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Sample records for implanted detection structures

  1. Detection of degradation in polyester implants by analysing mode shapes of structure vibration.

    PubMed

    Samami, Hassan; Pan, Jingzhe

    2016-09-01

    This paper presents a numerical study on using vibration analysis to detect degradation in degrading polyesters. A numerical model of a degrading plate sample is considered. The plate is assumed to degrade following the typical behaviour of amorphous copolymers of polylactide and polyglycolide. Due to the well-known autocatalytic effect in the degradation of these polyesters, the inner core of the plate degrades faster than outer surface region, forming layers of materials with varying Young׳s modulus. Firstly the change in molecular weight and corresponding change in Young׳s modulus at different times are calculated using the mathematical models developed in our previous work. Secondly the first four mode shapes of transverse vibration of the plate are calculated using the finite element method. Finally the curvature of the mode shapes are calculated and related to the spatial distribution of the polymer degradation. It is shown that the curvature of the mode shapes can be used to detect the onset and distribution of polymer degradation. The level of measurement accuracy required in an experiment is presented to guide practical applications of the method. At the end of this paper a demonstration case of coronary stent is presented showing how the method can be used to detect degradation in an implant of sophisticated structure. PMID:27235780

  2. Detection of Acoustic Temporal Fine Structure by Cochlear Implant Listeners: Behavioral Results and Computational Modeling

    PubMed Central

    Imennov, Nikita S.; Won, Jong Ho; Drennan, Ward R.; Jameyson, Elyse; Rubinstein, Jay T.

    2013-01-01

    A test of within-channel detection of acoustic temporal fine structure (aTFS) cues is presented. Eight cochlear implant listeners (CI) were asked to discriminate between two Schroeder-phase (SP) complexes using a two-alternative, forced-choice task. Because differences between the acoustic stimuli are primarily constrained to their aTFS, successful discrimination reflects a combination of the subjects’ perception of and the strategy’s ability to deliver aTFS cues. Subjects were mapped with single-channel Continuous Interleaved Sampling (CIS) and Simultaneous Analog Stimulation (SAS) strategies. To compare within- and across- channel delivery of aTFS cues, a 16-channel clinical HiRes strategy was also fitted. Throughout testing, SAS consistently outperformed the CIS strategy (p ≤ 0.002). For SP stimuli with F0 =50 Hz, the highest discrimination scores were achieved with the HiRes encoding, followed by scores with the SAS and the CIS strategies, respectively. At 200 Hz, single-channel SAS performed better than HiRes (p = 0.022), demonstrating that under a more challenging testing condition, discrimination performance with a single-channel analog encoding can exceed that of a 16-channel pulsatile strategy. To better understand the intermediate steps of discrimination, a biophysical model was used to examine the neural discharges evoked by the SP stimuli. Discrimination estimates calculated from simulated neural responses successfully tracked the behavioral performance trends of single-channel CI listeners. PMID:23333260

  3. Injury to the coronary arteries and related structures by implantation of cardiac implantable electronic devices.

    PubMed

    Pang, Benjamin J; Barold, S Serge; Mond, Harry G

    2015-04-01

    Damage to the coronary arteries and related structures from pacemaker and implantable cardioverter-defibrillator lead implantation is a rarely reported complication that can lead to myocardial infarction and pericardial tamponade that may occur acutely or even years later. We summarize the reported cases of injury to coronary arteries and related structures and review the causes of troponin elevation in the setting of cardiac implantable electronic device implantation. PMID:25564549

  4. In Vivo Ultrasonic Detection of Polyurea Crosslinked Silica Aerogel Implants

    PubMed Central

    Sabri, Firouzeh; Sebelik, Merry E.; Meacham, Ryan; Boughter, John D.; Challis, Mitchell J.; Leventis, Nicholas

    2013-01-01

    Background Polyurea crosslinked silica aerogels are highly porous, lightweight, and mechanically strong materials with great potential for in vivo applications. Recent in vivo and in vitro studies have demonstrated the biocompatibility of this type of aerogel. The highly porous nature of aerogels allows for exceptional thermal, electric, and acoustic insulating capabilities that can be taken advantage of for non-invasive external imaging techniques. Sound-based detection of implants is a low cost, non-invasive, portable, and rapid technique that is routinely used and readily available in major clinics and hospitals. Methodology In this study the first in vivo ultrasound response of polyurea crosslinked silica aerogel implants was investigated by means of a GE Medical Systems LogiQe diagnostic ultrasound machine with a linear array probe. Aerogel samples were inserted subcutaneously and sub-muscularly in a) fresh animal model and b) cadaveric human model for analysis. For comparison, samples of polydimethylsiloxane (PDMS) were also imaged under similar conditions as the aerogel samples. Conclusion/significance Polyurea crosslinked silica aerogel (X-Si aerogel) implants were easily identified when inserted in either of the regions in both fresh animal model and cadaveric model. The implant dimensions inferred from the images matched the actual size of the implants and no apparent damage was sustained by the X-Si aerogel implants as a result of the ultrasonic imaging process. The aerogel implants demonstrated hyperechoic behavior and significant posterior shadowing. Results obtained were compared with images acquired from the PDMS implants inserted at the same location. PMID:23799093

  5. Surface topographical and structural analysis of Ag+-implanted polymethylmethacrylate

    NASA Astrophysics Data System (ADS)

    Arif, Shafaq; Rafique, M. Shahid; Saleemi, Farhat; Naab, Fabian; Toader, Ovidiu; Sagheer, Riffat; Bashir, Shazia; Zia, Rehana; Siraj, Khurram; Iqbal, Saman

    2016-08-01

    Specimens of polymethylmethacrylate (PMMA) were implanted with 400-keV Ag+ ions at different ion fluences ranging from 1 × 1014 to 5 × 1015 ions/cm2 using a 400-kV NEC ion implanter. The surface topographical features of the implanted PMMA were investigated by a confocal microscope. Modifications in the structural properties of the implanted specimens were analyzed in comparison with pristine PMMA by X-ray diffraction (XRD) and Raman spectroscopy. UV-Visible spectroscopy was applied to determine the effects of ion implantation on optical transmittance of the implanted PMMA. The confocal microscopic images revealed the formation of hillock-like microstructures along the ion track on the implanted PMMA surface. The increase in ion fluence led to more nucleation of hillocks. The XRD pattern confirmed the amorphous nature of pristine and implanted PMMA, while the Raman studies justified the transformation of Ag+-implanted PMMA into amorphous carbon at the ion fluence of ⩾5 × 1014 ions/cm2. Moreover, the decrease in optical transmittance of PMMA is associated with the formation of hillocks and ion-induced structural modifications after implantation.

  6. Spectrotemporal Modulation Detection and Speech Perception by Cochlear Implant Users

    PubMed Central

    Won, Jong Ho; Moon, Il Joon; Jin, Sunhwa; Park, Heesung; Woo, Jihwan; Cho, Yang-Sun; Chung, Won-Ho; Hong, Sung Hwa

    2015-01-01

    Spectrotemporal modulation (STM) detection performance was examined for cochlear implant (CI) users. The test involved discriminating between an unmodulated steady noise and a modulated stimulus. The modulated stimulus presents frequency modulation patterns that change in frequency over time. In order to examine STM detection performance for different modulation conditions, two different temporal modulation rates (5 and 10 Hz) and three different spectral modulation densities (0.5, 1.0, and 2.0 cycles/octave) were employed, producing a total 6 different STM stimulus conditions. In order to explore how electric hearing constrains STM sensitivity for CI users differently from acoustic hearing, normal-hearing (NH) and hearing-impaired (HI) listeners were also tested on the same tasks. STM detection performance was best in NH subjects, followed by HI subjects. On average, CI subjects showed poorest performance, but some CI subjects showed high levels of STM detection performance that was comparable to acoustic hearing. Significant correlations were found between STM detection performance and speech identification performance in quiet and in noise. In order to understand the relative contribution of spectral and temporal modulation cues to speech perception abilities for CI users, spectral and temporal modulation detection was performed separately and related to STM detection and speech perception performance. The results suggest that that slow spectral modulation rather than slow temporal modulation may be important for determining speech perception capabilities for CI users. Lastly, test–retest reliability for STM detection was good with no learning. The present study demonstrates that STM detection may be a useful tool to evaluate the ability of CI sound processing strategies to deliver clinically pertinent acoustic modulation information. PMID:26485715

  7. MIS diode structure in As/+/ implanted CdS

    NASA Technical Reports Server (NTRS)

    Hutchby, J. A.

    1977-01-01

    Structure made by As implantation of carefully prepared high-conductivity CdS surfaces followed by Pt deposition and 450 C anneal display rectifying, although substantially different, I-V characteristics in the dark and during illumination with subband-gap light. Structures prepared in the same way on an unimplanted portion of the substrate have similar I-V characteristics, except that the forward turnover voltage for an illuminated unimplanted diode is much smaller than that for an implanted diode. It is suggested that the charge conduction in both structures is dominated by hole and/or electron tunneling through a metal-semiconductor potential barrier. The tunneling processes appear to be quite sensitive to subband-gap illumination, which causes the dramatic decreases of turnover voltages and apparent series resistances. The difference in turnover voltage appears to be caused by interface states between the Pt electrode and the implanted layer, which suggests a MIS model.

  8. Label-free detection of antigens using implantable SERS nanosensors

    NASA Astrophysics Data System (ADS)

    Li, Honggang; Baum, Caitlin E.; Cullum, Brian M.

    2005-11-01

    Monitoring the presence, production and transport of proteins inside individual living cells can provide vital information about cellular signaling pathways and the overall biological response of an organism. For example, cellular response to external stimuli, such as biological warfare (BW) agents, can be monitored by measuring interleukin-II (IL-2) expression inside T-cells as well as other chemical species associated with T-cell activation. By monitoring such species, pre-symptomatic detection of exposure to BW agents can be achieved, leading to significantly increased post-exposure survival rates. To accomplish such monitoring, we have developed and optimized implantable nanosphere-based nanosensors for the intracellular analysis of specific proteins in a label-free fashion. These sensors consist of 300-520 nm diameter silica spheres that have been coated with silver and antibodies to allow for trace protein detection via surface enhanced Raman spectroscopy (SERS). They have been optimized for SERS response by evaluating the size of the nanospheres best suited to 632.8 nm laser excitation, as well as the various nanosensor fabrication steps (i.e., silver deposition process, antibody binding, etc.). During usage, the presence of the specific protein of interest is monitored by either directly measuring SERS signals associated with the protein and/or changes in the SERS spectrum of the antibodies resulting from conformational changes after antigen binding. In this work, human insulin was used as a model compound for initial studies into the sensitivity of these optimized nanosensors.

  9. Sensing and detection in Medtronic implantable cardioverter defibrillators.

    PubMed

    Brown, Mark L; Swerdlow, Charles D

    2016-09-01

    Ensuring sensing and detection of ventricular tachycardia (VT) and ventricular fibrillation (VF) was a prerequisite for the clinical trials that established the survival benefit of implantable cardioverter defibrillators (ICDs). However, for decades, a high incidence of unnecessary shocks limited patients' and physicians' acceptance of ICD therapy. Oversensing, misclassification of supraventricular tachycardia (SVT) as VT, and self-terminating VT accounted for the vast majority of unnecessary shocks. Medtronic ICDs utilize sensitive baseline settings with minimal blanking periods to ensure accurate sensing of VF, VT, and SVT electrograms. Programmable algorithms reject oversensing caused by far-field R waves, T waves, and non-physiologic signals caused by lead failure. A robust hierarchy of SVT-VT discriminators minimize misclassification of SVT as VT. These features, combined with evidence-based programming, have reduced the 1‑year inappropriate shock rate to 1.5 % for dual-/triple-chamber ICDs and to 2.5 % for single-chamber ICDs. PMID:27624809

  10. Structural and magnetic properties of Co + implanted n-GaN dilute magnetic semiconductors

    NASA Astrophysics Data System (ADS)

    Husnain, G.; Tao, Fa; Yao, Shu-De

    2010-05-01

    The n-type GaN epilayer was grown on sapphire prepared by metal organic chemical vapour deposition and subsequently Co + ions implanted. The properties of Co + ions implanted GaN epilayer were investigated by structural and magnetic measurements. The results of Rutherford backscattering spectrometry and channeling illustrate that an excellent crystalline quality ( χmin=1.3%) of as-grown GaN. After the implantation of 150 keV Co + ions with dose 3×10 16 cm -2 into GaN and subsequently annealed at 700, 800 and 900 °C, no secondary phase or metal related-peaks were detected by typical XRD. In addition high-resolution X-ray diffraction (HRXRD) was performed to study structural related properties. The magnetization curves were obtained by SQUID and AGM measurements, a well-defined hysteresis loop was observed even at 300 K. The temperature dependence of magnetization was taken in FC and ZFC conditions showed the highest Curie temperature ( TC) ∼370 K recorded for Co + implanted GaN.

  11. [Tachycardia detection in implantable cardioverter-defibrillators by Sorin/LivaNova : Algorithms, pearls and pitfalls].

    PubMed

    Kolb, Christof; Ocklenburg, Rolf

    2016-09-01

    For physicians involved in the treatment of patients with implantable cardioverter-defibrillators (ICDs) the knowledge of tachycardia detection algorithms is of paramount importance. This knowledge is essential for adequate device selection during de-novo implantation, ICD replacement, and for troubleshooting during follow-up. This review describes tachycardia detection algorithms incorporated in ICDs by Sorin/LivaNova and analyses their strengths and weaknesses. PMID:27605232

  12. Using channel-specific statistical models to detect reverberation in cochlear implant stimuli.

    PubMed

    Desmond, Jill M; Collins, Leslie M; Throckmorton, Chandra S

    2013-08-01

    Reverberation is especially detrimental for cochlear implant listeners; thus, mitigating its effects has the potential to provide significant improvements to cochlear implant communication. Efforts to model and correct for reverberation in acoustic listening scenarios can be quite complex, requiring estimation of the room transfer function and localization of the source and receiver. However, due to the limited resolution associated with cochlear implant stimulation, simpler processing for reverberation detection and mitigation may be possible for cochlear implants. This study models speech stimuli in a cochlear implant on a per-channel basis both in quiet and in reverberation, and assesses the efficacy of these models for detecting the presence of reverberation. This study was able to successfully detect reverberation in cochlear implant pulse trains, and the results appear to be robust to varying room conditions and cochlear implant stimulation parameters. Reverberant signals were detected 100% of the time for a long reverberation time of 1.2 s and 86% of the time for a shorter reverberation time of 0.5 s. PMID:23927111

  13. Use of cone-beam computed tomography in early detection of implant failure.

    PubMed

    Yepes, Juan F; Al-Sabbagh, Mohanad

    2015-01-01

    Preimplant planning with complex imaging techniques has long been a recommended practice for assessing the quality and quantity of alveolar bone before dental implant placement. When maxillofacial imaging is necessary, static film or digital images lack the depth and dimension offered by computed tomography. Cone-beam computed tomography (CBCT) offers the dentist not only a radiographic volumetric view of alveolar bone but also a 3-dimensional reconstruction. This article reviews the use of CBCT for assessing implant placement and early detection of failure, and compares the performance of CBCT with that of other imaging modalities in the early detection of implant failure. PMID:25434558

  14. Structural and electrical properties of In-implanted Ge

    SciTech Connect

    Feng, R. Kremer, F.; Mirzaei, S.; Medling, S. A.; Ridgway, M. C.; Sprouster, D. J.; Decoster, S.; Glover, C. J.; Russo, S. P.

    2015-10-28

    We report on the effects of dopant concentration on the structural and electrical properties of In-implanted Ge. For In concentrations of ≤ 0.2 at. %, extended x-ray absorption fine structure and x-ray absorption near-edge structure measurements demonstrate that all In atoms occupy a substitutional lattice site while metallic In precipitates are apparent in transmission electron micrographs for In concentrations ≥0.6 at. %. Evidence of the formation of In-vacancy complexes deduced from extended x-ray absorption fine structure measurements is complimented by density functional theory simulations. Hall effect measurements of the conductivity, carrier density, and carrier mobility are then correlated with the substitutional In fraction.

  15. Structure and micro-mechanical properties of helium-implanted layer on Ti by plasma-based ion implantation

    NASA Astrophysics Data System (ADS)

    Ma, Xinxin; Li, Jinlong; Sun, Mingren

    2008-08-01

    The present paper concentrates on structure and micro-mechanical properties of the helium-implanted layer on titanium treated by plasma-based ion implantation with a pulsed voltage of -30 kV and doses of 3, 6, 9 and 12 × 10 17 ions/cm 2, respectively. X-ray photoelectron spectroscopy and transmission electron microscopy are employed to characterize the structure of the implanted layer. The hardnesses at different depths of the layer were measured by nano-indentation. We found that helium ion implantation into titanium leads to the formation of bubbles with a diameter from a few to more than 10 nm and the bubble size increases with the increase of dose. The primary existing form of Ti is amorphous in the implanted layer. Helium implantation also enhances the ingress of O, C and N and stimulates the formations of TiO 2, Ti 2O 3, TiO, TiC and TiN in the near surface layer. And the amount of the ingressed oxygen is obviously higher than those of nitrogen and carbon due to its higher activity. At the near surface layer, the hardnesses of all implanted samples increases remarkably comparing with untreated one and the maximum hardness has an increase by a factor of up to 3.7. For the samples implanted with higher doses of 6, 9 and 12 × 10 17 He/cm 2, the local displacement bursts are clearly found in the load-displacement curves. For the samples implanted with a lower dose of 3 × 10 17 He/cm 2, there is no obvious displacement burst found. Furthermore, the burst width increases with the increase of the dose.

  16. Detection of deeply implanted impedance-switching devices using ultrasound doppler.

    PubMed

    Mari, Jean Martial; Lafon, Cyril; Chapelon, Jean Yves

    2013-06-01

    Communication with and transmission of energy to remote devices, such as deeply-implanted physiological recorders, using ultrasound presents several technical problems. In particular, device detection and piezoelectric sensor targeting remains difficult. Both tasks require differentiating the device from the surrounding fully passive tissues. Like radiofrequency identification devices, ultrasonic transponders have the capacity to rapidly change the impedance of their piezoelectric elements, which modulates their backscattering coefficient and allows the device to "flash" periodically at a very low energy cost, and, in particular situations, to communicate with an external device. A method for localizing the device by interpreting this flashing as movement is presented here. An ultrasound Doppler scan sequence is implemented using a programmable scanner, and radio-frequency data are collected and processed. The data are then analyzed for different excitation lengths and flashing frequencies to determine the optimum detection parameters. Measurements show that 1) detection can be achieved and is maximal when the excitation length reaches that of the Doppler processing window, and 2) when the flashing frequency is in a specific range. A study of the incidence angle also showed that 3) the sensor of the device can be detected over a given angular window. The conclusion is that by using ultrasound color Doppler sequences, impedance-switching piezoelectric devices can be detected under the conditions provided in the present study, and can be distinguished from fully passive structures. PMID:25004471

  17. Application of collision detection to assess implant insertion in elbow replacement surgery

    NASA Astrophysics Data System (ADS)

    Tutunea-Fatan, O. Remus; Bernick, Joshua H.; Lalone, Emily; King, Graham J. W.; Johnson, James A.

    2010-02-01

    An important aspect of implant replacement of the human joint is the fit achieved between the implant and bone canal. As the implant is inserted within the medullary canal, its position and orientation is subjected to a variety of constraints introduced either by the external forces and moments applied by the surgeon or by the interaction of the implant with the cortical wall of the medullary canal. This study evaluated the implant-bone interaction of a humeral stem in elbow replacement surgery as an example, but the principles can also be applied to other joints. After converting CT scan data of the humerus to the parametric NURBS-based representation, a collision detection procedure based on existing Computer-Aided Engineering techniques was employed to control the instantaneous kinematics and dynamics of the insertion of a humeral implant in an attempt to determine its final posture within the canal. By measuring the misalignment between the native flexion-extension (FE) axis of the distal humerus and the prosthesis, a prediction was made regarding the fit between the canal and the implant. This technique was shown to be effective in predicting the final misalignment of the implant axis with respect to the native FE axis of the distal humerus using a cadaver specimen for in-vitro validation.

  18. Assessing the hierarchical structure of titanium implant surfaces.

    PubMed

    Matteson, Jesse L; Greenspan, David C; Tighe, Timothy B; Gilfoy, Nathan; Stapleton, Joshua J

    2016-08-01

    The physical texture of implant surfaces are known to be one important factor in creating a stable bone-implant interface. Simple roughness parameters (for e.g., Sa or Sz) are not entirely adequate when characterizing surfaces possessing hierarchical structure (macro, micro, and nano scales). The aim of this study was to develop an analytical approach to quantify hierarchical surface structure of implant surfaces possessing nearly identical simple roughness. Titanium alloys with macro/micro texture (MM) and macro/micro/nano texture (MMN) were chosen as model surfaces to be evaluated. There was no statistical difference (p > 0.05) in either Sa (13.56 vs. 13.43 µm) or Sz (91.74 vs. 92.39 µm) for the MM and MMN surfaces, respectively. However, when advanced filtering algorithms were applied to these datasets, a statistical difference in roughness was found between MM (Sa = 0.54 µm) and MMN (Sa = 1.06 µm; p < 0.05). Additionally, a method was developed to specifically quantify the density of surface features appearing similar in geometry to natural osteoclastic pits. This analysis revealed a significantly greater numbers of these features (i.e., valleys) on the MMN surface as compared to the MM surface. Finally, atomic force microscopy showed a rougher nano-texture on the MMN surface compared with the MM surface (p < 0.05). The results support recent published studies that show a combination of appropriate micron and nano surface results in a more robust cellular response and increased osteoblast differentiation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1083-1090, 2016. PMID:26034005

  19. Influence of the chemical nature of implanted ions on the structure of a silicon layer damaged by implantation

    SciTech Connect

    Shcherbachev, K. D. Voronova, M. I.; Bublik, V. T.; Mordkovich, V. N. Pazhin, D. M.; Zinenko, V. I.; Agafonov, Yu. A.

    2013-12-15

    The influence of the implantation of silicon single crystals by fluorine, nitrogen, oxygen, and neon ions on the distribution of strain and the static Debye-Waller factor in the crystal lattice over the implanted-layer depth has been investigated by high-resolution X-ray diffraction. The density depth distribution in the surface layer of native oxide has been measured by X-ray reflectometry. Room-temperature implantation conditions have ensured the equality of the suggested ranges of ions of different masses and the energies transferred by them to the target. It is convincingly shown that the change in the structural parameters of the radiation-damaged silicon layer and the native oxide layer depend on the chemical activity of the implanted ions.

  20. Detection and manipulation of sychronization processes during depth electrode implantation

    NASA Astrophysics Data System (ADS)

    Schiek, Michael; Zimmermann, Egon; Freund, Hans-Joachim; Sturm, Volker; Tass, Peter

    2002-03-01

    Population of phase oscillators can effectively be desynchronized with composite stimulation techniques using stochastic phase resetting principles [1]. This approach is used to design the first model-based demand controlled deep brain stimulation techniques for the therapy of neurological diseases like Parkinson's disease. We report on first tests of these novel techniques performed in patients during electrode implantation. [1] P.A. Tass: Europhys.Lett. 53(2001) 15-21; 55(2001) 171-177; Biol. Cybern. 85(2001) 343-354

  1. How are arrhythmias detected by implanted cardiac devices managed in Europe? Results of the European Heart Rhythm Association Survey.

    PubMed

    Todd, Derick; Hernandez-Madrid, Antonio; Proclemer, Alessandro; Bongiorni, Maria Grazia; Estner, Heidi; Blomström-Lundqvist, Carina

    2015-09-01

    The management of arrhythmias detected by implantable cardiac devices can be challenging. There are no formal international guidelines to inform decision-making. The purpose of this European Heart Rhythm Association (EHRA) survey was to assess the management of various clinical scenarios among members of the EHRA electrophysiology research network. There were 49 responses to the questionnaire. The survey responses were mainly (81%) from medium-high volume device implanting centres, performing more than 200 total device implants per year. Clinical scenarios were described focusing on four key areas: the implantation of pacemakers for bradyarrhythmia detected on an implantable loop recorder (ILR), the management of patients with ventricular arrhythmia detected by an ILR or pacemaker, the management of atrial fibrillation in patients with pacemakers and cardiac resynchronization therapy devices and the management of ventricular tachycardia in patients with implantable cardioverter-defibrillators. PMID:26443791

  2. A detection system for charged-particle decay studies with a continuous-implantation method

    NASA Astrophysics Data System (ADS)

    Sun, L. J.; Xu, X. X.; Lin, C. J.; Wang, J. S.; Fang, D. Q.; Li, Z. H.; Wang, Y. T.; Li, J.; Yang, L.; Ma, N. R.; Wang, K.; Zang, H. L.; Wang, H. W.; Li, C.; Shi, C. Z.; Nie, M. W.; Li, X. F.; Li, H.; Ma, J. B.; Ma, P.; Jin, S. L.; Huang, M. R.; Bai, Z.; Wang, J. G.; Yang, F.; Jia, H. M.; Zhang, H. Q.; Liu, Z. H.; Bao, P. F.; Wang, D. X.; Yang, Y. Y.; Zhou, Y. J.; Ma, W. H.; Chen, J.

    2015-12-01

    A new detection system with high detection efficiency and low detection threshold has been developed for charged-particle decay studies, including β-delayed proton, α decay or direct proton emission from proton-rich nuclei. The performance was evaluated by using the β-delayed proton emitter 24Si produced by projectile fragmentation at the First Radioactive Ion Beam Line in Lanzhou. Under a continuous-beam mode, the isotopes of interest were implanted into two double-sided silicon strip detectors, where the subsequent decays were measured and correlated to the preceding implantations by using position and time information. The system allows us to measure protons with energies down to about 200 keV without obvious β background in the proton spectrum. Further application of the detection system can be extended to the measurements of β-delayed proton decay and the direct proton emission of more exotic proton-rich nuclei.

  3. Diagnostic Accuracy of Inverted and Unprocessed Digitized Periapical Radiographs for Detection of Peri-Implant Defects

    PubMed Central

    Pourhashemi, Seyed Jalal; Kiani, Mohammad Taghi; Emami, Raheleh; Kharazifard, Mohamad Javad

    2015-01-01

    Objectives: This study aimed to compare the diagnostic accuracy of inverted and unprocessed digitized periapical radiographs for detection of peri-implant defects. Materials and Methods: A total of 30 osteotomy sites were prepared in three groups of control, study group 1 with 0.425 mm defects and study group 2 with 0.725 mm defects using the SIC and Astra Tech drill systems with 4.25mm and 4.85mm diameters. Small and large defects were randomly created in the coronal 8mm of 20 implant sites; implants (3.4mm diameter, 14.5mm length) were then placed. Thirty periapical (PA) radiographs were obtained using Digora imaging system (Soredex Corporation, Helsinki, Finland), size 2 photostimulable storage phosphor (PSP) plate sensors (40.0mm×30.0mm) and Scanora software. Unprocessed images were inverted using Scanora software by applying image inversion and a total of 60 images were obtained and randomly evaluated by four oral and maxillofacial radiologists. Data were analyzed using the t-test. Results: Significant differences were observed in absolute and complete sensitivity and specificity of the two imaging modalities for detection of small and large defects (P<0.05). Unprocessed digital images had a higher mean in terms of absolute sensitivity for detection of small defects, complete sensitivity for detection of large peri-implant defects and definite rule out of defects compared with inverted images. Conclusion: Unprocessed digital images have a higher diagnostic value for detection of small and large peri-implant defects and also for definite rule out of defects compared with inverted images. PMID:27123016

  4. Investigation of the silicone structure in breast implants using ¹H NMR.

    PubMed

    Formes, Andreas; Diehl, Bernd

    2014-05-01

    Against the background of the scandal about low-grade silicone breast implants of the French manufacturer Poly Implant Prothese (PIP), several types of implants were examined using (1)H NMR spectroscopy. The intention was to classify an implant according to its silicone structure. Therefore, the certificated raw material of the American silicone producer Nusil Technology was analyzed and used as a reference. The list of tested implants consists of implants by PFM medical, PIP, Silimed, Rofil, Eurosilicone, Mentor, Perouse Plastie, Polytech, Nagor, CUI, and McGhan. In the (1)H NMR spectrum the signal of the vinyl group, which is used to cross link silicone rubbers, is visible. It is possible to differentiate between silicones which have a vinyl terminated end group and silicones whose vinyl group is located within the chain of the polymer. The two different types of the vinyl group are one mean to classify the implants. Other categories besides the type of vinyl include the relative amount of the remaining vinyl in the implant and the chemical structure of the material used for the production of the envelope. With these characteristics the examined implants could be grouped into four types. PMID:24342752

  5. Development of Linear Mode Detection for Top-down Ion Implantation of Low Energy Sb Donors

    NASA Astrophysics Data System (ADS)

    Pacheco, Jose; Singh, Meenakshi; Bielejec, Edward; Lilly, Michael; Carroll, Malcolm

    2015-03-01

    Fabrication of donor spin qubits for quantum computing applications requires deterministic control over the number of implanted donors and the spatial accuracy to within which these can be placed. We present an ion implantation and detection technique that allows us to deterministically implant a single Sb ion (donor) with a resulting volumetric distribution of <10 nm. This donor distribution is accomplished by implanting 30keV Sb into Si which yields a longitudinal straggle of <10 nm and combined with a <50 nm spot size using the Sandia NanoImplanter (nI). The ion beam induced charge signal is collected using a MOS detector that is integrated with a Si quantum dot for transport measurments. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. The work was supported by Sandia National Laboratories Directed Research and Development Program. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  6. Measurements of deformations in osseous structures and implants by digital speckle interferometry (DSPI)

    NASA Astrophysics Data System (ADS)

    Salvador, Rosario; González-Peña, Rolando; Cibrián, Rosa; Buendía, Mateo; Mínguez, Fe; Laguía, Manuel; Molina, Teresa; Marti, Luis; Esteve, José; Caballero, José; Micó, Vicente; Sanjuan, Elena

    2006-09-01

    Knowledge of how osseous structures and implants behave under deforming stress is an interesting point when evaluating the response of an implanted prosthesis. The failure of an implant is not always due to the great stress a structure may be subjected to at a particular moment, but rather to the effects of deterioration associated with lesser stress but which is continuously applied. Therefore it is helpful to know how bones and implants respond to this lesser stress. Digital speckle interferometry (DSPI) is suitable for this type of determination, as it is a highly sensitive, non-invasive optical technique. In this study we present the results we obtained when determining the elasticity of a sample of a macerated human radius, a titanium implant and a titanium screw used to treat the fractures of this bone. The correlation ratios we obtained in determining Young's modulus were in the order of r=0.994. Models were made of these structures using the finite elements method (FEM) with the aid of the ANSYS 10.0 program, applying Young's modulus values determined by DSPI. With a view to monitoring the accuracy of the FEM models of the bone and the implant elements we designed a flexion experiment to obtain the DSPI values in and out of plane. The high degree of concordance between the results of both methods makes it possible to continue studying osseous samples with a fixed implant, and also other implants made of different alloys.

  7. Structure analysis of bimetallic Co-Au nanoparticles formed by sequential ion implantation

    NASA Astrophysics Data System (ADS)

    Chen, Hua-jian; Wang, Yu-hua; Zhang, Xiao-jian; Song, Shu-peng; chen, Hong; Zhang, Ke; Xiong, Zu-zhao; Ji, Ling-ling; Dai, Hou-mei; Wang, Deng-jing; Lu, Jian-duo; Wang, Ru-wu; Zheng, Li-rong

    2016-08-01

    Co-Au alloy Metallic nanoparticles (MNPs) are formed by sequential ion implantation of Co and Au into silica glass at room temperature. The ion ranges of Au ions implantation process have been displayed to show the ion distribution. We have used the atomic force microscopy (AFM) and transmission electron microscopy (TEM) to investigate the formation of bimetallic nanoparticles. The extended X-ray absorption fine structure (EXAFS) has been used to study the local structural information of bimetallic nanoparticles. With the increase of Au ion implantation, the local environments of Co ions are changed enormously. Hence, three oscillations, respectively, Co-O, Co-Co and Co-Au coordination are determined.

  8. Shallow nitrogen ion implantation: Evolution of chemical state and defect structure in titanium

    NASA Astrophysics Data System (ADS)

    Manojkumar, P. A.; Chirayath, V. A.; Balamurugan, A. K.; Krishna, Nanda Gopala; Ilango, S.; Kamruddin, M.; Amarendra, G.; Tyagi, A. K.; Raj, Baldev

    2016-09-01

    Evolution of chemical states and defect structure in titanium during low energy nitrogen ion implantation by Plasma Immersion Ion Implantation (PIII) process is studied. The underlying process of chemical state evolution is investigated using secondary ion mass spectrometry and X-ray photoelectron spectroscopy. The implantation induced defect structure evolution as a function of dose is elucidated using variable energy positron annihilation Doppler broadening spectroscopy (PAS) and the results were corroborated with chemical state. Formation of 3 layers of defect state was modeled to fit PAS results.

  9. 3D imaging of biofilms on implants by detection of scattered light with a scanning laser optical tomograph

    PubMed Central

    Heidrich, Marko; Kühnel, Mark P.; Kellner, Manuela; Lorbeer, Raoul-Amadeus; Lange, Tineke; Winkel, Andreas; Stiesch, Meike; Meyer, Heiko; Heisterkamp, Alexander

    2011-01-01

    Biofilms – communities of microorganisms attached to surfaces – are a constant threat for long-term success in modern implantology. The application of laser scanning microscopy (LSM) has increased the knowledge about microscopic properties of biofilms, whereas a 3D imaging technique for the large scale visualization of bacterial growth and migration on curved and non-transparent surfaces is not realized so far. Towards this goal, we built a scanning laser optical tomography (SLOT) setup detecting scattered laser light to image biofilm on dental implant surfaces. SLOT enables the visualization of living biofilms in 3D by detecting the wavelength-dependent absorption of non-fluorescent stains like e.g. reduced triphenyltetrazolium chloride (TTC) accumulated within metabolically active bacterial cells. Thus, the presented system allows the large scale investigation of vital biofilm structure and in vitro development on cylindrical and non-transparent objects without the need for fluorescent vital staining. We suggest SLOT to be a valuable tool for the structural and volumetric investigation of biofilm formation on implants with sizes up to several millimeters. PMID:22076261

  10. In Situ Transformation of Chitosan Films into Microtubular Structures on the Surface of Nanoengineered Titanium Implants.

    PubMed

    Gulati, Karan; Johnson, Lucas; Karunagaran, Ramesh; Findlay, David; Losic, Dusan

    2016-04-11

    There is considerable interest in combining bioactive polymers such as chitosan with titanium bone implants to promote bone healing and address therapeutic needs. However, the fate of these biodegradable polymers especially on titanium implants is not fully explored. Here we report in situ formation of chitosan microtube (CMT) structures from chitosan films on the implant surface with titania nanotubes (TNTs) layer, based on phosphate buffer-induced transformation and precipitation process. We have comprehensively analyzed this phenomenon and the factors that influence CMT formation, including substrate topography, immersion solution and its pH, effect of coating thickness, and time of immersion. Significance of reported in situ formation of chitosan microtubes on the TNTs surface is possibly to tailor properties of implants with favorable micro and nano morphology using a self-ordering process after the implant's insertion. PMID:26999291

  11. Luminescence and structural properties of defects in ion implanted ZnO

    NASA Astrophysics Data System (ADS)

    Monteiro, T.; Soares, M. J.; Neves, A. J.; Carmo, M. C.; Peres, M.; Cruz, A.; Alves, E.; Wahl, U.; Rita, E.; Munoz-Sanjose, V.; Zuniga-Perez, J.

    2006-03-01

    ZnO substrates and films were intentionally implanted with rare earth and transition metal ions. The influence of the implantation and subsequent air thermal annealing treatments on the structural and optical properties of ZnO samples were studied by using Rutherford backscattering spectrometry and low temperature photoluminescence techniques. Intraionic Tm-related emission was observed for bulk and ZnO films. Similarly, Eu and Tb-doped ZnO films follow the same trend observed in bulk samples. No intraionic related emission was observed for Eu-doped samples even being the ion in Zn sites and for the Tb-doped samples ion segregation was observed for thermal annealing temperatures above 800 °C. For the Mn-doped ZnO bulk samples the lattice recovery follows the same trend to that one observed for the Fe-doped samples, starting near 800 °C being fully recovered at 1050 °C. Although Fe3+ was observed no intraionic Mn-related emission was detected under the used conditions.

