in vivo studies by randomized crossover design in rabbits (n = 6) for pharmacokinetic comparison with oral solution administration. Physical evaluation revealed that translucent, flexible, non brittle patches of uniform weight and thickness were prepared. Release from patches followed Higuchi model. Mechanism of release was Fickian. Formulation containing IPM showed that release was by anomalous transport. Highest permeation flux was observed for formulation containing IPM with 2-fold enhancement in permeation. Permeation flux for patches was in order of formulation with no enhancer > IPM > T20 > S20 > DMSO = eucalyptus oil. Plasma concentration from in vivo studies exhibited sustained plasma levels of metoprolol after transdermal patch application in comparison to oral solution administration. Pharmacokinetic analysis of in vivo data elucidated that half life was increased 8 times when compared to oral administration, due to controlled release of drug for longer period of time. These findings suggested that hydrophobic transdermal patches of highly water soluble drug metoprolol were successfully prepared with 10% of IPM for sustained systemic delivery for prolonged half life.

Ly-alpha polarimeter design for CLASP rocket experiment

NASA Astrophysics Data System (ADS)

Kubo, M.; Watanabe, H.; Narukage, N.; Ishikawa, R.; Bando, T.; Kano, R.; Tsuneta, S.; Kobayashi, K.; Ichimoto, K.; Trujillo Bueno, J.; Song, D.

2011-12-01

A sounding-rocket program called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is proposed to be launched in the Summer of 2014. CLASP will observe the upper solar chromosphere in Ly-alpha (121.567 nm), aiming to detect the linear polarization signal produced by scattering processes and the Hanle effect for the first time. The CLASP needs a rotating half-waveplate and a polarization analyzer working at the Ly-alpha wavelength to measure the linear polarization signal. We select Magnesium Fluoride (MgF2) as a material of the optical components because of its birefringent property and high transparency at UV wavelength. We have confirmed that the reflection at the Brewster's Angle of MgF2 plate is a good polarization analyzer for the Ly-alpha line by deriving its ordinary refractive index and extinction coefficient along the ordinary and extraordinary axes. These optical parameters are calculated with a least-square fitting in such a way that the reflectance and transmittance satisfy the Kramers-Kronig relation. The reflectance and transmittance against oblique incident angles for the s-polarized and the p-polarized light are measured using the synchrotron beamline at the Ultraviolet Synchrotron Orbital Radiation Facility (UVSOR). We have also measured a retardation of a zeroth-order waveplate made of MgF2. The thickness difference of the waveplate is 14.57 um.This waveplate works as a half-waveplate at 121.74 nm. From this measurement, we estimate that a waveplate with the thickness difference of 15.71 um will work as a half-waveplate at the Ly-alpha wavelength. We have developed a rotating waveplate - polarization analyzer system called a prototype of CLASP polarimeter, and input the perfect Stokes Q and U signals. The modulation patterns that are consistent with the theoretical prediction are successfully obtained in both cases.

Geophysical Investigation of Avon Valley, West-Central Montana, using Gravity and Seismic Reflection Profiling

NASA Astrophysics Data System (ADS)

Knatterud, L.; Mosolf, J.; Speece, M. A.; Zhou, X.

2014-12-01

The Avon Valley and adjacent mountains in west-central Montana lie within the Lewis and Clark Line, a major system of WNW-striking faults and folds that transect the more northerly structural grain of the northern Rockies and represent alternating episodes of transtensional and transpressional deformation. The northwest-trending valley has been previously interpreted as an extensional half graben filled with Tertiary sedimentary and volcanic deposits; however, little-to-no geophysical constraints on basin architecture or the thickness of Tertiary fill have been reported. A major northwest-striking fault with significant normal displacement clearly bounds the valley to the northeast, juxtaposing Tertiary sedimentary deposits against Proterozoic-Mesozoic units deformed by shortening structures and crosscut by Cretaceous granitic intrusions. Tertiary volcanic deposits unconformably overlying faulted and folded Phanerozoic-Proterozoic sequences in the eastern Garnet Range bound the valley to the southwest, but in the past no faults had been mapped along this margin. New mapping by the Montana Bureau of Mines and Geology (MBMG) has identified a system of high-angle, northwest- and northeast-striking, oblique-slip faults along the southwest border of the Avon calling into question if the valley is a half, full, or asymmetrical graben. Geophysical data has recently been acquired by Montana Tech to help define the structural architecture of the Avon Valley and the thickness of its Tertiary fill. Gravity data and a short seismic reflection profile have been collected and a preliminary interpretation of these data indicates a half graben with a series of normal faults bounding the western side of the valley. Ongoing gravity data collection throughout 2014 should refine this interpretation by better defining the bedrock-Tertiary interface at depth.

Magnetic Configurations of the Tilted Current Sheets and Dynamics of Their Flapping in Magnetotail

NASA Astrophysics Data System (ADS)

Shen, C.; Rong, Z. J.; Li, X.; Dunlop, M.; Liu, Z. X.; Malova, H. V.; Lucek, E.; Carr, C.

2009-04-01

Based on multiple spacecraft measurements, the geometrical structures of tilted current sheet and tail flapping waves have been analyzed and some features of the tilted current sheets have been made clear for the first time. The geometrical features of the tilted current sheet revealed in this investigation are as follows: (1) The magnetic field lines (MFLs) are generally plane curves and the osculating planes in which the MFLs lie are about vertical to the magnetic equatorial plane, while the tilted current sheet may lean severely to the dawn or dusk side. (2) The tilted current sheet may become very thin, its half thickness is generally much less than the minimum radius of the curvature of the MFLs. (3) In the neutral sheet, the field-aligned current density becomes very large and has a maximum value at the center of the current sheet. (4) In some cases, the current density is a bifurcated one, and the two humps of the current density often superpose two peaks in the gradient of magnetic strength, indicating that the magnetic gradient drift current is possibly responsible for the formation of the two humps of the current density in some tilted current sheets. Tilted current sheets often appear along with tail thick current sheet flapping waves. It is found that, in the tail flapping current sheets, the minimum curvature radius of the MFLs in the current sheet is rather large with values around 1RE, while the neutral sheet may be very thin, with its half thickness being several tenths ofRE. During the flapping waves, the current sheet is tilted substantially, and the maximum tilt angle is generally larger than 45

Crustal structure along the geosciences transect from Altay to Altun Tagh

USGS Publications Warehouse

Wang, Y.-X.; Han, G.-H.; Jiang, M.; Yuan, X.-C.; Mooney, W.D.; Coleman, R.G.

2004-01-01

Based upon the P- and S-wave data acquired along the geoscience transect from Altay to Altun Tagh in Northwest China, the crustal structures of velocities and Poisson's ratio are determined. The crustal velocity structure features an obvious three-layer structure with velocities of 6. 0 ??? 6. 3km/s, 6. 3 ??? 6. 6km/s and 6.9 ??? 7. Okm/s from surface to depth, respectively. The crustal thickness along the. entire profile is mostly 50km with the thickest crust (56km) beneath the Altay and the thinnest (46km) beneath the Junggar basin. The velocities underlying Moho are 7.7 to 7.8km/s between the Tianshan and the Junggar basin, and 7.9 to 8.0km/s below the Altay Mountains and eastern margin of the Tarim basin. The southern half of the profile, including the eastern Tianshan Mountains and eastern margin of the Tarim basin, shows low P-wave velocities and ?? = 0. 25 to a depth, of 30km, which suggests a quartz-rich, granitic upper crustal composition. The northern half of the profile below the Altay Mountains and Junggar Accretional Belt has a higher Poisson's ratio of ?? = 0.26 ??? 0.27 to a depth of 30km, indicative of an intermediate crustal composition, The entire profile is underlain by a 15 to 30km thick high-velocity (6.9 ??? 7.0km/s; ?? = 0. 26 - 0.28) lower crustal layer that we interpret to have a bulk composition of mafic granulite. At the southern end of the profile a 5km-thick midcrustal low-velocity layer ( Vp, = 5.9km/s, ?? = 0.25) underlies the Tianshan and the region to the south, and may be indicative of granitic intrusive in Late Paleozoic.

Orientation of Myosin Binding Protein C in the Cardiac Muscle Sarcomere Determined by Domain-Specific Immuno-EM

PubMed Central

Lee, Kyounghwan; Harris, Samantha P.; Sadayappan, Sakthivel; Craig, Roger

2014-01-01

Myosin binding protein-C is a thick filament protein of vertebrate striated muscle. The cardiac isoform (cMyBP-C) is essential for normal cardiac function, and mutations in cMyBP-C cause cardiac muscle disease. The rod-shaped molecule is composed primarily of 11 immunoglobulin- or fibronectin-like domains, and is located at 9 sites, 43 nm apart, in each half of the A-band. To understand how cMyBP-C functions, it is important to know its structural organization in the sarcomere, as this will affect its ability to interact with other sarcomeric proteins. Several models have been proposed, in which cMyBP-C wraps around, extends radially from, or runs axially along the thick filament. Our goal was to define cMyBP-C orientation by determining the relative axial positions of different cMyBP-C domains. Immuno-electron microscopy was performed using mouse cardiac myofibrils labeled with antibodies specific to the N- and C-terminal domains and to the middle of cMyBP-C. Antibodies to all regions of the molecule, except the C-terminus, labeled at the same nine axial positions in each half A-band, consistent with a circumferential and/or radial rather than an axial orientation of the bulk of the molecule. The C-terminal antibody stripes were slightly displaced axially, demonstrating an axial orientation of the C-terminal 3 domains, with the C-terminus closer to the M-line. These results, combined with previous studies, suggest that the C-terminal domains of cMyBP-C run along the thick filament surface, while the N-terminus extends towards neighboring thin filaments. This organization provides a structural framework for understanding cMyBP-C’s modulation of cardiac muscle contraction. PMID:25451032

Historical trend in river ice thickness and coherence in hydroclimatological trends in Maine

USGS Publications Warehouse

Huntington, T.G.; Hodgkins, G.A.; Dudley, R.W.

2003-01-01

We analyzed long-term records of ice thickness on the Piscataquis River in central Maine and air temperature in Maine to determine whether there were temporal trends that were associated with climate warming. The trend in ice thickness was compared and correlated with regional time series of winter air temperature, heating degree days (HDD), date of river ice-out, seasonal center-of-volume date (SCVD) (date on which half of the stream runoff volume during the period 1 Jan. to 31 May has occurred), water temperature, and lake ice-out date. All of these variables except lake ice-out date showed significant temporal trends during the 20th century. Average ice thickness around 28 February decreased by about 23 cm from 1912 to 2001. Over the period 1900 to 1999, winter air temperature increased by 1.7??C and HDD decreased by about 7.5%. Final ice-out date on the Piscataquis River occurred earlier (advanced), by 0.21 days yr-1 over the period 1931 to 2002, and the SCVD advanced by 0.11 days yr-1 over the period 1903 to 2001. Ice thickness was significantly correlated (P-value < 0.01) with winter air temperature, HDD, river ice-out, and SCVD. These systematic temporal trends in multiple hydrologic indicator variables indicate a coherent response to climate forcing.

Local sample thickness determination via scanning transmission electron microscopy defocus series.

PubMed

Beyer, A; Straubinger, R; Belz, J; Volz, K

2016-05-01

The usable aperture sizes in (scanning) transmission electron microscopy ((S)TEM) have significantly increased in the past decade due to the introduction of aberration correction. In parallel with the consequent increase of convergence angle the depth of focus has decreased severely and optical sectioning in the STEM became feasible. Here we apply STEM defocus series to derive the local sample thickness of a TEM sample. To this end experimental as well as simulated defocus series of thin Si foils were acquired. The systematic blurring of high resolution high angle annular dark field images is quantified by evaluating the standard deviation of the image intensity for each image of a defocus series. The derived dependencies exhibit a pronounced maximum at the optimum defocus and drop to a background value for higher or lower values. The full width half maximum (FWHM) of the curve is equal to the sample thickness above a minimum thickness given by the size of the used aperture and the chromatic aberration of the microscope. The thicknesses obtained from experimental defocus series applying the proposed method are in good agreement with the values derived from other established methods. The key advantages of this method compared to others are its high spatial resolution and that it does not involve any time consuming simulations. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Model-based cartilage thickness measurement in the submillimeter range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Streekstra, G. J.; Strackee, S. D.; Maas, M.

2007-09-15

Current methods of image-based thickness measurement in thin sheet structures utilize second derivative zero crossings to locate the layer boundaries. It is generally acknowledged that the nonzero width of the point spread function (PSF) limits the accuracy of this measurement procedure. We propose a model-based method that strongly reduces PSF-induced bias by incorporating the PSF into the thickness estimation method. We estimated the bias in thickness measurements in simulated thin sheet images as obtained from second derivative zero crossings. To gain insight into the range of sheet thickness where our method is expected to yield improved results, sheet thickness wasmore » varied between 0.15 and 1.2 mm with an assumed PSF as present in the high-resolution modes of current computed tomography (CT) scanners [full width at half maximum (FWHM) 0.5-0.8 mm]. Our model-based method was evaluated in practice by measuring layer thickness from CT images of a phantom mimicking two parallel cartilage layers in an arthrography procedure. CT arthrography images of cadaver wrists were also evaluated, and thickness estimates were compared to those obtained from high-resolution anatomical sections that served as a reference. The thickness estimates from the simulated images reveal that the method based on second derivative zero crossings shows considerable bias for layers in the submillimeter range. This bias is negligible for sheet thickness larger than 1 mm, where the size of the sheet is more than twice the FWHM of the PSF but can be as large as 0.2 mm for a 0.5 mm sheet. The results of the phantom experiments show that the bias is effectively reduced by our method. The deviations from the true thickness, due to random fluctuations induced by quantum noise in the CT images, are of the order of 3% for a standard wrist imaging protocol. In the wrist the submillimeter thickness estimates from the CT arthrography images correspond within 10% to those estimated from the anatomical sections. We present a method that yields virtually unbiased thickness estimates of cartilage layers in the submillimeter range. The good agreement of thickness estimates from CT images with estimates from anatomical sections is promising for clinical application of the method in cartilage integrity staging of the wrist and the ankle.« less

Strong modification of thin film properties due to screening across the interface

NASA Astrophysics Data System (ADS)

Altendorf, S. G.; Reisner, A.; Tam, B.; Meneghin, F.; Wirth, S.; Tjeng, L. H.

2018-04-01

We report on our investigation of the influence of screening across the interface on the properties of semiconducting thin films. Using EuO as a well-defined model material, layers of various thickness deposited on yttria-stabilized zirconia (100) substrates were covered half with Mg metal and half with the wide-band-gap insulator MgO. We observed that the Curie temperature for the thinnest films is significantly higher for the part which is interfaced with the metal compared to the part which is interfaced with the insulator. We infer that the proximity of a polarizable medium reduces the energies of virtual charge excitations and thus increases the effective exchange interactions, a strong effect that can be utilized systematically for the design of thin film and multilayer systems.

NUCLEAR CHEMISTRY RESEARCH AT CARNEGIE INSTITUTE OF TECHNOLOGY 1962-1963. Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1963-06-01

Progress is reported on: nuclear reaction studies of cross sections of iron and stone meteoritic elements for 130- to 400-Mev protons, simulated cosmic- ray irradiations of thick iron and stone targets with 100-Mev to 3-Bev protons, and induced alpha-activity in short half-life ranges; nuclear geochemistry and cosmochemistry studies of nuclide dating of sediments, pseudo-diffusion in ocean and Maria sediments, cosmogenic radionuclides in iron and stone meteorites, cosmogenic radionuclides in Bondoc Achondrite and Bogou iron, half life of Mn/sup 53/, cosmogenic radioactivity in fragments of Sputnik N, Be/sup 10/ occurrence in tektites, and conversion of sealed anticoincidence shield counters to flow,more » counters; and the search for natural radioactivity in Ca/sup 48/. (B.O.G.)« less

Small-scale explosive seam welding. [using ribbon explosive encased in lead sheath

NASA Technical Reports Server (NTRS)

Bement, L. J.

1972-01-01

A unique small scale explosive seam welding technique is reported that has successfully joined a variety of aluminum alloys and alloy combinations in thicknesses to 0.125 inch, as well as titanium in thicknesses to 0.056 inch. The explosively welded joints are less than one-half inch in width and apparently have no long length limitation. The ribbon explosive developed in this study contains very small quantities of explosive encased in a flexible thin lead sheath. The evaluation and demonstration of this welding technique was accomplished in three phases: evaluation and optimization of ten major explosive welding variables, the development of four weld joints, and an applicational analysis which included photomicrographs, pressure integrity tests, vacuum effects, and fabrication of some potentially useful structures in aluminum and titanium.

Neutron detection using a current biased kinetic inductance detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shishido, Hiroaki, E-mail: shishido@pe.osakafu-u.ac.jp; Miyajima, Shigeyuki; Ishida, Takekazu

2015-12-07

We demonstrate neutron detection using a solid state superconducting current biased kinetic inductance detector (CB-KID), which consists of a superconducting Nb meander line of 1 μm width and 40 nm thickness. {sup 10}B-enriched neutron absorber layer of 150 nm thickness is placed on top of the CB-KID. Our neutron detectors are able to operate in a wide superconducting region in the bias current–temperature diagram. This is in sharp contrast with our preceding current-biased transition edge detector, which can operate only in a narrow range just below the superconducting critical temperature. The full width at half maximum of the signals remains of the ordermore » of a few tens of ns, which confirms the high speed operation of our detectors.« less

Investigations at supersonic speeds of 22 triangular wings representing two airfoil sections for each of 11 apex angles

NASA Technical Reports Server (NTRS)

Love, Eugene S

1949-01-01

Data obtained from wind tunnel investigations of two series of 11 triangular wings conducted at Mach numbers of 1.62, 1.92, and 1.40 to determine the effect of leading-edge shape and to compare actual test values with the nonviscous linear theory are presented. The two series of wings had identical plan forms, a constant thickness ratio of 8 percent, a constant location of maximum-thickness point of 18 percent, and a range of apex half-angles from 10 degrees to forty-five degrees. The first series has an elliptical leading edge and the second series a wedge leading edge. Measurements were made of lift, drag, pitching moment, and pressure distribution, the latter being confined to three wings at one Mach number.

Simulation of multiple scattering in a medium with an anisotropic scattering pattern

NASA Astrophysics Data System (ADS)

Kuzmin, V. L.; Val'kov, A. Yu.

2017-03-01

Multiple backscattering from layers with various thicknesses, including the case of half-space, is numerically simulated and a comparative analysis is performed for systems with the anisotropy of scattering described by the Henyey-Greenstein and Rayleigh-Gans phase functions. It is shown that the intensity of backscattering depends on the form of the phase function; the difference between the intensities obtained within the two models increases with anisotropy.

Effect of image quality on calcification detection in digital mammography

PubMed Central

Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

2012-01-01

Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC (AFROC) area decreased from 0.84 to 0.63 and the ROC area decreased from 0.91 to 0.79 (p < 0.0001). This corresponded to a 30% drop in lesion sensitivity at a NLF equal to 0.1. Detection was also sensitive to the dose used. There was no significant difference in detection between the two image processing algorithms used (p > 0.05). It was additionally found that lower threshold gold thickness from CDMAM analysis implied better cluster detection. The measured threshold gold thickness passed the acceptable limit set in the EU standards for all image qualities except half dose CR. However, calcification detection varied significantly between image qualities. This suggests that the current EU guidelines may need revising. Conclusions: Microcalcification detection was found to be sensitive to detector and dose used. Standard measurements of image quality were a good predictor of microcalcification cluster detection. PMID:22755704

Effect of image quality on calcification detection in digital mammography.

PubMed

Warren, Lucy M; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M; Wallis, Matthew G; Chakraborty, Dev P; Dance, David R; Bosmans, Hilde; Young, Kenneth C

2012-06-01

This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC (AFROC) area decreased from 0.84 to 0.63 and the ROC area decreased from 0.91 to 0.79 (p < 0.0001). This corresponded to a 30% drop in lesion sensitivity at a NLF equal to 0.1. Detection was also sensitive to the dose used. There was no significant difference in detection between the two image processing algorithms used (p > 0.05). It was additionally found that lower threshold gold thickness from CDMAM analysis implied better cluster detection. The measured threshold gold thickness passed the acceptable limit set in the EU standards for all image qualities except half dose CR. However, calcification detection varied significantly between image qualities. This suggests that the current EU guidelines may need revising. Microcalcification detection was found to be sensitive to detector and dose used. Standard measurements of image quality were a good predictor of microcalcification cluster detection. © 2012 American Association of Physicists in Medicine.

Visual detection of particulates in x-ray images of processed meat products

NASA Astrophysics Data System (ADS)

Schatzki, Thomas F.; Young, Richard; Haff, Ron P.; Eye, J.; Wright, G.

1996-08-01

A study was conducted to test the efficacy of detecting particulate contaminants in processed meat samples by visual observation of line-scanned x-ray images. Six hundred field- collected processed-product samples were scanned at 230 cm2/s using 0.5 X 0.5-mm resolution and 50 kV, 13 mA excitation. The x-ray images were image corrected, digitally stored, and inspected off-line, using interactive image enhancement. Forty percent of the samples were spiked with added contaminants to establish the visual recognition of contaminants as a function of sample thickness (1 to 10 cm), texture of the x-ray image (smooth/textured), spike composition (wood/bone/glass), size (0.1 to 0.4 cm), and shape (splinter/round). The results were analyzed using a maximum likelihood logistic regression method. In packages less than 6 cm thick, 0.2-cm-thick bone chips were easily recognized, 0.1-cm glass splinters were recognized with some difficulty, while 0.4-cm-thick wood was generally missed. Operational feasibility in a time-constrained setting was confirmed. One half percent of the samples arriving from the field contained bone slivers > 1 cm long, 1/2% contained metallic material, while 4% contained particulates exceeding 0.3 cm in size. All of the latter appeared to be bone fragments.

Structural and optical properties of CuS thin films deposited by Thermal co-evaporation

NASA Astrophysics Data System (ADS)

Sahoo, A. K.; Mohanta, P.; Bhattacharyya, A. S.

2015-02-01

Copper sulfide (CuS) thin films with thickness 100, 150 and 200 nm have been deposited on glass substrates by thermal co-evaporation of Copper and Sulphur. The effect of CuS film thickness on the structural and optical properties have investigated and discussed. Structural and optical investigations of the films were carried out by X-ray diffraction, atomic force microscopy, high-resolution transmission electron microscopy and UV spectroscopy. XRD and selected area electron diffraction conforms that polycrystalline in nature with hexagonal crystal structure. AFM studies revealed a smooth surface morphology with root mean-square roughness values increases from 24 nm to 42 nm as the film thickness increase from 100 nm to 200 nm. AFM image showed that grain size increases with thickness of film increases and good agreement with the calculated from full width half maximum of the X-ray diffraction peak using Scherrer's formula and Williamson-Hall plot. The absorbance of the thin films were absorbed decreases with wavelength through UV-visible regions but showed a increasing in the near-infrared regions. The reflectance spectra also showed lower reflectance peak (25% to 32%) in visible region and high reflectance peak (49 % to 54 %) in near-infrared region. These high absorbance films made them for photo-thermal conversion of solar energy.

Full thickness facial burns: Outcomes following orofacial rehabilitation.

PubMed

Clayton, N A; Ward, E C; Maitz, P K M

2015-11-01

To document orofacial rehabilitation and outcomes after full thickness orofacial burn. Participants included 12 consecutive patients presenting with full thickness orofacial burns. A group of 120 age-matched healthy participants was recruited for normative comparison. Non-surgical exercise was initiated within 48 h of admission and continued until wounds had healed, circumoral scar tissue had stabilised and functional goals were achieved to the best of the patient's ability. Outcomes were documented using vertical and horizontal mouth opening measures at start and end of treatment and therapy duration was recorded. At commencement of treatment, participants had significantly (p<0.001) reduced vertical and horizontal mouth opening range compared to controls. Average duration of orofacial contracture management was 550 days, with half requiring >2 years rehabilitation. By end of treatment, significant (p<0.01) positive improvement in vertical and horizontal mouth opening had been achieved, however measures had returned to lower limits of normal function and remained significantly (p<0.05) reduced compared to the control group. This study demonstrates that although positive gains can be achieved through non-surgical exercise after full thickness burn, the duration of rehabilitation is considerable and some degree of long term loss in functional mouth opening remains. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Charge transfer at the interface between ferromagnetic La0.7Sr0.3MnO3 and superconducting EuBa2Cu3O7 probed by STM/STS

NASA Astrophysics Data System (ADS)

Liu, Yinghao; Xiong, Jie

2012-02-01

La0.7Sr0.3MnO3 (LSMO) is a ferromagnetic half-metallic compound with nearly 100% spin polarization at room temperature, making it an ideal candidate for applications in spintronic devices. However, this useful functionality disappears when the thickness of LSMO film grown on SrTiO3 substrate is reduced to below 4 nm, limiting its application in nanoscale devices. Here, we show that metallic and ferromagnetic properties of ultrathin (< 4nm) LSMO film can be restored by interfacing it with a superconductor EuBa2Cu3O7- δ (EBCO). We use scanning tunneling microscopy and spectroscopy to probe the evolution of the electronic structure of LSMO film grown on EBCO as functions of LSMO layer thickness and aging of bilayer LSMO/EBCO. Our results reveal that the charge (hole) transfer at LSMO/EBCO interface is responsible for driving LSMO film (of only five-unit-cell thickness) to metallic state. The conductive behavior of aged LSMO/EBCO bilayers varies systematically with the thickness of LSMO layer, allowing us to estimate the charge-transfer depth to be 4˜5 nm on the LSMO side.

Analysis of the moments of the sensitivity function for resistivity over a homogeneous half-space: Rules of thumb for pseudoposition, offline sensitivity and resolution

NASA Astrophysics Data System (ADS)

Butler, S. L.

2017-08-01

It is instructive to consider the sensitivity function for a homogeneous half space for resistivity since it has a simple mathematical formula and it does not require a priori knowledge of the resistivity of the ground. Past analyses of this function have allowed visualization of the regions that contribute most to apparent resistivity measurements with given array configurations. The horizontally integrated form of this equation gives the sensitivity function for an infinitesimally thick horizontal slab with a small resistivity contrast and analysis of this function has admitted estimates of the depth of investigation for a given electrode array. Recently, it has been shown that the average of the vertical coordinate over this function yields a simple formula that can be used to estimate the depth of investigation. The sensitivity function for a vertical inline slab has also been previously calculated. In this contribution, I show that the sensitivity function for a homogeneous half-space can also be integrated so as to give sensitivity functions to semi-infinite vertical slabs that are perpendicular to the array axis. These horizontal sensitivity functions can, in turn, be integrated over the spatial coordinates to give the mean horizontal positions of the sensitivity functions. The mean horizontal positions give estimates for the centres of the regions that affect apparent resistivity measurements for arbitrary array configuration and can be used as horizontal positions when plotting pseudosections even for non-collinear arrays. The mean of the horizontal coordinate that is perpendicular to a collinear array also gives a simple formula for estimating the distance over which offline resistivity anomalies will have a significant effect. The root mean square (rms) widths of the sensitivity functions are also calculated in each of the coordinate directions as an estimate of the inverse of the resolution of a given array. For depth and in the direction perpendicular to the array, the rms thickness is shown to be very similar to the mean distance. For the direction parallel to the array, the rms thickness is shown to be proportional to the array length and similar to the array length divided by 2 for many arrays. I expect that these formulas will provide useful rules of thumb for estimating the centres and extents of regions influencing apparent resistivity measurements for survey planning and for education.

Influence of anode thickness on the power output of solid oxide fuel cells with (La,Sr)(Co,Fe)-type cathode

NASA Astrophysics Data System (ADS)

Menzler, Norbert H.; Haanappel, Vincent A. C.

The influence of the thickness of the anode (functional layer) on the power output of anode-supported solid oxide fuel cells with a lanthanum-strontium-cobalt-ferrite cathode was investigated. The anode was applied by vacuum slip casting and the thickness varied between 1 and 22 μm. All other material and microstructural parameters were kept constant. Single cells with dimensions of 50 mm × 50 mm and with an active cathode area of 40 mm × 40 mm were manufactured and tested in an alumina housing with air as oxidant and hydrogen with 3% water vapour as the fuel gas. Results have shown that SOFCs with anodes between 1 and 13 μm have slightly better performance than those with thicker anodes (∼1.7 A cm -2 versus 1.5 A cm -2 at 800 °C and 0.7 V). The current densities were discussed with respect to cell area specific resistance, helium leak rate of the half-cell, and microstructure.

Multi-band filter design with less total film thickness for short-wave infrared

NASA Astrophysics Data System (ADS)

Yan, Yung-Jhe; Chien, I.-Pen; Chen, Po-Han; Chen, Sheng-Hui; Tsai, Yi-Chun; Ou-Yang, Mang

2017-08-01

A multi-band pass filter array was proposed and designed for short wave infrared applications. The central wavelength of the multi-band pass filters are located about 905 nm, 950 nm, 1055 nm and 1550 nm. In the simulation of an optical interference band pass filter, high spectrum performance (high transmittance ratio between the pass band and stop band) relies on (1) the index gap between the selected high/low-index film materials, with a larger gap correlated to higher performance, and (2) sufficient repeated periods of high/low-index thin-film layers. When determining high and low refractive index materials, spectrum performance was improved by increasing repeated periods. Consequently, the total film thickness increases rapidly. In some cases, a thick total film thickness is difficult to process in practice, especially when incorporating photolithography liftoff. Actually the maximal thickness of the photoresist being able to liftoff will bound the total film thickness of the band pass filter. For the application of the short wave infrared with the wavelength range from 900nm to 1700nm, silicone was chosen as a high refractive index material. Different from other dielectric materials used in the visible range, silicone has a higher absorptance in the visible range opposite to higher transmission in the short wave infrared. In other words, designing band pass filters based on silicone as a high refractive index material film could not obtain a better spectrum performance than conventional high index materials like TiO2 or Ta2O5, but also its material cost would reduce about half compared to the total film thickness with the conventional material TiO2. Through the simulation and several experimental trials, the total film thickness below 4 um was practicable and reasonable. The fabrication of the filters was employed a dual electric gun deposition system with ion assisted deposition after the lithography process. Repeating four times of lithography and deposition process and black matrix coating, the optical device processes were completed.

SnO2 epitaxial films with varying thickness on c-sapphire: Structure evolution and optical band gap modulation

NASA Astrophysics Data System (ADS)

Zhang, Mi; Xu, Maji; Li, Mingkai; Zhang, Qingfeng; Lu, Yinmei; Chen, Jingwen; Li, Ming; Dai, Jiangnan; Chen, Changqing; He, Yunbin

2017-11-01

A series of a-plane SnO2 films with thickness between 2.5 nm and 1436 nm were grown epitaxially on c-sapphire by pulsed laser deposition (PLD), to allow a detailed probe into the structure evolution and optical band gap modulation of SnO2 with growing thickness. All films exhibit excellent out-of-plane ordering (lowest (200) rocking-curve half width ∼0.01°) with an orientation of SnO2(100) || Al2O3(0001), while three equivalent domains that are rotated by 120° with one another coexist in-plane with SnO2[010] || Al2O3 [11-20]. Initially the SnO2(100) film assumes a two-dimensional (2D) layer-by-layer growth mode with atomically smooth surface (minimum root-mean-square roughness of 0.183 nm), and endures compressive strain along both c and a axes as well as mild tensile strain along the b-axis. With increasing thickness, transition from the 2D to 3D island growth mode takes place, leading to formation of various defects to allow relief of the stress and thus relaxation of the film towards bulk SnO2. More interestingly, with increasing thickness from nm to μm, the SnO2 films present a non-monotonic V-shaped variation in the optical band gap energy. While the band gap of SnO2 films thinner than 6.1 nm increases rapidly with decreasing film thickness due to the quantum size effect, the band gap of thicker SnO2 films broadens almost linearly with increasing film thickness up to 374 nm, as a result of the strain effect. The present work sheds light on future design of SnO2 films with desired band gap for particular applications by thickness control and strain engineering.

Observations of Large-Amplitude, Whistler-Mode Wave Ducts in the Outer Plasmasphere

DTIC Science & Technology

1990-02-12

evidence for whistler ducts [Smith and Angerami , 1968]. They showed that the spectral shape (dispersion) of whistlers arising from lightning strokes...the equatorial separation of the ducts near L z 3 ranged from 50 to 500 km and that the equatorial thicknesses were about 400 km. Angerami [1970...reported [Smith and Angerami , 1968; Angerami , 1970; Scarf and Chappell, 1973; Carpenter et al., 1981]. The half- width of the ducts and the density

Atmospheric pressure scanning transmission electron microscopy.

PubMed

de Jonge, Niels; Bigelow, Wilbur C; Veith, Gabriel M

2010-03-10

Scanning transmission electron microscope (STEM) images of gold nanoparticles at atmospheric pressure have been recorded through a 0.36 mm thick mixture of CO, O2, and He. This was accomplished using a reaction cell consisting of two electron-transparent silicon nitride membranes. Gold nanoparticles of a full width at half-maximum diameter of 1.0 nm were visible above the background noise, and the achieved edge resolution was 0.4 nm in accordance with calculations of the beam broadening.

Split rheometer Couette attachment to enable sample extraction

NASA Astrophysics Data System (ADS)

Guthrie, Sarah E.; Idziak, Stefan H. J.

2005-02-01

We report on the development of a Couette attachment insert for a rheometer, which is designed to split in half, enabling intact sample extraction of cocoa butter crystallized from the melt under known dynamic stress conditions. This cell is capable of producing a sample 1mm thick. At shear rates of 90-720s-1 and final temperatures of 18-20°C it was shown that the sample will completely separate from the cell surface intact.

On the evolution of antiferromagnetic nanodomains in NiO thin films: A LEEM study

NASA Astrophysics Data System (ADS)

Das, Jayanta; Menon, Krishnakumar S. R.

2018-03-01

Fractional order (1/2, 0) spots appear in the electron diffraction from NiO/Ag(0 0 1) films due to exchange scattering of low energy electrons by the antiferromagnetically ordered surface Ni moments. Utilizing these beams, imaging of the nanosized surface magnetic domains were carried out employing the high spatial resolution (∼ 10 nm) of the Low Energy Electron Microscopy (LEEM) in the dark-field (DF) mode. While selected through a contrast aperture, the four magnetic reflections produced by the p (2 × 2) antiferromagnetic sub-lattice lead to the visualization of the different magnetic twin domains. The intensity variations of different twin domains were measured as a function of electron beam energies via domain resolved LEEM I-V plots. The surface Néel temperatures (TN) of the films were measured using the temperature dependence of these half-order spot intensities. Detailed morphological studies of the size and shape of these nanodomains and their evolution as a function of the film thickness have been carried out with the help of pair-correlation function and fractal analysis. The size, shape and distribution of these magnetic domains are modified significantly by the strain relaxation mechanism beyond the critical film thickness. A method to estimate the relative domain sizes from a quantitative measure of the half-order spot intensities is manifested well below TN .

Visual detection of particulates in processed meat products by x ray

NASA Astrophysics Data System (ADS)

Schatzki, Thomas F.; Young, Richard; Haff, Ron P.; Eye, J.; Wright, G.

1995-01-01

A test has been run to study the efficacy of detecting particulate contaminants in processed meat samples by manual observation of line-scanned x-ray images. Six hundred processed product samples arriving over a 3 month period at a national USDA-FSIS laboratory were scanned at 230 cm2sec with 0.5 X 0.5 mm resolution, using 50 KV, 13 ma excitation, with digital interfacing and image correction. Images were inspected off-line, using interactive image enhancement. Forty percent of the samples were spiked, blind to the analyst, in order to establish the manual recognition rate as a function of sample thickness [1 - 10 cm] and texture of the x-ray image [smooth/textured], as well as spike composition [wood/bone/glass], size [1 - 4 mm] and shape [splinter/round]. The results have been analyzed using maximum likelihood logistic regression. In meat packages less than 6 cm thick, 2 mm bone chips are easily recognized, 1 mm glass splinters with some difficulty, while wood is generally missed even at 4 mm. Operational feasibility in a time-constrained setting has bee confirmed. One half percent of the samples arriving from the field contained bone slivers > 1 cm long, one half percent contained metallic material, while 4% contained particulates exceeding 3.2 mm in size. All of the latter appeared to be bone fragments.

CMUTs with High-K Atomic Layer Deposition Dielectric Material Insulation Layer

PubMed Central

Xu, Toby; Tekes, Coskun; Degertekin, F. Levent

2014-01-01

Use of high-κ dielectric, atomic layer deposition (ALD) materials as an insulation layer material for capacitive micromachined ultrasonic transducers (CMUTs) is investigated. The effect of insulation layer material and thickness on CMUT performance is evaluated using a simple parallel plate model. The model shows that both high dielectric constant and the electrical breakdown strength are important for the dielectric material, and significant performance improvement can be achieved, especially as the vacuum gap thickness is reduced. In particular, ALD hafnium oxide (HfO2) is evaluated and used as an improvement over plasma-enhanced chemical vapor deposition (PECVD) silicon nitride (SixNy) for CMUTs fabricated by a low-temperature, complementary metal oxide semiconductor transistor-compatible, sacrificial release method. Relevant properties of ALD HfO2 such as dielectric constant and breakdown strength are characterized to further guide CMUT design. Experiments are performed on parallel fabricated test CMUTs with 50-nm gap and 16.5-MHz center frequency to measure and compare pressure output and receive sensitivity for 200-nm PECVD SixNy and 100-nm HfO2 insulation layers. Results for this particular design show a 6-dB improvement in receiver output with the collapse voltage reduced by one-half; while in transmit mode, half the input voltage is needed to achieve the same maximum output pressure. PMID:25474786

Shape of wear particles found in human knee joints and their relationship to osteoarthritis.

PubMed

Kuster, M S; Podsiadlo, P; Stachowiak, G W

1998-09-01

To analyse and compare the shape of wear particles found in healthy and osteoarthritic human knee joints for monitoring the progress of osteoarthritis, the long-term prognosis and to evaluate therapeutic regimens. Joint particles from seven patients with normal cartilage in all compartments of the knee joint, 12 patients with fibrillation of less than half the cartilage thickness (grade 1), seven patients with fibrillation of more than half the cartilage thickness (grade 2) and four patients with erosions down to bone (grade 3) were analysed. A total of 565 particles were extracted from synovial fluid samples by ferrography and analysed in a scanning electron microscope. A number of numerical descriptors, i.e. boundary fractal dimension, shape factor, convexity and elongation, were calculated for each particle image and correlated to the degree of osteoarthritis using non-parametric tests. Experiments demonstrated that there were significant differences between the numerical descriptors calculated for wear particles from healthy and osteoarthritic knee joints (P < 0.01), suggesting that the particle shape can be used as an indicator of the joint condition. In particular, the fractal dimension of the particle boundary was shown to correlate directly with the degree of osteoarthritis. Numerical analysis of the shape of wear particles found in human knee joints may provide a reliable means for the assessment of cartilage repair after surgical or conservative treatment of osteoarthritis.

