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Sample records for neural prostheses iridium

  1. Investigation of sputtered iridium oxide as a stimulating/sensing material for neural prostheses

    Science.gov (United States)

    Negi, Sandeep

    Neural interface devices are developed for neuroscience and neuroprosthetics applications to record and stimulate nerve signals. Microelectrodes represent the direct interface between the biological tissue and the electronic system in neural prostheses that serve to record electrical signals from the nerves to obtain information from the natural sensors of the body or the motor fibers of the muscles. Also, the microelectrodes can inject charge into the targeted tissue to functionally excite nerves and muscles by electrical stimulation. Overall, the neural microelectrodes have to measure electrical potentials and have to exchange charge between the solid state of the electrode and the fluid state of the electrolyte in the body. Therefore, the interface between the microelectrode and biological fluid is a critical factor for the performance of the neural device. The interface properties depend mainly on the physical, electrical and chemical property of the electrode material. Even though a large selection of electrode materials has been tested for this purpose, to date no electrode material or coating process presented in scientific literature has been identified or qualified for long-term stimulation and recording neural signals. In this work, sputtered iridium oxide film (SIROF) was investigated as a potential electrode material. SIROF was deposited on the microelectrodes by reactive pulsed DC sputtering. The deposition parameters and corresponding film properties were examined and correlated with the stimulation and recording characteristics. Furthermore, for chronic applications, the stability of SIROF was investigated and stimulation protocol was determined for damage threshold of the film. The sputtering pressure was varied to obtain SIROF with desired properties. The SIROF properties were optimized based on its ability to inject charge in the tissue and its mechanical strength. The electrochemical characterization of SIROF was studied by electrochemical

  2. Stimulation and recording electrodes for neural prostheses

    CERN Document Server

    Pour Aryan, Naser; Rothermel, Albrecht

    2015-01-01

    This book provides readers with basic principles of the electrochemistry of the electrodes used in modern, implantable neural prostheses. The authors discuss the boundaries and conditions in which the electrodes continue to function properly for long time spans, which are required when designing neural stimulator devices for long-term in vivo applications. Two kinds of electrode materials, titanium nitride and iridium are discussed extensively, both qualitatively and quantitatively. The influence of the counter electrode on the safety margins and electrode lifetime in a two electrode system is explained. Electrode modeling is handled in a final chapter.

  3. Neural prostheses and brain plasticity

    Science.gov (United States)

    Fallon, James B.; Irvine, Dexter R. F.; Shepherd, Robert K.

    2009-12-01

    The success of modern neural prostheses is dependent on a complex interplay between the devices' hardware and software and the dynamic environment in which the devices operate: the patient's body or 'wetware'. Over 120 000 severe/profoundly deaf individuals presently receive information enabling auditory awareness and speech perception from cochlear implants. The cochlear implant therefore provides a useful case study for a review of the complex interactions between hardware, software and wetware, and of the important role of the dynamic nature of wetware. In the case of neural prostheses, the most critical component of that wetware is the central nervous system. This paper will examine the evidence of changes in the central auditory system that contribute to changes in performance with a cochlear implant, and discuss how these changes relate to electrophysiological and functional imaging studies in humans. The relationship between the human data and evidence from animals of the remarkable capacity for plastic change of the central auditory system, even into adulthood, will then be examined. Finally, we will discuss the role of brain plasticity in neural prostheses in general.

  4. Performance sustaining intracortical neural prostheses

    Science.gov (United States)

    Nuyujukian, Paul; Kao, Jonathan C.; Fan, Joline M.; Stavisky, Sergey D.; Ryu, Stephen I.; Shenoy, Krishna V.

    2014-12-01

    Objective. Neural prostheses, or brain-machine interfaces, aim to restore efficient communication and movement ability to those suffering from paralysis. A major challenge these systems face is robust performance, particularly with aging signal sources. The aim in this study was to develop a neural prosthesis that could sustain high performance in spite of signal instability while still minimizing retraining time. Approach. We trained two rhesus macaques implanted with intracortical microelectrode arrays 1-4 years prior to this study to acquire targets with a neurally-controlled cursor. We measured their performance via achieved bitrate (bits per second, bps). This task was repeated over contiguous days to evaluate the sustained performance across time. Main results. We found that in the monkey with a younger (i.e., two year old) implant and better signal quality, a fixed decoder could sustain performance for a month at a rate of 4 bps, the highest achieved communication rate reported to date. This fixed decoder was evaluated across 22 months and experienced a performance decline at a rate of 0.24 bps yr-1. In the monkey with the older (i.e., 3.5 year old) implant and poorer signal quality, a fixed decoder could not sustain performance for more than a few days. Nevertheless, performance in this monkey was maintained for two weeks without requiring additional online retraining time by utilizing prior days’ experimental data. Upon analysis of the changes in channel tuning, we found that this stability appeared partially attributable to the cancelling-out of neural tuning fluctuations when projected to two-dimensional cursor movements. Significance. The findings in this study (1) document the highest-performing communication neural prosthesis in monkeys, (2) confirm and extend prior reports of the stability of fixed decoders, and (3) demonstrate a protocol for system stability under conditions where fixed decoders would otherwise fail. These improvements to decoder

  5. Neural prostheses in clinical practice: biomedical microsystems in neurological rehabilitation.

    Science.gov (United States)

    Stieglitz, T

    2007-01-01

    Technical devices have supported physicians in diagnosis, therapy, and rehabilitation since ancient times. Neural prostheses interface parts of the nervous system with technical (micro-) systems to partially restore sensory and motor functions that have been lost due to trauma or diseases. Electrodes act as transducers to record neural signals or to excite neural cells by means of electrical stimulation. The field of neural prostheses has grown over the last decades. An overview of neural prostheses illustrates the opportunities and limitations of the implants and performance in their current size and complexity. The implementation of microsystem technology with integrated microelectronics in neural implants 20 years ago opened new fields of application, but also new design paradigms and approaches with respect to the biostability of passivation and housing concepts and electrode interfaces. Microsystem specific applications in the peripheral nervous system, vision prostheses and brain-machine interfaces show the variety of applications and the challenges in biomedical microsystems for chronic nerve interfaces in new and emerging research fields that bridge neuroscientific disciplines with material science and engineering. Different scenarios are discussed where system complexity strongly depends on the rehabilitation objective and the amount of information that is necessary for the chosen neuro-technical interface.

  6. Titania nanotube arrays as interfaces for neural prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Sorkin, Jonathan A. [Department of Mechanical Engineering, Colorado State University, Fort Collins CO 80523 (United States); Hughes, Stephen [Department of Chemical and Biological Engineering, Colorado State University, Fort Collins CO 80523 (United States); School of Biomedical Engineering, Colorado State University, Fort Collins CO 80523 (United States); Soares, Paulo [Department of Mechanical Engineering, Polytechnic School, Pontifícia Universidade Católica do Paraná, Curitiba, PR 80215-901 (Brazil); Popat, Ketul C., E-mail: ketul.popat@colostate.edu [Department of Mechanical Engineering, Colorado State University, Fort Collins CO 80523 (United States); School of Biomedical Engineering, Colorado State University, Fort Collins CO 80523 (United States)

    2015-04-01

    Neural prostheses have become ever more acceptable treatments for many different types of neurological damage and disease. Here we investigate the use of two different morphologies of titania nanotube arrays as interfaces to advance the longevity and effectiveness of these prostheses. The nanotube arrays were characterized for their nanotopography, crystallinity, conductivity, wettability, surface mechanical properties and adsorption of key proteins: fibrinogen, albumin and laminin. The loosely packed nanotube arrays fabricated using a diethylene glycol based electrolyte, contained a higher presence of the anatase crystal phase and were subsequently more conductive. These arrays yielded surfaces with higher wettability and lower modulus than the densely packed nanotube arrays fabricated using water based electrolyte. Further the adhesion, proliferation and differentiation of the C17.2 neural stem cell line was investigated on the nanotube arrays. The proliferation ratio of the cells as well as the level of neuronal differentiation was seen to increase on the loosely packed arrays. The results indicate that loosely packed nanotube arrays similar to the ones produced here with a DEG based electrolyte, may provide a favorable template for growth and maintenance of C17.2 neural stem cell line. - Highlights: • Titania nanotube arrays can be fabricated with to have loosely or densely packed morphologies. • Titania nanotube arrays support higher C17.2 neural stem cell adhesion and proliferation. • Titania nanotube arrays support higher C17.2 neural stem cell differentiation towards neuronal lineage.

  7. Titania nanotube arrays as interfaces for neural prostheses.

    Science.gov (United States)

    Sorkin, Jonathan A; Hughes, Stephen; Soares, Paulo; Popat, Ketul C

    2015-04-01

    Neural prostheses have become ever more acceptable treatments for many different types of neurological damage and disease. Here we investigate the use of two different morphologies of titania nanotube arrays as interfaces to advance the longevity and effectiveness of these prostheses. The nanotube arrays were characterized for their nanotopography, crystallinity, conductivity, wettability, surface mechanical properties and adsorption of key proteins: fibrinogen, albumin and laminin. The loosely packed nanotube arrays fabricated using a diethylene glycol based electrolyte, contained a higher presence of the anatase crystal phase and were subsequently more conductive. These arrays yielded surfaces with higher wettability and lower modulus than the densely packed nanotube arrays fabricated using water based electrolyte. Further the adhesion, proliferation and differentiation of the C17.2 neural stem cell line was investigated on the nanotube arrays. The proliferation ratio of the cells as well as the level of neuronal differentiation was seen to increase on the loosely packed arrays. The results indicate that loosely packed nanotube arrays similar to the ones produced here with a DEG based electrolyte, may provide a favorable template for growth and maintenance of C17.2 neural stem cell line. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Electric stimulation with sinusoids and white noise for neural prostheses

    Directory of Open Access Journals (Sweden)

    Daniel K Freeman

    2010-02-01

    Full Text Available We are investigating the use of novel stimulus waveforms in neural prostheses to determine whether they can provide more precise control over the temporal and spatial pattern of elicited activity as compared to conventional pulsatile stimulation. To study this, we measured the response of retinal ganglion cells to both sinusoidal and white noise waveforms. The use of cell-attached and whole cell patch clamp recordings allowed the responses to be observed without significant obstruction from the stimulus artifact. Electric stimulation with sinusoids elicited robust responses. White noise analysis was used to derive the linear kernel for the ganglion cell’s spiking response as well as for the underlying excitatory currents. These results suggest that in response to electric stimulation, presynaptic retinal neurons exhibit bandpass filtering characteristics with peak response that occur 25ms after onset. The experimental approach demonstrated here may be useful for studying the temporal response properties of other neurons in the CNS.

  9. Auditory Neural Prostheses – A Window to the Future

    Directory of Open Access Journals (Sweden)

    Mohan Kameshwaran

    2015-06-01

    Full Text Available Hearing loss is one of the commonest congenital anomalies to affect children world-over. The incidence of congenital hearing loss is more pronounced in developing countries like the Indian sub-continent, especially with the problems of consanguinity. Hearing loss is a double tragedy, as it leads to not only deafness but also language deprivation. However, hearing loss is the only truly remediable handicap, due to remarkable advances in biomedical engineering and surgical techniques. Auditory neural prostheses help to augment or restore hearing by integration of an external circuitry with the peripheral hearing apparatus and the central circuitry of the brain. A cochlear implant (CI is a surgically implantable device that helps restore hearing in patients with severe-profound hearing loss, unresponsive to amplification by conventional hearing aids. CIs are electronic devices designed to detect mechanical sound energy and convert it into electrical signals that can be delivered to the coch­lear nerve, bypassing the damaged hair cells of the coch­lea. The only true prerequisite is an intact auditory nerve. The emphasis is on implantation as early as possible to maximize speech understanding and perception. Bilateral CI has significant benefits which include improved speech perception in noisy environments and improved sound localization. Presently, the indications for CI have widened and these expanded indications for implantation are related to age, additional handicaps, residual hearing, and special etiologies of deafness. Combined electric and acoustic stimulation (EAS / hybrid device is designed for individuals with binaural low-frequency hearing and severe-to-profound high-frequency hearing loss. Auditory brainstem implantation (ABI is a safe and effective means of hearing rehabilitation in patients with retrocochlear disorders, such as neurofibromatosis type 2 (NF2 or congenital cochlear nerve aplasia, wherein the cochlear nerve is damaged

  10. Nonlinear modeling of neural population dynamics for hippocampal prostheses.

    Science.gov (United States)

    Song, Dong; Chan, Rosa H M; Marmarelis, Vasilis Z; Hampson, Robert E; Deadwyler, Sam A; Berger, Theodore W

    2009-11-01

    Developing a neural prosthesis for the damaged hippocampus requires restoring the transformation of population neural activities performed by the hippocampal circuitry. To bypass a damaged region, output spike trains need to be predicted from the input spike trains and then reinstated through stimulation. We formulate a multiple-input, multiple-output (MIMO) nonlinear dynamic model for the input-output transformation of spike trains. In this approach, a MIMO model comprises a series of physiologically-plausible multiple-input, single-output (MISO) neuron models that consist of five components each: (1) feedforward Volterra kernels transforming the input spike trains into the synaptic potential, (2) a feedback kernel transforming the output spikes into the spike-triggered after-potential, (3) a noise term capturing the system uncertainty, (4) an adder generating the pre-threshold potential, and (5) a threshold function generating output spikes. It is shown that this model is equivalent to a generalized linear model with a probit link function. To reduce model complexity and avoid overfitting, statistical model selection and cross-validation methods are employed to choose the significant inputs and interactions between inputs. The model is applied successfully to the hippocampal CA3-CA1 population dynamics. Such a model can serve as a computational basis for the development of hippocampal prostheses.

  11. At the interface: convergence of neural regeneration and neural prostheses for restoration of function.

    Science.gov (United States)

    Grill, W M; McDonald, J W; Peckham, P H; Heetderks, W; Kocsis, J; Weinrich, M

    2001-01-01

    The rapid pace of recent advances in development and application of electrical stimulation of the nervous system and in neural regeneration has created opportunities to combine these two approaches to restoration of function. This paper relates the discussion on this topic from a workshop at the International Functional Electrical Stimulation Society. The goals of this workshop were to discuss the current state of interaction between the fields of neural regeneration and neural prostheses and to identify potential areas of future research that would have the greatest impact on achieving the common goal of restoring function after neurological damage. Identified areas include enhancement of axonal regeneration with applied electric fields, development of hybrid neural interfaces combining synthetic silicon and biologically derived elements, and investigation of the role of patterned neural activity in regulating various neuronal processes and neurorehabilitation. Increased communication and cooperation between the two communities and recognition by each field that the other has something to contribute to their efforts are needed to take advantage of these opportunities. In addition, creative grants combining the two approaches and more flexible funding mechanisms to support the convergence of their perspectives are necessary to achieve common objectives.

  12. Neural prostheses and biomedical microsystems in neurological rehabilitation.

    Science.gov (United States)

    Koch, K P

    2007-01-01

    Interfaces between electrodes and the neural system differ with respect to material and shape depending on their intended application and fabrication method. This chapter will review the different electrode designs regarding the technological implementation and fabrication process. Furthermore this book chapter will describe electrodes for interfacing the peripheral nerves like cuff, book or helix as well as electrodes for interfacing the cortex like needle arrays. The implantation method and mechanical interaction between the electrode and the nervous tissue were taken into consideration. To develop appropriate microtechnological assembling strategies that ensure proper interfacing between the tiny electrodes and microelectronics or connectors is one of the major challenges. The integration of electronics into the system helps to improve the reliability of detecting neural signals and reduces the size of the implants. Promising results with these novel electrodes will pave the road for future developments such as visual prosthetics or improved control of artificial limbs in paralyzed patients.

  13. Neural prostheses in clinical applications--trends from precision mechanics towards biomedical microsystems in neurological rehabilitation.

    Science.gov (United States)

    Stieglitz, T; Schuettler, M; Koch, K P

    2004-04-01

    Neural prostheses partially restore body functions by technical nerve excitation after trauma or neurological diseases. External devices and implants have been developed since the early 1960s for many applications. Several systems have reached nowadays clinical practice: Cochlea implants help the deaf to hear, micturition is induced by bladder stimulators in paralyzed persons and deep brain stimulation helps patients with Parkinson's disease to participate in daily life again. So far, clinical neural prostheses are fabricated with means of precision mechanics. Since microsystem technology opens the opportunity to design and develop complex systems with a high number of electrodes to interface with the nervous systems, the opportunity for selective stimulation and complex implant scenarios seems to be feasible in the near future. The potentials and limitations with regard to biomedical microdevices are introduced and discussed in this paper. Target specifications are derived from existing implants and are discussed on selected applications that has been investigated in experimental research: a micromachined implant to interface a nerve stump with a sieve electrode, cuff electrodes with integrated electronics, and an epiretinal vision prosthesis.

  14. Flavopiridol reduces the impedance of neural prostheses in vivo without affecting recording quality.

    Science.gov (United States)

    Purcell, Erin K; Thompson, David E; Ludwig, Kip A; Kipke, Daryl R

    2009-10-15

    We hypothesized that re-entry into the cell cycle may be associated with reactive gliosis surrounding neural prostheses, and that administration of a cell cycle inhibitor (flavopiridol) at the time of surgery would reduce this effect. We investigated the effects of flavopiridol on recording quality and impedance over a 28-day time period and conducted histology at 3 and 28 days post-implantation. Flavopiridol reduced the expression of a cell cycle protein (cyclin D1) in microglia surrounding probes at the 3-day time point. Impedance at 1 kHz was decreased by drug administration across the study period compared to vehicle controls. Correlations between recording (SNR, units) and impedance metrics revealed a small, but statistically significant, inverse relationship between these variables. However, the relationship between impedance and recording quality was not sufficiently strong for flavopiridol to result in an improvement in SNR or the number of units detected. Our data indicate that flavopiridol is an effective, easily administered treatment for reducing impedance in vivo, potentially through inhibiting microglial encapsulation of implanted devices. This strategy may be useful in stimulation applications, where reduced impedance is desirable for achieving activation thresholds and prolonging the lifetime of the implanted power supply. While improvements in recording quality were not observed, a combination of flavopiridol with a second strategy which enhances neuronal signal detection may enhance these results in future studies.

  15. Mechanomyography-Based Wearable Monitor of Quasi-Isometric Muscle Fatigue for Motor Neural Prostheses.

    Science.gov (United States)

    Krueger, Eddy; Popović-Maneski, Lana; Nohama, Percy

    2018-02-01

    A motor neural prosthesis based on surface functional electrical stimulation (sFES) can restore functional movement (e.g., standing, walking) in patients with a spinal cord injury (SCI). sFES generates muscle contractions in antigravity muscles and allows balance-assisted standing. This induced standing has several benefits, such as improved cardiovascular function, decreased incidence of urinary infections, reduced joint contractures, and muscle atrophy. The duration of sFES assisted standing is limited due to the quick onset of muscle fatigue. Currently, there is no method available to reliably estimate real-time muscle fatigue during sFES. Simply monitoring the M-wave changes is not suitable due to the high signal disturbances that arise during multi-channel electrical stimulation. Mechanomyography (MMG) is immune to electrical stimulation artifacts and can be used to detect subtle vibrations on the surface of the skin related to activation of the underlying muscle's motor units (MU). The aim of this study was to develop a method for detecting muscle fatigue brought on by sFES. The method was tested in three different heads of the quadriceps muscle in SCI patients during electrically elicited quasi-isometric contraction. Six spinal cord-injured male volunteers, with no voluntary control of the quadriceps muscle participated in the study. Electrical bursts of voltage-controlled monophasic square pulses at frequencies of 1 kHz (50% duty cycle) at 50 Hz (15% duty cycle) were used to generate thigh muscle contractions that controlled the knee joint in the sagittal plane. The pulse amplitudes were set to position the knee joint at a 5° angle from the horizontal plane and when the knee angle dropped to 20° (e.g., the quadriceps were unable to hold the lower leg in the desired position), the test was terminated. Two data segments lasting 10 s each, at the beginning and end of each test, were analyzed. The muscle contraction was assessed by MMG sensors positioned on

  16. Refining Radchem Detectors: Iridium

    Science.gov (United States)

    Arnold, C. W.; Bredeweg, T. A.; Vieira, D. J.; Bond, E. M.; Jandel, M.; Rusev, G.; Moody, W. A.; Ullmann, J. L.; Couture, A. J.; Mosby, S.; O'Donnell, J. M.; Haight, R. C.

    2013-10-01

    Accurate determination of neutron fluence is an important diagnostic of nuclear device performance, whether the device is a commercial reactor, a critical assembly or an explosive device. One important method for neutron fluence determination, generally referred to as dosimetry, is based on exploiting various threshold reactions of elements such as iridium. It is possible to infer details about the integrated neutron energy spectrum to which the dosimetry sample or ``radiochemical detector'' was exposed by measuring specific activation products post-irradiation. The ability of radchem detectors like iridium to give accurate neutron fluence measurements is limited by the precision of the cross-sections in the production/destruction network (189Ir-193Ir). The Detector for Advanced Neutron Capture Experiments (DANCE) located at LANSCE is ideal for refining neutron capture cross sections of iridium isotopes. Recent results from a measurement of neutron capture on 193-Ir are promising. Plans to measure other iridium isotopes are underway.

  17. Iridium complexes for electrocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Sheehan, Stafford Wheeler; Hintermair, Ulrich; Thomsen, Julianne M; Brudvig, Gary W; Crabtree, Robert H

    2017-10-17

    Solution-phase (e.g., homogeneous) or surface-immobilized (e.g., heterogeneous) electrode-driven oxidation catalysts based on iridium coordination compounds which self-assemble upon chemical or electrochemical oxidation of suitable precursors and methods of making and using thereof are. Iridium species such as {[Ir(LX).sub.x(H.sub.2O).sub.y(.mu.-O)].sub.z.sup.m+}.sub.n wherein x, y, m are integers from 0-4, z and n from 1-4 and LX is an oxidation-resistant chelate ligand or ligands, such as such as 2(2-pyridyl)-2-propanolate, form upon oxidation of various molecular iridium complexes, for instance [Cp*Ir(LX)OH] or [(cod)Ir(LX)] (Cp*=pentamethylcyclopentadienyl, cod=cis-cis,1,5-cyclooctadiene) when exposed to oxidative conditions, such as sodium periodate (NaIO.sub.4) in aqueous solution at ambient conditions.

  18. Disaster mitigation - The Iridium way

    Science.gov (United States)

    Swan, Peter A.; Love, Lee M.

    1992-08-01

    The paper discusses salient features of a telecommunication concept, called Iridium. Iridium is envisioned as a network of telecommunication satellites which will make it possible to communicate 'anytime-at-any-place' on the globe. The Iridium system will consist of 77 satellites; earth stations, called gateways, connected to the public switched telephone networks; and the personal communication telephone. It is pointed out that Iridium communication system will have a dramatic impact on mitigating the effects of severe disasters (natural or manmade) by providing direct communications to the user before, during, and after the disaster.

  19. Photodiode circuits for retinal prostheses.

    Science.gov (United States)

    Loudin, J D; Cogan, S F; Mathieson, K; Sher, A; Palanker, D V

    2011-10-01

    Photodiode circuits show promise for the development of high-resolution retinal prostheses. While several of these systems have been constructed and some even implanted in humans, existing descriptions of the complex optoelectronic interaction between light, photodiode, and the electrode/electrolyte load are limited. This study examines this interaction in depth with theoretical calculations and experimental measurements. Actively biased photoconductive and passive photovoltaic circuits are investigated, with the photovoltaic circuits consisting of one or more diodes connected in series, and the photoconductive circuits consisting of a single diode in series with a pulsed bias voltage. Circuit behavior and charge injection levels were markedly different for platinum and sputtered iridium-oxide film (SIROF) electrodes. Photovoltaic circuits were able to deliver 0.038 mC/cm(2) (0.75 nC/phase) per photodiode with 50- μm platinum electrodes, and 0.54-mC/cm(2) (11 nC/phase) per photodiode with 50-μ m SIROF electrodes driven with 0.5-ms pulses of light at 25 Hz. The same pulses applied to photoconductive circuits with the same electrodes were able to deliver charge injections as high as 0.38 and 7.6 mC/cm(2) (7.5 and 150 nC/phase), respectively. We demonstrate photovoltaic stimulation of rabbit retina in-vitro, with 0.5-ms pulses of 905-nm light using peak irradiance of 1 mW/mm(2). Based on the experimental data, we derive electrochemical and optical safety limits for pixel density and charge injection in various circuits. While photoconductive circuits offer smaller pixels, photovoltaic systems do not require an external bias voltage. Both classes of circuits show promise for the development of high-resolution optoelectronic retinal prostheses.

  20. Decoding stimulus identity from multi-unit activity and local field potentials along the ventral auditory stream in the awake primate: implications for cortical neural prostheses

    Science.gov (United States)

    Smith, Elliot; Kellis, Spencer; House, Paul; Greger, Bradley

    2013-02-01

    Objective. Hierarchical processing of auditory sensory information is believed to occur in two streams: a ventral stream responsible for stimulus identity and a dorsal stream responsible for processing spatial elements of a stimulus. The objective of the current study is to examine neural coding in this processing stream in the context of understanding the possibility for an auditory cortical neural prosthesis. Approach. We examined the selectivity for species-specific primate vocalizations in the ventral auditory processing stream by applying a statistical classifier to neural data recorded from microelectrode arrays. Multi-unit activity (MUA) and local field potential (LFP) data recorded simultaneously from primary auditory complex (AI) and rostral parabelt (PBr) were decoded on a trial-by-trial basis. Main results. While decode performance in AI was well above chance, mean performance in PBr did not deviate >15% from chance level. Mean performance levels were similar for MUA and LFP decodes. Increasing the spectral and temporal resolution improved decode performance; while inter-electrode spacing could be as large as 1.14 mm without degrading decode performance. Significance. These results serve as preliminary guidance for a human auditory cortical neural prosthesis; instructing interface implementation, microstimulation patterns and anatomical placement.

  1. A bright tetranuclear iridium(III) complex.

    Science.gov (United States)

    Baranoff, Etienne; Orselli, Enrico; Allouche, Lionel; Di Censo, Davide; Scopelliti, Rosario; Grätzel, Michael; Nazeeruddin, Md Khaja

    2011-03-14

    A cyclic tetranuclear cyclometallated iridium(III) complex using cyanide anions as bridging ligands and displaying a tetrahedrally distorted square geometry has been obtained with high yield; photo- and electrochemical characterizations show that most interesting properties of mononuclear cyclometallated iridium complexes are retained in the tetranuclear assembly.

  2. TCP Performance Enhancement Over Iridium

    Science.gov (United States)

    Torgerson, Leigh; Hutcherson, Joseph; McKelvey, James

    2007-01-01

    In support of iNET maturation, NASA-JPL has collaborated with NASA-Dryden to develop, test and demonstrate an over-the-horizon vehicle-to-ground networking capability, using Iridium as the vehicle-to-ground communications link for relaying critical vehicle telemetry. To ensure reliability concerns are met, the Space Communications Protocol Standards (SCPS) transport protocol was investigated for its performance characteristics in this environment. In particular, the SCPS-TP software performance was compared to that of the standard Transmission Control Protocol (TCP) over the Internet Protocol (IP). This paper will report on the results of this work.

  3. On the dissolution of iridium by aluminum.

    Energy Technology Data Exchange (ETDEWEB)

    Hewson, John C.

    2009-08-01

    The potential for liquid aluminum to dissolve an iridium solid is examined. Substantial uncertainties exist in material properties, and the available data for the iridium solubility and iridium diffusivity are discussed. The dissolution rate is expressed in terms of the regression velocity of the solid iridium when exposed to the solvent (aluminum). The temperature has the strongest influence in the dissolution rate. This dependence comes primarily from the solubility of iridium in aluminum and secondarily from the temperature dependence of the diffusion coefficient. This dissolution mass flux is geometry dependent and results are provided for simplified geometries at constant temperatures. For situations where there is negligible convective flow, simple time-dependent diffusion solutions are provided. Correlations for mass transfer are also given for natural convection and forced convection. These estimates suggest that dissolution of iridium can be significant for temperatures well below the melting temperature of iridium, but the uncertainties in actual rates are large because of uncertainties in the physical parameters and in the details of the relevant geometries.

  4. DC Breakdown Experiments with Iridium Cathode

    CERN Document Server

    Profatilova, Iaroslava; Korsback, Anders; Muranaka, Tomoko; Wuensch, Walter

    2015-01-01

    Electrical breakdown occurring in rf accelerating structures is one of the major disruptions of the accelerated beam in CLIC. At CERN, as complements to rf facilities, DC-spark systems have been used to study breakdown properties of many candidate materials for making rf components. In this note, measurements of conditioning speed, breakdown field and field enhancement factor of iridium are presented comparing with previously tested materials. The average breakdown field after conditioning reached 238 MV/m, which places iridium next to copper. By comparison with results and properties of other metals, the low breakdown field of iridium could be explained by its face-centred-cubic crystal structure.

  5. [Craniofacial prostheses for facial defects].

    Science.gov (United States)

    Federspil, P A

    2010-06-01

    Craniofacial prostheses (or epitheses) are artificial substitutes for facial defects. Today, prostheses made of silicone are state-of-the-art. They may be fixed anatomically (to already existing structures), mechanically (to spectacle frames), chemically (using adhesives), or surgically (to osseointegrated titanium implants). With the existing extraoral implant systems, prostheses may be securely anchored to the bone regardless of size and location of the defect. The classic atraumatic surgical technique has remained an unchanged prerequisite for successful implantation by avoidance of any heat trauma to the bone. This review outlines the indications and contra-indications as well as advantages and disadvantages of craniofacial prostheses and their retention methods in various facial regions. It summarizes the basic principles of extraoral implantology in respect to implant positioning and the management of children and radiated patients.

  6. Iridium-192 Production for Cancer Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Rostelato, M.E.C.M.; Silva, C.P.G.; Rela, P.R.; Zeituni, C.A.; Lepki, V.; Feher, A.

    2004-10-05

    The purpose of this work is to settle a laboratory for Iridium -192 sources production, that is, to determine a wire activation method and to build a hot cell for the wires manipulation, quality control and packaging. The paper relates, mainly, the wire activation method and its quality control. The wire activation is carried out in our nuclear reactor, IEA- R1m.

  7. Powered Lower Limb Prostheses

    OpenAIRE

    Grimmer, Martin

    2015-01-01

    Human upright locomotion emerged about 6 million years ago. It is achieved by a complex interaction of the biological infrastructure and the neural control. Bones, muscles, tendons, central nervous commands and reflex mechanisms interact to provide robust and efficient bipedal movement patterns like walking or running. Next to these locomotion tasks humans can also perform complex movements like climbing, dancing or jumping. Diseases or traumatic events may cause the loss of parts of the biol...

  8. Nanoporous sputtered platinum-iridium-thinfilms for medical and energy applications; Nanoporoese gesputterte Platin-Iridium-Schichten fuer Anwendungen in der Medizin- und Energietechnik

    Energy Technology Data Exchange (ETDEWEB)

    Ganske, Gerald

    2012-10-05

    Sputtering makes it possible to create thinfilms of only a few atom layers and to customize them for special applications by adjusting the deposition parameters. In this work interface-layers are deposited and characterized in biological systems as stimulation electrodes for neural cells and as catalysts in hydrogen fuel cells. First of all, highly porous platinum films were created by sputtering at a pressure of 9 Pa and low power of less than 100 W. These parameters are an ideal compromise between deposition rate, porosity and disordered crystal structure of the layers. Investigations on co-sputtered platinum-iridium-films (PtIr) showed that these films form homogeneous structures and no distinction between the separate layers is possible. It was demonstrated that these films obtain the crystal structure of Pt as well as the finer cauliflower-like structure of iridium, if the atoms reach the substrate surface only with their thermal energy. Furthermore, it was shown that the film composition reflects the sputtering power of the separate targets in a linear way. The structure of the films can be predicted by means of monte-carlo-simulation, which was verified by SEM-pictures. The ratio of the sputtering power can be used to control the amount of interface elements which was confirmed by electrochemical tests. Electrode materials for the stimulation of neural cells need a large electrochemically active surface that allows for an interface between electron and ion conductivity. Test on platinum, iridium and PtIr have shown that the films sputtered at the lowest impact energy do have the largest active surface as well as the largest charge delivery capacity (CDC). Iridium films show the highest CDC (48 mC/cm{sup 2}), followed by platinum-iridium (2 mC/cm{sup 2}, 100 W power at both targets) and pure platinum (16 mC/cm{sup 2}). This can be explained by the large surface area of iridium and its electrochemical activation process. Although PtIr layers also show an

  9. Global personal communications this decade with Iridium

    Science.gov (United States)

    Swan, Peter A.; Cloutier, Paul N.

    1991-10-01

    The concepts and technologies related to the Iridium global communication system are described emphasizing the cross-linked satellite network and cellular architecture. The cellular architecture is implemented in an up-side-down fashion, and crosslinks at K-band are to be used for 77 internetted small smart spacecraft. A system-control facility is also described which is designed to maintain the automated network of global space-based telecommunications.

  10. [Biomechanic considerations in wrist prostheses].

    Science.gov (United States)

    Kapandji, A I

    1992-01-01

    At the present time, in disorders of the wrist, avulsion of the first carpal row is the most commonly used technique as a last resort. However, there are many wrist prostheses, which are reviewed here. Roughly, they belong to two families: the three axis prostheses (spherical) that cannot transmit to the hand the pronation supination torque, because of their geometrical characteristics, and the two axis prostheses (universal joint) that are able to transmit this movement. The characteristics of future prostheses must include: based on the "universal joint" principle, occupy minimum space, isometric, maintain tendon tension, an axis identical to the true axis of the wrist, to maintain the hand in line with the forearm, fixed without cement but, not shortened with time, possibilities of mechanical flexibility immediately and lastingly stable, to be easily replaced modularly. This ideal prosthesis will certainly exist one day and will take the place of the first carpal row avulsion. In the meantime, this technique will still have a long use.

  11. Microbial biofilms on facial prostheses

    NARCIS (Netherlands)

    Ariani, Nina; Vissink, Arjan; van Oort, Robert P.; Kusdhany, Lindawati; Djais, Ariadna; Rahardjo, Tri Budi W.; van der Mei, Henny C.; Krom, Bastiaan P.

    2012-01-01

    The composition of microbial biofilms on silicone rubber facial prostheses was investigated and compared with the microbial flora on healthy and prosthesis-covered skin. Scanning electron microscopy showed the presence of mixed bacterial and yeast biofilms on and deterioration of the surface of the

  12. High Iridium concentration of alkaline rocks of Deccan and ...

    Indian Academy of Sciences (India)

    We report here an unusually high concentration of iridium in some alkali basalts and alkaline rocks of Deccan region having an age of about 65Ma, similar to the age of the Cretaceous-Tertiary boundary. The alkali basalts of Anjar, in the western periphery of Deccan province, have irid-ium concentration as high as 178pg/g ...

  13. Cementless Hydroxyapatite Coated Hip Prostheses

    Science.gov (United States)

    Herrera, Antonio; Mateo, Jesús; Gil-Albarova, Jorge; Lobo-Escolar, Antonio; Ibarz, Elena; Gabarre, Sergio; Más, Yolanda

    2015-01-01

    More than twenty years ago, hydroxyapatite (HA), calcium phosphate ceramics, was introduced as a coating for cementless hip prostheses. The choice of this ceramic is due to its composition being similar to organic apatite bone crystals. This ceramic is biocompatible, bioactive, and osteoconductive. These qualities facilitate the primary stability and osseointegration of implants. Our surgical experience includes the implantation of more than 4,000 cementless hydroxyapatite coated hip prostheses since 1990. The models implanted are coated with HA in the acetabulum and in the metaphyseal area of the stem. The results corresponding to survival and stability of implants were very satisfactory in the long-term. From our experience, HA-coated hip implants are a reliable alternative which can achieve long term survival, provided that certain requirements are met: good design selection, sound choice of bearing surfaces based on patient life expectancy, meticulous surgical technique, and indications based on adequate bone quality. PMID:25802848

  14. Cementless Hydroxyapatite Coated Hip Prostheses

    Directory of Open Access Journals (Sweden)

    Antonio Herrera

    2015-01-01

    Full Text Available More than twenty years ago, hydroxyapatite (HA, calcium phosphate ceramics, was introduced as a coating for cementless hip prostheses. The choice of this ceramic is due to its composition being similar to organic apatite bone crystals. This ceramic is biocompatible, bioactive, and osteoconductive. These qualities facilitate the primary stability and osseointegration of implants. Our surgical experience includes the implantation of more than 4,000 cementless hydroxyapatite coated hip prostheses since 1990. The models implanted are coated with HA in the acetabulum and in the metaphyseal area of the stem. The results corresponding to survival and stability of implants were very satisfactory in the long-term. From our experience, HA-coated hip implants are a reliable alternative which can achieve long term survival, provided that certain requirements are met: good design selection, sound choice of bearing surfaces based on patient life expectancy, meticulous surgical technique, and indications based on adequate bone quality.

  15. Hip prostheses in young adults. Surface prostheses and short-stem prostheses.

    Science.gov (United States)

    Gallart, X; Riba, J; Fernández-Valencia, J A; Bori, G; Muñoz-Mahamud, E; Combalia, A

    2017-11-28

    The poor results obtained in young patients when using a conventional prosthesis led to the resurgence of hip resurfacing to find less invasive implants for the bone. Young patients present a demand for additional activity, which makes them a serious challenge for the survival of implants. In addition, new information technologies contribute decisively to the preference for non-cemented prostheses. Maintaining quality of life, preserving the bone and soft tissues, as well as achieving a very stable implant, are the goals of every hip orthopaedic surgeon for these patients. The results in research point to the use of smaller prostheses, which use the metaphyseal zone more and less the diaphyseal zone, and hence the large number of the abovementioned short stem prostheses. Both models are principally indicated in the young adult. Their revision should be a more simple operation, but this is only true for hip resurfacing, not for short stems. Copyright © 2017 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  16. Reconditioning medical prostheses by welding

    Science.gov (United States)

    Rontescu, C.; Cicic, D. T.; Vasile, I. M.; Bogatu, A. M.; Amza, C. G.

    2017-08-01

    After the technological process of making, some of the medical prostheses may contain imperfections, which can lead to framing the product in the spoilage category. This paper treats the possibility of reconditioning by welding of the prosthesis made of titanium alloys. The paper presents the obtained results after the reconditioning by welding, using the GTAW process, of a intramedullary rod type prosthesis in which was found a crack after the non-destructive examination. The obtained result analysis, after the micrographic examination of the welded joint areas, highlighted that the process of reconditioning by welding can be applied successfully in such situations.

  17. Half-sandwich ruthenium, rhodium and iridium complexes of ...

    Indian Academy of Sciences (India)

    sandwich ruthenium, rhodium and iridium complexes of triazolopyridine ligand: Synthesis and structural studies. NARASINGA RAO PALEPU RAO MOHAN KOLLIPARA. Regular Article Volume 129 Issue 2 February 2017 pp 177-184 ...

  18. Iridium Catalysis: Reductive Conversion of Glucan to Xylan

    DEFF Research Database (Denmark)

    Pedersen, Martin Jæger; Madsen, Robert; Clausen, Mads Hartvig

    2018-01-01

    By using iridium catalysed dehydrogenative decarbonylation, we converted a partly protected cellobioside into a fully protected xylobioside. We demonstrate good yields with two different aromatic ester protecting groups. The resulting xylobioside was directly used as glycosyl donor in further syn...

  19. CO adsorption on neutral iridium clusters

    CERN Document Server

    Kerpal, Christian; Meijer, Gerard; Fielicke, André

    2010-01-01

    The adsorption of carbon monoxide on neutral iridium clusters in the size range of n = 3 to 21 atoms is investigated with infrared multiple photon dissociation spectroscopy. For each cluster size only a single v(CO) band is present with frequencies in the range between 1962 cm-1 (n = 8) and 1985 cm-1 (n = 18) which can be attributed to an atop binding geometry. This behaviour is compared to the CO binding geometries on clusters of other group 9 and 10 transition metals as well as to that on extended surfaces. The preference of Ir for atop binding is rationalized by relativistic effects on the electronic structure of the later 5d metals.

  20. Iridium NEXT: A Global access for your sensor needs

    Science.gov (United States)

    Gupta, O. P.; Fish, C. S.

    2010-12-01

    The operational Iridium constellation is comprised of 66 satellites, used to primarily provide worldwide voice and data coverage to satellite phones, pagers and integrated transceivers. The satellites are in low Earth orbit at 781 km and inclination of 86.4 deg, resulting in unprecedented 24/7 coverage and real-time visibility of the entire globe. Recently, through funding from the National Science Foundation (NSF), Iridium has been utilized by the Johns Hopkins University Applied Physics Laboratory (APL), with help from The Boeing Company, as an infrastructure for a comprehensive network for space environment measurements. Known as the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE), the Iridium-based system provides real-time magnetic field measurements using the satellites as part of a new observation network to forecast weather in space. In February 2007, Iridium announced Iridium NEXT, a novel design for a second-generation satellite constellation. Anticipated to begin launching in 2015, Iridium NEXT will maintain the existing Iridium constellation architecture of 66 cross-linked satellite LEO covering 100 percent of the globe. In the spirit of AMPERE, for commercial, government, and scientific organizations Iridium NEXT also plans to offer new earth and space observation opportunities through hosted hosted payloads on the 66 Iridium NEXT satellite network. To provide seamless support and access to this latest innovation in payload transportation, Iridium NEXT has teamed with Space Dynamics Laboratory - Utah State University which has delivered thousands of successful sensors and subsystems for over 400 space borne and aircraf based payloads. One such innovation called SensorPOD will offer unique benefits such as unprecedented spatial and temporal coverage, real-time relay of data to and from up to 5 Kg payloads in space, and access to space at a fraction of the cost of a dedicated missions such as 3U or larger Cubesats. In this

  1. Knee Angle Estimation Algorithm for Myoelectric Control of Active Transfemoral Prostheses

    Science.gov (United States)

    Delis, Alberto López; de Carvalho, João Luiz Azevedo; Da Rocha, Adson Ferreira; de Oliveira Nascimento, Francisco Assis; Borges, Geovany Araújo

    This paper presents a bioinstrumentation system for the acquisition and pre-processing of surface electromyographic (SEMG) signals, and a knee angle estimation algorithm for control of active transfemoral leg prostheses, using methods for feature extraction and classification of myoelectric signal patterns. The presented microcontrolled bioinstrumentation system is capable of recording up to four SEMG channels, and one electrogoniometer channel. The proposed neural myoelectric controller algorithm is capable of predicting the intended knee joint angle from the measured SEMG signals. The algorithm is designed in three stages: feature extraction, using auto-regressive model and amplitude histogram; feature projection, using self organizing maps; and pattern classification, using a Levenberg-Marquardt neural network. The use of SEMG signals and additional mechanical information such as that provided by the electrogoniometer may improve precision in the control of leg prostheses. Preliminary results are presented.

  2. A High-Performance Neural Prosthesis Enabled by Control Algorithm Design

    Science.gov (United States)

    Gilja, Vikash; Nuyujukian, Paul; Chestek, Cindy A.; Cunningham, John P.; Yu, Byron M.; Fan, Joline M.; Churchland, Mark M.; Kaufman, Matthew T.; Kao, Jonathan C.; Ryu, Stephen I.; Shenoy, Krishna V.