  12. The local structure and ferromagnetism in Fe-implanted SrTiO₃ single crystals

    SciTech Connect

    Lobacheva, O. Chavarha, M.; Yiu, Y. M.; Sham, T. K.; Goncharova, L. V.

    2014-07-07

    We report a connection between the local structure of low-level Fe impurities and vacancies as the cause of ferromagnetic behavior observed in strontium titanate single crystals (STO), which were implanted with Fe and Si ions at different doses then annealed in oxygen. The effects of Fe doping and post-implantation annealing of STO were studied by X-ray Absorption Near Edge Structure (XANES) spectroscopy and Superconducting Quantum Interference Device magnetometry. XANES spectra for Fe and Ti K- and L-edge reveal the changes in the local environment of Fe and Ti following the implantation and annealing steps. The annealing in oxygen atmosphere partially healed implantation damages and changed the oxidation state of the implanted iron from metallic Fe⁰ to Fe²⁺/Fe³⁺ oxide. The STO single crystals were weak ferromagnets prior to implantation. The maximum saturation moment was obtained after our highest implantation dose of 2×10¹⁶ Fe atom/cm², which could be correlated with the metallic Fe⁰ phases in addition to the presence of O/Ti vacancies. After recrystallization annealing, the ferromagnetic response disappears. Iron oxide phases with Fe²⁺ and Fe³⁺ corresponding to this regime were identified and confirmed by calculations using Real Space Multiple Scattering program (FEFF9).

  13. The local structure and ferromagnetism in Fe-implanted SrTiO3 single crystals

    NASA Astrophysics Data System (ADS)

    Lobacheva, O.; Chavarha, M.; Yiu, Y. M.; Sham, T. K.; Goncharova, L. V.

    2014-07-01

    We report a connection between the local structure of low-level Fe impurities and vacancies as the cause of ferromagnetic behavior observed in strontium titanate single crystals (STO), which were implanted with Fe and Si ions at different doses then annealed in oxygen. The effects of Fe doping and post-implantation annealing of STO were studied by X-ray Absorption Near Edge Structure (XANES) spectroscopy and Superconducting Quantum Interference Device magnetometry. XANES spectra for Fe and Ti K- and L-edge reveal the changes in the local environment of Fe and Ti following the implantation and annealing steps. The annealing in oxygen atmosphere partially healed implantation damages and changed the oxidation state of the implanted iron from metallic Fe0 to Fe2+/Fe3+ oxide. The STO single crystals were weak ferromagnets prior to implantation. The maximum saturation moment was obtained after our highest implantation dose of 2 × 1016 Fe atom/cm2, which could be correlated with the metallic Fe0 phases in addition to the presence of O/Ti vacancies. After recrystallization annealing, the ferromagnetic response disappears. Iron oxide phases with Fe2+ and Fe3+ corresponding to this regime were identified and confirmed by calculations using Real Space Multiple Scattering program (FEFF9).

  14. The relationship between dental implant stability and trabecular bone structure using cone-beam computed tomography

    PubMed Central

    2016-01-01

    Purpose The objective of this study was to investigate the relationships between primary implant stability as measured by impact response frequency and the structural parameters of trabecular bone using cone-beam computed tomography(CBCT), excluding the effect of cortical bone thickness. Methods We measured the impact response of a dental implant placed into swine bone specimens composed of only trabecular bone without the cortical bone layer using an inductive sensor. The peak frequency of the impact response spectrum was determined as an implant stability criterion (SPF). The 3D microstructural parameters were calculated from CT images of the bone specimens obtained using both micro-CT and CBCT. Results SPF had significant positive correlations with trabecular bone structural parameters (BV/TV, BV, BS, BSD, Tb.Th, Tb.N, FD, and BS/BV) (P<0.01) while SPF demonstrated significant negative correlations with other microstructural parameters (Tb.Sp, Tb.Pf, and SMI) using micro-CT and CBCT (P<0.01). Conclusions There was an increase in implant stability prediction by combining BV/TV and SMI in the stepwise forward regression analysis. Bone with high volume density and low surface density shows high implant stability. Well-connected thick bone with small marrow spaces also shows high implant stability. The combination of bone density and architectural parameters measured using CBCT can predict the implant stability more accurately than the density alone in clinical diagnoses. PMID:27127692

  15. A study of the structural and magnetic properties of ZnO implanted by Gd ions

    NASA Astrophysics Data System (ADS)

    Macková, A.; Malinský, P.; Sofer, Z.; Šimek, P.; Sedmidubský, D.; Mikulics, M.; Wilhelm, R. A.

    2014-08-01

    The structural and magnetic properties of ZnO (0 0 0 1) single crystals implanted with 200 keV Gd ions up to a fluence of 5 × 1015 cm-2 and subsequently annealed at 800 °C in various atmospheres were studied. The chemical composition and concentration depth profiles of ion-implanted layers were characterised by Rutherford Back-Scattering spectrometry (RBS) and compared to SRIM simulations. The as-implanted Gd depth profiles were found to be broader than those simulated by SRIM, but the projected range coincided well with that simulated. After annealing at 800 °C, the depth profiles became narrower. The structural changes in the layers modified by ion implantation and subsequent annealing were characterised by RBS channelling. The annealing led to partial recrystallisation and a decrease in the number of Gd atoms situated in substitutional positions. Raman spectroscopy showed that the point defects in Zn and O vacancies had been created by implantation and that these defects are most effectively cured after annealing in oxygen atmosphere. AFM analysis was used to determine the surface-morphology changes after the implantation and annealing procedures. The as-implanted samples exhibited ferromagnetism persisting up to room temperature. The annealing procedure led to paramagnetic behaviour, probably caused by the formation of gadolinium clusters.

  16. Structural investigations in helium implanted cubic zirconia using grazing incidence XRD and EXAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Kuri, G.; Degueldre, C.; Bertsch, J.; Döbeli, M.

    2010-06-01

    The crystal structure and local atom arrangements surrounding Zr atoms were determined for a helium implanted cubic stabilized zirconia (CSZ) using X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy, respectively, measured at glancing angles. The implanted specimen was prepared at a helium fluence of 2 × 10 16 cm -2 using He + beams at two energies (2.54 and 2.74 MeV) passing through a 8.0 μm Al absorber foil. XRD results identified the formation of a new rhombohedral phase in the helium embedded layer, attributed to internal stress as a result of expansion of the CSZ-lattice. Zr K-edge EXAFS data suggested loss of crystallinity in the implanted lattice and disorder of the Zr atoms environment. EXAFS Fourier transforms analysis showed that the average first-shell radius of the Zr sbnd O pair in the implanted sample was slightly larger than that of the CSZ standard. Common general disorder features were explained by rhombohedral type short-range ordered clusters. The average structural parameters estimated from the EXAFS data of unimplanted and implanted CSZ are compared and discussed. Potential of EXAFS as a local probe of atomic-scale structural modifications induced by helium implantation in CSZ is demonstrated.

  17. Formation of SIMOX-SOI structure by high-temperature oxygen implantation

    NASA Astrophysics Data System (ADS)

    Hoshino, Yasushi; Kamikawa, Tomohiro; Nakata, Jyoji

    2015-12-01

    We have performed oxygen ion implantation in silicon at very high substrate-temperatures (⩽1000 °C) for the purpose of forming silicon-on-insulator (SOI) structure. We have expected that the high-temperature implantation can effectively avoids ion-beam-induced damages in the SOI layer and simultaneously stabilizes the buried oxide (BOX) and SOI-Si layer. Such a high-temperature implantation makes it possible to reduce the post-implantation annealing temperature. In the present study, oxygen ions with 180 keV are incident on Si(0 0 1) substrates at various temperatures from room temperature (RT) up to 1000 °C. The ion-fluencies are in order of 1017-1018 ions/cm2. Samples have been analyzed by atomic force microscope, Rutherford backscattering, and micro-Raman spectroscopy. It is found in the AFM analysis that the surface roughness of the samples implanted at 500 °C or below are significantly small with mean roughness of less than 1 nm, and gradually increased for the 800 °C-implanted sample. On the other hand, a lot of dents are observed for the 1000 °C-implanted sample. RBS analysis has revealed that stoichiometric SOI-Si and BOX-SiO2 layers are formed by oxygen implantation at the substrate temperatures of RT, 500, and 800 °C. However, SiO2-BOX layer has been desorbed during the implantation. Raman spectra shows that the ion-beam-induced damages are fairly suppressed by such a high-temperatures implantation.

  18. Structural, electronic and magnetic properties of Er implanted ZnO thin films

    NASA Astrophysics Data System (ADS)

    Murmu, P. P.; Kennedy, J.; Ruck, B. J.; Leveneur, J.

    2015-09-01

    We report the structural, electronic and magnetic properties of Er implanted and annealed ZnO thin films. The effect of annealing in oxygen-deficient and oxygen-rich conditions was investigated. Rutherford backscattering spectrometry results revealed that the Er atoms are located at the implantation depth of around 13 nm, and annealing conditions had no adverse effect on the Er concentration in the layer. Raman spectroscopy results showed peak related to E2(high) mode of ZnO indicating enhanced crystalline quality of the Er implanted and annealed ZnO films. X-ray absorption near edge spectroscopy results demonstrated pre-edge features in O K-edge which are attributed to the structural defects in the films. Room temperature magnetic ordering was observed in Er implanted and annealed films, and is mainly assigned to the intrinsic defects in ZnO.

  19. Structural and magnetic impact of Cr+-implantation into GaN thin film

    NASA Astrophysics Data System (ADS)

    Husnain, G.; Shu-De, Yao; Ahmad, Ishaq; Rafique, H. M.

    2012-06-01

    Thin films of GaN with thickness of 2 μm were synthesized on sapphire. Cr+ ions were implanted into GaN with150 keV energy at a fluence of 3 × 1015 cm-2. The annealing of the samples was carried out for a short time using rapid thermal annealing (RTA). Structural properties of the implanted samples were undertaken by XRD and Rutherford backscattering. The annealed samples demonstrated lattice recovery and damages caused by implantation. The structural properties were also studied by High-resolution X-ray Diffraction (HRXRD). Magnetic measurements of the samples were performed by Alternating Gradient Magnetometer (AGM) at room temperature and by SQUID in the range of 5-380 K. The SQUID results showed ferromagnetic behavior at T = 5 K and above 380 K for Cr+-implanted GaN.

  20. The structural and optical properties of metal ion-implanted GaN

    NASA Astrophysics Data System (ADS)

    Macková, A.; Malinský, P.; Sofer, Z.; Šimek, P.; Sedmidubský, D.; Veselý, M.; Böttger, R.

    2016-03-01

    The practical development of novel optoelectronic materials with appropriate optical properties is strongly connected to the structural properties of the prepared doped structures. We present GaN layers oriented along the (0 0 0 1) crystallographic direction that have been grown by low-pressure metal-organic vapour-phase epitaxy (MOVPE) on sapphire substrates implanted with 200 keV Co+, Fe+ and Ni+ ions. The structural properties of the ion-implanted layers have been characterised by RBS-channelling and Raman spectroscopy to obtain a comprehensive insight into the structural modification of implanted GaN layers and to study the subsequent influence of annealing on crystalline-matrix recovery. Photoluminescence was measured to control the desired optical properties. The post-implantation annealing induced the structural recovery of the modified GaN layer depending on the introduced disorder level, e.g. depending on the ion implantation fluence, which was followed by structural characterisation and by the study of the surface morphology by AFM.

  1. Oxygen Implant Isolation of n-GaN Field-Effect Transistor Structures

    SciTech Connect

    Dang, G.; Cao, X.A.; Ren, F.; Pearton, S.J.; Han, J.; Baca, A.G.; Shul, R.J.

    1999-07-20

    Multiple-energy (30-325 keV) O{sup +} implantation into GaN field-effect transistor structures (n {approximately} 10{sup 18} cm{sup {minus}3}, 3000 {angstrom} thick) can produce as-implanted sheet resistances of 4 x 10{sup 12} {Omega}/{open_square}, provided care is taken to ensure compensation of the region up to the projected range of the lowest energy implant. The sheet resistance remains above 10{sup 7} {Omega}/{open_square} to annealing temperatures of {approximately} 650 C and displays an activation energy of 0.29 eV. No diffusion of the implanted oxygen was observed for anneals up to 800 C.

  2. Structural Transformations in Austenitic Stainless Steel Induced by Deuterium Implantation: Irradiation at 295 K

    NASA Astrophysics Data System (ADS)

    Morozov, Oleksandr; Zhurba, Volodymir; Neklyudov, Ivan; Mats, Oleksandr; Progolaieva, Viktoria; Boshko, Valerian

    2016-02-01

    Deuterium thermal desorption spectra were investigated on the samples of austenitic steel 18Cr10NiTi pre-implanted at 295 K with deuterium ions in the dose range from 8 × 1014 to 2.7 × 1018 D/cm2. The kinetics of structural transformation development in the steel layer was traced from deuterium thermodesorption spectra as a function of deuterium concentration. Three characteristic regions with different low rates of deuterium amount desorption as the implantation dose increases were revealed: I—the linear region of low implantation doses (up to 1 × 1017 D/cm2); II—the nonlinear region of medium implantation doses (1 × 1017 to 8 × 1017 D/cm2); III—the linear region of high implantation doses (8 × 1017 to 2.7 × 1018 D/cm2). During the process of deuterium ion irradiation, the coefficient of deuterium retention in steel varies in discrete steps. Each of the discrete regions of deuterium retention coefficient variation corresponds to different implanted-matter states formed during deuterium ion implantation. The low-dose region is characterized by formation of deuterium-vacancy complexes and solid-solution phase state of deuterium in the steel. The total concentration of the accumulated deuterium in this region varies between 2.5 and 3 at.%. The medium-dose region is characterized by the radiation-induced action on the steel in the presence of deuterium with the resulting formation of the energy-stable nanosized crystalline structure of steel, having a developed network of intercrystalline boundaries. The basis for this developed network of intercrystalline boundaries is provided by the amorphous state, which manifests itself in the thermodesorption spectra as a widely temperature-scale extended region of deuterium desorption (structure formation with a varying activation energy). The total concentration of the accumulated deuterium in the region of medium implantation doses makes 7 to 8 at.%. The resulting structure shows stability against the action of

  3. Structural Transformations in Austenitic Stainless Steel Induced by Deuterium Implantation: Irradiation at 295 K.

    PubMed

    Morozov, Oleksandr; Zhurba, Volodymir; Neklyudov, Ivan; Mats, Oleksandr; Progolaieva, Viktoria; Boshko, Valerian

    2016-12-01

    Deuterium thermal desorption spectra were investigated on the samples of austenitic steel 18Cr10NiTi pre-implanted at 295 K with deuterium ions in the dose range from 8 × 10(14) to 2.7 × 10(18) D/cm(2). The kinetics of structural transformation development in the steel layer was traced from deuterium thermodesorption spectra as a function of deuterium concentration. Three characteristic regions with different low rates of deuterium amount desorption as the implantation dose increases were revealed: I-the linear region of low implantation doses (up to 1 × 10(17) D/cm(2)); II-the nonlinear region of medium implantation doses (1 × 10(17) to 8 × 10(17) D/cm(2)); III-the linear region of high implantation doses (8 × 10(17) to 2.7 × 10(18) D/cm(2)). During the process of deuterium ion irradiation, the coefficient of deuterium retention in steel varies in discrete steps. Each of the discrete regions of deuterium retention coefficient variation corresponds to different implanted-matter states formed during deuterium ion implantation. The low-dose region is characterized by formation of deuterium-vacancy complexes and solid-solution phase state of deuterium in the steel. The total concentration of the accumulated deuterium in this region varies between 2.5 and 3 at.%. The medium-dose region is characterized by the radiation-induced action on the steel in the presence of deuterium with the resulting formation of the energy-stable nanosized crystalline structure of steel, having a developed network of intercrystalline boundaries. The basis for this developed network of intercrystalline boundaries is provided by the amorphous state, which manifests itself in the thermodesorption spectra as a widely temperature-scale extended region of deuterium desorption (structure formation with a varying activation energy). The total concentration of the accumulated deuterium in the region of medium implantation doses makes 7 to 8 at.%. The

  4. Detecting the onset of urinary bladder contractions using an implantable pressure sensor.

    PubMed

    Melgaard, J; Rijkhoff, N J M

    2011-12-01

    This study investigates whether signals obtained from an implantable pressure sensor placed in the urinary bladder wall could be used to detect the onset of bladder contractions. The sensor assembly was custom made using a small piezoresistive sensor die. The die was mounted on ceramic substrate (8 mm × 8 mm) and encapsulated in silicone by a two-part moulding process. The final sensor was lens shaped with a diameter of 13.6 mm and height of 2.0 mm. Experiments were performed in six pigs that had one or more sensors placed in the bladder wall. An external reference sensor was used to simultaneously monitor intravesical pressure via a transurethral catheter. Bladder contractions were evoked by unilateral electrical stimulation of the pelvic nerve. Onset latency was computed using both signals. In addition, the correlation between wall pressure and intravesical pressure was calculated. On average, the onset latency was - 307 ms using the wall sensors compared to the intravesical pressure, i.e., the detection occurred earlier using the wall sensors than the intravesical sensor. In 91 of 114 recordings the correlation coefficient was above 0.90. In conclusion, the implantable sensor performs similar to the reference sensor when used to detect the onset of bladder contractions. PMID:21997323

  5. Applications of Fault Detection in Vibrating Structures

    NASA Technical Reports Server (NTRS)

    Eure, Kenneth W.; Hogge, Edward; Quach, Cuong C.; Vazquez, Sixto L.; Russell, Andrew; Hill, Boyd L.

    2012-01-01

    Structural fault detection and identification remains an area of active research. Solutions to fault detection and identification may be based on subtle changes in the time series history of vibration signals originating from various sensor locations throughout the structure. The purpose of this paper is to document the application of vibration based fault detection methods applied to several structures. Overall, this paper demonstrates the utility of vibration based methods for fault detection in a controlled laboratory setting and limitations of applying the same methods to a similar structure during flight on an experimental subscale aircraft.

  6. Influence of Si ion implantation on structure and morphology of g-C3N4

    NASA Astrophysics Data System (ADS)

    Varalakshmi, B.; Sreenivasulu, K. V.; Asokan, K.; Srikanth, V. V. S. S.

    2016-07-01

    Effect of Si ion implantation on structural and morphological features of graphite-like carbon nitride (g-C3N4) was investigated. g-C3N4 was prepared by using a simple atmospheric thermal decomposition process. The g-C3N4 pellets were irradiated with a Si ion beam of energy 200 keV with different fluencies. Structural, morphological and elemental, and phase analysis of the implanted samples in comparison with the pristine samples was carried out by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) techniques, respectively. The observations revealed that Si ion implantation results in a negligible change in the crystallite size and alteration of the network-like to the sheet-like morphology of g-C3N4 and Si ions in the g-C3N4 network.

  7. Implantable self-reset CMOS image sensor and its application to hemodynamic response detection in living mouse brain

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Takahiro; Takehara, Hiroaki; Sunaga, Yoshinori; Haruta, Makito; Motoyama, Mayumi; Ohta, Yasumi; Noda, Toshihiko; Sasagawa, Kiyotaka; Tokuda, Takashi; Ohta, Jun

    2016-04-01

    A self-reset pixel of 15 × 15 µm2 with high signal-to-noise ratio (effective peak SNR ≃64 dB) for an implantable image sensor has been developed for intrinsic signal detection arising from hemodynamic responses in a living mouse brain. For detecting local conversion between oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) in brain tissues, an implantable imaging device was fabricated with our newly designed self-reset image sensor and orange light-emitting diodes (LEDs; λ = 605 nm). We demonstrated imaging of hemodynamic responses in the sensory cortical area accompanied by forelimb stimulation of a living mouse. The implantable imaging device for intrinsic signal detection is expected to be a powerful tool to measure brain activities in living animals used in behavioral analysis.

  8. Tachycardia detection in modern implantable cardioverter-defibrillators.

    PubMed

    Brüggemann, Thomas; Dahlke, Daniel; Chebbo, Amin; Neumann, Ilka

    2016-09-01

    Implantable cardioverter-defibrillators (ICD) have to reliably sense, detect, and treat malignant ventricular tachyarrhythmias. Inappropriate treatment of non life-threatening tachyarrhythmias should be avoided. This article outlines the functionality of ICDs developed and manufactured by BIOTRONIK. Proper sensing is achieved by an automatic sensitivity control which can be individually tailored to solve special under- and oversensing situations. The programming of detection zones for ventricular fibrillation (VF), ventricular tachycardia (VT), and zones to monitor other tachyarrhythmias is outlined. Dedicated single-chamber detection algorithms based on average heart rate, cycle length variability, sudden rate onset, and changes in QRS morphology as used in ICDs by BIOTRONIK are described in detail. Preconditions and confirmation algorithms for therapy deliveries as antitachycardia pacing (ATP) and high energy shocks are explained. Finally, a detailed description of the dual-chamber detection algorithm SMART is given. It comprises additional detection criteria as stability of atrial intervals, 1:1 conduction, atrial-ventricular (AV) multiplicity, AV trend, and AV regularity to differentiate between ventricular and supraventricular tachyarrhythmias. PMID:27576695

  9. Detection of Structural Abnormalities Using Neural Nets

    NASA Technical Reports Server (NTRS)

    Zak, M.; Maccalla, A.; Daggumati, V.; Gulati, S.; Toomarian, N.

    1996-01-01

    This paper describes a feed-forward neural net approach for detection of abnormal system behavior based upon sensor data analyses. A new dynamical invariant representing structural parameters of the system is introduced in such a way that any structural abnormalities in the system behavior are detected from the corresponding changes to the invariant.

  10. Transtelephonic monitoring and transmission of stored arrhythmia detection and therapy data from an implantable cardioverter defibrillator.

    PubMed

    Fetter, J G; Stanton, M S; Benditt, D G; Trusty, J; Collins, J

    1995-08-01

    A new transtelephonic monitoring device designed for use with implantable cardioverter defibrillators (ICDs) was evaluated. It is capable of interrogating ICDs and transmitting the following data via telephone: programmed parameters (e.g., ventricular tachycardia [VT] and ventricular fibrillation [VF] detection, therapies), number of VT and VF episodes, identification of successful therapies, the 20 cycle lengths preceding the last episode detected, the 10 cycle lengths after the last delivered therapy, battery voltage, and real-time transmission of the patient's rhythm. Eighteen patients (mean age 64 +/- 17 years; 15 males) were implanted with an ICD and epicardial lead system. The patients who did not live near the primary hospital were provided with this transmitter and instructed to transmit monthly and whenever presyncope, syncope, or a shock were experienced. Five hundred ten episodes of spontaneous arrhythmia (495 VT, 15 VF) were detected in 14 of 18 patients in a 24-month period and the success of each therapy (antitachycardia pacing, cardioversion 0.4-34 J, defibrillation 34 J) was analyzed. The number of therapies delivered and their success (%) in terminating the arrhythmia were: 380 ramp/86%, 116 burst/84%, 119 cardioversion/57%, and 15 defibrillations/100%. Sixty-three (42%) of the 152 transmissions indicated an arrhythmia. Twenty-five (16%) of the 152 were transmitted because of symptoms. Sixteen (9.7%) of 165 VT episodes could not be terminated by the full set of programmed VT therapies. Analysis of the pre- and post-episode intervals along with the patient's transmitted rhythm indicated that sinus tachycardia or atrial fibrillation were likely responsible for these episodes.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7479174

  11. Detection of underground structures and tunnels

    SciTech Connect

    Mack, J.M.; Moses, R.W.; Kelly, R.E.; Flynn, E.R.; Kraus, R.H.; Cogbill, A.H.; Stolarczyk, L.G.

    1996-09-01

    This is the final report of a one year, Laboratory Directed Research and Development project at Los Alamos National Laboratory. There is a continuing need in the United States defense and drug interdiction for effective over, convert, and standoff means of detecting underground tunnels, structures, and objects. This project sought to begin an assessment of electromagnetic and gravitational gradient detection approaches to the detection of underground structures and tunnels.

  12. Synergistic effects of surface chemistry and topologic structure from modified microarc oxidation coatings on Ti implants for improving osseointegration.

    PubMed

    Zhou, Rui; Wei, Daqing; Cao, Jianyun; Feng, Wei; Cheng, Su; Du, Qing; Li, Baoqiang; Wang, Yaming; Jia, Dechang; Zhou, Yu

    2015-04-29

    Microarc oxidation (MAO) coating containing Ca, P, Si, and Na elements on a titanium (Ti) implant has been steam-hydrothermally treated and further mediated by post-heat treatment to overcome the compromised bone-implant integration. The bone regeneration, bone-implant contact, and biomechanical push-out force of the modified Ti implants are discussed thoroughly in this work. The best in vivo performances for the steam-hydrothermally treated one is attributed to the synergistic effects of surface chemistry and topologic structure. Through post-heat treatment, we can decouple the effects of surface chemistry and the nanoscale topologic structure easily. Attributed to the excellent in vivo performance of the surface-modified Ti implant, the steam-hydrothermal treatment could be a promising strategy to improve the osseointegration of the MAO coating covered Ti implant. PMID:25860058

  13. [Structural changes of toothbrush bristles by brushing in patients with dental implants].

    PubMed

    Rubtsova, N G; Sirak, S V; Sirak, A G

    2014-01-01

    Lack of proper oral hygiene practices can lead to treatment failure in patients with implant-retained restorations. Structural changes of toothbrush bristles were studied using scanning electron microscopy and correlated with cleaning efficiency which was assessed at baseline and after 3 months of use of various toothbrushes types in 146 patients with implant-retained restorations. Oral hygiene was valued according to several indices (Approximal Plaque-Index (API), the Turesky index (PI), a modified superstructure plaque index Silness-Loe (PLIsk). Ultrasound toothbrush provided the best and the most efficient cleaning outcome in patients with implant-retained restorations. Scanning electron microscopy proved ultrasonic toothbrush bristles to be more resistant to abrasion during the three-month use. PMID:24781121

  14. Compositional and Structural Study of Gd Implanted ZnO Films

    SciTech Connect

    Murmu, Peter P.; Kennedy, John V.; Markwitz, Andreas; Ruck, Ben J.

    2009-07-23

    We report a compositional and structural study of ZnO films implanted with 30 keV Gd ions. The depth profile of the implanted ions, measured by Rutherford backscattering spectrometry, matches predictions of DYNAMIC-TRIM calculations. However, after annealing at temperatures above 550 deg. C the Gd ions are observed to migrate towards the bulk, and at the same time atomic force microscope images of the film surfaces show significant roughening. Raman spectroscopy shows that the annealed films have a reduced number of crystalline defects. The overall results are useful for developing an implantation-annealing regime to produce well characterized samples to investigate magnetism in the ZnO:Gd system.

  15. Probability of detection of internal voids in structural ceramics using microfocus radiography

    NASA Technical Reports Server (NTRS)

    Baaklini, G. Y.; Roth, D. J.

    1985-01-01

    The reliability of microfocus x-radiography for detecting subsurface voids in structural ceramic test specimens was statistically evaluated. The microfocus system was operated in the projection mode using low X-ray photon energies (20 keV) and a 10 micro m focal spot. The statistics were developed for implanted subsurface voids in green and sintered silicon carbide and silicon nitride test specimens. These statistics were compared with previously-obtained statistics for implanted surface voids in similar specimens. Problems associated with void implantation are discussed. Statistical results are given as probability-of-detection curves at a 95 percent confidence level for voids ranging in size from 20 to 528 micro m in diameter.

  16. Contrast-enhanced X-ray microtomography of the bone structure adjacent to oral implants

    NASA Astrophysics Data System (ADS)

    Tesei, L.; Casseler, F.; Dreossi, D.; Mancini, L.; Tromba, G.; Zanini, F.

    2005-08-01

    One of the most important aims about cortical and cancellous bone research is to understand the factors that determine their mechanical properties, how these properties are maintained, and how bone reacts to changes in its environment, such as the introduction of a titanium implant. Trabecular morphometry has been traditionally assessed in two dimensions, where the structural parameters are either inspected visually or measured from sections, and the third dimension is added on the basis of stereology. Particularly, limiting is the destructive nature of this extremely time consuming procedure, preventing the specimens from being used for other measurements. The most common technique used to overcome some of the limitations of two-dimensional analysis is stereo- or scanning microscopy to assess three-dimensional structural indices qualitatively. Synchrotron radiation X-ray computed microtomography is a particular kind of X-ray computerized axial tomography with higher resolution and the possibility to choose among a very wide range of X-ray energies. Beam energies ranging between 30 and 40 keV will provide a satisfactory signal-to-noise ratio and contrast for bone, except for the parts falling in the shadow of the Ti implant. Higher beam energies would provide correctly exposed images, with lower -to noise ratio for the bone trabecular structure. We will show how the use of alternative materials, such as aluminum, while not altering the evaluation of the mechanical impact of an implant, allows a satisfactory non-destructive, three-dimensional analysis of the bone-implant interface.

  17. Infrared Structural Biology: Detect Functionally Important Structural Motions of Proteins

    NASA Astrophysics Data System (ADS)

    Xie, Aihua

    Proteins are dynamic. Lack of dynamic structures of proteins hampers our understanding of protein functions. Infrared structural biology (IRSB) is an emerging technology. There are several advantages of IRSB for mechanistic studies of proteins: (1) its excellent dynamic range (detecting structural motions from picoseconds to >= seconds); (2) its high structural sensitivity (detect tiny but functionally important structural motions such as proton transfer and changes in hydrogen bonding interaction); (3) its ability to detect different structural motions simultaneously. Successful development of infrared structural biology demands not only new experimental techniques (from infrared technologies to chemical synthesis and cell biology), but also new data processing (how to translate infrared signals into quantitative structural information of proteins). These topics will be discussed as well as examples of how to use IRSB to study structure-function relationship of proteins. This work was supported by NSF DBI1338097 and OCAST HR10-078.

  18. Novel composite fiber structures to provide drug/protein delivery for medical implants and tissue regeneration.

    PubMed

    Zilberman, Meital

    2007-01-01

    A novel class of bioresorbable composite (core/shell) fiber structures loaded with bioactive agents was developed and studied. These unique polymeric structures are designed to combine good mechanical properties with a desired controlled release profile, in order to serve as scaffolds for tissue regeneration applications and as basic elements of medical implants. These core/shell fiber structures were formed by "coating" core polymer fibers with drug/protein-containing poly(dl-lactic-co-glycolic acid) porous structures. The shell preparation ("coating") was performed by the freeze-drying of water-in-oil emulsions. Both water soluble and water insoluble agents can be incorporated in these structures and their activity is preserved, since the fiber fabrication requires neither high temperatures nor harsh solvents in the vicinity of the bioactive agents. Examples for release profiles of protein (horseradish peroxidase) and drug (paclitaxel) are presented. We have demonstrated that appropriate selection of the emulsion's parameters can yield a variety of new core/shell fiber structures with desirable drug/protein release behavior. This will lead to the engineering of new implants and scaffolds, and will advance the field of tissue regeneration and medical implants. PMID:16956799

  19. Real-time detection of implant-associated neutrophil responses using a formyl peptide receptor-targeting NIR nanoprobe

    PubMed Central

    Zhou, Jun; Tsai, Yi-Ting; Weng, Hong; Tang, Ewin N; Nair, Ashwin; Davé, Digant P; Tang, Liping

    2012-01-01

    Neutrophils play an important role in implant-mediated inflammation and infection. Unfortunately, current methods which monitor neutrophil activity, including enzyme measurements and histological evaluation, require many animals and cannot be used to accurately depict the dynamic cellular responses. To understand the neutrophil interactions around implant-mediated inflammation and infection it is critical to develop methods which can monitor in vivo cellular activity in real time. In this study, formyl peptide receptor (FPR)-targeting near-infrared nanoprobes were fabricated. This was accomplished by conjugating near-infrared dye with specific peptides having a high affinity to the FPRs present on activated neutrophils. The ability of FPR-targeting nanoprobes to detect and quantify activated neutrophils was assessed both in vitro and in vivo. As expected, FPR-targeting nanoprobes preferentially accumulated on activated neutrophils in vitro. Following transplantation, FPR-targeting nanoprobes preferentially accumulated at the biomaterial implantation site. Equally important, a strong relationship was observed between the extent of fluorescence intensity in vivo and the number of recruited neutrophils at the implantation site. Furthermore, FPR-targeting nanoprobes may be used to detect and quantify the number of neutrophils responding to a catheter-associated infection. The results show that FPR-targeting nanoprobes may serve as a powerful tool to monitor and measure the extent of neutrophil responses to biomaterial implants in vivo. PMID:22619542

  20. Direct observation of enhanced emission sites in nitrogen implanted hybrid structured ultrananocrystalline diamond films

    SciTech Connect

    Panda, Kalpataru; Sundaravel, B.; Panigrahi, B. K.; Chen, Huang-Chin; Lin, I.-Nan

    2013-02-07

    A hybrid-structured ultrananocrystalline diamond (h-UNCD) film, synthesized on Si-substrates by a two-step microwave plasma enhanced chemical vapour deposition (MPECVD) process, contains duplex structure with large diamond aggregates evenly dispersed in a matrix of ultra-small grains ({approx}5 nm). The two-step plasma synthesized h-UNCD films exhibit superior electron field emission (EFE) properties than the one-step MPECVD deposited UNCD films. Nitrogen-ion implantation/post-annealing processes further improve the EFE properties of these films. Current imaging tunnelling spectroscopy in scanning tunnelling spectroscopy mode directly shows increased density of emission sites in N implanted/post-annealed h-UNCD films than as-prepared one. X-ray photoelectron spectroscopy measurements show increased sp{sup 2} phase content and C-N bonding fraction in N ion implanted/post-annealed films. Transmission electron microscopic analysis reveals that the N implantation/post-annealing processes induce the formation of defects in the diamond grains, which decreases the band gap and increases the density of states within the band gap of diamond. Moreover, the formation of nanographitic phase surrounding the small diamond grains enhanced the conductivity at the diamond grain boundaries. Both of the phenomena enhance the EFE properties.

  1. The Structure of Sapphire Implanted with Carbon at Room Temperature and 1000° C

    NASA Astrophysics Data System (ADS)

    Alves, E.; Marques, C.; Safran, G.; McHargue, Carl J.

    2009-03-01

    Carbon was implanted into sapphire at various temperatures as part of a study of the different defect structures produced by a series of light ions. Implantations were made with 150 keV ions to fluences of 1×1016 and 1×1017ions/cm2 at room temperature (RT) and 1000° C. The defect structures were characterized using Rutherford backscattering-channeling (RBS-C) and transmission electron microscopy (TEM). The RBS-C spectra indicated low residual disorder for RT implantation at 1×1016 C+/cm2. The de-channeling approached the random value at 1×1017 C+/cm2 and the TEM examination revealed a buried amorphous layer containing embedded sapphire nanocrystals. Damaged layers containing planar defects generally aligned parallel to the surface surrounded this layer. The RBS-C spectra for the sample implanted at 1000° C with 1×1017C+/cm2 suggested a highly damaged but crystalline surface that was confirmed by TEM micrographs.

  2. Optimal controller design for structural damage detection

    NASA Astrophysics Data System (ADS)

    Lew, Jiann-Shiun

    2005-03-01

    The virtual passive control technique has recently been applied to structural damage detection, where the virtual passive controller only uses the existing control devices, and no additional physical elements are attached to the tested structure. One important task is to design passive controllers that can enhance the sensitivity of the identified parameters, such as natural frequencies, to structural damage. This paper presents a novel study of an optimal controller design for structural damage detection. We apply not only passive controllers but also low-order and fixed-structure controllers, such as PID controllers. In the optimal control design, the performance of structural damage detection is based on the application of a neural network technique, which uses the pattern of the correlation between the natural frequency changes of the tested system and the damaged system.