Towards Standardization of X-ray Beam Filters in Digital Mammography and Digital Breast Tomosynthesis: Monte Carlo simulations and analytical modelling

PubMed Central

Shrestha, Suman; Vedantham, Srinivasan; Karellas, Andrew

2017-01-01

In digital breast tomosynthesis and digital mammography, the x-ray beam filter material and thickness vary between systems. Replacing K-edge filters with Al was investigated with the intent to reduce exposure duration and to simplify system design. Tungsten target x-ray spectra were simulated with K-edge filters (50μm Rh; 50μm Ag) and Al filters of varying thickness. Monte Carlo simulations were conducted to quantify the x-ray scatter from various filters alone, scatter-to-primary ratio (SPR) with compressed breasts, and to determine the radiation dose to the breast. These data were used to analytically compute the signal-difference-to-noise ratio (SDNR) at unit (1 mGy) mean glandular dose (MGD) for W/Rh and W/Ag spectra. At SDNR matched between K-edge and Al filtered spectra, the reductions in exposure duration and MGD were quantified for three strategies: (i) fixed Al thickness and matched tube potential in kilovolts (kV); (ii) fixed Al thickness and varying the kV to match the half-value layer (HVL) between Al and K-edge filtered spectra; and, (iii) matched kV and varying the Al thickness to match the HVL between Al and K-edge filtered spectra. Monte Carlo simulations indicate that the SPR with and without the breast were not different between Al and K-edge filters. Modelling for fixed Al thickness (700μm) and kV matched to K-edge filtered spectra, identical SDNR was achieved with 37–57% reduction in exposure duration and with 2–20% reduction in MGD, depending on breast thickness. Modelling for fixed Al thickness (700μm) and HVL matched by increasing the kV over [0,4] range, identical SDNR was achieved with 62–65% decrease in exposure duration and with 2–24% reduction in MGD, depending on breast thickness. For kV and HVL matched to K-edge filtered spectra by varying Al filter thickness over [700,880]μm range, identical SDNR was achieved with 23–56% reduction in exposure duration and 2–20% reduction in MGD, depending on breast thickness. These simulations indicate that increased fluence with Al filter of fixed or variable thickness substantially decreases exposure duration while providing for similar image quality with moderate reduction in MGD. PMID:28075335

Gravitational instability of thin gas layer between two thick liquid layers

NASA Astrophysics Data System (ADS)

Pimenova, A. V.; Goldobin, D. S.

2016-12-01

We consider the problem of gravitational instability (Rayleigh-Taylor instability) of a horizontal thin gas layer between two liquid half-spaces (or thick layers), where the light liquid overlies the heavy one. This study is motivated by the phenomenon of boiling at the surface of direct contact between two immiscible liquids, where the rate of the "break-away" of the vapor layer growing at the contact interface due to development of the Rayleigh-Taylor instability on the upper liquid-gas interface is of interest. The problem is solved analytically under the assumptions of inviscid liquids and viscous weightless vapor. These assumptions correspond well to the processes in real systems, e.g., they are relevant for the case of interfacial boiling in the system water- n-heptane. In order to verify the results, the limiting cases of infinitely thin and infinitely thick gas layers were considered, for which the results can be obviously deduced from the classical problem of the Rayleigh-Taylor instability. These limiting cases are completely identical to the well-studied cases of gravity waves at the liquidliquid and liquid-gas interfaces. When the horizontal extent of the system is long enough, the wavenumber of perturbations is not limited from below, and the system is always unstable. The wavelength of the most dangerous perturbations and the rate of their exponential growth are derived as a function of the layer thickness. The dependence of the exponential growth rate on the gas layer thickness is cubic.

Magnetic resonance imaging of placenta accreta

PubMed Central

Varghese, Binoj; Singh, Navdeep; George, Regi A.N; Gilvaz, Sareena

2013-01-01

Placenta accreta (PA) is a severe pregnancy complication which occurs when the chorionic villi (CV) invade the myometrium abnormally. Optimal management requires accurate prenatal diagnosis. Ultrasonography (USG) and magnetic resonance imaging (MRI) are the modalities for prenatal diagnosis of PA, although USG remains the primary investigation of choice. MRI is a complementary technique and reserved for further characterization when USG is inconclusive or incomplete. Breath-hold T2-weighted half-Fourier rapid acquisition with relaxation enhancement (RARE) and balanced steady-state free precession imaging in the three orthogonal planes is the key MRI technique. Markedly heterogeneous placenta, thick intraplacental dark bands on half-Fourier acquisition single-shot turbo spin-echo (HASTE), and disorganized abnormal intraplacental vascularity are the cardinal MRI features of PA. MRI is less reliable in differentiating between different degrees of placental invasion, especially between accreta vera and increta. PMID:24604945

DFT investigations of the hydrogenation effect on silicene/graphene hybrids.

PubMed

Drissi, L B; Saidi, E H; Bousmina, M; Fassi-Fehri, O

2012-12-05

We report here a study on the effect of hydrogenation on a new one-atom thick material made of silicon and carbon atoms (silicene/graphene (SG) hybrid) within density functional theory. The structural, electronic and magnetic properties are investigated for non-, semi- and fully hydrogenated SG hybrids in a chair configuration and are compared with their parent materials. Calculations reveal that pure SG is a non-zero band gap semi-conductor with stable planar honeycomb structure. So mixing C and Si in an alternating manner gives another way to generate a finite band gap in one-atom thick materials. Fully hydrogenation makes the gap larger; however half chemical modification with H reduces the gap in favor of ferromagnetism order. The findings of this work open a wide spectrum of possibilities for designing SG-based nanodevices with controlled and tuned properties.

Opto-Mechanics of the Constellation-X SXT Mirrors: Challenges in Mounting and Assembling the Mirror Segments

NASA Technical Reports Server (NTRS)

Chan, Kai-Wing; Zhang, WIlliam W.; Saha, Timo; Lehan, John P.; Mazzarella, James; Lozipone, Lawrence; Hong, Melinda; Byron, Glenn

2008-01-01

The Constellation-X Spectroscopy X-Ray Telescopes consists of segmented glass mirrors with an axial length of 200 mm, a width of up to 400 mm, and a thickness of 0.4 mm. To meet the requirement of less than 15 arc-second half-power diameter with the small thickness and relatively large size is a tremendous challenge in opto-mechanics. How shall we limit distortion of the mirrors due to gravity in ground tests, that arises from thermal stress, and that occurs in the process of mounting, affixing and assembling of these mirrors? In this paper, we will describe our current opto-mechanical approach to these problems. We will discuss, in particular, the approach and experiment where the mirrors are mounted vertically by first suspending it at two points.

Role of “Hard” and “Soft” Confinement on Polymer Dynamics at the Nanoscale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Ravi P.; Green, Peter F.

2017-08-11

We investigated the segmental dynamics of asymmetrically confined polymer films and report an unusual phenomenon in which the presence and thickness of a soft confining layer are responsible for significant changes in the segmental dynamics of the confined films. Specifically, the segmental dynamics of poly(vinyl alcohol) (PVA) thin films asymmetrically confined between hard aluminum (Al), and soft polystyrene (PS) films are shown to shift by as much as half an order of magnitude upon changes in the thicknesses of the confining PS layer. These effects are more significant than those due to symmetric confinement between hard Al substrates or exposuremore » to a free surface. These observations, partially rationalized in terms of recent simulations and theory, implicate the role of the moduli of the confining layers.« less

Novel high-performance scattering materials for use in energy-saving light fittings and skylights based on polymer pigmented with polymer

NASA Astrophysics Data System (ADS)

Smith, Geoffrey B.; Earp, Alan; Franklin, Jim B.; McCredie, Geoffrey

2001-11-01

Simple quantitative performance criteria are developed for translucent materials in terms of hemispherical visible transmittance, and angular spread of transmitted luminance using a half angle. Criteria are linked to applications in luminaires and skylights with emphasis on maximising visible throughput while minimising glare. These basic criteria are also extended to angle of incidence changes which are substantial. Example data is provided showing that acrylic pigmented with spherical polymer particles can have total hemispherical transmittance with weak thickness dependence, which is better than clear sheet, while the spread of transmitted light is quite thickness-sensitive and occurs over wider angles than inorganic pigments. This combination means significantly fewer lamps can achieve specified lux levels with low glare, and smaller skylights can provide higher, more uniform daylight illuminance.

Direct Growth of CdTe on a (211) Si Substrate with Vapor Phase Epitaxy Using a Metallic Cd Source

NASA Astrophysics Data System (ADS)

Iso, Kenji; Gokudan, Yuya; Shiraishi, Masumi; Murakami, Hisashi; Koukitu, Akinori

2017-10-01

We successfully performed epitaxial CdTe growth on a Si (211) substrate with vapor-phase epitaxy using a cost-effective metallic cadmium source as a group-II precursor. The thermodynamic data demonstrate that the combination of metallic Cd and diisopropyl-telluride (DiPTe) with a H2 carrier gas enables the growth of CdTe crystals. A CdTe single crystal with a (422) surface orientation was obtained when a growth temperature between 600°C and 650°C was employed. The surface morphology and crystalline quality were improved with increasing film thickness. The full-width at half-maximum of the x-ray rocking curves with a film thickness of 15.7 μm for the skew-symmetrical (422) and asymmetrical (111) reflection were 528 arcsec and 615 arcsec, respectively.

Detecting grouting quality of tendon ducts using the impact-echo method

NASA Astrophysics Data System (ADS)

Qu, Guangzhen; Sun, Min; Zhou, Guangli

2018-06-01

The performance, durability and safety of prestressed concrete bridge were directly affected by the compaction of prestressed pipe. However, the pipe was hidden in the beam, and its grouting density was difficult to detect. The paper had modified three different status of gouting quality through making test model. After that, the impact-Echo method was adopted to detect the grouting quality of tendon ducts, the study was sunmmarized as follow. If the reflect time of slab bottom and nominal thickness of slab increased, the degree of density will increase; testing from half-hole of web, the reflect time and nominal thickness of slab was biggest. At the same time, the reflect time of compacted and uncompacted tendon ducts were mainly. At last, the method was verified by the engineering project, which provided reference value.

Barium Titanate Photonic Crystal Electro-Optic Modulators for Telecommunication and Data Network Applications

NASA Astrophysics Data System (ADS)

Girouard, Peter D.

The microwave, optical, and electro-optic properties of epitaxial barium titanate thin films grown on (100) MgO substrates and photonic crystal electro-optic modulators fabricated on these films were investigated to demonstrate the applicability of these devices for telecommunication and data networks. The electrical and electro-optical properties were characterized up to modulation frequencies of 50 GHz, and the optical properties of photonic crystal waveguides were determined for wavelengths spanning the optical C band between 1500 and 1580 nm. Microwave scattering parameters were measured on coplanar stripline devices with electrode gap spacings between 5 and 12 mum on barium titanate films with thicknesses between 230 and 680 nm. The microwave index and device characteristic impedance were obtained from the measurements. Larger (lower) microwave indices (impedances) were obtained for devices with narrower electrode gap spacings and on thicker films. Thinner film devices have both lower index mismatch between the co-propagating microwave and optical signals and lower impedance mismatch to a 50O system, resulting in a larger predicted electro-optical 3 dB bandwidth. This was experimentally verified with electro-optical frequency response measurements. These observations were applied to demonstrate a record high 28 GHz electro-optic bandwidth measured for a BaTiO3 conventional ridge waveguide modulator having 1mm long electrodes and 12 mum gap spacing on a 260nm thick film. The half-wave voltage and electro-optic coefficients of barium titanate modulators were measured for films having thicknesses between 260 and 500 nm. The half-wave voltage was directly measured at low frequencies using a polarizer-sample-compensator-analyzer setup by over-driving waveguide integrated modulators beyond their linear response regime. Effective in-device electro-optic coefficients were obtained from the measured half-wave voltages. The effective electro-optic coefficients were found to increase with both applied electrical dc bias and with film thickness. A record low 0.39V ˙ cm (0.45V ˙ cm) voltage-length product was measured for barium titanate modulators operating at telecommunication wavelengths on a device with 5 ?m electrode gap spacing on a 500nm thick film modulated at a frequency of 100 Hz (1 MHz). This measured voltage-length product is more than a factor of 5 lower than that reported for state-of-the-art silicon conventional waveguide modulators. The electro-optical characterization of BaTiO3 films revealed a trade-off that exists for traveling wave BaTiO3 modulators: lower voltages are obtained in thicker film devices with narrow electrode gap spacing while larger bandwidths are obtained in thinner film devices with wider electrode gap spacing. These findings were supported by calculations of the film thickness dependent half-wave voltage and electro-optic bandwidth. In order to demonstrate modulators having simultaneously low voltage operation and high electro-optic bandwidth, photonic crystal waveguide modulators with large group index were investigated through theory and experiment. The theory for slow light phase delay in linear optical materials was extended for second order nonlinear optical materials. This theory was incorporated into a detailed model for predicting photonic crystal modulator performance in terms of voltage-length product and electro-optic bandwidth. Modeling shows that barium titanate photonic crystal modulators with sub-millimeter length, sub-volt operation, and greater than 40 GHz electro-optic bandwidth are achievable in a single device. Two types of photonic crystal waveguides (PC) on BaTiO3 films were designed, fabricated, and characterized: waveguides with hexagonal lattice symmetry and waveguides with hexagonal symmetry having a line defect oriented in the direction of light propagation. Excellent agreement was obtained between the simulated and measured transmission for hexagonal lattice PC waveguides. An extinction of 20 dB was measured across a 9.9 nm stop band edge, yielding a record large band edge sharpness of 2 dB/nm for all photonic crystal waveguides on ferroelectric films. A 12-fold enhancement of the electro-optic coefficient was measured via optical spectral analysis in a line defect BaTiO3 modulator, yielding an effective electro-optic coefficient of 900 pm/V in the photonic crystal region at a modulation frequency of 10 GHz. This enhancement was demonstrated over a 48 nm range, demonstrating the wideband operation of these devices.

Angular multiplexing holograms of four images recorded on photopolymer films with recording-film-thickness-dependent holographic characteristics

NASA Astrophysics Data System (ADS)

Osabe, Keiichi; Kawai, Kotaro

2017-03-01

In this study, angular multiplexing hologram recording photopolymer films were studied experimentally. The films contained acrylamide as a monomer, eosin Y as a sensitizer, and triethanolamine as a promoter in a polyvinyl alcohol matrix. In order to determine the appropriate thickness of the photopolymer films for angular multiplexing, photopolymer films with thicknesses of 29-503 μm were exposed to two intersecting beams of a YVO laser at a wavelength of 532 nm to form a holographic grating with a spatial frequency of 653 line/mm. The diffraction efficiencies as a function of the incident angle of reconstruction were measured. A narrow angular bandwidth and high diffraction efficiency are required for angular multiplexing; hence, we define the Q value, which is the diffraction efficiency divided by half the bandwidth. The Q value of the films depended on the thickness of the films, and was calculated based on the measured diffraction efficiencies. The Q value of a 297-μm-thick film was the highest of the all films. Therefore, the angular multiplexing experiments were conducted using 300-μm-thick films. In the angular multiplexing experiments, the object beam transmitted by a square aperture was focused by a Fourier transform lens and interfered with a reference beam. The maximum order of angular multiplexing was four. The signal intensity that corresponds to the squared-aperture transmission and the noise intensity that corresponds to transmission without the square aperture were measured. The signal intensities decreased as the order of angular multiplexing increased, and the noise intensities were not dependent on the order of angular multiplexing.

Crustal structure and kinematics of the TAMMAR propagating rift system on the Mid-Atlantic Ridge from seismic refraction and satellite altimetry gravity

NASA Astrophysics Data System (ADS)

Kahle, Richard L.; Tilmann, Frederik; Grevemeyer, Ingo

2016-08-01

The TAMMAR segment of the Mid-Atlantic Ridge forms a classic propagating system centred about two degrees south of the Kane Fracture Zone. The segment is propagating to the south at a rate of 14 mm yr-1, 15 per cent faster than the half-spreading rate. Here, we use seismic refraction data across the propagating rift, sheared zone and failed rift to investigate the crustal structure of the system. Inversion of the seismic data agrees remarkably well with crustal thicknesses determined from gravity modelling. We show that the crust is thickened beneath the highly magmatic propagating rift, reaching a maximum thickness of almost 8 km along the seismic line and an inferred (from gravity) thickness of about 9 km at its centre. In contrast, the crust in the sheared zone is mostly 4.5-6.5 km thick, averaging over 1 km thinner than normal oceanic crust, and reaching a minimum thickness of only 3.5 km in its NW corner. Along the seismic line, it reaches a minimum thickness of under 5 km. The PmP reflection beneath the sheared zone and failed rift is very weak or absent, suggesting serpentinisation beneath the Moho, and thus effective transport of water through the sheared zone crust. We ascribe this increased porosity in the sheared zone to extensive fracturing and faulting during deformation. We show that a bookshelf-faulting kinematic model predicts significantly more crustal thinning than is observed, suggesting that an additional mechanism of deformation is required. We therefore propose that deformation is partitioned between bookshelf faulting and simple shear, with no more than 60 per cent taken up by bookshelf faulting.

Parsing parallel evolution: ecological divergence and differential gene expression in the adaptive radiations of thick-lipped Midas cichlid fishes from Nicaragua.

PubMed

Manousaki, Tereza; Hull, Pincelli M; Kusche, Henrik; Machado-Schiaffino, Gonzalo; Franchini, Paolo; Harrod, Chris; Elmer, Kathryn R; Meyer, Axel

2013-02-01

The study of parallel evolution facilitates the discovery of common rules of diversification. Here, we examine the repeated evolution of thick lips in Midas cichlid fishes (the Amphilophus citrinellus species complex)-from two Great Lakes and two crater lakes in Nicaragua-to assess whether similar changes in ecology, phenotypic trophic traits and gene expression accompany parallel trait evolution. Using next-generation sequencing technology, we characterize transcriptome-wide differential gene expression in the lips of wild-caught sympatric thick- and thin-lipped cichlids from all four instances of repeated thick-lip evolution. Six genes (apolipoprotein D, myelin-associated glycoprotein precursor, four-and-a-half LIM domain protein 2, calpain-9, GTPase IMAP family member 8-like and one hypothetical protein) are significantly underexpressed in the thick-lipped morph across all four lakes. However, other aspects of lips' gene expression in sympatric morphs differ in a lake-specific pattern, including the magnitude of differentially expressed genes (97-510). Generally, fewer genes are differentially expressed among morphs in the younger crater lakes than in those from the older Great Lakes. Body shape, lower pharyngeal jaw size and shape, and stable isotopes (δ(13)C and δ(15)N) differ between all sympatric morphs, with the greatest differentiation in the Great Lake Nicaragua. Some ecological traits evolve in parallel (those related to foraging ecology; e.g. lip size, body and head shape) but others, somewhat surprisingly, do not (those related to diet and food processing; e.g. jaw size and shape, stable isotopes). Taken together, this case of parallelism among thick- and thin-lipped cichlids shows a mosaic pattern of parallel and nonparallel evolution. © 2012 Blackwell Publishing Ltd.

Low temperature aluminum nitride thin films for sensory applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yarar, E.; Zamponi, C.; Piorra, A.

2016-07-15

A low-temperature sputter deposition process for the synthesis of aluminum nitride (AlN) thin films that is attractive for applications with a limited temperature budget is presented. Influence of the reactive gas concentration, plasma treatment of the nucleation surface and film thickness on the microstructural, piezoelectric and dielectric properties of AlN is investigated. An improved crystal quality with respect to the increased film thickness was observed; where full width at half maximum (FWHM) of the AlN films decreased from 2.88 ± 0.16° down to 1.25 ± 0.07° and the effective longitudinal piezoelectric coefficient (d{sub 33,f}) increased from 2.30 ± 0.32 pm/Vmore » up to 5.57 ± 0.34 pm/V for film thicknesses in the range of 30 nm to 2 μm. Dielectric loss angle (tan δ) decreased from 0.626% ± 0.005% to 0.025% ± 0.011% for the same thickness range. The average relative permittivity (ε{sub r}) was calculated as 10.4 ± 0.05. An almost constant transversal piezoelectric coefficient (|e{sub 31,f}|) of 1.39 ± 0.01 C/m{sup 2} was measured for samples in the range of 0.5 μm to 2 μm. Transmission electron microscopy (TEM) investigations performed on thin (100 nm) and thick (1.6 μm) films revealed an (002) oriented AlN nucleation and growth starting directly from the AlN-Pt interface independent of the film thickness and exhibit comparable quality with the state-of-the-art AlN thin films sputtered at much higher substrate temperatures.« less

Regional TEMPEST survey in north-east Namibia

NASA Astrophysics Data System (ADS)

Peters, Geoffrey; Street, Gregory; Kahimise, Ivor; Hutchins, David

2015-09-01

A regional scale TEMPEST208 airborne electromagnetic survey was flown in north-east Namibia in 2011. With broad line spacing (4 km) and a relatively low-powered, fixed-wing system, the approach was intended to provide a regional geo-electric map of the area, rather than direct detection of potential mineral deposits. A key component of the geo-electric profiling was to map the relative thickness of the Kalahari sediments, which is up to 200 m thick and obscures most of the bedrock in the area. Knowledge of the thickness would allow explorers to better predict the costs of exploration under the Kalahari. An additional aim was to determine if bedrock conductors were detectable beneath the Kalahari cover. The system succeeded in measuring the Kalahari thickness where this cover was relatively thin and moderately conductive. Limitations in depth penetration mean that it is not possible to map the thickness in the centre of the survey area, and much of the northern half of the survey area. Additional problems arise due to the variable conductivity of the Kalahari cover. Where the conductivity of the Kalahari sediment is close to that of the basement, there is no discernable contrast to delineate the base of the Kalahari. Basement conductors are visible beneath the more thinly covered areas such as in the north-west and south of the survey area. The remainder of the survey area generally comprises deeper, more conductive cover and for the most part basement conductors cannot be detected. A qualitative comparison with VTEM data shows comparable results in terms of regional mapping, and suggests that even more powerful systems such as the VTEM may not detect discrete conductors beneath the thick conductive parts of the Kalahari cover.

The Role of the Plasma during Laser-Gas Laser-Metal Interactions.

DTIC Science & Technology

1986-10-13

argument will be treated in Chap. 5. It 50 Ushlo and Matsuda [421 assessed the target transport in an argon TIG welding assembly. The TIG process involves...i 3 1. LITERATURE SURVEY 1.1 Introduction The most widespread commercial use of the laser is in cutting, welding , drilling, and heat treatment. Many...targets was presented by Locke, et al. [1]. The authors were concerned with the non-uniform penetration depths in laser welding . Half inch thick 304

Echo's Legacy

NASA Technical Reports Server (NTRS)

1980-01-01

The Echo 1 Satellite is simply a very large balloon, the diameter of a 10 story building. Metallized Products, Inc. developed a special material for NASA used for the balloons's skin. For "bouncing signals," material had to be reflective, lightweight, and thin enough to be folded into a beach ball size canister for delivery into orbit, where it would automatically inflate. Material selected was mylar polyester, with a reflective layer of tiny aluminum particles so fine that Echo's skin had a thickness half that of cellophane on a cigarette package.

Analysis of stresses at the bore of a drilled ball operating in a high-speed bearing. [with stiffening web

NASA Technical Reports Server (NTRS)

Coe, H. H.; Lynch, J. E.

1973-01-01

Three-dimensional stress distributions were calculated for both a regular drilled ball with a stiffening web. The balls were 20.6 mm (0.8125 in.) in diameter and had a 12.6 mm (0.496 in.) diameter concentric hole. The stiffening web was 1.5 mm (0.06 in.) thick. The calculations showed that a large reversing tangential stress at the hole bore was reduced by one-half by the addition of the web.

The Coast Artillery Journal. Volume 75, Number 2, March-April 1932

DTIC Science & Technology

1932-04-01

after three years’ study of the Japanese language-study which has re- sulted not in my gaining easy fluency in the language of the Samurai but in...eight and a half feet thick, using 850 pounds of cement to ite cubic yard. In standard European fortifications the proportion of cement to the cubic yard...withthe mechanized"support," i.e., mortar companies, mechanizedand M. G. Cosoand first-line transport. Corps artillery, engineers, armored cars of the R

Second harmonic generation in resonant optical structures

DOEpatents

Eichenfield, Matt; Moore, Jeremy; Friedmann, Thomas A.; Olsson, Roy H.; Wiwi, Michael; Padilla, Camille; Douglas, James Kenneth; Hattar, Khalid Mikhiel

2018-01-09

An optical second-harmonic generator (or spontaneous parametric down-converter) includes a microresonator formed of a nonlinear optical medium. The microresonator supports at least two modes that can be phase matched at different frequencies so that light can be converted between them: A first resonant mode having substantially radial polarization and a second resonant mode having substantially vertical polarization. The first and second modes have the same radial order. The thickness of the nonlinear medium is less than one-half the pump wavelength within the medium.

The influence of pore-fluid in the soil on ground vibrations from a tunnel embedded in a layered half-space

NASA Astrophysics Data System (ADS)

Yuan, Zonghao; Cao, Zhigang; Boström, Anders; Cai, Yuanqiang

2018-04-01

A computationally efficient semi-analytical solution for ground-borne vibrations from underground railways is proposed and used to investigate the influence of hydraulic boundary conditions at the scattering surfaces and the moving ground water table on ground vibrations. The arrangement of a dry soil layer with varying thickness resting on a saturated poroelastic half-space, which includes a circular tunnel subject to a harmonic load at the tunnel invert, creates the scenario of a moving water table for research purposes in this paper. The tunnel is modelled as a hollow cylinder, which is made of viscoelastic material and buried in the half-space below the ground water table. The wave field in the dry soil layer consists of up-going and down-going waves while the wave field in the tunnel wall consists of outgoing and regular cylindrical waves. The complete solution for the saturated half-space with a cylindrical hole is composed of down-going plane waves and outgoing cylindrical waves. By adopting traction-free boundary conditions on the ground surface and continuity conditions at the interfaces of the two soil layers and of the tunnel and the surrounding soil, a set of algebraic equations can be obtained and solved in the transformed domain. Numerical results show that the moving ground water table can cause an uncertainty of up to 20 dB for surface vibrations.

Metal artifact reduction by filter-based dual-energy cone-beam computed tomography on a bench-top micro-CBCT system: concept and demonstration.

PubMed

Iramina, Hiraku; Hamaguchi, Takumi; Nakamura, Mitsuhiro; Mizowaki, Takashi; Kanno, Ikuo

2018-04-30

We evaluated two dual-energy cone-beam computed tomography (DE-CBCT) methodologies for a bench-top micro-CBCT system to reduce metal artifacts on reconstructed images. Two filter-based DE-CBCT methodologies were tested: (i) alternative spectral switching and (ii) simultaneous beam splitting. We employed filters of 0.6-mm-thick tin and 0.1-mm-thick tungsten to generate high- and low-energy spectra from 120 kVp X-rays, respectively. The spectral switching method was imitated by two half scans with different filters (pseudo-switching). Filters were placed and between the X-ray tube and a phantom ('1-u,' '2-u'), a phantom and a flat panel detector ('1-d,' '2-d'), and compared with (iii) two half scans at 80 and 140 kVp [pseudo-(80,140)]. For the splitting method, two half-width filters were aligned along a rotating axis. Projections were separated into halves and merged with corresponding areas of opposed projections after one full rotation. A solid 30-mm-diameter acrylic phantom and an acrylic phantom with four 5-mm-diameter titanium rods were used. DE images were generated by weighted summation of the high- and low-energy images. The blending factor was changed from 0 to +5 in increments of 0.01. Relative errors (REs) of the linear attenuation coefficients of the two phantoms and the contrast-to-noise ratios (CNRs) between the titanium and acrylic regions were compared. All methods showed zero REs except for the method (2-d). CNRs for pseudo-switching with upstream placement were 1.4-fold larger than CNRs for the pseudo-(80,140) method. CNRs for the downstream placements were small. It was concluded that the pseudo-switching method with upstream placement is appropriate for reducing metal artifacts.

Anatomical features of pepper plants (Capsicum annuum L.) grown under red light-emitting diodes supplemented with blue or far-red light

NASA Technical Reports Server (NTRS)

Schuerger, A. C.; Brown, C. S.; Stryjewski, E. C.

1997-01-01

Pepper plants (Capsicum annuum L. cv., Hungarian Wax) were grown under metal halide (MH) lamps or light-emitting diode (LED) arrays with different spectra to determine the effects of light quality on plant anatomy of leaves and stems. One LED (660) array supplied 90% red light at 660 nm (25nm band-width at half-peak height) and 1% far-red light between 700-800nm. A second LED (660/735) array supplied 83% red light at 660nm and 17% far-red light at 735nm (25nm band-width at half-peak height). A third LED (660/blue) array supplied 98% red light at 660nm, 1% blue light between 350-550nm, and 1% far-red light between 700-800nm. Control plants were grown under broad spectrum metal halide lamps. Plants were gron at a mean photon flux (300-800nm) of 330 micromol m-2 s-1 under a 12 h day-night photoperiod. Significant anatomical changes in stem and leaf morphologies were observed in plants grown under the LED arrays compared to plants grown under the broad-spectrum MH lamp. Cross-sectional areas of pepper stems, thickness of secondary xylem, numbers of intraxylary phloem bundles in the periphery of stem pith tissues, leaf thickness, numbers of choloplasts per palisade mesophyll cell, and thickness of palisade and spongy mesophyll tissues were greatest in peppers grown under MH lamps, intermediate in plants grown under the 660/blue LED array, and lowest in peppers grown under the 660 or 660/735 LED arrays. Most anatomical features of pepper stems and leaves were similar among plants grown under 660 or 660/735 LED arrays. The effects of spectral quality on anatomical changes in stem and leaf tissues of peppers generally correlate to the amount of blue light present in the primary light source.

Effect of Treadmill Exercise Timing on Repair of Full-Thickness Defects of Articular Cartilage by Bone-Derived Mesenchymal Stem Cells: An Experimental Investigation in Rats

PubMed Central

Li, Xue; Xu, Chang-peng; Cui, Zhuang; Jiang, Nan; Jia, Jun-jie; Yu, Bin

2014-01-01

Objective Current medical practice for the treatment of articular cartilage lesions remains a clinical challenge due to the limited self-repair ability of articular cartilage. Both experimental and clinical researches show that moderate exercise can improve articular cartilage repair process. However, optimal timing of moderate exercise is unclear. We aimed to evaluate the effect of timing of moderate treadmill exercise on repair of full-thickness defects of articular cartilage. Design Full-thickness cartilage defects were drilled in the patellar groove of bilateral femoral condyles in a total of 40 male SD rats before they were randomly assigned into four even groups. In sedentary control (SED) group, no exercise was given; in 2-week (2W), 4-week (4W) and 8-week groups, moderate treadmill exercise was initiated respectively two, four and eight weeks after operation. Half of the animals were sacrificed at week 10 after operation and half at week 14 after operation. Femoral condyles were harvested for gross observation and histochemical measurement by O'Driscoll scoring system. Collagen type II was detected by immunohistochemistry and mRNA expressions of aggrecan and collagen type II cartilage by RT-PCR. Results Both 10 and 14 weeks post-operation, the best results were observed in 4W group and the worst results appeared in 2W group. The histochemistry scores and the expressions of collagen type II and aggrecan were significantly higher in 4W group than that in other three groups (P<0.05). Conclusions Moderate exercise at a selected timing (approximately 4 weeks) after injury can significantly promote the healing of cartilage defects but may hamper the repair process if performed too early while delayed intervention by moderate exercise may reduce its benefits in repair of the defects. PMID:24595327

Anatomical features of pepper plants (Capsicum annuum L.) grown under red light-emitting diodes supplemented with blue or far-red light.

PubMed

Schuerger, A C; Brown, C S; Stryjewski, E C

1997-03-01

Pepper plants (Capsicum annuum L. cv., Hungarian Wax) were grown under metal halide (MH) lamps or light-emitting diode (LED) arrays with different spectra to determine the effects of light quality on plant anatomy of leaves and stems. One LED (660) array supplied 90% red light at 660 nm (25nm band-width at half-peak height) and 1% far-red light between 700-800nm. A second LED (660/735) array supplied 83% red light at 660nm and 17% far-red light at 735nm (25nm band-width at half-peak height). A third LED (660/blue) array supplied 98% red light at 660nm, 1% blue light between 350-550nm, and 1% far-red light between 700-800nm. Control plants were grown under broad spectrum metal halide lamps. Plants were gron at a mean photon flux (300-800nm) of 330 micromol m-2 s-1 under a 12 h day-night photoperiod. Significant anatomical changes in stem and leaf morphologies were observed in plants grown under the LED arrays compared to plants grown under the broad-spectrum MH lamp. Cross-sectional areas of pepper stems, thickness of secondary xylem, numbers of intraxylary phloem bundles in the periphery of stem pith tissues, leaf thickness, numbers of choloplasts per palisade mesophyll cell, and thickness of palisade and spongy mesophyll tissues were greatest in peppers grown under MH lamps, intermediate in plants grown under the 660/blue LED array, and lowest in peppers grown under the 660 or 660/735 LED arrays. Most anatomical features of pepper stems and leaves were similar among plants grown under 660 or 660/735 LED arrays. The effects of spectral quality on anatomical changes in stem and leaf tissues of peppers generally correlate to the amount of blue light present in the primary light source.

Comparison of Tissue Density in Hounsfield Units in Computed Tomography and Cone Beam Computed Tomography.

PubMed

Varshowsaz, Masoud; Goorang, Sepideh; Ehsani, Sara; Azizi, Zeynab; Rahimian, Sepideh

2016-03-01

Bone quality and quantity assessment is one of the most important steps in implant treatment planning. Different methods such as computed tomography (CT) and recently suggested cone beam computed tomography (CBCT) with lower radiation dose and less time and cost are used for bone density assessment. This in vitro study aimed to compare the tissue density values in Hounsfield units (HUs) in CBCT and CT scans of different tissue phantoms with two different thicknesses, two different image acquisition settings and in three locations in the phantoms. Four different tissue phantoms namely hard tissue, soft tissue, air and water were scanned by three different CBCT and a CT system in two thicknesses (full and half) and two image acquisition settings (high and low kVp and mA). The images were analyzed at three sites (middle, periphery and intermediate) using eFilm software. The difference in density values was analyzed by ANOVA and correction coefficient test (P<0.05). There was a significant difference between density values in CBCT and CT scans in most situations, and CBCT values were not similar to CT values in any of the phantoms in different thicknesses and acquisition parameters or the three different sites. The correction coefficients confirmed the results. CBCT is not reliable for tissue density assessment. The results were not affected by changes in thickness, acquisition parameters or locations.

Investigation of graphene-on-metal substrates for SPR-based sensor using finite-difference time domain.

PubMed

Said, Fairus Atida; Menon, Pulliyaseri Susthitha; Rajendran, Venkatachalam; Shaari, Sahbudin; Majlis, Burhanuddin Y

2017-12-01

In this study, the authors investigated the effects of a single layer graphene as a coating layer on top of metal thin films such as silver, gold, aluminum and copper using finite-difference time domain method. To enhance the resolution of surface plasmon resonance (SPR) sensor, it is necessary to increase the SPR reflectivity and decrease the full-width-half maximum (FWHM) of the SPR curve so that there is minimum uncertainty in the determination of the resonance dip. Numerical data was verified with analytical and experimental data where all the data were in good agreement with resonance angle differing in <10% due to noise present in components such as humidity and temperature. In further analysis, reflectivity and FWHM were compared among four types of metal with various thin film thicknesses where graphene was applied on top of the metal layers, and data was compared against pure conventional metal thin films. A 60 nm-thick Au thin film results in higher performance with reflectivity of 92.4% and FWHM of 0.88° whereas single layer graphene-on-60 nm-thick Au gave reflectivity of 91.7% and FWHM of 1.32°. However, a graphene-on-40 nm-thick Ag also gave good performance with narrower FWHM of 0.88° and reflection spectra of 89.2%.

Impact of nutrition education and medical supervision on pregnancy outcome.

PubMed

Sachdeva, R; Mann, S K

1993-11-01

Sixty Punjabi women from low and lower middle income groups were selected from eight villages of Ludhiana district. The supplements of iron, folic acid and calcium in the form of Folifer and Calcium Sandoz tablets were regularly supplied to experimental (E) group from second trimester onwards. A pamphlet about the diet during pregnancy was distributed to the E group along with four individual and three group contacts during the second half of pregnancy. The control (C) group was provided iron and folate supplements as per Government practice. Body height, weight, mid-upper arm circumference (MUA) and skinfold thickness of the subjects were recorded. Weight gained during pregnancy and post partum weight were also recorded and body mass index was calculated. In addition, crown heel length (CHL), birth weight (BW), skinfold thickness, MUA, head circumference (HC), Chest circumference (CC) and ponderal index (PI) of the neonates were recorded within eight hours of their birth. The gain in weight during pregnancy was 6.30 and 5.7 kg in E and C groups respectively. The study revealed that BW, CHL, skinfold thickness and PI of the newborns were significantly (p < 0.01) higher in E group. The mean BW of newborns in E and C groups was 2700 g and 2300 g, respectively. Weight gained during pregnancy had significant (p < 0.05) correlation to MUA, BW and skinfold thickness of the newborn.

Thick solid electrolyte interphases grown on silicon nanocone anodes during slow cycling and their negative effects on the performance of Li-ion batteries.

PubMed

Luo, Fei; Chu, Geng; Xia, Xiaoxiang; Liu, Bonan; Zheng, Jieyun; Li, Junjie; Li, Hong; Gu, Changzhi; Chen, Liquan

2015-05-07

Thickness, homogeneity and coverage of the surface passivation layer on Si anodes for Li-ion batteries have decisive influences on their cyclic performance and coulombic efficiency, but related information is difficult to obtain, especially during cycling. In this work, a well-defined silicon nanocone (SNC) on silicon wafer sample has been fabricated as a model electrode in lithium ion batteries to investigate the growth of surface species on the SNC electrode during cycling using ex situ scanning electronic microscopy. It is observed that an extra 5 μm thick layer covers the top of the SNCs after 25 cycles at 0.1 C. This top layer has been proven to be a solid electrolyte interphase (SEI) layer by designing a solid lithium battery. It is noticed that the SEI layer is much thinner at a high rate of 1 C. The cyclic performance of the SNCs at 1 C looks much better than that of the same electrode at 0.1 C in the half cell. Our findings clearly demonstrate that the formation of the thick SEI on the naked nanostructured Si anode during low rate cycling is a serious problem for practical applications. An in depth understanding of this problem may provide valuable guidance in designing Si-based anode materials.

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures.

PubMed

Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Zhou, Shizhong; Li, Guoqiang

2015-11-13

2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.0%, very smooth surface with a RMS surface roughness of 3.0 nm, full-width at half-maximums (FWHMs) for GaN(0002) and GaN(102) X-ray rocking curves of 0.7° and 0.8°, respectively, and sharp and abrupt AlN/GaN hetero-interfaces. With the increase in the growth temperature from 550 to 850 °C, the surface morphology, crystalline quality, and interfacial property of as-grown ~300 nm-thick GaN films are gradually improved at first and then decreased. Based on the characterizations, the corresponding growth mechanisms of GaN films grown on AlN/Si hetero-structures by PLD with various growth temperatures are hence proposed. This work would be beneficial to understanding the further insight of the GaN films grown on Si(111) substrates by PLD for the application of GaN-based devices.

High-quality AlN film grown on a nanosized concave-convex surface sapphire substrate by metalorganic vapor phase epitaxy

NASA Astrophysics Data System (ADS)

Yoshikawa, Akira; Nagatomi, Takaharu; Morishita, Tomohiro; Iwaya, Motoaki; Takeuchi, Tetsuya; Kamiyama, Satoshi; Akasaki, Isamu

2017-10-01

We developed a method for fabricating high-crystal-quality AlN films by combining a randomly distributed nanosized concavo-convex sapphire substrate (NCC-SS) and a three-step growth method optimized for NCC-SS, i.e., a 3-nm-thick nucleation layer (870 °C), a 150-nm-thick high-temperature layer (1250 °C), and a 3.2-μm-thick medium-temperature layer (1110 °C). The NCC-SS is easily fabricated using a conventional metalorganic vapor phase epitaxy reactor equipped with a showerhead plate. The resultant AlN film has a crack-free and single-step surface with a root-mean-square roughness of 0.5 nm. The full-widths at half-maxima of the X-ray rocking curve were 50/250 arcsec for the (0002)/(10-12) planes, revealing that the NCC surface is critical for achieving such a high-quality film. Hexagonal-pyramid-shaped voids at the AlN/NCC-SS interface and confinement of dislocations within the 150-nm-thick high-temperature layer were confirmed. The NCC surface feature and resultant faceted voids play an important role in the growth of high-crystal-quality AlN films, likely via localized and/or disordered growth of AlN at the initial stage, contributing to the alignment of high-crystal-quality nuclei and dislocations.

The external scanning proton microprobe of Firenze: A comprehensive description

NASA Astrophysics Data System (ADS)

Giuntini, L.; Massi, M.; Calusi, S.