    2012-01-01

    Neural prostheses translate neural activity from the brain into control signals for guiding prosthetic devices, such as computer cursors and robotic limbs, and thus offer disabled patients greater interaction with the world. However, relatively low performance remains a critical barrier to successful clinical translation; current neural prostheses are considerably slower with less accurate control than the native arm. Here we present a new control algorithm, the recalibrated feedback intention-trained Kalman filter (ReFIT-KF), that incorporates assumptions about the nature of closed loop neural prosthetic control. When tested with rhesus monkeys implanted with motor cortical electrode arrays, the ReFIT-KF algorithm outperforms existing neural prostheses in all measured domains and halves acquisition time. This control algorithm permits sustained uninterrupted use for hours and generalizes to more challenging tasks without retraining. Using this algorithm, we demonstrate repeatable high performance for years after implantation across two monkeys, thereby increasing the clinical viability of neural prostheses. PMID:23160043

  3. Conducting Polymers for Neural Prosthetic and Neural Interface Applications

    Science.gov (United States)

    2015-01-01

    Neural interfacing devices are an artificial mechanism for restoring or supplementing the function of the nervous system lost as a result of injury or disease. Conducting polymers (CPs) are gaining significant attention due to their capacity to meet the performance criteria of a number of neuronal therapies including recording and stimulating neural activity, the regeneration of neural tissue and the delivery of bioactive molecules for mediating device-tissue interactions. CPs form a flexible platform technology that enables the development of tailored materials for a range of neuronal diagnostic and treatment therapies. In this review the application of CPs for neural prostheses and other neural interfacing devices are discussed, with a specific focus on neural recording, neural stimulation, neural regeneration, and therapeutic drug delivery. PMID:26414302

  4. Patients' satisfaction with facial prostheses.

    Science.gov (United States)

    Wondergem, Marloes; Lieben, George; Bouman, Shirley; van den Brekel, Michiel W M; Lohuis, Peter J F M

    2016-05-01

    We assessed the "impact on wellbeing" and "satisfaction" of patients who had a facial prosthesis (of the ear, nose, or orbit) fitted in The Netherlands Cancer Institute. Patients had either an adhesive-retained or an implant-retained facial prosthesis between 1951 and 2011. We did a cross-sectional survey of 104 patients, then gave a questionnaire to the final study group of 71 (68%), a year or more later. All were satisfied with their prostheses (visual analogue scale (VAS): mean (SD) 8.1(1.5). The implant-retained group were the most satisfied (p=0.022), and the adhesive-retained group felt more self-conscious (p=0.013). Three-quarters of all patients said that the prosthesis was not painful and there were no problems with the way it functioned. A well-designed facial prosthesis has obvious benefits, but there were no appreciable differences between the two groups. Each patient must make a careful decision about which type of prosthesis to choose, taking into account the quality of their remaining tissue, the site of the defect, and their general health. Copyright © 2015 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  5. Homogeneous and heterogenized iridium water oxidation catalysts

    Science.gov (United States)

    Macchioni, Alceo

    2014-10-01

    The development of an efficient catalyst for the oxidative splitting of water into molecular oxygen, protons and electrons is of key importance for producing solar fuels through artificial photosynthesis. We are facing the problem by means of a rational approach aimed at understanding how catalytic performance may be optimized by the knowledge of the reaction mechanism of water oxidation and the fate of the catalytic site under the inevitably harsh oxidative conditions. For the purposes of our study we selected iridium water oxidation catalysts, exhibiting remarkable performance (TOF > 5 s-1 and TON > 20000). In particular, we recently focused our attention on [Cp*Ir(N,O)X] (N,O = 2-pyridincarboxylate; X = Cl or NO3) and [IrCl(Hedta)]Na water oxidation catalysts. The former exhibited a remarkable TOF whereas the latter showed a very high TON. Furthermore, [IrCl(Hedta)]Na was heterogenized onto TiO2 taking advantage of the presence of a dandling -COOH functionality. The heterogenized catalyst maintained approximately the same catalytic activity of the homogeneous analogous with the advantage that could be reused many times. Mechanistic studies were performed in order to shed some light on the rate-determining step and the transformation of catalysts when exposed to "oxidative stress". It was found that the last oxidative step, preceding oxygen liberation, is the rate-determining step when a small excess of sacrificial oxidant is used. In addition, several intermediates of the oxidative transformation of the catalyst were intercepted and characterized by NMR, X-Ray diffractometry and ESI-MS.

  6. Clinico-statistical study on radiotherapy prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Takaaki; Taniguchi, Hisashi; Sunahara, Yuichi; Shinozuka, Osamu; Suzuki, Ruri; Ohyama, Takashi; Takeda, Masamune [Tokyo Medical and Dental Univ. (Japan). School of Dentistry

    1996-06-01

    Various radiotherapy prostheses, including spacer, protector, carrier and mold, are frequently used for oral and maxillofacial cancer patients because they enhance the treatment efficacy of radiotherapy and protect adjacent normal tissue from irradiation. Therefore a clinical investigation was carried out on 310 cases of radiotherapy prostheses applied in our clinic from 1981 to 1995. The results were as follows: Sex ratio (male: female) of patients was 1.67: 1 and the number of the patients at the age of 60-69 was the largest. Spacer accounted for 81.0% of prostheses, followed by mold (10.6%), protector (5.5%) and carrier (2.9%). As for the site of malignant tumor, the tongue was 77.1% of all cases. External irradiation was already performed on 23.3% of all cases. Abutment teeth remained in 85.9% of 304 cases in which the prostheses were applied intraorally. The average time to make the prostheses was 12.4 days. As for the retention of the prosthesis to the mouth, a ball clasp was used most frequently in spacer and carrier, and overlay type was applied most frequently in mold and protector. As for the retention of shield to carrier in mold cases, mechanical interlocking of the resin parts of carrier and shield was 75.8% of the cases. (author)

  7. Synthesis, structure, redox and spectra of green iridium complexes ...

    Indian Academy of Sciences (India)

    TECS

    3. *For correspondence. Synthesis, structure, redox and spectra of green iridium complexes of tridentate azo-aromatic ligands. MANASHI PANDA,a CHAYAN DAS,a CHEN-HSIUNG HUNGb and. SREEBRATA ... Mn(II)7 and Fe(II)8 but also produces stable anionic ..... the EPR of the oxidized complexes were not suc- cessful ...

  8. Atropisomerism in a thermally switchable, cyclometallated iridium complex.

    Science.gov (United States)

    Howarth, Ashlee J; Davies, David L; Lelj, Francesco; Wolf, Michael O; Patrick, Brian O

    2012-09-14

    Two stable diastereomeric atropisomers of a cyclometallated iridium complex containing a pyrene functionalized pyridine imine ligand have been isolated. These are the first fully characterized examples of metal containing atropisomers in which the rotational axis is not between two chelating atoms. The atropisomers can be converted thermally via a rocking motion of the pyrene moiety.

  9. Prototyping iridium coated mirrors for x-ray astronomy

    Science.gov (United States)

    Döhring, Thorsten; Probst, Anne-Catherine; Stollenwerk, Manfred; Emmerich, Florian; Stehlíková, Veronika; Inneman, Adolf

    2017-05-01

    X-ray astronomy uses space-based telescopes to overcome the disturbing absorption of the Earth's atmosphere. The telescope mirrors are operating at grazing incidence angles and are coated with thin metal films of high-Z materials to get sufficient reflectivity for the high-energy radiation to be observed. In addition the optical payload needs to be light-weighted for launcher mass constrains. Within the project JEUMICO, an acronym for "Joint European Mirror Competence", the Aschaffenburg University of Applied Sciences and the Czech Technical University in Prague started a collaboration to develop mirrors for X-ray telescopes. The X-ray telescopes currently developed within this Bavarian- Czech project are of Lobster eye type optical design. Corresponding mirror segments use substrates of flat silicon wafers which are coated with thin iridium films, as this material is promising high reflectivity in the X-ray range of interest. The deposition of the iridium films is based on a magnetron sputtering process. Sputtering with different parameters, especially by variation of the argon gas pressure, leads to iridium films with different properties. In addition to investigations of the uncoated mirror substrates the achieved surface roughness has been studied. Occasional delamination of the iridium films due to high stress levels is prevented by chromium sublayers. Thereby the sputtering parameters are optimized in the context of the expected reflectivity of the coated X-ray mirrors. In near future measurements of the assembled mirror modules optical performances are planned at an X-ray test facility.

  10. Achieving Zero Stress in Iridium, Chromium, and Nickle Thin Films

    Science.gov (United States)

    Broadway, David M.; Weimer, Jeffrey; Gurgew, Danielle; Lis, Tomasz; Ramsey, Brian D.; O'Dell, Stephen L.; Ames, A.; Bruni, R.

    2015-01-01

    We examine a method for achieving zero intrinsic stress in thin films of iridium, chromium, and nickel deposited by magnetron sputter deposition. The examination of the stress in these materials is motivated by efforts to advance the optical performance of light-weight x-ray space telescopes into the regime of sub-arc second resolution that rely on control of the film stress to values within 10-100 MPa. A characteristic feature of the intrinsic stress behavior in chromium and nickel is their sensitivity to the magnitude and sign of the intrinsic stress with argon gas pressure, including the existence of a critical pressure that results in zero film stress. This critical pressure scales linearly with the film's density. While the effect of stress reversal with argon pressure has been previously reported by Hoffman and others for nickel and chromium, we have discovered a similar behavior for iridium. Additionally, we have identified zero stress in iridium shortly after island coalescence. This feature of film growth is used for achieving a total internal stress of -2.89 MPa for a 15.8 nm thick iridium film. The surface roughness of this low-stress film was examined using scanning probe microscopy (SPM) and x-ray reflectivity (XRR) at CuKa and these results presented and discussed.

  11. Iridium profiles and delivery across the Cretaceous/Paleogene boundary

    NARCIS (Netherlands)

    Esmeray-Senlet, Selen; Miller, Kenneth G.; Sherrell, Robert M.; Senlet, Turgay; Vellekoop, Johan; Brinkhuis, Henk

    2017-01-01

    We examined iridium (Ir) anomalies at the Cretaceous/Paleogene (K/Pg) boundary in siliciclastic shallow marine cores of the New Jersey Coastal Plain, USA, that were deposited at an intermediate distance (∼2500 km) from the Chicxulub, Mexico crater. Although closely spaced and generally

  12. High Iridium concentration of alkaline rocks of Deccan and ...

    Indian Academy of Sciences (India)

    R. Narasimhan, Krishtel eMaging Solutions

    and implications to K/T boundary. P N Shukla, N Bhandari∗, Anirban Das, A D Shukla and J S Ray. Physical Research Laboratory, Ahmedabad 380 009, India. ∗e-mail: bhandari@prl.ernet.in. We report here an unusually high concentration of iridium in some alkali basalts and alkaline rocks of Deccan region having an age ...

  13. The Iridium (tm) system: Personal communications anytime, anyplace

    Science.gov (United States)

    Hatlelid, John E.; Casey, Larry

    1993-01-01

    The Iridium system is designed to provide handheld personal communications between diverse locations around the world at any time and without prior knowledge of the location of the personal units. This paper provides an overview of the system, the services it provides, its operation, and an overview of the commercial practices and relatively high volume satellite production techniques which will make the system cost effective. A constellation of 66 satellites will provide an orbiting, spherical-shell, infrastructure for this global calling capability. The satellites act as tall cellular towers and allow convenient operation for portable handheld telephones. The system will provide a full range of services including voice, paging, data, geolocation, and fax capabilities. Motorola is a world leader in the production of high volume, high quality, reliable telecommunications hardware. One of Iridium's goals is to apply these production techniques to high reliability space hardware. Concurrent engineering, high performance work teams, advanced manufacturing technologies, and improved assembly and test methods are some of the techniques that will keep the Iridium system cost effective. Mobile, global, flexible personal communications are coming that will allow anyone to call or receive a call from/to anyplace at anytime. The Iridium system will provide communications where none exist today. This connectivity will allow increased information transfer, open new markets for various business endeavors, and in general increase productivity and development.

  14. The Iridium (tm) system: Personal communications anytime, anyplace

    Science.gov (United States)

    Hatlelid, John E.; Casey, Larry

    The Iridium system is designed to provide handheld personal communications between diverse locations around the world at any time and without prior knowledge of the location of the personal units. This paper provides an overview of the system, the services it provides, its operation, and an overview of the commercial practices and relatively high volume satellite production techniques which will make the system cost effective. A constellation of 66 satellites will provide an orbiting, spherical-shell, infrastructure for this global calling capability. The satellites act as tall cellular towers and allow convenient operation for portable handheld telephones. The system will provide a full range of services including voice, paging, data, geolocation, and fax capabilities. Motorola is a world leader in the production of high volume, high quality, reliable telecommunications hardware. One of Iridium's goals is to apply these production techniques to high reliability space hardware. Concurrent engineering, high performance work teams, advanced manufacturing technologies, and improved assembly and test methods are some of the techniques that will keep the Iridium system cost effective. Mobile, global, flexible personal communications are coming that will allow anyone to call or receive a call from/to anyplace at anytime. The Iridium system will provide communications where none exist today. This connectivity will allow increased information transfer, open new markets for various business endeavors, and in general increase productivity and development.

  15. A STUDY OF TRACHEAL PROSTHESES PRODUCED BY ...

    African Journals Online (AJOL)

    BIG TIMMY

    2009-01-05

    Jan 5, 2009 ... Natural tracheal may become defective due to, among other things, abnormal narrowing or fistulas, direct or indirect result of accidents or narrowing caused by inflammation. In an acute situation when direct anastomoses. (cross-connection) cannot be made, tracheal prostheses are often needed to bridge ...

  16. [Improving the quality of glass ocular prostheses].

    Science.gov (United States)

    Nadareĭshvili, T B; Pakhomova, T S; Labutina, L V; Kachko, A L

    1979-01-01

    A critical analysis has been attempted of the current state-of-the-art in studying seleno-cadmium ruby glasses applicable for glass ocular prosthesis production. Better quality of these prostheses can be achieved by both the refinement of the ruby glass composition and by its strengthening (hardening) through proper methods.

  17. Magnetic resonance imaging of breast prostheses

    African Journals Online (AJOL)

    G5

    by silicone gel and when the silicone gel separates the elastomer shell from the sur- rounding fibrous breast capsule. Introduction. Breast implantation using prostheses is becoming a common plastic surgical proce- dure in this country. In the USA between 1 and 2 million women have had breast implantation procedures.1.

  18. Magnetic resonance imaging of breast prostheses

    African Journals Online (AJOL)

    G5

    ... these two signs,. 7. SA JOURNAL OF RADIOLOGY • October 2005. REVIEW ARTICLE. Magnetic resonance imaging of breast prostheses. P Corr. FFRad (D) SA. P Seolall. Nat Dip Rad (D). H Booth. Nat Dip Rad (D). Department of Radiology. Nelson Mandela School of Medicine and Inkosi Albert Luthuli Hospital. Durban ...

  19. Cycle Training Using Implanted Neural Prostheses: Team Cleveland

    Directory of Open Access Journals (Sweden)

    John McDaniel

    2017-12-01

    Full Text Available Recently our laboratory team focused on training five individuals with complete spinal cord injuries for an overground FES bike race in the 2016 Cybathlon held in Zurich Switzerland. A unique advantage team Cleveland had over other teams was the use of implanted pulse generators that provide more selective activation of muscles compared to standard surface stimulation. The advancements in muscle strength and endurance and ultimately cycling power our pilots made during this training period helped propel our competing pilot to win gold at the Cybathlon and allowed our pilots to ride their bikes outside within their communities. Such positive outcomes has encouraged us to further explore more widespread use of FES overground cycling as a rehabilitative tool for those with spinal cord injuries. This review will describes our approach to this race including information on the pilots, stimulation strategy, bike details and training program.

  20. Modelling the luminescence of iridium cyclometalated complexes encapsulated in cucurbituril.

    Science.gov (United States)

    Alrawashdeh, Lubna R; Cronin, Michael P; Day, Anthony I; Wallace, Lynne; Woodward, Clifford E

    2018-01-15

    Iridium(iii) cyclometalated complexes in aqueous solution often display relatively weak luminescence. It has been shown in previous work that this emission can be significantly enhanced (by up to two orders of magnitude) by encapsulation in cucurbit[10]uril (Q[10]). Luminescence lifetime measurements suggest a dynamic self-quenching mechanism is active, possibly due to displacement of an excited guest complex via collision with an unbound complex. We devise a model for the association of a group of iridium(iii) cyclometalated complexes with Q[10]. The model parameters are then fitted to steady-state emission titration curves. The excellent agreement of experimental data with the model provides valuable mechanistic information relating to the way this class of metal complexes interact and associate with the Q[10] host.

  1. Iridium-Doped Ruthenium Oxide Catalyst for Oxygen Evolution

    Science.gov (United States)

    Valdez, Thomas I.; Narayan, Sri R.; Billings, Keith J.

    2011-01-01

    NASA requires a durable and efficient catalyst for the electrolysis of water in a polymer-electrolyte-membrane (PEM) cell. Ruthenium oxide in a slightly reduced form is known to be a very efficient catalyst for the anodic oxidation of water to oxygen, but it degrades rapidly, reducing efficiency. To combat this tendency of ruthenium oxide to change oxidation states, it is combined with iridium, which has a tendency to stabilize ruthenium oxide at oxygen evolution potentials. The novel oxygen evolution catalyst was fabricated under flowing argon in order to allow the iridium to preferentially react with oxygen from the ruthenium oxide, and not oxygen from the environment. Nanoparticulate iridium black and anhydrous ruthenium oxide are weighed out and mixed to 5 18 atomic percent. They are then heat treated at 300 C under flowing argon (in order to create an inert environment) for a minimum of 14 hours. This temperature was chosen because it is approximately the creep temperature of ruthenium oxide, and is below the sintering temperature of both materials. In general, the temperature should always be below the sintering temperature of both materials. The iridium- doped ruthenium oxide catalyst is then fabricated into a PEM-based membrane- electrode assembly (MEA), and then mounted into test cells. The result is an electrolyzer system that can sustain electrolysis at twice the current density, and at the same efficiency as commercial catalysts in the range of 100-200 mA/sq cm. At 200 mA/sq cm, this new system operates at an efficiency of 85 percent, which is 2 percent greater than commercially available catalysts. Testing has shown that this material is as stable as commercially available oxygen evolution catalysts. This means that this new catalyst can be used to regenerate fuel cell systems in space, and as a hydrogen generator on Earth.

  2. Occlusion management of implant-supported prostheses

    OpenAIRE

    Delmas, Marion

    2017-01-01

    The implant solution has become the treatment of choice to replace missing teeth and to help in the retention of complete denture. Dental implants have different biological and biomechanical characteristics than natural teeth. Occlusion of implant-supported prostheses is considered to be one of the most important factors contributing to implant success. This thesis aims to review current recommendations for occlusal management of implant-supported prosthesis. The known and applied occlusal co...

  3. Rockot Launch Vehicle Commercial Operations for Grace and Iridium Program

    Science.gov (United States)

    Viertel, Y.; Kinnersley, M.; Schumacher, I.

    2002-01-01

    The GRACE mission and the IRIDIUM mission on ROCKOT launch vehicle are presented. Two identical GRACE satellites to measure in tandem the gravitational field of the earth with previously unattainable accuracy - it's called the Gravity Research and Climate Experiment, or and is a joint project of the U.S. space agency, NASA and the German Centre for Aeronautics and Space Flight, DLR. In order to send the GRACE twins into a 500x500 km , 89deg. orbit, the Rockot launch vehicle was selected. A dual launch of two Iridium satellites was scheduled for June 2002 using the ROCKOT launch vehicle from Plesetsk Cosmodrome in Northern Russia. This launch will inject two replacement satellites into a low earth orbit (LEO) to support the maintenance of the Iridium constellation. In September 2001, Eurockot successfully carried out a "Pathfinder Campaign" to simulate the entire Iridium mission cycle at Plesetsk. The campaign comprised the transport of simulators and related equipment to the Russian port-of-entry and launch site and also included the integration and encapsulation of the simulators with the actual Rockot launch vehicle at Eurockot's dedicated launch facilities at Plesetsk Cosmodrome. The pathfinder campaign lasted four weeks and was carried out by a joint team that also included Khrunichev, Russian Space Forces and Eurockot personnel on the contractors' side. The pathfinder mission confirmed the capability of Eurockot Launch Services to perform the Iridium launch on cost and on schedule at Plesetsk following Eurockot's major investment in international standard preparation, integration and launch facilities including customer facilities and a new hotel. In 2003, Eurockot will also launch the Japanese SERVI'S-1 satellite for USEF. The ROCKOT launch vehicle is a 3 stage liquid fuel rocket whose first 2 stages have been adapted from the Russian SS-19. A third stage, called "Breeze", can be repeatedly ignited and is extraordinarily capable of manoeuvre. Rockot can place

  4. Biomechanical Energy Harvester Design For Active Prostheses

    Directory of Open Access Journals (Sweden)

    Akın Oğuz Kaptı

    2012-06-01

    Full Text Available One of the factors restricting the functions of active prostheses is limited charge times and weights of the batteries. Therefore, some biomechanical energy harvesting studies are conducted for reducing the dependence on batteries and developing the systems that produce energy by utilizing one's own actions during daily living activities. In this study, as a new approach to meet energy needs of active-controlled lower limb prostheses, the design of a biomechanical energy harvester that produces electrical energy from the movements of the knee joint during gait were carried out. This harvester is composed of the generator, planetary gear system and one-way clutch that transmit just the knee extension. Low weight, low additional metabolic power consumption requirement and high electrical power generation are targeted in design process. The total reduction ratio of the transmission is 104, and the knee joint reaction torque applied by the system is 6 Nm. Average electrical powers that can be obtained are 17 W and 5,8 W for the swing extension phase and the entire cycle, respectively. These values seem to be sufficient for charging the battery units of many prostheses and similar medical systems, and portable electronic devices such as mobile phones, navigation devices and laptops.

  5. Towards high-resolution retinal prostheses with direct optical addressing and inductive telemetry

    Science.gov (United States)

    Ha, Sohmyung; Khraiche, Massoud L.; Akinin, Abraham; Jing, Yi; Damle, Samir; Kuang, Yanjin; Bauchner, Sue; Lo, Yu-Hwa; Freeman, William R.; Silva, Gabriel A.; Cauwenberghs, Gert

    2016-10-01

    Objective. Despite considerable advances in retinal prostheses over the last two decades, the resolution of restored vision has remained severely limited, well below the 20/200 acuity threshold of blindness. Towards drastic improvements in spatial resolution, we present a scalable architecture for retinal prostheses in which each stimulation electrode is directly activated by incident light and powered by a common voltage pulse transferred over a single wireless inductive link. Approach. The hybrid optical addressability and electronic powering scheme provides separate spatial and temporal control over stimulation, and further provides optoelectronic gain for substantially lower light intensity thresholds than other optically addressed retinal prostheses using passive microphotodiode arrays. The architecture permits the use of high-density electrode arrays with ultra-high photosensitive silicon nanowires, obviating the need for excessive wiring and high-throughput data telemetry. Instead, the single inductive link drives the entire array of electrodes through two wires and provides external control over waveform parameters for common voltage stimulation. Main results. A complete system comprising inductive telemetry link, stimulation pulse demodulator, charge-balancing series capacitor, and nanowire-based electrode device is integrated and validated ex vivo on rat retina tissue. Significance. Measurements demonstrate control over retinal neural activity both by light and electrical bias, validating the feasibility of the proposed architecture and its system components as an important first step towards a high-resolution optically addressed retinal prosthesis.

  6. Phosphorescent Imaging of Living Cells Using a Cyclometalated Iridium(III) Complex

    Science.gov (United States)

    Ma, Dik-Lung; Zhong, Hai-Jing; Fu, Wai-Chung; Chan, Daniel Shiu-Hin; Kwan, Hiu-Yee; Fong, Wang-Fun; Chung, Lai-Hon; Wong, Chun-Yuen; Leung, Chung-Hang

    2013-01-01

    A cell permeable cyclometalated iridium(III) complex has been developed as a phosphorescent probe for cell imaging. The iridium(III) solvato complex [Ir(phq)2(H2O]2)] preferentially stains the cytoplasm of both live and dead cells with a bright luminescence. PMID:23457478

  7. Development and Testing of High Surface Area Iridium Anodes for Molten Oxide Electrolysis

    Science.gov (United States)

    Shchetkovskiy, Anatoliy; McKechnie, Timothy; Sadoway, Donald R.; Paramore, James; Melendez, Orlando; Curreri, Peter A.

    2010-01-01

    Processing of lunar regolith into oxygen for habitat and propulsion is needed to support future space missions. Direct electrochemical reduction of molten regolith is an attractive method of processing, because no additional chemical reagents are needed. The electrochemical processing of molten oxides requires high surface area, inert anodes. Such electrodes need to be structurally robust at elevated temperatures (1400-1600?C), be resistant to thermal shock, have good electrical conductivity, be resistant to attack by molten oxide (silicate), be electrochemically stable and support high current density. Iridium with its high melting point, good oxidation resistance, superior high temperature strength and ductility is the most promising candidate for anodes in high temperature electrochemical processes. Several innovative concepts for manufacturing such anodes by electrodeposition of iridium from molten salt electrolyte (EL-Form? process) were evaluated. Iridium electrodeposition to form of complex shape components and coating was investigated. Iridium coated graphite, porous iridium structure and solid iridium anodes were fabricated. Testing of electroformed iridium anodes shows no visible degradation. The result of development, manufacturing and testing of high surface, inert iridium anodes will be presented.

  8. Determination of trace amounts of iridium by means of dithizone and substoichiometric isotope dilution

    Energy Technology Data Exchange (ETDEWEB)

    Roebisch, G.; Schober, W.; Bauer, P. (Paedagogische Hochschule Karl Liebknecht, Potsdam (German Democratic Republic). Sektion Chemie/Biologie)

    1982-01-01

    Iridium(III or IV) reacts with dithizone at pH 6 to form a 1:2 complex, which can be concentrated by extraction into chloroform. Based on this reaction, a reproducible, selective determination of iridium (1 ppb) is achieved by means of substoichiometric isotope dilution analysis based on /sup 192/Ir.

  9. VOICE PROSTHESES – TEN YEARS AFTER

    Directory of Open Access Journals (Sweden)

    Igor Fajdiga

    2002-12-01

    Full Text Available Since the introduction of tracheoesophageal puncture method by Bloom and Singer in 1980, the success of restoring vocal communication in laryngectomees has improved significantly. At the University Department of Otorhinolaringology and Cervicofacial Surgery in Ljubljana, the method has been used since 1993. We have performed 76 secondary tracheoesophageal punctures in patients with no objective contraindications and with an interest for this method. The success rate was 92%. With regard to our 10-years experience, we wanted to (re define present and future role of tracheoesophageal voice/speech in the alaryngeal voice rehabilitation. To compare both alaryngeal speech modes, 32 patients using tracheoesophageal speech and 35 patients using esophageal speech were included into the study. In both groups the patients were established speakers. The complications that occurred in the patients with voice prostheses are presented. Most of them required only replacement of prostheses for their solution.The tracheoesophageal puncture and voice prosthesis insertion is a reliable and fast way of restoring good voice and speech after laryngectomy. In spite of some objective disadvantage in comparison to esophageal speech – like the use of hand, need for regular maintenance, and relying to medical service, its good characteristics should rank it immediately after a good esophageal speech. This means that tracheoesophageal voice prostheses should be offered to all patients, which are not able to learn a good esophageal voice in short time, to avoid a frustrating time with no vocal communication. After tracheoesophageal puncture and voice prosthesis insertion, the patient should still get a possibility to learn esophageal speech if he wants to avoid the drawbacks of the tracheoesophageal speech.

  10. Field electron emission from a carbon-covered iridium tip

    Science.gov (United States)

    Bernatskii, D. P.; Pavlov, V. G.

    2017-11-01

    The formation of a carbon coating on an iridium field-emission electron emitter by benzene vapor pyrolysis has been studied. Processes on an emitting tip differ from those studied earlier on flat metal surfaces. The resulting coating either represents a monoatomic graphene film on the flat faces of the emitter or consists of graphene clusters. The field electron emission is localized on the edges and in the corners of a faceted graphite outgrowth. After alkali metals are adsorbed on the carbon coating, emissions from the flat faces anomalously grows and localizes on graphene-coated faces with alkali atoms present on the surface and under the graphene film.

  11. Aluminium Nitride Solidly Mounted BAW Resonators with Iridium Electrodes

    OpenAIRE

    Clement Lorenzo, Marta; Olivares Roza, Jimena; Iborra Grau, Enrique; González Castilla, Sheila; Sangrador García, Jesús; Rimmer, Nick; Rastogi, A; Ivira, B.; Reinhardt, Alexandre

    2008-01-01

    In this work we investigated the performance of aluminium nitride (AlN)-based solidly mounted resonators (SMR) made with iridium (Ir) bottom electrodes. Ir/AlN/metal stacks were grown on top of insulating Bragg mirrors composed of alternate λ/4 layers of silicon oxi-carbide (SiOC) and silicon nitride (Si3N4).Ir electrodes of various thicknesses were electron-beam evaporated on different adhesion layers, which also acted as seed layers. AlN was deposited by sputtering after conditioning the Ir...

  12. Luminescent cyclometallated iridium(III) complexes having acetylide ligands

    Science.gov (United States)

    Thompson, Mark E.; Bossi, Alberto; Djurovich, Peter Ivan

    2014-09-02

    The present invention relates to phosphorescent (triplet-emitting) organometallic materials. The phosphorescent materials of the present invention comprise Ir(III)cyclometallated alkynyl complexes for use as triplet light-emitting materials. The Ir(III)cyclometallated alkynyl complexes comprise at least one cyclometallating ligand and at least one alkynyl ligand bonded to the iridium. Also provided is an organic light emitting device comprising an anode, a cathode and an emissive layer between the anode and the cathode, wherein the emissive layer comprises a Ir(III)cyclometallated alkynyl complex as a triplet emitting material.

  13. Reverse saturable absorption (RSA) in fluorinated iridium derivatives

    Science.gov (United States)

    Ferry, Michael J.; O'Donnell, Ryan M.; Bambha, Neal; Ensley, Trenton R.; Shensky, William M.; Shi, Jianmin

    2017-08-01

    The photophysical properties of cyclometallated iridium compounds are beneficial for nonlinear optical (NLO) applications, such as the design of reverse saturable absorption (RSA) materials. We report on the NLO characterization of a family of compounds of the form [Ir(pbt)2(LX)], where pbt is 2-phenylbenzothiazole and LX is a beta-diketonate ligand. In particular, we investigate the effects of trifluoromethylation on compound solubility and photophysics compared to the parent acetylacetonate (acac) version. The NLO properties, such as the singlet and triplet excited-state cross sections, of these compounds were measured using the Z-scan technique. The excited-state lifetimes were determined from visible transient absorption spectroscopy.

  14. [Wrist joint arthroplasty: results after 41 prostheses].

    Science.gov (United States)

    Strunk, S; Bracker, W

    2009-06-01

    The advantage of wrist arthroplasty remains controversial, primarily due to the high complication rate. For this reason it seems sensible to monitor the results of different types of prostheses even with small numbers of cases. We were particularly interested to see if wrist joint arthroplasty is a useful alternative for patients with rheumatoid arthritis, and which of the types we used shows the best results. In our hospital, 41 wrist joint prostheses (15 Meuli, 16 BIAX and 10 Universal 2) were implanted in 36 patients from 1992 until 2005 (follow-up 1 to 14 years, mean 5.3 years). 33 patients had rheumatic destruction of the wrist, two had osteoarthritis following fracture of the scaphoid, and one pseudarthrosis after failed arthroplasty and arthrodesis for Kienböck's disease. Mean age was 54 years, ranging from 34 to 73 years. 14 patients had had surgery on this wrist before. The patients were sent a questionnaire including the DASH score, and a clinical evaluation and X-rays were performed. 33 patients with 38 wrist arthroplasties answered the questionnaire, 34 wrist joint prosthesis of 29 patients could be evaluated. 6 prostheses had to be removed because of complications (3 arthrodeses were performed after removal, 3 prostheses were exchanged). There were 4 dislocations (3 times with the Meuli type, once with the BIAX type). There was one case of CRPS type I. But subjectively, in answering our questionnaire, 31 of 38 patients claimed to be very satisfied or satisfied with the result of the operation, only 6 were less satisfied or not satisfied at all. An improvement of pain was found by all but one patient. An increase in strength or range of movement was found more rarely. The mean postoperative DASH score was 61 points. Mean wrist joint mobility was 50 degrees for extension/flexion, and 20 degrees for radial- and ulnar abduction. The result of total wrist joint arthroplasty depends very much on a careful patient selection. A preoperative bony malposition

  15. Subjective benefits of energy storing prostheses.

    Science.gov (United States)

    Alaranta, H; Lempinen, V M; Haavisto, E; Pohjolainen, T; Hurri, H

    1994-08-01

    The energy storing (ES) prosthesis has been used in the Prosthetic Foundation's workshop since 1987. Subjective responses from 168 amputees (141 trans-tibial and 27 trans-femoral) fitted with the ES prosthesis were analysed. Ratings were generally favourable in comparison with those for conventional prostheses. The most pronounced advantages of the new prosthesis as shown by the ratings were in walking uphill or swift walking. The younger amputees had more benefit than the older ones. High body weight decreased the benefit of the ES prosthesis. The ES prosthesis does not seem to provide any major advantage for the less active amputee whose movements are mainly indoors.

  16. Oral cavity anaerobic pathogens in biofilm formation on voice prostheses

    NARCIS (Netherlands)

    Bertl, Kristina; Zijnge, Vincent; Zatorska, Beata; Leonhard, Matthias; Schneider-Stickler, Berit; Harmsen, Hermie J. M.

    BACKGROUND: A polymerase chain reaction (PCR)-based method has been used to identify oral anaerobic pathogens in biofilms on voice prostheses. The purpose of the present study was to determine the location of those pathogens inside the biofilms. METHODS: Biofilms of 15 voice prostheses were sampled

  17. Lactobacilli : Important in biofilm formation on voice prostheses

    NARCIS (Netherlands)

    Buijssen, Kevin J. D. A.; Harmsen, Hermie J. M.; van der Mei, Henny C.; Busscher, Henk J.; van der Laan, Bernard F. A. M.

    OBJECTIVE: We sought to identify bacterial strains responsible for biofilm formation on silicone rubber voice prostheses. STUDY DESIGN: We conducted an analysis of the bacterial population in biofilms on used silicone rubber voice prostheses by using new microbiological methods. METHODS: Two

  18. Dynamic high-temperature characterization of an iridium alloy in tension

    Energy Technology Data Exchange (ETDEWEB)

    Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Jin, Helena [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bignell, John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); George, E. P. [Ruhr Univ., Bochum (Germany)

    2015-09-01

    Iridium alloys have been utilized as structural materials for certain high-temperature applications, due to their superior strength and ductility at elevated temperatures. The mechanical properties, including failure response at high strain rates and elevated temperatures of the iridium alloys need to be characterized to better understand high-speed impacts at elevated temperatures. A DOP-26 iridium alloy has been dynamically characterized in compression at elevated temperatures with high-temperature Kolsky compression bar techniques. However, the dynamic high-temperature compression tests were not able to provide sufficient dynamic high-temperature failure information of the iridium alloy. In this study, we modified current room-temperature Kolsky tension bar techniques for obtaining dynamic tensile stress-strain curves of the DOP-26 iridium alloy at two different strain rates (~1000 and ~3000 s-1) and temperatures (~750°C and ~1030°C). The effects of strain rate and temperature on the tensile stress-strain response of the iridium alloy were determined. The DOP-26 iridium alloy exhibited high ductility in stress-strain response that strongly depended on both strain rate and temperature.

  19. [Abdominal wall prostheses. Biomechanic and histological study].

    Science.gov (United States)

    Rath, A M; Zhang, J; Amouroux, J; Chevrel, J P

    1996-01-01

    The best prosthetic material is one which provides the best mechanical resistance with the best biological tolerance. In order to assess the mechanical and histological properties of abdominal wall prostheses, we performed experimental tests in animal models comparing four materials: polypropylene, dacron, polyglactine 910 and a dacron-polyglactine 910 composite. One hundred thirty rabbits were used including 10 controls and 120 test animals. A medial laparotomy was closed with an antemuscular aponevrotic prosthesis in the test animals. Animals were sacrificed at one, two and three months after the operation. Abdominal wall and prosthesis samples were tested to determine resistance to pressure and extension, deformability and elasticity. Histology tests were also done to determine resistance quality and biological tolerance. Dacron was tolerated best and was less resistant than polypropylene, though resistance was satisfactory. There was no advantage with polyglactine compared with non-resorbable prostheses; its only indication would be a septic site. The composite material tested had a resistance comparable with that of dacron but was less well tolerated.

  20. Iridium and tantalum foils for spaceflight neutron dosimetry.

    Science.gov (United States)

    English, R. A.; Liles, E. D.

    1972-01-01

    Description of a two-foil system of iridium and tantalum which can measure thermal and intermediate energy neutrons at flux densities of 1 neutron/sq cm-sec over a ten-day lunar mission (1,000,000 neutrons/sq cm). The foils are chemically inert and nontoxic, weigh less than 1 g each, and require only routine gamma pulse height analysis for activation measurement. Detection of fluences below 1,000,000 neutrons/sq cm are achieved for counts of foil activity made as late as two months following neutron exposure. Tantalum foils flown in Apollo 11 indicated a mean dose equivalent to the astronauts of less than 16 mrem from thermal plus intermediate energy neutrons, while nuclear emulsion track analysis indicated approximately 17 mrem from neutrons of energy greater than 0.6 MeV. Iridium foils flown on Apollo 12 indicated dose equivalents of 1.8 to 2.8 mrem from thermal neutrons, excluding tissue thermalized SNAP-27 neutrons.

  1. EDITORIAL: Focus on the neural interface Focus on the neural interface

    Science.gov (United States)

    Durand, Dominique M.

    2009-10-01

    The possibility of an effective connection between neural tissue and computers has inspired scientists and engineers to develop new ways of controlling and obtaining information from the nervous system. These applications range from `brain hacking' to neural control of artificial limbs with brain signals. Notwithstanding the significant advances in neural prosthetics in the last few decades and the success of some stimulation devices such as cochlear prosthesis, neurotechnology remains below its potential for restoring neural function in patients with nervous system disorders. One of the reasons for this limited impact can be found at the neural interface and close attention to the integration between electrodes and tissue should improve the possibility of successful outcomes. The neural interfaces research community consists of investigators working in areas such as deep brain stimulation, functional neuromuscular/electrical stimulation, auditory prostheses, cortical prostheses, neuromodulation, microelectrode array technology, brain-computer/machine interfaces. Following the success of previous neuroprostheses and neural interfaces workshops, funding (from NIH) was obtained to establish a biennial conference in the area of neural interfaces. The first Neural Interfaces Conference took place in Cleveland, OH in 2008 and several topics from this conference have been selected for publication in this special section of the Journal of Neural Engineering. Three `perspectives' review the areas of neural regeneration (Corredor and Goldberg), cochlear implants (O'Leary et al) and neural prostheses (Anderson). Seven articles focus on various aspects of neural interfacing. One of the most popular of these areas is the field of brain-computer interfaces. Fraser et al, report on a method to generate robust control with simple signal processing algorithms of signals obtained with electrodes implanted in the brain. One problem with implanted electrode arrays, however, is that

  2. Balancing activity, stability and conductivity of nanoporous core-shell iridium/iridium oxide oxygen evolution catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong-Tae; Lopes, Pietro Papa; Park, Shin-Ae; Lee, A-Yeong; Lim, Jinkyu; Lee, Hyunjoo; Back, Seoin; Jung, Yousung; Danilovic, Nemanja; Stamenkovic, Vojislav; Erlebacher, Jonah; Snyder, Joshua; Markovic, Nenad M.

    2017-11-13

    The selection of oxide materials for catalyzing the Oxygen Evolution Reaction in acid-based electrolyzers must be guided by the proper balance between activity, stability and conductivity – a challenging mission of great importance for delivering affordable and environmentally friendly hydrogen. Here we report that the highly conductive nanoporous architecture of an iridium oxide shell on a metallic iridium core, formed through the fast dealloying of osmium from an Ir25Os75 alloy, exhibits an exceptional balance between oxygen evolution activity and stability as quantified by the Activity-Stability FactorASF. Based on this metric, the nanoporous Ir/IrO2 morphology of dealloyed Ir25Os75 shows a factor of ~30 improvement ASFrelative to conventional Ir-based oxide materials and a ~8 times improvement over dealloyed Ir25Os75 nanoparticles due to optimized stability and conductivity, respectively. We propose that the Activity-Stability FactorASF is the key “metric” for determining the technological relevance of oxide-based anodic water electrolyzer catalysts.

  3. Maintenance of implant hybrid prostheses: clinical and laboratory procedures.

    Science.gov (United States)

    Drago, Carl; Gurney, Lynn

    2013-01-01

    Fixed implant hybrid prostheses have been used for the last 40+ years in the treatment of edentulous patients. These prostheses have provided long-term masticatory function for thousands of patients. The original treatment protocol included fabrication of cast metal frameworks that fit accurately on the restorative platforms or abutments and/or endosseous implants. Frameworks were designed to splint implants together; they also provided retention and support for the functional and esthetic portions of the fixed hybrid prostheses. Initially, edentulous patients were treated with maxillary complete dentures and mandibular fixed, hybrid prostheses. Denture teeth were used in both prostheses. Over the span of many years, occlusal surfaces of the denture teeth in the mandibular prostheses exhibited signs of occlusal abrasion and wear, sometimes completely abrading the teeth and denture bases, resulting in framework exposures. Ultimately, this resulted in decreased chewing efficiency and loss of vertical facial height. Patients would then return to clinicians and ask for retreatment. In certain instances, the underlying frameworks would have to be remade. This involved replicating the original series of appointments and significant additional expense to patients and clinicians alike. The protocol presented in this article avoids having to remake the most expensive portion of fixed implant prostheses--the frameworks. The protocol identifies the clinical and laboratory procedures involved in using existing frameworks and replacing preexisting denture bases and denture teeth, with minimal inconvenience to patients. © 2012 by the American College of Prosthodontists.

  4. Analysis and Implications of the Iridium 33-Cosmos 2251 Collision

    Science.gov (United States)

    Kelso, T. S.

    On 2009 February 10, Iridium 33--an operational US communications satellite in low-Earth orbit--was struck and destroyed by Cosmos 2251--a long-defunct Russian communications satellite. This is the first time since the dawn of the Space Age that two satellites have collided in orbit. To better understand the circumstances of this event and the ramifications for avoiding similar events in the future, this paper provides a detailed analysis of the predictions leading up to the collision, using various data sources, and looks in detail at the collision, the evolution of the debris clouds, and the long-term implications for satellite operations. The only publicly available system available to satellite operators for screening for close approaches, SOCRATES, did predict this close approach, but it certainly wasn't the closest approach predicted for the week of February 10. In fact, at the time of the collision, SOCRATES ranked this close approach 152 of the 11,428 within 5 km of any payload. A detailed breakdown is provided to help understand the limitations of screening for close approaches using the two-line orbital element sets. Information is also provided specifically for the Iridium constellation to provide an understanding of how these limitations affect decision making for satellite operators. Post-event analysis using high-accuracy orbital data sources will be presented to show how that information might have been used to prevent this collision, had it been available and used. Analysis of the collision event, along with the distribution of the debris relative to the original orbits, will be presented to help develop an understanding of the geometry of the collision and the near-term evolution of the resulting debris clouds. Additional analysis will be presented to show the long-term evolution of the debris clouds, including orbital lifetimes, and estimate the increased risk for operations conducted by Iridium and other satellite operators in the low-Earth orbit

  5. Tribology of total hip arthroplasty prostheses

    Science.gov (United States)

    Rieker, Claude B.

    2016-01-01

    Articulating components should minimise the generation of wear particles in order to optimize long-term survival of the prosthesis. A good understanding of tribological properties helps the orthopaedic surgeon to choose the most suitable bearing for each individual patient. Conventional and highly cross-linked polyethylene articulating either with metal or ceramic, ceramic-on-ceramic and metal-on-metal are the most commonly used bearing combinations. All combinations of bearing surface have their advantages and disadvantages. An appraisal of the individual patient’s objectives should be part of the assessment of the best bearing surface. Cite this article: Rieker CB. Tribology of total hip arthroplasty prostheses: what an orthopaedic surgeon should know. EFORT Open Rev 2016;1:52-57. DOI: 10.1302/2058-5241.1.000004. PMID:28461928

  6. Low-Stress Iridium Coatings for Thin-Shell X-Ray Telescopes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop and commercialize a new type of low-stress iridium (Ir) X-ray mirror coating technology that can be used for the construction of...

  7. Postimpact examinations of three DOP 4 iridium shells from simulant fuel sphere assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, E.M.; Hecker, S.S.

    1975-12-01

    Three fuel sphere assemblies, with thoria in doped iridium containment shells, were examined after a simulated earth impact from an aborted orbital mission of a multihundred-watt thermoelectric heat source. The extent of deformation of each unit was measured. Damage to the containment shells was minimal in comparison to that in undoped iridium. Metallographic sections from critical areas indicated that superficial grain boundary cracking in weld zones and microscopic cracking in regions of maximum diameter had occurred in addition to local thinning and coining. The improved properties of the doped iridium are attributed to the retention of a small grain size and to an additional fracture resistance over iridium of a comparable grain size, imparted by either a change in grain boundary chemistry or the flow characteristics of the doped material.