  3. A broad chemical and structural characterization of the damaged region of carbon implanted alumina

    NASA Astrophysics Data System (ADS)

    González, M.; Román, R.; Maffiotte, C.; González-Casablanca, J.; Perez, R.; Hole, D.

    2009-05-01

    As candidate materials for future thermonuclear fusion reactors, isolating ceramics will be submitted to high energy gamma and neutron radiation fluxes together with an intense particle flux. Amorphization cannot be tolerated in ceramics for fusion applications, due to the associated volume change and the deterioration of mechanical properties. Therefore, a comprehensive study was carried out to examine the effects of carbon beam irradiation on polycrystalline aluminium oxide (Al2O3), a ceramic component of some diagnostic and plasma heating systems. Complementary techniques have allowed a complete chemical and structural surface analysis of the implanted alumina. Implantation with 75 keV, mono-energetic carbon ions at doses of 1 × 1017 and 5 × 1017 ions/cm2 was performed on polished and thermally treated ceramic discs. The alumina targets were kept below 120 °C. The structural modifications induced during ion irradiation were studied by the GXRD and TEM techniques. Under these conditions, alumina is readily amorphized by carbon ions, the thickness of the ion-beam induced disordered area increasing with the ion dose. Matrix elements and ion implanted profiles were followed as a function of depth by using ToF-SIMS, indicating the maximum concentration of implanted ions to be in the deeper half of the amorphous region. Ion distribution and chemical modifications caused in the Al2O3 substrate by carbon irradiation were corroborated with XPS. The amount of oxygen in the vicinity of the implanted alumina surface was reduced, suggesting that this element was selectively sputtered during carbon irradiation. The intensity of those peaks referring to Al-O bonds diminishes, while contributions of reduced aluminium and metal carbides are found at the maximum of the carbon distribution. TEM observations on low temperature thermally annealed specimens indicate partial recovery of the initial crystalline structure.

  4. Temporal Fine Structure and Applications to Cochlear Implants

    ERIC Educational Resources Information Center

    Li, Xing

    2013-01-01

    Complex broadband sounds are decomposed by the auditory filters into a series of relatively narrowband signals, each of which conveys information about the sound by time-varying features. The slow changes in the overall amplitude constitute envelope, while the more rapid events, such as zero crossings, constitute temporal fine structure (TFS).…

  5. Usefulness of Sonication of Cardiovascular Implantable Electronic Devices to Enhance Microbial Detection

    PubMed Central

    Nagpal, Avish; Patel, Robin; Greenwood-Quaintance, Kerryl E.; Baddour, Larry M.; Lynch, David T.; Lahr, Brian D.; Maleszewski, Joseph J.; Friedman, Paul A.; Hayes, David L.; Sohail, M. Rizwan

    2015-01-01

    The cardiovascular implantable electronic device (CIED) infection rate is rising disproportionately to the rate of device implantation. Identification of microorganisms that cause CIED infections is not always achieved using present laboratory techniques. We conducted a prospective study to determine whether device vortexing-sonication followed by culture of the resulting sonicate fluid would enhance microbial detection compared with traditional swab or pocket tissue cultures. Forty-two subjects with noninfected and 35 with infected CIEDs were prospectively enrolled over 12 months. One swab each from the device pocket and device surface, pocket tissue, and the CIED were collected from each patient. Swabs and tissues were cultured using routine methods. The CIED was processed in Ringer’s solution using vortexing-sonication and the resultant fluid semiquantitatively cultured. Tissue and swab growth was considered significant when colonies grew on ≥2 quadrants of the culture plate and device was considered significant when ≥20 colonies were isolated from 10 ml of sonicate fluid. In noninfected group, 5% of sonicate fluids yielded significant bacterial growth, compared with 5% of tissue cultures (p = 1.00) and 2% of both pocket and device swab cultures (p = 0.317 each). In infected group, significant bacterial growth was observed in 54% of sonicate fluids, significantly greater than the sensitivities of pocket swab (20%, p = 0.001), device swab (9%, p <0.001), or tissue (9%, p <0.001) culture. In conclusion, vortexing-sonication of CIEDs with semiquantitative culture of the resultant sonicate fluid results in a significant increase in the sensitivity of culture results, compared with swab or tissue cultures. PMID:25779615

  6. EXAFS study of the structural properties of In and In + C implanted Ge

    NASA Astrophysics Data System (ADS)

    Feng, R.; Kremer, F.; Sprouster, D. J.; Mirzaei, S.; Decoster, S.; Glover, C. J.; Medling, S. A.; Russo, S. P.; Ridgway, M. C.

    2016-05-01

    The structural configurations of In implanted Ge have been studied via x-ray absorption spectroscopy with and without the codoping of C. In the case of In singly implanted Ge, while the In atoms occupy an substitutional site in Ge (InGe4) at low In concentration (≤ 2 at. %), they precipitate into a metallic phase (In metal) and form complexes composed of one vacancy and three Ge atoms (InVGe3) at concentration ≥ 0.6 at. %. This behaviour can be suppressed by the addition of C leading to In-C pairing to form InCGe3 complexes. This cluster enables In atoms to recover a four-fold coordinated structure and has the potential to improve the electrical activation of In atoms in Ge.

  7. A comparative study of the structure and cytotoxicity of polytetrafluoroethylene after ion etching and ion implantation

    NASA Astrophysics Data System (ADS)

    Shtansky, D. V.; Glushankova, N. A.; Kiryukhantsev-Korneev, F. V.; Sheveiko, A. N.; Sigarev, A. A.

    2011-03-01

    The ion-plasma treatment has been widely used for modifying the surface structure of polymers in order to improve their properties, but it can lead to destruction of the surface and, as a consequence, to an increase in their toxicity. A comparative study of the structure and cytotoxicity of polytetrafluoroethylene (PTFE) after the ion etching (IE) and ion implantation (II) for 10 min with energy densities of 363 and 226 J/cm2, respectively, has been performed. It has been shown that, unlike the ion implantation, the ion etching results in the destruction of the polymer and in the appearance of the cytotoxicity. The factors responsible for this effect, which are associated with the bulk and surface treatment, as well as with the influence of the temperature, have been discussed.

  8. Structural Damage Detection Using Virtual Passive Controllers

    NASA Technical Reports Server (NTRS)

    Lew, Jiann-Shiun; Juang, Jer-Nan

    2001-01-01

    This paper presents novel approaches for structural damage detection which uses the virtual passive controllers attached to structures, where passive controllers are energy dissipative devices and thus guarantee the closed-loop stability. The use of the identified parameters of various closed-loop systems can solve the problem that reliable identified parameters, such as natural frequencies of the open-loop system may not provide enough information for damage detection. Only a small number of sensors are required for the proposed approaches. The identified natural frequencies, which are generally much less sensitive to noise and more reliable than the identified natural frequencies, are used for damage detection. Two damage detection techniques are presented. One technique is based on the structures with direct output feedback controllers while the other technique uses the second-order dynamic feedback controllers. A least-squares technique, which is based on the sensitivity of natural frequencies to damage variables, is used for accurately identifying the damage variables.

  9. Fourier transform spectral imaging microscopy (FT-SIM) and scanning Raman microscopy for the detection of indoor common contaminants on the surface of dental implants.

    PubMed

    Lutin, Anna; Bulatov, Valery; Jadwat, Yusuf; Wood, Neil H; Feller, Liviu; Schechter, Israel

    2015-03-01

    Endosteal dental implants are used routinely with high success rates to rehabilitate the integrity of the dentition. However if implant surfaces become contaminated by foreign material, osseointegration may not occur and the dental implant will fail because of the lack of mechanical stability. Detection and characterization of dental implant surface contaminants is a difficult task. In this article we investigate the application of several spectral microscopy methods to detect airborne contaminants on dental implant surfaces. We found that Fourier Transform Spectral Imaging Microscopy (FT-SIM) and scanning Raman microscopy provided the most useful information. Some implants possess weak and homogeneous auto-fluorescence and are best analyzed using FT-SIM methods, while others are Raman inactive and can be analyzed using scanning Raman microscopy. PMID:25618702

  10. Nano-structure and tribological properties of B + and Ti + co-implanted silicon nitride

    NASA Astrophysics Data System (ADS)

    Nakamura, Naoki; Noda, Katsutoshi; Yamauchi, Yukihiko

    2005-01-01

    Silicon nitride ceramics have been co-implanted with boron and titanium ions at a fluence of 2 × 1017 ions/cm2 and an energy of 200 keV. TEM results indicated that the boron and titanium-implanted layers were amorphized separately and titanium nitride nano-crystallites were formed in the titanium-implanted layer. XPS results indicated that the implantation profile varied a little depending on the ion implantation sequence of boron and titanium ions, with the boron implantation peak shifting to a shallower position when implanted after Ti+-implantation. Wear tests of these ion-implanted materials were carried out using a block-on-ring wear tester under non-lubricated conditions against commercially available silicon nitride materials. The specific wear rate was reduced by ion implantation and showed that the specific wear rate of Ti+-implanted sample was the lowest, followed by B+, Ti+ co-implanted and B+-implanted samples.

  11. Osteoinduction of porous Ti implants with a channel structure fabricated by selective laser melting.

    PubMed

    Fukuda, A; Takemoto, M; Saito, T; Fujibayashi, S; Neo, M; Pattanayak, Deepak K; Matsushita, T; Sasaki, K; Nishida, N; Kokubo, T; Nakamura, T

    2011-05-01

    Many studies have shown that certain biomaterials with specific porous structures can induce bone formation in non-osseous sites without the need for osteoinductive biomolecules, however, the mechanisms responsible for this phenomenon (intrinsic osteoinduction of biomaterials) remain unclear. In particular, to our knowledge the type of pore structure suitable for osteoinduction has not been reported in detail. In the present study we investigated the effects of interconnective pore size on osteoinductivity and the bone formation processes during osteoinduction. Selective laser melting was employed to fabricate porous Ti implants (diameter 3.3mm, length 15 mm) with a channel structure comprising four longitudinal square channels, representing pores, of different diagonal widths, 500, 600, 900, and 1200 μm (termed p500, p600, p900, and p1200, respectively). These were then subjected to chemical and heat treatments to induce bioactivity. Significant osteoinduction was observed in p500 and p600, with the highest observed osteoinduction occurring at 5mm from the end of the implants. A distance of 5mm probably provides a favorable balance between blood circulation and fluid movement. Thus, the simple architecture of the implants allowed effective investigation of the influence of the interconnective pore size on osteoinduction, as well as the relationship between bone quantity and its location for different pore sizes. PMID:21295166

  12. Local structural properties of Co-ion-implanted ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Park, C. I.; Jin, Zhenlan; Jeong, E. S.; Hwang, I. H.; Han, S. W.

    2013-12-01

    We examined the local structural properties around Co and Zn ions in Co-ion-implanted ZnO nanorods by using an X-ray absorption fine structure (XAFS) analysis. Vertically-aligned ZnO nanorods were synthesized on Al2O3 substrates by using a catalyst-free metal-organic chemicalvapor deposition. Co ions (Co+ and Co2+) with energies of 50 and 100 keV and fluxes of 1013 and 1015 particles/cm2 were implanted in the ZnO nanorods, and the ion-implanted ZnO nanorods were annealed at 400-650°C. X-ray absorption near edge structure (XANES) analyses demonstrated that the chemical valence state of the Co ions were mostly 2+. An extended XAFS (EXAFS) analysis revealed that the Co ions were mostly substituted at the Zn sites of ZnO nanorods at a Coion flux of 1015 particles/cm2. However, at a flux of 1013 particles/cm2, Co ions formed Co-O and Co-Co clusters. These results were in contrast to the Co distribution in Co-added ZnO predicted by using a Monte Carlo method.

  13. Predictors of Arrhythmic Events Detected by Implantable Loop Recorders in Renal Transplant Candidates

    PubMed Central

    Silva, Rodrigo Tavares; Martinelli Filho, Martino; Peixoto, Giselle de Lima; de Lima, José Jayme Galvão; de Siqueira, Sérgio Freitas; Costa, Roberto; Gowdak, Luís Henrique Wolff; de Paula, Flávio Jota; Kalil Filho, Roberto; Ramires, José Antônio Franchini

    2015-01-01

    Background The recording of arrhythmic events (AE) in renal transplant candidates (RTCs) undergoing dialysis is limited by conventional electrocardiography. However, continuous cardiac rhythm monitoring seems to be more appropriate due to automatic detection of arrhythmia, but this method has not been used. Objective We aimed to investigate the incidence and predictors of AE in RTCs using an implantable loop recorder (ILR). Methods A prospective observational study conducted from June 2009 to January 2011 included 100 consecutive ambulatory RTCs who underwent ILR and were followed-up for at least 1 year. Multivariate logistic regression was applied to define predictors of AE. Results During a mean follow-up of 424 ± 127 days, AE could be detected in 98% of patients, and 92% had more than one type of arrhythmia, with most considered potentially not serious. Sustained atrial tachycardia and atrial fibrillation occurred in 7% and 13% of patients, respectively, and bradyarrhythmia and non-sustained or sustained ventricular tachycardia (VT) occurred in 25% and 57%, respectively. There were 18 deaths, of which 7 were sudden cardiac events: 3 bradyarrhythmias, 1 ventricular fibrillation, 1 myocardial infarction, and 2 undetermined. The presence of a long QTc (odds ratio [OR] = 7.28; 95% confidence interval [CI], 2.01–26.35; p = 0.002), and the duration of the PR interval (OR = 1.05; 95% CI, 1.02–1.08; p < 0.001) were independently associated with bradyarrhythmias. Left ventricular dilatation (LVD) was independently associated with non-sustained VT (OR = 2.83; 95% CI, 1.01–7.96; p = 0.041). Conclusions In medium-term follow-up of RTCs, ILR helped detect a high incidence of AE, most of which did not have clinical relevance. The PR interval and presence of long QTc were predictive of bradyarrhythmias, whereas LVD was predictive of non-sustained VT. PMID:26351983

  14. The structural changes and optical properties of LiNbO3 after Er implantation using high ion fluencies

    NASA Astrophysics Data System (ADS)

    Macková, A.; Malinský, P.; Pupíková, H.; Nekvindová, P.; Cajzl, J.; Sofer, Z.; Wilhelm, R. A.; Kolitsch, A.; Oswald, J.

    2014-08-01

    The structural and compositional changes of LiNbO3 implanted with 190 keV Er+ ions into various crystallographic cuts with fluencies of 1 × 1016 and 5 × 1016 cm-2 were studied. The effect of post-implantation annealing at 1000 °C in oxygen atmosphere was also examined. Concentration depth profiles of implanted erbium, determined by Rutherford Backscattering Spectrometry (RBS), are broader than those from the SRIM simulation. The maximum erbium concentration (of up to 8 at.%) is observed at the depth of about 50 nm, for all crystal cuts. The structure of the implanted layers were characterised by RBS-channelling method. The lower relative number of disordered atoms in the crystalline matrix was observed in the lithium niobate (LN) implanted at a fluence of 1 × 1016 cm-2, where also the preferential position of the erbium in substitutional sites was observed when compared to the randomly distributed erbium in interstitial positions at a fluence of 5 × 1016 cm-2 after the annealing. Surface-morphology changes at the highest implantation fluencies were studied using Atomic Force Microscopy (AFM). Since we were interested in the relation between the structural changes and optical properties, erbium luminescence properties were measured in the region of 1440-1650 nm. The positive effect of post-implantation annealing on the luminescence properties caused by structural recovery was proved.

  15. Rate discrimination, gap detection and ranking of temporal pitch in cochlear implant users.

    PubMed

    Cosentino, Stefano; Carlyon, Robert P; Deeks, John M; Parkinson, Wendy; Bierer, Julie A

    2016-08-01

    Cochlear implant (CI) users have poor temporal pitch perception, as revealed by two key outcomes of rate discrimination tests: (i) rate discrimination thresholds (RDTs) are typically larger than the corresponding frequency difference limen for pure tones in normal hearing listeners, and (ii) above a few hundred pulses per second (i.e. the "upper limit" of pitch), CI users cannot discriminate further increases in pulse rate. Both RDTs at low rates and the upper limit of pitch vary across listeners and across electrodes in a given listener. Here, we compare across-electrode and across-subject variation in these two measures with the variation in performance on another temporal processing task, gap detection, in order to explore the limitations of temporal processing in CI users. RDTs were obtained for 4-5 electrodes in each of 10 Advanced Bionics CI users using two interleaved adaptive tracks, corresponding to standard rates of 100 and 400 pps. Gap detection was measured using the adaptive procedure and stimuli described by Bierer et al. (JARO 16:273-284, 2015), and for the same electrodes and listeners as for the rate discrimination measures. Pitch ranking was also performed using a mid-point comparison technique. There was a marginal across-electrode correlation between gap detection and rate discrimination at 400 pps, but neither measure correlated with rate discrimination at 100 pps. Similarly, there was a highly significant across-subject correlation between gap detection and rate discrimination at 400, but not 100 pps, and these two correlations differed significantly from each other. Estimates of low-rate sensitivity and of the upper limit of pitch, obtained from the pitch ranking experiment, correlated well with rate discrimination for the 100- and 400-pps standards, respectively. The results are consistent with the upper limit of rate discrimination sharing a common basis with gap detection. There was no evidence that this limitation also applied to rate

  16. Optimization of an acoustic telemetry array for detecting transmitter-implanted fish

    USGS Publications Warehouse

    Clements, S.; Jepsen, D.; Karnowski, M.; Schreck, C.B.

    2005-01-01

    The development of miniature acoustic transmitters and economical, robust automated receivers has enabled researchers to study the movement patterns and survival of teleosts in estuarine and ocean environments, including many species and age-classes that were previously considered too small for implantation. During 2001-2003, we optimized a receiver mooring system to minimize gear and data loss in areas where current action or wave action and acoustic noise are high. In addition, we conducted extensive tests to determine (1) the performance of a transmitter and receiver (Vemco, Ltd.) that are widely used, particularly in North America and Europe and (2) the optimal placement of receivers for recording the passage of fish past a point in a linear-flow environment. Our results suggest that in most locations the mooring system performs well with little loss of data; however, boat traffic remains a concern due to entanglement with the mooring system. We also found that the reception efficiency of the receivers depends largely on the method and location of deployment. In many cases, we observed a range of 0-100% reception efficiency (the percentage of known transmissions that are detected while the receiver is within range of the transmitter) when using a conventional method of mooring. The efficiency was improved by removal of the mounting bar and obstructions from the mooring line. ?? Copyright by the American Fisheries Society 2005.

  17. Simple probabilistic algorithm for detecting community structure

    NASA Astrophysics Data System (ADS)

    Ren, Wei; Yan, Guiying; Liao, Xiaoping; Xiao, Lan

    2009-03-01

    With the growing number of available social and biological networks, the problem of detecting the network community structure is becoming more and more important which acts as the first step to analyze these data. The community structure is generally regarded as that nodes in the same community tend to have more edges and less if they are in different communities. We propose a simple probabilistic algorithm for detecting community structure which employs expectation-maximization (SPAEM). We also give a criterion based on the minimum description length to identify the optimal number of communities. SPAEM can detect overlapping nodes and handle weighted networks. It turns out to be powerful and effective by testing simulation data and some widely known data sets.

  18. Critical issues in the formation of quantum computer test structures by ion implantation

    SciTech Connect

    Schenkel, T.; Lo, C. C.; Weis, C. D.; Schuh, A.; Persaud, A.; Bokor, J.

    2009-04-06

    The formation of quantum computer test structures in silicon by ion implantation enables the characterization of spin readout mechanisms with ensembles of dopant atoms and the development of single atom devices. We briefly review recent results in the characterization of spin dependent transport and single ion doping and then discuss the diffusion and segregation behaviour of phosphorus, antimony and bismuth ions from low fluence, low energy implantations as characterized through depth profiling by secondary ion mass spectrometry (SIMS). Both phosphorus and bismuth are found to segregate to the SiO2/Si interface during activation anneals, while antimony diffusion is found to be minimal. An effect of the ion charge state on the range of antimony ions, 121Sb25+, in SiO2/Si is also discussed.

  19. High Structural Stability of Textile Implants Prevents Pore Collapse and Preserves Effective Porosity at Strain

    PubMed Central

    Klinge, Uwe; Otto, Jens; Mühl, Thomas

    2015-01-01

    Reinforcement of tissues by use of textiles is encouraged by the reduced rate of recurrent tissue dehiscence but for the price of an inflammatory and fibrotic tissue reaction to the implant. The latter mainly is affected by the size of the pores, whereas only sufficiently large pores are effective in preventing a complete scar entrapment. Comparing two different sling implants (TVT and SIS), which are used for the treatment of urinary incontinence, we can demonstrate that the measurement of the effective porosity reveals considerable differences in the textile construction. Furthermore the changes of porosity after application of a tensile load can indicate a structural instability, favouring pore collapse at stress and questioning the use for purposes that are not “tension-free.” PMID:25973427

  20. Structural and vibrational properties of Co nanoparticles formed by ion implantation

    NASA Astrophysics Data System (ADS)

    Sprouster, D. J.; Giulian, R.; Araujo, L. L.; Kluth, P.; Johannessen, B.; Cookson, D. J.; Foran, G. J.; Ridgway, M. C.

    2010-01-01

    We report on the structural and vibrational properties of Co nanoparticles formed by ion implantation and thermal annealing in amorphous silica. The evolution of the nanoparticle size, phase, and structural parameters were determined as a function of the formation conditions using transmission electron microscopy, small-angle x-ray scattering, and x-ray absorption spectroscopy. The implantation fluence and annealing temperature governed the spherical nanoparticle size and phase. To determine the latter, x-ray absorption near-edge structure analysis was used to quantify the hexagonal close packed, face-centered cubic and oxide fractions. The structural properties were characterized by extended x-ray absorption fine structure spectroscopy (EXAFS) and finite-size effects were readily apparent. With a decrease in nanoparticle size, an increase in structural disorder and a decrease in both coordination number and bondlength were observed as consistent with the non-negligible surface-area-to-volume ratio characteristic of nanoparticles. The surface tension of Co nanoparticles calculated using a liquid drop model was more than twice that of bulk material. The size-dependent vibrational properties were probed with temperature-dependent EXAFS measurements. Using a correlated anharmonic Einstein model and thermodynamic perturbation theory, Einstein temperatures for both nanoparticles and bulk material were determined. Compared to bulk Co, the mean vibrational frequency of the smallest nanoparticles was reduced as attributed to a greater influence of loosely bonded, undercoordinated surface atoms relative to the effect of capillary pressure generated by surface curvature.

  1. Reliability of scanning laser acoustic microscopy for detecting internal voids in structural ceramics

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Baaklini, G. Y.

    1986-01-01

    The reliability of 100 MHz scanning laser acoustic microscopy (SLAM) for detecting internal voids in sintered specimens of silicon nitride and silicon carbide was evaluated. The specimens contained artificially implanted voids and were positioned at depths ranging up to 2 mm below the specimen surface. Detection probability of 0.90 at a 0.95 confidence level was determined as a function of material, void diameter, and void depth. The statistical results presented for void detectability indicate some of the strengths and limitations of SLAM as a nondestructive evaluation technique for structural ceramics.

  2. A Structural Equation Modeling Approach to Examining Factors Influencing Outcomes with Cochlear Implant in Mandarin-Speaking Children

    PubMed Central

    Chen, Yuan; Wong, Lena L. N.; Zhu, Shufeng; Xi, Xin

    2015-01-01

    Objective To examine the direct and indirect effects of demographical factors on speech perception and vocabulary outcomes of Mandarin-speaking children with cochlear implants (CIs). Methods 115 participants implanted before the age of 5 and who had used CI before 1 to 3 years were evaluated using a battery of speech perception and vocabulary tests. Structural equation modeling was used to test the hypotheses proposed. Results Early implantation significantly contributed to speech perception outcomes while having undergone a hearing aid trial (HAT) before implantation, maternal educational level (MEL), and having undergone universal newborn hearing screening (UNHS) before implantation had indirect effects on speech perception outcomes via their effects on age at implantation. In addition, both age at implantation and MEL had direct and indirect effects on vocabulary skills, while UNHS and HAT had indirect effects on vocabulary outcomes via their effects on age at implantation. Conclusion A number of factors had indirect and direct effects on speech perception and vocabulary outcomes in Mandarin-speaking children with CIs and these factors were not necessarily identical to those reported among their English-speaking counterparts. PMID:26348360

  3. Porous Tantalum Structures for Bone Implants: Fabrication, Mechanical and In vitro Biological Properties

    PubMed Central

    Balla, Vamsi Krishna; Bodhak, Subhadip; Bose, Susmita; Bandyopadhyay, Amit

    2010-01-01

    Relatively high cost of manufacturing and inability to produce modular all tantalum implants has limited its widespread acceptance, in spite of its excellent in vitro and in vivo biocompatibility. In this article, we report how to process Ta to create net shape porous structures with varying porosity using Laser Engineered Net Shaping (LENS™) for the first time. Porous Ta samples with relative densities between 45 to 73% have been successfully fabricated and characterized for their mechanical properties. In vitro cell materials interactions, using human osteoblast cell line hFOB, have been accessed on these porous Ta structures and compared with porous Ti control samples. The results show that the Young’s modulus of porous Ta can be tailored between 1.5 to 20 GPa by changing the pore volume fraction between 27 and 55%. In vitro biocompatibility in terms of MTT assay and immunochemistry study showed excellent cellular adherence, growth and differentitation with abundant extracellular matrix formation on porous Ta structures compared to porous Ti control. These results indicate that porous Ta structures can promote enhanced/early biological fixation. The enhanced in vitro cell-materials interactions on porous Ta surface are attributed to chemistry and its high wettability and surface energy relative to porous Ti. Our results show that these laser processed porous Ta structures can find numerous applications, particularly among older patients, for metallic implants because of their excellent bioactivity. PMID:20132912

  4. Histrelin Implant

    MedlinePlus

    ... bone growth and development of sexual characteristics) in girls usually between 2 and 8 years of age ... MRI scans (radiology techniques designed to show the images of body structures) to find the implant when ...

  5. Detecting structure of haplotypes and local ancestry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We present a two-layer hidden Markov model to detect the structure of haplotypes for unrelated individuals. This allows us to model two scales of linkage disequilibrium (one within a group of haplotypes and one between groups), thereby taking advantage of rich haplotype information to infer local an...

  6. [Comparative animal experimental study on the importance of the surface structure for the stability of extension implantations].

    PubMed

    Dördelmann, K; Tetsch, P; Ibing, G

    1977-04-01

    An animal experimental study was undertaken where the embedding of extension implants with a smooth or porous surface was histologically examined. Under extreme functional stress there occurs a mobility of the implants with the formation of a broad connective tissue zone, inflammatory reactions and ingrowth of epithelium, which is independent of the surface structure. Implants under less stress show a narrower connective tissue layer which narrows itself further if the surface is porous. The possible causes of this tissue reaction are discussed. PMID:266991

  7. Usefulness of an Implantable Loop Recorder to Detect Clinically Relevant Arrhythmias in Patients With Advanced Fabry Cardiomyopathy.

    PubMed

    Weidemann, Frank; Maier, Sebastian K G; Störk, Stefan; Brunner, Thomas; Liu, Dan; Hu, Kai; Seydelmann, Nora; Schneider, Andreas; Becher, Jan; Canan-Kühl, Sima; Blaschke, Daniela; Bijnens, Bart; Ertl, Georg; Wanner, Christoph; Nordbeck, Peter

    2016-07-15

    Patients with genetic cardiomyopathy that involves myocardial hypertrophy often develop clinically relevant arrhythmias that increase the risk of sudden death. Consequently, guidelines for medical device therapy were established for hypertrophic cardiomyopathy, but not for conditions with only anecdotal evidence of arrhythmias, like Fabry cardiomyopathy. Patients with Fabry cardiomyopathy progressively develop myocardial fibrosis, and sudden cardiac death occurs regularly. Because 24-hour Holter electrocardiograms (ECGs) might not detect clinically important arrhythmias, we tested an implanted loop recorder for continuous heart rhythm surveillance and determined its impact on therapy. This prospective study included 16 patients (12 men) with advanced Fabry cardiomyopathy, relevant hypertrophy, and replacement fibrosis in "loco typico." No patients previously exhibited clinically relevant arrhythmias on Holter ECGs. Patients received an implantable loop recorder and were prospectively followed with telemedicine for a median of 1.2 years (range 0.3 to 2.0 years). The primary end point was a clinically meaningful event, which required a therapy change, captured with the loop recorder. Patients submitted data regularly (14 ± 11 times per month). During follow-up, 21 events were detected (including 4 asystole, i.e., ECG pauses ≥3 seconds) and 7 bradycardia events; 5 episodes of intermittent atrial fibrillation (>3 minutes) and 5 episodes of ventricular tachycardia (3 sustained and 2 nonsustained). Subsequently, as defined in the primary end point, 15 events leaded to a change of therapy. These patients required therapy with a pacemaker or cardioverter-defibrillator implantation and/or anticoagulation therapy for atrial fibrillation. In conclusion, clinically relevant arrhythmias that require further device and/or medical therapy are often missed with Holter ECGs in patients with advanced stage Fabry cardiomyopathy, but they can be detected by telemonitoring with an implantable

  8. Processing and mechanical behavior of lamellar structured degradable magnesium-hydroxyapatite implants.

    PubMed

    Ratna Sunil, B; Ganapathy, C; Sampath Kumar, T S; Chakkingal, Uday

    2014-12-01

    Multilayered (laminated) composites exhibit tunable mechanical behavior compared to bulk materials due to the presence of more interfaces and therefore magnesium based composites are gaining wide popularity as biodegradable materials targeted for temporary implant applications. The objective of the present work is to fabricate magnesium based lamellar metal matrix composites (MMCs) for degradable implant applications. Nano-hydroxyapatite (HA) powder was selected as the secondary phase and lamellar structured magnesium-nano-hydroxyapatite (Mg-HA) composites of 8, 10 and 15wt% HA were fabricated by ball milling and spark plasma sintering. It was found that HA particles were coated on the Mg flakes after 20h of ball milling carried out using tungsten carbide (WC) as the milling media. Spark plasma sintering of the milled powders resulted in the formation of lamellar structure of Mg with the presence of HA and magnesium oxide (MgO) at the inter-lamellar sites of the composites. Phase analysis of the milled powder by an X-ray diffraction (XRD) method confirms the presence of HA and MgO along with Mg after sintering. Corrosion behavior of the composites investigated by potentiodynamic polarization tests shows a reduction in the inter-lamellar corrosion with increase in HA content and the best corrosion resistance is found for the Mg-10% HA composite. This composite also exhibits maximum Vickers hardness. Young׳s modulus and fracture toughness measured by nano-indentation method were higher for the Mg-8% HA composite. The results thus suggest that lamellar structured Mg composites with 8% and 10% HA show promise for temporary degradable orthopedic implant applications because of their improved corrosion resistance and superior mechanical properties. PMID:25241282

  9. Dynamic based damage detection in composite structures

    NASA Astrophysics Data System (ADS)

    Banerjee, Sauvik; Ricci, Fabrizio; Baid, Harsh; Mal, Ajit K.

    2009-03-01

    Advanced composites are being used increasingly in state-of-the-art aircraft and aerospace structures. In spite of their many advantages, composite materials are highly susceptible to hidden flaws that may occur at any time during the life cycle of a structure, and if undetected, may cause sudden and catastrophic failure of the entire structure. This paper is concerned with the detection and characterization of hidden defects in composite structures before they grow to a critical size. A methodology for automatic damage identification and localization is developed using a combination of vibration and wave propagation data. The structure is assumed to be instrumented with an array of actuators and sensors to excite and record its dynamic response, including vibration and wave propagation effects. A damage index, calculated from the measured dynamical response of the structure in a previous (reference) state and the current state, is introduced as a determinant of structural damage. The indices are used to identify low velocity impact damages in increasingly complex composite structural components. The potential application of the approach in developing health monitoring systems in defects-critical structures is indicated.

  10. PreImplantation factor (PIF) detection in maternal circulation in early pregnancy correlates with live birth (bovine model)

    PubMed Central

    2013-01-01

    Background Early identification of viable pregnancy is paramount for successful reproduction. Detection of specific signals from pre-implantation viable embryos in normal pregnancy circulation would indicate initiation of embryo-maternal interaction and create a continuum to accurately reflect embryo/fetal well-being post-implantation. Viable mammalian embryos secrete PreImplantation Factor (PIF), a biomarker which plays key, multi-targeted roles to promote implantation, trophoblast invasion and modulate maternal innate and adaptive immunity toward acceptance. Anti-PIF monoclonal antibody (mAb-based chemiluminescent ELISA) accurately detects PIF in singly cultured embryos media and its increased levels correlate with embryo development up to the blastocyst stage. Herein reported that PIF levels (ELISA) in early maternal serum correlate with pregnancy outcome. Methods Artificially inseminated (AI) blind-coded Angus cattle (N = 21-23) serum samples (day10,15 & 20 post-AI) with known calf birth were blindly tested, using both non-pregnant heifers (N = 30) and steer serum as negative controls. Assay properties and anti-PIF monoclonal antibody specificity were determined by examining linearity, spike and recovery experiments and testing the antibody against 234 different circulating proteins by microarray. Endogenous PIF was detected using <3 kDa filter separation followed by anti-PIF mAb-based affinity chromatography and confirmed by ELISA and HPLC. PIF expression was established in placenta using anti-PIF mAb-based IHC. Results PIF detects viable pregnancy at day 10 post-AI with 91.3% sensitivity, reaching 100% by day 20 and correlating with live calf birth. All non-pregnant samples were PIF negative. PIF level in pregnant samples was a stringent 3 + SD higher as compared to heifers and steer sera. Assay is linear and spike and recovery data demonstrates lack of serum interference. Anti-PIF mAb is specific and does not interact with circulating proteins

  11. Nanopore sequencing detects structural variants in cancer

    PubMed Central

    Norris, Alexis L.; Workman, Rachael E.; Fan, Yunfan; Eshleman, James R.; Timp, Winston

    2016-01-01

    ABSTRACT Despite advances in sequencing, structural variants (SVs) remain difficult to reliably detect due to the short read length (<300 bp) of 2nd generation sequencing. Not only do the reads (or paired-end reads) need to straddle a breakpoint, but repetitive elements often lead to ambiguities in the alignment of short reads. We propose to use the long-reads (up to 20 kb) possible with 3rd generation sequencing, specifically nanopore sequencing on the MinION. Nanopore sequencing relies on a similar concept to a Coulter counter, reading the DNA sequence from the change in electrical current resulting from a DNA strand being forced through a nanometer-sized pore embedded in a membrane. Though nanopore sequencing currently has a relatively high mismatch rate that precludes base substitution and small frameshift mutation detection, its accuracy is sufficient for SV detection because of its long reads. In fact, long reads in some cases may improve SV detection efficiency. We have tested nanopore sequencing to detect a series of well-characterized SVs, including large deletions, inversions, and translocations that inactivate the CDKN2A/p16 and SMAD4/DPC4 tumor suppressor genes in pancreatic cancer. Using PCR amplicon mixes, we have demonstrated that nanopore sequencing can detect large deletions, translocations and inversions at dilutions as low as 1:100, with as few as 500 reads per sample. Given the speed, small footprint, and low capital cost, nanopore sequencing could become the ideal tool for the low-level detection of cancer-associated SVs needed for molecular relapse, early detection, or therapeutic monitoring. PMID:26787508

  12. Nanopore sequencing detects structural variants in cancer.

    PubMed

    Norris, Alexis L; Workman, Rachael E; Fan, Yunfan; Eshleman, James R; Timp, Winston

    2016-03-01

    Despite advances in sequencing, structural variants (SVs) remain difficult to reliably detect due to the short read length (<300 bp) of 2nd generation sequencing. Not only do the reads (or paired-end reads) need to straddle a breakpoint, but repetitive elements often lead to ambiguities in the alignment of short reads. We propose to use the long-reads (up to 20 kb) possible with 3rd generation sequencing, specifically nanopore sequencing on the MinION. Nanopore sequencing relies on a similar concept to a Coulter counter, reading the DNA sequence from the change in electrical current resulting from a DNA strand being forced through a nanometer-sized pore embedded in a membrane. Though nanopore sequencing currently has a relatively high mismatch rate that precludes base substitution and small frameshift mutation detection, its accuracy is sufficient for SV detection because of its long reads. In fact, long reads in some cases may improve SV detection efficiency. We have tested nanopore sequencing to detect a series of well-characterized SVs, including large deletions, inversions, and translocations that inactivate the CDKN2A/p16 and SMAD4/DPC4 tumor suppressor genes in pancreatic cancer. Using PCR amplicon mixes, we have demonstrated that nanopore sequencing can detect large deletions, translocations and inversions at dilutions as low as 1:100, with as few as 500 reads per sample. Given the speed, small footprint, and low capital cost, nanopore sequencing could become the ideal tool for the low-level detection of cancer-associated SVs needed for molecular relapse, early detection, or therapeutic monitoring. PMID:26787508

  13. Etching and structural changes in nitrogen plasma immersion ion implanted polystyrene films

    NASA Astrophysics Data System (ADS)

    Gan, B. K.; Bilek, M. M. M.; Kondyurin, A.; Mizuno, K.; McKenzie, D. R.