2007-06-01

An external proton scanning microbeam setup is installed on the -30° line of the new 3 MV tandem accelerator in Firenze; the most relevant features of the line, such as detection setup for IBA measurements, target viewing system, beam diagnostic and transport are described here. With our facility we can work with a beam spot on sample better than 10 μm full-width half-maximum (FWHM) and an intensity of some nanoamperes. Standard beam exit windows are silicon nitride (Si 3N 4) TEM membranes, 100 nm thick and 0.5×0.5 mm 2 wide; we also successfully performed measurements using membranes 1×1 mm 2 wide, 100 nm thick, and 2×2 mm 2 wide, 200 and 500 nm thick. Exploiting the yield of Si X-rays produced by the beam in the exit window as an indirect measurement of the charge, a beam charge monitor system was implemented. The analytical capabilities of the microbeam have been extended by integrating a two-detector PIXE setup with BS and PIGE detectors; the external scanning proton microprobe in Firenze is thus a powerful instrument to fully characterize samples by ion beam analysis, through the simultaneous collection of PIXE, PIGE and BS elemental maps. Its characteristics can make it often competitive with traditional in vacuum microbeam for measurements of thick targets.

Random myosin loss along thick-filaments increases myosin attachment time and the proportion of bound myosin heads to mitigate force decline in skeletal muscle

PubMed Central

Tanner, Bertrand C.W.; McNabb, Mark; Palmer, Bradley M.; Toth, Michael J.; Miller, Mark S.

2014-01-01

Diminished skeletal muscle performance with aging, disuse, and disease may be partially attributed to the loss of myofilament proteins. Several laboratories have found a disproportionate loss of myosin protein content relative to other myofilament proteins, but due to methodological limitations, the structural manifestation of this protein loss is unknown. To investigate how variations in myosin content affect ensemble cross-bridge behavior and force production we simulated muscle contraction in the half-sarcomere as myosin was removed either i) uniformly, from the Z-line end of thick-filaments, or ii) randomly, along the length of thick-filaments. Uniform myosin removal decreased force production, showing a slightly steeper force-to-myosin content relationship than the 1:1 relationship that would be expected from the loss of cross-bridges. Random myosin removal also decreased force production, but this decrease was less than observed with uniform myosin loss, largely due to increased myosin attachment time (ton) and fractional cross-bridge binding with random myosin loss. These findings support our prior observations that prolonged ton may augment force production in single fibers with randomly reduced myosin content from chronic heart failure patients. These simulation also illustrate that the pattern of myosin loss along thick-filaments influences ensemble cross-bridge behavior and maintenance of force throughout the sarcomere. PMID:24486373

Synthesizing new types of ultrathin 2D metal oxide nanosheets via half-successive ion layer adsorption and reaction

NASA Astrophysics Data System (ADS)

Gao, Linjie; Li, Yaguang; Xiao, Mu; Wang, Shufang; Fu, Guangsheng; Wang, Lianzhou

2017-06-01

Two-dimensional (2D) metal oxide nanosheets have demonstrated their great potential in a broad range of applications. The existing synthesis strategies are mainly preparing 2D nanosheets from layered and specific transition metal oxides. How to prepare the other types of metal oxides as ultrathin 2D nanosheets remains unsolved, especially for metal oxides containing alkali, alkaline earth metal, and multiple metal elements. Herein, we developed a half-successive ion layer adsorption and reaction (SILAR) method, which could synthesize those types of metal oxides as ultrathin 2D nanosheets. The synthesized 2D metal oxides nanosheets are within 1 nm level thickness and 500 m2 · g-1 level surface area. This method allows us to develop many new types of ultrathin 2D metal oxides nanosheets that have never been prepared before.

Morphology and stability in a half-metallic ferromagnetic CrO 2 compound of nanoparticles synthesized via a polymer precursor

NASA Astrophysics Data System (ADS)

Biswas, S.; Ram, S.

2004-11-01

Nanoparticles of stable CrO2 of a half-metallic ferromagnet are synthesized with a novel chemical method involving a Cr4+-polymer composite precursor. A single phase CrO2 of D4h 14 : P42 / mnm tetragonal crystal structure (lattice parameters a = 0.4250 and c = 0.3190 nm) lies after firing the precursor at 350 °C for 1 h in air. Microstructure reveals single domain CrO2 particles of thin platelets (aspect ratio ∼1) of average 50 nm diameter and 35 nm thickness. In air, unless heating at temperatures above 500 °C, no due CrO2 → Cr2O3 phase transformation encounters. The results are presented in terms of X-ray diffraction and thermal or thermogravimetric analysis of precursor and derived CrO2 powder.

Encapsulated fuel unit and method of forming same

DOEpatents

Groh, Edward F.; Cassidy, Dale A.; Lewandowski, Edward F.

1985-01-01

This invention teaches an encapsulated fuel unit for a nuclear reactor, such as for an enriched uranium fuel plate of thin cross section of the order of 1/64 or 1/8 of an inch and otherwise of rectangular shape 1-2 inches wide and 2-4 inches long. The case is formed from (a) two similar channel-shaped half sections extended lengthwise of the elongated plate and having side edges butted and welded together to define an open ended tube-like structure and from (b) porous end caps welded across the open ends of the tube-like structure. The half sections are preferably of stainless steel between 0.002 and 0.01 of an inch thick, and are beam welded together over and within machined and hardened tool steel chill blocks. The porous end caps preferably are of T-316-L stainless steel having pores of approximately 3-10 microns size.

Improved encapsulated fuel unit and method of forming same

DOEpatents

Groh, E.F.; Cassidy, D.A.; Lewandowski, E.

1982-09-07

This invention teaches an encapsulated fuel unit for a nuclear reactor, such as for an enriched uranium fuel plate of thin cross section of the order of 1/64 or 1/8 of an inch and otherwise of rectangular shape 1 to 2 inches wide and 2 to 4 inches long. The case is formed from (a) two similar channel-shaped half sections extended lengthwise of the elongated plate and having side edges butted and welded together to define an open ended tube-like structure and from (b) porous end caps welded across the open ends of the tube-like structure. The half sections are preferably of stainless steel between 0.002 and 0.01 of an inch thick, and are beam welded together over and within machined and hardened tool steel chill blocks. The porous end caps preferably are of T-316-L stainless steel having pores of approximately 3 to 10 microns size.

Faulting and instability of shelf sediments: eastern Gulf of Alaska

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, P.R.; Molnia, B.F.

1976-04-01

Faults and submarine slides or slumps are potential environmental hazards on the outer continental shelf of the northern Gulf of Alaska. Submarine slides or slumps have been found in two places in the OCS region: (1) seaward of the Malaspina Glacier and Icy Bay, an area of 1770 square kilometers, that has a slope of less than one-half degree, and (2) across the entire span of the Copper River prodelta, an area of 1730 square kilometers, that has a slope of about one-half degree. Seismic profiles across these areas show disrupted reflectors and irregular topography commonly associated with submarine slidesmore » or slumps. Other potential slide or slum areas have been delineated in areas of thick sediment accumulation and relatively steep slopes. These areas include Kayak Trough, parts of Hinchinbrook Entrance and Sea Valley, parts of the outer shelf and upper slope between Kayak Island and Yakutat Bay and Bering Trough.« less

Imaging of oral pathological tissue using optical coherence tomography

NASA Astrophysics Data System (ADS)

Canjau, Silvana; Todea, Carmen; Sinescu, Cosmin; Duma, Virgil-Florin; Topala, Florin I.; Podoleanu, Adrian G.

2014-01-01

Oral squamous cell carcinoma (OSCC) constitutes 90% of oral cancer. Early detection is a cornerstone to improve survival. Interaction of light with tissues may highlight changes in tissue structure and metabolism. We propose optical coherence tomography (OCT), as a non-invasive diagnosis method, being a new high-resolution optical technique that permits tri-dimensional (3-D), real-time imaging of near surface abnormalities in complex tissues. In this study half of the excisional biopsy was directed to the pathologist and the other half was assigned for OCT investigation. Histopathology validated the results. Areas of OSCC of the buccal mucosa were identified in the OCT images. The elements obserced included extensive epithelial down-growth, the disruption of the basement membrane, with areas of erosion, an epithelial layer that was highly variable in thickness and invasion into the sub-epithelial layers. Therefore, OCT appears to be a highly promising imaging modality.

Thunder-induced ground motions: 2. Site characterization

NASA Astrophysics Data System (ADS)

Lin, Ting-L.; Langston, Charles A.

2009-04-01

Thunder-induced ground motion, near-surface refraction, and Rayleigh wave dispersion measurements were used to constrain near-surface velocity structure at an unconsolidated sediment site. We employed near-surface seismic refraction measurements to first define ranges for site structure parameters. Air-coupled and hammer-generated Rayleigh wave dispersion curves were used to further constrain the site structure by a grid search technique. The acoustic-to-seismic coupling is modeled as an incident plane P wave in a fluid half-space impinging into a solid layered half-space. We found that the infrasound-induced ground motions constrained substrate velocities and the average thickness and velocities of the near-surface layer. The addition of higher-frequency near-surface Rayleigh waves produced tighter constraints on the near-surface velocities. This suggests that natural or controlled airborne pressure sources can be used to investigate the near-surface site structures for earthquake shaking hazard studies.

Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation

USGS Publications Warehouse

Jakobsson, Martin; Nilsson, Johan; Anderson, Leif G.; Backman, Jan; Bjork, Goran; Cronin, Thomas M.; Kirchner, Nina; Koshurnikov, Andrey; Mayer, Larry; Noormets, Riko; O'Regan, Matthew; Stranne, Christian; Ananiev, Roman; Macho, Natalia Barrientos; Cherniykh, Dennis; Coxall, Helen; Eriksson, Bjorn; Floden, Tom; Gemery, Laura; Gustafsson, Orjan; Jerram, Kevin; Johansson, Carina; Khortov, Alexey; Mohammad, Rezwan; Semiletov, Igor

2016-01-01

The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice-shelf groundings on bathymetric highs in the central Arctic Ocean, resurrecting the concept of an ice shelf extending over the entire central Arctic Ocean during at least one previous ice age. New and previously mapped glacial landforms together reveal flow of a spatially coherent, in some regions >1-km thick, central Arctic Ocean ice shelf dated to marine isotope stage 6 (~140 ka). Bathymetric highs were likely critical in the ice-shelf development by acting as pinning points where stabilizing ice rises formed, thereby providing sufficient back stress to allow ice shelf thickening.

Development of 256 x 256 Element Impurity Band Conduction Infrared Detector Arrays for Astronomy

NASA Technical Reports Server (NTRS)

Domingo, George

1997-01-01

This report describes the work performed on a one and a half year advance technology program to develop Impurity Band Conduction (IBC) detectors with very low dark current, high quantum efficiency, and with good repeatable processes. The program fabricated several epitaxial growths of Si:As detecting layers from 15 to 35 microns thick and analyzed the performance versus the thickness and the Arsenic concentration of these epitaxial layers. Some of the epitaxial runs did not yield because of excessive residual impurities. The thicker epitaxial layers and the ones with higher Arsenic concentration resulted in good detectors with low dark currents and good quantum efficiency. The program hybridized six detector die from the best detector wafers to a low noise, 256 x 256 readout array and delivered the hybrids to NASA Ames for a more detailed study of the performance of the detectors.

A new form of Elongatoolithidae, Undulatoolithus pengi oogen. et oosp. nov. from Pingxiang, Jiangxi, China.

PubMed

Wang, Qiang; Zhao, Zikui; Wang, Xiaolin; Li, Ning; Zou, Songlin

2013-12-10

A new oogenus and oospecies of the Elongatoolithidae, Undulatoolithus pengi oogen. et oosp. nov., is described on the basis of specimens from the Upper Cretaceous Zhoutian Formation of the Pingxiang Basin, Jiangxi Province, China. The eggs are slightly asymmetrical, paired, and lay radially-oriented in a circular configuration within the clutch, and most suggestive of Macroolithus of the Elongatoolithidae by medium-sized eggs with average polar axis and equatorial diameter of 19.36 and 8.35 cm, and the ornamentation pattern of nodes and ridges on the outer surface. The new oogenus differs from Macroolithus in its prominent ridges 0.67 mm in height, about half of the entire eggshell thickness, gradational boundary between the cone layer and the overlying columnar layer, cone layer-to-columnar layer thickness ratio of 1/8 or 1/4. This discovery adds new data on the morphology and diversification of Late Cretaceous elongatoolithid ootaxa. 

Dynamic laser piercing of thick section metals

NASA Astrophysics Data System (ADS)

Pocorni, Jetro; Powell, John; Frostevarg, Jan; Kaplan, Alexander F. H.

2018-01-01

Before a contour can be laser cut the laser first needs to pierce the material. The time taken to achieve piercing should be minimised to optimise productivity. One important aspect of laser piercing is the reliability of the process because industrial laser cutting machines are programmed for the minimum reliable pierce time. In this work piercing experiments were carried out in 15 mm thick stainless steel sheets, comparing a stationary laser and a laser which moves along a circular trajectory with varying processing speeds. Results show that circular piercing can decrease the pierce duration by almost half compared to stationary piercing. High speed imaging (HSI) was employed during the piercing process to understand melt behaviour inside the pierce hole. HSI videos show that circular rotation of the laser beam forces melt to eject in opposite direction of the beam movement, while in stationary piercing the melt ejects less efficiently in random directions out of the hole.

Photo-induced persistent inversion of germanium in a 200-nm-deep surface region.

PubMed

Prokscha, T; Chow, K H; Stilp, E; Suter, A; Luetkens, H; Morenzoni, E; Nieuwenhuys, G J; Salman, Z; Scheuermann, R

2013-01-01

The controlled manipulation of the charge carrier concentration in nanometer thin layers is the basis of current semiconductor technology and of fundamental importance for device applications. Here we show that it is possible to induce a persistent inversion from n- to p-type in a 200-nm-thick surface layer of a germanium wafer by illumination with white and blue light. We induce the inversion with a half-life of ~12 hours at a temperature of 220 K which disappears above 280 K. The photo-induced inversion is absent for a sample with a 20-nm-thick gold capping layer providing a Schottky barrier at the interface. This indicates that charge accumulation at the surface is essential to explain the observed inversion. The contactless change of carrier concentration is potentially interesting for device applications in opto-electronics where the gate electrode and gate oxide could be replaced by the semiconductor surface.

La2/3Sr1/3MnO3-La0.1Bi0.9MnO3 heterostructures for spin filtering

NASA Astrophysics Data System (ADS)

Gajek, M.; Bibes, M.; Varela, M.; Fontcuberta, J.; Herranz, G.; Fusil, S.; Bouzehouane, K.; Barthélémy, A.; Fert, A.

2006-04-01

We have grown heterostructures associating half-metallic La2/3Sr1/3MnO3 (LSMO) bottom electrodes and ferromagnetic La0.1Bi0.9MnO3 (LBMO) tunnel barriers. The layers in the heterostructures have good structural properties and top LBMO films (4 nm thick) have a very low roughness when deposited onto LSMO/SrTiO3(1.6 nm) templates. The LBMO films show an insulating behavior and a ferromagnetic character that are both preserved down to very low thicknesses. They are thus suitable for being used as tunnel barriers. Spin-dependent transport measurements performed on tunnel junctions defined from LSMO/SrTiO3/LBMO/Au samples show a magnetoresistance of up to ~90% at low temperature and bias. This evidences a spin-filtering effect by the LBMO layer, with a spin-filtering efficiency of ~35%.

Development, testing, and numerical modeling of a foam sandwich biocomposite

NASA Astrophysics Data System (ADS)

Chachra, Ricky

This study develops a novel sandwich composite material using plant based materials for potential use in nonstructural building applications. The face sheets comprise woven hemp fabric and a sap based epoxy, while the core comprises castor oil based foam with waste rice hulls as reinforcement. Mechanical properties of the individual materials are tested in uniaxial compression and tension for the foam and hemp, respectively. The sandwich composite is tested in 3 point bending. Flexural results are compared to a finite element model developed in the commercial software Abaqus, and the validated model is then used to investigate alternate sandwich geometries. Sandwich model responses are compared to existing standards for nonstructural building panels, showing that the novel material is roughly half the strength of equally thick drywall. When space limitations are not an issue, a double thickness sandwich biocomposite is found to be a structurally acceptable replacement for standard gypsum drywall.

Broadband and wide-angle light harvesting by ultra-thin silicon solar cells with partially embedded dielectric spheres.

PubMed

Yang, Zhenhai; Shang, Aixue; Qin, Linling; Zhan, Yaohui; Zhang, Cheng; Gao, Pingqi; Ye, Jichun; Li, Xiaofeng

2016-04-01

We propose a design of crystalline silicon thin-film solar cells (c-Si TFSCs, 2 μm-thick) configured with partially embedded dielectric spheres on the light-injecting side. The intrinsic light trapping and photoconversion are simulated by the complete optoelectronic simulation. It shows that the embedding depth of the spheres provides an effective way to modulate and significantly enhance the optical absorption. Compared to the conventional planar and front sphere systems, the optimized partially embedded sphere design enables a broadband, wide-angle, and strong optical absorption and efficient carrier transportation. Optoelectronic simulation predicts that a 2 μm-thick c-Si TFSC with half-embedded spheres shows an increment of more than 10  mA/cm² in short-circuit current density and an enhancement ratio of more than 56% in light-conversion efficiency, compared to the conventional planar counterparts.

Analysis of fluid film lubrication in artificial hip joint replacements with surfaces of high elastic modulus.

PubMed

Jin, Z M; Dowson, D; Fisher, J

1997-01-01

Lubrication mechanisms and contact mechanics have been analysed for total hip joint replacements made from hard bearing surfaces such as metal-on-metal and ceramic-on-ceramic. A similar analysis for ultra-high molecular weight polyethylene (UHMWPE) against a hard bearing surface has also been carried out and used as a reference. The most important factor influencing the predicted lubrication film thickness has been found to be the radial clearance between the ball and the socket. Full fluid film lubrication may be achieved in these hard/hard bearings provided that the surface finish of the bearing surface and the radial clearance are chosen correctly and maintained. Furthermore, there is a close relation between the predicted contact half width and the predicted lubrication film thickness. Therefore, it is important to analyse the contact mechanics in artificial hip joint replacements. Practical considerations of manufacturing these bearing surfaces have also been discussed.

Secondary neutrons as the main source of neutron-rich fission products in the bombardment of a thick U target by 1 GeV protons

NASA Astrophysics Data System (ADS)

Barzakh, A. E.; Lhersonneau, G.; Batist, L. Kh.; Fedorov, D. V.; Ivanov, V. S.; Mezilev, K. A.; Molkanov, P. L.; Moroz, F. V.; Orlov, S. Yu.; Panteleev, V. N.; Volkov, Yu. M.; Alyakrinskiy, O.; Barbui, M.; Stroe, L.; Tecchio, L. B.

2011-05-01

The diffusion-effusion model has been used to analyse the release and yields of Fr and Cs isotopes from uranium carbide targets of very different thicknesses (6.3 and 148 g/cm2) bombarded by a 1 GeV proton beam. Release curves of several isotopes of the same element and production efficiency versus decay half-life are well fitted with the same set of parameters. Comparison of efficiencies for neutron-rich and neutron-deficient Cs isotopes enables separation of the contributions from the primary ( p + 238U) and secondary (n + 238U) reactions to the production of neutron-rich Cs isotopes. A rather simple calculation of the neutron contribution describes these data fairly well. The FLUKA code describes the primary and secondary-reaction contributions to the Cs isotopes production efficiencies for different targets quite well.

An Examination of the Sea Ice Rheology for Seasonal Ice Zones Based on Ice Drift and Thickness Observations

NASA Astrophysics Data System (ADS)

Toyota, Takenobu; Kimura, Noriaki

2018-02-01

The validity of the sea ice rheological model formulated by Hibler (1979), which is widely used in present numerical sea ice models, is examined for the Sea of Okhotsk as an example of the seasonal ice zone (SIZ), based on satellite-derived sea ice velocity, concentration and thickness. Our focus was the formulation of the yield curve, the shape of which can be estimated from ice drift pattern based on the energy equation of deformation, while the strength of the ice cover that determines its magnitude was evaluated using ice concentration and thickness data. Ice drift was obtained with a grid spacing of 37.5 km from the AMSR-E 89 GHz brightness temperature using a maximum cross-correlation method. The ice thickness was obtained with a spatial resolution of 100 m from a regression of the PALSAR backscatter coefficients with ice thickness. To assess scale dependence, the ice drift data derived from a coastal radar covering a 70 km range in the southernmost Sea of Okhotsk were similarly analyzed. The results obtained were mostly consistent with Hibler's formulation that was based on the Arctic Ocean on both scales with no dependence on a time scale, and justify the treatment of sea ice as a plastic material, with an elliptical shaped yield curve to some extent. However, it also highlights the difficulty in parameterizing sub-grid scale ridging in the model because grid scale ice velocities reduce the deformation magnitude by half due to the large variation of the deformation field in the SIZ.

On the meaning of the diffusion layer thickness for slow electrode reactions.

PubMed

Molina, A; González, J; Laborda, E; Compton, R G

2013-02-21

A key concept underpinning electrochemical science is that of the diffusion layer - the zone of depletion around an electrode accompanying electrolysis. The size of this zone can be found either from the simulated or measured concentration profiles (yielding the 'true' diffusion layer thickness) or, in the case of the Nernst ('linear') diffusion layer by extrapolating the concentration gradient at the electrode surface to the distance at which the concentration takes its bulk value. The latter concept is very well developed in the case of fast (so-called reversible) electrode processes, however the study of the linear diffusion layer has received scant attention in the case of slow charge transfer processes, despite its study being of great interest in the analysis of the influence of different experimental variables which determine the electrochemical response. Analytical explicit solutions for the concentration profiles, surface concentrations and real and linear diffusion layers corresponding to the application of a potential step to a slow charge transfer process are presented. From these expressions the dependence of the diffusion layer thickness on the potential, pulse time, heterogeneous rate constant and ratio of bulk concentrations of electroactive species and of diffusion coefficients is quantified. A profound influence of the reversibility degree of the charge transfer on the diffusion layer thickness is clear, showing that for non-reversible processes the real and linear diffusion layers reveal a minimum thickness which coincides with the equilibrium potential of the redox couple in the former case and with the reversible half-wave potential in the latter one.

Dynamic Defrosting on Scalable Superhydrophobic Surfaces

DOE PAGES

Murphy, Kevin R.; McClintic, William T.; Lester, Kevin C.; ...

2017-06-27

Recent studies have shown that frost can grow in a suspended Cassie state on nanostructured superhydrophobic surfaces. During defrosting, the melting sheet of Cassie frost spontaneously dewets into quasi-spherical slush droplets that are highly mobile. Promoting Cassie frost would therefore seem advantageous from a defrosting standpoint; however, nobody has systematically compared the efficiency of defrosting Cassie ice versus defrosting conventional surfaces. Here, we characterize the defrosting of an aluminum plate, one-half of which exhibits a superhydrophobic nanostructure while the other half is smooth and hydrophobic. For thick frost sheets (>1 mm), the superhydrophobic surface was able to dynamically shed themore » meltwater, even at very low tilt angles. In contrast, the hydrophobic surface was unable to shed any appreciable meltwater even at a 90° tilt angle. For thin frost layers (≲1 mm), not even the superhydrophobic surface could mobilize the meltwater. We attribute this to the large apparent contact angle of the meltwater, which for small amounts of frost serves to minimize coalescence events and prevent droplets from approaching the capillary length. Finally, we demonstrate a new mode of dynamic defrosting using an upside-down surface orientation, where the melting frost was able to uniformly detach from the superhydrophobic side and subsequently pull the frost from the hydrophobic side in a chain reaction. Treating surfaces to enable Cassie frost is therefore very desirable for enabling rapid and low-energy thermal defrosting, but only for frost sheets that are sufficiently thick.« less

Dynamic Defrosting on Scalable Superhydrophobic Surfaces.

PubMed

Murphy, Kevin R; McClintic, William T; Lester, Kevin C; Collier, C Patrick; Boreyko, Jonathan B

2017-07-19

Recent studies have shown that frost can grow in a suspended Cassie state on nanostructured superhydrophobic surfaces. During defrosting, the melting sheet of Cassie frost spontaneously dewets into quasi-spherical slush droplets that are highly mobile. Promoting Cassie frost would therefore seem advantageous from a defrosting standpoint; however, nobody has systematically compared the efficiency of defrosting Cassie ice versus defrosting conventional surfaces. Here, we characterize the defrosting of an aluminum plate, one-half of which exhibits a superhydrophobic nanostructure while the other half is smooth and hydrophobic. For thick frost sheets (>1 mm), the superhydrophobic surface was able to dynamically shed the meltwater, even at very low tilt angles. In contrast, the hydrophobic surface was unable to shed any appreciable meltwater even at a 90° tilt angle. For thin frost layers (≲1 mm), not even the superhydrophobic surface could mobilize the meltwater. We attribute this to the large apparent contact angle of the meltwater, which for small amounts of frost serves to minimize coalescence events and prevent droplets from approaching the capillary length. Finally, we demonstrate a new mode of dynamic defrosting using an upside-down surface orientation, where the melting frost was able to uniformly detach from the superhydrophobic side and subsequently pull the frost from the hydrophobic side in a chain reaction. Treating surfaces to enable Cassie frost is therefore very desirable for enabling rapid and low-energy thermal defrosting, but only for frost sheets that are sufficiently thick.

Indentation-induced solid-state dewetting of thin Au(Fe) films

NASA Astrophysics Data System (ADS)

Kosinova, Anna; Schwaiger, Ruth; Klinger, Leonid; Rabkin, Eugen

2017-07-01

We studied the effect of local plastic deformation on the thermal stability and solid-state dewetting of thin homogeneous Au(Fe) films deposited on sapphire substrates. The films with ordered square arrays of indents produced by nanoindentation were annealed at the temperature of 700 °C in a forming gas atmosphere. The behavior of the film in the region of shallow indents (reaching a depth up to one half of the film thickness) was very different from the one in the region of deep indents (with depths greater than one half of the film thickness). In the first case, the grain growth in indented and unperturbed regions of the film proceeded quite similarly, and nearly complete healing of the indents was observed. In the latter case, a recrystallization process in the vicinity of the indents resulted in the formation of small new grains with misorientation angles that were not present in the as-deposited film. The thermal grooving along the corresponding new high-energy grain boundaries caused an increase of the depth of the indents and the formation of the dewetting holes. The morphology of these holes and their size were different compared to the holes formed randomly in the unperturbed regions of the same films. In particular, the interaction between the individual indents of an array led to the preferential formation of holes at the periphery of the arrays. These findings shed a new light on the process of nucleation of the solid-state dewetting in thin films.

Transrectal ultrasonographic evaluation of combined utero-placental thickness during the last half of pregnancy in Martina Franca donkeys.

PubMed

Carluccio, A; Noto, F; Parrillo, S; Contri, A; De Amicis, I; Gloria, A; Robbe, D; Veronesi, M C

2016-12-01

In the recent years, the donkey population decreased dramatically so that many breeds are presently considered as endangered. In comparison to the horse, the donkey placenta still remains not completely studied. In the horse, one of the diagnostic tools useful to identify pregnant mares at risk of abortion or premature delivery, include the transrectal ultrasound examination of the uterus and its contents; and especially of the combined thickness of the uterus and of the placenta (CUPT). Since the CUPT was never investigated in donkeys, the present study was aimed to define the transrectal CUPT values during the last half of pregnancy in 20 Martina Franca jennies. Foalings times, foals characteristics and placental gross appearance, and measurements were also evaluated and values resulted always within normality. Differently to the mare, a continuous significant CUPT increase between the sixth to the 12 months of pregnancy, and a substantial increase from the ninth to the 12th month of pregnancy, was found. Although statistically not evaluable, the CUPT values recorded from three jennies with pregnancy loss did not show evidence of CUPT increases. In conclusion, normal CUPT values from the sixth to the 12th month of pregnancy in Martina Franca donkeys are provided, but further investigations are needed to define possible breed or body-size CUPT specific differences, as well as the CUPT values during pregnancy disturbances or placental abnormalities. Copyright © 2016 Elsevier Inc. All rights reserved.

Symmetry of Epitaxial BiFeO3 Films in the Ultrathin Regime

NASA Astrophysics Data System (ADS)

Yang, Yongsoo; Schlep&üTz, Christian; Adamo, Carolina; Schlom, Darrell; Clarke, Roy

2013-03-01

BiFeO3 (BFO) films grown on SrTiO3 (STO) with a SrRuO3 buffer layer exhibit a monoclinic structure at thicknesses greater than 40 nm, but higher structural symmetry can be observed for thinner films [Phys. Rev. B 81, 144115 (2010)]. We report a structural phase transition from monoclinic to tetragonal in ultra-thin BFO films grown directly on (100)-oriented STO. X-ray diffraction measurements of 3-dimensional reciprocal space maps reveal half-integer order peaks due to oxygen octahedral tilting. When the film thickness is decreased below 20 unit cells, the integer-order Bragg peak splitting associated with the presence of multiple domains of the monoclinic phase disappears. Instead, a single peak that is commensurate with the STO substrate lattice appears. The diffraction pattern has four-fold symmetry, ruling out the presence of a single monoclinic domain in favor of a tetragonal film structure. The evolution of the oxygen octahedra tilt pattern inferred from the intensities of half-order peaks suggests that this transition originates from the corner-connectivity of oxygen atoms at the interface between BFO and STO, and also strongly supports this monoclinic to tetragonal transition. Supported in part by the U.S. Department of Energy (DE-FG02-06ER46273). Measurements performed at Sectors 13-BMC, 33-IDD, 33-BMC of the Advanced Photon Source, Argonne National Laboratory, USA (DOE contract No. DE-AC02-06CH11357).

Dynamic Defrosting on Scalable Superhydrophobic Surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murphy, Kevin R.; McClintic, William T.; Lester, Kevin C.

Recent studies have shown that frost can grow in a suspended Cassie state on nanostructured superhydrophobic surfaces. During defrosting, the melting sheet of Cassie frost spontaneously dewets into quasi-spherical slush droplets that are highly mobile. Promoting Cassie frost would therefore seem advantageous from a defrosting standpoint; however, nobody has systematically compared the efficiency of defrosting Cassie ice versus defrosting conventional surfaces. Here, we characterize the defrosting of an aluminum plate, one-half of which exhibits a superhydrophobic nanostructure while the other half is smooth and hydrophobic. For thick frost sheets (>1 mm), the superhydrophobic surface was able to dynamically shed themore » meltwater, even at very low tilt angles. In contrast, the hydrophobic surface was unable to shed any appreciable meltwater even at a 90° tilt angle. For thin frost layers (≲1 mm), not even the superhydrophobic surface could mobilize the meltwater. We attribute this to the large apparent contact angle of the meltwater, which for small amounts of frost serves to minimize coalescence events and prevent droplets from approaching the capillary length. Finally, we demonstrate a new mode of dynamic defrosting using an upside-down surface orientation, where the melting frost was able to uniformly detach from the superhydrophobic side and subsequently pull the frost from the hydrophobic side in a chain reaction. Treating surfaces to enable Cassie frost is therefore very desirable for enabling rapid and low-energy thermal defrosting, but only for frost sheets that are sufficiently thick.« less

Paleogeographic implications of Late Miocene lacustrine and nonmarine evaporite deposits in the Lake Mead region: Immediate precursors to the Colorado River

USGS Publications Warehouse

Faulds, James E.; Schreiber, Charlotte; Langenheim, Victoria; Hinz, Nicholas H.; Shaw, Tom; Heizler, Matthew T.; Perkins, Michael E; El Tabakh, Mohammed; Kunk, Michael J.

2016-01-01

Thick late Miocene nonmarine evaporite (mainly halite and gypsum) and related lacustrine limestone deposits compose the upper basin fill in half grabens within the Lake Mead region of the Basin and Range Province directly west of the Colorado Plateau in southern Nevada and northwestern Arizona. Regional relations and geochronologic data indicate that these deposits are late synextensional to postextensional (ca. 12–5 Ma), with major extension bracketed between ca. 16 and 9 Ma and the abrupt western margin of the Colorado Plateau established by ca. 9 Ma. Significant accommodation space in the half grabens allowed for deposition of late Miocene lacustrine and evaporite sediments. Concurrently, waning extension promoted integration of initially isolated basins, progressive enlargement of drainage nets, and development of broad, low gradient plains and shallow water bodies with extensive clastic, carbonate, and/or evaporite sedimentation. The continued subsidence of basins under restricted conditions also allowed for the preservation of particularly thick, localized evaporite sequences prior to development of the through-going Colorado River.The spatial and temporal patterns of deposition indicate increasing amounts of freshwater input during the late Miocene (ca. 12–6 Ma) immediately preceding arrival of the Colorado River between ca. 5.6 and 4.9 Ma. In axial basins along and proximal to the present course of the Colorado River, evaporite deposition (mainly gypsum) transitioned to lacustrine limestone progressively from east to west, beginning ca. 12–11 Ma in the Grand Wash Trough in the east and shortly after ca. 5.6 Ma in the western Lake Mead region. In several satellite basins to both the north and south of the axial basins, evaporite deposition was more extensive, with thick halite (>200 m to 2.5 km thick) accumulating in the Hualapai, Overton Arm, and northern Detrital basins. Gravity and magnetic lows suggest that thick halite may also lie within the northern Grand Wash, Mesquite, southern Detrital, and northeastern Las Vegas basins. New tephrochronologic data indicate that the upper part of the halite in the Hualapai basin is ca. 5.6 Ma, with rates of deposition of ∼190–450 m/m.y., assuming that deposition ceased approximately coincidental with the arrival of the Colorado River. A 2.5-km-thick halite sequence in the Hualapai basin may have accumulated in ∼5–7 m.y. or ca. 12–5 Ma, which coincides with lacustrine limestone deposition near the present course of the Colorado River in the region.The distribution and similar age of the limestone and evaporite deposits in the region suggest a system of late Miocene axial lakes and extensive continental playas and salt pans. The playas and salt pans were probably fed by both groundwater discharge and evaporation from shallow lakes, as evidenced by sedimentary textures. The elevated terrain of the Colorado Plateau was likely a major source of water that fed the lakes and playas. The physical relationships in the Lake Mead region suggest that thick nonmarine evaporites are more likely to be late synextensional and accumulate in basins with relatively large catchments proximal to developing river systems or broad elevated terranes. Other basins adjacent to the lower Colorado River downstream of Lake Mead, such as the Dutch Flat, Blythe-McCoy, and Yuma basins, may also contain thick halite deposits.

Proton acceleration by a pair of successive ultraintense femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Ferri, J.; Senje, L.; Dalui, M.; Svensson, K.; Aurand, B.; Hansson, M.; Persson, A.; Lundh, O.; Wahlström, C.-G.; Gremillet, L.; Siminos, E.; DuBois, T. C.; Yi, L.; Martins, J. L.; Fülöp, T.

2018-04-01

We investigate the target normal sheath acceleration of protons in thin aluminum targets irradiated at a relativistic intensity by two time-separated ultrashort (35 fs) laser pulses. When the full-energy laser pulse is temporally split into two identical half-energy pulses, and using target thicknesses of 3 and 6 μm, we observe experimentally that the second half-pulse boosts the maximum energy and charge of the proton beam produced by the first half-pulse for time delays below ˜0.6-1 ps. Using two-dimensional particle-in-cell simulations, we examine the variation of the proton energy spectra with respect to the time-delay between the two pulses. We demonstrate that the expansion of the target front surface caused by the first pulse significantly enhances the hot-electron generation by the second pulse arriving after a few hundreds of fs time delay. This enhancement, however, does not suffice to further accelerate the fastest protons driven by the first pulse once three-dimensional quenching effects have set in. This implies a limit to the maximum time delay that leads to proton energy enhancement, which we theoretically determine.

Methodology for assessing the probability of corrosion in concrete structures on the basis of half-cell potential and concrete resistivity measurements.

PubMed

Sadowski, Lukasz

2013-01-01

In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. Potential E corr and concrete resistivity ρ in each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures.

Investigation of hydrodynamic behaviour of membranes using radiotracer techniques

NASA Astrophysics Data System (ADS)

Miskiewicz, A.; Zakrzewska-Trznadel, G.

2013-05-01

The aim of the work was to study membrane devices using short-lived radioisotopes like Ba-137m and Ga-68 as tracers. These radioisotopes were obtained from radionuclide generators: Cs-137/Ba-137m and Ge-68/Ga-68. The first radionuclide, namely Ba-137m with a half-life of 2.55 minutes was applied as a liquid phase tracer for studying hydrodynamic conditions inside the membrane apparatus. The membrane module with ceramic membranes was tested by using Ba-137m. The experiments showed that this radionuclide with a short half-life is a perfect tracer for liquid phase, whereas Ga-68 with longer half-life equal to 68 minutes was considered as a solid phase (bentonite) tracer. Ga-68 was used to gain more knowledge about the phenomena occurring in the membrane boundary layer. After kinetic studies of isotope adsorption into the carrier material, the growth rate of the deposit layer as well as deposit's thickness on the flat-sheet membrane were studied. The influence of such process parameters like pressure, linear velocity of liquid and feed concentration on formation of the bentonite layer on the membrane surface was studied.

Thermoelectric properties of Zn4Sb3/CeFe(4-x)CoxSb12 nano-layered superlattices modified by MeV Si ion beam

NASA Astrophysics Data System (ADS)

Budak, S.; Guner, S.; Minamisawa, R. A.; Muntele, C. I.; Ila, D.

2014-08-01

We prepared multilayers of superlattice thin film system with 50 periodic alternating nano-layers of semiconducting half-Heusler β-Zn4Sb3 and skutterudite CeFe2Co2Sb12 compound thin films using ion beam assisted deposition (IBAD) with Au layers deposited on both sides as metal contacts. The deposited multilayer thin films have alternating layers about 5 nm thick. The total thickness of the multilayer system is 275 nm. The superlattices were then bombarded by 5 MeV Si ion at six different fluences to form nano-cluster structures. The film thicknesses and composition were monitored by Rutherford backscattering spectrometry (RBS) before and after MeV ion bombardment. We have measured the thermoelectric efficiency, Figure of Merit ZT, of the fabricated device by measuring the cross plane thermal conductivity by the 3rd harmonic (3ω) method, the cross plane Seebeck coefficient, and the electrical conductivity using the van der Pauw method before and after the MeV ion bombardments. We reached the remarkable thermoelectric Figure of Merit results at optimal fluences.

Preliminary report on the coal resources of the National Petroleum Reserve in Alaska

USGS Publications Warehouse

Martin, G.C.; Callahan, J.E.

1978-01-01

NPR-A, located on the Arctic slope of Northern Alaska, is underlain by a thick sequence of sedimentary rocks of Cretaceous age which attain a thickness of as much as 4600 m (15,000 feet). The bulk of the coal resources occurs in rocks of the Nanushuk Group of Early and Late Cretaceous age. The Nanushuk Group is a wedge-shaped unit of marginal marine and nonmarine rocks that is as thick as 3300 m (11,000 feet) just west of NPR-A. Within the reserve, coal occurs primarily in the middle and thicker portions of this clastic wedge and occurs stratigraphically in the upper half of the section. Specific data on individual coal beds or zones are scarce, and estimates of identified coal resources of about 49.5 billion tons represent a sampling of coal resources too small to give a realistic indication of the potential resources for an area so large. Estimates of undiscovered resources suggest hypothetical resources of between 330 billion and 3.3 trillion tons. The wide range in the undiscovered resource estimates reflects the scarcity and ambiguity of the available data but also suggests the presence of a potentially large coal resource.

The Crustal Structure of the Central Anatolia (Turkey) Using Receiver Functions

NASA Astrophysics Data System (ADS)

Yelkenci, S.; Benoit, M.; Kuleli, H.; Gurbuz, C.

