Vertically aligned carbon nanopillars with size and spacing control for a transparent field emission display.

PubMed

Lee, Seok Woo; Lee, Chang Hwa; Lee, Jung A; Lee, Seung S

2013-01-18

A top-down fabrication method is presented for vertically aligned carbon nanopillars (CNPs) using photolithography and pyrolysis. The modified backside exposure method of photolithography fabricates vertically aligned polymer (SU-8) nanopillars. The pyrolysis process, which transforms the polymer to amorphous carbon, reliably produces vertically aligned CNPs with widths ranging from 100 to 400 nm. The CNPs can be used as a transparent field emission cathode for a transparent display and light emission is observed.

High yield growth of patterned vertically aligned carbon nanotubes using inkjet-printed catalyst.

PubMed

Beard, James D; Stringer, Jonathan; Ghita, Oana R; Smith, Patrick J

2013-10-09

This study reports on the fabrication of vertically aligned carbon nanotubes localized at specific sites on a growth substrate by deposition of a nanoparticle suspension using inkjet printing. Carbon nanotubes were grown with high yield as vertically aligned forests to a length of approximately 400 μm. The use of inkjet printing for catalyst fabrication considerably improves the production rate of vertically aligned patterned nanotube forests compared with conventional patterning techniques, for example, electron beam lithography or photolithography.

Bayesian Markov Chain Monte Carlo inversion for weak anisotropy parameters and fracture weaknesses using azimuthal elastic impedance

NASA Astrophysics Data System (ADS)

Chen, Huaizhen; Pan, Xinpeng; Ji, Yuxin; Zhang, Guangzhi

2017-08-01

A system of aligned vertical fractures and fine horizontal shale layers combine to form equivalent orthorhombic media. Weak anisotropy parameters and fracture weaknesses play an important role in the description of orthorhombic anisotropy (OA). We propose a novel approach of utilizing seismic reflection amplitudes to estimate weak anisotropy parameters and fracture weaknesses from observed seismic data, based on azimuthal elastic impedance (EI). We first propose perturbation in stiffness matrix in terms of weak anisotropy parameters and fracture weaknesses, and using the perturbation and scattering function, we derive PP-wave reflection coefficient and azimuthal EI for the case of an interface separating two OA media. Then we demonstrate an approach to first use a model constrained damped least-squares algorithm to estimate azimuthal EI from partially incidence-phase-angle-stack seismic reflection data at different azimuths, and then extract weak anisotropy parameters and fracture weaknesses from the estimated azimuthal EI using a Bayesian Markov Chain Monte Carlo inversion method. In addition, a new procedure to construct rock physics effective model is presented to estimate weak anisotropy parameters and fracture weaknesses from well log interpretation results (minerals and their volumes, porosity, saturation, fracture density, etc.). Tests on synthetic and real data indicate that unknown parameters including elastic properties (P- and S-wave impedances and density), weak anisotropy parameters and fracture weaknesses can be estimated stably in the case of seismic data containing a moderate noise, and our approach can make a reasonable estimation of anisotropy in a fractured shale reservoir.

kISMET: Stress and fracture characterization in a deep mine

NASA Astrophysics Data System (ADS)

Oldenburg, C. M.; Dobson, P. F.; Daley, T. M.; Birkholzer, J. T.; Cook, P. J.; Ajo Franklin, J. B.; Rutqvist, J.; Siler, D.; Kneafsey, T. J.; Nakagawa, S.; Wu, Y.; Guglielmi, Y.; Ulrich, C.; Marchesini, P.; Wang, H. F.; Haimson, B. C.; Sone, H.; Vigilante, P.; Roggenthen, W.; Doe, T.; Lee, M.; Mattson, E.; Huang, H.; Johnson, T. C.; Morris, J.; White, J. A.; Johnson, P. A.; Coblentz, D. D.; Heise, J.

2016-12-01

We are developing a community facility called kISMET (permeability (k) and Induced Seismicity Management for Energy Technologies) at the Sanford Underground Research Facility (SURF) in Lead, SD. The purpose of kISMET is to investigate stress and the effects of rock fabric on hydraulic fracturing. Although findings from kISMET may have broad applications that inform stress and fracturing in anisotropic rock, results will be most applicable to improving control of hydraulic fracturing for enhanced geothermal systems (EGS) in crystalline rock. At the kISMET site on the 4850 ft (1480 m depth) level of SURF, we have drilled and cored an array of nearly vertical boreholes in Precambrian phyllite. The array consists of four 50-m deep monitoring boreholes surrounding one 100-m deep borehole forming a 6 m-wide five-spot pattern at a depth of 1530 m. Previous investigations of the stress field at SURF suggest that the principal stress s1 is nearly vertical. By aligning the kISMET boreholes approximately with σ1, fractures created in the center borehole should in theory be perpendicular to σ3, the least principal horizontal stress. But the phyllite at kISMET has a strong fabric (foliation) that could influence fracturing. Stress measurements and stimulation using hydraulic fracturing will be carried out in the center borehole using a straddle packer and high-pressure pump. We will use an impression packer and image logs after stress testing and stimulation to determine fracture orientation and extent at the center borehole. In order to study the control of stress, rock fabric, and stimulation approach on size, aperture, and orientation of hydraulic fractures, we will carefully monitor the stress measurements and stimulation. For example, we will use continuous active source seismic (CASSM) in two of the monitoring boreholes to measure changes in seismic-wave velocity as water fills the fracture. Second, near real-time electrical resistance tomography (ERT) will be used in the other two boreholes to monitor the changes in resistivity during stress measurement and stimulation. Finally, accelerometers placed nearby on the 4850 level will monitor induced microseismicity. Results of pre-test fracturing simulations, laboratory tests on core, stress testing, and stimulation and associated monitoring will be presented.

Water saturation effects on elastic wave attenuation in porous rocks with aligned fractures

NASA Astrophysics Data System (ADS)

Amalokwu, Kelvin; Best, Angus I.; Sothcott, Jeremy; Chapman, Mark; Minshull, Tim; Li, Xiang-Yang

2014-05-01

Elastic wave attenuation anisotropy in porous rocks with aligned fractures is of interest to seismic remote sensing of the Earth's structure and to hydrocarbon reservoir characterization in particular. We investigated the effect of partial water saturation on attenuation in fractured rocks in the laboratory by conducting ultrasonic pulse-echo measurements on synthetic, silica-cemented, sandstones with aligned penny-shaped voids (fracture density of 0.0298 ± 0.0077), chosen to simulate the effect of natural fractures in the Earth according to theoretical models. Our results show, for the first time, contrasting variations in the attenuation (Q-1) of P and S waves with water saturation in samples with and without fractures. The observed Qs/Qp ratios are indicative of saturation state and the presence or absence of fractures, offering an important new possibility for remote fluid detection and characterization.

The Effect of fluid buoyancy and fracture orientation on CaCO3 Formation in a Fracture

NASA Astrophysics Data System (ADS)

Xu, Z.; Li, Q.; Sheets, J.; Kneafsey, T. J.; Jun, Y. S.; Cole, D. R.; Pyrak-Nolte, L. J.

2016-12-01

Sealing fractures through mineral precipitation is a potential way for improving caprock integrity in subsurface reservoirs. We investigated the effect of buoyancy and fracture orientation on the amount and spatial distribution of calcium carbonate (CaCO3) precipitates in a fracture. To monitor mineral precipitation during reactive flow, transparent acrylic casts of an induced fracture in Austin chalk were used. To trigger CaCO3 precipitates, 1M CaCl2 with either 0.6M NaHCO3 solution (for surface adhering precipitation), or 0.3M Na2CO3 solution (for pore filling precipitation) were injected simultaneously into a saturated fracture. Experiments were performed with the fracture plane oriented either parallel or perpendicular to gravity. Acoustic wave transmission (compressional wave, 1 MHz) and optical imaging were used to monitor the sample prior to, during and after fluid injection. Complementary X-ray computed tomography was performed throughout the experiments on vertical fractures and post injection for the horizontal fractures. For the vertical fractures, the denser CaCl2 almost completely displaced the carbonate solution in the fracture and caused strong localization of the precipitates. The width of the precipitated region grew slowly over time. The horizontal fracture caused the less dense carbonate to flow over the CaCl2 solution thus resulting in more mixing and a more even distribution of precipitates throughout the fracture. The acoustic signatures depended on the type of precipitation that occurred. For pore filling experiments, the compressional wave amplitude increased by 5-20% and the velocity increased for both the vertical and horizontal fractures. However, the acoustic responses differed between the vertical and horizontal fractures for surface adhering experiments. Based on the acoustic response, surface adhering precipitation increased fracture specific stiffness more in the horizontal fracture than in the vertical fracture. The horizontal fracture enabled more mixing of the two solutions within the fracture than the vertical fracture. This work was supported by the Center for Nanoscale Controls on Geologic CO (NCGC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-AC02-05CH11231

Fabrication of high thermal conductivity arrays of carbon nanotubes and their composites

DOEpatents

Geohegan, David B [Knoxville, TN; Ivanov, Ilya N [Knoxville, TN; Puretzky, Alexander A [Knoxville, TN

2010-07-27

Methods and apparatus are described for fabrication of high thermal conductivity arrays of carbon nanotubes and their composites. A composition includes a vertically aligned nanotube array including a plurality of nanotubes characterized by a property across substantially all of the vertically aligned nanotube array. A method includes depositing a vertically aligned nanotube array that includes a plurality of nanotubes; and controlling a deposition rate of the vertically aligned nanotubes array as a function of an in situ monitored property of the plurality of nanotubes.

Fast Response and Spontaneous Alignment in Liquid Crystals Doped with 12-Hydroxystearic Acid Gelators.

PubMed

Lin, Hui-Chi; Wang, Chih-Hung; Wang, Jyun-Kai; Tsai, Sheng-Feng

2018-05-07

The spontaneous vertical alignment of liquid crystals (LCs) in gelator (12-hydroxystearic acid)-doped LC cells was studied. Gelator-induced alignment can be used in both positive and negative LC cells. The electro-optical characteristics of the gelator-doped negative LC cell were similar to those of an LC cell that contained a vertically aligned (VA) host. The rise time of the gelator-doped LC cell was two orders of magnitude shorter than that of the VA host LC cell. The experimental results indicate that the gelator-induced vertical alignment of LC molecules occurred not only on the surface of the indium tin oxide (ITO) but also on the homogeneous alignment layer. Various LC alignments (planar, hybrid, multistable hybrid, and vertical alignments) were achieved by modulating the doped gelator concentrations. The multistable characteristic of LCs doped with the gelator is also presented. The alignment by doping with a gelator reduces the manufacturing costs and provides a means of fabricating fast-responding, flexible LC displays using a low-temperature process.

Vertical root fractures and their management

PubMed Central

Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj

2014-01-01

Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502

Analysis of the Postoperative Displacement of Trochanteric Fractures on Lateral View Radiographs.

PubMed

Furui, Atsuo; Terada, Nobuki

2017-08-01

Achieving sufficient support of the anterior cortex of the femoral neck is a fundamental goal of the reduction of trochanteric fractures. However, anterior-cortex support is often lost after the fracture reduction. Our aim was to analyze factors contributing to the postoperative displacement of an acceptably reduced trochanteric fracture. The cases of 40 patients with a post-reduction Ikuta subtype N fracture alignment were reviewed. All fractures were fixed with 135° free-sliding plates. On postoperative day 14, patients were classified into two groups: those with retention of the Ikuta subtype N alignment, and those with progression to Ikuta subtype P alignment. The clinical and radiological factors were evaluated between the groups. In addition, to define one of the factors, i.e., the postoperative rotational displacement between the proximal and distal fragments, the relationship between radiographic findings and computed tomography image measurements was assessed in 15 of the 40 patients. Angulation at the fracture site on lateral view radiographs was defined as postoperative rotational displacement, and unstable trochanteric fractures and postoperative rotational displacement were identified as significant risk factors for the postoperative displacement. Therefore, cautious and careful follow-up is warranted for patients with unstable trochanteric fractures or fractures having rotational displacement.

Differences in pediatric vertical ground reaction force between planovalgus and neutrally aligned feet.

PubMed

Pauk, Jolanta; Szymul, Joanna

2014-01-01

Ground reaction forces (GRF) reflect the force history of human body contact with the ground. The purpose of this study was to explore human gait abnormalities due to planovalgus by comparing vertical GRF data between individuals with planovalgus and those with neutrally aligned feet. Second we estimated associations between various measurements and vertical GRF parameters in a pediatric population. Boys and girls between the ages of 4 and 18 years (72 planovalgus feet and 74 neutrally aligned feet) took part in this study. Ground reaction forces were recorded by two Kistler platforms and normalized to body weight. Comparison of vertical GRF between planovalgus and neutrally aligned feet suggests that the first and the second peaks of vertical force (Fz1, Fz2) are most affected by planovalgus. The results also indicate that neutrally aligned feet display a different ground reaction force pattern than planovalgus, and that differences between boys and girls may be observed. The shape of the vertical GRF curve can help in clinical interpretation of abnormal gait.

Characterization of fracture permeability with high-resolution vertical flow measurements during borehole pumping.

USGS Publications Warehouse

Paillet, Frederick L.; Hess, A.E.; Cheng, C.H.; Hardin, E.

1987-01-01

The distribution of fracture permeability in granitic rocks was investigated by measuring the distribution of vertical flow in boreholes during periods of steady pumping. Pumping tests were conducted at two sites chosen to provide examples of moderately fractured rocks near Mirror Lake, New Hampshire and intensely fractured rocks near Oracle, Arizona. A sensitive heat-pulse flowmeter was used for accurate measurements of vertical flow as low as 0.2 liter per minute. Results indicate zones of fracture permeability in crystalline rocks are composed of irregular conduits that cannot be approximated by planar fractures of uniform aperture, and that the orientation of permeability zones may be unrelated to the orientation of individual fractures within those zones.-Authors

Fast Response and Spontaneous Alignment in Liquid Crystals Doped with 12-Hydroxystearic Acid Gelators

PubMed Central

Lin, Hui-Chi; Wang, Chih-Hung; Wang, Jyun-Kai; Tsai, Sheng-Feng

2018-01-01

The spontaneous vertical alignment of liquid crystals (LCs) in gelator (12-hydroxystearic acid)-doped LC cells was studied. Gelator-induced alignment can be used in both positive and negative LC cells. The electro-optical characteristics of the gelator-doped negative LC cell were similar to those of an LC cell that contained a vertically aligned (VA) host. The rise time of the gelator-doped LC cell was two orders of magnitude shorter than that of the VA host LC cell. The experimental results indicate that the gelator-induced vertical alignment of LC molecules occurred not only on the surface of the indium tin oxide (ITO) but also on the homogeneous alignment layer. Various LC alignments (planar, hybrid, multistable hybrid, and vertical alignments) were achieved by modulating the doped gelator concentrations. The multistable characteristic of LCs doped with the gelator is also presented. The alignment by doping with a gelator reduces the manufacturing costs and provides a means of fabricating fast-responding, flexible LC displays using a low-temperature process. PMID:29735937

An Innovative Approach for Management of Vertical Coronal Fracture in Molar: Case Report

PubMed Central

Kathuria, Ambica; Kavitha, M.; Ravishankar, P.

2012-01-01

Unlike anterior teeth, acute exogenous trauma is an infrequent cause of posterior coronal vertical tooth fractures. Endodontic and restorative management of such fractures is a great challenge for the clinician. Newer advancements in adhesive techniques can provide successful intracoronal splinting of such teeth to reinforce the remaining tooth structure. This paper describes the diagnosis and management of a case of complicated vertical coronal fracture in mandibular first molar induced by a traffic accident. PMID:22567453

Diagnosis and Managment of Maxillary Incisor with Vertical Root Fracture: A Clinical Report with Three-Year Follow-Up

PubMed Central

Moussaoui, Eya; Chtioui, Fadwa; Douki, Nabiha

2018-01-01

According to the American Association of Endodontists, “a ‘true' vertical root fracture is defined as a complete or incomplete fracture initiated from the root at any level, usually directed buccolingually.” Vertical root fracture (VRF) usually starts from an internal dentinal crack and develops over time, due to masticatory forces and occlusal loads. When they occur in teeth, those types of fractures can present difficulties in diagnosis, and there are however many clinic and radiographical signs which can guide clinicians to the existence of the fracture. Prognosis, most often, is hopeless, and differential diagnosis from other etiologies may be difficult sometimes. In this paper, we present a case of VRF diagnosed after surgical exploration; the enlarged fracture line was filled with a fluid resin. A 36-month clinical and radiological follow-up showed an asymptomatic tooth, reduction of the periodontal probing depth from 7 mm prior to treatment to 4 mm with no signs of ankylosis. In this work, the diagnosis and treatment alternatives of vertical root fracture were discussed through the presented clinical case. PMID:29552361

Diagnosis and Managment of Maxillary Incisor with Vertical Root Fracture: A Clinical Report with Three-Year Follow-Up.

PubMed

Kallel, Ines; Moussaoui, Eya; Chtioui, Fadwa; Douki, Nabiha

2018-01-01

According to the American Association of Endodontists, "a 'true' vertical root fracture is defined as a complete or incomplete fracture initiated from the root at any level, usually directed buccolingually." Vertical root fracture (VRF) usually starts from an internal dentinal crack and develops over time, due to masticatory forces and occlusal loads. When they occur in teeth, those types of fractures can present difficulties in diagnosis, and there are however many clinic and radiographical signs which can guide clinicians to the existence of the fracture. Prognosis, most often, is hopeless, and differential diagnosis from other etiologies may be difficult sometimes. In this paper, we present a case of VRF diagnosed after surgical exploration; the enlarged fracture line was filled with a fluid resin. A 36-month clinical and radiological follow-up showed an asymptomatic tooth, reduction of the periodontal probing depth from 7 mm prior to treatment to 4 mm with no signs of ankylosis. In this work, the diagnosis and treatment alternatives of vertical root fracture were discussed through the presented clinical case.

Controlled Synthesis and Functionalization of Vertically-Aligned Carbon Nanotubes for Multifunctional Applications

DTIC Science & Technology

2015-05-07

6 1.6 Lithium - Ion Batteries Based on Vertically-Aligned Carbon Nanotube Electrodes and Ionic...Cl, Br, or I) Prepared by Ball-Milling and Used as Anode Materials for Lithium - Ion Batteries ……………....................23 3.4 Well-Defined Two...9 1.6 Lithium - Ion Batteries Based on Vertically-Aligned Carbon Nanotube Electrodes and Ionic Liquid Electrolytes

In vitro resistance to fracture of roots obturated with Resilon or gutta-percha.

PubMed

Monteiro, Jeanne; de Ataide, Ida de Noronha; Chalakkal, Paul; Chandra, Pavan Kumar

2011-06-01

There have been varied results from studies comparing postendodontic fracture resistance between teeth obturated with Resilon or gutta-percha. This study was performed to evaluate the fracture resistance of roots obturated by using Resilon (RealSeal system) or gutta-percha (with AH Plus sealer). Eighty extracted human mandibular single-rooted premolars stored in 10% formalin were used in the study. They were prepared by using a crown-down technique, debrided with NaOCl, ethylenediaminetetraacetic acid, and sterile water and divided into 4 groups. Obturation was performed by using the lateral condensation method. The negative control group consisted of unfilled specimens, and the positive control group consisted of those obturated with flowable, dual-cure composite resin. All root specimens were stored for 2 weeks in 100% humidity to allow complete setting of the sealer. Each specimen was mounted in acrylic in a polyvinyl ring and tested for fracture resistance with the Universal testing machine. The loading fixture of the machine was mounted with its spherical tip aligned with the center of the canal opening of each root. A vertical loading force was applied until it fractured the root. The force values were subjected to statistical analysis including analysis of variance and Fisher least significant difference testing. Teeth obturated with Resilon were more resistant to fracture than those obturated with gutta-percha. The difference was found to be highly significant (P=.00001). Resilon increased the resistance to fracture of single-rooted teeth in vitro. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Formation and evolution of radial fracture systems on Venus

NASA Technical Reports Server (NTRS)

Parfitt, E. A.; Head, James W.

1993-01-01

A survey of approximately 90 percent of the surface of Venus using Magellan data has been carried out to locate all radial fracture systems and to assess their association with other features such as volcanic edifices and coronae. Squyres et al. and Stofan et al. have discussed the association of radial fracture features in relation to coronae features, our approach was to assess the associations of all of the fracture systems. These fracture systems have two broad types of form - some fracture systems are associated with updomed topography, radiate from a point and have relatively uniform fracture lengths while others have a wider range of fracture lengths and radiate from the outer edge of a central caldera. Squyres et al. and Stofan et al. have interpreted both types of feature as reflecting tectonic fracturing resulting from uplift of the surface as a mantle plume impinges upon the crust. While it is true that a number of features are related to uplift and that such uplift will induce stresses consistent with radial fracturing, we explore the possibility that these fractures are not exclusively of tectonic origin. Purely tectonic fracturing will tend to generate a few main fractures/faults along which most of the stresses due to uplift will be accommodated leading to the triple-junction form common for terrestrial updoming. Though this type of feature is observed on Venus (e.g., feature located at 34S86), the majority of radial fracture systems display much more intensive fracturing than this through a full 360 degrees; this is difficult to explain by purely tectonic processes. The association of many of the fractures with radial lava flows leads us to interpret these fractures as reflecting dike emplacement: the form of the fractures being consistent with primarily vertical propagation from the head of a mantle plume. In the case of the second type of fracture system (those radiating from a central caldera), an even stronger case can be made that the fractures are not of tectonic origin. These features are not as commonly associated with updoming of the surface and where they are, the fractures extend out well beyond the edge of the topographic rise - an observation which is not consistent with the fractures being of tectonic uplift origin. Furthermore the fractures have a distribution of lengths (many short, fewer long) which is characteristic of dike swarms, and show direct associations with calderas and lava flows consistent with a volcanic origin. In addition, the longest fractures have a radial pattern only close to the center of the system but bend with distance to align themselves with the regional stress field - this behavior is very difficult to explain on purely tectonic grounds but is a pattern commonly seen for terrestrial dikes. For these reasons, we argue that many, if not the majority, of radial fracture systems found on Venus are the surface reflection of dike swarms, those associated with positive topography reflecting vertical emplacement and those radiating from calderas reflecting lateral propagation.

A critical look at spatial scale choices in satellite-based aerosol indirect effect studies

NASA Astrophysics Data System (ADS)

Grandey, B. S.; Stier, P.

2010-06-01

Analysing satellite datasets over large regions may introduce spurious relationships between aerosol and cloud properties due to spatial variations in aerosol type, cloud regime and synoptic regime climatologies. Using MODerate resolution Imaging Spectroradiometer data, we calculate relationships between aerosol optical depth τa, derived liquid cloud droplet effective number concentration Ne and liquid cloud droplet effective radius re at different spatial scales. Generally, positive values of dlnNe dlnτa are found for ocean regions, whilst negative values occur for many land regions. The spatial distribution of dlnre dlnτa shows approximately the opposite pattern, with generally postive values for land regions and negative values for ocean regions. We find that for region sizes larger than 4°×4°, spurious spatial variations in retrieved cloud and aerosol properties can introduce widespread significant errors to calculations of dlnNe dlnτa and dlnre dlnτa . For regions on the scale of 60°×60°, these methodological errors may lead to an overestimate in global cloud albedo effect radiative forcing of order 80%.

Azimuthal Seismic Amplitude Variation with Offset and Azimuth Inversion in Weakly Anisotropic Media with Orthorhombic Symmetry

NASA Astrophysics Data System (ADS)

Pan, Xinpeng; Zhang, Guangzhi; Yin, Xingyao

2018-01-01

Seismic amplitude variation with offset and azimuth (AVOaz) inversion is well known as a popular and pragmatic tool utilized to estimate fracture parameters. A single set of vertical fractures aligned along a preferred horizontal direction embedded in a horizontally layered medium can be considered as an effective long-wavelength orthorhombic medium. Estimation of Thomsen's weak-anisotropy (WA) parameters and fracture weaknesses plays an important role in characterizing the orthorhombic anisotropy in a weakly anisotropic medium. Our goal is to demonstrate an orthorhombic anisotropic AVOaz inversion approach to describe the orthorhombic anisotropy utilizing the observable wide-azimuth seismic reflection data in a fractured reservoir with the assumption of orthorhombic symmetry. Combining Thomsen's WA theory and linear-slip model, we first derive a perturbation in stiffness matrix of a weakly anisotropic medium with orthorhombic symmetry under the assumption of small WA parameters and fracture weaknesses. Using the perturbation matrix and scattering function, we then derive an expression for linearized PP-wave reflection coefficient in terms of P- and S-wave moduli, density, Thomsen's WA parameters, and fracture weaknesses in such an orthorhombic medium, which avoids the complicated nonlinear relationship between the orthorhombic anisotropy and azimuthal seismic reflection data. Incorporating azimuthal seismic data and Bayesian inversion theory, the maximum a posteriori solutions of Thomsen's WA parameters and fracture weaknesses in a weakly anisotropic medium with orthorhombic symmetry are reasonably estimated with the constraints of Cauchy a priori probability distribution and smooth initial models of model parameters to enhance the inversion resolution and the nonlinear iteratively reweighted least squares strategy. The synthetic examples containing a moderate noise demonstrate the feasibility of the derived orthorhombic anisotropic AVOaz inversion method, and the real data illustrate the inversion stabilities of orthorhombic anisotropy in a fractured reservoir.

Hybrid hydrogels containing vertically aligned carbon nanotubes with anisotropic electrical conductivity for muscle myofiber fabrication.

PubMed

Ahadian, Samad; Ramón-Azcón, Javier; Estili, Mehdi; Liang, Xiaobin; Ostrovidov, Serge; Shiku, Hitoshi; Ramalingam, Murugan; Nakajima, Ken; Sakka, Yoshio; Bae, Hojae; Matsue, Tomokazu; Khademhosseini, Ali

2014-03-19

Biological scaffolds with tunable electrical and mechanical properties are of great interest in many different fields, such as regenerative medicine, biorobotics, and biosensing. In this study, dielectrophoresis (DEP) was used to vertically align carbon nanotubes (CNTs) within methacrylated gelatin (GelMA) hydrogels in a robust, simple, and rapid manner. GelMA-aligned CNT hydrogels showed anisotropic electrical conductivity and superior mechanical properties compared with pristine GelMA hydrogels and GelMA hydrogels containing randomly distributed CNTs. Skeletal muscle cells grown on vertically aligned CNTs in GelMA hydrogels yielded a higher number of functional myofibers than cells that were cultured on hydrogels with randomly distributed CNTs and horizontally aligned CNTs, as confirmed by the expression of myogenic genes and proteins. In addition, the myogenic gene and protein expression increased more profoundly after applying electrical stimulation along the direction of the aligned CNTs due to the anisotropic conductivity of the hybrid GelMA-vertically aligned CNT hydrogels. We believe that platform could attract great attention in other biomedical applications, such as biosensing, bioelectronics, and creating functional biomedical devices.

Hybrid hydrogels containing vertically aligned carbon nanotubes with anisotropic electrical conductivity for muscle myofiber fabrication

PubMed Central

Ahadian, Samad; Ramón-Azcón, Javier; Estili, Mehdi; Liang, Xiaobin; Ostrovidov, Serge; Shiku, Hitoshi; Ramalingam, Murugan; Nakajima, Ken; Sakka, Yoshio; Bae, Hojae; Matsue, Tomokazu; Khademhosseini, Ali

2014-01-01

Biological scaffolds with tunable electrical and mechanical properties are of great interest in many different fields, such as regenerative medicine, biorobotics, and biosensing. In this study, dielectrophoresis (DEP) was used to vertically align carbon nanotubes (CNTs) within methacrylated gelatin (GelMA) hydrogels in a robust, simple, and rapid manner. GelMA-aligned CNT hydrogels showed anisotropic electrical conductivity and superior mechanical properties compared with pristine GelMA hydrogels and GelMA hydrogels containing randomly distributed CNTs. Skeletal muscle cells grown on vertically aligned CNTs in GelMA hydrogels yielded a higher number of functional myofibers than cells that were cultured on hydrogels with randomly distributed CNTs and horizontally aligned CNTs, as confirmed by the expression of myogenic genes and proteins. In addition, the myogenic gene and protein expression increased more profoundly after applying electrical stimulation along the direction of the aligned CNTs due to the anisotropic conductivity of the hybrid GelMA-vertically aligned CNT hydrogels. We believe that platform could attract great attention in other biomedical applications, such as biosensing, bioelectronics, and creating functional biomedical devices. PMID:24642903

Hybrid hydrogels containing vertically aligned carbon nanotubes with anisotropic electrical conductivity for muscle myofiber fabrication

NASA Astrophysics Data System (ADS)

Ahadian, Samad; Ramón-Azcón, Javier; Estili, Mehdi; Liang, Xiaobin; Ostrovidov, Serge; Shiku, Hitoshi; Ramalingam, Murugan; Nakajima, Ken; Sakka, Yoshio; Bae, Hojae; Matsue, Tomokazu; Khademhosseini, Ali

2014-03-01

Biological scaffolds with tunable electrical and mechanical properties are of great interest in many different fields, such as regenerative medicine, biorobotics, and biosensing. In this study, dielectrophoresis (DEP) was used to vertically align carbon nanotubes (CNTs) within methacrylated gelatin (GelMA) hydrogels in a robust, simple, and rapid manner. GelMA-aligned CNT hydrogels showed anisotropic electrical conductivity and superior mechanical properties compared with pristine GelMA hydrogels and GelMA hydrogels containing randomly distributed CNTs. Skeletal muscle cells grown on vertically aligned CNTs in GelMA hydrogels yielded a higher number of functional myofibers than cells that were cultured on hydrogels with randomly distributed CNTs and horizontally aligned CNTs, as confirmed by the expression of myogenic genes and proteins. In addition, the myogenic gene and protein expression increased more profoundly after applying electrical stimulation along the direction of the aligned CNTs due to the anisotropic conductivity of the hybrid GelMA-vertically aligned CNT hydrogels. We believe that platform could attract great attention in other biomedical applications, such as biosensing, bioelectronics, and creating functional biomedical devices.

Physical simulation study on the hydraulic fracture propagation of coalbed methane well

NASA Astrophysics Data System (ADS)

Wu, Caifang; Zhang, Xiaoyang; Wang, Meng; Zhou, Longgang; Jiang, Wei

2018-03-01

As the most widely used technique to modify reservoirs in the exploitation of unconventional natural gas, hydraulic fracturing could effectively raise the production of CBM wells. To study the propagation rules of hydraulic fractures, analyze the fracture morphology, and obtain the controlling factors, a physical simulation experiment was conducted with a tri-axial hydraulic fracturing test system. In this experiment, the fracturing sample - including the roof, the floor, and the surrounding rock - was prepared from coal and similar materials, and the whole fracturing process was monitored by an acoustic emission instrument. The results demonstrated that the number of hydraulic fractures in coal is considerably higher than that observed in other parts, and the fracture morphology was complex. Vertical fractures were interwoven with horizontal fractures, forming a connected network. With the injection of fracturing fluid, a new hydraulic fracture was produced and it extended along the preexisting fractures. The fracture propagation was a discontinuous, dynamic process. Furthermore, in-situ stress plays a key role in fracture propagation, causing the fractures to extend in a direction perpendicular to the minimum principal stress. To a certain extent, the different mechanical properties of the coal and the other components inhibited the vertical propagation of hydraulic fractures. Nonetheless, the vertical stress and the interfacial property are the major factors to influence the formation of the "T" shaped and "工" shaped fractures.

Effect of processing induced particle alignment on the fracture toughness and fracture behavior of multiphase dental ceramics.

PubMed

Gonzaga, Carla C; Okada, Cristina Yuri; Cesar, Paulo F; Miranda, Walter G; Yoshimura, Humberto N

2009-11-01

To investigate the processing induced particle alignment on fracture behavior of four multiphase dental ceramics (one porcelain, two glass-ceramics and a glass-infiltrated-alumina composite). Disks (Ø12 mm x 1.1mm-thick) and bars (3 mm x 4 mm x 20 mm) of each material were processed according to manufacturer instructions, machined and polished. Fracture toughness (K(Ic)) was determined by the indentation strength method using 3-point bending and biaxial flexure fixtures for the fracture of bars and disks, respectively. Microstructural and fractographic analyses were performed with scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The isotropic microstructure of the porcelain and the leucite-based glass-ceramic resulted in similar fracture toughness values regardless of the specimen geometry. On the other hand, materials containing second-phase particles with high aspect ratio (lithium disilicate glass-ceramic and glass-infiltrated-alumina composite) showed lower fracture toughness for disk specimens compared to bars. For the lithium disilicate glass-ceramic disks, it was demonstrated that the occurrence of particle alignment during the heat-pressing procedure resulted in an unfavorable pattern that created weak microstructural paths during the biaxial test. For the glass-infiltrated-alumina composite, the microstructural analysis showed that the large alumina platelets tended to align their large surfaces perpendicularly to the direction of particle deposition during slip casting of green preforms. The fracture toughness of dental ceramics with anisotropic microstructure should be determined by means of biaxial testing, since it results in lower values.

Experimental observation of water saturation effects on shear wave splitting in synthetic rock with fractures aligned at oblique angles

NASA Astrophysics Data System (ADS)

Amalokwu, Kelvin; Chapman, Mark; Best, Angus I.; Sothcott, Jeremy; Minshull, Timothy A.; Li, Xiang-Yang

2015-01-01

Fractured rocks are known to exhibit seismic anisotropy and shear wave splitting (SWS). SWS is commonly used for fractured rock characterization and has been shown to be sensitive to fluid type. The presence of partial liquid/gas saturation is also known to affect the elastic properties of rocks. The combined effect of both fractures and partial liquid/gas saturation is still unknown. Using synthetic, silica-cemented sandstones with aligned penny-shaped voids, we conducted laboratory ultrasonic experiments to investigate the effect fractures aligned at an oblique angle to wave propagation would have on SWS under partial liquid/gas saturation conditions. The result for the fractured rock shows a saturation dependence which can be explained by combining a fractured rock model and a partial saturation model. At high to full water saturation values, SWS decreases as a result of the fluid bulk modulus effect on the quasi-shear wave. This bulk modulus effect is frequency dependent as a result of wave-induced fluid flow mechanisms, which would in turn lead to frequency dependent SWS. This result suggests the possible use of SWS for discriminating between full liquid saturation and partial liquid/gas saturation.

Preferential flow and pesticide transport in a clay-rich till: Field, laboratory, and modeling analysis

NASA Astrophysics Data System (ADS)

JøRgensen, Peter R.; Hoffmann, Martin; Kistrup, Jens P.; Bryde, Claus; Bossi, Rossana; Villholth, Karen G.

2002-11-01

This study investigates vertical flow and pesticide transport along fractures in water saturated unoxidized clayey till. From two experimental fields, each 40 m2, 96% and 98%, respectively, of total vertical flow was conducted along fractures in the till, while the remaining 2-4% of flow occurred in the clay matrix at very slow flow rate. An applied dye tracer was observed only along 10-26% of the total fracture length measured on the horizontal surface of the experimental fields. In vertical sections the dyed fracture portions constituted root channels, which penetrated the till vertically along the fractures into the local aquifer at 5 m depth. No dye tracer was observed in the fractures without root channels or in the unfractured clay matrix, suggesting that root growth along the fracture surfaces was the principal agent of fracture aperture enhancement. Using hydraulic fracture aperture values determined from large undisturbed column (LUC) collected from one of the experimental fields, it was estimated that 94% of flow in the fractures was conducted along the fracture root channels, while only 6% of flow was conducted along the fracture sections without root channels. For natural vertical hydraulic gradients (0.8-2.3 at the site), flow rates of 0.8-2 km/d were determined for a fracture root channel, while fracture sections without root channels revealed flow rates of 9-22 m/d. Corresponding flow rates in the unfractured matrix were 7-19 mm/yr. For infiltrated bromide (nonreactive tracer) and mobile pesticides mecoprop (MCPP) and metsulfuron, very rapid migration (0.28-0.5 m/d) and high relative breakthrough concentrations (30-60%) into the aquifer were observed to occur along the fracture root channels using a constant hydraulic gradient of 1. Only traces were measured from infiltration of the strongly sorbed pesticide prochloraz. The concentrations of the bromide and pesticides in the monitoring wells were modeled with a discrete fracture matrix diffusion (DFDM) model coupled with a single porosity model (SP) for the till and aquifer, respectively. Using effective fracture spacings and mean fracture apertures for the fracture channel sections as modeling input parameters for the till, the concentrations observed in the wells of the aquifer could be reasonably approximated.

A 3-dimensional-printed patient-specific guide system for minimally invasive plate osteosynthesis of a comminuted mid-diaphyseal humeral fracture in a cat.

PubMed

Oxley, Bill

2018-04-01

To report the use of a 3-dimensional (3D)-printed patient-specific reduction guide system to facilitate minimally invasive plate osteosynthesis (MIPO) of a humeral fracture in a cat. Case report. A 9-year-old male neutered domestic short hair cat weighing 4.4 kg. A 9-year-old male domestic short hair cat was presented with a comminuted, mid-diaphyseal left humeral fracture. Computed tomographic data were processed to yield 3D mesh representations of both humeri and subsequently manipulated in computer-aided design software. The mirrored, intact humerus was used as a template for appropriate spatial orientation of the major proximal and distal fracture fragments. Patient-specific Ellis pin orientation guides and a reduction guide were designed and 3D printed. The guide system was used intraoperatively to align the major fracture fragments before application of locking internal fixation via standard MIPO surgical portals. Internal fixation of the fracture resulted in appropriate bone alignment. Recovery was uncomplicated, with early return to normal limb function and radiographic evidence of advanced fracture healing after 4 months. A 3D-printed patient-specific reduction guide system facilitated accurate alignment of a comminuted humeral fracture during MIPO without intraoperative imaging. © 2018 The American College of Veterinary Surgeons.

Kinesthetic perceptions of earth- and body-fixed axes.

PubMed

Darling, W G; Hondzinski, J M

1999-06-01

The major purpose of this research was to determine whether kinesthetic/proprioceptive perceptions of the earth-fixed vertical axis are more accurate than perceptions of intrinsic axes. In one experiment, accuracy of alignment of the forearm to earth-fixed vertical and head- and trunk-longitudinal axes by seven blindfolded subjects was compared in four tasks: (1) Earth-Arm--arm (humerus) orientation was manipulated by the experimenter; subjects aligned the forearm parallel to the vertical axis, which was also aligned with the head and trunk longitudinal axis; (2) Head--head, trunk, and upper-limb orientations were manipulated by the experimenter, subjects aligned the forearm parallel to the longitudinal axis of the head using only elbow flexion/extension and shoulder internal/external rotation; (3) Trunk--same as (2), except that subjects aligned the forearm parallel to the trunk-longitudinal axis; (4) Earth--same as (2), except that subjects aligned the forearm parallel to the earth-fixed vertical. Head, trunk, and gravitational axes were never parallel in tasks 2, 3, and 4 so that subjects could not simultaneously match their forearm to all three axes. The results showed that the errors for alignment of the forearm with the earth-fixed vertical were lower than for the trunk- and head-longitudinal axes. Furthermore, errors in the Earth condition were less dependent on alterations of the head and trunk orientation than in the Head and Trunk conditions. These data strongly suggest that the earth-fixed vertical is used as one axis for the kinesthetic sensory coordinate system that specifies upper-limb orientation at the perceptual level. We also examined the effects of varying gravitational torques at the elbow and shoulder on the accuracy of forearm alignment to earth-fixed axes. Adding a 450 g load to the forearm to increase gravitational torques when the forearm is not vertical did not improve the accuracy of forearm alignment with the vertical. Furthermore, adding small, variably sized loads (between which the subjects could not distinguish at the perceptual level) to the forearm just proximal to the wrist produced similar errors in aligning the forearm with the vertical and horizontal. Forearm-positioning errors were not correlated with the size of the load, as would be expected if gravitational torques affected forearm-position sense. We conclude that gravitational torques exerted about the shoulder and elbow do not make significant contributions to sensing forearm-orientation relative to earth-fixed axes when the upper-limb segments are not constrained by external supports.

The fracture sites of atypical femoral fractures are associated with the weight-bearing lower limb alignment.

PubMed

Saita, Yoshitomo; Ishijima, Muneaki; Mogami, Atsuhiko; Kubota, Mitsuaki; Baba, Tomonori; Kaketa, Takefumi; Nagao, Masashi; Sakamoto, Yuko; Sakai, Kensuke; Kato, Rui; Nagura, Nana; Miyagawa, Kei; Wada, Tomoki; Liu, Lizu; Obayashi, Osamu; Shitoto, Katsuo; Nozawa, Masahiko; Kajihara, Hajime; Gen, Hogaku; Kaneko, Kazuo

2014-09-01

Atypical femoral fractures (AFFs) are stress-related fractures that are speculated to associate with long-term treatment with bisphosphonates for osteoporosis. A history of AFF is a high risk factor for the development of a subsequent AFF in the same location of the contralateral femur, suggesting that a patient's individual anatomical factor(s) are related to the fracture site of AFFs. In this study, we investigated the radiographs of fourteen AFFs (four bilateral fractures among ten patients) treated at six hospitals associated with our university between 2005 and 2010. The fracture site and standing femorotibial angle (FTA), which reflects the mechanical axis of the lower limb, were measured on weight-bearing lower limb radiographs. The fracture site and FTA of patients with typical femoral fractures (TFF) were compared to those of patients with AFFs. The correlations were examined using Spearman's rank correlation coefficients. The fracture locations in the femora were almost the same in the patients with bilateral AFFs. There was a positive correlation between the fracture site and the standing FTA in the patients with AFFs (r=0.82, 95% confidence interval; 0.49 to 0.94), indicating that the larger the standing FTA (varus alignment), the more distal the site of the fracture in the femur. The FTA of the patients with atypical diaphyseal femoral fracture were significantly larger compared to that of those with not only atypical subtrochanteric fractures but also TFFs. In conclusion, the fracture sites of AFFs are associated with the standing lower limb alignment, while those of TFFs are not. Copyright © 2014 Elsevier Inc. All rights reserved.

The Comprehensive AOCMF Classification System: Condylar Process Fractures - Level 3 Tutorial

PubMed Central

Neff, Andreas; Cornelius, Carl-Peter; Rasse, Michael; Torre, Daniel Dalla; Audigé, Laurent

2014-01-01

This tutorial outlines the detailed system for fractures of the condylar process at the precision level 3 and is organized in a sequence of sections dealing with the description of the classification system within topographical subdivisions along with rules for fracture coding and a series of case examples with clinical imaging. Basically, the condylar process comprises three fracture levels and is subdivided into the head region, the condylar neck, and the condylar base. Fractures of the condylar head show typical fracture lines either within the lateral pole zone, which may lead to loss of vertical height, or medially to the pole zone, with the latter ones usually not compromising the vertical condyle to fossa relation. In condylar head fractures, the morphology is further described by the presence of minor or major fragmentation, the vertical apposition of fragments at the plane of the head fracture, the displacement of the condylar head with regard to the fossa including a potential distortion of the condylar head congruency resulting in dystopic condyle to fossa relations and the presence or absence of a loss of vertical ramus height. A specific vertical fracture pattern extending from the head to the neck or base subregion is considered. Fractures of the condylar neck and base can be differentiated according to a newly introduced one-third to two-thirds rule with regard to the proportion of the fracture line above and below the level of the sigmoid notch, which is presented in the classification article, and are basically subdivided according to the presence or absence of displacement or dislocation. In both condylar neck and base fractures, the classification is again based on the above mentioned parameters such as fragmentation, displacement of the condylar head with regard to the fossa, including dystopic condyle to fossa relations and loss of vertical ramus height, that is, according to the measurement of the condylar process. In addition, the classification assesses a sideward displacement including the respective displacement sector at the neck or base fracture site as well as the angulation of the superior main fragment and also considers a potential displacement of the caudal fragment with regard to the fossa, which may occur in fractures affecting additional fracture locations in the mandible. The design of this classification is discussed along with a review of existing classification systems. The condylar process for fracture location was defined according to the level 2 system presented in a previous tutorial in this special issue. PMID:25489390

The Comprehensive AOCMF Classification System: Condylar Process Fractures - Level 3 Tutorial.

PubMed

Neff, Andreas; Cornelius, Carl-Peter; Rasse, Michael; Torre, Daniel Dalla; Audigé, Laurent

2014-12-01

This tutorial outlines the detailed system for fractures of the condylar process at the precision level 3 and is organized in a sequence of sections dealing with the description of the classification system within topographical subdivisions along with rules for fracture coding and a series of case examples with clinical imaging. Basically, the condylar process comprises three fracture levels and is subdivided into the head region, the condylar neck, and the condylar base. Fractures of the condylar head show typical fracture lines either within the lateral pole zone, which may lead to loss of vertical height, or medially to the pole zone, with the latter ones usually not compromising the vertical condyle to fossa relation. In condylar head fractures, the morphology is further described by the presence of minor or major fragmentation, the vertical apposition of fragments at the plane of the head fracture, the displacement of the condylar head with regard to the fossa including a potential distortion of the condylar head congruency resulting in dystopic condyle to fossa relations and the presence or absence of a loss of vertical ramus height. A specific vertical fracture pattern extending from the head to the neck or base subregion is considered. Fractures of the condylar neck and base can be differentiated according to a newly introduced one-third to two-thirds rule with regard to the proportion of the fracture line above and below the level of the sigmoid notch, which is presented in the classification article, and are basically subdivided according to the presence or absence of displacement or dislocation. In both condylar neck and base fractures, the classification is again based on the above mentioned parameters such as fragmentation, displacement of the condylar head with regard to the fossa, including dystopic condyle to fossa relations and loss of vertical ramus height, that is, according to the measurement of the condylar process. In addition, the classification assesses a sideward displacement including the respective displacement sector at the neck or base fracture site as well as the angulation of the superior main fragment and also considers a potential displacement of the caudal fragment with regard to the fossa, which may occur in fractures affecting additional fracture locations in the mandible. The design of this classification is discussed along with a review of existing classification systems. The condylar process for fracture location was defined according to the level 2 system presented in a previous tutorial in this special issue.

Surgical management of vertical root fractures for posterior teeth: report of four cases.

PubMed

Floratos, Spyros G; Kratchman, Samuel I

2012-04-01

The objective of this article was to present a surgical treatment option for teeth with incomplete vertical root fracture in maxillary and mandibular posterior teeth. Four cases are presented in which 1 endodontically treated maxillary or mandibular molar had an incomplete vertical root fracture involving 1 of the roots. The tooth underwent a flap elevation procedure to visualize the pattern of bone loss and assess the extent of root fracture. The fracture line was eliminated by resecting the root in a beveled manner, after which root-end preparation and root-end filling were performed by using mineral trioxide aggregate. The osteotomy was covered with an absorbable collagen membrane. Cases were followed up for 8-24 months after surgery. The procedure was shown to be predictable and successful in this series. Root length was preserved, and tooth extraction was avoided. The microsurgical treatment option for multirooted teeth with incomplete vertical root fracture resulted in long-term clinical success. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

FORGE Milford Triaxial Test Data and Summary from EGI labs

DOE Data Explorer

Joe Moore

2016-03-01

Six samples were evaluated in unconfined and triaxial compression, their data are included in separate excel spreadsheets, and summarized in the word document. Three samples were plugged along the axis of the core (presumed to be nominally vertical) and three samples were plugged perpendicular to the axis of the core. A designation of "V"indicates vertical or the long axis of the plugged sample is aligned with the axis of the core. Similarly, "H" indicates a sample that is nominally horizontal and cut orthogonal to the axis of the core. Stress-strain curves were made before and after the testing, and are included in the word doc.. The confining pressure for this test was 2800 psi. A series of tests are being carried out on to define a failure envelope, to provide representative hydraulic fracture design parameters and for future geomechanical assessments. The samples are from well 52-21, which reaches a maximum depth of 3581 ft +/- 2 ft into a gneiss complex.

Proposed technique for vertical alignment of a crane's cable

NASA Technical Reports Server (NTRS)

Gera, J., Jr.

1969-01-01

Proposed vertical alignment technique senses the attitude of a cranes cable and displays any deviation from the vertical. The system consists of a detector assembly fixed to the boom and a display scope located in the cabin. It has potential application with either fixed-boom cranes or gantries.

Controllable growth of vertically aligned graphene on C-face SiC

DOE PAGES

Liu, Yu; Chen, Lianlian; Hilliard, Donovan; ...

2016-10-06

We investigated how to control the growth of vertically aligned graphene on C-face SiC by varying the processing conditions. It is found that, the growth rate scales with the annealing temperature and the graphene height is proportional to the annealing time. Temperature gradient and crystalline quality of the SiC substrates influence their vaporization. The partial vapor pressure is crucial as it can interfere with further vaporization. A growth mechanism is proposed in terms of physical vapor transport. The monolayer character of vertically aligned graphene is verified by Raman and X-ray absorption spectroscopy. With the processed samples, d 0 magnetism ismore » realized and negative magnetoresistance is observed after Cu implantation. We also prove that multiple carriers exist in vertically aligned graphene.« less

Controllable growth of vertically aligned graphene on C-face SiC

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

Liu, Yu; Chen, Lianlian; Hilliard, Donovan

We investigated how to control the growth of vertically aligned graphene on C-face SiC by varying the processing conditions. It is found that, the growth rate scales with the annealing temperature and the graphene height is proportional to the annealing time. Temperature gradient and crystalline quality of the SiC substrates influence their vaporization. The partial vapor pressure is crucial as it can interfere with further vaporization. A growth mechanism is proposed in terms of physical vapor transport. The monolayer character of vertically aligned graphene is verified by Raman and X-ray absorption spectroscopy. With the processed samples, d 0 magnetism ismore » realized and negative magnetoresistance is observed after Cu implantation. We also prove that multiple carriers exist in vertically aligned graphene.« less

3D reconstruction of highly fragmented bone fractures

NASA Astrophysics Data System (ADS)

Willis, Andrew; Anderson, Donald; Thomas, Thad; Brown, Thomas; Marsh, J. Lawrence

2007-03-01

A system for the semi-automatic reconstruction of highly fragmented bone fractures, developed to aid in treatment planning, is presented. The system aligns bone fragment surfaces derived from segmentation of volumetric CT scan data. Each fragment surface is partitioned into intact- and fracture-surfaces, corresponding more or less to cortical and cancellous bone, respectively. A user then interactively selects fracture-surface patches in pairs that coarsely correspond. A final optimization step is performed automatically to solve the N-body rigid alignment problem. The work represents the first example of a 3D bone fracture reconstruction system and addresses two new problems unique to the reconstruction of fractured bones: (1) non-stationary noise inherent in surfaces generated from a difficult segmentation problem and (2) the possibility that a single fracture surface on a fragment may correspond to many other fragments.

Partially to fully saturated flow through smooth, clean, open fractures: qualitative experimental studies

NASA Astrophysics Data System (ADS)

Jones, Brendon R.; Brouwers, Luke B.; Dippenaar, Matthys A.

2018-05-01

Fractures are both rough and irregular but can be expressed by a simple model concept of two smooth parallel plates and the associated cubic law governing discharge through saturated fractures. However, in natural conditions and in the intermediate vadose zone, these assumptions are likely violated. This paper presents a qualitative experimental study investigating the cubic law under variable saturation in initially dry free-draining discrete fractures. The study comprised flow visualisation experiments conducted on transparent replicas of smooth parallel plates with inlet conditions of constant pressure and differing flow rates over both vertical and horizontal inclination. Flow conditions were altered to investigate the influence of intermittent and continuous influx scenarios. Findings from this research proved, for instance, that saturated laminar flow is not likely achieved, especially in nonhorizontal fractures. In vertical fractures, preferential flow occupies the minority of cross-sectional area despite the water supply. Movement of water through the fractured vadose zone therefore becomes a matter of the continuity principle, whereby water should theoretically be transported downward at significantly higher flow rates given the very low degree of water saturation. Current techniques that aim to quantify discrete fracture flow, notably at partial saturation, are questionable. Inspired by the results of this study, it is therefore hypothetically improbable to achieve saturation in vertical fractures under free-draining wetting conditions. It does become possible under extremely excessive water inflows or when not free-draining; however, the converse is not true, as a wet vertical fracture can be drained.

Growth of vertically aligned carbon nanotubes on silicon and quartz substrate by spray pyrolysis of a natural precursor: Turpentine oil

NASA Astrophysics Data System (ADS)

Afre, Rakesh A.; Soga, T.; Jimbo, T.; Kumar, Mukul; Ando, Y.; Sharon, M.

2005-10-01

Vertically aligned carbon nanotubes (VACNTs) were grown by spray pyrolysis of turpentine oil and ferrocene mixture at 700 °C. Using this simple method, we report the successful growth of vertically aligned nanotubes of 300 μm length and diameter in the range of 50-100 nm on Si(1 0 0) substrate. The ferrocene act as an in situ Fe catalyst precursor and forming the nanosize iron particles for formation of VACNTs on Si and quartz substrates. Morphological differences between aligned carbon nanotubes grown on different substrates are studied and discussed by SEM, TEM and Raman spectroscopy characterizations.

A critical look at spatial scale choices in satellite-based aerosol indirect effect studies

NASA Astrophysics Data System (ADS)

Grandey, B. S.; Stier, P.

2010-12-01

Analysing satellite datasets over large regions may introduce spurious relationships between aerosol and cloud properties due to spatial variations in aerosol type, cloud regime and synoptic regime climatologies. Using MODerate resolution Imaging Spectroradiometer data, we calculate relationships between aerosol optical depth τa derived liquid cloud droplet effective number concentration Ne and liquid cloud droplet effective radius re at different spatial scales. Generally, positive values of dlnNedlnτa are found for ocean regions, whilst negative values occur for many land regions. The spatial distribution of dlnredlnτa shows approximately the opposite pattern, with generally postive values for land regions and negative values for ocean regions. We find that for region sizes larger than 4° × 4°, spurious spatial variations in retrieved cloud and aerosol properties can introduce widespread significant errors to calculations of dlnNedlnτa and dlnredlnτa. For regions on the scale of 60° × 60°, these methodological errors may lead to an overestimate in global cloud albedo effect radiative forcing of order 80% relative to that calculated for regions on the scale of 1° × 1°.

Outcomes of long retrograde intramedullary nailing for periprosthetic supracondylar femoral fractures following total knee arthroplasty.

PubMed

Lee, Sung-San; Lim, Seung-Jae; Moon, Young-Wan; Seo, Jai-Gon

2014-01-01

The treatment of periprosthetic supracondylar femoral fractures following total knee arthroplasty (TKA) is challenging because of osteopenia and the limited bone available for distal fixation. The purpose of this study was to report the outcomes of periprosthetic supracondylar femoral fractures treated with long retrograde intramedullary nailing. We conducted a retrospective review of 25 patients who were treated with a long retrograde intramedullary nail for periprosthetic supracondylar femoral fractures following TKA. Clinical evaluation included range of motion of knee, Knee Society Score (KSS), Western Ontario and McMaster Universities Arthritis (WOMAC) score, and radiologic evaluation including time to union, coronal and sagittal alignment of femoral component, lower limb alignment, and implant loosening. The mean duration of follow-up after the fracture repair was 39 months (range 12-47). All 25 fractures were united with a mean time of 12 weeks (range 8-20). At the last follow-up, the mean knee flexion was 111° (range 60°-130°), the mean KSS was 81.5 (range 50-100), and the mean WOMAC score was 30.2 (range 5-55). Four (16%) of the 25 patients developed malalignment according to Rorabeck and Taylor criteria, but all patients had a knee flexion of more than 90°. Coronal and sagittal alignments of femoral component and lower limb alignment did not differ significantly between before and after the fracture repair. Complications included the loosening or breakage of distal interlocking screws in three patients. No deep infection or prosthesis loosening was detected at the last follow-up. Surgical treatment of periprosthetic supracondylar femoral fractures following TKA with long retrograde intramedullary nailing resulted in high union rates and encouraging functional outcomes.

A three-dimensional architecture of vertically aligned multilayer graphene facilitates heat dissipation across joint solid surfaces

NASA Astrophysics Data System (ADS)

Liang, Qizhen; Yao, Xuxia; Wang, Wei; Wong, C. P.

2012-02-01

Low operation temperature and efficient heat dissipation are important for device life and speed in current electronic and photonic technologies. Being ultra-high thermally conductive, graphene is a promising material candidate for heat dissipation improvement in devices. In the application, graphene is expected to be vertically stacked between contact solid surfaces in order to facilitate efficient heat dissipation and reduced interfacial thermal resistance across contact solid surfaces. However, as an ultra-thin membrane-like material, graphene is susceptible to Van der Waals forces and usually tends to be recumbent on substrates. Thereby, direct growth of vertically aligned free-standing graphene on solid substrates in large scale is difficult and rarely available in current studies, bringing significant barriers in graphene's application as thermal conductive media between joint solid surfaces. In this work, a three-dimensional vertically aligned multi-layer graphene architecture is constructed between contacted Silicon/Silicon surfaces with pure Indium as a metallic medium. Significantly higher equivalent thermal conductivity and lower contact thermal resistance of vertically aligned multilayer graphene are obtained, compared with those of their recumbent counterpart. This finding provides knowledge of vertically aligned graphene architectures, which may not only facilitate current demanding thermal management but also promote graphene's widespread applications such as electrodes for energy storage devices, polymeric anisotropic conductive adhesives, etc.

[Three-dimensional vertically aligned CNTs coated by Ag nanoparticles for surface-enhanced Raman scattering].

PubMed

Zhang, Xiao-Lei; Zhang, Jie; Fan, Tuo; Ren, Wen-Jie; Lai, Chun-Hong

2014-09-01

In order to make surface-enhanced Raman scattering (SERS) substrates contained more "hot spots" in a three-dimensional (3D) focal volume, and can be adsorbed more probe molecules and metal nanoparticles, to obtain stronger Raman spectral signal, a new structure based on vertically aligned carbon nanotubes (CNTs) coated by Ag nanoparticles for surface Raman enhancement is presented. The vertically aligned CNTs are synthesized by chemical vapor deposition (CVD). A silver film is first deposited on the vertically aligned CNTs by magnetron sputtering. The samples are then annealed at different temperature to cause the different size silver nanoparticles to coat on the surface and sidewalls of vertically aligned CNTs. The result of scanning electron microscopy(SEM) shows that Ag nanoparticles are attached onto the sidewalls and tips of the vertically aligned CNTs, as the annealing temperature is different , pitch size, morphology and space between the silver nanoparticles is vary. Rhodamine 6G is served as the probe analyte. Raman spectrum measurement indicates that: the higher the concentration of R6G, the stronger the Raman intensity, but R6G concentration increase with the enhanced Raman intensity varies nonlinearly; when annealing temperature is 450 °C, the average size of silver nanoparticles is about 100 to 120 nm, while annealing temperature is 400 °C, the average size is about 70 nm, and the Raman intensity of 450 °C is superior to the annealing temperature that of 400 °C and 350 °C.

Post-injection Multiphase Flow Modeling and Risk Assessments for Subsurface CO2 Storage in Naturally Fractured Reservoirs

NASA Astrophysics Data System (ADS)

Jin, G.

2015-12-01

Subsurface storage of carbon dioxide in geological formations is widely regarded as a promising tool for reducing global atmospheric CO2 emissions. Successful geologic storage for sequestrated carbon dioxides must prove to be safe by means of risk assessments including post-injection analysis of injected CO2 plumes. Because fractured reservoirs exhibit a higher degree of heterogeneity, it is imperative to conduct such simulation studies in order to reliably predict the geometric evolution of plumes and risk assessment of post CO2injection. The research has addressed the pressure footprint of CO2 plumes through the development of new techniques which combine discrete fracture network and stochastic continuum modeling of multiphase flow in fractured geologic formations. A subsequent permeability tensor map in 3-D, derived from our preciously developed method, can accurately describe the heterogeneity of fracture reservoirs. A comprehensive workflow integrating the fracture permeability characterization and multiphase flow modeling has been developed to simulate the CO2plume migration and risk assessments. A simulated fractured reservoir model based on high-priority geological carbon sinks in central Alabama has been employed for preliminary study. Discrete fracture networks were generated with an NE-oriented regional fracture set and orthogonal NW-fractures. Fracture permeability characterization revealed high permeability heterogeneity with an order of magnitude of up to three. A multiphase flow model composed of supercritical CO2 and saline water was then applied to predict CO2 plume volume, geometry, pressure footprint, and containment during and post injection. Injection simulation reveals significant permeability anisotropy that favors development of northeast-elongate CO2 plumes, which are aligned with systematic fractures. The diffusive spreading front of the CO2 plume shows strong viscous fingering effects. Post-injection simulation indicates significant upward lateral spreading of CO2 resulting in accumulation of CO2 directly under the seal unit because of its buoyancy and strata-bound vertical fractures. Risk assessment shows that lateral movement of CO2 along interconnected fractures requires widespread seals with high integrity to confine the injected CO2.

Allgöwer-Donati Versus Vertical Mattress Suture Technique Impact on Perfusion in Ankle Fracture Surgery: A Randomized Clinical Trial Using Intraoperative Angiography.

PubMed

Shannon, Steven F; Houdek, Matthew T; Wyles, Cody C; Yuan, Brandon J; Cross, William W; Cass, Joseph R; Sems, Stephen A

2017-02-01

The purpose of this study was to evaluate which primary wound closure technique for ankle fractures affords the most robust perfusion as measured by laser-assisted indocyanine green angiography: Allgöwer-Donati or vertical mattress. Prospective, randomized. Level 1 Academic Trauma Center. Thirty patients undergoing open reduction internal fixation for ankle fractures were prospectively randomized to Allgöwer-Donati (n = 15) or vertical mattress (n = 15) closure. Demographics were similar for both cohorts with respect to age, sex, body mass index, surgical timing, and OTA/AO fracture classification. Skin perfusion (mean incision perfusion and mean perfusion impairment) was quantified in fluorescence units with laser-assisted indocyanine green angiography along the lateral incision as well as anterior and posterior to the incision at 30 separate locations. Minimum follow-up was 3 months with a mean follow-up 4.7 months. Allgöwer-Donati enabled superior perfusion compared with the vertical mattress suture technique. Mean incision perfusion for Allgöwer-Donati was 51 (SD = 13) and for vertical mattress was 28 (SD = 10, P < 0.0001). Mean perfusion impairment was less in the Allgöwer-Donati cohort (12.8, SD = 9) compared with that in the vertical mattress cohort (23.4, SD = 14; P = 0.03). One patient in each cohort experienced a wound complication. The Allgöwer-Donati suture technique offers improved incision perfusion compared with vertical mattress closure after open reduction internal fixation of ankle fractures. Theoretically, this may enhance soft tissue healing and decrease the risk of wound complications. Surgeons may take this into consideration when deciding closure techniques for ankle fractures. Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Effect of microstructural anisotropy on fracture toughness of hot rolled 13Cr ODS steel - The role of primary and secondary cracking

NASA Astrophysics Data System (ADS)

Das, A.; Viehrig, H. W.; Bergner, F.; Heintze, C.; Altstadt, E.; Hoffmann, J.

2017-08-01

ODS steels have been known to exhibit anisotropic fracture behaviour and form secondary cracks. In this work, the factors responsible for the anisotropic fracture behaviour have been investigated using scanning electron microscopy and electron backscatter microscopy. Fracture toughness of hot rolled 13Cr ODS steel was determined using unloading compliance method for L-T and T-L orientations at various temperatures. L-T orientation had higher fracture toughness than T-L orientation and also contained more pronounced secondary cracking. Secondary cracks appeared at lower loads than primary cracks in both orientations. Primary crack propagation was found to be preferentially through fine grains in a bimodal microstructure. Grains were aligned and elongated the most towards rolling direction followed by T and S directions resulting in fracture anisotropy. Crystallographic texture and preferential alignment of Ti enriched particles parallel to rolling direction also contributed towards fracture anisotropy.

Plasmonic Properties of Vertically Aligned Nanowire Arrays

DTIC Science & Technology

2012-01-01

scattering (SERS) applications. In this investigation, two types of vertical NW arrays were studied; those of ZnO NWs grown on nanosphere lithography...plasmonic nanowires to investigate this SERS effect. Here we used two types of vertical NWs, ZnO NWs, and Si NWs, respectively, to investigate SERS...successfully grow vertically aligned ZnO nanowires by the well-known VLS process. In this way, the ZnO NWs can be arranged in a repeatable hexagonal pattern

Highly efficient growth of vertically aligned carbon nanotubes on Fe-Ni based metal alloy foils for supercapacitors

NASA Astrophysics Data System (ADS)

Amalina Raja Seman, Raja Noor; Asyadi Azam, Mohd; Ambri Mohamed, Mohd

2016-12-01

Supercapacitors are highly promising energy devices with superior charge storage performance and a long lifecycle. Construction of the supercapacitor cell, especially electrode fabrication, is critical to ensure good performance in applications. This work demonstrates direct growth of vertically aligned carbon nanotubes (CNTs) on Fe-Ni based metal alloy foils, namely SUS 310S, Inconel 600 and YEF 50, and their use in symmetric vertically aligned CNT supercapacitor electrodes. Alumina and cobalt thin film catalysts were deposited onto the foils, and then CNT growth was performed using alcohol catalytic chemical vapour deposition. By this method, vertically aligned CNTs were successfully grown and used directly as a binder-free supercapacitor electrode to deliver excellent electrochemical performance. The device showed relatively good specific capacitance, a superior rate capability and excellent cycle stability, maintaining about 96% capacitance up to 1000 cycles.

Purification process for vertically aligned carbon nanofibers

NASA Technical Reports Server (NTRS)

Nguyen, Cattien V.; Delziet, Lance; Matthews, Kristopher; Chen, Bin; Meyyappan, M.

2003-01-01

Individual, free-standing, vertically aligned multiwall carbon nanotubes or nanofibers are ideal for sensor and electrode applications. Our plasma-enhanced chemical vapor deposition techniques for producing free-standing and vertically aligned carbon nanofibers use catalyst particles at the tip of the fiber. Here we present a simple purification process for the removal of iron catalyst particles at the tip of vertically aligned carbon nanofibers derived by plasma-enhanced chemical vapor deposition. The first step involves thermal oxidation in air, at temperatures of 200-400 degrees C, resulting in the physical swelling of the iron particles from the formation of iron oxide. Subsequently, the complete removal of the iron oxide particles is achieved with diluted acid (12% HCl). The purification process appears to be very efficient at removing all of the iron catalyst particles. Electron microscopy images and Raman spectroscopy data indicate that the purification process does not damage the graphitic structure of the nanotubes.

Angular dependent anisotropic terahertz response of vertically aligned multi-walled carbon nanotube arrays with spatial dispersion.

PubMed

Zhou, Yixuan; E, Yiwen; Xu, Xinlong; Li, Weilong; Wang, Huan; Zhu, Lipeng; Bai, Jintao; Ren, Zhaoyu; Wang, Li

2016-12-14

Spatial dispersion effect of aligned carbon nanotubes (CNTs) in the terahertz (THz) region has significance for both theoretical and applied consideration due to the unique intrinsically anisotropic physical properties of CNTs. Herein, we report the angular dependent reflection of p-polarized THz wave from vertically aligned multi-walled CNT arrays in both experiment and theory. The spectra indicate that the reflection depends on the film thickness of vertically aligned CNTs, the incident angle, and the frequency. The calculation model is based on the spatial dispersion effect of aligned CNTs and performed with effective impedance method and the Maxwell-Garnett approximation. The results fit well with the experiment when the thickness of CNT film is thin, which reveals a coherent superposition mechanism of the CNT surface reflection and CNTs/Si interface reflection. For thick CNT films, the CNTs/Si interface response determines the reflection at small incident angles, while the CNTs surface effect dominates at large incident angles. This work investigates the spatial dispersion effect of vertically aligned CNT arrays in the THz region, and paves a way for potential anisotropic THz applications based on CNTs with oblique incidence requirements.

Angular dependent anisotropic terahertz response of vertically aligned multi-walled carbon nanotube arrays with spatial dispersion

NASA Astrophysics Data System (ADS)

Zhou, Yixuan; Yiwen, E.; Xu, Xinlong; Li, Weilong; Wang, Huan; Zhu, Lipeng; Bai, Jintao; Ren, Zhaoyu; Wang, Li

2016-12-01

Spatial dispersion effect of aligned carbon nanotubes (CNTs) in the terahertz (THz) region has significance for both theoretical and applied consideration due to the unique intrinsically anisotropic physical properties of CNTs. Herein, we report the angular dependent reflection of p-polarized THz wave from vertically aligned multi-walled CNT arrays in both experiment and theory. The spectra indicate that the reflection depends on the film thickness of vertically aligned CNTs, the incident angle, and the frequency. The calculation model is based on the spatial dispersion effect of aligned CNTs and performed with effective impedance method and the Maxwell-Garnett approximation. The results fit well with the experiment when the thickness of CNT film is thin, which reveals a coherent superposition mechanism of the CNT surface reflection and CNTs/Si interface reflection. For thick CNT films, the CNTs/Si interface response determines the reflection at small incident angles, while the CNTs surface effect dominates at large incident angles. This work investigates the spatial dispersion effect of vertically aligned CNT arrays in the THz region, and paves a way for potential anisotropic THz applications based on CNTs with oblique incidence requirements.

A Computational/Experimental Platform for Investigating Three-Dimensional Puzzle Solving of Comminuted Articular Fractures

PubMed Central

Thomas, Thaddeus P.; Anderson, Donald D.; Willis, Andrew R.; Liu, Pengcheng; Frank, Matthew C.; Marsh, J. Lawrence; Brown, Thomas D.

2011-01-01

Reconstructing highly comminuted articular fractures poses a difficult surgical challenge, akin to solving a complicated three-dimensional (3D) puzzle. Pre-operative planning using CT is critically important, given the desirability of less invasive surgical approaches. The goal of this work is to advance 3D puzzle solving methods toward use as a pre-operative tool for reconstructing these complex fractures. Methodology for generating typical fragmentation/dispersal patterns was developed. Five identical replicas of human distal tibia anatomy, were machined from blocks of high-density polyetherurethane foam (bone fragmentation surrogate), and were fractured using an instrumented drop tower. Pre- and post-fracture geometries were obtained using laser scans and CT. A semi-automatic virtual reconstruction computer program aligned fragment native (non-fracture) surfaces to a pre-fracture template. The tibias were precisely reconstructed with alignment accuracies ranging from 0.03-0.4mm. This novel technology has potential to significantly enhance surgical techniques for reconstructing comminuted intra-articular fractures, as illustrated for a representative clinical case. PMID:20924863

Structure and Characterization of Vertically Aligned Single-Walled Carbon Nanotube Bundles

DOE PAGES

Márquez, Francisco; López, Vicente; Morant, Carmen; ...

2010-01-01

Arrmore » ays of vertically aligned single-walled carbon nanotube bundles, SWCNTs, have been synthesized by simple alcohol catalytic chemical vapor deposition process, carried out at 800 ° C . The formed SWCNTs are organized in small groups perpendicularly aligned and attached to the substrate. These small bundles show a constant diameter of ca. 30 nm and are formed by the adhesion of no more than twenty individual SWCNTs perfectly aligned along their length.« less

Highly aligned vertical GaN nanowires using submonolayer metal catalysts

DOEpatents

Wang, George T [Albuquerque, NM; Li, Qiming [Albuquerque, NM; Creighton, J Randall [Albuquerque, NM

2010-06-29

A method for forming vertically oriented, crystallographically aligned nanowires (nanocolumns) using monolayer or submonolayer quantities of metal atoms to form uniformly sized metal islands that serve as catalysts for MOCVD growth of Group III nitride nanowires.

Esthetic enhancement of a traumatized anterior tooth with a combination of forced eruption and tooth alignment: a case report

PubMed Central

Kang, So-Hee; Jin, Myoung-Uk; Kim, Sung-Kyo

2016-01-01

Exposing sound structure of a subgingivally fractured tooth using orthodontic extrusion is considered to be a conservative way to re-establish biologic width without sacrificing esthetics or jeopardizing periodontal support of neighboring teeth. When a misaligned tooth is traumatically involved, a more comprehensive approach combining tooth extrusion and re-alignment may be necessary for a successful restorative outcome. This case report describes a successful esthetic management of a patient with complicated crown-root fracture on the maxillary right central incisor and pre-existing malocclusion in the maxillary anterior region. Forced eruption along with re-alignment of teeth by orthodontic movement seems to allow re-positioning of the fracture line to a favorable position and correction of crowding, providing a better esthetic result. PMID:27508163

Fracture patterns at lava-ice contacts on Kokostick Butte, OR, and Mazama Ridge, Mount Rainier, WA: Implications for flow emplacement and cooling histories

NASA Astrophysics Data System (ADS)

Lodge, Robert W. D.; Lescinsky, David T.

2009-09-01

Cooling lava commonly develop polygonal joints that form equant hexagonal columns. Such fractures are formed by thermal contraction resulting in an isotropic tensional stress regime. However, certain linear cooling fracture patterns observed at some lava-ice contacts do not appear to fit the model for formation of cooling fractures and columns because of their preferred orientations. These fracture types include sheet-like (ladder-like rectangular fracture pattern), intermediate (pseudo-aligned individual column-bounding fractures), and pseudopillow (straight to arcuate fractures with perpendicular secondary fractures caused by water infiltration) fractures that form the edges of multiple columns along a single linear fracture. Despite the relatively common occurrence of these types of fractures at lava-ice contacts, their significance and mode of formation have not been fully explored. This study investigates the stress regimes responsible for producing these unique fractures and their significance for interpreting cooling histories at lava-ice contacts. Data was collected at Kokostick Butte dacite flow at South Sister, OR, and Mazama Ridge andesite flow at Mount Rainier, WA. Both of these lava flows have been interpreted as being emplaced into contact with ice and linear fracture types have been observed on their ice-contacted margins. Two different mechanisms are proposed for the formation of linear fracture networks. One possible mechanism for the formation of linear fracture patterns is marginal bulging. Melting of confining ice walls will create voids into which flowing lava can deform resulting in margin-parallel tension causing margin-perpendicular fractures. If viewed from the ice-wall, these fractures would be steeply dipping, linear fractures. Another possible mechanism for the formation of linear fracture types is gravitational settling. Pure shear during compression and settling can result in a tensional environment with similar consequences as marginal inflation. In addition to this, horizontally propagating cooling fractures will be directly influenced by viscous strain caused by the settling of the flow. This would cause preferential opening of fractures horizontally, resulting in vertically oriented fractures. It is important to note that the proposed model for the formation of linear fractures is dependent on contact with and confinement by glacial ice. The influence of flow or movement on cooling fracture patterns has not been extensively discussed in previous modeling of cooling fractures. Rapid cooling of lava by the interaction with water and ice will increase the ability to the capture and preserve perturbations in the stress regime.