    2006-06-01

    Plasma immersion ion implantation (PIII), with nitrogen ions of energy 20 keV in the fluence range of 5 × 1014-2 × 1016 ions cm-2, is used to modify 100 nm thin films of polystyrene on silicon wafer substrates. Ellipsometry is used to study changes in thickness with etching and changes in optical constants. Two distinctly different etch rates are observed as the polymer structure is modified. FTIR spectroscopy data reveals the structural changes, including changes in aromatic and aliphatic groups and oxidation and carbonisation processes, occurring in the polystyrene film as a function of the ion fluence. The transformation to a dense amorphous carbon-like material was observed to progress through an intermediate structural form containing a high concentration of Cdbnd C and Cdbnd O bonds.

  14. RX Puppis - Detection of asymmetrical radio structure

    NASA Technical Reports Server (NTRS)

    Hollis, J. M.; Yusef-Zadeh, F.; Oliversen, R. J.; Michalitsianos, A. G.; Cornwell, T. J.

    1989-01-01

    Subarcsecond observations of the RX Puppis symbiotic system with the VLA have resolved 2 cm continuum emission which deviates from a previously reported circularly symmetric radio distribution. The radio structure is comprised of at least three nearly colinear components. Under the assumption that the strongest feature is coincident with the hot star, the other two features lie 230 and 590 AU distant. These radio features are reminiscent of small-scale radio structure detected toward R Aquarii, another symbiotic star system, and probably represents material ejected from the RX Puppis system at an earlier epoch.

  15. Leak detection using structure-borne noise

    NASA Technical Reports Server (NTRS)

    Holland, Stephen D. (Inventor); Chimenti, Dale E. (Inventor); Roberts, Ronald A. (Inventor)

    2010-01-01

    A method for detection and location of air leaks in a pressure vessel, such as a spacecraft, includes sensing structure-borne ultrasound waveforms associated with turbulence caused by a leak from a plurality of sensors and cross correlating the waveforms to determine existence and location of the leak. Different configurations of sensors and corresponding methods can be used. An apparatus for performing the methods is also provided.

  16. Magnetic and structural properties of CoCrPt-SiO2-based graded media prepared by ion implantation

    NASA Astrophysics Data System (ADS)

    Gaur, Nikita; Pandey, K. K. M.; Maurer, S. L.; Piramanayagam, S. N.; Nunes, R. W.; Yang, H.; Bhatia, C. S.

    2011-10-01

    The magnetic and structural properties of graded media fabricated by ion implantation of nitrogen (14 N+), oxygen (16O+), and cobalt (59Co+) ions in the CoCrPt-SiO2 recording layer of prototype disk have been studied. Ion implantation of the species was controlled at the atomic scale to fabricate the graded media. Magnetometric measurements indicated that the coercivity was reduced with an increasing dose of the implanted species. The observation of an increase in magnetic domain size has been attributed to the reduction in magnetocrystalline anisotropy energy, which is desirable for achieving graded media. The study indicates that the magnetic properties can be tailored by the appropriate selection of the implantation dose and species.

  17. Mechanisms of formation of nonlinear optical light guide structures in metal cluster composites produced by ion beam implantation

    SciTech Connect

    Sarkisov, S.S.; Williams, E.K.; Curley, M.; Smith, C.C.; Ila, D.; Venkateswarlu, P.; Poker, D.B.; Hensley, D.K.

    1997-11-01

    Ion implantation has been shown to produce a high density of metal colloids in glasses and crystalline materials. The high-precipitate volume fraction and small size of metal nanoclusters formed leads to values for the third-order susceptibility much greater than those for metal doped solids. This has stimulated interest in use of ion implantation to make nonlinear optical materials. On the other side, LiNbO{sub 3} has proved to be a good material for optical waveguides produced by MeV ion implantation. Light confinement in these waveguides is produced by refractive index step difference between the implanted region and the bulk material. Implantation of LiNbO{sub 3} with MeV metal ions can therefore result into nonlinear optical waveguide structures with great potential in a variety of device applications. The authors describe linear and nonlinear optical properties of a waveguide structure in LiNbO{sub 3}-based composite material produced by silver ion implantation in connection with mechanisms of its formation.

  18. Quantum structures for multiband photon detection

    NASA Astrophysics Data System (ADS)

    Perera, A. G. U.

    2005-09-01

    The work describes multiband photon detectors based on semiconductor micro- and nano-structures. The devices considered include quantum dot, homojunction, and heterojunction structures. In the quantum dot structures, transitions are from one state to another, while free carrier absorption and internal photoemission play the dominant role in homo or heterojunction detectors. Quantum Dots-in-a-Well (DWELL) detectors can tailor the response wavelength by varying the size of the well. A tunneling Quantum Dot Infrared Photodetector (T-QDIP) could operate at room temperature by blocking the dark current except in the case of resonance. Photoexcited carriers are selectively collected from InGaAs quantum dots by resonant tunneling, while the dark current is blocked by AlGaAs/InGaAs tunneling barriers placed in the structure. A two-color infrared detector with photoresponse peaks at ~6 and ~17 μm at room temperature will be discussed. A Homojunction or HEterojunction Interfacial Workfunction Internal Photoemission (HIWIP or HEIWIP) infrared detector, formed by a doped emitter layer, and an intrinsic layer acting as the barrier followed by another highly doped contact layer, can detect near infrared (NIR) photons due to interband transitions and mid/far infrared (MIR/FIR) radiation due to intraband transitions. The threshold wavelength of the interband response depends on the band gap of the barrier material, and the MIR/FIR response due to intraband transitions can be tailored by adjusting the band offset between the emitter and the barrier. GaAs/AlGaAs will provide NIR and MIR/FIR dual band response, and with GaN/AlGaN structures the detection capability can be extended into the ultraviolet region. These detectors are useful in numerous applications such as environmental monitoring, medical diagnosis, battlefield-imaging, space astronomy applications, mine detection, and remote-sensing.

  19. The structure and tribological properties of gradient layers prepared by plasma-based ion implantation on 2024 Al alloy

    NASA Astrophysics Data System (ADS)

    Liao, J. X.; Xia, L. F.; Sun, M. R.; Liu, W. M.; Xu, T.; Xue, Q. J.

    2004-02-01

    Using plasma-based ion implantation, two types of gradient layers have been prepared on 2024 Al alloy. One is prepared by N-implantation then C-deposition, the other adds an interlayer composed of a Ti layer and a Ti-N layer between N-implantation and C-deposition. C-deposition is carried out at various implanting voltages or C2H2/H2 ratios. The composition depth profiles of these layers were characterized by x-ray photoelectron spectroscopy. The structure, morphologies and microstructure of the C layers were studied using Raman spectroscopy, atomic force microscope and transmission electron microscope, respectively. The surface hardness was measured with a Knoop tester and a mechanical property microprobe. The dry ball-on-disc wear tests were performed in ambient air. The gradient layer without interlayer is composed of an N-implanted layer rich in AlN and a diamond-like carbon (DLC) layer (film), and the two layers are connected with a C-Al transition layer containing Al4C3. The Ti layer rich in agr -Ti and the N-implanted layer are connected by a Ti-Al transition layer containing TiAl3, while the Ti-N layer rich in TiN and the DLC film are connected by a C-Ti transition layer containing TiC, TiCN, etc. Thus, the gradient layer with interlayers has optimized the gradient structure. DLC films are compact and amorphous, contain high sp3/sp2 ratios and depend on the implanting voltage and the C2H2/H2 ratio. Similarly, these gradient layers exhibit significant improvement in morphologies, surface hardness and tribological properties; the interlayer, the implanting voltage and the C2H2/H2 ratio all have prominent effects on these properties.

  20. Feasibility of Structural and Functional MRI Acquisition with Unpowered Implants in Argus II Retinal Prosthesis Patients: A Case Study

    PubMed Central

    Cunningham, Samantha I.; Shi, Yonggang; Weiland, James D.; Falabella, Paulo; Olmos de Koo, Lisa C.; Zacks, David N.; Tjan, Bosco S.

    2015-01-01

    Purpose Magnetic resonance imaging (MRI) can measure the effects of vision loss and recovery on brain function and structure. In this case study, we sought to determine the feasibility of acquiring anatomical and functional MRI data in recipients of the Argus II epiretinal prosthesis system. Methods Following successful implantation with the Argus II device, two retinitis pigmentosa (RP) patients completed MRI scans with their implant unpowered to measure primary visual cortex (V1) functional responses to a tactile task, whole-brain morphometry, V1 cortical thickness, and diffusion properties of the optic tract and optic radiation. Measurements in the subjects with the Argus II implant were compared to measurements obtained previously from RP patients and sighted individuals. Results The presence of the Argus II implant resulted in artifacts that were localized around the patient's implanted eye and did not extend into cortical regions or white matter tracts associated with the visual system. Structural data on V1 cortical thickness and the retinofugal tract obtained from the two Argus II subjects fell within the ranges of sighted and RP groups. When compared to the RP and sighted subjects, Argus II patients' tactile-evoked cross-modal functional MRI (fMRI) blood oxygen level-dependent (BOLD) responses in V1 also fell within the range of either sighted or RP groups, apparently depending on time since implantation. Conclusions This study demonstrates that successful acquisition and quantification of structural and functional MR images are feasible in the presence of the inactive implant and provides preliminary information on functional changes in the brain that may follow sight restoration treatments. Transitional Relevance Successful MRI and fMRI acquisition in Argus II recipients demonstrates feasibility of using MRI to study the effect of retinal prosthesis use on brain structure and function. PMID:26693097

  1. Intelligent-based Structural Damage Detection Model

    SciTech Connect

    Lee, Eric Wai Ming; Yu, K.F.

    2010-05-21

    This paper presents the application of a novel Artificial Neural Network (ANN) model for the diagnosis of structural damage. The ANN model, denoted as the GRNNFA, is a hybrid model combining the General Regression Neural Network Model (GRNN) and the Fuzzy ART (FA) model. It not only retains the important features of the GRNN and FA models (i.e. fast and stable network training and incremental growth of network structure) but also facilitates the removal of the noise embedded in the training samples. Structural damage alters the stiffness distribution of the structure and so as to change the natural frequencies and mode shapes of the system. The measured modal parameter changes due to a particular damage are treated as patterns for that damage. The proposed GRNNFA model was trained to learn those patterns in order to detect the possible damage location of the structure. Simulated data is employed to verify and illustrate the procedures of the proposed ANN-based damage diagnosis methodology. The results of this study have demonstrated the feasibility of applying the GRNNFA model to structural damage diagnosis even when the training samples were noise contaminated.

  2. Implantable polymer/metal thin film structures for the localized treatment of cancer by Joule heating

    NASA Astrophysics Data System (ADS)

    Kan-Dapaah, Kwabena; Rahbar, Nima; Theriault, Christian; Soboyejo, Wole

    2015-04-01

    This paper presents an implantable polymer/metal alloy thin film structure for localized post-operative treatment of breast cancer. A combination of experiments and models is used to study the temperature changes due to Joule heating by patterned metallic thin films embedded in poly-dimethylsiloxane. The heat conduction within the device and the surrounding normal/cancerous breast tissue is modeled with three-dimensional finite element method (FEM). The FEM simulations are used to explore the potential effects of device geometry and Joule heating on the temperature distribution and lesion (thermal dose). The FEM model is validated using a gel model that mimics biological media. The predictions are also compared to prior results from in vitro studies and relevant in vivo studies in the literature. The implications of the results are discussed for the potential application of polymer/metal thin film structures in hyperthermic treatment of cancer.

  3. Structural health monitoring and impact detection for primary aircraft structures

    NASA Astrophysics Data System (ADS)

    Kosters, Eric; van Els, Thomas J.

    2010-04-01

    The increasing use of thermoplastic carbon fiber-reinforced plastic (CFRP) materials in the aerospace industry for primary aircraft structures, such as wing leading-edge surfaces and fuselage sections, has led to rapid growth in the field of structural health monitoring (SHM). Impact, vibration, and load can all cause failure, such as delamination and matrix cracking, in composite materials. Moreover, the internal material damage can occur without being visible to the human eye, making inspection of and clear insight into structural integrity difficult using currently available evaluation methods. Here, we describe the detection of impact and its localization in materials and structures by high-speed interrogation of multiple-fiber Bragg grating (FBG) sensors mounted on a composite aircraft component.

  4. Finite element analysis and cellular studies on advanced, controlled porous structures with subsurface continuity in bio-implantable titanium alloys.

    PubMed

    Lambert, P; Ankem, S; Wyatt, Z; Ferlin, K M; Fisher, J

    2014-01-01

    Highly-porous metallic implant onlay materials (specifically those containing surface pores that intersect beneath the onlay surface) have been investigated recently for their potential to reduce bone resorption and to improve the overall stability of the implant. In the current study, sub-surface interconnectivity of high-aspect-ratio pores was created directly in the substrate of an implant material using wire electrical discharge machining (EDM). This technique was used to produce intersecting pores with diameters of 180-250 μm on a clinically relevant implant material—commercially pure (CP) Grade 4 Ti—with a very high degree of control over pore morphology. These pores resulted in no significant microstructural modification to the surrounding Ti, and the inner pore surfaces could be thermally oxidized to produce a microrough, bioactive TiO2 layer. Finite element analysis of Ti models containing these EDM-attainable intersecting pore geometries suggested they produce higher bone/implant interface strengths and lower susceptibility to stress shielding of the surrounding bone as compared with models containing simpler surface geometries. In vitro experiments using mesenchymal stem cells (MSCs) demonstrated mineralized tissue ingrowth of ∼ 300 μm into EDM-produced pores. This amount of ingrowth is expected to allow for full interlocking of mineralized tissue and implant given the proper pore structure design. PMID:23686820

  5. High Mobility SiGe/Si Transistor Structures on Sapphire Substrates Using Ion Implantation

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Mueller, C. H.; Croke, E. T.

    2003-01-01

    High mobility n-type SiGe/Si transistor structures have been fabricated on sapphire substrates by ion implanting phosphorus ions into strained 100 Angstrom thick silicon channels for the first time. The strained Si channels were sandwiched between Si(sub 0.7)Ge(sub 0.3) layers, which, in turn, were deposited on Si(sub 0.7)Ge(sub 0.3) virtual substrates and graded SiGe buffer layers. After the molecular beam epitaxy (MBE) film growth process was completed, ion thick silicon channels implantation and post-annealing were used to introduce donors. The phosphorous ions were preferentially located in the Si channel at a peak concentration of approximately 1x10(exp 18)/cu cm. Room temperature electron mobilities exceeding 750 sq cm/V-sec at carrier densities of 1x10(exp 12)/sq cm were measured. Electron concentration appears to be the key factor that determines mobility, with the highest mobility observed for electron densities in the 1 - 2x10(exp 12)/sq cm range.

  6. Doping of Graphene by Low-Energy Ion Beam Implantation: Structural, Electronic, and Transport Properties.

    PubMed

    Willke, Philip; Amani, Julian A; Sinterhauf, Anna; Thakur, Sangeeta; Kotzott, Thomas; Druga, Thomas; Weikert, Steffen; Maiti, Kalobaran; Hofsäss, Hans; Wenderoth, Martin

    2015-08-12

    We investigate the structural, electronic, and transport properties of substitutional defects in SiC-graphene by means of scanning tunneling microscopy and magnetotransport experiments. Using ion incorporation via ultralow energy ion implantation, the influence of different ion species (boron, nitrogen, and carbon) can directly be compared. While boron and nitrogen atoms lead to an effective doping of the graphene sheet and can reduce or raise the position of the Fermi level, respectively, (12)C(+) carbon ions are used to study possible defect creation by the bombardment. For low-temperature transport, the implantation leads to an increase in resistance and a decrease in mobility in contrast to undoped samples. For undoped samples, we observe in high magnetic fields a positive magnetoresistance that changes to negative for the doped samples, especially for (11)B(+)- and (12)C(+)-ions. We conclude that the conductivity of the graphene sheet is lowered by impurity atoms and especially by lattice defects, because they result in weak localization effects at low temperatures. PMID:26120803

  7. Feasibility of fully automated detection of fiducial markers implanted into the prostate using electronic portal imaging: A comparison of methods

    SciTech Connect

    Harris, Emma J. . E-mail: eharris@icr.ac.uk; McNair, Helen A.; Evans, Phillip M.

    2006-11-15

    Purpose: To investigate the feasibility of fully automated detection of fiducial markers implanted into the prostate using portal images acquired with an electronic portal imaging device. Methods and Materials: We have made a direct comparison of 4 different methods (2 template matching-based methods, a method incorporating attenuation and constellation analyses and a cross correlation method) that have been published in the literature for the automatic detection of fiducial markers. The cross-correlation technique requires a-priory information from the portal images, therefore the technique is not fully automated for the first treatment fraction. Images of 7 patients implanted with gold fiducial markers (8 mm in length and 1 mm in diameter) were acquired before treatment (set-up images) and during treatment (movie images) using 1MU and 15MU per image respectively. Images included: 75 anterior (AP) and 69 lateral (LAT) set-up images and 51 AP and 83 LAT movie images. Using the different methods described in the literature, marker positions were automatically identified. Results: The method based upon cross correlation techniques gave the highest percentage detection success rate of 99% (AP) and 83% (LAT) set-up (1MU) images. The methods gave detection success rates of less than 91% (AP) and 42% (LAT) set-up images. The amount of a-priory information used and how it affects the way the techniques are implemented, is discussed. Conclusions: Fully automated marker detection in set-up images for the first treatment fraction is unachievable using these methods and that using cross-correlation is the best technique for automatic detection on subsequent radiotherapy treatment fractions.

  8. Thermal migration of deuterium implanted in graphite: Influence of free surface proximity and structure

    NASA Astrophysics Data System (ADS)

    Le Guillou, M.; Moncoffre, N.; Toulhoat, N.; Pipon, Y.; Ammar, M. R.; Rouzaud, J. N.; Deldicque, D.

    2016-03-01

    This paper is a contribution to the study of the behavior of activation products produced in irradiated nuclear graphite, graphite being the moderator of the first French generation of CO2 cooled nuclear fission reactors. This paper is focused on the thermal release of Tritium, a major contributor to the initial activity, taking into account the role of the free surfaces (open pores and graphite surface). Two kinds of graphite were compared. On one hand, Highly Oriented Pyrolitic Graphite (HOPG), a model well graphitized graphite, and on the other hand, SLA2, a porous less graphitized nuclear graphite. Deuterium ion implantation at three different energies 70, 200 and 390 keV allows simulating the presence of Tritium at three different depths, corresponding respectively to projected ranges Rp of 0.75, 1.7 and 3.2 μm. The D isotopic tracing is performed thanks to the D(3He,p)4He nuclear reaction. The graphite structure is studied by Raman microspectrometry. Thermal annealing is performed in the temperature range 200-1200 °C up to 300 h annealing time. As observed in a previous study, the results show that the D release occurs according to three kinetic regimes: a rapid permeation through open pores, a transient regime corresponding to detrapping and diffusion of D located at low energy sites correlated to the edges of crystallites and finally a saturation regime attributed to detrapping of interstitial D located at high energy sites inside the crystallites. Below 600 °C, D release is negligible whatever the implantation depth and the graphite type. The present paper clearly puts forward that above 600 °C, the D release decreases at deeper implantation depths and strongly depends on the graphite structure. In HOPG where high energy sites are more abundant, the D release is less dependent on the surface proximity compared to SLA2. In SLA2, in which the low energy sites prevail, the D release curves are clearly shifted towards lower temperatures when D is located

  9. Structural defects and electronic structure of N-ion implanted TiO2: Bulk versus thin film

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Boukhvalov, D. W.; Kurmaev, E. Z.; Zhidkov, I. S.; Gavrilov, N. V.; Korotin, M. A.; Kim, S. S.

    2015-11-01

    Systematic investigation of atomic structure of N-ion implanted TiO2 (thin films and bulk ceramics) was performed by XPS measurements (core levels and valence bands) and first-principles density functional theory (DFT) calculations. In bulk samples experiment and theory demonstrate anion N → O substitution. For the thin films case experiments evidence valuable contributions from N2 and NO molecule-like structures and theoretical modeling reveals a possibility of formation of these species as result of the appearance of interstitial nitrogen defects on the various surfaces of TiO2. Energetics of formation of oxygen vacancies and its key role for band gap reduction is also discussed.

  10. Ion implantation induced modification of structural and magnetic properties of perpendicular media

    NASA Astrophysics Data System (ADS)

    Gaur, Nikita; Piramanayagam, S. N.; Maurer, S. L.; Nunes, R. W.; Steen, S.; Yang, H.; Bhatia, C. S.

    2011-09-01

    This study reports the effects of implanting various doses of boron (11B+) and argon (40Ar+) ions into the recording layer and the soft underlayer of CoCrPt-SiO2-based perpendicular recording media. Implantation of a lower dose of boron ions (1011 ions cm-2) in the recording layer was found to reduce the out-of-plane coercivity, whereas no changes in the coercivity were observed when they were implanted into the soft underlayer. In the case of argon ions, lower dose implantation did not show any changes in the coercivity, irrespective of the implanted layer. However, higher dose implantations (1016 ions cm-2) of all the species were found to cause a reduction in coercivity, irrespective of the implanted layer. The reduction in coercivity was more significant when the ions were implanted in the recording layer compared with the case of implantation in the soft underlayer. X-ray diffraction (XRD) results on samples where argon was implanted in the recording layer showed a strong shift in the position of Co (0 0 .2) peaks, indicating an increase in the 'c' parameter. The shift is explained, on the basis of x-ray photoelectron spectroscopy, to be arising from intra-layer mixing at the CoCrPt-SiO2/Ru interface. Magnetic force microscopy images indicated an increase in domain size arising from the ion implantation.

  11. Ion implantation processing of sub-stoichiometric titanium nitrides and carbonitrides: chemical structural and micromechanical investigations

    NASA Astrophysics Data System (ADS)

    Guemmaz, M.; Mosser, A.; Grob, J. J.

    Sub-stoichiometric titanium nitrides TiNx ( , and ) and carbonitride TiNxCy ( ) were synthesized at the titanium surface by multiple energy (180, 100, 50 and 20 keV) ion implantation. The in-depth distributions of carbon and nitrogen deduced from RBS and SIMS spectra were compared with TRIM calculations. From the X-ray grazing incidence we observed the following structures: (i) An NaCl type structure for TiN0.35C0.35 and TiN0.61, the latter is commonly known as -titanium nitride; (ii) A nitrogen solid solution in an -Ti structure for TiN0.25, and a mixture of both structures for TiN0.45. In the case of the NaCl structures, the layers were composed of very small strained crystallites (nanocrystals). X-ray photoelectron spectroscopy of C , N and Ti levels, as well as the valence band spectrum, show that the carbon and the nitrogen are fully bonded to titanium. Nanoindentation measurements show an elastoplastic behavior for the layers. The hardness and Young's modulus were derived from load-displacement curves. The results were discussed in the light of the published work.

  12. Electronic structure and photoluminescence properties of Zn-ion implanted silica glass before and after thermal annealing

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Zatsepin, A. F.; Boukhvalov, D. W.; Kurmaev, E. Z.; Pchelkina, Z. V.; Gavrilov, N. V.

    2016-01-01

    The results of XPS core-level and valence band measurements, photoluminescence spectra of a-SiO2 implanted by Zn-ions (E=30 keV, D=1*1017 cm^-2) and Density Functional Theory calculations of electronic structure as well as formation energies of structural defects in silica glass induced by Zn-ion implantation are presented. Both theory and experiment show that it is energetically more favorable for implanted zinc ions to occupy the interstitial positions instead of cation substitution. As a result, the Zn-ions embedded to interstitials, form chemical bonds with the surrounding oxygen atoms, formation ZnO-like nanoparticles and oxygen-deficient SiOx matrix. The subsequent thermal annealing at 900 0C (1 hr) strongly reduces the amount of ZnO nanoparticles and induces the formation of {\\alpha}-Zn2SiO4 phase which markedly enhances the green emission.

  13. Detection of refrigerator-associated 60 Hz alternating current as ventricular fibrillation by an implantable defibrillator.

    PubMed

    Al Khadra, Ayman S; Al Jutaily, Abdulaziz; Al Shuhri, Salem

    2006-03-01

    This report describes a patient with an implantable defibrillator who suffered an inappropriate defibrillation shock upon retrieving some food items from his inadequately earthed refrigerator. Noise typical of electrical interference can be observed in the stored electrogram of the episode. The patient was instructed to earth his home appliances, but he decided to avoid his refrigerator altogether, and has had no subsequent shocks. PMID:16627434

  14. Optimization of a Low Noise Detection Circuit for Probing the Structure of Damage Cascades with IBIC

    NASA Astrophysics Data System (ADS)

    Auden, Elizabeth C.; Doyle, Barney L.; Bielejec, Edward; Vizkelethy, Gyorgy; Wampler, William R.

    Optimal detector / pre-amplifier combinations have been identified for the use of light ion IBIC (ion beam induced charge) to probe the physical structure of electrically active defects in damage cascades caused by heavy ion implantation. The ideal detector must have a sufficiently thin dead layer that incident ions will produce the majority of damage cascades in the depletion region of the detector rather than the dead layer. Detector and circuit noise must be low enough to detect the implantation of a single heavy ion as well as the decrease in the light ion IBIC signal caused by Shockley-Read-Hall recombination when the beam scans regions of the detector damaged by the heavy ion. The IBIC signals from three detectors irradiated with 750 keV He+ ions are measured with commercial and bespoke charge sensitive pre-amplifiers to identify the combination with the lowest noise.

  15. Optimization of a low noise detection circuit for probing the structure of damage cascades with IBIC

    SciTech Connect

    Auden, Elizabeth C.; Doyle, Barney L.; Bielejec, Edward; Vizkelethy, Gyorgy; Wampler, William R.

    2015-06-18

    Optimal detector / pre-amplifier combinations have been identified for the use of light ion IBIC (ion beam induced charge) to probe the physical structure of electrically active defects in damage cascades caused by heavy ion implantation. The ideal detector must have a sufficiently thin dead layer that incident ions will produce the majority of damage cascades in the depletion region of the detector rather than the dead layer. Detector and circuit noise must be low enough to detect the implantation of a single heavy ion as well as the decrease in the light ion IBIC signal caused by Shockley-Read-Hall recombination when the beam scans regions of the detector damaged by the heavy ion. The IBIC signals from three detectors irradiated with 750 keV He⁺ ions are measured with commercial and bespoke charge sensitive pre-amplifiers to identify the combination with the lowest noise.

  16. Optimization of a low noise detection circuit for probing the structure of damage cascades with IBIC

    DOE PAGESBeta

    Auden, Elizabeth C.; Doyle, Barney L.; Bielejec, Edward; Vizkelethy, Gyorgy; Wampler, William R.

    2015-06-18

    Optimal detector / pre-amplifier combinations have been identified for the use of light ion IBIC (ion beam induced charge) to probe the physical structure of electrically active defects in damage cascades caused by heavy ion implantation. The ideal detector must have a sufficiently thin dead layer that incident ions will produce the majority of damage cascades in the depletion region of the detector rather than the dead layer. Detector and circuit noise must be low enough to detect the implantation of a single heavy ion as well as the decrease in the light ion IBIC signal caused by Shockley-Read-Hall recombinationmore » when the beam scans regions of the detector damaged by the heavy ion. The IBIC signals from three detectors irradiated with 750 keV He⁺ ions are measured with commercial and bespoke charge sensitive pre-amplifiers to identify the combination with the lowest noise.« less

  17. Investigation of various phases of Fe-Si structures formed in Si by low energy Fe ion implantation

    NASA Astrophysics Data System (ADS)

    Lakshantha, Wickramaarachchige J.; Dhoubhadel, Mangal S.; Reinert, Tilo; McDaniel, Floyd D.; Rout, Bibhudutta

    2015-12-01

    The compositional phases of ion beam synthesized Fe-Si structures at two high fluences (0.50 × 1017 atoms/cm2 and 2.16 × 1017 atoms/cm2) were analyzed using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The distribution of Fe implanted in Si was simulated using a dynamic simulation code (TRIDYN) incorporating target sputtering effects. The Fe depth profiles in the Si matrix were confirmed with Rutherford backscattering spectrometry (RBS) and XPS depth profiling using Ar-ion etching. Based on XPS binding energy shift and spectral asymmetry, the distribution of stable Fe-Si phases in the substrate was analyzed as a function of depth. Results indicate Fe implantation with a fluence of 0.50 × 1017 atoms/cm2 and subsequent thermal annealing produce mainly the β-FeSi2 phase in the whole thickness of the implanted region. But for the samples with a higher fluence Fe implantation, multiple phases are formed. Significant amount of Fe3Si phase are found at depth intervals of 14 nm and 28 nm from the surface. Initially, as-implanted samples show amorphous Fe3Si formation and further thermal annealing at 500 °C for 60 min formed crystalline Fe3Si structures at the same depth intervals. In addition, thermal annealing at 800 °C for 60 min restructures the Fe3Si clusters to form FeSi2 and FeSi phases.

  18. Local Arsenic Structure in Shallow Implants in Si following SPER: an EXAFS and MEIS study

    SciTech Connect

    Pepponi, G.; Giubertoni, D.; Gennaro, S.; Bersani, M.; Anderle, M.; Grisenti, R.; Werner, M.; Berg, J. A. van den

    2006-11-13

    Solid phase epitaxial regrowth (SPER) has been investigated in the last few years as a possible method to form ultra shallow dopant distributions in silicon with a high level of electrical. Despite the interest for this process, few investigations were related to arsenic. Apart from the fact that it is easier to form shallow distribution with arsenic than with boron, it is also well known that at the moderate temperatures implied by SPER (500-700 deg. C) arsenic easily deactivates, probably by forming inactive clusters around point defects in silicon. In order to have a better understanding of the SPER process for arsenic implanted silicon in shallow regime, an EXAFS (extended x-ray absorption fine structure) and MEIS (medium energy ion scattering) study is reported in this paper. Silicon samples were implanted at 3 keV with arsenic ions (dose was 2E15 at/cm2 producing a 11 nm amorphous layer) and then annealed in nitrogen at temperatures ranging from 500 to 700 deg. C to have different levels of recrystallisation. From the comparison of the recrystallised fraction as measured by MEIS with the electrical activation measured by Hall effect it results evident that a full regrowth of the lattice is not reflected by a high electrical activation. The activated arsenic corresponds to less than one third of the apparently substitutional dopant for all the samples analyzed. This lack of activation was further investigated by EXAFS: the samples that according to MEIS are fully recrystallised do not reveal a clear local order around As atoms suggesting that either the As atoms are not yet completely relocated within the lattice sites or a deactivation occurred resulting in a more disordered local structure.

  19. Characterization of porous glass fiber-reinforced composite (FRC) implant structures: porosity and mechanical properties.

    PubMed

    Ylä-Soininmäki, Anne; Moritz, Niko; Lassila, Lippo V J; Peltola, Matti; Aro, Hannu T; Vallittu, Pekka K

    2013-12-01

    The aim of this study was to characterize the microstructure and mechanical properties of porous fiber-reinforced composites (FRC). Implants made of the FRC structures are intended for cranial applications. The FRC specimens were prepared by impregnating E-glass fiber sheet with non-resorbable bifunctional bis-phenyl glycidyl dimethacrylate and triethylene glycol dimethacrylate resin matrix. Four groups of porous FRC specimens were prepared with a different amount of resin matrix. Control group contained specimens of fibers, which were bound together with sizing only. Microstructure of the specimens was analyzed using a micro computed tomography (micro-CT) based method. Mechanical properties of the specimens were measured with a tensile test. The amount of resin matrix in the specimens had an effect on the microstructure. Total porosity was 59.5 % (median) in the group with the lowest resin content and 11.2 % (median) in the group with the highest resin content. In control group, total porosity was 94.2 % (median). Correlations with resin content were obtained for all micro-CT based parameters except TbPf. The tensile strength of the composites was 21.3 MPa (median) in the group with the highest resin content and 43.4 MPa (median) in the group with the highest resin content. The tensile strength in control group was 18.9 MPa (median). There were strong correlations between the tensile strength of the specimens and most of the micro-CT based parameters. This experiment suggests that porous FRC structures may have the potential for use in implants for cranial bone reconstructions, provided further relevant in vitro and in vivo tests are performed. PMID:23929214

  20. Impact detection on airborne multilayered structures

    NASA Astrophysics Data System (ADS)

    Noharet, Bertrand; Chazelas, Jean; Bonniau, Philippe; Lecuellet, Jerome; Turpin, Marc J.

    1995-04-01

    This paper reviews the progress of an ongoing research program at Thomson-CSF and Bertin & Cie which addresses an optical fiber system dedicated to the assessment of impact induced damages on airborne multilayered structures. The method is based on the use of embedded high birefringence optical fiber sensors and distributed white light interfero-polarimetry. The first part is devoted to the transduction process efficiency within optical fibers depending on the applied force intensity, direction versus the fiber eigen axes and the interaction length. To understand the behavior of these optical fibers and calibrate the detection system, experiments have been conducted on elliptical core fibers, `bow-tie' fibers and side-hole fibers and showed a wide range of available sensitivities. The second step is related to the inclusion of optical fibers in a sandwich structure representative of an airborne dome, and composed of foam between glass/epoxy composite skins. Different designs of grooves in the foam and tube sheathings have been investigated to support and protect the optical fiber. Impacts have been performed on the structure in the 1 to 10 Joules energy range. Experimental impact location and energy measurements have been achieved for a variety of stress fields.

  1. Structural modifications of alumina implanted with zirconium, copper, and titanium ions

    NASA Astrophysics Data System (ADS)

    Bigarré, J.; Fayeulle, S.; Tréheux, D.; Moncoffre, N.

    1997-10-01

    Microstructural modifications (amorphization, lattice deformation, phase transformations) in alumina induced by implantation of zirconium, copper, or titanium ions and by postimplantation thermal annealings were studied using grazing incidence x-ray diffraction. It was shown that the amount of lattice deformation and the type of damage resulting in the lattice depend on the ion implanted. When zirconium was implanted, the alumina lattice was highly deformed. Amorphization was observed when a high ion dose was implanted. Copper implantation led to the formation of gamma alumina. With titanium ions, very high strain was created and delta alumina was formed. After postimplantation annealings, lattices returned to their equilibrium state through crystallization of alpha alumina and precipitation of oxides of the implanted species (ZrO2, CuO and CuAl2O4, and TiO2).

  2. Electrical and structural analysis of high-dose Si implantation in GaN

    SciTech Connect

    Zolper, J.C.; Tan, H.H.; Williams, J.S.; Zou, J.; Cockayne, D.J.; Pearton, S.J.; Crawford, M.H.; Karlicek, R.F. , Jr.