2005-12-01

Central Anatolia lies in a transitional region between the extensional tectonics of western Anatolia and the complex transpressional tectonics of Eastern Anatolia, and has a complicated thermal and structural history. Few studies of the crustal structure of Anatolia have been performed, however, studies of the crustal structure of Eastern Anatolia showed that crustal thicknesses were thinner than previously thought. To further investigate the crustal structure in Central Anatolia, we present results from receiver function analysis using new data from broad-band instruments. The stations were equipped with 7 broadband three-component STS-2 and 13 short period three-component S-13 sensors. These stations operated for period of one and half months between the October and November, 2002, and yielded data for ~ 40 high quality receiver functions. Additionally, receiver functions were also computed using data from permanent stations MALT, ISP, and ANTO. We applied the hk-stacking technique of Zhu and Kanamori (2000) to receiver functions to obtain the crustal thickness and Vp/Vs ratios. Furthermore, we applied a waveform modeling technique to investigate mid-crustal discontinuties previously imaged in the region. Our results compare well with refraction-based crustal thicknesses in overlapped areas.

Verification of drag-reduction capabilities of stiff compliant coatings in air flow at moderate speeds

NASA Astrophysics Data System (ADS)

Boiko, Andrey V.; Kulik, Victor M.; Chun, Ho-Hwan; Lee, Inwon

2011-12-01

Skin frictional drag reduction efficiency of "stiff" compliant coating was investigated in a wind tunnel experiment. Flat plate compliant coating inserts were installed in a wind tunnel and the measurements of skin frictional drag and velocity field were carried out. The compliant coatings with varying viscoelastic properties had been prepared using different composition. In order to optimize the coating thickness, the most important design parameter, the dynamic viscoelastic properties had been determined experimentally. The aging of the materials (variation of their properties) during half a year was documented as well. A design procedure proposed by Kulik et al. (2008) was applied to get an optimal value for the coating thickness. Along with the drag measurement using the strain balance, velocity and pressure were measured for different coatings. The compliant coatings with the thickness h = 7mm achieved 4~5% drag reduction within a velocity range 30~40 m/s. The drag reduction mechanism of the attenuation of turbulence velocity fluctuations due to the compliant coating was demonstrated. It is envisioned that larger drag reduction effect is obtainable at higher flow velocities for high speed trains and subsonic aircrafts.

Cluster Formation of Anchored Proteins Induced by Membrane-Mediated Interaction

PubMed Central

Li, Shuangyang; Zhang, Xianren; Wang, Wenchuan

2010-01-01

Abstract Computer simulations were used to study the cluster formation of anchored proteins in a membrane. The rate and extent of clustering was found to be dependent upon the hydrophobic length of the anchored proteins embedded in the membrane. The cluster formation mechanism of anchored proteins in our work was ascribed to the different local perturbations on the upper and lower monolayers of the membrane and the intermonolayer coupling. Simulation results demonstrated that only when the penetration depth of anchored proteins was larger than half the membrane thickness, could the structure of the lower monolayer be significantly deformed. Additionally, studies on the local structures of membranes indicated weak perturbation of bilayer thickness for a shallowly inserted protein, while there was significant perturbation for a more deeply inserted protein. The origin of membrane-mediated protein-protein interaction is therefore due to the local perturbation of the membrane thickness, and the entropy loss—both of which are caused by the conformation restriction on the lipid chains and the enhanced intermonolayer coupling for a deeply inserted protein. Finally, in this study we addressed the difference of cluster formation mechanisms between anchored proteins and transmembrane proteins. PMID:20513399

HST and Adaptive Optics Imaging of the Edge-on Circumtertiary Disk in the Young Triple System HV Tauri

NASA Astrophysics Data System (ADS)

Stapelfeldt, K. R.; Menard, F.; Brandner, W.; Padgett, D. L.; Krist, J. E.; Watson, A. M.

2000-12-01

Hubble Space Telescope images of the HV Tauri triple system show that HV Tau C appears as a compact bipolar nebula at visual wavelengths. Near-infrared adaptive optics observations made at the Canada France Hawaii Telescope show a similar morphology, and no directly visible star at wavelengths less than 2 microns. These results confirm the conclusions of Monin & Bouvier 2000, namely that HV Tau C is an optically thick circumstellar disk seen close to edge-on. The images are compared to scattered light models for circumstellar disks. We find that the HV Tau C disk has an outer radius of 85 AU, inclination of about 6 deg, gaussian scale height of 15 AU at its outer radius, and is flared. The thickness of the dark lane indicates a total disk mass about half that of Jupiter. There is clear evidence for declining dust opacity toward longer wavelengths, as the dust lane thickness shrinks by 30 between 0.8 and 2.2 microns; the trend is consistent with interstellar dust grains. Tidal truncation of the disk outer radius may have occurred in this system.

A self-assembly aptasensor based on thick-shell quantum dots for sensing of ochratoxin A

NASA Astrophysics Data System (ADS)

Chu, Xianfeng; Dou, Xiaowen; Liang, Ruizheng; Li, Menghua; Kong, Weijun; Yang, Xihui; Luo, Jiaoyang; Yang, Meihua; Zhao, Ming

2016-02-01

A novel self-assembling aptasensor was fabricated by precisely attaching three phosphorothioate-modified capture aptamers onto a single thick-shell quantum dot in a controllable manner for monitoring of ochratoxin A (OTA), a poisonous contaminant widespread in foodstuffs. Herein, CdSe/CdS QDs coated in ten layer CdS shells were synthesized using a continual precursor injection method. Analysis of the prepared CdSe/CdS QDs showed a zinc-blende structure, high photoluminescence quantum yields (>80%), and a photoemission peak with a narrow full-width at half-maximum (about 29 nm), all qualities that render them as a superior choice for optical applications. By adjusting the number of phosphorothioate bases in the anchor domain, the tunable-valency aptasensor was able to self-assemble. In the sensing strategy, the thick-shell quantum dot was provided as an acceptor while OTA itself was used as a donor. In the presence of OTA, the capture aptamers drive the aptasensor function into a measurable signal through a fluorescence resonance energy transfer (FRET) system. The newly developed aptasensor had a detection limit as low as 0.5 ng mL-1, with a linear concentration in the range of 1 to 30 ng mL-1, and therefore meets the requirements for rapid, effective, and anti-interference sensors for real-world applications. Moreover, the high quality thick-shell QDs provide an ideal alternative for highly sensitive imaging and intensive illumination in the fields of biotechnology and bioengineering.A novel self-assembling aptasensor was fabricated by precisely attaching three phosphorothioate-modified capture aptamers onto a single thick-shell quantum dot in a controllable manner for monitoring of ochratoxin A (OTA), a poisonous contaminant widespread in foodstuffs. Herein, CdSe/CdS QDs coated in ten layer CdS shells were synthesized using a continual precursor injection method. Analysis of the prepared CdSe/CdS QDs showed a zinc-blende structure, high photoluminescence quantum yields (>80%), and a photoemission peak with a narrow full-width at half-maximum (about 29 nm), all qualities that render them as a superior choice for optical applications. By adjusting the number of phosphorothioate bases in the anchor domain, the tunable-valency aptasensor was able to self-assemble. In the sensing strategy, the thick-shell quantum dot was provided as an acceptor while OTA itself was used as a donor. In the presence of OTA, the capture aptamers drive the aptasensor function into a measurable signal through a fluorescence resonance energy transfer (FRET) system. The newly developed aptasensor had a detection limit as low as 0.5 ng mL-1, with a linear concentration in the range of 1 to 30 ng mL-1, and therefore meets the requirements for rapid, effective, and anti-interference sensors for real-world applications. Moreover, the high quality thick-shell QDs provide an ideal alternative for highly sensitive imaging and intensive illumination in the fields of biotechnology and bioengineering. Electronic supplementary information (ESI) available: Table S1. See DOI: 10.1039/c5nr08284f

A method to generate surface UV radiation maps over Europe using GOME, Meteosat, and ancillary geophysical data

NASA Astrophysics Data System (ADS)

Verdebout, Jean

2000-02-01

This paper presents a method for generating surface ultraviolet (UV) radiation maps over Europe, with a spatial resolution of 0.05°, and potentially on a half-hour basis. The UV irradiance is obtained by interpolation in a look-up table (LUT), the entries of which are solar zenith angle, total column ozone amount, cloud liquid water thickness, near-surface horizontal visibility, surface elevation, and UV albedo. Both satellite (Meteosat, GOME) and nonsatellite (synoptic observations, meteorological model results, digital elevation model) data are exploited to assign values to the influencing factors. With the help of another LUT simulating the visible signal, Meteosat data are processed to retrieve the cloud liquid water thickness. The radiative transfer calculations are performed with the UVspec code. A preliminary step consists in generating an effective surface Meteosat albedo map from a series of 10 consecutive days. In this process the well-known difficulty of distinguishing clouds from snow-covered surfaces is encountered. An attempt is made to partially resolve the ambiguity by using the Meteosat infrared channel and modeled snow cover data. After additional empirical cloud filtering, the effective albedo map is used as a baseline to estimate the cloud liquid water thickness. The UV surface albedo is assigned uniform values for land and sea/ocean, except in the presence of snow. In this case it is given a value proportional to the Meteosat effective albedo. The total column ozone is extracted from the level 3 GOME products. The aerosol optical thickness is mapped by gridding the daily measurements performed by ˜1000 ground stations. The digital elevation model is the GTOPO30 data set from the U.S. Geological Survey. European wide UV dose rate maps are presented for one day in April 1997, and the influence of the various factors is illustrated. A daily integrated dose map was also generated using 27 Meteosat acquisitions at half-hour intervals on the same day. The dose map produced in this way takes into account the evolution of the cloud field and is thought to be more accurate than if it were estimated from one data take, in particular at the relatively high spatial resolution of the product. Finally, a preliminary comparison of modeled dose rate and daily dose with measurements performed with a ground instrument is discussed.

The crustal structure from the Altai Mountains to the Altyn Tagh fault, northwest China

USGS Publications Warehouse

Wang, Y.; Mooney, W.D.; Yuan, X.; Coleman, R.G.

2003-01-01

We present a new crustal section across northwest China based on a seismic refraction profile and geologic mapping. The 1100-km-long section crosses the southern margin of the Chinese Altai Mountains, Junggar Accretional Belt and eastern Junggar basin, easternmost Tianshan Mountains, and easternmost Tarim basin. The crustal velocity structure and Poisson's ratio (??), which provide a constraint on crustal composition, were determined from P and S wave data. Despite the complex geology, the crustal thickness along the entire profile is nearly uniform at 50 km. The thickest crust (56 km) occurs at the northern end of the profile beneath the Altai Mountains and the thinnest (46 km) crust is beneath the Junggar basin. Beneath surficial sediments, the crust is found to have three layers with P wave velocities (Vp) of 6.0-6.3, 6.3-6.6, and 6.9-7.0 km/s, respectively. The southern half of the profile, including the eastern Tianshan Mountains and eastern margin of the Tarim basin, shows low P wave velocities and ?? = 0.25 to a depth of 30 km, which suggests a quartz-rich, granitic upper crustal composition. The northern half of the profile below the Altai Mountains and Junggar Accretional Belt has a higher Poisson's ratio of ?? = 0.26-0.27 to a depth of 30 km, indicative of an intermediate crustal composition. The entire 1100-km-long profile is underlain by a 15-30 km thick high velocity (6.9-7.0 km/s; ?? = 0.26-0.28) lower-crustal layer that we interpret to have a bulk composition of mafic granulite. At the southern end of the profile, a 5-km-thick midcrustal low-velocity layer (Vp = 5.9 km/s, ?? = 0.25) underlies the Tianshan and the region to the south, and may be indicative of a near-horizontal detachment interface. Pn velocities are ???7.7-7.8 km/s between the Tianshan and the Junggar basin, and ???7.9-8.0 km/s below the Altai Mountains and eastern margin of the Tarim basin. We interpret the consistent three-layer stratification of the crust to indicate that the crust has undergone partial melting and differentiation after Paleozoic terrane accretion. The thickness (50 km) of the crust appears to be related to compression resulting from the Indo-Asian collision.

Root morphology and mycorrhizal type strongly influence root production in nutrient hot spots of mixed forests

DOE PAGES

Chen, Weile; Koide, Roger T.; Eissenstat, David M.

2017-04-26

Plants compete for nutrients using a range of strategies. We investigated nutrient foraging within nutrient hot-spots simultaneously available to plant species with diverse root traits. We hypothesized that there would be more root proliferation by thin-root species than by thick-root species, and that root proliferation by thin-root species would limit root proliferation by thick-root species. We conducted a root ingrowth experiment in a temperate forest in eastern USA where root systems of different tree species could interact. Tree species varied in the thickness of their absorptive roots, and were associated with either ectomycorrhizal (EM) or arbuscular mycorrhizal (AM) fungi. Thus,more » there were thin- and thick-root AM and thin- and thick-root EM plant functional groups. Half the ingrowth cores were amended with organic nutrients (dried green leaves). Relative root length abundance, the proportion of total root length in a given soil volume occupied by a particular plant functional group, was calculated for the original root population and ingrowth roots after 6 months. The shift in relative root length abundance from original to ingrowth roots was positive in thin-root species but negative in thick-root species (p < .001), especially in unamended patches (AM: +6% vs. -7%; EM: +8% vs. -9%). Being thin-rooted may thus allow a species to more rapidly recolonize soil after a disturbance, which may influence competition for nutrients. Moreover, we observed that nutrient additions amplified the shift in root length abundance of thin over thick roots in AM trees (+13% vs. -14%), but not in EM trees (+1% vs -3%). In contrast, phospholipid fatty acid biomarkers suggested that EM fungal hyphae strongly proliferated in nutrient hot-spots whereas AM fungal hyphae exhibited only modest proliferation. We found no evidence that when growing in the shared patch, the proliferation of thin roots inhibited the growth of thick roots. As a result, knowledge of root morphology and mycorrhizal type of co-existing tree species may improve prediction of patch exploitation and nutrient acquisition in heterogeneous soils.« less

Root morphology and mycorrhizal type strongly influence root production in nutrient hot spots of mixed forests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Weile; Koide, Roger T.; Eissenstat, David M.

Plants compete for nutrients using a range of strategies. We investigated nutrient foraging within nutrient hot-spots simultaneously available to plant species with diverse root traits. We hypothesized that there would be more root proliferation by thin-root species than by thick-root species, and that root proliferation by thin-root species would limit root proliferation by thick-root species. We conducted a root ingrowth experiment in a temperate forest in eastern USA where root systems of different tree species could interact. Tree species varied in the thickness of their absorptive roots, and were associated with either ectomycorrhizal (EM) or arbuscular mycorrhizal (AM) fungi. Thus,more » there were thin- and thick-root AM and thin- and thick-root EM plant functional groups. Half the ingrowth cores were amended with organic nutrients (dried green leaves). Relative root length abundance, the proportion of total root length in a given soil volume occupied by a particular plant functional group, was calculated for the original root population and ingrowth roots after 6 months. The shift in relative root length abundance from original to ingrowth roots was positive in thin-root species but negative in thick-root species (p < .001), especially in unamended patches (AM: +6% vs. -7%; EM: +8% vs. -9%). Being thin-rooted may thus allow a species to more rapidly recolonize soil after a disturbance, which may influence competition for nutrients. Moreover, we observed that nutrient additions amplified the shift in root length abundance of thin over thick roots in AM trees (+13% vs. -14%), but not in EM trees (+1% vs -3%). In contrast, phospholipid fatty acid biomarkers suggested that EM fungal hyphae strongly proliferated in nutrient hot-spots whereas AM fungal hyphae exhibited only modest proliferation. We found no evidence that when growing in the shared patch, the proliferation of thin roots inhibited the growth of thick roots. As a result, knowledge of root morphology and mycorrhizal type of co-existing tree species may improve prediction of patch exploitation and nutrient acquisition in heterogeneous soils.« less

Shock destruction armor system

DOEpatents

Froeschner, Kenneth E.

1993-01-01

A shock destruction armor system is constructed and arranged to destroy the force of impact of a projectile by shock hydrodynamics. The armor system is designed to comprise a plurality of superimposed armor plates each preferably having a thickness less than five times the projectile's diameter and are preferably separated one-from-another by a distance at least equal to one-half of the projectile's diameter. The armor plates are effective to hydrodynamically and sequentially destroy the projectile. The armor system is particularly adapted for use on various military vehicles, such as tanks, aircraft and ships.

A study of photon interaction in some building materials: High-volume admixture of blast furnace slag into Portland cement

NASA Astrophysics Data System (ADS)

Kurudirek, Murat; Türkmen, İbrahim; Özdemir, Yüksel

2009-09-01

Total mass attenuation coefficients, mean free paths (MFP), half-value (HVT) and tenth-value (TVT) thicknesses of Portland cement and three mixtures have been calculated in function of the energy from 1 keV to 100 GeV. Both in the low- and high-energy region there were significant variations in those parameters where photoelectric process and pair production partially dominates, respectively. In general, the attenuation parameters were found to vary with chemical composition, density of given material and photon energy.

γ-ray spectroscopy of 209Tl

DOE PAGES

Amro, B. M. S.; Lister, C. J.; McCutchan, E. A.; ...

2017-01-30

Here, states in 209TI were populated using a multi-nucleon transfer reaction with a 136Xe beam impinging on a thick 208Pb target at E = 785 MeV. The beam was pulsed at 825 ns intervals in order to perform isomer decay spectroscopy. The known J π = 17/2 + isomer in 209TI was located at 1228(4) keV and measured to have a half-life of T 1/2 = 146(10) ns. A second isomer with J π = 13/2 + were found to have T 1/2 = 14(5) ns.

Gestational Heat Stress Alters Postnatal Offspring Body Composition Indices and Metabolic Parameters in Pigs

PubMed Central

Boddicker, Rebecca L.; Seibert, Jacob T.; Johnson, Jay S.; Pearce, Sarah C.; Selsby, Joshua T.; Gabler, Nicholas K.; Lucy, Matthew C.; Safranski, Timothy J.; Rhoads, Robert P.; Baumgard, Lance H.; Ross, Jason W.

2014-01-01

The study objectives were to test the hypothesis that heat stress (HS) during gestational development alters postnatal growth, body composition, and biological response to HS conditions in pigs. To investigate this, 14 first parity crossbred gilts were exposed to one of four environmental treatments (TNTN, TNHS, HSTN, or HSHS) during gestation. TNTN and HSHS dams were exposed to thermal neutral (TN, cyclical 18–22°C) or HS conditions (cyclical 28–34°C) during the entire gestation, respectively. Dams assigned to HSTN and TNHS treatments were heat-stressed for the first or second half of gestation, respectively. Postnatal offspring were exposed to one of two thermal environments for an acute (24 h) or chronic (five weeks) duration in either constant TN (21°C) or HS (35°C) environment. Exposure to chronic HS during their growth phase resulted in decreased longissimus dorsi cross-sectional area (LDA) in offspring from HSHS and HSTN treated dams whereas LDA was larger in offspring from dams in TNTN and TNHS conditions. Irrespective of HS during prepubertal postnatal growth, pigs from dams that experienced HS during the first half of gestation (HSHS and HSTN) had increased (13.9%) subcutaneous fat thickness compared to pigs from dams exposed to TN conditions during the first half of gestation. This metabolic repartitioning towards increased fat deposition in pigs from dams heat-stressed during the first half of gestation was accompanied by elevated blood insulin concentrations (33%; P = 0.01). Together, these results demonstrate HS during the first half of gestation altered metabolic and body composition parameters during future development and in biological responses to a subsequent HS challenge. PMID:25383953

Retinal Anatomy and Electrode Array Position in Retinitis Pigmentosa Patients after Argus II Implantation: an International Study.

PubMed

Gregori, Ninel Z; Callaway, Natalia F; Hoeppner, Catherine; Yuan, Alex; Rachitskaya, Aleksandra; Feuer, William; Ameri, Hossein; Arevalo, J Fernando; Augustin, Albert J; Birch, David G; Dagnelie, Gislin; Grisanti, Salvatore; Davis, Janet L; Hahn, Paul; Handa, James T; Ho, Allen C; Huang, Suber S; Humayun, Mark S; Iezzi, Raymond; Jayasundera, K Thiran; Kokame, Gregg T; Lam, Byron L; Lim, Jennifer I; Mandava, Naresh; Montezuma, Sandra R; Olmos de Koo, Lisa; Szurman, Peter; Vajzovic, Lejla; Wiedemann, Peter; Weiland, James; Yan, Jiong; Zacks, David N

2018-06-22

To assess the retinal anatomy and array position in the Argus II Retinal Prosthesis recipients. Prospective, non-comparative cohort study METHODS: Setting: international multicenter study PATIENTS: Argus II recipients enrolled in the Post-Market Surveillance Studies. Spectral-domain Optical Coherence Tomography images collected for the Surveillance Studies (NCT01860092 and NCT01490827) were reviewed. Baseline and postoperative macular thickness, electrode-retina distance (gap), optic disc-array overlap, and preretinal membrane presence were recorded at 1, 3, 6, and 12 months. Axial retinal thickness and axial gap along the array's long axis (a line between the tack and handle), maximal retinal thickness and maximal gap along a B-scan near the tack, midline, and handle. Thirty-three patients from 16 surgical sites in the United States and Germany were included. Mean axial retinal thickness increased from month 1 through month 12 at each location, but reached statistical significance only at the array midline (p-value=0.007). The rate of maximal thickness increase was highest near the array midline (slope=6.02, p=0.004), compared to the tack (slope=3.60, p<0.001) or the handle (slope=1.93, p=0.368). The mean axial and maximal gaps decreased over the study period, and the mean maximal gap size decrease was significant at midline (p=0.032). Optic disc-array overlap was seen in the minority of patients. Preretinal membranes were common before and after implantation. Progressive macular thickening under the array was common and corresponded to decreased electrode-retina gap over time. By month 12, the array was completely apposed to the macula in approximately half of the eyes. Copyright © 2018. Published by Elsevier Inc.

Wound-healing improvement by resurfacing split-thickness skin donor sites with thin split-thickness grafting.

PubMed

Bian, Yongqian; Sun, Chaofeng; Zhang, Xinping; Li, Yuejun; Li, Wangzhou; Lv, Xiaoxing; Li, Jing; Jiang, Li; Li, Jinqing; Feng, Jian; Li, Xue-Yong

2016-02-01

Split-thickness skin graft (STSG) donor site dressing has been controversial until now. Our study aimed to assess the patient comfort and wound-healing efficacy with the application of thin split-thickness skin grafts regrafting on STSG donor sites. One hundred ninety-two consecutive patients undergoing split-thickness skin grafting were included in the study, and the participants were randomly divided into the following three groups: group A was regrafted with thin STSGs and groups B and C were covered with occlusive hydrocellular dressing and paraffin gauze, respectively. The participants were compared according to the epithelialization time, pain and scar formation. The average time of epithelialization was 6.2 ± 1.1 days in group A, 11.1 ± 2.1 days in group B and 13.5 ± 2.5 days in group C. The pain scores on days 2 and 5 after operation were 2.3 ± 0.8 and 1.9 ± 0.8 in group A, 2.5 ± 1.1 and 3.9 ± 1.3 in group B, and 3.8 ± 1.4 and 5.9 ± 2.1 in group C. The scar scores at half a year and one year after operation were 4.3 ± 0.6 and 2.50 ± 0.6 in group A, 7.4 ± 0.6 and 6.2 ± 0.6 in group B, and 11.8 ± 0.4 and 10.9 ± 1.0 in group C, separately. The difference in the three groups was significant. Utilizing thin STSGs regrafting on donor sites could significantly shorten the epithelialization time, reduce pain and prevent hyperplastic scar formulation. Copyright © 2015. Published by Elsevier Ltd.

Evaluation of Methods to Estimate the Surface Downwelling Longwave Flux during Arctic Winter

NASA Technical Reports Server (NTRS)

Chiacchio, Marc; Francis, Jennifer; Stackhouse, Paul, Jr.

2002-01-01

Surface longwave radiation fluxes dominate the energy budget of nighttime polar regions, yet little is known about the relative accuracy of existing satellite-based techniques to estimate this parameter. We compare eight methods to estimate the downwelling longwave radiation flux and to validate their performance with measurements from two field programs in thc Arctic: the Coordinated Eastern Arctic Experiment (CEAREX ) conducted in the Barents Sea during the autumn and winter of 1988, and the Lead Experiment performed in the Beaufort Sea in the spring of 1992. Five of the eight methods were developed for satellite-derived quantities, and three are simple parameterizations based on surface observations. All of the algorithms require information about cloud fraction, which is provided from the NASA-NOAA Television and Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) polar pathfinder dataset (Path-P): some techniques ingest temperature and moisture profiles (also from Path-P): one-half of the methods assume that clouds are opaque and have a constant geometric thickness of 50 hPa, and three include no thickness information whatsoever. With a somewhat limited validation dataset, the following primary conclusions result: (1) all methods exhibit approximately the same correlations with measurements and rms differences, but the biases range from -34 W sq m (16% of the mean) to nearly 0; (2) the error analysis described here indicates that the assumption of a 50-hPa cloud thickness is too thin by a factor of 2 on average in polar nighttime conditions; (3) cloud-overlap techniques. which effectively increase mean cloud thickness, significantly improve the results; (4) simple Arctic-specific parameterizations performed poorly, probably because they were developed with surface-observed cloud fractions; and (5) the single algorithm that includes an estimate of cloud thickness exhibits the smallest differences from observations.

Propagation behavior of two transverse surface waves in a three-layer piezoelectric/piezomagnetic structure

NASA Astrophysics Data System (ADS)

Nie, Guoquan; Liu, Jinxi; Liu, Xianglin

2017-10-01

Propagation of transverse surface waves in a three-layer system consisting of a piezoelectric/piezomagnetic (PE/PM) bi-layer bonded on an elastic half-space is theoretically investigated in this paper. Dispersion relations and mode shapes for transverse surface waves are obtained in closed form under electrically open and shorted boundary conditions at the upper surface. Two transverse surface waves related both to Love-type wave and Bleustein-Gulyaev (B-G) type wave propagating in corresponding three-layer structure are discussed through numerically solving the derived dispersion equation. The results show that Love-type wave possesses the property of multiple modes, it can exist all of the values of wavenumber for every selected thickness ratios regardless of the electrical boundary conditions. The presence of PM interlayer makes the phase velocity of Love-type wave decrease. There exist two modes allowing the propagation of B-G type wave under electrically shorted circuit, while only one mode appears in the case of electrically open circuit. The modes of B-G type wave are combinations of partly normal dispersion and partly anomalous dispersion whether the electrically open or shorted. The existence range of mode for electrically open case is greatly related to the thickness ratios, with the thickness of PM interlayer increasing the wavenumber range for existence of B-G type wave quickly shortened. When the thickness ratio is large enough, the wavenumber range of the second mode for electrically shorted circuit is extremely narrow which can be used to remove as an undesired mode. The propagation behaviors and mode shapes of transverse surface waves can be regulated by the modification of the thickness of PM interlayer. The obtained results provide a theoretical prediction and basis for applications of PE-PM composites and acoustic wave devices.

Validity and reliability of a structured-light 3D scanner and an ultrasound imaging system for measurements of facial skin thickness.

PubMed

Lee, Kang-Woo; Kim, Sang-Hwan; Gil, Young-Chun; Hu, Kyung-Seok; Kim, Hee-Jin

2017-10-01

Three-dimensional (3 D)-scanning-based morphological studies of the face are commonly included in various clinical procedures. This study evaluated validity and reliability of a 3 D scanning system by comparing the ultrasound (US) imaging system versus the direct measurement of facial skin. The facial skin thickness at 19 landmarks was measured using the three different methods in 10 embalmed adult Korean cadavers. Skin thickness was first measured using the ultrasound device, then 3 D scanning of the facial skin surface was performed. After the skin on the left half of face was gently dissected, deviating slightly right of the midline, to separate it from the subcutaneous layer, and the harvested facial skin's thickness was measured directly using neck calipers. The dissected specimen was then scanned again, then the scanned images of undissected and dissected faces were superimposed using Morpheus Plastic Solution (version 3.0) software. Finally, the facial skin thickness was calculated from the superimposed images. The ICC value for the correlations between the 3 D scanning system and direct measurement showed excellent reliability (0.849, 95% confidence interval = 0.799-0.887). Bland-Altman analysis showed a good level of agreement between the 3 D scanning system and direct measurement (bias = 0.49 ± 0.49 mm, mean±SD). These results demonstrate that the 3 D scanning system precisely reflects structural changes before and after skin dissection. Therefore, an in-depth morphological study using this 3 D scanning system could provide depth data about the main anatomical structures of face, thereby providing crucial anatomical knowledge for utilization in various clinical applications. Clin. Anat. 30:878-886, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

16 year climatology of cirrus clouds over a tropical station in southern India using ground and space-based lidar observations

NASA Astrophysics Data System (ADS)

Pandit, A. K.; Gadhavi, H. S.; Venkat Ratnam, M.; Raghunath, K.; Rao, S. V. B.; Jayaraman, A.

2015-06-01

16 year (1998-2013) climatology of cirrus clouds and their macrophysical (base height, top height and geometrical thickness) and optical properties (cloud optical thickness) observed using a ground-based lidar over Gadanki (13.5° N, 79.2° E), India, is presented. The climatology obtained from the ground-based lidar is compared with the climatology obtained from seven and half years (June 2006-December 2013) of Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) observations. A very good agreement is found between the two climatologies in spite of their opposite viewing geometries and difference in sampling frequencies. Nearly 50-55% of cirrus clouds were found to possess geometrical thickness less than 2 km. Ground-based lidar is found to detect more number of sub-visible clouds than CALIOP which has implications for global warming studies as sub-visible cirrus clouds have significant positive radiative forcing. Cirrus clouds with mid-cloud temperatures between -50 to -70 °C have a mean geometrical thickness greater than 2 km in contrast to the earlier reported value of 1.7 km. Trend analyses reveal a statistically significant increase in the altitude of sub-visible cirrus clouds which is consistent with the recent climate model simulations. Also, the fraction of sub-visible cirrus cloud is found to be increasing during the last sixteen years (1998 to 2013) which has implications to the temperature and water vapour budget in the tropical tropopause layer.

Prevalence of scarred and dysfunctional myocardium in patients with heart failure of ischaemic origin: A cardiovascular magnetic resonance study

PubMed Central

2011-01-01

Background Cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE) can provide unique data on the transmural extent of scar/viability. We assessed the prevalence of dysfunctional myocardium, including partial thickness scar, which could contribute to left ventricular contractile dysfunction in patients with heart failure and ischaemic heart disease who denied angina symptoms. Methods We invited patients with ischaemic heart disease and a left ventricular ejection fraction < 50% by echocardiography to have LGE CMR. Myocardial contractility and transmural extent of scar were assessed using a 17-segment model. Results The median age of the 193 patients enrolled was 70 (interquartile range: 63-76) years and 167 (87%) were men. Of 3281 myocardial segments assessed, 1759 (54%) were dysfunctional, of which 581 (33%) showed no scar, 623 (35%) had scar affecting ≤50% of wall thickness and 555 (32%) had scar affecting > 50% of wall thickness. Of 1522 segments with normal contractile function, only 98 (6%) had evidence of scar on CMR. Overall, 182 (94%) patients had ≥1 and 107 (55%) patients had ≥5 segments with contractile dysfunction that had no scar or ≤50% transmural scar suggesting viability. Conclusions In this cohort of patients with left ventricular systolic dysfunction and ischaemic heart disease, about half of all segments had contractile dysfunction but only one third of these had > 50% of the wall thickness affected by scar, suggesting that most dysfunctional segments could improve in response to an appropriate intervention. PMID:21936915

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures

PubMed Central

Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Zhou, Shizhong; Li, Guoqiang

2015-01-01

2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.0%, very smooth surface with a RMS surface roughness of 3.0 nm, full-width at half-maximums (FWHMs) for GaN(0002) and GaN(102) X-ray rocking curves of 0.7° and 0.8°, respectively, and sharp and abrupt AlN/GaN hetero-interfaces. With the increase in the growth temperature from 550 to 850 °C, the surface morphology, crystalline quality, and interfacial property of as-grown ~300 nm-thick GaN films are gradually improved at first and then decreased. Based on the characterizations, the corresponding growth mechanisms of GaN films grown on AlN/Si hetero-structures by PLD with various growth temperatures are hence proposed. This work would be beneficial to understanding the further insight of the GaN films grown on Si(111) substrates by PLD for the application of GaN-based devices. PMID:26563573

Perpendicular magnetic anisotropy and magnetization dynamics in oxidized CoFeAl films

PubMed Central

Wu, Di; Zhang, Zhe; Li, Le; Zhang, Zongzhi; Zhao, H. B.; Wang, J.; Ma, B.; Jin, Q. Y.

2015-01-01

Half-metallic Co-based full-Heusler alloys with perpendicular magnetic anisotropy (PMA), such as Co2FeAl in contact with MgO, are receiving increased attention recently due to its full spin polarization for high density memory applications. However, the PMA induced by MgO interface can only be realized for very thin magnetic layers (usually below 1.3 nm), which would have strong adverse effects on the material properties of spin polarization, Gilbert damping parameter, and magnetic stability. In order to solve this issue, we fabricated oxidized Co50Fe25Al25 (CFAO) films with proper thicknesses without employing the MgO layer. The samples show controllable PMA by tuning the oxygen pressure (PO2) and CFAO thickness (tCFAO), large perpendicular anisotropy field of ~8.0 kOe can be achieved at PO2 = 12% for the sample of tCFAO = 2.1 nm or at PO2 = 7% for tCFAO = 2.8 nm. The loss of PMA at thick tCFAO or high PO2 results mainly from the formation of large amount of CoFe oxides, which are superparamagnetic at room temperature but become hard magnetic at low temperatures. The magnetic CFAO films, with strong PMA in a relatively wide thickness range and small intrinsic damping parameter below 0.028, would find great applications in developing advanced spintronic devices. PMID:26190066

Solid surface combustion experiment flame spread in a quiescent, microgravity environment implications of spread rate and flame structure

NASA Technical Reports Server (NTRS)

Bundy, Matthew; West, Jeff; Thomas, Peter C.; Bhattacharjee, Subrata; Tang, Lin; Altenkirch, Robert A.; Sacksteder, Kurt

1995-01-01

A unique environment in which flame spreading, a phenomenon of fundamental, scientific interest, has importance to fire safety is that of spacecraft in which the gravitational acceleration is low compared with that of the Earth, i.e., microgravity. Experiments aboard eight Space Shuttle missions between October 1990 and February 1995 were conducted using the Solid Surface Combustion Experiment (SSCE) payload apparatus in an effort to determine the mechanisms of gas-phase flame spread over solid fuel surfaces in the absence of any buoyancy induced or externally imposed oxidizer flow. The overall SSCE effort began in December of 1984. The SSCE apparatus consists of a sealed container, approximately 0.039 cu m, that is filled with a specified O2/N2 mixture at a prescribed pressure. Five of the experiments used a thin cellulosic fuel, ashless filter paper, 3 cm wide x 10 cm long, 0.00825 cm half-thickness, ignited in five different ambient conditions. Three of the experiments, the most recent, used thick polymethylmethacrylate (PMMA) samples 0.635 cm wide x 2 cm long, 0.32 cm half-thickness. Three experiments, STS 41, 40 and 43, were designed to evaluate the effect of ambient pressure on flame spread over the thin cellulosic fuel while flights STS 50 and 47 were at the same pressure as two of the earlier flights but at a lower oxygen concentration in order to evaluate the effect of ambient oxygen level on the flame spread process at microgravity. For the PMMA flights, two experiments, STS 54 and 63, were at the same pressure but different oxygen concentrations while STS 64 was at the same oxygen concentration as STS 63 but at a higher pressure. Two orthogonal views of the experiments were recorded on 16 mm cine-cameras operating at 24 frames/s. In addition to filmed images of the side view of the flames and surface view of the burning samples, solid- and gas-phase temperatures were recorded using thermocouples. The experiment is battery powered and follows an automated sequence upon activation by the Shuttle Crew. In this study we separate the SSCE data into two groups according to the fuel type: (1) thin cellulose; and (2) thick PMMA. The experimental spread rates are compared with prediction from a number of models in an effort to uncover the important physics that characterize microgravity flame spread. Both steady and unsteady solutions are employed to explore the flame evolution, especially for thick fuels. Finally, the flame structure in downward spread is compared with the microgravity flame structure and modeling results to delineate the difference between the two configurations and the influence of normal gravity.

Gravity anomalies and flexure of the lithosphere at the Middle Amazon Basin, Brazil

NASA Astrophysics Data System (ADS)

Nunn, Jeffrey A.; Aires, Jose R.

1988-01-01

The Middle Amazon Basin is a large Paleozoic sedimentary basin on the Amazonian craton in South America. It contains up to 7 km of mainly shallow water sediments. A chain of Bouguer gravity highs of approximately +40 to +90 mGals transects the basin roughly coincident with the axis of maximum thickness of sediment. The gravity highs are flanked on either side by gravity lows of approximately -40 mGals. The observed gravity anomalies can be explained by a steeply sided zone of high density in the lower crust varying in width from 100 to 200 km wide. Within this region, the continental crust has been intruded/replaced by more dense material to more than half its original thickness of 45-50 km. The much wider sedimentary basin results from regional compensation of the subsurface load and the subsequent load of accumulated sediments by flexure of the lithosphere. The observed geometry of the basin is consistent with an elastic lithosphere model with a mechanical thickness of 15-20 km. Although this value is lower than expected for a stable cratonic region of Early Proterozoic age, it is within the accepted range of effective elastic thicknesses for the earth. Rapid subsidence during the late Paleozoic may be evidence of a second tectonic event or lithospheric relaxation which could lower the effective mechanical thickness of the lithosphere. The high-density zone in the lower crust, as delineated by gravity and flexural modeling, has a complex sinuous geometry which is narrow and south of the axis of maximum sediment thickness on the east and west margins and wide and offset to the north in the center of the basin. The linear trough geometry of the basin itself is a result of smoothing by regional compensation of the load in the lower crust.

The Lunar Crust: Global Structure and Signature of Major Basins

NASA Technical Reports Server (NTRS)

Neumann, Gregory A.; Zuber, Maria T.; Smith, David E.; Lemoine, Frank G.

1996-01-01

New lunar gravity and topography data from the Clementine Mission provide a global Bouguer anomaly map corrected for the gravitational attraction of mare fill in mascon basins. Most of the gravity signal remaining after corrections for the attraction of topography and mare fill can be attributed to variations in depth to the lunar Moho and therefore crustal thickness. The large range of global crustal thickness (approx. 20-120 km) is indicative of major spatial variations in melting of the lunar exterior and/or significant impact-related redistribution. The 6l-km average crustal thickness, constrained by a depth-to-Moho measured during the Apollo 12 and 14 missions, is preferentially distributed toward the farside, accounting for much of the offset in center-of-figure from the center-of-mass. While the average farside thickness is 12 km greater than the nearside, the distribution is nonuniform, with dramatic thinning beneath the farside, South Pole-Aitken basin. With the global crustal thickness map as a constraint, regional inversions of gravity and topography resolve the crustal structure of major mascon basins to half wavelengths of 150 km. In order to yield crustal thickness maps with the maximum horizontal resolution permitted by the data, the downward continuation of the Bouguer gravity is stabilized by a three- dimensional, minimum-slope and curvature algorithm. Both mare and non-mare basins are characterized by a central upwarped moho that is surrounded by rings of thickened crust lying mainly within the basin rims. The inferred relief at this density interface suggests a deep structural component to the surficial features of multiring lunar impact basins. For large (greater than 300 km diameter) basins, moho relief appears uncorrelated with diameter, but is negatively correlated with basin age. In several cases, it appears that the multiring structures were out of isostatic equilibrium prior to mare emplacement, suggesting that the lithosphere was strong enough to maintain their state of stress to the present.

Long-term trend analysis and climatology of tropical cirrus clouds using 16 years of lidar data set over Southern India

NASA Astrophysics Data System (ADS)

Pandit, A. K.; Gadhavi, H. S.; Venkat Ratnam, M.; Raghunath, K.; Rao, S. V. B.; Jayaraman, A.