  8. Antipseudomonal activity enhancement of luminescent iridium(iii) dipyridylamine complexes under visible blue light.

    Science.gov (United States)

    Sauvageot, E; Elie, M; Gaillard, S; Daniellou, R; Fechter, P; Schalk, I J; Gasser, V; Renaud, J-L; Mislin, G L A

    2017-11-22

    Cyclometallated iridium(iii) dipyridylamine complexes present antibacterial activity against P. aeruginosa, a highly resistant pathogenic bacterium. This activity is increased when the complex is conjugated to biotin, a bacterial nutrient, and a MIC of 4 μM (4 μg mL(-1)) has been observed. The irradiation of P. aeruginosa cultures with blue LED light potentiates the anti-bacterial activities of these iridium(iii) complexes when they are conjugated to a glycoside.

  9. Identification of an iridium(III) complex with anti-bacterial and anti-cancer activity

    OpenAIRE

    Lihua Lu; Li-Juan Liu; Wei-chieh Chao; Hai-Jing Zhong; Modi Wang; Xiu-Ping Chen; Jin-Jian Lu; Ruei-nian Li; Dik-Lung Ma; Chung-Hang Leung

    2015-01-01

    Group 9 transition metal complexes have been widely explored as therapeutic agents due to their unique geometry, their propensity to undergo ligand exchanges with biomolecules and their diverse steric and electronic properties. These metal complexes can offer distinct modes of action in living organisms compared to carbon-based molecules. In this study, we investigated the antimicrobial and anti-proliferative abilities of a series of cyclometallated iridium(III) complexes. The iridium(III) co...

  10. Iridium-Catalyzed Condensation of Primary Amines To Form Secondary Amines

    DEFF Research Database (Denmark)

    Lorentz-Petersen, Linda Luise Reeh; Jensen, Paw; Madsen, Robert

    2009-01-01

    Symmetric secondary amines are readily obtained by heating a neat primary amine with 0.5 mol% of bis(dichloro[eta(5)-pentamethylcyclopentadienyl]iridium). The products are isolated by direct distillation in good yields.......Symmetric secondary amines are readily obtained by heating a neat primary amine with 0.5 mol% of bis(dichloro[eta(5)-pentamethylcyclopentadienyl]iridium). The products are isolated by direct distillation in good yields....

  11. Enantiomeric separation of iridium (III) complexes using HPLC chiral stationary phases based on amylose derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hee Eun; Seo, Na Hyeon; Hyun, Myung Ho [Dept. of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan (Korea, Republic of)

    2016-12-15

    Cyclometalated iridium (III) complexes formed with three identical cyclometalating (C-N) ligands (homoleptic) or formed with two cyclometalating (C-N) ligands and one ancillary (LX) ligand (heteroleptic) have been known as highly phosphorescent materials and, thus, they have been utilized as efficient phosphorescent dopants in organic light emitting diodes (OLEDs) 1–3 or as effective phosphorescent chemosensors. 4–7 Cylometalated iridium (III) complexes are chiral compounds consisting of lambda (Λ, left-handed) and delta (Δ, right-handed) isomers. Racemic cyclometa- lated iridium (III) complexes emit light with no net polarization, but optically active cyclometalated iridium (III) complexes emit circularly polarized light. 8,9 Circularly polarized light can be used in various fields including highly efficient three dimensional electronic devices, photo nic devices for optical data storage, biological assays, and others. 8,9 In order to obtain optically active cylometalated iridium (III) complexes and to determine the enantiomeric composition of optically active cylometalated iridium (III) complexes, liquid chromatogr aphic enantiomer separation method on chiral stationary phases (CSPs) has been used. For example, Okamoto and coworkers first reported the high performance liquid chromatographic (HPLC) direct enantiomeric separation of two homoleptic cylometalated iridium (III) complexes on immobilized amylose tris(3,5- dimethylphenylcarbamate) (Chiralpak IA), coated cellulose tris(3,5-dimethylphenylcarbamate) (Chiralc el OD), and coated cellulose tris(4-methylbenzoate) (Chiralce l OJ). 10 Supercritical fluid chromatography (SFC) was also used by Bernhard and coworkers for the enantiomeric separation of cylometalated iridium (III) complexes on coated amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD-H). 8 However, the general use of the HPLC method for the direct enantiomeric separation of homoleptic.

  12. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes.

    Science.gov (United States)

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-09-30

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1-40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1-40 peptide on the basis of their emission response.

  13. Investigation of spherical and cylindrical catural Iridium targets by photonuclear reaction

    Directory of Open Access Journals (Sweden)

    Korkmaz Mehmet Emin

    2017-01-01

    Full Text Available In this study, natural iridium consisting of Ir-191 and Ir-193 isotopes has been irradiated with 21 MeV photons. The distribution of photons, electrons and neutrons fluxes in the spherical and cylindrical natural iridium target have been calculated using MCNPX 2.7.0 Monte Carlo code. The intensity of the photon fluxes on both targets has been compared to the 106 particle story by showing them as mesh and optimizing the two targets.

  14. Nuclear moments of neutron deficient iridium isotopes from laser spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Verney, D.; Le Blanc, F. [IN2P3 CNRS, Institut de Physique Nucleaire (France); Cabaret, L. [Laboratoire Aime Cotton (France); Crawford, J. [McGill University, Physics Department (Canada); Duong, H.T. [Laboratoire Aime Cotton (France); Genevey, J. [IN2P3 CNRS/UJF, Institut des Sciences Nucleaires (France); Huber, G. [Universitaet Mainz, Institut fuer Physik (Germany); Ibrahim, F. [IN2P3 CNRS/UJF, Institut des Sciences Nucleaires (France); Krieg, M. [Universitaet Mainz, Institut fuer Physik (Germany); Lee, J.K.P. [McGill University, Physics Department (Canada); Lunney, D. [IN2P3 CNRS, CSNSM (France); Obert, J.; Oms, J. [IN2P3 CNRS, Institut de Physique Nucleaire (France); Pinard, J. [Laboratoire Aime Cotton (France); Putaux, J.C.; Roussiere, B.; Sauvage, J. [IN2P3 CNRS, Institut de Physique Nucleaire (France); Sebastian, V. [Universitaet Mainz, Institut fuer Physik (Germany)

    2000-08-15

    Laser spectroscopy measurements have been performed on neutron deficient iridium isotopes. The hyperfine structure and isotope shift of the optical Ir I transition 5d{sup 7}6s{sup 24}F{sub 9/2} {sup {yields}} 5d{sup 7}6s6p {sup 6}F{sub 11/2} at 351.5 nm have been studied for the {sup 182-189}Ir, {sup 186}Ir{sup 1}m and {sup 191,193}Ir isotopes. The nuclear magnetic and quadrupole moments were obtained from the HFS measurements and the changes of the mean square charge radii from the IS measurements. A large mean square charge radius change between {sup 187}Ir and {sup 186}Ir and between {sup 186}Ir{sup 1}m and {sup 186}Ir{sup 1}g has been observed.

  15. Large Deformation Change in Iridium Isotopes from Laser Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    D. Verney; L. Cabaret; J. Crawford; H.T. Duong; J. Genevey; G. Hubert; F. Ibrahim; M. Krieg; F. Le Blanc; J.K.P. Lee; G. Le Scornet; D. Lunney; J. Obert; J. Oms; J. Pinard; J.C. Putaux; B. Roussiere; J. Sauvage; V. Sebastian

    1999-12-31

    Laser spectroscopy measurements have been performed on neutron-deficient iridium isotopes. The hyperfine structure and isotope shift of the optical Ir I transition 5d{sup 7}6s{sup 2} {sup 4}F{sub 9/2} {yields}5d{sup 7}6s6p {sup 6}F{sub 11/2} have been studied for the {sup 182-189}Ir, {sup 186}Ir{sup m} and {sup 191,193}Ir isotopes. The nuclear magnetic and quadrupole moments were obtained from the hyperfine splitting measurements and the changes of the mean square charge radii from the isotope shift measurements. A large deformation change between {sup 187}Ir and {sup 186}Ir and between {sup 186}Ir{sup m} and {sup 186}Ir{sup g} has been observed.

  16. Electron beam welding of iridium heat source capsules

    Science.gov (United States)

    Mustaleski, Thomas M.; Yearwood, J. Cecil; Burgan, Clyde E.; Green, L. A.

    1991-01-01

    The development of the welding procedures for the production of DOP-26 iridium alloy cups for heat source encapsulation is described. All the final assembly welds were made using the electron beam welding process. The welding of the 0.13-mm weld shield required the use of computer controlled X-Y table and a run-off tab. Welding of the frit vent to the cup required that a laser weld be made to hold the frit assembly edges together for the final electron beam weld. Great care is required in tooling design and beam placement to achieve acceptable results. Unsuccessful attempts to use laser beam welding for heat shield butt weld are discussed.

  17. Preparation of platinum/iridium scanning probe microscopy tips

    DEFF Research Database (Denmark)

    Sørensen, Alexis Hammer; Hvid, U.; Mortensen, M.W.

    1999-01-01

    material being etched is platinum/iridium (10%) the influence of the stop phase of the ac current terminating each pulse in the second etching is found to be negligible, while in the case of second etching of tungsten wires it is important to break the pulse in a certain phase to avoid formation of a thick...... of platinum from the wire surface and hereby give rise to "etching" of the wire. In the second etching blunt tips become sharp while tips which are already sharp apparently stay sharp. Therefore, the second etching scheme with pulses separated by pauses is found to be a very important factor...... for the production of sharp tips. After being etched the tips are ready for use in scanning tunneling microscopes, or they may be bent to form integrated tip/cantilever systems in ordinary commercial atomic force microscopes, being applicable as tapping mode tips and as electrostatic force microscopy tips. ©1999...

  18. Synthesis and characterization of low-valence actinide phosphide tellurides and ternary selenium-halide iridium complexes; Synthese und Charakterisierung niedervalenter Actinoidphosphidtelluride und ternaerer Selen-Halogenid-Komplexe des Iridiums

    Energy Technology Data Exchange (ETDEWEB)

    Stolze, Karoline

    2016-04-07

    The thesis on the synthesis and characterization of low-valence actinide phosphide tellurides and ternary selenium-halide iridium complexes includes two parts: a description of the experimental synthesis of UPTe and U2PTe2O and ThPTe and the synthesis of selenium-chloride iridium complexes and selenium-bromide iridium complexes. The characterization included X-ray diffraction and phase studies.

  19. Single step radiolytic synthesis of iridium nanoparticles onto graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, J.V., E-mail: jvrojas@vcu.edu [Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, Richmond, VA 23284-3067301 (United States); Molina Higgins, M.C.; Toro Gonzalez, M. [Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, Richmond, VA 23284-3067301 (United States); Castano, C.E., E-mail: cecastanolond@vcu.edu [Nanomaterials Core Characterization Facility, Chemical and Life Science Engineering Department, Virginia Commonwealth University, 401 West Main Street, Richmond, VA (United States)

    2015-12-01

    Graphical abstract: - Highlights: • Ir nanoparticles were synthesized through a single step gamma irradiation process. • Homogeneously distributed Ir nanoparticles on graphene oxide are ∼2.3 nm in size. • Ir−O bonds evidenced the interaction of the nanoparticles with the support. - Abstract: In this work a new approach to synthesize iridium nanoparticles on reduced graphene oxide is presented. The nanoparticles were directly deposited and grown on the surface of the carbon-based support using a single step reduction method through gamma irradiation. In this process, an aqueous isopropanol solution containing the iridium precursor, graphene oxide, and sodium dodecyl sulfate was initially prepared and sonicated thoroughly to obtain a homogeneous dispersion. The samples were irradiated with gamma rays with energies of 1.17 and 1.33 MeV emitted from the spontaneous decay of the {sup 60}Co irradiator. The interaction of gamma rays with water in the presence of isopropanol generates highly reducing species homogeneously distributed in the solution that can reduce the Ir precursor down to a zero valence state. An absorbed dose of 60 kGy was used, which according to the yield of reducing species is sufficient to reduce the total amount of precursor present in the solution. This novel approach leads to the formation of 2.3 ± 0.5 nm Ir nanoparticles distributed along the surface of the support. The oxygenated functionalities of graphene oxide served as nucleation sites for the formation of Ir nuclei and their subsequent growth. XPS results revealed that the interaction of Ir with the support occurs through Ir−O bonds.

  20. Dynamic High-Temperature Characterization of an Iridium Alloy in Compression at High Strain Rates

    Energy Technology Data Exchange (ETDEWEB)

    Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Experimental Environment Simulation Dept.; Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials Dept.; Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Nuclear Fuel Cycle Technology Dept.; Bignell, John L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Structural and Thermal Analysis Dept.; Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program; George, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program

    2014-06-01

    Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-temperature high-strain-rate performance are needed for understanding high-speed impacts in severe elevated-temperature environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain-rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. Current high-temperature Kolsky compression bar techniques are not capable of obtaining satisfactory high-temperature high-strain-rate stress-strain response of thin iridium specimens investigated in this study. We analyzed the difficulties encountered in high-temperature Kolsky compression bar testing of thin iridium alloy specimens. Appropriate modifications were made to the current high-temperature Kolsky compression bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high strain rates (300 – 10000 s-1) and temperatures (750°C and 1030°C). Uncertainties in such high-temperature high-strain-rate experiments on thin iridium specimens were also analyzed. The compressive stress-strain response of the iridium alloy showed significant sensitivity to strain rate and temperature.

  1. Carbon fibre prostheses and running in amputees: a review.

    Science.gov (United States)

    Nolan, Lee

    2008-01-01

    Amputee sport performance has greatly improved over the past 20 years along with the development of carbon fibre prostheses. As the margins between winning and losing become smaller, athletes increasingly rely on prosthetic limb technology to give them an edge over other competitors and break existing records. Originally, the aim of improving prostheses was to try to increase performance by reducing the functional disadvantage of the prosthetic foot compared to the human foot. However, claims have been made recently that not only have the functional disadvantages been redressed, but today's sprint prostheses may provide a mechanical advantage over the human limb. This review will present what is currently known about carbon fibre prostheses and their effect on the running technique of transtibial amputees.

  2. Running-specific prostheses limit ground-force during sprinting

    National Research Council Canada - National Science Library

    Grabowski, Alena M; McGowan, Craig P; McDermott, William J; Beale, Matthew T; Kram, Rodger; Herr, Hugh M

    2010-01-01

    Running-specific prostheses (RSP) emulate the spring-like behaviour of biological limbs during human running, but little research has examined the mechanical means by which amputees achieve top speeds...

  3. Breast prostheses and connective tissue disease (CTD): myth or reality?

    Science.gov (United States)

    Bassetto, F; Vindigni, V; Scarpa, Carlotta; Doria, A

    2010-06-01

    Since their first appearance, breast prostheses have been criticized as being both responsible for and giving rise to systemic disease. The literature contains many reports on the subject, and theories were controversial from the 1980s to the 2000s. The aim of this review was to gather together the most important studies on breast prostheses and systemic disease, with particular attention to connective tissue disease (CTD), in order to verify any relationship between silicone breast implants and the occurrence of pathologies.

  4. Selective laser sintering technology for customized fabrication of facial prostheses.

    Science.gov (United States)

    Wu, Guofeng; Zhou, Bing; Bi, Yunpeng; Zhao, Yimin

    2008-07-01

    Traditionally, wax or clay sculpted patterns have been used in the development of facial prostheses. New advances in rapid prototyping technologies have demonstrated significant advantages compared to more conventional techniques for fabricating facial prostheses. The use of selective laser sintering technology described in this report is an alternative approach for fabricating a wax pattern for a partial nasal prosthesis. This new approach can generate the wax nasal pattern directly and reduce labor-intensive laboratory procedures.

  5. Morphological characterization of dental prostheses interfaces using optical coherence tomography

    Science.gov (United States)

    Sinescu, Cosmin; Negrutiu, Meda L.; Ionita, Ciprian; Marsavina, Liviu; Negru, Radu; Caplescu, Cristiana; Bradu, Adrian; Topala, Florin; Rominu, Roxana O.; Petrescu, Emanuela; Leretter, Marius; Rominu, Mihai; Podoleanu, Adrian G.

    2010-03-01

    Fixed partial prostheses as integral ceramic, polymers, metal-ceramic or metal-polymers bridges are mainly used in the frontal part of the dental arch (especially the integral bridges). They have to satisfy high stress as well as esthetic requirements. The masticatory stress may induce fractures of the bridges. These may be triggered by initial materials defects or by alterations of the technological process. The fractures of these bridges lead to functional, esthetic and phonetic disturbances which finally render the prosthetic treatment inefficient. Dental interfaces represent one of the most significant aspects in the strength of the dental prostheses under the masticatory load. The purpose of this study is to evaluate the capability of optical coherence tomography (OCT) to characterize the dental prostheses interfaces. The materials used were several fixed partial prostheses integral ceramic, polymers, metal-ceramic and metal-polymers bridges. It is important to produce both C-scans and B-scans of the defects in order to differentiate morphological aspects of the bridge infrastructures. The material defects observed with OCT were investigated with micro-CT in order to prove their existence and positions. In conclusion, it is important to have a non invasive method to investigate dental prostheses interfaces before the insertion of prostheses in the oral cavity.

  6. Characterizing the Mechanical Properties of Running-Specific Prostheses.

    Science.gov (United States)

    Beck, Owen N; Taboga, Paolo; Grabowski, Alena M

    2016-01-01

    The mechanical stiffness of running-specific prostheses likely affects the functional abilities of athletes with leg amputations. However, each prosthetic manufacturer recommends prostheses based on subjective stiffness categories rather than performance based metrics. The actual mechanical stiffness values of running-specific prostheses (i.e. kN/m) are unknown. Consequently, we sought to characterize and disseminate the stiffness values of running-specific prostheses so that researchers, clinicians, and athletes can objectively evaluate prosthetic function. We characterized the stiffness values of 55 running-specific prostheses across various models, stiffness categories, and heights using forces and angles representative of those measured from athletes with transtibial amputations during running. Characterizing prosthetic force-displacement profiles with a 2nd degree polynomial explained 4.4% more of the variance than a linear function (prunning 3 m/s and 6 m/s (10°-25°) compared to neutral (0°) (pRunning-specific prostheses should be tested under the demands of the respective activity in order to derive relevant characterizations of stiffness and function. In all, our results indicate that when athletes with leg amputations alter prosthetic model, height, and/or sagittal plane alignment, their prosthetic stiffness profiles also change; therefore variations in comfort, performance, etc. may be indirectly due to altered stiffness.

  7. Emerging trends in neuro engineering and neural computation

    CERN Document Server

    Lee, Kendall; Garmestani, Hamid; Lim, Chee

    2017-01-01

    This book focuses on neuro-engineering and neural computing, a multi-disciplinary field of research attracting considerable attention from engineers, neuroscientists, microbiologists and material scientists. It explores a range of topics concerning the design and development of innovative neural and brain interfacing technologies, as well as novel information acquisition and processing algorithms to make sense of the acquired data. The book also highlights emerging trends and advances regarding the applications of neuro-engineering in real-world scenarios, such as neural prostheses, diagnosis of neural degenerative diseases, deep brain stimulation, biosensors, real neural network-inspired artificial neural networks (ANNs) and the predictive modeling of information flows in neuronal networks. The book is broadly divided into three main sections including: current trends in technological developments, neural computation techniques to make sense of the neural behavioral data, and application of these technologie...

  8. Platelet thrombosis in cardiac-valve prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Dewanjee, M.K.

    1989-01-01

    The contribution of platelets and clotting factors in thrombosis on cardiovascular prostheses had been quantified with several tracers. Thrombus formation in vivo could be measured semiquantitatively in animal models and patients with indium-111, Technetium-99m labeled platelets, iodine-123, iodine-131 labeled fibrinogen, and In-111 and Tc-99m labeled antibody to the fibrinogen-receptor on the platelet- membrane, or fibrin. The early studies demonstrated that certain platelet-inhibitors, e.g. sulfinpyrazone, aspirin or aspirin- persantine increased platelet survival time with mechanical valves implanted in the baboon model and patients. Thrombus localization by imaging is possible for large thrombus on thrombogenic surface of prosthesis in the acute phase. The majority of thrombus was found in the sewing ring (Dacron) in the acute phase in both the mechanical and tissue valves. The amount of retained thrombus in both mechanical and tissue valves in our one-day study in the dog model was similar (< 1% if injected In-111 platelets = 5 billion platelets). As the fibrous ingrowth covered the sewing ring, the thrombus formation decreased significantly. Only a small amount of thrombus was found on the leaflets at one month in both the dog and calf models. 38 refs., 9 figs., 5 tabs.

  9. Cortical neural prosthetics.

    Science.gov (United States)

    Schwartz, Andrew B

    2004-01-01

    Control of prostheses using cortical signals is based on three elements: chronic microelectrode arrays, extraction algorithms, and prosthetic effectors. Arrays of microelectrodes are permanently implanted in cerebral cortex. These arrays must record populations of single- and multiunit activity indefinitely. Information containing position and velocity correlates of animate movement needs to be extracted continuously in real time from the recorded activity. Prosthetic arms, the current effectors used in this work, need to have the agility and configuration of natural arms. Demonstrations using closed-loop control show that subjects change their neural activity to improve performance with these devices. Adaptive-learning algorithms that capitalize on these improvements show that this technology has the capability of restoring much of the arm movement lost with immobilizing deficits.

  10. Cyclometallated, bis-terdentate iridium complexes as linearly expandable cores for the construction of multimetallic assemblies.

    Science.gov (United States)

    Whittle, Victoria L; Williams, J A Gareth

    2009-05-28

    Cyclometallated iridium complexes comprised of two terdentate cyclometallating ligands, of the form [Ir(Ninsertion markCinsertion markN)(Ninsertion markNinsertion markC)](+), have been explored for the preparation of multimetallic systems by palladium-catalysed cross-coupling reactions. An Ninsertion markNinsertion markC-coordinating ligand carrying a boronate ester group has been prepared and complexed to iridium to give a boronic acid appended complex of this type, . This complex has been subjected to cross-coupling with a bromo-substituted bis-terpyridyl iridium complex to give a dinuclear iridium compound , in which one of the two iridium centres is N(6)-coordinated and the other has an N(4)C(2)-coordination sphere. Meanwhile, a bromo-substituted complex has been coupled with a boronic acid-appended ruthenium complex, to give a dinuclear heterometallic complex that can be activated to a second coupling by in situ bromination, offering access to a linear Ir-Ir-Ru trimetallic assembly . The electrochemical and luminescence properties of these systems are investigated. In the case of and , the behaviour can be rationalised in terms of a supramolecular description: efficient energy transfer occurs from the Ir terminus to the Ru. In contrast, for compound , an excited state with significant bridge character appears to play a key role in determining the emission properties.

  11. Solution-processable phosphorescence based on iridium-cored small molecules with the trifluoromethyl group

    Science.gov (United States)

    Zhang, Wenguan; He, Zhiqun; Wang, Yongsheng; Zhao, Shengmin

    2015-04-01

    A novel cyclometallated ligand 2-(4-(2‧-ethylhexyloxy)phenyl)-5-trifluoromethyl-pyridine (EHO-5CF3-ppy) was synthesized, and two solution-processable iridium complexes bis[2-(4-(2‧-ethylhexyloxy)phenyl)-5-trifluoromethylpyridinto-C3, N] iridium (acetylacetonate) (EHO-5CF3-ppy)2Ir(acac) (5) and bis[2-(4-(2‧-ethylhexyl-oxy)phenyl)-5-trifluoromethylpyridinto-C3, N] iridium (2-picolinic acid) (EHO-5CF3-ppy)2Ir(pic) (6) were afforded. Trifluoromethyl and dendritic ethylhexyloxy group were incorporated into iridium ligands to tune luminescent color, to reduce luminescence quenching and to improve the solution-processable property. Photoluminescent spectra of 5 and 6 in tetrahydrofuran peaked at around 540 and 523 nm. Electrophosphorescent devices were fabricated using 5 and 6 as dopant emitters (2%), which exhibited electroluminescent (EL) peaks at 536 and 524 nm, and current efficiencies of 10.4 and 16.7 cd/A, respectively. With the concentration of iridium complexes increasing to 8%, the main EL peak showed a 4 nm of red shift and a distinct shoulder peak occurred at 583 nm for 5 or 560 nm for 6, respectively. Maximum external quantum efficiencies of the devices at the concentration of 2% and 8% were 2.8% and 4.2% for 5, 4.7% and 4.8% for 6. These indicated that 5 and 6 were efficient solution-processable emitters.

  12. Development of iridium coated x-ray mirrors for astronomical applications

    Science.gov (United States)

    Döhring, Thorsten; Probst, Anne-Catherine; Emmerich, Florian; Stollenwerk, Manfred; Stehlíková, Veronika; Friedrich, Peter; Damm, Christine

    2017-08-01

    Future space-based X-ray observatories need to be very lightweight for launcher mass constraints. Therefore they will use a reduced mirror thickness, which results in the additional requirement of low coating stress to avoid deformation of the initial precisely shaped mirror substrates. Due to their excellent reflection properties iridium coatings are sometimes applied for grazing incidence mirrors in astronomical X-ray telescopes. At Aschaffenburg University of Applied Sciences the coating of thin iridium films by an RF-magnetron sputtering technique is under development. The work is embedded in collaborations with the Max-Planck-Institute for Extraterrestrial Physics in Germany, the Czech Technical University in Prague, the Osservatorio Astronomico di Brera in Italy, the German Leibniz Institute for Solid State and Materials Research in Dresden, and the French Institute Fresnel. Sputtering with different parameters leads to iridium films with different properties. The current work is focused on the microstructure of the iridium coatings to study the influence of the substrate and of the argon gas pressure on the thin film growing process. Correlations between coating density, surface micro-roughness, the crystalline structure of the iridium layers, and the expected reflectivity of the X-ray mirror as well as coating stress effects are presented and discussed. The final goal of the project is to integrate the produced prototype mirrors into an X-ray telescope module. On a longer timescale measurements of the mirror modules optical performance are planned at the X-ray test facility PANTER.

  13. Design, analysis, and fabrication of oxide-coated iridium/rhenium combustion chambers

    Science.gov (United States)

    Jang, Q.; Tuffias, R. H.; Laferla, R.; Ghoniem, N. M.

    1993-01-01

    Iridium-coated rhenium (Ir/Re) combustion chambers provide high temperature, oxidation-resistant operation for radiation-cooled liquid-fueled rocket engines. A 22-N (5-lb(sub f)) chamber has been operated for 15 hours at 2200 C (4000 F) using nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) propellant, with negligible internal erosion. The oxidation resistance of these chambers could be further increased by the addition of refractory oxide coatings, providing longer life and/or operation in more oxidizing and higher temperature environments. The oxide coatings would serve as a thermal and diffusion barrier for the iridium coating, lowering the temperature of the iridium layer while also preventing the ingress of oxygen and egress of iridium oxides. This would serve to slow the failure mechanisms of Ir/Re chambers, namely the diffusion of rhenium to the inner surface and the oxidation of iridium. Such protection could extend chamber lifetimes by tens or perhaps hundreds of hours, and allow chamber operation on stoichiometric or higher mixture ratio oxygen/hydrogen (O2/H2) propellant. Extensive thermomechanical, thermochemical, and mass transport modeling was performed as a key material/structure design tool. Based on the results of these analyses, several 22-N oxide-coated Ir/Re chambers were fabricated and delivered to NASA Lewis Research Center for hot-fire testing.

  14. [Scanning electron microscopy findings in titanium middle ear prostheses].

    Science.gov (United States)

    Schwager, K

    2000-12-01

    Titanium as a biomaterial in ossicular replacement has widely spread within the last couple of years. 23 prostheses (12 PORPs, partial ossicular replacement prostheses and 11 TORPs total ossicular replacement prostheses) removed during revision surgery were studied using scanning electron microscopy. The average implantation time was 8 (range 3-15) months. The specimens were investigated regarding tissue growth, epithelialization, inflammation and cellular signs of rejection. Only few prostheses were totally covered by connective tissue or epithelium due to technical problems in removing the implant and the covering tissue as one specimen. But this offered the possibility to study the interface at the edges where the tissue was torn off. The connective tissue looked unremarkable. Polygonal squamous epithelium was detected on several implants. Respiratory epithelium with ciliated cells and mucus producing goblet cells was seen in two specimens. In cases of cholesteatoma or protrusion the explanted prostheses showed typical rosette-like formation of hornifying squamous epithelium. According to underlying disease a lymphocytic infiltration could be seen. There were no cellular signs of incompatibility noticed neither macrophages nor foreign body giant cells. From these investigations titanium seems to be a favorable biomaterial for ossicular replacement with good acceptance also in an implantation site showing chronic inflammation.

  15. Cyanation of arenes via iridium-catalyzed borylation.

    Science.gov (United States)

    Liskey, Carl W; Liao, Xuebin; Hartwig, John F

    2010-08-25

    We report a method to conduct one-pot meta cyanation of arenes by iridium-catalyzed C-H borylation and copper-mediated cyanation of the resulting arylboronate esters. This process relies on a method to conduct the cyanation of arylboronic esters, and conditions for this new transformation are reported. Conditions for the copper-mediated cyanation of arylboronic acids are also reported. By the resulting sequence of borylation and cyanation, 1,3-disubstituted and 1,2,3-trisubstituted arenes and heteroarenes containing halide, ketone, ester, amide, and protected alcohol functionalities are converted to the corresponding meta-substituted aryl nitriles. The utility of this methodology is demonstrated through the conversion of a protected 2,6-disubstituted phenol to 4-cyano-2,6-dimethylphenol, which is an intermediate in the synthesis of the pharmaceutical etravirine. The utility of the method is further demonstrated by the conversion of 3-chloro-5-methylbenzonitrile, produced through the one-pot C-H borylation and cyanation sequence, to the corresponding 3,5-disubstituted aldehydes, ketones, amides, carboxylic acids, tetrazoles, and benzylamines.

  16. Mossbauer investigation of iridium oxide-hematite nanoparticles

    Science.gov (United States)

    Limongelli, Julia; Sorescu, Monica

    2014-03-01

    Iridium oxide-doped hematite, xIrO2*(1-x) α-Fe2O3 with concentration x=0.1, 0.3, and 0.5, were prepared using ball milling with samples taken at times 0, 2, 4, 8, and 12 hours. The resulting Mössbauer spectra of the nanoparticles systems were parameterized using NORMOS-90. For each concentration, the spectra for 0 hours consisted of one sextet because the substitution of IrO2 into Fe2O3 did not appear until 2 hours ball milling time (BMT). For x=0.1 and 0.3 and BMT 2 hours, the spectra were fit with three sextets. The remaining spectra in x=0.1 and 0.3 were each fit with four sextets. For concentration x=0.5, each spectra from BMT 2-12 hours was fit with four sextets and one quadrupole-split doublet. With increasing initial concentration, the appearance of the quadrupole-split doublet also increased, indicating that the reverse substitution of Fe into IrO2 also occurred. Increased BMT did not influence the profusion of quadrupole-split doublets, however it did affect the number of sextets; as the BMT increased per concentration, the number of sextets also increased. This shows that increasing the initial concentration causes an increase in the amount of IrO2 that is substituted into Fe2O3.

  17. Retroca valvular Replacement of heart valves prostheses

    Directory of Open Access Journals (Sweden)

    Pablo M. A Pomerantzeff

    1987-12-01

    replacement, at our Institution. These patients received a total of 157 prostheses and 4 had their Starr-Edwards valve ball replaced due to ball variance. Six patients were submitted to a third valvular replacement in the mitral position, withouth deaths. Nine patients had a third valvular replacement in the aortic position with 1 death in the immediate postoperative period. Rupture or calcification of the dura mater leaflets were the main reason for the indication of prosthetic replacement. In the mitral position 41 patients presented rupture of the leaflets and 19 showed calcification. In the aortic position 32 bioprostheses underwent rupture and 12, calcification. Bio-prostheses were utilized in the majority of cases of replace the dysfunctioning prostheses. Porcine bioprostheses were implanted in 63 cases and bovine pericardial bioprostheses, in 35. Immediate mortality was 8.3% (12 patients; low cardiac output was the main cause of death. The most frequent immediate complications were low cardiac output, arrhythmias and bleeding. In the preoperative period 90% of the patients were in functional classes III and IV (NYHA. After the replacement, 89% of the aortics and 82% of the mitral were in functional classes I an II.

  18. Adherence of Staphylococcus aureus to Dyneema Purity® Patches and to Clinically Used Cardiovascular Prostheses

    NARCIS (Netherlands)

    Basir, Amir; Grundeman, Paul; Moll, Frans; van Herwaarden, Joost; Pasterkamp, Gerard; Nijland, Reindert

    2016-01-01

    Various materials that are used for vascular and heart valve prostheses carry drawbacks: some require anticoagulant drugs or have moderate durability; others are not suitable for endovascular treatment. These prostheses are associated with bacterial infections. A material potentially suitable for

  19. Implant-retained craniofacial prostheses for facial defects

    Science.gov (United States)

    Federspil, Philipp A.

    2012-01-01

    Craniofacial prostheses, also known as epistheses, are artificial substitutes for facial defects. The breakthrough for rehabilitation of facial defects with implant-retained prostheses came with the development of the modern silicones and bone anchorage. Following the discovery of the osseointegration of titanium in the 1950s, dental implants have been made of titanium in the 1960s. In 1977, the first extraoral titanium implant was inserted in a patient. Later, various solitary extraoral implant systems were developed. Grouped implant systems have also been developed which may be placed more reliably in areas with low bone presentation, as in the nasal and orbital region, or the ideally pneumatised mastoid process. Today, even large facial prostheses may be securely retained. The classical atraumatic surgical technique has remained an unchanged prerequisite for successful implantation of any system. This review outlines the basic principles of osseointegration as well as the main features of extraoral implantology. PMID:22073096

  20. Heterogeneous Catalysis for Water Oxidation by an Iridium Complex Immobilized on Bipyridine-Periodic Mesoporous Organosilica.

    Science.gov (United States)

    Liu, Xiao; Maegawa, Yoshifumi; Goto, Yasutomo; Hara, Kenji; Inagaki, Shinji

    2016-07-04

    Heterogenization of metal-complex catalysts for water oxidation without loss of their catalytic activity is important for the development of devices simulating photosynthesis. In this study, efficient heterogeneous iridium complexes for water oxidation were prepared using bipyridine-bridged periodic mesoporous organosilica (BPy-PMO) as a solid chelating ligand. The BPy-PMO-based iridium catalysts (Ir-BPy-PMO) were prepared by postsynthetic metalation of BPy-PMO and characterized through physicochemical analyses. The Ir-BPy-PMOs showed high catalytic activity for water oxidation. The turnover frequency (TOF) values for Ir-BPy-PMOs were one order of magnitude higher than those of conventional heterogeneous iridium catalysts. The reusability and stability of Ir-BPy-PMO were also examined, and detailed characterization was conducted using powder X-ray diffraction, nitrogen adsorption, (13) C DD MAS NMR spectroscopy, TEM, and XAFS methods. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Identification of an iridium(III) complex with anti-bacterial and anti-cancer activity.

    Science.gov (United States)

    Lu, Lihua; Liu, Li-juan; Chao, Wei-chieh; Zhong, Hai-Jing; Wang, Modi; Chen, Xiu-Ping; Lu, Jin-Jian; Li, Ruei-nian; Ma, Dik-Lung; Leung, Chung-Hang

    2015-09-29

    Group 9 transition metal complexes have been widely explored as therapeutic agents due to their unique geometry, their propensity to undergo ligand exchanges with biomolecules and their diverse steric and electronic properties. These metal complexes can offer distinct modes of action in living organisms compared to carbon-based molecules. In this study, we investigated the antimicrobial and anti-proliferative abilities of a series of cyclometallated iridium(III) complexes. The iridium(III) complex 1 inhibited the growth of S. aureus with MIC and MBC values of 3.60 and 7.19 μM, respectively, indicating its potent bactericidal activity. Moreover, complex 1 also exhibited cytotoxicity against a number of cancer cell lines, with particular potency against ovarian, cervical and melanoma cells. This cyclometallated iridium(III) complex is the first example of a substitutionally-inert, Group 9 organometallic compound utilized as a direct and selective inhibitor of S. aureus.

  2. Polyurethane foam for the extraction of rhodium and its separation from iridium

    Energy Technology Data Exchange (ETDEWEB)

    Al-Bazi, S.J.; Chow, A. (Manitoba Univ., Winnipeg (Canada). Dept. of Chemistry)

    1984-06-01

    The rate of reaction of rhodium with thiocyanate at 90 deg in the presence of lithium chloride or sufficient hydrochloric acid and the subsequent extraction of the metal from hydrochloric acid medium by polyether-type polyurethane foam was investigated. The effect of the chloride salts of different cations decreased in the order Li/sup +/ > Na/sup +/ > K/sup +/ indicating that Rh(SCN)/sub 6//sup 3 -/ is extracted through a simple solvent-extraction mechanism rather than the 'cation-chelation' mechanism. The separation of rhodium and iridium was also examined and the results indicated that in the presence of 5-fold excess of iridium, an average of 95 +- 2% iridium remained in the aqueous phase while an average of 93 +- 2% rhodium was retained by the foam.

  3. ASSESSMENT OF MECHANICAL CHARACTERISTICS OF VASCULAR ENDO-PROSTHESES

    Directory of Open Access Journals (Sweden)

    V. T. Minchenya

    2017-01-01

    Full Text Available Titanium nickelide (nitinol is one of prospective materials for production of special endo-prostheses and other parts and characterized with effect of shape memory. A specific feature of vascular endo-prostheses is the necessity to provide the required rigidity within the temperature interval from 15 to 42 оС. It has been established that titanium nickelide is able to provide the required rigidity but it depends on preliminary heat treatment parameters. So, it is important to determine rela-tions between rigidity of titanium nickelide wire and its preliminary heat treatment parameters for the given temperature in-terval. The aim of the work is to create devices that allow to estimate radial and flexural rigidity of elements made of flexible nitinol wire for manufacturing various medical products, including endo-prostheses of vessels – stents and stent grafts, filter traps. Laboratory digital scales and a specially developed dynamometer based on a cylindrical slotted spring and inductive displacement transducer have been used for measuring a load. The paper proposes possible variants of device designs used to monitor radial rigidity of blood vessel endo-prostheses, as well as to control flexural rigidity of endo-prosthesis elements and wire for their manufacture. The developed devices allow us to evaluate mechanical characteristics of samples under the desired temperature conditions. An introduction of the developed devices has permitted to carry out an operative control on radial and flexural stiffness of intravascular endo-prostheses elements both under conditions of research investigations and during technological process of their manufacture. Currently, the devices are used to specify heat treatment regimes for nitin-ol wire from various manufacturers while manufacturing vascular endo-prostheses

  4. Complications associated with implant-retained removable prostheses.

    Science.gov (United States)

    Vahidi, Farhad; Pinto-Sinai, Gitanjali

    2015-01-01

    Implant-supported removable prostheses improve patients' satisfaction with treatment and quality of life. Improvements in the implant's surface and in attachment elements have made this treatment method very successful. However, some biological and mechanical complications remain. Mechanical complications associated with implant-supported overdentures and implant-supported removable partial dentures are loss of retention of attachment systems, the need to replace retention elements and to reline or repair the resin portion of the denture, and implant fracture. Despite their success, implant-supported removable prostheses require periodic maintenance. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Synthesis of Fluoroalkoxy Substituted Arylboronic Esters by Iridium-Catalyzed Aromatic C–H Borylation

    KAUST Repository

    Batool, Farhat

    2015-08-17

    The preparation of fluoroalkoxy arylboronic esters by iridium-catalyzed aromatic C–H borylation is described. The fluoroalkoxy groups employed include trifluoromethoxy, difluoromethoxy, 1,1,2,2-tetrafluoroethoxy, and 2,2-difluoro-1,3-benzodioxole. The borylation reactions were carried out neat without the use of a glovebox or Schlenk line. The regioselectivities available through the iridium-catalyzed C–H borylation are complementary to those obtained by the electrophilic aromatic substitution reactions of fluoroalkoxy arenes. Fluoroalkoxy arylboronic esters can serve as versatile building blocks.

  6. Development of cyclometallated iridium(III) complexes for light-emitting electrochemical cells

    OpenAIRE

    Housecroft, Catherine E.; Constable, Edwin C.

    2017-01-01

    This chapter gives an overview of the development of cyclometallated iridium(III) complexes for application in light-emitting electrochemical cells (LECs) and highlights the ligand-design strategies employed to enhance device stability, operating efficiency and (critically for LECs in which the ion mobilities are typically low) turn-on times. Typical iridium-containing ionic transtion metal complexes (Ir-iTMCs) belong to the family of [Ir(C^N) 2 (N^N)] + complexes in which H(C^N) is a cyclome...

  7. Influence of iridium on the reactivity of LaFeO3 base perovskites

    DEFF Research Database (Denmark)

    Kindermann, L.; Das, D.; Bahadur, D.

    1998-01-01

    The influence of iridium on the reactivity of powder mixtures made of perovskites and 8 mol% yttria stabilized zirconia (8 YSZ) is reported. Iridium is added to the perovskites of the composition (La0.6M0.4)(z)Fe0.8TM0.2O3-delta (M = Sr, Ca; TM = Mn, Co; z = 0.90, 1.00) via the gaseous phase. Iri...... of the perovskites, thermodynamic activities, Ir(IV)-O bonding, tolerance factor and oxygen migration....

  8. Iridium oxide-carbon hybrid materials as electrodes for neural systems. Electrochemical synthesis and characterization

    OpenAIRE

    Carretero González, Nina Magali

    2014-01-01

    El desarrollo de interfaces neuronales requiere el uso de nuevos materiales electroactivos y biocompatibles, que al aplicar campos eléctricos no causen efectos secundarios que pueden dañar los tejidos o degradar la funcionalidad del electrodo. A día de hoy, existen diferentes materiales electroactivos que se usan como electrodos en el sistema nervioso: oro, platino, carbón, Pt-Ir o IrOx entre otros, siendo este último el que ha mostrado superiores resultados. Una alta eficiencia electroquímic...

  9. Cyclometallated iridium and platinum complexes with noninnocent ligands.

    Science.gov (United States)

    Hirani, Bhavna; Li, Jian; Djurovich, Peter I; Yousufuddin, Muhammed; Oxgaard, Jonas; Persson, Petter; Wilson, Scott R; Bau, Robert; Goddard, William A; Thompson, Mark E

    2007-05-14

    The electronic properties of the cyclometalated (CwedgeN) complexes of iridium and platinum metals with a catechol ligand have been studied experimentally and computationally. The synthesis and characterization of (p-tolylpyridine)Ir(3,5-di-tert-butylcatechol) (abbreviated Ir-sq) and (2,4-diflorophenylpyridine)Pt(3,5-di-tert-butylcatechol) (abbreviated Pt-sq) are reported along with their structural, spectral, and electrochemical properties. Reaction of the 3,5-di-tert-butylcatechol (DTBCat) ligand with the prepared cyclometalated metal complex was carried out in air in the presence of a base. The resulting complexes are air stable and are paramagnetic with the unpaired electron residing mainly on the catechol ligand. The bond lengths obtained from X-ray structure analysis and the theoretical results suggest the semiquinone form of the catechol ligand. Low-energy, intense (approximately 10(3) M-1 cm-1) transitions are observed in the visible to near-infrared region (600-700 nm) of the absorption spectra of the metal complexes. Electrochemically, the complexes exhibit a reversible reduction of the semiquinone form to the catechol form of the ligand and an irreversible oxidation to the unstable quinone form of the ligand. The noninnocent catechol ligand plays a significant role in the electronic properties of the metal complexes. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations on the two open-shell molecules provide the ground-state and excited-state energies of the molecular orbitals involved in the observed low-energy transitions. The spin density in the two complexes resides mainly on the catechol ligand. The intense transition arises from excitation of the beta electron from a HOMO-n (n = 1 or 2 here) to the LUMO, rather than from the excitation of the unpaired alpha electron.