Ipsilateral femoral shaft and vertical patella fracture: a case report

PubMed Central

Ozkan, Korhan; Eceviz, Engin; Sahin, Adem; Ugutmen, Ender

2009-01-01

Introduction A femoral shaft fracture with an ipsilateral patella fracture has been, to our knowledge, given only cursory attention in English-speaking literature. Case presentation A 15 year old male patient had hitten by a car to his motorcycle came to emergency room and he had been operated for his femoral shaft freacture and vertical patellar fracture which was iniatally missed. Conclusion To us it is vital to obtain CT scan of the patient’s knee if there is an ipsilateral femoral fracture with an ipsilateral knee effusion and a punction which reveals hematoma even in the absence of a fracture line seen in AP and lateral projections. PMID:19829933

The effects of window shape and reticle presence on performance in a vertical alignment task

NASA Technical Reports Server (NTRS)

Rosenberg, Erika L.; Haines, Richard F.; Jordan, Kevin

1989-01-01

This study was conducted to evaluate the effect of selected interior work-station orientational cuing upon the ability to align a target image with local vertical in the frontal plane. Angular error from gravitational vertical in an alignment task was measured for 20 observers viewing through two window shapes (square, round), two initial orientations of a computer-generated space shuttle image, and the presence or absence of a stabilized optical alignment reticle. In terms of overall accuracy, it was found that observer error was significantly smaller for the square window and reticle-present conditions than for the round window and reticle-absent conditions. Response bias data reflected an overall tendency to undershoot and greater variability of response in the round window/no reticle condition. These results suggest that environmental cuing information, such as that provided by square window frames and alignment reticles, may aid in subjective orientation and increase accuracy of response in a Space Station proximity operations alignment task.

Large-scale fabrication of vertically aligned ZnO nanowire arrays

DOEpatents

Wang, Zhong Lin; Hu, Youfan; Zhang, Yan; Xu, Chen; Zhu, Guang

2014-09-09

A generator includes a substrate, a first electrode layer, a dense plurality of vertically-aligned piezoelectric elongated nanostructures, an insulating layer and a second electrode layer. The substrate has a top surface and the first electrode layer is disposed on the top surface of the substrate. The dense plurality of vertically-aligned piezoelectric elongated nanostructures extends from the first electrode layer. Each of the nanostructures has a top end. The insulating layer is disposed on the top ends of the nanostructures. The second electrode layer is disposed on the non-conductive layer and is spaced apart from the nanostructures.

Vertical Structural Variation and Their Development of the Sanukayama Rhyolite Lava in Kozushima Island, Japan

NASA Astrophysics Data System (ADS)

Furukawa, K.; Uno, K.; Kanamaru, T.; Nakai, K.

2017-12-01

We revealed structural development of the Pleistocene Sanukayama rhyolite lava of Kozushima Island, Japan. The good exposure, with about 130 m thick, provides valuable opportunity to understand the vertical structural variation. This exposure corresponds to the upper half of the lava. The paleomagnetic results show that the lava emplaced in subaerial condition at least in the exposed part. The vertical lithofacies are divided into the pumiceous (25-40 m thick), obsidian (40-60 m), spherulitic (30-50 m) layers from top to base. The pumiceous layer is characterized by massive foliated pumice. The foliation dips are gradually changed from gentle (10-30°) in lower part to steep (around 90°) in upper part. This shows the balloon-like morphology. The massive pumiceous layer would be generated from late stage diapiric inflation of the lava (Fink and Manley, 1987). The obsidian layer is composed of massive and welded-brecciated parts. The ductile-deformed light-colored veins, with a few mm thick, are frequently developed. In the microscopic observation, the veins are composed of broken crystals and obsidian clasts indicating fracturing of the lava followed by ductile deformation such as the RFH process (Tuffen et al., 2003). In this layer, extensive vesiculation and microlite development must have been prevented by higher load pressure and faster cooling, respectively. Consequently, they resulted in formation of the obsidian. The spherulitic layer is characterized by development of the ductile-deformed flow banding. The microscopic observation shows that the bands are formed by the spherulite trail. Furthermore, the microlites are aligned within the spherulites. In the heat-retained inner part of the lava, microlites would be developed around the healed fractures. The microlites acted as nucleation site of spherulite. In transition layer between obsidian and spherulitic layers (<10 m thick), the fragments of spherulitic rhyolite are entrained within the obsidian layer. This would be caused by high flow-induced shear arising from their rheological contrast. We showed the complicated structure of the Sanukayama rhyolite lava, especially for varied crystal occurrences. The variation is considered to be caused by specific phenomena of high-viscous magma such as sluggish atomic mobility and lava fracturing.

Palaeoseismological evidence for the 1570 Ferrara earthquake, Italy

NASA Astrophysics Data System (ADS)

Caputo, R.; Poli, M. E.; Minarelli, L.; Rapti, D.; Sboras, S.; Stefani, M.; Zanferrari, A.

2016-06-01

In May 2012, two earthquakes (Mw 6.1 and 5.9) affected the Po Plain, Italy. The strongest shock produced extensive secondary effects associated with liquefaction phenomena. Few weeks after the earthquakes, an exploratory trench was excavated across a levee of the palaeo-Reno reach, where a system of aligned ground ruptures was observed. The investigated site well preserves the geomorphic expression of a fluvial body that mainly formed in the fifteenth to sixteenth centuries as historical sources and radiometric data testify. In the trench several features pinpointed the occurrence of past liquefaction events: (i) dikes filled with overpressured injected sand and associated with vertical displacements have no correspondence with the fractures mapped at the surface; (ii) thick dikes are buried by the plowed level or even by fluvial deposits; (iii) although some of the 2012 ground fractures characterized by vertical displacement and opening occurred in correspondence of thick dikes observed in the trench, sand and water ejection did not occur; (iv) some seismites (load casts) were observed in the trench well above the 2012 water level. The results strongly suggest that shaking has locally occurred in the past producing a sufficient ground motion capable of triggering liquefaction phenomena prior to, and likely stronger than, the May 2012 earthquake. Historical seismicity documents three seismic events that might have been able to generate liquefaction in the broader investigated area. Based on the analysis of their macroseismic fields, the 17 November 1570 Ferrara earthquake is the most likely causative event of the observed palaeoliquefactions.

Direction of balance and perception of the upright are perceptually dissociable

PubMed Central

Panic, Alexander Sacha; DiZio, Paul; Lackner, James R.

2015-01-01

We examined whether the direction of balance rather than an otolith reference determines the perceived upright. Participants seated in a device that rotated around the roll axis used a joystick to control its motion. The direction of balance of the device, the location where it would not be accelerated to either side, could be offset from the gravitational vertical, a technique introduced by Riccio, Martin, and Stoffregen (J Exp Psychol Hum Percept Perform 18: 624–644, 1992). Participants used the joystick to align themselves in different trials with the gravitational vertical, the direction of balance, the upright, or the direction that minimized oscillations. They pressed the joystick trigger whenever they thought they were at the instructed orientation. Achieved angles for the “align with gravity” and “align with the upright” conditions were not different from each other and were significantly displaced past the gravitational vertical opposite from the direction of balance. Mean indicated angles for align with gravity and align with the upright coincided with the gravitational vertical. Both mean achieved and indicated angles for the “minimize oscillations” and “align with the direction of balance” conditions were significantly deviated toward the gravitational vertical. Three control experiments requiring self-settings to instructed orientations only, perceptual judgments only, and perceptual judgments during passive exposure to dynamic roll profiles confirmed that perception of the upright is determined by gravity, not by the direction of balance. PMID:25761954

Pelvic crescent fractures: variations in injury mechanism and radiographic pattern.

PubMed

Gehlert, Rick J; Xing, Zhiqing; DeCoster, Thomas A

2014-01-01

Pelvic crescent fracture, also known as sacroiliac fracture-dislocation, is traditionally considered as a lateral compression injury and a vertically stable injury. Thirty consecutive cases were analyzed and it was found that 63% of cases were caused by lateral compression (LC), 27% by anteroposterior compression (APC), and 10% by vertical shear (VS). APC and VS injuries cause significant displacement of the anterior iliac fragment, but 21% of LC injury cases showed minimal displacement and were treated successfully with nonoperative treatment. Different injury mechanisms also produce different types of pelvic instability. More important, different injury mechanisms produce distinct radiographic fracture patterns regarding the obliquity of the fracture line and fracture surface. These differences in the fracture pattern will influence the decision of internal fixation options. Therefore, treatment of pelvic crescent fractures should be based on individual analysis of injury mechanism and radiographic fracture pattern.

Induced Seismicity at the UK "Hot Dry Rock" Test Site for Geothermal Energy Production

NASA Astrophysics Data System (ADS)

Li, Xun; Main, Ian; Jupe, Andrew

2018-03-01

In enhanced geothermal systems (EGS), fluid is injected at high pressure in order to stimulate fracturing and/or fluid flow through otherwise relatively impermeable underlying hot rocks to generate power and/or heat. The stimulation induces micro-earthquakes whose precise triggering mechanism and relationship to new and pre-existing fracture networks are still the subject of some debate. Here we analyse the dataset for induced micro-earthquakes at the UK "hot dry rock" experimental geothermal site (Rosemanowes, Cornwall). We quantify the evolution of several metrics used to characterise induced seismicity, including the seismic strain partition factor and the "seismogenic index". The results show a low strain partition factor of 0.01% and a low seismogenenic index indicating that aseismic processes dominate. We also analyse the spatio-temporal distribution of hypocentres, using simple models for the evolution of hydraulic diffusivity by (a) isotropic and (b) anisotropic pore-pressure relaxation. The principal axes of the diffusivity or permeability tensor inferred from the spatial distribution of earthquake foci are aligned parallel to the present-day stress field, although the maximum permeability is vertical, whereas the maximum principal stress is horizontal. Our results are consistent with a triggering mechanism that involves (a) seismic shear slip along optimally-oriented pre-existing fractures, (b) a large component of aseismic slip with creep (c) activation of tensile fractures as hydraulic conduits created by both the present-day stress field and by the induced shear slip, both exploiting pre-existing joint sets exposed in borehole data.

Evaluation of an Image-Based Tool to Examine the Effect of Fracture Alignment and Joint Congruency on Outcomes after Wrist Fracture.

PubMed

Lalone, Emily A; Grewal, Ruby; King, Graham W; MacDermid, Joy C

2015-01-01

Some mal-alignment of the wrist occurs in up to 71% of patients following a distal radius fracture. A multiple case study was used to provide proof of principle of an image-based technique to investigate the evolution and impact of post-traumatic joint changes at the distal radioulnar joint. Participants who had a unilateral distal radius fracture who previously participated in a prospective study were recruited from a single tertiary hand center. Long term follow-up measures of pain, disability, range of motion and radiographic alignment were obtained and compared to joint congruency measures. The inter-bone distance, a measure of joint congruency was quantified from reconstructed CT bone models of the distal radius and ulna and the clinical outcome was quantified using the patient rated wrist evaluation. In all four cases, acceptable post-reduction alignment and minimal pain/disability at 1-year suggested good clinical outcomes. However, 10 years following injury, 3 out of 4 patients had radiographic signs of degenerative changes occurring in their injured wrist (distal radioulnar joint/radio-carpal joint). Proximity maps displaying inter-bone distances showed asymmetrical congruency between wrists in these three patients. The 10-year PRWE (patient rated wrist evaluation) varied from 4 to 60, with 3 reporting minimal pain/disability and one experiencing high pain/disability. These illustrative cases demonstrate long-term joint damage post-fracture is common and occurs despite positive short-term clinical outcomes. Imaging and functional outcomes are not necessarily correlated. A novel congruency measure provides an indicator of the overall impact of joint mal-alignment that can be used to determine predictors of post-traumatic arthritis and is viable for clinical or large cohort studies.

Separate Vertical Wirings for the Extra-articular Fractures of the Distal Pole of the Patella.

PubMed

Kim, Young Mo; Yang, Jun Young; Kim, Kyung Cheon; Kang, Chan; Joo, Yong Bum; Lee, Woo Yong; Hwang, Jung Mo

2011-12-01

To evaluate the usefulness of separate vertical wirings for extra-articular fracture of distal pole of patella. We have analyzed the clinical results of 18 cases that underwent separate vertical wirings for extra-articular fracture of distal pole of the patella from March 2005 to March 2010, by using the range of motion and Bostman score. Occurrence of complication was also evaluated. Additionally, by taking simple radiographs, the correlation between the postoperative degree of anterior transposition of bone fragment and the time of bone fusion, preoperative length of bone fragment, and occurrence of comminuted fracture were investigated. It took an average of 13.8 weeks for radiological bone union after separate vertical wiring fixation. Flexion contracture was an average of 0.8 degrees and further flexion was an average of 127.6°, and Bostman score was an average of 27.5 points (excellent in 12 cases, and good in 6 cases). On the first postoperative year, average flexion contracture was 0.6 degrees and further flexion was an average of 136.3°, which exhibited increased joint motion and recovery to normal range of motion, and Bostman score was an average of 28.7 points (excellent in 16 cases, and good in 2 cases). There was no statistically significant difference between the preoperative bone fragment length and presence of comminution, and degree of anterior transposition of bone fragment after fracture union on simple radiograph (p=0.175, p=0.146). We were able to obtain satisfactory clinical results, while preserving the bone fragment by separate vertical wiring fixation for extra-articular fracture of distal pole of patella. Moreover, the method is easy to perform, which is also considered as a useful surgical method for extra-articular fracture of distal pole of patella.

Periodontal healing after bonding treatment of vertical root fracture.

PubMed

Sugaya, T; Kawanami, M; Noguchi, H; Kato, H; Masaka, N

2001-08-01

Vertical root fractures lead to advanced periodontal breakdown with deep periodontal pockets and vertical bone defects. The purpose of this study is to evaluate clinically the periodontal healing of root fracture treatment using adhesive resin cement. In 22 patients, 23 teeth with vertical root fractures were treated with 4-META/MMA-TBB resin cement. Eleven fractured roots were bonded through the root canal (group A) and 12 fractured roots were bonded extra-orally and replanted (group B). All teeth were then restored with full cast crowns (n=20) or coping (n=3). Mean probing depth was 6.6 mm at pre-treatment and 4.4 mm 6 months after the treatment in group A, and 7.4 mm and 4.6 mm, respectively, in group B. Bleeding scores were 100% at pre-treatment and 36.4% after 6 months in group A and 91.7% and 8.3%, respectively in group B. Radiographic bone level was 56.8% at pretreatment and 59.1% after 6 months in group A, and 18.8% and 29.2%, respectively, in group B. Two roots of group A and three roots of group B were extracted due to refracture, deterioration of periodontal inflammation, mobility, and luxation. The remaining roots (n=18) presented no discomfort to the patients and there was no deterioration of periodontal conditions over a mean period of 33 months (range 14-74 months) in group A and over a mean period of 22 months (range 6-48 months) in group B. There was no ankylosed teeth nor was any root resorption detected. The results suggested that the treatment of vertical root fracture using 4-META/MMA-TBB resin has good prognostic possibilities.

Why Gas Hydrate Occurrenced Over Topographic Highs in Shenhu Area Northern South China Sea？

NASA Astrophysics Data System (ADS)

Liao, J.

2015-12-01

Methane gas hydrate has been drilled by China Geological Survey in shenhu area northern south china sea in 2007 .Shenhu area is located in the middle-lower continental slope and 17 submarine canyons are incised into the shelf,gas hydrtae was observed in boreholes over topographic highs,but origin of the hydrate is controversial.Accumulation of gas hydrate is depending on temperature-pressure field and supply quantities of methane and some other factors,in the same depth of the shallow sediments there is the same press,so temperature field and supply quantities of methane become the most important factors.Lachenbruch(1968) calculated the topographic disturbance to geothermal gradients,in shenhu area consistent local variations were observed, notably low heat flow values over prominent topographic highs and high heat flow values over the flanks of the topographic highs. At some localities over a horizontal distance of 2.5 km, heat flow increased by as much as 50%, from typical values of 65 to 100 mW/m2 .Some vertical fractures were observed beneath topographic highs in previous studies.Based on the profile across borehole SH7,we designed four experiments:A,uniform distribution of heat flux with no vertical fractures；B,Uniform distribution of heat flux with vertical fractures beneath geographic highs;C,uneven distribution of heat flux with no vertical fractures;D,uneven distribution of heat flux with vertical fractures beneath geographic highs.According to previous studies,we restored Palaeobathymetry,abundance of organic matters, sandstone-madstone ratio ,porosity and permeability of each,and parameters of vertical fractures.The result of experiment D shows the similar distribution characteristic with the drilling result,so We believe that low heat flux and Vertical fractures are the most important factors . This work was supported by the National Science Foundation of China(grant no. 41406080).

Tuning vertical alignment and field emission properties of multi-walled carbon nanotube bundles

NASA Astrophysics Data System (ADS)

Sreekanth, M.; Ghosh, S.; Srivastava, P.

2018-01-01

We report the growth of vertically aligned carbon nanotube bundles on Si substrate by thermal chemical vapor deposition technique. Vertical alignment was achieved without any carrier gas or lithography-assisted deposition. Growth has been carried out at 850 °C for different quantities of solution of xylene and ferrocene ranging from 2.25 to 3.00 ml in steps of 0.25 ml at a fixed concentration of 0.02 gm (ferrocene) per ml. To understand the growth mechanism, deposition was carried out for different concentrations of the solution by changing only the ferrocene quantity, ranging from 0.01 to 0.03 gm/ml. A tunable vertical alignment of multi-walled carbon nanotubes (CNTs) has been achieved by this process and examined by scanning and transmission electron microscopic techniques. Micro-crystalline structural analysis has been done using Raman spectroscopy. A systematic variation in field emission (FE) current density has been observed. The highest FE current density is seen for the film grown with 0.02 gm/ml concentration, which is attributed to the better alignment of CNTs, less structural disorder and less entanglement of CNTs on the surface. The alignment of CNTs has been qualitatively understood on the basis of self-assembled catalytic particles.

The Radiator-Enhanced Geothermal System

NASA Astrophysics Data System (ADS)

Hilpert, M.; Marsh, B. D.; Geiser, P.

2015-12-01

Standard Enhanced Geothermal Systems (EGS) have repeatedly been hobbled by the inability of rock to conductively transfer heat at rates sufficient to re-supply heat extracted convectively via artificially made fracture systems. At the root of this imbalance is the basic magnitude of thermal diffusivity for most rocks, which severely hampers heat flow once the cooled halos about fractures reach ~0.1 m or greater. This inefficiency is exacerbated by the standard EGS design of mainly horizontally constructed fracture systems with inflow and outflow access at the margins of the fracture network. We introduced an alternative system whereby the heat exchanger mimics a conventional radiator in an internal combustion engine, which we call a Radiator-EGS (i.e., RAD-EGS). The heat exchanger is built vertically with cool water entering the base and hot water extracted at the top. The RAD-EGS itself consists of a family of vertical vanes produced through sequential horizontal drilling and permeability stimulation through propellant fracking. The manufactured fracture zones share the orientation of the natural transmissive fracture system. As below about 700 m, S1 is vertical and the average strike of transmissive fractures parallels SHmax, creating vertical fractures that include S1 and SHmax requires drilling stacked laterals parallel to SHmax. The RAD-EGS is also based on the observation that the longevity of natural hydrothermal systems depends on thermal recharge through heat convection but not heat conduction. In this paper, we present numerical simulations that examine the effects of the depths of the injector and extraction wells, vane size, coolant flow rate, the natural crustal geothermal gradient, and natural regional background flow on geothermal energy extraction.

Waveform Tomography of Two-Dimensional Three-Component Seismic Data for HTI Anisotropic Media

NASA Astrophysics Data System (ADS)

Gao, Fengxia; Wang, Yanghua; Wang, Yun

2018-06-01

Reservoirs with vertically aligned fractures can be represented equivalently by horizontal transverse isotropy (HTI) media. But inverting for the anisotropic parameters of HTI media is a challenging inverse problem, because of difficulties inherent in a multiple parameter inversion. In this paper, when we invert for the anisotropic parameters, we consider for the first time the azimuthal rotation of a two-dimensional seismic survey line from the symmetry of HTI. The established wave equations for the HTI media with azimuthal rotation consist of nine elastic coefficients, expressed in terms of five modified Thomsen parameters. The latter are parallel to the Thomsen parameters for describing velocity characteristics of weak vertical transverse isotropy media. We analyze the sensitivity differences of the five modified Thomsen parameters from their radiation patterns, and attempt to balance the magnitude and sensitivity differences between the parameters through normalization and tuning factors which help to update the model parameters properly. We demonstrate an effective inversion strategy by inverting velocity parameters in the first stage and updates the five modified Thomsen parameters simultaneously in the second stage, for generating reliably reconstructed models.

Triangular osteosynthesis of vertically unstable sacrum fractures: a new concept allowing early weight-bearing.

PubMed

Schildhauer, T A; Josten, Ch; Muhr, G

2006-01-01

Presentation of a new triangular osteosynthesis technique that permits early weight-bearing in vertically unstable sacral fractures. : Retrospective evaluation of a consecutive series. Level I trauma center. Thirty-four patients, twenty-eight of whom were poly-traumatized, all with vertically unstable sacral fractures. This group included eight women and twenty-six men, with a mean age of thirty-five years. Average time between trauma and definite operation was thirteen days (range 0 to 28 days). All patients underwent triangular osteosynthesis using a combination of a vertical vertebro-pelvic distraction osteosynthesis (pedicle screw system) and a transverse fixation of the sacrum fracture with either iliosacral screws or trans-sacral plating. Immediate postoperative weight-bearing was permitted postoperatively. Nineteen patients were treated with early progressive weight-bearing and advanced to full weight-bearing, on average, after twenty-three days (range 8 to 70 days). Three of the thirty-four patients (9 percent) experienced loosening of hardware, including two patients (6 percent) who required secondary intervention because of loss of the original reduction. Further complications included one pulmonary embolism (3 percent), one iatrogenic nerve lesion (3 percent), one wound necrosis (3 percent), and two local infections (6 percent). Triangular osteosynthesis is a demanding procedure that can be performed on vertically unstable sacral fractures to allow early progressive weight-bearing with an acceptable complication rate.

Performance of an artificial neural network for vertical root fracture detection: an ex vivo study.

PubMed

Kositbowornchai, Suwadee; Plermkamon, Supattra; Tangkosol, Tawan

2013-04-01

To develop an artificial neural network for vertical root fracture detection. A probabilistic neural network design was used to clarify whether a tooth root was sound or had a vertical root fracture. Two hundred images (50 sound and 150 vertical root fractures) derived from digital radiography--used to train and test the artificial neural network--were divided into three groups according to the number of training and test data sets: 80/120,105/95 and 130/70, respectively. Either training or tested data were evaluated using grey-scale data per line passing through the root. These data were normalized to reduce the grey-scale variance and fed as input data of the neural network. The variance of function in recognition data was calculated between 0 and 1 to select the best performance of neural network. The performance of the neural network was evaluated using a diagnostic test. After testing data under several variances of function, we found the highest sensitivity (98%), specificity (90.5%) and accuracy (95.7%) occurred in Group three, for which the variance of function in recognition data was between 0.025 and 0.005. The neural network designed in this study has sufficient sensitivity, specificity and accuracy to be a model for vertical root fracture detection. © 2012 John Wiley & Sons A/S.

Virtual plate pre-bending for the long bone fracture based on axis pre-alignment.

PubMed

Liu, Bin; Luo, Xinjian; Huang, Rui; Wan, Chao; Zhang, Bingbing; Hu, Weihua; Yue, Zongge

2014-06-01

In this paper, a modeling and visualizing system for assisting surgeons in correctly registering for the closed fracture reduction surgery is presented. By using this system, the geometric parameters of the target fixation plate before the long bone fracture operation can be obtained. The main processing scheme consists of following steps: firstly (image data process), utilize the Curvelet transform to denoise the CT images of fracture part and then reconstruct the 3D models of the broken bones. Secondly (pre-alignment), extract the axial lines of the broken bones and spatially align them. Then drive the broken bone models to be pre-aligned. Thirdly (mesh segmentation), a method based on vertex normal feature is utilized to obtain the broken bone cross-sections mesh models. Fourthly (fine registration), the ICP (Iterative Closest Point) algorithm is used to register the cross-sections and the broken bone models are driven to achieve the fine registration posture. Lastly (plate fitting), an accurate NURBS surface fitting method is used to construct the virtual plate. The experiment proved that the obtained models of the pre-bended plates were closely bonded to the surface of the registered long bone models. Finally, the lengths, angles and other interested geometric parameters can be measured on the plate models. Copyright © 2014 Elsevier Ltd. All rights reserved.

Vertically Aligned Carbon Nanotubes at Different Temperatures by Spray Pyrolysis Techniques

NASA Astrophysics Data System (ADS)

Afre, Rakesh A.; Soga, T.; Jimbo, T.; Kumar, Mukul; Ando, Y.; Sharon, M.

Vertically aligned arrays of multi-walled carbon nanotubes (VACNTs) were grown by spray pyrolysis of turpentine oil and ferrocene mixture at temperatures higher than 700°C. Using this simple method, we report the successful growth of vertically aligned nanotubes of ~300μm length and diameter in the range of ?20-80nm on Si(100) substrate. The ferrocene acts as an in situ Fe catalyst precursor, forming the nano-sized metallic iron particles for formation of VACNTs on the Si substrate. The morphological characteristics of VACNTs are confirmed by SEM, TEM and Raman spectroscopy and growth mechanism is discussed in short.

Acoustic Monitoring of Gravity-Driven Controls on CaCO3 Precipitates in a Fracture

NASA Astrophysics Data System (ADS)

Xu, Z.; Sheets, J.; Zhang, L.; Kim, D.; Kneafsey, T. J.; Cole, D. R.; Jun, Y. S.; Pyrak-Nolte, L. J.

2017-12-01

Sealing fractures by mineral precipitation is an important process for improving caprock integrity in subsurface reservoirs. In this study, the ability to monitor precipitate distribution in fractures with buoyant fluids was examined. Fractures with uniform aperture distributions of 0.5, 1.0 and 2.0 mm were created from acrylic plates to enable direct imaging of precipitate formation over time. CaCO3 precipitation was induced in a fracture from invasion of 1M CaCl2 and 0.3M Na2CO3 solutions. During chemical invasion, a fracture plane was oriented either parallel or perpendicular to gravity. Acoustic (P) wave transmission ( 1 MHz) and optical imaging were used to monitor the sample prior to, during and after fluid injection. Complementary X-ray computed tomography was performed throughout the experiments on vertical fractures and post injection for the horizontal fractures. Precipitate particle sizes during formation were determined using SAXS and WAXS. In both horizontal and vertical fractures, the density contrast between the two solutions affected the spatial distribution of precipitation. In vertical fractures, the denser CaCl2 solution almost completely displaced the NaCO3 solution, causing strong localization of precipitates. However, in the horizontal fractures, flow stratification occurred in the 2 mm aperture fractures, with the less dense Na2CO3 flowing over the CaCl2 solution, resulting in a more even distribution of precipitates cross the fracture plane. P-wave amplitudes increased up to 8% and the arrival time decreased with precipitate accumulation in the horizontal fracture. This is consistent with a three-layered approach as the seismic impedance inside the fracture increases. The initial contact between the two was observed as a decrease in the P-wave amplitude. As precipitates accumulated, the amplitude recovered and increased, with greater increases observed along the mixing flow path. Fractures in the subsurface may seal differently depending on the orientation thus affecting the ability of a fracture to self-heal if oriented vertically. This work was supported by the Center for Nanoscale Controls on Geologic CO (NCGC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-AC02-05CH11231

[Distortion and vertical fracture of the root: effect produced by condenser design].

PubMed

Dang, D A; Walton, R E

1990-01-01

The incidence of vertical root fractures and the amount of root distortion created during lateral condensation of gutta-percha with either D11 spreaders or B-finger pluggers were evaluated in vitro. Fifty-five extracted human, single-rooted teeth were instrumented using the step-back flare technique. Ten teeth served as positive controls (obturation to the point of fracture) and five teeth as negative controls (prepared but not obtured). Strain gauges were attached to the root surfaces. In the experimental group, 20 teeth were obturated using a D11 spreader and 20 with a B-finger plugger. Recordings were made of root distortion (expansion) created during obturation. Then, after sectioning the teeth, root surfaces of obturated samples were examined for fractures under the scanning electron microscope. Only the more tapered spreader, the D11, produces vertical root fractures, although very few in number. Also, the D11 spreader caused greater root distortion than did the B-finger plugger.

Wave field features of shallow vertical discontinuity and their application in non-destructive detection

USGS Publications Warehouse

Liu, J.; Xia, J.; Luo, Y.; Chen, C.; Li, X.; Huang, Y.

2007-01-01

The geotechnical integrity of critical infrastructure can be seriously compromised by the presence of fractures or crevices. Non-destructive techniques to accurately detect fractures in critical infrastructure such as dams and highways could be of significant benefit to the geotechnical industry. This paper investigates the application of shallow seismic and georadar methods to the detection of a vertical discontinuity using numerical simulations. The objective is to address the kinematical analysis of a vertical discontinuity, determine the resulting wave field characteristics, and provide the basis for determining the existence of vertical discontinuities based on the recorded signals. Simulation results demonstrate that: (1) A reflection from a vertical discontinuity produces a hyperbolic feature on a seismic or georadar profile; (2) In order for a reflection from a vertical discontinuity to be produced, a reflecting horizon below the discontinuity must exist, the offset between source and receiver (x0) must be non-zero, on the same side of the vertical discontinuity; (3) The range of distances from the vertical discontinuity where a reflection event is observed is proportional to its length and to x0; (4) Should the vertical crevice (or fracture) pass through a reflecting horizon, dual hyperbolic features can be observed on the records, and this can be used as a determining factor that the vertical crevice passes through the interface; and (5) diffractions from the edges of the discontinuity can be recorded with relatively smaller amplitude than reflections and their ranges are not constrained by the length of discontinuity. If the length of discontinuity is short enough, diffractions are the dominant feature. Real-world examples show that the shallow seismic reflection method and the georadar method are capable of recording the hyperbolic feature, which can be interpreted as vertical discontinuity. Thus, these methods show some promise as effective non-destructive detection methods for locating vertical discontinuities (e.g., fractures or crevices) in infrastructure such as dams and highway pavement. ?? 2007 Elsevier B.V. All rights reserved.

Purely numerical approach for analyzing flow to a well intercepting a vertical fracture

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

Narasimhan, T.N.; Palen, W.A.

1979-03-01

A numerical method, based on an Integral Finite Difference approach, is presented to investigate wells intercepting fractures in general and vertical fractures in particular. Such features as finite conductivity, wellbore storage, damage, and fracture deformability and its influence as permeability are easily handled. The advantage of the numerical approach is that it is based on fewer assumptions than analytic solutions and hence has greater generality. Illustrative examples are given to validate the method against known solutions. New results are presenteed to demonstrate the applicability of the method to problems not apparently considered in the literature so far.

Fractographic Examination of the Vertical Stabilizer and Rudder from American Airlines Flight 587

NASA Technical Reports Server (NTRS)

Fox, Matthew R.; Schultheisz, Carl R.; Reeder, James R.

2005-01-01

The first major structural component failure of a composite part on a commercial airplane occurred during the crash of American Airlines Flight 587. The fractured composite lugs that attached the vertical stabilizer to the aircraft tail and the fractured composite honeycomb rudder were examined as part of the National Transportation Safety Board investigation of the accident. In this paper the composite fractures are described and the resulting clues to the failure events are discussed.

Investigation of Possible Wellbore Cement Failures During Hydraulic Fracturing Operations

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

Kim, Jihoon; Moridis, George

2014-11-01

We model and assess the possibility of shear failure, using the Mohr-Coulomb model ? along the vertical well by employing a rigorous coupled flow-geomechanic analysis. To this end, we vary the values of cohesion between the well casing and the surrounding cement to representing different quality levels of the cementing operation (low cohesion corresponds to low-quality cement and/or incomplete cementing). The simulation results show that there is very little fracturing when the cement is of high quality.. Conversely, incomplete cementing and/or weak cement can causes significant shear failure and the evolution of long fractures/cracks along the vertical well. Specifically, lowmore » cohesion between the well and cemented areas can cause significant shear failure along the well, but the same cohesion as the cemented zone does not cause shear failure. When the hydraulic fracturing pressure is high, low cohesion of the cement can causes fast propagation of shear failure and of the resulting fracture/crack, but a high-quality cement with no weak zones exhibits limited shear failure that is concentrated near the bottom of the vertical part of the well. Thus, high-quality cement and complete cementing along the vertical well appears to be the strongest protection against shear failure of the wellbore cement and, consequently, against contamination hazards to drinking water aquifers during hydraulic fracturing operations.« less

Conjugate fracture pairs in the Molina Member of the Wasatch Formation, Piceance basin, Colorado: Implications for fracture origins and hydrocarbon production/exploration

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

Lorenz, J.C.

1997-05-01

The sandstones of the Molina Member of the Wasatch Formation in the Piceance basin of northwestern Colorado contain a suite of fractures that have a conjugate-pair geometry. The fractures are vertical and intersect at an acute angle of between 20 and 40 degrees. Although direct evidence of shear is rare, the fracture surfaces commonly display small steps. The fracture geometries suggest that the maximum compressive stress during fracturing was in the plane of the acute angle of the conjugate fractures: the steps are interpreted as broken-face manifestations of very low angle en echelon fractures, formed within exceptionally narrow zones ofmore » incipient shear. In contrast to the highly anisotropic permeability enhancement created by subparallel vertical extension fractures in the underlying Mesaverde Formation, the conjugate pairs in the Molina sandstones should create a well connected and relatively isotropic mesh of fracture conductivity. Increases in stress magnitudes and anisotropy during production drawdown of reservoir pressures should cause shear offsets along the fractures, initially enhancing permeability.« less

Proton radiation effects on the optical properties of vertically aligned carbon nanotubes

NASA Astrophysics Data System (ADS)

Kuhnhenn, J.; Khavrus, V.; Leonhardt, A.; Eversheim, D.; Noll, C.; Hinderlich, S.; Dahl, A.

2017-11-01

This paper discusses proton-induced radiation effects in vertically aligned carbon nanotubes (VA-CNT). VACNTs exhibit extremely low optical reflectivity which makes them interesting candidates for use in spacecraft stray light suppression. Investigating their behavior in space environment is a precondition for the implementation on a satellite.

Vertically aligned carbon nanotubes as anode and air-cathode in single chamber microbial fuel cells

NASA Astrophysics Data System (ADS)

Amade, R.; Moreno, H. A.; Hussain, S.; Vila-Costa, M.; Bertran, E.

2016-10-01

Electrode optimization in microbial fuel cells is a key issue to improve the power output and cell performance. Vertically aligned carbon nanotubes (VACNTs) grown on low cost stainless-steel mesh present an attractive approach to increase the cell performance while avoiding the use of expensive Pt-based materials. In comparison with non-aligned carbon nanotubes (NACNTs), VACNTs increase the oxygen reduction reaction taking place at the cathode by a factor of two. In addition, vertical alignment also increases the power density up to 2.5 times with respect to NACNTs. VACNTs grown at the anode can further improve the cell performance by increasing the electrode surface area and thus the electron transfer between bacteria and the electrode. The maximum power density obtained using VACNTs was 14 mW/m2 and 160 mV output voltage.

Effects of alignment layer thickness on the pretilt angle of liquid crystals

NASA Astrophysics Data System (ADS)

Son, Jong-Ho; Zin, Wang-Cheol

2010-12-01

Mixture solutions of vertical- and planar-aligning polyimide precursors were coated on bare glass. The concentrations of the solutions were varied to control the thicknesses of the films. The resulting blend films were baked to induce imidization and then rubbed. The thicknesses (t) of the blend film and of the pure vertical-alignment film affected their surface energies; the pretilt angle can be fully controlled in the range 5.5°≤Θ0≤87° by adjusting t. The surface energy of pure planar-alignment layers was independent of t.

Fractographic logging for determination of pre-core and core-induced fractures: Nicholas Combs No. 7239 well, Hazard, Kentucky

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

Kulander, B.R.; Dean, S.L.; Barton, C.C.

1977-01-01

Methods results, and conclusions formulated during a prototype fractographic logging study of seventy-five feet of oriented Devonian shale core are summarized. The core analyzed is from the Nicholas Combs No. 7239 well located twelve miles due north of Hazard, Kentucky. The seventy-five foot core length was taken from a cored section lying between 2369.0 feet (subsea) and 2708.0 feet (subsea). Total core length is 339.0 feet. The core was extracted from the upper Devonian Ohio and Olentangy shale formations. Results indicate that there are few tectonic (pre-core) fractures within the studied core section. The region may nevertheless be cut atmore » core sample depth by well-defined vertical or inclined tectonic fractures that the vertically drilled test core didn't intersect. This is likely since surface Plateau systematic fractures in other Plateau areas are vertical to sub-vertical and seldom have a frequency of less than one major fracture per foot. The remarkable directional preference of set three fractures about strikes of N 40/sup 0/ E, N 10/sup 0/ W, N 45/sup 0/ W, suggests some incipient pre-core rock anisotropy or stored directional strain energy. If this situation exists, the anisotropy strike change or stored strain variance from N 40/sup 0/ E to N 45/sup 0/ W downcore remains an unanswered question. Tectonic features, indicating local and/or regional movement plans, are present on and within the tectonichorizontal fracture set one. Slickensides had a preferred orientation within several core levels, and fibrous-nonfibrous calcite serves as fracture fillings.« less

Mechanical stratigraphic controls on natural fracture spacing and penetration

NASA Astrophysics Data System (ADS)

McGinnis, Ronald N.; Ferrill, David A.; Morris, Alan P.; Smart, Kevin J.; Lehrmann, Daniel

2017-02-01

Fine-grained low permeability sedimentary rocks, such as shale and mudrock, have drawn attention as unconventional hydrocarbon reservoirs. Fracturing - both natural and induced - is extremely important for increasing permeability in otherwise low-permeability rock. We analyze natural extension fracture networks within a complete measured outcrop section of the Ernst Member of the Boquillas Formation in Big Bend National Park, west Texas. Results of bed-center, dip-parallel scanline surveys demonstrate nearly identical fracture strikes and slight variation in dip between mudrock, chalk, and limestone beds. Fracture spacing tends to increase proportional to bed thickness in limestone and chalk beds; however, dramatic differences in fracture spacing are observed in mudrock. A direct relationship is observed between fracture spacing/thickness ratio and rock competence. Vertical fracture penetrations measured from the middle of chalk and limestone beds generally extend to and often beyond bed boundaries into the vertically adjacent mudrock beds. In contrast, fractures in the mudrock beds rarely penetrate beyond the bed boundaries into the adjacent carbonate beds. Consequently, natural bed-perpendicular fracture connectivity through the mechanically layered sequence generally is poor. Fracture connectivity strongly influences permeability architecture, and fracture prediction should consider thin bed-scale control on fracture heights and the strong lithologic control on fracture spacing.

Fluid identification based on P-wave anisotropy dispersion gradient inversion for fractured reservoirs

NASA Astrophysics Data System (ADS)

Zhang, J. W.; Huang, H. D.; Zhu, B. H.; Liao, W.

2017-10-01

Fluid identification in fractured reservoirs is a challenging issue and has drawn increasing attentions. As aligned fractures in subsurface formations can induce anisotropy, we must choose parameters independent with azimuths to characterize fractures and fluid effects such as anisotropy parameters for fractured reservoirs. Anisotropy is often frequency dependent due to wave-induced fluid flow between pores and fractures. This property is conducive for identifying fluid type using azimuthal seismic data in fractured reservoirs. Through the numerical simulation based on Chapman model, we choose the P-wave anisotropy parameter dispersion gradient (PADG) as the new fluid factor. PADG is dependent both on average fracture radius and fluid type but independent on azimuths. When the aligned fractures in the reservoir are meter-scaled, gas-bearing layer could be accurately identified using PADG attribute. The reflection coefficient formula for horizontal transverse isotropy media by Rüger is reformulated and simplified according to frequency and the target function for inverting PADG based on frequency-dependent amplitude versus azimuth is derived. A spectral decomposition method combining Orthogonal Matching Pursuit and Wigner-Ville distribution is used to prepare the frequency-division data. Through application to synthetic data and real seismic data, the results suggest that the method is useful for gas identification in reservoirs with meter-scaled fractures using high-qualified seismic data.

Digital radiography with computerized conventional monitors compared to medical monitors in vertical root fracture diagnosis.

PubMed

Tofangchiha, Maryam; Adel, Mamak; Bakhshi, Mahin; Esfehani, Mahsa; Nazeman, Pantea; Ghorbani Elizeyi, Mojgan; Javadi, Amir

2013-01-01

Vertical root fracture (VRF) is a complication which is chiefly diagnosed radiographically. Recently, film-based radiography has been substituted with digital radiography. At the moment, there is a wide range of monitors available in the market for viewing digital images. The present study aims to compare the diagnostic accuracy, sensitivity and specificity of medical and conventional monitors in detection of vertical root fractures. In this in vitro study 228 extracted single-rooted human teeth were endodontically treated. Vertical root fractures were induced in 114 samples. The teeth were imaged by a digital charge-coupled device radiography using parallel technique. The images were evaluated by a radiologist and an endodontist on two medical and conventional liquid-crystal display (LCD) monitors twice. Z-test was used to analyze the sensitivity, accuracy and specificity of each monitor. Significance level was set at 0.05. Inter and intra observer agreements were calculated by Cohen's kappa. Accuracy, specificity and sensitivity for conventional monitor were calculated as 67.5%, 72%, 62.5% respectively; and data for medical grade monitor were 67.5%, 66.5% and 68% respectively. Statistical analysis showed no significant differences in detecting VRF between the two techniques. Inter-observer agreement for conventional and medical monitor was 0.47 and 0.55 respectively (moderate). Intra-observer agreement was 0.78 for medical monitor and 0.87 for conventional one (substantial). The type of monitor does not influence diagnosis of vertical root fractures.

Investigation of possible wellbore cement failures during hydraulic fracturing operations

EPA Pesticide Factsheets

Researchers used the peer-reviewed TOUGH+ geomechanics computational software and simulation system to investigate the possibility of fractures and shear failure along vertical wells during hydraulic fracturing operations.

Seismic determination of saturation in fractured reservoirs

USGS Publications Warehouse

Brown, R.L.; Wiggins, M.L.; Gupta, A.

2002-01-01

Detecting the saturation of a fractured reservoir using shear waves is possible when the fractures have a geometry that induces a component of movement perpendicular to the fractures. When such geometry is present, vertically traveling shear waves can be used to examine the saturation of the fractured reservoir. Tilted, corrugated, and saw-tooth fracture models are potential examples.

A multidisciplinary-based conceptual model of a fractured sedimentary bedrock aquitard: improved prediction of aquitard integrity

NASA Astrophysics Data System (ADS)

Runkel, Anthony C.; Tipping, Robert G.; Meyer, Jessica R.; Steenberg, Julia R.; Retzler, Andrew J.; Parker, Beth L.; Green, Jeff A.; Barry, John D.; Jones, Perry M.

2018-06-01

A hydrogeologic conceptual model that improves understanding of variability in aquitard integrity is presented for a fractured sedimentary bedrock unit in the Cambrian-Ordovician aquifer system of midcontinent North America. The model is derived from multiple studies on the siliciclastic St. Lawrence Formation and adjacent strata across a range of scales and geologic conditions. These studies employed multidisciplinary techniques including borehole flowmeter logging, high-resolution depth-discrete multilevel well monitoring, fracture stratigraphy, fluorescent dye tracing, and three-dimensional (3D) distribution of anthropogenic tracers regionally. The paper documents a bulk aquitard that is highly anisotropic because of poor connectivity of vertical fractures across matrix with low permeability, but with ubiquitous bed parallel partings. The partings provide high bulk horizontal hydraulic conductivity, analogous to aquifers in the system, while multiple preferential termination horizons of vertical fractures serve as discrete low vertical hydraulic conductivity intervals inhibiting vertical flow. The aquitard has substantial variability in its ability to protect underlying groundwater from contamination. Across widespread areas where the aquitard is deeply buried by younger bedrock, preferential termination horizons provide for high aquitard integrity (i.e. protection). Protection is diminished close to incised valleys where stress release and weathering has enhanced secondary pore development, including better connection of fractures across these horizons. These conditions, along with higher hydraulic head gradients in the same areas and more complex 3D flow where the aquitard is variably incised, allow for more substantial transport to deeper aquifers. The conceptual model likely applies to other fractured sedimentary bedrock aquitards within and outside of this region.

Electro-optic characteristics of 4-domain vertical alignment nematic liquid crystal display with interdigital electrode

NASA Astrophysics Data System (ADS)

Hong, S. H.; Jeong, Y. H.; Kim, H. Y.; Cho, H. M.; Lee, W. G.; Lee, S. H.

2000-06-01

We have fabricated a vertically aligned 4-domain nematic liquid crystal display cell with thin film transistor. Unlike the conventional method constructing 4-domain, i.e., protrusion and surrounding electrode which needs additional processes, in this study the pixel design forming 4-domain with interdigital electrodes is suggested. In the device, one pixel is divided into two parts. One part has a horizontal electric field in the vertical direction and the other part has a horizontal one in the horizontal direction. Such fields in the horizontal and vertical direction drive the liquid crystal director to tilt down in four directions. In this article, the electro-optic characteristics of cells with 2 and 4 domain have been studied. The device with 4 domain shows faster response time than normal twisted-nematic and in-plane switching cells, wide viewing angle with optical compensation film, and more stable color characteristics than 2-domain vertical alignment cell with similar structure.

Biodiesel and Integrated STEM: Vertical Alignment of High School Biology/Biochemistry and Chemistry

ERIC Educational Resources Information Center

Burrows, Andrea C.; Breiner, Jonathan M.; Keiner, Jennifer; Behm, Chris

2014-01-01

This article explores the vertical alignment of two high school classes, biology and chemistry, around the core concept of biodiesel fuel production. High school teachers and university faculty members investigated biodiesel as it relates to societal impact through a National Science Foundation Research Experience for Teachers. Using an action…

Fast preparation of hydroxyapatite/superhydrophilic vertically aligned multiwalled carbon nanotube composites for bioactive application.

PubMed

Lobo, Anderson O; Corat, Marcus A F; Ramos, Sandra C; Matsushima, Jorge T; Granato, Alessandro E C; Pacheco-Soares, Cristina; Corat, Evaldo J

2010-12-07

A method for the electrodeposition of hydroxyapatite films on superhydrophilic vertically aligned multiwalled carbon nanotubes is presented. The formation of a thin homogeneous film with high crystallinity was observed without any thermal treatment and with bioactivity properties that accelerate the in vitro biomineralization process and osteoblast adhesion.

Microwave and Millimeter Wave Properties of Vertically-Aligned Single Wall Carbon Nanotubes Films

NASA Astrophysics Data System (ADS)

Haddadi, K.; Tripon-Canseliet, C.; Hivin, Q.; Ducournau, G.; Teo, E.; Coquet, P.; Tay, B. K.; Lepilliet, S.; Avramovic, V.; Chazelas, J.; Decoster, D.

2016-05-01

We present the experimental determination of the complex permittivity of vertically aligned single wall carbon nanotubes (SWCNTs) films grown on quartz substrates in the microwave regime from 10 MHz up to 67 GHz, with the electrical field perpendicular to the main axis of the carbon nanotubes (CNTs), based on coplanar waveguide transmission line approach together with the measurement of the microwave impedance of top metalized vertically—aligned SWCNTs grown on conductive silicon substrates up to 26 GHz. From coplanar waveguide measurements, we obtain a real part of the permittivity almost equal to unity, which is interpreted in terms of low carbon atom density (3 × 1019 at/cm3) associated with a very low imaginary part of permittivity (<10-3) in the frequency range considered due to a very small perpendicular conductivity. The microwave impedance of a vertically aligned CNTs bundle equivalent to a low resistance reveals a good conductivity (3 S/cm) parallel to the CNTs axis. From these two kinds of data, we experimentally demonstrate the tensor nature of the vertically grown CNTs bundles.

Laser-assisted simultaneous transfer and patterning of vertically aligned carbon nanotube arrays on polymer substrates for flexible devices.

PubMed

In, Jung Bin; Lee, Daeho; Fornasiero, Francesco; Noy, Aleksandr; Grigoropoulos, Costas P

2012-09-25

We demonstrate a laser-assisted dry transfer technique for assembling patterns of vertically aligned carbon nanotube arrays on a flexible polymeric substrate. A laser beam is applied to the interface of a nanotube array and a polycarbonate sheet in contact with one another. The absorbed laser heat promotes nanotube adhesion to the polymer in the irradiated regions and enables selective pattern transfer. A combination of the thermal transfer mechanism with rapid direct writing capability of focused laser beam irradiation allows us to achieve simultaneous material transfer and direct micropatterning in a single processing step. Furthermore, we demonstrate that malleability of the nanotube arrays transferred onto a flexible substrate enables post-transfer tailoring of electric conductance by collapsing the aligned nanotubes in different directions. This work suggests that the laser-assisted transfer technique provides an efficient route to using vertically aligned nanotubes as conductive elements in flexible device applications.

Comparison of surgical techniques of 111 medial malleolar fractures classified by fracture geometry.

PubMed

Ebraheim, Nabil A; Ludwig, Todd; Weston, John T; Carroll, Trevor; Liu, Jiayong

2014-05-01

Evaluation of operative techniques used for medial malleolar fractures by classifying fracture geometry has not been well documented. One hundred eleven patients with medial malleolar fractures (transverse n = 63, oblique n = 29, vertical n = 7, comminuted n = 12) were included in this study. Seventy-two patients had complicating comorbidities. All patients were treated with buttress plate, lag screw, tension band, or K-wire fixation. Treatment outcomes were evaluated on the basis of radiological outcome (union, malunion, delayed union, or nonunion), need for operative revision, presence of postoperative complications, and AOFAS Ankle-Hindfoot score. For transverse fractures, tension band fixation showed the highest rate of union (79%), highest average AOFAS score (86), lowest revision rate (5%), and lowest complication rate (16%). For oblique fractures, lag screws showed the highest rate of union (71%), highest average AOFAS score (80), lowest revision rate (19%), and lowest complication rate (33%) of the commonly used fixation techniques. For vertical fractures, buttress plating was used in every case but 1, achieving union (whether normal or delayed) in all cases with an average AOFAS score of 84, no revisions, and a 17% complication rate. Comminuted fractures had relatively poor outcomes regardless of fixation method. The results of this study suggest that both tension bands and lag screws result in similar rates of union for transverse fractures of the medial malleolus, but that tension band constructs are associated with less need for revision surgery and fewer complications. In addition, our data demonstrate that oblique fractures were most effectively treated with lag screws and that vertical fractures attained superior outcomes with buttress plating. Level III, retrospective comparative series.

Reactor Pressure Vessel Fracture Analysis Capabilities in Grizzly

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

Spencer, Benjamin; Backman, Marie; Chakraborty, Pritam

2015-03-01

Efforts have been underway to develop fracture mechanics capabilities in the Grizzly code to enable it to be used to perform deterministic fracture assessments of degraded reactor pressure vessels (RPVs). Development in prior years has resulted a capability to calculate -integrals. For this application, these are used to calculate stress intensity factors for cracks to be used in deterministic linear elastic fracture mechanics (LEFM) assessments of fracture in degraded RPVs. The -integral can only be used to evaluate stress intensity factors for axis-aligned flaws because it can only be used to obtain the stress intensity factor for pure Mode Imore » loading. Off-axis flaws will be subjected to mixed-mode loading. For this reason, work has continued to expand the set of fracture mechanics capabilities to permit it to evaluate off-axis flaws. This report documents the following work to enhance Grizzly’s engineering fracture mechanics capabilities for RPVs: • Interaction Integral and -stress: To obtain mixed-mode stress intensity factors, a capability to evaluate interaction integrals for 2D or 3D flaws has been developed. A -stress evaluation capability has been developed to evaluate the constraint at crack tips in 2D or 3D. Initial verification testing of these capabilities is documented here. • Benchmarking for axis-aligned flaws: Grizzly’s capabilities to evaluate stress intensity factors for axis-aligned flaws have been benchmarked against calculations for the same conditions in FAVOR. • Off-axis flaw demonstration: The newly-developed interaction integral capabilities are demon- strated in an application to calculate the mixed-mode stress intensity factors for off-axis flaws. • Other code enhancements: Other enhancements to the thermomechanics capabilities that relate to the solution of the engineering RPV fracture problem are documented here.« less

Transition of vertically aligned liquid crystal driven by fan-shaped electric field

NASA Astrophysics Data System (ADS)

Tsung, J. W.; Ting, T. L.; Chen, C. Y.; Liang, W. L.; Lai, C. W.; Lin, T. H.; Hsu, W. H.

2017-09-01

Interdigital electrodes are implemented in many commercial and novel liquid crystal devices to align molecules. Although many empirical principles and patents apply to electrode design, only a few numerical simulations of alignment have been conducted. Why and how the molecules align in an ordered manner has never been adequately explained. Hence, this investigation addresses the Fréedericksz transition of vertically aligned liquid crystal that is driven by fishbone electrodes, and thereafter identifies the mechanism of liquid crystal alignment. Theoretical calculations suggest that the periodic deformation that is caused by the fan-shaped fringe field minimizes the free energy in the liquid crystal cell, and the optimal alignment can be obtained when the cell parameters satisfy the relation p /2 d =√{k11/k33 } , where p is the spatial period of the strips of the electrode; d denotes the cell gap; and k11 and k33 are the splay and bend elastic constants of the liquid crystal, respectively. Polymer-stabilized vertical alignment test cells with various p values and spacings between the electrodes were fabricated, and the process of liquid crystal alignment was observed under an optical microscope. The degree of alignment was evaluated by measuring the transmittance of the test cell. The experimental results were consistent with the theoretical predictions. The principle of design, p /2 d =√{k11/k33 } , greatly improves the uniformity and stability of the aligned liquid crystal. The methods that are presented here can be further applied to cholesteric liquid crystal and other self-assembled soft materials.

Installation and assembly device and method of using

DOEpatents

Kolsun, George J.

1997-01-01

An installation and assembly device for aligning a first member such as a pump impeller with a second member such as an inlet nozzle of an impeller pump. The installation and assembly device includes a sleeve slideable within the inlet nozzle and a vertical positioning assembly which has a contact member that is extendable out away from the sleeve so as to vertically position the sleeve on a shoulder of the inlet nozzle and to present an upper contact surface spaced a certain distance from the shoulder to provide the desired vertical spacing with respect to the impeller contacting the upper contact surface. The vertical positioning assembly is retractable so as to allow for removal of the sleeve through the nozzle when installation and assembly are completed. The alignment device also includes a radial alignment assembly supported by the sleeve and adjustable to an expanded state for contacting and spacing the interior surface of the impeller a certain distance from the sleeve and hence a certain distance from the inlet nozzle. The radial alignment device being adjustable from a retracted removal state to an expanded state and also being adjustable to fine tune the spacing of the impeller from the sleeve. The radial alignment device also preferably includes members that can be used to releasably secure the sleeve to the impeller.

Periodontal tissue repair after sealing of the gap in vertical root fracture.

PubMed

Sugaya, Tsutomu; Tomita, Mahito; Motoki, Youji; Zaman, Khurshiduz; Miyaji, Hirofumi; Kawanami, Masamitsu

2017-04-01

The aim of this study was to determine whether sealing of fracture gap using adhesive resin through the root canal can prevent inflammation of periodontal tissue, and resealing the incompletely sealed fracture gap from outside can resolve such inflammation in experimentally created vertical root fractures. Vertical root fractures were created in incisor of beagles. In the experimental group, the fracture gap was sealed through the root canal with adhesive resin. After 5 weeks, sites with the clinical attachment level ≥4 mm were further divided randomly into the poor-replanting group and the poor-untreated group. In the poor-replanting group, the tooth was extracted and replanted after resealing the fracture gap with adhesive resin from the outer surface. Sites with clinical attachment level ≤3 mm after 5 weeks were considered as the satisfactory group. The poor-untreated group and the satisfactory group were subjected to no further treatment. The clinical attachment level was evaluated at baseline and after 2, 5, and 9 weeks. After 9 weeks, histological measurements were made to determine the length of the epithelial downgrowth and the area of alveolar bone resorption. The clinical attachment level and the area of bone resorption were significantly smaller in the poor-replanting group and the satisfactory group than in the poor-untreated group (p < 0.05). The results indicate the possibility that periodontal inflammation along the fracture line can be prevented and improved if the fracture gap is sealed.

Hydraulic Fracture Growth in a Layered Formation based on Fracturing Experiments and Discrete Element Modeling

NASA Astrophysics Data System (ADS)

Yushi, Zou; Xinfang, Ma; Tong, Zhou; Ning, Li; Ming, Chen; Sihai, Li; Yinuo, Zhang; Han, Li

2017-09-01

Hydraulic fracture (HF) height containment tends to occur in layered formations, and it significantly influences the entire HF geometry or the stimulated reservoir volume. This study aims to explore the influence of preexisting bedding planes (BPs) on the HF height growth in layered formations. Laboratory fracturing experiments were performed to confirm the occurrence of HF height containment in natural shale that contains multiple weak and high-permeability BPs under triaxial stresses. Numerical simulations were then conducted to further illustrate the manner in which vertical stress, BP permeability, BP density(or spacing), pump rate, and fluid viscosity control HF height growth using a 3D discrete element method-based fracturing model. In this model, the rock matrix was considered transversely isotropic and multiple BPs can be explicitly represented. Experimental and numerical results show that the vertically growing HF tends to be limited by multi-high-permeability BPs, even under higher vertical stress. When the vertically growing HF intersects with the multi-high-permeability BPs, the injection pressure will be sharply reduced. If a low pumping rate or a low-viscosity fluid is used, the excess fracturing fluid leak-off into the BPs obviously decreases the rate of pressure build up, which will then limit the growth of HF. Otherwise, a higher pumping rate and/or a higher viscosity will reduce the leak-off time and fluid volume, but increase the injection pressure to drive the HF to grow and to penetrate through the BPs.

Geological evidence of pre-2012 Emilia, Italy, seismic events

NASA Astrophysics Data System (ADS)

Caputo, Riccardo; Minarelli, Luca; Papathanassiou, Giorgos; Poli, Eliana M.; Rapti-Caputo, Dimitra; Sboras, Sotiris; Stefani, Marco; Zanferrari, Adriano

2013-04-01

In May 2012, two moderate (ML = 5.9 and 5.8) earthquakes, associated with a noticeable aftershock sequence, affected the eastern sector of the Po Plain, Italy. The causative faults are two segments of the Ferrara Arc thrust system representing the most frontal portion of the buried Northern Apennines fold-and-thrust belt. Few weeks after the earthquake, a palaeoseismological trench was excavated south of the San Carlo village (western Ferrara Province), where a system of aligned ground ruptures were observed. In the trench walls we observed several features documenting the occurrence of past liquefaction events affecting the same site. For example, i) 10 cm-thick dikes filled with injected sand and associated with vertical displacements have no correspondence with the fractures mapped at the surface before the excavation; ii) some thick dikes are arrested below the ploughed level or even by older sedimentary layers; iii) along the internal slope of the palaeo-channel exposed by the trench, load structures and slided blocks are observed; iv) in correspondence with the ground fractures characterised by vertical displacement and opening occurred during the 2012 earthquake and thick dikes, observed at the surface and in the trench's walls, respectively, sand and water ejection did not occur. In conclusion, the results of the palaeoseismological investigation document for the first time that shacking (i.e. seismic) events occurred in the past producing a sufficient ground motion capable of triggering liquefaction phenomena prior to, but likely stronger than, the May 2012 earthquake. A likely candidate is the November 17, 1570 Ferrara earthquake.

Induced seismicity at the UK `hot dry rock' test site for geothermal energy production

NASA Astrophysics Data System (ADS)

Li, Xun; Main, Ian; Jupe, Andrew

2018-07-01

In enhanced geothermal systems (EGS), fluid is injected at high pressure in order to stimulate fracturing and/or fluid flow through otherwise relatively impermeable underlying hot rocks to generate power and/or heat. The stimulation induces microearthquakes whose precise triggering mechanism and relationship to new and pre-existing fracture networks are still the subject of some debate. Here, we analyse the data set for induced microearthquakes at the UK `hot dry rock' experimental geothermal site (Rosemanowes, Cornwall). We quantify the evolution of several metrics used to characterise induced seismicity, including the seismic strain partition factor and the `seismogenic index'. The results show a low strain partition factor of 0.01 per cent and a low seismogenic index indicating that aseismic processes dominate. We also analyse the spatio-temporal distribution of hypocentres, using simple models for the evolution of hydraulic diffusivity by (1) isotropic and (2) anisotropic pore-pressure relaxation. The principal axes of the diffusivity or permeability tensor inferred from the spatial distribution of earthquake foci are aligned parallel to the present-day stress field, although the maximum permeability is vertical, whereas the maximum principal stress is horizontal. Our results are consistent with a triggering mechanism that involves (1) seismic shear slip along optimally oriented pre-existing fractures, (2) a large component of aseismic slip with creep and (3) activation of tensile fractures as hydraulic conduits created by both the present-day stress field and by the induced shear slip, both exploiting pre-existing joint sets exposed in borehole data.

Nanostructured pillars based on vertically aligned carbon nanotubes as the stationary phase in micro-CEC.

PubMed

Wu, Ren-Guei; Yang, Chung-Shi; Wang, Pen-Cheng; Tseng, Fan-Gang

2009-06-01

We present a micro-CEC chip carrying out a highly efficient separation of dsDNA fragments through vertically aligned multi-wall carbon nanotubes (MWCNTs) in a microchannel. The vertically aligned MWCNTs were grown directly in the microchannel to form straight nanopillar arrays as ordered and directional chromatographic supports. 1-Pyrenedodecanoic acid was employed for the surface modification of the MWCNTs' stationary phase to adsorb analytes by hydrophobic interactions. This device was used for separating dsDNA fragments of three different lengths (254, 360, and 572 bp), and fluorescence detection was employed to verify the electrokinetic transport in the MWCNT array. The micro-CEC separation of the three compounds was achieved in less than 300 s at a field strength of 66 V/cm due to superior laminar flow patterns and a lower flow resistance resulting from the vertically aligned MWCNTs being used as the stationary phase medium. In addition, a fivefold reduction of band broadening was obtained when the analyte was separated by the chromatographic MWCNT array channel instead of the CE channel. From all of the results, we suggest that an in situ grown and directional MWCNT array can potentially be useful for preparing more diversified forms of stationary phases for vertically efficient chip-based electrochromatography.

Highly uniform and vertically aligned SnO2 nanochannel arrays for photovoltaic applications

NASA Astrophysics Data System (ADS)

Kim, Jae-Yup; Kang, Jin Soo; Shin, Junyoung; Kim, Jin; Han, Seung-Joo; Park, Jongwoo; Min, Yo-Sep; Ko, Min Jae; Sung, Yung-Eun

2015-04-01

Nanostructured electrodes with vertical alignment have been considered ideal structures for electron transport and interfacial contact with redox electrolytes in photovoltaic devices. Here, we report large-scale vertically aligned SnO2 nanochannel arrays with uniform structures, without lateral cracks fabricated by a modified anodic oxidation process. In the modified process, ultrasonication is utilized to avoid formation of partial compact layers and lateral cracks in the SnO2 nanochannel arrays. Building on this breakthrough, we first demonstrate the photovoltaic application of these vertically aligned SnO2 nanochannel arrays. These vertically aligned arrays were directly and successfully applied in quasi-solid state dye-sensitized solar cells (DSSCs) as photoanodes, yielding reasonable conversion efficiency under back-side illumination. In addition, a significantly short process time (330 s) for achieving the optimal thickness (7.0 μm) and direct utilization of the anodized electrodes enable a simple, rapid and low-cost fabrication process. Furthermore, a TiO2 shell layer was coated on the SnO2 nanochannel arrays by the atomic layer deposition (ALD) process for enhancement of dye-loading and prolonging the electron lifetime in the DSSC. Owing to the presence of the ALD TiO2 layer, the short-circuit photocurrent density (Jsc) and conversion efficiency were increased by 20% and 19%, respectively, compared to those of the DSSC without the ALD TiO2 layer. This study provides valuable insight into the development of efficient SnO2-based photoanodes for photovoltaic application by a simple and rapid fabrication process.Nanostructured electrodes with vertical alignment have been considered ideal structures for electron transport and interfacial contact with redox electrolytes in photovoltaic devices. Here, we report large-scale vertically aligned SnO2 nanochannel arrays with uniform structures, without lateral cracks fabricated by a modified anodic oxidation process. In the modified process, ultrasonication is utilized to avoid formation of partial compact layers and lateral cracks in the SnO2 nanochannel arrays. Building on this breakthrough, we first demonstrate the photovoltaic application of these vertically aligned SnO2 nanochannel arrays. These vertically aligned arrays were directly and successfully applied in quasi-solid state dye-sensitized solar cells (DSSCs) as photoanodes, yielding reasonable conversion efficiency under back-side illumination. In addition, a significantly short process time (330 s) for achieving the optimal thickness (7.0 μm) and direct utilization of the anodized electrodes enable a simple, rapid and low-cost fabrication process. Furthermore, a TiO2 shell layer was coated on the SnO2 nanochannel arrays by the atomic layer deposition (ALD) process for enhancement of dye-loading and prolonging the electron lifetime in the DSSC. Owing to the presence of the ALD TiO2 layer, the short-circuit photocurrent density (Jsc) and conversion efficiency were increased by 20% and 19%, respectively, compared to those of the DSSC without the ALD TiO2 layer. This study provides valuable insight into the development of efficient SnO2-based photoanodes for photovoltaic application by a simple and rapid fabrication process. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00202h

Transient pressure analysis of a volume fracturing well in fractured tight oil reservoirs

NASA Astrophysics Data System (ADS)

Lu, Cheng; Wang, Jiahang; Zhang, Cong; Cheng, Minhua; Wang, Xiaodong; Dong, Wenxiu; Zhou, Yingfang

2017-12-01

This paper presents a semi-analytical model to simulate transient pressure curves for a vertical well with a reconstructed fracture network in fractured tight oil reservoirs. In the proposed model, the reservoir is a composite system and contains two regions. The inner region is described as a formation with a finite conductivity hydraulic fracture network and the flow in the fracture is assumed to be linear, while the outer region is modeled using the classical Warren-Root model where radial flow is applied. The transient pressure curves of a vertical well in the proposed reservoir model are calculated semi-analytically using the Laplace transform and Stehfest numerical inversion. As shown in the type curves, the flow is divided into several regimes: (a) linear flow in artificial main fractures; (b) coupled boundary flow; (c) early linear flow in a fractured formation; (d) mid radial flow in the semi-fractures of the formation; (e) mid radial flow or pseudo steady flow; (f) mid cross-flow; (g) closed boundary flow. Based on our newly proposed model, the effects of some sensitive parameters, such as elastic storativity ratio, cross-flow coefficient, fracture conductivity and skin factor, on the type curves were also analyzed extensively. The simulated type curves show that for a vertical fractured well in a tight reservoir, the elastic storativity ratios and crossflow coefficients affect the time and the degree of crossflow respectively. The pressure loss increases with an increase in the fracture conductivity. To a certain extent, the effect of the fracture conductivity is more obvious than that of the half length of the fracture on improving the production effect. With an increase in the wellbore storage coefficient, the fluid compressibility is so large that it might cover the early stage fracturing characteristics. Linear or bilinear flow may not be recognized, and the pressure and pressure derivative gradually shift to the right. With an increase in the skin effect, the pressure loss increases gradually.

Dynamic mechanical analysis and high strain-rate energy absorption characteristics of vertically aligned carbon nanotube reinforced woven fiber-glass composites

USDA-ARS?s Scientific Manuscript database

The dynamic mechanical behavior and energy absorption characteristics of nano-enhanced functionally graded composites, consisting of 3 layers of vertically aligned carbon nanotube (VACNT) forests grown on woven fiber-glass (FG) layer and embedded within 10 layers of woven FG, with polyester (PE) and...

A black body absorber from vertically aligned single-walled carbon nanotubes

PubMed Central

Mizuno, Kohei; Ishii, Juntaro; Kishida, Hideo; Hayamizu, Yuhei; Yasuda, Satoshi; Futaba, Don N.; Yumura, Motoo; Hata, Kenji

2009-01-01

Among all known materials, we found that a forest of vertically aligned single-walled carbon nanotubes behaves most similarly to a black body, a theoretical material that absorbs all incident light. A requirement for an object to behave as a black body is to perfectly absorb light of all wavelengths. This important feature has not been observed for real materials because materials intrinsically have specific absorption bands because of their structure and composition. We found a material that can absorb light almost perfectly across a very wide spectral range (0.2–200 μm). We attribute this black body behavior to stem from the sparseness and imperfect alignment of the vertical single-walled carbon nanotubes. PMID:19339498

Positional Change in Displacement of Midshaft Clavicle Fractures: An Aid to Initial Evaluation.

PubMed

Malik, Awais; Jazini, Ehsan; Song, Xuyang; Johal, Herman; OʼHara, Nathan; Slobogean, Gerard; Abzug, Joshua M

2017-01-01

To determine how change in position affects displacement of midshaft clavicle fractures. Retrospective review. Level I Trauma Center. Eighty patients with displaced midshaft clavicle fractures and presence of supine and semiupright or upright chest radiographs taken within 2 weeks of each other. Supine, semiupright, and upright chest radiographs. Fracture shortening and vertical displacement on supine, semiupright, and upright radiographs. Mean vertical displacement was 9.42 mm [95% confidence interval (95% CI), 8.07-10.77 mm], 11.78 mm (95% CI, 10.25-13.32 mm), and 15.72 mm (95% CI, 13.71-17.72 mm) in supine, semiupright, and upright positions, respectively. Fracture shortening was -0.41 mm (95% CI, -2.53 to 1.70 mm), 2.11 mm (95% CI, -0.84 to 5.07), and 4.86 mm (95% CI, 1.66-8.06 mm) in supine, semiupright, and upright positions, respectively. Change in position from supine to upright significantly increased both vertical displacement and fracture shortening (P < 0.001). In the upright position, the proportion of patients who met operative indications (fracture shortening >20 mm) was 3 times greater when compared with that in the supine position (upright 17.65%; supine 5.88%, P = 0.06). Positional changes in fracture displacement were not associated with body mass index, age, or gender. Patient position is associated with significant changes in fracture displacement. Over 3 times more patients meet operative indications when placed in the upright versus supine position. An upright chest radiograph should be obtained to evaluate midshaft clavicle fracture displacement, as it represents the physiologic stress across the fracture when considering nonoperative management. Prognostic level IV. See Instructions for Authors for a complete description of levels of evidence.

Review of aquifer test results for the Lansdale area, Montgomery County, Pennsylvania, 1980-95

USGS Publications Warehouse

Goode, Daniel J.; Senior, Lisa A.

1998-01-01

Aquifer and aquifer-isolation test results in and around North Penn Area 6 Superfund site, Lansdale, Montgomery County, Pennsylvania are reviewed to provide estimated aquifer properties for use in a numerical model of ground-water flow. This review is in support of remedial action investigations by U.S. Environmental Protection Agency (USEPA), Region III, Philadelphia. Data are from files of the U.S. Geological Survey, USEPA, and water companies, and from unpublished consultant reports for USEPA and corporations in the Lansdale area. Tested wells are in fractured sedimentary rocks of the Brunswick Formation, which are Triassic-aged, dipping shales and sandstones. Review procedures include, in some cases, new analyses of drawdown during pumping and recovery using analytical models of flow to wells. Estimated aquifer transmissivities (T) range from zero to about 1,300 m2/d (meters squared per day), with most tests indicating T between 10 and 100 m2/d. Aquifer-isolation testing results indicate that most flow enters wells at a few discrete zones, probably fractures or bedding plane openings. The vertical connection between the zones in a single borehole with multiple producing zones often is negligible. This suggests that the formation is vertically anisotropic; the hydraulic conductivity is much larger in the horizontal direction than in the vertical direction. Some evidence of well-field-scale horizontal anisotropy exists, with maximum transmissivity aligned with the regional northeast strike of bedding, but this evidence is weak because of the small number of observation wells, particularly wells screened in isolated depth intervals. Analysis of recovery data after constant-pumping-rate aquifer tests and of drawdown during step tests suggests that a significant fraction, perhaps as much as 85 percent, of the drawdown in some production wells is due to well loss or skin effects in or very near the pumped well and is not caused by resistance to flow in the surrounding formations.

Crystallization Behavior of Poly(ethylene oxide) in Vertically Aligned Carbon Nanotube Array.

PubMed

Sheng, Jiadong; Zhou, Shenglin; Yang, Zhaohui; Zhang, Xiaohua

2018-03-27

We investigate the effect of the presence of vertically aligned multiwalled carbon nanotubes (CNTs) on the orientation of poly(ethylene oxide) (PEO) lamellae and PEO crystallinity. The high alignment of carbon nanotubes acting as templates probably governs the orientation of PEO lamellae. This templating effect might result in the lamella planes of PEO crystals oriented along a direction parallel to the long axis of the nanotubes. The presence of aligned carbon nanotubes also gives rise to the decreases in PEO crystallinity, crystallization temperature, and melting temperature due to the perturbation of carbon nanotubes to the crystallization of PEO. These effects have significant implications for controlling the orientation of PEO lamellae and decreasing the crystallinity of PEO and thickness of PEO lamellae, which have significant impacts on ion transport in PEO/CNT composite and the capacitive performance of PEO/CNT composite. Both the decreased PEO crystallinity and the orientation of PEO lamellae along the long axes of vertically aligned CNTs give rise to the decrease in the charge transfer resistance, which is associated with the improvements in the ion transport and capacitive performance of PEO/CNT composite.