2015-12-01

Sixteen-year (1998-2013) climatology of cirrus clouds and their macrophysical (base height, top height and geometrical thickness) and optical properties (cloud optical thickness) observed using a ground-based lidar over Gadanki (13.5° N, 79.2° E), India, is presented. The climatology obtained from the ground-based lidar is compared with the climatology obtained from 7 and a half years (June 2006-December 2013) of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations. A very good agreement is found between the two climatologies in spite of their opposite viewing geometries and the differences in sampling frequencies. Nearly 50-55 % of cirrus clouds were found to possess geometrical thickness less than 2 km. Ground-based lidar is found to detect a higher number of sub-visible clouds than CALIOP which has implications for global warming studies as sub-visible cirrus clouds have significant positive radiative forcing. Cirrus clouds with mid-cloud temperatures between -50 to -70 °C have a mean geometrical thickness greater than 2 km in contrast to the earlier reported value of 1.7 km. Trend analyses reveal a statistically significant increase in the altitude of sub-visible cirrus clouds which is consistent with the recent climate model simulations. The mid-cloud altitude of sub-visible cirrus clouds is found to be increasing at the rate of 41 ± 21 m year-1. Statistically significant decrease in optical thickness of sub-visible and thick cirrus clouds is observed. Also, the fraction of sub-visible cirrus cloud is found to have increased by 9 % in the last 16 years (1998 to 2013). This increase is mainly compensated by a 7 % decrease in thin cirrus cloud fraction. This has implications for the temperature and water vapour budget in the tropical tropopause layer.

MO-FG-CAMPUS-IeP2-01: Characterization of Beam Shaping Filters and Photon Spectra From HVL Profiles in CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bujila, R; Royal Institute of Technology, Stockholm; Kull, L

Purpose: Advanced dosimetry in CT (e.g. the Monte Carlo method) requires an accurate characterization of the shaped filter and radiation quality used during a scan. The purpose of this work was to develop a method where half value layer (HVL) profiles along shaped filters could be made. From the HVL profiles the beam shaping properties and effective photon spectrum for a particular scan can be inferred. Methods: A measurement rig was developed to allow determinations of the HVL under a scatter-free narrow-beam geometry and constant focal spot to ionization chamber distance for different fan angles. For each fan angle themore » HVL is obtained by fitting the transmission of radiation through different thicknesses of an Al absorber (type 1100) using an appropriate model. The effective Al thickness of shaped filters and effective photon spectra are estimated using a model of photon emission from a Tungsten anode. This method is used to obtain the effective photon spectra and effective Al thickness of shaped filters for a CT scanner recently introduced to the market. Results: This study resulted in a set of effective photon spectra (central ray) for each kVp along with effective Al thicknesses of the different shaped filters. The effective photon spectra and effective Al thicknesses of shaped filters were used to obtain numerically approximated HVL profiles and compared to measured HVL profiles (mean absolute percentage error = 0.02). The central axis HVL found in the vendor’s technical documentation were compared to approximated HVL values (mean absolute percentage error = 0.03). Conclusion: This work has resulted in a unique method of measuring HVL profiles along shaped filters in CT. Further the effective photon spectra and the effective Al thicknesses of shaped filters that were obtained can be incorporated into Monte Carlo simulations.« less

Faraday effect on the Rb D{sub 1} line in a cell with a thickness of half the wavelength of light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sargsyan, A., E-mail: sarmeno@mail.ru, E-mail: sargsyanarmen85@gmail.com; Pashayan-Leroy, Y.; Leroy, C.

2016-09-15

The rotation of the radiation polarization plane in a longitudinal magnetic field (Faraday effect) on the D{sub 1} line in atomic Rb vapor has been studied with the use of a nanocell with the thickness L varying in the range of 100–900 nm. It has been shown that an important parameter is the ratio L/λ, where λ = 795 nm is the wavelength of laser radiation resonant with the D{sub 1} line. The best parameters of the signal of rotation of the radiation polarization plane have been obtained at the thickness L = λ/2 = 397.5 nm. The fabricated nanocellmore » had a large region with such a thickness. The spectral width of the signal reached at the thickness L = 397.5 nm is approximately 30 MHz, which is much smaller than the spectral width (≈ 500 MHz) reached with ordinary cells with a thickness in the range of 1–100 mm. The parameters of the Faraday rotation signal have been studied as functions of the temperature of the nanocell, the laser power, and the magnetic field strength. The signal has been reliably detected at the laser power P{sub L} ≥ 1 μW, magnetic field strength B ≥ 0.5 G, and the temperature of the nanocell T ≥ 100°C. It has been shown that the maximum rotation angle of the polarization plane in the longitudinal magnetic field is reached on the F{sub g} = 3 → F{sub e} = 2 transition of the {sup 85}Rb atom. The spectral profile of the Faraday rotation signal has a specific shape with a sharp peak, which promotes its applications. In particular, Rb atomic transitions in high magnetic fields about 1000 G are split into a large number of components, which are completely spectrally resolved and allow the study of the behavior of an individual transition.« less

3D enamel thickness in Neandertal and modern human permanent canines.

PubMed

Buti, Laura; Le Cabec, Adeline; Panetta, Daniele; Tripodi, Maria; Salvadori, Piero A; Hublin, Jean-Jacques; Feeney, Robin N M; Benazzi, Stefano

2017-12-01

Enamel thickness figures prominently in studies of human evolution, particularly for taxonomy, phylogeny, and paleodietary reconstruction. Attention has focused on molar teeth, through the use of advanced imaging technologies and novel protocols. Despite the important results achieved thus far, further work is needed to investigate all tooth classes. We apply a recent approach developed for anterior teeth to investigate the 3D enamel thickness of Neandertal and modern human (MH) canines. In terms of crown size, the values obtained for both upper and lower unworn/slightly worn canines are significantly greater in Neandertals than in Upper Paleolithic and recent MH. The 3D relative enamel thickness (RET) is significantly lower in Neandertals than in MH. Moreover, differences in 3D RET values between the two groups appear to decrease in worn canines beginning from wear stage 3, suggesting that both the pattern and the stage of wear may have important effects on the 3D RET value. Nevertheless, the 3D average enamel thickness (AET) does not differ between the two groups. In both groups, 3D AET and 3D RET indices are greater in upper canines than in lower canines, and overall the enamel is thicker on the occlusal half of the labial aspect of the crown, particularly in MH. By contrast, the few early modern humans investigated show the highest volumes of enamel while for all other components of 3D enamel, thickness this group holds an intermediate position between Neandertals and recent MH. Overall, our study supports the general findings that Neandertals have relatively thinner enamel than MH (as also observed in molars), indicating that unworn/slightly worn canines can be successfully used to discriminate between the two groups. Further studies, however, are needed to understand whether these differences are functionally related or are the result of pleiotropic or genetic drift effects. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Optical coherence tomography of the effects of stromal hydration on clear corneal incision architecture.

PubMed

Calladine, Daniel; Tanner, Vaughan

2009-08-01

To evaluate the effects of stromal hydration on clear corneal incision (CCI) architecture immediately after surgery using anterior segment optical coherence tomography (AS-OCT). Department of Ophthalmology, Royal Berkshire Hospital, Reading, United Kingdom. Clear corneal incisions in adult eyes were examined using a Visante AS-OCT imaging system within 1 hour of surgery. Half the CCIs had stromal hydration with a balanced salt solution and half did not. Incisions were made with a 2.75 mm steel keratome. Intraocular pressure (IOP) was measured within 90 minutes after surgery. The CCI length and corneal thickness at the CCI site were measured using software built into the AS-OCT system. Thirty CCIs were evaluated. Stromal hydration significantly increased the measured CCI length (P<.05, t test); this was the result of a trend toward increased corneal thickness at the CCI site with hydration (P<.1, t test). The mean CCI length was 1.69 mm +/- 0.27 (SD) (range 1.31 to 2.32 mm) with hydration and 1.51 +/- 0.23 mm (range 1.30 to 1.95 mm) without hydration. The mean IOP was 20.9 +/- 8.18 mm Hg and 15.8 +/- 8.20 mm Hg, respectively. The IOP tended to be higher with hydration (P<.1, t test). Local detachment of Descemet membrane was more likely with stromal hydration (63%) than without (25%). Stromal hydration significantly increased CCI length and tended to leave the eye with a higher early postoperative IOP, showing the importance of taking stromal hydration into account when designing similar OCT studies of CCI architecture.

Stratigraphy and depositional environment of upper Cambrian Red Lion Formation, southwestern Montana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayden, L.L.; Bush, J.H.

1987-08-01

The Red Lion Formation was examined along a northwest-southeast transect from Missoula to Bozeman, Montana. Lateral equivalents are the Snowy Range Formation east of Bozeman and the upper Fishtrap Dolomite in northwest Montana. The basal Dry Creek Member (0-5 m) consists of shale interbedded with quartz siltstones and sandstones. The overlying Sage Member, up to 115 meters in thickness, is characterized by ribbon carbonate beds containing lime mudstone and quartzose calcisiltite couplets arranged in fining-upward sequences 1-5 cm thick. Couplets are interlayered in places with thin (1-5 cm) to medium bedded (6-70 cm) units of laminated and non-laminated calcareous siltstones,more » flat-pebble conglomerates, trilobite packstones, cryptalgal boundstones, bioturbated lime mudstones and shales. In places, the upper Sage contains columnar and domal algal features. The Red Lion Formation is considered to be one Grand Cycle with the Dry Creek representing a lower inner detrital half-cycle and the Sage an upper carbonate half-cycle. The Dry Creek formed as the result of a westward clastic pulse from the inner detrital belt across an intrashelf basin onto outer middle carbonate peritidal complexes of the underlying Pilgrim Formation. Lower Sage ribbon rocks were deposited in storm-crossed, below wave-base areas. During deposition of the upper Sage, shallowing formed discontinuous algal-peritidal complexes over much of western and central Montana. These complexes were less extensive than earlier Cambrian buildups owing to slower rates of basin subsidence and clastic input suppressing carbonate production.« less

Temporal properties of compensation for positive and negative spectacle lenses in chicks.

PubMed

Zhu, Xiaoying; Wallman, Josh

2009-01-01

Chicks' eyes rapidly compensate for defocus imposed by spectacle lenses by changing their rate of elongation and their choroidal thickness. Compensation may involve internal emmetropization signals that rise and become saturated during episodes of lens wear and decline between episodes. The time constants of these signals were measured indirectly by measuring the magnitude of lens compensation in refractive error and ocular dimensions as a function of the duration of episodes and the intervals between the episodes. First, in a study of how quickly the signals rose, chicks were subjected to episodes of lens-wear of various durations (darkness otherwise), and the duration required to cause a half-maximum effect (rise-time) was estimated. Second, in a study of how quickly the signals declined, various dark intervals were imposed between episodes of lens-wear, and the interval required to reduce the maximum effect by half (fall-time) was estimated. The rise-times for the rate of ocular elongation and choroidal thickness were approximately 3 minutes for positive and negative lenses. The fall-times had a broad range of time courses: Positive lenses caused an enduring inhibition of ocular elongation with a fall-time of 24 hours. In contrast, negative lenses caused a transient stimulation of ocular elongation with a fall-time of 0.4 hour. The effects of episodes of defocus rise rapidly with episode duration to an asymptote and decline between episodes, with the time course depending strongly on the sign of defocus and the ocular component. The complex etiology of human myopia may reflect these temporal properties.

Rapid extension in an Eocene volcanic arc: Structure and paleogeography of an intra-arc half graben in central Idaho

USGS Publications Warehouse

Janecke, S.U.; Hammond, B.F.; Snee, L.W.; Geissman, J.W.

1997-01-01

A study of extension, volcanism, and sedimentation in the middle Eocene Panther Creek half graben in central Idaho shows that it formed rapidly during an episode of voluminous volcanism. The east-southeast-tilted Panther Creek half graben developed across the northeast edge of the largest cauldron complex of the Challis volcanic field and along the northeast-trending Trans-Challis fault zone. Two normal fault systems bound the east side of the half graben. One fault system strikes northeast, parallel to the Trans-Challis fault zone, and the other strikes north to northwest. The geometry of the basin-fill deposits shows that movement on these two normal fault systems was synchronous and that both faults controlled the development of the Panther Creek half graben. Strikes of the synextension volcanic and sedimentary rocks are similar throughout the half graben, whereas dips decrease incrementally upsection from as much as 60?? to less than 10??. Previous K-Ar dates and a new 40Ar/39Ar plateau date from the youngest widespread tuff in the basin suggest that most of basin formation spanned 3 m.y. between about 47.7 Ma and 44.5 Ma. As much as 6.5 km of volcanic and sedimentary rocks were deposited during that time. Although rates of extension and subsidence were very high, intense volcanic activity continually filled the basin with ash-flow tuffs, outpacing subsidence and sedimentation, until the end of basin development. After the abrupt end of Challis volcanism, locally derived pebble to boulder conglomerate and massive, reworked ash accumulated in the half graben. These sedimentary rocks make up a small part of the basin fill in the Panther Creek half graben and were derived mainly from Proterozoic metasedimentary rocks uplifted in the footwall of the basin. The east-southeast tilt of the sedimentary rocks, their provenance and coarse grain size, and the presence of a gravity slide block derived from tilted volcanic rocks in the hanging wall attest to continued tectonism during conglomerate deposition. Provenance data from the sedimentary rocks imply that the highland in the footwall of the Panther Creek half graben was never thickly blanketed by synex-tension volcanic rocks, despite intense volcanic activity. Analysis of the Panther Creek half graben and other intra-arc rift basins supports previous interpretations that relative rates of volcanism and subsidence control the proportion of volcanic rocks deposited in intra-arc rifts.

Realisation of magnetically and atomically abrupt half-metal/semiconductor interface: Co2FeSi0.5Al0.5/Ge(111)

PubMed Central

Nedelkoski, Zlatko; Kuerbanjiang, Balati; Glover, Stephanie E.; Sanchez, Ana M.; Kepaptsoglou, Demie; Ghasemi, Arsham; Burrows, Christopher W.; Yamada, Shinya; Hamaya, Kohei; Ramasse, Quentin M.; Hasnip, Philip J.; Hase, Thomas; Bell, Gavin R.; Hirohata, Atsufumi; Lazarov, Vlado K.

2016-01-01

Halfmetal-semiconductor interfaces are crucial for hybrid spintronic devices. Atomically sharp interfaces with high spin polarisation are required for efficient spin injection. In this work we show that thin film of half-metallic full Heusler alloy Co2FeSi0.5Al0.5 with uniform thickness and B2 ordering can form structurally abrupt interface with Ge(111). Atomic resolution energy dispersive X-ray spectroscopy reveals that there is a small outdiffusion of Ge into specific atomic planes of the Co2FeSi0.5Al0.5 film, limited to a very narrow 1 nm interface region. First-principles calculations show that this selective outdiffusion along the Fe-Si/Al atomic planes does not change the magnetic moment of the film up to the very interface. Polarized neutron reflectivity, x-ray reflectivity and aberration-corrected electron microscopy confirm that this interface is both magnetically and structurally abrupt. Finally, using first-principles calculations we show that this experimentally realised interface structure, terminated by Co-Ge bonds, preserves the high spin polarization at the Co2FeSi0.5Al0.5/Ge interface, hence can be used as a model to study spin injection from half-metals into semiconductors. PMID:27869132

Methodology for Assessing the Probability of Corrosion in Concrete Structures on the Basis of Half-Cell Potential and Concrete Resistivity Measurements

PubMed Central

2013-01-01

In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. Potential E corr and concrete resistivity ρ in each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures. PMID:23766706

Opening of an interface flaw in a layered elastic half-plane under compressive loading

NASA Technical Reports Server (NTRS)

Kennedy, J. M.; Fichter, W. B.; Goree, J. G.

1984-01-01

A static analysis is given of the problem of an elastic layer perfectly bonded, except for a frictionless interface crack, to a dissimilar elastic half-plane. The free surface of the layer is loaded by a finite pressure distribution directly over the crack. The problem is formulated using the two dimensional linear elasticity equations. Using Fourier transforms, the governing equations are converted to a pair of coupled singular integral equations. The integral equations are reduced to a set of simultaneous algebraic equations by expanding the unknown functions in a series of Jacobi polynomials and then evaluating the singular Cauchy-type integrals. The resulting equations are found to be ill-conditioned and, consequently, are solved in the least-squares sense. Results from the analysis show that, under a normal pressure distribution on the free surface of the layer and depending on the combination of geometric and material parameters, the ends of the crack can open. The resulting stresses at the crack-tips are singular, implying that crack growth is possible. The extent of the opening and the crack-top stress intensity factors depend on the width of the pressure distribution zone, the layer thickness, and the relative material properties of the layer and half-plane.

Quantitative analysis of airway abnormalities in CT

NASA Astrophysics Data System (ADS)

Petersen, Jens; Lo, Pechin; Nielsen, Mads; Edula, Goutham; Ashraf, Haseem; Dirksen, Asger; de Bruijne, Marleen

2010-03-01

A coupled surface graph cut algorithm for airway wall segmentation from Computed Tomography (CT) images is presented. Using cost functions that highlight both inner and outer wall borders, the method combines the search for both borders into one graph cut. The proposed method is evaluated on 173 manually segmented images extracted from 15 different subjects and shown to give accurate results, with 37% less errors than the Full Width at Half Maximum (FWHM) algorithm and 62% less than a similar graph cut method without coupled surfaces. Common measures of airway wall thickness such as the Interior Area (IA) and Wall Area percentage (WA%) was measured by the proposed method on a total of 723 CT scans from a lung cancer screening study. These measures were significantly different for participants with Chronic Obstructive Pulmonary Disease (COPD) compared to asymptomatic participants. Furthermore, reproducibility was good as confirmed by repeat scans and the measures correlated well with the outcomes of pulmonary function tests, demonstrating the use of the algorithm as a COPD diagnostic tool. Additionally, a new measure of airway wall thickness is proposed, Normalized Wall Intensity Sum (NWIS). NWIS is shown to correlate better with lung function test values and to be more reproducible than previous measures IA, WA% and airway wall thickness at a lumen perimeter of 10 mm (PI10).

Propagation of Love waves with surface effects in an electrically-shorted piezoelectric nanofilm on a half-space elastic substrate.

PubMed

Zhang, Sijia; Gu, Bin; Zhang, Hongbin; Feng, Xi-Qiao; Pan, Rongying; Alamusi; Hu, Ning

2016-03-01

The propagation of Love waves in the structure consisting of a nanosized piezoelectric film and a semi-infinite elastic substrate is investigated in the present paper with the consideration of surface effects. In our analysis, surface effects are taken into account in terms of the surface elasticity theory and the electrically-shorted conditions are adopted on the free surface of the piezoelectric film and the interface between the film and the substrate. This work focuses on the new features in the dispersion relations of different modes due to surface effects. It is found that with the existence of surface effects, the frequency dispersion of Love waves shows the distinct dependence on the thickness and the surface constants when the film thickness reduces to nanometers. In general, phase velocities of all dispersion modes increase with the decrease of the film thickness and the increase of the surface constants. However, surface effects play different functions in the frequency dispersions of different modes, especially for the first mode dispersion. Moreover, different forms of Love waves are observed in the first mode dispersion, depending on the presence of the surface effects on the surface and the interface. Copyright © 2015 Elsevier B.V. All rights reserved.

Shearographic Non-destructive Evaluation of Space Shuttle Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Davis, Christopher K.; Hooker, Jeffery A.; Simmons, Stephen A.; Tenbusch, Kenneth E.

1995-01-01

Preliminary results of shearographic inspections of the shuttle external tank (ET) spray-on foam insulation (SOFI) and solid rocket booster (SRB) Marshall sprayable ablative (MSA-2) epoxy-cork thermal protection systems (TPS) are presented. Debonding SOFI or MSA-2 damage the orbiter 'belly' tile and exposes the ET/SRB to thermal loading. Previous work with the ET/SRB showed promising results with shearography. The first area investigated was the jack pad close-out, one of many areas on the ET where foam is applied at KSC. Voids 0.375 inch were detected in 1.75 inch thick foam using a pressure reduction of less than 0.4 psi. Of primary interest are areas of the ET that directly face the orbiter tile TPS. It is estimated that 90% of tile TPS damage on the orbiter 'belly' results from debonding SOFI during ascent. Test panels modeling these areas were manufactured with programmed debonds to determine the sensitivity of shearography as a function of debond size, SOFI thickness and vacuum. Results show repeatable detection of debonds with a diameter approximately half the SOFI thickness at less than 0.4 psi pressure reduction. Preliminary results are also presented on inspections of MSA-2 and the remote manipulator system (RMS) honeycomb material.

Shearographic non-destructive evaluation of space shuttle thermal protection systems

NASA Technical Reports Server (NTRS)

Hooker, Jeffrey A.; Simmons, Stephen M.; Davis, Christopher K.; Tenbusch, Kenneth E.

1995-01-01

Preliminary results of shearographic inspections of the shuttle external tank (ET) spray-on foam insulation (SOFI) and solid rocket booster (SRB) Marshall sprayable ablative (MSA-2) epoxy-cork thermal protection systems (TPS) are presented. Debonding SOFI or MSA-2 damage the orbiter 'belly' tile and exposes the ET/SRB to thermal loading. Previous work with the ET/SRB showed promising results with shearography. The first area investigated was the jack pad close-out, one of many areas on the ET where foam is applied at KSC. Voids 0.375 inch were detected in 1.75 inch thick foam using a pressure reduction of less than 0.4 psi. Of primary interest are areas of the ET that directly face the orbiter tile TPS. It is estimated that 90% of tile TPS damage on the orbiter 'belly' results from debonding SOFI during ascent. Test panels modeling these areas were manufactured with programmed debonds to determine the sensitivity of shearography as a function of debond size, SOFI thickness and vacuum. Results show repeatable detection of debonds with a diameter approximately half the SOFI thickness at less than 0.4 psi pressure reduction. Preliminary results are also presented on inspections of MSA-2 and the remote manipulator system (RMS) honeycomb material

Membranous appendices of spherosomes (oleosomes) : Possible role in fat utilization in germinating oil seeds.

PubMed

Wanner, G; Theimer, R R

1978-01-01

Spherosomes (oleosomes) of cotyledons of rape (Brassica napus L.), sunflower (Helianthus annuus L.), and watermelon (Citrullus vulgaris, Schrad.) seedlings are delimited by a "half unit membrane" that appears to be continuous with each of the osmiophilic layers of a tripartite unit membrane forming a handlelike appendix of the spherosomes. Prior to any noticeable utilization of the spherosomal storage fat, ribosomes were found to be attached to these "handles". At later stages appendices of the spherosomes are smooth, showing a diameter of about 22 nm that greatly exceeds the thickness of any other unit membrane profiles identical in structure and diameter osomes appears to be continuous with the thick lipid layer of the handles. In intermediate stages of fat depletion the spherosomal bodies become invaginated with cytoplasmic material. Finally vesicles with cytoplasmic contents surrounded by a membrane with a typically thick lipid layer are left in the cells. Membrane profiles indentical in structure and diameter to the spherosomal appendices were also present in electron micrographs of the lipolytic membrane fraction recovered from sucrose density gradients after centrifugation of a microsomal cell fraction. The ultrastructural observations are taken for evidence that the spherosomal appendices represent the lipase-carrying membranes isolated previously (Theimer and Rosnitschek, 1978). A novel hypothesis for development and utilization of fat-storing spherosomes is also proposed.

Imaging exciton–polariton transport in MoSe2 waveguides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, F.; Luan, Y.; Scott, M. E.

The exciton polariton (EP), a half-light and half-matter quasiparticle, is potentially an important element for future photonic and quantum technologies1-4. It provides both strong light-matter interactions and long-distance propagation that is necessary for applications associated with energy or information transfer. Recently, strongly-coupled cavity EPs at room temperature have been demonstrated in van der Waals (vdW) materials due to their strongly-bound excitons5-9. Here we report a nano-optical imaging study of waveguide EPs in MoSe2, a prototypical vdW semiconductor. The measured propagation length of the EPs is sensitive to the excitation photon energy and reaches over 12 μm. The polariton wavelength canmore » be conveniently altered from 600 nm down to 300 nm by controlling the waveguide thickness. Furthermore, we found an intriguing back-bending polariton dispersion close to the exciton resonance. The observed EPs in vdW semiconductors could be useful in future nanophotonic circuits operating in the near-infrared to visible spectral regions.« less

Imaging exciton–polariton transport in MoSe2 waveguides

DOE PAGES

Hu, F.; Luan, Y.; Scott, M. E.; ...

2017-05-08

The exciton polariton (EP), a half-light and half-matter quasiparticle, is potentially an important element for future photonic and quantum technologies1-4. It provides both strong light-matter interactions and long-distance propagation that is necessary for applications associated with energy or information transfer. Recently, strongly-coupled cavity EPs at room temperature have been demonstrated in van der Waals (vdW) materials due to their strongly-bound excitons5-9. Here we report a nano-optical imaging study of waveguide EPs in MoSe2, a prototypical vdW semiconductor. The measured propagation length of the EPs is sensitive to the excitation photon energy and reaches over 12 μm. The polariton wavelength canmore » be conveniently altered from 600 nm down to 300 nm by controlling the waveguide thickness. Furthermore, we found an intriguing back-bending polariton dispersion close to the exciton resonance. The observed EPs in vdW semiconductors could be useful in future nanophotonic circuits operating in the near-infrared to visible spectral regions.« less

Catalyst evaluation for oxygen reduction reaction in concentrated phosphoric acid at elevated temperatures

NASA Astrophysics Data System (ADS)

Hu, Yang; Jiang, Yiliang; Jensen, Jens Oluf; Cleemann, Lars N.; Li, Qingfeng

2018-01-01

Phosphoric acid is the common electrolyte for high-temperature polymer electrolyte fuel cells (HT-PEMFCs) that have advantages such as enhanced CO tolerance and simplified heat and water management. The currently used rotating disk electrode technique is limited to tests in dilute solutions at low temperatures and hence is not suitable for catalyst evaluation for HT-PEMFCs. In this study, we have designed and constructed a half-cell setup to measure the intrinsic activities of catalysts towards the oxygen reduction reaction (ORR) in conditions close to HT-PEMFC cathodes. By optimization of the hydrophobic characteristics of electrodes and the catalyst layer thickness, ORR activities of typical Pt/C catalysts are successfully measured in concentrated phosphoric acid at temperatures above 100 °C. In terms of mass-specific activities, the catalyst exhibits about two times higher activity in the half-cell electrode than that observed in fuel cells, indicating the feasibility of the technique as well as the potential for further improvement of fuel cell electrode performance.

Patient doses from chest radiography in Victoria.

PubMed

Cardillo, I; Boal, T J; Einsiedel, P F

1997-06-01

This survey examines doses from PA chest radiography at radiology practices, private hospitals and public hospitals throughout metropolitan and country Victoria. Data were collected from 111 individual X-ray units at 86 different practices. Entrance skin doses in air were measured for exposure factors used by the centre for a 23 cm thick male chest. A CDRH LucA1 chest phantom was used when making these measurements. About half of the centres used grid technique and half used non-grid technique. There was a factor of greater than 10 difference in the entrance dose delivered between the highest dose centre and the lowest dose centre for non-grid centres; and a factor of about 5 for centres using grids. Factors contributing to the high doses recorded at some centres were identified. Guidance levels for chest radiography based on the third quartile value of the entrance doses from this survey have been recommended and compared with guidance levels recommended in other countries.

A Spectroscopic Survey of Field Red Horizontal-branch Stars

NASA Astrophysics Data System (ADS)

Afşar, Melike; Bozkurt, Zeynep; Böcek Topcu, Gamze; Casetti-Dinescu, Dana I.; Sneden, Christopher; Şehitog̅lu, Gizem

2018-06-01

A metallicity, chemical composition, and kinematic survey has been conducted for a sample of 340 candidate field red horizontal-branch (RHB) stars. Spectra with high resolution and high signal-to-noise ratio were gathered with the McDonald Observatory 2.7 m Tull and the Hobby–Eberly Telescope echelle spectrographs, and were used to determine effective temperatures, surface gravities, microturbulent velocities, [Fe/H] metallicities, and abundance ratios [X/Fe] for seven α and Fe-group species. The derived temperatures and gravities confirm that at least half of the candidates are true RHB stars, with (average) parameters T eff ∼ 5000 K and log g ∼ 2.5. From the α abundances alone, the thin and thick Galactic populations are apparent in our sample. Space motions for 90% of the program stars were computed from Hipparcos and Gaia parallaxes and proper motions. Correlations between chemical compositions and Galactic kinematics clearly indicate the existence of both thin-disk and thick-disk RHB stars.

Heavy ion contributions to organ dose equivalent for the 1977 galactic cosmic ray spectrum

NASA Astrophysics Data System (ADS)

Walker, Steven A.; Townsend, Lawrence W.; Norbury, John W.

2013-05-01

Estimates of organ dose equivalents for the skin, eye lens, blood forming organs, central nervous system, and heart of female astronauts from exposures to the 1977 solar minimum galactic cosmic radiation spectrum for various shielding geometries involving simple spheres and locations within the Space Transportation System (space shuttle) and the International Space Station (ISS) are made using the HZETRN 2010 space radiation transport code. The dose equivalent contributions are broken down by charge groups in order to better understand the sources of the exposures to these organs. For thin shields, contributions from ions heavier than alpha particles comprise at least half of the organ dose equivalent. For thick shields, such as the ISS locations, heavy ions contribute less than 30% and in some cases less than 10% of the organ dose equivalent. Secondary neutron production contributions in thick shields also tend to be as large, or larger, than the heavy ion contributions to the organ dose equivalents.

Hydrodynamic characteristics over a range of speeds up to 80 feet per second of a rectangular modified flat plate having an aspect ratio of 0.25 and operating at several depths of submersion

NASA Technical Reports Server (NTRS)

Vaughan, Victor L , Jr; Ramsen, John A

1957-01-01

Results of an investigation of the hydrodynamic characteristics over an extended speed range of a rectangular modified flat plate having an aspect ratio of 0.25 and operating at several depths of submersion are presented. Comparisons between these data and data over a lower speed range on a similar aspect-ratio-0.25 flat plate but having one-half the thickness are presented. These comparisons show no significant differences at the low speeds. At high speeds and high angles of attack, where extensive cavitation was present, the lift coefficients were lower than would have been indicated by the results of the previous investigations and the present investigation at the lower angles of attack. A brief discussion and comparison of ventilation are presented which shows two types of planing bubble formation and the effect of increasing the thickness of the model on the ventilation boundary.

Investigation of PDMS based bi-layer elasticity via interpretation of apparent Young's modulus.

PubMed

Sarrazin, Baptiste; Brossard, Rémy; Guenoun, Patrick; Malloggi, Florent

2016-02-21

As the need of new methods for the investigation of thin films on various kinds of substrates becomes greater, a novel approach based on AFM nanoindentation is explored. Substrates of polydimethylsiloxane (PDMS) coated by a layer of hard material are probed with an AFM tip in order to obtain the force profile as a function of the indentation. The equivalent elasticity of those composite systems is interpreted using a new numerical approach, the Coated Half-Space Indentation Model of Elastic Response (CHIMER), in order to extract the thicknesses of the upper layer. Two kinds of coating are investigated. First, chitosan films of known thicknesses between 30 and 200 nm were probed in order to test the model. A second type of samples is produced by oxygen plasma oxidation of the PDMS substrate, which results in the growth of a relatively homogeneous oxide layer. The local nature of this protocol enables measurements at long oxidation time, where the apparition of cracks prevents other kinds of measurements.

Finite Element Modeling of Micromachined MEMS Photon Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Datskos, P.G.; Evans, B.M.; Schonberger, D.

1999-09-20

The technology of microelectronics that has evolved over the past half century is one of great power and sophistication and can now be extended to many applications (MEMS and MOEMS) other than electronics. An interesting application of MEMS quantum devices is the detection of electromagnetic radiation. The operation principle of MEMS quantum devices is based on the photoinduced stress in semiconductors, and the photon detection results from the measurement of the photoinduced bending. These devices can be described as micromechanical photon detectors. In this work, we have developed a technique for simulating electronic stresses using finite element analysis. We havemore » used our technique to model the response of micromechanical photon devices to external stimuli and compared these results with experimental data. Material properties, geometry, and bimaterial design play an important role in the performance of micromechanical photon detectors. We have modeled these effects using finite element analysis and included the effects of bimaterial thickness coating, effective length of the device, width, and thickness.« less

Characterization on White Etching Layer Formed During Ceramic Milling of Inconel 718

NASA Astrophysics Data System (ADS)

Kruk, A.; Wusatowska-Sarnek, A. M.; Ziętara, M.; Jemielniak, K.; Siemiątkowski, Z.; Czyrska-Filemonowicz, A.

2018-03-01

A comprehensive characterization of the near surface formed during the interrupted high-speed dry ceramic milling of IN718 was performed using light imaging, SEM/EDX, TEM and nano-hardness methods. It was found out that even an initial cut by a fresh tool creates a sub-surface alteration roughly 20 µm deep. The depth of altered sub-surface progressively changed to a roughly 40 µm when the tool reached an approximately half of its life, and almost 60 µm at the tool's end of the life. In the last two cases, the visible WEL (utilizing a light microscope) of the thickness roughly 6 and 15 µm was created, respectively. The outermost layer of the deformed subsurface was found to be for all three cases approximately 1.5 µm thick and composed of dynamically recrystallized γ phase grains with the average diameter of approximately 150 nm. This layer was free of δ phase and γ' or γ″ precipitates. It was followed by a plastically deformed zone.

An equivalent source model of the satellite-altitude magnetic anomaly field over Australia

NASA Technical Reports Server (NTRS)

Mayhew, M. A.; Johnson, B. D.; Langel, R. A.

1980-01-01

The low-amplitude, long-wavelength magnetic anomaly field measured between 400 and 700 km elevation over Australia by the POGO satellites is modeled by means of the equivalent source technique. Magnetic dipole moments are computed for a latitude-longitude array of dipole sources on the earth's surface such that the dipoles collectively give rise to a field which makes a least squares best fit to that observed. The distribution of magnetic moments is converted to a model of apparent magnetization contrast in a layer of constant (40 km) thickness, which contains information equivalent to the lateral variation in the vertical integral of magnetization down to the Curie isotherm and can be transformed to a model of variable thickness magnetization. It is noted that the closest equivalent source spacing giving a stable solution is about 2.5 deg, corresponding to about half the mean data elevation, and that the magnetization distribution correlates well with some of the principle tectonic elements of Australia.

Comparison between cylindrical and prismatic lithium-ion cell costs using a process based cost model

NASA Astrophysics Data System (ADS)

Ciez, Rebecca E.; Whitacre, J. F.

2017-02-01

The relative size and age of the US electric vehicle market means that a few vehicles are able to drive market-wide trends in the battery chemistries and cell formats on the road today. Three lithium-ion chemistries account for nearly all of the storage capacity, and half of the cells are cylindrical. However, no specific model exists to examine the costs of manufacturing these cylindrical cells. Here we present a process-based cost model tailored to the cylindrical lithium-ion cells currently used in the EV market. We examine the costs for varied cell dimensions, electrode thicknesses, chemistries, and production volumes. Although cost savings are possible from increasing cell dimensions and electrode thicknesses, economies of scale have already been reached, and future cost reductions from increased production volumes are minimal. Prismatic cells, which are able to further capitalize on the cost reduction from larger formats, can offer further reductions than those possible for cylindrical cells.

Polarization filtering in the visible wavelength range using surface plasmon resonance and a sunflower-type photonic quasi-crystal fiber

NASA Astrophysics Data System (ADS)

Yan, Bei; Wang, Anran; Liu, Exian; Tan, Wei; Xie, Jianlan; Ge, Rui; Liu, Jianjun

2018-04-01

A novel polarization filter based on a sunflower-type photonic quasi-crystal fiber (PQF) is proposed in this paper. We also discuss different methods to tune the filter wavelength. The proposed filter can efficiently produce polarized light with visible wavelengths by using the resonance between the second-order surface plasmon polariton mode and the core mode of the PQF. The filtered wavelength can be tuned between 0.55 µm and 0.68 µm by adjusting the thickness of the gold film. When the thickness of the gold film is 25.3 nm, the resonance loss in the y-polarized direction reaches 11707 dB m‑1 for a wavelength of 0.6326 µm, and the full width at half maximum is only 5 nm. Due to the flexible design and absence of both polarization coupling and polarization dispersion, this polarization filter can be used in devices that require narrow-band filtering.

Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation

PubMed Central

Jakobsson, Martin; Nilsson, Johan; Anderson, Leif; Backman, Jan; Björk, Göran; Cronin, Thomas M.; Kirchner, Nina; Koshurnikov, Andrey; Mayer, Larry; Noormets, Riko; O'Regan, Matthew; Stranne, Christian; Ananiev, Roman; Barrientos Macho, Natalia; Cherniykh, Denis; Coxall, Helen; Eriksson, Björn; Flodén, Tom; Gemery, Laura; Gustafsson, Örjan; Jerram, Kevin; Johansson, Carina; Khortov, Alexey; Mohammad, Rezwan; Semiletov, Igor

2016-01-01

The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice-shelf groundings on bathymetric highs in the central Arctic Ocean, resurrecting the concept of an ice shelf extending over the entire central Arctic Ocean during at least one previous ice age. New and previously mapped glacial landforms together reveal flow of a spatially coherent, in some regions >1-km thick, central Arctic Ocean ice shelf dated to marine isotope stage 6 (∼140 ka). Bathymetric highs were likely critical in the ice-shelf development by acting as pinning points where stabilizing ice rises formed, thereby providing sufficient back stress to allow ice shelf thickening. PMID:26778247

Theory of the mode stabilization mechanism in concave-micromirror-capped vertical-cavity surface-emitting lasers

NASA Astrophysics Data System (ADS)

Park, Si-Hyun; Park, Yeonsang; Jeon, Heonsu

2003-08-01

We have investigated theoretically the transverse mode stabilization mechanism in oxide-confined concave-micromirror-capped vertical-cavity surface-emitting lasers (CMC-VCSELs) as reported by Park et al. [Appl. Phys. Lett. 80, 183 (2002)]. From detailed numerical calculations on a model CMC-VCSEL structure, we found that mode discrimination factors appear to be periodic in the micromirror layer thickness with a periodicity of λ/2. We also found that there are two possible concave micromirror structures for the fundamental transverse mode laser operation. These structures can be grouped according to the thickness of the concave micromirror layer: whether it is an integer or a half-integer multiple of λ/2. The optimal micromirror curvature radius differs accordingly for each case. In an optimally designed CMC-VCSEL model structure, the fundamental transverse mode can be favored as much as 4, 8, and 13 times more strongly than the first, second, and third excited modes, respectively.

One-dimensional nanowires of pseudoboehmite (aluminum oxyhydroxide γ-AlOOH)

PubMed Central

Iijima, Sumio; Yumura, Takashi; Liu, Zheng

2016-01-01

We report the discovery of a 1D crystalline structure of aluminum oxyhydroxide. It was found in a commercial product of fibrous pseudoboehmite (PB), γ-AlOOH, synthesized easily with low cost. The thinnest fiber found was a ribbon-like structure of only two layers of an Al–O octahedral double sheet having a submicrometer length along its c axis and 0.68-nm thickness along its b axis. This thickness is only slightly larger than half of the lattice parameter of the b-axis unit cell of the boehmite crystal (b/2 = 0.61 nm). Moreover, interlayer splittings having an average width of 1 nm inside the fibrous PB are found. These wider interlayer spaces may have intercalation of water, which is suggested by density functional theory (DFT) calculation. The fibers appear to grow as almost isolated individual filaments in aqueous Al-hydroxide sols and the growth direction of fibrous PB is always along its c axis. PMID:27708158

Critical current density and microstructure of screen-printed (Bi,Pb)2Sr2Ca2Cu3O(x) thick film sandwiched between Ag substrates

NASA Astrophysics Data System (ADS)

Oota, A.; Matsui, H.; Funakura, M.; Iwaya, J.; Maeda, J.

1993-07-01

A process of combined rolling and uniaxial pressing with intermediate sintering steps for fabrication of screen-printed (Bi,Pb)2Sr2Ca2Cu3O(x) thick films sandwiched between Ag substrates yields c-axis-oriented microstructures with a high critical current density (Jc) of 1.5 x 10 exp 4 A/sq cm (77 K, 0 T) and 9.0 x 10 exp 4 A/sq cm (23 K, 0 T). The measured Jc anisotropy at 77 K, as a function of the angle Theta between B and c axis, is pronounced. An increase in B sharpens a peak at Theta = 90 deg in the Jc vs Theta curve, together with enhancement of the anisotropy ratio. In high fields above 0.5 T, the half-height angular width of the peak approaches an average misalignment angle between the grains with increasing B.