  10. High Strain Rate Testing of Welded DOP-26 Iridium

    Energy Technology Data Exchange (ETDEWEB)

    Schneibel, J. H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Miller, R. G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Carmichael, C. A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fox, E. E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); George, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    The iridium alloy DOP-26 is used to produce Clad Vent Set cups that protect the radioactive fuel in radioisotope thermoelectric generators (RTGs) which provide electric power for spacecraft and rovers. In a previous study, the tensile properties of DOP-26 were measured over a wide range of strain rates and temperatures and reported in ORNL/TM-2007/81. While that study established the properties of the base material, the fabrication of the heat sources requires welding, and the mechanical properties of welded DOP-26 have not been extensively characterized in the past. Therefore, this study was undertaken to determine the mechanical properties of DOP-26 specimens containing a transverse weld in the center of their gage sections. Tensile tests were performed at room temperature, 750, 900, and 1090°C and engineering strain rates of 1×10-3 and 10 s-1. Room temperature testing was performed in air, while testing at elevated temperatures was performed in a vacuum better than 1×10-4 Torr. The welded specimens had a significantly higher yield stress, by up to a factor of ~2, than the non-welded base material. The yield stress did not depend on the strain rate except at 1090°C, where it was slightly higher for the faster strain rate. The ultimate tensile stress, on the other hand, was significantly higher for the faster strain rate at temperatures of 750°C and above. At 750°C and above, the specimens deformed at 1×10-3 s-1 showed pronounced necking resulting sometimes in perfect chisel-edge fracture. The specimens deformed at 10 s-1 exhibited this fracture behavior only at the highest test temperature, 1090°C. Fracture occurred usually in the fusion zone of the weld and was, in most cases, primarily intergranular.

  11. Cobalt release and complications resulting from the use of dental prostheses

    DEFF Research Database (Denmark)

    Al-Imam, Hiba; Benetti, Ana R.; Özhayat, Esben B.

    2016-01-01

    of the functional prostheses released cobalt, whereas this was observed in 24 of 32 non-functional prostheses. None of the patients had contact allergy to cobalt. Of the 66 patients, 11 showed signs of inflammation of the oral mucosa, 2 had oral candidiasis, 16 had ill-fitting prostheses, and all had insufficient...... oral hygiene. CONCLUSIONS: Dental prostheses released cobalt during the fabrication stages, but not 1-5 years after insertion. No allergic reactions were observed. Signs of inflammation were related to candidiasis, insufficient oral hygiene, and ill-fitting prostheses....

  12. Magnetic resonance imaging of breast prostheses | Corr | SA ...

    African Journals Online (AJOL)

    Breast MR imaging is the most accurate imaging investigation to detect breast prosthesis rupture. Rupture is common in older prostheses (> 10 years post implantation) and is often asymptomatic. The radiological signs of rupture are due to collapse of the elastomer shell which is eneveloped by silicone gel and when the ...

  13. Composition and architecture of biofilms on used voice prostheses

    NARCIS (Netherlands)

    Buijssen, Kevin J. D. A.; van der Laan, Bernard F. A. M.; van der Mei, Henny C.; Atema-Smit, Jelly; van den Huijssen, Pauline; Busscher, Henk J.; Harmsen, Hermie J. M.

    Background Biofilms on medical devices are a frequent reason for failure of the device. Voice prostheses in laryngectomized patients deteriorate within 3 to 4 months due to adhering biofilms, impeding proper functioning. Recently, we showed that these biofilms are dominated by Candida and

  14. Using Noncontingent Reinforcement to Increase Compliance with Wearing Prescription Prostheses

    Science.gov (United States)

    Richling, Sarah M.; Rapp, John T.; Carroll, Regina A.; Smith, Jeanette N.; Nystedt, Aaron; Siewert, Brook

    2011-01-01

    We evaluated the effects of noncontingent reinforcement (NCR) on compliance with wearing foot orthotics and a hearing aid with 2 individuals. Results showed that NCR increased the participants' compliance with wearing prescription prostheses to 100% after just a few 5-min sessions, and the behavior change was maintained during lengthier sessions.…

  15. Evaluation of pneumatic cylinder actuators for hand prostheses

    NARCIS (Netherlands)

    Peerdeman, B.; Smit, Gerwin; Stramigioli, Stefano; Plettenburg, Dick; Misra, Sarthak

    2012-01-01

    DC motors are currently the preferred actuation method for externally powered hand prostheses. However, they are often heavy and large, which limits the number of actuators that can be integrated into the prosthesis. Alternative actuation methods are being researched, but have not yet found wide

  16. [Complications within two years after revision of total hip prostheses

    NARCIS (Netherlands)

    Witjes, Suzanne; Schrier, J.C.; Gardeniers, J.W.M.; Schreurs, B.W.

    2007-01-01

    OBJECTIVE: To describe the complications within 2 years after revision of failed total hip prostheses. DESIGN: Descriptive. METHOD: Using prospective registration, data were collected on the complications that had occurred in patients who had undergone hip revision in 2002 and 2003 on the

  17. A study of tracheal prostheses produced by composite laminate ...

    African Journals Online (AJOL)

    Natural tracheal may become defective due to, among other things, abnormal narrowing or fistulas, direct or indirect result of accidents or narrowing caused by inflammation. In an acute situation when direct anastomoses (cross-connection) cannot be made, tracheal prostheses are often needed to bridge the defects.

  18. Optical coherence tomography and confocal microscopy investigations of dental prostheses

    Science.gov (United States)

    Negrutiu, Meda L.; Sinescu, Cosmin; Hughes, Michael; Bradu, Adrian; Rominu, Mihai; Todea, Carmen; Dobre, George; Podoleanu, Adrian

    2008-09-01

    Dental prostheses are very complex systems, heterogenous in structure, made up from various materials, with different physical properties. An essential question mark is on the physical, chemical and mechanical compatibility between these materials. They have to satisfy high stress requirements as well as esthetic challenges. The masticatory stress may induce fractures of the prostheses, which may be triggered by initial materials defects or by alterations of the technological process. The failures of dental prostheses lead to functional, esthetic and phonetic disturbances which finally render the prosthetic treatment inefficient. The purpose of this study is to evaluate the capability of en-face optical coherence tomography as a possible non-invasive high resolution method in supplying the necessary information on the material defects of dental prostheses and microleakage at prosthetic interfaces. C-scan and B-scan OCT images as well as confocal images are acquired from a large range of samples. Gaps between the dental interfaces and material defects are clearly exposed. We conclude that OCT can successfully be used as a noninvasive analysis method.

  19. Critiquing the Computer-Aided Design of Dental Prostheses.

    Science.gov (United States)

    Fitzpatrick, F. J.; And Others

    This paper describes RaPiD, a computer-aided assistant for the design of dental prostheses called removable partial dentures. The user manipulates icons directly to indicate the desired design solution to a given clinical situation. A developing design is represented as a logic database of components in a design; expert rules are applied as…

  20. Estimation of the knee joint angle from surface electromyographic signals for active control of leg prostheses.

    Science.gov (United States)

    Delis, Alberto L; Carvalho, João L A; da Rocha, Adson F; Ferreira, Renan U; Rodrigues, Suélia S; Borges, Geovany A

    2009-09-01

    The surface electromyographic (SEMG) signal is very convenient for prosthesis control because it is non-invasively acquired and intrinsically related to the user's intention. This work presents a feature extraction and pattern classification algorithm for estimation of the intended knee joint angle from SEMG signals acquired using two sets of electrodes placed on the upper leg. The proposed algorithm uses a combination of time-domain and frequency-domain approaches for feature extraction (signal amplitude histogram and auto-regressive coefficients, respectively), a self-organizing map for feature projection and a Levenberg-Marquardt multi-layer perceptron neural network for pattern classification. The new algorithm was quantitatively compared with the method proposed by Wang et al (2006 Med. Biol. Eng. Comput. 44 865-72), which uses wavelet packet feature extraction, principal component analysis and a multi-layer perceptron neural classifier. The proposed method provided lower error-to-signal percentage and peak error amplitudes, higher correlation and fewer error events. The algorithm presented in this work may be useful as part of a myoelectric controller for active leg prostheses designed for transfemoral amputees.

  1. AICRG, Part IV: Patient satisfaction reported for Ankylos implant prostheses.

    Science.gov (United States)

    Morris, Harold F; Ochi, Shigeru; Rodriguez, Arthur; Lambert, Paul M

    2004-01-01

    Although many maxillary dentures exhibit sufficient retention and stability for patients to adapt well to them, mandibular dentures present a major challenge. The introduction of the endosseous dental implant provided the opportunity for the patient to have esthetic replacements (implant prostheses) that were retentive and stable for all missing natural teeth. This paper reports on the satisfaction of over 470 patients with implant prostheses fabricated using a new and innovative implant design (Ankylos, Dentsply-Friadent, Mannheim, Germany). A total of 1500 Ankylos implants were placed, restored, and followed for 3 to 5 years. Patients were asked to respond to a series of questions related to their satisfaction with their new replacements for missing natural teeth. A total of 95.6% of the patients rated chewing ability with Ankylos prosthesis as excellent to good; 92.2% indicated a significant improvement in their ability to chew; 92.6% reported overall clinical function much better than conventional dentures; 99.1% indicated that speech had improved or was not changed; 96.3% indicated hot and cold foods tasted better; 98.8% indicated no pain or discomfort during clinical function; 99.4% liked their new implant prosthesis; 98.0% would seek implant-prostheses treatment again, if necessary; 99.1% would recommend implant prostheses to friends and relatives; and 98.8% indicated the advantages of Ankylos prostheses far exceeded any disadvantages that may exist. Patients indicated that they (1) were highly satisfied with the final results of the replacements for their natural teeth that were retained or supported by this new implant design, (2) would not hesitate to recommend this form of treatment to their friends and relatives, and (3) would not hesitate to seek the same treatment again if necessary in the future.

  2. Hyperbranched red light-emitting phosphorescent polymers based on iridium complex as the core

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Ting; Yu, Lei; Yang, Yong; Li, Yanhu; Tao, Yun [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China); Hou, Qiong [School of Chemistry & Environment, South China Normal University, Guangzhou 510006 (China); Ying, Lei, E-mail: msleiying@scut.edu.cn [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China); Yang, Wei; Wu, Hongbin; Cao, Yong [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China)

    2015-11-15

    A series of hyperbranched π-conjugated light-emitting polymers containing an iridium complex as the branched core unit and polyfluorene or poly(fluorene-alt-carbazole) as the branched segments were synthesized via a palladium catalyzed Suzuki polymerization. Apparent Förster energy transfer in the photoluminescent spectra as thin films was observed, while no discernible characteristic absorbance and photoluminescence of the iridium complex can be realized in dilute solutions. Copolymers based on poly(fluorene-alt-carbazole) as the branched segments demonstrated enhanced highest occupied molecular orbital energy levels relative to those based on polyfluorene. The electroluminescent spectra of these copolymers exclusively showed the characteristic emission of the iridium complex, with corresponding CIE coordinates of (0.67±0.01, 0.31). All devices exhibited relatively slow roll-off of efficiency, and the best device performance with the maximum luminous efficiency of 5.33 cd A{sup −1} was attained by using PFCzTiqIr3 as the emissive layer. These results indicated that the hyperbranched conjugated architectures can be a promising molecular design strategy for efficient electrophosphorescent light-emitting polymers. - Highlights: • Hyperbranched red light-emitting polymers are synthesized. • Red light-emitting iridium complex is used as the branched core unit. • Hyperbranched polymers based on PFCz exhibit higher luminescence. • The highest luminous efficiency of 5.33 cd A{sup −1} is attained.

  3. Iridium(III) and Rhodium(III) compounds of dipyridyl-N-alkylimine ...

    Indian Academy of Sciences (India)

    compounds of this classes exhibited anticancer12 14 and. DNA intercalative properties.15,16 Owing to their wide applications, synthesis of iridium(III) and rhodium(III) complexes bearing η5-C5Me5 fragment have been a sub- ject of interest over the past years.16 19 Numerous stud- ies have been reported for their synthesis ...

  4. Synthesis and Luminescence Properties of Iridium(III Azide- and Triazole-Bisterpyridine Complexes

    Directory of Open Access Journals (Sweden)

    Timothy W. Schmidt

    2013-07-01

    Full Text Available We describe here the synthesis of azide-functionalised iridium(III bisterpyridines using the “chemistry on the complex” strategy. The resulting azide-complexes are then used in the copper(I-catalysed azide-alkyne Huisgen 1,3-dipolar cycloaddition “click chemistry” reaction to from the corresponding triazole-functionalised iridium(III bisterpyridines. The photophysical characteristics, including lifetimes, of these compounds were also investigated. Interestingly, oxygen appears to have very little effect on the lifetime of these complexes in aqueous solutions. Unexpectedly, sodium ascorbate acid appears to quench the luminescence of triazole-functionalised iridium(III bisterpyridines, but this effect can be reversed by the addition of copper(II sulfate, which is known to oxidize ascorbate under aerobic conditions. The results demonstrate that iridium(III bisterpyridines can be functionalized for use in “click chemistry” facilitating the use of these photophysically interesting complexes in the modification of polymers or surfaces, to highlight just two possible applications.

  5. Atomic structure of self-organizing iridium induced nanowires on Ge(001)

    NARCIS (Netherlands)

    Kabanov, Nikolai; Heimbuch, Rene; Zandvliet, Henricus J.W.; Saletsky, A.M.; Klavsyuk, A.L.

    2017-01-01

    The atomic structure of self-organizing iridium (Ir) induced nanowires on Ge(001) is studied by density functional theory (DFT) calculations and variable-temperature scanning tunneling microscopy. The Ir induced nanowires are aligned in a direction perpendicular to the Ge(001) substrate dimer rows,

  6. Chemiluminescence of a cyclometallated iridium(III) complex and its application in the detection of cysteine.

    Science.gov (United States)

    Dong, Yong Ping; Shi, Ming Juan; Tong, Bi Hai; Zhang, Qian Feng

    2012-01-01

    Chemiluminescence (CL) of a cyclometallated iridium (III) complex {tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium(III)} in the presence of potassium permanganate and oxalic acid is reported for the first time. Cysteine exhibits sufficient enhancing effect on the CL generated from the cyclometallated iridium(III) complex, which make it possible for the sensitive detection of cysteine using a flow-injection-chemiluminescence (FI-CL) method. The optimum conditions for the chemiluminescence emission were investigated. Under the optimal condition, the linear range for the determination of cysteine was 1.0 × 10(-9) -5.0 × 10(-6)  mol/L with a detection limit of 6.9 × 10(-10)  mol/L. A relative standard deviation of 1.6% was obtained for eight replicate determinations. The mechanisms of CL are proposed and the emitting species was identified as the metal-to-ligand charge-transfer (MLCT) excited states of the iridium complex. Copyright © 2011 John Wiley & Sons, Ltd.

  7. A highly active cyclometallated iridium catalyst for the hydrogenation of imines.

    Science.gov (United States)

    Villa-Marcos, Barbara; Tang, Weijun; Wu, Xiaofeng; Xiao, Jianliang

    2013-09-25

    A cyclometallated iridium complex containing an imino ligand has been shown to catalyse the hydrogenation of imines. The catalyst is highly active and selective for imino bonds, with a wide variety of imines being hydrogenated in less than 1 hour at a substrate/catalyst (S/C) ratio of 2000 at 20 bar H2 pressure and 75 °C.

  8. A luminescent bimetallic iridium(iii) complex for ratiometric tracking intracellular viscosity.

    Science.gov (United States)

    Liu, Fengyu; Wen, Jia; Chen, Su-Shing; Sun, Shiguo

    2018-02-01

    A luminescent bimetallic iridium probe C10 was developed through a long soft carbon chain linkage to achieve ratiometric detection of viscosity. C10 features high sensitivity and selectivity for viscosity. More importantly, C10 is living cell permeable and can be employed to distinguish cancer cells from normal cells and track viscosity changes during MCF-7 cell apoptosis.

  9. Asymmetric synthesis of N,O-heterocycles via enantioselective iridium-catalysed intramolecular allylic amidation

    NARCIS (Netherlands)

    Zhao, Depeng; Fananas-Mastral, Martin; Chang, Mu-Chieh; Otten, Edwin; Feringa, Ben L.

    2014-01-01

    Chiral N,O-heterocycles were synthesized in high yields and excellent enantioselectivity up to 97% ee via iridium-catalysed intramolecular allylic substitution with nucleophilic attack by the amide oxygen atom. The resulting benzoxazine derivatives were further transformed into challenging chiral

  10. Single orientation graphene synthesized on iridium thin films grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Dangwal Pandey, A., E-mail: arti.pandey@desy.de; Grånäs, E.; Shayduk, R.; Noei, H.; Vonk, V. [Deutsches Elektronen-Synchrotron (DESY), D-22607 Hamburg (Germany); Krausert, K.; Franz, D.; Müller, P.; Keller, T. F.; Stierle, A., E-mail: andreas.stierle@desy.de [Deutsches Elektronen-Synchrotron (DESY), D-22607 Hamburg (Germany); Fachbereich Physik, Universität Hamburg, D-22607 Hamburg (Germany)

    2016-08-21

    Heteroepitaxial iridium thin films were deposited on (0001) sapphire substrates by means of molecular beam epitaxy, and subsequently, one monolayer of graphene was synthesized by chemical vapor deposition. The influence of the growth parameters on the quality of the Ir films, as well as of graphene, was investigated systematically by means of low energy electron diffraction, x-ray reflectivity, x-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and atomic force microscopy. Our study reveals (111) oriented iridium films with high crystalline quality and extremely low surface roughness, on which the formation of large-area epitaxial graphene is achieved. The presence of defects, like dislocations, twins, and 30° rotated domains in the iridium films is also discussed. The coverage of graphene was found to be influenced by the presence of 30° rotated domains in the Ir films. Low iridium deposition rates suppress these rotated domains and an almost complete coverage of graphene was obtained. This synthesis route yields inexpensive, air-stable, and large-area graphene with a well-defined orientation, making it accessible to a wider community of researchers for numerous experiments or applications, including those which use destructive analysis techniques or irreversible processes. Moreover, this approach can be used to tune the structural quality of graphene, allowing a systematic study of the influence of defects in various processes like intercalation below graphene.

  11. Iridium-decorated multiwall carbon nanotubes and its catalytic activity with Shell 405 in hydrazine decomposition

    Science.gov (United States)

    Prasad, V.; Vasanthkumar, M. S.

    2015-10-01

    Iridium-functionalized multiwalled carbon nanotubes (Ir-MWNT) are the future catalyst support material for hydrazine fuel decomposition. The present work demonstrates decoration of iridium particle on iron-encapsulated multiwalled carbon nanotubes (MWNT) by wet impregnation method in the absence of any stabilizer. Electron microscopy studies reveal the coated iridium particle size in the range of 5-10 nm. Elemental analysis by energy dispersive X-ray diffraction confirms 21 wt% of Ir coated over MWNT. X-ray photoelectron spectroscopy (XPS) shows 4f5/2 and 4f7/2 lines of iridium and confirms the metallic nature. The catalytic activity of Ir-MWNT/Shell 405 combination is performed in 1 N hydrazine micro-thrusters. The thruster performance shows increase in chamber pressure and decrease in chamber temperature when compared to Shell 405 alone. This enhanced performance is due to high thermal conducting nature of MWNTs and the presence of Ir active sites over MWNTs.

  12. A pH Sensor Based on a Stainless Steel Electrode Electrodeposited with Iridium Oxide

    Science.gov (United States)

    Martinez, C. C. M.; Madrid, R. E.; Felice, C. J.

    2009-01-01

    A simple procedure to make an iridium oxide (IrO[subscript 2]) electrodeposited pH sensor, that can be used in a chemical, biomedical, or materials laboratory, is presented here. Some exercises, based on this sensor, that can be used to teach important concepts in the field of biomedical, biochemical, tissue, or materials engineering, are also…

  13. Analysis of using EMG and mechanical sensors to enhance intent recognition in powered lower limb prostheses.

    Science.gov (United States)

    Young, A J; Kuiken, T A; Hargrove, L J

    2014-10-01

    The purpose of this study was to determine the contribution of electromyography (EMG) data, in combination with a diverse array of mechanical sensors, to locomotion mode intent recognition in transfemoral amputees using powered prostheses. Additionally, we determined the effect of adding time history information using a dynamic Bayesian network (DBN) for both the mechanical and EMG sensors. EMG signals from the residual limbs of amputees have been proposed to enhance pattern recognition-based intent recognition systems for powered lower limb prostheses, but mechanical sensors on the prosthesis-such as inertial measurement units, position and velocity sensors, and load cells-may be just as useful. EMG and mechanical sensor data were collected from 8 transfemoral amputees using a powered knee/ankle prosthesis over basic locomotion modes such as walking, slopes and stairs. An offline study was conducted to determine the benefit of different sensor sets for predicting intent. EMG information was not as accurate alone as mechanical sensor information (p EMG in combination with the mechanical sensor data did significantly reduce intent recognition errors (p EMG and mechanical sensors. Combining EMG and mechanical sensor data with sensor time history reduced the average transitional error from 18.4% to 12.2% and the average steady-state error from 3.8% to 1.0% when classifying level-ground walking, ramps, and stairs in eight transfemoral amputee subjects. These results suggest that a neural interface in combination with time history methods for locomotion mode classification can enhance intent recognition performance; this strategy should be considered for future real-time experiments.

  14. Dynamics of a cis-dihydrogen/hydride complex of iridium.

    Science.gov (United States)

    Nanishankar, H V; Dutta, Saikat; Nethaji, Munirathinam; Jagirdar, Balaji R

    2005-09-05

    Insertion of CS2 into one of the Ir-H bonds of [Ir(H)5(PCy3)2] takes place to afford the dihydrido dithioformate complex cis-[Ir(H)2(eta2-S2CH)(PCy3)2] accompanied by the elimination of H2. Protonation of the dithioformate complex using HBF4.Et2O gives cis-[Ir(H)(eta2-H2)(eta2-S2CH)(PCy3)2][BF4] wherein the H atom undergoes site exchange between the dihydrogen and the hydride ligands. The dynamics was found to be so extremely rapid with respect to the NMR time scale that the barrier to exchange could not be measured. Partial deuteration of the hydride ligands resulted in a J(H,D) of 6.5 and 7.7 Hz for the H2D and the HD2 isotopomers of cis-[Ir(H)(eta2-H2)(eta2-S2CH)(PCy3)2][BF4], respectively. The H-H distance (d(HH)) for this complex has been calculated to be 1.05 A, which can be categorized under the class of elongated dihydrogen complexes. The cis-[Ir(H)(eta2-H2)(eta2-S2CH)(PCy3)2][BF4] complex undergoes substitution of the bound H2 moiety with CH(3)CN and CO resulting in new hydride derivatives, cis-[Ir(H)(L)(eta2-S2CH)(PCy3)2][BF4] (L = CH3CN, CO). Reaction of cis-[Ir(H)2(eta2-S2CH)(PCy3)2] with electrophilic reagents such as MeOTf and Me3SiOTf afforded a new hydride aquo complex cis-[Ir(H)(H2O)(eta2-S2CH)(PCy3)2][OTf] via the elimination of CH4 and Me3SiH, respectively, followed by the binding of a water molecule (present in trace quantities in the solvent) to the iridium center. The X-ray crystal structures of cis-[Ir(H)2(eta2-S2CH)(PCy3)2] and cis-[Ir(H)(H2O)(eta2-S2CH)(PCy3)2][OTf] have been determined.

  15. Outcomes of Constrained Prostheses in Primary and Revision TKR

    Science.gov (United States)

    Parkinson, Ben; Lorimer, Michelle; Lewis, Peter

    2017-01-01

    Introduction: The decision to use varus/valgus constrained or hinge knee prostheses in complex Total Knee Replacement (TKR) cases is difficult. There are few publications that compare survival rates, to aid this decision-making. This study compares the survival rates of unlinked fully constrained and hinge constrained prostheses in the primary and revision settings. Methods: Data from the AOANJRR to 31st of December 2013 was analysed to determine the survival rate of unlinked and hinge constrained TKR in the primary and revision settings (excluding the diagnosis of tumour and infection). Only first-time revisions of a known primary TKR were included in the revision analysis. Kaplan-Meier estimates of survivorship were calculated for the two categories of constraint and were matched for age and diagnosis in both primary and revision TKR situations. Hazard ratios using the Cox proportional-hazards model were used. The survivorship of individual prosthesis models was determined. Results: There were 3237 prostheses implanted during the study period that met the inclusion criteria. Of these, 1896 were for primary TKR and 1341 for revision TKR. There were 1349 unlinked fully constrained and 547 hinge prostheses for primary TKR and 991 unlinked fully constrained and 350 hinge prostheses for revision TKR. In both the primary and revision settings when matched by age, there was no difference in rates of revision for either level of constraint. When matched by indication in the primary setting, there was no difference in the rates of revision for either level of constraint. The rate of revision for both categories of constrained prosthesis was significantly higher in younger patients <55 years of age (p < 0.05). There were no differences in survival rates of individual models of constrained TKR. Conclusions: The survival rates of unlinked constrained and hinge knee prostheses are similar when matched by age or diagnosis. In complex TKR instability cases, surgeons should feel

  16. Cemented, cementless, and hybrid prostheses for total hip replacement: cost effectiveness analysis.

    Science.gov (United States)

    Pennington, Mark; Grieve, Richard; Sekhon, Jasjeet S; Gregg, Paul; Black, Nick; van der Meulen, Jan H

    2013-02-27

    To compare the cost effectiveness of the three most commonly chosen types of prosthesis for total hip replacement. Lifetime cost effectiveness model with parameters estimated from individual patient data obtained from three large national databases. English National Health Service. Adults aged 55 to 84 undergoing primary total hip replacement for osteoarthritis. Total hip replacement using either cemented, cementless, or hybrid prostheses. Cost (£), quality of life (EQ-5D-3L, where 0 represents death and 1 perfect health), quality adjusted life years (QALYs), incremental cost effectiveness ratios, and the probability that each prosthesis type is the most cost effective at alternative thresholds of willingness to pay for a QALY gain. Lifetime costs were generally lowest with cemented prostheses, and postoperative quality of life and lifetime QALYs were highest with hybrid prostheses. For example, in women aged 70 mean costs were £6900 ($11 000; €8200) for cemented prostheses, £7800 for cementless prostheses, and £7500 for hybrid prostheses; mean postoperative EQ-5D scores were 0.78, 0.80, and 0.81, and the corresponding lifetime QALYs were 9.0, 9.2, and 9.3 years. The incremental cost per QALY for hybrid compared with cemented prostheses was £2500. If the threshold willingness to pay for a QALY gain exceeded £10 000, the probability that hybrid prostheses were most cost effective was about 70%. Hybrid prostheses have the highest probability of being the most cost effective in all subgroups, except in women aged 80, where cemented prostheses were most cost effective. Cemented prostheses were the least costly type for total hip replacement, but for most patient groups hybrid prostheses were the most cost effective. Cementless prostheses did not provide sufficient improvement in health outcomes to justify their additional costs.

  17. FEATURE EXTRACTION FOR EMG BASED PROSTHESES CONTROL

    Directory of Open Access Journals (Sweden)

    R. Aishwarya

    2013-01-01

    Full Text Available The control of prosthetic limb would be more effective if it is based on Surface Electromyogram (SEMG signals from remnant muscles. The analysis of SEMG signals depend on a number of factors, such as amplitude as well as time- and frequency-domain properties. Time series analysis using Auto Regressive (AR model and Mean frequency which is tolerant to white Gaussian noise are used as feature extraction techniques. EMG Histogram is used as another feature vector that was seen to give more distinct classification. The work was done with SEMG dataset obtained from the NINAPRO DATABASE, a resource for bio robotics community. Eight classes of hand movements hand open, hand close, Wrist extension, Wrist flexion, Pointing index, Ulnar deviation, Thumbs up, Thumb opposite to little finger are taken into consideration and feature vectors are extracted. The feature vectors can be given to an artificial neural network for further classification in controlling the prosthetic arm which is not dealt in this paper.

  18. Two Fungal Infections of Inflatable Penile Prostheses in Diabetics

    Directory of Open Access Journals (Sweden)

    Brittney H. Cotta, MD

    2015-12-01

    Conclusions: This report supports the emerging literature that the flora of IPP infections is changing. We suggest considering adding antifungal agents to antibiotic coatings, dips, or washout solutions at the time of penile prosthesis surgery in diabetic patients. Cotta BH, Butcher M, Welliver C, McVary K, and Köhler T. Two fungal infections of inflatable penile prostheses in diabetics. Sex Med 2015;3:339–342.

  19. Tissue Engineered Testicular Prostheses With Prolonged Testosterone Release

    Science.gov (United States)

    2008-12-01

    in infertile men. Fertil. Steril ., Epub ahead of print. Marshall, S., 1986: Potential problems with testicular prostheses. Urology, 28, 388-390...strengths to maintain structural integrity. The polymers were sterilized in ethylene oxide and placed under sterile conditions until cell delivery...washed in Povidone-iodine 10% solution, and dissected into 2 to 3 mm tissue fragments. Chondrocytes were isolated under sterile conditions using a

  20. Cantilever Resin-Bonded Fixed Dental Prostheses Show Clinical Success

    Science.gov (United States)

    2018-03-26

    FROM: 59 MDW/SGVU SUBJECT: Professional Presentation Approval 16 MAR 2017 1. Your paper, entitled Cantilever Resin-Bonded Fixed Dental Prosthesis ...Show Clinical Success presented at/published to Texas Dental Journal in accordance with MDWI 41- 108, has been approved and assigned local file #17147...resin-bonded lixed dental prostheses show clinical success 7. FUNDING RECEIVED FOR THIS STUDY? 0 YES [gj NO FUNDING SOURCE: 8. DO YOU NEED FUNDING

  1. Changes in photon dose distributions due to breast prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Klein, E.E. (Washington Univ. School of Medicine, St. Louis, MO (United States)); Kuske, R.R. (Ochsner Clinic, New Orleans, LA (United States))

    1993-02-15

    Subcutaneous prosthetic implants have been routinely used for cosmetic augmentation and for tissue replacement following mastectomy over the last 15 years. The implants come in many forms as the gel filler material and surrounding shell material(s) vary significantly. This study uses a thin window parallel-plate chamber and thermoluminescent dosimeters to quantify any dosimetric changes to surrounding breast tissue due to the presence of the prosthesis. A mammographic phantom was compared to four commercial prostheses, namely two silicon gel fillers within two different shells (silicon or silicon/polyurethane), a tri-glyceride within silicon and a bio-oncotic gel within silicon and a bio-oncotic gel within silicon/polyurethane. The latter two implants were designed with a low-Z fill for diagnostic imaging benefits. Ion chamber results indicate no significant alteration of depth doses away from the implant with only minor canceling (parallel opposed) interface perturbations for all implants. In addition the physical changes to the irradiated prostheses were quantified by tonometry testing and qualified by color change. Each implant exhibited color change following 50 Gy, and the bio-oncotic gel became significantly less formable following irradiation, and even less formable 6 weeks postirradiation. The data indicates that prostheses do not affect the photon beam distribution, but radiation does affect the prosthesis. 9 refs., 10 figs., 5 tabs.

  2. Clinical Management of Implant Prostheses in Patients with Bruxism

    Directory of Open Access Journals (Sweden)

    Osamu Komiyama

    2012-01-01

    Full Text Available There is general agreement that excessive stress to the bone-implant interface may result in implant overload and failure. Early failure of the implant due to excessive loading occurs shortly after uncovering the implant. Excess load on a final restoration after successful implant integration can result in physical failure of the implant structure. Many clinicians believe that overload of dental implants is a risk factor for vertical peri-implant bone loss and/or may be detrimental for the suprastructure in implant prostheses. It has been documented that occlusal parafunction, such as, bruxism (tooth grinding and clenching affects the outcome of implant prostheses, but there is no evidence for a causal relation between the failures and overload of dental implants. In spite of this lack of evidence, often metal restorations are preferred instead of porcelain for patients in whom bruxism is presumed on the basis of tooth wear. The purpose of this paper is to discuss the importance of the occlusal scheme used in implant restorations for implant longevity and to suggest a clinical approach and occlusal materials for implant prostheses in order to prevent complications related to bruxism.

  3. Clinical Management of Implant Prostheses in Patients with Bruxism

    Science.gov (United States)

    Komiyama, Osamu; Lobbezoo, Frank; De Laat, Antoon; Iida, Takashi; Kitagawa, Tsuyoshi; Murakami, Hiroshi; Kato, Takao; Kawara, Misao

    2012-01-01

    There is general agreement that excessive stress to the bone-implant interface may result in implant overload and failure. Early failure of the implant due to excessive loading occurs shortly after uncovering the implant. Excess load on a final restoration after successful implant integration can result in physical failure of the implant structure. Many clinicians believe that overload of dental implants is a risk factor for vertical peri-implant bone loss and/or may be detrimental for the suprastructure in implant prostheses. It has been documented that occlusal parafunction, such as, bruxism (tooth grinding and clenching) affects the outcome of implant prostheses, but there is no evidence for a causal relation between the failures and overload of dental implants. In spite of this lack of evidence, often metal restorations are preferred instead of porcelain for patients in whom bruxism is presumed on the basis of tooth wear. The purpose of this paper is to discuss the importance of the occlusal scheme used in implant restorations for implant longevity and to suggest a clinical approach and occlusal materials for implant prostheses in order to prevent complications related to bruxism. PMID:22701484

  4. Clinical management of implant prostheses in patients with bruxism.

    Science.gov (United States)

    Komiyama, Osamu; Lobbezoo, Frank; De Laat, Antoon; Iida, Takashi; Kitagawa, Tsuyoshi; Murakami, Hiroshi; Kato, Takao; Kawara, Misao

    2012-01-01

    There is general agreement that excessive stress to the bone-implant interface may result in implant overload and failure. Early failure of the implant due to excessive loading occurs shortly after uncovering the implant. Excess load on a final restoration after successful implant integration can result in physical failure of the implant structure. Many clinicians believe that overload of dental implants is a risk factor for vertical peri-implant bone loss and/or may be detrimental for the suprastructure in implant prostheses. It has been documented that occlusal parafunction, such as, bruxism (tooth grinding and clenching) affects the outcome of implant prostheses, but there is no evidence for a causal relation between the failures and overload of dental implants. In spite of this lack of evidence, often metal restorations are preferred instead of porcelain for patients in whom bruxism is presumed on the basis of tooth wear. The purpose of this paper is to discuss the importance of the occlusal scheme used in implant restorations for implant longevity and to suggest a clinical approach and occlusal materials for implant prostheses in order to prevent complications related to bruxism.

  5. A dynamical systems view of motor preparation: Implications for neural prosthetic system design

    Science.gov (United States)

    Shenoy, Krishna V.; Kaufman, Matthew T.; Sahani, Maneesh; Churchland, Mark M.

    2013-01-01

    Neural prosthetic systems aim to help disabled patients suffering from a range of neurological injuries and disease by using neural activity from the brain to directly control assistive devices. This approach in effect bypasses the dysfunctional neural circuitry, such as an injured spinal cord. To do so, neural prostheses depend critically on a scientific understanding of the neural activity that drives them. We review here several recent studies aimed at understanding the neural processes in premotor cortex that precede arm movements and lead to the initiation of movement. These studies were motivated by hypotheses and predictions conceived of within a dynamical systems perspective. This perspective concentrates on describing the neural state using as few degrees of freedom as possible and on inferring the rules that govern the motion of that neural state. Although quite general, this perspective has led to a number of specific predictions that have been addressed experimentally. It is hoped that the resulting picture of the dynamical role of preparatory and movement-related neural activity will be particularly helpful to the development of neural prostheses, which can themselves be viewed as dynamical systems under the control of the larger dynamical system to which they are attached. PMID:21763517

  6. Adherence of Staphylococcus aureus to Dyneema Purity® Patches and to Clinically Used Cardiovascular Prostheses

    OpenAIRE

    Basir, Amir; Grundeman, Paul; Moll, Frans; van Herwaarden, Joost; Pasterkamp, Gerard; Nijland, Reindert

    2016-01-01

    Various materials that are used for vascular and heart valve prostheses carry drawbacks: some require anticoagulant drugs or have moderate durability; others are not suitable for endovascular treatment. These prostheses are associated with bacterial infections. A material potentially suitable for prostheses is Dyneema Purity®, made of ultra-high-molecularweight polyethylene. Dyneema Purity® fibers are very thin, flexible, resistant to fatigue and abrasion, and have high strength. S. aureus ad...

  7. Movement characteristics of upper extremity prostheses during basic goal-directed tasks

    OpenAIRE

    Bouwsema, Hanneke; van der Sluis, Corry K.; Bongers, Raoul M.

    2010-01-01

    Background: After an upper limb amputation a prosthesis is often used to restore the functionality. However, the frequency of prostheses use is generally low. Movement kinematics of prostheses use might suggest origins of this low use. The aim of this study was to reveal movement patterns of prostheses during basic goal-directed actions in upper limb prosthetic users and to compare this with existing knowledge of able-bodied performance during these actions. Methods: Movements from six users ...

  8. Hybrid Invariance and Stability of a Feedback Linearizing Controller for Powered Prostheses

    OpenAIRE

    Martin, Anne E.; Gregg, Robert D.

    2015-01-01

    The development of powered lower-limb prostheses has the potential to significantly improve amputees’ quality of life. By applying advanced control schemes, such as hybrid zero dynamics (HZD), to prostheses, more intelligent prostheses could be designed. Originally developed to control bipedal robots, HZD-based control specifies the motion of the actuated degrees of freedom using output functions to be zeroed, and the required torques are calculated using feedback linearization. Previous work...

  9. An inconvenient influence of iridium(III) isomer on OLED efficiency.

    Science.gov (United States)

    Baranoff, Etienne; Bolink, Henk J; De Angelis, Filippo; Fantacci, Simona; Di Censo, Davide; Djellab, Karim; Grätzel, Michael; Nazeeruddin, Md Khaja

    2010-10-14

    The recently reported heteroleptic cyclometallated iridium(III) complex [Ir(2-phenylpyridine)(2)(2-carboxy-4-dimethylaminopyridine)] N984 and its isomer N984b have been studied more in detail. While photo- and electrochemical properties are very similar, DFT/TDDFT calculations show that the two isomers have different HOMO orbital characteristics. As a consequence, solution processed OLEDs made using a mixture of N984 and isomer N984b similar to vacuum processed devices show that the isomer has a dramatic detrimental effect on the performances of the device. In addition, commonly used thermogravimetric analysis is not suitable for showing the isomerization process. The isomer could impact performances of vacuum processed OLEDs using heteroleptic cyclometallated iridium(III) complexes as dopant.

  10. Experimental and Theoretical Mechanistic Investigation of the Iridium-Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols

    DEFF Research Database (Denmark)

    Olsen, Esben Paul Krogh; Singh, Thishana; Harris, Pernille

    2015-01-01

    The mechanism for the iridium-BINAP catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of molecular hydrogen and carbon monoxide was studied experimentally and computationally. The reaction takes place by tandem catalysis through two catalytic cycles involving...... dehydrogenation of the alcohol and decarbonylation of the resulting aldehyde. The square planar complex IrCl(CO)(rac-BINAP) was isolated from the reaction between [Ir(cod)Cl](2), rac-BINAP, and benzyl alcohol. The complex was catalytically active and applied in the study of the individual steps in the catalytic...... cycles. One carbon monoxide ligand was shown to remain coordinated to iridium throughout the reaction, and release of carbon monoxide was suggested to occur from a dicarbonyl complex. IrH2Cl(CO)(rac-BINAP) was also synthesized and detected in the dehydrogenation of benzyl alcohol. In the same experiment...

  11. Phosphorescent Organic Light-Emitting Devices: Working Principle and Iridium Based Emitter Materials

    Directory of Open Access Journals (Sweden)

    Emil J. W. List

    2008-08-01

    Full Text Available Even though organic light-emitting device (OLED technology has evolved to a point where it is now an important competitor to liquid crystal displays (LCDs, further scientific efforts devoted to the design, engineering and fabrication of OLEDs are required for complete commercialization of this technology. Along these lines, the present work reviews the essentials of OLED technology putting special focus on the general working principle of single and multilayer OLEDs, fluorescent and phosphorescent emitter materials as well as transfer processes in host materials doped with phosphorescent dyes. Moreover, as a prototypical example of phosphorescent emitter materials, a brief discussion of homo- and heteroleptic iridium(III complexes is enclosed concentrating on their synthesis, photophysical properties and approaches for realizing iridium based phosphorescent polymers.

  12. First Applications of DoD Iridium RUDICS in the NSF Polar Programs

    Science.gov (United States)

    Valentic, T.; Stehle, R.

    2008-12-01

    We will present the first deployment and application of the new Iridium RUDICS service to remote instrumentation projects within the National Science Foundation's polar programs. The rise of automated observing networks has increased the demand for real-time connectivity to remote instruments, not only for immediate access to data, but to also interrogate health and status. Communicating with field sites in the polar regions is complicated by the remoteness from existing infrastructure, low temperatures and limited connection options. Sites located above 78° latitude are not able to see geostationary satellites, leaving the Iridium constellation as the only one that provide a direct connection. Some others, such as Orbcomm, only provide a store-and-forward service. Iridium is often used as a dial up modem to establish a PPP connection to the Internet with data files transferred via FTP. On low-bandwidth, high-latency networks like Iridium (2400bps with ping times of seconds), this approach is time consuming and inefficient. The dial up time alone takes upwards of a minute, and standard TCP/IP and FTP protocols are hampered by the long latencies. Minimizing transmission time is important for reducing battery usage and connection costs. The new Iridium RUDICS service can be used for more efficient transfers. RUDICS is an acronym for "Router-based Unstructured Digital Inter-working Connectivity Solution" and provides a direct connection between an instrument in the field and a server on the Internet. After dialing into the Iridium gateway, a socket connection is opened to a registered port on a user's server. Bytes sent to or from the modem appear at the server's socket. The connection time is reduced to about 10 seconds because the modem training and PPP negotiation stages are eliminated. The remote device does not need to have a full TCP/IP stack, allowing smaller instruments such as data loggers to directly handle the data transmission. Alternative protocols can

  13. Grain Growth and Precipitation Behavior of Iridium Alloy DOP-26 During Long Term Aging

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Dean T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Muralidharan, Govindarajan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fox, Ethan E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cox, Victoria A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Geer, Tom [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-05-01

    The influence of long term aging on grain growth and precipitate sizes and spatial distribution in iridium alloy DOP-26 was studied. Samples of DOP-26 were fabricated using the new process, recrystallized for 1 hour (h) at 1375 C, then aged at either 1300, 1400, or 1500 C for times ranging from 50 to 10,000 h. Grain size measurements (vertical and horizontal mean linear intercept and horizontal and vertical projection) and analyses of iridium-thorium precipitates (size and spacing) were made on the longitudinal, transverse, and rolling surfaces of the as-recrystallized and aged specimens from which the two-dimensional spatial distribution and mean sizes of the precipitates were obtained. The results obtained from this study are intended to provide input to grain growth models.

  14. Fusion of electromyographic signals with proprioceptive sensor data in myoelectric pattern recognition for control of active transfemoral leg prostheses.

    Science.gov (United States)

    Delis, Alberto López; de Carvalho, João Luiz Azevedo; Borges, Geovany Araújo; de Siqueira Rodrigues, Suélia; dos Santos, Icaro; da Rocha, Adson Ferreira

    2009-01-01

    This paper presents a myoelectric knee joint angle estimation algorithm for control of active transfemoral prostheses, based on feature extraction and pattern classification. The feature extraction stage uses a combination of time domain and frequency domain methods (entropy of myoelectric signals and cepstral coefficients, respectively). Additionally, the methods are fused with data from proprioceptive sensors (gyroscopes), from which angular rate information is extracted using a Kalman filter. The algorithm uses a Levenberg-Marquardt neural network for estimating the intended knee joint angle. The proposed method is demonstrated in a normal volunteer, and the results are compared with pattern classification methods based solely on electromyographic data. The use of surface electromyographic signals and additional information related to proprioception improves the knee joint angle estimation precision and reduces estimation artifacts.