    1997-05-01

    For the development of ion implantation processes for GaN to advanced devices, it is important to understand the dose dependence of impurity activation along with implantation-induced damage generation and removal. We find that Si implantation in GaN can achieve 50{percent} activation at a dose of 1{times}10{sup 16} cm{sup {minus}2}, despite significant residual damage after the 1100{degree}C activation anneal. The possibility that the generated free carriers are due to implantation damage alone and not Si-donor activation is ruled out by comparing the Si results to those for implantation of the neutral species Ar. Ion channeling and cross-sectional transmission electron microscopy are used to characterize the implantation-induced damage both as implanted and after a 1100{degree}C anneal. Both techniques confirm that significant damage remains after the anneal, which suggests that activation of implanted Si donors in GaN doses not require complete damage removal. However, an improved annealing process may be needed to further optimize the transport properties of implanted regions in GaN. {copyright} {ital 1997 American Institute of Physics.}

  3. Structural-phase changes in Al6061-T6 alloy during high-dose N-2(+) implantation

    NASA Astrophysics Data System (ADS)

    Soukieh, M.

    2004-02-01

    N 2 + nitrogen ions with an energy of 50 keV were implanted into Al6061-T6 alloy with high dose (10(16) - 2 x 10(17) ions/cm(2)) at room temperature in order to form thin aluminium nitride (AlN) layers. The structural-phase changes in implanted Al 6061-T6 alloy were investigated using Rutherford back-scattering and transmission electron microscopic techniques. The results indicate that nitrogen implantation led to the formation of nitride phases (AlN, Al7N C-3(3)) which improved the surface hardness by 80% and increased the electrical resistance up to 1800% at maximum dose (2 x 10(17) ions/cm(2)).

  4. Structural, optical, and magnetic properties of highly-resistive Sm-implanted GaN thin films

    SciTech Connect

    Lo, Fang-Yuh Huang, Cheng-De; Chou, Kai-Chieh; Guo, Jhong-Yu; Liu, Hsiang-Lin; Chia, Chi-Ta; Ney, Verena; Ney, Andreas; Shvarkov, Stepan; Reuter, Dirk; Wieck, Andreas D.; Pezzagna, Sébastien; Chern, Ming-Yau; Massies, Jean

    2014-07-28

    Samarium ions of 200 keV in energy were implanted into highly-resistive molecular-beam-epitaxy grown GaN thin films with a focused-ion-beam implanter at room temperature. The implantation doses range from 1 × 10{sup 14} to 1 × 10{sup 16 }cm{sup −2}. Structural properties studied by x-ray diffraction and Raman-scattering spectroscopy revealed Sm incorporation into GaN matrix without secondary phase. The optical measurements showed that the band gap and optical constants changed very slightly by the implantation. Photoluminescence measurements showed emission spectra similar to p-type GaN for all samples. Magnetic investigations with a superconducting quantum interference device identified magnetic ordering for Sm dose of and above 1 × 10{sup 15 }cm{sup −2} before thermal annealing, while ferromagnetism was only observed after thermal annealing from the sample with highest Sm dose. The long-range magnetic ordering can be attributed to interaction of Sm ions through the implantation-induced Ga vacancy.

  5. Lagrangian based methods for coherent structure detection.

    PubMed

    Allshouse, Michael R; Peacock, Thomas

    2015-09-01

    There has been a proliferation in the development of Lagrangian analytical methods for detecting coherent structures in fluid flow transport, yielding a variety of qualitatively different approaches. We present a review of four approaches and demonstrate the utility of these methods via their application to the same sample analytic model, the canonical double-gyre flow, highlighting the pros and cons of each approach. Two of the methods, the geometric and probabilistic approaches, are well established and require velocity field data over the time interval of interest to identify particularly important material lines and surfaces, and influential regions, respectively. The other two approaches, implementing tools from cluster and braid theory, seek coherent structures based on limited trajectory data, attempting to partition the flow transport into distinct regions. All four of these approaches share the common trait that they are objective methods, meaning that their results do not depend on the frame of reference used. For each method, we also present a number of example applications ranging from blood flow and chemical reactions to ocean and atmospheric flows. PMID:26428570

  6. Lagrangian based methods for coherent structure detection

    SciTech Connect

    Allshouse, Michael R.; Peacock, Thomas

    2015-09-15

    There has been a proliferation in the development of Lagrangian analytical methods for detecting coherent structures in fluid flow transport, yielding a variety of qualitatively different approaches. We present a review of four approaches and demonstrate the utility of these methods via their application to the same sample analytic model, the canonical double-gyre flow, highlighting the pros and cons of each approach. Two of the methods, the geometric and probabilistic approaches, are well established and require velocity field data over the time interval of interest to identify particularly important material lines and surfaces, and influential regions, respectively. The other two approaches, implementing tools from cluster and braid theory, seek coherent structures based on limited trajectory data, attempting to partition the flow transport into distinct regions. All four of these approaches share the common trait that they are objective methods, meaning that their results do not depend on the frame of reference used. For each method, we also present a number of example applications ranging from blood flow and chemical reactions to ocean and atmospheric flows.

  7. Detecting slab structure beneath the Mediterranean

    NASA Astrophysics Data System (ADS)

    Miller, Meghan S.; Sun, Daoyuan; Piana Agostinetti, Nicola

    2013-04-01

    The presence of subducted slabs in the Mediterranean has been well documented with seismic tomography, however, these images, which are produced by smoothed, damped inversions, underestimate the sharpness of the structures. The position and extent of the slabs and the presence possible tears or gaps in the subducted lithosphere are still debated, yet the shape and location these structures are important for kinematic reconstructions and evolution of the entire subduction zone system. Extensive distribution of broadband seismic instrumentation in the Mediterranean (Italian National Seismic Network in Italy and the NSF-PICASSO project in Spain and Morocco) has allowed us to use alternative methodologies to detect the position of the slabs and slab tears beneath the Central and Western Mediterranean. Using S receiver functions we are able to identify S-to-p conversions from the bottom of the subducted slab and a lack of these signals where there are gaps or tears in the slab. We also analyze broadband waveforms for changes in P wave coda from deep (> 300 km depth) local earthquakes. The waveform records for stations in southern Italy and around the Betic-Rif show large amplitude, high frequency (f > 5 Hz) late arrivals with long coda after relatively low-frequency onset. High frequency arrivals are the strongest from events whose raypaths travel within the slab to the stations where they are recorded allowing for mapping of where the subducted material is located within the upper mantle. These two methods, along with inferring the slab position from fast P-wave velocity perturbations in tomography and intermediate depth seismicity, provide additional geophysical evidence to aid in interpretation of the complex, segmented slab structure beneath the Mediterranean.

  8. Clinical assessment of spectral modulation detection for adult cochlear implant recipients: A non-language based measure of performance outcomes

    PubMed Central

    Gifford, René H.; Hedley-Williams, Andrea; Spahr, Anthony J.

    2014-01-01

    Objective Spectral modulation detection (SMD) provides a psychoacoustic estimate of spectral resolution. The SMD threshold for an implanted ear is highly correlated with speech understanding and is thus a non-linguistic, psychoacoustic index of speech understanding. This measure, however, is time and equipment intensive and thus not practical for clinical use. Thus the purpose of the current study was to investigate the efficacy of a quick SMD task with the following three study aims: (1) to investigate the correlation between the long psychoacoustic, and quick SMD tasks, (2) to determine the test/retest variability of the quick SMD task, and (3) to evaluate the relationship between the quick SMD task and speech understanding. Design This study included a within-subjects, repeated-measures design. Study sample Seventy-six adult cochlear implant recipients participated. Results The results were as follows: (1) there was a significant correlation between the long psychoacoustic, and quick SMD tasks, (2) the test-retest variability of the quick SMD task was highly significant and, (3) there was a significant positive correlation between the quick SMD task and monosyllabic word recognition. Conclusions The results of this study represent the direct clinical translation of a research-proven task of SMD into a quick, clinically feasible format. PMID:24456178

  9. Comparison of implantation-driven permeation characteristics of fusion reactor structural materials

    SciTech Connect

    Longhurst, G.R.; Anderl, R.A.; Struttmann, D.A.

    1986-04-04

    Implantation-driven permeation experiments have been conducted on samples of the ferritic steel HT-9, the austenitic Primary Candidate Alloy (PCA) and the vanadium alloy V-15Cr-5Ti using D/sub 3//sup +/ ions under conditions that simulate charge-exchange neutral loading on a fusion reactor first wall. The steels all exhibited an initially intense permeation ''spike'' followed by an exponential decrease to low steady-state values. That spike was not evident in the V-15Cr-5Ti experiments. Steady-state permeation was highest in the vanadium alloy and lowest in the austenitic steel. Though permeation rates in the HT-9 were lower than those in V-15Cr-5Ti, permeation transients were much faster in HT-9 than in other materials tested. Ion-beam sputtering of the surface in the steel experiments resulted in enhanced remission at the front surface, whereas in the vanadium tests, recombination and diffusivity both appeared to diminish as the deuterium concentration rose. This may be due to a phase change in the material. We conclude that for conditions comparable to those of these experiments, tritium retention and loss in first wall structures made of steels will be less than in structures made of V-15Cr-5Ti.

  10. Ultra-structural evaluation of an anodic oxidated titanium dental implant.

    PubMed

    Yamagami, Akiyoshi; Nagaoka, Noriyuki; Yoshihara, Kumiko; Nakamura, Mariko; Shirai, Hajime; Matsumoto, Takuya; Suzuki, Kazuomi; Yoshida, Yasuhiro

    2014-01-01

    Anodic oxidation is used for the surface treatment of commercial implants to improve their functional properties for clinical success. Here we conducted ultrastructural and chemical investigations into the micro- and nanostructure of the anodic oxide film of a titanium implant. The anodic oxidized layer of a Ti6Al4V alloy implant was examined ultrastructurally by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). They were also analyzed using energy dispersive X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). The TEM revealed that the oxide layer of the Ti6Al4V implant prepared through anodic oxidation was separated into two layers. Al and V were not present on the top surface of the anodic oxide. This can be attributed to the biocompatibility of the anodic oxidized Ti6Al4V alloy implant, because the release of harmful metal ions such as Al and V can be suppressed by the biocompatibility. PMID:25483382

  11. Damage Detection in Electrically Conductive Structures

    NASA Astrophysics Data System (ADS)

    Anderson, Todd A.

    2002-12-01

    High-technology systems are in need of structures that perform with increased functionality and a reduction in weight, while simultaneously maintaining a high level of performance and reliability. To accomplish this, structural elements must be designed more efficiently and with increased functionality, thereby creating multifunctional structures (MFS). Through the addition of carbon fibers, nanotubes, or particles, composite structures can be made electrically conductive while simultaneously increasing their strength and stiffness to weight ratios. Using the electrical properties of these structures for the purpose of damage detection and location for health and usage monitoring is of particular interest for aerospace structures. One such method for doing this is Electrical Impedance Tomography (EIT). With EIT, an electric current is applied through a pair of electrodes and the electric potential is recorded at other monitoring electrodes around the area of study. An inverse solution of the governing Maxwell equations is then required to determine the conductivities of discrete areas within the region of interest. However, this method is nearly ill-posed and computationally intensive as it focuses on imaging small changes in conductivity within the region of interest. For locating damage in a medium with an otherwise homogeneous conductivity, an alternative approach is to search for parameters such as the damage location and size. Towards those ends, this study develops an Artificial Neural Network (ANN) to determine the state of an electrically conductive region based on applied reference current and electrical potentials at electrodes around the periphery of the region. A significant benefit of the ANN approach is that once trained, the solution of an inverse problem does not require costly computations of the inverse problem. This method also takes advantage of the pattern recognition abilities of neural networks and is a robust solution method in the presence

  12. Subclinical tonic-clonic epileptic seizure detected by an implantable loop recorder.

    PubMed

    Kohno, Ritsuko; Abe, Haruhiko; Akamatsu, Naoki; Tamura, Masahito; Takeuchi, Masaaki; Otsuji, Yutaka; Benditt, David G

    2013-01-01

    A 73-year old man received an implantable loop recorder (ILR) for the evaluation of transient loss of consciousness (TLOC) spells. His medical history was without any epileptic convulsions or automatism. ILR recording during a spontaneous episode revealed the presence of a regular, narrow QRS complex tachycardia associated with low-amplitude, high-frequency, continuous or discontinuous artifacts, consistent with myopotentials. During the event, the regular, low-amplitude continuous signals gradually became discontinuous, with a prolongation of the inter-signal cycle length, until their disappearance after manual activation of the ILR. The patient was diagnosed as experiencing subclinical tonic-clonic epileptic seizures. Antiepileptic drug treatment was initiated, and the patient has remained free of TLOC symptoms during 13 months follow-up. PMID:24097218

  13. The Effect of Thermal Annealing on Structural-phase Changes in the Ni-Ti Alloy Implanted with Krypton Ions

    NASA Astrophysics Data System (ADS)

    Poltavtseva, V. P.; Kislitsin, S. B.; Ghyngazov, S. A.

    2016-06-01

    The influence of thermal annealing within the temperature range 100-300°C on the structural-phase state of a Ni-Ti alloy with shape memory effect (SME) implanted with 84Kr ions at the energies E = 280 keV and 1.75 MeV/nucl and the fluences within 5·1012-1·1020 ion/m2 is investigated. For the samples modified by 84Kr ions at E = 1.75 MeV/nucl up to the fluences 1·1020 and 5·1012 ion/m2, the formation of a martensitic NiTi phase with the B19 ' structure, responsible for the SME, is revealed at the annealing temperatures 100 and 300°C, respectively, in the near-surface region corresponding to the outrange area. This is accompanied by the formation of nanosized NiTi particles in the R-phase. As the implantation fluence increases, the probability of their formation decreases. It is shown that annealing of the implanted structures can increase the strength of the Ni-Ti alloy. The degree of hardening is determined by the value of annealing temperature, and an increase in strength is primarily due to ordering of the radiation-induced defect structures (phases). A correlation between the onset temperature of a forward martensitic transition and the structural-phase state of the thermally annealed Ni-Ti alloy is established.

  14. Hydrogen ion-implantation induced low resistive layer in KNbO3 bulk single crystal: Evaluation by elastic recoil detection analysis

    NASA Astrophysics Data System (ADS)

    Shinkawa, A.; Shibasaki, Y.; Nishimura, T.; Tanuma, C.; Kuriyama, K.

    2016-03-01

    Origins of low resistivity in H-ion implanted KNbO3 bulk single crystals are studied by elastic recoil detection analysis (ERDA) and Van der Pauw methods. The H-ion implantation (peak ion fluence: 5.0 × 1015 cm-2) into KNbO3 is performed using a 500 keV implanter. The sheet resistance decreases from ∼108 Ω/□ for an un-implanted KNbO3 sample to 2.33 × 105 Ω/□ for as-implanted, 2.29 × 105 Ω/□ for 100 °C annealed, and 4.25 × 105 Ω/□ for 150 °C annealed samples, respectively. The ERDA experiment using the 1.5 MeV-4He+ beam can evaluate hydrogen from the surface to around 60 nm. The hydrogen concentration near the surface estimated using the 1.5 MeV helium beam is 5.1 × 1014 cm-2 for un-implanted KNbO3 sample, 5.6 × 1014 cm-2 for as-implanted, 3.4 × 1014 cm-2 for 150 °C annealed samples, respectively, indicating that a part of hydrogen is diffused out by annealing. The low resistive layer induced in H-ion implanted KNbO3 suggests the existence of a shallow energy level related to the complex defect consisting of hydrogen interstitial and the proton induced defect such as oxygen vacancy.

  15. Hydrogen interstitial in H-ion implanted ZnO bulk single crystals: Evaluation by elastic recoil detection analysis and electron paramagnetic resonance

    NASA Astrophysics Data System (ADS)

    Kaida, T.; Kamioka, K.; Nishimura, T.; Kuriyama, K.; Kushida, K.; Kinomura, A.

    2015-12-01

    The origins of low resistivity in H ion-implanted ZnO bulk single crystals are evaluated by elastic recoil detection analysis (ERDA), electron paramagnetic resonance (EPR), and Van der Pauw methods. The H-ion implantation (peak concentration: 5.0 × 1015 cm-2) into ZnO is performed using a 500 keV implanter. The maximum of the concentration of the implanted H estimated by a TRIM simulation is at 3600 nm in depth. The resistivity decreases from ∼103 Ω cm for un implanted ZnO to 6.5 Ω cm for as-implanted, 2.3 × 10-1 Ω cm for 200 °C annealed, and 3.2 × 10-1 Ω cm for 400 °C annealed samples. The ERDA measurements can evaluate the concentration of hydrogens which move to the vicinity of the surface (surface to 300 nm or 100 nm) because of the diffusion by the annealing at 200 °C and 400 °C. The hydrogen concentration near the surface estimated using the 2.0 MeV helium beam is ∼3.8 × 1013 cm-2 for annealed samples. From EPR measurements, the oxygen vacancy of +charge state (Vo+) is observed in as-implanted samples. The Vo+ related signal (g = 1.96) observed under no illumination disappears after successive illumination with a red LED and appears again with a blue light illumination. The activation energy of as-implanted, 200 °C annealed, and 400 °C annealed samples estimated from the temperature dependence of carrier concentration lies between 29 meV and 23 meV, suggesting the existence of H interstitial as a shallow donor level.

  16. STN area detection using K-NN classifiers for MER recordings in Parkinson patients during neurostimulator implant surgery

    NASA Astrophysics Data System (ADS)

    Schiaffino, L.; Rosado Muñoz, A.; Guerrero Martínez, J.; Francés Villora, J.; Gutiérrez, A.; Martínez Torres, I.; Kohan, y. D. R.

    2016-04-01

    Deep Brain Stimulation (DBS) applies electric pulses into the subthalamic nucleus (STN) improving tremor and other symptoms associated to Parkinson’s disease. Accurate STN detection for proper location and implant of the stimulating electrodes is a complex task and surgeons are not always certain about final location. Signals from the STN acquired during DBS surgery are obtained with microelectrodes, having specific characteristics differing from other brain areas. Using supervised learning, a trained model based on previous microelectrode recordings (MER) can be obtained, being able to successfully classify the STN area for new MER signals. The K Nearest Neighbours (K-NN) algorithm has been successfully applied to STN detection. However, the use of the fuzzy form of the K-NN algorithm (KNN-F) has not been reported. This work compares the STN detection algorithm of K-NN and KNN-F. Real MER recordings from eight patients where previously classified by neurophysiologists, defining 15 features. Sensitivity and specificity for the classifiers are obtained, Wilcoxon signed rank non-parametric test is used as statistical hypothesis validation. We conclude that the performance of KNN-F classifier is higher than K-NN with p<0.01 in STN specificity.

  17. Simulation of fracture of the bone implant with the porous structure

    NASA Astrophysics Data System (ADS)

    Korobenkov, M. V.; Kulkov, S. N.

    2016-08-01

    Different approaches to bone defects reconstruction with the use of ceramic materials have been developed recently. Ceramics are identical with bone matrix, provide biomedical compatibility with bone tissue and possess high strength. But with an overall high strength ceramic implants destruct in dynamic mode. The paper presents a study of the effect of the porosity gradient on the destruction of the bone implants under dynamic loading. It is shown that the fracture behavior of the bone implants is changed with increasing levels of the gradient of porosity.

  18. Magnesium behavior and structural defects in Mg+ ion implanted silicon carbide

    NASA Astrophysics Data System (ADS)

    Jiang, Weilin; Jung, Hee Joon; Kovarik, Libor; Wang, Zhaoying; Roosendaal, Timothy J.; Zhu, Zihua; Edwards, Danny J.; Hu, Shenyang; Henager, Charles H.; Kurtz, Richard J.; Wang, Yongqiang

    2015-03-01

    As a candidate material for fusion reactor applications, silicon carbide (SiC) undergoes transmutation reactions under high-energy neutron irradiation with magnesium as the major metallic transmutant; the others include aluminum, beryllium and phosphorus in addition to helium and hydrogen gaseous species. The impact of these transmutants on SiC structural stability is currently unknown. This study uses ion implantation to introduce Mg into SiC. Multiaxial ion-channeling analysis of the as-produced damage state indicates a lower dechanneling yield observed along the <1 0 0> axis. The microstructure of the annealed sample was examined using high-resolution scanning transmission electron microscopy. The results show a high concentration of likely non-faulted tetrahedral voids and possible stacking fault tetrahedra near the damage peak. In addition to lattice distortion, dislocations and intrinsic and extrinsic stacking faults are also observed. Magnesium in 3C-SiC prefers to substitute for Si and it forms precipitates of cubic Mg2Si and tetragonal MgC2. The diffusion coefficient of Mg in 3C-SiC single crystal at 1573 K has been determined to be 3.8 ± 0.4 × 10-19 m2/s.

  19. Magnesium behavior and structural defects in Mg+ ion implanted silicon carbide

    SciTech Connect

    Jiang, Weilin; Jung, Hee Joon; Kovarik, Libor; Wang, Zhaoying; Roosendaal, Timothy J.; Zhu, Zihua; Edwards, Danny J.; Hu, Shenyang; Henager, Charles H.; Kurtz, Richard J.; Wang, Yongqiang

    2015-03-01

    As a candidate material for fusion reactor applications, silicon carbide (SiC) undergoes transmutation reactions under high-energy neutron irradiation with magnesium as the major metallic transmutant; the others include aluminum, beryllium and phosphorus in addition to helium and hydrogen gaseous species. The impact of these transmutants on SiC structural stability is currently unknown. This study uses ion implantation to introduce Mg into SiC. Multiaxial ion-channeling analysis of the as-produced damage state suggests that there are preferred Si <100> interstitial splits. The microstructure of the annealed sample was examined using high-resolution scanning transmission electron microscopy. The results show a high concentration of likely non-faulted tetrahedral voids and possible stacking fault tetrahedra near the damage peak. In addition to lattice distortion, dislocations and intrinsic and extrinsic stacking faults are also observed. Magnesium in 3C-SiC prefers to substitute for Si and it forms precipitates of cubic Mg2Si and tetragonal MgC2. The diffusion coefficient of Mg in 3C-SiC single crystal at 1573 K has been determined to be 3.8±0.4×10e-19 m2/sec.

  20. Sensitivity of bilateral cochlear implant users to fine-structure and envelope interaural time differencesa

    PubMed Central

    Noel, Victor A.; Eddington, Donald K.

    2013-01-01

    Bilateral cochlear implant users have poor sensitivity to interaural time differences (ITDs) of high-rate pulse trains, which precludes use of these stimuli to convey fine-structure ITD cues. However, previous reports of single-neuron recordings in cats demonstrated good ITD sensitivity to 1000 pulses-per-second (pps) pulses when the pulses were sinusoidally amplitude modulated. The ability of modulation to restore ITD sensitivity to high-rate pulses in humans was tested by measuring ITD thresholds for three conditions: ITD encoded in the modulated carrier pulses alone, in the envelope alone, and in the whole waveform. Five of six subjects were not sensitive to ITD in the 1000-pps carrier, even with modulation. One subject's 1000-pps carrier ITD sensitivity did significantly improve due to modulation. Sensitivity to ITD encoded in the envelope was also measured as a function of modulation frequency, including at frequencies from 4 to 16 Hz where much of the speech envelope's energy and information resides. Sensitivity was best at the modulation frequency of 100 Hz and degraded rapidly outside of a narrow range. These results provide little evidence to support encoding ITD in the carrier of current bilateral processors, and suggest envelope ITD sensitivity is poor for an important segment of the speech modulation spectrum. PMID:23556598

  1. Chemical and structural analysis of the bone-implant interface by TOF-SIMS, SEM, FIB and TEM: Experimental study in animal

    NASA Astrophysics Data System (ADS)

    Palmquist, Anders; Emanuelsson, Lena; Sjövall, Peter

    2012-06-01

    Although bone-anchored implants are widely used in reconstructive medicine, the mechanism of osseointegration is still not fully understood. Novel analytical tools are needed to further understand this process, where both the chemical and structural aspects of the bone-implant interface are important. The aim of this study was to evaluate the advantages of combining time-of-flight secondary ion mass spectroscopy (TOF-SIMS) with optical (LM), scanning (SEM) and transmission electron microscopy (TEM) techniques for studying the bone-implant interface of bone-anchored implants. Laser-modified titanium implants with surrounded bone retrieved after 8 weeks healing in rabbit were dehydrated and resin embedded. Three types of sample preparation were studied to evaluate the information gained by combining TOF-SIMS, SEM, FIB and TEM. The results show that imaging TOF-SIMS can provide detailed chemical information, which in combination with structural information from microscopy methods provide a more complete characterization of anatomical structures at the bone-implant interface. By investigating various sample preparation techniques, it is shown that grinded cross section samples can be used for chemical imaging using TOF-SIMS, if careful consideration of potential preparation artifacts is taken into account. TOF-SIMS analysis of FIB-prepared bone/implant cross section samples show distinct areas corresponding to bone tissue and implant with a sharp interface, although without chemical information about the organic components.

  2. A Brief Survey of β-Detected NMR of Implanted 8Li+ in Organic Polymers

    NASA Astrophysics Data System (ADS)

    McGee, F. H.; McKenzie, I.; Buck, T.; Daley, C. R.; Forrest, J. A.; Harada, M.; Kiefl, R. F.; Levy, C. D. P.; Morris, G. D.; Pearson, M. R.; Sugiyama, J.; Wang, D.; MacFarlane, W. A.

    2014-12-01

    Unlike the positive muon, we expect the chemistry of the implanted 8Li+β-NMR probe in organic polymers to be simply that of the monovalent ion, but almost nothing is known about the NMR of isolated Li+ in this context. Here, we present a brief survey of 8Li+β-NMR in a variety of insulating polymers at high magnetic field, including polyimide, PET, polycarbonate, polystyrene and polyethylene oxide. In all cases, we find a large-amplitude, broad Lorentzian resonance near the Larmor frequency, consistent with the expected diamagnetic charge state. We also find remarkably fast spin-lattice relaxation rates 1/T1. There is very little dependence of either linewidth or 1/T1 on the proton density, the main source of nuclear dipolar magnetic fields, leading us to conclude the main contribution to both broadening and spin relaxation at room temperature is quadrupolar in origin. This behaviour is very different from crystalline insulators such as MgO and Al2O3, and suggests that 8Li+β-NMR will be an important probe of polymer dynamics. Additionally, we note dramatically different behaviour of one sample above its glass transition, motivating the construction of a high temperature spectrometer to enable further exploration at elevated temperature.

  3. Structural phase states in nickel-titanium surface layers doped with silicon by plasma immersion ion implantation

    NASA Astrophysics Data System (ADS)

    Kashin, Oleg A.; Lotkov, Aleksandr I.; Kudryashov, Andrey N.; Krukovsky, Konstantin V.; Ostapenko, Marina G.; Neiman, Alexey A.; Borisov, Dmitry P.

    2015-10-01

    The paper reports on a study of NiTi-based alloys used for manufacturing self-expanding intravascular stents to elucidate how the technological modes of plasma immersion ion implantation with silicon influence the chemical and phase composition of their surface layers. It is shown that two types of surface structure can be obtained depending on the mode of plasma immersion implantation: quasi-amorphous Si coating and Si-doped surface layer. The Si-doped surface layer contains new phases: a phase structured as the main B2 phase of NiTi but with a lower lattice parameter, R phase, and phase of highly dispersed SiO2 precipitates.

  4. Stress influenced trapping processes in Si based multi-quantum well structures and heavy ions implanted Si

    SciTech Connect

    Ciurea, Magdalena Lidia Lazanu, Sorina

    2014-10-06

    Multi-quantum well structures and Si wafers implanted with heavy iodine and bismuth ions are studied in order to evaluate the influence of stress on the parameters of trapping centers. The experimental method of thermostimullatedcurrents without applied bias is used, and the trapping centers are filled by illumination. By modeling the discharge curves, we found in multilayered structures the parameters of both 'normal' traps and 'stress-induced' ones, the last having a Gaussian-shaped temperature dependence of the cross section. The stress field due to the presence of stopped heavy ions implanted into Si was modeled by a permanent electric field. The increase of the strain from the neighborhood of I ions to the neighborhood of Bi ions produces the broadening of some energy levels and also a temperature dependence of the cross sections for all levels.

  5. Structural and optical properties of Mn-doped CdS thin films prepared by ion implantation

    SciTech Connect

    Chandramohan, S.; Tripathi, J. K.; Sarangi, S. N.; Som, T.; Kanjilal, A.; Sathyamoorthy, R.

    2009-06-15

    We report on structural and optical properties of Mn-doped CdS thin films prepared by 190 keV Mn-ion implantation at different temperatures. Mn-ion implantation in the fluence range of 1x10{sup 13}-1x10{sup 16} ions cm{sup -2} does not lead to the formation of any secondary phase. However, it induces structural disorder, causing a decrease in the optical band gap. This is addressed on the basis of band tailing due to creation of localized energy states and Urbach energy calculations. Mn-doped samples exhibit a new band in their photoluminescence spectra at 2.22 eV, which originates from the d-d({sup 4}T{sub 1}->{sup 6}A{sub 1}) transition of tetrahedrally coordinated Mn{sup 2+} ions.

  6. Animal Models for Evaluation of Bone Implants and Devices: Comparative Bone Structure and Common Model Uses.

    PubMed

    Wancket, L M

    2015-09-01

    Bone implants and devices are a rapidly growing field within biomedical research, and implants have the potential to significantly improve human and animal health. Animal models play a key role in initial product development and are important components of nonclinical data included in applications for regulatory approval. Pathologists are increasingly being asked to evaluate these models at the initial developmental and nonclinical biocompatibility testing stages, and it is important to understand the relative merits and deficiencies of various species when evaluating a new material or device. This article summarizes characteristics of the most commonly used species in studies of bone implant materials, including detailed information about the relevance of a particular model to human bone physiology and pathology. Species reviewed include mice, rats, rabbits, guinea pigs, dogs, sheep, goats, and nonhuman primates. Ultimately, a comprehensive understanding of the benefits and limitations of different model species will aid in rigorously evaluating a novel bone implant material or device. PMID:26163303

  7. Structural, mechanical and optical properties of nitrogen-implanted titanium at different pulse frequency

    NASA Astrophysics Data System (ADS)

    Raaif, Mohamed; Mohamed, Sodky H.; Abd El-Rahman, Ahmed M.; Kolitsch, Andreas

    2013-04-01

    Plasma-immersion ion implantation (PIII) is a potent method to obtain hard and wear-resistant surface on Ti by nitrogen implantation. This presentation is one part of a sequence of experiments to optimize the microstructure and physical properties of TiN through adapting the plasma-processing parameters. In this work, nitrogen ions were implanted into samples of pure Ti at different nitrogen pulse frequency without using any external source of heating. The nitrogen-implanted surfaces were characterized by X-ray diffraction (XRD), Auger electron spectroscopy (AES), optical microscope, nano-indentation technique, ball-on-disk type tribometer, surface profilemeter, Tafel polarization technique for corrosion performance and ellipsometry. The outcomes show that, nitrogen PIII is an effectual method for nitriding titanium and nitrogen pulse frequency affected the microstructure and physical properties of the treated Ti. X-ray diffraction depicted the formation of α-Ti (N) and the cubic TiN after implanting titanium by nitrogen and the thickness of the nitrided layer increased as the nitrogen pulse frequency increased. The wear and corrosion resistance of the nitrogen-implanted titanium are improved and the friction coefficient decreased from nearly 0.8 for the un-implanted titanium to 0.3 for the implanted titanium, this ascribed to the formation of the titanium nitrided phases. Ellipsometric measurements were carried out on the PIII titanium samples at different nitrogen pulse frequency. The ellipsometric measurements show that, the thickness of the nitrided layer and surface roughness increased while the refractive index decreased with increasing nitrogen pulse frequency.

  8. Investigating the structure and biocompatibility of niobium and titanium oxides as coatings for orthopedic metallic implants.

    PubMed

    Pradhan, D; Wren, A W; Misture, S T; Mellott, N P

    2016-01-01

    Applying sol gel based coatings to orthopedic metallic implant materials can significantly improve their properties and lifespan in vivo. For this work, niobium (Nb2O5) and titanium (TiO2) oxides were prepared via solution processing in order to determine the effect of atomic arrangement (amorphous/crystalline) on bioactivity. Thermal evaluation on the synthesized materials identified an endotherm for Nb2O5 at 75 °C with 40% weight loss below 400 °C, and minimal weight loss between 400 and 850 °C. Regarding TiO2 an endotherm was present at 92 °C with 25% weight loss below 400 °C, and 4% between 400 and 850 °C. Phase evolution was determined using High Temperature X-ray Diffraction (HT-XRD) where amorphous-Nb2O5 (450 °C), hexagonal-Nb2O5 (525 °C), orthorhombic-Nb2O5 (650 °C), amorphous-TiO2 (275 °C) and tetragonal TiO2 (500 °C) structures were produced. Simulated body fluid (SBF) testing was conducted over 1, 7 and 30 days and resulted in positive chemical and morphological changes for crystalline Nb2O5 (525 °C) and TiO2 (500 °C) after 30 days of incubation. Rod-like CaP deposits were observed on the surfaces using Scanning Electron Microscopy (FE-SEM) and Grazing Incidence-X-ray Diffraction (GI-XRD) shows that the deposits were X-ray amorphous. Cell viability was higher with the TiO2 (122%) samples when compared to the growing cell population while Nb2O5 samples exhibited a range of viability (64-105%), partially dependent on materials atomic structure. PMID:26478387

  9. A Three-Dimensional Finite Element Study on the Biomechanical Simulation of Various Structured Dental Implants and Their Surrounding Bone Tissues.

    PubMed

    Zhang, Gong; Yuan, Hai; Chen, Xianshuai; Wang, Weijun; Chen, Jianyu; Liang, Jimin; Zhang, Peng

    2016-01-01

    Background/Purpose. This three-dimensional finite element study observed the stress distribution characteristics of 12 types of dental implants and their surrounding bone tissues with various structured abutments, implant threads, and healing methods under different amounts of concentrated loading. Materials and Methods. A three-dimensional geometrical model of a dental implant and its surrounding bone tissue was created; the model simulated a screw applied with a preload of 200 N or a torque of 0.2 N·m and a prosthetic crown applied with a vertical or an inclined force of 100 N. The Von Mises stress was evaluated on the 12 types of dental implants and their surrounding bone tissues. Results. Under the same loading force, the stress influence on the implant threads was not significant; however, the stress influence on the cancellous bone was obvious. The stress applied to the abutment, cortical bone, and cancellous bone by the inclined force applied to the crown was larger than the stress applied by the vertical force to the crown, and the abutment stress of the nonsubmerged healing implant system was higher than that of the submerged healing implant system. Conclusion. A dental implant system characterised by a straight abutment, rectangle tooth, and nonsubmerged healing may provide minimum value for the implant-bone interface. PMID:26904121

  10. A Three-Dimensional Finite Element Study on the Biomechanical Simulation of Various Structured Dental Implants and Their Surrounding Bone Tissues

    PubMed Central

    Zhang, Gong; Yuan, Hai; Chen, Xianshuai; Wang, Weijun; Chen, Jianyu; Liang, Jimin; Zhang, Peng

    2016-01-01

    Background/Purpose. This three-dimensional finite element study observed the stress distribution characteristics of 12 types of dental implants and their surrounding bone tissues with various structured abutments, implant threads, and healing methods under different amounts of concentrated loading. Materials and Methods. A three-dimensional geometrical model of a dental implant and its surrounding bone tissue was created; the model simulated a screw applied with a preload of 200 N or a torque of 0.2 N·m and a prosthetic crown applied with a vertical or an inclined force of 100 N. The Von Mises stress was evaluated on the 12 types of dental implants and their surrounding bone tissues. Results. Under the same loading force, the stress influence on the implant threads was not significant; however, the stress influence on the cancellous bone was obvious. The stress applied to the abutment, cortical bone, and cancellous bone by the inclined force applied to the crown was larger than the stress applied by the vertical force to the crown, and the abutment stress of the nonsubmerged healing implant system was higher than that of the submerged healing implant system. Conclusion. A dental implant system characterised by a straight abutment, rectangle tooth, and nonsubmerged healing may provide minimum value for the implant-bone interface. PMID:26904121

  11. A study of silicon-on-insulator structures formed by heavy-dose nitrogen implantation

    SciTech Connect

    Polchlopek, S.W.