Thick nonpolar m-plane and semipolar (10 1 ̅ 1 ̅) GaN on an ammonothermal seed by tri-halide vapor-phase epitaxy using GaCl3

NASA Astrophysics Data System (ADS)

Iso, Kenji; Matsuda, Karen; Takekawa, Nao; Hikida, Kazuhiro; Hayashida, Naoto; Murakami, Hisashi; Koukitu, Akinori

2017-03-01

GaN layers of thickness 0.5-1.3 mm were grown at 1280 °C at a growth rate of 95-275 μm/h by tri-halide vapor-phase epitaxy on nonpolar m-plane (10 1 ̅ 0) and semipolar (10 1 ̅ 1 ̅) ammonothermal GaN substrates. For nonpolar m-plane (10 1 ̅ 0) with a -5° off-angle, the full widths at half maximum (FWHMs) of X-ray rocking curves (XRCs) and the basal plane stacking fault (BSF) density increased from 50 to 178″ and from 4.8×101 to 1.0×103 cm-1, respectively, upon increasing the growth rate from 115 to 245 μm/h. On the other hand, the XRC-FWHM and the BSF density for semipolar (10 1 ̅ 1 ̅) grown at 275 μm/h were as small as 28″ and 8.3×101 cm-1, respectively.

Finite element modeling of micromachined MEMS photon devices

NASA Astrophysics Data System (ADS)

Evans, Boyd M., III; Schonberger, D. W.; Datskos, Panos G.

1999-09-01

The technology of microelectronics that has evolved over the past half century is one of great power and sophistication and can now be extended to many applications (MEMS and MOEMS) other than electronics. An interesting application of MEMS quantum devices is the detection of electromagnetic radiation. The operation principle of MEMS quantum devices is based on the photoinduced stress in semiconductors, and the photon detection results from the measurement of the photoinduced bending. These devices can be described as micromechanical photon detectors. In this work, we have developed a technique for simulating electronic stresses using finite element analysis. We have used our technique to model the response of micromechanical photon devices to external stimuli and compared these results with experimental data. Material properties, geometry, and bimaterial design play an important role in the performance of micromechanical photon detectors. We have modeled these effects using finite element analysis and included the effects of bimaterial thickness coating, effective length of the device, width, and thickness.

Orthogonal Simulation Experiment for Flow Characteristics of Ore in Ore Drawing and Influencing Factors in a Single Funnel Under a Flexible Isolation Layer

NASA Astrophysics Data System (ADS)

Chen, Qingfa; Zhao, Fuyu; Chen, Qinglin; Wang, Yuding; Zhong, Yu; Niu, Wenjing

2017-12-01

A study on the flow characteristics of ore and factors that influence these characteristics is important to master ore flow laws. An orthogonal ore-drawing numerical model was established and the flow characteristics were explored. A weight matrix was obtained and the effect of the factors was determined. It was found that (1) the entire isolation-layer interface presents a Gaussian curve morphology and marked particles in each layer show a funnel morphology; (2) the drawing amount, Q, and the isolation layer half-width, W, are correlated positively with the fall depth, H, of the isolation layer; (3) factors that affect the characteristics sequentially include the particle friction coefficient, the interface friction coefficient, the isolation layer thickness, and the particle radius, and (4) the optimal combination is an isolation layer thickness of 0.005 m, an interface friction coefficient of 0.8, a particle friction coefficient of 0.2, and a particle radius of 0.007 m.

Geothermal heating in the Panama Basin and its impact on water mass transformation

NASA Astrophysics Data System (ADS)

Banyte, D.; Morales Maqueda, M. A.; Hobbs, R. W.; Megann, A.; Smeed, D.

2017-12-01

Geothermal heating is a driving force of abyssal water transformation. To quantify its impact at the basin scale, a hydrographic survey of the Panama Basin was carried out in 2014-2015 as part of the international project OSCAR (Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge). The study shows that about half of the water entering the basin, which is connected to the Pacific Ocean only through the a narrow passage part of the Ecuador Trench, is converted to lighter water within just 200 km downstream of the passage. Of the resulting water, a staggering 90% is transformed by geothermal heating inside the basin, welling up into the ocean interior from a bottom boundary layer (BBL) that can be up to 1000 m thick. The geothermal forcing leaves an imprint in temperature-salinity properties hundreds of meters above the thick BBL. We present a conceptual model of the abyssal water transformation in the basin that incorporates these processes.

Modelling of surface stresses and fracturing during dyke emplacement: Application to the 2009 episode at Harrat Lunayyir, Saudi Arabia

NASA Astrophysics Data System (ADS)

Al Shehri, Azizah; Gudmundsson, Agust

2018-05-01

Correct interpretation of surface stresses and deformation or displacement during volcanotectonic episodes is of fundamental importance for hazard assessment and dyke-path forecasting. Here we present new general numerical models on the local stresses induced by arrested dykes. In the models, the crustal segments hosting the dyke vary greatly in mechanical properties, from uniform or non-layered (elastic half-spaces) to highly anisotropic (layers with strong contrast in Young's modulus). The shallow parts of active volcanoes and volcanic zones are normally highly anisotropic and some with open contacts. The numerical results show that, for a given surface deformation, non-layered (half-space) models underestimate the dyke overpressure/thickness needed and overestimate the likely depth to the tip of the dyke. Also, as the mechanical contrast between the layers increases, so does the stress dissipation and associated reduction in surface stresses (and associated fracturing). In the absence of open contacts, the distance between the two dyke-induced tensile and shear stress peaks (and fractures, if any) at the surface is roughly twice the depth to the tip of the dyke. The width of a graben, if it forms, should therefore be roughly twice the depth to the tip of the associated arrested dyke. When applied to the 2009 episode at Harrat Lunayyir, the main results are as follows. The entire 3-7 km wide fracture zone/graben formed during the episode is far too wide to have been generated by induced stresses of a single, arrested dyke. The eastern part of the zone/graben may have been generated by the inferred, arrested dyke, but the western zone primarily by regional extensional loading. The dyke tip was arrested at only a few hundred metres below the surface, the estimated thickness of the uppermost part of the dyke being between about 6 and 12 m. For the inferred dyke length (strike dimension) of about 14 km, this yields a dyke length/thickness ratio between 2400 and 1200, similar to commonly measured ratios of regional dykes in the field.

Impact of induced seismic events on seal integrity, Texas Gulf Coast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicot, Jean-Philippe; Meckel, Timothy A.; Carr, David A.

Recent publications have suggested that large-scale CO 2 injection could trigger earthquakes and that even small- to moderate-sized earthquakes may threaten the seal integrity of the injection zone, and potentially damage buildings and other surface structures. In this study, we compared seal thickness to estimated fault displacement due to a single hypothetical seismic event in a selected area of the Texas Gulf Coast comprising an offshore strip of state waters along two Texas counties. To evaluate the slip generated by a single seismic event, we compiled well log information on shale/sand sequences and seismic information on fault geometric characteristics ofmore » a section of Lower Miocene age. The section is thousands of feet thick and is overlain and underlain by marine shales (Amph. B and Anahuac, respectively) that are relatively easy to correlate between wells. The Amph. B. shale is the secondary and ultimate seal for all injection intervals in the Lower Miocene. Given its thickness, no realistic seismic event or small series of seismic events will offset it significantly. However, this may not be true of smaller local primary seals. An analysis of geophysical logs of a total of 71 wells yielded a total of 2,871 sand / shale binary intervals. An analysis of the dedicated 3D seismic survey counted 723 fault traces at five roughly horizontal horizons within the Lower Miocene Fault displacement estimated using the product of the fault length times an uncertain multiplier coefficient assumed to follow a triangular distribution with a 10 -3 to 10 -5 range and a mode of 8 × 10 -5. We then compared estimated single-event fault displacements to seal thicknesses by means of a Monte-Carlo analysis. Only 1.8% of thickness/displacement pairs display a displacement greater than 20% of the seal thickness. Only 0.26% of the pairs result in a displacement of half the seal thickness and only 0.05% of thickness/displacement pairs result in a clear seal rupture. The next step was to compare the magnitude of the event generated by such a displacement to documented magnitudes of “large” earthquakes generated by waterflooding and fluid disposal. Based on this analysis, we conclude that seismicity that may arise from CO 2 injection appears not to be a serious complication for CO 2 storage integrity, at least in the Gulf Coast area.« less

WE-DE-207B-08: Towards Standardization of X-Ray Filters in Digital Mammography-Enabled Breast Tomosynthesis Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrestha, S; Vedantham, S; Karellas, A

Purpose: In digital breast tomosynthesis (DBT) systems capable of digital mammography (DM), Al filters are used during DBT and K-edge filters during DM. The potential for standardizing the x-ray filters with Al, instead of K-edge filters, was investigated with intent to reduce exposure duration and to promote a simpler system design. Methods: Analytical computations of the half-value thickness (HVT) and the photon fluence per mAs (photons/mm2/mAs) for K-edge filters (50µm Rh; 50µm Ag) were compared with Al filters of varying thickness. Two strategies for matching the HVT from K-edge and Al filtered spectra were investigated: varying the kVp for fixedmore » Al thickness, or varying the Al thickness at matched kVp. For both strategies, Al filters were an order of magnitude thicker than K-edge filters. Hence, Monte Carlo simulations were conducted with the GEANT4 toolkit to determine if the scatter-to-primary ratio (SPR) and the point spread function of scatter (scatter PSF) differed between Al and K-edge filters. Results: Results show the potential for replacing currently used Kedge filters with Al. For fixed Al thickness (700µm), ±1 kVp and +(1–3) kVp change, matched HVT of Rh and Ag filtered spectra. At matched kVp, Al thickness range (650,750)µm and (750,860)µm matched the HVT from Rh and Ag filtered spectra. Photon fluence/mAs with Al filters were 1.5–2.5 times higher, depending on kVp and Al thickness, compared to K-edge filters. Although Al thickness was an order higher than K-edge filters, neither the SPR nor the scatter PSF differed from K-edge filters. Conclusion: The use of Al filters for digital mammography is potentially feasible. The increased fluence/mAs with Al could decrease exposure duration for the combined DBT+DM exam and simplify system design. Effect of x-ray spectrum change due to Al filtration on radiation dose, signal, noise, contrast and related metrics are being investigated. Funding support: Supported in part by NIH R21CA176470 and R01CA195512. The contents are solely the responsibility of the authors and do not reflect the official views of the NIH or NCI.« less

Impact of induced seismic events on seal integrity, Texas Gulf Coast

DOE PAGES

Nicot, Jean-Philippe; Meckel, Timothy A.; Carr, David A.; ...

2014-12-31

Recent publications have suggested that large-scale CO 2 injection could trigger earthquakes and that even small- to moderate-sized earthquakes may threaten the seal integrity of the injection zone, and potentially damage buildings and other surface structures. In this study, we compared seal thickness to estimated fault displacement due to a single hypothetical seismic event in a selected area of the Texas Gulf Coast comprising an offshore strip of state waters along two Texas counties. To evaluate the slip generated by a single seismic event, we compiled well log information on shale/sand sequences and seismic information on fault geometric characteristics ofmore » a section of Lower Miocene age. The section is thousands of feet thick and is overlain and underlain by marine shales (Amph. B and Anahuac, respectively) that are relatively easy to correlate between wells. The Amph. B. shale is the secondary and ultimate seal for all injection intervals in the Lower Miocene. Given its thickness, no realistic seismic event or small series of seismic events will offset it significantly. However, this may not be true of smaller local primary seals. An analysis of geophysical logs of a total of 71 wells yielded a total of 2,871 sand / shale binary intervals. An analysis of the dedicated 3D seismic survey counted 723 fault traces at five roughly horizontal horizons within the Lower Miocene Fault displacement estimated using the product of the fault length times an uncertain multiplier coefficient assumed to follow a triangular distribution with a 10 -3 to 10 -5 range and a mode of 8 × 10 -5. We then compared estimated single-event fault displacements to seal thicknesses by means of a Monte-Carlo analysis. Only 1.8% of thickness/displacement pairs display a displacement greater than 20% of the seal thickness. Only 0.26% of the pairs result in a displacement of half the seal thickness and only 0.05% of thickness/displacement pairs result in a clear seal rupture. The next step was to compare the magnitude of the event generated by such a displacement to documented magnitudes of “large” earthquakes generated by waterflooding and fluid disposal. Based on this analysis, we conclude that seismicity that may arise from CO 2 injection appears not to be a serious complication for CO 2 storage integrity, at least in the Gulf Coast area.« less

Nitrogen-doped carbonaceous catalysts for gas-diffusion cathodes for alkaline aluminum-air batteries

NASA Astrophysics Data System (ADS)

Davydova, E. S.; Atamanyuk, I. N.; Ilyukhin, A. S.; Shkolnikov, E. I.; Zhuk, A. Z.

2016-02-01

Cobalt tetramethoxyphenyl porphyrin and polyacrylonitrile - based catalysts for oxygen reduction reaction were synthesized and characterized by means of SEM, TEM, XPS, BET, limited evaporation method, rotating disc and rotating ring-disc electrode methods. Half-cell and Al-air cell tests were carried out to determine the characteristics of gas-diffusion cathodes. Effect of active layer thickness and its composition on the characteristics of the gas-diffusion cathodes was investigated. Power density of 300 mW cm-2 was achieved for alkaline Al-air cell with an air-breathing polyacrylonitrile-based cathode.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, Lianfeng; Li, Jonathan; Zakharov, Dmitri

Using in situ transmission electron microscopy that spatially and temporally resolves the evolution of the atomic structure in the surface and subsurface regions, we Find that the surface segregation of Au atoms in a Cu(Au) solid solution results in the nucleation and growth of a (2 × 1) missing-row reconstructed, half-unit-cell thick L1 2 Cu 3Au(110) surface alloy. Our in situ electron microscopy observations and atomistic simulations demonstrate that the (2 × 1) reconstruction of the Cu 3Au(110) surface alloy remains as a stable surface structure as a result of the favored Cu-Au diatom configuration.

Development of multi-wavelength Kretschmann setup for the efficient excitation of surface plasmons

NASA Astrophysics Data System (ADS)

Priya, Sugandh; Laha, Ranjit; Dantham, Venkata R.

2018-05-01

Recently, surface plasmon resonance biosensors have become popular devices for studying biomolecular interactions, chemical detection and immunoassays. However, these biosensors have the lower figure of merit (FOM) when the sample concentration is in the order of nanoMolar or lower. To improve the FOM of these devices, (i) the dependence of full width at half maximum (FWHM) of the resonance on excitation wavelength, thickness and electric permittivity of a metal thin film has been systematically studied and (ii) multi-wavelength Kretschmann setup has been developed and tested with a few metal thin films.

Control of Angular Intervals for Angle-Multiplexed Holographic Memory

NASA Astrophysics Data System (ADS)

Kinoshita, Nobuhiro; Muroi, Tetsuhiko; Ishii, Norihiko; Kamijo, Koji; Shimidzu, Naoki

2009-03-01

In angle-multiplexed holographic memory, the full width at half maximum of the Bragg selectivity curves is dependent on the angle formed between the medium and incident laser beams. This indicates the possibility of high density and high multiplexing number by varying the angular intervals between adjacent holograms. We propose an angular interval scheduling for closely stacking holograms into medium even when the angle range is limited. We obtained bit error rates of the order of 10-4 under the following conditions: medium thickness of 1 mm, laser beam wavelength of 532 nm, and angular multiplexing number of 300.

Circularly polarized lasing in chiral modulated semiconductor microcavity with GaAs quantum wells

NASA Astrophysics Data System (ADS)

Demenev, A. A.; Kulakovskii, V. D.; Schneider, C.; Brodbeck, S.; Kamp, M.; Höfling, S.; Lobanov, S. V.; Weiss, T.; Gippius, N. A.; Tikhodeev, S. G.

2016-10-01

We report close to circularly polarized lasing at ℏ ω = 1.473 and 1.522 eV from an AlAs/AlGaAs Bragg microcavity, with 12 GaAs quantum wells in the active region and chirally etched upper distributed Bragg refractor under optical pump at room temperature. The advantage of using the chiral photonic crystal with a large contrast of dielectric permittivities is its giant optical activity, allowing to fabricate a very thin half-wave plate, with a thickness of the order of the emitted light wavelength, and to realize the monolithic control of circular polarization.

Effect of current injection into thin-film Josephson junctions

DOE PAGES

Kogan, V. G.; Mints, R. G.

2014-11-11

New thin-film Josephson junctions have recently been tested in which the current injected into one of the junction banks governs Josephson phenomena. One thus can continuously manage the phase distribution at the junction by changing the injected current. Our method of calculating the distribution of injected currents is also proposed for a half-infinite thin-film strip with source-sink points at arbitrary positions at the film edges. The strip width W is assumed small relative to Λ=2λ 2/d;λ is the bulk London penetration depth of the film material and d is the film thickness.

Instrumentation development for the EUVE. [Extreme Ultraviolet Explorer Satellite

NASA Technical Reports Server (NTRS)

Finley, D.

1980-01-01

The prototype mirror was successfully replated with a thick layer of nickel and diamond turned again. Optimization of the sensitivity of the instruments was studied with emphasis on the filter material, and on the available telemetry. The JHU Preliminary Project Definition Document was critically analyzed. Further studies of the electron cloud distribution produced by a channel plate were performed, and a wedge and strip anode with 17 quartets per inch was shown to image with better than 0.5% linearity. Half the microchannel plates being used in the lifetest completed initial processing and are in the lifetest vacuum chamber.

Hydride vapor phase epitaxy of AlN using a high temperature hot-wall reactor

NASA Astrophysics Data System (ADS)

Baker, Troy; Mayo, Ashley; Veisi, Zeinab; Lu, Peng; Schmitt, Jason

2014-10-01

Aluminum nitride (AlN) was grown on c-plane sapphire substrates by hydride vapor phase epitaxy (HVPE). The experiments utilized a two zone inductively heated hot-wall reactor. The surface morphology, crystal quality, and growth rate were investigated as a function of growth temperature in the range of 1450-1575 °C. AlN templates grown to a thickness of 1 μm were optimized with double axis X-ray diffraction (XRD) rocking curve full width half maximums (FWHMs) of 135″ for the (002) and 513″ for the (102).

Reflection and interference of electromagnetic waves in inhomogeneous media

NASA Technical Reports Server (NTRS)

Geiger, F. E.; Kyle, H. L.

1973-01-01

Solutions were obtained of the wave equation for a plane horizontally polarized electro-magnetic wave incident on a semi infinite two dimensional inhomogeneous medium. Two problems were considered: An inhomogeneous half space, and an inhomogeneous layer of arbitrary thickness. Solutions of the wave equation were obtained in terms of Hankel functions with complex arguments. Numerical calculations were made of the reflection coefficient R at the interface of the homogeneous medium. The startling results show that the reflection coefficient for a complex dielectric constant with gradient, can be less than that of the same medium with zero gradient.

Industrial Applications of Terahertz Imaging

NASA Astrophysics Data System (ADS)

Zeitler, J. Axel; Shen, Yao-Chun

This chapter gives a concise overview of potential industrial applications for terahertz imaging that have been reported over the past decade with a discussion of the major advantages and limitations of each approach. In the second half of the chapter we discuss in more detail how terahertz imaging can be used to investigate the microstructure of pharmaceutical dosage forms. A particular focus in this context is the nondestructive measurement of the coating thickness of polymer coated tablets, both by means of high resolution offline imaging in research and development as well as for in-line quality control during production.

Statistical survey on the magnetic structure in magnetotail current sheets

NASA Astrophysics Data System (ADS)

Rong, Z. J.; Wan, W. X.; Shen, C.; Li, X.; Dunlop, M. W.; Petrukovich, A. A.; Zhang, T. L.; Lucek, E.

2011-09-01

On the basis of the multipoint magnetic observations of Cluster in the region 15-19 RE downtail, the magnetic field structure in magnetotail current sheet (CS) center is statistically surveyed. It is found that the By component (in GSM coordinates) is distributed mainly within ∣By∣ < 5nT, while the Bz component is mostly positive and distributes mainly within 1˜10 nT. The plane of the magnetic field lines (MFLs) is mostly vertical to the equatorial plane, with the radius of curvature (Rc) of the MFLs being directed earthward and the binormal (perpendicular to the curvature and magnetic field direction) being directed azimuthally westward. The curvature radius of MFLs reaches a minimum, Rc,min, at the CS center and is larger than the corresponding local half thickness of the neutral sheet, h. Statistically, it is found that the overall surface of the CS, with the normal pointing basically along the south-north direction, can be approximated to be a plane parallel to equatorial plane, although the local CS may be flapping and is frequently tilted to the equatorial plane. The tilted CS (normal inclined to the equatorial plane) is apt to be observed near both flanks and is mainly associated with the slippage of magnetic flux tubes. It is statistically verified that the minimum curvature radius, Rc,min, half thickness of neutral sheet, h, and the slipping angle of MFLs, δ, in the CS satisfies h = Rc,min cosδ. The current density, with a mean strength of 4-8 nA/m2, basically flows azimuthally and tangentially to the surface of the CS, from dawn side to the dusk side. There is an obvious dawn-dusk asymmetry of CS, however. For magnetic local times (MLT) ˜21:00-˜01:00, the CS is relatively thinner; the minimum curvature radius of MFLs, Rc,min (0.6-1 RE) and the half-thickness of neutral sheet, h (0.2-0.4 RE), are relatively smaller, and Bz (3-5 nT) and the minimum magnetic field, Bmin (5-7 nT), are weaker. It is also found that negative Bz has a higher probability of occurrence and the cross-tail current density jY is dominant (2-4 nA/m2) in comparison to those values near both flanks. This implies that magnetic activity, e.g., magnetic reconnection and current disruption, could be triggered more frequently in CS with ˜21:00-˜01:00 MLT. Accordingly, if mapped to the region in the auroral ionosphere, it is expected that substorm onset would be optically observed with higher probability for ˜21:00-˜01:00 MLT, which is well in agreement with statistical observations of auroral substorm onset.

The composition, structure, and stability of guinier-preston zones in lunar and terrestrial orthopyroxene

USGS Publications Warehouse

Nord, G.L.

1980-01-01

Lunar and terrestrial orthopyroxenes (Mg,Fe,Ca)2Si2O6 contain varying abundances of coherent, Ca-enriched Guinier-Preston (G.P.) zones. G.P. zones 5-6 unit cells thick have been found in one lunar sample whereas all other examples (lunar and terrestrial) are only one unit-cell-thick. Electron diffraction maxima from the larger lunar G.P. zones indicate that d100=18.52 A?? whereas, d100=18.2 A?? for the host. This increase in the a direction corresponds to an increase in calcium content in the G.P. zones over that of the host of ???25 mol% Ca2Si2O6. Diffraction patterns of the hk0 net from an area containing G.P. zones show extra spots (h=2 n+1) not observed in the host orthopyroxene (Pbca), that violate the a-glide of the host. The G.P. zones, therefore, have space group Pbc21 if it is assumed that the c-glide of pyroxene is retained and the space group of the G.P. zone is a subgroup of Pbca. The loss of the a-glide in the G.P. zones results in 4 distinct silica chains and 4 distinct cation sites M1A, M1B, M2A, M2B; by symmetry, equivalent M2A or M2B sites are clustered together in only one-half of the unit cell. As one-fourth of the divalent cations in the G.P. zones are calcium, ordering of Ca on M2A or M2B would produce a zone 9 A?? thick extended parallel to (100) with the composition of Ca(Mg,Fe)Si2O6, but constrained by the host to the structure of orthopyroxene. This zone and the Ca-poor half-unit-cell then constitute an 18 A?? thick G.P. zone. Heating experiments of varying duration indicate that the zones become unstable with respect to the host orthopyroxene at ???950??C for Wo0.6 and ???1,050??C for Wo2.5. The zones are interpreted in terms of the pyroxene subsolidus as a metastable phase having either a solvus relationship with orthopyroxene or originating as a distinct phase. The size, distribution, composition and structure of G.P. zones may be an important indicator of the low-temperature thermal history of orthopyroxene. ?? 1980 Springer-Verlag.

Transabdominal ultrasonographic appearance of the gastrointestinal viscera of healthy camels (Camelus dromedaries).

PubMed

Tharwat, Mohamed; Al-Sobayil, Fahd; Ali, Ahmed; Buczinski, Sébastien

2012-10-01

The purpose of this study was to describe the ultrasonographic picture of the gastrointestinal tract in healthy camels (Camelus dromedarius). For this purpose, 22 camels were examined. The rumen and its glandular sacs were filling most of the left side of the abdomen. The rumen wall was smooth and echogenic. The ventral part of the reticulum could be best imaged in 17 (77%) camels from the left and right paramedian region just behind to the sternal pad. The reticulum in these animals had a thick wall (1.17±0.27 cm) that appeared as a half-moon-shaped structure with a biphasic contraction. The omasum was best viewed through the right 8th to 6th intercostal spaces in 18 (82%) camels. In the remaining 4 (18%), it was visualized through four consecutive intercostal spaces (right 9th to 6th). It had a wall thickness of 1.1±0.7 cm and a transverse diameter of 8.74±3.4 cm. The abomasum could be best visualized from the right 9th and 8th intercostal spaces in 14 (64%) camels, while it was observed in the 9th intercostal space in 3 (14%) animals and in the 8th and 7th intercostal space in 5 (22%) camels. Small intestinal structures were best seen low in the right paralumbar fossa. It was thin-walled (0.43±0.14 cm) and had a diameter of 2.62±0.47 cm. The cecum was imaged chiefly in the caudal right flank. It was thin-walled (0.37±0.05 cm), had a diameter of 13.8±1.6 cm. The proximal loop of the large colon appeared as thick, echogenic, continuous and slightly curved lines. It was thin-walled (0.51±0.08 cm) and had a diameter of 3.5±0.8 cm. The spiral colon was confined in all camels to the caudal ventral half of the abdomen. It appeared as structures with thick echoic lateral walls with a number of echogenic arched lines next to each other. Free peritoneal fluid pockets were imaged in two locations in 19 (86%) camels. Ultrasound-guided abdominocentesis was successful in 15 (68%) of the examined camels. This study provides the ultrasonographic appearance of the normal gastrointestinal tract in healthy camels that could be used as a reference for the interpretation of suspected digestive abnormalities. Copyright © 2012. Published by Elsevier India Pvt Ltd.

Air-coupled ultrasonic through-transmission thickness measurements of steel plates.

PubMed

Waag, Grunde; Hoff, Lars; Norli, Petter

2015-02-01

Non-destructive ultrasonic testing of steel structures provide valuable information in e.g. inspection of pipes, ships and offshore structures. In many practical applications, contact measurements are cumbersome or not possible, and air-coupled ultrasound can provide a solution. This paper presents air-coupled ultrasonic through-transmission measurements on a steel plate with thicknesses 10.15 mm; 10.0 mm; 9.8 mm. Ultrasound pulses were transmitted from a piezoelectric transducer at normal incidence, through the steel plate, and were received at the opposite side. The S1, A2 and A3 modes of the plate are excited, with resonance frequencies that depend on the material properties and the thickness of the plate. The results show that the resonances could be clearly identified after transmission through the steel plate, and that the frequencies of the resonances could be used to distinguish between the three plate thicknesses. The S1-mode resonance was observed to be shifted 10% down compared to a simple plane wave half-wave resonance model, while the A2 and S2 modes were found approximately at the corresponding plane-wave resonance frequencies. A model based on the angular spectrum method was used to predict the response of the through-transmission setup. This model included the finite aperture of the transmitter and receiver, and compressional and shear waves in the solid. The model predicts the frequencies of the observed modes of the plate to within 1%, including the down-shift of the S1-mode. Copyright © 2014 Elsevier B.V. All rights reserved.

Glaucoma-Diagnostic Ability of Ganglion Cell-Inner Plexiform Layer Thickness Difference Across Temporal Raphe in Highly Myopic Eyes.

PubMed

Kim, Young Kook; Yoo, Byeong Wook; Jeoung, Jin Wook; Kim, Hee Chan; Kim, Hae Jin; Park, Ki Ho

2016-11-01

To evaluate the glaucoma-diagnostic ability of the ganglion cell-inner plexiform layer (GCIPL) thickness difference across the temporal raphe in highly myopic eyes. We consecutively enrolled a total of 195 highly myopic eyes (axial length [AL] >26.5 mm) of 195 subjects: 93 glaucoma patients along with and 102 nonglaucomatous subjects. Cirrus high-definition optical coherence tomography (OCT) was employed to scan all of the subjects' macular and optic discs. Using a MATLAB-based customized program (the GCIPL hemifield test), a positive test result was automatically declared if the following two conditions were met: (1) the horizontal line is detected for longer than one-half of the distance from the temporal inner elliptical annulus to the outer elliptical annulus, and (2) the average GCIPL thickness difference within 10 pixels of the reference line, both above and below, is 5 μm or more. The glaucoma-diagnostic ability was computed using the area under the receiver operating characteristic curve (AUC). Among the glaucomatous eyes, GCIPL hemifield test positivity was shown in 92.5% (86 of 93), significantly higher than that for the nonglaucomatous eyes (4.90%, 5 of 102; P <0.001). The value of AUC for the GCIPL hemifield test was excellent (0.938; sensitivity 92.50%, specificity 95.10%) and was the best compared with those for any of OCT parameters. In highly myopic eyes, determination of the presence or absence of GCIPL thickness difference across the temporal raphe via OCT macula scan can be a useful means of distinguishing the glaucomatous damage.

Analyses on the geometrical structure of magnetic field in the current sheet based on cluster measurements

NASA Astrophysics Data System (ADS)

Shen, C.; Li, X.; Dunlop, M.; Liu, Z. X.; Balogh, A.; Baker, D. N.; Hapgood, M.; Wang, X.

2003-05-01

The geometrical structure of the magnetic field is a critical character in the magnetospheric dynamics. Using the magnetic field data measured by the Cluster constellation satellites, the geometrical structure including the curvature radius, directions of curvature, and normal of the osculating planes of the magnetic field lines within the current sheet/neutral sheet have been investigated. The results are (1) Inside of the tail neutral sheet (NS), the curvature of magnetic field lines points towards Earth, the normal of the osculating plane points duskward, and the characteristic half width (or the minimum curvature radius) of the neutral sheet is generally less than 2 RE, for many cases less than 1600 km. (2) Outside of the neutral sheet, the curvature of magnetic field lines pointed northward (southward) at the north (south) side of NS, the normal of the osculating plane points dawnward, and the curvature radius is about 5 RE ˜ 10 RE. (3) Thin NS, where the magnetic field lines have the minimum of the curvature radius less than 0.25 RE, may appear at all the local time between LT 20 hours and 4 hours, but thin NS occurs more frequently near to midnight than that at the dawnside and duskside. (4) The size of the NS is dependent on substorm phases. Generally, the NS is thin during the growth and expansion phases and grows thick during the recovery phase. (5) For the one-dimensional NS, the half thickness and flapping velocity of the NS could be quantitatively determined. Therefore the differential geometry analyses based on Cluster 4-point magnetic measurements open a window for visioning the three-dimensional static and dynamic magnetic field structure of geomagnetosphere.

The NuSTAR Extragalactic Surveys: Source Catalog and the Compton-thick Fraction in the UDS Field

NASA Astrophysics Data System (ADS)

Masini, A.; Civano, F.; Comastri, A.; Fornasini, F.; Ballantyne, D. R.; Lansbury, G. B.; Treister, E.; Alexander, D. M.; Boorman, P. G.; Brandt, W. N.; Farrah, D.; Gandhi, P.; Harrison, F. A.; Hickox, R. C.; Kocevski, D. D.; Lanz, L.; Marchesi, S.; Puccetti, S.; Ricci, C.; Saez, C.; Stern, D.; Zappacosta, L.

2018-03-01

We present the results and the source catalog of the NuSTAR survey in the UKIDSS Ultra Deep Survey (UDS) field, bridging the gap in depth and area between NuSTAR’s ECDFS and COSMOS surveys. The survey covers a ∼0.6 deg2 area of the field for a total observing time of ∼1.75 Ms, to a half-area depth of ∼155 ks corrected for vignetting at 3–24 keV, and reaching sensitivity limits at half-area in the full (3–24 keV), soft (3–8 keV), and hard (8–24 keV) bands of 2.2 × 10‑14 erg cm‑2 s‑1, 1.0 × 10‑14 erg cm‑2 s‑1, and 2.7 × 10‑14 erg cm‑2 s‑1, respectively. A total of 67 sources are detected in at least one of the three bands, 56 of which have a robust optical redshift with a median of < z> ∼ 1.1. Through a broadband (0.5–24 keV) spectral analysis of the whole sample combined with the NuSTAR hardness ratios, we compute the observed Compton-thick (CT; NH > 1024 cm‑2) fraction. Taking into account the uncertainties on each NH measurement, the final number of CT sources is 6.8 ± 1.2. This corresponds to an observed CT fraction of 11.5% ± 2.0%, providing a robust lower limit to the intrinsic fraction of CT active galactic nuclei and placing constraints on cosmic X-ray background synthesis models.

In Vivo Evaluation of Immediately Loaded Stainless Steel and Titanium Orthodontic Screws in a Growing Bone

PubMed Central

Gritsch, Kerstin; Laroche, Norbert; Bonnet, Jeanne-Marie; Exbrayat, Patrick; Morgon, Laurent; Rabilloud, Muriel; Grosgogeat, Brigitte

2013-01-01

The present work intends to evaluate the use of immediate loaded orthodontic screws in a growing model, and to study the specific bone response. Thirty-two screws (half of stainless steel and half of titanium) were inserted in the alveolar bone of 8 growing pigs. The devices were immediately loaded with a 100 g orthodontic force. Two loading periods were assessed: 4 and 12 weeks. Both systems of screws were clinically assessed. Histological observations and histomorphometric analysis evaluated the percent of “bone-to-implant contact” and static and dynamic bone parameters in the vicinity of the devices (test zone) and in a bone area located 1.5 cm posterior to the devices (control zone). Both systems exhibit similar responses for the survival rate; 87.5% and 81.3% for stainless steel and titanium respectively (p = 0.64; 4-week period), and 62.5% and 50.0% for stainless steel and titanium respectively (p = 0.09; 12-week period). No significant differences between the devices were found regarding the percent of “bone-to-implant contact” (p = 0.1) or the static and dynamic bone parameters. However, the 5% threshold of “bone-to-implant contact” was obtained after 4 weeks with the stainless steel devices, leading to increased survival rate values. Bone in the vicinity of the miniscrew implants showed evidence of a significant increase in bone trabecular thickness when compared to bone in the control zone (p = 0.05). In our study, it is likely that increased trabecular thickness is a way for low density bone to respond to the stress induced by loading. PMID:24124540

Cardiovascular magnetic resonance demonstration of the spectrum of morphological phenotypes and patterns of myocardial scarring in Anderson-Fabry disease.

PubMed

Deva, Djeven Parameshvara; Hanneman, Kate; Li, Qin; Ng, Ming Yen; Wasim, Syed; Morel, Chantal; Iwanochko, Robert M; Thavendiranathan, Paaladinesh; Crean, Andrew Michael

2016-03-31

Although it is known that Anderson-Fabry Disease (AFD) can mimic the morphologic manifestations of hypertrophic cardiomyopathy (HCM) on echocardiography, there is a lack of cardiovascular magnetic resonance (CMR) literature on this. There is limited information in the published literature on the distribution of myocardial fibrosis in patients with AFD, with scar reported principally in the basal inferolateral midwall. All patients with confirmed AFD undergoing CMR at our center were included. Left ventricular (LV) volumes, wall thicknesses and scar were analyzed offline. Patients were categorized into 4 groups: (1) no wall thickening; (2) concentric hypertrophy; (3) asymmetric septal hypertrophy (ASH); and (4) apical hypertrophy. Charts were reviewed for clinical information. Thirty-nine patients were included (20 males [51%], median age 45.2 years [range 22.3-64.4]). Almost half (17/39) had concentric wall thickening. Almost half (17/39) had pathologic LV scar; three quarters of these (13/17) had typical inferolateral midwall scar. A quarter (9/39) had both concentric wall thickening and typical inferolateral scar. A subgroup with ASH and apical hypertrophy (n = 5) had greater maximum wall thickness, total LV scar, apical scar and mid-ventricular scar than those with concentric hypertrophy (n = 17, p < 0.05). Patients with elevated LVMI had more overall arrhythmia (p = 0.007) more ventricular arrhythmia (p = 0.007) and sustained ventricular tachycardia (p = 0.008). Concentric thickening and inferolateral mid-myocardial scar are the most common manifestations of AFD, but the spectrum includes cases morphologically identical to apical and ASH subtypes of HCM and these have more apical and mid-ventricular LV scar. Significant LVH is associated with ventricular arrhythmia.

Control of femtosecond laser interference ejection with angle and polarisation

NASA Astrophysics Data System (ADS)

Roper, David M.; Ho, Stephen; Haque, Moez; Herman, Peter R.

2017-03-01

The nonlinear interactions of femtosecond lasers are driving multiple new application directions for nanopatterning and structuring of thin transparent dielectric films that serve in range of technological fields. Fresnel reflections generated by film interfaces were recently shown to confine strong nonlinear interactions at the Fabry-Perot fringe maxima to generate thin nanoscale plasma disks of 20 to 40 nm thickness stacked on half wavelength spacing, λ/2nfilm, inside a film (refractive index, nfilm). The following phase-explosion and ablation dynamics have resulted in a novel means for intrafilm processing that includes `quantized' half-wavelength machining steps and formation of blisters with embedded nanocavities. This paper presents an extension in the control of interferometric laser processing around our past study of Si3N4 and SiOx thin films at 515 nm, 800 nm, and 1044 nm laser wavelengths. The role of laser polarization and incident angle is explored on fringe visibility and improving interferometric processing inside the film to dominate over interface and / or surface ablation. SiOx thin films of 1 μm thickness on silicon substrates were irradiated with a 515 nm wavelength, 280 fs duration laser pulses at 0° to 65° incident angles. A significant transition in ablation region from complete film removal to structured quantized ejection is reported for p- and s-polarised light that is promising to improve control and expand the versatility of the technique to a wider range of applications and materials. The research is aimed at creating novel bio-engineered surfaces for cell culture, bacterial studies and regenerative medicine, and nanofluidic structures that underpin lab-in-a-film. Similarly, the formation of intrafilm blisters and nanocavities offers new opportunities in structuring existing thin film devices, such as CMOS microelectronics, LED, lab-on-chips, and MEMS.

Surface Phenomena During Plasma-Assisted Atomic Layer Etching of SiO2.

PubMed

Gasvoda, Ryan J; van de Steeg, Alex W; Bhowmick, Ranadeep; Hudson, Eric A; Agarwal, Sumit

2017-09-13

Surface phenomena during atomic layer etching (ALE) of SiO 2 were studied during sequential half-cycles of plasma-assisted fluorocarbon (CF x ) film deposition and Ar plasma activation of the CF x film using in situ surface infrared spectroscopy and ellipsometry. Infrared spectra of the surface after the CF x deposition half-cycle from a C 4 F 8 /Ar plasma show that an atomically thin mixing layer is formed between the deposited CF x layer and the underlying SiO 2 film. Etching during the Ar plasma cycle is activated by Ar + bombardment of the CF x layer, which results in the simultaneous removal of surface CF x and the underlying SiO 2 film. The interfacial mixing layer in ALE is atomically thin due to the low ion energy during CF x deposition, which combined with an ultrathin CF x layer ensures an etch rate of a few monolayers per cycle. In situ ellipsometry shows that for a ∼4 Å thick CF x film, ∼3-4 Å of SiO 2 was etched per cycle. However, during the Ar plasma half-cycle, etching proceeds beyond complete removal of the surface CF x layer as F-containing radicals are slowly released into the plasma from the reactor walls. Buildup of CF x on reactor walls leads to a gradual increase in the etch per cycle.