  15. Coordination chemistry and catalytic activity of N-heterocyclic carbene iridium(I) complexes.

    Science.gov (United States)

    Fu, Ching-Feng; Chang, Yung-Hung; Liu, Yi-Hong; Peng, Shei-Ming; Elsevier, Cornelis J; Chen, Jwu-Ting; Liu, Shiuh-Tzung

    2009-09-21

    Iridium complexes [(CO)2Ir(NHC-R)Cl] (R = Et-, 3a; PhCH2-, 3b; CH3OCH2CH2-, 3c; o-CH3OC6H4CH2-, 3d; NHC: N-heterocyclic carbene) are prepared via the carbene transfer from [(NHC-R)W(CO)5] to [Ir(COD)Cl]2. By using substitution with 13CO, we are able to estimate the activation energy (G) of the CO-exchange in 3a-d, which are in the range of 12-13 kcal mol-1, significantly higher than those for the phosphine analog [(CO)2Ir(PCy3)Cl]. Reactions of 3b and 3d with an equimolar amount of PPh3 result in the formation of the corresponding [(NHC-R)Ir(CO)(PPh3)Cl] with the phosphine and NHC in trans arrangement. In contrast, the analogous reaction of 3a or 3c with phosphine undergoes substitution followed by the anion metathesis to yield the corresponding di-substituted [(NHC-R)Ir(CO)(PPh3)2]BF4 (5) directly. Treatment of 3b or 3d with excess of PPh3 leads to the similar product of disubstitution 5b and 5d. The analysis for the IR data of carbonyliridium complexes provides the estimation of electron-donating power of NHCs versus phosphines. The NHC moiety on the iridium center cannot be replaced by phosphines, even 1,2-bis(diphenylphohino)ethane (dppe). All the carbene moieties on the iridium complexes are inert toward sulfur treatment, indicating a strong interaction between NHC and the iridium centers. Complexes 3a-c are active on the catalysis of the oxidative cyclization of 2-(o-aminophenyl)ethanol to yield the indole compound. The phosphine substituted complexes or analogs are less active.

  16. Transformation of a Cp*-iridium(III) precatalyst for water oxidation when exposed to oxidative stress.

    Science.gov (United States)

    Zuccaccia, Cristiano; Bellachioma, Gianfranco; Bortolini, Olga; Bucci, Alberto; Savini, Arianna; Macchioni, Alceo

    2014-03-17

    The reaction of [Cp*Ir(bzpy)NO3 ] (1; bzpy=2-benzoylpyridine, Cp*=pentamethylcyclopentadienyl anion), a competent water-oxidation catalyst, with several oxidants (H2 O2 , NaIO4 , cerium ammonium nitrate (CAN)) was studied to intercept and characterize possible intermediates of the oxidative transformation. NMR spectroscopy and ESI-MS techniques provided evidence for the formation of many species that all had the intact Ir-bzpy moiety and a gradually more oxidized Cp* ligand. Initially, an oxygen atom is trapped in between two carbon atoms of Cp* and iridium, which gives an oxygen-Ir coordinated epoxide, whereas the remaining three carbon atoms of Cp* are involved in a η(3) interaction with iridium (2 a). Formal addition of H2 O to 2 a or H2 O2 to 1 leads to 2 b, in which a double MeCOH functionalization of Cp* is present with one MeCOH engaged in an interaction with iridium. The structure of 2 b was unambiguously determined in the solid state and in solution by X-ray single-crystal diffractometry and advanced NMR spectroscopic techniques, respectively. Further oxidation led to the opening of Cp* and transformation of the diol into a diketone with one carbonyl coordinated at the metal (2 c). A η(3) interaction between the three non-oxygenated carbons of "ex-Cp*" and iridium is also present in both 2 b and 2 c. Isolated 2 b and mixtures of 2 a-c species were tested in water-oxidation catalysis by using CAN as sacrificial oxidant. They showed substantially the same activity than 1 (turnover frequency values ranged from 9 to 14 min(-1) ). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Csp(3) -H Activation without Chelation Assistance in an Iridium Pincer Complex Forming Cyclometallated Products.

    Science.gov (United States)

    Ahlstrand, David A; Polukeev, Alexey V; Marcos, Rocío; Ahlquist, Mårten S G; Wendt, Ola F

    2017-02-03

    Cyclometallation of 8-methylquinoline and 2-(dimethylamino)-pyridine in an iridium-based pincer complex is described. The C-H activation of 2-(dimethylamino)pyridine is not chelation assisted, which has not been described before for Csp(3) -H bonds in cyclometallation reactions. The mechanism of the cyclometallation of 2-(dimethylamino)pyridine was studied by DFT calculations and kinetic measurements. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. High performance optical oxygen sensors based on iridium complexes exhibiting interchromophore energy shuttling

    OpenAIRE

    Medina-Rodríguez, Santiago; Denisov, Sergey A.; Cudré, Yanouk; Male, Louise; Marín-Suárez, Marta; Fernández-Gutiérrez, Alberto; Fernández-Sánchez, Jorge F.; Tron, Arnaud,; Jonusauskas, Gediminas; McClenaghan, Nathan D.; Baranoff, Etienne

    2016-01-01

    International audience; A doubly pyrene-grafted bis-cyclometallated iridium complex with engineered electronically excited states demonstrates reversible electronic energy transfer between adjacent chromophores giving rise to extremely long-lived red luminescence in solution (τ = 480 μs). Time-resolved spectroscopic studies afforded determination of pertinent photophysical parameters including rates of energy transfer and energy distribution between constituent chromophores in the equilibrate...

  19. Copper(I) complexes as alternatives to iridium(III) complexes for highly efficient oxygen sensing.

    Science.gov (United States)

    Medina-Rodríguez, Santiago; Orriach-Fernández, Francisco J; Poole, Christopher; Kumar, Prashant; de la Torre-Vega, Ángel; Fernández-Sánchez, Jorge F; Baranoff, Etienne; Fernández-Gutiérrez, Alberto

    2015-07-21

    The complex [Cu(xantphos)(dmp)][PF6] (dmp = 2,9-dimethyl-1,10-phenanthroline) in a nanostructured metal oxyde matrix shows better sensitivity to oxygen (KSV = 9.74 ± 0.87 kPa(-1) between 0 and 1 kPa pO2 and 5.59 ± 0.15 kPa(-1) between 0 and 10 kPa pO2) than cyclometallated iridium complexes in the same conditions.

  20. Biocompatibility and durability of Teflon-coated platinum-iridium wires implanted in the vitreous cavity.

    Science.gov (United States)

    Nishida, Kentaro; Sakaguchi, Hirokazu; Xie, Ping; Terasawa, Yasuo; Ozawa, Motoki; Kamei, Motohiro; Nishida, Kohji

    2011-12-01

    Teflon-coated platinum-iridium wires are placed in the vitreous as electrodes in artificial vision systems. The purpose of this study was to determine whether these wires have toxicity in the vitreous cavity, and to examine the durability of their coating when grasped by forceps. Rabbits were implanted with platinum-iridium wires that were 50 μm in diameter and coated with Teflon to a total diameter of 68 or 100 μm. To examine the biocompatibility, electroretinograms (ERGs) and fluorescein angiography (FA) were performed before and 1 week, 1, 3, and 6 months after the implantation of the electrode. After 6 months, the eyes were histologically examined with light microscopy. To check the durability, the surface of a coated wire was examined with scanning electron microscopy after grasping with different types of forceps. At all times after the implantation the amplitudes and implicit times of the ERGs recorded were not significantly different from those recorded before the implantation (P > 0.05). FA showed no notable change during the follow-up periods. Histological studies showed that the retinas were intact after 6 months of implantation. There was no damage to the Teflon-coated wire after grasping the wire with forceps with silicon-coated tips, while surface damage of the Teflon that did not extend to the platinum-iridium wire was found when grasped by vitreoretinal forceps. We conclude that Teflon-coated platinum-iridium wire is highly biocompatible in the vitreous for at least 6 months. Wires should be handled with vitreoretinal forceps with silicone-coated tips in order to avoid causing damage during wire manipulation.

  1. Enantioselective synthesis of alcohols and amines by iridium-catalyzed hydrogenation, transfer hydrogenation, and related processes.

    Science.gov (United States)

    Bartoszewicz, Agnieszka; Ahlsten, Nanna; Martín-Matute, Belén

    2013-06-03

    The preparation of chiral alcohols and amines by using iridium catalysis is reviewed. The methods presented include the reduction of ketones or imines by using hydrogen (hydrogenations), isopropanol, formic acid, or formate (transfer hydrogenations). Also dynamic and oxidative kinetic resolutions leading to chiral alcohols and amines are included. Selected literature reports from early contributions to December 2012 are discussed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Highly efficient deep-blue phosphorescence from heptafluoropropyl-substituted iridium complexes.

    Science.gov (United States)

    Kim, Jung-Bum; Han, Seung-Hoon; Yang, Kiyull; Kwon, Soon-Ki; Kim, Jang-Joo; Kim, Yun-Hi

    2015-01-04

    New deep-blue iridium complexes, consisting of a heptafluoropropyl (HFP) substituent at the 3' position of 2',4''-difluorophenyl, have a deep HOMO level and decreased shoulder electronic transition and inhibit self-quenching due to the sterically hindered group without conjugation. An OLED using (HFP)2Ir(mpic) exhibited a maximum EQE of 21.4% with a CIE of (0.146, 0.165).

  3. Le système binaire aluminium-iridium, du diagramme de phases aux surfaces atomiques

    OpenAIRE

    Kadok, Joris

    2016-01-01

    A complex metallic alloy (CMA) is an intermetallic compound whose unit cell contains a large number of atoms oftenly forming highly-symmetric clusters. From the complexity of these compounds can arise physical and chemical properties interesting for various fields of application. The aluminium-iridium binary system exhibits numerous intermetallic compounds of which half of them are actually CMAs. Despite this system being extensively studied in the literature, some uncertainies remained unsol...

  4. Enhancing and inhibiting effects of benzenediols on chemiluminescence of a novel cyclometallated iridium(III) complex.

    Science.gov (United States)

    Dong, Yong Ping; Huang, Li; Tong, Bi Hai; Shi, Ming Juan; Zhang, Wang Bing; Zhang, Qian Feng

    2012-01-01

    A novel chemiluminescence (CL) system, including the cyclometallated iridium(III) complex {tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium}, potassium permanganate and oxalic acid, is proposed for the determination of benzenediols. This method is based on the fact that hydroquinone and catechol exhibited an inhibiting effect, while resorcinol exhibited an enhancing effect on CL intensity. The optimum conditions for CL emission were investigated. Under optimal conditions, the detection limits of hydroquinone, catechol and resorcinol were 6.4 × 10(-8), 2.7 × 10(-9) and 8.1 × 10(-7)  mol/L, respectively. The method has been successfully applied to the determination of benzenediols in different types of water sample. The luminophors of the CL systems were all identified as the metal-ligand charge-transfer (MLCT) excited state of the iridium complex. Copyright © 2011 John Wiley & Sons, Ltd.

  5. Study of lobster eye optics with iridium coated x-ray mirrors for a rocket experiment

    Science.gov (United States)

    Stehlikova, Veronika; Urban, Martin; Nentvich, Ondrej; Inneman, Adolf; Döhring, Thorsten; Probst, Anne-Catherine

    2017-05-01

    In the field of astronomical X-ray telescopes, different types of optics based on grazing incidence mirrors can be used. This contribution describes the special design of a lobster-eye optics in Schmidt's arrangement, which uses dual reflection to increase the collecting area. The individual mirrors of this wide-field telescope are made of at silicon wafers coated with reflecting iridium layers. This iridium coatings have some advantages compared to more common gold layers as is shown in corresponding simulations. The iridium coating process for the X-ray mirrors was developed within a cooperation of the Aschaffenburg University of Applied Sciences and the Czech Technical University in Prague. Different mirror parameters essential for a proper function of the X-ray optics, like the surface microroughness and the problematic of a good adhesion quality of the coatings were studied. After integration of the individual mirrors into the final lobster-eye optics and the corresponding space qualification testing it is planned to fly the telescope in a recently proposed NASA rocket experiment.

  6. A review and update on the current status of retinal prostheses (bionic eye).

    Science.gov (United States)

    Luo, Yvonne H-L; da Cruz, Lyndon

    2014-01-01

    The Argus® II is the first retinal prosthesis approved for the treatment of patients blind from retinitis pigmentosa (RP), receiving CE (Conformité Européenne) marking in March 2011 and FDA approval in February 2013. Alpha-IMS followed closely and obtained CE marking in July 2013. Other devices are being developed, some of which are currently in clinical trials. A systematic literature search was conducted on PubMED, Google Scholar and IEEExplore. Retinal prostheses play a part in restoring vision in blind RP patients providing stable, safe and long-term retinal stimulation. Objective improvement in visual function does not always translate into consistent improvement in the patient's quality of life. Controversy exists over the use of an external image-capturing device versus internally placed photodiode devices. The alpha-IMS, a photovoltaic-based retinal prosthesis recently obtained its CE marking in July 2013. Improvement in retinal prosthetic vision depends on: (i) improving visual resolution, (ii) improving the visual field, (iii) developing an accurate neural code for image processing and (iv) improving the biocompatibility of the device to ensure longevity.

  7. Recent advances in neural recording microsystems.

    Science.gov (United States)

    Gosselin, Benoit

    2011-01-01

    The accelerating pace of research in neuroscience has created a considerable demand for neural interfacing microsystems capable of monitoring the activity of large groups of neurons. These emerging tools have revealed a tremendous potential for the advancement of knowledge in brain research and for the development of useful clinical applications. They can extract the relevant control signals directly from the brain enabling individuals with severe disabilities to communicate their intentions to other devices, like computers or various prostheses. Such microsystems are self-contained devices composed of a neural probe attached with an integrated circuit for extracting neural signals from multiple channels, and transferring the data outside the body. The greatest challenge facing development of such emerging devices into viable clinical systems involves addressing their small form factor and low-power consumption constraints, while providing superior resolution. In this paper, we survey the recent progress in the design and the implementation of multi-channel neural recording Microsystems, with particular emphasis on the design of recording and telemetry electronics. An overview of the numerous neural signal modalities is given and the existing microsystem topologies are covered. We present energy-efficient sensory circuits to retrieve weak signals from neural probes and we compare them. We cover data management and smart power scheduling approaches, and we review advances in low-power telemetry. Finally, we conclude by summarizing the remaining challenges and by highlighting the emerging trends in the field.

  8. Recent Advances in Neural Recording Microsystems

    Directory of Open Access Journals (Sweden)

    Benoit Gosselin

    2011-04-01

    Full Text Available The accelerating pace of research in neuroscience has created a considerable demand for neural interfacing microsystems capable of monitoring the activity of large groups of neurons. These emerging tools have revealed a tremendous potential for the advancement of knowledge in brain research and for the development of useful clinical applications. They can extract the relevant control signals directly from the brain enabling individuals with severe disabilities to communicate their intentions to other devices, like computers or various prostheses. Such microsystems are self-contained devices composed of a neural probe attached with an integrated circuit for extracting neural signals from multiple channels, and transferring the data outside the body. The greatest challenge facing development of such emerging devices into viable clinical systems involves addressing their small form factor and low-power consumption constraints, while providing superior resolution. In this paper, we survey the recent progress in the design and the implementation of multi-channel neural recording Microsystems, with particular emphasis on the design of recording and telemetry electronics. An overview of the numerous neural signal modalities is given and the existing microsystem topologies are covered. We present energy-efficient sensory circuits to retrieve weak signals from neural probes and we compare them. We cover data management and smart power scheduling approaches, and we review advances in low-power telemetry. Finally, we conclude by summarizing the remaining challenges and by highlighting the emerging trends in the field.

  9. Immediate loading of tooth-implant-supported telescopic mandibular prostheses.

    Science.gov (United States)

    Romanos, George E; May, Stephan; May, Dittmar

    2012-01-01

    Extractions in partially edentulous patients often lead to insufficient stability of an existing partial prosthesis and a need for additional anchorage. Implants may therefore be placed as supplementary abutments to increase patient comfort and satisfaction. The aim of this study was to evaluate the long-term clinical outcome of implants combined with teeth to support telescopic abutment-retained removable full-arch prostheses under an immediate functional loading protocol. The present retrospective study included implants placed and connected via removable prostheses with periodontally healthy teeth immediately postplacement using prefabricated abutments. Secondary copings, precisely fit to the abutments, were placed and the partial dentures were relined chairside. The prosthetic restorations were not removed for 10 days. Clinical and radiographic evaluations of implants loaded for at least 2 years were performed. One hundred ten implants with a progressive thread design (Ankylos, Dentsply) were placed in 55 patients (mean age, 63.51±9.95 years). Twenty-five implants were placed in fresh extraction sockets (22.73%) and 85 implants were placed in healed ridges. All implants were placed 2 to 3 mm subcrestally (measured from the midfacial bone level). After a mean follow-up of 61.58±28.47 months (range, 24 to 125 months), there were only three failures (2.73%); another six implants (5.45%) displayed crestal bone loss greater than 2 mm but remained stable. Therefore, the failure rate was 8.18% for the entire observation period of 5.13 years. The success rate was 91.82% and the cumulative survival rate was 97.27%. All patients were satisfied with the stability of their prostheses, and no prosthetic, peri-implant, or abutment tooth problems were observed. Telescopic tooth-implant-supported mandibular restorations with immediate loading present an alternative prosthetic solution for partially edentulous patients, providing a long-term predictable clinical outcome.

  10. Residual stresses in porcelain-veneered zirconia prostheses.

    Science.gov (United States)

    Baldassarri, Marta; Stappert, Christian F J; Wolff, Mark S; Thompson, Van P; Zhang, Yu

    2012-08-01

    Compressive stress has been intentionally introduced into the overlay porcelain of zirconia-ceramic prostheses to prevent veneer fracture. However, recent theoretical analysis has predicted that the residual stresses in the porcelain may be also tensile in nature. This study aims to determine the type and magnitude of the residual stresses in the porcelain veneers of full-contour fixed-dental prostheses (FDPs) with an anatomic zirconia coping design and in control porcelain with the zirconia removed using a well-established Vickers indentation method. Six 3-unit zirconia FDPs were manufactured (NobelBiocare, Gothenburg, Sweden). Porcelain was hand-veneered using a slow cooling rate. Each FDP was sectioned parallel to the occlusal plane for Vickers indentations (n = 143; load = 9.8 N; dwell time = 5s). Tests were performed in the veneer of porcelain-zirconia specimens (bilayers, n=4) and porcelain specimens without zirconia cores (monolayers, n = 2). The average crack lengths and standard deviation, in the transverse and radial directions (i.e. parallel and perpendicular to the veneer/core interface, respectively), were 67 ± 12 μm and 52 ± 8 μm for the bilayers and 64 ± 8 μm and 64 ± 7 μm for the monolayers. These results indicated a major hoop compressive stress (~40-50 MPa) and a moderate radial tensile stress (~10 MPa) in the bulk of the porcelain veneer. Vickers indentation is a powerful method to determine the residual stresses in veneered zirconia systems. Our findings revealed the presence of a radial tensile stress in the overlay porcelain, which may contribute to the large clinical chip fractures observed in these prostheses. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  11. Residual Stresses in Porcelain-veneered Zirconia Prostheses

    Science.gov (United States)

    Baldassarri, Marta; Stappert, Christian F. J.; Wolff, Mark S.; Thompson, Van P.; Zhang, Yu

    2012-01-01

    Objectives Compressive stress has been intentionally introduced into the overlay porcelain of zirconia-ceramic prostheses to prevent veneer fracture. However, recent theoretical analysis has predicted that the residual stresses in the porcelain may be also tensile in nature. This study aims to determine the type and magnitude of the residual stresses in the porcelain veneers of full-contour fixed-dental prostheses (FDPs) with an anatomic zirconia coping design and in control porcelain with the zirconia removed using a well-established Vickers indentation method. Methods Six 3-unit zirconia FDPs were manufactured (NobelBiocare, Gothenburg, Sweden). Porcelain was hand-veneered using a slow cooling rate. Each FDP was sectioned parallel to the occlusal plane for Vickers indentations (n = 143; load = 9.8 N; dwell time = 5 s). Tests were performed in the veneer of porcelain-zirconia specimens (bilayers, n = 4) and porcelain specimens without zirconia cores (monolayers, n = 2). Results The average crack lengths and standard deviation, in the transverse and radial directions (i.e. parallel and perpendicular to the veneer/core interface, respectively), were 67 ± 12 μm and 52 ± 8 μm for the bilayers and 64 ± 8 μm and 64 ± 7 μm for the monolayers. These results indicated a major hoop compressive stress (~40 to 50 MPa) and a moderate radial tensile stress (~10 MPa) in the bulk of the porcelain veneer. Significance Vickers indentation is a powerful method to determine the residual stresses in veneered zirconia systems. Our findings revealed the presence of a radial tensile stress in the overlay porcelain, which may contributed to the large clinical chip fractures observed in these prostheses. PMID:22578663

  12. Stress analysis in oral obturator prostheses, part II: photoelastic imaging.

    Science.gov (United States)

    Pesqueira, Aldiéris Alves; Goiato, Marcelo Coelho; da Silva, Emily Vivianne Freitas; Haddad, Marcela Filié; Moreno, Amália; Zahoui, Abbas; dos Santos, Daniela Micheline

    2014-06-01

    In part I of the study, two attachment systems [O-ring; bar-clip (BC)] were used, and the system with three individualized O-rings provided the lowest stress on the implants and the support tissues. Therefore, the aim of this study was to assess the stress distribution, through the photoelastic method, on implant-retained palatal obturator prostheses associated with different attachment systems: BOC--splinted implants with a bar connected to two centrally placed O-rings, and BOD--splinted implants with a BC connected to two distally placed O-rings (cantilever). One photoelastic model of the maxilla with oral-sinus-nasal communication with three parallel implants was fabricated. Afterward, two implant-retained palatal obturator prostheses with the two attachment systems described above were constructed. Each assembly was positioned in a circular polariscope and a 100-N axial load was applied in three different regions with implants by using a universal testing machine. The results were obtained through photograph record analysis of stress. The BOD system exhibited the highest stress concentration, followed by the BOC system. The O-ring, centrally placed on the bar, allows higher mobility of the prostheses and homogeneously distributes the stress to the region of the alveolar ridge and implants. It can be concluded that the use of implants with O-rings, isolated or connected with a bar, to rehabilitate maxillectomized patients allows higher prosthesis mobility and homogeneously distributes the stress to the alveolar ridge region, which may result in greater chewing stress distribution to implants and bone tissue. The clinical implication of the augmented bone support loss after maxillectomy is the increase of stress in the attachment systems and, consequently, a higher tendency for displacement of the prosthesis.

  13. Modular externally-powered system for limb prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Seamone, W.; Hoshall, C.H.; Schmeisser, G.

    Many upper limb amputees especially those who have sustained high level amputations of injury to remaining portions of the body, are unable to use conventional prosthetic devices effectively. In an effort to help the more severely handicapped amputees and those who may for other reasons require capabilities that standard prostheses cannot provide, the Applied Physics Laboratory, in conjunction with the Johns Hopkins Medical Institutions, has developed a prosthetic system which is powered by rechargeable batteries. The amputee need supply only a control signal. This article describes the concept which is now being evaluated with the aid of amputee subjects, and discusses results obtained to data in field tests.

  14. A biodegradable gentamicin-hydroxyapatite-coating for infection prophylaxis in cementless hip prostheses

    NARCIS (Netherlands)

    Neut, D.; Dijkstra, R. J. B.; Thompson, J. I.; Kavanagh, C.; van der Mei, H. C.; Busscher, H. J.

    2015-01-01

    A degradable, poly (lactic-co-glycolic acid) (PLGA), gentamicin-loaded prophylactic coating for hydroxyapatite (HA)-coated cementless hip prostheses is developed with similar antibacterial efficacy as offered by gentamicin-loaded cements for fixing traditional, cemented prostheses in bone. We

  15. High cable forces deteriorate pinch force control in voluntary-closing body-powered prostheses

    NARCIS (Netherlands)

    Hichert, M.; Abbink, D.A.; Kyberd, P.J.; Plettenburg, D.H.

    2017-01-01

    Background It is generally asserted that reliable and intuitive control of upper-limb prostheses requires adequate feedback of prosthetic finger positions and pinch forces applied to objects. Bodypowered prostheses (BPPs) provide the user with direct proprioceptive feedback. Currently available

  16. A need for a more user-centered design in body powered prostheses

    NARCIS (Netherlands)

    Hichert, M.; Plettenburg, D.H.; Vardy, A.N.; Will, Wendy; Scheme, Erik

    2014-01-01

    Users of body powered prostheses (BPP) complain about too high operating forces, leading to pain and/or fatigue during or after prosthetic operation. In the worst case nerve and vessel damage can occur [1, 2], leading to nonuse of prostheses. Smit et al. investigated cable forces and displacements

  17. Adherence of staphylococcus aureus to dyneema Purity® patches and to clinically used cardiovascular prostheses

    NARCIS (Netherlands)

    Basir, Amir; Gründeman, Paul; Moll, Frans; Herwaarden, van Joost; Pasterkamp, Gerard; Nijland, Reindert

    2016-01-01

    Various materials that are used for vascular and heart valve prostheses carry drawbacks: some require anticoagulant drugs or have moderate durability; others are not suitable for endovascular treatment. These prostheses are associated with bacterial infections. A material potentially suitable for

  18. Dual jaw treatment of edentulism using implant-supported monolithic zirconia fixed prostheses.

    Science.gov (United States)

    Altarawneh, Sandra; Limmer, Bryan; Reside, Glenn J; Cooper, Lyndon

    2015-01-01

    This case report describes restoration of the edentulous maxilla and mandible with implant supported fixed prostheses using monolithic zirconia, where the incisal edges and occluding surfaces were made of monolithic zirconia. Edentulism is a debilitating condition that can be treated with either a removable or fixed dental prosthesis. The most common type of implant-supported fixed prosthesis is the metal acrylic (hybrid), with ceramo-metal prostheses being used less commonly in complete edentulism. However, both of these prostheses designs are associated with reported complications of screw loosening or fracture and chipping of acrylic resin and porcelain. Monolithic zirconia implant-supported fixed prostheses have the potential for reduction of such complications. In this case, the CAD/CAM concept was utilized in fabrication of maxillary and mandibular screw-retained implant-supported fixed prostheses using monolithic zirconia. Proper treatment planning and execution coupled with utilizing advanced technologies contributes to highly esthetic results. However, long-term studies are required to guarantee a satisfactory long-term outcome of this modality of treatment. This case report describes the clinical and technical procedures involved in fabrication of maxillary and mandibular implant-supported fixed prostheses using monolithic zirconia as a treatment of edentulism, and proposes the possible advantages associated with using monolithic zirconia in eliminating dissimilar interfaces in such prostheses that are accountable for the most commonly occurring technical complication for these prostheses being chipping and fracture of the veneering material. © 2015 Wiley Periodicals, Inc.

  19. Biofilm formation on voice prostheses : Influence of dairy products in vitro

    NARCIS (Netherlands)

    Free, RH; Van der Mei, HC; Dijk, F; Van Weissenbruch, R; Busscher, HJ; Albers, FWJ

    2001-01-01

    Laryngectomized patients use silicone rubber voice prostheses to regain their speech: however. the lifetime of these devices is limited due to biofilm formation. Following anecdotal evidence. the influence of various dairy products on biofilm formation on voice prostheses was studied, using the

  20. In vivo fragmentation of microporous polyurethane- and copolyester elastomer-based vascular prostheses

    NARCIS (Netherlands)

    Hinrichs, W.L.J.; Hinrichs, W.L.J.; Kuit, J.; Feil, H.; Feil, H.; Wildevuur, Ch.R.H.; Feijen, Jan

    1992-01-01

    A previous study showed that microporous, compliant and (bio)degradable vascular prostheses prepared from a polyurethane/poly(-lactic acid) mixture can function as a temporary scaffold for the regeneration of small-calibre arteries. In this study the mechanism of fragmentation of vascular prostheses

  1. Movement characteristics of upper extremity prostheses during basic goal-directed tasks

    NARCIS (Netherlands)

    Bouwsema, Hanneke; van der Sluis, Corry K.; Bongers, Raoul M.

    Background: After an upper limb amputation a prosthesis is often used to restore the functionality. However, the frequency of prostheses use is generally low. Movement kinematics of prostheses use might suggest origins of this low use. The aim of this study was to reveal movement patterns of

  2. Differences in aerodynamic characteristics of new and dysfunctional Provox (R) 2 voice prostheses in vivo

    NARCIS (Netherlands)

    Schwandt, LQ; Tjong-Ayong, HJ; van Weissenbruch, R; der Mei, HC; Albers, FWJ

    Tracheoesophageal voice prostheses need to be replaced due to increased airflow resistance or retrograde leakage of fluid into the trachea as a consequence of biofilm formation. Previous in vitro studies show a change of aerodynamic features of biofilm covered voice prostheses after removal of the

  3. Air-flow resistances of silicone rubber voice prostheses after formation of bacterial and fungal biofilms

    NARCIS (Netherlands)

    Elving, GJ; van der Mei, HC; Busscher, HJ; van Weissenbruch, R; Albers, FWJ

    Laryngectomized patients use silicone rubber voice prostheses to rehabilitate their voice. However, biofilm formation limits the lifetime of voice prostheses by causing leakage or an increased air-flow resistance and the prosthesis has to be replaced. To determine which bacterial or yeast strains,

  4. Seeding neural progenitor cells on silicon-based neural probes.

    Science.gov (United States)

    Azemi, Erdrin; Gobbel, Glenn T; Cui, Xinyan Tracy

    2010-09-01

    Chronically implanted neural electrode arrays have the potential to be used as neural prostheses in patients with various neurological disorders. While these electrodes perform well in acute recordings, they often fail to function reliably in clinically relevant chronic settings because of glial encapsulation and the loss of neurons. Surface modification of these implants may provide a means of improving their biocompatibility and integration within host brain tissue. The authors proposed a method of improving the brain-implant interface by seeding the implant's surface with a layer of neural progenitor cells (NPCs) derived from adult murine subependyma. Neural progenitor cells may reduce the foreign body reaction by presenting a tissue-friendly surface and repair implant-induced injury and inflammation by releasing neurotrophic factors. In this study, the authors evaluated the growth and differentiation of NPCs on laminin-immobilized probe surfaces and explored the potential impact on transplant survival of these cells. Laminin protein was successfully immobilized on the silicon surface via covalent binding using silane chemistry. The growth, adhesion, and differentiation of NPCs expressing green fluorescent protein (GFP) on laminin-modified silicon surfaces were characterized in vitro by using immunocytochemical techniques. Shear forces were applied to NPC cultures in growth medium to evaluate their shearing properties. In addition, neural probes seeded with GFP-labeled NPCs cultured in growth medium for 14 days were implanted in murine cortex. The authors assessed the adhesion properties of these cells during implantation conditions. Moreover, the tissue response around NPC-seeded implants was observed after 1 and 7 days postimplantation. Significantly improved NPC attachment and growth was found on the laminin-immobilized surface compared with an unmodified control before and after shear force application. The NPCs grown on the laminin-immobilized surface

  5. Development of accurate mass spectrometric routine and reference methods for the determination of trace amounts of iridium and rhodium in photographic emulsionsf

    NARCIS (Netherlands)

    Krystek, Petra; Heumann, Klaus G.

    1999-01-01

    For the determination of trace amounts of iridium and rhodium in photographic emulsions different sample treatment procedures were coupled with inductively coupled plasma mass spectrometry (ICP-MS) and, for iridium, also with negative thermal ionisation isotope dilution mass spectrometry (NTI-IDMS)

  6. Occupational allergic contact dermatitis caused by exposure to acrylates during work with dental prostheses.

    Science.gov (United States)

    Kanerva, L; Estlander, T; Jolanki, R; Tarvainen, K

    1993-05-01

    Between 1974 and 1992, we were consulted by 4 patients (an orthodontist, 2 dental technicians and a dental worker trained in-house) who had developed occupational allergic contact dermatitis from working with dental prostheses. All patients had positive allergic patch test reactions to methyl methacrylate (MMA), the acrylate which is the most widely used in work with prostheses. All but the orthodontist also reacted to dimethacrylates, which are used in cross-linked dental prostheses. The last patient, investigated in 1992, had been exposed mainly to light-cured acrylics, which are similar in composition to dental composite resins. These acrylics, only recently introduced into prosthetic work, contain more potent acrylic sensitizers than MMA. Accordingly, dental personnel working with prostheses may face a higher risk of sensitization than previously. To detect cases of occupational allergic contact dermatitis, we suggest that patients working with dental prostheses should be patch tested with MMA, 2-hydroxyethyl methacrylate, dimethacrylates, epoxy acrylates and urethane acrylates.

  7. Study of neutron deficient iridium isotopes by using laser spectroscopy; Etude des noyaux d'iridium deficients en neutrons par spectroscopie laser

    Energy Technology Data Exchange (ETDEWEB)

    Verney, D

    2000-12-19

    Resonance ionization spectroscopy was performed on neutron deficient iridium isotopes {sup 182-189}Ir, {sup 186}Ir{sup m} and stable isotopes {sup 191,193}Ir. Hyperfine spectra were recorded from the optical transition at 351,7 nm between the 5d{sup 7}6s{sup 2} {sup 4}F{sub 9/2} ground state and the 5d{sup 7}6s6p {sup 6}F{sub 11/2} excited state. Radioactive iridium isotopes were obtained from {beta}{sup +}/EC decay of radioactive mercury nuclei deposited on a graphite substrate. The radioactive mercury nuclei were produced at the ISOLDE facility at CERN through spallation reactions, by bombarding a molten lead target with the 1 GeV proton beam delivered by the PS-Booster. Magnetic dipole moments and spectroscopic quadrupole moments were extracted from the hyperfine spectra. The mean square charge radius variations, as deduced from the measured isotopic shift, show a sharp change between {sup 187}Ir and {sup 186}Ir{sup g}, accompanied by a sudden increase in deformation: from {beta}2 {approx} 0,16 to {beta}2 > 0, 2. These results were analysed in the framework of an axial rotor plus one or two quasiparticles. The wave functions of the osmium and platinum cores which are used in order to describe the iridium nuclei were calculated from the HF+BCS method with the Skyrme SIII effective interaction. The cores were constrained to take the deformation parameters extracted from the isotopic shift measurements. One shows then that this sudden deformation change corresponds also to a change in the proton state that describes the odd nuclei ground state or that participates in the coupling with the neutron in odd-odd nuclei. This state is identified with the {pi}3/2{sup +}[402] orbital for the smaller deformations nuclei and with the {pi}1/2{sup -}[541] orbital stemming from the h{sub 9/2} subshell for bigger deformations nuclei. (author)

  8. Neural engineering from advanced biomaterials to 3D fabrication techniques

    CERN Document Server

    Kaplan, David

    2016-01-01

    This book covers the principles of advanced 3D fabrication techniques, stem cells and biomaterials for neural engineering. Renowned contributors cover topics such as neural tissue regeneration, peripheral and central nervous system repair, brain-machine interfaces and in vitro nervous system modeling. Within these areas, focus remains on exciting and emerging technologies such as highly developed neuroprostheses and the communication channels between the brain and prostheses, enabling technologies that are beneficial for development of therapeutic interventions, advanced fabrication techniques such as 3D bioprinting, photolithography, microfluidics, and subtractive fabrication, and the engineering of implantable neural grafts. There is a strong focus on stem cells and 3D bioprinting technologies throughout the book, including working with embryonic, fetal, neonatal, and adult stem cells and a variety of sophisticated 3D bioprinting methods for neural engineering applications. There is also a strong focus on b...

  9. [Application of negative molds technology based on three-dimensional printing in digital maxillofacial prostheses].

    Science.gov (United States)

    Gu, X Y; Chen, X B; Jiao, T; Zhang, F Q; Jiang, X Q

    2017-06-09

    Objective: To explore a digital negative molds technique based on three-dimensional (3D) printing to assist in the manufacture of maxillofacial prostheses, and to improve the deficiency of the current clinical treatment. Methods: Seventeen patients with maxillofacial defects (including nasal defects, orbital defects, cheek defects, auricle defect) were scanned by means of facial optical scanning and computer tomography (CT). The 3D models were then reconstructed and global registration was made to merge the reconstructed models into a new digital model for 3D design. The 3D design of the prostheses was implemented in software. The mechanical connection structure was designed by forward engineering technology for 3 patients with intra-oral defects in maxilla who needed to make removable partial dentures, so that the silicone prostheses and removable partial denture could be combined. The removable partial dentures were made by conventional method and connected with the prostheses. According to the 3D data of the prostheses, the digital negative molds were designed, and the 3D printing technology was used to finish the processing of the resin molds. Silicone for prostheses were filled and cured in the resin molds to fabricate the clinical restorations for the patients. The margin adaptation and retention of the prostheses was detected. Results: Twenty patients with varying degrees of maxillofacial defects were rehabilitated using the courses developed in the study. All patients reported no pain or discomfort during the treatment; and they were satisfied with the final prostheses of the shape, color, retention, stability, etc. Eighteen of the prostheses showed good marginal adaptation, and sixteen of the prostheses showed good retention effect. Conclusions: The digital negative molds technique used in this study could greatly reduce the intensity of manual operation and provided a good therapeutic effect for patients with maxillofacial defects.

  10. Oral Implant-Prostheses: New Teeth for a Brighter Brain.

    Directory of Open Access Journals (Sweden)

    Vincenzo De Cicco

    Full Text Available Several studies have demonstrated that chewing can be regarded as a preventive measure for cognitive impairment, whereas masticatory deficiency, associated with soft-diet feeding, is a risk factor for the development of dementia. At present the link between orofacial sensorimotor activity and cognitive functions is unknown. In subjects with unilateral molar loss we have shown asymmetries in both pupil size and masticatory muscles electromyographic (EMG activity during clenching: the molar less side was characterized by a lower EMG activity and a smaller pupil. Since implant-prostheses, greatly reduced both the asymmetry in EMG activity and in pupil's size, trigeminal unbalance, leading to unbalance in the activity of the Locus Coeruleus (LC, may be responsible for the pupil's asymmetry. According to the findings obtained in animal models, we propose that the different activity of the right and left LC may induce an asymmetry in brain activity, thus leading to cognitive impairment. According to this hypothesis, prostheses improved the performance in a complex sensorimotor task and increased the mydriasis associated with haptic tasks. In conclusion, the present study indicates that the implant-prosthesis therapy, which reduces the unbalance of trigeminal proprioceptive afferents and the asymmetry in pupil's size, may improve arousal, boosting performance in a complex sensorimotor task.

  11. Rotational constraint in posterior-stabilized total knee prostheses.

    Science.gov (United States)

    Klein, R; Serpe, L; Kester, M A; Edidin, A; Fishkin, Z; Mahoney, O M; Schmalzried, T P

    2003-05-01

    Rotational stresses from box-post impingement have been implicated in the loosening of posterior-stabilized total knee prostheses. A bench model was constructed to assess the forces generated by tibiofemoral rotation. Rotational torque under load was measured in two different posteriorstabilized total knee prostheses using an axial-torsion load cell at 0 degrees, 20 degrees, and 40 degrees flexion over 20 degrees internal and external rotation. The Sigma posterior-stabilized prosthesis generated little torque through 5 degrees internal and external rotation. An increase in torque then occurred because of box-post impingement, generating peak torques of 17 to 18 N-m at 12 degrees to 14 degrees rotation. The bench model produced the same deformation of the polyethylene post as seen on retrieved specimens. The Scorpio posterior-stabilized prosthesis had a relatively continuous rise in generated torque from tibiofemoral conformity. Box-post impingement did not occur resulting in 32% lower torque between 12 degrees and 14 degrees rotation. Peak rotational torques of 15 to 16 N-m were reached at 19 degrees to 20 degrees rotation. Tibiofemoral conformity is the primary source of rotational constraint. Box-post impingement can be a source of additional rotational constraint. Depending on specific design features, small changes in relative tibiofemoral component rotation can more than double the generated torque. Axial rotation of the knee in vivo can generate substantial torque. Relative tibiofemoral rotational position is an important factor influencing component function and fixation.

  12. Iridium nanoparticles supported on hierarchical porous N-doped carbon: an efficient water-tolerant catalyst for bio-alcohol condensation in water

    Science.gov (United States)

    Liu, Di; Chen, Xiufang; Xu, Guoqiang; Guan, Jing; Cao, Quan; Dong, Bo; Qi, Yunfei; Li, Chunhu; Mu, Xindong

    2016-02-01

    Nitrogen-doped hierarchical porous carbons were synthesized successfully by a controllable one-pot method using glucose and dicyandiamide as carbon source and nitrogen source via hydrothermal carbonization process. The nitrogen-doped materials, possessing high nitrogen content (up to 7 wt%), large surface area (>320 m2 g-1) and excellent hierarchical nanostructure, were employed as catalyst supports for immobilization of iridium nanoparticles for bio-alcohol condensation in water. The introduction of nitrogen atoms into the carbon framework significantly improved iridium nanoparticles dispersion and stabilization. The novel iridium catalysts exhibited superior catalytic activity in the aqueous phase condensation of butanol, offering high butanol conversion of 45% with impressive 2-ethylhexanol selectivity of 97%. The heterogeneous catalysts had great advantages of easy recovery and high catalytic stability. The outstanding catalytic performance could be attributed to excellent dispersion of iridium nanoparticles, stronger iridium-support interactions and interaction of nitrogen species with alcohol substrates.

  13. Nuclear resonance scattering study of iridates, iridium and antimony based pyrochlores

    Energy Technology Data Exchange (ETDEWEB)

    Alexeev, P.

    2017-04-15

    This thesis shows the first synchrotron-based Moessbauer spectroscopy studies on iridium containing compounds and first vibrational spectroscopy on Sb containing compounds carried out at the P01 beamline of PETRA III. In this context, two types of X-ray monochromators have been developed: a monochromator for 73 keV photons with medium energy resolution, and a high-resolution backscattering monochromator based on a sapphire crystal. The monochromator for 73 keV X-rays is the key instrument for hyperfine spectroscopy on Iridium compounds, while the sapphire backscattering monochromator is purposed to vibrational spectroscopy on any Moessbauer resonances with the transition energies in the 20-50 keV range. Additionally, the signal detection for nuclear resonance scattering experiments at the beamline was significantly improved during this work, inspired by the high energies and low lifetimes of the employed resonances. The first synchrotron-based hyperfine spectroscopy on Iridium-containing compounds was demonstrated by NRS on 73 keV resonance in {sup 193}Ir. The results can be interpreted by dynamical theory of nuclear resonance scattering. In this work, special emphasis is set onto the electronic and magnetic properties of Ir nuclei in IrO{sub 2} and in Ruddlesden-Popper (RP) phases of strontium iridates Sr{sub n+1}Ir{sub n}O{sub 3n+1} (n=0,1). These systems are well-suited for studies with X-ray scattering techniques, since the scattered signal contains vast information about the widely tunable crystallographic and electronic structure of these systems; furthermore, studies with X-rays are less limited by absorption from iridium as it is the case for neutron scattering experiments. The hyperfine parameters in IrO{sub 2}, SrIrO{sub 3} and Sr{sub 2}IrO{sub 4} have been measured via Nuclear Forward Scattering for the first time. Using the dynamical theory of NRS, the temperature and magnetic field dependence of the electric field gradient and magnetic hyperfine field

  14. Techniques for Achieving Zero Stress in Thin Films of Iridium, Chromium, and Nickel

    Science.gov (United States)

    Broadway, David M.; O'Dell, Stephen L.; Ramsey, Brian D.; Weimer, Jeffrey

    2015-01-01

    We examine techniques for achieving zero intrinsic stress in thin films of iridium, chromium, and nickel deposited by magnetron sputter deposition. The intrinsic stress is further correlated to the microstructural features and physical properties such as surface roughness and optical density at a scale appropriate to soft X-ray wavelengths. The examination of the stress in these materials is motivated by efforts to advance the optical performance of light-weight X-ray space telescopes into the regime of sub-arcsecond resolution through various deposition techniques that rely on control of the film stress to values within 10-100 MPa. A characteristic feature of the intrinsic stress behavior in chromium and nickel is their sensitivity to the magnitude and sign of the intrinsic stress with argon gas pressure and deposition rate, including the existence of a critical argon process pressure that results in zero film stress which scales linearly with the atomic mass of the sputtered species. While the effect of stress reversal with argon pressure has been previously reported by Hoffman and others for nickel and chromium, we report this effect for iridium. In addition to stress reversal, we identify zero stress in the optical functioning iridium layer shortly after island coalescence for low process pressures at a film thickness of approximately 35nm. The measurement of the low values of stress during deposition was achieved with the aid of a sensitive in-situ instrument capable of a minimum detectable level of stress, assuming a 35nm thick film, in the range of 0.40-6.0 MPa for oriented crystalline silicon substrate thicknesses of 70-280 microns, respectively.