Distributed deformation structures in shallow water carbonates subsiding through a simple stress field (Jandaira Formation, NE Brazil)

NASA Astrophysics Data System (ADS)

Bertotti, Giovanni; Bisdom, Kevin; Bezerra, Hilario; Reijmer, John; Cazarin, Carol

2016-04-01

Despite the scarcity of major deformation structures such as folds and faults, the flat-lying, post-rift shallow water carbonates of the Jandaira Formation (Potiguar Basin, NE Brazil) display well-organized fracture systems distributed of tens of km2. Structures observed in the outcropping carbonates are sub-vertical, generally N-S trending mode I and hybrid veins and barren fractures, sub-vertical roughly E-W trending stylolites and sub-horizontal stylolites. These features developed during subsidence in a simple and constant stress field characterized by, beside gravity, a significant horizontal stress probably of tectonic origin. The corresponding depth curves have different origin and slopes and, therefore, cross each other resulting in position of the principal stresses which change with depth. As a result, the type and amount of fractures affecting subsiding rocks change despite the fact that the far-field stresses remain constant. Following early diagenesis and porosity elimination in the first 100-200m depth, Jandaira carbonates experienced wholesale fracturing at depths of 400-800m resulting in a network of NNW-NE trending fractures partly organized in conjugate sets with a low interfault angle and a sub-vertical intersection, and sub-vertical stylolites roughly perpendicular to the fractures. Intense fluid circulation was activated as a consequence through the carbonates. With increasing subsidence, sub-horizontal stylolites formed providing calcite which precipitated in the open fractures transforming them in veins. The Jandaira formation lost thereby the permeability it had reached during the previous stage. Because of the lack of major deformation, the outcrops of the Jandaira Formation is an excellent analog for carbonate reservoirs in the Middle East, South Atlantic and elsewhere.

Vertical Root Fracture Detection Using Limited-FOV Cone-Beam Computed Tomography

DTIC Science & Technology

2012-06-01

A thesis submitted to the Faculty of the Endodontics Graduate Program Naval Postgraduate Dental School Uniformed Services...Dental Program Navy Medicine Professional Development Center Terry D. Webb, DDS, MS CAPT, DC, USN Chairman, Endodontics Dept. Glen M. Imamura, S...Computed Tomography Geoffrey McMurray, DDS, MS ABSTRACT Introduction: Vertical root fractures (VRF) often occur in endodontically treated teeth

Vertically-Integrated Dual-Continuum Models for CO2 Injection in Fractured Aquifers

NASA Astrophysics Data System (ADS)

Tao, Y.; Guo, B.; Bandilla, K.; Celia, M. A.

2017-12-01

Injection of CO2 into a saline aquifer leads to a two-phase flow system, with supercritical CO2 and brine being the two fluid phases. Various modeling approaches, including fully three-dimensional (3D) models and vertical-equilibrium (VE) models, have been used to study the system. Almost all of that work has focused on unfractured formations. 3D models solve the governing equations in three dimensions and are applicable to generic geological formations. VE models assume rapid and complete buoyant segregation of the two fluid phases, resulting in vertical pressure equilibrium and allowing integration of the governing equations in the vertical dimension. This reduction in dimensionality makes VE models computationally more efficient, but the associated assumptions restrict the applicability of VE model to formations with moderate to high permeability. In this presentation, we extend the VE and 3D models for CO2 injection in fractured aquifers. This is done in the context of dual-continuum modeling, where the fractured formation is modeled as an overlap of two continuous domains, one representing the fractures and the other representing the rock matrix. Both domains are treated as porous media continua and can be modeled by either a VE or a 3D formulation. The transfer of fluid mass between rock matrix and fractures is represented by a mass transfer function connecting the two domains. We have developed a computational model that combines the VE and 3D models, where we use the VE model in the fractures, which typically have high permeability, and the 3D model in the less permeable rock matrix. A new mass transfer function is derived, which couples the VE and 3D models. The coupled VE-3D model can simulate CO2 injection and migration in fractured aquifers. Results from this model compare well with a full-3D model in which both the fractures and rock matrix are modeled with 3D models, with the hybrid VE-3D model having significantly reduced computational cost. In addition to the VE-3D model, we explore simplifications of the rock matrix domain by using sugar-cube and matchstick conceptualizations and develop VE-dual porosity and VE-matchstick models. These vertically-integrated dual-permeability and dual-porosity models provide a range of computationally efficient tools to model CO2 storage in fractured saline aquifers.

Anatomical and Functional Recovery of Intracapsular Fractures of the Mandibular Condyle: Analysis of 124 Cases after Closed Treatment

PubMed Central

Lee, Jong-Sung; Jeon, Eun-Gyu; Seol, Guk-Jin; Choi, So-Young; Kim, Jin-Wook; Kwon, Tae-Geon; Paeng, Jun-Young

2014-01-01

Purpose: The purpose of this study is to evaluate the influence of intracapsular fracture lines of the mandibular condyle on the anatomical and functional recovery after non-surgical closed treatment. Methods: Clinical and radiological follow-up of 124 patients with intracapsular fractures of the mandibular condyle was performed after closed treatment between 2005 and 2012. The intracapsular fractures were classified into three categories: type A (medial condylar pole fracture), type B (lateral condylar pole fracture with loss of vertical height) and type M (multiple fragments or comminuted fracture). Results: By radiological finding, fracture types B and M lost up to 24% vertical height of the mandibular condyle compared to the height on the opposite side. In Type M, moderate to severe dysfunction was observed in 33% of the cases. Bilateral fractures were significantly associated with the risk of temporomandibular joint (TMJ) dysfunction in fracture types A and B. Bilateral fracture and TMJ dysfunction were not statistically significantly associated in type M fractures. Conclusion: Most of the mandibular intracapsular condylar fractures recovered acceptably after conservative non-surgical treatment with functional rehabilitation, even with some anatomical shortening of the condylar height. The poor functional recovery encountered in type M fractures, especially in cases with additional fracture sites and bilateral fractures, points up the limitation of closed treatment in such cases. PMID:27489844

Materials Examination of the Vertical Stabilizer from American Airlines Flight 587

NASA Technical Reports Server (NTRS)

Fox, Matthew R.; Schultheisz, Carl R.; Reeder, James R.; Jensen, Brian J.

2005-01-01

The first in-flight failure of a primary structural component made from composite material on a commercial airplane led to the crash of American Airlines Flight 587. As part of the National Transportation Safety Board investigation of the accident, the composite materials of the vertical stabilizer were tested, microstructure was analyzed, and fractured composite lugs that attached the vertical stabilizer to the aircraft tail were examined. In this paper the materials testing and analysis is presented, composite fractures are described, and the resulting clues to the failure events are discussed.

Intraoperative panoramic image using alignment grid, is it accurate?

PubMed

Apivatthakakul, T; Duanghakrung, M; Luevitoonvechkit, S; Patumasutra, S

2013-07-01

Minimally invasive orthopedic trauma surgery relies heavily on intraoperative fluoroscopic images to evaluate the quality of fracture reduction and fixation. However, fluoroscopic images have a narrow field of view and often cannot visualize the entire long bone axis. To compare the coronal femoral alignment between conventional X-rays to that achieved with a new method of acquiring a panoramic intraoperative image. Twenty-four cadaveric femurs with simple diaphyseal fractures were fixed with an angulated broad DCP to create coronal plane malalignment. An intraoperative alignment grid was used to help stitch different fluoroscopic images together to produce a panoramic image. A conventional X-ray of the entire femur was then performed. The coronal plane angulation in the panoramic images was then compared to the conventional X-rays using a Wilcoxon signed rank test. The mean angle measured from the panoramic view was 173.9° (range 169.3°-178.0°) with median of 173.2°. The mean angle measured from the conventional X-ray was 173.4° (range 167.7°-178.7°) with a median angle of 173.5°. There was no significant difference between both methods of measurement (P = 0.48). Panoramic images produced by stitching fluoroscopic images together with help of an alignment grid demonstrated the same accuracy at evaluating the coronal plane alignment of femur fractures as conventional X-rays.

Fracture resistance of pulpless teeth restored with post-cores and crowns.

PubMed

Hayashi, Mikako; Takahashi, Yutaka; Imazato, Satoshi; Ebisu, Shigeyuki

2006-05-01

The present study was designed to test the null hypothesis that there is no difference in the fracture resistance of pulpless teeth restored with different types of post-core systems and full coverage crowns. Extracted human upper premolars were restored with a fiber post, prefabricated metallic post or cast metallic post-core. Teeth with full crown preparations without post-core restorations served as a control. All teeth were restored with full coverage crowns. A 90-degree vertical or 45-degree oblique load was applied to the restored teeth with a crosshead speed of 0.5 mm/min, and the fracture loads and mode of fracture were recorded. Under the condition of vertical loading, the fracture load of teeth restored with the cast metallic post-cores was greatest among the groups (two-factor factorial ANOVA and Scheffe's F test, P<0.05). All fractures in teeth restored with all types of post-core systems propagated in the middle portions of roots, including the apices of the posts. Under the condition of oblique loading, the fracture load of teeth restored with pre-fabricated metallic posts was significantly smaller than that in other groups. Two-thirds of fractures in the fiber post group propagated within the cervical area, while most fractures in other groups extended beyond the middle of the roots. From the results of the present investigations, it was concluded that under the conditions of vertical and oblique loadings, the combination of a fiber post and composite resin core with a full cast crown is most protective of the remaining tooth structure.

Structural controls on anomalous transport in fractured porous rock

NASA Astrophysics Data System (ADS)

Edery, Yaniv; Geiger, Sebastian; Berkowitz, Brian

2016-07-01

Anomalous transport is ubiquitous in a wide range of disordered systems, notably in fractured porous formations. We quantitatively identify the structural controls on anomalous tracer transport in a model of a real fractured geological formation that was mapped in an outcrop. The transport, determined by a continuum scale mathematical model, is characterized by breakthrough curves (BTCs) that document anomalous (or "non-Fickian") transport, which is accounted for by a power law distribution of local transition times ψ>(t>) within the framework of a continuous time random walk (CTRW). We show that the determination of ψ>(t>) is related to fractures aligned approximately with the macroscopic direction of flow. We establish the dominant role of fracture alignment and assess the statistics of these fractures by determining a concentration-visitation weighted residence time histogram. We then convert the histogram to a probability density function (pdf) that coincides with the CTRW ψ>(t>) and hence anomalous transport. We show that the permeability of the geological formation hosting the fracture network has a limited effect on the anomalous nature of the transport; rather, it is the fractures transverse to the flow direction that play the major role in forming the long BTC tail associated with anomalous transport. This is a remarkable result, given the complexity of the flow field statistics as captured by concentration transitions.

The Role of Radiographs and Office Visits in the Follow-Up of Healed Intertrochanteric Hip Fractures: An Economic Analysis.

PubMed

Kempegowda, Harish; Richard, Raveesh; Borade, Amrut; Tawari, Akhil; Howenstein, Abby M; Kubiak, Erik N; Suk, Michael; Horwitz, Daniel S

2016-12-01

The purpose of this study was to evaluate the role and the necessity of radiographs and office visits obtained during follow-up of intertrochanteric hip injuries. Retrospective study. Two level I trauma centers. Four hundred sixty-five elderly patients who were surgically treated for an intertrochanteric fracture of the femur at 2 level I trauma centers between January 2009 and August 2014 were retrospectively identified from orthopaedic trauma databases. Analysis of all healed intertrochanteric hip fractures, including demographic characteristics, quality of reduction, time of healing, number of office visits, number of radiographs obtained, and each radiograph for fracture alignment, implant position or any pathological changes. The surgical fixation of 465 fractures included 155 short nails (33%), 232 long nails (50%), 69 sliding hip screw devices (15%), 7 trochanteric stabilizing plates (1.5%), and 2 proximal femur locking plates (0.5%). The average fracture healing time was 12.8 weeks and the average follow-up was 81.2 weeks. Radiographs of any patient obtained after the fracture had healed did not reveal any changes, including fracture alignment or implant position and hardware failure. In 9 patients, pathological changes, including arthritis (3), avascular necrosis (3), and ectopic ossification (3) were noted. The average number of elective office visits and radiographs obtained after the fracture had healed were 2.8 (range: 1-8) and 2.6 (range: 1-8), respectively. According to Medicare payments to the institution, these radiographs and office visits account for a direct cost of $360.81 and $192, respectively, per patient. The current study strongly suggests that there is a negligible role for radiographs and office visits during the follow-up of a well-healed hip fracture when there is documented evidence of radiographic and clinical healing with acceptable fracture alignment and implant position. Implementation of this simple measure will help in reducing the cost of care and inconvenience to elderly patients. Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Motor mechanisms of vertical fusion in individuals with superior oblique paresis.

PubMed

Mudgil, Ananth V; Walker, Mark; Steffen, Heimo; Guyton, David L; Zee, David S

2002-06-01

We wanted to determine the mechanisms of motor vertical fusion in patients with superior oblique paresis and to correlate these mechanisms with surgical outcomes. Ten patients with superior oblique paresis underwent 3-axis, bilateral, scleral search coil eye movement recordings. Eye movements associated with fusion were analyzed. Six patients had decompensated congenital superior oblique paresis and 4 had acquired superior oblique paresis. All patients with acquired superior oblique paresis relied predominantly on the vertical rectus muscles for motor fusion. Patients with congenital superior oblique paresis were less uniform in their mechanisms for motor fusion: 2 patients used predominantly the oblique muscles, 2 patients used predominantly the vertical recti, and 2 patients used predominantly the superior oblique in the hyperdeviated eye and the superior rectus in the hypodeviated eye. The last 2 patients developed the largest changes in torsional eye alignment relative to changes in vertical eye alignment and were the only patients to develop symptomatic surgical overcorrections. There are 3 different mechanisms for vertical fusion in individuals with superior oblique paresis, with the predominant mechanism being the vertical recti. A subset of patients with superior oblique paresis uses predominantly the superior oblique muscle in the hyperdeviated paretic eye and the superior rectus muscle in the fellow eye for fusion. This results in intorsion of both eyes, causing a large change in torsional alignment. The consequent cyclodisparity, in addition to the existing vertical deviation, may make fusion difficult. The differing patterns of vertical fusional vergence may have implications for surgical treatment.

Large-scale horizontally aligned ZnO microrod arrays with controlled orientation, periodic distribution as building blocks for chip-in piezo-phototronic LEDs.

PubMed

Guo, Zhen; Li, Haiwen; Zhou, Lianqun; Zhao, Dongxu; Wu, Yihui; Zhang, Zhiqiang; Zhang, Wei; Li, Chuanyu; Yao, Jia

2015-01-27

A novel method of fabricating large-scale horizontally aligned ZnO microrod arrays with controlled orientation and periodic distribution via combing technology is introduced. Horizontally aligned ZnO microrod arrays with uniform orientation and periodic distribution can be realized based on the conventional bottom-up method prepared vertically aligned ZnO microrod matrix via the combing method. When the combing parameters are changed, the orientation of horizontally aligned ZnO microrod arrays can be adjusted (θ = 90° or 45°) in a plane and a misalignment angle of the microrods (0.3° to 2.3°) with low-growth density can be obtained. To explore the potential applications based on the vertically and horizontally aligned ZnO microrods on p-GaN layer, piezo-phototronic devices such as heterojunction LEDs are built. Electroluminescence (EL) emission patterns can be adjusted for the vertically and horizontally aligned ZnO microrods/p-GaN heterojunction LEDs by applying forward bias. Moreover, the emission color from UV-blue to yellow-green can be tuned by investigating the piezoelectric properties of the materials. The EL emission mechanisms of the LEDs are discussed in terms of band diagrams of the heterojunctions and carrier recombination processes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-assembled vertically aligned Au nanorod arrays for surface-enhanced Raman scattering (SERS) detection of Cannabinol

NASA Astrophysics Data System (ADS)

Milliken, Sarah; Fraser, Jeff; Poirier, Shawn; Hulse, John; Tay, Li-Lin

2018-05-01

Self-assembled multi-layered vertically aligned gold nanorod (AuNR) arrays have been fabricated by a simple preparation process that requires a balance between the particle concentration and the ionic strength of the solvent. An experimentally determined critical AuNR concentration of 2.0 nM and 50 mM NaCl produces well-ordered vertically aligned hexagonally close-packed AuNR arrays. We demonstrate surface treatment via UV Ozone cleaning of such samples to allow introduction of analyte molecules (benzenethiol and cannabinol) for effective surface enhanced Raman scattering detection. This is the first demonstration of the SERS analysis of cannabinol. This approach demonstrates a cost-effective, high-yield and simple fabrication route to SERS sensors with application in the screening for the cannabinoids.

Improvement in device performance from a mixture of a liquid crystal and photosensitive acrylic prepolymer with the photoinduced vertical alignment method

PubMed Central

Ho, Czung-Yu; Lin, Fa-Hsin; Tao, Yu-Tai; Lee, Jiunn-Yih

2011-01-01

In a multicomponent nematic liquid crystal (NLC) mixture of a liquid crystal (negative-type NLC) and a photosensitive acrylic prepolymer, photopolymerization upon UV irradiation induces the separation of the LC and photosensitive acrylic prepolymer layers, thereby leading to a vertical arrangement of LC molecules. In this study, we propose a simple vertical alignment method for LC molecules, by adding a chiral smectic A (SmA∗) liquid crystal having homeotropic texture characteristics to an NLC mixture solution. Measurements of electro-optical properties revealed that the addition of the SmA∗ LC not only strengthened the anchoring force of the copolymer alignment film surface, but also significantly enhanced the contrast ratio (∼73%), response time and grayscale switching performance of the device. PMID:27877462

Fracture line morphology of complex proximal humeral fractures.

PubMed

Hasan, Afsana P; Phadnis, Joideep; Jaarsma, Ruurd L; Bain, Gregory I

2017-10-01

The aim of this study was to assess proximal humeral fracture patterns using 3-dimensional computed tomography images and relate them to the normal osseous landmarks and soft-tissue attachments. Forty-eight 3-dimensional computed tomography scans of proximal humeral fractures were retrospectively collected, and the fractures were transcribed onto proximal humeral templates. We analyzed the common location and orientation of the fracture lines, with a focus on fractures of the articular surface, tuberosities, metaphysis, and proximal diaphysis. These fractures were compared with the attachments of the rotator cuff and glenohumeral capsule. Fifty-two percent of the fractures involved the articular surface. No fractures passed through the bicipital groove, and fractures were more commonly found on the posterior lesser tuberosity and on the anterior greater tuberosity, coinciding with the intervals between the rotator cuff tendon insertions. Intracapsular fractures of the calcar were more common (68%) than extracapsular fractures (32%). On the anterolateral aspect of the proximal humerus, fractures radiated from the articular margin, vertically down through the tuberosity zone between the rotator cuff footprints, meeting horizontally oriented fractures in the metaphyseal zone. On the posterior aspect, vertical fractures from the tuberosity zone continued downward to the metaphyseal zone adjacent to the infraspinatus and teres minor footprints. Fractures of the proximal humerus follow characteristic patterns. Fractures frequently split the greater tuberosity and are closely related to the intervals of the rotator cuff attachments. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

Effects of cloud condensate vertical alignment on radiative transfer calculations in deep convective regions

NASA Astrophysics Data System (ADS)

Wang, Xiaocong

2017-04-01

Effects of cloud condensate vertical alignment on radiative transfer process were investigated using cloud resolving model explicit simulations, which provide a surrogate for subgrid cloud geometry. Diagnostic results showed that the decorrelation length Lcw varies in the vertical dimension, with larger Lcw occurring in convective clouds and smaller Lcw in cirrus clouds. A new parameterization of Lcw is proposed that takes into account such varying features and gives rise to improvements in simulations of cloud radiative forcing (CRF) and radiative heating, i.e., the peak of bias is respectively reduced by 8 W m- 2 for SWCF and 2 W m- 2 for LWCF in comparison with Lcw = 1 km. The role of Lcw in modulating CRFs is twofold. On the one hand, larger Lcw tends to increase the standard deviation of optical depth στ, as dense and tenuous parts of the clouds would be increasingly aligned in the vertical dimension, thereby broadening the probability distribution. On the other hand, larger στ causes a decrease in the solar albedo and thermal emissivity, as implied in their convex functions on τ. As a result, increasing (decreasing) Lcwleads to decreased (increased) CRFs, as revealed by comparisons among Lcw = 0, Lcw = 1 km andLcw = ∞. It also affects the vertical structure of radiative flux and thus influences the radiative heating. A better representation of στ in the vertical dimension yields an improved simulation of radiative heating. Although the importance of vertical alignment of cloud condensate is found to be less than that of cloud cover in regards to their impacts on CRFs, it still has enough of an effect on modulating the cloud radiative transfer process.

Separate vertical wiring for the fixation of comminuted fractures of the inferior pole of the patella.

PubMed

Song, Hyung Keun; Yoo, Je Hyun; Byun, Young Soo; Yang, Kyu Hyun

2014-05-01

Among patients over 50 years of age, separate vertical wiring alone may be insufficient for fixation of fractures of the inferior pole of the patella. Therefore, mechanical and clinical studies were performed in patients over the age of 50 to test the strength of augmentation of separate vertical wiring with cerclage wire (i.e., combined technique). Multiple osteotomies were performed to create four-part fractures in the inferior poles of eight pairs of cadaveric patellae. One patella from each pair was fixed with the separate wiring technique, while the other patella was fixed with a combined technique. The ultimate load to failure and stiffness of the fixation were subsequently measured. In a clinical study of 21 patients (average age of 64 years), comminuted fractures of the inferior pole of the patellae were treated using the combined technique. Operative parameters were recorded from which post-operative outcomes were evaluated. For cadaveric patellae, whose mean age was 69 years, the mean ultimate loads to failure for the separate vertical wiring technique and the combined technique were 216.4±72.4 N and 324.9±50.6 N, respectively (p=0.012). The mean stiffness for the separate vertical wiring technique and the combined technique was 241.1±68.5 N/mm and 340.8±45.3 N/mm, respectively (p=0.012). In the clinical study, the mean clinical score at final follow-up was 28.1 points. Augmentation of separate vertical wiring with cerclage wire provides enough strength for protected early exercise of the knee joint and uneventful healing.

Air-bridged Ohmic contact on vertically aligned si nanowire arrays: application to molecule sensors.

PubMed

Han, Hee; Kim, Jungkil; Shin, Ho Sun; Song, Jae Yong; Lee, Woo

2012-05-02

A simple, cost-effective, and highly reliable method for constructing an air-bridged electrical contact on large arrays of vertically aligned nanowires was developed. The present method may open up new opportunities for developing advanced nanowire-based devices for energy harvest and storage, power generation, and sensing applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Superior Thermal Interface via Vertically Aligned Carbon Nanotubes Grown on Graphite Foils

DTIC Science & Technology

2012-01-01

accepted 12 November 2012) In an attempt to study the thermal transport at the interface between nanotubes and graphene, vertically aligned multiwalled...tually increases the thermal barrier in a significant manner. On the other hand, thermal transport properties of thermal tapes and thermally conductive...aforementioned study achieved superior thermal transport properties, the processing and scale-up of the developed process would be prohibitively

Method of fabricating vertically aligned group III-V nanowires

DOEpatents

Wang, George T; Li, Qiming

2014-11-25

A top-down method of fabricating vertically aligned Group III-V micro- and nanowires uses a two-step etch process that adds a selective anisotropic wet etch after an initial plasma etch to remove the dry etch damage while enabling micro/nanowires with straight and smooth faceted sidewalls and controllable diameters independent of pitch. The method enables the fabrication of nanowire lasers, LEDs, and solar cells.

Beyond Scissors and Glue: Staff Developers Guide Teachers in Piecing Together a Vertically Aligned Curriculum and in Creating a Method to Get This Job Done

ERIC Educational Resources Information Center

Phelps, Vickie

2005-01-01

Layers and layers of curricula stuffed into vinyl binders were the norm in this Texas district until teachers sat down with scissors and glue to create a vertically aligned curriculum. They then created standards-based lessons to support the curriculum and put them into a database readily accessible by all.

SU-G-JeP3-02: Comparison of Magnitude and Frequency of Patient Positioning Errors in Breast Irradiation Using AlignRT 3D Optical Surface Imaging and Skin Mark Techniques

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

Yao, R; Chisela, W; Dorbu, G

2016-06-15

Purpose: To evaluate clinical usefulness of AlignRT (Vision RT Ltd., London, UK) in reducing patient positioning errors in breast irradiation. Methods: 60 patients undergoing whole breast irradiation were selected for this study. Patients were treated to the left or right breast lying on Qfix Access breast board (Qfix, Avondale, PA) in supine position for 28 fractions using tangential fields. 30 patients were aligned using AlignRT by aligning a breast surface region of interest (ROI) to the same area from a reference surface image extracted from planning CT. When the patient’s surface image deviated from the reference by more than 3mmmore » on one or more translational and rotational directions, a new reference was acquired using AlignRT in-room cameras. The other 30 patients were aligned to the skin marks with room lasers. On-Board MV portal images of medial field were taken daily and matched to the DRRs. The magnitude and frequency of positioning errors were determined from measured translational shifts. Kolmogorov-Smirnov test was used to evaluate statistical differences of positional accuracy and precision between AlignRT and non-AlignRT patients. Results: The percentage of port images with no shift required was 46.5% and 27.0% in vertical, 49.8% and 25.8% in longitudinal, 47.6% and 28.5% in lateral for AlignRT and non-AlignRT patients, respectively. The percentage of port images requiring more than 3mm shifts was 18.1% and 35.1% in vertical, 28.6% and 50.8% in longitudinal, 11.3% and 24.2% in lateral for AlignRT and non-AlignRT patients, respectively. Kolmogorov-Smirnov test showed that there were significant differences between the frequency distributions of AlignRT and non-AlignRT in vertical, longitudinal, and lateral shifts. Conclusion: As confirmed by port images, AlignRT-assisted patient positioning can significantly reduce the frequency and magnitude of patient setup errors in breast irradiation compared to the use of lasers and skin marks.« less

Coupled Hydro-mechanical process of natural fracture network formation in sedimentary basin

NASA Astrophysics Data System (ADS)

Ouraga, zady; Guy, Nicolas; Pouya, amade

2017-04-01

In sedimentary basin numerous phenomenon depending on the geological time span and its history can lead to a decrease in effective stress and therefore result in fracture initiation. Thus, during its formation, under certain conditions, natural fracturing and fracture network formation can occur in various context such as under erosion, tectonic loading and the compaction disequilibrium due to significant sedimentation rate. In this work, natural fracture network and fracture spacing induced by significant sedimentation rate is studied considering mode I fracture propagation, using a coupled hydro-mechanical numerical methods. Assumption of vertical fracture can be considered as a relevant hypothesis in our case of low ratio of horizontal total stress to vertical stress. A particular emphasis is put on synthetic geological structure on which a constant sedimentation rate is imposed on its top. This synthetic geological structure contains defects initially closed and homogeneously distributed. The Fractures are modeled with a constitutive model undergoing damage and the flow is described by poiseuille's law. The damage parameter affects both the mechanical and the hydraulic opening of the fracture. For the numerical simulations, the code Porofis based on finite element modeling is used, fractures are taken into account by cohesive model and the flow is described by Poiseuille's law. The effect of several parameters is also studied and the analysis lead to a fracture network and fracture spacing criterion for basin modeling.

Origin and timing of Dauphiné twins in quartz cement in fractured sandstones from diagenetic environments: Insight from fluid inclusions

NASA Astrophysics Data System (ADS)

Fall, András; Ukar, Estibalitz; Laubach, Stephen E.

2016-09-01

Electron backscattered diffraction techniques (EBSD) show that Dauphiné twins in quartz are widespread in many tectonometamorphic environments. Our study documents that under diagenetic temperatures (< 200 °C) and burial depths < 5 km Dauphiné twins are common in isolated fracture quartz deposits spanning between fracture walls (i.e., quartz bridges) in low-porosity quartz-cemented sandstones. Using examples from East Texas and Colorado cores, we show that twins are associated with crack-seal microstructure and fluid inclusions. Fracture wall-parallel and wall-normal inclusion trails contain coexisting aqueous and hydrocarbon gas inclusions, so homogenization temperatures of aqueous inclusions record true trapping temperatures. Inclusions in alignments normal to fracture walls are large and irregularly shaped compared to those aligned parallel to walls, but both show similar liquid-to-vapor ratios. Stacking transmitted light images with scanning electron microscope cathodoluminescence (SEM-CL) and EBSD images demonstrates that Dauphiné twin boundaries are localized along wall-normal inclusion trails. Trapping temperatures for wall-normal inclusion trails are usually higher than those aligned parallel to the fracture wall. Wall-normal fluid inclusion assemblage temperatures typically match the highest temperatures of wall-parallel assemblages trapped during sequential widening, but not necessarily the most recent. In context of burial histories for these samples, this temperature pattern implies that wall-normal assemblages form at discrete times during or after crack-seal fracture widening. Localization in isolated, potentially high-stress quartz deposits in fractures is compatible with a mechanical origin for these Dauphiné twins. Punctuated temperature values and discrepant sizes and shapes of inclusions in wall-normal trails implies that twinning is a by-product of the formation of the wall-normal inclusion assemblages. The association of Dauphiné twins and fluid inclusion assemblages from which temperature and possibly timing can be inferred provides a way to research timing as well as magnitude of paleostress in some diagenetic settings.

Alignment of x-ray tube focal spots for spectral measurement.

PubMed

Nishizawa, K; Maekoshi, H; Kamiya, Y; Kobayashi, Y; Ohara, K; Sakuma, S

1982-01-01

A general method to align a diagnostic x-ray machine for x-ray spectrum measurement purpose was theoretically and experimentally investigated by means of the optical alignment of focal pinhole images. Focal pinhole images were obtained by using a multi-pinholed lead plate. the vertical plane, including the central axis and tube axis, was decided upon by observing the symmetry of focal images. the central axis was designated as a line through the center of focus parallel to the target surface lying in the vertical plane. A method to determine the manipulation of the central axis in any direction is presented.

Fast-switching chiral nematic liquid-crystal mode with polymer-sustained twisted vertical alignment.

PubMed

Chang, Kai-Han; Joshi, Vinay; Chien, Liang-Chy

2017-04-01

We demonstrate a fast-switching liquid-crystal mode with polymer-sustained twisted vertical alignment. By optimizing the polymerization condition, a polymer microstructure with controlled orientation is produced. The polymer microstructure not only synergistically suppresses the optical bounce during field-induced homeotropic-twist transition but also shortens the response time significantly. Theoretical analyses validate that the ground state free energy density is modified by the aligning field of the polymer microstructure, which affects the driving voltage of the device. The outcomes of this paper will enable the development of fast-switching and achromatic electro-optical and photonic devices.

Fast-switching chiral nematic liquid-crystal mode with polymer-sustained twisted vertical alignment

NASA Astrophysics Data System (ADS)

Chang, Kai-Han; Joshi, Vinay; Chien, Liang-Chy

2017-04-01

We demonstrate a fast-switching liquid-crystal mode with polymer-sustained twisted vertical alignment. By optimizing the polymerization condition, a polymer microstructure with controlled orientation is produced. The polymer microstructure not only synergistically suppresses the optical bounce during field-induced homeotropic-twist transition but also shortens the response time significantly. Theoretical analyses validate that the ground state free energy density is modified by the aligning field of the polymer microstructure, which affects the driving voltage of the device. The outcomes of this paper will enable the development of fast-switching and achromatic electro-optical and photonic devices.

Comminuted inferior pole fracture of patella can be successfully treated with rim-plate-augmented separate vertical wiring.

PubMed

Cho, Jae-Woo; Kim, Jinil; Cho, Won-Tae; Gujjar, Pranay H; Oh, Chang-Wug; Oh, Jong-Keon

2018-02-01

We present the surgical technique of rim-plate-augmented separate vertical wiring for comminuted inferior pole fracture of the patella and report the clinical outcomes. Between July 2013 and January 2016, 13 patients (7 male and 6 female) who were diagnosed with comminuted inferior pole fracture of the patella in preoperative computed tomography and underwent a minimum of 1 year of follow-up were enrolled in this study. Mean patient age was 57.7 years (range 28-72 years). All patients underwent open reduction and internal fixation by rim-plate-augmented separate vertical wiring. Bony union, complications, range of motion and Bostman score were the clinical outcomes. Bony union was achieved in all cases at an average of 10 weeks after surgery (range 8-12). There was no loss of reduction and fixative failure during follow-up. The average range of motion was 127° (range 120°-130°). The mean Bostman score at last follow-up was 29.6 points (range 27-30) and graded excellent in 12 patients. Rim-plate-augmented separate vertical wiring demonstrated secure fixation and favorable clinical outcomes. This study provides evidence for its effectiveness as a fixation method for treating displaced, comminuted inferior pole fracture of the patella.

Internal fixation of displaced inferior pole of the patella fractures using vertical wiring augmented with Krachow suturing.

PubMed

Oh, Hyoung-Keun; Choo, Suk-Kyu; Kim, Ji-Wan; Lee, Mark

2015-12-01

We present the surgical technique of separate vertical wiring for displaced inferior pole fractures of the patella combined with Krachow suture and report the surgical outcomes. Between September 2007 to May 2012, 11 consecutive patients (mean age, 54.6 years) with inferior pole fractures of the patella (AO/OTA 34-A1) were retrospectively enrolled in this study. Through longitudinal incision, all patients underwent open reduction and internal fixation by separate vertical wiring combined with Krackow suture. The range of motion, loss of fixation, and Bostman score were primary outcome measures. The union time was 10 weeks after surgery on average (range: 8-12). No patient had nonunion, loss of reduction and wire breakage. There was no case of wound problem and irritation from the implant. At final follow-up, the average range of motion arc was 129.4° (range: 120-140). The mean Bostman score at last follow-up was 29.6 points (range: 28-30) and graded excellent in all cases. Separate vertical wiring combined with Krackow suture for inferior pole fractures of the patella is a useful technique that is easy to perform and can provide stable fixation with excellent results in knee function. Copyright © 2015 Elsevier Ltd. All rights reserved.

Changes in bone microstructure and toughness during the healing process of long bones

NASA Astrophysics Data System (ADS)

Ishimoto, T.; Nakano, T.; Umakoshi, Y.; Tabata, Y.

2009-05-01

It is of great importance to understand how bone defects regain the microstructure and mechanical function of bone and how the microstructure affects the mechanical function during the bone healing process. In the present study on long bone defects, we investigated the relationship between the recovery process of fracture toughness and biological apatite (BAp)/collagen (Col) alignment as an index of the bone microstructure to clarify the bone toughening mechanisms. A 5-mm defect introduced in the rabbit ulna was allowed to heal naturally and a three-point bending test was conducted on the regenerated site to assess bone toughness. The bone toughness was quite low at the early stage of bone regeneration but increased during the postoperative period. The change in toughness agreed well with the characteristics of the fracture surface morphology, which reflected the history of the crack propagation. SEM and microbeam X-ray diffraction analyses indicated that the toughness was dominated by the degree and orientation of the preferred BAp/Col alignment, i.e. bundles aligned perpendicular to the crack propagation clearly contributed to the bone toughening owing to extra energy consumption for resistance to crack propagation. In conclusion, regenerated bone improves fracture toughness by reconstructing the preferred BAp/Col alignment along the bone longitudinal axis during the healing process of long bones.

Diameter modulation of vertically aligned single-walled carbon nanotubes.

PubMed

Xiang, Rong; Einarsson, Erik; Murakami, Yoichi; Shiomi, Junichiro; Chiashi, Shohei; Tang, Zikang; Maruyama, Shigeo

2012-08-28

We demonstrate wide-range diameter modulation of vertically aligned single-walled carbon nanotubes (SWNTs) using a wet chemistry prepared catalyst. In order to ensure compatibility to electronic applications, the current minimum mean diameter of 2 nm for vertically aligned SWNTs is challenged. The mean diameter is decreased to about 1.4 nm by reducing Co catalyst concentrations to 1/100 or by increasing Mo catalyst concentrations by five times. We also propose a novel spectral analysis method that allows one to distinguish absorbance contributions from the upper, middle, and lower parts of a nanotube array. We use this method to quantitatively characterize the slight diameter change observed along the array height. On the basis of further investigation of the array and catalyst particles, we conclude that catalyst aggregation-rather than Ostwald ripening-dominates the growth of metal particles.

Self-assembled vertically aligned Au nanorod arrays for surface-enhanced Raman scattering (SERS) detection of Cannabinol.

PubMed

Milliken, Sarah; Fraser, Jeff; Poirier, Shawn; Hulse, John; Tay, Li-Lin

2018-05-05

Self-assembled multi-layered vertically aligned gold nanorod (AuNR) arrays have been fabricated by a simple preparation process that requires a balance between the particle concentration and the ionic strength of the solvent. An experimentally determined critical AuNR concentration of 2.0nM and 50mM NaCl produces well-ordered vertically aligned hexagonally close-packed AuNR arrays. We demonstrate surface treatment via UV Ozone cleaning of such samples to allow introduction of analyte molecules (benzenethiol and cannabinol) for effective surface enhanced Raman scattering detection. This is the first demonstration of the SERS analysis of cannabinol. This approach demonstrates a cost-effective, high-yield and simple fabrication route to SERS sensors with application in the screening for the cannabinoids. Copyright © 2018. Published by Elsevier B.V.

Nucleation, Growth Mechanism, and Controlled Coating of ZnO ALD onto Vertically Aligned N-Doped CNTs.

PubMed

Silva, R M; Ferro, M C; Araujo, J R; Achete, C A; Clavel, G; Silva, R F; Pinna, N

2016-07-19

Zinc oxide thin films were deposited on vertically aligned nitrogen-doped carbon nanotubes (N-CNTs) by atomic layer deposition (ALD) from diethylzinc and water. The study demonstrates that doping CNTs with nitrogen is an effective approach for the "activation" of the CNTs surface for the ALD of metal oxides. Conformal ZnO coatings are already obtained after 50 ALD cycles, whereas at lower ALD cycles an island growth mode is observed. Moreover, the process allows for a uniform growth from the top to the bottom of the vertically aligned N-CNT arrays. X-ray photoelectron spectroscopy demonstrates that ZnO nucleation takes place at the N-containing species on the surface of the CNTs by the formation of the Zn-N bonds at the interface between the CNTs and the ZnO film.

A methodology for using borehole temperature-depth profiles under ambient, single and cross-borehole pumping conditions to estimate fracture hydraulic properties

NASA Astrophysics Data System (ADS)

Klepikova, Maria V.; Le Borgne, Tanguy; Bour, Olivier; Davy, Philippe

2011-09-01

SummaryTemperature profiles in the subsurface are known to be sensitive to groundwater flow. Here we show that they are also strongly related to vertical flow in the boreholes themselves. Based on a numerical model of flow and heat transfer at the borehole scale, we propose a method to invert temperature measurements to derive borehole flow velocities. This method is applied to an experimental site in fractured crystalline rocks. Vertical flow velocities deduced from the inversion of temperature measurements are compared with direct heat-pulse flowmeter measurements showing a good agreement over two orders of magnitudes. Applying this methodology under ambient, single and cross-borehole pumping conditions allows us to estimate fracture hydraulic head and local transmissivity, as well as inter-borehole fracture connectivity. Thus, these results provide new insights on how to include temperature profiles in inverse problems for estimating hydraulic fracture properties.

Cornering characteristics of the main-gear tire of the space shuttle orbiter

NASA Technical Reports Server (NTRS)

Daugherty, Robert H.; Stubbs, Sandy M.; Robinson, Martha P.

1988-01-01

An experimental investigation was conducted at the NASA Langley Research Center to study the effects of various vertical load and yaw angle conditions on the cornering behavior of the Space Shuttle Orbiter main gear tire. Measured parameters included side and drag force, side and drag force coefficients, aligning torque, and overturning torque. Side force coefficient was found to increase as yaw angle was increased, but decreased as the vertical load was increased. Drag force was found to increase as vertical load was increased at constant yaw angles. Aligning torque measurements indicated that the tire is stable in yaw.

Fabrication of Single, Vertically Aligned Carbon Nanotubes in 3D Nanoscale Architectures

NASA Technical Reports Server (NTRS)

Kaul, Anupama B.; Megerian, Krikor G.; Von Allmen, Paul A.; Baron, Richard L.

2010-01-01

Plasma-enhanced chemical vapor deposition (PECVD) and high-throughput manufacturing techniques for integrating single, aligned carbon nanotubes (CNTs) into novel 3D nanoscale architectures have been developed. First, the PECVD growth technique ensures excellent alignment of the tubes, since the tubes align in the direction of the electric field in the plasma as they are growing. Second, the tubes generated with this technique are all metallic, so their chirality is predetermined, which is important for electronic applications. Third, a wafer-scale manufacturing process was developed that is high-throughput and low-cost, and yet enables the integration of just single, aligned tubes with nanoscale 3D architectures with unprecedented placement accuracy and does not rely on e-beam lithography. Such techniques should lend themselves to the integration of PECVD grown tubes for applications ranging from interconnects, nanoelectromechanical systems (NEMS), sensors, bioprobes, or other 3D electronic devices. Chemically amplified polyhydroxystyrene-resin-based deep UV resists were used in conjunction with excimer laser-based (lambda = 248 nm) step-and-repeat lithography to form Ni catalyst dots = 300 nm in diameter that nucleated single, vertically aligned tubes with high yield using dc PECVD growth. This is the first time such chemically amplified resists have been used, resulting in the nucleation of single, vertically aligned tubes. In addition, novel 3D nanoscale architectures have been created using topdown techniques that integrate single, vertically aligned tubes. These were enabled by implementing techniques that use deep-UV chemically amplified resists for small-feature-size resolution; optical lithography units that allow unprecedented control over layer-to-layer registration; and ICP (inductively coupled plasma) etching techniques that result in near-vertical, high-aspect-ratio, 3D nanoscale architectures, in conjunction with the use of materials that are structurally and chemically compatible with the high-temperature synthesis of the PECVD-grown tubes. The techniques offer a wafer-scale process solution for integrating single PECVD-grown nanotubes into novel architectures that should accelerate their integration in 3D electronics in general. NASA can directly benefit from this technology for its extreme-environment planetary missions. Current Si transistors are inherently more susceptible to high radiation, and do not tolerate extremes in temperature. These novel 3D nanoscale architectures can form the basis for NEMS switches that are inherently less susceptible to radiation or to thermal extremes.

Vertically-aligned carbon nanotubes on aluminum as a light-weight positive electrode for lithium-polysulfide batteries.

PubMed

Liatard, S; Benhamouda, K; Fournier, A; Ramos, R; Barchasz, C; Dijon, J

2015-05-04

A light-weight, high specific surface current collector made of vertically-aligned carbon nanotubes grown on an aluminum substrate was fabricated and studied as a positive electrode in a semi-liquid lithium/polysulfide battery. This simple system delivered stable capacities over 1000 mA h gS(-1) and 2 mA h cm(-2) with almost no capacity loss over 50 cycles.

Vertically aligned carbon nanotubes for microelectrode arrays applications.

PubMed

Castro Smirnov, J R; Jover, Eric; Amade, Roger; Gabriel, Gemma; Villa, Rosa; Bertran, Enric

2012-09-01

In this work a methodology to fabricate carbon nanotube based electrodes using plasma enhanced chemical vapour deposition has been explored and defined. The final integrated microelectrode based devices should present specific properties that make them suitable for microelectrode arrays applications. The methodology studied has been focused on the preparation of highly regular and dense vertically aligned carbon nanotube (VACNT) mat compatible with the standard lithography used for microelectrode arrays technology.

High-performance Supercapacitors Based on Electrochemical-induced Vertical-aligned Carbon Nanotubes and Polyaniline Nanocomposite Electrodes

NASA Astrophysics Data System (ADS)

Wu, Guan; Tan, Pengfeng; Wang, Dongxing; Li, Zhe; Peng, Lu; Hu, Ying; Wang, Caifeng; Zhu, Wei; Chen, Su; Chen, Wei

2017-03-01

Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density. Here we report a high-performance supercapacitor based on polyaniline/vertical-aligned carbon nanotubes (PANI/VA-CNTs) nanocomposite electrodes where the vertical-aligned-structure is formed by the electrochemical-induction (0.75 V). The supercapacitor displays large specific capacitance of 403.3 F g-1, which is 6 times higher than disordered CNTs in HClO4 electrolyte. Additionally, the supercapacitor can also present high specific capacitance (314.6 F g-1), excellent cycling stability (90.2% retention after 3000 cycles at 4 A g-1) and high energy density (98.1 Wh kg-1) in EMIBF4 organic electrolyte. The key to high-performance lies in the vertical-aligned-structure providing direct path channel for ion faster diffusion and high electrochemical capacitance of polyaniline for ion more accommodation.

High-performance field emission device utilizing vertically aligned carbon nanotubes-based pillar architectures

NASA Astrophysics Data System (ADS)

Gupta, Bipin Kumar; Kedawat, Garima; Gangwar, Amit Kumar; Nagpal, Kanika; Kashyap, Pradeep Kumar; Srivastava, Shubhda; Singh, Satbir; Kumar, Pawan; Suryawanshi, Sachin R.; Seo, Deok Min; Tripathi, Prashant; More, Mahendra A.; Srivastava, O. N.; Hahm, Myung Gwan; Late, Dattatray J.

2018-01-01

The vertical aligned carbon nanotubes (CNTs)-based pillar architectures were created on laminated silicon oxide/silicon (SiO2/Si) wafer substrate at 775 °C by using water-assisted chemical vapor deposition under low pressure process condition. The lamination was carried out by aluminum (Al, 10.0 nm thickness) as a barrier layer and iron (Fe, 1.5 nm thickness) as a catalyst precursor layer sequentially on a silicon wafer substrate. Scanning electron microscope (SEM) images show that synthesized CNTs are vertically aligned and uniformly distributed with a high density. The CNTs have approximately 2-30 walls with an inner diameter of 3-8 nm. Raman spectrum analysis shows G-band at 1580 cm-1 and D-band at 1340 cm-1. The G-band is higher than D-band, which indicates that CNTs are highly graphitized. The field emission analysis of the CNTs revealed high field emission current density (4mA/cm2 at 1.2V/μm), low turn-on field (0.6 V/μm) and field enhancement factor (6917) with better stability and longer lifetime. Emitter morphology resulting in improved promising field emission performances, which is a crucial factor for the fabrication of pillared shaped vertical aligned CNTs bundles as practical electron sources.

High-performance Supercapacitors Based on Electrochemical-induced Vertical-aligned Carbon Nanotubes and Polyaniline Nanocomposite Electrodes.

PubMed

Wu, Guan; Tan, Pengfeng; Wang, Dongxing; Li, Zhe; Peng, Lu; Hu, Ying; Wang, Caifeng; Zhu, Wei; Chen, Su; Chen, Wei

2017-03-08

Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density. Here we report a high-performance supercapacitor based on polyaniline/vertical-aligned carbon nanotubes (PANI/VA-CNTs) nanocomposite electrodes where the vertical-aligned-structure is formed by the electrochemical-induction (0.75 V). The supercapacitor displays large specific capacitance of 403.3 F g -1 , which is 6 times higher than disordered CNTs in HClO 4 electrolyte. Additionally, the supercapacitor can also present high specific capacitance (314.6 F g -1 ), excellent cycling stability (90.2% retention after 3000 cycles at 4 A g -1 ) and high energy density (98.1 Wh kg -1 ) in EMIBF 4 organic electrolyte. The key to high-performance lies in the vertical-aligned-structure providing direct path channel for ion faster diffusion and high electrochemical capacitance of polyaniline for ion more accommodation.

High-performance Supercapacitors Based on Electrochemical-induced Vertical-aligned Carbon Nanotubes and Polyaniline Nanocomposite Electrodes

PubMed Central

Wu, Guan; Tan, Pengfeng; Wang, Dongxing; Li, Zhe; Peng, Lu; Hu, Ying; Wang, Caifeng; Zhu, Wei; Chen, Su; Chen, Wei

2017-01-01

Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density. Here we report a high-performance supercapacitor based on polyaniline/vertical-aligned carbon nanotubes (PANI/VA-CNTs) nanocomposite electrodes where the vertical-aligned-structure is formed by the electrochemical-induction (0.75 V). The supercapacitor displays large specific capacitance of 403.3 F g−1, which is 6 times higher than disordered CNTs in HClO4 electrolyte. Additionally, the supercapacitor can also present high specific capacitance (314.6 F g−1), excellent cycling stability (90.2% retention after 3000 cycles at 4 A g−1) and high energy density (98.1 Wh kg−1) in EMIBF4 organic electrolyte. The key to high-performance lies in the vertical-aligned-structure providing direct path channel for ion faster diffusion and high electrochemical capacitance of polyaniline for ion more accommodation. PMID:28272474

Active and passive seismic imaging of a hydraulic fracture in diatomite

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

Vinegar, H.J.; Wills, P.B.; De Martini, D.C.

1992-01-01

This paper reports on a comprehensive set of experiments including remote- and treatment-well microseismic monitoring, interwell shear-wave shadowing, and surface tiltmeter arrays, that was used to monitor the growth of a hydraulic fracture in the Belridge diatomite. To obtain accurate measurements, and extensive subsurface network of geophones was cemented spanning the diatomite formation in three closely spaced observation wells around the well to be fracture treated. Data analysis indicates that the minifracture and main hydraulic fracture stimulations resulted in a nearly vertical fracture zone (striking N26{degrees}E) vertically segregated into two separate elements, the uppermost of which grew 60 ft abovemore » the perforated interval. The interwell seismic effects are consistent with a side process zone of reduced shear velocity, which remote-well microseismic data independently suggest may be as wide as 40 ft. The experiments indicate complicated processes occurring during hydraulic fracturing that have significant implications for stimulation, waterflooding, in fill drilling, and EOR. These processes are neither well understood nor included in current hydraulic fracture models.« less

A Viscoplastic Stress Relaxation Model for Predicting Variations of the Least Principal Stress With Depth in Unconventional Reservoirs

NASA Astrophysics Data System (ADS)

Zoback, M. D.; Xu, S.; Rassouli, F.; Ma, X.

2016-12-01

In this paper we extend the viscoplastic stress relaxation model of Sone and Zoback (Jour. Petrol. Sci. and Eng., 2014) for predicting variations of least principal stress with stress and its impact on the vertical propagation of hydraulic fractures. Viscoplastic stress relaxation in clay-rich (or diagenetically immature) sedimentary rocks makes the stress field more isotropic. In normal faulting and strike-slip faulting environments, this causes the least principal stress to increase making such formations likely barriers to vertical hydraulic fracture growth. In order to predict the magnitude of viscoplastic stress relaxation in different unconventional formations, we generalize a constitutive law developed from a wide range of creep experiments in our lab over the past several years and apply it to areas of stacked pay in Oklahoma and Texas. Using frac gradients were measured from minifrac and DFIT (Diagnostic Fracture Injection Test) experiments. The viscoplastic model does a good job of explaining vertical hydraulic fracture propagation, as indicated by the distribution of microseismic events recorded during stimulation.

Separate Vertical Wiring for the Fixation of Comminuted Fractures of the Inferior Pole of the Patella

PubMed Central

Song, Hyung Keun; Yoo, Je Hyun; Byun, Young Soo

2014-01-01

Purpose Among patients over 50 years of age, separate vertical wiring alone may be insufficient for fixation of fractures of the inferior pole of the patella. Therefore, mechanical and clinical studies were performed in patients over the age of 50 to test the strength of augmentation of separate vertical wiring with cerclage wire (i.e., combined technique). Materials and Methods Multiple osteotomies were performed to create four-part fractures in the inferior poles of eight pairs of cadaveric patellae. One patella from each pair was fixed with the separate wiring technique, while the other patella was fixed with a combined technique. The ultimate load to failure and stiffness of the fixation were subsequently measured. In a clinical study of 21 patients (average age of 64 years), comminuted fractures of the inferior pole of the patellae were treated using the combined technique. Operative parameters were recorded from which post-operative outcomes were evaluated. Results For cadaveric patellae, whose mean age was 69 years, the mean ultimate loads to failure for the separate vertical wiring technique and the combined technique were 216.4±72.4 N and 324.9±50.6 N, respectively (p=0.012). The mean stiffness for the separate vertical wiring technique and the combined technique was 241.1±68.5 N/mm and 340.8±45.3 N/mm, respectively (p=0.012). In the clinical study, the mean clinical score at final follow-up was 28.1 points. Conclusion Augmentation of separate vertical wiring with cerclage wire provides enough strength for protected early exercise of the knee joint and uneventful healing. PMID:24719149

40 CFR 146.83 - Minimum criteria for siting.

Code of Federal Regulations, 2012 CFR

2012-07-01

... or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide... without initiating or propagating fractures in the confining zone(s). (b) The Director may require owners... vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for...

40 CFR 146.83 - Minimum criteria for siting.

Code of Federal Regulations, 2014 CFR

2014-07-01

... or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide... without initiating or propagating fractures in the confining zone(s). (b) The Director may require owners... vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for...

40 CFR 146.83 - Minimum criteria for siting.

Code of Federal Regulations, 2013 CFR

2013-07-01

... or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide... without initiating or propagating fractures in the confining zone(s). (b) The Director may require owners... vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for...

40 CFR 146.83 - Minimum criteria for siting.

Code of Federal Regulations, 2011 CFR

2011-07-01

... or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide... without initiating or propagating fractures in the confining zone(s). (b) The Director may require owners... vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for...

Topographically induced homeotropic alignment of liquid crystals on self-assembled opal crystals.

PubMed

Kumar, Pankaj; Oh, Su Yeon; Baliyan, Vijay K; Kundu, Sudarshan; Lee, Seung Hee; Kang, Shin-Woong

2018-04-02

The surface of multilayered opal crystals resulted in homeotropic alignment of liquid crystal (LC), originated from the surface topography of opal crystals rather than a chemical nature of the nanoparticles. The polar anchoring energy (5.51 × 10 -5 J/m 2 ) of the crystal surface for nematic LC molecules was in a similar range to the conventional polyimide alignment layer (2.11 × 10 -5 J/m 2 ) used for commercial applications. The critical length scale for anchoring transition was approximately Lw = ~1 μm. If a diameter of particle d < 1 μm for opal crystals, LC molecules preferred to anchor vertically to the surface to minimize elastic free energy of bulk LCs. The LC favored a planar anchoring if d > 1 μm. The results provide crucial insights to understand the homeotropic alignment of LCs on solid surfaces and therefore offer opportunities to develop novel materials for a vertical alignment of LCs.

A successful treatment of vertical root fracture: a case report and 4-year follow-up.

PubMed

Oztürk, Mine; Unal, Gül Celik

2008-10-01

This case report describes a successful treatment of vertically fractured tooth which was reconstructed with a self-etching dual-cured adhesive resin cement and intentionally replanted without using rotation in conjunction with a bio-absorbable barrier membrane. At a follow-up consultation 4 years later, the tooth was asymptomatic, and attachment gain and bone regeneration were observed. In addition, no ankylosis was detected clinically or radiographically.

Experimental analysis of multiple factors on hydraulic fracturing in coalbed methane reservoirs

PubMed Central

Ma, Geng; Liu, Xiao; Tao, Yunqi; Feng, Dan; Li, Rui

2018-01-01

Hydraulic fracturing can improve the permeability of coalbed methane (CBM) reservoirs effectively, which is of great significance to the commercial production of CBM. However, the efficiency of hydraulic fracturing is affected by multiple factors. The mechanism of fracture initiation, morphology and propagation in CBM reservoirs is not clear and need to be further explored. Hydraulic fracturing experiment is an accurate tool to explore these mechanisms. The quantity of experimental coal rock is large and processing method is complex, so specimen made of similar materials was applied to replace coal rock. The true triaxial hydraulic fracturing experimental apparatus, 3D scanning device for coal rock section were applied to carry out hydraulic fracturing experiment. The results show that the initiation pressure is inversely proportional to the horizontal stress difference (Δσ) and positively related to fracturing fluid injection rate. When vertical stress (σv) is constant, the initiation pressure and fracture width decrease with the increasing of Δσ. Natural fractures can be connected by main fracture when propagates perpendicular to the direction of minimum horizontal stress (σh), then secondary fractures and fracture network form in CBM reservoirs. When two stresses of crustal stress are close and far different from the third one, the fracture morphology and propagation become complex. Influenced by perforations and filtration of fracturing fluid in specimen, fracturing fluid flows to downward easily after comparing horizontal well fracturing with vertical well fracturing. Fracture width increases with the decreasing of elastic modulus, the intensity of fracture is positively related with the elastic modulus of coal rock. The research results can provide theoretical basis and technical support for the efficient development of CBM. PMID:29621295

Experimental analysis of multiple factors on hydraulic fracturing in coalbed methane reservoirs.

PubMed

Zhang, Fan; Ma, Geng; Liu, Xiao; Tao, Yunqi; Feng, Dan; Li, Rui

2018-01-01

Hydraulic fracturing can improve the permeability of coalbed methane (CBM) reservoirs effectively, which is of great significance to the commercial production of CBM. However, the efficiency of hydraulic fracturing is affected by multiple factors. The mechanism of fracture initiation, morphology and propagation in CBM reservoirs is not clear and need to be further explored. Hydraulic fracturing experiment is an accurate tool to explore these mechanisms. The quantity of experimental coal rock is large and processing method is complex, so specimen made of similar materials was applied to replace coal rock. The true triaxial hydraulic fracturing experimental apparatus, 3D scanning device for coal rock section were applied to carry out hydraulic fracturing experiment. The results show that the initiation pressure is inversely proportional to the horizontal stress difference (Δσ) and positively related to fracturing fluid injection rate. When vertical stress (σv) is constant, the initiation pressure and fracture width decrease with the increasing of Δσ. Natural fractures can be connected by main fracture when propagates perpendicular to the direction of minimum horizontal stress (σh), then secondary fractures and fracture network form in CBM reservoirs. When two stresses of crustal stress are close and far different from the third one, the fracture morphology and propagation become complex. Influenced by perforations and filtration of fracturing fluid in specimen, fracturing fluid flows to downward easily after comparing horizontal well fracturing with vertical well fracturing. Fracture width increases with the decreasing of elastic modulus, the intensity of fracture is positively related with the elastic modulus of coal rock. The research results can provide theoretical basis and technical support for the efficient development of CBM.

Pediatric Ankle Fractures: Concepts and Treatment Principles

PubMed Central

Su, Alvin W.; Larson, A. Noelle

2016-01-01

Synopsis Current clinical concepts are reviewed regarding the epidemiology, anatomy, evaluation and treatment of pediatric ankle fractures. Correct diagnosis and management relies on appropriate exam, imaging, and knowledge of fracture patterns specific to children. Treatment is guided by patient history, physical examination, plain film radiographs and, in some instances, CT. Treatment goals are to restore acceptable limb alignment, physeal anatomy, and joint congruency. For high risk physeal fractures, patients should be monitored for growth disturbance as needed until skeletal maturity. PMID:26589088

Vertically aligned carbon nanotubes black coatings from roll-to-roll deposition process

NASA Astrophysics Data System (ADS)

Goislard de Monsabert, Thomas; Papciak, L.; Sangar, A.; Descarpentries, J.; Vignal, T.; de Longiviere, Xavier; Porterat, D.; Mestre, Q.; Hauf, H.

2017-09-01

Vertically aligned carbon nanotubes (VACNTs) have recently attracted growing interest as a very efficient light absorbing material over a broad spectral range making them a superior coating in space optics applications such as radiometry, optical calibration, and stray light elimination. However, VACNT coatings available to-date most often result from batch-to-batch deposition processes thus potentially limiting the manufacturing repeatability, substrate size and cost efficiency of this material.

Vertically aligned carbon nanotube emitter on metal foil for medical X-ray imaging.

PubMed

Ryu, Je Hwang; Kim, Wan Sun; Lee, Seung Ho; Eom, Young Ju; Park, Hun Kuk; Park, Kyu Chang

2013-10-01

A simple method is proposed for growing vertically aligned carbon nanotubes on metal foil using the triode direct current plasma-enhanced chemical vapor deposition (PECVD). The carbon nanotube (CNT) electron emitter was fabricated using fewer process steps with an acid treated metal substrate. The CNT emitter was used for X-ray generation, and the X-ray image of mouse's joint was obtained with an anode current of 0.5 mA at an anode bias of 60 kV. The simple fabrication of a well-aligned CNT with a protection layer on metal foil, and its X-ray application, were studied.

Uniform, dense arrays of vertically aligned, large-diameter single-walled carbon nanotubes.

PubMed

Han, Zhao Jun; Ostrikov, Kostya

2012-04-04

Precisely controlled reactive chemical vapor synthesis of highly uniform, dense arrays of vertically aligned single-walled carbon nanotubes (SWCNTs) using tailored trilayered Fe/Al(2)O(3)/SiO(2) catalyst is demonstrated. More than 90% population of thick nanotubes (>3 nm in diameter) can be produced by tailoring the thickness and microstructure of the secondary catalyst supporting SiO(2) layer, which is commonly overlooked. The proposed model based on the atomic force microanalysis suggests that this tailoring leads to uniform and dense arrays of relatively large Fe catalyst nanoparticles on which the thick SWCNTs nucleate, while small nanotubes and amorphous carbon are effectively etched away. Our results resolve a persistent issue of selective (while avoiding multiwalled nanotubes and other carbon nanostructures) synthesis of thick vertically aligned SWCNTs whose easily switchable thickness-dependent electronic properties enable advanced applications in nanoelectronic, energy, drug delivery, and membrane technologies.

Thin Polymer Films with Continuous Vertically Aligned 1 nm Pores Fabricated by Soft Confinement

DOE PAGES

Feng, Xunda; Nejati, Siamak; Cowan, Matthew G.; ...

2015-12-03

Membrane separations are critically important in areas ranging from health care and analytical chemistry to bioprocessing and water purification. An ideal nanoporous membrane would consist of a thin film with physically continuous and vertically aligned nanopores and would display a narrow distribution of pore sizes. However, the current state of the art departs considerably from this ideal and is beset by intrinsic trade-offs between permeability and selectivity. We demonstrate an effective and scalable method to fabricate polymer films with ideal membrane morphologies consisting of submicron thickness films with physically continuous and vertically aligned 1 nm pores. The approach is basedmore » on soft confinement to control the orientation of a cross-linkable mesophase in which the pores are produced by self-assembly. The scalability, exceptional ease of fabrication, and potential to create a new class of nanofiltration membranes stand out as compelling aspects.« less

Effect of retained fractured instruments on tooth resistance to vertical fracture with or without attempt at removal.

PubMed

Madarati, A A; Qualtrough, A J E; Watts, D C

2010-11-01

To investigate the effect of retained fractured endodontic instruments on root strength and to evaluate the effectiveness of several root filling materials in reinforcing roots that had undergone unsuccessful attempt at removal of fractured instruments. Seventy five mandibular premolar roots were divided into five groups. In group A (control), canals were prepared to a size F5-ProTaper instrument and filled with gutta-percha and TubliSeal sealer fragments. In the experimental groups (B, C, D and E), 4 mm of F5-ProTaper instruments were fractured in the apical one-third of the canal and then treated as follows: in group B, the fragments were left in situ without attempt at removal, and canals were filled with gutta-percha and TubliSeal sealer (GP No Removal). In groups C, D and E, an attempt at removal of the fragment was simulated by preparing a staging platform coronal to the fragment using modified Gates Glidden burs (No 2-5). Canals in group C were filled with gutta-percha and TubliSeal sealer (GP Removal), group D filled with Resilon (Resilon Removal) and group E with mineral trioxide aggregate (MTA Removal). Roots then underwent vertical fracture. Data were analysed using the one-way anova at P<0.05. Roots in the GP Removal group had significantly lower values for mean force for fracture (404.9 N). There was no significant difference between the control group and GP No Removal (765.2 and 707.8, respectively). Resilon Removal and MTA Removal groups (577.3 and 566.6 N) were not significantly different from the GP No Removal group. Leaving fractured instruments in the apical one-third of the canal does not appear to affect the resistance of the root to vertical fracture; Resilon and MTA appear to compensate for root dentine loss that occurred as a consequence of attempts at retrieval of fractured instruments when used as canal filling materials. © 2010 International Endodontic Journal.

Improvement of spinal alignment and quality of life after corrective surgery for spinal kyphosis in patients with osteoporosis: a comparative study with non-operated patients.

PubMed

Miyakoshi, N; Hongo, M; Kobayashi, T; Abe, T; Abe, E; Shimada, Y

2015-11-01

This study evaluated changes in spinal alignment and quality of life (QOL) after corrective spinal surgery for patients with postmenopausal osteoporosis and spinal kyphosis. Spinal global alignment and QOL were significantly improved after corrective spinal surgery but did not reach the level of non-operated controls. With the increased aging of society, the demand for corrective spinal instrumentation for spinal kyphosis in osteoporotic patients is increasing. However, previous studies have not focused on the improvement of quality of life (QOL) after corrective spinal surgery in patients with osteoporosis, compared to non-operated control patients. The purposes of this study were thus to evaluate changes in spinal alignment and QOL after corrective spinal instrumentation for patients with osteoporosis and spinal kyphosis and to compare these results with non-operated patients. Participants comprised 39 patients with postmenopausal osteoporosis ≥50 years old who underwent corrective spinal surgery using multilevel posterior lumbar interbody fusion (PLIF) for symptomatic thoracolumbar or lumbar kyphosis, and 82 age-matched patients with postmenopausal osteoporosis without prevalent vertebral fractures. Spinopelvic parameters were evaluated with standing lateral spine radiography, and QOL was evaluated with the Japanese Osteoporosis QOL Questionnaire (JOQOL), SF-36, and Roland-Morris Disability Questionnaire (RDQ). Lumbar kyphosis angle, sagittal vertical axis, and pelvic tilt were significantly improved postoperatively. QOL evaluated with all three questionnaires also significantly improved after 6 months postoperatively, particularly in domain and subscale scores for pain and general/mental health. However, these radiographic parameters, total JOQOL score, SF-36 physical component summary score, and RDQ score were significantly inferior compared with non-operated controls. The results indicate that spinal global alignment and QOL were significantly improved after corrective spinal surgery using multilevel PLIF for patients with osteoporosis and spinal kyphosis but did not reach the level of non-operated controls.

Stochastic Ground Water Flow Simulation with a Fracture Zone Continuum Model

USGS Publications Warehouse

Langevin, C.D.

2003-01-01

A method is presented for incorporating the hydraulic effects of vertical fracture zones into two-dimensional cell-based continuum models of ground water flow and particle tracking. High hydraulic conductivity features are used in the model to represent fracture zones. For fracture zones that are not coincident with model rows or columns, an adjustment is required for the hydraulic conductivity value entered into the model cells to compensate for the longer flowpath through the model grid. A similar adjustment is also required for simulated travel times through model cells. A travel time error of less than 8% can occur for particles moving through fractures with certain orientations. The fracture zone continuum model uses stochastically generated fracture zone networks and Monte Carlo analysis to quantify uncertainties with simulated advective travel times. An approach is also presented for converting an equivalent continuum model into a fracture zone continuum model by establishing the contribution of matrix block transmissivity to the bulk transmissivity of the aquifer. The methods are used for a case study in west-central Florida to quantify advective travel times from a potential wetland rehydration site to a municipal supply wellfield. Uncertainties in advective travel times are assumed to result from the presence of vertical fracture zones, commonly observed on aerial photographs as photolineaments.

Vertically-aligned Mn(OH) 2 nanosheet films for flexible all-solid-state electrochemical supercapacitors

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

Yang, Ziyuan; Gong, Jiangfeng; Tang, Chunmei

We report that the arrangement of the electrode materials is a significant contributor for constructing high performance supercapacitor. Here, vertically-aligned Mn(OH) 2 nanosheet thin films were synthesized by cathodic electrodeposition technique on flexible Au coated polyethylene terephthalate substrates. Morphologies, microstructures, chemical compositions and valence state of the nanosheet films were characterized systematically. It shows that the nanosheets arranged vertically to the substrate, forming a porous nanowall structures and creating large open framework, which greatly facilitate the adsorption or diffusion of electrolyte ions for faradaic redox reaction. Electrochemical tests of the films show the specific capacitance as high as 240.2 Fmore » g -1 at 1.0 A g -1. The films were employed to assemble symmetric all-solid-state supercapacitors with LiCl/PVA gel severed as solid electrolyte. Finally, the solid devices exhibit high volumetric capacitance of 39.3 mF cm -3 at the current density 0.3 mA cm -3 with robust cycling stability. The superior performance is attributed to the vertically-aligned configuration.« less

Vertically-aligned Mn(OH) 2 nanosheet films for flexible all-solid-state electrochemical supercapacitors

DOE PAGES

Yang, Ziyuan; Gong, Jiangfeng; Tang, Chunmei; ...

2017-08-28

We report that the arrangement of the electrode materials is a significant contributor for constructing high performance supercapacitor. Here, vertically-aligned Mn(OH) 2 nanosheet thin films were synthesized by cathodic electrodeposition technique on flexible Au coated polyethylene terephthalate substrates. Morphologies, microstructures, chemical compositions and valence state of the nanosheet films were characterized systematically. It shows that the nanosheets arranged vertically to the substrate, forming a porous nanowall structures and creating large open framework, which greatly facilitate the adsorption or diffusion of electrolyte ions for faradaic redox reaction. Electrochemical tests of the films show the specific capacitance as high as 240.2 Fmore » g -1 at 1.0 A g -1. The films were employed to assemble symmetric all-solid-state supercapacitors with LiCl/PVA gel severed as solid electrolyte. Finally, the solid devices exhibit high volumetric capacitance of 39.3 mF cm -3 at the current density 0.3 mA cm -3 with robust cycling stability. The superior performance is attributed to the vertically-aligned configuration.« less

Similar Fracture Patterns in Human Nose and Gothic Cathedral.

PubMed

Lee, Shu Jin; Tse, Kwong Ming; Lee, Heow Pueh

2015-10-01

This study proposes that the bony anatomy of the human nose and masonry structure of the Gothic cathedral are geometrically similar, and have common fracture patterns. We also aim to correlate the fracture patterns observed in patients' midface structures with those seen in the Gothic cathedral using computational approach. CT scans of 33 patients with facial fractures were examined and compared with computer simulations of both the Gothic cathedral and human nose. Three similar patterns were found: (1) Cracks of the nasal arch with crumpling of the vertical buttresses akin to the damage seen during minor earthquakes; (2) lateral deviation of the central nasal arch and collapse of the vertical buttresses akin to those due to lateral forces from wind and in major earthquakes; and (3) Central arch collapse seen as a result of collapse under excessive dead weight. Interestingly, the finding of occult nasal and septal fractures in the mandible fractures with absence of direct nasal trauma highlights the possibility of transmission of forces from the foundation to the arch leading to structural failure. It was also found that the structural buttresses of the Gothic cathedral delineate the vertical buttresses in the human midface structure. These morphologic similarities between the human nose and Gothic cathedral will serve as a basis to study the biomechanics of nasal fractures. Identification of structural buttresses in a skeletal structure has important implications for reconstruction as reestablishment of structural continuity restores normal anatomy and architectural stability of the human midface structure. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

High voltage electrophoretic deposition for electrochemical energy storage and other applications

NASA Astrophysics Data System (ADS)

Santhanagopalan, Sunand

High voltage electrophoretic deposition (HVEPD) has been developed as a novel technique to obtain vertically aligned forests of one-dimensional nanomaterials for efficient energy storage. The ability to control and manipulate nanomaterials is critical for their effective usage in a variety of applications. Oriented structures of one-dimensional nanomaterials provide a unique opportunity to take full advantage of their excellent mechanical and electrochemical properties. However, it is still a significant challenge to obtain such oriented structures with great process flexibility, ease of processing under mild conditions and the capability to scale up, especially in context of efficient device fabrication and system packaging. This work presents HVEPD as a simple, versatile and generic technique to obtain vertically aligned forests of different one-dimensional nanomaterials on flexible, transparent and scalable substrates. Improvements on material chemistry and reduction of contact resistance have enabled the fabrication of high power supercapacitor electrodes using the HVEPD method. The investigations have also paved the way for further enhancements of performance by employing hybrid material systems and AC/DC pulsed deposition. Multi-walled carbon nanotubes (MWCNTs) were used as the starting material to demonstrate the HVEPD technique. A comprehensive study of the key parameters was conducted to better understand the working mechanism of the HVEPD process. It has been confirmed that HVEPD was enabled by three key factors: high deposition voltage for alignment, low dispersion concentration to avoid aggregation and simultaneous formation of holding layer by electrodeposition for reinforcement of nanoforests. A set of suitable parameters were found to obtain vertically aligned forests of MWCNTs. Compared with their randomly oriented counterparts, the aligned MWCNT forests showed better electrochemical performance, lower electrical resistance and a capability to achieve superhydrophpbicity, indicating their potential in a broad range of applications. The versatile and generic nature of the HVEPD process has been demonstrated by achieving deposition on flexible and transparent substrates, as well as aligned forests of manganese dioxide (MnO2) nanorods. A continuous roll-printing HVEPD approach was then developed to obtain aligned MWCNT forest with low contact resistance on large, flexible substrates. Such large-scale electrodes showed no deterioration in electrochemical performance and paved the way for practical device fabrication. The effect of a holding layer on the contact resistance between aligned MWCNT forests and the substrate was studied to improve electrochemical performance of such electrodes. It was found that a suitable precursor salt like nickel chloride could be used to achieve a conductive holding layer which helped to significantly reduce the contact resistance. This in turn enhanced the electrochemical performance of the electrodes. High-power scalable redox capacitors were then prepared using HVEPD. Very high power/energy densities and excellent cyclability have been achieved by synergistically combining hydrothermally synthesized, highly crystalline α-MnO 2 nanorods, vertically aligned forests and reduced contact resistance. To further improve the performance, hybrid electrodes have been prepared in the form of vertically aligned forest of MWCNTs with branches of α-MnO 2 nanorods on them. Large- scale electrodes with such hybrid structures were manufactured using continuous HVEPD and characterized, showing further improved power and energy densities. The alignment quality and density of MWCNT forests were also improved by using an AC/DC pulsed deposition technique. In this case, AC voltage was first used to align the MWCNTs, followed by immediate DC voltage to deposit the aligned MWCNTs along with the conductive holding layer. Decoupling of alignment from deposition was proven to result in better alignment quality and higher electrochemical performance.

Vertical decomposition with Genetic Algorithm for Multiple Sequence Alignment

PubMed Central

2011-01-01

Background Many Bioinformatics studies begin with a multiple sequence alignment as the foundation for their research. This is because multiple sequence alignment can be a useful technique for studying molecular evolution and analyzing sequence structure relationships. Results In this paper, we have proposed a Vertical Decomposition with Genetic Algorithm (VDGA) for Multiple Sequence Alignment (MSA). In VDGA, we divide the sequences vertically into two or more subsequences, and then solve them individually using a guide tree approach. Finally, we combine all the subsequences to generate a new multiple sequence alignment. This technique is applied on the solutions of the initial generation and of each child generation within VDGA. We have used two mechanisms to generate an initial population in this research: the first mechanism is to generate guide trees with randomly selected sequences and the second is shuffling the sequences inside such trees. Two different genetic operators have been implemented with VDGA. To test the performance of our algorithm, we have compared it with existing well-known methods, namely PRRP, CLUSTALX, DIALIGN, HMMT, SB_PIMA, ML_PIMA, MULTALIGN, and PILEUP8, and also other methods, based on Genetic Algorithms (GA), such as SAGA, MSA-GA and RBT-GA, by solving a number of benchmark datasets from BAliBase 2.0. Conclusions The experimental results showed that the VDGA with three vertical divisions was the most successful variant for most of the test cases in comparison to other divisions considered with VDGA. The experimental results also confirmed that VDGA outperformed the other methods considered in this research. PMID:21867510

[Separate vertical wiring combined with tension band and Kirschner-wire plus cerclage wire in the treatment of displaced inferior pole fractures of the patella].