Fabrication of bundle-structured tube-leaky optical fibers for infrared thermal imaging

NASA Astrophysics Data System (ADS)

Kobayashi, T.; Katagiri, T.; Matsuura, Y.

2017-02-01

Bundled glass tubular fibers were fabricated by glass drawing technique for endoscopic infrared-thermal imaging. The bundle fibers were made of borosilicate glass and have a structure like a photonic crystal fiber having multiple hollow cores. Fabricated fibers have a length of 90 cm and each pixel sizes are less than 80 μm. By setting the thickness of glass wall to a quarter-wavelength optical thickness, light is confined in the air core as a leaky mode with a low loss owing to the interference effect of the thin glass wall and this type of hollow-core fibers is known as tube leaky fibers. The transmission losses of bundled fibers were firstly measured and it was found that bundled tube-leaky fibers have reasonably low transmission losses in spite of the small pixel size. Then thermal images were delivered by the bundled fibers combining with an InSb infrared camera. Considering applications with rigid endoscopes, an imaging system composed of a 30-cm long fiber bundle and a half-ball lens with a diameter of 2 mm was fabricated. By using this imaging system, a metal wire with a thickness of 200 μm was successfully observed and another test showed that the minimum detected temperature was 32.0 °C and the temperature resolution of the system was around 0.7 °C.

Computational modeling of epidural cortical stimulation

NASA Astrophysics Data System (ADS)

Wongsarnpigoon, Amorn; Grill, Warren M.

2008-12-01

Epidural cortical stimulation (ECS) is a developing therapy to treat neurological disorders. However, it is not clear how the cortical anatomy or the polarity and position of the electrode affects current flow and neural activation in the cortex. We developed a 3D computational model simulating ECS over the precentral gyrus. With the electrode placed directly above the gyrus, about half of the stimulus current flowed through the crown of the gyrus while current density was low along the banks deep in the sulci. Beneath the electrode, neurons oriented perpendicular to the cortical surface were depolarized by anodic stimulation, and neurons oriented parallel to the boundary were depolarized by cathodic stimulation. Activation was localized to the crown of the gyrus, and neurons on the banks deep in the sulci were not polarized. During regulated voltage stimulation, the magnitude of the activating function was inversely proportional to the thickness of the CSF and dura. During regulated current stimulation, the activating function was not sensitive to the thickness of the dura but was slightly more sensitive than during regulated voltage stimulation to the thickness of the CSF. Varying the width of the gyrus and the position of the electrode altered the distribution of the activating function due to changes in the orientation of the neurons beneath the electrode. Bipolar stimulation, although often used in clinical practice, reduced spatial selectivity as well as selectivity for neuron orientation.

Preparation of multi-layer film consisting of hydrogen-free DLC and nitrogen-containing DLC for conductive hard coating

NASA Astrophysics Data System (ADS)

Iijima, Yushi; Harigai, Toru; Isono, Ryo; Degai, Satoshi; Tanimoto, Tsuyoshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Yasui, Haruyuki; Kaneko, Satoru; Kunitsugu, Shinsuke; Kamiya, Masao; Taki, Makoto

2018-01-01

Conductive hard-coating films have potential application as protective films for contact pins used in the electrical inspection process for integrated circuit chips. In this study, multi-layer diamond-like carbon (DLC) films were prepared as conductive hard-coating films. The multi-layer DLC films consisting of DLC and nitrogen-containing DLC (N-DLC) film were prepared using a T-shape filtered arc deposition method. Periodic DLC/N-DLC four-layer and eight-layer films had the same film thickness by changing the thickness of each layer. In the ball-on-disk test, the N-DLC mono-layer film showed the highest wear resistance; however, in the spherical polishing method, the eight-layer film showed the highest polishing resistance. The wear and polishing resistance and the aggressiveness against an opponent material of the multi-layer DLC films improved by reducing the thickness of a layer. In multi-layer films, the soft N-DLC layer between hard DLC layers is believed to function as a cushion. Thus, the tribological properties of the DLC films were improved by a multi-layered structure. The electrical resistivity of multi-layer DLC films was approximately half that of the DLC mono-layer film. Therefore, the periodic DLC/N-DLC eight-layer film is a good conductive hard-coating film.

Substrate spacing and thin-film yield in chemical bath deposition of semiconductor thin films

NASA Astrophysics Data System (ADS)

Arias-Carbajal Reádigos, A.; García, V. M.; Gomezdaza, O.; Campos, J.; Nair, M. T. S.; Nair, P. K.

2000-11-01

Thin-film yield in the chemical bath deposition technique is studied as a function of separation between substrates in batch production. Based on a mathematical model, it is proposed and experimentally verified in the case of CdS thin films that the film thickness reaches an asymptotic maximum with increase in substrate separation. It is shown that at a separation less than 1 mm between substrates the yield, i.e. percentage in moles of a soluble cadmium salt deposited as a thin film of CdS, can exceed 50%. This behaviour is explained on the basis of the existence of a critical layer of solution near the substrate, within which the relevant ionic species have a higher probability of interacting with the thin-film layer than of contributing to precipitate formation. The critical layer depends on the solution composition and the temperature of the bath as well as the duration of deposition. An effective value for the critical layer thickness has been defined as half the substrate separation at which 90% of the maximum film thickness for the particular bath composition, bath temperature and duration of deposition is obtained. In the case of CdS thin films studied as an example, the critical layer is found to extend from 0.5 to 2.5 mm from the substrate surface, depending on the deposition conditions.

The structure of a Mesozoic basin beneath the Lake Tana area, Ethiopia, revealed by magnetotelluric imaging

NASA Astrophysics Data System (ADS)

Hautot, Sophie; Whaler, Kathryn; Gebru, Workneh; Desissa, Mohammednur

2006-03-01

The northwestern Plateau of Ethiopia is almost entirely covered with extensive Tertiary continental flood basalts that mask the underlying formations. Mesozoic and Tertiary sediments are exposed in a few locations surrounding the Lake Tana area suggesting that the Tana depression is an extensional basin buried by the 1-2 km thick Eocene-Oligocene flood basalt sequences in this region. A magnetotelluric survey has been carried out to investigate the deep structure of the Tana area. The objectives were to estimate the thickness of the volcanics and anticipated underlying sedimentary basin. We have collected 27 magnetotelluric soundings south and east of Lake Tana. Two-dimensional inversion of the data along a 160 km long profile gives a model consistent with a NW-SE trending sedimentary basin beneath the lava flows. The thickness of sediments overlying the Precambrian basement averages 1.5-2 km, which is comparable to the Blue Nile stratigraphic section, south of the area. A 1 km thickening of sediments over a 30-40 km wide section suggests that the form of the basin is a half-graben. It is suggested that electrically resistive features in the model are related to volcanic materials intruded within the rift basin sediments through normal faults. The results illustrate the strong control of the Precambrian fracture zones on the feeding of the Tertiary Trap series.

Coal resources of the Fruitland Formation in part of the Ute Mountain Ute Indian Reservation, San Juan County, New Mexico

USGS Publications Warehouse

Roberts, Laura N. Robinson

1991-01-01

The coal-bearing Upper Cretaceous Fruitland Formation occupies an area of about 14 square miles in the extreme southeast corner of the Ute Mountain Ute Indian Reservation in San Juan County, New Mexico. In this area, the Fruitland Formation contains an estimated 252 million short tons of coal in beds that range from 1.2 to 14 feet thick. About 100 million short tons of coal occur under less than 500 feet of overburden in the Ute Canyon, Upper Main, and Main coal beds. These three coal beds reach a cumulative coal thickness of about 18 feet in a stratigraphic interval that averages about 120 feet thick in the prospecting permit area, which is located in the extreme southwestern part of the study area. The southwestern part of the study area is probably best suited for surface mining, although steep dips may reduce minability locally. A major haul road that was recently constructed across the eastern half of the study area greatly improves the potential for surface mining. Core sample analyses indicate that the apparent rank of the Ute Canyon, Upper Main, and Main coal beds is high-volatile C bituminous. Average heat-of-combustion on an as-received basis is 10,250 British thermal units per pound, average ash content is 15.5 percent, and average sulfur content is 1.0 percent.

Improving the Total Impulse Capability of the NSTAR Ion Thruster With Thick-Accelerator-Grid Ion Optics

NASA Technical Reports Server (NTRS)

Soulas, George C.

2001-01-01

The results of performance tests with thick-accelerator-grid (TAG) ion optics are presented. TAG ion optics utilize a 50 percent thicker accelerator grid to double ion optics' service life. NSTAR ion optics were also tested to provide a baseline performance for comparison. Impingement-limited total voltages for the TAG ion optics were only 0 to 15 V higher than those of the NSTAR ion optics. Electron backstreaming limits for the TAG ion optics were 3 to 9 V higher than those for the NSTAR optics due to the increased accelerator grid thickness for the TAG ion optics. Screen grid ion transparencies for the TAG ion optics were only about 2 percent lower than those for the NSTAR optics, reflecting the lower physical screen grid open area fraction of the TAG ion optics. Accelerator currents for the TAG ion optics were 19 to 43 percent greater than those for the NSTAR ion optics due, in part, to a sudden increase in accelerator current during TAG ion optics' performance tests for unknown reasons and to the lower-than-nominal accelerator aperture diameters. Beam divergence half-angles that enclosed 95 percent of the total beam current and beam divergence thrust correction factors for the TAG ion optics were within 2 degrees and 1 percent, respectively, of those for the NSTAR ion optics.

Studies of uranium carbide targets of a high density

NASA Astrophysics Data System (ADS)

Panteleev, V. N.; Alyakrinskiy, O.; Barbui, M.; Barzakh, A. E.; Dubois, M.; Eleon, C.; Essabaa, S.; Fedorov, D. V.; Gaubert, G.; Ionan, A. M.; Ivanov, V. S.; Jardin, P.; Lau, C.; Leroy, R.; Lhersonneau, G.; Mezilev, K. A.; Mhamed, C.; Molkanov, P. L.; Moroz, F. V.; Orlov, S. Yu.; Saint Laurent, M. G.; Stroe, L.; Tecchio, L. B.; Tonezzer, M.; Villari, A. C. C.; Volkov, Yu. M.

2008-10-01

Production of Cs and Fr isotopes from uranium carbide targets of a high density has been investigated at IRIS (Investigation Radioactive Isotopes at Synchrocyclotron), Gatchina. The UC target material with a density of 12 g/cm3 was prepared in a form of pellets. Two targets were tested on-line under the same temperature conditions: (a) a reference small target with a thickness of 4.5 g/cm2; (b) a heavier (so called intermediate) target with a thickness of 91 g/cm2. Yields and release efficiencies of nuclides with half-lives from some minutes to some milliseconds produced by 1 GeV protons in these targets are presented. It is remarkable that yields, even those of very short-lived isotopes such as 214Fr (T1/2 = 5 ms) and 219Fr (T1/2 = 20 ms), increase proportionally to the target thickness. A one month off-line heating test of the 91 g/cm2 target at a temperature of 2000 °C has been carried out successfully. The yields and release efficiencies of Cs and Fr measured on-line before and after the heating test coincided within the limits of measurement errors, thereby demonstrating the conservation of the target unit parameters. Based on these very promising results, a heavier target with a mass about 0.7 kg is prepared presently at IRIS.

Influences of the inner retinal sublayers and analytical areas in macular scans by spectral-domain OCT on the diagnostic ability of early glaucoma.

PubMed

Nakatani, Yusuke; Higashide, Tomomi; Ohkubo, Shinji; Sugiyama, Kazuhisa

2014-10-23

We investigated the influences of the inner retinal sublayers and analytical areas in macular scans by spectral-domain optical coherence tomography (OCT) on the diagnostic ability of early glaucoma. A total of 64 early (including 24 preperimetric) glaucomatous and 40 normal eyes underwent macular and peripapillary retinal nerve fiber layer (pRNFL) scans (3D-OCT-2000). The area under the receiver operating characteristics (AUC) for glaucoma diagnosis was determined from the average thickness of the total 100 grids (6 × 6 mm), central 44 grids (3.6 × 4.8 mm), and peripheral 56 grids (outside of the 44 grids), and for each macular sublayer: macular RNFL (mRNFL), ganglion cell layer plus inner plexiform layer (GCL/IPL), and mRNFL plus GCL/IPL (ganglion cell complex [GCC]). Correlation of OCT parameters with visual field parameters was evaluated by Spearman's rank correlation coefficients (rs). The GCC-related parameters had a significantly larger AUC (0.82-0.97) than GCL/IPL (0.81-0.91), mRNFL-related parameters (0.72-0.94), or average pRNFL (0.88) in more than half of all comparisons. The central 44 grids had a significantly lower AUC than other analytical areas in GCC and mRNFL thickness. Conversely, the peripheral 56 grids had a significantly lower AUC than the 100 grids in GCL/IPL inferior thickness. Inferior thickness of GCC (rs, 0.45-0.49) and mRNFL (rs, 0.43-0.51) showed comparably high correlations with central visual field parameters to average pRNFL thickness (rs, 0.41, 0.47) even in the central 44 grids. The diagnostic ability of macular OCT parameters for early glaucoma differed by inner retinal sublayers and also by the analytical areas studied. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Large Volcanic Rises on Venus

NASA Technical Reports Server (NTRS)

Smrekar, Suzanne E.; Kiefer, Walter S.; Stofan, Ellen R.

1997-01-01

Large volcanic rises on Venus have been interpreted as hotspots, or the surface manifestation of mantle upwelling, on the basis of their broad topographic rises, abundant volcanism, and large positive gravity anomalies. Hotspots offer an important opportunity to study the behavior of the lithosphere in response to mantle forces. In addition to the four previously known hotspots, Atla, Bell, Beta, and western Eistla Regiones, five new probable hotspots, Dione, central Eistla, eastern Eistla, Imdr, and Themis, have been identified in the Magellan radar, gravity and topography data. These nine regions exhibit a wider range of volcano-tectonic characteristics than previously recognized for venusian hotspots, and have been classified as rift-dominated (Atla, Beta), coronae-dominated (central and eastern Eistla, Themis), or volcano-dominated (Bell, Dione, western Eistla, Imdr). The apparent depths of compensation for these regions ranges from 65 to 260 km. New estimates of the elastic thickness, using the 90 deg and order spherical harmonic field, are 15-40 km at Bell Regio, and 25 km at western Eistla Regio. Phillips et al. find a value of 30 km at Atla Regio. Numerous models of lithospheric and mantle behavior have been proposed to interpret the gravity and topography signature of the hotspots, with most studies focusing on Atla or Beta Regiones. Convective models with Earth-like parameters result in estimates of the thickness of the thermal lithosphere of approximately 100 km. Models of stagnant lid convection or thermal thinning infer the thickness of the thermal lithosphere to be 300 km or more. Without additional constraints, any of the model fits are equally valid. The thinner thermal lithosphere estimates are most consistent with the volcanic and tectonic characteristics of the hotspots. Estimates of the thermal gradient based on estimates of the elastic thickness also support a relatively thin lithosphere (Phillips et al.). The advantage of larger estimates of the thermal lithospheric thickness is that they provide an explanation for the apparently modest levels of geologic activity on Venus over the last half billion years.

Superficial Fascia (SF) in the Cheek and Parotid Area: Histology and Magnetic Resonance Image (MRI).

PubMed

Hwang, Kun; Kim, Hun; Kim, Dae Joong; Kim, Yeo Ju; Kang, Young Hye

2016-08-01

The aim of this study is to compare the superficial fascia (SF) in the cheek and parotid areas histologically and through MRI. An in vitro study included a histological report and an MRI of the cheek of two Korean adult cadavers. The in vivo study included 100 MRI images and three axial image cuts (mandibular condyle, notch, and half the distance between the top of the condyle and the angle). Four angles, one length, and four thicknesses were measured and compared. The MRI results were in concord with the gross specimen or histology. The SF consisted of multilayered horizontal and vertical fibrous connective tissues at all three levels in both the histology and MRI. In the cheek, both histology and MRI showed horizontal fibrous connective tissues which were connected with the zygomaticus major, visualized as a continuous membrane (membranous layer, MSF). MSF divided the SF into the superficial fatty layer (SFS) and the deep fatty layer. The thickness of the SF depended upon the thickness of the SFS since the thickness of the MSF was very similar irrespective of the three levels. The thickness of the SFS was thicker in females than in males. At the condyle level, the AS-PS angle (AP line-the most posterior superficial fascia angle) and AS-PS length increased significantly (p = 0.001, y = 0.15x + 16.19, and p < 0.001, y = 0.33x + 14.68, respectively). We hope the information we have gathered could be useful to provide subcutaneous dissection or sub-SMAS dissection in facelift surgeries. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Optimization of tungsten x-ray spectra for digital mammography: a comparison of model to experiment

NASA Astrophysics Data System (ADS)

Andre, Michael P.; Spivey, Brett A.

1997-05-01

Tungsten (W) target x-rays tubes are being studied for use in digital mammography to improve x-ray flux, reduce noise and increase tube heat capacity. A parametric model was developed for digital mammography to evaluate optimization of x-ray spectra for a particular sensor. The model computes spectra and mean glandular doses (MGD) for combinations of W target, beam filters, kVp, breast type and thickness. Two figures of merit were defined: (signal/noise)2/MGD and spectral quantum efficiency; these were computed as a means to approach optimization of object contrast. The model is derived from a combination of classic equations, XCOM from NBS, and published data. X-ray spectra were calculated and measured for filters of Al, Sn, Rh, Mo and Ag on a Eureka tube. (Signal/noise)2/MGD was measured for a filtered W target tube and a digital camera employing CsI scintillator optically coupled to a CCD for which the detective quantum efficiency (DQE) was known. A 3-mm thick acrylic disk was imaged on thickness of 3-8 cm of acrylic and the results were compared to the predictions of the model. The relative error between predicted and measured spectra was +/- 2 percent from 24 to 34 kVp. Calculated MGD as a function of breast thickness, half-value layer and beam filter compares very well to published data. Best performance was found for the following combinations: Mo filter with 30 mm breast, Ag filter with 45 mm, Sn filter for 60 mm, and Al filter for 75 mm thick breast. The parametric model agrees well with measurement and provides a means to explore optimum combinations of kVp and beam filter. For a particular detector, this data may be used with the DQE to estimate total system signal-to-noise ratio for a particular imaging task.

Experimental Investigation of Premixed Turbulent Hydrocarbon/Air Bunsen Flames

NASA Astrophysics Data System (ADS)

Tamadonfar, Parsa

Through the influence of turbulence, the front of a premixed turbulent flame is subjected to the motions of eddies that leads to an increase in the flame surface area, and the term flame wrinkling is commonly used to describe it. If it is assumed that the flame front would continue to burn locally unaffected by the stretch, then the total turbulent burning velocity is expected to increase proportionally to the increase in the flame surface area caused by wrinkling. When the turbulence intensity is high enough such that the stretch due to hydrodynamics and flame curvature would influence the local premixed laminar burning velocity, then the actual laminar burning velocity (that is, flamelet consumption velocity) should reflect the influence of stretch. To address this issue, obtaining the knowledge of instantaneous flame front structures, flame brush characteristics, and burning velocities of premixed turbulent flames is necessary. Two axisymmetric Bunsen-type burners were used to produce premixed turbulent flames, and three optical measurement techniques were utilized: Particle image velocimetry to measure the turbulence statistics; Rayleigh scattering method to measure the temperature fields of premixed turbulent flames, and Mie scattering method to visualize the flame front contours of premixed turbulent flames. Three hydrocarbons (methane, ethane, and propane) were used as the fuel in the experiments. The turbulence was generated using different perforated plates mounted upstream of the burner exit. A series of comprehensive parameters including the thermal flame front thickness, characteristic flame height, mean flame brush thickness, mean volume of the turbulent flame region, two-dimensional flame front curvature, local flame front angle, two-dimensional flame surface density, wrinkled flame surface area, turbulent burning velocity, mean flamelet consumption velocity, mean turbulent flame stretch factor, mean turbulent Markstein length and number, and mean fuel consumption rate were systematically evaluated from the experimental data. The normalized preheat zone and reaction zone thicknesses decreased with increasing non-dimensional turbulence intensity in ultra-lean premixed turbulent flames under a constant equivalence ratio of 0.6, whereas they increased with increasing equivalence ratios from 0.6 to 1.0 under a constant bulk flow velocity. The normalized preheat zone and reaction zone thicknesses showed no overall trend with increasing non-dimensional longitudinal integral length scale. The normalized preheat zone and reaction zone thicknesses decreased by increasing the Karlovitz number, suggesting that increasing the total stretch rate is the controlling mechanism in the reduction of flame front thickness for the experimental conditions studied in this thesis. In general, the leading edge and half-burning surface turbulent burning velocities were enhanced with increasing equivalence ratio from lean to stoichiometric mixtures, whereas they decreased with increasing equivalence ratio for rich mixtures. These velocities were enhanced with increasing total turbulence intensity. The leading edge and half-burning surface turbulent burning velocities for lean/stoichiometric mixtures were observed to be smaller than that for rich mixtures. The mean turbulent flame stretch factor displayed a dependence on the equivalence ratio and turbulence intensity. Results show that the mean turbulent flame stretch factors for lean/stoichiometric and rich mixtures were not equal when the unstrained premixed laminar burning velocity, non-dimensional bulk flow velocity, non-dimensional turbulence intensity, and non-dimensional longitudinal integral length scale were kept constant.

Atomically Visualizing Elemental Segregation-Induced Surface Alloying and Restructuring

DOE PAGES

Zou, Lianfeng; Li, Jonathan; Zakharov, Dmitri; ...

2017-12-01

Using in situ transmission electron microscopy that spatially and temporally resolves the evolution of the atomic structure in the surface and subsurface regions, we Find that the surface segregation of Au atoms in a Cu(Au) solid solution results in the nucleation and growth of a (2 × 1) missing-row reconstructed, half-unit-cell thick L1 2 Cu 3Au(110) surface alloy. Our in situ electron microscopy observations and atomistic simulations demonstrate that the (2 × 1) reconstruction of the Cu 3Au(110) surface alloy remains as a stable surface structure as a result of the favored Cu-Au diatom configuration.

Comparison of Spall Pullback Signals and X-ray Tomography Analysis in Copper

NASA Astrophysics Data System (ADS)

Gard, Marcie; Russell, Rod; Hanna, Romy; Bless, Stephan; InstituteAdvanced Technology Collaboration; Department of Geological Sciences-UT Austin Collaboration

2011-06-01

Spall experiments were conducted on electrolytic tough pitch C110 copper plates. Flyer plates half the target-plate thickness were launched with a single-stage compressed-gas gun. Pullback signals were measured with a photonic Doppler velocimeter (PDV). Spall stresses were determined and found to be about 1 GPa. In addition, damage on the spall plane for samples that failed to separate a spall plate was characterized by x-ray tomography. The paper will include a description of threshold damage. The threshold for appearance of a pullback signal corresponded to the initiation of tensile damage, not formation of a spall separation plane.

Geometric optics-based multiband cloaking of large objects with the wave phase and amplitude preservation.

PubMed

Duan, Ran; Semouchkina, Elena; Pandey, Ravi

2014-11-03

The geometric optics principles are used to develop a unidirectional transmission cloak for hiding objects with dimensions substantially exceeding the incident radiation wavelengths. Invisibility of both the object and the cloak is achieved without metamaterials, so that significant widths of the cloaking bands are provided. For the preservation of wave phases, the λ-multiple delays of waves passing through the cloak are realized. Suppression of reflection losses is achieved by using half-λ multiple thicknesses of optical elements. Due to periodicity of phase delay and reflection suppression conditions, the cloak demonstrates efficient multiband performance confirmed by full-wave simulations.

Preliminary structural design of a lunar transfer vehicle aerobrake. M.S. Thesis

NASA Technical Reports Server (NTRS)

Bush, Lance B.

1992-01-01

An aerobrake concept for a Lunar transfer vehicle was weight optimized through the use of the Taguchi design method, structural finite element analyses and structural sizing routines. Six design parameters were chosen to represent the aerobrake structural configuration. The design parameters included honeycomb core thickness, diameter to depth ratio, shape, material, number of concentric ring frames, and number of radial frames. Each parameter was assigned three levels. The minimum weight aerobrake configuration resulting from the study was approx. half the weight of the average of all twenty seven experimental configurations. The parameters having the most significant impact on the aerobrake structural weight were identified.

Lubricant Coating Process

NASA Technical Reports Server (NTRS)

1989-01-01

"Peen Plating," a NASA developed process for applying molybdenum disulfide, is the key element of Techniblast Co.'s SURFGUARD process for applying high strength solid lubricants. The process requires two machines -- one for cleaning and one for coating. The cleaning step allows the coating to be bonded directly to the substrate to provide a better "anchor." The coating machine applies a half a micron thick coating. Then, a blast gun, using various pressures to vary peening intensities for different applications, fires high velocity "media" -- peening hammers -- ranging from plastic pellets to steel shot. Techniblast was assisted by Rural Enterprises, Inc. Coating service can be performed at either Techniblast's or a customer's facility.

KSC-99wl06

NASA Image and Video Library

1999-01-08

KENNEDY SPACE CENTER, FLA. -- Spotted in the Merritt Island National Wildlife Refuge, which shares a boundary with the space center, an anhinga captures a fish in its long, dagger-shaped bill. It is also known as the "snakebird" because in the water its body is submerged so that only its head and long, slender neck are visible. Ranging the Atlantic and Gulf Coasts from North Carolina to Texas, north in the Mississippi Valley to Arkansas and Tennessee, and in the South to South America, it inhabits freshwater ponds and swamps with thick vegetation. They are often seen with wings half-open, drying them in the sun since they lack oil glands with which to preen

A surface impedance-based three-channel acoustic metasurface retroreflector

NASA Astrophysics Data System (ADS)

Shen, Chen; Díaz-Rubio, Ana; Li, Junfei; Cummer, Steven A.

2018-04-01

We propose the design and measurement of an acoustic metasurface retroreflector that works at three discrete incident angles. An impedance model is developed such that for acoustic waves impinging at -60°, the reflected wave is defined by the surface impedance of the metasurface, which is realized by a periodic grating. At 0° and 60°, the retroreflection condition can be fulfilled by the diffraction of the surface. The thickness of the metasurface is about half of the operating wavelength and the retroreflector functions without parasitic diffraction associated with conventional gradient-index metasurfaces. Such highly efficient and compact retroreflectors open up possibilities in metamaterial-based acoustic sensing and communications.

Drag measurements of an axisymmetric nacelle mounted on a flat plate at supersonic speeds

NASA Technical Reports Server (NTRS)

Flamm, Jeffrey D.; Wilcox, Floyd J., Jr.

1995-01-01

An experimental investigation was conducted to determine the effect of diverter wedge half-angle and nacelle lip height on the drag characteristics of an assembly consisting of a nacelle fore cowl from a typical high-speed civil transport (HSCT) and a diverter mounted on a flat plate. Data were obtained for diverter wedge half-angles of 4.0 deg, 6.0 deg, and 8.0 deg and ratios of the nacelle lip height above a flat plate to the boundary-layer thickness (h(sub n)/delta) of approximately 0.87 to 2.45. Limited drag data were also obtained on a complete nacelle/diverter configuration that included fore and aft cowls. Although the nacelle/diverter drag data were not corrected for base pressures or internal flow drag, the data are useful for comparing the relative drag of the configuration tested. The tests were conducted in the Langley Unitary Plan Wind Tunnel at Mach numbers of 1.50, 1.80, 2.10, and 2.40 and Reynolds numbers ranging from 2.00 x 10(exp 6) to 5.00 x 10(exp 6) per foot. The results of this investigation showed that the nacelle/diverter drag essentially increased linearly with increasing h(sub n)/delta except near 1.0 where the data showed a nonlinear behavior. This nonlinear behavior was probably caused by the interaction of the shock waves from the nacelle/diverter configuration with the flat-plate boundary layer. At the lowest h(sub n)/delta tested, the diverter wedge half-angle had virtually no effect on the nacelle/diverter drag. However, as h(sub n)/delta increased, the nacelle/diverter drag increased as diverter wedge half-angle increased.

Dissipation kinetics of pre-plant pesticides in greenhouse-devoted soils.

PubMed

López-Fernández, O; Rial-Otero, R; Simal-Gándara, J; Boned, J

2016-02-01

This work was conducted to study the distribution of methyl isothiocyanate (MITC) in greenhouse soils treated with the fumigant dazomet (DZ) from the formulated product "Basamid Granular(®)", but also of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) from the fumigant "Agrocelhone NE(®)". In order to achieve this aim, several methods for the determination of fumigants residues in soils, but also pepper fruits were optimized and characterized. With independence of the soil depth, no residues of MITC, 1,3-D and CP above the detection limits were observed in soils covered with a polyethylene (PE) film (0.04 mm thick) after 27, 13 and 8 days of treatment, respectively. Liberation and dissipation curves of MITC in soil in presence of a PE film (0.04 mm) used to limit volatilization losses were also obtained. According to the results, the rate of decomposition of DZ into MITC have a half-life of 3.7 days in the surface horizon (5-10 cm) of the soil while in the subsurface horizon (15-20 cm), MITC formation rate is slightly slow (half-life of 3.2 days). With respect to the dissipation process, half-lives lower than 1 day were obtained for both depths (0.8 and 0.9 for the surface and the subsurface horizon, respectively). In the case of 1,3-D and CP in soil, the dissipation half-life of 1,3-D on soils was a bit higher than for CP (2 days vs. 1). In addition, the presence of residues of the fumigants on green pepper fruits grown on the treated soils was not detected as expected. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison of the characteristics in hen and quail corneas as experimental models of refractive surgery.

PubMed

Gonçalves, G C; Pérez-Merino, P; Martínez-García, M C; Barcía, A; Merayo-Loves, J

2016-07-01

To compare the histological, morphological and the biophysical measurements between hen and quail corneas, in order to determine which of them were better suited for use as an animal model for research into corneal refractive surgery. A study was performed using the biophysical measurements of the cornea (curvature, thickness, refraction, and axial length) of 20 animals (10 hens and 10 quails). The corneas were then prepared for histological analysis under microscopy light. The analysis showed that both groups have the same number of corneal layers as the human cornea and with an evident Bowman's layer. The thickness of the hen cornea and axial length of the eye, 225.3±18.4μm and 12.8±0.25mm, respectively, were larger than that of the quail (P<.01 and P<.001, respectively). The radius of curvature for the hen central cornea, 3.65±0.08mm, was greater than that for the quail (P<.001), but the refractive power of each cornea was similar. The proportion of total corneal thickness of the hen stroma, 82.6%, was more similar to that of the human than was the quail stroma, 72.5%. Within the hen stroma, the density of keratocytes, 8.57±1.49 per 5,000μm(2), was about half that in the quail stroma (P<.005). Because of the large size of the hen cornea, the stromal thickness and proportional similarity of the corneal layers with human cornea, the hen maybe better than the quail as an alternative species suitable for use in studies of corneal refractive surgery. Copyright © 2016 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

Narrow Energy Spread Protons and Ions from High-Intensity, High-Contrast Laser Solid Target Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dollar, Franklin; Matsuoka, Takeshi; McGuffey, Christopher

2010-11-04

Recent simulations show that an idealized, high intensity, short pulse laser can generate quasi-monoenergetic proton beams with energies over 100 MeV in an interaction with a thin film. However, most short pulse laser facilities with sufficient intensity have difficulty controlling the nanosecond and picosecond contrast necessary to realize such a regime. Experiments were performed to investigate proton and ion acceleration from a high contrast, short pulse laser by employing dual plasma mirrors along with a deformable mirror at the HERCULES laser facility at the Center for Ultrafast Optical Sciences, University of Michigan. Plasma mirrors were characterized, allowing a 50% throughputmore » with an intensity contrast increase of 105. The focal spot quality was also exceptional, showing a 1.1 micron full width at half maximum (FWHM) focal diameter. Experiments were done using temporally cleaned 30 TW, 32 fs pulses to achieve an intensity of up to 10{sup 21} Wcm{sup -2} on Si{sub 3}N{sub 4} and Mylar targets with thicknesses ranging 50 nm to 13 microns. Proton beams with energy spreads below 2 MeV were observed from all thicknesses, peaking with energies up to 10.3 MeV and an energy spread of 0.8 MeV. Similar narrow energy spreads were observed for oxygen, nitrogen, and carbon at the silicon nitride thickness of 50 nm with energies up to 24 MeV with an energy spread of 3 MeV, whereas the energy spread is greatly increased at a larger thickness. Maximum energies were confirmed with CR39 track detectors, while a Thomson ion spectrometer was used to gauge the monoenergetic nature of the beam.« less

In-vitro performance and fracture strength of thin monolithic zirconia crowns

PubMed Central

Weigl, Paul; Wu, Yanyun; Felber, Roland; Lauer, Hans-Christoph

2018-01-01

PURPOSE All-ceramic restorations required extensive tooth preparation. The purpose of this in vitro study was to investigate a minimally invasive preparation and thickness of monolithic zirconia crowns, which would provide sufficient mechanical endurance and strength. MATERIALS AND METHODS Crowns with thickness of 0.2 mm (group 0.2, n=32) or of 0.5 mm (group 0.5, n=32) were milled from zirconia and fixed with resin-based adhesives (groups 0.2A, 0.5A) or zinc phosphate cements (groups 0.2C, 0.5C). Half of the samples in each subgroup (n=8) underwent thermal cycling and mechanical loading (TCML)(TC: 5℃ and 55℃, 2×3,000 cycles, 2 min/cycle; ML: 50 N, 1.2×106 cycles), while the other samples were stored in water (37℃/24 h). Survival rates were compared (Kaplan-Maier). The specimens surviving TCML were loaded to fracture and the maximal fracture force was determined (ANOVA; Bonferroni; α=.05). The fracture mode was analyzed. RESULTS In both 0.5 groups, all crowns survived TCML, and the comparison of fracture strength among crowns with and without TCML showed no significant difference (P=.628). Four crowns in group 0.2A and all of the crowns in group 0.2C failed during TCML. The fracture strength after 24 hours of the cemented 0.2 mm-thick crowns was significantly lower than that of adhesive bonded crowns. All cemented crowns provided fracture in the crown, while about 80% of the adhesively bonded crowns fractured through crown and die. CONCLUSION 0.5 mm thick monolithic crowns possessed sufficient strength to endure physiologic performance, regardless of the type of cementation. Fracture strength of the 0.2 mm cemented crowns was too low for clinical application. PMID:29713427

Major Element Analysis of the Target Rocks at Meteor Crater, Arizona

NASA Technical Reports Server (NTRS)

See, Thomas H.; Hoerz, Friedrich; Mittlefehldt, David W.; Varley, Laura; Mertzman, Stan; Roddy, David

2002-01-01

We collected approximately 400 rock chips in continuous vertical profile at Meteor Crater, Arizona, representing, from bottom to top, the Coconino, Toroweap, Kaibab, and Moenkopi Formations to support ongoing compositional analyses of the impact melts and their stratigraphic source depth(s) and other studies at Meteor Crater that depend on the composition of the target rocks. These rock chips were subsequently pooled into 23 samples for compositional analysis by XRF (x ray fluorescence) methods, each sample reflecting a specific stratigraphic "subsection" approximately 5-10 in thick. We determined the modal abundance of quartz, dolomite, and calcite for the entire Kaibab Formation at vertical resolutions of 1-2 meters. The Coconino Formation composes the lower half of the crater cavity. It is an exceptionally pure sandstone. The Toroweap is only two inches thick and compositionally similar to Coconino, therefore, it is not a good compositional marker horizon. The Kaibab Formation is approximately 80 in thick. XRD (x ray diffraction) studies show that the Kaibab Formation is dominated by dolomite and quartz, albeit in highly variable proportions; calcite is a minor phase at best. The Kaibab at Meteor Crater is therefore a sandy dolomite rather than a limestone, consistent with pronounced facies changes in the Permian of SE Arizona over short vertical and horizontal distances. The Moenkopi forms the 12 in thick cap rock and has the highest Al2O3 and FeO concentrations of all target rocks. With several examples, we illustrate how this systematic compositional and modal characterization of the target ideologies may contribute to an understanding of Meteor Crater, such as the depth of its melt zone, and to impact cratering in general, such as the liberation of CO2 from shocked carbonates.

Variations in pesticide leaching related to land use, pesticide properties, and unsaturated zone thickness

USGS Publications Warehouse

Webb, R.M.T.; Wieczorek, M.E.; Nolan, B.T.; Hancock, T.C.; Sandstrom, M.W.; Barbash, J.E.; Bayless, E.R.; Healy, R.W.; Linard, J.

2008-01-01

Pesticide leaching through variably thick soils beneath agricultural fields in Morgan Creek, Maryland was simulated for water years 1995 to 2004 using LEACHM (Leaching Estimation and Chemistry Model). Fifteen individual models were constructed to simulate five depths and three crop rotations with associated pesticide applications. Unsaturated zone thickness averaged 4.7 m but reached a maximum of 18.7 m. Average annual recharge to ground water decreased from 15.9 to 11.1 cm as the unsaturated zone increased in thickness from 1 to 10 m. These point estimates of recharge are at the lower end of previously published values, which used methods that integrate over larger areas capturing focused recharge in the numerous detention ponds in the watershed. The total amount of applied and leached masses for five parent pesticide compounds and seven metabolites were estimated for the 32-km2 Morgan Creek watershed by associating each hectare to the closest one-dimensional model analog of model depth and crop rotation scenario as determined from land-use surveys. LEACHM parameters were set such that branched, serial, first-order decay of pesticides and metabolites was realistically simulated. Leaching is predicted to be greatest for shallow soils and for persistent compounds with low sorptivity. Based on simulation results, percent parent compounds leached within the watershed can be described by a regression model of the form e−depth (a ln t½−b ln KOC) where t 1/2 is the degradation half-life in aerobic soils, K OC is the organic carbon normalized sorption coefficient, and a and b are fitted coefficients (R 2 = 0.86, p value = 7 × 10−9).

The Last Gasp - the Terminal Magmatic Stages of the Keweenaw LIP

NASA Astrophysics Data System (ADS)

Rooney, T. O.; Brown, E.; Moucha, R.; Stein, C. A.; Stein, S.

2016-12-01

The Keweenaw Flood Basalts, which represent the magmatic record of the best preserved example of a Precambrian Large Igneous Province (LIP), erupted contemporaneously with the development of the failed Mid-Continent Rift ca. 1.1 Ga. At 2 x 106 km3 in volume, the Keweenaw LIP is roughly equivalent in scale to the Parana-Etendeka LIP, but the origin and evolution of the magmatic source of the Keweenaw LIP remains poorly constrained. Specifically, while modern LIPs have a primary magmatic pulse lasting <5Ma, followed by a long phase of waning activity, the Keweenaw LIP underwent significant flood basalt eruptions for ca. 21 Myr. Here we examine the geochemical characteristics of the final phases of magmatic activity within the Keweenaw LIP - the Lake Shore Traps - which erupted ca. 1087 Ma within an alluvial fan sequence (Copper Harbor Conglomerate). The Lake Shore Traps are best exposed at High Rock Bay, where 62 flows ( 1-30m thick) are observed intercalated with thin paleosols over a 530m thickness. Thus, while this late-stage activity might represent a waning phase of magmatism, the thickness represents some half of the total average thickness of modern continental flood basalt provinces. Our initial data suggests a dominantly tholeiitic magma series spanning an unexpectedly wide and continuous range of compositions from basalt to andesite; rare alkaline lavas are also evident. Distinctive geochemical stratigraphic patterns were observed suggesting crystal fractionation and recharge events dominated the magma system. Our initial data do not show any unambiguous parallels between the geochemical characteristics of the Lake Shore Traps and prior phases of magmatic activity in the province. We explore the potential source characteristics of these lavas to refine the source and conditions of melt generation during the terminal phase of activity in the region.

Orbitofrontal cortex and drug use during adolescence: role of prenatal exposure to maternal smoking and BDNF genotype.