  15. Synthesis and structural studies of Cp{sup *} rhodium and Cp{sup *} iridium complexes of picolinic hydrazine ligand

    Energy Technology Data Exchange (ETDEWEB)

    Palepu, Narasinga Rao; Kollipara, Mohan Rao [Centre for Advanced Studies in Chemistry, North-Eastern Hill University, Shillong (India); Kaminsky Werner [Dept. of Chemistry, University of Washington, Seattle (United States)

    2017-01-15

    A series of Cp{sup *}Rh and Cp{sup *}Ir complexes of picolinic hydrazine ligand are synthesized and characterized. Picolinic hydrazine has yielded only dinuclear complexes in the case of rhodium metal whereas both mono and dinuclear complexes with iridium metal. Iridium complexes are formed as quaternary salts by the migration of the N–H proton onto the adjacent amine group of the hydrazine after binding to the metal. Picolinic hydrazine acts as nitrogen and oxygen donor ligand in the form of bi and tetradentate bonding modes.

  16. A colorimetric and luminescent dual-modal assay for Cu(II ion detection using an iridium(III complex.

    Directory of Open Access Journals (Sweden)

    Dik-Lung Ma

    Full Text Available A novel iridium(III complex-based chemosensor bearing the 5,6-bis(salicylideneimino-1,10-phenanthroline ligand receptor was developed, which exhibited a highly sensitive and selective color change from colorless to yellow and a visible turn-off luminescence response upon the addition of Cu(II ions. The interactions of this iridium(III complex with Cu2+ ions and thirteen other cations have been investigated by UV-Vis absorption titration, emission titration, and 1H NMR titration.

  17. Preparation of boron doped diamond modified by iridium for electroreduction of carbon dioxide (CO2)

    Science.gov (United States)

    Ichzan, A. M.; Gunlazuardi, J.; Ivandini, T. A.

    2017-04-01

    Electroreduction of carbon dioxide (CO2) at iridium oxide-modified boron-doped diamond (IrOx-BDD) electrodes in aqueous electrolytes was studied by voltammetric method. The aim of this study was to find out the catalytic effect of IrOx to produce fine chemicals contained of two or more carbon atoms (for example acetic acid) in high percentage. Characterization using FE-SEM and XPS indicated that IrO2 can be deposited at BDD electrode, whereas characterization using cyclic voltammetry indicated that the electrode was applicable to be used as working electrode for CO2 electroreduction.

  18. A colorimetric chemosensor for Cu2+ ion detection based on an iridium(III) complex

    Science.gov (United States)

    Wang, Modi; Leung, Ka-Ho; Lin, Sheng; Chan, Daniel Shiu-Hin; Kwong, Daniel W. J.; Leung, Chung-Hang; Ma, Dik-Lung

    2014-01-01

    We report herein the synthesis and application of a series of novel cyclometalated iridium(III) complexes 1−3 bearing a rhodamine-linked NˆN ligand for the detection of Cu2+ ions. Under the optimised conditions, the complexes exhibited high sensitivity and selectivity for Cu2+ ions over a panel of other metal ions, and showed consistent performance in a pH value range of 6 to 8. Furthermore, the potential application of this system for the monitoring of Cu2+ ions in tap water or natural river water samples was demonstrated. PMID:25348724

  19. Enantioselective Synthesis of Acyclic α-Quaternary Carboxylic Acid Derivatives through Iridium-Catalyzed Allylic Alkylation.

    Science.gov (United States)

    Shockley, Samantha E; Hethcox, J Caleb; Stoltz, Brian M

    2017-09-11

    The first highly enantioselective iridium-catalyzed allylic alkylation that provides access to products bearing an allylic all-carbon quaternary stereogenic center has been developed. The reaction utilizes a masked acyl cyanide (MAC) reagent, which enables the one-pot preparation of α-quaternary carboxylic acids, esters, and amides with a high degree of enantioselectivity. The utility of these products is further explored through a series of diverse product transformations. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Neural prostheses for vision: designing a functional interface with retinal neurons.

    Science.gov (United States)

    Hetling, John R; Baig-Silva, Monica S

    2004-01-01

    A number of prevalent eye diseases exist which may lead to partial or total blindness, and for which there are currently no cures or means by which to restore lost sight. Based on recent progress, it has become apparent that artificial prosthetic devices, which would use electrical stimulation of neurons in the visual pathway to elicit visual percepts, are likely to some day become a viable treatment for patients blinded by these diseases. A number of recent scientific reviews have summarized general functional electrical stimulation (FES) approaches related to the visual system, and many of the technical considerations regarding fabrication, biocompatibility, stimulation thresholds and electrotoxicity. This review will address a principal outstanding question in retinal prosthesis development: the design and implementation of a functional interface with the retina. A functional interface between electrodes and retinal neurons will be stable, biocompatible, and will convey useful information to the visual system. Several parameters related to both the artificial and biological aspects of the interface must be considered; this paper will emphasize electrode design. Additional issues central to the development of prosthesis interface design, including retinal physiology, eye diseases, and existing animal models of retinal degeneration, are also summarized.

  1. A prospective evaluation of zirconia anterior partial fixed dental prostheses: Clinical results after seven years.

    Science.gov (United States)

    Solá-Ruíz, Maria Fernanda; Agustin-Panadero, Rubén; Fons-Font, Antonio; Labaig-Rueda, Carlos

    2015-06-01

    Because of the high mechanical strength of zirconium dioxide, the metal in fixed partial prostheses can now be replaced. However, the material is susceptible to aging or hydrothermal degradation and to chipping of the feldspathic veneer. The purpose of this prospective study was to evaluate the survival (without failure) and success (survival without any complication or failure) rate and clinical efficacy of anterior zirconia partial fixed dental prostheses. Twenty-seven anterior partial fixed dental prostheses of 3 to 6 units were fabricated. All participants were examined after 1 month and 6 months, then annually for 7 years. Three partial fixed dental prostheses failed and had to be removed: 2 because of secondary caries, which increased failure significantly (P=.001) and 1 because of severe chipping. Six partial fixed dental prostheses had complications: 2 debonded, 3 had chipping, and 1 had periapical pathology. All veneer porcelain fractures occurred in 6-unit fixed partial prostheses (P=.002). The clinical success rate was 88.8% after the 7-year follow-up. The clinical behavior of partial fixed dental prostheses with a zirconium dioxide core in the anterior region provides an adequate medium-term survival rate. The main cause of failure was secondary caries. The most frequent complication was chipping, which was directly related to the number of units of the prosthesis. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  2. Prediction and control of neural responses to pulsatile electrical stimulation

    Science.gov (United States)

    Campbell, Luke J.; Sly, David James; O'Leary, Stephen John

    2012-04-01

    This paper aims to predict and control the probability of firing of a neuron in response to pulsatile electrical stimulation of the type delivered by neural prostheses such as the cochlear implant, bionic eye or in deep brain stimulation. Using the cochlear implant as a model, we developed an efficient computational model that predicts the responses of auditory nerve fibers to electrical stimulation and evaluated the model's accuracy by comparing the model output with pooled responses from a group of guinea pig auditory nerve fibers. It was found that the model accurately predicted the changes in neural firing probability over time to constant and variable amplitude electrical pulse trains, including speech-derived signals, delivered at rates up to 889 pulses s-1. A simplified version of the model that did not incorporate adaptation was used to adaptively predict, within its limitations, the pulsatile electrical stimulus required to cause a desired response from neurons up to 250 pulses s-1. Future stimulation strategies for cochlear implants and other neural prostheses may be enhanced using similar models that account for the way that neural responses are altered by previous stimulation.

  3. Double-crown-retained removable dental prostheses: a retrospective study of survival and complications.

    Science.gov (United States)

    Schwindling, Franz Sebastian; Dittmann, Britta; Rammelsberg, Peter

    2014-09-01

    Research data are scarce on double-crown-retained removable dental prostheses. In double-crown-retained removable dental prostheses, crown-like copings are definitively cemented to the abutment teeth and serve as prosthesis attachments. The purpose of this study was to evaluate the survival of double-crown-retained removable dental prostheses in use for 7 years and to determine their most common complications. A retrospective analysis was conducted to investigate the clinical outcome of 117 prostheses in 86 patients with 385 abutment teeth. Thirty-two telescopic-crown-retained removable dental prostheses, 51 conical-crown-retained removable dental prostheses, and 34 resilient telescopic-crown-retained overdentures were clinically reexamined by 1 investigator. Prosthesis success was defined as survival without severe complications (abutment tooth extraction). Statistical analyses were performed with Kaplan-Meier modeling and Cox regression (α=.05). Minor complications, for example, the decementation of primary crowns (34.2%), failure of the veneer of secondary crowns (11.1%), fracture of the denture base (17.1%), and the need for relining (12%), were common. Cumulative prosthesis survival for all types of prostheses was 93.8% after 7 years. After the same period, prosthesis success was 90% for telescopic-crown-retained removable dental prostheses and 78.5% for conical-crown-retained removable dental prostheses and resilient telescopic-crown-retained overdentures. The medium-term double-crown-retained removable dental prosthesis survival found in this retrospective investigation appears acceptable. When bearing in mind the limits of this study, this kind of prosthesis might be a viable treatment option for patients with a reduced dentition. However, more laboratory and clinical research is necessary to reduce the incidence of minor complications and confirm the present in vivo results in larger patient groups. Copyright © 2014 Editorial Council for the Journal of

  4. International comparative evaluation of knee replacement with fixed or mobile-bearing posterior-stabilized prostheses.

    Science.gov (United States)

    Graves, Stephen; Sedrakyan, Art; Baste, Valborg; Gioe, Terence J; Namba, Robert; Martínez Cruz, Olga; Stea, Susanna; Paxton, Elizabeth; Banerjee, Samprit; Isaacs, Abby J; Robertsson, Otto

    2014-12-17

    Posterior-stabilized total knee prostheses were introduced to address instability secondary to loss of posterior cruciate ligament function, and they have either fixed or mobile bearings. Mobile bearings were developed to improve the function and longevity of total knee prostheses. In this study, the International Consortium of Orthopaedic Registries used a distributed health data network to study a large cohort of posterior-stabilized prostheses to determine if the outcome of a posterior-stabilized total knee prosthesis differs depending on whether it has a fixed or mobile-bearing design. Aggregated registry data were collected with a distributed health data network that was developed by the International Consortium of Orthopaedic Registries to reduce barriers to participation (e.g., security, proprietary, legal, and privacy issues) that have the potential to occur with the alternate centralized data warehouse approach. A distributed health data network is a decentralized model that allows secure storage and analysis of data from different registries. Each registry provided data on mobile and fixed-bearing posterior-stabilized prostheses implanted between 2001 and 2010. Only prostheses associated with primary total knee arthroplasties performed for the treatment of osteoarthritis were included. Prostheses with all types of fixation were included except for those with the rarely used reverse hybrid (cementless tibial and cemented femoral components) fixation. The use of patellar resurfacing was reported. The outcome of interest was time to first revision (for any reason). Multivariate meta-analysis was performed with linear mixed models with survival probability as the unit of analysis. This study includes 137,616 posterior-stabilized knee prostheses; 62% were in female patients, and 17.6% had a mobile bearing. The results of the fixed-effects model indicate that in the first year the mobile-bearing posterior-stabilized prostheses had a significantly higher hazard

  5. Running-specific prostheses limit ground-force during sprinting

    Science.gov (United States)

    Grabowski, Alena M.; McGowan, Craig P.; McDermott, William J.; Beale, Matthew T.; Kram, Rodger; Herr, Hugh M.

    2010-01-01

    Running-specific prostheses (RSP) emulate the spring-like behaviour of biological limbs during human running, but little research has examined the mechanical means by which amputees achieve top speeds. To better understand the biomechanical effects of RSP during sprinting, we measured ground reaction forces (GRF) and stride kinematics of elite unilateral trans-tibial amputee sprinters across a range of speeds including top speed. Unilateral amputees are ideal subjects because each amputee's affected leg (AL) can be compared with their unaffected leg (UL). We found that stance average vertical GRF were approximately 9 per cent less for the AL compared with the UL across a range of speeds including top speed (p amputee sprinters. We infer that RSP impair force generation and thus probably limit top speed. Some elite unilateral trans-tibial amputee sprinters appear to have learned or trained to compensate for AL force impairment by swinging both legs rapidly. PMID:19889694

  6. Tympanic-ossicular prostheses and MEMS technology: whats and whys.

    Science.gov (United States)

    Urquiza, Rafael; López, Javier; Gonzalez-Herrera, Antonio; Povedano, Valerio; Ciges, Miguel

    2009-04-01

    Microelectromechanical systems (MEMS) technology fulfils the requirements of implantable middle ear devices and consequently it becomes an excellent option to design and develop the related transducers. To present a summarized overview of the fundamentals of mechanical technologies in relation to middle ear implants research. Analysis of the possibilities, limitations and practical applications of MEMS as regards the research, development, transference and fabrication processes. MEMS is a new technology with the potential to develop small integrated mechanical and electronic systems that share many processes of integrated circuits technology and its wide application potential. Middle ear prostheses are essentially special implantable transducers that mimic the properties of the tympano-ossicular system: electromechanical systems that deliver low energy pulses safely and efficiently into the labyrinth fluids. They primarily require: active mechanisms to preclude potential damage levels; minimum energy consumption; adequate dimensions for the middle ear; and biotolerable materials. Additionally, development and translational aspects of the selected technology are of utmost importance in this field.

  7. Bionic balance organs: progress in the development of vestibular prostheses.

    Science.gov (United States)

    Smith, Paul F

    2017-09-01

    The vestibular system is a sensory system that is critically important in humans for gaze and image stability as well as postural control. Patients with complete bilateral vestibular loss are severely disabled and experience a poor quality of life. There are very few effective treatment options for patients with no vestibular function. Over the last 10 years, rapid progress has been made in developing artificial 'vestibular implants' or 'prostheses', based on cochlear implant technology. As of 2017, 13 patients worldwide have received vestibular implants and the results are encouraging. Vestibular implants are now becoming part of an increasing effort to develop artificial, bionic sensory systems, and this paper provides a review of the progress in this area.

  8. Good occlusal practice in the provision of implant borne prostheses.

    Science.gov (United States)

    Davies, S J; Gray, R J M; Young, M P J

    2002-01-26

    The increased use of endosseous dental implants means that many dentists will encounter patients with dental implants in their everyday practice. Dental practitioners might be actively involved in the provision of implant borne prostheses at both the surgical and restorative phases, or only at the restorative stage. This section is written for all dentists and aims to examine the subject of occlusion within implantology. It aims to provide guidelines of good occlusal practice to be used in the design of the prosthesis that is supported or retained by one or more implants. As implantology is a 'new' discipline of dentistry, there are fewer standard texts and this section, therefore, is much more extensively referenced than the subjects that have been considered to date.

  9. Development of speech prostheses: current status and recent advances.

    Science.gov (United States)

    Brumberg, Jonathan S; Guenther, Frank H

    2010-09-01

    Brain-computer interfaces (BCIs) have been developed over the past decade to restore communication to persons with severe paralysis. In the most severe cases of paralysis, known as locked-in syndrome, patients retain cognition and sensation, but are capable of only slight voluntary eye movements. For these patients, no standard communication method is available, although some can use BCIs to communicate by selecting letters or words on a computer. Recent research has sought to improve on existing techniques by using BCIs to create a direct prediction of speech utterances rather than to simply control a spelling device. Such methods are the first steps towards speech prostheses as they are intended to entirely replace the vocal apparatus of paralyzed users. This article outlines many well known methods for restoration of communication by BCI and illustrates the difference between spelling devices and direct speech prediction or speech prosthesis.

  10. Running-specific prostheses limit ground-force during sprinting.

    Science.gov (United States)

    Grabowski, Alena M; McGowan, Craig P; McDermott, William J; Beale, Matthew T; Kram, Rodger; Herr, Hugh M

    2010-04-23

    Running-specific prostheses (RSP) emulate the spring-like behaviour of biological limbs during human running, but little research has examined the mechanical means by which amputees achieve top speeds. To better understand the biomechanical effects of RSP during sprinting, we measured ground reaction forces (GRF) and stride kinematics of elite unilateral trans-tibial amputee sprinters across a range of speeds including top speed. Unilateral amputees are ideal subjects because each amputee's affected leg (AL) can be compared with their unaffected leg (UL). We found that stance average vertical GRF were approximately 9 per cent less for the AL compared with the UL across a range of speeds including top speed (p amputee sprinters. We infer that RSP impair force generation and thus probably limit top speed. Some elite unilateral trans-tibial amputee sprinters appear to have learned or trained to compensate for AL force impairment by swinging both legs rapidly.

  11. Study of dental prostheses influence in radiation therapy.

    Science.gov (United States)

    De Conto, C; Gschwind, R; Martin, E; Makovicka, L

    2014-02-01

    Dental prostheses made of high density material contribute to modify dose distribution in head and neck cancer treatment. Our objective is to quantify dose perturbation due to high density inhomogeneity with experimental measurements and Monte Carlo simulations. Firstly, measurements were carried in a phantom representing a human jaw with thermoluminescent detectors (GR200A) and EBT2 Gafchromic films in the vicinity of three samples: a healthy tooth, a tooth with amalgam and a Ni-Cr crown, irradiated in clinical configuration. Secondly, Monte Carlo simulations (BEAMnrc code) were assessed in an identical configuration. Experimental measurements and simulation results confirm the two well-known phenomena: firstly the passage from a low density medium to a high density medium induces backscattered electrons causing a dose increase at the interface, and secondly, the passage from a high density medium to a low density medium creates a dose decrease near the interface. So, the results show a 1.4% and 23.8% backscatter dose rise and attenuation after sample of 26.7% and 10.9% respectively for tooth with amalgam and crown compared to the healthy tooth. Although a tooth with amalgam has a density of about 12-13, the changes generated are not significant. However, the results for crown (density of 8) are very significant and the discordance observed may be due to calculation point size difference 0.8 mm and 0.25 mm respectively for TLD and Monte Carlo. The use of Monte Carlo simulations and experimental measurements provides objective evidence to evaluate treatment planning system results with metal dental prostheses. Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  12. A Nonsurgical Approach to Adolescent Breast Asymmetry Using External Prostheses.

    Science.gov (United States)

    Pike, Carolyn M; Firriolo, Joseph M; Ontiveros, Nicole C; Kuchibhotla, Sarada P; Oppel, Olivia K; Monoxelos, Lauren C; Greene, Arin K; Labow, Brian I

    2017-08-01

    Currently, there are few nonsurgical treatment options for pediatric patients with developmental breast asymmetry. Our group established a partnership with a prosthetic unit within a local oncology center to provide custom-fit breast prostheses for young women with breast asymmetry. The purpose of this study was to describe the effect of this experience on patients' self-esteem and body image. Patients were administered an anonymous satisfaction survey at least 1 month after their first fitting at the prosthetic unit. The survey was designed to evaluate body image, self-esteem, as well as social and emotional well-being before and after treatment. Thematic analysis was used to assess their experiences. Seventeen patients, aged 12-19 years, visited the prosthetic unit and subsequently completed the retrospective survey. After using the breast prostheses, 14 (82.4%) patients reported an improvement in body image and 12 (70.6%) patients reported an improvement in self-esteem. Benefits pertaining to three emergent themes were revealed: "body wholeness/symmetry," "body image and psychological well-being," and "esthetic outcome." Results from the survey demonstrate the ease and efficacy of a form of nonsurgical treatment for adolescent breast asymmetry. Our partnership with an adult oncology center can serve as a national model to support the development of similar treatment programs. Existing resources that have been previously used only for adult breast cancer survivors can be effectively applied to the adolescent population to ameliorate the negative psychological effects of breast asymmetry. Copyright © 2017 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

  13. Investigation of Timing to Switch Control Mode in Powered Knee Prostheses during Task Transitions.

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    Full Text Available Current powered prosthetic legs require switching control modes according to the task the user is performing (e.g. level-ground walking, stair climbing, walking on slopes, etc.. To allow prosthesis users safely and seamlessly transition between tasks, it is critical to determine when to switch the prosthesis control mode during task transitions. Our previous study defined critical timings for different types of task transitions in ambulation; however, it is unknown whether it is the unique timing that allows safe and seamless transitions. The goals of this study were to (1 systematically investigate the effects of mode switch timing on the prosthesis user's performance in task transitions, and (2 identify appropriate timing to switch the prosthesis control mode so that the users can seamlessly transition between different locomotion tasks. Five able-bodied (AB and two transfemoral (TF amputee subjects were tested as they wore a powered knee prosthesis. The prosthesis control mode was switched manually at various times while the subjects performed different types of task transitions. The subjects' task transition performances were evaluated by their walking balance and success in performing seamless task transitions. The results demonstrated that there existed a time window within which switching the prosthesis control mode neither interrupted the subjects' task transitions nor disturbed their walking balance. Therefore, the results suggested the control mode switching of a lower limb prosthesis can be triggered within an appropriate time window instead of a specific timing or an individual phase. In addition, a generalized criterion to determine the appropriate mode switch timing was proposed. The outcomes of this study could provide important guidance for future designs of neurally controlled powered knee prostheses that are safe and reliable to use.

  14. Iridium nanoparticles with high catalytic activity in degradation of acid red-26: an oxidative approach.

    Science.gov (United States)

    Goel, Anjali; Lasyal, Rajni

    2016-12-01

    Nanocatalysis using metal nanoparticles constitutes one of the emerging technologies for destructive oxidation of organics such as dyes. This paper deals with the degradation of acid red-26 (AR-26), an azo dye by hexacyanoferrate (abbreviated as HCF) (III) using iridium nanoparticles. UV-vis spectroscopy has been employed to obtain the details of the oxidative degradation of the selected dye. The effect of various operational parameters such as HCF(III) concentration, pH, initial dye concentration, catalyst and temperature was investigated systematically at the λmax, 507 nm, of the reaction mixture. Degradation kinetics follows the first order kinetic model with respect to AR-26 and Ir nano concentrations, while with respect to the HCF(III) concentration reaction it follows first order kinetics at lower concentrations, tending towards zero order at higher concentrations. Thermodynamic parameters have been calculated by studying the reaction rate at four different temperatures. The UV-vis, high performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS) analysis of degradation products showed the formation of carboxylic acid and substituted carboxylic acids as major degradation products, which are simple and less hazardous compounds. The big advantage of the present method is the recovery and reuse of iridium nanoparticles. Moreover, turnover frequencies for each catalytic cycle have been determined, indicating the long life span of Ir nanoparticles. Thus, the finding is a novel and highly economical alternative for environmental safety against pollution by dyes, and extendable for other contaminants as well.

  15. Ligand exchange and redox processes in iridium triazolylidene complexes relevant to catalytic water oxidation.

    Science.gov (United States)

    Petronilho, Ana; Llobet, Antoni; Albrecht, Martin

    2014-12-15

    Iridium(III) complexes containing a bidentate spectator ligand have emerged as powerful catalyst precursors for water oxidation. Here we investigate the initial steps of the transformation at the iridium center when using complex [IrCp*(pyr-trz)Cl] 1 (Cp* = pentamethylcyclopentadienyl, pyr-trz = 4-(2-pyridyl)-1,2,3-triazol-5-ylidene), a potent water oxidation catalyst precursor. Ligand exchange with water is facile and is reversed in the presence of chloride ions, while MeCN substitution is effective only from the corresponding aqua complex. A pKa of 8.3 for the aqua complex was determined, which is in agreement with strong electron donation from the triazolylidene ligand that is comparable to aryl anions. Evaluation of the pH-dependent oxidation process in aqueous media reveals two regimes (pH 4-8.5 and above pH 10.5) where proton-coupled electron transfer processes occur. These investigations will help to further optimize water oxidation catalysts and indicate that MeCN as a cosolvent has adverse effects for initiating water coordination in the oxidation process.

  16. Efficiency Control in Iridium Complex-Based Phosphorescent Light-Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Boucar Diouf

    2012-01-01

    Full Text Available Key factors to control the efficiency in iridium doped red and green phosphorescent light emitting diodes (PhOLEDs are discussed in this review: exciton confinement, charge trapping, dopant concentration and dopant molecular structure. They are not independent from each other but we attempt to present each of them in a situation where its specific effects are predominant. A good efficiency in PhOLEDs requires the triplet energy of host molecules to be sufficiently high to confine the triplet excitons within the emitting layer (EML. Furthermore, triplet excitons must be retained within the EML and should not drift into the nonradiative levels of the electron or hole transport layer (resp., ETL or HTL; this is achieved by carefully choosing the EML’s adjacent layers. We prove how reducing charge trapping results in higher efficiency in PhOLEDs. We show that there is an ideal concentration for a maximum efficiency of PhOLEDs. Finally, we present the effects of molecular structure on the efficiency of PhOLEDs using red iridium complex dopant with different modifications on the ligand to tune its highest occupied molecular orbital (HOMO and lowest unoccupied molecular orbital (LUMO energies.

  17. Accurate prediction of emission energies with TD-DFT methods for platinum and iridium OLED materials.

    Science.gov (United States)

    Morello, Glenn R

    2017-06-01

    Accurate prediction of triplet excitation energies for transition metal complexes has proven to be a difficult task when confronted with a variety of metal centers and ligand types. Specifically, phosphorescent transition metal light emitters, typically based on iridium or platinum, often give calculated results of varying accuracy when compared to experimentally determined T1 emission values. Developing a computational protocol for reliably calculating OLED emission energies will allow for the prediction of a complex's color prior to synthesis, saving time and resources in the laboratory. A comprehensive investigation into the dependence of the DFT functional, basis set, and solvent model is presented here, with the aim of identifying an accurate method while remaining computationally cost-effective. A protocol that uses TD-DFT excitation energies on ground-state geometries was used to predict triplet emission values of 34 experimentally characterized complexes, using a combination of gas phase B3LYP/LANL2dz for optimization and B3LYP/CEP-31G/PCM(THF) for excitation energies. Results show excellent correlation with experimental emission values of iridium and platinum complexes for a wide range of emission energies. The set of complexes tested includes neutral and charged complexes, as well as a variety of different ligand types.

  18. Treatment of carcinoma of the penis by iridium 192 wire implant

    Energy Technology Data Exchange (ETDEWEB)

    Daly, N.J.; Douchez, J.; Combes, P.F.

    1982-07-01

    Since 1971, a group of 22 adult patients with squamous cell carcinoma of the penis have been treated by iridium 192 wire implants. There were 6 T1 tumors, 14 T2 tumors and 2 T3; only one patient (T3) presented with local failure after implant. Local necrosis occurred in 2 patients without local tumoral recurrence, but was sufficient enough to warrant amputation. Thus 19/22 (86%) patients were locally cured with penile conservation. In these patients the most frequent posttherapeutic complication is chronic urethral stenosis (9/19 patients, 47%) requiring repeated instrumental dilations. Four patients presented with initial inguinal mestastatic nodes; only one was cured by radiosurgical treatment. Among patients without metastatic nodes at the time of diagnosis, none had delayed metastatic nodes. Three patients died of nodal evolution, 5 patients died of intercurrent disease without evidence of disease and 14 are now alive and NED. It appears that iridium 192 wire implant is the most effective conservative treatment of invasive squamous cell carcinoma of the penis; however, these results confirm that no particular treatment is required for inguinal nodal areas for patients who initially present with no disease.

  19. [Brachytherapy in France: current situation and economic outlook due to the unavailability of iridium wires].

    Science.gov (United States)

    Le Vu, B; Boucher, S

    2014-10-01

    In 2013, about 6000 patients were treated with brachytherapy, the number diminishing by 2.6% per year since 2008. Prostate, breast and gynecological cancers are the most common types of cancers. Since 2008, the number of brachytherapy facilities has decreased by 18%. In medicoeconomic terms, brachytherapy faces many problems: the coding system is outdated; brachytherapy treatments cost as much as internal radiation; fees do not cover costs; since iridium wire has disappeared from the market, the technique will be transferred to more expensive high-speed or pulse dose rates. The French financing grid based on the national study of costs lags behind changes in such treatments and in the best of cases, hospitals resorting to alternatives such as in-hospital brachytherapy are funded at 46% of their additional costs. Brachytherapy is a reference technique. With intense pressure on hospital pricing, financing brachytherapy facilities will become even more problematic as a consequence of the disappearance of iridium 192 wires. The case of brachytherapy illustrates the limits of the French financing system and raises serious doubts as to its responsiveness. Copyright © 2014 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

  20. High-Performance Computer Modeling of the Cosmos-Iridium Collision

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S; Cook, K; Fasenfest, B; Jefferson, D; Jiang, M; Leek, J; Levatin, J; Nikolaev, S; Pertica, A; Phillion, D; Springer, K; De Vries, W

    2009-08-28

    This paper describes the application of a new, integrated modeling and simulation framework, encompassing the space situational awareness (SSA) enterprise, to the recent Cosmos-Iridium collision. This framework is based on a flexible, scalable architecture to enable efficient simulation of the current SSA enterprise, and to accommodate future advancements in SSA systems. In particular, the code is designed to take advantage of massively parallel, high-performance computer systems available, for example, at Lawrence Livermore National Laboratory. We will describe the application of this framework to the recent collision of the Cosmos and Iridium satellites, including (1) detailed hydrodynamic modeling of the satellite collision and resulting debris generation, (2) orbital propagation of the simulated debris and analysis of the increased risk to other satellites (3) calculation of the radar and optical signatures of the simulated debris and modeling of debris detection with space surveillance radar and optical systems (4) determination of simulated debris orbits from modeled space surveillance observations and analysis of the resulting orbital accuracy, (5) comparison of these modeling and simulation results with Space Surveillance Network observations. We will also discuss the use of this integrated modeling and simulation framework to analyze the risks and consequences of future satellite collisions and to assess strategies for mitigating or avoiding future incidents, including the addition of new sensor systems, used in conjunction with the Space Surveillance Network, for improving space situational awareness.

  1. Iridium-Based Nanowires as Highly Active, Oxygen Evolution Reaction Electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Alia, Shaun M. [Chemistry; Shulda, Sarah [Department; Ngo, Chilan [Department; Pylypenko, Svitlana [Department; Pivovar, Bryan S. [Chemistry

    2018-01-30

    Iridium-nickel (Ir-Ni) and iridium-cobalt (Ir-Co) nanowires have been synthesized by galvanic displacement and studied for their potential to increase the performance and durability of electrolysis systems. Performances of Ir-Ni and Ir-Co nanowires for the oxygen evolution reaction (OER) have been measured in rotating disk electrode half-cells and single-cell electrolyzers and compared with commercial baselines and literature references. The nanowire catalysts showed improved mass activity, by more than an order of magnitude compared with commercial Ir nanoparticles in half-cell tests. The nanowire catalysts also showed greatly improved durability, when acid-leached to remove excess Ni and Co. Both Ni and Co templates were found to have similarly positive impacts, although specific differences between the two systems are revealed. In single-cell electrolysis testing, nanowires exceeded the performance of Ir nanoparticles by 4-5 times, suggesting that significant reductions in catalyst loading are possible without compromising performance.

  2. Colorimetric and luminescent bifunctional iridium(III) complexes for the sensitive recognition of cyanide ions

    Science.gov (United States)

    Chen, Xiudan; Wang, Huili; Li, Jing; Hu, Wenqin; Li, Mei-Jin

    2017-02-01

    Two new cyclometalated iridium(III) complexes [(ppy)2Irppz]Cl (1) and [(ppy)2Irbppz]Cl (2) (where ppy = 2-phenylpyridine, ppz = 4,7-phenanthrolino-5,6:5,6-pyrazine, bppz = 2.3-di-2-pyridylpyrazine), were designed and synthesized. The structure of [(ppy)2Irppz]Cl was determined by single crystal X-ray diffraction. Their photophysical properties were also studied. This kind of complexes could coordinate with Cu2 +, the photoluminescence (PL) of the complex was quenched, and the color changed from orange-red to green. The forming M-Cu (M: complexes 1 and 2) ensemble could be further utilized as a colorimetric and emission ;turn-on; bifunctional detection for CN-, especially for complex 1-Cu2 + showed a high sensitivity toward CN- with a limit of diction is 97 nM. Importantly, this kind of iridium(III) complexes shows a unique recognition of cyanide ions over other anions which makes it an eligible sensing probe for cyanide ions.

  3. Poly(dendrimers) with phosphorescent iridium(III) complex-based side chains prepared via ring-opening metathesis polymerization

    NARCIS (Netherlands)

    Lai, W.-Y.; Balfour, M.N.; Levell, J.W.; Bansal, A.K.; Burn, P.L.; Lo, S.-C.; Samuel, I.D.W.

    2012-01-01

    Phosphorescent poly(dendrimers) with a norbornene-derived backbone have been synthesized using ring-opening metathesis polymerization with the Grubbs III catalyst. The dendrimers are comprised of a heteroleptic iridium(III) complex core with two 2-phenylpyridyl ligands and a phenyltriazolyl ligand,

  4. Synthesis of N-phenyl β-amino acids via iridium-catalyzed asymmetric hydrogenation using mixed monodentate ligands

    NARCIS (Netherlands)

    Mrsic, Natasa; Panella, Lavinia; Minnaard, Adriaan J.; Feringa, Ben L.; de Vries, Johannes G.

    2011-01-01

    The iridium-catalyzed asymmetric hydrogenation of N-phenyl-beta-dehydroamino acid derivatives was examined using monodentate phosphoramidite ligands. The highest yields and enantioselectivities were obtained using a mixed ligand approach with PipPhos L1 and achiral triphenylphosphine (full

  5. Electrochemical and Spectroelectrochemical Characterization of an Iridium-Based Molecular Catalyst for Water Splitting: Turnover Frequencies, Stability, and Electrolyte Effects

    NARCIS (Netherlands)

    Diaz-Morales, O.; Hersbach, T.J.P.; Hetterscheid, D.G.H.; Reek, J.N.H.; Koper, M.T.M.

    2014-01-01

    We present a systematic electrochemical and spectroelectrochemical study of the catalytic activity for water oxidation of an iridium-N-dimethylimidazolin-2-ylidene (Ir-NHC-Me-2) complex adsorbed on a polycrystalline gold electrode. The work aims to understand the effect of the electrolyte properties

  6. Phosphorescence Imaging of Living Cells with Amino Acid-Functionalized Tris(2-phenylpyridine)iridium(III) Complexes

    NARCIS (Netherlands)

    Steunenberg, P.; Ruggi, A.; Berg, van den N.S.; Buckle, T.; Kuil, J.; Leeuwen, van F.W.B.; Velders, A.H.

    2012-01-01

    A series of nine luminescent cyclometalated octahedral iridium(III) tris(2-phenylpyridine) complexes has been synthesized, functionalized with three different amino acids (glycine, alanine, and lysine), on one, two, or all three of the phenylpyridine ligands. All starting complexes and final

  7. Application of AirCell Cellular AMPS Network and Iridium Satellite System Dual Mode Service to Air Traffic Management

    Science.gov (United States)

    Shamma, Mohammed A.

    2004-01-01

    The AirCell/Iridium dual mode service is evaluated for potential applications to Air Traffic Management (ATM) communication needs. The AirCell system which is largely based on the Advanced Mobile Phone System (AMPS) technology, and the Iridium FDMA/TDMA system largely based on the Global System for Mobile Communications(GSM) technology, can both provide communication relief for existing or future aeronautical communication links. Both have a potential to serve as experimental platforms for future technologies via a cost effective approach. The two systems are well established in the entire CONUS and globally hence making it feasible to utilize in all regions, for all altitudes, and all classes of aircraft. Both systems have been certified for air usage. The paper summarizes the specifications of the AirCell/Iridium system, as well as the ATM current and future links, and application specifications. the paper highlights the scenarios, applications, and conditions under which the AirCell/Iridium technology can be suited for ATM Communication.

  8. Soft tissue facial morphometry before and after total oral rehabilitation with implant-supported prostheses.

    Science.gov (United States)

    Tartaglia, Gianluca M; Dolci, Claudia; Sidequersky, Fernanda V; Ferrario, Virgilio F; Sforza, Chiarella

    2012-11-01

    The objective of the current study was to assess a low-cost, noninvasive facial morphometric digitizer to assist the practitioner in three-dimensional soft-tissue changes before and after oral rehabilitation. Twenty-two patients aged 45 to 82 years, all with edentulous maxilla and mandible, were assessed both before and after receiving their definitive complete implant-supported prostheses (each received 4-11 implants in each dental arch; full-arch fixed prostheses were made). The three-dimensional coordinates of 50 soft-tissue facial landmarks were collected with a noninvasive digitizer; labial and facial areas, volumes, angles, and distances were compared without and with the prostheses. Dental prostheses induced significant reductions in the nasolabial, mentolabial, and interlabial angles, with increased labial prominence (P provisional prosthetic restoration, providing quantitative information to prepare the best definitive prosthesis.

  9. Effects of quaternary ammonium silane coatings on mixed fungal and bacterial biofilms on tracheoesophageal shunt prostheses

    NARCIS (Netherlands)

    Oosterhof, JJH; Buijssen, KJDA; Busscher, HJ; van der Laan, BFAM; van der Mei, HC

    Two quaternary ammonium silanes (QAS) were used to coat silicone rubber tracheoesophageal shunt prostheses, yielding a positively charged surface. One QAS coating [(trimethoxysilyl)-propyidimethylocta-decylammonium chloride] was applied through chemical bonding, while the other coating, Biocidal ZF,

  10. Progress in the clinical development and utilization of vision prostheses: an update.

    Science.gov (United States)

    Brandli, Alice; Luu, Chi D; Guymer, Robyn H; Ayton, Lauren N

    2016-01-01

    Vision prostheses, or "bionic eyes", are implantable medical bionic devices with the potential to restore rudimentary sight to people with profound vision loss or blindness. In the past two decades, this field has rapidly progressed, and there are now two commercially available retinal prostheses in the US and Europe, and a number of next-generation devices in development. This review provides an update on the development of these devices and a discussion on the future directions for the field.

  11. Evaluation of dental material series from patients with dental prostheses and suspicion of delayed hypersensitivity*

    OpenAIRE

    Yoshimura, Fernanda Cortinhas; Cunha, Victor do Espirito Santo; Hahnstadt, Ruppert Ludwig; Pires, M?rio Cezar

    2016-01-01

    Abstract: BACKGROUND: Patients with oral sensitivity are common in our practice. Allergic contact dermatitis is one of the most frequent etiologies. OBJECTIVES: Evaluate oral contact dermatitis using the Brazilian standard series and complementary dental series in patients using dental prostheses, with or without oral complaints. Determine specific dental Brazilian series. METHODS: Patients using dental prostheses with or without oral complaints realized patch tests. Brazilian standard ser...

  12. Origins of Enantioselectivity during Allylic Substitution Reactions Catalyzed by Metallacyclic Iridium Complexes

    Science.gov (United States)

    Madrahimov, Sherzod T.; Hartwig, John F.

    2012-01-01

    In depth mechanistic studies of iridium catalyzed regioselective and enantioselective allylic substitution reactions are presented. A series of cyclometallated allyliridium complexes that are kinetically and chemically competent to be intermediates in the allylic substitution reactions was prepared and characterized by 1D and 2D NMR spectroscopies and solid state structural analysis. The rates of epimerization of the less thermodynamically stable diastereomeric allyliridium complexes to the thermodynamically more stable allyliridium stereoisomers were measured. The rates of nucleophilic attack by aniline and by N-methylaniline on the isolated allyliridium complexes were also measured. Attack on the thermodynamically less stable allyliridium complex was found to be orders of magnitude faster than attack on the thermodynamically more stable complex, yet the major enantiomer of the catalytic reaction is formed from the more stable diastereomer. Comparison of the rates of nucleophilic attack to the rates of epimerization of the diastereomeric allyliridium complexes containing a weakly-coordinating counterion showed that nucleophilic attack on the less stable allyliridium species is much faster than conversion of the less stable isomer to the more stable isomer. These observations imply that Curtin-Hammett conditions are not met during iridium catalyzed allylic substitution reactions by η3-η1-η3 interconversion. Rather, these data imply that when these conditions exist for this reaction, they are created by reversible oxidative addition and the high selectivity of this oxidative addition step to form the more stable diastereomeric allyl complex leads to the high enantioselectivity. The stereochemical outcome of the individual steps of allylic substitution was assessed by reaction of deuterium-labeled substrates. The reaction was shown to occur by oxidative addition with inversion of configuration, followed by an outer sphere nucleophilic attack that leads to a second

  13. Impact of Physical Activity on Participation and Quality of Life in Individuals who use Prostheses and other Assistive Technology/Lower Extremity Prostheses versus Wheelchair for Functional Performance and Participation of Military and Veteran Personnel

    Science.gov (United States)

    2007-03-01

    See Table 1) Additional questions were asked regarding the participation in specific organized sports such as rugby, wheelchair basketball , or events...Participation and Quality of Life in Individuals who use Prostheses and other Assistive Technology/Lower Extremity Prostheses versus Wheelchair for Functional...other Assistive Technology/Lower Extremity Prostheses versus 5b. GRANT NUMBER W81XWH-06-1-0493 Wheelchair for Functional Performance and

  14. Migration of Single Iridium Atoms and Tri-iridium Clusters on MgO Surfaces. Aberration-Corrected STEM Imaging and ab-initio Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Han, Chang W. [Purdue Univ., West Lafayette, IN (United States); Iddir, Hakim [Argonne National Lab. (ANL), Argonne, IL (United States); Uzun, Alper [Koc Univ., Instanbul (Turkey); Curtiss, Larry A. [Argonne National Lab. (ANL), Argonne, IL (United States); Browning, Nigel D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gates, Bruce C. [Univ. of California, Davis, CA (United States); Ortalan, Volkan [Purdue Univ., West Lafayette, IN (United States)

    2015-11-06

    To address the challenge of fast, direct atomic-scale visualization of the diffusion of atoms and clusters on surfaces, we used aberration-corrected scanning transmission electron microscopy (STEM) with high scan speeds (as little as ~0.1 s per frame) to visualize the diffusion of (1) a heavy atom (Ir) on the surface of a support consisting of light atoms, MgO(100), and (2) an Ir3 cluster on MgO(110). Sequential Z-contrast images elucidate the diffusion mechanisms, including the hopping of Ir1 and the rotational migration of Ir3 as two Ir atoms remain anchored to the surface. Density functional theory (DFT) calculations provided estimates of the diffusion energy barriers and binding energies of the iridium species to the surfaces. The results show how the combination of fast-scan STEM and DFT calculations allow real-time visualization and fundamental understanding of surface diffusion phenomena pertaining to supported catalysts and other materials.

  15. [Endo-exo prostheses following limb-amputation].

    Science.gov (United States)

    Juhnke, D-L; Aschoff, H-H

    2015-06-01

    Rehabilitation of patients having undergone limb amputation is difficult due to problems related to poor socket fit, which often deteriorates comfort, gait and the ability to take part in everyday life and work. The endo-exo prosthesis has been an alternative provision for people having undergone lower limb amputation for reasons other than diabetes or peripheral vascular disease for more than 10 years. The system consists of an intramedullar, osseointegrated and skin perforating prosthesis, which is implanted in the remaining bone and has an abutment to allow the attachment of the external prosthetic part including the knee joint in the case of a trans-femoral amputation. The idea originates in findings of modern tooth-implantology and involves a two-step operation. This study focuses on one centre's experience with the endo-exo prostheses in Lübeck, Germany, to describe and discuss the reliability of this alternative treatment method after lower limb amputation. This article presents the results of lower limb amputees operated on in Lübeck, Germany between 1999-2013. It focuses on theoretical aspects of osseointegration and different clinically-based findings using the endo-exo technique over the last decade. 74 lower-limb amputees were treated with an endo-exo prosthesis until December 2013. There were only 4 verified intramedullar infections, yet there were many unplanned surgical revisions secondary to soft-tissue infections in the beginning. They were successfully encountered via clinically-based changes that were made concerning implant design, wound treatment and operative technique. Since 1990 a few groups have developed an innovative method that provides an alternative to traditional socket-type prostheses. This involves a skeletally anchored device that is inserted into the remaining stump and provides osseointegration into the bone. The distal part of the implant protrudes transcutaneously and allows attachment to a prosthetic limb. This creates a

  16. Evolvable synthetic neural system

    Science.gov (United States)

    Curtis, Steven A. (Inventor)

    2009-01-01

    An evolvable synthetic neural system includes an evolvable neural interface operably coupled to at least one neural basis function. Each neural basis function includes an evolvable neural interface operably coupled to a heuristic neural system to perform high-level functions and an autonomic neural system to perform low-level functions. In some embodiments, the evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy.