PubMed

Zhang, J; Jiang, X Y; Huang, X W

2016-06-18

To investigate the clinical efficacy and outcomes of two separate vertical wiring combined with tension band and Kirschner-wire plus cerclage wire in the treatment of displaced inferior pole fractures of the patella. From January 2013 to January 2015, 15 consecutive patients (mean age 54.5 years) with inferior pole fractures of the patella were retrospectively included in this study. All the patients underwent open reduction and internal fixation by separate vertical wiring combined with tension band and Kirschner-wire plus cerclage wire through longitudinal incision, 4.5 d (range: 3.1-5.9 d) after initial injury. A safety check for early knee range of motion was performed before wound closure. The complications including infection, nonunion, loss of fixation and any wire breakage or irritation from implant were recorded. Anteroposterior and lateral views of the knee joint obtained during the follow-up were used to assess bony union based on the time when the fracture line disappeared. At the time of the final outpatient follow up, functional evaluation of the knee joint was conducted by Bostman system. The follow-up time was 13.1 months (range: 12-19 months) after surgery on average, immediate motion without immobilization in all the cases was allowed and there was no case of reduction loss of the fracture and wire breakage. There was no case of irritation from the implant. At the final follow-up, the average range of motion (ROM) arc was 126.7° (range: 115°-140°), the average ROM lag versus contralateral healthy leg was 10.3° (range: 0°-35°). The mean Bostman score at the last follow-up was 28.9 (range: 27-30), and graded excellent in most cases. Two separate vertical wiring is an easy and effective method to reduce the displaced inferior pole fracture of patella. Augmentation of separate vertical wiring with tension band and Kirschner-wire plus cerclage wire in these patients provides enough strength to protected the early exercise of the knee joint and uneventful healing. By this surgical treatment, excellent results in knee function can be expected for cases of displaced inferior pole fractures of the patella.

Comparative study between biologic plating and intramedullary nailing for the treatment of subtrochanteric fractures: Is biologic plating using LCP-DF superior to intramedullary nailing?

PubMed

Shin, Won Chul; Moon, Nam Hoon; Jang, Jae Hoon; Lee, Hee Jin; Suh, Kuen Tak

2017-10-01

The objective of this study is to evaluate the outcome measures of subtrochanteric fractures between biologic plating and intramedullary nailing and determine if biologic plating is superior to intramedullary nailing. Between March 2009 and December 2015, 81 patients with subtrochanteric fractures were enrolled (52 males and 29 females; 31 treated with biologic plating and 50 with intramedullary nailing). Biologic plating was conducted consecutively between May 2011 and March 2013 and intramedullary nailing was performed for the rest of period. Perioperative outcomes including operation time and blood loss during the operation; postoperative radiologic outcomes including union, time to union, coronal alignment, and shortening of the femur; and clinical outcomes including walking ability and pain were evaluated. The biologic plating group was compared with the intramedullary nailing group as a historical control. No significant differences were identified for bony union and time to union between the two different fixation methods Coronal alignment was significantly better in the biologic plating group than in the intramedullary nailing group (p<0.016). Postoperative coronal alignment was the only risk factor associated with the nonunion of subtrochanteric fractures (unadjusted OR: 1.915, 95% CI: 0.190 - 19.273; adjusted OR: 0.042, 95% CI: 0.000 - 21.517; p=0.320). Surgical outcomes using LCP-DF are comparable to those using intramedullary nailing. Further clinical studies with a larger sample size are required to show the advantage of biologic plating for the treatment of subtrochanteric fractures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bovine xenograft application for treatment of a metatarsal nonunion fracture in an alpaca (Vicugna pacos).

PubMed

Longo, F; Finotti, L; Bellini, L; Zavan, B; Busetto, R; Isola, M

2016-05-01

A 15-year-old female huacaya alpaca (Vicugna pacos) was referred because of a non-weight-bearing lameness (4/4) in the left pelvic limb caused by a grade three open metatarsal fracture. The referring veterinarian treated the fracture with conservative management using bandages, but it progressively evolved to a non-union. Clinical examination revealed external wounds on the medial and lateral surfaces of the metatarsus. Radiographs confirmed an open, nonarticular, displaced, diaphyseal fracture of the left metatarsus. Cancellous bone was sourced from bovine proximal and distal femur epiphyses, followed by a thermal shock procedure to achieve decellularisation, to produce a xenograft. Open reduction and internal fixation of the fracture using locking plates was performed. Alignment of the fracture fragments was corrected and the xenograft was placed at the debrided fracture site to stimulate and harness osteogenesis in situ. Clinical and radiographic follow-up was performed up to 40 weeks postoperatively. Clinical evaluations revealed that the alpaca gradually increased weight bearing following bandage removal 10 days after surgery. Serial radiographs showed correct alignment of the left metatarsus, progressive bone modelling and, complete bone union at 12 weeks. Ten months postoperatively the alpaca showed no signs of lameness and resumed normal activity. For management of a metatarsal non-union, a combination of bovine xenograft application and angular stable internal fixation progressed toward an excellent long-term recovery.

Development of the T+M coupled flow–geomechanical simulator to describe fracture propagation and coupled flow–thermal–geomechanical processes in tight/shale gas systems

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

Kim, Jihoon; Moridis, George J.

2013-10-01

We developed a hydraulic fracturing simulator by coupling a flow simulator to a geomechanics code, namely T+M simulator. Modeling of the vertical fracture development involves continuous updating of the boundary conditions and of the data connectivity, based on the finite element method for geomechanics. The T+M simulator can model the initial fracture development during the hydraulic fracturing operations, after which the domain description changes from single continuum to double or multiple continua in order to rigorously model both flow and geomechanics for fracture-rock matrix systems. The T+H simulator provides two-way coupling between fluid-heat flow and geomechanics, accounting for thermoporomechanics, treatsmore » nonlinear permeability and geomechanical moduli explicitly, and dynamically tracks changes in the fracture(s) and in the pore volume. We also fully accounts for leak-off in all directions during hydraulic fracturing. We first validate the T+M simulator, matching numerical solutions with the analytical solutions for poromechanical effects, static fractures, and fracture propagations. Then, from numerical simulation of various cases of the planar fracture propagation, shear failure can limit the vertical fracture propagation of tensile failure, because of leak-off into the reservoirs. Slow injection causes more leak-off, compared with fast injection, when the same amount of fluid is injected. Changes in initial total stress and contributions of shear effective stress to tensile failure can also affect formation of the fractured areas, and the geomechanical responses are still well-posed.« less

Designing a monitoring network for contaminated ground water in fractured chalk

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

Nativ, R.; Adar, E.M.; Becker, A.

1999-01-01

One of the challenges of monitoring network design in a fractured rock setting is the heterogeneity of the rocks. This paper summarizes the activities and problems associated with the monitoring of contaminated groundwater in porous, low-permeability fractured chalk in the Negev Desert, Israel. Preferential flow documented in the study area required siting the monitoring boreholes in the predominant fracture systems. Lineaments traced from aerial photographs were examined in the field to sort out the large-extension, through-going, multilayer fracture systems crossing the study area. At each proposed drilling site, these fractures were exposed below the sediment cover using trenches. Slanted boreholesmore » were drilled at a distance from the fracture systems so that each borehole would intersect the targeted fracture plane below the water table. Based on their short recovery period and contaminated ground water, these newly drilled, fracture-oriented boreholes appeared to be better connected to preferential flowpaths crossing the industrial site than the old boreholes existing on site. Other considerations concerning the drilling and logging of monitoring boreholes in a fractured media were: (1) coring provides better documentation of the vertical fracture distribution, but dry augering is less costly and enables immediate ground water sampling and the sampling of vadose rock for contaminant analysis; (2) caliper and TV camera logs appear to provide only partial information regarding the vertical fracture distribution; and (3) the information gained by deepening the monitoring boreholes and testing fractures crossing their uncased walls has to be carefully weighed against the risk of potential cross-contamination through the monitoring boreholes, which is enhanced in fractured media.« less

Simulation of ground-water flow to assess geohydrologic factors and their effect on source-water areas for bedrock wells in Connecticut

USGS Publications Warehouse

Starn, J. Jeffrey; Stone, Janet Radway

2005-01-01

Generic ground-water-flow simulation models show that geohydrologic factors?fracture types, fracture geometry, and surficial materials?affect the size, shape, and location of source-water areas for bedrock wells. In this study, conducted by the U.S. Geological Survey in cooperation with the Connecticut Department of Public Health, ground-water flow was simulated to bedrock wells in three settings?on hilltops and hillsides with no surficial aquifer, in a narrow valley with a surficial aquifer, and in a broad valley with a surficial aquifer?to show how different combinations of geohydrologic factors in different topographic settings affect the dimensions and locations of source-water areas in Connecticut. Three principal types of fractures are present in bedrock in Connecticut?(1) Layer-parallel fractures, which developed as partings along bedding in sedimentary rock and compositional layering or foliation in metamorphic rock (dips of these fractures can be gentle or steep); (2) unroofing joints, which developed as strain-release fractures parallel to the land surface as overlying rock was removed by erosion through geologic time; and (3) cross fractures and joints, which developed as a result of tectonically generated stresses that produced typically near-vertical or steeply dipping fractures. Fracture geometry is defined primarily by the presence or absence of layering in the rock unit, and, if layered, by the angle of dip in the layering. Where layered rocks dip steeply, layer-parallel fracturing generally is dominant; unroofing joints also are typically well developed. Where layered rocks dip gently, layer-parallel fracturing also is dominant, and connections among these fractures are provided only by the cross fractures. In gently dipping rocks, unroofing joints generally do not form as a separate fracture set; instead, strain release from unroofing has occurred along gently dipping layer-parallel fractures, enhancing their aperture. In nonlayered and variably layered rocks, layer-parallel fracturing is absent or poorly developed; fracturing is dominated by well-developed subhorizontal unroofing joints and steeply dipping, tectonically generated fractures and (or) cooling joints. Cross fractures (or cooling joints) in nonlayered and variably layered rocks have more random orientations than in layered rocks. Overall, nonlayered or variably layered rocks do not have a strongly developed fracture direction. Generic ground-water-flow simulation models showed that fracture geometry and other geohydrologic factors affect the dimensions and locations of source-water areas for bedrock wells. In general, source-water areas to wells reflect the direction of ground-water flow, which mimics the land-surface topography. Source-water areas to wells in a hilltop setting were not affected greatly by simulated fracture zones, except for an extensive vertical fracture zone. Source-water areas to wells in a hillside setting were not affected greatly by simulated fracture zones, except for the combination of a subhorizontal fracture zone and low bedrock vertical hydraulic conductivity, as might be the case where an extensive subhorizontal fracture zone is not connected or is poorly connected to the surface through vertical fractures. Source-water areas to wells in a narrow valley setting reflect complex ground-water-flow paths. The typical flow path originates in the uplands and passes through either till or bedrock into the surficial aquifer, although only a small area of the surficial aquifer actually contributes water to the well. Source-water areas in uplands can include substantial areas on both sides of a river. Source-water areas for wells in this setting are affected mainly by the rate of ground-water recharge and by the degree of anisotropy. Source-water areas to wells in a broad valley setting (bedrock with a low angle of dip) are affected greatly by fracture properties. The effect of a given fracture is to channel the

Geometrical appearance and spatial arrangement of structural blocks of the Malan loess in NW China: implications for the formation of loess columns

NASA Astrophysics Data System (ADS)

Li, Yanrong; Zhang, Tao; Zhang, Yongbo; Xu, Qiang

2018-06-01

Loess, as one of the main Quaternary deposits, covers approximately 6% of the land surface of the Earth. Although loess is loose and fragile, loess columns are popular and they can stand stably for hundreds of years, thereby forming a spectacular landform. The formation of such special column-shaped soil structures is puzzling, and the underlying fundamentals remain unclear. The present study focuses on quantifying and examining the geometrical shape and spatial alignment of structural blocks of the Malan loess at different locations in the Loess Plateau of China. The structural blocks under investigation include clay- and silt-sized particles, aggregates, fragments, lumps, and columns, which vary in size from microns to tens of meters. Regardless of their size, the structural blocks of the Malan loess are found to be similar in shape, i.e., elongated with a length-to-width ratio of approximately 2.6. The aggregates, fragments, lumps, columns, and macropores between aggregates exhibit strong concentration in the vertical or subvertical alignment. These phenomena imply that the Malan loess is anisotropic and it is composed of a combination of vertically aligned strong units and vertically aligned weak segments. Based on this, "vertiloess" structure is proposed to denote this combination. The vertiloess structure prevents horizontal erosion, but favors spalling, peeling, toppling, falling and cracking-sliding of vertical loess pieces, thereby forming loess columns.

Octahedral Tin Dioxide Nanocrystals Anchored on Vertically Aligned Carbon Aerogels as High Capacity Anode Materials for Lithium-Ion Batteries.

PubMed

Liu, Mingkai; Liu, Yuqing; Zhang, Yuting; Li, Yiliao; Zhang, Peng; Yan, Yan; Liu, Tianxi

2016-08-11

A novel binder-free graphene - carbon nanotubes - SnO2 (GCNT-SnO2) aerogel with vertically aligned pores was prepared via a simple and efficient directional freezing method. SnO2 octahedrons exposed of {221} high energy facets were uniformly distributed and tightly anchored on multidimensional graphene/carbon nanotube (GCNT) composites. Vertically aligned pores can effectively prevent the emersion of "closed" pores which cannot load the active SnO2 nanoparticles, further ensure quick immersion of electrolyte throughout the aerogel, and can largely shorten the transport distance between lithium ions and active sites of SnO2. Especially, excellent electrical conductivity of GCNT-SnO2 aerogel was achieved as a result of good interconnected networks of graphene and CNTs. Furthermore, meso- and macroporous structures with large surface area created by the vertically aligned pores can provide great benefit to the favorable transport kinetics for both lithium ion and electrons and afford sufficient space for volume expansion of SnO2. Due to the well-designed architecture of GCNT-SnO2 aerogel, a high specific capacity of 1190 mAh/g with good long-term cycling stability up to 1000 times was achieved. This work provides a promising strategy for preparing free-standing and binder-free active electrode materials with high performance for lithium ion batteries and other energy storage devices.

Octahedral Tin Dioxide Nanocrystals Anchored on Vertically Aligned Carbon Aerogels as High Capacity Anode Materials for Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Liu, Mingkai; Liu, Yuqing; Zhang, Yuting; Li, Yiliao; Zhang, Peng; Yan, Yan; Liu, Tianxi

2016-08-01

A novel binder-free graphene - carbon nanotubes - SnO2 (GCNT-SnO2) aerogel with vertically aligned pores was prepared via a simple and efficient directional freezing method. SnO2 octahedrons exposed of {221} high energy facets were uniformly distributed and tightly anchored on multidimensional graphene/carbon nanotube (GCNT) composites. Vertically aligned pores can effectively prevent the emersion of “closed” pores which cannot load the active SnO2 nanoparticles, further ensure quick immersion of electrolyte throughout the aerogel, and can largely shorten the transport distance between lithium ions and active sites of SnO2. Especially, excellent electrical conductivity of GCNT-SnO2 aerogel was achieved as a result of good interconnected networks of graphene and CNTs. Furthermore, meso- and macroporous structures with large surface area created by the vertically aligned pores can provide great benefit to the favorable transport kinetics for both lithium ion and electrons and afford sufficient space for volume expansion of SnO2. Due to the well-designed architecture of GCNT-SnO2 aerogel, a high specific capacity of 1190 mAh/g with good long-term cycling stability up to 1000 times was achieved. This work provides a promising strategy for preparing free-standing and binder-free active electrode materials with high performance for lithium ion batteries and other energy storage devices.

FRACOR-software toolbox for deterministic mapping of fracture corridors in oil fields on AutoCAD platform

NASA Astrophysics Data System (ADS)

Ozkaya, Sait I.

2018-03-01

Fracture corridors are interconnected large fractures in a narrow sub vertical tabular array, which usually traverse entire reservoir vertically and extended for several hundreds of meters laterally. Fracture corridors with their huge conductivities constitute an important element of many fractured reservoirs. Unlike small diffuse fractures, actual fracture corridors must be mapped deterministically for simulation or field development purposes. Fracture corridors can be identified and quantified definitely with borehole image logs and well testing. However, there are rarely sufficient image logs or well tests, and it is necessary to utilize various fracture corridor indicators with varying degrees of reliability. Integration of data from many different sources, in turn, requires a platform with powerful editing and layering capability. Available commercial reservoir characterization software packages, with layering and editing capabilities, can be cost intensive. CAD packages are far more affordable and may easily acquire the versatility and power of commercial software packages with addition of a small software toolbox. The objective of this communication is to present FRACOR, a software toolbox which enables deterministic 2D fracture corridor mapping and modeling on AutoCAD platform. The FRACOR toolbox is written in AutoLISPand contains several independent routines to import and integrate available fracture corridor data from an oil field, and export results as text files. The resulting fracture corridor maps consists mainly of fracture corridors with different confidence levels from combination of static and dynamic data and exclusion zones where no fracture corridor can exist. The exported text file of fracture corridors from FRACOR can be imported into an upscaling programs to generate fracture grid for dual porosity simulation or used for field development and well planning.

Annealed Au-assisted epitaxial growth of si nanowires: control of alignment and density.

PubMed

Park, Yi-Seul; Jung, Da Hee; Kim, Hyun Ji; Lee, Jin Seok

2015-04-14

The epitaxial growth of 1D nanostructures is of particular interest for future nanoelectronic devices such as vertical field-effect transistors because it directly influences transistor densities and 3D logic or memory architectures. Silicon nanowires (SiNWs) are a particularly important 1D nanomaterial because they possess excellent electronic and optical properties. What is more, the scalable fabrication of vertically aligned SiNW arrays presents an opportunity for improved device applications if suitable properties can be achieved through controlling the alignment and density of SiNWs, yet this is something that has not been reported in the case of SiNWs synthesized from Au films. This work therefore explores the controllable synthesis of vertically aligned SiNWs through the introduction of an annealing process prior to growth via a Au-catalyzed vapor-liquid-solid mechanism. The epitaxial growth of SiNWs was demonstrated to be achievable using SiCl4 as the Si precursor in chemical vapor deposition, whereas the alignment and density of the SiNWs could be controlled by manipulating the annealing time during the formation of Au nanoparticles (AuNPs) from Au films. During the annealing process, gold silicide was observed to form on the interface of the liquid-phase AuNPs, depending on the size of the AuNPs and the annealing time. This work therefore makes a valuable contribution to improving nanowire-based engineering by controlling its alignment and density as well as providing greater insight into the epitaxial growth of 1D nanostructures.

Evaluation of Hydraulically Significant Discontinuities in Dockum Group Mudrocks in Andrews County, Texas

NASA Astrophysics Data System (ADS)

Holt, R. M.; Kuszmaul, J. S.; Cao, S.; Powers, D. W.

2013-12-01

Triassic mudrocks of the Dockum Group (Cooper Canyon Formation) host four, below-grade landfills at the Waste Control Specialists (WSC) site in Andrews County, Texas, including: a hazardous waste landfill and three radioactive waste landfills. At the study site, the Dockum consists of mudrocks with sparse siltstone/sandstone interbeds that developed in a semi-arid environment from an ephemeral meandering fluvial system. Sedimentary studies reveal that the mudrocks are ancient floodplain vertisols (soils with swelling clays) and siltstone/sandstone interbeds are fluvial channel deposits that were frequently subaerially exposed. Rock discontinuities, including fractures and syndepositional slickensided surfaces, were mapped during the excavation of the WCS radioactive waste landfills along vertical faces prepared by the construction contractor. Face locations were selected to insure a sampled area with nearly complete vertical coverage for each landfill. Individual discontinuities were mapped and their strike, dip, length, roughness, curvature, staining, and evidence of displacement were described. In the three radioactive waste disposal landfills, over 1750 discontinuities across 35 excavated faces were mapped and described, where each face was nominally 8 to 10 ft tall and 50 to 100 ft long. Genetic units related to paleosol development were identified. On average, the orientation of the discontinuities was horizontal, and no other significant trends were observed. Mapping within the landfill excavations shows that most discontinuities within Dockum rocks are horizontal, concave upward, slickensided surfaces that developed in the depositional environment, as repeated wetting and drying cycles led to shrinking and swelling of floodplain vertisols. Fractures that showed staining (a possible indicator of past or present hydraulic activity) are rare, vertical to near-vertical, and occur mainly in, and adjacent to, mechanically stiff siltstone and sandstone interbeds. No interconnected fracture networks were observed during mapping. A series of pressurized air tests conducted in three pairs of vertical and three pairs of inclined boreholes were tested at depths, ranging from 40 to 215 feet below ground surface, also showed no evidence of fracture interconnection. Genetic units generally consist of fining upward sequences that show increasing pedogenic alteration upward. Arcuate, slickensided discontinuities are more abundant near the top of genetic units, while stained fractures are more common in the more mechanically competent materials near the base of genetic units. A statistical analysis of fractures and discontinuities revealed limited differences between most genetic units. A series of discrete fracture network models were developed to evaluate the uncertainty in our fracture observations. Slickensided discontinuities showing no evidence of staining or past fluid movement were excluded from the analysis. Monte Carlo simulations show no continuous fracture interconnections across the landfill depth intervals.

Internal fixation of pilon fractures of the distal radius.

PubMed Central

Trumble, T. E.; Schmitt, S. R.; Vedder, N. B.

1993-01-01

When closed manipulation fails to restore articular congruity in comminuted, displaced fractures of the distal radius, open reduction and internal fixation is required. Results of surgical stabilization and articular reconstruction of these injuries are reviewed in this retrospective study of 49 patients with 52 displaced, intra-articular distal radius fractures. Forty-three patients (87%) with a mean age of 37 years (range of 17 to 79 years) were available for evaluation. The mean follow-up time was 38 months (range 22-69 months). When rated according to the Association for the Study of Internal Fixation (ASIF), 19 were type C2 and 21 were type C3. We devised an Injury Score System based on the initial injury radiographs to classify severely comminuted intra-articular fractures and to identify those associated with carpal injury (3 patients). Post-operative fracture alignment, articular congruity, and radial length were significantly improved following surgery (p < .01). Grip strength averaged 69% +/- 22% of the contralateral side, and the range of motion averaged 75% +/- 18% of the contralateral side post-operatively. A combined outcome rating system that included grip strength, range of motion, and pain relief averaged 76% +/- 19% of the contralateral side. There was a statistically significant decrease in the combined rating with more severe fracture patterns as defined by the ASIF system (p < .01), Malone classification (p < .03), and the Injury Score System (p < .001). The Injury Score System presented here, and in particular the number of fracture fragments, correlated most closely with outcome of all the classification systems studied. Operative treatment of these distal radius fractures with reconstruction of the articular congruity and correction of the articular surface alignment with internal fixation and/or external fixation, can significantly improve the radiographic alignment and functional outcome. Furthermore, the degree to which articular stepoff, gap between fragments, and radial shortening are improved by surgery is strongly correlated with improved outcome, even when the results are corrected for severity of initial injury, whereas correction of radial tilt or dorsal tilt did not correlate with improved outcome. Images Figure 2 PMID:8209554

Advances in Permeable Reactive Barrier Technologies

DTIC Science & Technology

2002-08-01

technical methods, such as jetting and hydraulic fracturing , has improved the ability to access deeper aquifers. Table 1 describes the established and...34, Cape Canaveral Air Station, FL. Hydraulic Fracturing 120 A series of wells are installed along the length of the PRB. A vertical fracture is...especially helpful with deep instal- lation methods, such as hydraulic fracturing , where the barrier installed is just a few inches thick. A second, new type

Microfractures in bed-parallel veins (beef) as predictors of vertical macrofractures in shale: Vaca Muerta Formation, Agrio Fold-and-Thrust Belt, Argentina

NASA Astrophysics Data System (ADS)

Ukar, Estibalitz; Lopez, Ramiro G.; Laubach, Stephen E.; Gale, Julia F. W.; Manceda, René; Marrett, Randall

2017-11-01

Shales of the Upper Jurassic-Lower Cretaceous Vaca Muerta Formation are the main source rock for petroleum in the Neuquén Basin, Argentina and an important unconventional exploration target. Folded Vaca Muerta Formation is well exposed in the Agrio Fold-and-Thrust belt where an arid climate and rapid erosion reveal relatively unweathered shale strata accessible along creek beds at Arroyo Mulichinco and in 10+ m-tall cliffs at Puesto. Widespread within these organic-rich shales are several cm-thick, prominent bed-parallel veins (BPVs) of fibrous calcite (beef) that are cut by multiple sets of vertical calcite lined or filled fractures having apertures unaffected by near-surface stress release. Similar, and probably contemporaneous fractures are present within horizons of interbedded dolomitic rock. Evidence that vertical fractures in BPVs and dolomitic horizons continue into shale beds suggests that in-depth analysis of vertical fractures within BPVs and dolomitic horizons allows fracture set and orientation identification and size population measurements-primarily aperture distributions-that circumvent some of the limitations of shale outcrops. At Arroyo Mulichinco, four main fracture sets are present separable by orientation and crosscutting relations. An E-W set is oldest, followed by successively younger NE-SW, NW-SE, and N-S sets. At Puesto, the E-W and N-S sets are the most prominent and show opposite cross-cutting relationships (E-W set is youngest) indicating a possible episode of younger E-W fractures. The E-W set shows the highest micro-and macrofracture intensity at both localities. The intensity of N-S micro- and macrofractures is similar at both outcrops away from faults, but macrofracture intensity increases closer to faults. While macrofracture abundance is similar in BPVs and in shale, microfractures having apertures smaller than ∼0.1 mm are mostly absent in shale and dolomitic layers but are abundant cutting BPVs. Thus, microfractures are BPV-bounded and only fractures wider than ∼0.05 mm are tall enough to cut into shale. Nevertheless, using size distributions of microfractures in BPVs that are absent in shale accurately predicts the abundance of macrofractures in nearby shale, either because microfractures in organic shale have annealed, or because of only small differences in fracture strain for fractures of different sizes across different rocks types. Microfractures in readily sampled BPVs may be a practical way to diagnose or predict attributes of macrofractures in adjacent shale.

Resistance to vertical fracture of MTA-filled roots.

PubMed

EL-Ma'aita, Ahmad M; Qualtrough, Alison J E; Watts, David C

2014-02-01

To investigate the effect of MTA root canal fillings on the resistance to vertical root fracture (VRF) over different time intervals. Freshly extracted anterior human teeth with single canals and minimal curvatures were decoronated, instrumented to size 50/.05 ProTaper file, irrigated with 1%NaOCl and randomly allocated to one of three groups (n = 36): (i) filled with MTA, (ii) filled with gutta-percha and sealer and (iii) unfilled roots used as a negative control. Each group was subdivided into three subgroups (n = 12) according to the storage time of 48 h, 1 and 6 months at 37°C in synthetic tissue fluid (STF). Following the storage periods, filled roots were mounted in acrylic supports, and the periodontal ligament was simulated using elastomeric impression material. Vertical loading was carried out with a ball-ended steel cylinder fitted on a universal testing machine at 1 mm/min crosshead speed. The maximum force at fracture (F-max) and the fracture mode were recorded for each root. Data were statistically analysed using two-way anova and Bonferroni post hoc tests. The mean F-max was significantly higher in the MTA subgroups after 1 and 6 months compared with all other subgroups. Two modes of fracture were identified: split and comminuted. The mean F-max values recorded with the latter were significantly higher compared with the former (P < 0.001). In all groups, split fracture was the most dominant mode apart from the MTA/1 month and MTA/6 month groups. MTA increases the resistance to VRF of endodontically treated teeth and influences the mode of fracture after 1 and 6 month of storage in STF compared with gutta-percha and sealer. © 2013 John Wiley & Sons A/S.

Composite Bone and Soft Tissue Loss Treated with Distraction Histiogenesis

DTIC Science & Technology

2010-01-01

their frames removed had healed docking sites, and the fourth whose frame remained in place had a healing fracture without evidence of delayed union ...interventions (3–8). The goals of limb salvage surgery in this setting are to restore length and alignment, regenerate bone loss, obtain fracture union ...angulation to manage composite bone and soft tissue loss associated with combat-related type IIIB open tibia fractures . Four patients underwent placement

Initial growth of vertically aligned carbon nanofibers

NASA Astrophysics Data System (ADS)

Cui, Hongtao; Yang, Xiaojing; Simpson, Michael L.; Lowndes, Douglas H.; Varela, Maria

2004-05-01

Samples of vertically aligned carbon nanofibers (VACNFs) were viewed transverse to the growth direction and studied using both scanning and transmission electron microscopy. The VACNFs are composed of graphite layers nearly parallel to the substrate at their bottom end, gradually formed graphite "cups" in the main body, and a catalyst particle on the tip. The formation of such structure is due to the corresponding transformation of the shape of the catalyst particle during initial VACNF growth. A model for their initial growth is proposed.

Four-probe charge transport measurements on individual vertically aligned carbon nanofibers

NASA Astrophysics Data System (ADS)

Zhang, Lan; Austin, Derek; Merkulov, Vladimir I.; Meleshko, Anatoli V.; Klein, Kate L.; Guillorn, Michael A.; Lowndes, Douglas H.; Simpson, Michael L.

2004-05-01

We report four-probe I-V measurements on individual vertically aligned carbon nanofibers (VACNFs). These measurements were enabled by the fabrication of multiple Ti/Au ohmic contacts on individual fibers that exhibited resistance of only a few kilohms. These measurements demonstrate that VACNFs exhibit linear I-V behavior at room temperature, with a resistivity of approximately 4.2×10-3 Ω cm. Our measurements are consistent with a dominant transport mechanism of electrons traveling through intergraphitic planes in the VACNFs.

Vertically aligned carbon nanofibers as sacrificial templates for nanofluidic structures

NASA Astrophysics Data System (ADS)

Melechko, A. V.; McKnight, T. E.; Guillorn, M. A.; Merkulov, V. I.; Ilic, B.; Doktycz, M. J.; Lowndes, D. H.; Simpson, M. L.

2003-02-01

We report a method to fabricate nanoscale pipes ("nanopipes") suitable for fluidic transport. Vertically aligned carbon nanofibers grown by plasma-enhanced chemical vapor deposition are used as sacrificial templates for nanopipes with internal diameters as small as 30 nm and lengths up to several micrometers that are oriented perpendicular to the substrate. This method provides a high level of control over the nanopipe location, number, length, and diameter, permitting them to be deterministically positioned on a substrate and arranged into arrays.

Growth of Vertically Aligned ZnO Nanowire Arrays Using Bilayered Metal Catalysts

DTIC Science & Technology

2012-01-01

12] J. P. Liu, C. X. Guo, C. M. Li et al., “Carbon-decorated ZnO nanowire array: a novel platform for direct electrochemistry of enzymes and...cited. Vertically aligned, high-density ZnO nanowires (NWs) were grown for the first time on c-plane sapphire using binary alloys of Ni/Au or Cu/Au as...deleterious to the ZnO NW array growth. Significant improvement of the Au adhesion on the substrate was noted, opening the potential for direct

Hydraulic fracturing water use variability in the United States and potential environmental implications

PubMed Central

Varela, Brian A.; Haines, Seth S.; Engle, Mark A.

2015-01-01

Abstract Until now, up‐to‐date, comprehensive, spatial, national‐scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000−36,620 m3 per well) in watersheds across the United States generally correlated with shale‐gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection‐induced earthquakes. PMID:26937056

Experimental and numerical study of hydraulic fracture geometry in shale formations with complex geologic conditions

NASA Astrophysics Data System (ADS)

Ma, Xinfang; Zhou, Tong; Zou, Yushi

2017-05-01

Strike-slip fault geostress and dipping laminated structures in Lujiaping shale formation typically result in difficultly predicting hydraulic fracture (HF) geometries. In this study, a novel 3D fracture propagation model based on discrete element method (DEM) is established. A series of simulations is performed to illustrate the influence of vertical stress difference (△σv = σv-σh), fluid viscosity, and injection rate, on HF growth geometry in the dipping layered formation. Results reveal that the fracturing fluid can easily infiltrate the dipping bedding plane (BP) interfaces with low net pressure for △σv = 1 MPa. HF height growth is also restricted. With increased △σv, fracture propagation in the vertical direction is enhanced, and a fracture network is formed by VF and partially opened dipping BPs. However, it is likely to create simple VF for △σv = 20 MPa. Appropriately increasing fracturing fluid viscosity and injection rate is conductive to weakening the containment effect of BPs on HF growth by increasing the fluid net pressure. However, no indication is found on whether a higher fracturing fluid viscosity is better. Higher viscosity can reduce the activation of BPs, so a stimulated reservoir volume is not necessarily increased. All these results can serve as theoretical guidance for the optimization of fracturing treatments in Lujiaping shale formation.

Hydraulic fracturing water use variability in the United States and potential environmental implications

USGS Publications Warehouse

Gallegos, Tanya J.; Varela, Brian A.; Haines, Seth S.; Engle, Mark A.

2015-01-01

Until now, up-to-date, comprehensive, spatial, national-scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000−36,620 m3 per well) in watersheds across the United States generally correlated with shale-gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection-induced earthquakes.

Does trampoline or hard surface jumping influence lower extremity alignment?

PubMed

Akasaka, Kiyokazu; Tamura, Akihiro; Katsuta, Aoi; Sagawa, Ayako; Otsudo, Takahiro; Okubo, Yu; Sawada, Yutaka; Hall, Toby

2017-12-01

[Purpose] To determine whether repetitive trampoline or hard surface jumping affects lower extremity alignment on jump landing. [Subjects and Methods] Twenty healthy females participated in this study. All subjects performed a drop vertical jump before and after repeated maximum effort trampoline or hard surface jumping. A three-dimensional motion analysis system and two force plates were used to record lower extremity angles, moments, and vertical ground reaction force during drop vertical jumps. [Results] Knee extensor moment after trampoline jumping was greater than that after hard surface jumping. There were no significant differences between trials in vertical ground reaction force and lower extremity joint angles following each form of exercise. Repeated jumping on a trampoline increased peak vertical ground reaction force, hip extensor, knee extensor moments, and hip adduction angle, while decreasing hip flexion angle during drop vertical jumps. In contrast, repeated jumping on a hard surface increased peak vertical ground reaction force, ankle dorsiflexion angle, and hip extensor moment during drop vertical jumps. [Conclusion] Repeated jumping on the trampoline compared to jumping on a hard surface has different effects on lower limb kinetics and kinematics. Knowledge of these effects may be useful in designing exercise programs for different clinical presentations.

Does trampoline or hard surface jumping influence lower extremity alignment?

PubMed Central

Akasaka, Kiyokazu; Tamura, Akihiro; Katsuta, Aoi; Sagawa, Ayako; Otsudo, Takahiro; Okubo, Yu; Sawada, Yutaka; Hall, Toby

2017-01-01

[Purpose] To determine whether repetitive trampoline or hard surface jumping affects lower extremity alignment on jump landing. [Subjects and Methods] Twenty healthy females participated in this study. All subjects performed a drop vertical jump before and after repeated maximum effort trampoline or hard surface jumping. A three-dimensional motion analysis system and two force plates were used to record lower extremity angles, moments, and vertical ground reaction force during drop vertical jumps. [Results] Knee extensor moment after trampoline jumping was greater than that after hard surface jumping. There were no significant differences between trials in vertical ground reaction force and lower extremity joint angles following each form of exercise. Repeated jumping on a trampoline increased peak vertical ground reaction force, hip extensor, knee extensor moments, and hip adduction angle, while decreasing hip flexion angle during drop vertical jumps. In contrast, repeated jumping on a hard surface increased peak vertical ground reaction force, ankle dorsiflexion angle, and hip extensor moment during drop vertical jumps. [Conclusion] Repeated jumping on the trampoline compared to jumping on a hard surface has different effects on lower limb kinetics and kinematics. Knowledge of these effects may be useful in designing exercise programs for different clinical presentations. PMID:29643592

Hydraulic properties of three types of glacial deposits in Ohio

USGS Publications Warehouse

Strobel, M.L.

1993-01-01

The effects of thickness, grain size, fractures, weathering, and atmosphericconditions on vertical ground-water flow in glacial deposits were studied at three sites that represent ground moraine, end moraine, and lacustrine depositional environments. Vertical hydraulic conductivities computed from pumped-well tests were 3.24 x 10-1 to 6.47 x 10-1 ft/d (feet per day) at the site representing end moraine and 1.17 ft/d at the site representing lacustrine deposits. Analysis of test data for the ground moraine site did not yield estimates of hydraulic conductivities, but did indicate that ground water flows through the total thickness of deposits in response to discharge from a lower gravel unit. Vertical hydraulic conductivities computed from pumped-well tests of nested wells and data from drill-core analyses indicate that fractures affect the migration of ground water downward through the glacial deposits at these sites. Flow through glacial deposits is complex; it is controlled by fractures, gram-size distribution, clay content, thickness, and degree of weathering, and atmospheric conditions.

Micro-miniature gas chromatograph column disposed in silicon wafers

DOEpatents

Yu, Conrad M.

2000-01-01

A micro-miniature gas chromatograph column is fabricated by forming matching halves of a circular cross-section spiral microcapillary in two silicon wafers and then bonding the two wafers together using visual or physical alignment methods. Heating wires are deposited on the outside surfaces of each wafer in a spiral or serpentine pattern large enough in area to cover the whole microcapillary area inside the joined wafers. The visual alignment method includes etching through an alignment window in one wafer and a precision-matching alignment target in the other wafer. The two wafers are then bonded together using the window and target. The physical alignment methods include etching through vertical alignment holes in both wafers and then using pins or posts through corresponding vertical alignment holes to force precision alignment during bonding. The pins or posts may be withdrawn after curing of the bond. Once the wafers are bonded together, a solid phase of very pure silicone is injected in a solution of very pure chloroform into one end of the microcapillary. The chloroform lowers the viscosity of the silicone enough that a high pressure hypodermic needle with a thumbscrew plunger can force the solution into the whole length of the spiral microcapillary. The chloroform is then evaporated out slowly to leave the silicone behind in a deposit.

A methodology for using borehole temperature-depth profiles under ambient, single and cross-borehole pumping conditions to estimate fracture hydraulic properties

NASA Astrophysics Data System (ADS)

Klepikova, M.; Le Borgne, T.; Bour, O.; Lavenant, N.

2011-12-01

In fractured aquifers flow generally takes place in a few fractured zones. The identification of these main flow paths is critical as it controls the transfer of fluids in the subsurface. For realistic modeling of the flow the knowledge about the spatial variability of hydraulic properties is required. Inverse problems based on hydraulic head data are generally strongly underconstrained. A possible way of reducing the uncertainty is to combine different type of data, such as flow measurements, temperature profiles or tracer test data. Here, we focus on the use of temperature, which can be seen as a natural tracer of ground water flow. Previous studies used temperature anomalies to quantify vertical or horizontal regional groundwater flow velocities. Most of these studies assume that water in the borehole is stagnant, and, thus, the temperature profile in the well is representative of the temperature in the aquifer. In fractured media, differences in hydraulic head between flow paths connected to a borehole generally create ambient vertical flow within the borehole. These differences in hydraulic head are in general due to regional flow conditions. Estimation of borehole vertical flow is of interest as it can be used to derive large scale hydraulic connections. Under a single-borehole configuration, the estimation of vertical flow can be used to estimate the local transimissivities and the hydraulic head differences driving the flow through the borehole. Under a cross-borehole set up, it can be used to characterize hydraulic connections and estimate their hydraulic properties. Using a flow and heat transfer numerical model, we find that the slope of the temperature profile is related directly to vertical borehole flow velocity. Thus, we propose a method to invert temperature measurements to derive borehole flow velocities and subsequently the fracture zone hydraulic and connectivity properties. The advantage of temperature measurements compared to flowmeter measurements is that temperature can be measured easily and very accurately, continuously in space and time. To test the methodology, we have performed a field experiment at a crystalline rocks field site, located in Ploemeur, Brittany (France). The site is composed of three 100 meters deep boreholes, located at 6-10 m distances from each other. The experiment consisted in measuring the borehole temperature profiles under all possible pumping configurations. Hence, the pumping and monitoring wells were successively changed. The thermal response in observation well induced by changes in pumping conditions is related to changes in vertical flow velocities and thus to the inter-borehole fracture connectivity. Based on this dataset, we propose a methodology to include temperature profiles in inverse problem for characterizing the spatial distribution of fracture zone hydraulic properties.

Carbon nanotubes for thermal interface materials in microelectronic packaging

NASA Astrophysics Data System (ADS)

Lin, Wei

As the integration scale of transistors/devices in a chip/system keeps increasing, effective cooling has become more and more important in microelectronics. To address the thermal dissipation issue, one important solution is to develop thermal interface materials with higher performance. Carbon nanotubes, given their high intrinsic thermal and mechanical properties, and their high thermal and chemical stabilities, have received extensive attention from both academia and industry as a candidate for high-performance thermal interface materials. The thesis is devoted to addressing some challenges related to the potential application of carbon nanotubes as thermal interface materials in microelectronics. These challenges include: 1) controlled synthesis of vertically aligned carbon nanotubes on various bulk substrates via chemical vapor deposition and the fundamental understanding involved; 2) development of a scalable annealing process to improve the intrinsic properties of synthesized carbon nanotubes; 3) development of a state-of-art assembling process to effectively implement high-quality vertically aligned carbon nanotubes into a flip-chip assembly; 4) a reliable thermal measurement of intrinsic thermal transport property of vertically aligned carbon nanotube films; 5) improvement of interfacial thermal transport between carbon nanotubes and other materials. The major achievements are summarized. 1. Based on the fundamental understanding of catalytic chemical vapor deposition processes and the growth mechanism of carbon nanotube, fast synthesis of high-quality vertically aligned carbon nanotubes on various bulk substrates (e.g., copper, quartz, silicon, aluminum oxide, etc.) has been successfully achieved. The synthesis of vertically aligned carbon nanotubes on the bulk copper substrate by the thermal chemical vapor deposition process has set a world record. In order to functionalize the synthesized carbon nanotubes while maintaining their good vertical alignment, an in situ functionalization process has for the first time been demonstrated. The in situ functionalization renders the vertically aligned carbon nanotubes a proper chemical reactivity for forming chemical bonding with other substrate materials such as gold and silicon. 2. An ultrafast microwave annealing process has been developed to reduce the defect density in vertically aligned carbon nanotubes. Raman and thermogravimetric analyses have shown a distinct defect reduction in the CNTs annealed in microwave for 3 min. Fibers spun from the as-annealed CNTs, in comparison with those from the pristine CNTs, show increases of ˜35% and ˜65%, respectively, in tensile strength (˜0.8 GPa) and modulus (˜90 GPa) during tensile testing; an ˜20% improvement in electrical conductivity (˜80000 S m-1) was also reported. The mechanism of the microwave response of CNTs was discussed. Such a microwave annealing process has been extended to the preparation of reduced graphene oxide. 3. Based on the fundamental understanding of interfacial thermal transport and surface chemistry of metals and carbon nanotubes, two major transfer/assembling processes have been developed: molecular bonding and metal bonding. Effective improvement of the interfacial thermal transport has been achieved by the interfacial bonding. 4. The thermal diffusivity of vertically aligned carbon nanotube (VACNT, multi-walled) films was measured by a laser flash technique, and shown to be ˜30 mm2 s-1 along the tube-alignment direction. The calculated thermal conductivities of the VACNT film and the individual CNTs are ˜27 and ˜540 W m-1 K-1, respectively. The technique was verified to be reliable although a proper sampling procedure is critical. A systematic parametric study of the effects of defects, buckling, tip-to-tip contacts, packing density, and tube-tube interaction on the thermal diffusivity was carried out. Defects and buckling decreased the thermal diffusivity dramatically. An increased packing density was beneficial in increasing the collective thermal conductivity of the VACNT film; however, the increased tube-tube interaction in dense VACNT films decreased the thermal conductivity of the individual CNTs. The tip-to-tip contact resistance was shown to be ˜1x10-7 m2 K W -1. The study will shed light on the potential application of VACNTs as thermal interface materials in microelectronic packaging. 5. A combined process of in situ functionalization and microwave curing has been developed to effective enhance the interface between carbon nanotubes and the epoxy matrix. Effective medium theory has been used to analyze the interfacial thermal resistance between carbon nanotubes and polymer matrix, and that between graphite nanoplatlets and polymer matrix.

Electrical and Magnetic Imaging of Proppants in Shallow Hydraulic Fractures

NASA Astrophysics Data System (ADS)

Denison, J. L. S.; Murdoch, L. C.; LaBrecque, D. J.; Slack, W. W.

2015-12-01

Hydraulic fracturing is an important tool to increase the productivity of wells used for oil and gas production, water resources, and environmental remediation. Currently there are relatively few tools available to monitor the distribution of proppants within a hydraulic fracture, or the propagation of the fracture itself. We have been developing techniques for monitoring hydraulic fractures by injecting electrically conductive, dielectric, or magnetically permeable proppants. We then use the resulting contrast with the enveloping rock to image the proppants using geophysical methods. Based on coupled laboratory and numerical modeling studies, three types of proppants were selected for field evaluation. Eight hydraulic fractures were created near Clemson, SC in May of 2015 by injecting specialized proppants at a depth of 1.5 m. The injections created shallow sub-horizontal fractures extending several meters from the injection point.Each cell had a dense array of electrodes and magnetic sensors on the surface and four shallow vertical electrode arrays that were used to obtain data before and after hydraulic fracturing. Net vertical displacement and transient tilts were also measured. Cores from 130 boreholes were used to characterize the general geometries, and trenching was used to characterize the forms of two of the fractures in detail. Hydraulic fracture geometries were estimated by inverting pre- and post-injection geophysical data. Data from cores and trenching show that the hydraulic fractures were saucer-shaped with a preferred propagation direction. The geophysical inversions generated images that were remarkably similar in form, size, and location to the ground truth from direct observation. Displacement and tilt data appear promising as a constraint on fracture geometry.

Numerical modeling of fracking fluid migration through fault zones and fractures in the North German Basin

NASA Astrophysics Data System (ADS)

Pfunt, Helena; Houben, Georg; Himmelsbach, Thomas

2016-09-01

Gas production from shale formations by hydraulic fracturing has raised concerns about the effects on the quality of fresh groundwater. The migration of injected fracking fluids towards the surface was investigated in the North German Basin, based on the known standard lithology. This included cases with natural preferential pathways such as permeable fault zones and fracture networks. Conservative assumptions were applied in the simulation of flow and mass transport triggered by a high pressure boundary of up to 50 MPa excess pressure. The results show no significant fluid migration for a case with undisturbed cap rocks and a maximum of 41 m vertical transport within a permeable fault zone during the pressurization. Open fractures, if present, strongly control the flow field and migration; here vertical transport of fracking fluids reaches up to 200 m during hydraulic fracturing simulation. Long-term transport of the injected water was simulated for 300 years. The fracking fluid rises vertically within the fault zone up to 485 m due to buoyancy. Progressively, it is transported horizontally into sandstone layers, following the natural groundwater flow direction. In the long-term, the injected fluids are diluted to minor concentrations. Despite the presence of permeable pathways, the injected fracking fluids in the reported model did not reach near-surface aquifers, either during the hydraulic fracturing or in the long term. Therefore, the probability of impacts on shallow groundwater by the rise of fracking fluids from a deep shale-gas formation through the geological underground to the surface is small.

In vitro study of root fracture treated by CO2 laser and DP-bioactive glass paste.

PubMed

Wang, Yin-Lin; Lee, Bor-Shiunn; Tseng, Ching-Li; Lin, Feng-Huei; Lin, Chun-Pin

2008-01-01

An ideal material has yet to be discovered that can successfully treat vertical root fracture. Therefore, the purpose of this study was to use a continuous-wave CO2 laser of medium-energy density to fuse DP-bioactive glass paste (DPGP) to vertical root fracture. The DP-bioglass powder was based on a Na2O-CaO-SiO2-P2O5 system and it was mixed with phosphoric acid (65% concentration) with a powder/liquid ratio of 2 g/4 mL to form DPGP. The interaction of DPGP and dentin was analyzed by means of X-ray diffractometer (XRD) and differential thermal analysis/thermogravimetric analysis (DTA/TGA). Root fracture line was filled with DPGP followed by CO2 laser irradiation and the result was examined by scanning electron microscopy (SEM). The main crystal phase of DPGP was monocalcium phosphate monohydrate (Ca(H2PO4)2.H2O) and the phase transformed to dicalcium phosphate dihydrate (CaHPO4.2H2O) after mixing DPGP with dentin powder (DPG-D). Additionally, gamma-Ca2P2O7 and beta-Ca2P2O7 were identified when DPG-D was lased by CO2 laser. The reaction temperature was between 500 degrees C and 1100 degrees C. SEM results demonstrated that the fracture line was effectively sealed by DPGP. The chemical reaction of DPGP and dentin indicated that DPGP combined with CO2 laser is a potential regimen for the treatment of vertical root fracture.

Controls on fracture distribution in the Giddings Austin Chalk

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

Wagner, D.T.

1990-09-01

Fracture distribution in the Giddings Austin Chalk is controlled by both structure and the stratigraphy of the Austin Group. Parameters that most affect reservoir performance include fracture width, height, and spacing, as well as the number of fracture sets and their orientations. Lateral variance of these parameters is a function of structural position, while vertical change is related to stratigraphy. The Austin Chalk productive trend is thought to coincide with the hingeline of the Gulf Coast basin, where extension has been concentrated during subsidence of the basin. Fracturing is attributed to a number of mechanisms including normal faulting, bending overmore » buried structures, gravity creep, differential compaction, and aquathermal pressuring. A change in structural style from faulting to flexure takes place from west to east across the Giddings field, accompanied by a change in fracture distribution. In the west, fractures develop only in close proximity to faults whereas in the east they are more widely distributed over broad warps. Stratigraphic controls include lithology, porosity, bed thickness, and ductility contrast between adjacent beds. The Austin Chalk consists of sparse biomicrite interbedded with marls, shales, and clay seams. In general, thin beds are more highly fractured than thick beds, and clean limestone is more highly fractured than marl or shale. Where the more ductile marls and clays exceed a critical thickness, fractures tend to terminate within individual chalk beds, resulting in barriers to vertical flow within the reservoir.« less

Vertically Aligned and Continuous Nanoscale Ceramic-Polymer Interfaces in Composite Solid Polymer Electrolytes for Enhanced Ionic Conductivity.

PubMed

Zhang, Xiaokun; Xie, Jin; Shi, Feifei; Lin, Dingchang; Liu, Yayuan; Liu, Wei; Pei, Allen; Gong, Yongji; Wang, Hongxia; Liu, Kai; Xiang, Yong; Cui, Yi

2018-06-13

Among all solid electrolytes, composite solid polymer electrolytes, comprised of polymer matrix and ceramic fillers, garner great interest due to the enhancement of ionic conductivity and mechanical properties derived from ceramic-polymer interactions. Here, we report a composite electrolyte with densely packed, vertically aligned, and continuous nanoscale ceramic-polymer interfaces, using surface-modified anodized aluminum oxide as the ceramic scaffold and poly(ethylene oxide) as the polymer matrix. The fast Li + transport along the ceramic-polymer interfaces was proven experimentally for the first time, and an interfacial ionic conductivity higher than 10 -3 S/cm at 0 °C was predicted. The presented composite solid electrolyte achieved an ionic conductivity as high as 5.82 × 10 -4 S/cm at the electrode level. The vertically aligned interfacial structure in the composite electrolytes enables the viable application of the composite solid electrolyte with superior ionic conductivity and high hardness, allowing Li-Li cells to be cycled at a small polarization without Li dendrite penetration.

Robust forests of vertically aligned carbon nanotubes chemically assembled on carbon substrates.

PubMed

Garrett, David J; Flavel, Benjamin S; Shapter, Joseph G; Baronian, Keith H R; Downard, Alison J

2010-02-02

Forests of vertically aligned carbon nanotubes (VACNTs) have been chemically assembled on carbon surfaces. The structures show excellent stability over a wide potential range and are resistant to degradation from sonication in acid, base, and organic solvent. Acid-treated single-walled carbon nanotubes (SWCNTs) were assembled on amine-terminated tether layers covalently attached to pyrolyzed photoresist films. Tether layers were electrografted to the carbon substrate by reduction of the p-aminobenzenediazonium cation and oxidation of ethylenediamine. The amine-modified surfaces were incubated with cut SWCNTs in the presence of N,N'-dicyclohexylcarbodiimide (DCC), giving forests of vertically aligned carbon nanotubes (VACNTs). The SWCNT assemblies were characterized by scanning electron microscopy, atomic force microscopy, and electrochemistry. Under conditions where the tether layers slow electron transfer between solution-based redox probes and the underlying electrode, the assembly of VACNTs on the tether layer dramatically increases the electron-transfer rate at the surface. The grafting procedure, and hence the preparation of VACNTs, is applicable to a wide range of materials including metals and semiconductors.

Fabrication of Vertically Aligned Carbon Nanotube or Zinc Oxide Nanorod Arrays for Optical Diffraction Gratings.

PubMed

Kim, Jeong; Kim, Sun Il; Cho, Seong-Ho; Hwang, Sungwoo; Lee, Young Hee; Hur, Jaehyun

2015-11-01

We report on new fabrication methods for a transparent, hierarchical, and patterned electrode comprised of either carbon nanotubes or zinc oxide nanorods. Vertically aligned carbon nanotubes or zinc oxide nanorod arrays were fabricated by either chemical vapor deposition or hydrothermal growth, in combination with photolithography. A transparent conductive graphene layer or zinc oxide seed layer was employed as the transparent electrode. On the patterned surface defined using photoresist, the vertically grown carbon nanotubes or zinc oxides could produce a concentrated electric field under applied DC voltage. This periodic electric field was used to align liquid crystal molecules in localized areas within the optical cell, effectively modulating the refractive index. Depending on the material and morphology of these patterned electrodes, the diffraction efficiency presented different behavior. From this study, we established the relationship between the hierarchical structure of the different electrodes and their efficiency for modulating the refractive index. We believe that this study will pave a new path for future optoelectronic applications.

Vertically aligned N-doped CNTs growth using Taguchi experimental design

NASA Astrophysics Data System (ADS)

Silva, Ricardo M.; Fernandes, António J. S.; Ferro, Marta C.; Pinna, Nicola; Silva, Rui F.

2015-07-01

The Taguchi method with a parameter design L9 orthogonal array was implemented for optimizing the nitrogen incorporation in the structure of vertically aligned N-doped CNTs grown by thermal chemical deposition (TCVD). The maximization of the ID/IG ratio of the Raman spectra was selected as the target value. As a result, the optimal deposition configuration was NH3 = 90 sccm, growth temperature = 825 °C and catalyst pretreatment time of 2 min, the first parameter having the main effect on nitrogen incorporation. A confirmation experiment with these values was performed, ratifying the predicted ID/IG ratio of 1.42. Scanning electron microscopy (SEM) characterization revealed a uniform completely vertically aligned array of multiwalled CNTs which individually exhibit a bamboo-like structure, consisting of periodically curved graphitic layers, as depicted by high resolution transmission electron microscopy (HRTEM). The X-ray photoelectron spectroscopy (XPS) results indicated a 2.00 at.% of N incorporation in the CNTs in pyridine-like and graphite-like, as the predominant species.

Functionalization of vertically aligned carbon nanotubes.

PubMed

Van Hooijdonk, Eloise; Bittencourt, Carla; Snyders, Rony; Colomer, Jean-François

2013-01-01

This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs). The intrinsic properties of individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by functionalization (grafting of functional chemical groups, decoration with metal particles or wrapping of polymers) to bring new properties or to improve the interactions between the VA-CNTs and their environment while maintaining the alignment of CNTs.

Functionalization of vertically aligned carbon nanotubes

PubMed Central

Snyders, Rony; Colomer, Jean-François

2013-01-01

Summary This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs). The intrinsic properties of individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by functionalization (grafting of functional chemical groups, decoration with metal particles or wrapping of polymers) to bring new properties or to improve the interactions between the VA-CNTs and their environment while maintaining the alignment of CNTs. PMID:23504581

Intra-operative 3D imaging system for robot-assisted fracture manipulation.

PubMed

Dagnino, G; Georgilas, I; Tarassoli, P; Atkins, R; Dogramadzi, S

2015-01-01

Reduction is a crucial step in the treatment of broken bones. Achieving precise anatomical alignment of bone fragments is essential for a good fast healing process. Percutaneous techniques are associated with faster recovery time and lower infection risk. However, deducing intra-operatively the desired reduction position is quite challenging due to the currently available technology. The 2D nature of this technology (i.e. the image intensifier) doesn't provide enough information to the surgeon regarding the fracture alignment and rotation, which is actually a three-dimensional problem. This paper describes the design and development of a 3D imaging system for the intra-operative virtual reduction of joint fractures. The proposed imaging system is able to receive and segment CT scan data of the fracture, to generate the 3D models of the bone fragments, and display them on a GUI. A commercial optical tracker was included into the system to track the actual pose of the bone fragments in the physical space, and generate the corresponding pose relations in the virtual environment of the imaging system. The surgeon virtually reduces the fracture in the 3D virtual environment, and a robotic manipulator connected to the fracture through an orthopedic pin executes the physical reductions accordingly. The system is here evaluated through fracture reduction experiments, demonstrating a reduction accuracy of 1.04 ± 0.69 mm (translational RMSE) and 0.89 ± 0.71 ° (rotational RMSE).

Risk factors for stress fractures.

PubMed

Bennell, K; Matheson, G; Meeuwisse, W; Brukner, P

1999-08-01

Preventing stress fractures requires knowledge of the risk factors that predispose to this injury. The aetiology of stress fractures is multifactorial, but methodological limitations and expediency often lead to research study designs that evaluate individual risk factors. Intrinsic risk factors include mechanical factors such as bone density, skeletal alignment and body size and composition, physiological factors such as bone turnover rate, flexibility, and muscular strength and endurance, as well as hormonal and nutritional factors. Extrinsic risk factors include mechanical factors such as surface, footwear and external loading as well as physical training parameters. Psychological traits may also play a role in increasing stress fracture risk. Equally important to these types of analyses of individual risk factors is the integration of information to produce a composite picture of risk. The purpose of this paper is to critically appraise the existing literature by evaluating study design and quality, in order to provide a current synopsis of the known scientific information related to stress fracture risk factors. The literature is not fully complete with well conducted studies on this topic, but a great deal of information has accumulated over the past 20 years. Although stress fractures result from repeated loading, the exact contribution of training factors (volume, intensity, surface) has not been clearly established. From what we do know, menstrual disturbances, caloric restriction, lower bone density, muscle weakness and leg length differences are risk factors for stress fracture. Other time-honoured risk factors such as lower extremity alignment have not been shown to be causative even though anecdotal evidence indicates they are likely to play an important role in stress fracture pathogenesis.

Effects of Nanowire Length and Surface Roughness on the Electrochemical Sensor Properties of Nafion-Free, Vertically Aligned Pt Nanowire Array Electrodes

PubMed Central

Li, Zhiyang; Leung, Calvin; Gao, Fan; Gu, Zhiyong

2015-01-01

In this paper, vertically aligned Pt nanowire arrays (PtNWA) with different lengths and surface roughnesses were fabricated and their electrochemical performance toward hydrogen peroxide (H2O2) detection was studied. The nanowire arrays were synthesized by electroplating Pt in nanopores of anodic aluminum oxide (AAO) template. Different parameters, such as current density and deposition time, were precisely controlled to synthesize nanowires with different surface roughnesses and various lengths from 3 μm to 12 μm. The PtNWA electrodes showed better performance than the conventional electrodes modified by Pt nanowires randomly dispersed on the electrode surface. The results indicate that both the length and surface roughness can affect the sensing performance of vertically aligned Pt nanowire array electrodes. Generally, longer nanowires with rougher surfaces showed better electrochemical sensing performance. The 12 μm rough surface PtNWA presented the largest sensitivity (654 μA·mM−1·cm−2) among all the nanowires studied, and showed a limit of detection of 2.4 μM. The 12 μm rough surface PtNWA electrode also showed good anti-interference property from chemicals that are typically present in the biological samples such as ascorbic, uric acid, citric acid, and glucose. The sensing performance in real samples (river water) was tested and good recovery was observed. These Nafion-free, vertically aligned Pt nanowires with surface roughness control show great promise as versatile electrochemical sensors and biosensors. PMID:26404303

Can a semi-automated surface matching and principal axis-based algorithm accurately quantify femoral shaft fracture alignment in six degrees of freedom?

PubMed

Crookshank, Meghan C; Beek, Maarten; Singh, Devin; Schemitsch, Emil H; Whyne, Cari M

2013-07-01

Accurate alignment of femoral shaft fractures treated with intramedullary nailing remains a challenge for orthopaedic surgeons. The aim of this study is to develop and validate a cone-beam CT-based, semi-automated algorithm to quantify the malalignment in six degrees of freedom (6DOF) using a surface matching and principal axes-based approach. Complex comminuted diaphyseal fractures were created in nine cadaveric femora and cone-beam CT images were acquired (27 cases total). Scans were cropped and segmented using intensity-based thresholding, producing superior, inferior and comminution volumes. Cylinders were fit to estimate the long axes of the superior and inferior fragments. The angle and distance between the two cylindrical axes were calculated to determine flexion/extension and varus/valgus angulation and medial/lateral and anterior/posterior translations, respectively. Both surfaces were unwrapped about the cylindrical axes. Three methods of matching the unwrapped surface for determination of periaxial rotation were compared based on minimizing the distance between features. The calculated corrections were compared to the input malalignment conditions. All 6DOF were calculated to within current clinical tolerances for all but two cases. This algorithm yielded accurate quantification of malalignment of femoral shaft fractures for fracture gaps up to 60 mm, based on a single CBCT image of the fractured limb. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

Forefoot Adduction Is a Risk Factor for Jones Fracture.

PubMed

Fleischer, Adam E; Stack, Rebecca; Klein, Erin E; Baker, Jeffrey R; Weil, Lowell; Weil, Lowell Scott

Jones fractures are among the most common fractures of the foot; however, much remains unknown about their etiology. The purpose of the present study was to further examine the risk factors of forefoot and hindfoot alignment on Jones fractures using an epidemiologic study design. We used a retrospective, matched, case-control study design. Cases consisted of patients with acute, isolated Jones fractures confirmed on plain film radiographs seen at our institute from January 2009 to December 2013. Patients presenting with pain unrelated to metatarsal fractures served as controls. Controls were matched to cases by age (±2 years), gender, and year of presentation. Weightbearing foot radiographs were assessed for 13 angular relationships by a single rater. Conditional multivariable logistic regression was used to identify important risk factors. Fifty patients with acute Jones fractures and 200 controls were included. The only significant variables in the final multivariable model were the metatarsus adductus angle (odds ratio [OR] 1.16, 95% confidence interval [CI] 1.08 to 1.25) and fourth/fifth intermetatarsal angle (OR 0.69, 95% CI 0.57 to 0.83)-both measures of static forefoot adduction. The presence of metatarsus adductus (defined as >15°) on foot radiographs was associated with a 2.4 times greater risk of a Jones fracture (adjusted OR 2.4, 95% CI 1.2 to 4.8). We have concluded that the risk of Jones fracture increases with an adducted forefoot posture. In our population, which consisted primarily of patients presenting after a fall (10 of 50; 20%) or misstep/inversion injury (19 of 50; 38%), the hindfoot alignment appeared to be a less important factor. Copyright © 2017 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Structural and Geophysical Characterization of Oklahoma Basement

NASA Astrophysics Data System (ADS)

Morgan, C.; Johnston, C. S.; Carpenter, B. M.; Reches, Z.

2017-12-01

Oklahoma has experienced a large increase in seismicity since 2009 that has been attributed to wastewater injection. Most earthquakes, including four M5+ earthquakes, nucleated at depths > 4 km, well within the pre-Cambrian crystalline basement, even though wastewater injection occurred almost exclusively in the sedimentary sequence above. To better understand the structural characteristics of the rhyolite and granite that makeup the midcontinent basement, we analyzed a 150 m long core recovered from a basement borehole (Shads 4) in Rogers County, NE Oklahoma. The analysis of the fracture network in the rhyolite core included measurements of fracture inclination, aperture, and density, the examination fracture surface features and fill minerology, as well as x-ray diffraction analysis of secondary mineralization. We also analyzed the highly fractured and faulted segments of the core with a portable gamma-ray detector, magnetometer, and rebound hammer. The preliminary analysis of the fractures within the rhyolite core showed: (1) Fracture density increasing with depth by a factor of 10, from 4 fractures/10m in the upper core segment to 40 fracture/10m at 150 m deeper. (2) The fractures are primarily sub-vertical, inclined 10-20° from the axis of the vertical core. (3) The secondary mineralization is dominated by calcite and epidote. (4) Fracture aperture ranges from 0.35 to 2.35mm based on the thickness of secondary filling. (5) About 8% of the examined fractures display slickenside striations. (6) Increases of elasticity (by rebound hammer) and gamma-ray emissions are systematically correlated with a decrease in magnetic susceptibility in core segments of high fracture density and/or faulting; this observation suggests diagenetic fracture re-mineralization.

Enhanced antibacterial activity through the controlled alignment of graphene oxide nanosheets.

PubMed

Lu, Xinglin; Feng, Xunda; Werber, Jay R; Chu, Chiheng; Zucker, Ines; Kim, Jae-Hong; Osuji, Chinedum O; Elimelech, Menachem

2017-11-14

The cytotoxicity of 2D graphene-based nanomaterials (GBNs) is highly important for engineered applications and environmental health. However, the isotropic orientation of GBNs, most notably graphene oxide (GO), in previous experimental studies obscured the interpretation of cytotoxic contributions of nanosheet edges. Here, we investigate the orientation-dependent interaction of GBNs with bacteria using GO composite films. To produce the films, GO nanosheets are aligned in a magnetic field, immobilized by cross-linking of the surrounding matrix, and exposed on the surface through oxidative etching. Characterization by small-angle X-ray scattering and atomic force microscopy confirms that GO nanosheets align progressively well with increasing magnetic field strength and that the alignment is effectively preserved by cross-linking. When contacted with the model bacterium Escherichia coli , GO nanosheets with vertical orientation exhibit enhanced antibacterial activity compared with random and horizontal orientations. Further characterization is performed to explain the enhanced antibacterial activity of the film with vertically aligned GO. Using phospholipid vesicles as a model system, we observe that GO nanosheets induce physical disruption of the lipid bilayer. Additionally, we find substantial GO-induced oxidation of glutathione, a model intracellular antioxidant, paired with limited generation of reactive oxygen species, suggesting that oxidation occurs through a direct electron-transfer mechanism. These physical and chemical mechanisms both require nanosheet penetration of the cell membrane, suggesting that the enhanced antibacterial activity of the film with vertically aligned GO stems from an increased density of edges with a preferential orientation for membrane disruption. The importance of nanosheet penetration for cytotoxicity has direct implications for the design of engineering surfaces using GBNs.

A rapid quantification of binocular misalignment without recording eye movements: Vertical and torsional alignment nulling.

PubMed

Beaton, Kara H; Shelhamer, Mark J; Roberts, Dale C; Schubert, Michael C

2017-05-01

Small, innate asymmetries between the left and right otolith organs can cause ocular misalignment with symptoms that include double vision and motion sickness. Additionally, ocular misalignment affects nearly 5% of the US population. We have developed a portable, non-invasive technology that uses subjective perception of binocular visual signals to estimate relative binocular alignment. The Vertical Alignment Nulling (VAN) and Torsional Alignment Nulling (TAN) tests ask subjects to view one red and one blue line on a tablet computer while looking through color-matched red and blue filters so that each eye sees only one of the lines. Subjects align the red and blue lines, which are initially vertically offset from one another during VAN or rotated relative to one another during TAN, until they perceive a single continuous line. Ocular misalignments are inferred from actual offsets in the final line positions. During testing, all binocular visual cues are eliminated by employing active-matrix organic light-emitting diode (AMOLED) technology and testing in darkness. VAN and TAN can accurately account for visual offsets induced by prisms, and test-retest reliability is excellent, with resolution better than many current standard clinical tests. VAN and TAN tests are similar to the clinical Lancaster red-green test. However, VAN and TAN employ inexpensive, hand-held hardware that can be self-administered with results that are quickly quantifiable. VAN and TAN provide simple, sensitive, and quantitative measures of binocular positioning alignment that may be useful for detecting subtle abnormalities in ocular positioning. Copyright © 2017 Elsevier B.V. All rights reserved.

49 CFR 572.43 - Lumbar spine and pelvis.

Code of Federal Regulations, 2010 CFR

2010-10-01

... vertical plane which is tangent to the back of the dummy's buttocks. (3) Align the test probe so that at... vertical planes perpendicular to the midsagittal plane passing through the designated impact point. (4) Adjust the dummy so that its midsagittal plane is vertical and the rear surfaces of the thorax and...

Hierarchical composites of sulfonated graphene-supported vertically aligned polyaniline nanorods for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Ma, Biao; Zhou, Xiao; Bao, Hua; Li, Xingwei; Wang, Gengchao

2012-10-01

Hierarchical composites of sulfonated graphene-supported vertically aligned polyaniline nanorods (sGNS/PANI) are successfully synthesized via interfacial polymerization of aniline monomers in the presence of sulfonated graphene nanosheets (sGNS). The FE-SEM images indicate that the morphologies of sGNS/PANI composites can be controlled by adjusting the concentration of aniline monomers. FTIR and Raman spectra reveal that aligned PANI nanorod arrays for sGNS/PANI exhibit higher degree of conjugation compared with pristine PANI nanorods. The hierarchical composite based on the two-electrode cell possesses higher specific capacitance (497 F g-1 at 0.2 A g-1), better rate capability and cycling stability (5.7% capacitance loss after 2000 cycles) than those of pristine PANI nanorods.

Comparative evaluation of the vertical fracture resistance of endodontically treated roots filled with Gutta-percha and Resilon: a meta-analysis of in vitro studies.

PubMed

Tan, Minmin; Chai, Zhaowu; Sun, Chengjun; Hu, Bo; Gao, Xiang; Chen, Yunjia; Song, Jinlin

2018-06-13

Teeth treated endodontically are more susceptible to vertical root fracture (VRF). Some studies have suggested that obturating the root canals with Gutta-percha or Resilon can reinforce endodontically treated teeth, but a few others have presented conflicting results. These inconsistent results cannot guide clinicians in determining clinical approaches. The objective of this meta-analysis is to evaluate and compare the vertical fracture resistance of endodontically treated root canals obturated with Gutta-percha/AH plus and the Resilon system. Comprehensive literature searches were performed in the PubMed, Cochrane Library, ScienceDirect, Web of Science and Embase databases. The titles and abstracts of all of the retrieved articles were independently assessed by two authors according to predefined selection criteria. Data in the included articles were independently extracted. Statistical analyses were conducted using Review Manager 5.3 and Stata 12.0 software. The pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated for the outcome indicators. The level of statistical significance was set at p < 0.05. The Cochran Q test (I 2 test) was used to test for heterogeneity among studies. Fourteen randomized controlled in vitro trials were included in the meta-analysis. The results demonstrated that the vertical root fracture resistance of unprepared and unfilled roots was significantly higher than that of roots obturated with Gutta-percha/AH plus (SMD = - 0.69, 95% CI = - 1.34 to - 0.04, p = 0.04) or the Resilon system (SMD = - 0.54, 95% CI = - 1.07 to - 0.00, p = 0.05). The differences in fracture resistance between the roots filled with Gutta-percha/AH plus and the prepared unfilled root canals was not significant (SMD = 0.59, 95% CI = - 0.02 to 1.21, p = 0.06). Roots obturated with Resilon had higher fracture resistance than instrumented unfilled roots (SMD = 0.83, 95% CI = 0.44 to 1.22, p < 0.0001) or roots filled with Gutta-percha/AH plus (SMD = 0.62, 95% CI = 0.01 to 1.23, p = 0.05). The present study suggests that filling with Gutta-percha/AH plus dose not reinforce endodontically treated roots, whereas obturating with the Resilon system can increase vertical root fracture resistance of prepared roots. As this meta-analysis was based on in vitro studies, it should be careful to extrapolate its conclusion to the clinical context.

Success of long bone fracture healing in ancient Egypt: a paleoepidemiological study of the Giza Necropolis skeletons.

PubMed

Erfan Zaki, Moushira

2013-01-01

Complications may provide information regarding the management of fractures in ancient populations. The aim of this study was to determine the rates of long-bone fractures and the proportion of misalignments as indicators of failed treatment or no treatment at all in skeletons from the Giza Necropolis dating to the Old Kingdom period (2700-2190 BC). We visually examined for fractures 2287 long bones of 204 adult skeletons (112 male and 92 female) and took x-rays of fractured bones in standard AP and ML views, so that we can analyse misalignments. Fractures were found in 45 of the 2287 examined long bones (1.97 %). Most of the fractures healed with good alignment, most likely as a result of successful treatment, and only three fractures showed misalignment.

A prospective study on 284 digital fractures of the hand.

PubMed

Pun, W K; Chow, S P; So, Y C; Luk, K D; Ip, F K; Chan, K C; Ngai, W K; Crosby, C; Ng, C

1989-05-01

We report a prospective study on 284 digital fractures of the hand in 235 patients. Management followed clear guidelines set out in a protocol. Important factors in the selection of the treatment method were, acceptable alignment, functional stability, and associated "significant" soft tissue injuries. "Functionally" stable fractures treated by free mobilization had satisfactory results. Unstable fractures treated by splints or Kirschner wire fixation produced unsatisfactory results. "Open fracture," "comminuted fracture," and "associated significant soft tissue injuries" were identified as unfavorable prognostic factors. The anatomic site of the fractures was not important in determining the final outcome. About 15% of the displaced fractures became functionally stable after closed reduction and their results were comparable with the undisplaced fractures. About 30% of the patients had various degrees of difficulty after they returned to work. About 14% of the patients eventually changed their jobs because of their residual disability.