PubMed

Lotfipour, Shahrdad; Ferguson, Eamonn; Leonard, Gabriel; Perron, Michel; Pike, Bruce; Richer, Louis; Séguin, Jean R; Toro, Roberto; Veillette, Suzanne; Pausova, Zdenka; Paus, Tomás

2009-11-01

Prenatal exposure to maternal cigarette smoking (PEMCS) may affect brain development and behavior in adolescent offspring. To evaluate the involvement of the orbitofrontal cortex (OFC) in mediating the relationship between PEMCS and substance use. Cross-sectional analyses from the Saguenay Youth Study aimed at evaluating the effects of PEMCS on brain development and behavior among adolescents. Nonexposed adolescents were matched with adolescents exposed prenatally to cigarette smoking by maternal educational level. A French Canadian founder population of the Saguenay-Lac-Saint-Jean region of Quebec, Canada. The behavioral data set included 597 adolescents (275 sibships; 12-18 years of age), half of whom were exposed in utero to maternal cigarette smoking. Analysis of cortical thickness and genotyping were performed using available data from 314 adolescents. The likelihood of substance use was assessed with the Diagnostic Interview Schedule for Children Predictive Scales. The number of different drugs tried by each adolescent was assessed using another questionnaire. Thickness of the OFC was estimated from T1-weighted magnetic resonance images using FreeSurfer software. Prenatal exposure to maternal cigarette smoking is associated with an increased likelihood of substance use. Among exposed adolescents, the likelihood of drug experimentation correlates with the degree of OFC thinning. In nonexposed adolescents, the thickness of the OFC increases as a function of the number of drugs tried. The latter effect is moderated by a brain-derived neurotrophic factor (BDNF) genotype (Val66Met). We speculate that PEMCS interferes with the development of the OFC and, in turn, increases the likelihood of drug use among adolescents. In contrast, we suggest that, among nonexposed adolescents, drug experimentation influences the OFC thickness via processes akin to experience-induced plasticity.

A molecular dynamics analysis of ion irradiation of ultrathin amorphous carbon films

NASA Astrophysics Data System (ADS)

Qi, J.; Komvopoulos, K.

2016-09-01

Molecular dynamics (MD) simulations provide insight into nanoscale problems where continuum description breaks down, such as the modeling of ultrathin films. Amorphous carbon (a-C) films are commonly used as protective overcoats in various contemporary technologies, including microelectromechanical systems, bio-implantable devices, optical lenses, and hard-disk drives. In all of these technologies, the protective a-C film must be continuous and very thin. For example, to achieve high storage densities (e.g., on the order of 1 Tb/in.2) in magnetic recording, the thickness of the a-C film used to protect the magnetic media and the recording head against mechanical wear and corrosion must be 2-3 nm. Inert ion irradiation is an effective post-deposition method for reducing the film thickness, while preserving the mechanical and chemical characteristics. In this study, MD simulations of Ar+ ion irradiated a-C films were performed to elucidate the effects of the ion incidence angle and ion kinetic energy on the film thickness and structure. The MD results reveal that the film etching rate exhibits a strong dependence on the ion kinetic energy and ion incidence angle, with a maximum etching rate corresponding to an ion incidence angle of ˜20°. It is also shown that Ar+ ion irradiation mainly affects the structure of the upper half of the ultrathin a-C film and that carbon atom hybridization is a strong function of the ion kinetic energy and ion incidence angle. The results of this study elucidate the effects of important ion irradiation parameters on the structure and thickness of ultrathin films and provide fundamental insight into the physics of dry etching.

Neutron shielding behavior of thermoplastic natural rubber/boron carbide composites

NASA Astrophysics Data System (ADS)

Mat Zali, Nurazila; Yazid, Hafizal; Megat Ahmad, Megat Harun Al Rashid

2018-01-01

Many shielding materials have been designed against the harm of different types of radiation to the human body. Today, polymer-based lightweight composites have been chosen by the radiation protection industry. In the present study, thermoplastic natural rubber (TPNR) composites with different weight percent of boron carbide (B4C) fillers (0% to 30%) were fabricated as neutron shielding through melt blending method. Neutron attenuation properties of TPNR/B4C composites have been investigated. The macroscopic cross section (Σ), half value layer (HVL) and mean free path length (λ) of the composites have been calculated and the transmission curves have been plotted. The obtained results show that Σ, HVL and λ greatly depend on the B4C content. Addition of B4C fillers into TPNR matrix were found to enhance the macroscopic cross section values thus decrease the mean free path length (λ) and half value layer (HVL) of the composites. The transmission curves exhibited that the neutron transmission of the composites decreased with increasing shielding thickness. These results showed that TPNR/B4C composites have high potential for neutron shielding applications.

Reflection and Transmission of P-Waves in an Intermediate Layer Lying Between Two Semi-infinite Media

NASA Astrophysics Data System (ADS)

Singh, Pooja; Chattopadhyay, Amares; Srivastava, Akanksha; Singh, Abhishek Kumar

2018-05-01

With a motivation to gain physical insight of reflection as well as transmission phenomena in frozen (river/ocean) situation for example in Antarctica and other coldest place on Earth, the present article undertakes the analysis of reflection and transmission of a plane wave at the interfaces of layered structured comprised of a water layer of finite thickness sandwiched between an upper half-space constituted of ice and a lower isotropic elastic half-space, which may be useful in geophysical exploration in such conditions. A closed form expression of reflection/transmission coefficients of reflected and transmitted waves has been derived in terms of angles of incidence, propagation vector, displacement vector and elastic constants of the media. Expressions corresponding to the energy partition of various reflected and transmitted waves have also been established analytically. It has been remarkably shown that the law of conservation of energy holds good in the entire reflection and transmission phenomena for different angles of incidence. A numerical examples were performed so to graphically portray the analytical findings. Further the deduced results are validated with the pre-established classical results.

Half-metallic superconducting triplet spin multivalves

NASA Astrophysics Data System (ADS)

Alidoust, Mohammad; Halterman, Klaus

2018-02-01

We study spin switching effects in finite-size superconducting multivalve structures. We examine F1F2SF3 and F1F2SF3F4 hybrids where a singlet superconductor (S) layer is sandwiched among ferromagnet (F) layers with differing thicknesses and magnetization orientations. Our results reveal a considerable number of experimentally viable spin-valve configurations that lead to on-off switching of the superconducting state. For S widths on the order of the superconducting coherence length ξ0, noncollinear magnetization orientations in adjacent F layers with multiple spin axes leads to a rich variety of triplet spin-valve effects. Motivated by recent experiments, we focus on samples where the magnetizations in the F1 and F4 layers exist in a fully spin-polarized half-metallic phase, and calculate the superconducting transition temperature, spatially and energy resolved density of states, and the spin-singlet and spin-triplet superconducting correlations. Our findings demonstrate that superconductivity in these devices can be completely switched on or off over a wide range of magnetization misalignment angles due to the generation of equal-spin and opposite-spin triplet pairings.

High-quality nonpolar a-plane GaN epitaxial films grown on r-plane sapphire substrates by the combination of pulsed laser deposition and metal–organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Yang, Weijia; Zhang, Zichen; Wang, Wenliang; Zheng, Yulin; Wang, Haiyan; Li, Guoqiang

2018-05-01

High-quality a-plane GaN epitaxial films have been grown on r-plane sapphire substrates by the combination of pulsed laser deposition (PLD) and metal–organic chemical vapor deposition (MOCVD). PLD is employed to epitaxial growth of a-plane GaN templates on r-plane sapphire substrates, and then MOCVD is used. The nonpolar a-plane GaN epitaxial films with relatively small thickness (2.9 µm) show high quality, with the full-width at half-maximum values of GaN(11\\bar{2}0) along [1\\bar{1}00] direction and GaN(10\\bar{1}1) of 0.11 and 0.30°, and a root-mean-square surface roughness of 1.7 nm. This result is equivalent to the quality of the films grown by MOCVD with a thickness of 10 µm. This work provides a new and effective approach for achieving high-quality nonpolar a-plane GaN epitaxial films on r-plane sapphire substrates.

Harvesting keratolimbal allografts from corneoscleral buttons: a novel application of cyanoacrylate adhesive.

PubMed

Lim, L T; Bhatt, P R; Ramaesh, K

2008-11-01

To describe an alternative and novel technique using cyanoacrylate glue to achieve successful limbal tissue dissection, from an organ culture media stored corneoscleral button, without an artificial anterior chamber. A donor corneoscleral button (leftover from penetrating keratoplasty) was divided into two equal semicircular halves. A thick layer of tissue adhesive (N-butyl-2-cyanoacrylate) was spread on a sterile rubber block (the under surface of the donor punch). One half of the donor corneoscleral rim was placed epithelial side up on the adhesive and allowed to attach firmly to the block. This composite provided stability to the donor rim allowing lamellar dissection of the limbal tissue to be performed without damaging the limbal epithelium. Regular, partial-thickness limbal tissue was obtained. There was no histological evidence of glue or cellular toxicity of the harvested limbal stem cells. This harvested tissue had been grafted successfully in patients with limbal stem cell deficiency also undergoing keratoplasty. Tissue adhesive can be a simple, effective and useful tool in the dissection and harvesting of corneal limbal stem cell allografts from corneoscleral buttons stored in organ culture media.

Nitric oxide-releasing chitosan film for enhanced antibacterial and in vivo wound-healing efficacy.

PubMed

Kim, Jong Oh; Noh, Jin-Ki; Thapa, Raj Kumar; Hasan, Nurhasni; Choi, Moonjeong; Kim, Jeong Hwan; Lee, Joon-Hee; Ku, Sae Kwang; Yoo, Jin-Wook

2015-08-01

Nitric oxide (NO) is a promising therapeutic agent with antibacterial and wound-healing properties. However, the gaseous state and short half-life of NO necessitate a formulation that can control its storage and release. In this study, we developed NO-releasing films (CS/NO film) composed of chitosan (CS) and S-nitrosoglutathione (GSNO) as a NO donor. Thermal analysis demonstrated molecular dispersion of GSNO in the films. In vitro release study revealed that NO release from CS/NO films followed Korsmeyer-Peppas model with Fickian diffusion kinetics. Moreover, the CS/NO film showed a stronger antibacterial activity against Pseudomonas aeruginosa (Gram-negative) and Staphylococcus aureus (Gram-positive) than the CS film. Further, the CS/NO film accelerated wound healing and epithelialization in a rat model of full-thickness wounds as compared to the CS film. Histopathological studies revealed that CS/NO films favorably enhanced the re-epithelialization and reconstruction of wounded skin. Therefore, our results suggest that CS/NO films could be a suitable formulation for treating full-thickness wounds. Copyright © 2015 Elsevier B.V. All rights reserved.

Terahertz Spectroscopy for Proximal Soil Sensing: An Approach to Particle Size Analysis

PubMed Central

Dworak, Volker; Mahns, Benjamin; Selbeck, Jörn; Weltzien, Cornelia

2017-01-01

Spatially resolved soil parameters are some of the most important pieces of information for precision agriculture. These parameters, especially the particle size distribution (texture), are costly to measure by conventional laboratory methods, and thus, in situ assessment has become the focus of a new discipline called proximal soil sensing. Terahertz (THz) radiation is a promising method for nondestructive in situ measurements. The THz frequency range from 258 gigahertz (GHz) to 350 GHz provides a good compromise between soil penetration and the interaction of the electromagnetic waves with soil compounds. In particular, soil physical parameters influence THz measurements. This paper presents investigations of the spectral transmission signals from samples of different particle size fractions relevant for soil characterization. The sample thickness ranged from 5 to 17 mm. The transmission of THz waves was affected by the main mineral particle fractions, sand, silt and clay. The resulting signal changes systematically according to particle sizes larger than half the wavelength. It can be concluded that THz spectroscopic measurements provide information about soil texture and penetrate samples with thicknesses in the cm range. PMID:29048392

Adjustable bipod flexures for mounting mirrors in a space telescope.

PubMed

Kihm, Hagyong; Yang, Ho-Soon; Moon, Il Kweon; Yeon, Jeong-Heum; Lee, Seung-Hoon; Lee, Yun-Woo

2012-11-10

A new mirror mounting technique applicable to the primary mirror in a space telescope is presented. This mounting technique replaces conventional bipod flexures with flexures having mechanical shims so that adjustments can be made to counter the effects of gravitational distortion of the mirror surface while being tested in the horizontal position. Astigmatic aberration due to the gravitational changes is effectively reduced by adjusting the shim thickness, and the relation between the astigmatism and the shim thickness is investigated. We tested the mirror interferometrically at the center of curvature using a null lens. Then we repeated the test after rotating the mirror about its optical axis by 180° in the horizontal setup, and searched for the minimum system error. With the proposed flexure mount, the gravitational stress at the adhesive coupling between the mirror and the mount is reduced by half that of a conventional bipod flexure for better mechanical safety under launch loads. Analytical results using finite element methods are compared with experimental results from the optical interferometer. Vibration tests verified the mechanical safety and optical stability, and qualified their use in space applications.

Radiation transmission data for radionuclides and materials relevant to brachytherapy facility shielding.

PubMed

Papagiannis, P; Baltas, D; Granero, D; Pérez-Calatayud, J; Gimeno, J; Ballester, F; Venselaar, J L M

2008-11-01

To address the limited availability of radiation shielding data for brachytherapy as well as some disparity in existing data, Monte Carlo simulation was used to generate radiation transmission data for 60Co, 137CS, 198Au, 192Ir 169Yb, 170Tm, 131Cs, 125I, and 103pd photons through concrete, stainless steel, lead, as well as lead glass and baryte concrete. Results accounting for the oblique incidence of radiation to the barrier, spectral variation with barrier thickness, and broad beam conditions in a realistic geometry are compared to corresponding data in the literature in terms of the half value layer (HVL) and tenth value layer (TVL) indices. It is also shown that radiation shielding calculations using HVL or TVL values could overestimate or underestimate the barrier thickness required to achieve a certain reduction in radiation transmission. This questions the use of HVL or TVL indices instead of the actual transmission data. Therefore, a three-parameter model is fitted to results of this work to facilitate accurate and simple radiation shielding calculations.

N-polar InGaN-based LEDs fabricated on sapphire via pulsed sputtering

NASA Astrophysics Data System (ADS)

Ueno, Kohei; Kishikawa, Eiji; Ohta, Jitsuo; Fujioka, Hiroshi

2017-02-01

High-quality N-polar GaN epitaxial films with an atomically flat surface were grown on sapphire (0001) via pulsed sputtering deposition, and their structural and electrical properties were investigated. The crystalline quality of N-polar GaN improves with increasing film thickness and the full width at half maximum values of the x-ray rocking curves for 0002 and 101 ¯ 2 diffraction were 313 and 394 arcsec, respectively, at the film thickness of 6 μ m . Repeatable p-type doping in N-polar GaN films was achieved using Mg dopant, and their hole concentration and mobility can be controlled in the range of 8 × 1016-2 × 1018 cm-3 and 2-9 cm2V-1s-1, respectively. The activation energy of Mg in N-polar GaN based on a temperature-dependent Hall measurement was estimated to be 161 meV, which is comparable to that of the Ga-polar GaN. Based on these results, we demonstrated the fabrication of N-polar InGaN-based light emitting diodes with the long wavelength up to 609 nm.

A mechanism for magnetospheric substorms

NASA Technical Reports Server (NTRS)

Erickson, G. M.; Heinemann, M.

1994-01-01

Energy-principle analysis performed on two-dimensional, self-consistent solutions for magnetospheric convection indicates that the magnetosphere is unstable to isobaric (yet still frozen-in) fluctuations of plasma-sheet flux tubes. Normally, pdV work associated with compression maintains stability of the inward/outward oscillating normal mode. However, if Earth's ionosphere can provide sufficient mass flux, isobaric expansion of flux tubes can occur. The growth of a field-aligned potential drop in the near-Earth, midnight portion of the plasma sheet, associated with upward field-aligned currents responsible for the Harang discontinuity, redistributes plasma along field lines in a manner that destabilizes the normal mode. The growth of this unstable mode results in an out-of-equilibrium situation near the inner edge. When this occurs over a downtail extent comparable to the half-thickness of the plasma sheet, collapse ensues and forces thinning of the plasma sheet whereby conditions favorable to reconnection occur. This scenario for substorm onset is consistent with observed upward fluxes of ions, parallel potential drops, and observations of substorm onset. These observations include near Earth onset, pseudobreakups, the substorm current wedge, and local variations of plasma-sheet thickness.

Slice-thickness evaluation in CT and MRI: an alternative computerised procedure.

PubMed

Acri, G; Tripepi, M G; Causa, F; Testagrossa, B; Novario, R; Vermiglio, G

2012-04-01

The efficient use of computed tomography (CT) and magnetic resonance imaging (MRI) equipment necessitates establishing adequate quality-control (QC) procedures. In particular, the accuracy of slice thickness (ST) requires scan exploration of phantoms containing test objects (plane, cone or spiral). To simplify such procedures, a novel phantom and a computerised LabView-based procedure have been devised, enabling determination of full width at half maximum (FWHM) in real time. The phantom consists of a polymethyl methacrylate (PMMA) box, diagonally crossed by a PMMA septum dividing the box into two sections. The phantom images were acquired and processed using the LabView-based procedure. The LabView (LV) results were compared with those obtained by processing the same phantom images with commercial software, and the Fisher exact test (F test) was conducted on the resulting data sets to validate the proposed methodology. In all cases, there was no statistically significant variation between the two different procedures and the LV procedure, which can therefore be proposed as a valuable alternative to other commonly used procedures and be reliably used on any CT and MRI scanner.

700 F hybrid capacitors cells composed of activated carbon and Li4Ti5O12 microspheres with ultra-long cycle life

NASA Astrophysics Data System (ADS)

Ruan, Dianbo; Kim, Myeong-Seong; Yang, Bin; Qin, Jun; Kim, Kwang-Bum; Lee, Sang-Hyun; Liu, Qiuxiang; Tan, Lei; Qiao, Zhijun

2017-10-01

To address the large-scale application demands of high energy density, high power density, and long cycle lifetime, 700-F hybrid capacitor pouch cells have been prepared, comprising ∼240-μm-thick activated carbon cathodes, and ∼60-μm-thick Li4Ti5O12 anodes. Microspherical Li4Ti5O12 (M-LTO) synthesized by spray-drying features 200-400 nm primary particles and interconnected nanopore structures. M-LTO half-cells exhibits high specific capacities (175 mAhh g-1), good rate capabilities (148 mAhh g-1 at 20 C), and ultra-long cycling stabilities (90% specific capacity retention after 10,000 cycles). In addition, the obtained hybrid capacitors comprising activated carbon (AC) and M-LTO shows excellent cell performances, achieving a maximum energy density of 51.65 Wh kg-1, a maximum power density of 2466 W kg-1, and ∼92% capacitance retention after 10,000 cycles, thus meeting the demands for large-scale applications such as trolleybuses.

Growth of High-Quality GaAs on Ge by Controlling the Thickness and Growth Temperature of Buffer Layer

NASA Astrophysics Data System (ADS)

Zhou, Xu-Liang; Pan, Jiao-Qing; Yu, Hong-Yan; Li, Shi-Yan; Wang, Bao-Jun; Bian, Jing; Wang, Wei

2014-12-01

High-quality GaAs thin films grown on miscut Ge substrates are crucial for GaAs-based devices on silicon. We investigate the effect of different thicknesses and temperatures of GaAs buffer layers on the crystal quality and surface morphology of GaAs on Ge by metal-organic chemical vapor deposition. Through high resolution x-ray diffraction measurements, it is demonstrated that the full width at half maximum for the GaAs epilayer (Ge substrate) peak could achieve 19.3 (11.0) arcsec. The value of etch pit density could be 4×104 cm-2. At the same time, GaAs surfaces with no pyramid-shaped pits are obtained when the buffer layer growth temperature is lower than 360°C, due to effective inhibition of initial nucleation at terraces of the Ge surface. In addition, it is shown that large island formation at the initial stage of epitaxial growth is a significant factor for the final rough surface and that this initial stage should be carefully controlled when a device quality GaAs surface is desired.

Time scales of radiation damage decay in four optical materials

NASA Astrophysics Data System (ADS)

Grupp, Frank; Geis, Norbert; Katterloher, Reinhard; Bender, Ralf

2017-09-01

In the framework of the qualification campaigns for the near infrared spectrometer and photometer instrument (NISP) on board the ESA/EUCLID satellite six optical materials where characterized with respect to their transmission losses after a radiation dose representing the mission exposure to high energy particles in the outer Lagrange point L2. Data was taken between 500 and 2000nm on six 25mm thick coated probes. Thickness and coating being representative for the NISP flight configuration. With this paper we present results owing up the radiation damage shown in [1]. We where able to follow up the decay of the radiation damage over almost one year under ambient conditions. This allows us to distinguish between curing effects that happen on different time-scales. As for some of the materials no radiation damage and thus no curing was detected, all materials that showed significant radiation damage in the measured passband showed two clearly distinguished time scales of curing. Up to 70% of the transmission losses cured on half decay time scales of several tens of days, while the rest of the damage cures on time scales of years.

Membrane catalyst layer for fuel cells

DOEpatents

Wilson, Mahlon S.

1993-01-01

A gas reaction fuel cell incorporates a thin catalyst layer between a solid polymer electrolyte (SPE) membrane and a porous electrode backing. The catalyst layer is preferably less than about 10 .mu.m in thickness with a carbon supported platinum catalyst loading less than about 0.35 mgPt/cm.sup.2. The film is formed as an ink that is spread and cured on a film release blank. The cured film is then transferred to the SPE membrane and hot pressed into the surface to form a catalyst layer having a controlled thickness and catalyst distribution. Alternatively, the catalyst layer is formed by applying a Na.sup.+ form of a perfluorosulfonate ionomer directly to the membrane, drying the film at a high temperature, and then converting the film back to the protonated form of the ionomer. The layer has adequate gas permeability so that cell performance is not affected and has a density and particle distribution effective to optimize proton access to the catalyst and electronic continuity for electron flow from the half-cell reaction occurring at the catalyst.

Hohlraum design for the LMJ ignition target

NASA Astrophysics Data System (ADS)

Malinie, G.; Cherfils, C.; Gauthier, P.; Lambert, F.; Monteil, M. C.

2011-10-01

First experiments with the Laser MegaJoule (LMJ) are scheduled to be performed in 2014. The current nominal point design for ignition with 160 beams on the LMJ has been described in. It consists of an indirectly driven A943 capsule, with a plastic ablator doped with Germanium. This capsule is mounted in the center of a Rugby-shaped hohlraum, which is filled with a low density H/He gas, and has a gold-uranium cocktail wall lined with pure gold. We investigate the influence of two key parameters of the hohlraum design: the radius of the laser entrance holes (LEHs), and the thickness of the cocktail layer. Since the Rugby shape of the nominal point design is that of a half-ellipse going from the hohlraum waist to the LEH, any change in the LEH radius has a global effect on the hohlraum shape. Taking into account the current laser spot profiles of the LMJ and using 2D integrated calculations with our FCI2 radiation hydrodynamics code, we assess the flexiblility we have to reduce the LEH radius and/or the cocktail layer thickness.

Characterisation of a MeV Bremsstrahlung x-ray source produced from a high intensity laser for high areal density object radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Courtois, C.; Compant La Fontaine, A.; Bazzoli, S.

2013-08-15

Results of an experiment to characterise a MeV Bremsstrahlung x-ray emission created by a short (<10 ps) pulse, high intensity (1.4 × 10{sup 19} W/cm{sup 2}) laser are presented. X-ray emission is characterized using several diagnostics; nuclear activation measurements, a calibrated hard x-ray spectrometer, and dosimeters. Results from the reconstructed x-ray energy spectra are consistent with numerical simulations using the PIC and Monte Carlo codes between 0.3 and 30 MeV. The intense Bremsstrahlung x-ray source is used to radiograph an image quality indicator (IQI) heavily filtered with thick tungsten absorbers. Observations suggest that internal features of the IQI can bemore » resolved up to an external areal density of 85 g/cm{sup 2}. The x-ray source size, inferred by the radiography of a thick resolution grid, is estimated to be approximately 400 μm (full width half maximum of the x-ray source Point Spread Function)« less

CT reconstruction techniques for improved accuracy of lung CT airway measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, A.; Ranallo, F. N.; Judy, P. F.

Purpose: To determine the impact of constrained reconstruction techniques on quantitative CT (qCT) of the lung parenchyma and airways for low x-ray radiation dose. Methods: Measurement of small airways with qCT remains a challenge, especially for low x-ray dose protocols. Images of the COPDGene quality assurance phantom (CTP698, The Phantom Laboratory, Salem, NY) were obtained using a GE discovery CT750 HD scanner for helical scans at x-ray radiation dose-equivalents ranging from 1 to 4.12 mSv (12–100 mA s current–time product). Other parameters were 40 mm collimation, 0.984 pitch, 0.5 s rotation, and 0.625 mm thickness. The phantom was sandwiched betweenmore » 7.5 cm thick water attenuating phantoms for a total length of 20 cm to better simulate the scatter conditions of patient scans. Image data sets were reconstructed using STANDARD (STD), DETAIL, BONE, and EDGE algorithms for filtered back projection (FBP), 100% adaptive statistical iterative reconstruction (ASIR), and Veo reconstructions. Reduced (half) display field of view (DFOV) was used to increase sampling across airway phantom structures. Inner diameter (ID), wall area percent (WA%), and wall thickness (WT) measurements of eight airway mimicking tubes in the phantom, including a 2.5 mm ID (42.6 WA%, 0.4 mm WT), 3 mm ID (49.0 WA%, 0.6 mm WT), and 6 mm ID (49.0 WA%, 1.2 mm WT) were performed with Airway Inspector (Surgical Planning Laboratory, Brigham and Women’s Hospital, Boston, MA) using the phase congruency edge detection method. The average of individual measures at five central slices of the phantom was taken to reduce measurement error. Results: WA% measures were greatly overestimated while IDs were underestimated for the smaller airways, especially for reconstructions at full DFOV (36 cm) using the STD kernel, due to poor sampling and spatial resolution (0.7 mm pixel size). Despite low radiation dose, the ID of the 6 mm ID airway was consistently measured accurately for all methods other than STD FBP. Veo reconstructions showed slight improvement over STD FBP reconstructions (4%–9% increase in accuracy). The most improved ID and WA% measures were for the smaller airways, especially for low dose scans reconstructed at half DFOV (18 cm) with the EDGE algorithm in combination with 100% ASIR to mitigate noise. Using the BONE + ASIR at half BONE technique, measures improved by a factor of 2 over STD FBP even at a quarter of the x-ray dose. Conclusions: The flexibility of ASIR in combination with higher frequency algorithms, such as BONE, provided the greatest accuracy for conventional and low x-ray dose relative to FBP. Veo provided more modest improvement in qCT measures, likely due to its compatibility only with the smoother STD kernel.« less

Minimum number of myosin motors accounting for shortening velocity under zero load in skeletal muscle.

PubMed

Fusi, Luca; Percario, Valentina; Brunello, Elisabetta; Caremani, Marco; Bianco, Pasquale; Powers, Joseph D; Reconditi, Massimo; Lombardi, Vincenzo; Piazzesi, Gabriella

2017-02-15

Myosin filament mechanosensing determines the efficiency of the contraction by adapting the number of switched ON motors to the load. Accordingly, the unloaded shortening velocity (V 0 ) is already set at the end of latency relaxation (LR), ∼10 ms after the start of stimulation, when the myosin filament is still in the OFF state. Here the number of actin-attached motors per half-myosin filament (n) during V 0 shortening imposed either at the end of LR or at the plateau of the isometric contraction is estimated from the relation between half-sarcomere compliance and force during the force redevelopment after shortening. The value of n decreases progressively with shortening and, during V 0 shortening starting at the end of LR, is 1-4. Reduction of n is accounted for by a constant duty ratio of 0.05 and a parallel switching OFF of motors, explaining the very low rate of ATP utilization found during unloaded shortening. The maximum velocity at which a skeletal muscle can shorten (i.e. the velocity of sliding between the myosin filament and the actin filament under zero load, V 0 ) is already set at the end of the latency relaxation (LR) preceding isometric force generation, ∼10 ms after the start of electrical stimulation in frog muscle fibres at 4°C. At this time, Ca 2+ -induced activation of the actin filament is maximal, while the myosin filament is in the OFF state characterized by most of the myosin motors lying on helical tracks on the filament surface, making them unavailable for actin binding and ATP hydrolysis. Here, the number of actin-attached motors per half-thick filament during V 0 shortening (n) is estimated by imposing, on tetanized single fibres from Rana esculenta (at 4°C and sarcomere length 2.15 μm), small 4 kHz oscillations and determining the relation between half-sarcomere (hs) compliance and force during the force development following V 0 shortening. When V 0 shortening is superimposed on the maximum isometric force T 0 , n decreases progressively with the increase of shortening (range 30-80 nm per hs) and, when V 0 shortening is imposed at the end of LR, n can be as low as 1-4. Reduction of n is accounted for by a constant duty ratio of the myosin motor of ∼0.05 and a parallel switching OFF of the thick filament, providing an explanation for the very low rate of ATP utilization during extended V 0 shortening. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie

Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into halfmore » of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC (AFROC) area decreased from 0.84 to 0.63 and the ROC area decreased from 0.91 to 0.79 (p < 0.0001). This corresponded to a 30% drop in lesion sensitivity at a NLF equal to 0.1. Detection was also sensitive to the dose used. There was no significant difference in detection between the two image processing algorithms used (p > 0.05). It was additionally found that lower threshold gold thickness from CDMAM analysis implied better cluster detection. The measured threshold gold thickness passed the acceptable limit set in the EU standards for all image qualities except half dose CR. However, calcification detection varied significantly between image qualities. This suggests that the current EU guidelines may need revising. Conclusions: Microcalcification detection was found to be sensitive to detector and dose used. Standard measurements of image quality were a good predictor of microcalcification cluster detection.« less

New perspectives on the geometry of the Albuquerque Basin, Rio Grande rift, New Mexico: Insights from geophysical models of rift-fill thickness

USGS Publications Warehouse

Grauch, V. J.; Connell, Sean D.

2013-01-01

Discrepancies among previous models of the geometry of the Albuquerque Basin motivated us to develop a new model using a comprehensive approach. Capitalizing on a natural separation between the densities of mainly Neogene basin fill (Santa Fe Group) and those of older rocks, we developed a three-dimensional (3D) geophysical model of syn-rift basin-fill thickness that incorporates well data, seismic-reflection data, geologic cross sections, and other geophysical data in a constrained gravity inversion. Although the resulting model does not show structures directly, it elucidates important aspects of basin geometry. The main features are three, 3–5-km-deep, interconnected structural depressions, which increase in size, complexity, and segmentation from north to south: the Santo Domingo, Calabacillas, and Belen subbasins. The increase in segmentation and complexity may reflect a transition of the Rio Grande rift from well-defined structural depressions in the north to multiple, segmented basins within a broader region of crustal extension to the south. The modeled geometry of the subbasins and their connections differs from a widely accepted structural model based primarily on seismic-reflection interpretations. Key elements of the previous model are an east-tilted half-graben block on the north separated from a west-tilted half-graben block on the south by a southwest-trending, scissor-like transfer zone. Instead, we find multiple subbasins with predominantly easterly tilts for much of the Albuquerque Basin, a restricted region of westward tilting in the southwestern part of the basin, and a northwesterly trending antiform dividing subbasins in the center of the basin instead of a major scissor-like transfer zone. The overall eastward tilt indicated by the 3D geophysical model generally conforms to stratal tilts observed for the syn-rift succession, implying a prolonged eastward tilting of the basin during Miocene time. An extensive north-south synform in the central part of the Belen subbasin suggests a possible path for the ancestral Rio Grande during late Miocene or early Pliocene time. Variations in rift-fill thickness correspond to pre-rift structures in several places, suggesting that a better understanding of pre-rift history may shed light on debates about structural inheritance within the rift.

3D Model of the Tuscarora Geothermal Area

DOE Data Explorer

Faulds, James E.

2013-12-31

The Tuscarora geothermal system sits within a ~15 km wide left-step in a major west-dipping range-bounding normal fault system. The step over is defined by the Independence Mountains fault zone and the Bull Runs Mountains fault zone which overlap along strike. Strain is transferred between these major fault segments via and array of northerly striking normal faults with offsets of 10s to 100s of meters and strike lengths of less than 5 km. These faults within the step over are one to two orders of magnitude smaller than the range-bounding fault zones between which they reside. Faults within the broad step define an anticlinal accommodation zone wherein east-dipping faults mainly occupy western half of the accommodation zone and west-dipping faults lie in the eastern half of the accommodation zone. The 3D model of Tuscarora encompasses 70 small-offset normal faults that define the accommodation zone and a portion of the Independence Mountains fault zone, which dips beneath the geothermal field. The geothermal system resides in the axial part of the accommodation, straddling the two fault dip domains. The Tuscarora 3D geologic model consists of 10 stratigraphic units. Unconsolidated Quaternary alluvium has eroded down into bedrock units, the youngest and stratigraphically highest bedrock units are middle Miocene rhyolite and dacite flows regionally correlated with the Jarbidge Rhyolite and modeled with uniform cumulative thickness of ~350 m. Underlying these lava flows are Eocene volcanic rocks of the Big Cottonwood Canyon caldera. These units are modeled as intracaldera deposits, including domes, flows, and thick ash deposits that change in thickness and locally pinch out. The Paleozoic basement of consists metasedimenary and metavolcanic rocks, dominated by argillite, siltstone, limestone, quartzite, and metabasalt of the Schoonover and Snow Canyon Formations. Paleozoic formations are lumped in a single basement unit in the model. Fault blocks in the eastern portion of the model are tilted 5-30 degrees toward the Independence Mountains fault zone. Fault blocks in the western portion of the model are tilted toward steeply east-dipping normal faults. These opposing fault block dips define a shallow extensional anticline. Geothermal production is from 4 closely-spaced wells, that exploit a west-dipping, NNE-striking fault zone near the axial part of the accommodation zone.

The Roles of the Yellowstone Hotspot and Crustal Assimilation in Generating Pleistocene-Holocene Basalts on the Eastern Snake River Plain

NASA Astrophysics Data System (ADS)

Mintz, H.; Chadwick, J.

2017-12-01

The southwest motion of the North American plate across the Yellowstone hotspot created a chain of age-progressive rhyolitic calderas over the past 16 myr. in southern Idaho, U.S. The focus of Yellowstone activity now resides in northwest Wyoming, but basaltic volcanism has continued in its wake in southern Idaho on the eastern Snake River Plain (ESRP). These younger basaltic lavas are not age progressive and have buried the Yellowstone rhyolites on the ESRP. The ultimate source of the basalts is commonly ascribed to the passage or presence of the hotspot. However, the mechanisms involved, and the relative roles of the hotspot, other mantle sources, and the North American crust in generating the ESRP basalts remain unclear and have been the subject of recent geochemical and isotopic studies. In this study, the role of crustal assimilation is addressed by analyzing the chemical and isotopic characteristics of some of the youngest Pleistocene-Holocene tholeiitic volcanic fields on the ESRP, which were erupted through varying thicknesses of continental crust. Samples were analyzed from the Hell's Half Acre flow (5,200 years old; all dates Kuntz et al., 1986, 1994), Cerro Grande flow (13,380 years), and Black Butte Crater (a.k.a. Shoshone) flow (10,130 years), which were erupted at distances from between about 200 to 300 km from the current location of the hotspot. The crust of the ESRP thins from northeast to southwest, from about 47 km at the Hells Half Acre flow to 40 km at the Black Butte Crater flow, a thickness difference of about 15%. The apparently similar tectonic and magmatic environments of the three sampled flows suggest the crustal thickness variation may be a primary influence on the magnitude of assimilation and therefore the isotopic characteristics of the lavas. The goal of this work is to constrain the relative role of assimilation and to understand the source(s) of the magmas and the Yellowstone hotspot contribution. Major elements, trace elements, and Pb-Sr-Nd isotopic data for the flows and crustal xenoliths, in conjunction with mixing modeling with MELTS software, constrain potential differences in fractional crystallization, residence times in the crust, and crustal assimilation for the flows.

Effect of bio-column composed of aged refuse on methane abatement--a novel configuration of biological oxidation in refuse landfill.

PubMed

Han, Dan; Zhao, Youcai; Xue, Binjie; Chai, Xiaoli

2010-01-01

An experimental bio-column composed of aged refuse was installed around the exhaust pipe as a new way to mitigate methane in refuse landfill. One of the objectives of this work was to assess the effect of aged refuse thickness in bio-column on reducing CH4 emissions. Over the study period, methane oxidation was observed at various thicknesses, 5 cm (small size), 10 cm (middle size) and 15 cm (large size), representing one to three times of pipeline diameters. The middle and large size both showed over 90% methane conversion, and the highest methane conversion rate of above 95% occurred in the middle-size column cell. Michaelis-Menten equation addressed the methanotrophs diffusion in different layers of the bio-columns. Maximum methanotrophic activity (Vmax) measured at the three thicknesses ranged from 6.4 x 10(-3) to 15.6 x 10(-3) units, and the half-saturation value (K(M)) ranged from 0.85% to 1.67%. Both the highest Vmax and K(M) were observed at the middle-size of the bio-column, as well as the largest methanotrophs population, suggesting a significant efficiency of methane mitigation happened in the optimum zone with greatest affinity and methanotrophic bacteria activities. Therefore, bio-column is a potential style for methane abatement in landfill, and the aged refuse both naturally formed and artificially placed in the column plays a critical role in CH4 emission.

Design Study of Wafer Seals for Future Hypersonic Vehicles

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H.; Finkbeiner, Joshua R.; Steinetz, Bruce M.; DeMange, Jeffrey J.

2005-01-01

Future hypersonic vehicles require high temperature, dynamic seals in advanced hypersonic engines and on the vehicle airframe to seal the perimeters of movable panels, flaps, and doors. Current seals do not meet the demanding requirements of these applications, so NASA Glenn Research Center is developing improved designs to overcome these shortfalls. An advanced ceramic wafer seal design has shown promise in meeting these needs. Results from a design of experiments study performed on this seal revealed that several installation variables played a role in determining the amount of leakage past the seals. Lower leakage rates were achieved by using a tighter groove width around the seals, a higher seal preload, a tighter wafer height tolerance, and a looser groove length. During flow testing, a seal activating pressure acting behind the wafers combined with simulated vibrations to seat the seals more effectively against the sealing surface and produce lower leakage rates. A seal geometry study revealed comparable leakage for full-scale wafers with 0.125 and 0.25 in. thicknesses. For applications in which lower part counts are desired, fewer 0.25-in.-thick wafers may be able to be used in place of 0.125-in.-thick wafers while achieving similar performance. Tests performed on wafers with a rounded edge (0.5 in. radius) in contact with the sealing surface resulted in flow rates twice as high as those for wafers with a flat edge. Half-size wafers had leakage rates approximately three times higher than those for full-size wafers.

Strain relaxation in the epitaxy of La2/3Sr1/3MnO3 grown by pulsed-laser deposition on SrTiO3(001)

NASA Astrophysics Data System (ADS)

Maurice, J.-L.; Pailloux, F.; Barthélémy, A.; Durand, O.; Imhoff, D.; Lyonnet, R.; Rocher, A.; Contour, J.-P.

2003-10-01

With a Curie point at 370 K, the half-metal (La0.7Sr0.3)MnO3 (LSMO) is one of the most interesting candidates for electronic devices based on tunnel magnetoresistance. SrTiO3 (STO) is up to now the best substrate for the epitaxy of suitable thin films of LSMO. The pseudocubic unit cell of rhombohedral LSMO has a parameter aLSMO such that (aSTO m aLSMO)/aLSMO = + 0.83% (where aSTO is the parameter of cubic STO) and an angle of 90.26°. As strained growth is tetragonal, relaxation implies recovery of both the pseudocubic parameter and of the original angle. In the LSMO layers that we prepare by pulsed-laser deposition, we show that these two processes are quite independent. The angular distortion is partially recovered by twinning in films 25 nm thick, while recovery of the parameter never occurs in the thickness range that we explored (up to 432 nm). A relaxation, however, takes place above a thickness of 100 nm, associated with a transition from two-dimensional to three-dimensional columnar growth. It is accompanied by chemical fluctuations. Our magnetic measurements exhibit Curie temperatures and magnetic moments very close to the bulk values in those layers where the crystal parameter is strained but the angle partially relaxed.