    1991-01-01

    Silicon substrates were implanted with heavy doses of high-energy nitrogen. After implantation, the substrates underwent high-temperature annealing. The resulting substrates were studied in an effort to determine the processing parameters necessary to create the optimum-buried silicon nitride insulating layer. Atomic concentration depth profiles were obtained with the use of Auger Electron Spectroscopy. The van der Pauw technique was used to determine carrier Hall mobility, dopant activation, and sheet resistivity in the top layer. Buried-layer leakage was studied using both electron-beam-induced-current (EBIC) analysis and direct front-to-back current-voltage measurements. Implant parameters studied include dose, temperature, and energy. Annealing conditions studied include time and temperature. Samples implanted with lower doses of nitrogen (dose < 1.4 {times} 10{sup 18} cm{sup {minus}2}) possess very leaky buried layers. Higher-dose implants (dose = 1.4 {times} 10{sup 18} cm{sup {minus}2} or greater) produce substrates with good-quality buried dielectrics. It is discovered that very-high-dose nitrogen implantation is necessary to produce good-quality buried insulators.

  12. Percutaneous Implants with Porous Titanium Dermal Barriers: An In Vivo Evaluation of Infection Risk

    PubMed Central

    Isackson, Dorthyann; McGill, Lawrence D.; Bachus, Kent N.

    2010-01-01

    Osseointegrated percutaneous implants are a promising prosthetic alternative for a subset of amputees. However, as with all percutaneous implants, they have an increased risk of infection since they breach the skin barrier. Theoretically, host tissues could attach to the metal implant creating a barrier to infection. When compared with smooth surfaces, it is hypothesized that porous surfaces improve the attachment of the host tissues to the implant, and decrease the infection risk. In this study, 4 titanium implants, manufactured with a percutaneous post and a subcutaneous disk, were placed subcutaneously on the dorsum of eight New Zealand White rabbits. Beginning at four weeks post-op, the implants were inoculated weekly with 108 CFU Staphylococcus aureus until signs of clinical infection presented. While we were unable to detect a difference in the incidence of infection of the porous metal implants, smooth surface (no porous coating) percutaneous and subcutaneous components had a 7-fold increased risk of infection compared to the implants with a porous coating on one or both components. The porous coated implants displayed excellent tissue ingrowth into the porous structures; whereas, the smooth implants were surrounded with a thick, organized fibrotic capsule that was separated from the implant surface. This study suggests that porous coated metal percutaneous implants are at a significantly lower risk of infection when compared to smooth metal implants. The smooth surface percutaneous implants were inadequate in allowing a long-term seal to develop with the soft tissue, thus increasing vulnerability to the migration of infecting microorganisms. PMID:21145778

  13. Benefits of preserving stationary and time-varying formant structure in alternative representations of speech: Implications for cochlear implants

    PubMed Central

    Nittrouer, Susan; Lowenstein, Joanna H.; Wucinich, Taylor; Tarr, Eric

    2014-01-01

    Cochlear implants have improved speech recognition for deaf individuals, but further modifications are required before performance will match that of normal-hearing listeners. In this study, the hypotheses were tested that (1) implant processing would benefit from efforts to preserve the structure of the low-frequency formants and (2) time-varying aspects of that structure would be especially beneficial. Using noise-vocoded and sine-wave stimuli with normal-hearing listeners, two experiments examined placing boundaries between static spectral channels to optimize representation of the first two formants and preserving time-varying formant structure. Another hypothesis tested in this study was that children might benefit more than adults from strategies that preserve formant structure, especially time-varying structure. Sixty listeners provided data to each experiment: 20 adults and 20 children at each of 5 and 7 years old. Materials were consonant-vowel-consonant words, four-word syntactically correct, meaningless sentences, and five-word syntactically correct, meaningful sentences. Results showed that listeners of all ages benefited from having channel boundaries placed to optimize information about the first two formants, and benefited even more from having time-varying structure. Children showed greater gains than adults only for time-varying formant structure. Results suggest that efforts would be well spent trying to design processing strategies that preserve formant structure. PMID:25324085

  14. Benefits of preserving stationary and time-varying formant structure in alternative representations of speech: implications for cochlear implants.

    PubMed

    Nittrouer, Susan; Lowenstein, Joanna H; Wucinich, Taylor; Tarr, Eric

    2014-10-01

    Cochlear implants have improved speech recognition for deaf individuals, but further modifications are required before performance will match that of normal-hearing listeners. In this study, the hypotheses were tested that (1) implant processing would benefit from efforts to preserve the structure of the low-frequency formants and (2) time-varying aspects of that structure would be especially beneficial. Using noise-vocoded and sine-wave stimuli with normal-hearing listeners, two experiments examined placing boundaries between static spectral channels to optimize representation of the first two formants and preserving time-varying formant structure. Another hypothesis tested in this study was that children might benefit more than adults from strategies that preserve formant structure, especially time-varying structure. Sixty listeners provided data to each experiment: 20 adults and 20 children at each of 5 and 7 years old. Materials were consonant-vowel-consonant words, four-word syntactically correct, meaningless sentences, and five-word syntactically correct, meaningful sentences. Results showed that listeners of all ages benefited from having channel boundaries placed to optimize information about the first two formants, and benefited even more from having time-varying structure. Children showed greater gains than adults only for time-varying formant structure. Results suggest that efforts would be well spent trying to design processing strategies that preserve formant structure. PMID:25324085

  15. Sonication of Explanted Cardiac Implants Improves Microbial Detection in Cardiac Device Infections

    PubMed Central

    Oliva, Alessandra; Nguyen, Bich Lien; Mascellino, Maria T.; D'Abramo, Alessandra; Iannetta, Marco; Ciccaglioni, Antonio; Vullo, Vincenzo

    2013-01-01

    The sonication technique has been shown to be a promising tool for microbiological diagnosis of device-related infections. We evaluated the usefulness of the sonication method for pathogen detection in 80 explanted cardiac components collected from 40 patients, and the results were compared with those of conventional cultures. Forty subjects undergoing cardiac device removal were studied: 20 had cardiac device infection, and 20 subjects underwent elective generator replacement or revision in the absence of infection. Sonication of explanted devices was more sensitive than traditional culture for microbial detection (67% and 50%, respectively; P = 0.0005). The bacterial count detected in sonication fluid culture was significantly higher than that detected in traditional culture in both infected (P = 0.019) and uninfected (P = 0.029) devices. In the infected patients, sonication fluid culture yielded a significantly higher rate of pathogen detection in explanted electrodes than traditional culture (65% versus 45%; P = 0.02), while no differences were found in the generators. Ten strains were detected only through sonication fluid culture: 6 Staphylococcus epidermidis strains, 1 Staphylococcus hominis strain, 2 Corynebacterium striatum strains, and 1 Brevundimonas sp. Neither the type nor the duration of antimicrobial therapy before device removal had an effect on the diagnostic performance of sonication fluid culture (P = 0.75 and P = 0.56, respectively). In the patients without infection, sonication fluid culture was positive in 8 cases (40%), whereas conventional culture was positive in only 4 (20%). In summary, the sonication technique improves the microbiological diagnosis of explanted cardiac devices. PMID:23196364

  16. Imaging of common breast implants and implant-related complications: A pictorial essay

    PubMed Central

    Shah, Amisha T; Jankharia, Bijal B

    2016-01-01

    The number of women undergoing breast implant procedures is increasing exponentially. It is, therefore, imperative for a radiologist to be familiar with the normal and abnormal imaging appearances of common breast implants. Diagnostic imaging studies such as mammography, ultrasonography, and magnetic resonance imaging are used to evaluate implant integrity, detect abnormalities of the implant and its surrounding capsule, and detect breast conditions unrelated to implants. Magnetic resonance imaging of silicone breast implants, with its high sensitivity and specificity for detecting implant rupture, is the most reliable modality to asses implant integrity. Whichever imaging modality is used, the overall aim of imaging breast implants is to provide the pertinent information about implant integrity, detect implant failures, and to detect breast conditions unrelated to the implants, such as cancer. PMID:27413269

  17. Effect of retention design of artificial teeth and implant-supported titanium CAD-CAM structures on fracture resistance

    PubMed Central

    Ladetzki, Kristin; Mateos-Palacios, Rocío; Pascual-Moscardó, Agustín

    2016-01-01

    Background For implant-supported hybrid prostheses, high mastication forces and reduced acrylic resin thickness over a metal substructure often cause failures arising from tooth or resin fractures. To assay fracture resistance of artificial teeth and resin in implant-supported hybrid prostheses in relation to the titanium structure and retention design supporting teeth. Material and Methods 40 specimens bearing incisors were divided into four groups according to the titanium structure supporting the teeth and the type of load force applied: Group I (Control; n=10): Application of static loading to ten incisors set over a metal structure with internal retention. Group II (Control; n=10): Application of static loading to ten incisors set over a metal structure with external retention. The remaining study specimens (n=20) were subjected to 120,000 masticatory and thermal cycles in a chewing simulator. Afterwards, static loading was applied until the point of fracture using an Instron machine. Group III (Study; n=10): Application of dynamic and static loading to ten incisors set over a metal structure with internal retention. Group IV (Study; n=10): Application of dynamic and static loading to ten incisors set over a metal structure with external retention. Data obtained for the four groups was analyzed and compared, determining the type of fracture (cohesive or adhesive) using a reflected light microscope. Results Statistical analysis confirmed that there were significant differences in fracture resistance between the four groups. External retention was found to have more fracture resistance than the internal retention. Conclusions Hybrid prostheses with titanium substructures and external retention obtained significantly better results than samples with internal retention. Key words:Chewing simulator, thermocycler, fatigue, implant-supported hybrid prosthesis, acrylic teeth, fracture, metal structure design. PMID:27034748

  18. In Situ Characterization of Stimulating Microelectrode Arrays: Study of an Idealized Structure Based on Argus II Retinal implants

    NASA Astrophysics Data System (ADS)

    Kandagor, Vincent; Cela, Carlos J.; Sanders, Charlene A.; Greenbaum, Elias; Lazzi, Gianluca; Zhou, David D.; Castro, Richard; Gaikwad, Sanjay; Little, Jim

    The development of a retinal prosthesis for artificial sight includes a study of the factors affecting the structural and functional stability of chronically implanted microelectrode arrays. Although neuron depolarization and propagation of electrical signals have been studied for nearly a century, the use of multielectrode stimulation as a proposed therapy to treat blindness is a frontier area of modern ophthalmology research. Mapping and characterizing the topographic information contained in the electric field potentials and understanding how this information is transmitted and interpreted in the visual cortex is still very much a work in progress. In order to characterize the electrical field patterns generated by the device, an in vitro prototype that mimics several of the physical and chemical parameters of the in vivo visual implant device was fabricated. We carried out multiple electrical measurements in a model "eye," beginning with a single electrode, followed by a 9-electrode array structure, both idealized components based on the Argus II retinal implants. Correlating the information contained in the topographic features of the electric fields with psychophysical testing in patients may help reduce the time required for patients to convert the electrical patterns into graphic signals.

  19. Detection of entrapped moisture in honeycomb sandwich structures

    NASA Technical Reports Server (NTRS)

    Hallmark, W. B.

    1967-01-01

    Thermal neutron moisture detection system detects entrapped moisture in intercellular areas of bonded honeycomb sandwich structures. A radium/beryllium fast neutron source bombards a specimen. The emitted thermal neutrons from the target nucleus are detected and counted by a boron trifluoride thermal neutron detector.

  20. Transmission electron microscopy and Rutherford backscattering studies of different damage structures in P/sup +/ implanted Si

    SciTech Connect

    Sadana, D.K.; Stratham, M.; Washburn, J.; Booker, G.R.

    1980-11-01

    Cross-sectional transmission electron microscopy (TEM) and MeV He/sup +/ channelling methods have been used to examine different damage structures present under the color bands visible at the surface of a high-dose-rate P/sup +/ implanted (111) Si implanted to a dose of 7.5 x 10/sup 15/ ions/cm/sup 2/. TEM and channelling results obtained from individual colored regions showed a good qualitative correlation in that discrete damage layers observed in the cross-sectional TEM micrographs appeared as discrete peaks in the channelled spectra. The mean depths of the damage layers obtained from these two methods were in agreement. However, the widths of the deeper lying damage layers calculated from the channelling measurements were always greater than the widths observed by TEM. An empirical method based on subtraction of dechannelling background in the channelling spectra gave damage layer widths that were in close agreement with the TEM results.

  1. Construction of waveguiding structures in potassium lithium tantalate niobate crystals by combined laser ablation and ion implantation

    NASA Astrophysics Data System (ADS)

    Yashar, Ayelet Badichi; Ilan, Harel; Agranat, Aharon J.

    2015-02-01

    A generic methodology for constructing complex integrated electro-optic circuits in waveguided configurations is presented. The method is based on combining two techniques, "laser ablation" and "refractive index engineering by ion implantations." The constructed circuits are side-cladded by air trenches that were produced using laser ablation and bottom-cladded by a layer with a reduced refractive index which is generated through the implantation of He+ ions. This fabrication technique enables the construction of circular structures with complex geometry featuring small radii of curvature, and further can be employed to construct microfluidic channels on the same substrate. The research demonstrates waveguides in both linear and circular configurations that were constructed in a potassium lithium tantalate niobate (KLTN) substrate using the aforementioned method, proving that this substrate is a suitable candidate for use in creating laboratories-on-a-chip with multifunctional capabilities. The proposed techniques used in the research are generic and applicable to a wide range of substrates.

  2. Two-dimensional profiling of large tilt angle, low energy boron implanted structure using secondary-ion mass spectrometry

    SciTech Connect

    Cooke, G.A.; Pearson, P.; Gibbons, R.; Dowsett, M.G.; Hill, C.

    1996-01-01

    Experimentally determined two-dimensional dopant maps of implants into semiconductors are required for the calibration and verification of process simulation tools used in very large scale integrated (VLSI) circuit design. Direct measurement with currently available techniques is not possible owing to the physical size of the areas in question. Using a specially fabricated structure and a modified secondary-ion mass spectroscopy instrument, it has been possible to measure profiles with high spatial resolution and sensitivity. In this article we present the results of an investigation of a complex boron implant into silicon, as used in advanced VLSI {ital P}-type metal{endash}oxide{endash}semiconductor source{endash}drain regions, and compare it with results from process simulators. {copyright} {ital 1996 American Vacuum Society}

  3. Charge accumulation in the buried oxide of SOI structures with the bonded Si/SiO2 interface under γ-irradiation: effect of preliminary ion implantation

    NASA Astrophysics Data System (ADS)

    Naumova, O. V.; Fomin, B. I.; Ilnitsky, M. A.; Popov, V. P.

    2012-06-01

    In this study, we examined the effect of preliminary boron or phosphorous implantation on charge accumulation in the buried oxide of SOI-MOSFETs irradiated with γ-rays in the total dose range (D) of 105-5 × 107 rad. The buried oxide was obtained by high-temperature thermal oxidation of Si, and it was not subjected to any implantation during the fabrication process of SOI structures. It was found that implantation with boron or phosphorous ions, used in fabrication technologies of SOI-MOSFETs, increases the concentration of precursor traps in the buried oxide of SOI structures. Unlike in the case of boron implantation, phosphorous implantation leads to an increased density of states at the Si/buried SiO2 interface during subsequent γ-irradiation. In the γ-irradiated SOI-MOSFETs, the accumulated charge density and the density of surface states in the Si/buried oxide layer systems both vary in proportion to kiln D. The coefficients ki for as-fabricated and ion-implanted Si/buried SiO2 systems were evaluated. From the data obtained, it was concluded that a low density of precursor hole traps was a factor limiting the positive charge accumulation in the buried oxide of as-fabricated (non-implanted) SOI structures with the bonded Si/buried SiO2 interface.

  4. Structured back gates for high-mobility two-dimensional electron systems using oxygen ion implantation

    NASA Astrophysics Data System (ADS)

    Berl, M.; Tiemann, L.; Dietsche, W.; Karl, H.; Wegscheider, W.

    2016-03-01

    We present a reliable method to obtain patterned back gates compatible with high mobility molecular beam epitaxy via local oxygen ion implantation that suppresses the conductivity of an 80 nm thick silicon doped GaAs epilayer. Our technique was optimized to circumvent several constraints of other gating and implantation methods. The ion-implanted surface remains atomically flat which allows unperturbed epitaxial overgrowth. We demonstrate the practical application of this gating technique by using magneto-transport spectroscopy on a two-dimensional electron system (2DES) with a mobility exceeding 20 × 106 cm2/V s. The back gate was spatially separated from the Ohmic contacts of the 2DES, thus minimizing the probability for electrical shorts or leakage and permitting simple contacting schemes.

  5. Cochlear Implants.

    ERIC Educational Resources Information Center

    Clark, Catherine; Scott, Larry

    This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

  6. Structural and optical characterization of GaN nanostructures formed by using N+ implantation into GaAs at various temperature

    NASA Astrophysics Data System (ADS)

    Woo, Hyung-Joo; Kim, Gi-Dong; Choi, Han-Woo; Kim, Joon-Kon

    2012-02-01

    We have investigated the evolution of GaN phase nanocrystallite formation in a GaAs matrix by using nitrogen-ion implantation and subsequent rapid thermal annealing. A semi-insulating GaAs (100) wafer was implanted with 50-keV nitrogen ions at fluences in the range of 0.5 ˜ 4.0 × 1017 cm-2 at temperatures of room temperature, 500 °C and 700 °C, followed by post-implantation annealing at 500 ˜ 900 °C under a pure nitrogen gas flow. In the case of high-temperature implantation, there were no significant changes in the UV-VIS absorption spectra after high-temperature annealing compared with the spectra of the as-implanted sample. On the other hand, microscopic blistering and/or exfoliation is preferred after post-implantation annealing at high temperatures above 600 °C. As a consequence, low-temperature implantation (<200 °C is recommended in order to keep a morphologically-clean sample surfaces especially at an implantation fluence of 2 × 1017 cm-2 or more. Formation of nanometer-sized GaN crystallites was confirmed by using X-ray diffraction, cross-sectional transmission electron microscopy and low-temperature photoluminescence spectroscopy, and the effects of different annealing conditions on the evolution of the structures of the crystallites are described.

  7. The Effect of Study Design Biases on the Diagnostic Accuracy of Magnetic Resonance Imaging to Detect Silicone Breast Implant Ruptures: A Meta-Analysis

    PubMed Central

    Song, Jae W.; Kim, Hyungjin Myra; Bellfi, Lillian T.; Chung, Kevin C.

    2010-01-01

    Background All silicone breast implant recipients are recommended by the US Food and Drug Administration to undergo serial screening to detect implant rupture with magnetic resonance imaging (MRI). We performed a systematic review of the literature to assess the quality of diagnostic accuracy studies utilizing MRI or ultrasound to detect silicone breast implant rupture and conducted a meta-analysis to examine the effect of study design biases on the estimation of MRI diagnostic accuracy measures. Method Studies investigating the diagnostic accuracy of MRI and ultrasound in evaluating ruptured silicone breast implants were identified using MEDLINE, EMBASE, ISI Web of Science, and Cochrane library databases. Two reviewers independently screened potential studies for inclusion and extracted data. Study design biases were assessed using the QUADAS tool and the STARDS checklist. Meta-analyses estimated the influence of biases on diagnostic odds ratios. Results Among 1175 identified articles, 21 met the inclusion criteria. Most studies using MRI (n= 10 of 16) and ultrasound (n=10 of 13) examined symptomatic subjects. Meta-analyses revealed that MRI studies evaluating symptomatic subjects had 14-fold higher diagnostic accuracy estimates compared to studies using an asymptomatic sample (RDOR 13.8; 95% CI 1.83–104.6) and 2-fold higher diagnostic accuracy estimates compared to studies using a screening sample (RDOR 1.89; 95% CI 0.05–75.7). Conclusion Many of the published studies utilizing MRI or ultrasound to detect silicone breast implant rupture are flawed with methodological biases. These methodological shortcomings may result in overestimated MRI diagnostic accuracy measures and should be interpreted with caution when applying the data to a screening population. PMID:21364405

  8. Implantable SERS nanosensors for pre-symptomatic detection of BW agents

    NASA Astrophysics Data System (ADS)

    Li, Honggang; Sun, Jian; Alexander, Troy A.; Cullum, Brian M.

    2005-05-01

    The early detection of biological warfare (BW) agents before any symptoms are present is critical for saving lives and reducing cost of therapy. Protein expression in T-cells represents one of the earliest detectable cellular signaling events to occur in response to the exposure to various toxins or BW agents. In order to fully understand a cellular response to a particular BW agent, it is often necessary to monitor the expression of specific proteins. Therefore, we have developed a novel class of surface enhanced Raman scattering (SERS) immuno-nanosensors for the real-time monitoring of protein expression within individual living cells. In this work, we have developed and optimized novel nanosphere-based silver coated SERS nanosensors for the detection of proteins at cellular levels. SERS nanosensors were optimized in terms of nanosphere size, silver coating methods, number of silver layers, antibody binding and affinity. These nanosensors are capable of being inserted into individual cells and non-invasively positioned to the sub-cellular location of interest using optical tweezers. They were constructed from monodisperse silica nanospheres. These nanospheres were condensed from tetraalkoxysilanes in an alcoholic solution of water and ammonia. Accurate control of the silica nanospheres" diameter was achieved by varying the reaction conditions. Nanosphere-based SERS immuno-nanosensors were then prepared by depositing multiple layers of silver on silica spheres, followed by binding of the antibody of interest to the silver. In binding the antibodies, different cross linker agents were characterized and compared. On one end, each of these cross linker agents contained sulfur or isothiocyanate groups which bound to the silver surface, while the other end contained a carboxylic or primary amine group which reacted readily with the antibodies. In order to improve sensitivity of these nanosensors, optimal silver surface coverage with crosslinkers was determined

  9. Thymoma of the left thymic lobe with a contralateral small pleural implant successfully detected with diffusion-weighted MRI.

    PubMed

    Priola, Adriano Massimiliano; Priola, Sandro Massimo

    2015-01-01

    Thymoma is the most common primary neoplasm of the anterior mediastinum. At diagnosis, up to 40% of patients present with advanced disease. Because advanced thymomas receive neoadjuvant chemotherapy, diagnostic imaging is crucial to plan the correct treatment. For characterizing thymomas, CT is the first choice modality, whereas 18F-FDG/PET is reserved for questionable cases and MRI is not routinely employed. Hereby, we describe a case of thymoma with a single contralateral pleural implant in a 30-year-old woman. The small pleural thickening detected at CT was correctly interpreted as pleural seeding related to thymoma at diffusion-weighted (DW)-MRI after a negative 18F-FDG/PET scan, and was subsequently confirmed at surgery. Precise diagnosis and accurate preoperative staging are crucial in managing thymic epithelial tumours in order to design the appropriate treatment and improve prognosis. Indeed, when stage IVa for pleural seeding is diagnosed preoperatively, a multimodality approach including primary chemotherapy followed by surgery and postoperative radiotherapy/chemotherapy is recommended. This is the first report that used DW-MRI for the characterization of pleural seeding in thymoma and demonstrates that DW-MRI could be useful for the correct pre-operatory staging in thymoma patients, especially in cases with indeterminate pleural thickenings at CT, in order to define the correct management. PMID:25702681

  10. Relationship between the surface chemical composition of implants and contact with the substrate.

    PubMed

    Lima da Costa Valente, Mariana; Shimano, Antonio Carlos; Marcantonio Junior, Elcio; Reis, Andréa Candido Dos

    2015-02-01

    The purpose of the study was to use scanning electron microscopy and energy dispersive x-ray spectrometry to assess possible morphologic and chemical changes after performing double-insertion and pullout tests of implants of different shapes and surface treatments. Four different types of implants were used-cylindrical machined-surface implants, cylindrical double-surface-treated porous implants, cylindrical surface-treated porous implants, and tapered surface-treated porous implants-representing a total of 32 screws. The implants were inserted into synthetic bone femurs, totaling 8 samples, before performing each insertion with standardized torque. After each pullout the implants were analyzed by scanning electron microscopy and energy dispersive x-ray spectrometry using a universal testing machine and magnified 35 times. No structural changes were detected on morphological surface characterization, only substrate accumulation. As for composition, there were concentration differences in the titanium, oxygen, and carbon elements. Implants with surface acid treatment undergo greater superficial changes in chemical composition than machined implants, that is, the greater the contact area of the implant with the substrate, the greater the oxide layer change. In addition, prior manipulation can alter the chemical composition of implants, typically to a greater degree in surface-treated implants. PMID:23339297

  11. On the Structure of Phoneme Categories in Listeners with Cochlear Implants

    ERIC Educational Resources Information Center

    Lane, Harlan; Denny, Margaret; Guenther, Frank H.; Hanson, Helen M.; Marrone, Nicole; Matthies, Melanie L.; Perkell, Joseph S.; Stockmann, Ellen; Tiede, Mark; Vick, Jennell; Zandipour, Majid

    2007-01-01

    Purpose: To describe cochlear implant users' phoneme labeling, discrimination, and prototypes for a vowel and a sibilant contrast, and to assess the effects of 1 year's experience with prosthetic hearing. Method: Based on naturally produced clear examples of "boot," "beet," "said," and "shed" by 1 male and 1 female speaker, continua with 13…

  12. Structural and optical properties of rare-earth doped lithium niobate waveguides formed by MeV helium ion implantation

    SciTech Connect

    Herreros, B.; Lifante, G.; Cusso, F.; Kling, A.; Soares, J.C.; Silva, M.F. da; Townsend, P.D.; Chandler, P.J.

    1996-12-31

    Results of investigations of optical waveguides formed by high energy helium implantation into lithium niobate codoped with 5 mol% MgO and 1 mol% Tm{sup 3+} or 1 mol% Er{sup 3+} are reported. A comparative study of structural and luminescence properties between implanted and untreated samples has been performed by means of Rutherford backscattering (RBS) combined with channeling and photoluminescence methods, respectively in order to investigate residual lattice damage and the incorporation of the optical active rare earths. For the case of Tm a full substitutional incorporation of the optical active rare earths. For the case of Tm a full substitutional incorporation on the lithium site and a high crystal quality in both bulk and implanted waveguide material has been found. For Er doped lithium niobate the channeling results show a fraction of Er randomly incorporated or forming precipitates and a deterioration of the waveguide`s lattice. The optical investigations show in both cases only a slight broadening of the emission lines of the rare earths in the waveguides compared to the bulk material.

  13. Usefulness of implantable loop recorders in office-based practice for evaluation of syncope in patients with and without structural heart disease.

    PubMed

    Mason, Pamela K; Wood, Mark A; Reese, Daniel B; Lobban, John H; Mitchell, Mark A; DiMarco, John P

    2003-11-01

    Early use of an implantable loop recorder for evaluating unexplained syncope in an office-based electrophysiology practice is an effective approach in patients with and without structural heart disease. Documentation of rhythm with an implantable loop recorder at the time of symptoms is possible in approximately 50% and 80% of patients in both groups after 1 and 2 years of follow-up, respectively. PMID:14583373

  14. Production of porous oxide coatings with ultrafine crystalline structure on medical implants fabricated from alloy 12Cr18Ni9Ti

    NASA Astrophysics Data System (ADS)

    Rodionov, Igor V.; Fomina, Marina A.; Fomin, Aleksandr A.; Poshivalova, Elena Yu.; Zakharevich, Andrey M.

    2015-06-01

    Using scanning electron microscopy the crystalline structure of porous oxide coatings produced by air-thermal oxidation of orthopedic implants of alloy 12Cr18Ni9Ti at the temperatures of 350 and 400 °C and duration of 1.5 hours was studied. In vivo tests revealed that the resulting coatings promote successful engraftment of thermally modified implants in the body with highly efficient interaction between morphologically heterogeneous coatings and surrounding bone tissue.

  15. Enhancing community detection by using local structural information

    NASA Astrophysics Data System (ADS)

    Xiang, Ju; Hu, Ke; Zhang, Yan; Bao, Mei-Hua; Tang, Liang; Tang, Yan-Ni; Gao, Yuan-Yuan; Li, Jian-Ming; Chen, Benyan; Hu, Jing-Bo

    2016-03-01

    Many real-world networks, such as gene networks, protein-protein interaction networks and metabolic networks, exhibit community structures, meaning the existence of groups of densely connected vertices in the networks. Many local similarity measures in the networks are closely related to the concept of the community structures, and may have a positive effect on community detection in the networks. Here, various local similarity measures are used to extract local structural information, which is then applied to community detection in the networks by using the edge-reweighting strategy. The effect of the local similarity measures on community detection is carefully investigated and compared in various networks. The experimental results show that the local similarity measures are crucial for the improvement of community detection methods, while the positive effect of the local similarity measures is closely related to the networks under study and applied community detection methods.

  16. Multi-Dimensional Damage Detection for Surfaces and Structures

    NASA Technical Reports Server (NTRS)

    Williams, Martha; Lewis, Mark; Roberson, Luke; Medelius, Pedro; Gibson, Tracy; Parks, Steen; Snyder, Sarah

    2013-01-01

    Current designs for inflatable or semi-rigidized structures for habitats and space applications use a multiple-layer construction, alternating thin layers with thicker, stronger layers, which produces a layered composite structure that is much better at resisting damage. Even though such composite structures or layered systems are robust, they can still be susceptible to penetration damage. The ability to detect damage to surfaces of inflatable or semi-rigid habitat structures is of great interest to NASA. Damage caused by impacts of foreign objects such as micrometeorites can rupture the shell of these structures, causing loss of critical hardware and/or the life of the crew. While not all impacts will have a catastrophic result, it will be very important to identify and locate areas of the exterior shell that have been damaged by impacts so that repairs (or other provisions) can be made to reduce the probability of shell wall rupture. This disclosure describes a system that will provide real-time data regarding the health of the inflatable shell or rigidized structures, and information related to the location and depth of impact damage. The innovation described here is a method of determining the size, location, and direction of damage in a multilayered structure. In the multi-dimensional damage detection system, layers of two-dimensional thin film detection layers are used to form a layered composite, with non-detection layers separating the detection layers. The non-detection layers may be either thicker or thinner than the detection layers. The thin-film damage detection layers are thin films of materials with a conductive grid or striped pattern. The conductive pattern may be applied by several methods, including printing, plating, sputtering, photolithography, and etching, and can include as many detection layers that are necessary for the structure construction or to afford the detection detail level required. The damage is detected using a detector or

  17. Structures in magnetohydrodynamic turbulence: detection and scaling.

    PubMed

    Uritsky, V M; Pouquet, A; Rosenberg, D; Mininni, P D; Donovan, E F

    2010-11-01

    We present a systematic analysis of statistical properties of turbulent current and vorticity structures at a given time using cluster analysis. The data stem from numerical simulations of decaying three-dimensional magnetohydrodynamic turbulence in the absence of an imposed uniform magnetic field; the magnetic Prandtl number is taken equal to unity, and we use a periodic box with grids of up to 1536³ points and with Taylor Reynolds numbers up to 1100. The initial conditions are either an X -point configuration embedded in three dimensions, the so-called Orszag-Tang vortex, or an Arn'old-Beltrami-Childress configuration with a fully helical velocity and magnetic field. In each case two snapshots are analyzed, separated by one turn-over time, starting just after the peak of dissipation. We show that the algorithm is able to select a large number of structures (in excess of 8000) for each snapshot and that the statistical properties of these clusters are remarkably similar for the two snapshots as well as for the two flows under study in terms of scaling laws for the cluster characteristics, with the structures in the vorticity and in the current behaving in the same way. We also study the effect of Reynolds number on cluster statistics, and we finally analyze the properties of these clusters in terms of their velocity-magnetic-field correlation. Self-organized criticality features have been identified in the dissipative range of scales. A different scaling arises in the inertial range, which cannot be identified for the moment with a known self-organized criticality class consistent with magnetohydrodynamics. We suggest that this range can be governed by turbulence dynamics as opposed to criticality and propose an interpretation of intermittency in terms of propagation of local instabilities. PMID:21230595

  18. Structures in magnetohydrodynamic turbulence: Detection and scaling

    NASA Astrophysics Data System (ADS)

    Uritsky, V. M.; Pouquet, A.; Rosenberg, D.; Mininni, P. D.; Donovan, E. F.

    2010-11-01

    We present a systematic analysis of statistical properties of turbulent current and vorticity structures at a given time using cluster analysis. The data stem from numerical simulations of decaying three-dimensional magnetohydrodynamic turbulence in the absence of an imposed uniform magnetic field; the magnetic Prandtl number is taken equal to unity, and we use a periodic box with grids of up to 15363 points and with Taylor Reynolds numbers up to 1100. The initial conditions are either an X -point configuration embedded in three dimensions, the so-called Orszag-Tang vortex, or an Arn’old-Beltrami-Childress configuration with a fully helical velocity and magnetic field. In each case two snapshots are analyzed, separated by one turn-over time, starting just after the peak of dissipation. We show that the algorithm is able to select a large number of structures (in excess of 8000) for each snapshot and that the statistical properties of these clusters are remarkably similar for the two snapshots as well as for the two flows under study in terms of scaling laws for the cluster characteristics, with the structures in the vorticity and in the current behaving in the same way. We also study the effect of Reynolds number on cluster statistics, and we finally analyze the properties of these clusters in terms of their velocity-magnetic-field correlation. Self-organized criticality features have been identified in the dissipative range of scales. A different scaling arises in the inertial range, which cannot be identified for the moment with a known self-organized criticality class consistent with magnetohydrodynamics. We suggest that this range can be governed by turbulence dynamics as opposed to criticality and propose an interpretation of intermittency in terms of propagation of local instabilities.

  19. Optical and structural characterization of zinc implanted silica under various thermal treatments

    SciTech Connect

    Mu, R.; Chen, J.; Gu, Y.

    1996-12-01

    Zn ion implanted silica with controlled thermal annealing was investigated. Low temperature optical measurements indicate presence of Zn cluster in as-implanted silica. Optical spectra of the annealed sample under a reducing environment suggest Zn cluster and Zn metal colloid formation. The absorption peak at 5.3 eV may be due to surface plasma absorption of Zn metal colloids in silica. Oxidized samples (10 and 6x10{sup 16} ions/cm{sup 2}) show an absorption peak at 4.3 and 4.8 eV, respectively, and imply ZnO quantum dot formation. The blueshift in exciton absorption can be attributed to quantum confinement effects.

  20. Detection of cystic structures using pulsed ultrasonically induced resonant cavitation

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph (Inventor); Kovach, John S. (Inventor)

    2002-01-01

    Apparatus and method for early detection of cystic structures indicative of ovarian and breast cancers uses ultrasonic wave energy at a unique resonance frequency for inducing cavitation in cystic fluid characteristic of cystic structures in the ovaries associated with ovarian cancer, and in cystic structures in the breast associated with breast cancer. Induced cavitation bubbles in the cystic fluid implode, creating implosion waves which are detected by ultrasonic receiving transducers attached to the abdomen of the patient. Triangulation of the ultrasonic receiving transducers enables the received signals to be processed and analyzed to identify the location and structure of the cyst.

  1. Using the whole read: structural variant detection using NGS data

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several classes of Structural Variants (SV) remain difficult to detect within sequenced genomes. Deletions and tandem duplications may affect a large proportion of variable genomic sequence space, yet their detection is still difficult to discern from false positive signals. Here, we present a metho...

  2. Effect of Piezoelectric Implant on the Structural Integrity of Composite Laminates Subjected to Tensile Loads

    NASA Astrophysics Data System (ADS)

    Masmoudi, Sahir; El Mahi, Abderrahim; Turki, Saïd

    2016-07-01

    The embedment of sensors within composite structures gives the opportunity to develop smart materials for health and usage monitoring systems. This study investigates the use of acoustic emission monitoring with embedded piezoelectric sensor during mechanical tests in order to identify the effects of introducing the sensor into the composite materials. The composite specimen with and without embedded sensor were subject to tensile static and fatigue loading. The analysis and observation of AE signals show that the integration of a sensor presents advantage of the detection of the acoustic events and also show the presence of three or four types of damage during tests. The incorporation of piezoelectric sensor has a negligible influence on the mechanical properties of materials.