Effect of hydro mechanical coupling on natural fracture network formation in sedimentary basins

NASA Astrophysics Data System (ADS)

Ouraga, Zady; Guy, Nicolas; Pouya, Amade

2018-05-01

In sedimentary basin context, numerous phenomena, depending on the geological time span, can result in natural fracture network formation. In this paper, fracture network and dynamic fracture spacing triggered by significant sedimentation rate are studied considering mode I fracture propagation using a coupled hydro-mechanical numerical methods. The focus is put on synthetic geological structure under a constant sedimentation rate on its top. This model contains vertical fracture network initially closed and homogeneously distributed. The fractures are modelled with cohesive zone model undergoing damage and the flow is described by Poiseuille's law. The effect of the behaviour of the rock is studied and the analysis leads to a pattern of fracture network and fracture spacing in the geological layer.

Assessment of Surrogate Fractured Rock Networks for Evidence of Complex Behavior

NASA Astrophysics Data System (ADS)

Wood, T. R.; McJunkin, T. R.; Podgorney, R. K.; Glass, R. J.; Starr, R. C.; Stoner, D. L.; Noah, K. S.; LaViolette, R. A.; Fairley, J.

2001-12-01

A complex system or complex process is -"one whose properties are not fully explained by an understanding of its component parts". Results from field experiments conducted at the Hell's Half-Acre field site (Arco, Idaho) suggest that the flow of water in an unsaturated, fractured medium exhibits characteristics of a complex process. A series of laboratory studies is underway with sufficient rigor to determine if complex behavior observed in the field is in fact a fundamental characteristic of water flow in unsaturated, fractured media. As an initial step, a series of four duplicate experiments has been performed using an array of bricks to simulate fractured, unsaturated media. The array consisted of 12 limestone blocks cut to uniform size (5cm x 7 cm x 30 cm) stacked on end 4 blocks wide and 3 blocks high with the interfaces between adjacent blocks representing 3 vertical fractures intersecting 2 horizontal fractures. Water was introduced at three point sources on the upper boundary of the model at the top of the vertical fractures. Water was applied under constant flux at a rate below the infiltration capacity of the system, thus maintaining unsaturated flow conditions. Water was collected from the lower boundary via fiberglass wicks at the bottom of each fracture. An automated system acquired and processed water inflow and outflow data and time-lapse photographic data during each of the 72-hour tests. From these experiments, we see that a few general statements can be made on the overall advance of the wetting front in the surrogate fracture networks. For instance, flow generally converged with depth to the center fracture in the bottom row of bricks. Another observation is that fracture intersections integrate the steady flow in overlying vertical fractures and allow or cause short duration high discharge pulses or "avalanches" of flow to quickly traverse the fracture network below. Smaller scale tests of single fracture and fracture intersections are underway to evaluate a wide array of unit processes that are believed to contribute to complex behavior. Examples of these smaller scale experiments include the role of fracture intersections in integrating a steady inflow to generate giant fluctuations in network discharge; the influence of microbe growth on flow; and the role of geochemistry in alterations of flow paths. Experiments are planned at the meso and field scale to document and understand the controls on self-organized behavior. Modeling is being conducted in parallel with the experiments to understand how simulations can be improved to capture the complexity of fluid flow in fractured rock vadose zones and to make better predictions of contaminant transport.

Understanding the etiology of the posteromedial tibial stress fracture.

PubMed

Milgrom, Charles; Burr, David B; Finestone, Aharon S; Voloshin, Arkady

2015-09-01

Previous human in vivo tibial strain measurements from surface strain gauges during vigorous activities were found to be below the threshold value of repetitive cyclical loading at 2500 microstrain in tension necessary to reduce the fatigue life of bone, based on ex vivo studies. Therefore it has been hypothesized that an intermediate bone remodeling response might play a role in the development of tibial stress fractures. In young adults tibial stress fractures are usually oblique, suggesting that they are the result of failure under shear strain. Strains were measured using surface mounted unstacked 45° rosette strain gauges on the posterior aspect of the flat medial cortex just below the tibial midshaft, in a 48year old male subject while performing vertical jumps, staircase jumps and running up and down stadium stairs. Shear strains approaching 5000 microstrain were recorded during stair jumping and vertical standing jumps. Shear strains above 1250 microstrain were recorded during runs up and down stadium steps. Based on predictions from ex vivo studies, stair and vertical jumping tibial shear strain in the test subject was high enough to potentially produce tibial stress fracture subsequent to repetitive cyclic loading without necessarily requiring an intermediate remodeling response to microdamage. Copyright © 2015 Elsevier Inc. All rights reserved.

Delamination toughness characterization of out-of-autoclave vacuum-bag-only polymer matrix composites enhanced by z-aligned carbon nanofibers

NASA Astrophysics Data System (ADS)

Brewer, John S.

Brewer, John S., M. S., University of South Alabama, May 2015. Delamination Toughness Characterization of Out-of-Autoclave Vacuum-Bag-Only Polymer Matrix Composites Enhanced by z-aligned Carbon Nanofibers. Chair of Committee: Kuang-Ting Hsiao, Ph.D. In the last few decades, the use of composite materials has revolutionized materials manufacturing. Now, carbon fiber materials are at the forefront of engineering and manufacturing technology. One of the chief failure modes of composite materials is delamination. For this reason, this study employed the Mode-I Interlaminar Fracture Toughness Test (ASTM D 5528-01) to characterize how the inclusion of z-aligned carbon nanofibers (CNF) in Carbon Fiber Reinforced Polymers (CFRP) affects delamination strength. CFRP with z-aligned CNF in concentrations of 0.3% and 0.6% by weight were compared to control CFRP samples and CFRP samples modified with 0.3 weight percent unaligned CNF. The largest improvement was seen in the 0.3 weight percent aligned composite with a mean interlaminar fracture toughness increase of over 35%, while the uncertainty was decreased. A standard deviation of 3.3% was observed which equates to an uncertainty value 30% better than the control samples. Data and microscopy are included and discussed.

Tool post modification allows easy turret lathe cutting-tool alignment

NASA Technical Reports Server (NTRS)

Fouts, L.

1966-01-01

Modified tool holder and tool post permit alignment of turret lathe cutting tools on the center of the spindle. The tool is aligned with the spindle by the holder which is kept in position by a hydraulic lock in feature of the tool post. The tool post is used on horizontal and vertical turret lathes and other engine lathes.

The effect of different posts on fracture strength of roots with vertical fracture and re-attached fragments.

PubMed

Ozcopur, B; Akman, S; Eskitascioglu, G; Belli, S

2010-08-01

The aim of this in vitro study was to test the effect of different post systems on fracture strength of roots with re-attached fragments. Root canals of eighty extracted single-rooted human teeth were instrumented (ProFile) and randomly divided into two groups. The roots in the first group were vertically cracked, and the fragments were re-attached using Super Bond C&B (Sun Medical, Tokya, Japan). The roots in the second group were kept sound. Obturation of the roots was performed with MetaSEAL (Sun Medical) and gutta-percha. Post spaces were prepared, and the roots were restored with one of the followings: UniCore (Ultradent), Everstick (Stick Tech), Ribbond (Ribbond), ParaPost (Coltene/Whaledent) (n = 10). Four mm high build-ups were created (Clearfil DC Bond Core; Kuraray, Tokyo, Japan). Compressive loading of the samples was performed after 24 h (1 mm min(-1)). Mean load necessary to fracture each sample was recorded (Newton) and statistically analysed (One-way anova, t-tests). ParaPost showed the highest fracture strength among the roots with re-attached fragments (P < 0.05). UniCore and ParaPost systems showed similar fracture strength in the sound roots (P > 0.05). Re-attached fragments significantly reduced the fracture strength of roots in UniCore group (P = 0.000). Ribbond post showed mostly repairable fractures. Metal post (ParaPost) showed the highest fracture strength in the roots with re-attached fragments; however, fracture pattern was 41% non-repairable. Re-attached fragments significantly reduced the fracture strength of the roots in UniCore group. Prefabricated posts showed similar fracture strength in the sound roots. Customized post systems EverStick and Ribbond showed mostly repairable failure after loading in sound roots or roots with re-attached fragments.

Induction logging device

DOEpatents

Koelle, A.R.; Landt, J.A.

An instrument is disclosed for mapping vertical conductive fractures in a resistive bedrock, magnetically inducing eddy currents by a pair of vertically oriented, mutually perpendicular, coplanar coils. The eddy currents drive magnetic fields which are picked up by a second, similar pair of coils.

A Generic analytical solution for modelling pumping tests in wells intersecting fractures

NASA Astrophysics Data System (ADS)

Dewandel, Benoît; Lanini, Sandra; Lachassagne, Patrick; Maréchal, Jean-Christophe

2018-04-01

The behaviour of transient flow due to pumping in fractured rocks has been studied for at least the past 80 years. Analytical solutions were proposed for solving the issue of a well intersecting and pumping from one vertical, horizontal or inclined fracture in homogeneous aquifers, but their domain of application-even if covering various fracture geometries-was restricted to isotropic or anisotropic aquifers, whose potential boundaries had to be parallel or orthogonal to the fracture direction. The issue thus remains unsolved for many field cases. For example, a well intersecting and pumping a fracture in a multilayer or a dual-porosity aquifer, where intersected fractures are not necessarily parallel or orthogonal to aquifer boundaries, where several fractures with various orientations intersect the well, or the effect of pumping not only in fractures, but also in the aquifer through the screened interval of the well. Using a mathematical demonstration, we show that integrating the well-known Theis analytical solution (Theis, 1935) along the fracture axis is identical to the equally well-known analytical solution of Gringarten et al. (1974) for a uniform-flux fracture fully penetrating a homogeneous aquifer. This result implies that any existing line- or point-source solution can be used for implementing one or more discrete fractures that are intersected by the well. Several theoretical examples are presented and discussed: a single vertical fracture in a dual-porosity aquifer or in a multi-layer system (with a partially intersecting fracture); one and two inclined fractures in a leaky-aquifer system with pumping either only from the fracture(s), or also from the aquifer between fracture(s) in the screened interval of the well. For the cases with several pumping sources, analytical solutions of flowrate contribution from each individual source (fractures and well) are presented, and the drawdown behaviour according to the length of the pumped screened interval of the well is discussed. Other advantages of this proposed generic analytical solution are also given. The application of this solution to field data should provide additional field information on fracture geometry, as well as identifying the connectivity between the pumped fractures and other aquifers.

Mathematical modelling of anisotropy of illite-rich shale

USGS Publications Warehouse

Chesnokov, E.M.; Tiwary, D.K.; Bayuk, I.O.; Sparkman, M.A.; Brown, R.L.

2009-01-01

The estimation of illite-rich shale anisotropy to account for the alignment of clays and gas- or brine-filled cracks is presented via mathematical modelling. Such estimation requires analysis to interpret the dominance of one effect over another. This knowledge can help to evaluate the permeability in the unconventional reservoir, stress orientation, and the seal capacity for the conventional reservoir. Effective media modelling is used to predict the elastic properties of the illite-rich shale and to identify the dominant contributions to the shale anisotropy. We consider two principal reasons of the shale anisotropy: orientation of clay platelets and orientation of fluid-filled cracks. In reality, both of these two factors affect the shale anisotropy. The goal of this study is, first, to separately analyse the effect of these two factors to reveal the specific features in P- and S-wave velocity behaviour typical of each of the factors, and, then, consider a combined effect of the factors when the cracks are horizontally or vertically aligned. To do this, we construct four models of shale. The behaviour of P- and S-wave velocities is analysed when gas- and water-filled cracks embedded in a host matrix are randomly oriented, or horizontally or vertically aligned. The host matrix can be either isotropic or anisotropic (of VTI symmetry). In such a modelling, we use published data on mineralogy and clay platelet alignment along with other micromechanical measurements. In the model, where the host matrix is isotropic, the presence of a singularity point (when the difference VS1 - VS2 changes its sign) in shear wave velocities is an indicator of brine-filled aligned cracks. In the model with the VTI host matrix and horizontally aligned cracks filled with gas, an increase in their volume concentration leads to that the azimuth at which the singularity is observed moves toward the symmetry axis. In this case, if the clay content is small (around 20 per cent), the singularity point may even vanish. The Thomsen parameters are helpful in fluid type indication in shale. An indicator of gas-filled aligned cracks is ?? > ??. If aligned cracks in illite-rich shale are brine-filled, ?? < ??. Negative value of ?? indicates brine-filled cracks in illite-rich shale. A shale with brine-filled cracks exhibits higher Vp/Vs ratio in the vertical direction as compared to the gas-filled shale. A disorientation of clay platelets and brine-filled cracks may lead to that the singularity point is absent for brine-saturated shale as well. In this case one can also observe ?? > ?? and decreased values of Vp/Vs in the vertical direction as in the case of gas-filled cracks. In the presence of vertically aligned cracks, shales exhibit distinctly revealed features of orthorhombic symmetry. The results have important applications where seismic measurements are applied to predict the maturity state of the shale. ?? 2009 The Authors Journal compilation ?? 2009 RAS.

Shallow fluid pressure transients caused by seismogenic normal faults

NASA Astrophysics Data System (ADS)

Fleischmann, Karl Henry

1993-10-01

Clastic dikes, induced by paleo-seismic slip along the Jonesboro Fault, can be used to estimate the magnitude of shallow fluid pressure transients. Fractures show evidence of two phases of seismically induced dilation by escaping fluids. Initial dilation and propagation through brittle rocks was caused by expulsion of trapped reducing fluids from beneath a clay cap. Second phase fluids were thixotropic clays which flowed vertically from clay beds upwards into the main fracture. Using the differential dilation and fracture trace lengths, the fluid pressure pulse is estimated to have ranged from 0.312-0.49 MPa, which is approximately equal to the vertical load during deformation. Field observations in adjacent rocks record evidence of large-magnitude seismic events, which are consistent with the large nature of the fluid pressure fluctuation.

Mineral crystal alignment in mineralized fracture callus determined by 3D small-angle X-ray scattering

NASA Astrophysics Data System (ADS)

Liu, Yifei; Manjubala, Inderchand; Roschger, Paul; Schell, Hanna; Duda, Georg N.; Fratzl, Peter

2010-10-01

Callus tissue formed during bone fracture healing is a mixture of different tissue types as revealed by histological analysis. But the structural characteristics of mineral crystals within the healing callus are not well known. Since two-dimensional (2D) scanning small-angle X-ray scattering (sSAXS) patterns showed that the size and orientation of callus crystals vary both spatially and temporally [1] and 2D electron microscopic analysis implies an anisotropic property of the callus morphology, the mineral crystals within the callus are also expected to vary in size and orientation in 3D. Three-dimensional small-angle X-ray scattering (3D SAXS), which combines 2D SAXS patterns collected at different angles of sample tilting, has been previously applied to investigate bone minerals in horse radius [2] and oim/oim mouse femur/tibia [3]. We implement a similar 3D SAXS method but with a different way of data analysis to gather information on the mineral alignment in fracture callus. With the proposed accurate yet fast assessment of 3D SAXS information, it was shown that the plate shaped mineral particles in the healing callus were aligned in groups with their predominant orientations occurring as a fiber texture.

Use of sinkhole and specific capacity distributions to assess vertical gradients in a karst aquifer

USGS Publications Warehouse

McCoy, K.J.; Kozar, M.D.

2008-01-01

The carbonate-rock aquifer in the Great Valley, West Virginia, USA, was evaluated using a database of 687 sinkholes and 350 specific capacity tests to assess structural, lithologic, and topographic influences on the groundwater flow system. The enhanced permeability of the aquifer is characterized in part by the many sinkholes, springs, and solutionally enlarged fractures throughout the valley. Yet, vertical components of subsurface flow in this highly heterogeneous aquifer are currently not well understood. To address this problem, this study examines the apparent relation between geologic features of the aquifer and two spatial indices of enhanced permeability attributed to aquifer karstification: (1) the distribution of sinkholes and (2) the occurrence of wells with relatively high specific capacity. Statistical results indicate that sinkholes (funnel and collapse) occur primarily along cleavage and bedding planes parallel to subparallel to strike where lateral or downward vertical gradients are highest. Conversely, high specific capacity values are common along prominent joints perpendicular or oblique to strike. The similarity of the latter distribution to that of springs suggests these fractures are areas of upward-convergent flow. These differences between sinkhole and high specific capacity distributions suggest vertical flow components are primarily controlled by the orientation of geologic structure and associated subsurface fracturing. ?? 2007 Springer-Verlag.

Effects of vertically aligned carbon nanotubes on shear performance of laminated nanocomposite bonded joints.

PubMed

Askari, Davood; Ghasemi-Nejhad, Mehrdad N

2012-08-01

The main objective is to improve the most commonly addressed weakness of the laminated composites (i.e. delamination due to poor interlaminar strength) using carbon nanotubes (CNTs) as reinforcement between the laminae and in the transverse direction. In this work, a chemical vapor deposition technique has been used to grow dense vertically aligned arrays of CNTs over the surface of chemically treated two-dimensionally woven cloth and fiber tows. The nanoforest-like fabrics can be used to fabricate three-dimensionally reinforced laminated nanocomposites. The presence of CNTs aligned normal to the layers and in-between the layers of laminated composites is expected to considerably enhance the properties of the laminates. To demonstrate the effectiveness of our approach, composite single lap-joint specimens were fabricated for interlaminar shear strength testing. It was observed that the single lap-joints with through-the-thickness CNT reinforcement can carry considerably higher shear stresses and strains. Close examination of the test specimens showed that the failure of samples with CNT nanoforests was completely cohesive, while the samples without CNT reinforcement failed adhesively. This concludes that the adhesion of adjacent carbon fabric layers can be considerably improved owing to the presence of vertically aligned arrays of CNT nanoforests.

Effects of vertically aligned carbon nanotubes on shear performance of laminated nanocomposite bonded joints

PubMed Central

Askari, Davood; Ghasemi-Nejhad, Mehrdad N

2012-01-01

The main objective is to improve the most commonly addressed weakness of the laminated composites (i.e. delamination due to poor interlaminar strength) using carbon nanotubes (CNTs) as reinforcement between the laminae and in the transverse direction. In this work, a chemical vapor deposition technique has been used to grow dense vertically aligned arrays of CNTs over the surface of chemically treated two-dimensionally woven cloth and fiber tows. The nanoforest-like fabrics can be used to fabricate three-dimensionally reinforced laminated nanocomposites. The presence of CNTs aligned normal to the layers and in-between the layers of laminated composites is expected to considerably enhance the properties of the laminates. To demonstrate the effectiveness of our approach, composite single lap-joint specimens were fabricated for interlaminar shear strength testing. It was observed that the single lap-joints with through-the-thickness CNT reinforcement can carry considerably higher shear stresses and strains. Close examination of the test specimens showed that the failure of samples with CNT nanoforests was completely cohesive, while the samples without CNT reinforcement failed adhesively. This concludes that the adhesion of adjacent carbon fabric layers can be considerably improved owing to the presence of vertically aligned arrays of CNT nanoforests. PMID:27877502

49 CFR 581.7 - Test procedures.

Code of Federal Regulations, 2014 CFR

2014-10-01

... is vertical and the impact line is horizontal at the specified height. (3) For impacts at a height... Figure 1 so that Plane A is vertical and the impact line is horizontal at the specified height. (3) For... that Plane A is vertical and the impact line is horizontal at a height within the range. (4) Align the...

Evaluation of rock/fracture interactions during steam injection through vertical hydraulic fractures

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

Kovscek, A.R.; Johnston, R.M.; Patzek, T.W.

1997-05-01

The design, results, and analysis of a steamdrive pilot in the South Belridge diatomite, Kern County, California, are reviewed. Pilot results demonstrate that steam can be injected across a 1,000-ft-tall diatomite column using hydraulically fractured wells and that significant oil is produced in response to steaming. A computationally simple numerical model is proposed and used to analyze reservoir heating and volumetric sweep by steam. Results from the analysis show that hydraulic fractures undergoing steam injection can be dynamic and asymmetrical.

Development of a fixation device for robot assisted fracture reduction of femoral shaft fractures: a biomechanical study.

PubMed

Weber-Spickschen, T S; Oszwald, M; Westphal, R; Krettek, C; Wahl, F; Gosling, T

2010-01-01

Robot assisted fracture reduction of femoral shaft fractures provides precise alignment while reducing the amount of intraoperative imaging. The connection between the robot and the fracture fragment should allow conventional intramedullary nailing, be minimally invasive and provide interim fracture stability. In our study we tested three different reduction tools: a conventional External Fixator, a Reposition-Plate and a Three-Point-Device with two variations (a 40 degrees and a 90 degrees version). We measured relative movements between the tools and the bone fragments in all translation and rotation planes. The Three-Point-Device 90 degrees showed the smallest average relative displacement and was the only device able to withstand the maximum applied load of 70 Nm without failure of any bone fragment. The Three-Point-Device 90 degrees complies with all the stipulated requirements and is a suitable interface for robot assisted fracture reduction of femoral shaft fractures.

Fractures of the Talus: State of the Art.

PubMed

Vallier, Heather A

2015-09-01

Talus fractures occur rarely but are often associated with complications and functional limitations. Urgent reduction of associated dislocations is recommended with open reduction and internal fixation of displaced fractures when adjacent soft tissue injury permits. Delayed definitive fixation may reduce the risks of wound complications and infections. Restoration of articular and axial alignment is necessary to optimize ankle and hindfoot function. Despite this, posttraumatic arthrosis occurs frequently after talar neck and body fractures, especially with comminution of the talar body. Osteonecrosis is reported in up to half of talar neck fractures, although many of these injuries will revascularize without collapse of the talar dome. Initial fracture displacement and presence of open fractures increase the risk of osteonecrosis. Talar process fractures may be subtle and easily missed on plain radiographs. Advanced imaging will provide detail to facilitate treatment planning. Therapeutic Level V. See Instructions for Authors for a complete description of levels of evidence.

Fracture controls on valley persistence: the Cairngorm Granite pluton, Scotland

NASA Astrophysics Data System (ADS)

Hall, A. M.; Gillespie, M. R.

2017-09-01

Valleys are remarkably persistent features in many different tectonic settings, but the reasons for this persistence are rarely explored. Here, we examine the structural controls on valleys in the Cairngorms Mountains, Scotland, part of the passive margin of the eastern North Atlantic. We consider valleys at three scales: straths, glens and headwater valleys. The structural controls on valleys in and around the Cairngorm Granite pluton were examined on satellite and aerial photographs and by field survey. Topographic lineaments, including valleys, show no consistent orientation with joint sets or with sheets of microgranite and pegmatitic granite. In this granite landscape, jointing is not a first-order control on valley development. Instead, glens and headwater valleys align closely to quartz veins and linear alteration zones (LAZs). LAZs are zones of weakness in the granite pluton in which late-stage hydrothermal alteration and hydro-fracturing have greatly reduced rock mass strength and increased permeability. LAZs, which can be kilometres long and >700 m deep, are the dominant controls on the orientation of valleys in the Cairngorms. LAZs formed in the roof zone of the granite intrusion. Although the Cairngorm pluton was unroofed soon after emplacement, the presence of Old Red Sandstone (ORS) outliers in the terrain to the north and east indicates that the lower relief of the sub-ORS basement surface has been lowered by <500 m. Hence, the valley patterns in and around the Cairngorms have persisted through >1 km of vertical erosion and for 400 Myr. This valley persistence is a combined product of regionally low rates of basement exhumation and of the existence of LAZs in the Cairngorm pluton and sub-parallel Caledonide fractures in the surrounding terrain with depths that exceed 1 km.

Development and application of rail defect fracture models to assess remedial actions

DOT National Transportation Integrated Search

1993-08-01

The fracture mechanics models were refined for two types of rail defects - the bolt hole crack and the vertical split head. Beam-type finite element analysis was conducted to determine the effects of joint bar looseness, rail height mismatch and trai...

Antimicrobial Properties of 2D MnO2 and MoS2 Nanomaterials Vertically Aligned on Graphene Materials and Ti3C2 MXene.

PubMed

Alimohammadi, Farbod; Sharifian Gh, Mohammad; Attanayake, Nuwan H; Thenuwara, Akila C; Gogotsi, Yury; Anasori, Babak; Strongin, Daniel R

2018-06-07

Two-dimensional (2D) nanomaterials have attracted considerable attention in biomedical and environmental applications due to their antimicrobial activity. In the interest of investigating the primary antimicrobial mode-of-action of 2D nanomaterials, we studied the antimicrobial properties of MnO 2 and MoS 2 , toward Gram-positive and Gram-negative bacteria. Bacillus subtilis and Escherichia coli bacteria were treated individually with 100 μg/mL of randomly oriented and vertically aligned nanomaterials for ∼3 h in the dark. The vertically aligned 2D MnO 2 and MoS 2 were grown on 2D sheets of graphene oxide, reduced graphene oxide, and Ti 3 C 2 MXene. Measurements to determine the viability of bacteria in the presence of the 2D nanomaterials performed by using two complementary techniques, flow cytometry, and fluorescence imaging showed that, while MnO 2 and MoS 2 nanosheets show different antibacterial activities, in both cases, Gram-positive bacteria show a higher loss in membrane integrity. Scanning electron microscopy images suggest that the 2D nanomaterials, which have a detrimental effect on bacteria viability, compromise the cell wall, leading to significant morphological changes. We propose that the peptidoglycan mesh (PM) in the bacterial wall is likely the primary target of the 2D nanomaterials. Vertically aligned 2D MnO 2 nanosheets showed the highest antimicrobial activity, suggesting that the edges of the nanosheets were likely compromising the cell walls upon contact.

Oxygen-promoted catalyst sintering influences number density, alignment, and wall number of vertically aligned carbon nanotubes

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

Shi, Wenbo; Li, Jinjing; Polsen, Erik S.

A lack of synthetic control and reproducibility during vertically aligned carbon nanotube (CNT) synthesis has stifled many promising applications of organic nanomaterials. Oxygen-containing species are particularly precarious in that they have both beneficial and deleterious effects and are notoriously difficult to control. In this paper, we demonstrated diatomic oxygen's ability, independent of water, to tune oxide-supported catalyst thin film dewetting and influence nanoscale (diameter and wall number) and macro-scale (alignment and density) properties for as-grown vertically aligned CNTs. In particular, single- or few-walled CNT forests were achieved at very low oxygen loading, with single-to-multi-walled CNT diameters ranging from 4.8 ±more » 1.3 nm to 6.4 ± 1.1 nm over 0–800 ppm O 2, and an expected variation in alignment, where both were related to the annealed catalyst morphology. Morphological differences were not the result of subsurface diffusion, but instead occurred via Ostwald ripening under several hundred ppm O 2, and this effect was mitigated by high H 2 concentrations and not due to water vapor (as confirmed in O 2-free water addition experiments), supporting the importance of O 2 specifically. Further characterization of the interface between the Fe catalyst and Al 2O 3 support revealed that either oxygen-deficit metal oxide or oxygen-adsorption on metals could be functional mechanisms for the observed catalyst nanoparticle evolution. Finally, taken as a whole, our results suggest that the impacts of O 2 and H 2 on the catalyst evolution have been underappreciated and underleveraged in CNT synthesis, and these could present a route toward facile manipulation of CNT forest morphology through control of the reactive gaseous atmosphere alone.« less

Oxygen-promoted catalyst sintering influences number density, alignment, and wall number of vertically aligned carbon nanotubes.

PubMed

Shi, Wenbo; Li, Jinjing; Polsen, Erik S; Oliver, C Ryan; Zhao, Yikun; Meshot, Eric R; Barclay, Michael; Fairbrother, D Howard; Hart, A John; Plata, Desiree L

2017-04-20

A lack of synthetic control and reproducibility during vertically aligned carbon nanotube (CNT) synthesis has stifled many promising applications of organic nanomaterials. Oxygen-containing species are particularly precarious in that they have both beneficial and deleterious effects and are notoriously difficult to control. Here, we demonstrated diatomic oxygen's ability, independent of water, to tune oxide-supported catalyst thin film dewetting and influence nanoscale (diameter and wall number) and macro-scale (alignment and density) properties for as-grown vertically aligned CNTs. In particular, single- or few-walled CNT forests were achieved at very low oxygen loading, with single-to-multi-walled CNT diameters ranging from 4.8 ± 1.3 nm to 6.4 ± 1.1 nm over 0-800 ppm O 2 , and an expected variation in alignment, where both were related to the annealed catalyst morphology. Morphological differences were not the result of subsurface diffusion, but instead occurred via Ostwald ripening under several hundred ppm O 2 , and this effect was mitigated by high H 2 concentrations and not due to water vapor (as confirmed in O 2 -free water addition experiments), supporting the importance of O 2 specifically. Further characterization of the interface between the Fe catalyst and Al 2 O 3 support revealed that either oxygen-deficit metal oxide or oxygen-adsorption on metals could be functional mechanisms for the observed catalyst nanoparticle evolution. Taken as a whole, our results suggest that the impacts of O 2 and H 2 on the catalyst evolution have been underappreciated and underleveraged in CNT synthesis, and these could present a route toward facile manipulation of CNT forest morphology through control of the reactive gaseous atmosphere alone.

Oxygen-promoted catalyst sintering influences number density, alignment, and wall number of vertically aligned carbon nanotubes

DOE PAGES

Shi, Wenbo; Li, Jinjing; Polsen, Erik S.; ...

2017-04-11

A lack of synthetic control and reproducibility during vertically aligned carbon nanotube (CNT) synthesis has stifled many promising applications of organic nanomaterials. Oxygen-containing species are particularly precarious in that they have both beneficial and deleterious effects and are notoriously difficult to control. In this paper, we demonstrated diatomic oxygen's ability, independent of water, to tune oxide-supported catalyst thin film dewetting and influence nanoscale (diameter and wall number) and macro-scale (alignment and density) properties for as-grown vertically aligned CNTs. In particular, single- or few-walled CNT forests were achieved at very low oxygen loading, with single-to-multi-walled CNT diameters ranging from 4.8 ±more » 1.3 nm to 6.4 ± 1.1 nm over 0–800 ppm O 2, and an expected variation in alignment, where both were related to the annealed catalyst morphology. Morphological differences were not the result of subsurface diffusion, but instead occurred via Ostwald ripening under several hundred ppm O 2, and this effect was mitigated by high H 2 concentrations and not due to water vapor (as confirmed in O 2-free water addition experiments), supporting the importance of O 2 specifically. Further characterization of the interface between the Fe catalyst and Al 2O 3 support revealed that either oxygen-deficit metal oxide or oxygen-adsorption on metals could be functional mechanisms for the observed catalyst nanoparticle evolution. Finally, taken as a whole, our results suggest that the impacts of O 2 and H 2 on the catalyst evolution have been underappreciated and underleveraged in CNT synthesis, and these could present a route toward facile manipulation of CNT forest morphology through control of the reactive gaseous atmosphere alone.« less

Alignment of nematic liquid crystals by inhomogeneous surfaces

NASA Astrophysics Data System (ADS)

Ong, Hiap Liew; Hurd, Alan J.; Meyer, Robert B.

1985-01-01

Variable oblique alignment of nematic liquid crystals has been achieved on microscopically inhomogeneous surfaces. The surfaces consist of small patches favoring vertical (homeotropic) alignment surrounded by a matrix favoring a planar alignment. The construction of these surfaces employs randomly distributed microscopic metal islands formed by certain metals as vapor-deposited films. Larger scale periodic patterns were made as well to verify the techniques. The results are interpreted in terms of a continuum elasticity theory and azimuthal degeneracy is also discussed.

A paradigm shift in the surgical reconstruction of extra-articular distal humeral fractures: single-column plating.

PubMed

Meloy, Gregory M; Mormino, Matthew A; Siska, Peter A; Tarkin, Ivan S

2013-11-01

The study aimed (1) to examine if there are equivalent results in terms of union, alignment and elbow functionally comparing single- to dual-column plating of AO/OTA 13A2 and A3 distal humeral fractures and (2) if there are more implant-related complications in patients managed with bicolumnar plating compared to single-column plate fixation. This was a multi-centred retrospective comparative study. The study was conducted at two academic level 1 trauma centres. A total of 105 patients were identified to have surgical management of extra-articular distal humeral fractures Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) 13A2 and AO/OTA 13A3). Patients were treated with traditional dual-column plating or a single-column posterolateral small-fragment pre-contoured locking plate used as a neutralisation device with at least five screws in the short distal segment. The patients' elbow functionality was assessed in terms of range of motion, union and alignment. In addition, the rate of complications between the groups including radial nerve palsy, implant-related complications (painful prominence and/or ulnar nerve neuritis) and elbow stiffness were compared. Patients treated with single-column plating had similar union rates and alignment. However, single-column plating resulted in a significantly better range of motion with less complications. The current study suggests that exposure/instrumentation of only the lateral column is a reliable and preferred technique. This technique allows for comparable union rates and alignment with increased elbow functionality and decreased number of complications. Copyright © 2013 Elsevier Ltd. All rights reserved.

FRICTION-FREE BALANCE

DOEpatents

Carson, N.J. Jr.; Ostrander, H.W.; Munter, C.N.

1964-03-01

A weighing device having a load-supporting vertical shaft buoyed up by mutually repellant magnets is described. The shaft is aligned by an air bearing and has an air gage to sense vertical displacement caused by weights placed on the top end of the shaft. (AEC)

New concept for in-line OLED manufacturing

NASA Astrophysics Data System (ADS)

Hoffmann, U.; Landgraf, H.; Campo, M.; Keller, S.; Koening, M.

2011-03-01

A new concept of a vertical In-Line deposition machine for large area white OLED production has been developed. The concept targets manufacturing on large substrates (>= Gen 4, 750 x 920 mm2) using linear deposition source achieving a total material utilization of >= 50 % and tact time down to 80 seconds. The continuously improved linear evaporation sources for the organic material achieve thickness uniformity on Gen 4 substrate of better than +/- 3 % and stable deposition rates down to less than 0.1 nm m/min and up to more than 100 nm m/min. For Lithium-Fluoride but also for other high evaporation temperature materials like Magnesium or Silver a linear source with uniformity better than +/- 3 % has been developed. For Aluminum we integrated a vertical oriented point source using wire feed to achieve high (> 150 nm m/min) and stable deposition rates. The machine concept includes a new vertical vacuum handling and alignment system for Gen 4 shadow masks. A complete alignment cycle for the mask can be done in less than one minute achieving alignment accuracy in the range of several 10 μm.

Fluid inclusions in calcite filled opening fractures of the Serra Alta Formation reveal paleotemperatures and composition of diagenetic fluids percolating Permian shales of the Paraná Basin

NASA Astrophysics Data System (ADS)

Teixeira, C. A. S.; Sawakuchi, A. O.; Bello, R. M. S.; Nomura, S. F.; Bertassoli, D. J.; Chamani, M. A. C.

2018-07-01

The thermal and diagenetic evolution of shale units has received renewed focus because of their emergence as unconventional hydrocarbon reservoirs. The Serra Alta Formation (SAF) is a Permian shale unit of the Paraná Basin, which is the largest South American cratonic basin. The SAF stands out as a pathway for aqueous fluids and hydrocarbon migration from the Irati organic-rich shales to the Pirambóia fluvial-eolian sandstone reservoirs. Vertical NNW and NNE opening fractures would be the main pathways for the migration of buried pore waters and aqueous fluids, besides the input of meteoric water. These fractures would be associated to the reactivation of basement discontinuities such as the Jacutinga (NE) and Guapiara (NW) faults. Thus, vertical NNE and NNW associated fractures would represent the main pathways for fluid migration in the studied area. The vertical calcite filled opening fractures from SAF record moderately low salinity (0-4.5 wt % of NaCl eq.) aqueous fluids, suggesting the input of meteoric water in the buried fracture system. Eutectic melting temperatures at -52±5 °C indicate an H2O + NaCl + CaCl2 system with CaCl2 or MgCl2 in solution. Homogenization temperatures recorded in fluid inclusion assemblages (FIAs) of calcite filled opening fractures indicate that the SAF in the studied area reached temperatures above 200 °C, suitable for generation of gaseous hydrocarbons. The recorded paleotemperatures point to a thermal peak associated with Serra Geral volcanic event during the Early Cretaceous, with the thermal effect of volcanic rock cap possibly overcoming the effect of intrusive igneous bodies. The detection of methane in SAF shale pores indicates conditions for hydrocarbon generation. However, additionally studies are necessary to confirm the thermogenic and/or biogenic origin of the methane within the SAF.

Radiological and functional outcomes 2.7 years following conservatively treated completely displaced midshaft clavicle fractures.

PubMed

Fuglesang, Hendrik F S; Flugsrud, Gunnar B; Randsborg, Per-Henrik; Stavem, Knut; Utvåg, Stein E

2016-01-01

It is unclear whether all completely displaced midshaft clavicle fractures require primary surgical intervention. The aim of this study was to elucidate the radiological and clinical outcomes after conservative treatment, and to identify subgroups at risk of an inferior outcome. Retrospective case series. Level II trauma center. Between 2005 and 2008, 122 patients were conservatively treated for a completely displaced midshaft clavicle fracture of whom 92 were eligible for inclusion in this study. Of these, 59 completed the study after a median of 2.7 years after the fracture (min-max, 1.1-4.9). The patients received the standard treatment administered at our institution at the time: nonsurgically with a sling without physiotherapy. Patients with painful nonunions were subsequently offered surgery. At follow-up, the patients' Disabilities of Arm, Shoulder, and Hand (DASH) and the Constant scores were evaluated. Radiographs were taken at follow-up and compared to those taken acutely. Nonunion was found in 9 of the 59 (15.3%) patients. Twenty-four (24%) patients reported a fair-to-poor DASH score (i.e. >20). Patients with fractures that were vertically displaced by more than 100% (one bone width) were significantly less satisfied than those with fractures vertically displaced at 100% (p = 0.04). Initial shortening of more than 15 mm was not associated with a worse outcome or nonunion. The odds ratio of developing a nonunion increased with age (p = 0.04). By treating completely displaced midshaft clavicle fractures conservatively with a sling and offering plate fixation for eventual painful nonunions, we found a 24% risk of a fair or poor clinical result with a DASH score over 20. A vertical displacement of more than 100 % between the main fragments on the initial radiograph was associated with an inferior clinical outcome in this study. IV.

Fracture characterization by means of attenuation and generation of tube waves in fractured crystalline rock at Mirror Lake, New Hampshire

USGS Publications Warehouse

Hardin, E.L.; Cheng, C.H.; Paillet, F.L.; Mendelson, J.D.

1987-01-01

Results are presented from experiments carried out in conjunction with the U. S. Geological Survey at the Hubbard Brook Experimental Forest near Mirror Lake, New Hampshire. The study focuses on our ability to obtain orientation and transmissivity estimates of naturally occurring fractures. The collected data set includes a four-offset hydrophone vertical seismic profile, full waveform acoustic logs at 5, 15, and 34 kHz, borehole televiewer, temperature, resistivity, and self-potential logs, and borehole-to-borehole pump test data. Borehole televiewer and other geophysical logs indicate that permeable fractures intersect the Mirror Lake boreholes at numerous depths, but less than half of these fractures appear to have significant permeability beyond the annulus of drilling disturbance on the basis of acoustic waveform log analysis. The vertical seismic profiling (VSP) data indicate a single major permeable fracture near a depth of 44 m, corresponding to one of the most permeable fractures identified in the acoustic waveform log analysis. VSP data also indicate a somewhat less permeable fracture at 220 m and possible fractures at depths of 103 and 135 m; all correspond to major permeable fractures in the acoustic waveform data set. Pump test data confirm the presence of a hydraulic connection between the Mirror Lake boreholes through a shallow dipping zone of permeability at 44 m in depth. Effective fracture apertures calculated from modeled transmissivities correspond to those estimated for the largest fractures indicated on acoustic waveform logs but are over an order of magnitude larger than effective apertures calculated from tube waves in the VSP data set. This discrepancy is attributed to the effect of fracture stiffness. A new model is presented to account for the mechanical strength of asperities in resisting fracture closure during the passage of seismic waves during the generation of VSPs.

Influence of packing density and surface roughness of vertically-aligned carbon nanotubes on adhesive properties of gecko-inspired mimetics.

PubMed

Chen, Bingan; Zhong, Guofang; Oppenheimer, Pola Goldberg; Zhang, Can; Tornatzky, Hans; Esconjauregui, Santiago; Hofmann, Stephan; Robertson, John

2015-02-18

We have systematically studied the macroscopic adhesive properties of vertically aligned nanotube arrays with various packing density and roughness. Using a tensile setup in shear and normal adhesion, we find that there exists a maximum packing density for nanotube arrays to have adhesive properties. Too highly packed tubes do not offer intertube space for tube bending and side-wall contact to surfaces, thus exhibiting no adhesive properties. Likewise, we also show that the surface roughness of the arrays strongly influences the adhesion properties and the reusability of the tubes. Increasing the surface roughness of the array strengthens the adhesion in the normal direction, but weakens it in the shear direction. Altogether, these results allow progress toward mimicking the gecko's vertical mobility.

Continuous high-yield production of vertically aligned carbon nanotubes on 2D and 3D substrates.

PubMed

Guzmán de Villoria, Roberto; Hart, A John; Wardle, Brian L

2011-06-28

Vertically aligned carbon nanotubes (VACNTs) have certain advantages over bulk CNT powders and randomly oriented CNT mats for applications in flexible electronic devices, filtration membranes, biosensors and multifunctional aerospace materials. Here, a machine and a process to synthesize VACNTs in a continuous manner are presented showing uniform growth on 2D and 3D substrates, including alumina fibers, silicon wafer pieces, and stainless steel foils. Aligned multiwalled carbon nanotubes (MWNT) are synthesized at substrate feed rates of up to 6.8 cm/min, and the CNTs reach up to 60 μm in length depending on residence time in the reactor. In addition to the aligned morphology indicative of high yield growth, transmission electron microscopy and Raman spectroscopy reveal that the CNTs are of comparable quality to CNTs grown via a similar batch process. A significant reduction in time, reaction products, gases, and energy is demonstrated relative to batch processing, paving the way for industrial production of VACNTs.

Biomechanical analysis of posteromedial tibial plateau split fracture fixation.

PubMed

Zeng, Zhi-Min; Luo, Cong-Feng; Putnis, Sven; Zeng, Bing-Fang

2011-01-01

The purpose of this study was to compare the biomechanical strength of four different fixation methods for a posteromedial tibial plateau split fracture. Twenty-eight tibial plateau fractures were simulated using right-sided synthetic tibiae models. Each fracture model was randomly instrumented with one of the four following constructs, anteroposterior lag-screws, an anteromedial limited contact dynamic compression plate (LC-DCP), a lateral locking plate, or a posterior T-shaped buttress plate. Vertical subsidence of the posteromedial fragment was measured from 500 N to 1500 N during biomechanical testing, the maximum load to failure was also determined. It was found that the posterior T-shaped buttress plate allowed the least subsidence of the posteromedial fragment and produced the highest mean failure load than each of the other three constructs (P=0.00). There was no statistical significant difference between using lag screws or an anteromedial LC-DCP construct for the vertical subsidence at a 1500 N load and the load to failure (P>0.05). This study showed that a posterior-based buttress technique is biomechanically the most stable in-vitro fixation method for posteromedial split tibial plateau fractures, with AP screws and anteromedial-based LC-DCP are not as stable for this type of fracture. Copyright © 2010 Elsevier B.V. All rights reserved.

Radiographic diagnosis of sagittal plane rotational displacement in pelvic fractures: a cadaveric model and clinical case study.

PubMed

Shui, Xiaolong; Ying, Xiaozhou; Kong, Jianzhong; Feng, Yongzeng; Hu, Wei; Guo, Xiaoshan; Wang, Gang

2015-08-01

Our objective was to measure the sagittal plane rotational (flexion and extension) displacement of hemipelvis radiologically and analyze the ratio of flexion and extension displacement of unstable pelvic fractures. We used 8 cadaveric models to study the radiographic evidence of pelvic fractures in the sagittal plane. We performed pelvic osteotomy on 8 cadavers to simulate anterior and posterior pelvic ring injury. Radiological data were measured in the flexion and extension group under different angles (5°, 10°, 15°, 20°, and 25°). We retrospectively reviewed 164 patients who were diagnosed with a unilateral fracture of the pelvis. Pelvic ring displacement was identified and recorded radiographically in cadaveric models. The flexion and extension displacement of pelvic fractures was measured in terms of the vertical distance of fracture from the top of iliac crest to the pubic tubercle (CD) or from the top of iliac crest to the lowest point of ischial tuberosity (AB). Fifty-seven pelves showed flexion displacement and 15 showed extension displacement. Closed reduction including internal fixation and external fixation was successfully used in 141 cases (86.0 %). The success rates of closed reduction in flexion and extension displacement groups were 77 and 73 %, respectively, which were lower than in unstable pelvic ring fractures. The sagittal plane rotation (flexion and extension) displacement of pelvic fractures could be measured by special points and lines on the radiographs. Minimally invasive reduction should be based on clearly identified differences between the sagittal plane rotation and the vertical displacement of pelvic fractures.

Ground-based hyperspectral imaging and terrestrial laser scanning for fracture characterization in the Mississippian Boone Formation

NASA Astrophysics Data System (ADS)

Sun, Lei; Khan, Shuhab D.; Sarmiento, Sergio; Lakshmikantha, M. R.; Zhou, Huawei

2017-12-01

Petroleum geoscientists have been using cores and well logs to study source rocks and reservoirs, however, the inherent discontinuous nature of these data cannot account for horizontal heterogeneities. Modern exploitation requires better understanding of important source rocks and reservoirs at outcrop scale. Remote sensing of outcrops is becoming a first order tool for reservoir analog studies including horizontal heterogeneities. This work used ground-based hyperspectral imaging, terrestrial laser scanning (TLS), and high-resolution photography to study a roadcut of the Boone Formation at Bella Vista, northwest Arkansas, and developed an outcrop model for reservoir analog analyses. The petroliferous Boone Formation consists of fossiliferous limestones interbedded with chert of early Mississippian age. We used remote sensing techniques to identify rock types and to collect 3D geometrical data. Mixture tuned matched filtering classification of hyperspectral data show that the outcrop is mostly limestones with interbedded chert nodules. 1315 fractures were classified according to their strata-bounding relationships, among these, larger fractures are dominantly striking in ENE - WSW directions. Fracture extraction data show that chert holds more fractures than limestones, and both vertical and horizontal heterogeneities exist in chert nodule distribution. Utilizing ground-based remote sensing, we have assembled a virtual outcrop model to extract mineral composition as well as fracture data from the model. We inferred anisotropy in vertical fracture permeability based on the dominancy of fracture orientations, the preferential distribution of fractures and distribution of chert nodules. These data are beneficial in reservoir analogs to study rock mechanics and fluid flow, and to improve well performances.

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

PubMed Central

Vollebregt, Sten; Ishihara, Ryoichi

2015-01-01

We demonstrate a method for the low temperature growth (350 °C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-κ dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used. PMID:26709530

Self-Organizing Fluid Convection Patterns in an en Echelon Fault Array

NASA Astrophysics Data System (ADS)

Patterson, James W.; Driesner, Thomas; Matthai, Stephan K.

2018-05-01

We present three-dimensional numerical simulations of natural convection in buried, vertical en echelon faults in impermeable host rock. Despite the fractures being hydraulically disconnected, convection within each fracture alters the temperature field in the surrounding host rock, altering convection in neighboring fractures. This leads to self-organization of coherent patterns of upward/downward flow and heating/cooling of the host rock spanning the entire fault array. This "synchronization" effect occurs when fracture spacing is less than the width of convection cells within the fractures, which is controlled by fracture transmissivity (permeability times thickness) and heterogeneity. Narrow fracture spacing and synchronization enhance convective fluid flow within fractures and cause convection to initiate earlier, even lowering the critical transmissivity necessary for convection initiation. Heat flow through the en echelon region, however, is enhanced only in low-transmissivity fractures, while heat flow in high-permeability fractures is reduced due to thermal interference between fractures.

The geometry and volume of melt beneath Ethiopia

NASA Astrophysics Data System (ADS)

Kendall, J. M.; Hammond, J. O. S.

2016-12-01

A range of seismic measurements can be used to map melt distribution in the crust and uppermost mantle. These include seismic P- and S-wave velocities derived from surface- and body-wave tomography, Vp/Vs ratios obtained from receiver functions, and estimates of seismic anisotropy and attenuation. The most obvious melt parameter that seismic data might be sensitive to is volume fraction. However, such data are more sensitive to the aspect ratio of melt inclusions, which is controlled by the melt wetting angle or in other words the shape of the melt inclusion. To better understand this we perform numerical modelling, varying the shape and amount of melt, to show how various seismic phases are effected by melt. To consider the effects on seismic anisotropy we assume that the melt can be stored in pockets of melt that are either horizontally or vertically aligned (e.g., sills versus dykes). We then consider a range of seismic observations from the rifting environment of Ethiopia. Recent studies of P- and S-wave tomography, Rayleigh and Love waves, and Pn or wide angle P-wave refractions provide provide complimentary constraints on melt volume, orientation and inclusion aspect ratio. Furthermore, receiver functions and shear-wave splitting in body waves show strong anisotropy in this region and can be used to constrain the strike of vertically-aligned partial melt. We show that melt in the mantle beneath Ethiopia is likely stored in low aspect ratio disk-like inclusions, suggesting melt is not in textural equilibrium. We estimate that 2-7% vertically aligned melt is stored beneath the Main Ethiopian Rift, >6% horizontally and vertically aligned melt is stored beneath the Afar-region of the Red Sea Rift and 1-6% horizontally aligned melt is stored beneath the Danakil microplate. This supports ideas of strong shear-derived segregation of melt in narrow parts of the rift and large volumes of melt beneath Afar.

Monolayer formation of human osteoblastic cells on vertically aligned multiwalled carbon nanotube scaffolds.

PubMed

Lobo, Anderson O; Antunes, Erica F; Palma, Mariana Bs; Pacheco-Soares, Cristina; Trava-Airoldi, Vladimir J; Corat, Evaldo J

2010-03-12

Monolayer formation of SaOS-2 (human osteoblast-like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non-toxicity and the flat spreading with monolayer formation of the SaOs-2 on VACNT scaffolds surface indicate that they can be used for biomedical applications.

Modeling and experimental study of resistive switching in vertically aligned carbon nanotubes

NASA Astrophysics Data System (ADS)

Ageev, O. A.; Blinov, Yu F.; Ilina, M. V.; Ilin, O. I.; Smirnov, V. A.

2016-08-01

Model of the resistive switching in vertically aligned carbon nanotube (VA CNT) taking into account the processes of deformation, polarization and piezoelectric charge accumulation have been developed. Origin of hysteresis in VA CNT-based structure is described. Based on modeling results the VACNTs-based structure has been created. The ration resistance of high-resistance to low-resistance states of the VACNTs-based structure amounts 48. The correlation the modeling results with experimental studies is shown. The results can be used in the development nanoelectronics devices based on VA CNTs, including the nonvolatile resistive random-access memory.

Dielectric properties of vertically aligned multi-walled carbon nanotubes in the terahertz and mid-infrared range

NASA Astrophysics Data System (ADS)

Thomson, Mark D.; Zouaghi, Wissem; Meng, Fanqi; Wiecha, Matthias M.; Rabia, Kaneez; Heinlein, Thorsten; Hussein, Laith; Babu, Deepu; Yadav, Sandeep; Engstler, Jörg; Schneider, Jörg J.; Nicoloso, Norbert; Rychetský, Ivan; Kužel, Petr; Roskos, Hartmut G.

2018-01-01

We investigate the broadband dielectric properties of vertically aligned, multi-wall carbon nanotubes (VACNT), over both the terahertz (THz) and mid-infrared spectral ranges. The nominally undoped, metallic VACNT samples are probed at normal incidence, i.e. the response is predominantly due to polarisation perpendicular to the CNT axis. A detailed comparison of various conductivity models and previously reported results is presented for the non-Drude behaviour we observe in the conventional THz range (up to 2.5 THz). Extension to the mid-infrared range reveals an absorption peak at \

Growth rate of plasma-synthesized vertically aligned carbon nanofibers

NASA Astrophysics Data System (ADS)

Merkulov, Vladimir I.; Melechko, A. V.; Guillorn, M. A.; Lowndes, D. H.; Simpson, M. L.

2002-08-01

Vertically aligned carbon nanofibers (VACNFs) were synthesized by direct-current plasma enhanced chemical vapor deposition using acetylene and ammonia as the gas source. The mechanisms responsible for changing the nanofiber growth rate were studied and phenomenological models are proposed. The feedstock for VACNF growth is suggested to consist mainly of radicals formed in the plasma and not the unexcited acetylene gas molecules. The growth rate is shown to increase dramatically by changing the radical transport mechanism from diffusive to forced flow, which was accomplished by increasing the gas flow in the direction perpendicular to the substrate.

The Effect of Sagittal Plane Deformities after Tibial Plateau Fractures to Functions and Instability of Knee Joint.

PubMed

Erdil, M; Yildiz, F; Kuyucu, E; Sayar, Ş; Polat, G; Ceylan, H H; Koçyiğit, F

2016-01-01

The objective of this study is to evaluate the effect of posterior tibial slope after fracture healing on antero-posterior knee laxity, functional outcome and patient satisfaction. 126 patients who were treated for tibial plateau fractures between 2008-2013 in the orthopedics and traumatology department of our institution were evaluated for the study. Patients were treated with open reduction and internal fixation, arthroscopy assisted minimally invasive osteosynthesis or conservative treatment. Mean posterior tibial slope after the treatment was 6.91 ± 5.11 and there was no significant difference when compared to the uninvolved side 6.42 ± 4,21 (p = 0.794). Knee laxity in anterior-posterior plane was 6.14 ± 2.11 and 5.95 ± 2.25 respectively on healthy and injured side. The difference of mean laxity in anterior-posterior plane between two sides was statistically significant. In this study we found no difference in laxity between the injured and healthy knees. However Tegner score decreased significantly in patients who had greater laxity difference between the knees. We did not find significant difference between fracture type and laxity, IKDC functional scores independent of the ligamentous injury. In conclusion despite coronal alignment is taken into consideration in treatment of tibial plateau fractures, sagittal alignment is reasonably important for stability and should not be ignored.

[Correction of refractive errors in patients with strabismus. Part I. Clinical problems associated with refraction, accommodation and convergence].

PubMed

Tokarz-Sawińska, Ewa

2012-01-01

In Part I the problems associated with refraction, accommodation and convergence and their role in proper eye position/visual alignment of the eyes as well as convergent, divergent and vertical alignment of the eyes have been described.

Discrimination of Mirror-Image shapes by Young Children

ERIC Educational Resources Information Center

Thompson, G. Brian

1975-01-01

Conducted two experiments which employed discrimination learning methods to test predictions related to the difficulty of discrimination of lateral reversals and of inversions when shapes are presented: (1) successively, (2) simultaneously in lateral alignment, and (3) simultaneously in vertical alignment. Subjects were 6-year-old children. (SDH)

STRUCTURAL AND HYDROGEOLOGIC APPLICATIONS OF REMOTE SENSING DATA, EASTERN YUCATAN PENINSULA, MEXICO.

USGS Publications Warehouse

Southworth, C. Scott; ,

1984-01-01

Landsat and Seasat satellite images and aerial photographs of eastern Yucatan Peninsula, Mexico, were analyzed to delineate geologic controls of ground water. Significant interpretation results include the delineation of linear topographic swales, interpreted as fractures, extending more than 50 km along strike from the previously known limit of the Holbox fracture system; the alignment of sink holes (cenotes) and inlets (caletas) on strike with existing faults and fracture systems; and the identification of tonal anomalies in Ingles Lagoon suggesting fresh-water discharge from a submarine spring.

Vertically aligned BCN nanotubes with high capacitance.

PubMed

Iyyamperumal, Eswaramoorthi; Wang, Shuangyin; Dai, Liming

2012-06-26

Using a chemical vapor deposition method, we have synthesized vertically aligned BCN nanotubes (VA-BCNs) on a Ni-Fe-coated SiO(2)/Si substrate from a melamine diborate precursor. The effects of pyrolysis conditions on the morphology and thermal property of grown nanotubes, as well as the nanostructure and composition of an individual BCN nanotube, were systematically studied. It was found that nitrogen atoms are bonded to carbons in both graphitic and pyridinic forms and that the resultant VA-BCNs grown at 1000 °C show the highest specific capacitance (321.0 F/g) with an excellent rate capability and high durability with respect to nonaligned BCN (167.3 F/g) and undoped multiwalled carbon nanotubes (117.3 F/g) due to synergetic effects arising from the combined co-doping of B and N in CNTs and the well-aligned nanotube structure.

Vertically aligned single-walled carbon nanotubes by chemical assembly--methodology, properties, and applications.

PubMed

Diao, Peng; Liu, Zhongfan

2010-04-06

Single-walled carbon nanotubes (SWNTs), as one of the most promising one-dimension nanomaterials due to its unique structure, peculiar chemical, mechanical, thermal, and electronic properties, have long been considered as an important building block to construct ordered alignments. Vertically aligned SWNTs (v-SWNTs) have been successfully prepared by using direct growth and chemical assembly strategies. In this review, we focus explicitly on the v-SWNTs fabricated via chemical assembly strategy. We provide the readers with a full and systematic summary covering the advances in all aspects of this area, including various approaches for the preparation of v-SWNTs using chemical assembly techniques, characterization, assembly kinetics, and electrochemical properties of v-SWNTs. We also review the applications of v-SWNTs in electrochemical and bioelectrochemical sensors, photoelectric conversion, and scanning probe microscopy.

Long Range In-Plane Order of Oriented Diblock Copolymer Thin Films by Graphoepitaxy

NASA Astrophysics Data System (ADS)

Fontana, Scott; Dadmun, Mark; Lowndes, Douglas

2003-03-01

Previous work by Russell and coworkers has demonstrated that controlling the interfacial energies and wetting behavior of an asymmetric diblock copolymer enables the control of the orientation of its microphases. In particular the cylindrical phase can be readily aligned perpendicular to a substrate when it is placed on a surface that is neutral to both components of the copolymer. The minor phase, PMMA may then be removed using UV radiation leaving a nanoporous template. In this work, we will report long range, in-plane ordering of the hexagonally packed nanopores that is achieved using graphoepitaxy. The long range ordered and vertically aligned diblock copolymer film can be used to produce arrays of catalytic nickel dots, which grow vertically aligned carbon nano-fibers (VACNF), resulting in a well ordered array of VACNFs.

Vertical Si nanowire arrays fabricated by magnetically guided metal-assisted chemical etching

NASA Astrophysics Data System (ADS)

Chun, Dong Won; Kim, Tae Kyoung; Choi, Duyoung; Caldwell, Elizabeth; Kim, Young Jin; Paik, Jae Cheol; Jin, Sungho; Chen, Renkun

2016-11-01

In this work, vertically aligned Si nanowire arrays were fabricated by magnetically guided metal-assisted directional chemical etching. Using an anodized aluminum oxide template as a shadow mask, nanoscale Ni dot arrays were fabricated on an Si wafer to serve as a mask to protect the Si during the etching. For the magnetically guided chemical etching, we deposited a tri-layer metal catalyst (Au/Fe/Au) in a Swiss-cheese configuration and etched the sample under the magnetic field to improve the directionality of the Si nanowire etching and increase the etching rate along the vertical direction. After the etching, the nanowires were dried with minimal surface-tension-induced aggregation by utilizing a supercritical CO2 drying procedure. High-resolution transmission electron microscopy (HR-TEM) analysis confirmed the formation of single-crystal Si nanowires. The method developed here for producing vertically aligned Si nanowire arrays could find a wide range of applications in electrochemical and electronic devices.

Enhanced solar photoelectrochemical conversion efficiency of the hydrothermally-deposited TiO2 nanorod arrays: Effects of the light trapping and optimum charge transfer

NASA Astrophysics Data System (ADS)

An, Gil Woo; Mahadik, Mahadeo A.; Chae, Weon-Sik; Kim, Hyun Gyu; Cho, Min; Jang, Jum Suk

2018-05-01

The vertically aligned TiO2 nanorod arrays (NRA) with manipulated aspect ratio were hydrothermally synthesized by changing the amount of the titanium (Ti) precursor in the initial growth solution. FE-SEM images show the optimum morphology, density and aspect ratio of the well-aligned TB-1.2 NRs on the surface of the FTO substrate. The UV-vis-absorption measurements revealed that a sample prepared at TB-1.2 can provide an increased light trapping effect. PEC analyses demonstrated that the TiO2 nanorods deposited at TB-1.2 of Titanium butoxide show a relatively high PEC conversion efficiency (3.5 times) compared with the TB-0.8 prepared TiO2 at a 1.0 V versus RHE. The higher PEC performance is believed to be the result of an enhancement of the optimum aspect ratio, light trapping, an efficient charge separation, and the high carrier transport in the vertically aligned TiO2 NRs. Further, the PEC based organic dye degradation experiments showed 77% and 94% removal of Orange II and methylene blue respectively. Additionally, 109 μmol h-1 cm-2 hydrogen generations were attributed using optimized vertically aligned TiO2 NRA's. Thus, the appropriate morphology manipulated the TiO2 NRAs are useful for solar conversion applications.

Displaced clavicle fractures in adolescents: facts, controversies, and current trends.

PubMed

Pandya, Nirav K; Namdari, Surena; Hosalkar, Harish S

2012-08-01

There is an increasing trend toward stabilization and fixation of markedly displaced midshaft clavicle fractures in adolescents. Recent studies in the adult literature have shown a greater prevalence of symptomatic malunion, nonunion, and poor functional outcomes after nonsurgical management of displaced fractures. Fixation of displaced midshaft clavicle fractures can restore length and alignment, resulting in shorter time to union. Symptomatic malunion after significantly displaced fractures in adolescents may be more common than previously thought. Adolescents often have high functional demands, and their remodeling potential is limited. Knowledge of bone biology and the effects of shortening, angulation, and rotation on shoulder girdle mechanics is critical in decision making in order to increase the likelihood of optimal results at skeletal maturity. Selection of fixation is dependent on many factors, including fracture type, patient age, skeletal maturity, and surgeon comfort.

External fixation techniques for distal radius fractures.

PubMed

Capo, John T; Swan, Kenneth G; Tan, Virak

2006-04-01

Fractures of the distal radius are common injuries. Low-energy or high-energy mechanisms may be involved. Unstable distal radius fractures present a challenge to the treating orthopaedic surgeon. External fixation is a valuable instrument for fracture reduction and stabilization. Limited open incisions, early range of motion, and treatment of complex wounds are a few of the benefits of external fixation. Fixators may be spanning or nonbridging and may be used alone or in combination with other stabilization methods to obtain and maintain distal radius fracture reduction. Augmentation with percutaneous wires allows for optimal fracture stabilization with physiologic alignment of the wrist. Moderate distraction at the carpus does not induce postoperative stiffness. The distal radioulnar joint must be assessed and may need to be stabilized. Complications of external fixation are usually minor, but must be anticipated and treated early. Level V (expert opinion).

Laser-fiber coupling by means of a silicon micro-optical bench and a self-aligned soldering process

NASA Astrophysics Data System (ADS)

Schmidt, Jan P.; Cordes, A.; Mueller, Joerg; Burkhardt, Hans

1995-02-01

The alignment of laser diodes to monomode fibers has to meet extremely close tolerances for a low coupling loss. Typically < 0.5 micrometers in lateral and vertical direction and less than two degrees in angle deviation are allowed for a coupling loss below 2 dB. Presently such close tolerances can only be met by gluing or soldering both components on separate base plates and combining them via piezoactivated alignment monitoring the output of the circuit and then gluing them using UV-hardening epoxies. Such a procedure is not very economical and not useful for mass applications. This paper presents the principle and realization of a silicon micro-optical bench for laser-fiber-coupling, which avoids the above mentioned disadvantages. The micro-optical bench is realized using well controlled plasma etching processes to transfer the guiding patterns for the laser and the fiber into the silicon substrate, keeping geometry tolerances below +/- 0.5 micrometers in lateral and vertical direction. Mounting the laser diode by means of a self-aligned soldering process, an additional contribution to the precise alignment of the laser is further improved.

Fabrication and characterisation of a novel biomimetic anisotropic ceramic/polymer-infiltrated composite material.

PubMed

Al-Jawoosh, Sara; Ireland, Anthony; Su, Bo

2018-04-10

To fabricate and characterise a novel biomimetic composite material consisting of aligned porous ceramic preforms infiltrated with polymer. Freeze-casting was used to fabricate and control the microstructure and porosity of ceramic preforms, which were subsequently infiltrated with 40-50% by volume UDMA-TEGDMA polymer. The composite materials were then subjected to characterisation, namely density, compression, three-point bend, hardness and fracture toughness testing. Samples were also subjected to scanning electron microscopy and computerised tomography (Micro-CT). Three-dimensional aligned honeycomb-like ceramic structures were produced and full interpenetration of the polymer phase was observed using micro-CT. Depending on the volume fraction of the ceramic preform, the density of the final composite ranged from 2.92 to 3.36g/cm 3 , compressive strength ranged from 206.26 to 253.97MPa, flexural strength from 97.73 to 145.65MPa, hardness ranged from 1.46 to 1.62GPa, and fracture toughness from 3.91 to 4.86MPam 1/2 . Freeze-casting provides a novel method to engineer composite materials with a unique aligned honeycomb-like interpenetrating structure, consisting of two continuous phases, inorganic and organic. There was a correlation between the ceramic fraction and the subsequent, density, strength, hardness and fracture toughness of the composite material. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Induction logging device with a pair of mutually perpendicular bucking coils

DOEpatents

Koelle, Alfred R.; Landt, Jeremy A.

1981-01-01

An instrument is disclosed for mapping vertical conductive fractures in a resistive bedrock, magnetically inducing eddy currents by a pair of vertically oriented, mutually perpendicular, coplanar coils. The eddy currents drive magnetic fields which are picked up by a second, similar pair of coils.

Shear Wave Generation by Explosions in Anisotropic Crystalline Rock

NASA Astrophysics Data System (ADS)

Rogers-Martinez, M. A.; Sammis, C. G.; Stroujkova, A. F.

2015-12-01

The use of seismic waves to discriminate between earthquakes and underground explosions is complicated by the observation that explosions routinely radiate strong S waves. Whether these S waves are primarily generated by non-linear processes at the source, or by mode conversions and scattering along the path remains an open question. It has been demonstrated that S waves are generated at the source by any mechanism that breaks the spherical symmetry of the explosion. Examples of such mechanisms include tectonic shear stress, spall, and anisotropy in the emplacement medium. Many crystalline rock massifs are transversely isotropic because they contain aligned fractures over a range of scales from microfractures at the grain scale (called the rift) to regional sets of joints. In this study we use a micromechanical damage mechanics to model the fracture damage patterns and seismic radiation generated by explosions in a material in which the initial distribution of fractures has a preferred direction. Our simulations are compared with a set of field experiments in a granite quarry in Barre, VT conducted by New England Research and Weston Geophysical. Barre granite has a strong rift plane of aligned microfractures. Our model captures two important results of these field studies: 1) the spatial extent of rock fracture and generation of S waves depends on the burn-rate of the explosion and 2) the resultant damage is anisotropic with most damage occurring in the preferred direction of the microfractures (the rift plane in the granite). The physical reason damage is enhanced in the rift direction is that the mode I stress intensity factor is large for each fracture in the array of parallel fractures in the rift plane. Tensile opening on the rift plane plus sliding on the preexisting fractures make strong non-spherical contributions to the moment tensor in the far-field.

The surface geometry of inherited joint and fracture trace patterns resulting from active and passive deformation

NASA Technical Reports Server (NTRS)

Podwysocki, M. H.; Gold, D. P.

1974-01-01

Hypothetical models are considered for detecting subsurface structure from the fracture or joint pattern, which may be influenced by the structure and propagated to the surface. Various patterns of an initially orthogonal fracture grid are modeled according to active and passive deformation mechanisms. In the active periclinal structure with a vertical axis, fracture frequency increased both over the dome and basin, and remained constant with decreasing depth to the structure. For passive periclinal features such as a reef or sand body, fracture frequency is determined by the arc of curvature and showed a reduction over the reefmound and increased over the basin.

A facile method to align carbon nanotubes on polymeric membrane substrate

PubMed Central

Zhao, Haiyang; Zhou, Zhijun; Dong, Hang; Zhang, Lin; Chen, Huanlin; Hou, Lian

2013-01-01

The alignment of carbon nanotubes (CNT) is the fundamental requirement to ensure their excellent functions but seems to be desolated in recent years. A facile method, hot-press combined with peel-off (HPPO), is introduced here, through which CNT can be successfully vertically aligned on the polymeric membrane substrate. Shear force and mechanical stretch are proposed to be the main forces to align the tubes perpendicular to the substrate surface during the peel-off process. The alignment of CNT keeps its orientation in a thin hybrid membrane by dip-coating cellulose acetate dope solution. It is expected that the stable alignment of CNT by HPPO would contribute to the realization of its potential applications. PMID:24326297

Self-aligned gated field emission devices using single carbon nanofiber cathodes

NASA Astrophysics Data System (ADS)

Guillorn, M. A.; Melechko, A. V.; Merkulov, V. I.; Hensley, D. K.; Simpson, M. L.; Lowndes, D. H.

2002-11-01

We report on the fabrication and operation of integrated gated field emission devices using single vertically aligned carbon nanofiber (VACNF) cathodes where the gate aperture has been formed using a self-aligned technique based on chemical mechanical polishing. We find that this method for producing gated cathode devices easily achieves structures with gate apertures on the order of 2 mum that show good concentric alignment to the VACNF emitter. The operation of these devices was explored and field emission characteristics that fit well to the Fowler-Nordheim model of emission was demonstrated.

A reliable method to grow vertically-aligned silicon nanowires by a novel ramp-cooling process

NASA Astrophysics Data System (ADS)

Ho, Tzuen-Wei; Hong, Franklin Chau-Nan

2012-08-01

We have grown silicon nanowires (SiNWs) on Si (1 1 1) substrates by gold-catalyzed vapor-liquid-solid (VLS) process using tetrachlorosilane (SiCl4) in a hot-wall chemical vapor deposition reactor. Even under the optimized conditions including H2 annealing to reduce the surface native oxide, epitaxial SiNWs of 150-200 nm in diameter often grew along all four <1 1 1> family directions with one direction vertical and three others inclined to the surface. Therefore, the growth of high degree ordered SiNW arrays along [1 1 1] only was attempted on Au-coated Si (1 1 1) by a ramp-cooling process utilizing the liquid phase epitaxy (LPE) mechanism. The Au-coated Si substrate was first annealed in H2 at 650 °C to form Au-Si alloy nanoparticles, and then ramp-cooled at a controlled rate to precipitate epitaxial Si seeds on the substrate based on LPE mechanism. The substrate was further heated in SiCl4/H2 to 850 °C for the VLS growths of SiNWs on the Si seeds. Thus, almost 100% vertically-aligned SiNWs along [1 1 1] only could be reproducibly grown on Si (1 1 1), without using a template or patterning the metal catalyst. The high-density vertically-aligned SiNWs have good potentials for solar cells and nano-devices.

Taxel-addressable matrix of vertical nanowire piezotronic transistors

DOEpatents

Wang, Zhong Lin; Wu, Wenzhuo; Wen, Xiaonan

2015-05-05

A tactile sensing matrix includes a substrate, a first plurality of elongated electrode structures, a plurality of vertically aligned piezoelectric members, an insulating layer infused into the piezoelectric members and a second plurality of elongated electrode structures. The first plurality of elongated electrode structures is disposed on the substrate along a first orientation. The vertically aligned piezoelectric members is disposed on the first plurality of elongated electrode structures and form a matrix having columns of piezoelectric members disposed along the first orientation and rows of piezoelectric members disposed along a second orientation that is transverse to the first orientation. The second plurality of elongated electrode structures is disposed on the insulating layer along the second orientation. The elongated electrode structures form a Schottky contact with the piezoelectric members. When pressure is applied to the piezoelectric members, current flow therethrough is modulated.

The Development of High-Density Vertical Silicon Nanowires and Their Application in a Heterojunction Diode.

PubMed

Chang, Wen-Chung; Su, Sheng-Chien; Wu, Chia-Ching

2016-06-30

Vertically aligned p-type silicon nanowire (SiNW) arrays were fabricated through metal-assisted chemical etching (MACE) of Si wafers. An indium tin oxide/indium zinc oxide/silicon nanowire (ITO/IZO/SiNW) heterojunction diode was formed by depositing ITO and IZO thin films on the vertically aligned SiNW arrays. The structural and electrical properties of the resulting ITO/IZO/SiNW heterojunction diode were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and current-voltage (I-V) measurements. Nonlinear and rectifying I-V properties confirmed that a heterojunction diode was successfully formed in the ITO/IZO/SiNW structure. The diode had a well-defined rectifying behavior, with a rectification ratio of 550.7 at 3 V and a turn-on voltage of 2.53 V under dark conditions.

Semi-analytical model of cross-borehole flow experiments for fractured medium characterization

NASA Astrophysics Data System (ADS)

Roubinet, D.; Irving, J.; Day-Lewis, F. D.

2014-12-01

The study of fractured rocks is extremely important in a wide variety of research fields where the fractures and faults can represent either rapid access to some resource of interest or potential pathways for the migration of contaminants in the subsurface. Identification of their presence and determination of their properties are critical and challenging tasks that have led to numerous fracture characterization methods. Among these methods, cross-borehole flowmeter analysis aims to evaluate fracture connections and hydraulic properties from vertical-flow-velocity measurements conducted in one or more observation boreholes under forced hydraulic conditions. Previous studies have demonstrated that analysis of these data can provide important information on fracture connectivity, transmissivity, and storativity. Estimating these properties requires the development of analytical and/or numerical modeling tools that are well adapted to the complexity of the problem. Quantitative analysis of cross-borehole flowmeter experiments, in particular, requires modeling formulations that: (i) can be adapted to a variety of fracture and experimental configurations; (ii) can take into account interactions between the boreholes because their radii of influence may overlap; and (iii) can be readily cast into an inversion framework that allows for not only the estimation of fracture hydraulic properties, but also an assessment of estimation error. To this end, we present a new semi-analytical formulation for cross-borehole flow in fractured media that links transient vertical-flow velocities measured in one or a series of observation wells during hydraulic forcing to the transmissivity and storativity of the fractures intersected by these wells. Our model addresses the above needs and provides a flexible and computationally efficient semi-analytical framework having strong potential for future adaptation to more complex configurations. The proposed modeling approach is demonstrated in the context of sensitivity analysis for a relatively simple two-fracture synthetic problem, as well as in the context of field-data analysis for fracture connectivity and estimation of corresponding hydraulic properties.