  17. [Clinical evaluation of "All-on-Four" provisional prostheses reinforced with carbon fibers].

    Science.gov (United States)

    Li, Bei-bei; Lin, Ye; Cui, Hong-yan; Hao, Qiang; Xu, Jia-bin; Di, Ping

    2016-02-18

    To assess the clinical effects of carbon fiber reinforcement on the "All-on-Four" provisional prostheses. Provisional prostheses were divided into control group and carbon fiber reinforcing group according to whether carbon fiber reinforcement was used in the provisional prostheses base resin. In our study, a total of 60 patients (32 males and 28 females) with 71 provisional prostheses(28 maxilla and 43 mandible)were enrolled between April 2008 and December 2012 for control group; a total of 23 patients (13 males and 10 females) with 28 provisional prostheses (9 maxillas and 19 mandibles) were enrolled between January 2013 and March 2014 for carbon fiber reinforcing group. The information of provisional prostheses in the patients was recorded according to preoperative examination. We used the date of definitive prosthesis restoration as the cut-off point, observing whether fracture occurred on the provisional prostheses in the two groups. Additionally we observed whether fiber exposure occurred on the tissue surface of the provisional prostheses and caused mucosal irritation. The interface between the denture base resin and the fibers was examined using scanning electron microscopy (SEM). The age [(57.3 ± 10.1) years vs.(55.1 ± 11.4) years], gender (32 males and 28 females vs. 13 males and 10 females), maxilla and mandible distributions (28 maxillas and 43 mandibles vs. 9 maxillas and 19 mandibles), the number of extraction jaws (46 vs. 23), the average using time [(7.8 ± 1.3) months vs. (7.5 ± 1.1) months], and the opposing dentition distributions of provisional prostheses of the patients showed no significant differences between the control and reinforcing groups. There were 21(29.6%) fractures that occurred on the 71 provisional prostheses in the control group; there was no fracture that occurred on the 28 provisional prosthesesin the carbon fiber reinforcing group. The fracture rate of the carbon fiber reinforcing group was significantly lower than that of

  18. Highly sensitive iridium(iii) complex-based phosphorescent probe for thiophenol detection.

    Science.gov (United States)

    Xiong, Li; Yang, Lin; Luo, Shuai; Huang, Yan; Lu, Zhiyun

    2017-10-10

    A cyclometalated iridium(iii) complex (Ir-DNBS) was designed and synthesized as a high-performance phosphorescent thiophenol probe. Ir-DNBS displays a distinct phosphorescence "off-on" response toward thiophenol with high selectivity, high sensitivity (detection limit: 2.5 nM) and fast response (10 min). It is noteworthy that the signaling phosphore of Ir-DNBS possesses relatively high photoluminescence quantum efficiency (ΦPL = 0.21) together with relatively long lifetime (τ = 2.07 μs), indicative of its potential in achieving high temporal resolution. Ir-DNBS is also applicable to the detection of thiophenol in actual water samples with high recovery rate. Photophysical and spectral characterization results revealed that the probing mechanism of Ir-DNBS toward thiophenol lies in the thiolate-mediated cleavage reaction, resulting in suppressed photo-induced excited state electron transfer process in the reaction product.

  19. Nuclear moments of neutron-deficient iridium isotopes from laser spectroscopy

    CERN Document Server

    Verney, D; Cabaret, L A; Crawford, J; Duong, H T; Genevey, J; Huber, G; Ibrahim, F; Krieg, M; Lee, J K P; Lunney, M D; Obert, J; Oms, J; Pinard, J; Putaux, J C; Roussière, B; Sauvage, J; Sebastian, V

    2000-01-01

    Laser spectroscopy measurements have been performed on neutron- deficient iridium isotopes. The hyperfine structure and isotope shift of the optical Ir I transition 5d/sup 7/6s/sup 2/ /sup 4/F/sub 9/2/ to 5d/sup 7/6s6p /sup 6/F/sub 11/2/ at 351.5 nm have been studied for the /sup 182-189/Ir, /sup 186/Ir/sup m/ and /sup 191,193/Ir isotopes. The nuclear magnetic and quadrupole moments were obtained from the HFS measurements and the changes of the mean square charge radii from the IS measurements. A large mean square charge radius change between /sup 187/Ir and /sup 186/Ir and between /sup 186/Ir/sup m/ and /sup 186/Ir/sup g/ has been observed. (18 refs).

  20. A water-soluble and highly phosphorescent cyclometallated iridium complex with versatile sensing capability.

    Science.gov (United States)

    Yang, Zhen; Zhao, Yuan; Wang, Chan; Song, Qijun; Pang, Qingfeng

    2017-05-01

    A water-soluble and highly phosphorescent cyclometallated iridium complex [(pq)2Ir(bpy-COOK)](+)Cl(-) (where pq=2-phenylquinoline, bpy-COOK= potassium 2,2'-bipyridine-4,4'-dicarboxylate) (Ir) has been synthesized and characterized. Its phosphorescence can be sensitively and selectively quenched by tryptophan through a photoinduced electron-transfer (PET) process. Furthermore, the phosphorescence of Ir is drastically increased upon binding with bovine serum albumin (BSA), and the enhanced signal is effectively quenched in the presence of Cu(2+). Thus, Ir can be used as a multifunctional chemosensor for tryptophan, BSA, and Cu(2+) determination as well as for cell imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. High performance optical oxygen sensors based on iridium complexes exhibiting interchromophore energy shuttling.

    Science.gov (United States)

    Medina-Rodríguez, Santiago; Denisov, Sergey A; Cudré, Yanouk; Male, Louise; Marín-Suárez, Marta; Fernández-Gutiérrez, Alberto; Fernández-Sánchez, Jorge F; Tron, Arnaud; Jonusauskas, Gediminas; McClenaghan, Nathan D; Baranoff, Etienne

    2016-05-10

    A doubly pyrene-grafted bis-cyclometallated iridium complex with engineered electronically excited states demonstrates reversible electronic energy transfer between adjacent chromophores giving rise to extremely long-lived red luminescence in solution (τ = 480 μs). Time-resolved spectroscopic studies afforded determination of pertinent photophysical parameters including rates of energy transfer and energy distribution between constituent chromophores in the equilibrated excited molecule (ca. 98% on the organic chromophores). Incorporation into a nanostructured metal-oxide matrix (AP200/19) gave highly sensitive O2 sensing films, as the detection sensitivity was 200-300% higher than with the commonly used PtTFPP and approaches the sensitivity of the best O2-sensing dyes reported to date.

  2. Transpapillary iridium-192 wire in the treatment of malignant bile duct obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Levitt, M.D.; Laurence, B.H.; Cameron, F.; Klemp, P.F.B.

    1988-02-01

    Twenty four patients with malignant bile duct obstruction were treated with intraluminal radiotherapy using iridium-192 wire inserted through an endoscopically placed nasobiliary catheter. Biliary drainage after treatment was maintained by an endoprosthesis. The median dose of intraluminal radiotherapy was 6000 cGy; two patients with cholangiocarcinoma were given a second course because of disease extension; four patients with pancreatic carcinoma received additional external irradiation (3000 cGy). There was one early death from a cerebrovascular accident (30 day mortality, 4.2%). Cholangitis (30%) was the major early complication and stent blockage (40%) the major late complication; there were no complications directly attributable to radiotherapy. The median survival for patients with pancreatic carcinoma was 250 days and for cholangiocarcinoma, 300 days. This method is technically feasible and may prove safer than the transhepatic technique. The ability of intraluminal irradiation to improve palliation or lengthen survival in patients with malignant bile duct obstruction remains uncertain.

  3. Rigid biimidazole ancillary ligands as an avenue to bright deep blue cationic iridium(iii) complexes.

    Science.gov (United States)

    Henwood, Adam F; Evariste, Sloane; Slawin, Alexandra M Z; Zysman-Colman, Eli

    2014-01-01

    Herein we report the synthesis and optoelectronic characterisation of three deep blue-emitting cationic iridium complexes, of the form [Ir(dFppy)(2)(N^N)]PF(6), bearing biimidazole-type N^N ancillary ligands (dFppyH = 2-(2,4-difluorophenyl)pyridine). Complex 1 contains the parent biimidazole, biim, while 2 contains a dimethylated analog, dMebiim, and 3 contains an ortho-xylyl-tethered biimidzole, o-xylbiim. We explore a strategy of tethering the biimidazole in order to rigidify the complex and increase the photoluminescent quantum yield, culminating in deep blue (λ(max): 457 nm in MeOH at 298 K) ligand-centered emission with a very high photoluminescent quantum yield of 68% and microsecond emission lifetime. Density functional theory calculations elucidate the origin of such disparate excited state kinetics across this series, especially in light of virtually identical optoelectronic properties observed for these compounds.

  4. Iridium- and Ruthenium-Catalyzed N-alkylation of Amines with Alcohols and Amines

    DEFF Research Database (Denmark)

    Lorentz-Petersen, Linda Luise Reeh

    experiments of the iridium catalyzed reactions revealed that the Voigt isomerization of the α-imino alcohol intermediate to the corresponding α-imino ketone plays a significant role. Synthesis of indoles Anilines and vicinal diols were reacted in the presence of a ruthenium complex (RuCl3 with PPh3...... catalysts have been employed for the N-alkylation of amines with either alcohols or amines. Synthesis of secondary amines Self-condensation of primary amines afforded secondary amines in good to high yields. The reaction is catalyzed by the commercially available [Cp*IrCl2]2 complex. The procedure...... is environmentally benign as it is performed in the absence of both solvent and additives and the only by-product is ammonia. Additionally, the work-up procedure is a simple distillation of the product directly from the reaction mixture. Synthesis of piperazines In the Madsen group it has previously been...

  5. Cyclometalated Iridium(III) Carbene Phosphors for Highly Efficient Blue Organic Light-Emitting Diodes.

    Science.gov (United States)

    Chen, Zhao; Wang, Liqi; Su, Sikai; Zheng, Xingyu; Zhu, Nianyong; Ho, Cheuk-Lam; Chen, Shuming; Wong, Wai-Yeung

    2017-11-22

    Five deep blue carbene-based iridium(III) phosphors were synthesized and characterized. Interestingly, one of them can be fabricated into deep blue, sky blue and white organic light-emitting diodes (OLEDs) through changing the host materials and exciton blocking layers. These deep and sky blue devices exhibit Commission Internationale de l'Éclairage (CIE) coordinates of (0.145, 0.186) and (0.152, 0.277) with external quantum efficiency (EQE) of 15.2% and 9.6%, respectively. The EQE of the deep blue device can be further improved up to 19.0% by choosing a host with suitable energy level of its lowest unoccupied molecular orbital (LUMO).

  6. Iridium Oxide Nanotube Electrodes for Highly Sensitive and Prolonged Intracellular Measurement of Action Potentials

    Science.gov (United States)

    Lin, Ziliang Carter; Xie, Chong; Osakada, Yasuko; Cui, Yi; Cui, Bianxiao

    2014-01-01

    Intracellular recording of action potentials is important to understand electrically-excitable cells. Recently, vertical nanoelectrodes have been developed to achieve highly sensitive, minimally invasive, and large scale intracellular recording. It has been demonstrated that the vertical geometry is crucial for the enhanced signal detection. Here we develop nanoelectrodes made up of nanotubes of iridium oxide. When cardiomyocytes are cultured upon those nanotubes, the cell membrane not only wraps around the vertical tubes but also protrudes deep into the hollow center. We show that this geometry enhances cell-electrode coupling and results in measuring much larger intracellular action potentials. The nanotube electrodes afford much longer intracellular access and are minimally invasive, making it possible to achieve stable recording up to an hour in a single session and more than 8 days of consecutive daily recording. This study suggests that the electrode performance can be significantly improved by optimizing the electrode geometry. PMID:24487777

  7. Iridium oxide nanotube electrodes for sensitive and prolonged intracellular measurement of action potentials

    Science.gov (United States)

    Lin, Ziliang Carter; Xie, Chong; Osakada, Yasuko; Cui, Yi; Cui, Bianxiao

    2014-02-01

    Intracellular recording of action potentials is important to understand electrically-excitable cells. Recently, vertical nanoelectrodes have been developed to achieve highly sensitive, minimally invasive and large-scale intracellular recording. It has been demonstrated that the vertical geometry is crucial for the enhanced signal detection. Here we develop nanoelectrodes of a new geometry, namely nanotubes of iridium oxide. When cardiomyocytes are cultured upon those nanotubes, the cell membrane not only wraps around the vertical tubes but also protrudes deep into the hollow centre. We show that this nanotube geometry enhances cell-electrode coupling and results in larger signals than solid nanoelectrodes. The nanotube electrodes also afford much longer intracellular access and are minimally invasive, making it possible to achieve stable recording up to an hour in a single session and more than 8 days of consecutive daily recording. This study suggests that the nanoelectrode performance can be significantly improved by optimizing the electrode geometry.

  8. Conodont survival and low iridium abundances across the Permian-Triassic boundary in south China

    Science.gov (United States)

    Clark, D. L.; Wang, C.-Y.; Orth, C. J.; Gilmore, J. S.

    1986-01-01

    The Permian-Triassic sedimentary sequence of China includes one of the most complete and fossiliferous Paleozoic-Mesozoic boundaries known. Closely spaced sampling across the boundary, which is an important extinction event for most organisms, has produced good conodont faunas that show little diversity change. A drop in conodont abundance is the only apparent response to the extinction event. A low concentration of iridium in the boundary clay (0.002 part per billion + or - 20 percent), as well as in samples immediately below and above, that range from 0.004 to 0.034 part per billion do not support the proposal of an extraterrestrial impact event at this boundary in China.

  9. Catalytic dehydroaromatization of n-alkanes by pincer-ligated iridium complexes

    Science.gov (United States)

    Ahuja, Ritu; Punji, Benudhar; Findlater, Michael; Supplee, Carolyn; Schinski, William; Brookhart, Maurice; Goldman, Alan S.

    2011-02-01

    Aromatic hydrocarbons are among the most important building blocks in the chemical industry. Benzene, toluene and xylenes are obtained from the high temperature thermolysis of alkanes. Higher alkylaromatics are generally derived from arene-olefin coupling, which gives branched products—that is, secondary alkyl arenes—with olefins higher than ethylene. The dehydrogenation of acyclic alkanes to give alkylaromatics can be achieved using heterogeneous catalysts at high temperatures, but with low yields and low selectivity. We present here the first catalytic conversion of n-alkanes to alkylaromatics using homogeneous or molecular catalysts—specifically ‘pincer’-ligated iridium complexes—and olefinic hydrogen acceptors. For example, the reaction of n-octane affords up to 86% yield of aromatic product, primarily o-xylene and secondarily ethylbenzene. In the case of n-decane and n-dodecane, the resulting alkylarenes are exclusively unbranched (that is, n-alkyl-substituted), with selectivity for the corresponding o-(n-alkyl)toluene.

  10. Broadband light absorber based on porous alumina structure covered with ultrathin iridium film

    Science.gov (United States)

    Fang, Bo; Yang, Chenying; Pang, Chenlei; Shen, Weidong; Zhang, Xing; Zhang, Yueguang; Yuan, Wenjia; Liu, Xu

    2017-04-01

    In this letter, we propose a broadband absorber with high efficiency by an atomic layer depositing nanometer iridium (Ir) film onto a porous anodic alumina (PAA) template. The average absorption is able to achieve as high as 93.4% from 400 to 1100 nm and the absorption efficiency can reach up to 96.8% for the improved structure of the quadrangular frustum pyramid array. Not only the hexagonal latticed structures of the PAA template but also many similar structures based on gratings or holes with the square latticed or other latticed mode can realize the broadband high absorption efficiency. The light absorbed within the Ir/Glass interface and the sidewalls of PAA by the light funneling effect both contribute to the broadband absorption with high efficiency. This absorber, described in this paper, can be manufactured with a low-cost and large-area manner and has potential applications in fields of light harvesting, imaging, etc.

  11. Leg stiffness of sprinters using running-specific prostheses

    Science.gov (United States)

    McGowan, Craig P.; Grabowski, Alena M.; McDermott, William J.; Herr, Hugh M.; Kram, Rodger

    2012-01-01

    Running-specific prostheses (RSF) are designed to replicate the spring-like nature of biological legs (bioL) during running. However, it is not clear how these devices affect whole leg stiffness characteristics or running dynamics over a range of speeds. We used a simple spring–mass model to examine running mechanics across a range of speeds, in unilateral and bilateral transtibial amputees and performance-matched controls. We found significant differences between the affected leg (AL) of unilateral amputees and both ALs of bilateral amputees compared with the bioL of non-amputees for nearly every variable measured. Leg stiffness remained constant or increased with speed in bioL, but decreased with speed in legs with RSPs. The decrease in leg stiffness in legs with RSPs was mainly owing to a combination of lower peak ground reaction forces and increased leg compression with increasing speeds. Leg stiffness is an important parameter affecting contact time and the force exerted on the ground. It is likely that the fixed stiffness of the prosthesis coupled with differences in the limb posture required to run with the prosthesis limits the ability to modulate whole leg stiffness and the ability to apply high vertical ground reaction forces during sprinting. PMID:22337629

  12. Application of dexterous space robotics technology to myoelectric prostheses

    Science.gov (United States)

    Hess, Clifford; Li, Larry C. H.; Farry, Kristin A.; Walker, Ian D.

    1994-01-01

    Future space missions will require robots equipped with highly dexterous robotic hands to perform a variety of tasks. A major technical challenge in making this possible is an improvement in the way these dexterous robotic hands are remotely controlled or teleoperated. NASA is currently investigating the feasibility of using myoelectric signals to teleoperate a dexterous robotic hand. In theory, myoelectric control of robotic hands will require little or no mechanical parts and will greatly reduce the bulk and weight usually found in dexterous robotic hand control devices. An improvement in myoelectric control of multifinger hands will also benefit prosthetics users. Therefore, as an effort to transfer dexterous space robotics technology to prosthetics applications and to benefit from existing myoelectric technology, NASA is collaborating with the Limbs of Love Foundation, the Institute for Rehabilitation and Research, and Rice University in developing improved myoelectric control multifinger hands and prostheses. In this paper, we will address the objectives and approaches of this collaborative effort and discuss the technical issues associated with myoelectric control of multifinger hands. We will also report our current progress and discuss plans for future work.

  13. Implant-supported prostheses versus conventional permanent and removable dentures

    Directory of Open Access Journals (Sweden)

    Koszuta Agnieszka

    2014-06-01

    Full Text Available Social, economic and technological progress results in an increasing range of treatment and rehabilitation methods for patients with partial or complete edentulism. The role of the dentist is to inform the patient about the full range of available missing teeth treatment options leading to complete rehabilitation of the masticatory organ in agreement with the patient’s aesthetic and functional expectations. The aim of the paper was to identify the type of prostheses used by patients before opting for implantsupported teeth replacements, according to the patients’ age, sex, marital status, place of residence and education. The study covered 464 patients, women and men, aged 20-74, treated with dental implants. The patients answered questions in an anonymous questionnaire. The influence of the prosthetic replacement type according to age and marital status was highly statistically significant, whereas it was statistically significant according to sex, place of residence and education. The female respondents who previously used tissue-borne complete or partial dentures opted for implant treatment more frequently. The respondents younger than 40 and between 40-60 years of age who did not previously used any prosthetic replacements opted for implant treatment more frequently. The respondents who did not use any prosthetic replacements decided to undergo implant treatment most frequently, regardless of their marital status, education and place of residence. The patients opted for implant treatment to improve their quality of life, despite the high cost of such therapy.

  14. Implant prostheses for convertibility, stress control, esthetics, and hygiene.

    Science.gov (United States)

    Garfield, R E

    1988-07-01

    A method of connecting "fixed partial denture" prostheses to osseointegrated implant fixtures has been described. The advantages of this system of restoration for partially and fully edentulous mouths are that it is more effective in addressing the problems of (1) stress-control on abutments, (2) a back-up system for abutment failures, (3) esthetics, and (4) control of bacterial plaques around abutments. To accomplish this procedure, the application of convertible periodontal prosthesis techniques with modifications to some existing implant systems is undertaken. The disadvantages of this method seem insignificant when one considers the complexities and risks involved with the present array of implant prosthesis alternatives. Some patients and dentists might consider the necessity of the prosthesis being detachable as one disadvantage. In reality, the prosthesis can be used as a fixed restoration until the patient has fully adapted to the new proprioception and appearance. A large percentage of patients feel uncomfortable with the word "removable" because it immediately creates a perception of unsightly metallic clasp display, palatal coverage, tongue interference, and negative body image. The use of the term "detachable" coupled with the doctor's offer to perform this task for the patient "whenever necessary" will usually relieve the patient's anxiety and allow the treatment to proceed. Once neuromuscular and esthetic adaptation have occurred and the patient has accepted the prosthesis, daily detaching and home-care hygiene by the patient will follow without incident. Esthetic improvement is obvious (Fig. 3).

  15. Intraocular camera for retinal prostheses: Refractive and diffractive lens systems

    Science.gov (United States)

    Hauer, Michelle Christine

    The focus of this thesis is on the design and analysis of refractive, diffractive, and hybrid refractive/diffractive lens systems for a miniaturized camera that can be surgically implanted in the crystalline lens sac and is designed to work in conjunction with current and future generation retinal prostheses. The development of such an intraocular camera (IOC) would eliminate the need for an external head-mounted or eyeglass-mounted camera. Placing the camera inside the eye would allow subjects to use their natural eye movements for foveation (attention) instead of more cumbersome head tracking, would notably aid in personal navigation and mobility, and would also be significantly more psychologically appealing from the standpoint of personal appearances. The capability for accommodation with no moving parts or feedback control is incorporated by employing camera designs that exhibit nearly infinite depth of field. Such an ultracompact optical imaging system requires a unique combination of refractive and diffractive optical elements and relaxed system constraints derived from human psychophysics. This configuration necessitates an extremely compact, short focal-length lens system with an f-number close to unity. Initially, these constraints appear highly aggressive from an optical design perspective. However, after careful analysis of the unique imaging requirements of a camera intended to work in conjunction with the relatively low pixellation levels of a retinal microstimulator array, it becomes clear that such a design is not only feasible, but could possibly be implemented with a single lens system.

  16. Wireless technologies for closed-loop retinal prostheses

    Science.gov (United States)

    Ng, David C.; Bai, Shun; Yang, Jiawei; Tran, Nhan; Skafidas, Efstratios

    2009-12-01

    In this paper, we discuss various technologies needed to develop retinal prostheses with wireless power and data telemetry operation. In addition to the need to communicate with the implanted device, supply of power to the retinal prosthesis is especially difficult. This is because, in the implanted state, the device is not fixed in position due to constant motion of the eye. Furthermore, a retinal prosthesis incorporating a high density electrode array of more than 1000 electrodes is expected to consume approximately 45 mW of power and require 300 kbps of image and stimulation data. The front end of the wireless power and data transmission, the antenna, needs to be small compared to the size of the eye. Also, the wireless module is expected to operate in the reactive near-field region due to small separation between the transmit and receive antennas compared to their size and corresponding operating wavelength. An inductive link is studied as a means to transfer power and for data telemetry between the implant and external unit. In this work, the use of integrated circuit and microfabrication technologies for implementing inductive links is discussed. A closed-loop approach is taken to improve performance and reach optimum operation condition. Design and simulation data are presented as the basis for development of viable wireless module prototypes.

  17. Evaluation of cleansing methods for previously worn prostheses.

    Science.gov (United States)

    Glass, R Thomas; Conrad, Robert S; Bullard, James W; Goodson, Leigh B; Mehta, Naresh; Lech, Stanley J; Loewy, Zvi G

    2011-04-01

    Although there are many product claims that address the issue of denture sanitization, controlled scientific studies on previously worn dentures have not been performed. The purpose of this study was to evaluate procedures directed at sanitizing previously worn contaminated dentures from two regions of the United States. This study examined 51 previously worn dentures from two regions. An established method of denture retrieval, sectioning, and culturing was used, including isolation of anaerobes. Evaluation of microbial contamination posttreatment was used to determine the effects of soaking dentures in Polident (US and European formulations) for varying periods of times/temperatures, microwaving dentures with varying temperatures, sonicating dentures, and immersing the dentures while using a vacuum. A combination of analysis of variance (ANOVA) and general linear model (GLM) of the SPSS was used to analyze the data with P sanitization rather than sterilization. Denture-borne microorganisms can be significantly reduced by using a Polident solution for 8 hours at room temperature or for 5 minutes at 65 degrees C. Microwaving, sonication, and use of a vacuum were less effective. ClLINICAL IMPLICATIONS The importance of daily use of Polident solution for 8 hours or for 5 minutes at 65 degrees C to sanitize worn prostheses must be stressed.

  18. Depth Sensing for Improved Control of Lower Limb Prostheses.

    Science.gov (United States)

    Krausz, Nili Eliana; Lenzi, Tommaso; Hargrove, Levi J

    2015-11-01

    Powered lower limb prostheses have potential to improve the quality of life of individuals with amputations by enabling all daily activities. However, seamless ambulation mode recognition is necessary to achieve this goal and is not yet a clinical reality. Current intent recognition systems use mechanical and EMG sensors to estimate prosthesis and user status. We propose to complement these systems by integrating information about the environment obtained through the depth sensing. This paper presents the design, characterization, and the early validation of a novel stair segmentation system based on Microsoft Kinect. Static and dynamic tests were performed. A first experiment showed how the resolution of the depth camera affects the speed and the accuracy of segmentation. A second test proved the robustness of the algorithm to different staircases. Finally, we performed an online walking test with the stair segmentation and related measures recorded online at >5 frames/s. Experimental results show that the proposed algorithm allows for an accurate estimate of distance, angle of intersection, number of steps, stair height, and stair depth for a set of stairs in the environment. The online test produced an estimate of whether the individual was approaching stairs in real time with approximately 98.8% accuracy.

  19. [Communication prostheses and behavioral alignment in hospital leaflets].

    Science.gov (United States)

    Vasconcellos-Silva, Paulo Roberto; Rivera, Francisco Javier Uribe; Rozemberg, Brani

    2003-08-01

    Review was made of publications that describe experience with printed material distributed to the lay public in hospital institutions. From the 146 leaflets examined, those aimed at professionals or disabled people, thus leaving 75 papers that illustrate the present pattern for the rationality behind the production, use and evaluation of this type of resource. In a general manner, such leaflets invest in the power of "ideal printed information" to align behavior with the hospital's biomedical agenda. The underlying rationality that permeates them perceives the "perfect information package" as one that efficiently describes its technical content for the purpose of unidirectional persuasion, is up-to-date in relation to readability scales and embellished by graphic design, and emphasizes the priorities defined by the professionals. Such "communication prostheses" should be capable of electronic validation by means of software suitable for proportioning the "doses" to the subject matter. Information as a drug, cognitivism, the lack of research on message reception and the need for communicative action for the deconstruction of systems of closed thinking within the hospital environment have been discussed.

  20. Polyetheretherketone-a suitable material for fixed dental prostheses?

    Science.gov (United States)

    Stawarczyk, Bogna; Beuer, Florian; Wimmer, Timea; Jahn, Dirk; Sener, Beatrice; Roos, Malgorzata; Schmidlin, Patrick R

    2013-10-01

    To study the surface properties of polyetheretherketone (PEEK) and its bond strength with two veneering resins after different conditioning methods as well as fracture load of PEEK three-unit fixed dental prostheses (FDPs). Two hundred and twenty five PEEK specimens were fabricated and divided into five groups: no treatment (A), etching with 98% sulfuric acid for 1 min (B), air-abrasion for 10 s with either 50 or 110 μm alumina (C and D, respectively), and silica coating using the Rocatec System (E). On 15 specimens of each conditioning method, contact angle and surface roughness were determined. The remaining 150 specimens of each conditioning method were divided into two groups for the veneering procedure with the composites Gradia (GC Europe) and Sinfony (3M ESPE). Shear bond strength (SBS) was measured and failure types were assessed. In addition, 15 FDPs were milled and the fracture load was tested. Data were analyzed using descriptive statistics, one-way ANOVA (Scheffé test), two sample Student's t-test, and Weibull statistics (p veneering material is applied. In this combination, PEEK might be a suitable material for FDPs, especially in load-bearing areas. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

  1. Leg stiffness of sprinters using running-specific prostheses.

    Science.gov (United States)

    McGowan, Craig P; Grabowski, Alena M; McDermott, William J; Herr, Hugh M; Kram, Rodger

    2012-08-07

    Running-specific prostheses (RSF) are designed to replicate the spring-like nature of biological legs (bioL) during running. However, it is not clear how these devices affect whole leg stiffness characteristics or running dynamics over a range of speeds. We used a simple spring-mass model to examine running mechanics across a range of speeds, in unilateral and bilateral transtibial amputees and performance-matched controls. We found significant differences between the affected leg (AL) of unilateral amputees and both ALs of bilateral amputees compared with the bioL of non-amputees for nearly every variable measured. Leg stiffness remained constant or increased with speed in bioL, but decreased with speed in legs with RSPs. The decrease in leg stiffness in legs with RSPs was mainly owing to a combination of lower peak ground reaction forces and increased leg compression with increasing speeds. Leg stiffness is an important parameter affecting contact time and the force exerted on the ground. It is likely that the fixed stiffness of the prosthesis coupled with differences in the limb posture required to run with the prosthesis limits the ability to modulate whole leg stiffness and the ability to apply high vertical ground reaction forces during sprinting.

  2. BIOSIMILAR ARTIFICIAL KNEE FOR TRANSFEMORAL PROSTHESES AND EXOSKELETONS

    Directory of Open Access Journals (Sweden)

    Aleksandr Poliakov

    2016-12-01

    Full Text Available Artificial knees play an important role in transfemoral prostheses, lower extremity exoskeletons and walking robots. Their designs must provide natural kinematics, high strength and stiffness required in the stance phase of gait. Additionally, modern artificial knee is the principal module by means of which the prosthesis control is performed. This paper presents a prototype of an artificial polycentric knee, designed on the basis of the hinge mechanism with cross links. In order to increase strength and stiffness, the elements of the joint have curved supporting surfaces formed in the shape of centroids in relative motion of links of the hinge mechanism. Such construction is a mechanical system with redundant links but it allows for providing desirable characteristics of the artificial knee. Synthesis of the hinge mechanism is made by a method of systematic study of the parameter space, uniformly distributed in a finite dimensional cube. Stiffness of bearing surfaces elements of knee was determined by solving the contact problem with slippage of surfaces relative to each other.

  3. Sol-Gel Deposition of Iridium Oxide for Biomedical Micro-Devices

    Directory of Open Access Journals (Sweden)

    Cuong M. Nguyen

    2015-02-01

    Full Text Available Flexible iridium oxide (IrOx-based micro-electrodes were fabricated on flexible polyimide substrates using a sol-gel deposition process for utilization as integrated pseudo-reference electrodes for bio-electrochemical sensing applications. The fabrication method yields reliable miniature on-probe IrOx electrodes with long lifetime, high stability and repeatability. Such sensors can be used for long-term measurements. Various dimensions of sol-gel iridium oxide electrodes including 1 mm × 1 mm, 500 µm × 500 µm, and 100 µm × 100 µm were fabricated. Sensor longevity and pH dependence were investigated by immersing the electrodes in hydrochloric acid, fetal bovine serum (FBS, and sodium hydroxide solutions for 30 days. Less pH dependent responses, compared to IrOx electrodes fabricated by electrochemical deposition processes, were measured at 58.8 ± 0.4 mV/pH, 53.8 ± 1.3 mV/pH and 48 ± 0.6 mV/pH, respectively. The on-probe IrOx pseudo-reference electrodes were utilized for dopamine sensing. The baseline responses of the sensors were higher than the one using an external Ag/AgCl reference electrode. Using IrOx reference electrodes integrated on the same probe with working electrodes eliminated the use of cytotoxic Ag/AgCl reference electrode without loss in sensitivity. This enables employing such sensors in long-term recording of concentrations of neurotransmitters in central nervous systems of animals and humans.

  4. Deep-blue phosphorescence from perfluoro carbonyl-substituted iridium complexes.

    Science.gov (United States)

    Lee, Sunghun; Kim, Seul-Ong; Shin, Hyun; Yun, Hui-Jun; Yang, Kiyull; Kwon, Soon-Ki; Kim, Jang-Joo; Kim, Yun-Hi

    2013-09-25

    The new deep-blue iridium(III) complexes, (TF)2Ir(pic), (TF)2Ir(fptz), (HF)2Ir(pic), and (HF)2Ir(fptz), consisting of 2',4″-difluororphenyl-3-methylpyridine with trifluoromethyl carbonyl or heptafluoropropyl carbonyl at the 3' position as the main ligand and a picolinate or a trifluoromethylated-triazole as the ancillary ligand, were synthesized and characterized for applications in organic light-emitting diodes (OLEDs). Density function theory (DFT) calculations showed that these iridium complexes had a wide band gap, owing to the introduction of the strong electron withdrawing perfluoro carbonyl group. Time-dependent DFT (TD-DFT) calculations suggested that their lowest triplet excited state was dominated by a HOMO → LUMO transition and that the contribution of the metal-to-ligand charge transfer (MLCT) was higher than 34% for all four complexes, indicating that strong spin-orbit coupling exists in the complexes. The 10 wt % (TF)2Ir(pic) doped 9-(3-(9H-carbazole-9-yl)phenyl)-3-(dibromophenylphosphoryl)-9H-carbazole (mCPPO1) film exhibited the highest photoluminescence quantum yield of 74 ± 3% among the films based on the four complexes. Phosphorescent OLEDs based on (TF)2Ir(pic) and (TF)2Ir(fptz) exhibited maximum external quantum efficiencies of 17.1% and 8.4% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.141, 0.158) and (0.147, 0.116), respectively. These CIE coordinates represent some of the deepest blue emissions ever achieved from phosphorescent OLEDs with considerably high EQEs.

  5. A prospective evaluation of zirconia posterior fixed dental prostheses: three-year clinical results.

    Science.gov (United States)

    Peláez, Jesus; Cogolludo, Pablo G; Serrano, Benjamin; Lozano, Jose F L; Suárez, Maria J

    2012-06-01

    Although the favorable mechanical properties of zirconium oxide-based ceramics have increased the acceptance of fixed dental prostheses for use in the posterior regions of the mouth in recent years, there are few clinical studies documenting the longevity of these restorations. Furthermore, certain complications must be resolved before the material is used more extensively. The purpose of this randomized prospective study was to evaluate the clinical performance of zirconia (Lava) 3-unit posterior fixed dental prostheses. Twenty 3-unit fixed dental prostheses were placed in 17 participants to replace a second premolar or a first molar. Eleven were placed in the maxilla and 9 in the mandible. All abutment teeth were prepared with a chamfer finish line of 0.8 to 1 mm, and frameworks were prepared with the Lava system. Restorations were cemented with a resin cement. Two calibrated examiners independently evaluated the fixed dental prostheses 1 week (baseline) and 1, 2, and 3 years after placement with the California Dental Association quality evaluation system. The periodontal parameters: the gingival index, plaque index, margin index, and the probing depths of abutment teeth and contralateral teeth were assessed. Data were analyzed by using descriptive statistics and the Wilcoxon signed-rank test (α=.05). All fixed dental prostheses were rated satisfactory after 3 years, and no fracture of the framework was observed during the observation period. One fixed dental prostheses was lost because of a biological complication at the 3-year examination, and a small degree of chipping of the veneering ceramic was observed in 2 participants. No significant differences among the periodontal parameters of the test and control teeth were observed except for the margin index. The results of a 3-year evaluation suggest that posterior zirconia 3-unit fixed dental prostheses are a reliable treatment. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry

  6. Iridium anomaly in the cretaceous-paleogene boundary at Højerup (Stevns Klint, Denmark and Woodside Creek (New Zealand: The question of an enormous proportion of extraterrestrial component

    Directory of Open Access Journals (Sweden)

    Premović Pavle I.

    2012-01-01

    Full Text Available The Cretaceous-Paleogene boundary clays at Højerup and Woodside Creek show anomalous enrichments of iridium compared with the marine sedimentary rocks. For the average iridium content of 465 ppb in CI chondrite the estimate of the carbonaceous chondritic proportions in the decarbonated iridium-rich boundary layers, based on the integrated iridium fluencies, is about 26% at Højerup and 65% at Woodside Creek. These proportions are most likely too high due to a significant Ir influx from the nearby marine or continental site to these sections.

  7. Fabrication of low cost soft tissue prostheses with the desktop 3D printer

    Science.gov (United States)

    He, Yong; Xue, Guang-Huai; Fu, Jian-Zhong

    2014-11-01

    Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods.

  8. Adherence of Staphylococcus aureus to Dyneema Purity® Patches and to Clinically Used Cardiovascular Prostheses.

    Science.gov (United States)

    Basir, Amir; Gründeman, Paul; Moll, Frans; van Herwaarden, Joost; Pasterkamp, Gerard; Nijland, Reindert

    2016-01-01

    Various materials that are used for vascular and heart valve prostheses carry drawbacks: some require anticoagulant drugs or have moderate durability; others are not suitable for endovascular treatment. These prostheses are associated with bacterial infections. A material potentially suitable for prostheses is Dyneema Purity®, made of ultra-high-molecular-weight polyethylene. Dyneema Purity® fibers are very thin, flexible, resistant to fatigue and abrasion, and have high strength. S. aureus adherence to Dyneema Purity® was tested and compared with currently used cardiovascular prostheses. We compared adhesion of S. aureus to Dyneema Purity® (1 membrane-based and 1 yarn-composed patch) with 5 clinically used yarn-composed polyester and membrane-based expanded polytetrafluoroethylene patches. Patches were contaminated with S. aureus bacteria and bacterial adherence was quantified. S. aureus adherence was also visualized in flow conditions. Overall, bacterial adherence was higher on yarn-composed prosthesis materials, with a rough surface, than on the membrane-based materials, with a smooth surface. Adherence to Dyneema Purity® materials was non-inferior to the currently used materials. Therefore, patches of Dyneema Purity® might be attractive for use in cardiovascular applications such as catheter-based heart valves and endovascular prostheses by their good mechanical properties combined with their noninferiority regarding bacterial adhesion.

  9. A Study of Ossiculoplasty in Chronic Otitis Media using different types of Prostheses

    Directory of Open Access Journals (Sweden)

    Parthapratim Laha

    2013-12-01

    Full Text Available Abstract Introduction: A wide range of prostheses, autologus and synthetic are available for use these days. Ideally, the ossicular reconstruction prosthesis should be biocompatible, safe, easy to handle and capable of efficient sound transmission. Aim and objectives: To study operative ease and post-operative hearing results in patients undergoing ossiculoplasty with different types of prostheses. Materials and methods: A prospective randomized study of 25 patients with Chronic Otitis Media, undergoing ossiculoplasty was conducted at Command Hospital, Kolkata. Tragal cartilage was used in 05 patients, conchal cartilage in 05, refashioned incus in 05, hydroxyapatite in 05 and titanium prostheses in 05 patients. Subjects with mixed hearing loss, multiple co-morbidities and revision surgeries were excluded. Hearing assessment was done by pure tone audiometry pre-operatively and 04 and 12 weeks postoperatively. Results were analyzed statistically. Results: Using tragal or conchal cartilage took almost equal time as autologus incus. Using synthetic material saved time. Titanium prosthesis gives maximum surgical ease. Post-operative air-bone gap reduction within 20 dB was seen in all, irrespective of type of prostheses.  Conclusion: Surgical ease is considerably better with titanium prostheses; however hearing results are equally good in all.

  10. Fabrication of low cost soft tissue prostheses with the desktop 3D printer.

    Science.gov (United States)

    He, Yong; Xue, Guang-huai; Fu, Jian-zhong

    2014-11-27

    Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods.

  11. Fabrication of low cost soft tissue prostheses with the desktop 3D printer

    Science.gov (United States)

    He, Yong; Xue, Guang-huai; Fu, Jian-zhong

    2014-01-01

    Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods. PMID:25427880

  12. Adherence of Staphylococcus aureus to Dyneema Purity® Patches and to Clinically Used Cardiovascular Prostheses.

    Directory of Open Access Journals (Sweden)

    Amir Basir

    Full Text Available Various materials that are used for vascular and heart valve prostheses carry drawbacks: some require anticoagulant drugs or have moderate durability; others are not suitable for endovascular treatment. These prostheses are associated with bacterial infections. A material potentially suitable for prostheses is Dyneema Purity®, made of ultra-high-molecular-weight polyethylene. Dyneema Purity® fibers are very thin, flexible, resistant to fatigue and abrasion, and have high strength. S. aureus adherence to Dyneema Purity® was tested and compared with currently used cardiovascular prostheses. We compared adhesion of S. aureus to Dyneema Purity® (1 membrane-based and 1 yarn-composed patch with 5 clinically used yarn-composed polyester and membrane-based expanded polytetrafluoroethylene patches. Patches were contaminated with S. aureus bacteria and bacterial adherence was quantified. S. aureus adherence was also visualized in flow conditions. Overall, bacterial adherence was higher on yarn-composed prosthesis materials, with a rough surface, than on the membrane-based materials, with a smooth surface. Adherence to Dyneema Purity® materials was non-inferior to the currently used materials. Therefore, patches of Dyneema Purity® might be attractive for use in cardiovascular applications such as catheter-based heart valves and endovascular prostheses by their good mechanical properties combined with their noninferiority regarding bacterial adhesion.

  13. Zirconia-Based Screw-Retained Prostheses Supported by Implants: A Retrospective Study on Technical Complications and Failures.

    Science.gov (United States)

    Worni, Andreas; Kolgeci, Lumni; Rentsch-Kollar, Andrea; Katsoulis, Joannis; Mericske-Stern, Regina

    2015-12-01

    Little information is yet available on zirconia-based prostheses supported by implants. To evaluate technical problems and failures of implant-supported zirconia-based prostheses with exclusive screw-retention. Consecutive patients received screw-retained zirconia-based prostheses supported by implants and were followed over a time period of 5 years. The implant placement and prosthetic rehabilitation were performed in one clinical setting, and all patients participated in the maintenance program. The treatment comprised single crowns (SCs) and fixed dental prostheses (FDPs) of three to 12 units. Screw-retention of the CAD/CAM-fabricated SCs and FDPs was performed with direct connection at the implant level. The primary outcome was the complete failure of zirconia-based prostheses; outcome measures were fracture of the framework or extensive chipping resulting in the need for refabrication. A life table analysis was performed, the cumulative survival rate (CSR) calculated, and a Kaplan-Meier curve drawn. Two hundred and ninety-four implants supported 156 zirconia-based prostheses in 95 patients (52 men, 43 women, average age 59.1 ± 11.7 years). Sixty-five SCs and 91 FDPs were identified, comprising a total of 441 units. Fractures of the zirconia framework and extensive chipping resulted in refabrication of nine prostheses. Nearly all the prostheses (94.2%) remained in situ during the observation period. The 5-year CSR was 90.5%, and 41 prostheses (14 SCs, 27 FDPs) comprising 113 units survived for an observation time of more than 5 years. Six SCs exhibited screw loosening, and polishing of minor chipping was required for five prostheses. This study shows that zirconia-based implant-supported fixed prostheses exhibit satisfactory treatment outcomes and that screw-retention directly at the implant level is feasible. © 2014 Wiley Periodicals, Inc.

  14. Development of a luminescent G-quadruplex-selective iridium(III) complex for the label-free detection of adenosine

    Science.gov (United States)

    Lu, Lihua; Zhong, Hai-Jing; He, Bingyong; Leung, Chung-Hang; Ma, Dik-Lung

    2016-01-01

    A panel of six luminescent iridium(III) complexes were synthesized and evaluated for their ability to act as G-quadruplex-selective probes. The novel iridium(III) complex 1 was found to be highly selective for G-quadruplex DNA, and was employed for the construction of a label-free G-quadruplex-based adenosine detection assay in aqueous solution. Two different detection strategies were investigated for adenosine detection, and the results showed that initial addition of adenosine to the adenosine aptamer gave superior results. The assay exhibited a linear response for adenosine in the concentration range of 5 to 120 μM (R2 = 0.992), and the limit of detection for adenosine was 5 μM. Moreover, this assay was highly selective for adenosine over other nucleosides, and exhibited potential use for biological sample analysis.