  3. Size-dependent structure of CdSe nanoclusters formed after ion implantation in MgO

    SciTech Connect

    Huis, M.A. van . E-mail: m.a.vanhuis@tnw.tudelft.nl; Veen, A. van; Schut, H.; Eijt, S.W.H.; Kooi, B.J.; Hosson, J.Th.M. de

    2005-03-01

    The band gap as well as the optical and structural properties of semiconductor CdSe nanoclusters change as a function of the nanocluster size. Embedded CdSe nanoclusters in MgO were created by means of sequential Cd and Se ion implantation followed by thermal annealing. Changes during annealing were monitored using optical absorption and positron annihilation spectroscopy. High-resolution TEM on cross-sections after annealing at a temperature of 1300 K showed that clusters with a size below 5 nm have the high-pressure rock-salt structure and are in a cube-on-cube orientation relation with MgO, whereas clusters larger than 5 nm adopt the stable wurtzite crystal structure and were observed in two different orientation relations with MgO.

  4. The efficacy of the Cook-Swartz implantable Doppler in the detection of free-flap compromise: a systematic review protocol

    PubMed Central

    Agha, Riaz A; Gundogan, Buket; Fowler, Alexander J; Bragg, Thomas W H; Orgill, Dennis P

    2014-01-01

    Introduction The Cook-Swartz implantable Doppler monitors venous or arterial blood flow from free flaps and can detect free-flap compromise. Previous studies have shown that the use of this Doppler can improve detection and salvage rates as it provides an earlier warning than the current method of clinical assessment. Such studies assert that the implantable Doppler is of great value in monitoring free flaps in current microsurgical units. This systematic review aims to compare the efficacy of the Cook-Swartz implantable Doppler in monitoring free-flap compromise against conventional clinical free-flap monitoring techniques. Methods and analysis Various electronic databases will be systematically searched for studies that compare the use of Cook-Swartz implantable Doppler with clinical assessment. The selected studies will then have their titles and abstracts screened by two authors. Articles selected after title and abstract screen will have full text downloaded and the complete article will be assessed for suitability. Once the articles have been selected for inclusion, data extraction will take place. For data analysis, the outcomes of the studies will be tabulated, with descriptive statistics performed as appropriate and the detection rate of the Doppler and clinical assessment will be compared and synthesised where possible. Ethics and dissemination The authors hope to disseminate the findings as widely as possible. This systematic review will be published in a peer-reviewed journal and include a number of recommendations as its conclusion based on the evidence contained within. Given the wide range of specialties now utilising flaps, it will be presented at a wide range of national and international conferences. Protocol Registration in PROSPERO CRD42013005818 The literature search and data extraction went on until 28 January 2014. These steps were revised in line with peer review comments. PMID:24622948

  5. Implantable CMOS Biomedical Devices

    PubMed Central

    Ohta, Jun; Tokuda, Takashi; Sasagawa, Kiyotaka; Noda, Toshihiko

    2009-01-01

    The results of recent research on our implantable CMOS biomedical devices are reviewed. Topics include retinal prosthesis devices and deep-brain implantation devices for small animals. Fundamental device structures and characteristics as well as in vivo experiments are presented. PMID:22291554

  6. Capacitance-based damage detection sensing for aerospace structural composites

    NASA Astrophysics Data System (ADS)

    Bahrami, P.; Yamamoto, N.; Chen, Y.; Manohara, H.

    2014-04-01

    Damage detection technology needs improvement for aerospace engineering application because detection within complex composite structures is difficult yet critical to avoid catastrophic failure. Damage detection is challenging in aerospace structures because not all the damage detection technology can cover the various defect types (delamination, fiber fracture, matrix crack etc.), or conditions (visibility, crack length size, etc.). These defect states are expected to become even more complex with future introduction of novel composites including nano-/microparticle reinforcement. Currently, non-destructive evaluation (NDE) methods with X-ray, ultrasound, or eddy current have good resolutions (< 0.1 mm), but their detection capabilities is limited by defect locations and orientations and require massive inspection devices. System health monitoring (SHM) methods are often paired with NDE technologies to signal out sensed damage, but their data collection and analysis currently requires excessive wiring and complex signal analysis. Here, we present a capacitance sensor-based, structural defect detection technology with improved sensing capability. Thin dielectric polymer layer is integrated as part of the structure; the defect in the structure directly alters the sensing layer's capacitance, allowing full-coverage sensing capability independent of defect size, orientation or location. In this work, capacitance-based sensing capability was experimentally demonstrated with a 2D sensing layer consisting of a dielectric layer sandwiched by electrodes. These sensing layers were applied on substrate surfaces. Surface indentation damage (~1mm diameter) and its location were detected through measured capacitance changes: 1 to 250 % depending on the substrates. The damage detection sensors are light weight, and they can be conformably coated and can be part of the composite structure. Therefore it is suitable for aerospace structures such as cryogenic tanks and rocket

  7. Bipart: Learning Block Structure for Activity Detection

    PubMed Central

    Mu, Yang; Lo, Henry Z.; Ding, Wei; Amaral, Kevin; Crouter, Scott E.

    2014-01-01

    Physical activity consists complex behavior, typically structured in bouts which can consist of one continuous movement (e.g. exercise) or many sporadic movements (e.g. household chores). Each bout can be represented as a block of feature vectors corresponding to the same activity type. This paper introduces a general distance metric technique to use this block representation to first predict activity type, and then uses the predicted activity to estimate energy expenditure within a novel framework. This distance metric, dubbed Bipart, learns block-level information from both training and test sets, combining both to form a projection space which materializes block-level constraints. Thus, Bipart provides a space which can improve the bout classification performance of all classifiers. We also propose an energy expenditure estimation framework which leverages activity classification in order to improve estimates. Comprehensive experiments on waist-mounted accelerometer data, comparing Bipart against many similar methods as well as other classifiers, demonstrate the superior activity recognition of Bipart, especially in low-information experimental settings. PMID:25328361

  8. Postnatal width changes in the internal structures of the human mandible: a longitudinal three-dimensional cephalometric study using implants.

    PubMed

    Baumrind, S; Korn, E L

    1992-12-01

    This paper presents case-specific quantitative evidence of the systematic lateral displacement of metallic implants in the mandibles of treated and untreated human subjects between the ages of 8.5 and 15.5 years. This evidence appears to be consistent with the inference of small, but systematic increases in distance between the internal structures of the two sides of the osseous mandible during growth. Such a conclusion, however, is inconsistent with traditional beliefs that the internal structures of the mandibular symphysis fuse at the midline during the first post-natal year and remain dimensionally constant thereafter. We recently published evidence of statistically significant transverse displacement of metallic implants in the mandibular body region for 12 of 28 subjects for whom longitudinal data were available. Of the twelve subjects for whom statistically significant changes were observed, widening occurred in eleven cases and narrowing in one. Matching data are now available on concurrent ramus changes for 22 of the same 28 subjects, including 11 of the 12 for whom statistically significant width changes had previously been noted in the body region. In eight of these 11 subjects, statistically significant widening in the ramus region was also observed. No subject had statistically significant widening in the ramus region without also having statistically significant widening in the body region. No subject had statistically significant trans-ramus narrowing. PMID:1486926

  9. Detection of five potentially periodontal pathogenic bacteria in peri-implant disease: A comparison of PCR and real-time PCR.

    PubMed

    Schmalz, Gerhard; Tsigaras, Sandra; Rinke, Sven; Kottmann, Tanja; Haak, Rainer; Ziebolz, Dirk

    2016-07-01

    The aim of this study was to compare the microbial analysis methods of polymerase chain reaction (PCR) and real-time PCR (RT-PCR) in terms of detection of five selected potentially periodontal pathogenic bacteria in peri-implant disease. Therefore 45 samples of healthy, mucositis and peri-implantitis (n = 15 each) were assessed according to presence of the following bacteria using PCR (DNA-strip technology) and RT-PCR (fluorescent dye SYBR green-system): Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Treponema denticola (Td), Tanerella forsythia (Tf), and Fusobacterium nucleatum (Fn). There were no significant correlations between the bacterial and disease patterns, so the benefit of using microbiological tests for the diagnosis of peri-implant diseases is questionable. Correlations between the methods were highest for Tf (Kendall's Tau: 0.65, Spearman: 0.78), Fn (0.49, 0.61) and Td (0.49, 0.59). For Aa (0.38, 0.42) and Pg (0.04, 0.04), lower correlation values were detected. Accordingly, conventional semi-quantitative PCR seems to be sufficient for analyzing potentially periodontal pathogenic bacterial species. PMID:27142589

  10. Underlying modal data issues for detecting damage in truss structures

    NASA Technical Reports Server (NTRS)

    Kashangaki, Thomas A-L.; Smith, Suzanne Weaver; Lim, Tae W.

    1992-01-01

    Independent of the modal identification techniques employed for damage detection, use of measured modal data limits the expectations for damage location. These limitations are examined using the distribution of modal strain energy and the sensitivity of the frequency and mode shapes to structural stiffness changes. For given measured modal information of specific accuracy, this examination reveals the following: (1) damage detection is feasible for members that contribute significantly to the strain energy of the measured modes, (2) the modes which are most effective in detecting damage to certain critical members can be identified, and (3) a relationship can be drawn between the accuracy of the measured modes and frequencies and damage detection feasibility.

  11. Detection of nanoscale structural changes in bone using random lasers

    PubMed Central

    Song, Qinghai; Xu, Zhengbin; Choi, Seung Ho; Sun, Xuanhao; Xiao, Shumin; Akkus, Ozan; Kim, Young L.

    2010-01-01

    We demonstrate that the unique characteristics of random lasing in bone can be used to assess nanoscale structural alterations as a mechanical or structural biosensor, given that bone is a partially disordered biological nanostructure. In this proof-of-concept study, we conduct photoluminescence experiments on cortical bone specimens that are loaded in tension under mechanical testing. The ultra-high sensitivity, the large detection area, and the simple detection scheme of random lasers allow us to detect prefailure damage in bone at very small strains before any microscale damage occurs. Random laser-based biosensors could potentially open a new possibility for highly sensitive detection of nanoscale structural and mechanical alterations prior to overt microscale changes in hard tissue and biomaterials. PMID:21258558

  12. Detection of karst structures using airborne EM and VLF

    SciTech Connect

    Beard, L.P. Nyquist, J.E.; Carpenter, P.J.

    1994-12-31

    Through the combined use of multi-frequency helicopter electromagnetic and VLF data, it is possible to detect and delineate a wide variety of karst structures and possibly to assess their interconnectedness. Multi-frequency EM Can detect karst features if some element of the structure is conductive. This conductive aspect may derive from thick, moist soils in the depression commonly associated with a doline, from conductive fluids in the cavity, or from conductive sediments in the cavity if these occupy a significant portion of it. Multiple loop configurations may also increase the likelihood of detecting karst features. Preliminary evidence indicates total field VLF measurements may be able to detect interconnected karst pathways, so long as the pathways are water or sediment filled. Neither technique can effectively detect dry, resistive air-filled cavities.

  13. Use of prefabricated titanium abutments and customized anatomic lithium disilicate structures for cement-retained implant restorations in the esthetic zone.

    PubMed

    Lin, Wei-Shao; Harris, Bryan T; Zandinejad, Amirali; Martin, William C; Morton, Dean

    2014-03-01

    This report describes the fabrication of customized abutments consisting of prefabricated 2-piece titanium abutments and customized anatomic lithium disilicate structures for cement-retained implant restorations in the esthetic zone. The heat-pressed lithium disilicate provides esthetic customized anatomic structures and crowns independently of the computer-aided design and computer-aided manufacturing process. PMID:24360007

  14. Vibration-based damage detection algorithm for WTT structures

    NASA Astrophysics Data System (ADS)

    Nguyen, Tuan-Cuong; Kim, Tae-Hwan; Choi, Sang-Hoon; Ryu, Joo-Young; Kim, Jeong-Tae

    2016-04-01

    In this paper, the integrity of a wind turbine tower (WTT) structure is nondestructively estimated using its vibration responses. Firstly, a damage detection algorithm using changes in modal characteristics to predict damage locations and severities in structures is outlined. Secondly, a finite element (FE) model based on a real WTT structure is established by using a commercial software, Midas FEA. Thirdly, forced vibration tests are performed on the FE model of the WTT structure under various damage scenarios. The changes in modal parameters such as natural frequencies and mode shapes are examined for damage monitoring in the structure. Finally, the feasibility of the vibration-based damage detection method is numerically verified by predicting locations and severities of the damage in the FE model of the WTT structure.

  15. The Effect of Automatic Gain Control Structure and Release Time on Cochlear Implant Speech Intelligibility

    PubMed Central

    Khing, Phyu P.; Swanson, Brett A.; Ambikairajah, Eliathamby

    2013-01-01

    Nucleus cochlear implant systems incorporate a fast-acting front-end automatic gain control (AGC), sometimes called a compression limiter. The objective of the present study was to determine the effect of replacing the front-end compression limiter with a newly proposed envelope profile limiter. A secondary objective was to investigate the effect of AGC speed on cochlear implant speech intelligibility. The envelope profile limiter was located after the filter bank and reduced the gain when the largest of the filter bank envelopes exceeded the compression threshold. The compression threshold was set equal to the saturation level of the loudness growth function (i.e. the envelope level that mapped to the maximum comfortable current level), ensuring that no envelope clipping occurred. To preserve the spectral profile, the same gain was applied to all channels. Experiment 1 compared sentence recognition with the front-end limiter and with the envelope profile limiter, each with two release times (75 and 625 ms). Six implant recipients were tested in quiet and in four-talker babble noise, at a high presentation level of 89 dB SPL. Overall, release time had a larger effect than the AGC type. With both AGC types, speech intelligibility was lower for the 75 ms release time than for the 625 ms release time. With the shorter release time, the envelope profile limiter provided higher group mean scores than the front-end limiter in quiet, but there was no significant difference in noise. Experiment 2 measured sentence recognition in noise as a function of presentation level, from 55 to 89 dB SPL. The envelope profile limiter with 625 ms release time yielded better scores than the front-end limiter with 75 ms release time. A take-home study showed no clear pattern of preferences. It is concluded that the envelope profile limiter is a feasible alternative to a front-end compression limiter. PMID:24312408

  16. Metabolic and structural changes in newly synthesized proteoglycans induced by implantation of a polyethylene sheet in the rabbit knee joint.

    PubMed

    Ribault, D; Garcia, F; Riera, H; Mritovic, D R

    1993-07-01

    A sheet of polyethylene was surgically implanted in a rabbit right patello-femoral joint and changes in the structure and chemical composition of newly synthesized articular cartilage proteoglycans (PGs) were studied 1 month after surgery. The articular cartilage from implanted and sham-operated control knee joints was labeled in vitro with 3H-glycine and 35S-SO4 and then extracted with 4 M guanidinium chloride (GuHCl) solution. Labeled extracts were analyzed by dissociative CsCl gradient centrifugation and by Sepharose CL-2B column chromatography. The labeled glycosaminoglycan side chains were analyzed by Sephadex G-200 column chromatography and specific enzymatic digestions. Compared with sham-operation, the trochlear articular cartilage of operated joints incorporated more 35S-SO4 and 3H-glycine into newly synthesized PGs and proteins. It also synthesized a higher proportion of extractable, hydrodynamically large and high density 35S-PG monomers with increased proportion of molecules, able to interact with exogeneous hyaluronan (HA). The fibro-cartilagenous 'osteo-chondrophytic' spurs, compared with trochlear hyaline articular cartilages, incorporated less 35S-SO4 and 3H-glycine and synthesized less extractable high density 35S-PG monomers able to interact with exogenous HA. Their 35S-GAG side chains were more heterogeneous and segregated into three distinct peaks as shown by Sephadex G-200 column chromatography. The results of the present studies demonstrate that, in response to the implant, there was an increase in the biosynthetic capacity of chondrocytes which synthetized larger PG monomers able to interact wih HA. PMID:15449426

  17. Direct synthesis of ultrathin SOI structure by extremely low-energy oxygen implantation

    NASA Astrophysics Data System (ADS)

    Hoshino, Yasushi; Yachida, Gosuke; Inoue, Kodai; Toyohara, Taiga; Nakata, Jyoji

    2016-06-01

    We performed extremely low-energy 16O+ implantation at 10 keV (Rp ˜ 25 nm) followed by annealing aiming at directly synthesizing an ultrathin Si layer separated by a buried SiO2 layer in Si(001) substrates, and then investigated feasible condition of recrystallization and stabilization of the superficial Si and the buried oxide layer by significantly low temperature annealing. The elemental compositions were analyzed by Rutherford backscattering (RBS) and secondary ion mass spectroscopy (SIMS). The crystallinity of the superficial Si layer was quantitatively confirmed by ananlyzing RBS-channeling spectra. Cross-sectional morphologies and atomic configurations were observed by transmission electron microscope (TEM). As a result, we succeeded in directly synthesizing an ultrathin single-crystalline silicon layer with ≤20 nm thick separated by a thin buried stoichiometric SiO2 layer with ≤20 nm thick formed by extremely low-energy 16O+ implantation followed by surprisingly low temperature annealing at 1050∘ C.

  18. Finite element analysis of provisional structures of implant-supported complete prostheses.

    PubMed

    Carneiro, Bruno Albuquerque; de Brito, Rui Barbosa; França, Fabiana Mantovani Gomes

    2014-04-01

    The use of provisional resin implant-supported complete dentures is a fast and safe procedure to restore mastication and esthetics of patients soon after surgery and during the adaptation phase to the new denture. This study assessed stress distribution of provisional implant-supported fixed dentures and the all-on-4 concept using self-curing acrylic resin (Tempron) and bis-acrylic resin (Luxatemp) to simulate functional loads through the three-dimensional finite element method. Solidworks software was used to build three-dimensional models using acrylic resin (Tempron, model A) and bis-acrylic resin (Luxatemp, model B) for denture captions. Two loading patterns were applied on each model: (1) right unilateral axial loading of 150 N on the occlusal surfaces of posterior teeth and (2) oblique loading vector of 150 N at 45°. The results showed that higher stress was found on the bone crest below oblique load application with a maximum value of 187.57 MPa on model A and 167.45 MPa on model B. It was concluded that model B improved stress distribution on the denture compared with model A. PMID:24779949

  19. Properties of Zn implanted GaN

    SciTech Connect

    Strite, S.; Epperlein, P.W.; Dommann, A.; Rockett, A.; Broom, R.F.

    1996-11-01

    The authors report the optical and structural properties of ion implanted GaN:Zn. Post-implant annealing up to 1,100 C was performed under flowing N{sub 2} in both a tube furnace and a rapid thermal annealing (RTA) system, with and without SiN{sub x} encapsulation layers. The implantation damage is quantified by transmission electron microscopy (TEM). Secondary ion mass spectroscopy (SIMS) detects significant rearrangement of implanted Zn only at the highest temperatures and doses investigated. Strain reduction, observed in GaN:Zn annealed at or above 975 C by high-resolution x-ray diffractometry (HRXRD), indicates successful damage removal. The optical activation of annealed GaN:Zn is measured by photoluminescence (PL). The room temperature (RT) Zn acceptor transition at {approximately} 430 nm is consistently observed in annealed GaN:Zn, but at low efficiency. The authors conclude that residual implantation damage and/or N loss during annealing limits the optical quality of implanted GaN:Zn.

  20. Detection of structural damage using novelty detection algorithm under variational environmental and operational conditions

    NASA Astrophysics Data System (ADS)

    El Mountassir, M.; Yaacoubi, S.; Dahmene, F.

    2015-07-01

    Novelty detection is a widely used algorithm in different fields of study due to its capabilities to recognize any kind of abnormalities in a specific process in order to ensure better working in normal conditions. In the context of Structural Health Monitoring (SHM), this method is utilized as damage detection technique because the presence of defects can be considered as abnormal to the structure. Nevertheless, the performance of such a method could be jeopardized if the structure is operating in harsh environmental and operational conditions (EOCs). In this paper, novelty detection statistical technique is used to investigate the detection of damages under various EOCs. Experiments were conducted with different scenarios: damage sizes and shapes. EOCs effects were simulated by adding stochastic noise to the collected experimental data. Different levels of noise were studied to determine the accuracy and the performance of the proposed method.

  1. Effect of thermal processing on the structure and optical properties of crystalline silicon with GaSb nanocrystals formed with the aid of high-doze ion implantation

    NASA Astrophysics Data System (ADS)

    Komarov, F. F.; Ismailova, G. A.; Mil'chanin, O. V.; Parkhomenko, I. N.; Zhusipbekova, F. B.; Yar-Mukhamedova, G. Sh.

    2015-09-01

    Rutherford backscattering and transmission electron microscopy (TEM) are used to study distributions of impurities and structure of the GaSb + Si nanocomposites in several regimes of ion implantation and thermal processing. It is demonstrated that the hot implantation and annealing lead to a significant loss of impurity and the shift of the maximum concentration of impurity atoms toward the surface. The TEM data prove the formation of nanocrystals with sizes ranging from 20 to 100 nm, dislocation defects, and residual mechanical stresses. Raman spectroscopy is used to study the structure and phase composition of experimental silicon samples containing various nanocrystalline impurities.

  2. Multilayer out-of-plane overlap electrostatic energy harvesting structure actuated by blood pressure for powering intra-cardiac implants

    NASA Astrophysics Data System (ADS)

    Deterre, M.; Risquez, S.; Bouthaud, B.; Dal Molin, R.; Woytasik, M.; Lefeuvre, E.

    2013-12-01

    We present an innovative multilayer out-of-plane electrostatic energy harvesting device conceived in view of scavenging energy from regular blood pressure in the heart. This concept involves the use of a deformable packaging for the implant in order to transmit the blood pressure to the electrostatic transducer. As shown in previous work, this is possible by using thin metal micro-bellows structure, providing long term hermeticity and high flexibility. The design of the electrostatic device has overcome several challenges such as the very low frequency of the mechanical excitation (1 to 2 Hz) and the small available room in the medical implant. Analytical and numerical models have been used to maximize the capacitance variation, and hence to optimize the energy conversion. We have theoretically shown that a 25-layer transducer with 6-mm diameter and 1-mm thickness could harvest at least 20 mJ per heart beat in the left ventricle under a maximum voltage of 75 V. These results show that the proposed concept is promising and could power the next generation of leadless pacemakers.

  3. Structural and electrical properties of Ge nanocrystals embedded in SiO{sub 2} by ion implantation and annealing

    SciTech Connect

    Duguay, S.; Grob, J.J.; Slaoui, A.; Le Gall, Y.; Amann-Liess, M.

    2005-05-15

    Silicon dioxide (SiO{sub 2}) on Si layers with embedded germanium nanocrystals (Ge-ncs) were fabricated using Ge{sup +} implantation and subsequent annealing. Transmission electron microscopy and Rutherford backscattering spectrometry have been used to study the Ge redistribution in the SiO{sub 2} films as a function of annealing temperature. A monolayer of Ge-ncs near the Si/SiO{sub 2} interface was formed under specific annealing conditions. This layer, with a nc density and mean size measured to be, respectively, 1.1x10{sup 12}/cm{sup 2} and 5 nm, is located at approximately 4 nm from the Si/SiO{sub 2} interface. Capacitance-voltage measurements were performed on metal-oxide-semiconductor structures containing such implanted SiO{sub 2} layers in order to study their electrical properties. The results indicate a strong memory effect at relatively low programming voltages (<5 V) due to the presence of Ge-ncs near the Si/SiO{sub 2} interface.

  4. Detection of Component Failures for Smart Structure Control Systems

    NASA Astrophysics Data System (ADS)

    Okubo, Hiroshi

    Uncertainties in the dynamics model of a smart structure are often of significance due to model errors caused by parameter identification errors and reduced-order modeling of the system. Design of a model-based Failure Detection and Isolation (FDI) system for smart structures, therefore, needs careful consideration regarding robustness with respect to such model uncertainties. In this paper, we proposes a new method of robust fault detection that is insensitive to the disturbances caused by unknown modeling errors while it is highly sensitive to the component failures. The capability of the robust detection algorithm is examined for the sensor failure of a flexible smart beam control system. It is shown by numerical simulations that the proposed method suppresses the disturbances due to model errors and markedly improves the detection performance.

  5. CONSERTING: integrating copy number analysis with structural variation detection

    PubMed Central

    Chen, Xiang; Gupta, Pankaj; Wang, Jianmin; Nakitandwe, Joy; Roberts, Kathryn; Dalton, James D.; Parker, Matthew; Patel, Samir; Holmfeldt, Linda; Payne, Debbie; Easton, John; Ma, Jing; Rusch, Michael; Wu, Gang; Patel, Aman; J. Baker, Suzanne; Dyer, Michael A.; Shurtleff, Sheila; Espy, Stephen; Pounds, Stanley; Downing, James R.; Ellison, David W.; Mullighan, Charles G.; Zhang, Jinghui

    2015-01-01

    We developed Copy Number Segmentation by Regression Tree in Next Generation Sequencing (CONSERTING), a novel algorithm for detecting somatic copy number alteration (CNA) using whole-genome sequencing (WGS) data. CONSERTING performs iterative analysis of segmentation by read depth change and localized structural variation detection, achieving high accuracy and sensitivity. Analysis of 43 pediatric and adult cancer genomes revealed novel oncogenic CNAs, complex re-arrangements and subclonal CNAs missed by alternative approaches. PMID:25938371

  6. Hidden Corrosion Detection in Aircraft Metallic Structures Using Lamb Waves

    SciTech Connect

    Titry, C.; Lepoutre, F.

    2005-04-09

    The corrosion of aeronautics structures in aluminum is difficult to detect at an early stage. Lamb waves are sometimes very sensitive to this damage and can be considered as good candidates for its detection. Unfortunately, the complex time evolution of Lamb wave signals makes difficult both utilization and interpretation of their interaction with defects. This paper demonstrates that, for many reasons, the analysis based on wavelets transform is of great help for recognition of Lamb modes and allows the cartography of corroded areas.

  7. Electrical properties and electronic structure of Si-implanted hexagonal boron nitride films

    SciTech Connect

    He, B.; Yuen, M. F.; Zhang, W. J.; Qiu, M.

    2014-07-07

    Si ion implantation with a set of ion energies and ion doses was carried out to dope hexagonal boron nitride (hBN) thin films synthesized by radio-frequency magnetron sputtering. Hall effect measurements revealed n-type conduction with a low resistivity of 0.5 Ω cm at room temperature, corresponding to an electron concentration of 2.0 × 10{sup 19} cm{sup −3} and a mobility of 0.6 cm{sup 2}/V s. Temperature-dependent resistivity measurements in a wide temperature range from 50 to 800 K demonstrated two shallow donor levels in the hBN band gap induced by Si doping, which was in consistence with the theoretical calculation by density function theory.

  8. Modification of implant material surface properties by means of oxide nano-structured coatings deposition

    NASA Astrophysics Data System (ADS)

    Safonov, Vladimir; Zykova, Anna; Smolik, Jerzy; Rogowska, Renata; Lukyanchenko, Vladimir; Kolesnikov, Dmitrii

    2014-08-01

    The deposition of functional coatings on the metal surface of artificial joints is an effective way of enhancing joint tribological characteristics. It is well-known that nanostructured oxide coatings have specific properties advantageous for future implant applications. In the present study, we measured the high hardness parameters, the adhesion strength and the low friction coefficient of the oxide magnetron sputtered coatings. The corrosion test results show that the oxide coating deposition had improved the corrosion resistance by a factor of ten for both stainless steel and titanium alloy substrates. Moreover, the hydrophilic nature of coated surfaces in comparison with the metal ones was investigated in the tensiometric tests. The surfaces with nanostructured oxide coatings demonstrated improved biocompatibility for in vitro and in vivo tests, attributed to the high dielectric constants and the high values of the surface free energy parameters.

  9. Structural-mechanical and antibacterial properties of a soft elastic polyurethane surface after plasma immersion N2(+) implantation.

    PubMed

    Morozov, Ilya A; Mamaev, Alexander S; Osorgina, Irina V; Lemkina, Larisa M; Korobov, Vladimir P; Belyaev, Anton Yu; Porozova, Svetlana E; Sherban, Marina G

    2016-05-01

    The surface of elastic polyurethane treated by plasma immersion N2(+) ion implantation at different fluences has been investigated. A folded surface structure is observed in all cases. Analysis has been performed to study the structural (roughness, steepness and fraction of folds, fractal characteristics), mechanical (stiffness, adhesion force between the AFM probe and the material) and wetting properties of surfaces. Under uniaxial stretching the cracks orthogonal to the axis of deformation and longitudinal folds are formed on the examined surfaces. After unloading the initial structure of the surface of deformed materials exposed to low fluences becomes smoother and does not recover, i.e. it has plastic properties. By contrast, the structure of the surfaces of materials subjected to high-fluence treatment recovers without visible changes and the cracks are fully closed. The study of Staphylococcus colonies grown on these materials has demonstrated significant reduction (from 3 to 5 times) in the vitality of bacteria on treated surfaces. This result was repeated on samples after 11months of storage. Such antibacterial properties are primarily related to the structural changes of the surfaces accompanied by the increased hydrophilicity. PMID:26952420

  10. KrF resists for implant layers patterning extreme high-aspect ratio structures with a double focal plane exposure technique

    NASA Astrophysics Data System (ADS)

    Rafaelli, Giorgio; Ferri, Fabio; Volpi, Stefano; Hong, Chisun

    2012-03-01

    The design rules for advanced image sensor applications are requiring continuous CD shrinkage, and increasing aspect ratios which resulting in major challenges associated with using KrF technology. For the implant photo layers in particular, the need to block high-energy boron implants (well above 2 MeV) with extremely localized implant profiles requires an aspect ratio of deep well structures greater than 10:1. Other desirable attributes of a good photoresist for such demanding applications are high transparency, a steep wall profile consistent throughout the entire film, good adhesion with no structure collapse, and a wide process window. In this paper, we will discuss the role of a chemically amplified, ESCAP-type of resist in meeting these design criteria using a double focal plane exposure technique.

  11. Cochlear Implants

    MedlinePlus

    ... electrodes are inserted. The electronic device at the base of the electrode array is then placed under ... FDA approval for implants The Food and Drug Administration (FDA) regulates cochlear implant devices for both adults ...

  12. Goserelin Implant

    MedlinePlus

    Goserelin implant is used in combination with radiation therapy and other medications to treat localized prostate cancer and is ... treatment of abnormal bleeding of the uterus. Goserelin implant is in a class of medications called gonadotropin- ...

  13. Cochlear Implants

    MedlinePlus

    A cochlear implant is a small, complex electronic device that can help to provide a sense of sound. People who are ... of-hearing can get help from them. The implant consists of two parts. One part sits on ...

  14. Carmustine Implant

    MedlinePlus

    Carmustine implant is used along with surgery and sometimes radiation therapy to treat malignant glioma (a certain type of ... Carmustine implant comes as a small wafer that is placed in the brain by a doctor during surgery to ...

  15. Breast Implants

    MedlinePlus

    ... Updated Safety Information (Consumer Article) FDA Provides Updated Safety Data on Silicone Gel-Filled Breast Implants (Press Announcement) [ARCHIVED] Breast Implant Guidance for Industry (2006) Post Approval Studies Webpage Freedom of Information ...

  16. Cochlear implant

    MedlinePlus

    ... antenna. This part of the implant receives the sound, converts the sound into an electrical signal, and sends it to ... implants allow deaf people to receive and process sounds and speech. However, these devices do not restore ...

  17. Effects of structural defects on the activation of sulfur donors in GaN/x/As/1-x/ formed by N implantation

    SciTech Connect

    Jasinski, J.; Yu, K.M.; Walukiewicz, W.; Liliental-Weber, Z.; Washburn, J.

    2001-07-16

    The effects of structural defects on the electrical activity of S doped GaN{sub x}As{sub 1-x} layers formed by S and N coimplantation in GaAs are reported. S and N ions were implanted to the depth of about 0.4 {micro}m. Electrochemical capacitance voltage measurements on samples annealed at 945 C for 10s show that in a thin (<0.1 {micro}m) surface layer the concentration of active shallow donors is almost an order of magnitude larger in S and N co-implanted samples than in samples implanted with S alone. The activation efficiency of S donors also shows a broad minimum at a depth of about 0.2 {micro}m below the surface. The results of these electrical measurements are correlated with the distribution of structural defects revealed by transmission electron microscopy (TEM). The TEM micrographs show that in addition to a band of dislocation loops commonly found in ion implanted GaAs, an additional band of small voids is observed in samples co-implanted with S and N. The location of this band correlates well with the region of reduced electrical activation of S donors, suggesting that formation of the voids through N accumulation results in a lower concentration of active, substitutional N atoms.

  18. Implant-supported overdenture manufactured using CAD/CAM techniques to achieve horizontal path insertion between the primary and secondary structure: A clinical case report

    PubMed Central

    Agustín-Panadero, Rubén; Peñarrocha-Oltra, David; Gomar-Vercher, Sonia; Ferreiroa, Alberto

    2015-01-01

    This report describes the case of an edentulous patient with an atrophic maxilla and severe class III malocclusion. Prosthetic rehabilitation was performed using CAD/CAM techniques for manufacturing an implant-supported overdenture with horizontal insertion. A vestibulo-lingual insertion overdenture is a precision prosthesis with a fixation system affording a good fit between the primary and secondary structure. Both structures exhibit passive horizontal adjustment. This treatment option requires the same number of implants as implant-supported fixed dentures. The horizontal assembly system prevents the prosthesis from loosening or moving in response to axial and non-axial forces. The technique was used to rehabilitate a patient presenting an atrophic upper maxilla, with the insertion of 8 implants. No complications were reported at follow-up 3, 6 and 12 months after fitting of the prosthesis. This system offers solutions to the clinical and laboratory complications associated with hybrid prostheses, concealing emergence of the chimneys and improving implant-prosthesis hygiene. PMID:26140179

  19. Rapid detection and quantification of impact damage in composite structures

    NASA Technical Reports Server (NTRS)

    Smith, Barry T.

    1992-01-01

    It is shown that a multidisciplinary nondestructive evaluation approach for impact damage detection in composite structures can be used to produce a more efficient inspection. The multidisciplinary NDE approach relies on fast large area thermographic inspections along with detailed ultrasonic volumetric imaging. The thermal inspection technique rapidly identifies the impact damage. The ultrasonic volumetric imaging quantifies the impact generated delaminations through the volume of the structure.

  20. A damage detection technique for reinforced concrete structures

    NASA Astrophysics Data System (ADS)

    Wu, Ai-Lun; Yang, Jann N.; Loh, Chin-Hsiung

    2012-04-01

    Civil engineering structures, such as reinforced concrete frames, exhibit nonlinear hysteretic behavior when subject to dynamic loads, such as earthquakes. The ability to detect damages in structures after a major earthquake will ensure their reliability and safety. Innovative analysis techniques for damage detection of structures have been extensively studied recently. However, practical and effective damage identification techniques remain to be developed for nonlinear structures, in particular hysteretic reinforced concrete (RC) structures. In this paper, a smooth hysteretic model with stiffness and strength degradations and with the pinching effect is used to represent the dynamic characteristics of reinforced concrete (RC) frames. A system identification method capable of detecting damages in nonlinear structures, referred to as the adaptive quadratic sum-square error with unknown inputs (AQSSE-UI), is used to detect damages in hysteretic RC frames. The performance of the AQSSE-UI technique is demonstrated by the experimental data. A 1/3 scale 2-story RC frame has been tested experimentally on the shake table at NCREE, Taiwan. This 2-story RC frame was subject to different levels of ground excitations back to back. The RC frame is firstly considered as a linear model with rotational springs and the tracking of the degradation of the stiffness parameters is carried out using the AQSSE-UI technique. Then the same RC frame is considered as a nonlinear structure with plastic hinges following a smooth hysteretic model. Experimental results show that the AQSSE-UI technique is quite effective for tracking of : (i) the stiffness degradation of linear structures, and (ii) the non-linear hysteretic parameters with stiffness and strength degradations.

  1. Rapid detection and quantification of impact damage in composite structures

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Farley, Gary; Smith, Barry T.