Cervical spine injuries, mechanisms, stability and AIS scores from vertical loading applied to military environments.

PubMed

Yoganandan, Narayan; Pintar, Frank A; Humm, John R; Maiman, Dennis J; Voo, Liming; Merkle, Andrew

2016-07-01

The purpose of this study was to determine injuries to osteo-ligamentous structures of cervical column, mechanisms, forces, severities and AIS scores from vertical accelerative loading. Seven human cadaver head-neck complexes (56.9 ± 9.5 years) were aligned based on seated the posture of military soldiers. Army combat helmets were used. Specimens were attached to a vertical accelerator to apply caudo-cephalad g-forces. They were accelerated with increasing insults. Intermittent palpation and radiography were done. A roof structure mimicking military vehicle interior was introduced after a series of tests and experiments were conducted following similar protocols. Upon injury detection, CT and dissection were done. Temporal force responses were extracted, peak forces and times of occurrence were obtained, injury severities were graded, and spine stability was determined. Injuries occurred in tests only when the roof structure was included. Responses were tri-phasic: initial thrust, secondary tensile, tertiary roof contact phases. Peak forces: 1364-4382 N, initial thrust, 165-169 N, secondary tensile, 868-3368 N tertiary helmet-head roof contact phases. Times of attainments: 5.3-9.6, 31.7-42.6, 55.0-70.8 ms. Injuries included fractures and joint disruptions. Multiple injuries occurred in all but one specimen. A majority of injury severities were AIS = 2. Spines were considered unstable in a majority of cases. Spine response was tri-phasic. Injuries occurred in roof contact tests with the helmeted head-neck specimen. Multiplicity and unstable nature of AIS = 2 level injuries, albeit at lower severities, might predispose the spine to long-term accelerated degenerative changes. Clinical protocols should include a careful evaluation of sub-catastrophic injuries in military patients.

Fiber optics welder having movable aligning mirror

DOEpatents

Higgins, Robert W.; Robichaud, Roger E.

1981-01-01

A system for welding fiber optic waveguides together. The ends of the two fibers to be joined together are accurately, collinearly aligned in a vertical orientation and subjected to a controlled, diffuse arc to effect welding and thermal conditioning. A front-surfaced mirror mounted at a 45.degree. angle to the optical axis of a stereomicroscope mounted for viewing the junction of the ends provides two orthogonal views of the interface during the alignment operation.

A Computer Program for Flow-Log Analysis of Single Holes (FLASH)

USGS Publications Warehouse

Day-Lewis, F. D.; Johnson, C.D.; Paillet, Frederick L.; Halford, K.J.

2011-01-01

A new computer program, FLASH (Flow-Log Analysis of Single Holes), is presented for the analysis of borehole vertical flow logs. The code is based on an analytical solution for steady-state multilayer radial flow to a borehole. The code includes options for (1) discrete fractures and (2) multilayer aquifers. Given vertical flow profiles collected under both ambient and stressed (pumping or injection) conditions, the user can estimate fracture (or layer) transmissivities and far-field hydraulic heads. FLASH is coded in Microsoft Excel with Visual Basic for Applications routines. The code supports manual and automated model calibration. ?? 2011, The Author(s). Ground Water ?? 2011, National Ground Water Association.

Analysis of accuracy in photogrammetric roughness measurements

NASA Astrophysics Data System (ADS)

Olkowicz, Marcin; Dąbrowski, Marcin; Pluymakers, Anne

2017-04-01

Regarding permeability, one of the most important features of shale gas reservoirs is the effective aperture of cracks opened during hydraulic fracturing, both propped and unpropped. In a propped fracture, the aperture is controlled mostly by proppant size and its embedment, and fracture surface roughness only has a minor influence. In contrast, in an unpropped fracture aperture is controlled by the fracture roughness and the wall displacement. To measure fracture surface roughness, we have used the photogrammetric method since it is time- and cost-efficient. To estimate the accuracy of this method we compare the photogrammetric measurements with reference measurements taken with a White Light Interferometer (WLI). Our photogrammetric setup is based on high resolution 50 Mpx camera combined with a focus stacking technique. The first step for photogrammetric measurements is to determine the optimal camera positions and lighting. We compare multiple scans of one sample, taken with different settings of lighting and camera positions, with the reference WLI measurement. The second step is to perform measurements of all studied fractures with the parameters that produced the best results in the first step. To compare photogrammetric and WLI measurements we regrid both data sets onto a regular 10 μm grid and determined the best fit, followed by a calculation of the difference between the measurements. The first results of the comparison show that for 90 % of measured points the absolute vertical distance between WLI and photogrammetry is less than 10 μm, while the mean absolute vertical distance is 5 μm. This proves that our setup can be used for fracture roughness measurements in shales.

Microstructure anisotropy and its effect on mechanical properties of reduced activation ferritic/martensitic steel fabricated by selective laser melting

NASA Astrophysics Data System (ADS)

Huang, Bo; Zhai, Yutao; Liu, Shaojun; Mao, Xiaodong

2018-03-01

Selective laser melting (SLM) is a promising way for the fabrication of complex reduced activation ferritic/martensitic steel components. The microstructure of the SLM built China low activation martensitic (CLAM) steel plates was observed and analyzed. The hardness, Charpy impact and tensile testing of the specimens in different orientations were performed at room temperature. The results showed that the difference in the mechanical properties was related to the anisotropy in microstructure. The planer unmelted porosity in the interface of the adjacent layers induced opening/tensile mode when the tensile samples parallel to the build direction were tested whereas the samples vertical to the build direction fractured in the shear mode with the grains being sheared in a slant angle. Moreover, the impact absorbed energy (IAE) of all impact specimens was significantly lower than that of the wrought CLAM steel, and the IAE of the samples vertical to the build direction was higher than that of the samples parallel to the build direction. The impact fracture surfaces revealed that the load parallel to the build layers caused laminated tearing among the layers, and the load vertical to the layers induced intergranular fracture across the layers.

Evaluation of borehole geophysical logs at the Sharon Steel Farrell Works Superfund site, Mercer County, Pennsylvania

USGS Publications Warehouse

McAuley, Steven D.

2004-01-01

On April 14?15, 2003, geophysical logging was conducted in five open-borehole wells in and adjacent to the Sharon Steel Farrell Works Superfund Site, Mercer County, Pa. Geophysical-logging tools used included caliper, natural gamma, single-point resistance, fluid temperature, and heatpulse flowmeter. The logs were used to determine casing depth, locate subsurface fractures, identify water-bearing fractures, and identify and measure direction and rate of vertical flow within the borehole. The results of the geophysical logging were used to determine the placement of borehole screens, which allows monitoring of water levels and sampling of water-bearing zones so that the U.S. Environmental Protection Agency can conduct an investigation of contaminant movement in the fractured bedrock. Water-bearing zones were identified in three of five boreholes at depths ranging from 46 to 119 feet below land surface. Borehole MR-3310 (MW03D) showed upward vertical flow from 71 to 74 feet below land surface to a receiving zone at 63-68 feet below land surface, permitting potential movement of ground water, and possibly contaminants, from deep to shallow zones. No vertical flow was measured in the other four boreholes.

Fault and joint geometry at Raft River Geothermal Area, Idaho

NASA Astrophysics Data System (ADS)

Guth, L. R.; Bruhn, R. L.; Beck, S. L.

1981-07-01

Raft River geothermal reservoir is formed by fractures in sedimentary strata of the Miocene and Pliocene salt lake formation. The fracturing is most intense at the base of the salt lake formation, along a decollement that dips eastward at less than 50 on top of metamorphosed precambrian and lower paleozoic rocks. Core taken from less than 200 m above the decollement contains two sets of normal faults. The major set of faults dips between 500 and 700. These faults occur as conjugate pairs that are bisected by vertical extension fractures. The second set of faults dips 100 to 200 and may parallel part of the basal decollement or reflect the presence of listric normal faults in the upper plate. Surface joints form two suborthogonal sets that dip vertically. East-northeast-striking joints are most frequent on the limbs of the Jim Sage anticline, a large fold that is associated with the geothermal field.

Results of the multiwell experiment in situ stresses, natural fractures, and other geological controls on reservoirs

NASA Astrophysics Data System (ADS)

Lorenz, John C.; Warpinski, Norman R.; Teufel, Lawrence W.; Branagan, Paul T.; Sattler, Allan R.; Northrop, David A.

Hundreds of millions of cubic meters of natural gas are locked up in low-permeability, natural gas reservoirs. The Multiwell Experiment (MWX) was designed to characterize such reservoirs, typical of much of the western United States, and to assess and develop a technology for the production of this unconventional resource. Flow-rate tests of the MWX reservoirs indicate a system permeability that is several orders of magnitude higher than laboratory permeability measurements made on matrix-rock sandstones. This enhanced permeability is caused by natural fractures. The single set of fractures present in the reservoirs provides a significant permeability anisotropy that is aligned with the maximum in situ horizontal stress. Hydraulic fractures therefore form parallel to the natural fractures and are consequently an inefficient mechanism for stimulation. Successful stimulation may be possible by perturbing the local stress field with a large hydraulic fracture in one well so that a second hydraulic fracture in an offset well propagates transverse to the natural fracture permeability trend.

Phase structure within a fracture network beneath a surface pond: Field experiment

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

GLASS JR.,ROBERT J.; NICHOLL,M.J.

2000-05-09

The authors performed a simple experiment to elucidate phase structure within a pervasively fractured welded tuff. Dyed water was infiltrated from a surface pond over a 36 minute period while a geophysical array monitored the wetted region within vertical planes directly beneath. They then excavated the rock mass to a depth of {approximately}5 m and mapped the fracture network and extent of dye staining in a series of horizontal pavements. Near the pond the network was fully stained. Below, the phase structure immediately expanded and with depth, the structure became fragmented and complicated exhibiting evidence of preferential flow, fingers, irregularmore » wetting patterns, and varied behavior at fracture intersections. Limited transient geophysical data suggested that strong vertical pathways form first followed by increased horizontal expansion and connection within the network. These rapid pathways are also the first to drain. Estimates also suggest that the excavation captured from {approximately}10% to 1% or less of the volume of rock interrogated by the infiltration slug and thus the penetration depth could have been quite large.« less

Trauma of the upper cervical spine: focus on vertical atlantoaxial dislocation.

PubMed

Pissonnier, M L; Lazennec, J Y; Renoux, J; Rousseau, M A

2013-10-01

Traumatic ligament injuries of the craniovertebral junction, either isolated or associated with bone avulsion or fracture, often lead to death. These injuries are rare and underrated but are increasingly seen in emergency departments due to the improvement in initial on-scene management of accidents. Vertical atlantoaxial dislocation (AAD) is a specific lesion that was barely reported. Based on our experience, our goal was to systematically investigate the prevalence and prognosis of traumatic vertical AAD and discuss its management. All cervical CT scans performed at our institution between 2006 and 2010 for cervical trauma in adults were retrospectively reviewed. Based on the measurement of lateral mass index (LMI), defined as the gap between C1 and C2 articular facets, we identified three cases of traumatic vertical AAD in 300 CT scans. Their medical records were investigated. The incidence of vertical AAD was 1% in the exposed population. One case was an isolated vertical AAD and two were associated with a type II odontoid fracture. We report the first case in the literature of unilateral vertical AAD. Two patients died rapidly; the survivor was treated with occipitocervical fixation. Specific maneuvers were used for immobilization and reduction. This study found a not insignificant incidence of vertical AAD and a high lethality rate. LMI appears to be a relevant radiological criterion for this diagnosis, for which traction is contraindicated. Associated neurological or vascular damage should be suspected and investigated. In our experience, spinal surgical fixation is required because of major instability.

Nanostructuring on zinc phthalocyanine thin films for single-junction organic solar cells

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

Chaudhary, Dhirendra K.; Kumar, Lokendra, E-mail: lokendrakr@allduniv.ac.in

2016-05-23

Vertically aligned and random oriented crystalline molecular nanorods of organic semiconducting Zinc Phthalocyanine (ZnPc) have been grown on ITO coated glass substrate using solvent volatilization method. Interesting changes in surface morphology were observed under different solvent treatment. Vertically aligned nanorods of ZnPc thin film were observed in the films treated with acetone, where as the random oriented nanorods were observed in the films treated with chloroform. The X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) have been used for characterization of nanostructures. The optical properties of the nanorods have been investigated by UV-Vis. absorption spectroscopy.

Polarization-dependent DANES study on vertically-aligned ZnO nanorods

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

Sun, Chengjun; Park, Chang-In; Jin, Zhenlan

2016-05-01

The local structural and local density of states of vertically-aligned ZnO nanorods were examined by using a polarization-dependent diffraction anomalous near edge structure (DANES) measurements from c-oriented ZnO nanorods at the Zn K edge with the incident x-ray electric field parallel and perpendicular to the x-ray momentum transfer direction. Orientation-dependent local structures determined by DANES were comparable with polarization-dependent EXAFS results. Unlike other techniques, polarization-dependent DANES can uniquely describe the orientation-dependent local structural properties and the local density of states of a selected element in selected-phased crystals of compounds or mixed-phased structures.

Growth of vertically aligned single-walled carbon nanotubes with metallic chirality through faceted FePt-Au catalysts

NASA Astrophysics Data System (ADS)

Ohashi, Toshiyuki; Iwama, Hiroki; Shima, Toshiyuki

2016-02-01

Direct synthesis of vertically aligned metallic single-walled carbon nanotubes (m-SWCNT forests) is a difficult challenge. We have successfully synthesized m-SWCNT forests using faceted iron platinum-gold catalysts epitaxially grown on a single crystalline magnesium oxide substrate. The metallic content of the forests estimated by Raman spectroscopy reaches 90%. From the standpoint of growth rate of the forests, the growth mechanism is probably based on the catalyst of solid state. It is suggested that preferential growth of m-SWCNTs is achieved when both factors are satisfied, namely, {111} dominant octahedral facet and ideal size (fine particles) of FePt particles.

Biomineralization of superhydrophilic vertically aligned carbon nanotubes.

PubMed

Marsi, Teresa Cristina O; Santos, Tiago G; Pacheco-Soares, Cristina; Corat, Evaldo J; Marciano, Fernanda R; Lobo, Anderson O

2012-03-06

Vertically aligned carbon nanotubes (VACNT) promise a great role for the study of tissue regeneration. In this paper, we introduce a new biomimetic mineralization routine employing superhydrophilic VACNT films as highly stable template materials. The biomineralization was obtained after VACNT soaking in simulated body fluid solution. Detailed structural analysis reveals that the polycrystalline biological apatites formed due to the -COOH terminations attached to VACNT tips after oxygen plasma etching. Our approach not only provides a novel route for nanostructured materials, but also suggests that COOH termination sites can play a significant role in biomimetic mineralization. These new nanocomposites are very promising as nanobiomaterials due to the excellent human osteoblast adhesion.

The effect of different temperature profiles upon the length and crystallinity of vertically-aligned multi-walled carbon nanotubes.

PubMed

Yun, Jongju; Lee, Cheesung; Zheng, Qing; Baik, Seunghyun

2012-08-01

We synthesized vertically-aligned multi-walled carbon nanotubes with an inner diameter of 1.6-7.5 nm and stack height of 80-28600 microm by chemical vapor deposition. The effects of synthesis conditions such as substrate position in the tube furnace, maximum temperature, temperature increasing rate and synthesis duration on the structure of nanotubes were investigated. It was found that slightly faster temperature increase rate resulted in significantly longer length, larger diameter and more defects of nanotubes. Structural parameters such as inner, outer diameters, wall thickness and defects were investigated using transmission electron microscopy and Raman spectroscopy.

Patterned forests of vertically-aligned multiwalled carbon nanotubes using metal salt catalyst solutions.

PubMed

Garrett, David J; Flavel, Benjamin S; Baronian, Keith H R; Downard, Alison J

2013-01-01

A simple method for producing patterned forests of multiwalled carbon nanotubes (MWCNTs) is described. An aqueous metal salt solution is spin-coated onto a substrate patterned with photoresist by standard methods. The photoresist is removed by acetone washing leaving the acetone-insoluble catalyst pattern on the substrate. Dense forests of vertically aligned (VA) MWCNTs are grown on the patterned catalyst layers by chemical vapour deposition. The procedures have been demonstrated by growing MWCNT forests on two substrates: silicon and conducting graphitic carbon films. The forests adhere strongly to the substrates and when grown directly on carbon film, offer a simple method of preparing MWCNT electrodes.

Growth of multiwalled-carbon nanotubes using vertically aligned carbon nanofibers as templates/scaffolds and improved field-emission properties

NASA Astrophysics Data System (ADS)

Cui, H.; Yang, X.; Baylor, L. R.; Lowndes, D. H.

2005-01-01

Multiwalled-carbon nanotubes (MWCNTs) are grown on top of vertically aligned carbon nanofibers (VACNFs) via microwave plasma-enhanced chemical vapor deposition (MPECVD). The VACNFs are first grown in a direct-current plasma-enhanced chemical vapor deposition reactor using nickel catalyst. A layer of carbon-silicon materials is then deposited on the VACNFs and the nickel catalyst particle is broken down into smaller nanoparticles during an intermediate reactive-ion-plasma deposition step. These nickel nanoparticles nucleate and grow MWCNTs in the following MPECVD process. Movable-probe measurements show that the MWCNTs have greatly improved field-emission properties relative to the VACNFs.

Microplasma illumination enhancement of vertically aligned conducting ultrananocrystalline diamond nanorods

PubMed Central

2012-01-01

Vertically aligned conducting ultrananocrystalline diamond (UNCD) nanorods are fabricated using the reactive ion etching method incorporated with nanodiamond particles as mask. High electrical conductivity of 275 Ω·cm−1 is obtained for UNCD nanorods. The microplasma cavities using UNCD nanorods as cathode show enhanced plasma illumination characteristics of low threshold field of 0.21 V/μm with plasma current density of 7.06 mA/cm2 at an applied field of 0.35 V/μm. Such superior electrical properties of UNCD nanorods with high aspect ratio potentially make a significant impact on the diamond-based microplasma display technology. PMID:23009733

Vertically aligned diamond-graphite hybrid nanorod arrays with superior field electron emission properties

NASA Astrophysics Data System (ADS)

Ramaneti, R.; Sankaran, K. J.; Korneychuk, S.; Yeh, C. J.; Degutis, G.; Leou, K. C.; Verbeeck, J.; Van Bael, M. K.; Lin, I. N.; Haenen, K.

2017-06-01

A "patterned-seeding technique" in combination with a "nanodiamond masked reactive ion etching process" is demonstrated for fabricating vertically aligned diamond-graphite hybrid (DGH) nanorod arrays. The DGH nanorod arrays possess superior field electron emission (FEE) behavior with a low turn-on field, long lifetime stability, and large field enhancement factor. Such an enhanced FEE is attributed to the nanocomposite nature of the DGH nanorods, which contain sp2-graphitic phases in the boundaries of nano-sized diamond grains. The simplicity in the nanorod fabrication process renders the DGH nanorods of greater potential for the applications as cathodes in field emission displays and microplasma display devices.

Vertically-aligned Co(OH)2 Nanosheet Films for Flexible All-solid-state Electrochemical Supercapacitor

NASA Astrophysics Data System (ADS)

Tian, Yazhou; Gong, Jiangfeng; Zhu, Weihua

2017-11-01

Vertically-aligned Co(OH)2 nanosheets were cathodically electrodeposited on a piece of gold coated polyethylene terephthalate (Au-PET) as an electrode material for supercapacitor. The Co(OH)2 electrode showed a high capacitance of 2695 F g-1 at 8 A g-1 in 1 M KOH aqueous electrolyte. Besides, the films were employed to assemble symmetric all-solid-state supercapacitors with PVA/LiCl gel served as solid electrolyte. The device exhibits an areal capacitance of 50.5 μF cm-2 at the current density of 2 μA cm-2 accompanied by excellent cycle stability.

Vertically aligned carbon nanofiber as nano-neuron interface for monitoring neural function.

PubMed

Yu, Zhe; McKnight, Timothy E; Ericson, M Nance; Melechko, Anatoli V; Simpson, Michael L; Morrison, Barclay

2012-05-01

Neural chips, which are capable of simultaneous multisite neural recording and stimulation, have been used to detect and modulate neural activity for almost thirty years. As neural interfaces, neural chips provide dynamic functional information for neural decoding and neural control. By improving sensitivity and spatial resolution, nano-scale electrodes may revolutionize neural detection and modulation at cellular and molecular levels as nano-neuron interfaces. We developed a carbon-nanofiber neural chip with lithographically defined arrays of vertically aligned carbon nanofiber electrodes and demonstrated its capability of both stimulating and monitoring electrophysiological signals from brain tissues in vitro and monitoring dynamic information of neuroplasticity. This novel nano-neuron interface may potentially serve as a precise, informative, biocompatible, and dual-mode neural interface for monitoring of both neuroelectrical and neurochemical activity at the single-cell level and even inside the cell. The authors demonstrate the utility of a neural chip with lithographically defined arrays of vertically aligned carbon nanofiber electrodes. The new device can be used to stimulate and/or monitor signals from brain tissue in vitro and for monitoring dynamic information of neuroplasticity both intracellularly and at the single cell level including neuroelectrical and neurochemical activities. Copyright © 2012 Elsevier Inc. All rights reserved.

WC Nanocrystals Grown on Vertically Aligned Carbon Nanotubes: An Efficient and Stable Electrocatalyst for Hydrogen Evolution Reaction.

PubMed

Fan, Xiujun; Zhou, Haiqing; Guo, Xia

2015-05-26

Single nanocrystalline tungsten carbide (WC) was first synthesized on the tips of vertically aligned carbon nanotubes (VA-CNTs) with a hot filament chemical vapor deposition (HF-CVD) method through the directly reaction of tungsten metal with carbon source. The VA-CNTs with preservation of vertical structure integrity and alignment play an important role to support the nanocrystalline WC growth. With the high crystallinity, small size, and uniform distribution of WC particles on the carbon support, the formed WC-CNTs material exhibited an excellent catalytic activity for hydrogen evolution reaction (HER), giving a η10 (the overpotential for driving a current of 10 mA cm(-2)) of 145 mV, onset potential of 15 mV, exchange current density@ 300 mV of 117.6 mV and Tafel slope values of 72 mV dec(-1) in acid solution, and η10 of 137 mV, onset potential of 16 mV, exchange current density@ 300 mV of 33.1 mV and Tafel slope values of 106 mV dec(-1) in alkaline media, respectively. Electrochemical stability test further confirms the long-term operation of the catalyst in both acidic and alkaline media.

Functionalized vertically aligned ZnO nanorods for application in electrolyte-insulator-semiconductor based pH sensors and label-free immuno-sensors

NASA Astrophysics Data System (ADS)

Kumar, Narendra; Senapati, Sujata; Kumar, Satyendra; Kumar, Jitendra; Panda, Siddhartha

2016-04-01

Vertically aligned ZnO nanorods were grown on a SiO2/Si surface by optimization of the temperature and atmosphere for annealing of the seed. The seed layer annealed at 500 °C in vacuum provided well separated and uniform seeds which also provided the best condition to get densely packed, uniformly distributed, and vertically aligned nanorods. These nanorods grown on the substrates were used to fabricate electrolyte-insulator-semiconductor (EIS) devices for pH sensing. Etching of ZnO at acidic pH prevents the direct use of nanorods for pH sensing. Therefore, the nanorods functionalised with 3-aminopropyltriethoxysilane (APTES) were utilized for pH sensing and showed the pH sensitivity of 50.1 mV/pH. APTES is also known to be used as a linker to immobilize biomolecules (such as antibodies). The EIS device with APTES functionalized nanorods was used for the label free detection of prostate-specific antigen (PSA). Finally, voltage shifts of 23 mV and 35 mV were observed with PSA concentrations of 1 ng/ml and 100 ng/ml, respectively.

Vertically-aligned BCN Nanotube Arrays with Superior Performance in Electrochemical capacitors

PubMed Central

Zhou, Junshuang; Li, Na; Gao, Faming; Zhao, Yufeng; Hou, Li; Xu, Ziming

2014-01-01

Electrochemical capacitors (EC) have received tremendous interest due to their high potential to satisfy the urgent demand in many advanced applications. The development of new electrode materials is considered to be the most promising approach to enhance the EC performance substantially. Herein, we present a high-capacity capacitor material based on vertically-aligned BC2N nanotube arrays (VA-BC2NNTAs) synthesized by low temperature solvothermal route. The obtained VA-BC2NNTAs display the good aligned nonbuckled tubular structure, which could indeed advantageously enhance capacitor performance. VA-BC2NNTAs exhibit an extremely high specific capacitance, 547 Fg−1, which is about 2–6 times larger than that of the presently available carbon-based materials. Meanwhile, VA-BC2NNTAs maintain an excellent rate capability and high durability. All these characteristics endow VA-BC2NNTAs an alternative promising candidate for an efficient electrode material for electrochemical capacitors (EC). PMID:25124300

High-performance supercapacitors based on vertically aligned carbon nanotubes and nonaqueous electrolytes

NASA Astrophysics Data System (ADS)

Kim, Byungwoo; Chung, Haegeun; Kim, Woong

2012-04-01

We demonstrate the high performance of supercapacitors fabricated with vertically aligned carbon nanotubes and nonaqueous electrolytes such as ionic liquids and conventional organic electrolytes. Specific capacitance, maximum power and energy density of the supercapacitor measured in ionic liquid were ˜75 F g-1, ˜987 kW kg-1 and ˜27 W h kg-1, respectively. The high power performance was consistently indicated by a fast relaxation time constant of 0.2 s. In addition, electrochemical oxidation of the carbon nanotubes improved the specific capacitance (˜158 F g-1) and energy density (˜53 W h kg-1). Both high power and energy density could be attributed to the fast ion transport realized by the alignment of carbon nanotubes and the wide operational voltage defined by the ionic liquid. The demonstrated carbon-nanotube- and nonaqueous-electrolyte-based supercapacitors show great potential for the development of high-performance energy storage devices.

Effect of Enhanced Thermal Stability of Alumina Support Layer on Growth of Vertically Aligned Single-Walled Carbon Nanotubes and Their Application in Nanofiltration Membranes.

PubMed

In, Jung Bin; Cho, Kang Rae; Tran, Tung Xuan; Kim, Seok-Min; Wang, Yinmin; Grigoropoulos, Costas P; Noy, Aleksandr; Fornasiero, Francesco

2018-06-07

We investigate the thermal stability of alumina supporting layers sputtered at different conditions and its effect on the growth of aligned single-walled carbon nanotube arrays. Radio frequency magnetron sputtering of alumina under oxygen-argon atmosphere produces a Si-rich alumina alloy film on a silicon substrate. Atomic force microscopy on the annealed catalysts reveals that Si-rich alumina films are more stable than alumina layers with low Si content at the elevated temperatures at which the growth of single-walled carbon nanotubes is initiated. The enhanced thermal stability of the Si-rich alumina layer results in a narrower (< 2.2 nm) diameter distribution of the single-walled carbon nanotubes. Thanks to the smaller diameters of their nanotube pores, membranes fabricated with vertically aligned nanotubes grown on the stable layers display improved ion selectivity.

Transferring vertically aligned carbon nanotubes onto a polymeric substrate using a hot embossing technique for microfluidic applications.

PubMed

Mathur, A; Roy, S S; McLaughlin, J A

2010-07-06

We explored the hot embossing method for transferring vertically aligned carbon nanotubes (CNTs) into microfluidic channels, fabricated on poly-methyl-methacrylate (PMMA). Patterned and unpatterned CNTs were synthesized by microwave plasma-enhanced chemical vapour deposition on silicon to work as a stamp. For hot embossing, 115 degrees C and 1 kN force for 2 min were found to be the most suitable parameters for the complete transfer of aligned CNTs on the PMMA microchannel. Raman and SEM studies were used to analyse the microstructure of CNTs before and after hot embossing. The PMMA microparticles with dimensions (approx. 10 microm in diameter) similar to red blood cells were successfully filtered using laminar flow through these microfluidic channels. Finally, a microfluidic-based point-of-care device for blood filtration and detection of bio-molecules is drawn schematically.

Transferring vertically aligned carbon nanotubes onto a polymeric substrate using a hot embossing technique for microfluidic applications

PubMed Central

Mathur, A.; Roy, S. S.; McLaughlin, J. A.

2010-01-01

We explored the hot embossing method for transferring vertically aligned carbon nanotubes (CNTs) into microfluidic channels, fabricated on poly-methyl-methacrylate (PMMA). Patterned and unpatterned CNTs were synthesized by microwave plasma-enhanced chemical vapour deposition on silicon to work as a stamp. For hot embossing, 115°C and 1 kN force for 2 min were found to be the most suitable parameters for the complete transfer of aligned CNTs on the PMMA microchannel. Raman and SEM studies were used to analyse the microstructure of CNTs before and after hot embossing. The PMMA microparticles with dimensions (approx. 10 µm in diameter) similar to red blood cells were successfully filtered using laminar flow through these microfluidic channels. Finally, a microfluidic-based point-of-care device for blood filtration and detection of bio-molecules is drawn schematically. PMID:20147316

Effect of Enhanced Thermal Stability of Alumina Support Layer on Growth of Vertically Aligned Single-Walled Carbon Nanotubes and Their Application in Nanofiltration Membranes

NASA Astrophysics Data System (ADS)

In, Jung Bin; Cho, Kang Rae; Tran, Tung Xuan; Kim, Seok-Min; Wang, Yinmin; Grigoropoulos, Costas P.; Noy, Aleksandr; Fornasiero, Francesco

2018-06-01

We investigate the thermal stability of alumina supporting layers sputtered at different conditions and its effect on the growth of aligned single-walled carbon nanotube arrays. Radio frequency magnetron sputtering of alumina under oxygen-argon atmosphere produces a Si-rich alumina alloy film on a silicon substrate. Atomic force microscopy on the annealed catalysts reveals that Si-rich alumina films are more stable than alumina layers with low Si content at the elevated temperatures at which the growth of single-walled carbon nanotubes is initiated. The enhanced thermal stability of the Si-rich alumina layer results in a narrower (< 2.2 nm) diameter distribution of the single-walled carbon nanotubes. Thanks to the smaller diameters of their nanotube pores, membranes fabricated with vertically aligned nanotubes grown on the stable layers display improved ion selectivity.

High-performance supercapacitors based on vertically aligned carbon nanotubes and nonaqueous electrolytes.

PubMed

Kim, Byungwoo; Chung, Haegeun; Kim, Woong

2012-04-20

We demonstrate the high performance of supercapacitors fabricated with vertically aligned carbon nanotubes and nonaqueous electrolytes such as ionic liquids and conventional organic electrolytes. Specific capacitance, maximum power and energy density of the supercapacitor measured in ionic liquid were ~75 F g(-1), ~987 kW kg(-1) and ~27 W h kg(-1), respectively. The high power performance was consistently indicated by a fast relaxation time constant of 0.2 s. In addition, electrochemical oxidation of the carbon nanotubes improved the specific capacitance (~158 F g(-1)) and energy density (~53 W h kg(-1)). Both high power and energy density could be attributed to the fast ion transport realized by the alignment of carbon nanotubes and the wide operational voltage defined by the ionic liquid. The demonstrated carbon-nanotube- and nonaqueous-electrolyte-based supercapacitors show great potential for the development of high-performance energy storage devices. © 2012 IOP Publishing Ltd

Dense Vertically Aligned Copper Nanowire Composites as High Performance Thermal Interface Materials.

PubMed

Barako, Michael T; Isaacson, Scott G; Lian, Feifei; Pop, Eric; Dauskardt, Reinhold H; Goodson, Kenneth E; Tice, Jesse

2017-12-06

Thermal interface materials (TIMs) are essential for managing heat in modern electronics, and nanocomposite TIMs can offer critical improvements. Here, we demonstrate thermally conductive, mechanically compliant TIMs based on dense, vertically aligned copper nanowires (CuNWs) embedded into polymer matrices. We evaluate the thermal and mechanical characteristics of 20-25% dense CuNW arrays with and without polydimethylsiloxane infiltration. The thermal resistance achieved is below 5 mm 2 K W -1 , over an order of magnitude lower than commercial heat sink compounds. Nanoindentation reveals that the nonlinear deformation mechanics of this TIM are influenced by both the CuNW morphology and the polymer matrix. We also implement a flip-chip bonding protocol to directly attach CuNW composites to copper surfaces, as required in many thermal architectures. Thus, we demonstrate a rational design strategy for nanocomposite TIMs that simultaneously retain the high thermal conductivity of aligned CuNWs and the mechanical compliance of a polymer.

Transfer of vertically aligned carbon nanofibers to polydimethylsiloxane (PDMS) while maintaining their alignment and impalefection functionality.

PubMed

Pearce, Ryan C; Railsback, Justin G; Anderson, Bryan D; Sarac, Mehmet F; McKnight, Timothy E; Tracy, Joseph B; Melechko, Anatoli V

2013-02-01

Vertically aligned carbon nanofibers (VACNFs) are synthesized on Al 3003 alloy substrates by direct current plasma-enhanced chemical vapor deposition. Chemically synthesized Ni nanoparticles were used as the catalyst for growth. The Si-containing coating (SiN(x)) typically created when VACNFs are grown on silicon was produced by adding Si microparticles prior to growth. The fiber arrays were transferred to PDMS by spin coating a layer on the grown substrates, curing the PDMS, and etching away the Al in KOH. The fiber arrays contain many fibers over 15 μm (long enough to protrude from the PDMS film and penetrate cell membranes) and SiN(x) coatings as observed by SEM, EDX, and fluorescence microscopy. The free-standing array in PDMS was loaded with pVENUS-C1 plasmid and human brain microcapillary endothelial (HBMEC) cells and was successfully impalefected.

Carbon nanotubes synthesized by Ni-assisted atmospheric pressure thermal chemical vapor deposition

NASA Astrophysics Data System (ADS)

Choi, G. S.; Cho, Y. S.; Hong, S. Y.; Park, J. B.; Son, K. H.; Kim, D. J.

2002-03-01

A detailed systematic study on the growth morphology of carbon nanotubes (CNTs) on Si in atmospheric pressure thermal chemical vapor deposition was undertaken. The role of NH3 for vertical alignment of CNTs was investigated. The direct cause for the alignment was a dense distribution of the catalytic metal particles, but that the particles are maintained catalytically active under amorphous carbon deposits was established by NH3. It allows a dense nucleation of the CNTs, and consequently, assists vertical alignment through entanglement and mechanical leaning among the tubes. The CNTs grew in a base growth mode. Since Ni is consumed both by silicide reaction and by capture into the growing tube, the growth stops when Ni is totally depleted. It occurs earlier for smaller particles, and thus a long time of growth results in a thin bottom with poor adhesion.

Zoom Reconstruction Tool: Evaluation of Image Quality and Influence on the Diagnosis of Root Fracture.

PubMed

Queiroz, Polyane Mazucatto; Santaella, Gustavo Machado; Capelozza, Ana Lúcia Alvares; Rosalen, Pedro Luiz; Freitas, Deborah Queiroz; Haiter-Neto, Francisco

2018-04-01

This study evaluated the image quality and the diagnosis of root fractures when using the Zoom Reconstruction tool (J Morita, Kyoto, Japan). A utility wax phantom with a metal sample inside was used for objective evaluation, and a mandible with 27 single-rooted teeth (with and without obturation and with and without vertical or horizontal fractures) was used for diagnostic evaluation. The images were acquired in 3 protocols: protocol 1, field of view (FOV) of 4 × 4 cm and a voxel size of 0.08 mm; protocol 2, FOV of 10 × 10 cm and a voxel size of 0.2 mm; and protocol 3, Zoom Reconstruction of images from protocol 2 (FOV of 4 × 4 cm and a voxel size of 0.08 mm). The objective evaluation was achieved by measuring the image noise, and the diagnosis of fractures was performed by 3 evaluators. The area under the receiver operating characteristic curve was used to calculate accuracy, and analysis of variance compared the accuracy and image quality of the protocols. Regarding quality, protocol 1 was superior to protocol 2 (P < .0001) and Zoom Reconstruction (P < .0001). Additionally, images of protocol 2 presented less noise than the Zoom Reconstruction image (P < .0001); however, for diagnosis, Zoom Reconstruction was superior in relation to protocol 2 (P = .011) and did not differ from protocol 1 (P = .228) for the diagnosis of a vertical root fracture in filled teeth. The Zoom Reconstruction tool allows better accuracy for vertical root fracture detection in filled teeth, making it possible to obtain a higher-resolution image from a lower-resolution examination without having to expose the patient to more radiation. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Long-bone fractures in llamas and alpacas: 28 cases (1998–2008)

PubMed Central

Knafo, S. Emmanuelle; Getman, Liberty M.; Richardson, Dean W.; Fecteau, Marie-Eve

2012-01-01

Treatment and outcome of camelids with long-bone fractures are described. Medical records (1998–2008) of camelids (n = 28) with long-bone fractures were reviewed for signalment, time to presentation, fracture type, method of repair, duration of hospitalization, and post-operative complications. Follow-up information was obtained via telephone interviews with owners. Mean age and weight at presentation were 3.4 years and 56.3 kg, respectively. Twenty-six fractures were treated with internal fixation (n = 11), external fixation (n = 10), combination of internal and external fixation (n = 3), amputation (n = 1), and external fixation followed by amputation (n = 1). Long-term follow-up information was obtained for 19 of the 26 animals. The post-operative complication rate was 23% and owner satisfaction was high. Animals with open fractures were more likely to experience complications. Internal fixation was associated with superior alignment and outcome. Internal fixation techniques should be recommended for camelids. PMID:23277645

Repair of a pediatric bilateral condylar and symphyseal fracture using a transfacial Steinman pin.

PubMed

Grow, Jacob N; Flores, Roberto L; Tholpady, Sunil S

2014-01-01

The proper management of complex pediatric mandibular fractures remains a topic of debate because of the relatively uncommon presentation of these fractures, combined with concerns related with deciduous teeth, tooth buds, and growth inhibition. In this current study, we present a novel approach to the repair of bilateral condylar fractures with concomitant symphyseal fracture in a 4-year-old girl. Manual closed reduction was first obtained, followed by placement of a transfacial Steinman pin through the angles of the mandible and placement of circummandibular wires. Maxillomandibular fixation remained for 2 weeks and the Steinman pin was removed after 11 weeks. At 3 months of postsurgical follow-up, the patient displayed class I occlusion, facial symmetry, full range of jaw motion, and absence of deviation or pain on full oral excursion. Radiographic findings also revealed complete resolution of the symphyseal fracture with appropriate condylar healing and alignment.

Long-bone fractures in llamas and alpacas: 28 cases (1998-2008).

PubMed

Knafo, S Emmanuelle; Getman, Liberty M; Richardson, Dean W; Fecteau, Marie-Eve

2012-07-01

Treatment and outcome of camelids with long-bone fractures are described. Medical records (1998-2008) of camelids (n = 28) with long-bone fractures were reviewed for signalment, time to presentation, fracture type, method of repair, duration of hospitalization, and post-operative complications. Follow-up information was obtained via telephone interviews with owners. Mean age and weight at presentation were 3.4 years and 56.3 kg, respectively. Twenty-six fractures were treated with internal fixation (n = 11), external fixation (n = 10), combination of internal and external fixation (n = 3), amputation (n = 1), and external fixation followed by amputation (n = 1). Long-term follow-up information was obtained for 19 of the 26 animals. The post-operative complication rate was 23% and owner satisfaction was high. Animals with open fractures were more likely to experience complications. Internal fixation was associated with superior alignment and outcome. Internal fixation techniques should be recommended for camelids.

Fracture control of ground water flow and water chemistry in a rock aquitard.

PubMed

Eaton, Timothy T; Anderson, Mary P; Bradbury, Kenneth R

2007-01-01

There are few studies on the hydrogeology of sedimentary rock aquitards although they are important controls in regional ground water flow systems. We formulate and test a three-dimensional (3D) conceptual model of ground water flow and hydrochemistry in a fractured sedimentary rock aquitard to show that flow dynamics within the aquitard are more complex than previously believed. Similar conceptual models, based on regional observations and recently emerging principles of mechanical stratigraphy in heterogeneous sedimentary rocks, have previously been applied only to aquifers, but we show that they are potentially applicable to aquitards. The major elements of this conceptual model, which is based on detailed information from two sites in the Maquoketa Formation in southeastern Wisconsin, include orders of magnitude contrast between hydraulic diffusivity (K/S(s)) of fractured zones and relatively intact aquitard rock matrix, laterally extensive bedding-plane fracture zones extending over distances of over 10 km, very low vertical hydraulic conductivity of thick shale-rich intervals of the aquitard, and a vertical hydraulic head profile controlled by a lateral boundary at the aquitard subcrop, where numerous surface water bodies dominate the shallow aquifer system. Results from a 3D numerical flow model based on this conceptual model are consistent with field observations, which did not fit the typical conceptual model of strictly vertical flow through an aquitard. The 3D flow through an aquitard has implications for predicting ground water flow and for planning and protecting water supplies.

Fracture control of ground water flow and water chemistry in a rock aquitard

USGS Publications Warehouse

Eaton, T.T.; Anderson, M.P.; Bradbury, K.R.

2007-01-01

There are few studies on the hydrogeology of sedimentary rock aquitards although they are important controls in regional ground water flow systems. We formulate and test a three-dimensional (3D) conceptual model of ground water flow and hydrochemistry in a fractured sedimentary rock aquitard to show that flow dynamics within the aquitard are more complex than previously believed. Similar conceptual models, based on regional observations and recently emerging principles of mechanical stratigraphy in heterogeneous sedimentary rocks, have previously been applied only to aquifers, but we show that they are potentially applicable to aquitards. The major elements of this conceptual model, which is based on detailed information from two sites in the Maquoketa Formation in southeastern Wisconsin, include orders of magnitude contrast between hydraulic diffusivity (K/Ss) of fractured zones and relatively intact aquitard rock matrix, laterally extensive bedding-plane fracture zones extending over distances of over 10 km, very low vertical hydraulic conductivity of thick shale-rich intervals of the aquitard, and a vertical hydraulic head profile controlled by a lateral boundary at the aquitard subcrop, where numerous surface water bodies dominate the shallow aquifer system. Results from a 3D numerical flow model based on this conceptual model are consistent with field observations, which did not fit the typical conceptual model of strictly vertical flow through an aquitard. The 3D flow through an aquitard has implications for predicting ground water flow and for planning and protecting water supplies. ?? 2007 National Ground Water Association.

Delineation of water sources for public-supply wells in three fractured-bedrock aquifer systems in Massachusetts

USGS Publications Warehouse

Lyford, Forest P.; Carlson, Carl S.; Hansen, Bruce P.

2003-01-01

Fractured-bedrock aquifer systems in West Newbury, Maynard, and Paxton, Massachusetts, were studied to advance methods of data collection and analysis for delineating contributing areas to public-supply wells completed in fractured rock and for determining the effects of pumping on streams and wetlands. Contributing areas, as defined for this study, include all areas through which ground water flows from recharge areas to wells. In West Newbury, exploratory public-supply wells at two locations were completed in phyllite of the Eliot Formation. Aquifer testing indicated that subhorizontal and steeply dipping fractures that parallel two sets of foliation form elongated transmissive zones in the bedrock aquifer near the two well locations and also form a vertical hydraulic connection to surficial materials consisting of till at one location and marine clay at the other location. Recharge to bedrock is largely through a thin veneer of till over bedrock, but leakage through thick drumlin tills also recharges bedrock. Simulated contributing areas for the three supply wells pumped at a combined rate of 251 gallons per minute encompass about 1.3 square miles and extend to ground-water divides within most of a subbasin of the Artichoke River. Pumping likely would reduce streamflow in the Artichoke River subbasin by approximately the pumping rate. Pumping is likely to affect wetland areas underlain by till near the wells because of the vertical hydraulic connection to surficial materials. In Maynard, three exploratory public-supply wells were completed in coarse-grained schist of the Nashoba Formation. Aquifer testing indicated that a dense network of fractures in bedrock forms a laterally extensive transmissive zone in bedrock that is well connected vertically to surficial materials consisting of sandy till, lacustrine silts, sand and gravel, and wetland deposits. The simulated contributing area for the three supply wells pumped at a combined rate of 780 gallons per minute encompasses about 1.8 square miles of the Fort Pond Brook drainage area. Pumping likely would reduce streamflow in Fort Pond Brook by about the same amount as the pumping rate, and wetland-water levels within a 2,000-foot radius from the wells are likely to be lowered below the land surface by pumping. In Paxton, three existing supply wells are completed in granofels and schist of the Paxton and Littleton Formations. Aquifer testing demonstrated that a shallow bedrock well completed to a depth of 150 feet is closely connected hydraulically to overlying till. Two deep wells, however, receive much of their water from fractures at depths below 500 feet. Ground-water flow in bedrock appears to be mostly through parting fractures along a foliation set that dips gently (10 degrees) eastward. These parting fractures at depth are poorly connected vertically to shallow bedrock

Nuclear reactor alignment plate configuration

DOEpatents

Altman, David A; Forsyth, David R; Smith, Richard E; Singleton, Norman R

2014-01-28

An alignment plate that is attached to a core barrel of a pressurized water reactor and fits within slots within a top plate of a lower core shroud and upper core plate to maintain lateral alignment of the reactor internals. The alignment plate is connected to the core barrel through two vertically-spaced dowel pins that extend from the outside surface of the core barrel through a reinforcement pad and into corresponding holes in the alignment plate. Additionally, threaded fasteners are inserted around the perimeter of the reinforcement pad and into the alignment plate to further secure the alignment plate to the core barrel. A fillet weld also is deposited around the perimeter of the reinforcement pad. To accomodate thermal growth between the alignment plate and the core barrel, a gap is left above, below and at both sides of one of the dowel pins in the alignment plate holes through with the dowel pins pass.

On the Alignment of Strain, Vorticity and Scalar Gradient in Turbulent, Buoyant, Nonpremixed Flames

NASA Technical Reports Server (NTRS)

Boratav, O. N.; Elghobashi, S. E.; Zhong, R.

1999-01-01

The alignment of vorticity and scalar gradient with the eigendirections of the rate of strain tensor is investigated in turbulent buoyant nonpremixed horizontal and vertical flames. The uniqueness of a buoyant nonpremixed flame is that it contains regions with distinct alignment characteristics. The strain-enstrophy angle Psi is used to identify these regions. Examination of the vorticity field and the vorticity production in these different regions indicates that Psi and consequently the alignment properties near the flame surface identified by the mixture fraction band F approximately equals F(sub st) differ from those in the fuel region, F > F(sub st) and the oxidizer region, F < F(sub st). The F approximately equals F(sub st) band shows strain-dominance resulting in vorticity/alpha alignment while F > F(sub st) (and F < F(sub st) for the vertical flame) band(s) show(s) vorticity/beta alignment. The implication of this result is that the scalar dissipation, epsilon(sub F), attains its maximum value always near F approximately equals F(sub st). These results are also discussed within the framework of recent dynamical results [Galanti et al., Nonlinearity 10, 1675 (1997)] suggesting that the Navier-Stokes equations evolved towards an attracting solution. It is shown that the properties of such an attracting solution are also consistent with our results of buoyant turbulent nonpremixed flames.

Immediate management of posterior urethral disruptions due to pelvic fracture: therapeutic alternatives.

PubMed

Podestá, M L; Medel, R; Castera, R; Ruarte, A

1997-04-01

We retrospectively reviewed the results of 3 types of initial management of pelvic fracture urethral disruption in children. From 1980 to 1994, 35 boys 2 to 15 years old (mean age 8.1) with prostatomembranous urethral disruption were treated, including 17 who also had associated injuries. Immediate treatment included suprapubic cystostomy and delayed urethroplasty in 19 patients (group 1), urethral catheter alignment without traction and concomitant suprapubic cystostomy in 10 (group 2), and primary retropubic anastomotic urethroplasty in 6 (group 3). In all patients in groups 1 and 2 severe urethral obliteration developed. Four group 3 patients (66%) had a stricture at the site of anastomotic repair. After delayed urethroplasty 16 group 1 (84%) and all 10 group 2 patients were continent. However, only 3 group 3 patients (50%) achieved continence. Retrospectively associated bladder neck injury occurred in 5 of the 6 incontinent boys. Erections were observed before and after treatment in all but 3 children. Unstable pelvic ring fractures (type IV) comprised 28% of all pelvic fractures with a high rate of associated injuries. As described, urethral alignment was not beneficial for avoiding urethral obliteration. Therefore we recommend suprapublic cystostomy as the only form of initial treatment in these cases. Urinary incontinence seems more likely related to associated bladder neck rupture and the severity of pelvic fracture rather than to initial treatment or delayed urethral repair. Consequently, when associated bladder neck injury is present, we advocate immediate surgical repair.

Metal-modified and vertically aligned carbon nanotube sensors array for landfill gas monitoring applications.

PubMed

Penza, M; Rossi, R; Alvisi, M; Serra, E

2010-03-12

Vertically aligned carbon nanotube (CNT) layers were synthesized on Fe-coated low-cost alumina substrates using radio-frequency plasma enhanced chemical vapour deposition (RF-PECVD) technology. A miniaturized CNT-based gas sensor array was developed for monitoring landfill gas (LFG) at a temperature of 150 degrees C. The sensor array was composed of 4 sensing elements with unmodified CNT, and CNT loaded with 5 nm nominally thick sputtered nanoclusters of platinum (Pt), ruthenium (Ru) and silver (Ag). Chemical analysis of multicomponent gas mixtures constituted of CO(2), CH(4), H(2), NH(3), CO and NO(2) has been performed by the array sensor responses and pattern recognition based on principal component analysis (PCA). The PCA results demonstrate that the metal-decorated and vertically aligned CNT sensor array is able to discriminate the NO(2) presence in the multicomponent mixture LFG. The NO(2) gas detection in the mixture LFG was proved to be very sensitive, e.g.: the CNT:Ru sensor shows a relative change in the resistance of 1.50% and 0.55% for NO(2) concentrations of 3.3 ppm and 330 ppb dispersed in the LFG, respectively, with a wide NO(2) gas concentration range measured from 0.33 to 3.3 ppm, at the sensor temperature of 150 degrees C. The morphology and structure of the CNT networks have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. A forest-like nanostructure of vertically aligned CNT bundles in the multi-walled form appeared with a height of about 10 microm and a single-tube diameter varying in the range of 5-35 nm. The intensity ratio of the Raman spectroscopy D-peak and G-peak indicates the presence of disorder and defects in the CNT networks. The size of the metal (Pt, Ru, Ag) nanoclusters decorating the CNT top surface varies in the range of 5-50 nm. Functional characterization based on electrical charge transfer sensing mechanisms in the metal-modified CNT-chemoresistor array demonstrates high sensitivity by providing minimal sub-ppm level detection, e.g., download up to 100 ppb NO(2), at the sensor temperature of 150 degrees C. The gas sensitivity of the CNT sensor array depends on operating temperature, showing a lower optimal temperature of maximum sensitivity for the metal-decorated CNT sensors compared to unmodified CNT sensors. Results indicate that the recovery mechanisms in the CNT chemiresistors can be altered by a rapid heating pulse from room temperature to about 110 degrees C. A comparison of the NO(2) gas sensitivity for the chemiresistors based on disorderly networked CNTs and vertically aligned CNTs is also reported. Cross-sensitivity towards relative humidity of the CNT sensors array is investigated. Finally, the sensing properties of the metal-decorated and vertically aligned CNT sensor arrays are promising to monitor gas events in the LFG for practical applications with low power consumption and moderate sensor temperature.

Impact of layer thickness and well orientation on caprock integrity for geologic carbon storage

DOE PAGES

Newell, P.; Martinez, M. J.; Eichhubl, P.

2016-07-29

Economic feasibility of geologic carbon storage demands sustaining large storage rates without damaging caprock seals. Reactivation of pre-existing or newly formed fractures may provide a leakage pathway across caprock layers. In this paper, we apply an equivalent continuum approach within a finite element framework to model the fluid-pressure-induced reactivation of pre-existing fractures within the caprock, during high-rate injection of super-critical CO 2 into a brine-saturated reservoir in a hypothetical system, using realistic geomechanical and fluid properties. We investigate the impact of reservoir to caprock layer thickness, wellbore orientation, and injection rate on overall performance of the system with respect tomore » caprock failure and leakage. We find that vertical wells result in locally higher reservoir pressures relative to horizontal injection wells for the same injection rate, with high pressure inducing caprock leakage along reactivated opening-mode fractures in the caprock. After prolonged injection, leakage along reactivated fractures in the caprock is always higher for vertical than horizontal injection wells. Furthermore, we find that low ratios of reservoir to caprock thickness favor high excess pressure and thus fracture reactivation in the caprock. Finally, injection into thick reservoir units thus lowers the risk associated with CO 2 leakage.« less

Vertically oriented structure and its fracture behavior of the Indonesia white-pearl oyster.

PubMed

Chen, Guowei; Luo, Hongyun; Luo, Shunfei; Lin, Zhenying; Ma, Yue

2017-02-01

Structural calcites, aragonites, and the bonding organic network decide the growth, structure and mechanical properties of the mollusk bivalvia shell. Here, it was found out that the calcite prisms together with the coated organics construct another kind of 'brick and mortar' structure similar to the aragonite tablets. The calcite layer can be divided into three sublayers and direct evidences show that the calcite prisms are produced by two methods: nucleation and growing in the first sublayer; or fusing from the aragonites, which is quite different from some previous reports. The crystallographic orientation, micro hardness and crack propagations were tested and observed by XRD, micro harness tester, SEM and TEM. Submicron twin crystals were observed in the immature aragonite tablets. The fracture processes and the micro deformation of the aragonite tablets are detected by acoustic emission (AE) in the tensile tests, which gave the interpretation of the dynamical fracture processes: plastic deformation and fracture of the organics, and friction of the minerals at the first two stages; wear and fracture of the minerals at the third stage. Calcites and aragonites are combined and working together, like two layers of vertical 'brick and mortar's, ensuring the stable mechanical properties of the whole shell. Copyright © 2016 Elsevier Ltd. All rights reserved.

An integrated study of seismic anisotropy and the natural fracture system at the Conoco Borehole Test Facility, Kay County, Oklahoma

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

Queen, J.H.; Rizer, W.D.

1990-07-10

A significant body of published work has developed establishing fracture-related seismic anisotropy as an observable effect. To further the understanding of seismic birefringence techniques in characterizing natural fracture systems at depth, an integrated program of seismic and geologic measurements has been conducted at Conoco's Borehole Test Facility in Kay County, Oklahoma. Birefringence parameters inferred from the seismic data are consistent with a vertical fracture model of density 0.04 striking east-northeast. That direction is subparallel to a fracture set mapped both on the surface and from subsurface data, to the in situ maximum horizontal stress, and to the inferred microfabric.

Role of the wetting layer in the enhanced responsivity of InAs/GaAsSb quantum dot infrared photodetectors

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

Guzmán, Álvaro, E-mail: guzman@die.upm.es; Yamamoto, Kenji; Ulloa, J. M.

2015-07-06

InAs/GaAs{sub 1−x}Sb{sub x} Quantum Dot (QD) infrared photodetectors are analyzed by photocurrent spectroscopy. We observe that the integrated responsivity of the devices is improved with the increasing Sb mole fraction in the capping layer, up to 4.2 times for x = 17%. Since the QD layers are not vertically aligned, the vertical transport of the carriers photogenerated within the QDs takes place mainly through the bulk material and the wetting layer of the additional QD regions. The lower thickness of the wetting layer for high Sb contents results in a reduced capture probability of the photocarriers, thus increasing the photoconductive gain andmore » hence, the responsivity of the device. The growth of not vertically aligned consecutive QD layers with a thinner wetting layer opens a possibility to improve the performance of quantum dot infrared photodetectors.« less

The Development of High-Density Vertical Silicon Nanowires and Their Application in a Heterojunction Diode

PubMed Central

Chang, Wen-Chung; Su, Sheng-Chien; Wu, Chia-Ching

2016-01-01

Vertically aligned p-type silicon nanowire (SiNW) arrays were fabricated through metal-assisted chemical etching (MACE) of Si wafers. An indium tin oxide/indium zinc oxide/silicon nanowire (ITO/IZO/SiNW) heterojunction diode was formed by depositing ITO and IZO thin films on the vertically aligned SiNW arrays. The structural and electrical properties of the resulting ITO/IZO/SiNW heterojunction diode were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and current−voltage (I−V) measurements. Nonlinear and rectifying I−V properties confirmed that a heterojunction diode was successfully formed in the ITO/IZO/SiNW structure. The diode had a well-defined rectifying behavior, with a rectification ratio of 550.7 at 3 V and a turn-on voltage of 2.53 V under dark conditions. PMID:28773656

Enhanced NH3 gas sensing properties of a QCM sensor by increasing the length of vertically orientated ZnO nanorods

NASA Astrophysics Data System (ADS)

Minh, Vu Anh; Tuan, Le Anh; Huy, Tran Quang; Hung, Vu Ngoc; Quy, Nguyen Van

2013-01-01

Vertically aligned ZnO nanorods were directly synthesised on a gold electrode of quartz crystal microbalance (QCM) by a simple low-temperature hydrothermal method for a NH3 gas sensing application. The length of vertically aligned ZnO nanorods was increased to purpose enhancement in the gas sensing response of the sensor. The length of ZnO nanorods increased with an increase in growth time. The growth time of ZnO nanorods was systematically varied in the range of 1-4 h to examine the effect of the length of the ZnO nanorods on the gas sensing properties of the fabricated sensors. The gas sensing properties of sensors with different ZnO nanorods lengths was examined at room temperature for various concentrations of NH3 (50-800 ppm) in synthetic air. Enhancement in gas sensing response by increasing the length of ZnO nanorods was observed.

Reordering transitions during annealing of block copolymer cylinder phases

DOE PAGES

Majewski, Pawel W.; Yager, Kevin G.

2015-10-06

While equilibrium block-copolymer morphologies are dictated by energy-minimization effects, the semi-ordered states observed experimentally often depend on the details of ordering pathways and kinetics. In this study, we explore reordering transitions in thin films of block-copolymer cylinder-forming polystyrene- block-poly(methyl methacrylate). We observe several transient states as films order towards horizontally-aligned cylinders. In particular, there is an early-stage reorganization from randomly-packed cylinders into hexagonally-packed vertically-aligned cylinders; followed by a reorientation transition from vertical to horizontal cylinder states. These transitions are thermally activated. The growth of horizontal grains within an otherwise vertical morphology proceeds anisotropically, resulting in anisotropic grains in the finalmore » horizontal state. The size, shape, and anisotropy of grains are influenced by ordering history; for instance, faster heating rates reduce grain anisotropy. These results help elucidate aspects of pathway-dependent ordering in block-copolymer thin films.« less

Microstructural effects on fracture toughness of polycrystalline ceramics in combined mode I and mode II loading

NASA Technical Reports Server (NTRS)

Singh, D.; Shetty, D. K.

1988-01-01

Fracture toughness of polycrystalline alumina and ceria partially-stabilized tetragonal zirconia (CeO2-TZP) ceramics were assessed in combined mode I and mode II loading using precracked disk specimens in diametral compression. Stress states ranging from pure mode I, combined mode I and mode II, and pure mode II were obtained by aligning the center crack at specific angles relative to the loading diameter. The resulting mixed-mode fracture toughness envelope showed significant deviation to higher fracture toughness in mode II relative to the predictions of the linear elastic fracture mechanics theory. Critical comparison with corresponding results on soda-lime glass and fracture surface observations showed that crack surface resistance arising from grain interlocking and abrasion was the main source of the increased fracture toughness in mode II loading of the polycrystalline ceramics. The normalized fracture toughness for pure mode II loading, (KII/KIc), increased with increasing grain size for the CeO2-TZP ceramics. Quantitative fractography confirmed an increased percentage of transgranular fracture of the grains in mode II loading.

Horizontal drilling in the Austin Chalk: Stratigraphic factors

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

Durham, C.O. Jr.; Bobigian, R.A.

1990-05-01

Horizontal drilling has renewed interest in the Austin chalk in south-central Texas. Large fields on opposite sides of the San Marcos arch Giddings to the northeast and Pearsall to the southwest were active with vertical drilling 10 years ago. Giddings' 4,500 Austin wells produced 209 million BO and 934 bcfg of gas through 1988; Pearsall's 1,440 wells produced 57 million BO and 35 bcfg of gas. Most vertical wells were completed, 20% were economic successes, 40% were marginal, 40% were uneconomic due to uneven areal distribution of near-vertical fractures and small faults, which provide reservoirs in otherwise tight chalk. Horizontalmore » drilling, led by Amoco in Giddings and Oryx in Pearsall, enhances the chances of encountering the fractures by drilling perpendicular to the fracture trend. Horizontal drilling requires preselection of the stratigraphic horizon to be penetrated. One must understand the variable Austin stratigraphy to choose the zone with the most brittle character and best matrix porosity, both reduced by increased clay content. Chalk 130 ft thick on the San Marcos arch thickens to 600 to 800 ft in central Giddings field where middle marl separates lower and upper chalk Northeastward only lower chalk is preserved beneath a post-Austin submarine channel. The Austin thickens to 300-500 ft in Pearsall field where middle member ash beds separate lower and upper chalk inhibiting vertical reservoir communication. Locally, on the Pearsall arch, ash is missing, lower chalk thickens, and upper chalk thins.« less

Porosimetry and packing morphology of vertically-aligned carbon nanotube arrays via impedance spectroscopy.

PubMed

Mutha, Heena K; Lu, Yuan; Stein, Itai; Cho, H Jeremy; Suss, Matthew; Laoui, Tahar; Thompson, Carl; Wardle, Brian; Wang, Evelyn

2016-12-13

Vertically aligned one-dimensional nanostructure arrays are promising in many applications such as electrochemical systems, solar cells, and electronics, taking advantage of high surface area per unit volume, nanometer length scale packing, and alignment leading to high conductivity. However, many devices need to optimize arrays for device performance by selecting an appropriate morphology. Developing a simple, non-invasive tool for understanding the role of pore volume distribution and interspacing would aid in the optimization of nanostructure morphologies in electrodes. In this work, we combined electrochemical impedance spectroscopy (EIS) with capacitance measurements and porous electrode theory to conduct in situ porosimetry of vertically-aligned carbon nanotubes (VA-CNTs) non-destructively. We utilized the EIS measurements with a pore size distribution model to quantify the average and dispersion of inter-CNT spacing (Γ), stochastically, in carpets that were mechanically densified from 1.7 × 10¹⁰ tubes/cm² to 4.5 × 10¹¹ tubes/cm². Our analysis predicts that the inter-CNT spacing ranges from over 100 ± 50 nm in sparse carpets to sub 10 ± 5 nm in packed carpets. Our results suggest that waviness of CNTs leads to variations in the inter-CNT spacing, which can be significant in sparse carpets. This methodology can be used to predict the performance of many nanostructured devices, including supercapacitors, batteries, solar cells, and semiconductor electronics. Copyright 2016 IOP Publishing Ltd.

Epitaxial growth of aligned AlGalnN nanowires by metal-organic chemical vapor deposition

DOEpatents

Han, Jung; Su, Jie

2008-08-05

Highly ordered and aligned epitaxy of III-Nitride nanowires is demonstrated in this work. <1010> M-axis is identified as a preferential nanowire growth direction through a detailed study of GaN/AlN trunk/branch nanostructures by transmission electron microscopy. Crystallographic selectivity can be used to achieve spatial and orientational control of nanowire growth. Vertically aligned (Al)GaN nanowires are prepared on M-plane AlN substrates. Horizontally ordered nanowires, extending from the M-plane sidewalls of GaN hexagonal mesas or islands demonstrate new opportunities for self-aligned nanowire devices, interconnects, and networks.

Description and analysis of cored hydraulic fractures -- Lost Hills field, Kern County, California

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

Fast, R.E.; Murer, A.S.; Timmer, R.S.

1994-05-01

An inclined observation well was drilled in shallow (2,000 ft) Opal-A diatomite. Seven sand-propped hydraulic fractures were cored and recovered. The hydraulic fractures were found within 5[degree] of the azimuth measured with tilt meters and were tilted 15[degree] from vertical, oriented perpendicular to the formation bedding dip. Hydraulic fractures widths ranged from less than one sand grain (40/60 mesh) to 0.4 in. Scanning electron microscopy (SEM) examination of fracture faces showed no damage to the matrix from proppant embedment or compaction, and no evidence of guard residue was detected in the proppant pack or on the formation face. Fractures appearmore » to be considerably longer than modeled. Three closely spaced fractures are interpreted to be branches of a single hydraulic fracture treatment. This paper presents a description of the fractures recovered during coring in Well OO2. Findings related to fracture dimensions and orientations, fracture sources, fracture permeability measurements, and fracture characteristics (proppant embedment, presence of gel residue) are presented. Implications related to field development are discussed.« less

Biomechanical Concepts for Fracture Fixation

PubMed Central

Bottlang, Michael; Schemitsch, Christine E.; Nauth, Aaron; Routt, Milton; Egol, Kenneth; Cook, Gillian E.; Schemitsch, Emil H.

2015-01-01

Application of the correct fixation construct is critical for fracture healing and long-term stability; however, it is a complex issue with numerous significant factors. This review describes a number of common fracture types, and evaluates their currently available fracture fixation constructs. In the setting of complex elbow instability, stable fixation or radial head replacement with an appropriately sized implant in conjunction with ligamentous repair is required to restore stability. For unstable sacral fractures, “standard” iliosacral screw fixation is not sufficient for fractures with vertical or multiplanar instabilities. Periprosthetic femur fractures, in particular Vancouver B1 fractures, have increased stability when using 90/90 fixation versus a single locking plate. Far Cortical Locking combines the concept of dynamization with locked plating in order to achieve superior healing of a distal femur fracture. Finally, there is no ideal construct for syndesmotic fracture stabilization; however, these fractures should be fixed using a device that allows for sufficient motion in the syndesmosis. In general, orthopaedic surgeons should select a fracture fixation construct that restores stability and promotes healing at the fracture site, while reducing the potential for fixation failure. PMID:26584263

[Fractures of the thoracic and lumbar spine in children and adolescents].

PubMed

Kraus, R; Stahl, J-P; Heiss, C; Horas, U; Dongowski, N; Schnettler, R

2013-05-01

Only 1.5-2% of all fractures in children and adolescents are fractures of the thoracic and lumbar spine. Treatment is most often conservative. This study compares the own experience with the recent literature. Over a 48 month period all patients with fractures of the thoracic and lumbar spine, younger than 16 years were included prospectively. Of the patients 67 underwent follow-up investigations after 3-36 months. The average age of the patients was 11.9 years. Sports (53%) and traffic (28%) accidents were most frequent. Fractures most often appeared in the mid-thoracic (47%) and thoracolumbar spine (41%). Operative treatment was performed in 9 cases (10.4%). Secondary loss of alignment was not observed neither after conservative nor operative treatment. Neurological deficits (n=2) did not completely improve. Most fractures of the thoracic and lumbar spine heal fast and without any sequelae. Unstable fractures of type B and C (exclusively occurring as a result of traffic accidents) need operative stabilization as in adults.

Aspect sensitive E- and F-region SPEAR-enhanced incoherent backscatter observed by the EISCAT Svalbard radar

NASA Astrophysics Data System (ADS)

Dhillon, R. S.; Robinson, T. R.; Yeoman, T. K.

2009-01-01

Previous studies of the aspect sensitivity of heater-enhanced incoherent radar backscatter in the high-latitude ionosphere have demonstrated the directional dependence of incoherent scatter signatures corresponding to artificially excited electrostatic waves, together with consistent field-aligned signatures that may be related to the presence of artificial field-aligned irregularities. These earlier high-latitude results have provided motivation for repeating the investigation in the different geophysical conditions that obtain in the polar cap ionosphere. The Space Plasma Exploration by Active Radar (SPEAR) facility is located within the polar cap and has provided observations of RF-enhanced ion and plasma line spectra recorded by the EISCAT Svalbard UHF incoherent scatter radar system (ESR), which is collocated with SPEAR. In this paper, we present observations of aspect sensitive E- and F-region SPEAR-induced ion and plasma line enhancements that indicate excitation of both the purely growing mode and the parametric decay instability, together with sporadic E-layer results that may indicate the presence of cavitons. We note consistent enhancements from field-aligned, vertical and also from 5° south of field-aligned. We attribute the prevalence of vertical scatter to the importance of the Spitze region, and of that from field-aligned to possible wave/irregularity coupling.

Horizontal versus vertical orientation of the loop for tension band wiring of transverse patella fractures.

PubMed

Lee, Sang Ki; Hwang, Yoon Sub; Choy, Won Sik

2014-03-01

Conventional operative treatments of patella fractures are frequently associated with implant failure or displacement. Recent biomechanical studies showed that the orientation of the wire loop and the site of the wire twist can affect the fixation strength. The purpose of this study was to compare the clinical outcome of the tension band technique with loops in different orientations and different knot positions. For this retrospective study, 72 patella fractures (71 patients) were fixed with figure-of-eight configurations in combination with 2 K-wires. Patients were divided into 3 groups according to the orientation of tension band construct. A total of 40 patella fractures were placed with figure-of-eight configurations in a vertical orientation either with 1 wire twist (group 1; 16 patella fractures) or with 2 wire twists at the adjacent corners (group 2; 24 patella fractures). Thirty-two patella fractures were placed with figure-of-eight configurations in a horizontal orientation with 2 wire twists at the adjacent corners (group 3). Range of motion, complication rates, and knee scoring scales (Hospital for Special Surgery and Lysholm) were assessed during serial follow-up. Satisfactory reductions were achieved in all groups, but functional results in the early stage were different. Group 3 had better Hospital for Special Surgery and Lysholm scores at 3 months postoperatively; however, at 6 months and 1 year postoperatively, all groups had similar scores. At the 1-year follow-up, all groups achieved acceptable flexion and range of motion. The overall complication rate was lower in the horizontal group (12.5%). Placing the figure-of-eight tension band construct in a horizontal orientation can provide functional benefits in the early stage after patella fractures. Copyright 2014, SLACK Incorporated.

UNDERSTANDING HARD ROCK HYDROGEOLOGY THROUGH AN EXPERIMENTAL HYDROGEOLOGICAL PARK IN SOUTH INDIA: Site development and investigations on the major role of the fractured zone in crystalline aquifers

NASA Astrophysics Data System (ADS)

Ahmed, S.; Guiheneuf, N.; Boisson, A.; Marechal, J.; Chandra, S.; Dewandel, B.; Perrin, J.

2012-12-01

In water stressed south India most of the groundwater used for irrigation is pumped from crystalline rocks aquifers. In those structures groundwater flow dominantly occur in a shallow higher-permeability zone that overlies a deeper lower-permeability zone hosting little flow. The fractured zone of the weathering profile plays an important role for groundwater. In order to understand clearly this impact on water availability and quality changes the Experimental Hydrogeological Park at Choutuppal, Andhra Pradesh, India is developed in the framework of the SORE H+ network. Several hydraulic tests (injection, flowmeter profiles, single-packer tests…) and geophysical measurements (ERT, Borehole logging…) are carried out on the site in order to characterize the depth-dependence of hydrodynamic parameters in the Indian Archean granite. Specific investigation on a borewell through packer tests demonstrate that the most conductive part of the aquifer corresponds to the upper part of the fractured layer, located just below the saprolite bottom, between 15 meters and 20 meters depth. There is no highly conductive fracture beyond 20 meters depth and no indication for any conductive fracture beyond 25 meters depth. Packer tests show that the upper part of the fractured layer (15-20 m depth) is characterized by a good vertical connectivity. On the contrary, the tests carried out below 20 m depth show no vertical connectivity at all. The geometry of the fracture network and associated hydrodynamic parameters are in agreement with the conceptual model of hard-rock aquifers that derive its properties from weathering processes. The general existence of such a highly conductive structure at the top of the fractured zone has a great impact on water prospection and exploitation in such crystalline aquifers.

Potential seal bypass and caprock storage produced by deformation-band-to-opening-mode-fracture transition at the reservoir/caprock interface

DOE PAGES

Raduha, S.; Butler, D.; Mozley, P. S.; ...

2016-06-18

Here, we examined the potential impact on CO 2 transport of zones of deformation bands in reservoir rock that transition to opening-mode fractures within overlying caprock. Sedimentological and petrophysical measurements were collected along an approximately 5 m × 5 m outcrop of the Slick Rock and Earthy Members of the Entrada Sandstone on the eastern flank of the San Rafael Swell, Utah, USA. Measured deformation band permeability (2 mD) within the reservoir facies is about three orders of magnitude lower than the host sandstone. Average permeability of the caprock facies (0.0005 mD) is about seven orders of magnitude lower thanmore » the host sandstone. Aperture-based permeability estimates of the opening-mode caprock fractures are high (3.3 × 10 7 mD). High-resolution CO 2–H 2O transport models incorporate these permeability data at the millimeter scale. We then varied fault properties at the reservoir/caprock interface between open fractures and deformation bands as part of a sensitivity study. Numerical modeling results suggest that zones of deformation bands within the reservoir strongly compartmentalize reservoir pressures largely blocking lateral, cross-fault flow of supercritical CO 2. Significant vertical CO 2 transport into the caprock occurred in some scenarios along opening-mode fractures. The magnitude of this vertical CO 2 transport depends on the small-scale geometry of the contact between the opening-mode fracture and the zone of deformation bands, as well as the degree to which fractures penetrate caprock. Finally, the presence of relatively permeable units within the caprock allows storage of significant volumes of CO 2, particularly when the fracture network does not extend all the way through the caprock.« less

Deep Seismic Reflection Images across a Major Reactivated Fracture Zone in the Wharton Basin: Implications for the Location of the Plate Boundary between India and Australia

NASA Astrophysics Data System (ADS)

Carton, H. D.; Singh, S. C.; Hananto, N. D.; Martin, J.; Djajadihardja, Y. S.; Udrekh, U.; Franke, D.; Gaedicke, C.