    1991-01-01

    NDE results from thermographic and volumetric ultrasonic techniques are presented to illustrate the multidisciplinary NDE approach to impact-damage detection in such composite structures as are increasingly prevalent in helicopters. Attention is given to both flat-panel and 'y-stiffened' panel specimens; these were fabricated either with kevlar or carbon fiber through-the-thickness reinforcements. While thermal inspection identifies impact damage, volumetric imaging quantifies the impact-generated delaminations through the volume of the structure.

  2. Biofilm formation on surface characterized micro-implants for skeletal anchorage in orthodontics.

    PubMed

    Chin, Mervyn Y H; Sandham, Andrew; de Vries, Joop; van der Mei, Henny C; Busscher, Henk J

    2007-04-01

    Micro-implants are increasingly popular in clinical orthodontics to effect skeletal anchorage. However, biofilm formation on their surfaces and subsequent infection of peri-implant tissues can result in either exfoliation or surgical removal of these devices. The present study aimed to assess biofilm formation on five commercially available, surface characterized micro-implant systems in vitro. The elemental surface compositions of as-received and autoclave-sterilized micro-implants were characterized by X-ray photoelectron spectroscopy. High carbon contamination was detected on the oxide surfaces, along with traces of inorganic elements (Ca, Cu, Cr, Pb, Zn, and P) which disappeared after Ar(+) ion sputtering. The mean surface roughnesses (R(a)) were around 182nm for titanium micro-implants, and 69nm for stainless steel micro-implants, as measured by atomic force microscopy. Scanning electron microscopy revealed different surface topographies between manufacturers, varying from typical machined grooves to structural defects like pores and pits. Overnight biofilms were grown on micro-implant surfaces by immersion in pooled human whole saliva. Biofilms on micro-implants treated with chlorhexidine and fluoride mouthrinses contained comparable numbers of viable organisms, but significantly less than did untreated micro-implants. Comparison of different implant systems using multiple linear regression analysis indicated that biofilm formation was governed by roughness of the implant surface and the prevalence of carbon- and oxygen-rich components. PMID:17194475

  3. Structural impact detection with vibro-haptic interfaces

    NASA Astrophysics Data System (ADS)

    Jung, Hwee-Kwon; Park, Gyuhae; Todd, Michael D.

    2016-07-01

    This paper presents a new sensing paradigm for structural impact detection using vibro-haptic interfaces. The goal of this study is to allow humans to ‘feel’ structural responses (impact, shape changes, and damage) and eventually determine health conditions of a structure. The target applications for this study are aerospace structures, in particular, airplane wings. Both hardware and software components are developed to realize the vibro-haptic-based impact detection system. First, L-shape piezoelectric sensor arrays are deployed to measure the acoustic emission data generated by impacts on a wing. Unique haptic signals are then generated by processing the measured acoustic emission data. These haptic signals are wirelessly transmitted to human arms, and with vibro-haptic interface, human pilots could identify impact location, intensity and possibility of subsequent damage initiation. With the haptic interface, the experimental results demonstrate that human could correctly identify such events, while reducing false indications on structural conditions by capitalizing on human’s classification capability. Several important aspects of this study, including development of haptic interfaces, design of optimal human training strategies, and extension of the haptic capability into structural impact detection are summarized in this paper.

  4. Early detection of local buckling in structural members

    NASA Astrophysics Data System (ADS)

    Ali, Bashir; Sundaresan, Mannur J.; Schulz, Mark J.; Hughes, Derke

    2005-05-01

    Most structural health monitoring analyses to date have focused on the determination of damage in the form of crack growth in metallic materials or delamination or other types of damage growth in composite materials. However, in many applications, local instability in the form of buckling can be the precursor to more extensive damage and unstable failure of the structure. If buckling could be detected in the very early stages, there is a possibility of taking preventive measures to stabilize and save the structure. Relatively few investigations have addressed this type of damage initiation in structures. Recently, during the structural health monitoring of a wind turbine blade, local buckling was identified as the cause of premature failure. A stress wave propagation technique was used in this test to detect the precursor to the buckling failure in the form of early changes in the local curvature of the blade. These conditions have also been replicated in the laboratory and results are reported in this paper. A composite column was subjected to axial compression to induce various levels of buckling deformation. Two different techniques were used to detect the precursors to buckling in this column. The first identifier is the change in the vibration shapes and natural frequencies of the column. The second is the change in the characteristics of diagnostic Lamb waves during the buckling deformation. Experiments indicate that very small changes in curvature during the initial stages of buckling are detectable using the structural health monitoring techniques. The experimental vibration characteristics of the column with slight initial curvatures compared qualitatively with finite element results. The finite element analysis is used to identify the frequencies that are most sensitive to buckling deformation, and to select suitable locations for the placement of sensors that can detect even small changes in the local curvature.

  5. Laser-based structural sensing and surface damage detection

    NASA Astrophysics Data System (ADS)

    Guldur, Burcu

    Damage due to age or accumulated damage from hazards on existing structures poses a worldwide problem. In order to evaluate the current status of aging, deteriorating and damaged structures, it is vital to accurately assess the present conditions. It is possible to capture the in situ condition of structures by using laser scanners that create dense three-dimensional point clouds. This research investigates the use of high resolution three-dimensional terrestrial laser scanners with image capturing abilities as tools to capture geometric range data of complex scenes for structural engineering applications. Laser scanning technology is continuously improving, with commonly available scanners now capturing over 1,000,000 texture-mapped points per second with an accuracy of ~2 mm. However, automatically extracting meaningful information from point clouds remains a challenge, and the current state-of-the-art requires significant user interaction. The first objective of this research is to use widely accepted point cloud processing steps such as registration, feature extraction, segmentation, surface fitting and object detection to divide laser scanner data into meaningful object clusters and then apply several damage detection methods to these clusters. This required establishing a process for extracting important information from raw laser-scanned data sets such as the location, orientation and size of objects in a scanned region, and location of damaged regions on a structure. For this purpose, first a methodology for processing range data to identify objects in a scene is presented and then, once the objects from model library are correctly detected and fitted into the captured point cloud, these fitted objects are compared with the as-is point cloud of the investigated object to locate defects on the structure. The algorithms are demonstrated on synthetic scenes and validated on range data collected from test specimens and test-bed bridges. The second objective of

  6. Gain analysis of higher-order-mode amplification in a dielectric-implanted multi-beam traveling wave structure

    SciTech Connect

    Gee, Anthony; Shin, Young-Min; Accelerator Physics Center , Fermi National Accelerator Laboratory , Batavia, Illinois 60510

    2013-07-15

    A multi-beam traveling wave amplifier designed with an overmoded staggered double grating array was examined by small signal analysis combined with simulation. Eigenmode and S-parameter analyses show that the 2 cm long slow wave structure (SWS) has 1–5 dB insertion loss over the passband (TM{sub 31} mode) with ∼28% cold bandwidth. Analytic gain calculation indicates that in the SWS, TM{sub 31}-mode is amplified with 15–20 dB/beam at 64–84 GHz with three elliptical beams of 10 kV and 150 mA/beam, which was compared with particle-in-cell (PIC) simulations. PIC analysis on the analysis of instability with zero-input driving excitations demonstrated that background noises and non-operating lower order modes are noticeably suppressed by implanting equidistant dielectric absorbers; the overmoded structure only allowed the desired 3rd order mode to propagate in the structure. The designed circuit structure can be widely applied to multi-beam devices for high power RF generation.

  7. Gain analysis of higher-order-mode amplification in a dielectric-implanted multi-beam traveling wave structure

    SciTech Connect

    Gee, Anthony; Shin, Young-Min

    2013-01-01

    A multi-beam traveling wave amplifier designed with an overmoded staggered double grating array was examined by small signal analysis combined with simulation. Eigenmode and S-parameter analyses show that the 2cm long slow wave structure (SWS) has 1-5dB insertion loss over the passband (TM31 mode) with ~28% cold bandwidth. Analytic gain calculation indicates that in the SWS, TM31-mode is amplified with 15–20 dB/beam at 64–84GHz with three elliptical beams of 10kV and 150mA/beam, which was compared with particle-in-cell (PIC) simulations. PIC analysis on the analysis of instability with zero-input driving excitations demonstrated that background noises and non-operating lower order modes are noticeably suppressed by implanting equidistant dielectric absorbers; the overmoded structure only allowed the desired 3rd order mode to propagate in the structure. The designed circuit structure can be widely applied to multi-beam devices for high power RF generation.

  8. Detection of structural deterioration and associated airline maintenance problems

    NASA Technical Reports Server (NTRS)

    Henniker, H. D.; Mitchell, R. G.

    1972-01-01

    Airline operations involving the detection of structural deterioration and associated maintenance problems are discussed. The standard approach to the maintenance and inspection of aircraft components and systems is described. The frequency of inspections and the application of preventive maintenance practices are examined. The types of failure which airline transport aircraft encounter and the steps taken to prevent catastrophic failure are reported.

  9. Damage detection and health monitoring of operational structures

    SciTech Connect

    James, G.; Mayes, R.; Carne, T.; Reese, G.

    1994-09-01

    Initial damage detection/health monitoring experiments have been performed on three different operational structures: a fracture critical bridge, a composite wind turbine blade, and an aging aircraft. An induced damage test was performed on the Rio Grande/I40 bridge before its demolition. The composite wind turbine test was fatgued to failure with periodic modal testing performed throughout the testing. The front fuselage of a DC-9 aircraft was used as the testbed for an induced damage test. These tests have yielded important insights into techniques for experimental damage detection on real structures. Additionally, the data are currently being used with current damage detection algorithms to further develop the numerical technology. State of the art testing technologies such as, high density modal testing, scanning laser vibrometry and natural excitation testing have also been utilized for these tests.

  10. Detecting Community Structure by Using a Constrained Label Propagation Algorithm.

    PubMed

    Chin, Jia Hou; Ratnavelu, Kuru

    2016-01-01

    Community structure is considered one of the most interesting features in complex networks. Many real-world complex systems exhibit community structure, where individuals with similar properties form a community. The identification of communities in a network is important for understanding the structure of said network, in a specific perspective. Thus, community detection in complex networks gained immense interest over the last decade. A lot of community detection methods were proposed, and one of them is the label propagation algorithm (LPA). The simplicity and time efficiency of the LPA make it a popular community detection method. However, the LPA suffers from instability detection due to randomness that is induced in the algorithm. The focus of this paper is to improve the stability and accuracy of the LPA, while retaining its simplicity. Our proposed algorithm will first detect the main communities in a network by using the number of mutual neighbouring nodes. Subsequently, nodes are added into communities by using a constrained LPA. Those constraints are then gradually relaxed until all nodes are assigned into groups. In order to refine the quality of the detected communities, nodes in communities can be switched to another community or removed from their current communities at various stages of the algorithm. We evaluated our algorithm on three types of benchmark networks, namely the Lancichinetti-Fortunato-Radicchi (LFR), Relaxed Caveman (RC) and Girvan-Newman (GN) benchmarks. We also apply the present algorithm to some real-world networks of various sizes. The current results show some promising potential, of the proposed algorithm, in terms of detecting communities accurately. Furthermore, our constrained LPA has a robustness and stability that are significantly better than the simple LPA as it is able to yield deterministic results. PMID:27176470

  11. Detecting Community Structure by Using a Constrained Label Propagation Algorithm

    PubMed Central

    Ratnavelu, Kuru

    2016-01-01

    Community structure is considered one of the most interesting features in complex networks. Many real-world complex systems exhibit community structure, where individuals with similar properties form a community. The identification of communities in a network is important for understanding the structure of said network, in a specific perspective. Thus, community detection in complex networks gained immense interest over the last decade. A lot of community detection methods were proposed, and one of them is the label propagation algorithm (LPA). The simplicity and time efficiency of the LPA make it a popular community detection method. However, the LPA suffers from instability detection due to randomness that is induced in the algorithm. The focus of this paper is to improve the stability and accuracy of the LPA, while retaining its simplicity. Our proposed algorithm will first detect the main communities in a network by using the number of mutual neighbouring nodes. Subsequently, nodes are added into communities by using a constrained LPA. Those constraints are then gradually relaxed until all nodes are assigned into groups. In order to refine the quality of the detected communities, nodes in communities can be switched to another community or removed from their current communities at various stages of the algorithm. We evaluated our algorithm on three types of benchmark networks, namely the Lancichinetti-Fortunato-Radicchi (LFR), Relaxed Caveman (RC) and Girvan-Newman (GN) benchmarks. We also apply the present algorithm to some real-world networks of various sizes. The current results show some promising potential, of the proposed algorithm, in terms of detecting communities accurately. Furthermore, our constrained LPA has a robustness and stability that are significantly better than the simple LPA as it is able to yield deterministic results. PMID:27176470

  12. Exploring representations of protein structure for automated remote homology detection and mapping of protein structure space

    PubMed Central

    2014-01-01

    Background Due to rapid sequencing of genomes, there are now millions of deposited protein sequences with no known function. Fast sequence-based comparisons allow detecting close homologs for a protein of interest to transfer functional information from the homologs to the given protein. Sequence-based comparison cannot detect remote homologs, in which evolution has adjusted the sequence while largely preserving structure. Structure-based comparisons can detect remote homologs but most methods for doing so are too expensive to apply at a large scale over structural databases of proteins. Recently, fragment-based structural representations have been proposed that allow fast detection of remote homologs with reasonable accuracy. These representations have also been used to obtain linearly-reducible maps of protein structure space. It has been shown, as additionally supported from analysis in this paper that such maps preserve functional co-localization of the protein structure space. Methods Inspired by a recent application of the Latent Dirichlet Allocation (LDA) model for conducting structural comparisons of proteins, we propose higher-order LDA-obtained topic-based representations of protein structures to provide an alternative route for remote homology detection and organization of the protein structure space in few dimensions. Various techniques based on natural language processing are proposed and employed to aid the analysis of topics in the protein structure domain. Results We show that a topic-based representation is just as effective as a fragment-based one at automated detection of remote homologs and organization of protein structure space. We conduct a detailed analysis of the information content in the topic-based representation, showing that topics have semantic meaning. The fragment-based and topic-based representations are also shown to allow prediction of superfamily membership. Conclusions This work opens exciting venues in designing novel

  13. Method for Real-Time Model Based Structural Anomaly Detection

    NASA Technical Reports Server (NTRS)

    Smith, Timothy A. (Inventor); Urnes, James M., Sr. (Inventor); Reichenbach, Eric Y. (Inventor)

    2015-01-01

    A system and methods for real-time model based vehicle structural anomaly detection are disclosed. A real-time measurement corresponding to a location on a vehicle structure during an operation of the vehicle is received, and the real-time measurement is compared to expected operation data for the location to provide a modeling error signal. A statistical significance of the modeling error signal to provide an error significance is calculated, and a persistence of the error significance is determined. A structural anomaly is indicated, if the persistence exceeds a persistence threshold value.

  14. Nonlinear damage detection in composite structures using bispectral analysis

    NASA Astrophysics Data System (ADS)

    Ciampa, Francesco; Pickering, Simon; Scarselli, Gennaro; Meo, Michele

    2014-03-01

    Literature offers a quantitative number of diagnostic methods that can continuously provide detailed information of the material defects and damages in aerospace and civil engineering applications. Indeed, low velocity impact damages can considerably degrade the integrity of structural components and, if not detected, they can result in catastrophic failure conditions. This paper presents a nonlinear Structural Health Monitoring (SHM) method, based on ultrasonic guided waves (GW), for the detection of the nonlinear signature in a damaged composite structure. The proposed technique, based on a bispectral analysis of ultrasonic input waveforms, allows for the evaluation of the nonlinear response due to the presence of cracks and delaminations. Indeed, such a methodology was used to characterize the nonlinear behaviour of the structure, by exploiting the frequency mixing of the original waveform acquired from a sparse array of sensors. The robustness of bispectral analysis was experimentally demonstrated on a damaged carbon fibre reinforce plastic (CFRP) composite panel, and the nonlinear source was retrieved with a high level of accuracy. Unlike other linear and nonlinear ultrasonic methods for damage detection, this methodology does not require any baseline with the undamaged structure for the evaluation of the nonlinear source, nor a priori knowledge of the mechanical properties of the specimen. Moreover, bispectral analysis can be considered as a nonlinear elastic wave spectroscopy (NEWS) technique for materials showing either classical or non-classical nonlinear behaviour.

  15. Structure and composition of silicon carbide films synthesized by ion implantation

    NASA Astrophysics Data System (ADS)

    Nussupov, K. Kh.; Beisenkhanov, N. B.; Zharikov, S. K.; Beisembetov, I. K.; Kenzhaliev, B. K.; Akhmetov, T. K.; Seitov, B. Zh.

    2014-11-01

    The mathematical decomposition of the IR absorption spectrum obtained from a Si layer after the C+ ion implantation with an energy of 10 or 40 keV or from a homogeneous SiC0.7 film has demonstrated that fractions of weak elongated Si-C bonds in the amorphous phase, strong shortened Si-C bonds on the surface of small nanocrystals, and tetrahedral Si-C bonds in the crystalline phase (degree of crystallinity) after high-temperature annealing (1250-1400°C) of the layers are equal to 29/29/42, 22/7/71, and 21/31/48%, respectively. A system of SiC2.0, SiO2, SiC0.8, and SiC0.6 layers in the film on the Si substrate has been identified using X-ray reflectometry and the simulation with the Release software. The reflectometry data on fluctuations of the intensity of X-ray reflections in the region of the main maximum have been interpreted in terms of variations in the density over the depth of the layer with a Gaussian distribution of carbon atoms from 2.55 and 2.90 g/cm3 for the SiC0.25 and SiC0.65 layers, respectively, to 3.29 g/cm3 for the SiC1.36 layer.

  16. Human population structure detection via multilocus genotype clustering

    PubMed Central

    Gao, Xiaoyi; Starmer, Joshua

    2007-01-01

    Background We describe a hierarchical clustering algorithm for using Single Nucleotide Polymorphism (SNP) genetic data to assign individuals to populations. The method does not assume Hardy-Weinberg equilibrium and linkage equilibrium among loci in sample population individuals. Results We show that the algorithm can assign sample individuals highly accurately to their corresponding ethnic groups in our tests using HapMap SNP data and it is also robust to admixed populations when tested with Perlegen SNP data. Moreover, it can detect fine-scale population structure as subtle as that between Chinese and Japanese by using genome-wide high-diversity SNP loci. Conclusion The algorithm provides an alternative approach to the popular STRUCTURE program, especially for fine-scale population structure detection in genome-wide association studies. This is the first successful separation of Chinese and Japanese samples using random SNP loci with high statistical support. PMID:17592628

  17. Structural and compositional characterization of X-cut LiNbO 3 crystals implanted with high energy oxygen and carbon ions

    NASA Astrophysics Data System (ADS)

    Bentini, G. G.; Bianconi, M.; Cerutti, A.; Chiarini, M.; Pennestrì, G.; Sada, C.; Argiolas, N.; Bazzan, M.; Mazzoldi, P.; Guzzi, R.

    2005-10-01

    High energy implantation of medium-light elements such as oxygen and carbon was performed in X-cut LiNbO3 single crystals in order to prepare high quality optical waveguides. The compositional and damage profiles, obtained by exploiting the secondary ion mass spectrometry and Rutherford back-scattering techniques respectively, were correlated to the structural properties measured by the high resolution X-ray diffraction. This study evidences the development of tensile strain induced by the ion implantation that can contribute to the decrease of the ordinary refractive index variation through the photo-elastic effect.

  18. Structural valve deterioration of a mitral Carpentier-Edwards pericardial bioprosthesis in an 87-year-old woman 16 years after its implantation.

    PubMed

    Ito, Hiroshi; Sakata, Kensuke; Haruki, Takashi; Kobayashi, Yurio

    2011-01-01

    The second-generation pericardial valve, the Carpentier-Edwards perimount bioprosthetic (CEP) valve, shows dramatically improved durability as compared to the first-generation pericardial valve, and excellent performance has been obtained, in both the aortic and mitral positions. Especially in elderly patients with an implanted CEP valve, reoperation due to structural valve deterioration (SVD) is rarely required. Here, we report the case of an 87-year-old woman with an explanted CEP valve in the mitral position due to SVD, 16 years after its implantation. PMID:21729285

  19. Ti-6Al-4V triply periodic minimal surface structures for bone implants fabricated via selective laser melting.

    PubMed

    Yan, Chunze; Hao, Liang; Hussein, Ahmed; Young, Philippe

    2015-11-01

    Triply periodic minimal surface (TPMS) structures have already been shown to be a versatile source of biomorphic scaffold designs. Therefore, in this work, Ti-6Al-4V Gyroid and Diamond TPMS lattices having an interconnected high porosity of 80-95% and pore sizes in the range of 560-1600 μm and 480-1450 μm respectively were manufactured by selective laser melting (SLM) for bone implants. The manufacturability, microstructure and mechanical properties of the Ti-6Al-4V TPMS lattices were evaluated. Comparison between 3D micro-CT reconstructed models and original CAD models of the Ti-6Al-4V TPMS lattices shows excellent reproduction of the designs. The as-built Ti-6Al-4V struts exhibit the microstructure of columnar grains filled with very fine and orthogonally oriented α' martensitic laths with the width of 100-300 nm and have the microhardness of 4.01 ± 0.34 GPa. After heat treatment at 680°C for 4h, the α' martensite was converted to a mixture of α and β, in which the α phase being the dominant fraction is present as fine laths with the width of 500-800 nm and separated by a small amount of narrow, interphase regions of dark β phase. Also, the microhardness is decreased to 3.71 ± 0.35 GPa due to the coarsening of the microstructure. The 80-95% porosity TPMS lattices exhibit a comparable porosity with trabecular bone, and the modulus is in the range of 0.12-1.25 GPa and thus can be adjusted to the modulus of trabecular bone. At the same range of porosity of 5-10%, the moduli of cortical bone and of the Ti-6Al-4V TPMS lattices are in a similar range. Therefore, the modulus and porosity of Ti-6Al-4V TPMS lattices can be tailored to the levels of human bones and thus reduce or avoid "stress shielding" and increase longevity of implants. Due to the biomorphic designs, and high interconnected porosity and stiffness comparable to human bones, SLM-made Ti-6Al-4V TPMS lattices can be a promising material for load bearing bone implants. PMID:26210549

  20. Detection of coherent structures in photospheric turbulent flows

    SciTech Connect

    Chian, Abraham C.-L.; Rempel, Erico L.; Aulanier, Guillaume; Schmieder, Brigitte; Shadden, Shawn C.; Welsch, Brian T.; Yeates, Anthony R. E-mail: rempel@ita.br

    2014-05-01

    We study coherent structures in solar photospheric flows in a plage in the vicinity of the active region AR 10930 using the horizontal velocity data derived from Hinode/Solar Optical Telescope magnetograms. Eulerian and Lagrangian coherent structures (LCSs) are detected by computing the Q-criterion and the finite-time Lyapunov exponents of the velocity field, respectively. Our analysis indicates that, on average, the deformation Eulerian coherent structures dominate over the vortical Eulerian coherent structures in the plage region. We demonstrate the correspondence of the network of high magnetic flux concentration to the attracting Lagrangian coherent structures (aLCSs) in the photospheric velocity based on both observations and numerical simulations. In addition, the computation of aLCS provides a measure of the local rate of contraction/expansion of the flow.

  1. High holding voltage segmentation stacking silicon-controlled-rectifier structure with field implant as body ties blocking layer

    NASA Astrophysics Data System (ADS)

    Yen, Shiang-Shiou; Cheng, Chun-Hu; Lan, Yu-Pin; Chiu, Yu-Chien; Fan, Chia-Chi; Hsu, Hsiao-Hsuan; Chang, Shao-Chin; Jiang, Zhe-Wei; Hung, Li-Yue; Tsai, Chi-Chung; Chang, Chun-Yen

    2016-04-01

    High electrostatic discharge (ESD) protection robustness and good transient-induced latchup immunity are two important issues for high voltage integrate circuit application. In this study, we report a high-voltage-n-type-field (HVNF) implantation to act as the body ties blocking layer in segmented topology silicon-controlled-rectifier (SCR) structure in 0.11 µm 32 V high voltage process. This body ties blocking layer eliminate the elevated triggered voltage in segmented technique. Using a large resistance as shunt resistor in resistor assisted triggered SCRs stacking structure, the double snapback phenomenon is eliminate. The series SCR could be decoupled a sufficient voltage drop to turned-on when a very low current flow through the shunt resistor. The holding voltage and the failure current of 22 V and 3.4 A are achieved in the best condition of segmented topology SCR stacking structure, respectively. It improves the latchup immunity at high voltage ICs application. On the other hand, the triggered voltage almost keep the same value which is identical to SCR single cell without using segmented topology.

  2. Effect of H + ion implantation on structural, morphological, optical and dielectric properties of L-arginine monohydrochloride monohydrate single crystals

    NASA Astrophysics Data System (ADS)

    Sangeetha, K.; Babu, R. Ramesh; Kumar, P.; Bhagvannarayana, G.; Ramamurthi, K.

    2011-06-01

    L-arginine monohydrochloride monohydrate (LAHCl) single crystals have been implanted with 100 keV H + ions at different ion fluence ranging from 10 12 to 10 15 ions/cm 2. Implanted LAHCl single crystals have been investigated for property changes. Crystal surface and crystalline perfection of the pristine and implanted crystals were analyzed by atomic force microscope and high-resolution X-ray diffraction studies, respectively. Optical absorption bands induced by colour centers, refractive index and birefringence, mechanical stability and dielectric constant of implanted crystals were studied at different ion fluence and compared with that of pristine LAHCl single crystal.

  3. Biomechanical, histological, and ultrastructural analyses of laser micro- and nano-structured titanium alloy implants: a study in rabbit.

    PubMed

    Palmquist, Anders; Lindberg, Fredrik; Emanuelsson, Lena; Brånemark, Rickard; Engqvist, Håkan; Thomsen, Peter

    2010-03-15

    The aim of this study was to evaluate the biomechanical properties and ultrastructure of the bone response of partly laser-modified Ti6Al4V implants compared with turned, machined implants after 8 weeks in rabbit. The surface analyses performed with interference microscopy and electron microscopy showed increased surface topography with micro- and nano-sized surface features as well as increased oxide thickness of the modified surface. The biomechanical testing demonstrated a 270% increase in torque value for the surface modified implants compared with the control implants. Histological evaluation of ground sections of specimens subjected to biomechanical testing revealed ongoing bone formation and remodeling. A histological feature exclusively observed at the laser-modified surface was the presence of fracture in the mineralized bone rather than at the interface between the bone and implant. Transmission electron microscopy (TEM) was performed on Focused Ion Beam (FIB) prepared samples of the intact bone-implant interface, demonstrating a direct contact between nanocrystalline hydroxyapatite and the oxide of the laser-modified implant surface. In conclusion, laser-modified titanium alloy implants have significantly stronger bone anchorage compared with machined implants and show no adverse tissue reactions. PMID:19425049

  4. Compressive behaviour of gyroid lattice structures for human cancellous bone implant applications.

    PubMed

    Yánez, A; Herrera, A; Martel, O; Monopoli, D; Afonso, H

    2016-11-01

    Electron beam melting (EBM) was used to fabricate porous titanium alloy structures. The elastic modulus of these porous structures was similar to the elastic modulus of the cancellous human bone. Two types of cellular lattice structures were manufactured and tested: gyroids and diamonds. The design of the gyroid structures was determined by the main angle of the struts with respect to the axial direction. Thus, structures with angles of between 19 and 68.5° were manufactured. The aim of the design was to reduce the amount of material needed to fabricate a structure with the desired angles to increase the range of stiffness of the scaffolds. Compression tests were conducted to obtain the elastic modulus and the strength. Both parameters increased as the angle decreased. Finally, the specific strength of the gyroid structures was compared with that of the diamond structures and other types of structures. It is shown that, for angles lower than 35°, the gyroid structures had a high strength to weight ratios. PMID:27524040

  5. Pedestrian Detection with Spatially Pooled Features and Structured Ensemble Learning.

    PubMed

    Paisitkriangkrai, Sakrapee; Shen, Chunhua; Hengel, Anton van den

    2016-06-01

    Many typical applications of object detection operate within a prescribed false-positive range. In this situation the performance of a detector should be assessed on the basis of the area under the ROC curve over that range, rather than over the full curve, as the performance outside the prescribed range is irrelevant. This measure is labelled as the partial area under the ROC curve (pAUC). We propose a novel ensemble learning method which achieves a maximal detection rate at a user-defined range of false positive rates by directly optimizing the partial AUC using structured learning. In addition, in order to achieve high object detection performance, we propose a new approach to extracting low-level visual features based on spatial pooling. Incorporating spatial pooling improves the translational invariance and thus the robustness of the detection process. Experimental results on both synthetic and real-world data sets demonstrate the effectiveness of our approach, and we show that it is possible to train state-of-the-art pedestrian detectors using the proposed structured ensemble learning method with spatially pooled features. The result is the current best reported performance on the Caltech-USA pedestrian detection dataset. PMID:26336118

  6. Language Structures Used by Kindergartners with Cochlear Implants: Relationship to Phonological Awareness, Lexical Knowledge and Hearing Loss

    PubMed Central

    Nittrouer, Susan; Sansom, Emily; Low, Keri; Rice, Caitlin; Caldwell-Tarr, Amanda

    2014-01-01

    Objective Listeners use their knowledge of how language is structured to aid speech recognition in everyday communication. When it comes to children with congenital hearing loss severe enough to warrant cochlear implants (CIs), the question arises of whether these children can acquire the language knowledge needed to aid speech recognition, in spite of only having spectrally degraded signals available to them. That question was addressed in the current study. Specifically there were three goals: (1) to compare the language structures used by children with CIs to those of children with normal hearing (NH); (2) to assess the amount of variance in the language measures explained by phonological awareness and lexical knowledge; and (3) to assess the amount of variance in the language measures explained by factors related to the hearing loss itself and subsequent treatment. Design Language samples were obtained and transcribed for 40 children who had just completed kindergarten: 19 with NH and 21 with CIs. Five measures were derived from Systematic Analysis of Language Transcripts (SALT): (1) mean length of utterance in morphemes, (2) number of conjunctions, excluding and, (3) number of personal pronouns, (4) number of bound morphemes, and (5) number of different words. Measures were also collected on phonological awareness and lexical knowledge. Statistics examined group differences, as well as the amount of variance in the language measures explained by phonological awareness, lexical knowledge, and factors related to hearing loss and its treatment for children with CIs. Results Mean scores of children with CIs were roughly one standard deviation below those of children with NH on all language measures, including lexical knowledge, matching outcomes of other studies. Mean scores of children with CIs were closer to two standard deviations below those of children with NH on two out of three measures of phonological awareness (specifically those related to phonemic

  7. Ultrasonic Techniques for Baseline-Free Damage Detection in Structures

    NASA Astrophysics Data System (ADS)

    Dutta, Debaditya

    This research presents ultrasonic techniques for baseline-free damage detection in structures in the context of structural health monitoring (SHM). Conventional SHM methods compare signals obtained from the pristine condition of a structure (baseline signals) with those from the current state, and relate certain changes in the signal characteristics to damage. While this approach has been successful in the laboratory, there are certain drawbacks of depending on baseline signals in real field applications. Data from the pristine condition are not available for most existing structures. Even if they are available, operational and environmental variations tend to mask the effect of damage on the signal characteristics. Most important, baseline measurements may become meaningless while assessing the condition of a structure after an extreme event such as an earthquake or a hurricane. Such events may destroy the sensors themselves and require installation of new sensors at different locations on the structure. Baseline-free structural damage detection can broaden the scope of SHM in the scenarios described above. A detailed discussion on the philosophy of baseline-free damage detection is provided in Chapter 1. Following this discussion, the research questions are formulated. The organization of this document and the major contributions of this research are also listed in this chapter. Chapter 2 describes a fully automated baseline-free technique for notch and crack detection in plates using a collocated pair of piezoelectric wafer transducers for measuring ultrasonic signals. Signal component corresponding to the damage induced mode-converted Lamb waves is extracted by processing the originally measured ultrasonic signals. The damage index is computed as a function of this mode-converted Lamb wave signal component. An over-determined system of Lamb wave measurements is used to find a least-square estimate of the measurement errors. This error estimate serves as the

  8. Detecting small scale CO2 emission structures using OCO-2

    NASA Astrophysics Data System (ADS)

    Schwandner, Florian M.; Eldering, Annmarie; Verhulst, Kristal R.; Miller, Charles E.; Nguyen, Hai M.; Oda, Tomohiro; O'Dell, Christopher; Rao, Preeti; Kahn, Brian; Crisp, David; Gunson, Michael R.; Sanchez, Robert M.; Ashok, Manasa; Pieri, David; Linick, Justin P.; Yuen, Karen

    2016-04-01

    Localized carbon dioxide (CO2) emission structures cover spatial domains of less than 50 km diameter and include cities and transportation networks, as well as fossil fuel production, upgrading and distribution infra-structure. Anthropogenic sources increasingly upset the natural balance between natural carbon sources and sinks. Mitigation of resulting climate change impacts requires management of emissions, and emissions management requires monitoring, reporting and verification. Space-borne measurements provide a unique opportunity to detect, quantify, and analyze small scale and point source emissions on a global scale. NASA's first satellite dedicated to atmospheric CO2 observation, the July 2014 launched Orbiting Carbon Observatory (OCO-2), now leads the afternoon constellation of satellites (A-Train). Its continuous swath of 2 to 10 km in width and eight footprints across can slice through coincident emission plumes and may provide momentary cross sections. First OCO-2 results demonstrate that we can detect localized source signals in the form of urban total column averaged CO2 enhancements of ~2 ppm against suburban and rural backgrounds. OCO-2's multi-sounding swath observing geometry reveals intra-urban spatial structures reflected in XCO2 data, previously unobserved from space. The transition from single-shot GOSAT soundings detecting urban/rural differences (Kort et al., 2012) to hundreds of soundings per OCO-2 swath opens up the path to future capabilities enabling urban tomography of greenhouse gases. For singular point sources like coal fired power plants, we have developed proxy detections of plumes using bands of imaging spectrometers with sensitivity to SO2 in the thermal infrared (ASTER). This approach provides a means to automate plume detection with subsequent matching and mining of OCO-2 data for enhanced detection efficiency and validation. © California Institute of Technology

  9. Extended Kalman filter based structural damage detection for MR damper controlled structures

    NASA Astrophysics Data System (ADS)

    Jin, Chenhao; Jang, Shinae; Sun, Xiaorong; Jiang, Zhaoshuo; Christenson, Richard

    2016-04-01

    The Magneto-rheological (MR) dampers have been widely used in many building and bridge structures against earthquake and wind loadings due to its advantages including mechanical simplicity, high dynamic range, low power requirements, large force capacity, and robustness. However, research about structural damage detection methods for MR damper controlled structures is limited. This paper aims to develop a real-time structural damage detection method for MR damper controlled structures. A novel state space model of MR damper controlled structure is first built by combining the structure's equation of motion and MR damper's hyperbolic tangent model. In this way, the state parameters of both the structure and MR damper are added in the state vector of the state space model. Extended Kalman filter is then used to provide prediction for state variables from measurement data. The two techniques are synergistically combined to identify parameters and track the changes of both structure and MR damper in real time. The proposed method is tested using response data of a three-floor MR damper controlled linear building structure under earthquake excitation. The testing results show that the adaptive extended Kalman filter based approach is capable to estimate not only structural parameters such as stiffness and damping of each floor, but also the parameters of MR damper, so that more insights and understanding of the damage can be obtained. The developed method also demonstrates high damage detection accuracy and light computation, as well as the potential to implement in a structural health monitoring system.

  10. Transcatheter aortic valve implantation

    PubMed Central

    Oliemy, Ahmed

    2014-01-01

    Transcatheter aortic valve implantation was developed to offer a therapeutic solution to patients with severe symptomatic aortic stenosis who are not candidates for conventional aortic valve replacement. The improvement in transcatheter aortic valve implantation outcomes is still of concern in the areas of stroke, vascular injury, heart block, paravalvular regurgitation and valve durability. Concomitantly, the progress, both technical and in terms of material advances of transcatheter valve systems, as well as in patient selection, renders transcatheter aortic valve implantation an increasingly viable treatment for more and more patients with structural heart disease. PMID:25374670