2012-12-01

The equatorial Indian Ocean has long been recognized to be hosting extensive "intra-plate" deformation. To west of the Ninety-East Ridge (NER), The Central Indian Ocean Basin is characterized by N-S compression in a broad region with E-W trending folds and high-angle reverse faulting. To the east of NER in the Wharton Basin, deformation mainly occurs along reactivated N5°E-trending oceanic fracture zones with left-lateral strike-slip motion. Near longitude 93°E in the Wharton Basin runs a major reactivated fracture zone, along which the epicenters of the two recent Mw=8.6 and Mw=8.2 strike-slip earthquakes of April 11, 2012, and an Mw=7.2 foreshock that occurred in January 2012 are aligned. The April 11 events are the largest known oceanic events occurring away from the main plate boundaries. They ruptured a 20-40 km thick section of the oceanic lithosphere, i.e. down to depths at which no direct images of fault zones have been obtained so far. Deep seismic reflection data acquired in the Mw=8.6 earthquake rupture zone ~100 km north of the epicenter shows the presence of sub-Moho reflectivity down to 37 km depth in the oceanic mantle. We interpret these events as reflections off the earthquake-generating fault plane in the oceanic mantle, in accordance with results suggesting that brittle deformation of the oceanic lithosphere extends well into the mantle down to the 600°C isotherm. The fracture zone near 93°E separates lithospheres of contrasting crustal thicknesses (3.5-4.5 km versus 6 km) with a 10 Ma age difference, and therefore seems to act as a rheological boundary. We find that the deep reflections could originate from either a plane trending approximately N105°E, at high angle to the fracture zone, or from the fracture zone itself if the dip of the fault surface decreases from nearly vertical in the sediments to about 45° in the oceanic mantle. We propose that this fracture zone is a major tectonic boundary in the Wharton Basin, and that the three 2012 earthquakes ruptured a large section of it as part of a poorly-defined diffuse plate boundary between the Indian and Australian plates, with slip occurring on this re-activated N-S fracture zone and on fossil E-W spreading-related faults. Over 1000 km of this plate boundary could have ruptured since the great 2004 Sumatra earthquake.

Orthodontic treatment for oral rehabilitation after multiple maxillofacial bone fractures.

PubMed

Nakamura, Yoshiki; Ogino, Tomoko Kuroiwa; Hirashita, Ayao

2008-09-01

We present the orthodontic treatment of a patient with occlusal dysfunction after plastic surgery for multiple maxillofacial bone fractures caused by a traffic accident. The patient had mandibular deviation to the right because of inappropriate repositioning and fixation of the fractured bone and complete avulsion of both mandibular central incisors. The bilateral mandibular incisors, canines, and premolars were also suspected of partial avulsion or alveolar bone fracture. Several tests, including percussion and dental computed tomography, were performed on these teeth to rule out ankylosis and confirm tooth movement. Camouflage orthodontic treatment was carried out with expansion of the maxillary arch, alignment of both arches, and space closure between the mandibular lateral incisors to improve the occlusion. Good occlusion and interdigitation were obtained. Orthodontic treatment is useful for the rehabilitation of occlusal dysfunction caused by multiple maxillofacial bone fractures.

TOPOGRAPHY, STRESSES, AND STABILITY AT YUCCA MOUNTAIN, NEVADA.

USGS Publications Warehouse

Wolfs, Henri; Savage, William Z.

1985-01-01

Plane-strain solutions are used to analyze the influence of topography on the state of stress at Yucca Mountain, Nye County, Nevada. The results are in good agreement with the measured stress components obtained in drill holes by the hydraulic-fracturing technique, particularly those measured directly beneath the crest of the ridge, and indicate that these stresses are gravitationally induced. A separate analysis takes advantage of the fact that a well-developed set of vertical faults and fractures, subparallel to the ridge trend, imparts a vertical transverse isotropy to the rock and that, as a consequence of gravitational loading, unequal horizontal stresses are induced in directions perpendicular and parallel to the anisotropy.

Tibial stress fracture after computer-navigated total knee arthroplasty.

PubMed

Massai, F; Conteduca, F; Vadalà, A; Iorio, R; Basiglini, L; Ferretti, A

2010-06-01

A correct alignment of the tibial and femoral component is one of the most important factors determining favourable long-term results of a total knee arthroplasty (TKA). The accuracy provided by the use of the computer navigation systems has been widely described in the literature so that their use has become increasingly popular in recent years; however, unpredictable complications, such as displaced or stress femoral or tibial fractures, have been reported to occur a few weeks after the operation. We present a case of a stress tibial fracture that occurred after a TKA performed with the use of a computer navigation system. The stress fracture, which eventually healed without further complications, occurred at one of the pinhole sites used for the placement of the tibial trackers.

49 CFR 572.154 - Thorax assembly and test procedure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... R5 of this subpart, with the lower limbs extended forward, parallel to the midsagittal plane and the arms 0 to 5 degrees forward of vertical. The dummy's midsagittal plane is vertical within ±/1 degree... alignment). (4) Establish the impact point at the chest midsagittal plane so that the impact point of the...

The perception of verticality in lunar and Martian gravity conditions.

PubMed

de Winkel, Ksander N; Clément, Gilles; Groen, Eric L; Werkhoven, Peter J

2012-10-31

Although the mechanisms of neural adaptation to weightlessness and re-adaptation to Earth-gravity have received a lot of attention since the first human space flight, there is as yet little knowledge about how spatial orientation is affected by partial gravity, such as lunar gravity of 0.16 g or Martian gravity of 0.38 g. Up to now twelve astronauts have spent a cumulated time of approximately 80 h on the lunar surface, but no psychophysical experiments were conducted to investigate their perception of verticality. We investigated how the subjective vertical (SV) was affected by reduced gravity levels during the first European Parabolic Flight Campaign of Partial Gravity. In normal and hypergravity, subjects accurately aligned their SV with the gravitational vertical. However, when gravity was below a certain threshold, subjects aligned their SV with their body longitudinal axis. The value of the threshold varied considerably between subjects, ranging from 0.03 to 0.57 g. Despite the small number of subjects, there was a significant positive correlation of the threshold with subject age, which calls for further investigation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Lower crustal seismic activity in the Adana Basin (Eastern Mediterranean): Possible connection to gravitational flexure

NASA Astrophysics Data System (ADS)

Ergin, Mehmet; Aktar, Mustafa

2018-04-01

High quality broadband data, together with the application of the double difference relocation technique, has been used to study the characteristics of the lower crustal seismicity in the Adana Basin, in southwestern Turkey. Deep events are clearly seen to be restricted only to the Adana Basin and never extend outside its boundaries. Furthermore, the seismogenic zone is observed to align roughly with the main axis of the basin and plunges steadily in the SSW-direction, following the basement trend of the Adana Basin. Similarities between geometries of the basin evolution and the deep seismic production suggest that both processes are closely related. A flexure process is proposed related to the subsidence of the Adana Basin. The seismogenic zone, originally at a shallow depth, is assumed to have been displaced vertically into the lower crust, by flexure. The temperature evolution of the crust during the flexure has been studied in detail using finite difference modeling, with amplitude and duration parameters taken from earlier studies. It has been concluded that the physical conditions for brittle fracturing remained unchanged for an extended period of time after the flexure. The brittle layers originally at shallow depths, preserved their original thermal properties after the subsidence and will continue to produce earthquakes at considerable depths. Numerical tests using inferred parameters imply a total vertical shift of 7-8 km for the seismogenic zone. Discussions for additional processes, which may further contribute to the cooling of the crust, are also included.

[Distal clavicle fracture].

PubMed

Seppel, G; Lenich, A; Imhoff, A B

2014-06-01

Reposition and fixation of unstable distal clavicle fractures with a low profile locking plate (Acumed, Hempshire, UK) in conjunction with a button/suture augmentation cerclage (DogBone/FibreTape, Arthrex, Naples, FL, USA). Unstable fractures of the distal clavicle (Jäger and Breitner IIA) in adults. Unstable fractures of the distal clavicle (Jäger and Breitner IV) in children. Distal clavicle fractures (Jäger and Breitner I, IIB or III) with marked dislocation, injury of nerves and vessels, or high functional demand. Patients in poor general condition. Fractures of the distal clavicle (Jäger and Breitner I, IIB or III) without marked dislocation or vertical instability. Local soft-tissue infection. Combination procedure: Initially the lateral part of the clavicle is exposed by a 4 cm skin incision. After reduction of the fracture, stabilization is performed with a low profile locking distal clavicle plate. Using a special guiding device, a transclavicular-transcoracoidal hole is drilled under arthroscopic view. Additional vertical stabilization is arthroscopically achieved by shuttling the DogBone/FibreTape cerclage from the lateral portal cranially through the clavicular plate. The two ends of the FibreTape cerclage are brought cranially via adjacent holes of the locking plate while the DogBone button is placed under the coracoid process. Thus, plate bridging is achieved. Finally reduction is performed and the cerclage is secured by surgical knotting. Use of an arm sling for 6 weeks. Due to the fact that the described technique is a relatively new procedure, long-term results are lacking. In the short term, patients postoperatively report high subjective satisfaction without persistent pain.

Vertical Alignment of Single-Walled Carbon Nanotubes on Nanostructure Fabricated by Atomic Force Microscope

DTIC Science & Technology

2007-02-16

SWNT films by Langmuir - Blodgett methods,8 and chemical assembly of SWNTs on a large substrate.9 Al- though these methods provide a good way to control... Langmuir - Blodgett to Self-Assembly. Academic: New York, (1991). [10] Moon, J.H., Shin, J.W., Kim, S.Y., Park, J.W. Langmuir , 12, 4621, (1996...aligning CNTs in solu- tion by applying an electric field5 or a magnetic field,6 align- ing SWNTs by blending them with liquid crystal,7 assem- bling

Screw Loosening and Pelvic Canal Narrowing After Lateral Plating of Feline Ilial Fractures With Locking and Nonlocking Plates.

PubMed

Schmierer, Philipp A; Kircher, Patrick R; Hartnack, Sonja; Knell, Sebastian C

2015-10-01

To compare the frequency of complications, including screw loosening and pelvic canal narrowing, associated with dynamic compression plating, locking plating, and double locking plating of ilial fractures in cats. Historical cohort study. The radiographs and medical records of cats with pelvic fractures that were presented between 2004 and 2013 were reviewed. The cases were categorized based on the plate type and number as dynamic compression plate (DCP), single locking plate (LPS) and double locking plates (dLPS). The frequency of screw loosening was compared across categories using a Fisher's exact test. The change in pelvic alignment, described by the change in sacral index (postoperative sacral index-followup sacral index), was compared across plate categories using ANOVA. The frequency of screw loosening for DCP (5/10) was significantly higher than LPS (1/13) and dLPS (0/11) (P = .05, P = .012, respectively). There was no significant difference in the SI change across plate categories. The mean change in sacral index for DCP was -0.11 (95%CI -0.25 to 0.03), for LPS was 0.0007 (95%CI -0.07 to 0.08), and for dLPS was -0.01 (95%CI -0.04 to 0.02). None of the cats showed constipation postoperatively. Screw loosening occurred less often but the change in pelvic canal alignment was not significantly different in ilial fractures repaired with LPS or dLPS compared to ilial fractures repaired with DCP. Locking plating of ilial fractures in cats may offer advantages compared to nonlocking plating. © Copyright 2015 by The American College of Veterinary Surgeons.

Optimization of Tube Current in Cone-beam Computed Tomography for the Detection of Vertical Root Fractures with Different Intracanal Materials.

PubMed

Gaêta-Araujo, Hugo; Silva de Souza, Gabriela Queiroz; Freitas, Deborah Queiroz; de Oliveira-Santos, Christiano

2017-10-01

There is no consensus about the accuracy of cone-beam computed tomography (CBCT) for detecting vertical root fractures (VRFs), nor is there certainty about the isolated effect of different tube current parameters on the diagnosis of VRF through CBCT scans. This study aimed to evaluate how tube current affects the detection of VRF on CBCT examinations in the absence of intracanal materials and in the presence of gutta-percha (GP) and metal (MP) or fiberglass (FP) intracanal posts. The sample consisted of 320 CBCT scans of tooth roots with and without VRF divided into 8 groups: no fracture/no intracanal material; no fracture + GP; no fracture + MP; no fracture + FP; fracture/no intracanal material; fracture + GP; fracture + MP; fracture + FP. The scans were acquired with an OP300 unit using 4 different milliamperes (4 mA, 8 mA, 10 mA, 13 mA). Five oral radiologists analyzed the images. The area under the receiver operating characteristic curve (Az), sensitivity, specificity, positive and negative predictive values, and interobserver agreement were calculated. Diagnostic performance for the different milliamperes tested was similar for teeth without root filling materials or with FP. Teeth with GP and MP showed the highest Az values for 8 mA and 10 mA, respectively. For teeth with MP, specificity was significantly higher when 10 mA was used. For teeth without root filling materials or with FP, the use of a reduced milliampere does not seem to influence the detection of VRF in a significant manner. For teeth with GP and MP, an increased milliampere may lead to increased diagnostic performance. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Biomechanical stability of intramedullary technique for fixation of joint depressed calcaneus fracture.

PubMed

Nelson, Joshua D; McIff, Terence E; Moodie, Patrick G; Iverson, Jamey L; Horton, Greg A

2010-03-01

Internal fixation of the os calcis is often complicated by prolonged soft tissue management and posterior facet disruption. An ideal calcaneal construct would include minimal hardware prominence, sturdy posterior facet fixation and nominal soft tissue disruption. The purpose of this study was to develop such a construct and provide a biomechanical analysis comparing our technique to a standard internal fixation technique. Twenty fresh-frozen cadaver calcanei were used to create a reproducible Sanders type-IIB calcaneal fracture pattern. One calcaneus of each pair was randomly selected to be fixed using our compressive headless screw technique. The contralateral matched calcaneus was fixed with a nonlocking calcaneal plate in a traditional fashion. Each calcaneus was cyclically loaded at a frequency of 1 Hz for 4000 cycles using an increasing force from 250 N to 1000 N. An Optotrak motion capturing system was used to detect relative motion of the three fracture fragments at eight different points along the fracture lines. Horizontal separation and vertical displacement at the fracture lines was recorded, as well as relative rotation at the primary fracture line. When the data were averaged, there was more horizontal displacement at the primary fracture line of the plate and screw construct compared to the headless screw construct. The headless screw construct also had less vertical displacement at the primary fracture line at every load. On average those fractures fixed with the headless screw technique had less rotation than those fixed with the side plate technique. A new headless screw technique for calcaneus fracture fixation was shown to provide stability as good as, or better than, a standard side plating technique under the axial loading conditions of our model. Although further testing is needed, the stability of the proposed technique is similar to that typically provided by intramedullary fixation. This fixation technique provides a biomechanically stable construct with the potential for a minimally invasive approach and improved post-operative soft tissue healing.

Cost-Effective Systems for Atomic Layer Deposition

ERIC Educational Resources Information Center

Lubitz, Michael; Medina, Phillip A., IV; Antic, Aleks; Rosin, Joseph T.; Fahlman, Bradley D.

2014-01-01

Herein, we describe the design and testing of two different home-built atomic layer deposition (ALD) systems for the growth of thin films with sub-monolayer control over film thickness. The first reactor is a horizontally aligned hot-walled reactor with a vacuum purging system. The second reactor is a vertically aligned cold-walled reactor with a…

Combined antenna and localized plasmon resonance in Raman scattering from random arrays of silver-coated, vertically aligned multiwalled carbon nanotubes.

PubMed

Dawson, P; Duenas, J A; Boyle, M G; Doherty, M D; Bell, S E J; Kern, A M; Martin, O J F; Teh, A-S; Teo, K B K; Milne, W I

2011-02-09

The electric field enhancement associated with detailed structure within novel optical antenna nanostructures is modeled using the surface integral equation technique in the context of surface-enhanced Raman scattering (SERS). The antennae comprise random arrays of vertically aligned, multiwalled carbon nanotubes dressed with highly granular Ag. Different types of "hot-spot" underpinning the SERS are identified, but contrasting characteristics are revealed. Those at the outer edges of the Ag grains are antenna driven with field enhancement amplified in antenna antinodes while intergrain hotspots are largely independent of antenna activity. Hot-spots between the tops of antennae leaning towards each other also appear to benefit from antenna amplification.

Stable Fe nanomagnets encapsulated inside vertically-aligned carbon nanotubes.

PubMed

Bondino, Federica; Magnano, Elena; Ciancio, Regina; Castellarin Cudia, Carla; Barla, Alessandro; Carlino, Elvio; Yakhou-Harris, Flora; Rupesinghe, Nalin; Cepek, Cinzia

2017-12-06

Well-defined sized (5-10 nm) metallic iron nanoparticles (NPs) with body-centered cubic structure encapsulated inside the tip of millimeter-long vertically aligned carbon nanotubes (VACNTs) of uniform length have been investigated with high-resolution transmission electron microscopy and soft X-ray spectroscopy techniques. Surface-sensitive and chemically-selective measurements have been used to evaluate the magnetic properties of the encapsulated NPs. The encapsulated Fe NPs display magnetic remanence up to room temperature, low coercivity, high chemical stability and no significant anisotropy. Our surface-sensitive measurements combined with the specific morphology of the studied VACNTs allow us to pinpoint the contribution of the surface oxidized or hydroxidized iron catalysts present at the VACNT-substrate interface.

Vertically aligned multiwalled carbon nanotubes for pressure, tactile and vibration sensing.

PubMed

Yilmazoglu, O; Popp, A; Pavlidis, D; Schneider, J J; Garth, D; Schüttler, F; Battenberg, G

2012-03-02

We report a simple method for the micro-nano integration of flexible, vertically aligned multiwalled CNT arrays sandwiched between a top and bottom carbon layer via a porous alumina (Al(2)O(3)) template approach. The electromechanical properties of the flexible CNT arrays have been investigated under mechanical stress conditions. First experiments show highly sensitive piezoresistive sensors with a resistance decrease of up to ∼35% and a spatial resolution of <1 mm. The results indicate that these CNT structures can be utilized for tactile sensing components. They also confirm the feasibility of accessing and utilizing nanoscopic CNT bundles via lithographic processing. The method involves room-temperature processing steps and standard microfabrication techniques.

Controlled transport of latex beads through vertically aligned carbon nanofiber membranes

NASA Astrophysics Data System (ADS)

Zhang, L.; Melechko, A. V.; Merkulov, V. I.; Guillorn, M. A.; Simpson, M. L.; Lowndes, D. H.; Doktycz, M. J.

2002-07-01

Stripes of vertically aligned carbon nanofibers (VACNFs) have been used to form membranes for size selectively controlling the transport of latex beads. Fluidic structures were created in poly(dimethylsiloxane) (PDMS) and interfaced to the VACNF structures for characterization of the membrane pore size. Solutions of fluorescently labeled latex beads were introduced into the PDMS channels and characterized by fluorescence and scanning electron microscopy. Results show that the beads size selectively pass through the nanofiber barriers and the size restriction limit correlates with the interfiber spacing. The results suggest that altering VACNF array density can alter fractionation properties of the membrane. Such membranes may be useful for molecular sorting and for mimicking the properties of natural membranes.

Hybrid nanostructure heterojunction solar cells fabricated using vertically aligned ZnO nanotubes grown on reduced graphene oxide.

PubMed

Yang, Kaikun; Xu, Congkang; Huang, Liwei; Zou, Lianfeng; Wang, Howard

2011-10-07

Using reduced graphene oxide (rGO) films as the transparent conductive coating, inorganic/organic hybrid nanostructure heterojunction photovoltaic devices have been fabricated through hydrothermal synthesis of vertically aligned ZnO nanorods (ZnO-NRs) and nanotubes (ZnO-NTs) on rGO films followed by the spin casting of a poly(3-hexylthiophene) (P3HT) film. The data show that larger interfacial area in ZnO-NT/P3HT composites improves the exciton dissociation and the higher electrode conductance of rGO films helps the power output. This study offers an alternative to manufacturing nanostructure heterojunction solar cells at low temperatures using potentially low cost materials.

Fluorination of vertically aligned carbon nanotubes: from CF4 plasma chemistry to surface functionalization.

PubMed

Struzzi, Claudia; Scardamaglia, Mattia; Colomer, Jean-François; Verdini, Alberto; Floreano, Luca; Snyders, Rony; Bittencourt, Carla

2017-01-01

The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes (vCNT) is correlated to the CF 4 plasma chemical composition. The results obtained via FTIR and mass spectrometry are combined with the XPS and Raman analysis of the sample surface showing the dependence on different plasma parameters (power, time and distance from the plasma region) on the resulting fluorination. Photoemission and absorption spectroscopies are used to investigate the evolution of the electronic properties as a function of the fluorine content at the vCNT surface. The samples suffer a limited ageing effect, with a small loss of fluorine functionalities after two weeks in ambient conditions.

Fluorination of vertically aligned carbon nanotubes: from CF4 plasma chemistry to surface functionalization

PubMed Central

Scardamaglia, Mattia; Colomer, Jean-François; Verdini, Alberto; Floreano, Luca; Snyders, Rony; Bittencourt, Carla

2017-01-01

The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes (vCNT) is correlated to the CF4 plasma chemical composition. The results obtained via FTIR and mass spectrometry are combined with the XPS and Raman analysis of the sample surface showing the dependence on different plasma parameters (power, time and distance from the plasma region) on the resulting fluorination. Photoemission and absorption spectroscopies are used to investigate the evolution of the electronic properties as a function of the fluorine content at the vCNT surface. The samples suffer a limited ageing effect, with a small loss of fluorine functionalities after two weeks in ambient conditions. PMID:28904833

Field emission from in situ-grown vertically aligned SnO2 nanowire arrays

PubMed Central

2012-01-01

Vertically aligned SnO2 nanowire arrays have been in situ fabricated on a silicon substrate via thermal evaporation method in the presence of a Pt catalyst. The field emission properties of the SnO2 nanowire arrays have been investigated. Low turn-on fields of 1.6 to 2.8 V/μm were obtained at anode-cathode separations of 100 to 200 μm. The current density fluctuation was lower than 5% during a 120-min stability test measured at a fixed applied electric field of 5 V/μm. The favorable field-emission performance indicates that the fabricated SnO2 nanowire arrays are promising candidates as field emitters. PMID:22330800

A systematic review of the angular values obtained by computerized photogrammetry in sagittal plane: a proposal for reference values.

PubMed

Krawczky, Bruna; Pacheco, Antonio G; Mainenti, Míriam R M

2014-05-01

Reference values for postural alignment in the coronal plane, as measured by computerized photogrammetry, have been established but not for the sagittal plane. The objective of this study is to propose reference values for angular measurements used for postural analysis in the sagittal plane for healthy adults. Electronic databases (PubMed, BVS, Cochrane, Scielo, and Science Direct) were searched using the following key words: evaluation, posture, photogrammetry, and software. Articles published between 2006 and 2012 that used the PAS/SAPO (postural assessment software) were selected. Another inclusion criterion was the presentation of, at least, one of the following measurements: head horizontal alignment, pelvic horizontal alignment, hip angle, vertical alignment of the body, thoracic kyphosis, and lumbar lordosis. Angle samples of the selected articles were grouped 2 by 2 in relation to an overall average, which made possible total average, variance, and SD calculations. Six articles were included, and the following average angular values were found: 51.42° ± 4.87° (head horizontal alignment), -12.26° ± 5.81° (pelvic horizontal alignment), -6.40° ± 3.86° (hip angle), and 1.73° ± 0.94° (vertical alignment of the body). None of the articles contained the measurements for thoracic kyphosis and lumbar lordosis. The reference values can be adopted as reference for postural assessment in future researches if the same anatomical points are considered. Copyright © 2014 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

Simulation of exposure and alignment for nanoimprint lithography

NASA Astrophysics Data System (ADS)

Deng, Yunfei; Neureuther, Andrew R.

2002-07-01

Rigorous electromagnetic simulation with TEMPEST is used to examine the exposure and alignment processes for nano-imprint lithography with attenuating thin-film molds. Parameters in the design of topographical features of the nano-imprint system and material choices of the components are analyzed. The small feature size limits light transmission through the feature. While little can be done with auxiliary structures to attract light into small holes, the use of an absorbing material with a low real part of the refractive index such as silver helps mitigates the problem. Results on complementary alignment marks shows that the small transmission through the metal layer and the vertical separation of two alignment marks create the leakage equivalent to 1 nm misalignment but satisfactory alignment can be obtained by measuring alignment signals over a +/- 30 nm range.

Effectiveness of sonography assisted minimal invasive plate osteosynthesis (MIPO) compare with fluoroscope assisted in femoral shaft fracture: A cadaveric study.

PubMed

Saengsin, Jirawat; Vaseenon, Tanawat; Pattamapaspong, Nuttaya; Kritsaneephaiboon, Apipop

2017-08-01

A minimal invasive plate osteosynthesis (MIPO) has an advantage of biological soft tissue preservation that consists of preserving bony blood supply, fracture hematoma and less soft tissue damage which leads to decreasing of infection rate and rapid bone healing. However, the radiation exposure is still a disadvantage of this technique. A sonography that provides dynamic real time imaging may be used as an alternative technique for assisting MIPO. The aim of this study was to compare the effectiveness of MIPO in femoral shaft fracture between the sonography assisted and the fluoroscopy assisted. Twenty-eight cadaveric limbs were subjected to create femoral shaft fracture. Then, sonography assisted reduction with temporary external fixation and MIPO were performed. Images of the sonography and the fluoroscopy were recorded including before reduction, after reduction and after MIPO in order to identify fracture displacements in anteroposterior and mediolateral directions. Moreover, the anterior and posterior distances from edge of the bone to the plate were measured to confirm plate position. The effectiveness of this technique was defined as the proper plate position and acceptable alignment after fixation. All distances from the sonography and the fluoroscopy were also analyzed and compared using Pearson correlation and Bland-Altman method to assess the agreements between two tests. All of the subjects were met the criteria for acceptable alignment. We found only three femoral shaft fracture (11%) operated with MIPO by sonography assisted that showed slipped plate off femoral bones. According to Pearson correlation, there were good to excellent agreements in term of measuring fracture displacement before (Pearson Correlation >0.7) and after reduction (Pearson Correlation >0.7) between these two tests. There was moderate agreement regarding to evaluation of plate position (Pearson Correlation 03.-0.7). When we compared two methods of measurement using Bland-Altman plot, there were no statistical significant difference (P<0.05). Images from the sonography could provide visualization of the fracture during reduction and MIPO as accurately as the radiography. Thus, the sonography assisted MIPO in femoral shaft fracture can be done effectively comparing with radiographic assisted. Copyright © 2017 Elsevier Ltd. All rights reserved.

Complications in the Treatment of Adolescent Clavicle Fractures

PubMed Central

Luo, T. David; Ashraf, Ali; Larson, A. Noelle; Stans, Anthony A.; Shaughnessy, William J.; McIntosh, Amy L.

2015-01-01

The authors’ study evaluates the complications associated with the treatment of clavicle fractures in adolescents. During the study period, 153 clavicle fractures occurred in patients between the ages of 14 and 17 years who were treated at the authors’ center, of which 23 (15.0%) were treated surgically. Compared to the fractures treated nonoperatively, the surgical fractures had greater shortening (mean, 2.0 vs 0.9 cm; P<.001) and were more likely to be comminuted (65.2% vs 23.1%; P<.001). Complications occurred in 21.7% of fractures treated surgically. One delayed union occurred in the nonoperative cohort, but no other complications or patients who required clavicular osteotomy for malunion. Pediatric fellowship-trained orthopedic surgeons treated 78 displaced fractures, resulting in 8 (10.3%) surgeries. Nonpediatric orthopedic specialists treated 46 displaced fractures, 15 (32.6%) of which were treated operatively (P=.0035). FigureA 15-year-old boy sustained a comminuted clavicle fracture from playing football. Preoperative radiograph showing significant clavicle shortening and a vertical fragment. PMID:25901621

An integrated geophysical and hydraulic investigation to characterize a fractured-rock aquifer, Norwalk, Connecticut

USGS Publications Warehouse

Lane, J.W.; Williams, J.H.; Johnson, C.D.; Savino, D.M.; Haeni, F.P.

2002-01-01

The U.S. Geological Survey conducted an integrated geophysical and hydraulic investigation at the Norden Systems, Inc. site in Norwalk, Connecticut, where chlorinated solvents have contaminated a fractured-rock aquifer. Borehole, borehole-to-borehole, surface-geophysical, and hydraulic methods were used to characterize the site bedrock lithology and structure, fractures, and transmissive zone hydraulic properties. The geophysical and hydraulic methods included conventional logs, borehole imagery, borehole radar, flowmeter under ambient and stressed hydraulic conditions, and azimuthal square-array direct-current resistivity soundings. Integrated interpretation of geophysical logs at borehole and borehole-to-borehole scales indicates that the bedrock foliation strikes northwest and dips northeast, and strikes north-northeast to northeast and dips both southeast and northwest. Although steeply dipping fractures that cross-cut foliation are observed, most fractures are parallel or sub-parallel to foliation. Steeply dipping reflectors observed in the radar reflection data from three boreholes near the main building delineate a north-northeast trending feature interpreted as a fracture zone. Results of radar tomography conducted close to a suspected contaminant source area indicate that a zone of low electromagnetic (EM) velocity and high EM attenuation is present above 50 ft in depth - the region containing the highest density of fractures. Flowmeter logging was used to estimate hydraulic properties in the boreholes. Thirty-three transmissive fracture zones were identified in 11 of the boreholes. The vertical separation between transmissive zones typically is 10 to 20 ft. Open-hole and discrete-zone transmissivity was estimated from heat-pulse flowmeter data acquired under ambient and stressed conditions. The open-hole transmissivity ranges from 2 to 86 ft2/d. The estimated transmissivity of individual transmissive zones ranges from 0.4 to 68 ft2/d. Drawdown monitoring in nearby boreholes under pumping conditions identified hydraulic connections along a northeast-southwest trend between boreholes as far as 560 ft apart. The vertical distribution of fractures can be described by power law functions, which suggest that the fracture network contains transmissive zones consisting of closely spaced fractures surrounded by a less fractured and much less permeable rock mass.

Passive characterization of hydrofracture properties using signals from hydraulic pumps

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

Rector III, J.W.; Dong, Q.; Patzek, T.W.

1999-01-02

Massive hydraulic fracturing is used to enhance production from the low-permeability diatomite fields of Kern County, CA. Although critical for designing injection and recovery well patterns, the in-situ hydraulic fracture geometry is poorly understood. In 1990, Shell conducted an extensive seismic monitoring experiment on several hydrofractures prior to a steam drive pilot to characterize hydrofracture geometry. The seismic data were recorded by cemented downhole geophone arrays in three observation holes (MO-1, MO-2, and MO-3) located near the hydraulic fracture treatment wells. Using lowpass filtering and moveout analysis, events in the geophone recordings are identified as conical shear waves radiating frommore » tube waves traveling down the treatment well. These events appear to be created by the hydraulic pumps, since their amplitudes are correlated with the injection rate and the wellhead pressure. Conical wave amplitudes are related to the tube wave attenuation in the treatment well and to wave-propagation characteristics of the shear component traveling in the earth. During the main fracturing stage, geophones above the fracture zone for wells MO-1 and MO-2 (both roughly along the inferred vertical fracture plane) exhibited conical-wave amplitude increases that are caused by shear wave reflection/scattering off the top of a fracture zone. From changes in the reflection amplitude as a function of depth, we interpret that the fracture zone initially extends along a confined vertical plane at a depth that correlates with many of the microseismic events. Toward the end of the main fracturing stage, the fracture zone extends upward and also extends in width, although we cannot determine the dimensions of the fracture from the reflection amplitudes alone. For all wells, we observe that the reflection (and what we infer to be the initial fracture) begins during a time period where no marked change in fracture pressure or injection rate or slurry concentration is observed. As the main fracturing stage progressed, we observed a significant decrease in amplitude for geophones below the top of the fracture zone. The attenuation was most pronounced for wells MO-1 and MO-2 (along the fracture plane). However, near the end of the main stage, well MO-3 also exhibited a significant amplitude decrease, suggesting the development of a fractured ''process zone'' around the main fracture plane. In addition, well MO-3 also exhibited an amplitude decrease in an interval well below the initial fracture zone. Both the interval and the direction (toward MO-3) correspond with temperature log increases observed during later steam injection.« less

Method for in situ combustion

DOEpatents

Pasini, III, Joseph; Shuck, Lowell Z.; Overbey, Jr., William K.

1977-01-01

This invention relates to an improved in situ combustion method for the recovery of hydrocarbons from subterranean earth formations containing carbonaceous material. The method is practiced by penetrating the subterranean earth formation with a borehole projecting into the coal bed along a horizontal plane and extending along a plane disposed perpendicular to the plane of maximum permeability. The subterranean earth formation is also penetrated with a plurality of spaced-apart vertical boreholes disposed along a plane spaced from and generally parallel to that of the horizontal borehole. Fractures are then induced at each of the vertical boreholes which project from the vertical boreholes along the plane of maximum permeability and intersect the horizontal borehole. The combustion is initiated at the horizontal borehole and the products of combustion and fluids displaced from the earth formation by the combustion are removed from the subterranean earth formation via the vertical boreholes. Each of the vertical boreholes are, in turn, provided with suitable flow controls for regulating the flow of fluid from the combustion zone and the earth formation so as to control the configuration and rate of propagation of the combustion zone. The fractures provide a positive communication with the combustion zone so as to facilitate the removal of the products resulting from the combustion of the carbonaceous material.

Surface Fractal Analysis for Estimating the Fracture Energy Absorption of Nanoparticle Reinforced Composites

PubMed Central

Pramanik, Brahmananda; Tadepalli, Tezeswi; Mantena, P. Raju

2012-01-01

In this study, the fractal dimensions of failure surfaces of vinyl ester based nanocomposites are estimated using two classical methods, Vertical Section Method (VSM) and Slit Island Method (SIM), based on the processing of 3D digital microscopic images. Self-affine fractal geometry has been observed in the experimentally obtained failure surfaces of graphite platelet reinforced nanocomposites subjected to quasi-static uniaxial tensile and low velocity punch-shear loading. Fracture energy and fracture toughness are estimated analytically from the surface fractal dimensionality. Sensitivity studies show an exponential dependency of fracture energy and fracture toughness on the fractal dimensionality. Contribution of fracture energy to the total energy absorption of these nanoparticle reinforced composites is demonstrated. For the graphite platelet reinforced nanocomposites investigated, surface fractal analysis has depicted the probable ductile or brittle fracture propagation mechanism, depending upon the rate of loading. PMID:28817017

Hydraulic fracture height limits and fault interactions in tight oil and gas formations

NASA Astrophysics Data System (ADS)

Flewelling, Samuel A.; Tymchak, Matthew P.; Warpinski, Norm

2013-07-01

widespread use of hydraulic fracturing (HF) has raised concerns about potential upward migration of HF fluid and brine via induced fractures and faults. We developed a relationship that predicts maximum fracture height as a function of HF fluid volume. These predictions generally bound the vertical extent of microseismicity from over 12,000 HF stimulations across North America. All microseismic events were less than 600 m above well perforations, although most were much closer. Areas of shear displacement (including faults) estimated from microseismic data were comparatively small (radii on the order of 10 m or less). These findings suggest that fracture heights are limited by HF fluid volume regardless of whether the fluid interacts with faults. Direct hydraulic communication between tight formations and shallow groundwater via induced fractures and faults is not a realistic expectation based on the limitations on fracture height growth and potential fault slip.

High-Performance Flexible All-Solid-State Asymmetric Supercapacitors Based on Vertically Aligned CuSe@Co(OH) 2 Nanosheet Arrays

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

Gong, Jiangfeng; Tian, Yazhou; Yang, Ziyuan

The developments of electrode active materials provide the opportunities for next-generation energy storage devices. The arrangement of electrode materials on the substrate has recently emerged as a promising strategy for preparing high-performance supercapacitors. In this paper, we demonstrate a novel vertically aligned CuSe@Co(OH) 2 nanosheet arrays electrode for supercapacitor application. The materials are thoroughly characterized by structural and spectroscopic techniques. Electrochemical performance of CuSe@Co(OH) 2 nanosheet arrays are investigated in detail, which exhibit a specific capacitance as much as 1180 F g -1 at a current density of 1 A g -1. A flexible asymmetric all-solid-state supercapacitor is fabricated usingmore » CuSe@Co(OH) 2 nanosheet arrays as the positive electrode and activated carbon as the negative electrode. The device delivers a volumetric capacitance of 441.4 mF cm -3 with maximum energy density and maximum power density is 0.17 and 62.1 mW cm -3, as well as robust cycling stability (~80.4% capacitance retention after 10 000 cycles), excellent flexibility, and mechanical stability. Finally, the excellent electrochemical performance can be attributed to its unique vertically aligned configuration.« less

High-Performance Flexible All-Solid-State Asymmetric Supercapacitors Based on Vertically Aligned CuSe@Co(OH) 2 Nanosheet Arrays

DOE PAGES

Gong, Jiangfeng; Tian, Yazhou; Yang, Ziyuan; ...

2018-01-04

The developments of electrode active materials provide the opportunities for next-generation energy storage devices. The arrangement of electrode materials on the substrate has recently emerged as a promising strategy for preparing high-performance supercapacitors. In this paper, we demonstrate a novel vertically aligned CuSe@Co(OH) 2 nanosheet arrays electrode for supercapacitor application. The materials are thoroughly characterized by structural and spectroscopic techniques. Electrochemical performance of CuSe@Co(OH) 2 nanosheet arrays are investigated in detail, which exhibit a specific capacitance as much as 1180 F g -1 at a current density of 1 A g -1. A flexible asymmetric all-solid-state supercapacitor is fabricated usingmore » CuSe@Co(OH) 2 nanosheet arrays as the positive electrode and activated carbon as the negative electrode. The device delivers a volumetric capacitance of 441.4 mF cm -3 with maximum energy density and maximum power density is 0.17 and 62.1 mW cm -3, as well as robust cycling stability (~80.4% capacitance retention after 10 000 cycles), excellent flexibility, and mechanical stability. Finally, the excellent electrochemical performance can be attributed to its unique vertically aligned configuration.« less

Kinematics and Kinetics of Squats, Drop Jumps and Imitation Jumps of Ski Jumpers.

PubMed

Pauli, Carole A; Keller, Melanie; Ammann, Fabian; Hübner, Klaus; Lindorfer, Julia; Taylor, William R; Lorenzetti, Silvio

2016-03-01

Squats, drop jumps, and imitation jumps are commonly used training exercises in ski jumping to enhance maximum force, explosive force, and sport-specific skills. The purpose of this study was to evaluate the kinetics and kinematics of training exercises in ski jumping and to find objective parameters in training exercises that most correlate with the competition performance of ski jumpers. To this end, barbell squats, drop jumps, and imitation jumps were measured in a laboratory environment for 10 elite ski jumpers. Force and motion data were captured, and the influence of maximum vertical force, force difference, vertical take-off velocity, knee moments, knee joint power, and a knee valgus/varus index was evaluated and correlated with their season jump performance. The results indicate that, especially for the imitation jumps, a good correlation exists between the vertical take-off velocity and the personal jump performance on the hill (R = 0.718). Importantly, however, the more the athletes tended toward a valgus knee alignment during the measured movements, the worse their performance (R = 0.729 imitation jumps; R = 0.685 squats). Although an evaluation of the athletes' lower limb alignment during competitive jumping on the hill is still required, these preliminary data suggest that performance training should additionally concentrate on improving knee alignment to increase ski jumping performance.

The Surface Interface Characteristics of Vertically Aligned Carbon Nanotube and Graphitic Carbon Fiber Arrays Grown by Thermal and Plasma Enhanced Chemical Vapor Deposition

NASA Technical Reports Server (NTRS)

Delzeit, Lance; Nguyen, Cattien; Li, Jun; Han, Jie; Meyyappan, M.

2002-01-01

The development of nano-arrays for sensors and devices requires the growth of arrays with the proper characteristics. One such application is the growth of vertically aligned carbon nanotubes (CNTs) and graphitic carbon fibers (GCFs) for the chemical attachment of probe molecules. The effectiveness of such an array is dependent not only upon the effectiveness of the probe and the interface between that probe and the array, but also the array and the underlaying substrate. If that array is a growth of vertically aligned CNTs or GCFs then the attachment of that array to the surface is of the utmost importance. This attachment provides the mechanical stability and durability of the array, as well as, the electrical properties of that array. If the detection is to be acquired through an electrical measurement, then the appropriate resistance between the array and the surface need to be fabricated into the device. I will present data on CNTs and GCFs grown from both thermal and plasma enhanced chemical vapor deposition. The focus will be on the characteristics of the metal film from which the CNTs and GCFs are grown and the changes that occur due to changes within the growth process.

Uncovering and Validating Toughening Mechanisms in High Performance Composites

DTIC Science & Technology

2015-09-17

striated regions have similar microstructures (see Figure 44). This aligned, fiber-reinforced design of the striated region has been adapted from spearing...Page 79 / 84 “Fracture mitigation strategies in gastropod shells,” C. Salinas and D. Kisailus, Journal of Materials, 65 (4) (2013) 473-480. DOI...2014.03.022 “Fracture mitigation strategies in gastropod shells,” C. Salinas and D. Kisailus, Journal of Materials, 65 (4) (2013) 473-480. DOI: J10.1007

[Revision of Schatzker type Ⅵ tibial plateau fracture failure focus on the recovery of lower limb alignment].

PubMed

Cong, R J; Liu, J F; Jiang, Y; Dilixiati, Duolikun; Hou, X D; Zheng, L P

2018-03-01

Objective: To explore the influence of the lower extremity abnormal alignment and the joint surface, and to explore the surgical skills. Methods: Twenty-two cases of tibial plateau Schatzker Ⅵ fracture internal fixation failure revision from January 2012 to January 2017 in Department of Orthopedics, Shanghai 10(th) Hospital.One year follow-up after initial surgery to make sure of failure.Three-dimensional CT scan, radiography, infection index, gait analysis, knee joint ROM, femur tibia angle, tibial plateau tibial shaft angle and posterior slope if tibial plateau were observed. The medial approach and bi-planer osteotoma were used.Autogenous iliac bone graft, postoperative fast recovery channel were used.Follow-up point included preoperative and postoperative 7 days, 6 weeks, 3 months, and 6 months.Obvervational index included double lower limbs radiography, knee society score(KSS), complications such as infection, skin necrosis, joint main passive activity, double lower limbs alignment the last follow-up SF-36 scale.Rate was compared by χ(2) test, measurement data using paired sample t test.Correlation was analyzed by Pearson correlation regression testing. Results: Twenty-two patients received follow-up.KSS, more than 21 cases were benign, with good gait.One case was poor, with claudication gait.Not skin necrosis, no deep infection cases, 1 case get blisters 2 days postoperatively, and disappear after 5 days with detumescence and cold therapy.Whether restoring force line affect the KSS significantly(χ(2)=22.000, P =0.000). Knee joint ROM, SF-36 score, KSS and lower limb alignment were improved significantly. In different individual the articular surface and anatomical angle recovered greatly but the posterior slope angle was quite difference which has no correlation with KSS and SF-36 scale( P >0.01). Conclusions: Revision of Schatzker type Ⅵ tibial plateau fracture failure should focus on the recovery of lower limb alignment.moderate overcorrect bone cutting and joint surface height can bring benefits to the postoperative knee function.Revision surgery patients have greater psychological pressure, more early psychological intervention is necessary.

[Forensic Analysis of the Characteristics of Pelvic Fracture in 65 Road Traffic Accident Death Cases].

PubMed

Zhang, W

2016-12-01

To analyze the characteristics and mechanisms of pelvic fractures in the cases of road traffic accident deaths. Total 65 cases of road traffic accident deaths with pelvic fracture were collected, and the sites, characteristics and injury mechanisms of pelvic fracture were statistically analyzed. Among the 65 cases of pelvic fracture, 38 cases of dislocation of sacroiliac joint were found, and most combined with pubis symphysis separation or fracture of pubis. In the fractures of pubis, ischium and acetabulum, linear fractures were most common, while comminuted fractures were most common in sacrum and coccyx fractures. There were 54 cases combined with pelvic soft tissue injury, and 8 cases with pelvic organ injury and 44 cases with abdominal organ injury. In the types of pelvic ring injury, 32 cases were separation, 49.32%, followed by compression, 26.15% and only one case was verticality, 1.54%. Detailed and comprehensive examination of the body and determination of the pelvic fracture type contribute to analyze the mechanisms of injury. Copyright© by the Editorial Department of Journal of Forensic Medicine

Composite materials: Fatigue and fracture. Vol. 3

NASA Technical Reports Server (NTRS)

O'Brien, T. K. (Editor)

1991-01-01

The present volume discusses topics in the fields of matrix cracking and delamination, interlaminar fracture toughness, delamination analysis, strength and impact characteristics, and fatigue and fracture behavior. Attention is given to cooling rate effects in carbon-reinforced PEEK, the effect of porosity on flange-web corner strength, mode II delamination in toughened composites, the combined effect of matrix cracking and free edge delamination, and a 3D stress analysis of plain weave composites. Also discussed are the compression behavior of composites, damage-based notched-strength modeling, fatigue failure processes in aligned carbon-epoxy laminates, and the thermomechanical fatigue of a quasi-isotropic metal-matrix composite.

Structural signature of a brittle-to-ductile transition in self-assembled networks.

PubMed

Ramos, Laurence; Laperrousaz, Arnaud; Dieudonné, Philippe; Ligoure, Christian

2011-09-30

We study the nonlinear rheology of a novel class of transient networks, made of surfactant micelles of tunable morphology reversibly linked by block copolymers. We couple rheology and time-resolved structural measurements, using synchrotron radiation, to characterize the highly nonlinear viscoelastic regime. We propose the fluctuations of the degree of alignment of the micelles under shear as a probe to identify a fracture process. We show a clear signature of a brittle-to-ductile transition in transient gels, as the morphology of the micelles varies, and provide a parallel between the fracture of solids and the fracture under shear of viscoelastic fluids.

A demographic analysis of vertical root fractures.

PubMed

Cohen, Stephen; Berman, Louis H; Blanco, Lucia; Bakland, Leif; Kim, Jay S

2006-12-01

Teeth with vertical root fractures (VRFs) have complete or incomplete fractures that extends through the enamel, dentin and pulp, down the long axis of the tooth. Several different variables were investigated and statistically evaluated as to their correlation with the presence of VRFs. Specifically analyzed were gender, tooth location, age, radiographic and clinical findings, bruxism, and pulpal status. The data were collected from three different endodontists, from three different geographic locations, comprising a total of 227 teeth. Although VRFs may occur in conjunction with any of the parameters investigated, only certain factors were found to occur in a significant number of cases. The results indicate that VRFs are statistically more prevalent in mandibular molars and maxillary premolars. They are associated with periradicular bone loss, pain to percussion, extensive restorations, and seem to occur more often in females and older patients. However, VRFs are not necessarily related to periapical bone loss, a widening of the periodontal ligament space, associated periodontal pockets, a sinus tract, particular pulpal status, or bruxism.

Evaluation of borehole geophysical and video logs, at Butz Landfill Superfund Site, Jackson Township, Monroe County, Pennsylvania

USGS Publications Warehouse

Low, Dennis J.; Conger, Randall W.

2001-01-01

Between February 1996 and November 2000, geophysical logging was conducted in 27 open borehole wells in and adjacent to the Butz Landfill Superfund Site, Jackson Township, Monroe County, Pa., to determine casing depth and depths of water-producing zones, water-receiving zones, and zones of vertical borehole flow. The wells range in depth from 57 to 319 feet below land surface. The geophysical logging determined the placement of well screens and packers, which allow monitoring and sampling of water-bearing zones in the fractured bedrock so that the horizontal and vertical distribution of contaminated ground water migrating from known sources could be determined. Geophysical logging included collection of caliper, natural-gamma, single-point-resistance, fluid-resistivity, fluid-temperature, and video logs. Caliper and video logs were used to locate fractures, joints, and weathered zones. Inflections on single-point-resistance, fluid-temperature, and fluid-resistivity logs indicated possible water-bearing fractures, and heatpulse-flowmeter measurements verified these locations. Natural-gamma logs provided information on stratigraphy.

Female urethral injuries associated with pelvic fracture: a systematic review of the literature.

PubMed

Patel, Devin N; Fok, Cynthia S; Webster, George D; Anger, Jennifer T

2017-12-01

To review systematically the literature on female urethral injuries associated with pelvic fracture and to determine the optimum management of this rare injury. Using Meta-analysis of Observational Studies in Epidemiology criteria, we searched the Cochrane, Pubmed and OVID databases for all articles available before 30 June 2016 using the terms 'female pelvic fracture urethroplasty', 'female urethral distraction', 'female pelvic fracture urethral injury' and 'female pelvic fracture urethra girls.' Two authors of this paper independently reviewed the titles, abstracts, and articles in duplicate. We identified 162 individual articles from the databases. Fifty-one articles met our criteria for full review, including 158 female patients with urethral trauma. Of these injuries, 83 (53%) were managed with immediate repair; 17/83 (20%) via primary alignment and 66/83 (80%) via anastomotic repair. The remaining 75/158 (47%) were managed with delayed repair. Rates of urethral stenosis and fistula were highest after primary alignment. Urethral integrity appears to be similar after both primary anastomosis and delayed repair; however, patients experienced significantly more incontinence and vaginal stenosis after delayed repair. Patients who underwent delayed urethral repair were more likely to undergo more extensive reconstructive surgery than those who underwent primary repair. The optimum management of female urethral distraction defects is based on very-low-quality literature. Based on our review of the available literature, primary anastomotic repair of a female urethral distraction defect via a vaginal approach as soon as the patient is haemodynamically stable appears to be optimal. © 2017 The Authors BJU International © 2017 BJU International Published by John Wiley & Sons Ltd.

Boattail Plates With Non-Rectangular Geometries For Reducing Aerodynamic Base Drag Of A Bluff Body In Ground Effect

DOEpatents

Ortega, Jason M.; Sabari, Kambiz

2006-03-07

An apparatus for reducing the aerodynamic base drag of a bluff body having a leading end, a trailing end, a top surface, opposing left and right side surfaces, and a base surface at the trailing end substantially normal to a longitudinal centerline of the bluff body, with the base surface joined (1) to the left side surface at a left trailing edge, (2) to the right side surface at a right trailing edge, and (3) to the top surface at a top trailing edge. The apparatus includes left and right vertical boattail plates which are orthogonally attached to the base surface of the bluff body and inwardly offset from the left and right trailing edges, respectively. This produces left and right vertical channels which generate, in a flowstream substantially parallel to the longitudinal centerline, respective left and right vertically-aligned vortical structures, with the left and right vertical boattail plates each having a plate width defined by a rear edge of the plate spaced from the base surface. Each plate also has a peak plate width at a location between top and bottom ends of the plate corresponding to a peak vortex of the respective vertically-aligned vortical structures.

An automatic alignment system for measuring optical path of transmissometer based on light beam scanning

NASA Astrophysics Data System (ADS)

Zhou, Shudao; Ma, Zhongliang; Wang, Min; Peng, Shuling

2018-05-01

This paper proposes a novel alignment system based on the measurement of optical path using a light beam scanning mode in a transmissometer. The system controls both the probe beam and the receiving field of view while scanning in two vertical directions. The system then calculates the azimuth angle of the transmitter and the receiver to determine the precise alignment of the optical path. Experiments show that this method can determine the alignment angles in less than 10 min with errors smaller than 66 μrad in the azimuth. This system also features high collimation precision, process automation and simple installation.

Density controlled carbon nanotube array electrodes

DOEpatents

Ren, Zhifeng F [Newton, MA; Tu, Yi [Belmont, MA

2008-12-16

CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.

Vertically aligned carbon nanotube electrodes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Welna, Daniel T.; Qu, Liangti; Taylor, Barney E.; Dai, Liming; Durstock, Michael F.

As portable electronics become more advanced and alternative energy demands become more prevalent, the development of advanced energy storage technologies is becoming ever more critical in today's society. In order to develop higher power and energy density batteries, innovative electrode materials that provide increased storage capacity, greater rate capabilities, and good cyclability must be developed. Nanostructured materials are gaining increased attention because of their potential to mitigate current electrode limitations. Here we report on the use of vertically aligned multi-walled carbon nanotubes (VA-MWNTs) as the active electrode material in lithium-ion batteries. At low specific currents, these VA-MWNTs have shown high reversible specific capacities (up to 782 mAh g -1 at 57 mA g -1). This value is twice that of the theoretical maximum for graphite and ten times more than their non-aligned equivalent. Interestingly, at very high discharge rates, the VA-MWNT electrodes retain a moderate specific capacity due to their aligned nature (166 mAh g -1 at 26 A g -1). These results suggest that VA-MWNTs are good candidates for lithium-ion battery electrodes which require high rate capability and capacity.

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

Chen, Yu; Gao, Kai; Huang, Lianjie

Accurate imaging and characterization of fracture zones is crucial for geothermal energy exploration. Aligned fractures within fracture zones behave as anisotropic media for seismic-wave propagation. The anisotropic properties in fracture zones introduce extra difficulties for seismic imaging and waveform inversion. We have recently developed a new anisotropic elastic-waveform inversion method using a modified total-variation regularization scheme and a wave-energy-base preconditioning technique. Our new inversion method uses the parameterization of elasticity constants to describe anisotropic media, and hence it can properly handle arbitrary anisotropy. We apply our new inversion method to a seismic velocity model along a 2D-line seismic data acquiredmore » at Eleven-Mile Canyon located at the Southern Dixie Valley in Nevada for geothermal energy exploration. Our inversion results show that anisotropic elastic-waveform inversion has potential to reconstruct subsurface anisotropic elastic parameters for imaging and characterization of fracture zones.« less

In-flight angular alignment of inertial navigation systems by means of radio aids

NASA Technical Reports Server (NTRS)

Tanner, W.

1972-01-01

The principles involved in the angular alignment of the inertial reference by nondirectional data from radio aids are developed and compared with conventional methods of alignment such as gyro-compassing and pendulous vertical determination. The specific problem is considered of the space shuttle reentry and a proposed technique for the alignment of the inertial reference system some time before landing. A description is given of the digital simulation of a transponder interrogation system and of its interaction with the inertial navigation system. Data from reentry simulations are used to demonstrate the effectiveness of in-flight inertial system alignment. Concluding remarks refer to other potential applications such as space shuttle orbit insertion and air navigation of conventional aircraft.

Igneous sills record far-field and near-field stress interactions during volcano construction: Isle of Mull, Scotland

NASA Astrophysics Data System (ADS)

Stephens, T. L.; Walker, R. J.; Healy, D.; Bubeck, A.; England, R. W.; McCaffrey, K. J. W.

2017-11-01

Sill emplacement is typically associated with horizontally mechanically layered host rocks in a near-hydrostatic far-field stress state, where contrasting mechanical properties across the layers promote transitions from dykes, or inclined sheets, to sills. We used detailed field observations from the Loch Scridain Sill Complex (Isle of Mull, UK), and mechanical models to show that layering is not always the dominant control on sill emplacement. The studied sills have consistently shallow dips (1°-25°) and cut vertically bedded and foliated metamorphic basement rocks, and horizontally bedded cover sedimentary rocks and lavas. Horizontal and shallowly-dipping fractures in the host rock were intruded with vertical opening in all cases, whilst steeply-dipping discontinuities within the sequence (i.e. vertical fractures and foliation in the basement, and vertical polygonal joints in the lavas) were not intruded during sill emplacement. Mechanical models of slip tendency, dilation tendency, and fracture susceptibility for local and overall sill geometry data, support a radial horizontal compression during sill emplacement. Our models show that dykes and sills across Mull were emplaced during NW-SE horizontal shortening, related to a far-field tectonic stress state. The dykes generally accommodated phases of NE-SW horizontal tectonic extension, whereas the sills record the superposition of the far-field stress with a near-field stress state, imposed by emplacement of the Mull Central Volcano. We show that through detailed geometric characterisation coupled with mechanical modelling, sills may be used as an indication of fluctuations in the paleostress state.

Geophysical characterization of an active hydrothermal shear zone in granitic rocks

NASA Astrophysics Data System (ADS)

Zahner, Tobias; Baron, Ludovic; Holliger, Klaus; Egli, Daniel

2016-04-01

Hydrothermally active faults and shear zones in the crystalline massifs of the central Alps are currently of particular interest because of their potential similarities and analogies with planned deep petrothermal reservoirs in the Alpine foreland. In order to better understand such hydrothermal systems, a near-vertical, hydrothermally active shear zone embedded in low-permeability granitic rocks has been drilled. This borehole is located on the Grimsel Pass in the central Swiss Alps, has an inclination of 24 degrees with regard to the vertical, and crosses the targeted shear zone between about 82 and 86 meters depth. The borehole has been fully cored and a comprehensive suite of geophysical logging data has been acquired. The latter comprises multi-frequency sonic, ground-penetrating radar, resistivity, self-potential, gamma-gamma, neutron-neutron, optical televiewer, and caliper log data. In addition to this, we have also performed a surface-to-borehole vertical seismic profiling experiment. The televiewer data and the retrieved core samples show a marked increase of the fracture density in the target region, which also finds its expression in rather pronounced and distinct signatures in all other log data. Preliminary results point towards a close correspondence between the ground-penetrating radar and the neutron-neutron log data, which opens the perspective of constraining the effective fracture porosity at vastly differing scales. There is also remarkably good agreement between the sonic log and the vertical seismic profiling data, which may allow for assessing the permeability of the probed fracture network by interpreting these data in a poroelastic context.

Cavitation-based hydro-fracturing technique for geothermal reservoir stimulation

DOEpatents

Wang, Jy-An John; Wang, Hong; Ren, Fei; Cox, Thomas S.

2017-02-21

A rotary shutter valve 500 is used for geothermal reservoir stimulation. The valve 500 includes a pressure chamber 520 for holding a working fluid (F) under pressure. A rotatable shutter 532 is turned with a powering device 544 to periodically align one or more windows 534 with one or more apertures 526 in a bulkhead 524. When aligned, the pressurized working fluid (F) flows through the bulkhead 524 and enters a pulse cavity 522, where it is discharged from the pulse cavity 522 as pressure waves 200. The pressure wave propagation 200 and eventual collapse of the bubbles 202 can be transmitted to a target rock surface 204 either in the form of a shock wave 206, or by micro jets 208, depending on the bubble-surface distance. Once cavitation at the rock face begins, fractures are initiated in the rock to create a network of micro-fissures for enhanced heat transfer.

Growth mechanism and optical properties of aligned hexagonal ZnO nanoprisms synthesized by noncatalytic thermal evaporation.

PubMed

Umar, Ahmad; Karunagaran, B; Kim, S H; Suh, E-K; Hahn, Y B

2008-05-19

Vertically aligned perfectly hexagonal-shaped ZnO nanoprisms have been grown on a Si(100) substrate via a noncatalytic thermal evaporation process by using metallic zinc powder in the presence of oxygen gas. The as-grown nanoprisms consist of ultra smooth Zn-terminated (0001) facets bounded with the {0110} surfaces. The as-synthesized products are single-crystalline with the wurtzite hexagonal phase and grown along the [0001] direction, as confirmed from the detailed structural investigations. The presence of a sharp and strong nonpolar optical phonon high-E2 mode at 437 cm(-1) in the Raman scattering spectrum further confirms good crystallinity and wurtzite hexagonal phase for the as-grown products. The as-grown nanoprisms exhibit a strong near-band-edge emission with a very weak deep-level emission in the room-temperature and low-temperature photoluminescence measurements, confirming good optical properties for the deposited products. Moreover, systematic time-dependent experiments were also performed to determine the growth process of the grown vertically aligned nanoprisms.

Vertically aligned carbon nanotubes as cytocompatible material for enhanced adhesion and proliferation of osteoblast-like cells.

PubMed

Giannona, Suna; Firkowska, Izabela; Rojas-Chapana, José; Giersig, Michael

2007-01-01

In this study, we describe the spatial organization of CAL-72 osteoblast-like cells on arrays of vertically aligned multi-walled carbon nanotubes (VACNTs). It was observed that, unlike cell growth on non-patterned surfaces, the cell attachment and spreading process on VACNTs was significantly enhanced. Additionally, since carbon nanotubes are known to possess resilient mechanical properties and are chemically stable, the effect of periodic arrays of VACNTs on CAL-72 osteoblast-like cells was also studied. The periodicity and alignment of VACNTs considerably influenced growth, shape and orientation of the cells by steering toward the nanopattern. This situation is of great interest for the potential application of VACNTs in bone bioenginnering. This data provides evidence that CAL-72 osteoblast-like cells can sense physical features at the nanoscale. These results give a fascinating insight into the ways in which cell growth can be influenced by man-made nanostructures and could provide a framework for achieving controlled cell guidance with controlled organization and special physical properties.

Multilevel, multicomponent microarchitectures of vertically-aligned carbon nanotubes for diverse applications.

PubMed

Qu, Liangti; Vaia, Rich A; Dai, Liming

2011-02-22

A simple multiple contact transfer technique has been developed for controllable fabrication of multilevel, multicomponent microarchitectures of vertically aligned carbon nanotubes (VA-CNTs). Three dimensional (3-D) multicomponent micropatterns of aligned single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs) have been fabricated, which can be used to develop a newly designed touch sensor with reversible electrical responses for potential applications in electronic devices, as demonstrated in this study. The demonstrated dependence of light diffraction on structural transfiguration of the resultant CNT micropattern also indicates their potential for optical devices. Further introduction of various components with specific properties (e.g., ZnO nanorods) into the CNT micropatterns enabled us to tailor such surface characteristics as wettability and light response. Owing to the highly generic nature of the multiple contact transfer strategy, the methodology developed here could provide a general approach for interposing a large variety of multicomponent elements (e.g., nanotubes, nanorods/wires, photonic crystals, etc.) onto a single chip for multifunctional device applications.

Whole-body vibration improves fracture healing and bone quality in rats with ovariectomy-induced osteoporosis.

PubMed

Butezloff, Mariana Maloste; Zamarioli, Ariane; Leoni, Graziela Bianchi; Sousa-Neto, Manoel Damião; Volpon, Jose Batista

2015-11-01

To investigate the effect of vibration therapy on the bone callus of fractured femurs and the bone quality of intact femurs in ovariectomized rats. Fifty-six rats aged seven weeks were divided into four groups: control with femoral fracture (CON, n=14), ovariectomized with femoral fracture (OVX, n=14), control with femoral fracture plus vibration therapy (CON+VT, n=14), and ovariectomized with femoral fracture plus vibration therapy (OVX+VT, n=14). Three months after ovariectomy or sham surgery, a complete fracture was produced at the femoral mid-diaphysis and stabilized with a 1-mm-diameter intramedullary Kirschner wire. X-rays confirmed the fracture alignment and fixation. Three days later, the VT groups underwent vibration therapy (1 mm, 60 Hz for 20 minutes, three times per week for 14 or 28 days). The bone and callus quality were assessed by densitometry, three-dimensional microstructure, and mechanical test. Ovariectomized rats exhibited a substantial loss of bone mass and severe impairment in bone microarchitecture, both in the non-fractured femur and the bone callus. Whole-body vibration therapy exerted an important role in ameliorating the bone and fracture callus parameters in the osteoporotic bone. Vibration therapy improved bone quality and the quality of the fracture bone callus in ovariectomized rats.

Proximal tibial fractures: early experience using polyaxial locking-plate technology.

PubMed

Nikolaou, Vassilios S; Tan, Hiang Boon; Haidukewych, George; Kanakaris, Nikolaos; Giannoudis, Peter V

2011-08-01

Between 2004 and 2009, 60 patients with proximal tibial fractures were included in this prospective study. All fractures were treated with the polyaxial locked-plate fixation system (DePuy, Warsaw, IN, USA). Clinical and radiographic data, including fracture pattern, changes in alignment, local and systemic complications, hardware failure and fracture union were analysed. The mean follow-up was 14 (12-36) months. According to the Orthopaedic Trauma Association (OTA) classification, there were five 41-A, 28 41-B and 27 41-C fractures. Fractures were treated percutaneously in 30% of cases. Double-plating was used in 11 cases. All but three fractures progressed to union at a mean of 3.2 (2.5-5) months. There was no evidence of varus collapse as a result of polyaxial screw failure. No plate fractured, and no screw cut out was noted. There was one case of lateral joint collapse (>10°) in a patient with open bicondylar plateau fracture. The mean Knee Society Score at the time of final follow-up was 91 points, and the mean functional score was 89 points. The polyaxial locking-plate system provided stable fixation of extra-articular and intra-articular proximal tibial fractures and good functional outcomes with a low complication rate.

One size does not fit all: distal radioulnar joint dysfunction after volar locking plate fixation.

PubMed

Jones, Christopher W; Lawson, Richard D

2014-02-01

Background Fractures of the distal radius are among the most common injuries treated by orthopedic surgeons worldwide. Failure to restore distal radius alignment can lead to fracture malunion and poor clinical outcomes, including distal radioulnar joint (DRUJ) instability and limitation of motion. Case Description We present a unique case of DRUJ dysfunction following volar plate fixation of bilateral distal radius fractures and analyze the biomechanical causes of this complication. As a result of a relatively excessive tilt of the precontoured locking plate (in comparison to the patient's particular anatomy), the fracture on one side was "over-reduced," disrupting the biomechanics of the DRUJ, causing a supination block. Clinical Relevance Volar locking plates are not a panacea to all distal radius fractures. Plate selection and fixation technique must include consideration of patient anatomy. Robust plates offer the advantage of providing rigid fixation but can be difficult to contour when reconstructing normal anatomy. Restoration of patient-specific anatomy is crucial to the management of distal radius fractures.

Pediatric distal femur fixation by proximal humeral plate.

PubMed

Abdelgawad, Amr Atef; Kanlic, Enes M

2013-12-01

Distal femoral metaphyseal fractures are common injuries in children. Multiple treatment options have been described for this type of injury. For older children with distal metaphyseal fracture, there is still no optimal method of fixation. We propose that the commonly used proximal humeral plate can provide good method of fixation for this fracture in adolescents. Two children (12 and 14 years old) with distal metaphyseal femoral fracture were treated with proximal humeral plate. We describe the surgical technique and postoperative management. The two children healed with good alignment and full range of motion of the knee. No external immobilization (other than knee immobilizer for the first 2 weeks) was used. We concluded that proximal humeral plate can provide adequate fixation for teenagers with distal femoral metaphyseal fracture. It is readily available; provide multiple options for screw fixation in the distal part of the fracture and fits easily on the distal part of the femur proximal to the physis. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

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

Not Available

We present preliminary hypocenter determinations for 52 earthquakes recorded by a large multiinstitutional network of ocean bottom seismometers and ocean bottom hydrophones in the Orozco Fracture Zone in the eastern Pacific during late February to mid-March 1979. The network was deployed as part of the Rivera Ocean Seismic Experiment, also known as Project ROSE. The Orozco Fracture Zone is Physiographically complex, and the pattern of microearthquake hypocenters at least partly reflects this complexity. All of the well-located epicenters lie within the active transform fault segment of the fracture zone. About half of the recorded earthquakes were aligned along a narrowmore » trough that extends eastward from the northern rise crest intersection in the approximate direction of the Cocos-Pacific relative plate motion; these events appear to be characterized by strike-slip faulting. The second major group of activity occurred in the central portion of the transform fault; the microearthquakes in this group do not display a preferred alignment parallel to the direction of spreading, and several are not obviously associated with distinct topographic features. Hypocentral depth was well resolved for many of the earthquakes reported here. Nominal depths range from 0 to 17 km below the seafloor.« less

Fibre Optic Connections And Method For Using Same

DOEpatents

Chan, Benson; Cohen, Mitchell S.; Fortier, Paul F.; Freitag, Ladd W.; Hall, Richard R.; Johnson, Glen W.; Lin, How Tzu; Sherman, John H.

2004-03-30

A package is described that couples a twelve channel wide fiber optic cable to a twelve channel Vertical Cavity Surface Emitting Laser (VCSEL) transmitter and a multiple channel Perpendicularly Aligned Integrated Die (PAID) receiver. The package allows for reduction in the height of the assembly package by vertically orienting certain dies parallel to the fiber optic cable and horizontally orienting certain other dies. The assembly allows the vertically oriented optoelectronic dies to be perpendicularly attached to the horizontally oriented laminate via a flexible circuit.

Influence of natural fractures on hydraulic fracture propagation

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

Teufel, L.W.; Warpinski, N.R.

Hydraulic fracturing has become a valuable technique for the stimulation of oil, gas, and geothermal reservoirs in a variety of reservoir rocks. In many applications, only short fractures are needed for economic production. In low-permeability reservoirs, however, long penetrating fractures are generally needed, and in this case, natural fractures can be the cause of many adverse effects during a fracture treatment. Natural fractures can influence the overall geometry and effectiveness of the hydraulic fracture by: (1) arresting the vertical or lateral growth, (2) reducing total fracture length via fluid leakoff, (3) limiting proppant transport and placement, and (4) enhancing themore » creation of multiple or secondary fractures rather than a single planar hydraulic fracture. The result may range from negligible to catastrophic depending on the values of the ancillary treatment and reservoir parameters, such as the treating pressure, in-situ stresses, pore pressure, orientations of the natural fractures relative to principal in-situ stresses, spacing and distribution of the natural fractures, permeability, etc. Field observations from mineback experiments at DOE's Nevada Test Site and the multiwell experiment in Colorado, laboratory tests, and analyses of these data are integrated to describe the complex fracture behavior found and to provide guidelines for predicting when this complex fracturing will occur.« less

Influence of natural fractures on hydraulic fracture propagation

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

Teufel, L.W.; Warpinski, N.R.

Hydraulic fracturing has become a valuable technique for the stimulation of oil, gas, and geothermal reservoirs in a variety of reservoir rocks. In many applications, only short fractures are needed for economic production. In low-permeability reservoirs, however, long penetrating fractures are generally needed, and in this case, natural fractures can be the cause of many adverse effects during a fracture treatment. Natural fractures can influence the overall geometry and effectiveness of the hydraulic fracture by: (1) arresting the vertical or lateral growth, (2) reducing total fracture length via fluid leakoff, (3) limiting proppant transport and placement, and (4) enhancing themore » creation of multiple or secondary fractures rather than a single planar hydraulic fracture. The result may range from negligible to catastrophic depending on the values of the ancillary treatment and reservoir parameters, such as the treating pressure, in-situ stresses, pore pressure, orientations of the natural fractures relative to principle in-situ stresses, spacing and distribution of the natural fractures, permeability, etc. Field observations from mineback experiments at DOE's Nevada Test Site and the multiwell experiment in Colorado, laboratory tests, and analyses of these data are integrated to describe the complex fracture behavior found to an provide guidelines for predicting when this complex fracturing occurs.« less

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

Raduha, S.; Butler, D.; Mozley, P. S.

Here, we examined the potential impact on CO 2 transport of zones of deformation bands in reservoir rock that transition to opening-mode fractures within overlying caprock. Sedimentological and petrophysical measurements were collected along an approximately 5 m × 5 m outcrop of the Slick Rock and Earthy Members of the Entrada Sandstone on the eastern flank of the San Rafael Swell, Utah, USA. Measured deformation band permeability (2 mD) within the reservoir facies is about three orders of magnitude lower than the host sandstone. Average permeability of the caprock facies (0.0005 mD) is about seven orders of magnitude lower thanmore » the host sandstone. Aperture-based permeability estimates of the opening-mode caprock fractures are high (3.3 × 10 7 mD). High-resolution CO 2–H 2O transport models incorporate these permeability data at the millimeter scale. We then varied fault properties at the reservoir/caprock interface between open fractures and deformation bands as part of a sensitivity study. Numerical modeling results suggest that zones of deformation bands within the reservoir strongly compartmentalize reservoir pressures largely blocking lateral, cross-fault flow of supercritical CO 2. Significant vertical CO 2 transport into the caprock occurred in some scenarios along opening-mode fractures. The magnitude of this vertical CO 2 transport depends on the small-scale geometry of the contact between the opening-mode fracture and the zone of deformation bands, as well as the degree to which fractures penetrate caprock. Finally, the presence of relatively permeable units within the caprock allows storage of significant volumes of CO 2, particularly when the fracture network does not extend all the way through the caprock.« less

A discrete fracture model for two-phase flow in fractured porous media

NASA Astrophysics Data System (ADS)

Gläser, Dennis; Helmig, Rainer; Flemisch, Bernd; Class, Holger

2017-12-01

A discrete fracture model on the basis of a cell-centered finite volume scheme with multi-point flux approximation (MPFA) is presented. The fractures are included in a d-dimensional computational domain as (d - 1)-dimensional entities living on the element facets, which requires the grid to have the element facets aligned with the fracture geometries. However, the approach overcomes the problem of small cells inside the fractures when compared to equi-dimensional models. The system of equations considered is solved on both the matrix and the fracture domain, where on the prior the fractures are treated as interior boundaries and on the latter the exchange term between fracture and matrix appears as an additional source/sink. This exchange term is represented by the matrix-fracture fluxes, computed as functions of the unknowns in both domains by applying adequate modifications to the MPFA scheme. The method is applicable to both low-permeable as well as highly conductive fractures. The quality of the results obtained by the discrete fracture model is studied by comparison to an equi-dimensional discretization on a simple geometry for both single- and two-phase flow. For the case of two-phase flow in a highly conductive fracture, good agreement in the solution and in the matrix-fracture transfer fluxes could be observed, while for a low-permeable fracture the discrepancies were more pronounced. The method is then applied two-phase flow through a realistic fracture network in two and three dimensions.

Structural Maps of the V-17 Beta Regio Quadrangle, Venus

NASA Technical Reports Server (NTRS)

Basilevsky, A. t.; Head, James W.

2008-01-01

These represent slices of the geologic map into 7 time-stratigraphic levels whose descriptions are found in [3-6]. From older to younger they are: 1) Tessera material unit (t), 2) Densely fractured plains material unit (pdf), 3) Fractured and ridged plains material unit (pfr), 4) Tessera transitional terrain structural unit (tt), 5) Fracture belts structural unit (fb), 6) Shield plains (psh) and plains with wrinkle ridges (pwr) material units combined, and 7) Lobate (pl) and smooth (ps) plains material units combined and, approximately contemporaneous with them, the structural unit of rifted terrain (rt). Each slice shows the generalized pattern of structures typical of these units. Figures 1-7 show the seven maps and Figure 8 shows the combined map illustrating what is shown in the seven maps. To visualize the Beta Regio uplift outlines, the major structure of this area, we show the +0.5 km and +2.5 km contour lines, corresponding respectively to the base and the mid-height of the uplift. It is seen in Figures 1-2 and 4 the trends of t, pdf and tt occupy relatively small areas and their structures seen in these small windows appear rather variable and with almost no orientation heritage with time. Figure 3 shows that swarms of ridge belts trend mostly NW and go through the Beta structure with no alignment with it, suggesting that this structure did not yet exist at this time. Figure 5 shows that fracture belts align along the northern base of the Beta uplift suggesting onset of the formation of this structure. Figure 6 shows that wrinkle ridges do not show alignment with the Beta uplift suggesting that this already forming structure was not high enough to exert topographic stress in its vicinity. Figure 7 shows that the Beta uplift has Devana Chasma as an axial rift zone, suggesting a genetic link between the uplift and rifting. Figure 8 shows that structural trends in this area significantly changed with time.

Comparison between Different Methods for Biomechanical Assessment of Ex Vivo Fracture Callus Stiffness in Small Animal Bone Healing Studies

PubMed Central

Steiner, Malte; Volkheimer, David; Meyers, Nicholaus; Wehner, Tim; Wilke, Hans-Joachim; Claes, Lutz; Ignatius, Anita

2015-01-01

For ex vivo measurements of fracture callus stiffness in small animals, different test methods, such as torsion or bending tests, are established. Each method provides advantages and disadvantages, and it is still debated which of those is most sensitive to experimental conditions (i.e. specimen alignment, directional dependency, asymmetric behavior). The aim of this study was to experimentally compare six different testing methods regarding their robustness against experimental errors. Therefore, standardized specimens were created by selective laser sintering (SLS), mimicking size, directional behavior, and embedding variations of respective rat long bone specimens. For the latter, five different geometries were created which show shifted or tilted specimen alignments. The mechanical tests included three-point bending, four-point bending, cantilever bending, axial compression, constrained torsion, and unconstrained torsion. All three different bending tests showed the same principal behavior. They were highly dependent on the rotational direction of the maximum fracture callus expansion relative to the loading direction (creating experimental errors of more than 60%), however small angular deviations (<15°) were negligible. Differences in the experimental results between the bending tests originate in their respective location of maximal bending moment induction. Compared to four-point bending, three-point bending is easier to apply on small rat and mouse bones under realistic testing conditions and yields robust measurements, provided low variation of the callus shape among the tested specimens. Axial compressive testing was highly sensitive to embedding variations, and therefore cannot be recommended. Although it is experimentally difficult to realize, unconstrained torsion testing was found to be the most robust method, since it was independent of both rotational alignment and embedding uncertainties. Constrained torsional testing showed small errors (up to 16.8%, compared to corresponding alignment under unconstrained torsion) due to a parallel offset between the specimens’ axis of gravity and the torsional axis of rotation. PMID:25781027

Comparison of Friction Characteristics on TN and VA Mode Alignment Films with Friction Force Microscopy

NASA Astrophysics Data System (ADS)

Kwak, Musun; Chung, Hanrok; Kwon, Hyukmin; Kim, Jehyun; Han, Daekyung; Yi, Yoonseon; Lee, Sangmun; Lee, Chulgu; Cha, Sooyoul

Using frictional force microscopy (FFM), the friction surface characteristics were compared between twisted nematic (TN) mode and vertical alignment (VA) mode alignment films (AFs). The friction asymmetry was detected depending on temperature conditions on TN mode AF, but not on VA mode AF. The difference between two modes was explained by leaning intermolecular repulsion caused by the pre-tilt angle uniformity and the density of side chain. No level difference according to temperature conditions appeared when the pre-tilt angle were measured after liquid crystal (LC) injection.

Analysis of geophysical logs, at North Penn Area 6 Superfund Site, Lansdale, Montgomery County, Pennsylvania

USGS Publications Warehouse

Conger, Randall W.

1999-01-01

The U.S. Geological Survey (USGS), as part of technical assistance to the U.S. Environmental Protection Agency (USEPA), collected borehole geophysical log data in 34 industrial, commercial, and public supply wells and 28 monitor wells at the North Penn Area 6 Superfund Site, in Lansdale, Pa., from August 22, 1995, through August 29, 1997. The wells range in depth from 50 to 1,027 feet below land surface and are drilled in Triassic-age shales and siltstones of the Brunswick Group and Lockatong Formation. The geophysical log data were collected to help describe the hydrogeologic framework in the area and to provide guidance in the reconstruction of the 28 monitor wells drilled during summer 1997. At the time of logging, all wells had open-hole construction. The geophysical logs, caliper, fluid-resistivity, and fluid-temperature, and borehole video logs were used to determine the vertical distribution of water-bearing fractures. Heatpulse-flowmeter measurements were used to determine vertical borehole flow under pumping and nonpumping conditions. The most productive fractures generally could be determined from heatpulse-flowmeter measurements under pumping conditions. Vertical borehole flow was measured under nonpumping conditions in most wells that had more than one water-bearing fracture. Upward flow was measured in 35 wells and probably is a result of natural head differences between fractures in the local ground-water-flow system. Downward flow was measured in 11 wells and commonly indicated differences in hydraulic heads of the fractures caused by nearby pumping. Both upward and downward flow was measured in three wells. No flow was detected in eight wells. Natural-gamma-ray logs were used to estimate the attitude of bedding. Thin shale marker beds, shown as spikes of elevated radioactivity in the natural-gamma logs of some wells throughout the area, enable the determination of bedding-plane orientation from three-point correlations. Generally, the marker beds in and near Lansdale strike about N. 48°-60° E. and dip about 11° NW. Acoustic televiewer logs run in selected boreholes indicate that the attitude of many water-bearing fractures commonly is similar to that of bedding.

Comparison of the compressive strength of 3 different implant design systems.

PubMed

Pedroza, Jose E; Torrealba, Ysidora; Elias, Augusto; Psoter, Walter

2007-01-01

The aims of this study were twofold: to compare the static compressive strength at the implant-abutment interface of 3 design systems and to describe the implant abutment connection failure mode. A stainless steel holding device was designed to align the implants at 30 degrees with respect to the y-axis. Sixty-nine specimens were used, 23 for each system. A computer-controlled universal testing machine (MTS 810) applied static compression loading by a unidirectional vertical piston until failure. Specimens were evaluated macroscopically for longitudinal displacement, abutment looseness, and screw and implant fracture. Data were analyzed by analysis of variance (ANOVA). The mean compressive strength for the Unipost system was 392.5 psi (SD +/-40.9), for the Spline system 342.8 psi (SD+/-25.8), and for the Screw-Vent system 269.1 psi (SD+/-30.7). The Unipost implant-abutment connection demonstrated a statistically significant superior mechanical stability (P < or = .009) compared with the Spline implant system. The Spline implant system showed a statistically significant higher compressive strength than the Screw-Vent implant system (P < or =.009). Regarding failure mode, the Unipost system consistently broke at the same site, while the other systems failed at different points of the connection. The Unipost system demonstrated excellent fracture resistance to compressive forces; this resistance may be attributed primarily to the diameter of the abutment screw and the 2.5 mm counter bore, representing the same and a unique piece of the implant. The Unipost implant system demonstrated a statistically significant superior compressive strength value compared with the Spline and Screw-Vent systems, at a 30 degrees angulation.

Effect of porosity variation on the electrochemical behavior of vertically aligned multi-walled carbon nanotubes.

PubMed

Raut, Akshay S; Parker, Charles B; Stoner, Brian R; Glass, Jeffrey T

2012-06-01

Electrochemical charge storage characteristics of vertically aligned multi-walled carbon nanotubes (MWCNTs) as a function of varying diameter and spacing are reported. It was observed that the specific capacitance of the MWCNTs increased as both diameter and inter-tube spacing decreased. The MWCNT films with 229 nm inter-MWCNT spacing exhibited specific capacitance of 228 F/g versus 70 F/g for 506 nm spacing, when tested in a non-aqueous electrolyte. Further, a trend in specific capacitance versus pore size is proposed. Coupled with previously reported trends observed in the sub-10 nm pore size regime, this is expected to offer better understanding of electrochemical behavior of porous carbon materials over a wide range of pore sizes.

Gas sensing with gold-decorated vertically aligned carbon nanotubes

PubMed Central

Mudimela, Prasantha R; Scardamaglia, Mattia; González-León, Oriol; Reckinger, Nicolas; Snyders, Rony; Llobet, Eduard; Colomer, Jean-François

2014-01-01

Summary Vertically aligned carbon nanotubes of different lengths (150, 300, 500 µm) synthesized by thermal chemical vapor deposition and decorated with gold nanoparticles were investigated as gas sensitive materials for detecting nitrogen dioxide (NO2) at room temperature. Gold nanoparticles of about 6 nm in diameter were sputtered on the top surface of the carbon nanotube forests to enhance the sensitivity to the pollutant gas. We showed that the sensing response to nitrogen dioxide depends on the nanotube length. The optimum was found to be 300 µm for getting the higher response. When the background humidity level was changed from dry to 50% relative humidity, an increase in the response to NO2 was observed for all the sensors, regardless of the nanotube length. PMID:24991529

Gas sensing with gold-decorated vertically aligned carbon nanotubes.

PubMed

Mudimela, Prasantha R; Scardamaglia, Mattia; González-León, Oriol; Reckinger, Nicolas; Snyders, Rony; Llobet, Eduard; Bittencourt, Carla; Colomer, Jean-François

2014-01-01

Vertically aligned carbon nanotubes of different lengths (150, 300, 500 µm) synthesized by thermal chemical vapor deposition and decorated with gold nanoparticles were investigated as gas sensitive materials for detecting nitrogen dioxide (NO2) at room temperature. Gold nanoparticles of about 6 nm in diameter were sputtered on the top surface of the carbon nanotube forests to enhance the sensitivity to the pollutant gas. We showed that the sensing response to nitrogen dioxide depends on the nanotube length. The optimum was found to be 300 µm for getting the higher response. When the background humidity level was changed from dry to 50% relative humidity, an increase in the response to NO2 was observed for all the sensors, regardless of the nanotube length.

Enhanced ionic liquid mobility induced by confinement in 1D CNT membranes

NASA Astrophysics Data System (ADS)

Berrod, Q.; Ferdeghini, F.; Judeinstein, P.; Genevaz, N.; Ramos, R.; Fournier, A.; Dijon, J.; Ollivier, J.; Rols, S.; Yu, D.; Mole, R. A.; Zanotti, J.-M.

2016-04-01

Water confined within carbon nanotubes (CNT) exhibits tremendous enhanced transport properties. Here, we extend this result to ionic liquids (IL) confined in vertically aligned CNT membranes. Under confinement, the IL self-diffusion coefficient is increased by a factor 3 compared to its bulk reference. This could lead to high power battery separators.Water confined within carbon nanotubes (CNT) exhibits tremendous enhanced transport properties. Here, we extend this result to ionic liquids (IL) confined in vertically aligned CNT membranes. Under confinement, the IL self-diffusion coefficient is increased by a factor 3 compared to its bulk reference. This could lead to high power battery separators. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01445c

Growth of vertically aligned carbon nanofibers by low-pressure inductively coupled plasma-enhanced chemical vapor deposition

NASA Astrophysics Data System (ADS)

Caughman, J. B. O.; Baylor, L. R.; Guillorn, M. A.; Merkulov, V. I.; Lowndes, D. H.; Allard, L. F.

2003-08-01

Vertically aligned carbon nanofibers (VACNFs) have been grown using a low-pressure, plasma-enhanced, chemical vapor deposition process. The nanofibers are grown from a nickel catalyst that can be patterned to form arrays of individual, isolated VACNFs. The fibers are grown at pressures below 100 mTorr, using an inductively coupled plasma source with a radio-frequency bias on the sample substrate to allow for independent control of the ion energies. Plasma conditions are related to growth results by comparing optical emission from the plasma to the physical structure of the nanofibers. We find that the ratio of etching species in the plasma to depositing species is critical to the final shape of the carbon structures that are formed.

Vertically aligned gas-insulated transmission line having particle traps at the inner conductor

DOEpatents

Dale, Steinar J.

1984-01-01

Gas insulated electrical apparatus having first and second conductors separated by an insulating support within an insulating gas environment, and particle traps disposed along the surface of the high potential conductor for trapping and inactivating foreign particles which may be present within the insulating gas medium. Several embodiments of the invention were developed which are particularly suited for vertically aligned gas insulated transmission lines. The particle traps are grooves or cavities formed into the walls of the tubular inner conductor, without extending into the hollow portion of the conductor. In other embodiments, the traps are appendages or insert flanges extending from the inner conductor, with the insulator supports contacting the appendages instead of the inner conductor.

Vertically aligned carbon nanofiber electrode arrays for nucleic acid detection

NASA Astrophysics Data System (ADS)

Arumugam, Prabhu U.; Yu, Edmond; Riviere, Roger; Meyyappan, M.

2010-10-01

We present electrochemical detection of DNA targets that corresponds to Escherichia coli O157:H7 16S rRNA gene using a nanoelectrode array consisting of vertically aligned carbon nanofiber (VACNF) electrodes. Parylene C is used as gap filling 'matrix' material to avoid high temperature processing in electrode construction. This easy to deposit film of several micron heights provides a conformal coating between the high aspect ratio VACNFs with negligible pin-holes. The low background currents show the potential of this approach for ultra-sensitive detection. Consistent and reproducible electrochemical-signals are achieved using a simple electrode preparation. This simple, reliable and low-cost approach is a forward step in developing practical sensors for applications like pathogen detection, early cancer diagnosis and environmental monitoring.

Preliminary analysis of force-torque measurements for robot-assisted fracture surgery.

PubMed

Georgilas, Ioannis; Dagnino, Giulio; Tarassoli, Payam; Atkins, Roger; Dogramadzi, Sanja

2015-08-01

Our group at Bristol Robotics Laboratory has been working on a new robotic system for fracture surgery that has been previously reported [1]. The robotic system is being developed for distal femur fractures and features a robot that manipulates the small fracture fragments through small percutaneous incisions and a robot that re-aligns the long bones. The robots controller design relies on accurate and bounded force and position parameters for which we require real surgical data. This paper reports preliminary findings of forces and torques applied during bone and soft tissue manipulation in typical orthopaedic surgery procedures. Using customised orthopaedic surgical tools we have collected data from a range of orthopaedic surgical procedures at Bristol Royal Infirmary, UK. Maximum forces and torques encountered during fracture manipulation which involved proximal femur and soft tissue distraction around it and reduction of neck of femur fractures have been recorded and further analysed in conjunction with accompanying image recordings. Using this data we are establishing a set of technical requirements for creating safe and dynamically stable minimally invasive robot-assisted fracture surgery (RAFS) systems.

Splitting of a vertical multiwalled carbon nanotube carpet to a graphene nanoribbon carpet and its use in supercapacitors.

PubMed

Zhang, Chenguang; Peng, Zhiwei; Lin, Jian; Zhu, Yu; Ruan, Gedeng; Hwang, Chih-Chau; Lu, Wei; Hauge, Robert H; Tour, James M

2013-06-25

Potassium vapor was used to longitudinally split vertically aligned multiwalled carbon nanotubes carpets (VA-CNTs). The resulting structures have a carpet of partially split MWCNTs and graphene nanoribbons (GNRs). The split structures were characterized by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. When compared to the original VA-CNTs carpet, the split VA-CNTs carpet has enhanced electrochemical performance with better specific capacitance in a supercapacitor. Furthermore, the split VA-CNTs carpet has excellent cyclability as a supercapacitor electrode material. There is a measured maximum power density of 103 kW/kg at an energy density of 5.2 Wh/kg and a maximum energy density of 9.4 Wh/kg. The superior electrochemical performances of the split VA-CNTs can be attributed to the increased surface area for ion accessibility after splitting, and the lasting conductivity of the structure with their vertical conductive paths based on the preserved GNR alignment.

Effects of spatial separation on the growth of vertically aligned carbon nanofibers produced by plasma-enhanced chemical vapor deposition

NASA Astrophysics Data System (ADS)

Merkulov, Vladimir I.; Melechko, Anatoli V.; Guillorn, Michael A.; Lowndes, Douglas H.; Simpson, Michael L.

2002-01-01

Vertically aligned carbon nanofibers (VACNFs) with vastly different spacing were grown by catalytically controlled dc glow discharge chemical vapor deposition. Both densely packed VACNFs and essentially isolated VACNFs were studied using scanning electron microscopy and x-ray energy dispersive spectroscopy. The morphology and chemical composition of isolated VACNFs were found to have a strong dependence upon the growth conditions, in particular on the C2H2/NH3 gas mixture used. This is attributed to the sidewalls of isolated VACNFs being exposed to reactive species during growth. In contrast, the sidewalls of densely packed VACNFs were shielded by the neighboring VACNFs, so that their growth occurred mainly in the vertical direction, by diffusion of carbon through the catalyst nanoparticle and subsequent precipitation at the nanofiber/nanoparticle interface. These striking differences in the growth process result in the formation of flattened carbon nanostructures (carbon nanotriangles) and also are quite important for the realization of VACNF-based devices.

The precision measurement and assembly for miniature parts based on double machine vision systems

NASA Astrophysics Data System (ADS)

Wang, X. D.; Zhang, L. F.; Xin, M. Z.; Qu, Y. Q.; Luo, Y.; Ma, T. M.; Chen, L.

2015-02-01

In the process of miniature parts' assembly, the structural features on the bottom or side of the parts often need to be aligned and positioned. The general assembly equipment integrated with one vertical downward machine vision system cannot satisfy the requirement. A precision automatic assembly equipment was developed with double machine vision systems integrated. In the system, a horizontal vision system is employed to measure the position of the feature structure at the parts' side view, which cannot be seen with the vertical one. The position measured by horizontal camera is converted to the vertical vision system with the calibration information. By careful calibration, the parts' alignment and positioning in the assembly process can be guaranteed. The developed assembly equipment has the characteristics of easy implementation, modularization and high cost performance. The handling of the miniature parts and assembly procedure were briefly introduced. The calibration procedure was given and the assembly error was analyzed for compensation.

Simulating Fragmentation and Fluid-Induced Fracture in Disordered Media Using Random Finite-Element Meshes

DOE PAGES

Bishop, Joseph E.; Martinez, Mario J.; Newell, Pania

2016-11-08

Fracture and fragmentation are extremely nonlinear multiscale processes in which microscale damage mechanisms emerge at the macroscale as new fracture surfaces. Numerous numerical methods have been developed for simulating fracture initiation, propagation, and coalescence. In this paper, we present a computational approach for modeling pervasive fracture in quasi-brittle materials based on random close-packed Voronoi tessellations. Each Voronoi cell is formulated as a polyhedral finite element containing an arbitrary number of vertices and faces. Fracture surfaces are allowed to nucleate only at the intercell faces. Cohesive softening tractions are applied to new fracture surfaces in order to model the energy dissipatedmore » during fracture growth. The randomly seeded Voronoi cells provide a regularized discrete random network for representing fracture surfaces. The potential crack paths within the random network are viewed as instances of realizable crack paths within the continuum material. Mesh convergence of fracture simulations is viewed in a weak, or distributional, sense. The explicit facet representation of fractures within this approach is advantageous for modeling contact on new fracture surfaces and fluid flow within the evolving fracture network. Finally, applications of interest include fracture and fragmentation in quasi-brittle materials and geomechanical applications such as hydraulic fracturing, engineered geothermal systems, compressed-air energy storage, and carbon sequestration.« less

Simulating Fragmentation and Fluid-Induced Fracture in Disordered Media Using Random Finite-Element Meshes

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

Bishop, Joseph E.; Martinez, Mario J.; Newell, Pania

Fracture and fragmentation are extremely nonlinear multiscale processes in which microscale damage mechanisms emerge at the macroscale as new fracture surfaces. Numerous numerical methods have been developed for simulating fracture initiation, propagation, and coalescence. In this paper, we present a computational approach for modeling pervasive fracture in quasi-brittle materials based on random close-packed Voronoi tessellations. Each Voronoi cell is formulated as a polyhedral finite element containing an arbitrary number of vertices and faces. Fracture surfaces are allowed to nucleate only at the intercell faces. Cohesive softening tractions are applied to new fracture surfaces in order to model the energy dissipatedmore » during fracture growth. The randomly seeded Voronoi cells provide a regularized discrete random network for representing fracture surfaces. The potential crack paths within the random network are viewed as instances of realizable crack paths within the continuum material. Mesh convergence of fracture simulations is viewed in a weak, or distributional, sense. The explicit facet representation of fractures within this approach is advantageous for modeling contact on new fracture surfaces and fluid flow within the evolving fracture network. Finally, applications of interest include fracture and fragmentation in quasi-brittle materials and geomechanical applications such as hydraulic fracturing, engineered geothermal systems, compressed-air energy storage, and carbon sequestration.« less

The estimation of CO2 storage potential of gas-bearing shale complex at the early stage of reservoir characterization: the case of Baltic Basin (Poland).

NASA Astrophysics Data System (ADS)

Wójcicki, Adam; Jarosiński, Marek

2017-04-01

For the stage of shale gas production, like in the USA, prediction of the CO2 storage potential in shale reservoir can be performed by dynamic modeling. We have made an attempt to estimate this potential at an early stage of shale gas exploration in the Lower Paleozoic Baltic Basin, based on data from 3,800 m deep vertical well (without hydraulic fracking stimulation), supplemented with additional information from neighboring boreholes. Such an attempt makes a sense as a first guess forecast for company that explores a new basin. In our approach, the storage capacity is build by: (1) sorption potential of organic matter, (2) open pore space and (3) potential fracture space. the sequence. our estimation is done for 120 m long shale sequence including three shale intervals enriched with organic mater. Such an interval is possible to be fracked from a single horizontal borehole as known from hydraulic fracture treatment in the other boreholes in this region. The potential for adsorbed CO2 is determined from Langmuir isotherm parameters taken from laboratory measurements in case of both CH4 and CO2 adsorption, as well as shale density and volume. CO2 has approximately three times higher sorption capacity than methane to the organic matter contained in the Baltic Basin shales. Finally, due to low permeability of shale we adopt the common assumption for the USA shale basins that the CO2 will be able to reach effectively only 10% of theoretical total sorption volume. The pore space capacity was estimated by utilizing results of laboratory measurements of dynamic capacity for pores bigger than 10 nm. It is assumed for smaller pores adsorption prevails over free gas. Similarly to solution for sorption, we have assumed that only 10 % of the tight pore space will be reached by CO2. For fracture space we have considered separately natural (tectonic-origin) and technological (potentially produced by hydraulic fracturing treatment) fractures. From fracture density profile and typical permeability of fractures under lithostatic stress we inferred negligible open space of natural fractures. Technological fracture space was calculated as an potential for hydraulic stimulation of vertical fractures until, due to elastic expansion of reservoir, the horizontal minimum stress equals the vertical one. In such a case, horizontal fractures start to open and the stimulation process gets to fail. Based on elastic anisotropy and tectonic stress differentiation, the maximum hydraulic horizontal extension was calculated for separated shale complexes. For further storage capacity we assumed that technological fracture space create primary pathway for CO2 transport is entirely accessible for the CO2. In general, the CO2 sorption capacity makes the predominant contribution and fracture space capacity is comparable or smaller than pore space contribution. When compare this with the best recognized Marcellus shale basin we can see that our calculations for the 35 m depth interval comprising formations with the higher TOC content show a slightly lower value than in the case of Marcellus.

Inverse modeling of the hydraulic properties of fractured media : development of a flow tomography approach

NASA Astrophysics Data System (ADS)

Bour, O.; Klepikova, M.; Le Borgne, T.; De Dreuzy, J.

2013-12-01

Inverse modeling of hydraulic and geometrical properties of fractured media is a very challenging objective due to the spatial heterogeneity of the medium and the scarcity of data. Here we present a flow tomography approach that permits to characterize the location, the connectivity and the hydraulic properties of main flow paths in fractured media. The accurate characterization of the location, hydraulic properties and connectivity of major fracture zones is essential to model flow and solute transport in fractured media. Cross-borehole flowmeter tests, which consist of measuring changes in vertical borehole flows when pumping a neighboring borehole, were shown to be an efficient technique to provide information on the properties of the flow zones that connect borehole pairs [Paillet, 1998; Le Borgne et al., 2006]. The interpretation of such experiments may however be quite uncertain when multiple connections exist. In this study, we explore the potential of flow tomography (i.e., sequential cross-borehole flowmeter tests) for characterizing aquifer heterogeneity. We first propose a framework for inverting flow and drawdown data to infer fracture connectivity and transmissivities. Here we use a simplified discrete fracture network approach that highlights main connectivity structures. This conceptual model attempts to reproduce fracture network connectivity without taking fracture geometry (length, orientation, dip) into account. We then explore the potential of the method for simplified synthetic fracture network models and quantify the sensitivity of drawdown and borehole flow velocities to the transmissivity of the connecting flowpaths. Flow tomography is expected to be most effective if cross-borehole pumping induces large changes in vertical borehole velocities. The uncertainty of the transmissivity estimates increases for small borehole flow velocities. The uncertainty about the transmissivity of fractures that connect the main flowpath but not the boreholes is generally higher. We demonstrate that successively changing pumping and observation boreholes improves the quality of available information and reduces the indetermination of the problem. The inverse method is validated for different synthetic flow scenarios. It is shown to provide a good estimation of connectivity patterns and transmissivities of main flowpaths. Although the chosen fracture network geometry has been simplified, flow tomography appears to be a promising approach for characterizing connectivity patterns and transmissivities of fractured media.

Vertical cross contamination of trichloroethylene in a borehole in fractured sandstone

USGS Publications Warehouse

Sterling, S.N.; Parker, B.L.; Cherry, J.A.; Williams, J.H.; Lane, J.W.; Haeni, F.P.

2005-01-01

Boreholes drilled through contaminated zones in fractured rock create the potential for vertical movement of contaminated ground water between fractures. The usual assumption is that purging eliminates cross contamination; however, the results of a field study conducted in a trichloroethylene (TCE) plume in fractured sandstone with a mean matrix porosity of 13% demonstrates that matrix-diffusion effects can be strong and persistent. A deep borehole was drilled to 110 m below ground surface (mbgs) near a shallow bedrock well containing high TCE concentrations. The borehole was cored continuously to collect closely spaced samples of rock for analysis of TCE concentrations. Geophysical logging and flowmetering were conducted in the open borehole, and a removable multilevel monitoring system was installed to provide hydraulic-head and ground water samples from discrete fracture zones. The borehole was later reamed to complete a well screened from 89 to 100 mbgs; persistent TCE concentrations at this depth ranged from 2100 to 33,000 ??g/L. Rock-core analyses, combined with the other types of borehole information, show that nearly all of this deep contamination was due to the lingering effects of the downward flow of dissolved TCE from shallower depths during the few days of open-hole conditions that existed prior to installation of the multilevel system. This study demonstrates that transfer of contaminant mass to the matrix by diffusion can cause severe cross contamination effects in sedimentary rocks, but these effects generally are not identified from information normally obtained in fractured-rock investigations, resulting in potential misinterpretation of site conditions. Copyright ?? 2005 National Ground Water Association.

Evaluation of borehole geophysical logging, aquifer-isolation tests, distribution of contaminants, and water-level measurements at the North Penn Area 5 Superfund Site, Bucks and Montgomery counties, Pennsylvania

USGS Publications Warehouse

Bird, Philip H.; Conger, Randall W.

2002-01-01

Borehole geophysical logging and aquifer-isolation (packer) tests were conducted at the North Penn Area 5 Superfund site in Bucks and Montgomery Counties, Pa. Caliper, naturalgamma, single-point-resistance, fluid-temperature, fluid-resistivity, heatpulse-flowmeter, and digital acoustic-televiewer logs and borehole television surveys were collected in 32 new and previously drilled wells that ranged in depth from 68 to 302 feet. Vertical borehole-fluid movement direction and rate were measured with a high-resolution heatpulse flowmeter under nonpumping conditions. The suite of logs was used to locate water-bearing fractures, determine zones of vertical borehole-fluid movement, select depths to set packers, and locate appropriate screen intervals for reconstructing new wells as monitoring wells. Aquifer-isolation tests were conducted in four wells to sample discrete intervals and to determine specific capacities of discrete water-bearing zones. Specific capacities of isolated zones during packer testing ranged from 0.12 to 15.30 gallons per minute per foot. Most fractures identified by borehole geophysical methods as water-producing or water-receiving zones produced water when isolated and pumped. The acoustic-televiewer logs define two basic fracture sets, bedding-plane partings with a mean strike of N. 62° E. and a mean dip of 27° NW., and high-angle fractures with a mean strike of N. 58° E. and a mean dip of 72° SE. Correlation of heatpulse-flowmeter data and acoustic-televiewer logs showed 83 percent of identified water-bearing fractures were high-angle fractures.

Strain-induced vertical self-organization of semiconductor quantum dots: A computational study

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

Shtinkov, N., E-mail: nshtinkov@uottawa.ca

Atomistic strain simulations based on the valence force field method are employed to study the vertical arrangements of semiconductor quantum dot (QD) multilayers. The effects of the QD shape, dimensions, and materials parameters are systematically investigated, varying independently the following parameters: spacer width H, QD lateral spacing D, base b, and height h, slope of the side facets, elastic properties of the dot and the substrate materials, and lattice mismatch between the dot and the substrate. The transition between vertically aligned and anti-aligned structures is found to be determined mainly by the ratios H/D and b/D, as well as bymore » the strain anisotropy of the substrate and to a lesser extent of the QD. The dependence on the QD height h is significant only for steep side facets and large aspect ratios h/b, and the effects of the lattice mismatch strain and the bulk elastic moduli are found to be negligible. The comparison with experimental data shows an excellent agreement with the results from the simulations, demonstrating that the presented analysis results in precise theoretical predictions for the vertical self-organization regime in a wide range of QD materials systems.« less

Role of cerebellar nodulus and uvula on the vestibular quick phase spatial constancy.

PubMed

Pettorossi, V E; Grassi, S; Errico, P; Barmack, N H

2001-01-01

We investigated the orientation of quick phases (QPs) of vestibularly-induced eye movements in rabbits in response to "off-vertical" sinusoidal vestibular stimulation. We also examined the possible role of the cerebellar nodulus and ventral uvula in controlling QP spatial orientation and modification. During "off-vertical" vestibular stimulation QPs remained aligned with the earth's horizontal plane, while the slow phases (SPs) were aligned with the plane of vestibular stimulation. This suggests that QPs are coded in gravito-inertial coordinates and SPs in head coordinates. When rabbits were oscillated in the light (20 degrees peak-to-peak; 0.2 Hz) about an "off-vertical" axis for 2 h, the QPs changed their trajectory, abandoning the earth's horizontal plane to approach the plane of the stimulus. By contrast, in the absence of conjunctive optokinetic stimulation, QPs remained fixed in the earth's horizontal plane even after 2 h of "off-vertical" stimulation. The conjunctive combination of optokinetic and vestibular stimulation caused QPs to change their plane of rotation. After lesion of the nodulus-uvula the ability of rabbits to reorient QPs during conjoint vestibular-optokinetic stimulation was maintained. We conclude that the space orientation and adaptation of QPs do not require cerebellar control.

Biomechanical assessment and 3D finite element analysis of the treatment of tibial fractures using minimally invasive percutaneous plates

PubMed Central

Hu, Xin-Jia; Wang, Hua

2017-01-01

The aim of the present study was to investigate the biomechanical effects of varying the length of a limited contact-dynamic compression plate (LC-DCP) and the number and position of screws on middle tibial fractures, and to provide biomechanical evidence regarding minimally invasive plate osteosynthesis (MIPO). For biomechanical testing, 60 tibias from cadavers (age at mortality, 20–40 years) were used to create middle and diagonal fracture models without defects. Tibias were randomly grouped and analyzed by biomechanic and three-dimensional (3D) finite element analysis. The differences among LC-DCPs of different lengths (6-, 10- and 14-hole) with 6 screws, 14-hole LC-DCPs with different numbers of screws (6, 10 and 14), and 14-hole LC-DCPs with 6 screws at different positions with regard to mechanical characteristics, including compressing, torsion and bending, were examined. The 6-hole LC-DCP had greater vertical compression strain compared with the 10- and 14-hole LC-DCPs (P<0.01), and the 14-hole LC-DCP had greater lateral strain than the 6- and 10-hole LC-DCPs (P<0.01). Furthermore, significant differences in torque were observed among the LC-DPs of different lengths (P<0.01). For 14-hole LC-DCPs with different numbers of screws, no significant differences in vertical strain, lateral strain or torque were detected (P>0.05). However, plates with 14 screws had greater vertical strain compared with those fixed with 6 or 10 screws (P<0.01). For 4-hole LC-DCPs with screws at different positions, vertical compression strain values were lowest for plates with screws at positions 1, 4, 7, 8, 11 and 14 (P<0.01). The lateral strain values and vertical strain values for plates with screws at positions 1, 3, 6, 9, 12 and 14 were significantly lower compared with those at the other positions (P<0.01), and torque values were also low. Thus, the 14-hole LC-DCP was the most stable against vertical compression, torsion and bending, and the 6-hole LC-DCP was the least stable. However, the use of 14 screws with a 14-hole LC-DCP provided less stability against bending than did 6 or 10 screws. Furthermore, fixation with distributed screws, in which some screws were close to the fracture line, provided good stability against compression and torsion, while fixation with screws at the ends of the LC-DCP provided poor stability against bending, compressing and torsion. PMID:28781632

Hindfoot Valgus following Interlocking Nail Treatment for Tibial Diaphysis Fractures: Can the Fibula Be Neglected?

PubMed Central

Uzun, Metin; Kara, Adnan; Adaş, Müjdat; Karslioğlu, Bülent; Bülbül, Murat; Beksaç, Burak

2014-01-01

Purpose. We evaluated whether intramedullary nail fixation for tibial diaphysis fractures with concomitant fibula fractures (except at the distal one-third level) managed conservatively with an associated fibula fracture resulted in ankle deformity and assessed the impact of the ankle deformity on lower extremity function. Methods. Sixty middle one-third tibial shaft fractures with associated fibular fractures, except the distal one-third level, were included in this study. All tibial shaft fractures were anatomically reduced and fixed with interlocking intramedullary nails. Fibular fractures were managed conservatively. Hindfoot alignment was assessed clinically. Tibia and fibular lengths were compared to contralateral measurements using radiographs. Functional results were evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Foot and Ankle Disability Index Score (FADI). Results. Anatomic union, defined as equal length in operative and contralateral tibias, was achieved in 60 fractures (100%). Fibular shortening was identified in 42 fractures (68%). Mean fibular shortening was 1.2 cm (range, 0.5–2 cm). Clinical exams showed increased hindfoot valgus in 42 fractures (68%). The mean KOOS was 88.4, and the mean FADI score was 90. Conclusion. Fibular fractures in the middle or proximal one-third may need to be stabilized at the time of tibial intramedullary nail fixation to prevent development of hindfoot valgus due to fibular shortening. PMID:25544899

The Israeli elite infantry recruit: a model for understanding the biomechanics of stress fractures.

PubMed

Milgrom, C

1989-01-01

In a series of prospective studies among infantry recruits the biomechanics of stress fractures have been studied. In this recruit model bone geometry and the natural shock absorbers of the body have been found to be related to stress fracture morbidity. Using the technique of accelerometry in this model, it has been shown that in the fatigue state shock absorption decreases, resulting in an increase in the amplitude of vertical accelerations that propagate up the skeleton at heel strike. Experiments to study the possibility of lowering stress fracture morbidity in this model by means of viscoelastic orthotics have been successful only in the case of femoral and metatarsal stress fractures among certain subpopulations. Stress fracture management in this model has been improved by early detection and by treatment regimens according to a protocol that emphasizes limited rest periods to allow healing to take place rather than judging recovery by pain levels.

Three types of gas hydrate reservoirs in the Gulf of Mexico identified in LWD data

USGS Publications Warehouse

Lee, Myung Woong; Collett, Timothy S.

2011-01-01

High quality logging-while-drilling (LWD) well logs were acquired in seven wells drilled during the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II in the spring of 2009. These data help to identify three distinct types of gas hydrate reservoirs: isotropic reservoirs in sands, vertical fractured reservoirs in shale, and horizontally layered reservoirs in silty shale. In general, most gas hydratebearing sand reservoirs exhibit isotropic elastic velocities and formation resistivities, and gas hydrate saturations estimated from the P-wave velocity agree well with those from the resistivity. However, in highly gas hydrate-saturated sands, resistivity-derived gas hydrate-saturation estimates appear to be systematically higher by about 5% over those estimated by P-wave velocity, possibly because of the uncertainty associated with the consolidation state of gas hydrate-bearing sands. Small quantities of gas hydrate were observed in vertical fractures in shale. These occurrences are characterized by high formation resistivities with P-wave velocities close to those of water-saturated sediment. Because the formation factor varies significantly with respect to the gas hydrate saturation for vertical fractures at low saturations, an isotropic analysis of formation factor highly overestimates the gas hydrate saturation. Small quantities of gas hydrate in horizontal layers in shale are characterized by moderate increase in P-wave velocities and formation resistivities and either measurement can be used to estimate gas hydrate saturations.

Control of spatial orientation of the angular vestibuloocular reflex by the nodulus and uvula.

PubMed

Wearne, S; Raphan, T; Cohen, B

1998-05-01

Spatial orientation of the angular vestibuloocular reflex (aVOR) was studied in rhesus monkeys after complete and partial ablation of the nodulus and ventral uvula. Horizontal, vertical, and torsional components of slow phases of nystagmus were analyzed to determine the axes of eye rotation, the time constants (Tcs) of velocity storage, and its orientation vectors. The gravito-inertial acceleration vector (GIA) was tilted relative to the head during optokinetic afternystagmus (OKAN), centrifugation, and reorientation of the head during postrotatory nystagmus. When the GIA was tilted relative to the head in normal animals, horizontal Tcs decreased, vertical and/or roll time constants (Tc(vert/roll)) lengthened according to the orientation of the GIA, and vertical and/or roll eye velocity components appeared (cross-coupling). This shifted the axis of eye rotation toward alignment with the tilted GIA. Horizontal and vertical/roll Tcs varied inversely, with T(chor) being longest and T(cvert/roll) shortest when monkeys were upright, and the reverse when stimuli were around the vertical or roll axes. Vertical or roll Tcs were longest when the axes of eye rotation were aligned with the spatial vertical, respectively. After complete nodulo-uvulectomy, T(chor) became longer, and periodic alternating nystagmus (PAN) developed in darkness. T(chor) could not be shortened in any of paradigms tested. In addition, yaw-to-vertical/roll cross-coupling was lost, and the axes of eye rotation remained fixed during nystagmus, regardless of the tilt of the GIA with respect to the head. After central portions of the nodulus and uvula were ablated, leaving lateral portions of the nodulus intact, yaw-to-vertical/roll cross-coupling and control of Tc(vert/roll) was lost or greatly reduced. However, control of Tchor was maintained, and T(chor) continued to vary as a function of the tilted GIA. Despite this, the eye velocity vector remained aligned with the head during yaw axis stimulation after partial nodulo-uvulectomy, regardless of GIA orientation to the head. The data were related to a three-dimensional model of the aVOR, which simulated the experimental results. The model provides a basis for understanding how the nodulus and uvula control processing within the vestibular nuclei responsible for spatial orientation of the aVOR. We conclude that the three-dimensional dynamics of the velocity storage system are determined in the nodulus and ventral uvula. We propose that the horizontal and vertical/roll Tcs are separately controlled in the nodulus and uvula with the dynamic characteristics of vertical/roll components modulated in central portions and the horizontal components laterally, presumably in a semicircular canal-based coordinate frame.

Desktop aligner for fabrication of multilayer microfluidic devices.

PubMed

Li, Xiang; Yu, Zeta Tak For; Geraldo, Dalton; Weng, Shinuo; Alve, Nitesh; Dun, Wu; Kini, Akshay; Patel, Karan; Shu, Roberto; Zhang, Feng; Li, Gang; Jin, Qinghui; Fu, Jianping

2015-07-01

Multilayer assembly is a commonly used technique to construct multilayer polydimethylsiloxane (PDMS)-based microfluidic devices with complex 3D architecture and connectivity for large-scale microfluidic integration. Accurate alignment of structure features on different PDMS layers before their permanent bonding is critical in determining the yield and quality of assembled multilayer microfluidic devices. Herein, we report a custom-built desktop aligner capable of both local and global alignments of PDMS layers covering a broad size range. Two digital microscopes were incorporated into the aligner design to allow accurate global alignment of PDMS structures up to 4 in. in diameter. Both local and global alignment accuracies of the desktop aligner were determined to be about 20 μm cm(-1). To demonstrate its utility for fabrication of integrated multilayer PDMS microfluidic devices, we applied the desktop aligner to achieve accurate alignment of different functional PDMS layers in multilayer microfluidics including an organs-on-chips device as well as a microfluidic device integrated with vertical passages connecting channels located in different PDMS layers. Owing to its convenient operation, high accuracy, low cost, light weight, and portability, the desktop aligner is useful for microfluidic researchers to achieve rapid and accurate alignment for generating multilayer PDMS microfluidic devices.

Desktop aligner for fabrication of multilayer microfluidic devices

PubMed Central

Li, Xiang; Yu, Zeta Tak For; Geraldo, Dalton; Weng, Shinuo; Alve, Nitesh; Dun, Wu; Kini, Akshay; Patel, Karan; Shu, Roberto; Zhang, Feng; Li, Gang; Jin, Qinghui; Fu, Jianping

2015-01-01

Multilayer assembly is a commonly used technique to construct multilayer polydimethylsiloxane (PDMS)-based microfluidic devices with complex 3D architecture and connectivity for large-scale microfluidic integration. Accurate alignment of structure features on different PDMS layers before their permanent bonding is critical in determining the yield and quality of assembled multilayer microfluidic devices. Herein, we report a custom-built desktop aligner capable of both local and global alignments of PDMS layers covering a broad size range. Two digital microscopes were incorporated into the aligner design to allow accurate global alignment of PDMS structures up to 4 in. in diameter. Both local and global alignment accuracies of the desktop aligner were determined to be about 20 μm cm−1. To demonstrate its utility for fabrication of integrated multilayer PDMS microfluidic devices, we applied the desktop aligner to achieve accurate alignment of different functional PDMS layers in multilayer microfluidics including an organs-on-chips device as well as a microfluidic device integrated with vertical passages connecting channels located in different PDMS layers. Owing to its convenient operation, high accuracy, low cost, light weight, and portability, the desktop aligner is useful for microfluidic researchers to achieve rapid and accurate alignment for generating multilayer PDMS microfluidic devices. PMID:26233409

Relevant signs of stable and unstable thoracolumbar vertebral column trauma

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

Gehweiler, J.A.; Daffner, R.H.; Osborne, R.L.

1981-12-01

One-hundred and seventeen patients with acute thoracolumbar vertebral column fracture or fracture-dislocations were analyzed and classified into stable (36%) and unstable (64%). Eight helpful roentgen signs were observed that may serve to direct attention to serious underlying, often occult, fractures and dislocations. The changes fall into four principal groups: abnormal soft tissues, abnormal vertebral alignment, abnormal joints, and widened vertebral canal. All stable and unstable lesions showed abnormal soft tissues, while 70% demonstrated kyphosis and/or scoliosis, and an abnormal adjacent intervertebral disk space. All unstable lesions showed one or more of the following signs: displaced vertebra, widened interspinous space, abnormalmore » apophyseal joint(s), and widened vertebral canal.« less

Growing Carbon Nanotubes

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

None

In situ transmission electron microscope (TEM) video (accelerated 10 times) of nucleation and self-organization of a high-density carbon nanotube network from catalytic iron nanoparticles, forming a vertically aligned forest.

Evaluation of three imaging techniques for the detection of vertical root fractures in the absence and presence of gutta-percha root fillings.

PubMed

Khedmat, S; Rouhi, N; Drage, N; Shokouhinejad, N; Nekoofar, M H

2012-11-01

To compare the accuracy of digital radiography (DR), multidetector computed tomography (MDCT) and cone beam computed tomography (CBCT) in detecting vertical root fractures (VRF) in the absence and presence of gutta-percha root filling. The root canals of 100 extracted human single-rooted teeth were prepared and randomly divided into four groups: two experimental groups with artificially fractured root and two intact groups as controls. In one experimental and one control group, a size 40, 0.04 taper gutta-percha cone was inserted in the root canals. Then DR, MDCT and CBCT were performed and the images evaluated. Statistical analyses of sensitivity, specificity and accuracy of each imaging technique in the presence and absence of gutta-percha were calculated and compared. In the absence of gutta-percha, the specificity of DR, MDCT and CBCT was similar. CBCT was the most accurate and sensitive imaging technique (P < 0 .05). In the presence of gutta-percha, the accuracy of MDCT was higher than the other imaging techniques (P < 0.05). The sensitivity of CBCT and MDCT was significantly higher than that of DR (P < 0.05), whereas CBCT was the least specific technique. Under the conditions of this ex vivo study, CBCT was the most sensitive imaging technique in detecting vertical root fracture. The presence of gutta-percha reduced the accuracy, sensitivity and specificity of CBCT but not MDCT. The sensitivity of DR was reduced in the presence of gutta-percha. The use of MDCT as an alternative technique may be recommended when VRF are suspected in root filled teeth. However, as the radiation dose of MDCT is higher than CBCT, the technique could be considered at variance with the principles of ALARA. © 2012 International Endodontic Journal.

Development of a new semi-analytical model for cross-borehole flow experiments in fractured media

USGS Publications Warehouse

Roubinet, Delphine; Irving, James; Day-Lewis, Frederick D.

2015-01-01

Analysis of borehole flow logs is a valuable technique for identifying the presence of fractures in the subsurface and estimating properties such as fracture connectivity, transmissivity and storativity. However, such estimation requires the development of analytical and/or numerical modeling tools that are well adapted to the complexity of the problem. In this paper, we present a new semi-analytical formulation for cross-borehole flow in fractured media that links transient vertical-flow velocities measured in one or a series of observation wells during hydraulic forcing to the transmissivity and storativity of the fractures intersected by these wells. In comparison with existing models, our approach presents major improvements in terms of computational expense and potential adaptation to a variety of fracture and experimental configurations. After derivation of the formulation, we demonstrate its application in the context of sensitivity analysis for a relatively simple two-fracture synthetic problem, as well as for field-data analysis to investigate fracture connectivity and estimate fracture hydraulic properties. These applications provide important insights regarding (i) the strong sensitivity of fracture property estimates to the overall connectivity of the system; and (ii) the non-uniqueness of the corresponding inverse problem for realistic fracture configurations.

Treatment of Pediatric Condylar Fractures: A 20-Year Experience.

PubMed

Ghasemzadeh, Ali; Mundinger, Gerhard S; Swanson, Edward W; Utria, Alan F; Dorafshar, Amir H

2015-12-01

The purpose of this study was to define patterns of injury and treatment for condylar and subcondylar fractures and evaluate short-term outcomes in the pediatric population. A retrospective chart review was performed on pediatric patients with mandibular condylar fractures who presented between 1990 and 2010. Computed tomographic imaging was reviewed for all patients to assess fracture characteristics. Mandibular fractures were codified using the Strasbourg Osteosynthesis Research Group and Lindahl classification methods. Sixty-four patients with 92 condylar fractures were identified. Of these patients, 29 had isolated condylar fracture and 35 had a condylar fracture associated with an additional mandibular arch fracture. The most common fracture patterns were diacapitular fracture in the Strasbourg Osteosynthesis Research Group system (n = 46) and vertical condylar head fracture in the Lindahl system (n = 14). Condylar fracture with additional mandibular arch fractures were treated with maxillomandibular fixation more often than patients with condylar fracture [n = 40 (74.1 percent) versus n = 14 (25.9 percent); p = 0.004]. No condylar fracture was treated in an open fashion. Forty-three patients returned for follow-up. The median follow-up period was 81 days (interquartile range, 35 to 294 days). Ten patients had complications (23.3 percent). The most common complication was malocclusion (n = 5). Nine of 10 patients with complications had condylar fracture with an additional mandibular arch fracture. Closed treatment of condylar fractures yields satisfactory results in pediatric patients. Pediatric patients with condylar fractures combined with additional arch fractures experience a higher rate of unfavorable outcomes.

Surface fault slip associated with the 2004 Parkfield, California, earthquake

USGS Publications Warehouse

Rymer, M.J.; Tinsley, J. C.; Treiman, J.A.; Arrowsmith, J.R.; Ciahan, K.B.; Rosinski, A.M.; Bryant, W.A.; Snyder, H.A.; Fuis, G.S.; Toke, N.A.; Bawden, G.W.

2006-01-01

Surface fracturing occurred along the San Andreas fault, the subparallel Southwest Fracture Zone, and six secondary faults in association with the 28 September 2004 (M 6.0) Parkfield earthquake. Fractures formed discontinuous breaks along a 32-km-long stretch of the San Andreas fault. Sense of slip was right lateral; only locally was there a minor (1-11 mm) vertical component of slip. Right-lateral slip in the first few weeks after the event, early in its afterslip period, ranged from 1 to 44 mm. Our observations in the weeks following the earthquake indicated that the highest slip values are in the Middle Mountain area, northwest of the mainshock epicenter (creepmeter measurements indicate a similar distribution of slip). Surface slip along the San Andreas fault developed soon after the mainshock; field checks in the area near Parkfield and about 5 km to the southeast indicated that surface slip developed more than 1 hr but generally less than 1 day after the event. Slip along the Southwest Fracture Zone developed coseismically and extended about 8 km. Sense of slip was right lateral; locally there was a minor to moderate (1-29 mm) vertical component of slip. Right-lateral slip ranged from 1 to 41 mm. Surface slip along secondary faults was right lateral; the right-lateral component of slip ranged from 3 to 5 mm. Surface slip in the 1966 and 2004 events occurred along both the San Andreas fault and the Southwest Fracture Zone. In 1966 the length of ground breakage along the San Andreas fault extended 5 km longer than that mapped in 2004. In contrast, the length of ground breakage along the Southwest Fracture Zone was the same in both events, yet the surface fractures were more continuous in 2004. Surface slip on secondary faults in 2004 indicated previously unmapped structural connections between the San Andreas fault and the Southwest Fracture Zone, further revealing aspects of the structural setting and fault interactions in the Parkfield area.

Development of a Comprehensive Neck Injury Criterion for Aircraft-Related Incidences

DTIC Science & Technology

1995-02-15

flight into ground because of distraction in cockpit. No attempt to eject, multiple extreme injuries. 38B 2 Multiple extreme FATAL; FATAL A-37B. Pilot...hypesthesia and hypalesthesia to the level of the lesion. (Reference 26) Pillar fracture A vertical fracture of the articular pillar (mass) resulting...from an Extension impaction of the involved mass by the ipsilateral superior (Hyperextension) articular mass during hyperextension and rotation. with

Recent Earthquakes Mark the Onset of Induced Seismicity in Northeastern Pennsylvania

NASA Astrophysics Data System (ADS)

Martone, P.; Nikulin, A.; Pietras, J.

2017-12-01

The link between induced seismicity and injection of hydraulic fracturing wastewater has largely been accepted and corroborated through case studies in Colorado, Arkansas, Texas, and Oklahoma. To date, induced seismicity has largely impacted hydrocarbon-producing regions in the Central United States, while the seismic response in Eastern states, like Pennsylvania, has been relatively muted. In recent years, Pennsylvania exponentially increased hydrocarbon production from the Marcellus and Utica Shales and our results indicate that this activity has triggered an onset of induced seismicity in areas of the state where no previous seismic activity was reported. Three recent earthquakes in Northeastern Pennsylvania directly correlate to hydraulic fracturing activity, though USGS NEIC earthquake catalog locations have vertical errors up to 31km. We present signal analysis results of recorded waveforms of the three identified events and results of a high-precision relocation effort and improvements to the regional velocity model aimed at constraining the horizontal and vertical error in hypocenter position. We show that at least one event is positioned directly along the wellbore track of an active well and correlate its timing to the hydraulic fracturing schedule. Results show that in the absence of wastewater disposal in this area, it is possible to confidently make the connection between the hydraulic fracturing process and induced seismicity.

Effect of different intraorifice barriers on the fracture resistance of roots obturated with Resilon or gutta-percha.

PubMed

Nagas, Emre; Uyanik, Ozgur; Altundasar, Emre; Durmaz, Veli; Cehreli, Zafer C; Vallittu, Pekka K; Lassila, Lippo V J

2010-06-01

This study investigated and compared the root reinforcement potential of 3 different intraorifice barriers (mineral trioxide aggregate [MTA], resin-modified glass ionomer cement [Vitremer], and fiber-reinforced composite [FRC]) placed over root canals obturated with gutta-percha or Resilon. Crowns of 80 extracted human mandibular premolars were sectioned off to obtain 14-mm-long root specimens. After preparation of root canals with nickel-titanium rotary files, the roots were obturated with either the Resilon/Epiphany system or gutta-percha + AH Plus sealer. In both obturation groups, specimens were further subgrouped with respect to the intraorifice barrier material placed after removal of 3-mm coronal portion of the root fillings: (1) MTA, (2) Vitremer, and (3) FRC. The specimens were loaded vertically at 1 mm/min crosshead speed until vertical root fracture occurred. Results were evaluated statistically with two-way analysis of variance and Tukey tests. Fracture resistance of roots was significantly affected by the type of intraorifice barrier (P < .05), but not by the type of obturation system used (P > .05). The use of Vitremer and FRC significantly improved the fracture resistance, whereas MTA did not exhibit any reinforcing effect as an intraorifice barrier. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

A lower border augmentation technique to allow implant placement after a bilateral mandibular fracture as a complication of vertical distraction osteogenesis: a case report.

PubMed

Perdijk, F B T; Meijer, G J; Soehardi, A; Koole, R

2013-07-01

As with other techniques, vertical distraction osteogenesis (VDO) can also induce complications. The case of a patient with a residual alveolar ridge in the symphyseal area of 8 mm is presented. After performing VDO, the patient returned at 1-day postoperatively complaining of pain and dislocation of the distractor device, due to a fracture of the lower mandibular segment on the right side. After removal of the distractor device and application of osteosynthesis plates, the patient returned 2 weeks later due to a second fracture of the lower segment, yet on the left side. After removing the osteosynthesis material, stabilization of the mandible was achieved with an acrylic splint, which was fixated with peri-mandibular wiring. Finally, reconstruction was accomplished by lower border onlay grafting, limited to the symphyseal area, in preparation for implant insertion. Ultimately, after a healing period of 5 months, two endosseous implants were installed. The patient's function has remained satisfactory for 3 years. Reinforcement of the extreme resorbed edentulous mandible after fracture healing by lower border bone augmentation can be a reliable method to allow implant installation in a second stage. Copyright © 2013 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Tectonic Setting and Characteristics of Natural Fractures in MesaVerde and Dakota Reservoirs of the San Juan Basin

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

LORENZ,JOHN C.; COOPER,SCOTT P.

2000-12-20

The Cretaceous strata that fill the San Juan Basin of northwestern New Mexico and southwestern Colorado were shortened in a generally N-S to NN13-SSW direction during the Laramide orogeny. This shortening was the result of compression of the strata between southward indentation of the San Juan Uplift at the north edge of the basin and northward to northeastward indentation of the Zuni Uplift from the south. Right-lateral strike-slip motion was concentrated at the eastern and western basin margins of the basin to form the Hogback Monocline and the Nacimiento Uplift at the same time, and small amounts of shear maymore » have been pervasive within the basin as well. Vertical extension fractures, striking N-S to NNE-SSW with local variations (parallel to the Laramide maximum horizontal compressive stress), formed in both Mesaverde and Dakota sandstones under this system, and are found in outcrops and in the subsurface of the San Juan Basin. The immature Mesaverde sandstones typically contain relatively long, irregular, vertical extension fractures, whereas the quartzitic Dakota sandstones contain more numerous, shorter, sub-parallel, closely spaced, extension fractures. Conjugate shear planes in several orientations are also present locally in the Dakota strata.« less

Evaluation of geophysical logs, Phase II, November 1998 to May 1999, at Crossley Farms Superfund Site, Berks County, Pennsylvania

USGS Publications Warehouse

Conger, Randall W.

2000-01-01

Between November 1998 and May 1999, geophysical logging was conducted in 29 boreholes at the Crossley Farms Superfund Site, Hereford Township, Berks County, Pa., to determine the fluidproducing zones, fluid-receiving zones, zones of vertical borehole flow, and casing depth. The wells range in depth from 96 to 500 feet below land surface. Gamma logs only were collected in three bedrock wells. The geophysical logging determined the placement of well screens and packers, which allow monitoring and sampling of water-bearing zones in the fractured bedrock so that the horizontal and vertical distribution of contaminated ground water migrating from known sources could be determined. Geophysical logging included collection of caliper, video, fluid-temperature, fluid-resistivity, single-point-resistance, natural-gamma, fluid-flow, and acoustic-televiewer logs. Caliper and video logs were used to locate fractures, joints, and weathered zones. Inflections on fluidtemperature and fluid-resistivity logs indicated possible water-bearing fractures, and flowmeter measurements verified these locations. Single-point-resistance and natural-gamma logs provided information on stratigraphy. After interpretation of geophysical, video logs, and drillers notes, 24 of the wells were reconstructed such that water levels can be monitored and water samples collected from discrete water-bearing fractures in each well.

Conformal atomic layer deposition of alumina on millimeter tall, vertically-aligned carbon nanotube arrays.

PubMed

Stano, Kelly L; Carroll, Murphy; Padbury, Richard; McCord, Marian; Jur, Jesse S; Bradford, Philip D

2014-11-12

Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substrates with conformal and precisely controlled thin films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs) with lengths up to 1.5 mm were conformally coated with alumina from base to tip. The nucleation and growth behaviors of Al2O3 ALD precursors on the MWCNTs were studied as a function of CNT surface chemistry. CNT surfaces were modified through a series of post-treatments including pyrolytic carbon deposition, high temperature thermal annealing, and oxygen plasma functionalization. Conformal coatings were achieved where post-treatments resulted in increased defect density as well as the extent of functionalization, as characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Using thermogravimetric analysis, it was determined that MWCNTs treated with pyrolytic carbon and plasma functionalization prior to ALD coating were more stable to thermal oxidation than pristine ALD coated samples. Functionalized and ALD coated arrays had a compressive modulus more than two times higher than a pristine array coated for the same number of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed that Al2O3 could be uniformly deposited through the entire thickness of the vertically aligned MWCNT array by manipulating sample orientation and mounting techniques. Following the ALD coating, the MWCNT arrays demonstrated hydrophilic wetting behavior and also exhibited foam-like recovery following compressive strain.

A vertically aligned carbon nanotube-based impedance sensing biosensor for rapid and high sensitive detection of cancer cells.

PubMed

Abdolahad, Mohammad; Taghinejad, Mohammad; Taghinejad, Hossein; Janmaleki, Mohsen; Mohajerzadeh, Shams

2012-03-21

A novel vertically aligned carbon nanotube based electrical cell impedance sensing biosensor (CNT-ECIS) was demonstrated for the first time as a more rapid, sensitive and specific device for the detection of cancer cells. This biosensor is based on the fast entrapment of cancer cells on vertically aligned carbon nanotube arrays and leads to mechanical and electrical interactions between CNT tips and entrapped cell membranes, changing the impedance of the biosensor. CNT-ECIS was fabricated through a photolithography process on Ni/SiO(2)/Si layers. Carbon nanotube arrays have been grown on 9 nm thick patterned Ni microelectrodes by DC-PECVD. SW48 colon cancer cells were passed over the surface of CNT covered electrodes to be specifically entrapped on elastic nanotube beams. CNT arrays act as both adhesive and conductive agents and impedance changes occurred as fast as 30 s (for whole entrapment and signaling processes). CNT-ECIS detected the cancer cells with the concentration as low as 4000 cells cm(-2) on its surface and a sensitivity of 1.7 × 10(-3)Ω cm(2). Time and cell efficiency factor (TEF and CEF) parameters were defined which describe the sensor's rapidness and resolution, respectively. TEF and CEF of CNT-ECIS were much higher than other cell based electrical biosensors which are compared in this paper.

Size-tunable band alignment and optoelectronic properties of transition metal dichalcogenide van der Waals heterostructures

NASA Astrophysics Data System (ADS)

Zhao, Yipeng; Yu, Wangbing; Ouyang, Gang

2018-01-01

2D transition metal dichalcogenide (TMDC)-based heterostructures exhibit several fascinating properties that can address the emerging market of energy conversion and storage devices. Current achievements show that the vertical stacked TMDC heterostructures can form type II band alignment and possess significant optoelectronic properties. However, a detailed analytical understanding of how to quantify the band alignment and band offset as well as the optimized power conversion efficiency (PCE) is still lacking. Herein, we propose an analytical model to exhibit the PCEs of TMDC van der Waals (vdW) heterostructures and explore the intrinsic mechanism of photovoltaic conversion based on the detailed balance principle and atomic-bond-relaxation correlation mechanism. We find that the PCE of monolayer MoS2/WSe2 can be up to 1.70%, and that of the MoS2/WSe2 vdW heterostructures increases with thickness, owing to increasing optical absorption. Moreover, the results are validated by comparing them with the available evidence, providing realistic efficiency targets and design principles. Highlights • Both electronic and optoelectronic models are developed for vertical stacked MoS2/WSe2 heterostructures. • The underlying mechanism on size effect of electronic and optoelectronic properties for vertical stacked MoS2/WSe2 heterostructures is clarified. • The macroscopically measurable quantities and the microscopical bond identities are connected.

Laser device

DOEpatents

Scott, Jill R.; Tremblay, Paul L.

2008-08-19

A laser device includes a virtual source configured to aim laser energy that originates from a true source. The virtual source has a vertical rotational axis during vertical motion of the virtual source and the vertical axis passes through an exit point from which the laser energy emanates independent of virtual source position. The emanating laser energy is collinear with an orientation line. The laser device includes a virtual source manipulation mechanism that positions the virtual source. The manipulation mechanism has a center of lateral pivot approximately coincident with a lateral index and a center of vertical pivot approximately coincident with a vertical index. The vertical index and lateral index intersect at an index origin. The virtual source and manipulation mechanism auto align the orientation line through the index origin during virtual source motion.

Is there a role for intramedullary nails in the treatment of simple pilon fractures? Rationale and preliminary results.

PubMed

Marcus, Matthew S; Yoon, Richard S; Langford, Joshua; Kubiak, Erik N; Morris, Andrew J; Koval, Kenneth J; Haidukewych, George J; Liporace, Frank A

2013-08-01

Certain patients with pilon fractures present with significant soft-tissue swelling or with a poor soft-tissue envelope typically not amenable to definitive fixation in the early time period. The objective of this study was to review the treatment of simple intra-articular fractures of the tibial plafond (Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) type 43C1-C2) via intramedullary nailing (IMN) with the assessment of clinical and radiographic results and any associated complications. Retrospective clinical and radiological reviews of 31 patients sustaining AO/OTA type 43C distal tibial fractures treated with IMN were evaluated. Our main outcome measurement included achievable alignment in the immediate postoperative period and at the time of union along with complications or need for secondary procedures within the first year of follow-up. Seven patients were lost to follow-up. All the remaining patients achieved bony union at a mean union time of 14.1 ± 4.9 weeks with no evidence of malunion or malrotation. All patients were at full-weight-bearing status at 1-year follow-up. Complications were notable for one delayed union, one non-union, one patient with superficial wound drainage, two with deep infection, one with symptomatic hardware and one with deep vein thrombosis. Simple articular fractures of the tibial plafond (AO/OTA type 43C) treated via IMN can achieve excellent alignment and union rates with proper patient selection and surgical indication. One should not hesitate to use additional bone screws or plating options to help achieve better anatomic reduction. However, larger, prospective randomised trials comparing plating versus nailing, in experienced hands, are needed to completely delineate the utility of this treatment modality. Copyright © 2013 Elsevier Ltd. All rights reserved.

Correlating Scatter in Fatigue Life with Fracture Mechanisms in Forged Ti-6242Si Alloy

NASA Astrophysics Data System (ADS)

Sinha, V.; Pilchak, A. L.; Jha, S. K.; Porter, W. J.; John, R.; Larsen, J. M.

2018-04-01

Unlike the quasi-static mechanical properties, such as strength and ductility, fatigue life can vary significantly (by an order of magnitude or more) for nominally identical material and test conditions in many materials, including Ti-alloys. This makes life prediction and management more challenging for components that are subjected to cyclic loading in service. The differences in fracture mechanisms can cause the scatter in fatigue life. In this study, the fatigue fracture mechanisms were investigated in a forged near- α titanium alloy, Ti-6Al-2Sn-4Zr-2Mo-0.1Si, which had been tested under a condition that resulted in life variations by more than an order of magnitude. The crack-initiation and small crack growth processes, including their contributions to fatigue life variability, were elucidated via quantitative characterization of fatigue fracture surfaces. Combining the results from quantitative tilt fractography and electron backscatter diffraction, crystallography of crack-initiating and neighboring facets on the fracture surface was determined. Cracks initiated on the surface for both the shortest and the longest life specimens. The facet plane in the crack-initiating grain was aligned with the basal plane of a primary α grain for both the specimens. The facet planes in grains neighboring the crack-initiating grain were also closely aligned with the basal plane for the shortest life specimen, whereas the facet planes in the neighboring grains were significantly misoriented from the basal plane for the longest life specimen. The difference in the extent of cracking along the basal plane can explain the difference in fatigue life of specimens at the opposite ends of scatter band.

Comparative study of single lateral locked plating versus double plating in type C bicondylar tibial plateau fractures.

PubMed

Neogi, Devdatta Suhas; Trikha, Vivek; Mishra, Kaushal Kant; Bandekar, Shivanand M; Yadav, Chandra Shekhar

2015-01-01

Bicondylar tibial plateau fractures are complex injuries and treatment is challenging. Ideal method is still controversial with risk of unsatisfactory results if not treated properly. Many different techniques of internal and external fixation are used. This study compares the clinical results in single locked plating versus dual plating (DP) using two incision approaches. Our hypothesis was that DP leads to less collapse and change in alignment at final followup compared with single plating. 61 cases of Type C tibial plateau fractures operated between January 2007 and June 2011 were included in this prospective study. All cases were operated either by single lateral locked plate by anterolateral approach or double plating through double incision. All cases were followed for a minimum of 24 months radiologically and clinically. The statistical analysis was performed using software SPSS 10.0 to analyze the data. Twenty nine patients in a single lateral locked plate and 32 patients in a double plating group were followed for minimum 2 years. All fractures healed, however there was a significant incidence of malalignment in the single lateral plating group. Though there was a significant increase in soft tissue issues with the double plating group; however, there was only 3.12% incidence of deep infection. There was no significant difference in Hospital for special surgery score at 2 years followup. Double plating through two incisions resulted in a better limb alignment and joint reduction with an acceptable soft tissue complication rate.

The nature of fracturing and stress distribution in quartzite around the 1128-M (3700-FT) level of the crescent mine, Coeur d'Alene mining district, Idaho

USGS Publications Warehouse

Miller, C.H.; Skinner, E.H.

1980-01-01

Silver and copper are the principal ores mined from the quartzite at the Crescent mine. Both the main ore-bearing veins and foliation in the quartzite are parallel to the nearly vertical formational contacts. Anisotropy of the quartzite is indicated by both dynamic and static tests. Disking and breakage of core from holes perpendicular to the foliation are about twice what they are in core from holes parallel to foliation. Natural cleavage as well as slabbing and blasting fractures around the tunnels are also controlled by the foliation. Extensive overcore deformation measurements indicate that most of the influence of the tunnels on the "free" stress field is between the rib and a depth of 2.7 m (1 tunnel diameter). The maximum principal stress axis in the free field is nearly horizontal; its magnitude is not much greater than the vertical component and calculations indicate a nearly hydrostatic free stress field. Stress considerably greater than the free field was measured between about 0.3-2.7 m behind the rib and is caused by a transfer of load from above the tunnel opening. Peak stress is in the vertical direction and about 1.7 m behind the rib. An air-injection survey shows that high permeabilities are confined to the highly fractured annulus around a tunnel to a depth of at least 0.6 m. Air-injection measurements could be taken in the interval of about 0.6-1.8 m, but more fractures with high permeabilities may also be present in the annulus from about 0.6-1.2 m. Permeabilities measured deeper than about 1.8 m by the air-injection technique are either very low or nonexistent. The absence of open and noncontinuous fractures beyond about 1.8 m is also indicated by very low porosities and permeabilities of core, very high stresses (which presumably would close fractures), the lack of stains or secondary fillings in disking fractures, a conspicuous lack of ground water in the tunnels, and the fact that fractures encountered in an experimental 0.9-m tunnel did not extend into the 1.8-m tunnel that was mined over it. Air-injection techniques exceed the accuracy of any field deformation measurement now in use, and they are sensitive to permeabilities as small as one microdarcy and to fracture widths as small as 250 nanometers. This technique was applied for future reference in mining design and, perhaps, to be used later to detect microfracturing prior to rockbursts. ?? 1980 Elsevier Scientific Publishing Company.

Characterization of a remotely intersected set of hydraulic fractures: Results of intersection well no. 1-B, GRI/DOE multi-site project

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

Branagan, P.T.; Peterson, R.E.; Warpinski, N.R.

A deviated observation or {open_quotes}intersection{close_quotes} well (IW 1-B) was drilled, cored, logged and tested through an area in a fluvial sandstone reservoir that had previously been hydraulically fractured. The point of intersection with the fractured interval was located 126 ft from the fracture well along one wing of the fracture(s) at a measured depth of 4,675 ft. Direct observations from core and borehole imagery logs in IW 1-B indicate that a total of 11 far-field vertical fractures were created. Clustered in a narrow 2.6-ft-wide interval, these 11 fractures are the direct result of 6 experimental fracture treatments executed in themore » distant frac well over a 4-month period. Diagnostic data acquired through IW I-B included direct core observations and measurements, borehole log imagery, gamma ray (GR) tracer identification, well-to-well pressure transient and fracture conductivity tests, and production logging surveys. The explicit intent in the emplacement of IW 1-B was to provide direct observations and information to characterize the hydraulic fracture(s) in support of a remote-sensing fracture diagnostic program that included microseismic monitoring and inclinometer measurements.« less

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

Lorenz, J.C.; Warpinski, N.R.; Sattler, A.R.

A model is presented that suggests that regional fracture systems commonly control permeability in flat-lying reservoirs. Such fractures are distributed in a continuum of sizes and occur in subparallel, en echelon patterns. Few high-angle, orthogonal fractures exist because this system is created by high pore pressures and relatively low differential horizontal (tectonic) stresses rather than by significant structural deformation. Interfracture communication occurs primarily at infrequent, low-angle intersections of fractures. Vertical continuity of such fractures through a reservoir commonly is limited to the numerous lithologic discontinuities inherent in nonmarine sandstones. This type of fracture system has been documented in Mesaverede rocksmore » in the Rulison field of the Piceance Creek basin, northwestern Colorado, by studies of 4,300 ft (1310 m) of core from the U.S. DOE's three Multiwell Experiment (MWX) wells and by studies of the excellent nearby outcrops. Well test results and geologic data from core and outcrop support the model. The described natural fracture system has a significant effect on production and stimulation.« less

Is Skin Tenting Secondary to Displaced Clavicle Fracture More Than a Theoretical Risk? A Report of 2 Adolescent Cases.

PubMed

Chalmers, Peter N; Van Thiel, Geoff S; Ferry, Scott T

2015-10-01

While one traditional indication for open reduction and internal fixation (ORIF) of clavicle fractures was tenting of the skin because of concern for an impending open fracture, recent review materials indicate that this complication may only be theoretical. To the best of the authors' knowledge, this complication has never been reported for a midshaft clavicle fracture. We report 2 adolescent cases of displaced, comminuted clavicle fractures in which the skin was initially intact. Both were managed nonoperatively and both secondarily presented with open lesions at the fracture site requiring urgent irrigation and débridement and ORIF. In displaced midshaft clavicle fractures, tenting of the skin sufficient to cause subsequent violation of the soft-tissue envelope is possible and is more than a theoretical risk. At-risk patients (ie, those with a vertically angulated sharp fragment of comminution) should be counseled appropriately and observed closely or considered for primary ORIF.

Along fault friction and fluid pressure effects on the spatial distribution of fault-related fractures

NASA Astrophysics Data System (ADS)

Maerten, Laurent; Maerten, Frantz; Lejri, Mostfa

2018-03-01

Whatever the processes involved in the natural fracture development in the subsurface, fracture patterns are often affected by the local stress field during propagation. This homogeneous or heterogeneous local stress field can be of mechanical and/or tectonic origin. In this contribution, we focus on the fracture-pattern development where active faults perturb the stress field, and are affected by fluid pressure and sliding friction along the faults. We analyse and geomechanically model two fractured outcrops in UK (Nash Point) and in France (Les Matelles). We demonstrate that the observed local radial joint pattern is best explained by local fluid pressure along the faults and that observed fracture pattern can only be reproduced when fault friction is very low (μ < 0.2). Additionally, in the case of sub-vertical faults, we emphasize that the far field horizontal stress ratio does not affect stress trajectories, or fracture patterns, unless fault normal displacement (dilation or contraction) is relatively large.

Groundwater circulation and geochemistry of a karstified bank marginal fracture system, South Andros Island, Bahamas

NASA Astrophysics Data System (ADS)

Whitaker, Fiona F.; Smart, Peter L.

1997-10-01

On the east coast of South Andros Island, Bahamas, a major bank-marginal fracture system characterised by vertically extensive cavern systems (blue holes) is developed sub-parallel to the steep-sided deep-water re-entrant of the Tongue of the Ocean. In addition to providing a discharge route for meteoric, mixed and geochemically evolved saline groundwaters, a strong local circulation occurs along the fracture system. This generates enhanced vertical mixing within voids of the fracture system, evidenced by the increasing mixing zone thickness, and the thinning and increasing salinity of brackish lens waters from north to south along the fracture system. Furthermore, tidally driven pumping of groundwaters occurs between the fracture and adjacent carbonate aquifer affecting a zone up to 200 m either side of the fracture. The resultant mixing of groundwaters of contrasting salinity and PCO 2 within and along the fracture system and with the surrounding aquifer waters, together with bacterial oxidation of organic matter, generates significant potential for locally enhanced diagenesis. Undersaturation with respect to calcite within the fresh (or brackish)-salt water mixing zone is observed in the fracture system and predicted in the adjacent aquifer, while mixing between the brackish fracture lens and surrounding high PCO 2 fresh waters causes dissolution of aragonite but not calcite. The latter gives rise to considerable secondary porosity development, because active tidal pumping ensures continued renewal of dissolutional potential. This is evidenced by calcium and strontium enrichment in the brackish lens which indicates porosity generation by aragonite dissolution at a maximum rate of 0.35% ka -1, up to twice the average estimated for the fresh water lens. In contrast saline groundwaters are depleted in calcium relative to open ocean waters suggesting the formation of calcite cements. The development of a major laterally continuous cavernous fracture zone along the margin of the carbonate platform permits enhanced groundwater flow and mixing which may result in generation of a diagenetic `halo' at a scale larger than that generally recognised around syn-sedimentary fractures in fossil carbonates. This may be characterised by increased secondary porosity where a relative fall in sea-level results in exposure and formation of a meteoric groundwater system, or cementation by `marine' calcite both below this meteoric system, and where the bank surface is flooded by seawater.