  15. Solution-processable deep red-emitting supramolecular phosphorescent polymer with novel iridium complex for organic light-emitting diodes

    Science.gov (United States)

    Liang, Aihui; Huang, Gui; Wang, Zhiping; Wu, Wenjin; Zhong, Yu; Zhao, Shan

    2016-09-01

    A novel bis(dibenzo-24-crown-8)-functionalized iridium complex with an emission peak at 665 nm was synthesized. Several deep red-emitting supramolecualr phosphorescent polymers (SPPs) as a class of solutionprocessable electroluminescent (EL) emitters were formed by utilizing the efficient non-bonding self-assembly between the resulting iridium complex and bis(dibenzylammonium)-tethered monomers. These SPPs show an intrinsic glass transition with a T g of ca. 90 °C. The photophysical and electroluminescent properties are strongly dependent on the hosts' structures of the supramolecular phosphorescent polymers. The polymer light-emitting diode based on SPP3 displayed a maximal external quantum efficiency (EQE) of 2.14% ph·el-1 and the Commission Internationale de L'Eclairage (CIE) coordinates of (0.70, 0.29).

  16. Dentistry investigations of teeth and dental prostheses using OCT

    Science.gov (United States)

    Sinescu, C.; Duma, V.-F.; Canjau, S.; Dobre, G.; Demian, D.; Cernat, R.; Negrutiu, M. L.; Todea, C.; Topala, F. I.; Hutiu, Gh.; Bradu, A.; Podoleanu, A. G.

    2016-04-01

    We present some of our recent investigations in Dental Medicine using Optical Coherence Tomography (OCT). Time Domain (TD), Spectral Domain (SD), and Swept Source (SS) OCT in-house developed systems are being used, for both ex vivo and in vivo investigations in the oral cavity. We study ex vivo the interface between the tooth and the dental sealant and demonstrate the limitations of the X-rays investigations that are now the gold standard for such procedures. Using OCT, defects in the interface that cannot be identified in radiographs can be determined both as position and magnitude. The drilling process of teeth can also be characterized in real time using OCT, to monitor the remaining dentin thickness (RDT) in order to avoid opening the pulp chamber. We demonstrate in this respect that an RDT of 0.5 mm is the minimum value to assure the integrity of the dentin wall between the drilled cavity and the pulp chamber; at an RDT of 0.3 mm or less a fracture is initiated, the dentin is punctured and endodontic treatment must follow. In vivo OCT investigations in the oral cavity were also performed (i.e., for metalloceramic prostheses and for ceramic inlay tooth interfaces), with the low cost, light weight and versatile handheld probes with 1D galvoscanners that we have developed and applied for a range of in-house developed OCT systems, in various clinical applications. They are briefly discussed, as well as some of our current and future work in the field, including for studies of soft tissue in the mouth.

  17. Full-arch prostheses from translucent zirconia: accuracy of fit.

    Science.gov (United States)

    Sachs, Caroline; Groesser, Julian; Stadelmann, Markus; Schweiger, Josef; Erdelt, Kurt; Beuer, Florian

    2014-08-01

    The aim of this study was to evaluate the marginal and internal fit of single crowns, compared to 14-unit frameworks made of translucent yttria-stabilized zirconia. We hypothesized that there is an influence of the type of restoration on the marginal and internal fit. Eight teeth (FDI locations 17, 15, 13, 11, 21, 23, 25 and 27) of a typodont maxillary model were provided with a chamfer preparation to accommodate a 14-unit prosthesis or four single crowns (SCs). Ten 14-unit fixed dental prostheses (FDPs) and 40 single crowns were fabricated using a computer aided design (CAD)/computer aided manufacturing (CAM) system with pre-sintered translucent yttria-stabilized zirconia blanks. The restorations were cemented onto twenty master dies, which were sectioned into four pieces each. Then, the marginal and internal fits were examined using a binocular microscope. In order to detect the differences between the two types of restorations a non-parameteric test (Mann-Whitney-U) was carried out; to detect differences between the abutment teeth and the abutment surfaces non-parametric tests (Kruskal-Wallis) and pairwise post hoc analyses (Mann-Whitney-U) were performed after testing data for normal distribution (method according to Shapiro-Wilk). Level of significance was set at 5%. The mean (SD) marginal opening gap dimensions were 18 μm (14) for the single crowns and 29 μm (27) for the 14-unit FDPs (p<0.001). Abutment 21 of the FDPs showed statistical differences concerning the location of the teeth in both marginal and internal fit (p<0.001). The measured gaps (types I-IV) revealed statistical differences between all types, when comparing SCs to the FDPs (p<0.001). Single crowns showed significantly better accuracy of fit, compared to the 14-unit FDPs. However, both restorations showed clinically acceptable marginal and internal fit. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Amputee locomotion: lower extremity loading using running-specific prostheses.

    Science.gov (United States)

    Hobara, Hiroaki; Baum, Brian S; Kwon, Hyun-Joon; Linberg, Alison; Wolf, Erik J; Miller, Ross H; Shim, Jae Kun

    2014-01-01

    Carbon fiber running-specific prostheses (RSPs) have allowed individuals with lower extremity amputation (ILEA) to actively participate in sporting activities including competitive sports. In spite of this positive trait, the RSPs have not been thoroughly evaluated regarding potential injury risks due to abnormal loading during running. Vertical impact peak (VIP) and average loading rate (VALR) of the vertical ground reaction force (vGRF) have been associated with running injuries in able-bodied runners but not for ILEA. The purpose of this study was to investigate vGRF loading in ILEA runners using RSPs across a range of running speeds. Eight ILEA with unilateral transtibial amputations and eight control subjects performed overground running at three speeds (2.5, 3.0, and 3.5m/s). From vGRF, we determined VIP and VALR, which was defined as the change in force divided by the time of the interval between 20 and 80% of the VIP. We observed that VIP and VALR increased in both ILEA and control limbs with an increase in running speed. Further, the VIP and VALR in ILEA intact limbs were significantly greater than ILEA prosthetic limbs and control subject limbs for this range of running speeds. These results suggest that (1) loading variables increase with running speed not only in able-bodied runners, but also in ILEA using RSPs, and (2) the intact limb in ILEA may be exposed to a greater risk of running related injury than the prosthetic limb or able-bodied limbs. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Color-tuning and stability enhancement of cyclometallated iridium (III) complexes in light-emitting electrochemical cells

    OpenAIRE

    Bünzli, Andreas

    2015-01-01

    In this thesis, the design and synthesis of cyclometallated iridium(III) complexes for use in light-emitting electrochemical cells (LEECs) are presented, divided into six chapters. Focus is put on the emission color-tuning of various compounds, covering almost the whole visible spectrum between blue and red including first steps towards white-light emission. Secondly, a new systematic approach for an intrinsic stability enhancement of highly pure Ir(III) complexes is investigated. The work is...

  20. Enhanced anti-Diastereo- and Enantioselectivity in Alcohol Mediated Carbonyl Crotylation Using an Isolable Single Component Iridium Catalyst

    OpenAIRE

    Gao, Xin; Townsend, Ian A.; Krische, Michael J.

    2011-01-01

    The cyclometallated iridium complex (S)-I derived from [Ir(cod)Cl]2, 4-cyano-3-nitrobenzoic acid, allyl acetate and (S)-SEGPHOS is conveniently isolated by precipitation or through conventional silica gel flash chromatography. This single component precatalyst allows alcohol mediated carbonyl crotylations to be performed at significantly lower temperature, resulting in enhanced levels of anti-diastereo- and enantioselectivity. Most significantly, the chromatographically isolated precatalyst (...

  1. An unusual highly emissive water-soluble iridium lissamine-alanine complex and its use in a molecular logic gate.

    Science.gov (United States)

    Oliveira, Elisabete; Santos, Sérgio M; Núñez, Cristina; Capelo, José Luis; Lodeiro, Carlos

    2016-01-21

    The interaction of iridium(iii) with a new lissamine rhodamine B sulfonyl derivative, bearing alanine as a building block, (1) with an orange emission in water results in a green highly emissive Ir@1 complex at room temperature. The new Ir@1 complex can sense the toxic Hg(2+) metal ion and cysteine. Based on such properties, a new sophisticated molecular logic gate with three inputs was designed.

  2. Psychophysiological analyses demonstrate the importance of neural envelope coding for speech perception in noise

    Science.gov (United States)

    Swaminathan, Jayaganesh; Heinz, Michael G.

    2012-01-01

    Understanding speech in noisy environments is often taken for granted; however, this task is particularly challenging for people with cochlear hearing loss, even with hearing aids or cochlear implants. A significant limitation to improving auditory prostheses is our lack of understanding of the neural basis for robust speech perception in noise. Perceptual studies suggest the slowly varying component of the acoustic waveform (envelope, ENV) is sufficient for understanding speech in quiet, but the rapidly varying temporal fine structure (TFS) is important in noise. These perceptual findings have important implications for cochlear implants, which currently only provide ENV; however, neural correlates have been difficult to evaluate due to cochlear transformations between acoustic TFS and recovered neural ENV. Here, we demonstrate the relative contributions of neural ENV and TFS by quantitatively linking neural coding, predicted from a computational auditory-nerve model, with perception of vocoded speech in noise measured from normal-hearing human listeners. Regression models with ENV and TFS coding as independent variables predicted speech identification and phonetic-feature reception at both positive and negative signal-to-noise ratios. We found that 1) neural ENV coding was a primary contributor to speech perception, even in noise, and 2) neural TFS contributed in noise mainly in the presence of neural ENV, but rarely as the primary cue itself. These results suggest neural TFS has less perceptual salience than previously thought due to cochlear signal-processing transformations between TFS and ENV. Because these transformations differ between normal and impaired ears, these findings have important translational implications for auditory prostheses. PMID:22302814

  3. Iridium-coated micropore x-ray optics using dry etching of a silicon wafer and atomic layer deposition.

    Science.gov (United States)

    Ogawa, Tomohiro; Ezoe, Yuichiro; Moriyama, Teppei; Mitsuishi, Ikuyuki; Kakiuchi, Takuya; Ohashi, Takaya; Mitsuda, Kazuhisa; Putkonen, Matti

    2013-08-20

    To enhance x-ray reflectivity of silicon micropore optics using dry etching of silicon (111) wafers, iridium coating is tested by use of atomic layer deposition. An iridium layer is successfully formed on sidewalls of tiny micropores with a pore width of 20 μm and depth of 300 μm. The film thickness is ∼20  nm. An enhanced x-ray reflectivity compared to that of silicon is confirmed at Ti Kα 4.51 keV, for what we believe to be the first time, with this type of optics. Some discrepancies from a theoretical reflectivity curve of iridium-coated silicon are noticed at small incident angles <1.3°. When a geometrical shadowing effect due to occultation by a ridge existing on the sidewalls is taken into account, the observed reflectivity becomes well represented by the modified theoretical curve. An estimated surface micro roughness of ∼1  nm rms is consistent with atomic force microscope measurements of the sidewalls.

  4. Design of Research on Performance of a New Iridium Coordination Compound for the Detection of Hg2+

    Directory of Open Access Journals (Sweden)

    Hailing Ma

    2017-10-01

    Full Text Available Heavy metal pollution has become one of the most significant pollution problems encountered by our country in terms of environment protection. In addition to the significant effects of heavy metals on the human body and other organisms through water, food chain enrichment and other routes, heavy metals involved in daily necessities beyond the level limit could also affect people’s lives, so the detection of heavy metals is extremely important. Ir (III coordination compound, considered to be one of the best phosphorescent sensing materials, is characterized by high luminous efficiency, easy modification of the ligand and so on, and it has potential applications in the field of heavy metal detection. This project aims to product a new Ir (III functional coordination compound by designing a new auxiliary ligand and a main ligand with a sulfur identification unit, in order to systematically investigate the application of iridium coordination compound in the detection of the heavy metal Hg2+. With the introduction of the sulfur identification unit, selective sensing of Hg2+ could be achieved. Additionally, a new auxiliary ligand is also introduced to produce a functional iridium coordination compound with high quantum efficiency, and to diversify the application of iridium coordination compound in this field.

  5. Using iridium films to compensate for piezo-electric materials processing stresses in adjustable x-ray optics

    Science.gov (United States)

    Ames, A.; Bruni, R.; Cotroneo, V.; Johnson-Wilke, R.; Kester, T.; Reid, P.; Romaine, S.; Tolier-McKinstry, S.; Wilke, R. H. T.

    2015-09-01

    Adjustable X-ray optics represent a potential enabling technology for simultaneously achieving large effective area and high angular resolution for future X-ray Astronomy missions. The adjustable optics employ a bimorph mirror composed of a thin (1.5 μm) film of piezoelectric material deposited on the back of a 0.4 mm thick conical mirror segment. The application of localized electric fields in the piezoelectric material, normal to the mirror surface, result in localized deformations in mirror shape. Thus, mirror fabrication and mounting induced figure errors can be corrected, without the need for a massive reaction structure. With this approach, though, film stresses in the piezoelectric layer, resulting from deposition, crystallization, and differences in coefficient of thermal expansion, can distort the mirror. The large relative thickness of the piezoelectric material compared to the glass means that even 100MPa stresses can result in significant distortions. We have examined compensating for the piezoelectric processing related distortions by the deposition of controlled stress chromium/iridium films on the front surface of the mirror. We describe our experiments with tuning the product of the chromium/iridium film stress and film thickness to balance that resulting from the piezoelectric layer. We also evaluated the repeatability of this deposition process, and the robustness of the iridium coating.

  6. Progress in the clinical development and utilization of vision prostheses: an update

    Directory of Open Access Journals (Sweden)

    Brandli A

    2016-05-01

    Full Text Available Alice Brandli, Chi D Luu, Robyn H Guymer, Lauren N Ayton Centre for Eye Research Australia, Department of Surgery (Ophthalmology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, VIC, Australia Abstract: Vision prostheses, or “bionic eyes”, are implantable medical bionic devices with the potential to restore rudimentary sight to people with profound vision loss or blindness. In the past two decades, this field has rapidly progressed, and there are now two commercially available retinal prostheses in the US and Europe, and a number of next-generation devices in development. This review provides an update on the development of these devices and a discussion on the future directions for the field. Keywords: vision prostheses, bionic eye, vision restoration, blindness, medical bionics, retinitis pigmentosa

  7. Hybrid Invariance and Stability of a Feedback Linearizing Controller for Powered Prostheses.

    Science.gov (United States)

    Martin, Anne E; Gregg, Robert D

    2015-07-01

    The development of powered lower-limb prostheses has the potential to significantly improve amputees' quality of life. By applying advanced control schemes, such as hybrid zero dynamics (HZD), to prostheses, more intelligent prostheses could be designed. Originally developed to control bipedal robots, HZD-based control specifies the motion of the actuated degrees of freedom using output functions to be zeroed, and the required torques are calculated using feedback linearization. Previous work showed that an HZD-like prosthesis controller can successfully control the stance period of gait. This paper shows that an HZD-based prosthesis controller can be used for the entire gait cycle and that feedback linearization can be performed using only information measured with on-board sensors. An analytic metric for orbital stability of a two-step periodic gait is developed. The results are illustrated in simulation.

  8. ["Bionic" arm prostheses. State of the art in research and development].

    Science.gov (United States)

    Pylatiuk, C; Döderlein, L

    2006-11-01

    A new generation of arm prostheses is being developed worldwide. These so-called bionic prostheses are intended to offer additional functions, such as sensory feedback, extended range of possible movement, intuitive movement control as far as possible, and a more natural cosmetic appearance. In recent years, prosthetic components with much enhanced performance have been developed for use at various levels of the upper limb. Artificial hands that allow for additional grips are are being tested in clinical settings. Innovative methods of signal acquisition and communication with the patient are being intensively researched. Several patients have been provided with prototypes of new arm prostheses. At the moment, the results are limited by the restricted communication between patient and prosthesis. However, we can expect the options for prosthesis control to be extended in the near future.

  9. Usefulness of magnetic resonance imaging in the postsurgical assessment of patients with inflatable penile prostheses.

    Science.gov (United States)

    Pacheco Usmayo, A; Torregrosa Andrés, A; Flores Méndez, J; Luján Marco, S; Rogel Bertó, R

    To describe the types of penile prostheses and their components, to review the appropriate magnetic resonance imaging (MRI) acquisition protocol, and to describe the normal imaging findings and possible complications in patients with inflatable penile implants. Three-piece inflatable penile prostheses are the last link in the treatment chain for erectile dysfunction. They can develop complications, which are classified as non-infectious related to the surgical technique, infectious, or due to mechanical failure of the device. MRI is the most appropriate imaging technique for the postsurgical evaluation of penile prostheses. Images are acquired in three planes using sequences with high spatial resolution, first with the prosthesis at rest and then with the prosthesis activated. Copyright © 2017 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

  10. Prevention of biofilm formation by dairy products and N-acetylcysteine on voice prostheses in an artificial throat

    NARCIS (Netherlands)

    Schwandt, LQ; Van Weissenbruch, R; Stokroos, [No Value; Van der Mei, HC; Busscher, HJ; Albers, FWJ

    Objective - To evaluate the preventive effect of buttermilk, Yakult Light fermented milk drink and N-acetylcysteine on biofilm formation on voice prostheses in vitro. Material and Methods - Groningen button and Provox(R) 2 voice prostheses were inoculated with a mixture of bacteria and yeasts

  11. Adhesion to silicone rubber of yeasts and bacteria isolated from voice prostheses : Influence of salivary conditioning films

    NARCIS (Netherlands)

    Busscher, HJ; GeertsemaDoornbusch, GI; vanderMei, HC

    Adhesion of yeasts and bacteria to silicone rubber is one of the first steps in the biodeterioration of silicone rubber voice prostheses. In this paper, adhesion of two streptococcal, staphylococcal, Candida albicans and Candida tropicalis strains, isolated from explanted voice prostheses was

  12. EVALUATION OF TEMPOROMANDIBULAR-JOINT PROSTHESES - REVIEW OF THE LITERATURE FROM 1946 TO 1994 AND IMPLICATIONS FOR FUTURE PROSTHESIS DESIGNS

    NARCIS (Netherlands)

    VANLOON, JP; DEBONT, LGM; BOERING, G

    Purpose: This article describes the useful elements of applied temporomandibular joint (TMJ) prostheses and discusses the factors necessary to be addressed in an appropriate TMJ prosthesis design. Materials and Methods: Information about TMJ prostheses was gathered by a literature search, Only

  13. Distal cantilever in full-arch prostheses and immediate loading: a retrospective clinical study.

    Science.gov (United States)

    Romanos, Georgios E; Gupta, Bhumija; Gaertner, Kathrin; Nentwig, Georg-Hubertus

    2014-01-01

    The purpose of this study was to analyze and evaluate the clinical success of distal cantilevers of fixed full-arch prostheses for the rehabilitation of edentulous arches in conjunction with immediate loading. Twenty-seven patients (15 men and 12 women) with a mean age of 59 years received 203 implants (Ankylos, Dentsply), either in edentulous jaws or after extraction and immediate implant placement. All implants were splinted together with provisional restorations and loaded immediately after surgery. After an average of 60 days, the definitive prostheses were fabricated and cemented provisionally. Thirty-one prostheses were delivered. A total of 92 units on distal cantilevers were incorporated into the prostheses. Implant stability was recorded (via percussion testing) after prostheses were removed and crestal bone levels were measured with radiographs. Average crestal bone loss was 0.33 mm. After a follow-up of 5 years, only one prosthesis broke (at the connection between the main part of the denture and the distal extension). A total of five implants were lost because of overloading or peri-implantitis (during early healing). The success rate of implants was 94.5%, the survival rate was 97.5%, and the survival rate of the prostheses was 96.7% after a loading period of 79.30 ± 35.31 months. Based on the long-term clinical data, distal cantilevers on a full-arch prosthesis can be a successful treatment modality and can be employed in patient treatment planning when posterior support is indicated.

  14. Endoskeletal ossicular reconstruction using the Kraus K-Helix Crown and Piston middle ear prostheses.

    Science.gov (United States)

    Kraus, Eric M; Christopher, Julia Y

    2010-01-01

    The Kraus K-Helix Crown and Piston prostheses are novel, newly designed, MRI compatible, titanium ossicular replacement prostheses that have received U.S. Food and Drug Administration clearance in March of 2008 for ossiculoplasty. Reconstruction is indicated to restore sound conduction of the ossicular chain during tympanoplasty in chronic and non-chronic ears. The prostheses have been specifically developed for reconstruction of an eroded or absent long process of the incus and an eroded or absent stapes superstructure. They may be used with or without glass-ionomer cement. The prostheses may be implanted incus-to-stapes or malleus-to-stapes (K-Helix Crown) or may be implanted incus-to-footplatelneo-membrane or malleus-to-footplate/neo-membrane (K-Helix Piston). The K-Helix Piston is useful during revision stapedectomy when an eroded long process of the incus is encountered. By coating the K-Helix prostheses with glass-ionomer cement, it is possible to perform "endoskeletal ossicular reconstruction" which greatly enhances long-term prosthesis stability and avoids contact with the tympanic membrane. The prostheses may be custom-fit to reconstruct each individual patient's anatomy. Preliminary hearing results in a small cohort of patients at one year indicate very satisfactory hearing results with closure of the air-bone gap in the majority of patients. The ENT OR nurse plays a role in the use of specialized, adjunctive OR equipment that is used with the technology, is required for the preparation of glass-ionomer cement, and provides patients with important educational information concerning reconstructive otologic procedures.

  15. Three-dimensional evaluation of gaps associated with fixed dental prostheses fabricated with new technologies.

    Science.gov (United States)

    Kim, Ki-Baek; Kim, Jae-Hong; Kim, Woong-Chul; Kim, Ji-Hwan

    2014-12-01

    One of the most important factors in determining the clinical outcomes of fixed dental prostheses is the gap between the fixed dental prosthesis and the abutment. However, reports that investigated these gaps in the context of fixed dental prostheses fabricated with new technologies are few. The purpose of this study was to measure and analyze the fit of fixed dental prostheses. The fixed dental prostheses for the study were produced with the subtractive method (milling soft metal blocks), additive method (selective laser sintering), and traditional method (lost wax and casting). Ten specimens were fabricated with the soft metal block, selective laser sintering, and lost wax and casting methods. The 3-dimensional measurement method was adopted to obtain the measure gap figures of the specimens. To fabricate a digital replica, computer-aided design reference casts were prepared by scanning the study casts, and silicone replicas were fabricated for each specimen. These silicone replicas were scanned and obtained 40,000 point cloud data. The study also defined the mean gap for each specimen by averaging approximately 40,000 gap points to evaluate the fit of the specimens. Data were analyzed with 1-way ANOVA and the Tukey honestly significant difference (α=.05). The mean gap was the smallest for fixed dental prostheses fabricated with the soft metal block, followed by the selective laser sintering, then the lost wax and casting. One-way ANOVA revealed statistically significant differences in the size of the gap among the 3 groups (Pselective laser sintering techniques was better than that obtained with the traditional lost wax and casting method. Thus, fixed dental prostheses produced by using these new techniques can be considered clinically acceptable. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  16. Complications after treating esophageal strictures with prostheses and stents – 20 years’ experience

    Directory of Open Access Journals (Sweden)

    Mariusz P. Łochowski

    2016-12-01

    Full Text Available Introduction : Over 80% of patients with esophageal cancer are qualified only for palliative treatment. The main goal of the therapy is to eliminate symptoms of dysphagia. Aim: To analyze complications after insertion of prostheses and stents in patients with inoperable cancer of the esophagus/cardia. Material and methods : From 1996 to 2015 prostheses of the esophagus were implanted in 1309 patients. In the strictures of the lower part of the esophagus, Barbin-Mousseau prostheses (102 cases and Häring prostheses (324 cases were placed. In the strictures of the upper and middle part of the esophagus, Wilson-Cook prostheses (65 cases and Sumi prostheses (51 cases were implanted using rigid oesophagoscopy. Since 2001, 867 esophageal stents have been implanted. Results: Complications occurred in 146 (11% patients, including 7 (0.6% cases of death. The most common complication was the recurrence of swallowing disorders (74 patients. In 51 patients, tumor overgrowth over the stent/prosthesis was responsible for that symptom, and in 23 patients its clogging. A fistula (22 cases and the passage of the prosthesis/stent (25 cases were the second most common group of complications. Compression of the trachea, bleeding, and dehiscence of wounds occurred in a total of 18 patients. Complications were mostly treated through the repositioning of the prosthesis/stent or the insertion of an additional one. Conclusions : The most common complications after esophageal prosthetics are the recurrence of dysphagia, a fistula and the displacement of the prosthesis/stent. The basic treatment of complications is the repositioning or insertion of an additional prosthesis.

  17. Optimization of tomotherapy treatment planning for patients with bilateral hip prostheses

    OpenAIRE

    Chapman, David; Smith, Shaun; Barnett, Rob; Bauman, Glenn; Yartsev, Slav

    2014-01-01

    Background To determine the effect of different imaging options and the most efficient imaging strategy for treatment planning of patients with hip prostheses. Methods The planning kilovoltage CT (kVCT) and daily megavoltage CT (MVCT) studies for three prostate cancer patients with bilateral hip prostheses were used for creating hybrid kVCT/MVCT image sets. Treatment plans were created for kVCT images alone, hybrid kVCT/MVCT images, and MVCT images alone using the same dose prescription and p...

  18. An innovative prostheses design for rehabilitation of severely mutilated dentition: a case report

    Science.gov (United States)

    2011-01-01

    Partial edentulism has multiple implications in relation to function, esthetics and future rehabilitative treatment. This case report illustrates the management of a patient with extreme consequences of partial edentulism. The main clinical findings were unopposed remaining teeth, overeruption of the remaining teeth, loss of vertical dimension of occlusion, and significant disfigurement of the occlusal plane. Following the diagnostic procedure, a well-coordinated prosthodontic treatment involving liaison with other dental disciplines was indicated. The management involved an innovative combination of fixed and removable prostheses in conjunction with crown lengthening surgery and strategic implant placement. Series of provisional prostheses were applied to facilitate the transition to the final treatment. PMID:21503192

  19. Separation of rhodium(III and iridium(IV chlorido species by quaternary diammonium centres hosted on silica microparticles

    Directory of Open Access Journals (Sweden)

    A. Majavu

    2017-12-01

    Full Text Available Silica gel was functionalized with six different quaternary diammonium centres derived from ethylenediamine (EDA, tetramethylenediamine (TMDA, hexamethylenediamine (HMDA, 1,8-diaminooctane (OMDA, 1,10-diaminodecane (DMDA and 1,12-diaminododecane (DDMDA to produce Si-QUAT EDA, Si-QUAT TMDA, Si-QUAT HMDA, Si-QUAT OMDA, Si-QUAT DMDA and Si-QUAT DDMDA, respectively. The synthesized silica-based resins were characterized by means of FTIR, XPS, SEM, BET surface area, thermogravimetric analysis and elemental analysis. The materials were used to investigate the adsorption and separation of [RhCl5(H2O]2− and [IrCl6]2−. Batch studies (equilibrium and kinetic studies were conducted to study the adsorption of [RhCl5(H2O]2− and [IrCl6]2− onto Si-QUAT EDA, Si-QUAT TMDA, Si-QUAT HMDA, Si-QUAT OMDA, Si-QUAT DMDA and Si-QUAT DDMDA using single metal aqueous solutions. The Freundlich isotherm confirmed multilayer adsorption and the Freundlich constant (kf displayed the following ascending order; Si-QUAT EDA, Si-QUAT TMDA, Si-QUAT HMDA, Si-QUAT OMDA and Si-QUAT DMDA, and a decrease in kf for Si-QUAT DDMDA. Kinetic studies suggest a pseudo-first order kinetic model. Column studies were also conducted for a binary mixture of these metal ion chlorido species ([RhCl5(H2O]2− and [IrCl6]2−. The iridium loading capacities increased as the carbon spacer between the diammonium centres increased in the following order; Si-QUAT EDA, Si-QUAT TMDA, Si-QUAT HMDA, Si-QUAT OMDA and Si-QUAT DMDA (4.56 mg/g, 6.88 mg/g, 14.63 mg/g, 19.01 mg/g and 29.35 mg/g, respectively. It was observed that the iridium loading capacity of Si-QUAT DDMDA decreased to 8.90 mg/g. This paper presents iridium-specific materials that could be applied in solutions of secondary PGMs sources containing rhodium and iridium as well as in feed solutions from ore processing. Keywords: Silica gel, Quaternary diammonium centres, Rhodium, Iridium, Separation

  20. High-latitude poynting flux from combined Iridium and SuperDARN data

    Directory of Open Access Journals (Sweden)

    C. L. Waters

    2004-09-01

    Full Text Available Field-aligned currents convey stress between the magnetosphere and ionosphere, and the associated low altitude magnetic and electric fields reflect the flow of electromagnetic energy to the polar ionosphere. We introduce a new technique to measure the global distribution of high latitude Poynting flux, S||, by combining electric field estimates from the Super Dual Auroral Radar Network (SuperDARN with magnetic perturbations derived using magnetometer data from the Iridium satellite constellation. Spherical harmonic methods are used to merge the data sets and calculate S|| for any magnetic local time (MLT from the pole to 60° magnetic latitude (MLAT. The effective spatial resolutions are 2° MLAT, 2h MLT, and the time resolution is about one hour due to the telemetry rate of the Iridium magnetometer data. The technique allows for the assessment of high-latitude net S|| and its spatial distribution on one hour time scales with two key advantages: (1 it yields the net S|| including the contribution of neutral winds; and (2 the results are obtained without recourse to estimates of ionosphere conductivity. We present two examples, 23 November 1999, 14:00-15:00 UT, and 11 March 2000, 16:00-17:00 UT, to test the accuracy of the technique and to illustrate the distributions of S|| that it gives. Comparisons with in-situ S|| estimates from DMSP satellites show agreement to a few mW/m2 and in the locations of S|| enhancements to within the technique's resolution. The total electromagnetic energy flux was 50GW for these events. At auroral latitudes, S|| tends to maximize in the morning and afternoon in regions less than 5° in MLAT by two hours in MLT having S||=10 to 20mW/m2 and total power up to 10GW. The power poleward of the Region 1 currents is about one

  1. High-latitude poynting flux from combined Iridium and SuperDARN data

    Directory of Open Access Journals (Sweden)

    C. L. Waters

    2004-09-01

    Full Text Available Field-aligned currents convey stress between the magnetosphere and ionosphere, and the associated low altitude magnetic and electric fields reflect the flow of electromagnetic energy to the polar ionosphere. We introduce a new technique to measure the global distribution of high latitude Poynting flux, S||, by combining electric field estimates from the Super Dual Auroral Radar Network (SuperDARN with magnetic perturbations derived using magnetometer data from the Iridium satellite constellation. Spherical harmonic methods are used to merge the data sets and calculate S|| for any magnetic local time (MLT from the pole to 60° magnetic latitude (MLAT. The effective spatial resolutions are 2° MLAT, 2h MLT, and the time resolution is about one hour due to the telemetry rate of the Iridium magnetometer data. The technique allows for the assessment of high-latitude net S|| and its spatial distribution on one hour time scales with two key advantages: (1 it yields the net S|| including the contribution of neutral winds; and (2 the results are obtained without recourse to estimates of ionosphere conductivity. We present two examples, 23 November 1999, 14:00-15:00 UT, and 11 March 2000, 16:00-17:00 UT, to test the accuracy of the technique and to illustrate the distributions of S|| that it gives. Comparisons with in-situ S|| estimates from DMSP satellites show agreement to a few mW/m2 and in the locations of S|| enhancements to within the technique's resolution. The total electromagnetic energy flux was 50GW for these events. At auroral latitudes, S|| tends to maximize in the morning and afternoon in regions less than 5° in MLAT by two hours in MLT having S||=10 to 20mW/m2 and total power up to 10GW. The power poleward of the Region 1 currents is about one-third of the total power, indicating significant energy flux over the polar cap.

  2. Neural Networks

    Directory of Open Access Journals (Sweden)

    Schwindling Jerome

    2010-04-01

    Full Text Available This course presents an overview of the concepts of the neural networks and their aplication in the framework of High energy physics analyses. After a brief introduction on the concept of neural networks, the concept is explained in the frame of neuro-biology, introducing the concept of multi-layer perceptron, learning and their use as data classifer. The concept is then presented in a second part using in more details the mathematical approach focussing on typical use cases faced in particle physics. Finally, the last part presents the best way to use such statistical tools in view of event classifers, putting the emphasis on the setup of the multi-layer perceptron. The full article (15 p. corresponding to this lecture is written in french and is provided in the proceedings of the book SOS 2008.

  3. Nano-biotechnology: carbon nanofibres as improved neural and orthopaedic implants

    Science.gov (United States)

    Webster, Thomas J.; Waid, Michael C.; McKenzie, Janice L.; Price, Rachel L.; Ejiofor, Jeremiah U.

    2004-01-01

    For the continuous monitoring, diagnosis, and treatment of neural tissue, implantable probes are required. However, sometimes such neural probes (usually composed of silicon) become encapsulated with non-conductive, undesirable glial scar tissue. Similarly for orthopaedic implants, biomaterials (usually titanium and/or titanium alloys) often become encapsulated with undesirable soft fibrous, not hard bony, tissue. Although possessing intriguing electrical and mechanical properties for neural and orthopaedic applications, carbon nanofibres/nanotubes have not been widely considered for these applications to date. The present work developed a carbon nanofibre reinforced polycarbonate urethane (PU) composite in an attempt to determine the possibility of using carbon nanofibres (CNs) as either neural or orthopaedic prosthetic devices. Electrical and mechanical characterization studies determined that such composites have properties suitable for neural and orthopaedic applications. More importantly, cell adhesion experiments revealed for the first time the promise these materials have to increase neural (nerve cell) and osteoblast (bone-forming cell) functions. In contrast, functions of cells that contribute to glial scar-tissue formation for neural prostheses (astrocytes) and fibrous-tissue encapsulation events for bone implants (fibroblasts) decreased on PU composites containing increasing amounts of CNs. In this manner, this study provided the first evidence of the future that CN formulations may have towards interacting with neural and bone cells which is important for the design of successful neural probes and orthopaedic implants, respectively.

  4. Immediately loaded mandibular fixed implant prostheses using the all-on-four protocol: a report of 183 consecutively treated patients with 1 year of function in definitive prostheses.

    Science.gov (United States)

    Galindo, Daniel F; Butura, Caesar C

    2012-01-01

    The purpose of this study was to evaluate a specific protocol using four implants to support immediately loaded fixed prostheses to restore edentulous and partially edentulous mandibles and report on the outcome after 1 year of function with the definitive prostheses. A retrospective study was conducted of all patients who were treated between June 2008 and December 2010 with fixed prostheses that were loaded immediately after placement of implants. The provisional prostheses were later replaced with computer-aided design/computer-assisted manufacture titanium frames supporting acrylic resin and denture teeth in the definitive prosthesis. All patients were followed for a minimum of 12 months and were assessed for implant survival and prosthetic performance, with descriptive statistics utilized to demonstrate results. One hundred eighty-three consecutive patients received immediately loaded axial and tilted implants according to the defined protocol. One implant failed, resulting in a 99.86% implant success rate. There were two catastrophic prosthetic failures (fracture of the titanium framework), for a 98.9% prosthetic success rate. Three patients (1.6%) presented with fracture of a prosthetic mandibular incisor tooth. No prosthetic screw loosening or fractures were seen. Radiographic evaluation revealed no major bone loss around dental implants. Based on this retrospective study, the following conclusions can be drawn: (1) this technique appears to provide a highly predictable implant performance; (2) it is necessary to critically evaluate framework design, especially around the connectors for cantilever extensions around the most distal implants; and (3) minor complications related to acrylic resin tooth fracture may be anticipated during the early phases of prosthetic treatment.

  5. Study and development of an Iridium-192 seed for use in ophthalmic cancer; Estudo e desenvolvimento de uma semente de iridio-192 para aplicacao em cancer oftalmico

    Energy Technology Data Exchange (ETDEWEB)

    Mattos, Fabio Rodrigues de

    2013-07-01

    Even ocular tumors are not among the cases with a higher incidence, they affect the population, especially children. The Institute of Energy and Nuclear Research (IPEN-CNEN/SP) in partnership with Escola Paulista de Medicina (UNIFESP), created a project to develop and implement a alternative treatment for ophthalmic cancer that use brachytherapy iridium-192 seeds. The project arose by reason of the Escola Paulista treat many cancer cases within the Unified Health System (SUS) and the research experience of sealed radioactive sources group at IPEN. The methodology was developed from the available infrastructure and the experience of researchers. The prototype seed presents with a core (192-iridium alloy of iridium-platinum) of 3.0 mm long sealed by a capsule of titanium of 0.8 mm outside diameter, 0.05 mm wall thickness and 4,5mm long. This work aims to study and develop a seed of iridium-192 from a platinum-iridium alloy. No study on the fabrication of these seeds was found in available literature. It was created a methodology that involved: characterization of the material used in the core, creation of device for neutron activation irradiation and and seed sealing tests. As a result, proved the feasibility of the method. As a suggestion for future work, studies regarding metrology and dosimetry of these sources and improvement of the methodology should be carried out, for future implementation in national scope. (author)

  6. Transperineal low-dose rate iridium-192 interstitial brachytherapy in cervical carcinoma stage IIB

    Energy Technology Data Exchange (ETDEWEB)

    Budrukkar, A.N.; Shrivastava, S.K.; Jalali, R.; Agarwal, J.P.; Dinshaw, K.A. [Tata Memorial Hospital, Parel, Mumbai (India). Dept. of Radiation Oncology; Deshpande, D.D.; Nehru, R.M. [Tata Memorial Hospital, Parel, Mumbai (India). Dept. of Medical Physics

    2001-10-01

    Purpose: To assess local control, survival and complications in patients with cervical carcinoma Stage IIB treated radically with transperineal Iridium-192 low-dose rate interstitial brachytherapy following external beam radiotherapy. Patients and Methods: 65 women (age 25-70 years, mean 47 years) with cervical carcinoma Stage IIB were initially treated with external beam radiotherapy on a telecobalt or 6 MW linear accelerator to a dose of 50 Gy delivered in 5-6 weeks. After 2-3 weeks of completing external radiation, patients received interstitial brachytherapy with Iridium-192 (activity 0.5-1 mCi/cm) using a Syed-Neblett perineal template. The median dose delivered to the implant volume was 24 Gy (range 20-32 Gy) delivered at an average dose rate of 0.70 Gy/h (range 0.40-1.20 Gy/h). A point defined at 1.5 cm lateral to the central uterine tandem at the level of os was taken as a representative for assessing the dose to the cervix. Mean doses delivered by interstitial brachytherapy to point A, cervix, point B and rectum were 38 Gy, 34 Gy, 16 Gy and 16 Gy, respectively. Results: At a median follow-up of 53 months, the actuarial disease free survival and overall survival for 65 patients at both 5 and 10 years was 64% and 44%, respectively. Response to radiotherapy was a strong predictor of local control with 82% of patients continuing to have pelvic control after initial complete response. Overall, nine (14%) patients had persistent disease, ten (15%) developed a central recurrence after initial control and three patients developed distant metastasis on follow-up. No patient had any immediate treatment-related complication. Late toxicity included grade I-II rectal reactions in five patients and grade IV bladder complication (vesico-vaginal fistula) in two patients. 5 years after treatment, one patient developed intestinal obstruction, which was relieved after conservative management. Two patients developed vaginal stenosis. The 5- and 10-year disease free survival

  7. Efficient red-emitting phosphorescent iridium(III) complexes of fluorinated 2,4-diphenylquinolines

    Energy Technology Data Exchange (ETDEWEB)

    Park, G.Y. [Department of Information Display Engineering, Hongik University, Seoul, 121-791 (Korea, Republic of); Kim, Y.S. [Department of Science, Hongik University, Seoul, 121-791 (Korea, Republic of); Ha, Y.K. [Department of Science, Hongik University, Seoul, 121-791 (Korea, Republic of)]. E-mail: ykha@hongik.ac.kr

    2007-04-23

    Ir({beta}) complexes of fluorinated dpqs(dpq-3-F, dpq-4-CF{sub 3}) as a cyclometallated ligand were prepared and their photonic properties were investigated, where dpq-3-F and dpq-4-CF{sub 3} represent 2-(3-fluoro-phenyl)-4-phenylquinoline and 4-phenyl-2-(4-trifluoromethylphenyl)quinoline, respectively. Fluorinated dpq derivatives were introduced to the iridium complexes to increase the efficiency compared to Ir(dpq){sub 2}(acac) which was recently reported to have emission wavelength of 614 nm with quantum efficiency of 0.14. These fluorinated ligands and their Ir(III) complexes were computationally calculated by ab initio methods to support our experimental results. It was found that the Ir complex containing dpq-3-F ligands exhibits the largest emission efficiency with maximum emission peak at 593.5 nm. The result of ab initio calculation using the time-dependent density functional theory (TD-DFT) showed that the strong {sup 3}MLCT transition of the complex occurs due to the strong coupling between the 5d orbital of the Ir atom and the highest occupied molecular orbitals (HOMOs) of these ligands.

  8. Atomic structure of self-organizing iridium induced nanowires on Ge(001)

    Energy Technology Data Exchange (ETDEWEB)

    Kabanov, N.S., E-mail: n.kabanov@utwente.nl [Faculty of Physics, Moscow State University, 119991 (Russian Federation); Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P. O. Box 217, Enschede 7500 AE (Netherlands); Heimbuch, R.; Zandvliet, H.J.W. [Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P. O. Box 217, Enschede 7500 AE (Netherlands); Saletsky, A.M.; Klavsyuk, A.L. [Faculty of Physics, Moscow State University, 119991 (Russian Federation)

    2017-05-15

    Highlights: • Ir/Ge(001) structure has been studied with DFT calculations and scanning tunneling microscopy. • Ir/Ge(001) nanowires are composed of Ge atoms and Ir atoms are located in subsurface positions. • The regions in the vicinity of the nanowires are very dynamic, even at temperatures as low as 77 K. - Abstract: The atomic structure of self-organizing iridium (Ir) induced nanowires on Ge(001) is studied by density functional theory (DFT) calculations and variable-temperature scanning tunneling microscopy. The Ir induced nanowires are aligned in a direction perpendicular to the Ge(001) substrate dimer rows, have a width of two atoms and are completely kink-less. Density functional theory calculations show that the Ir atoms prefer to dive into the Ge(001) substrate and push up the neighboring Ge substrate atoms. The nanowires are composed of Ge atoms and not Ir atoms as previously assumed. The regions in the vicinity of the nanowires are very dynamic, even at temperatures as low as 77 K. Time-resolved scanning tunneling microscopy measurements reveal that this dynamics is caused by buckled Ge substrate dimers that flip back and forth between their two buckled configurations.

  9. Selective molecular recognition by nanoscale environments in a supported iridium cluster catalyst

    Science.gov (United States)

    Okrut, Alexander; Runnebaum, Ron C.; Ouyang, Xiaoying; Lu, Jing; Aydin, Ceren; Hwang, Son-Jong; Zhang, Shengjie; Olatunji-Ojo, Olayinka A.; Durkin, Kathleen A.; Dixon, David A.; Gates, Bruce C.; Katz, Alexander

    2014-06-01

    The active sites of enzymes are contained within nanoscale environments that exhibit exquisite levels of specificity to particular molecules. The development of such nanoscale environments on synthetic surfaces, which would be capable of discriminating between molecules that would nominally bind in a similar way to the surface, could be of use in nanosensing, selective catalysis and gas separation. However, mimicking such subtle behaviour, even crudely, with a synthetic system remains a significant challenge. Here, we show that the reactive sites on the surface of a tetrairidium cluster can be controlled by using three calixarene-phosphine ligands to create a selective nanoscale environment at the metal surface. Each ligand is 1.4 nm in length and envelopes the cluster core in a manner that discriminates between the reactivities of the basal-plane and apical iridium atoms. CO ligands are initially present on the clusters and can be selectively removed from the basal-plane sites by thermal dissociation and from the apical sites by reactive decarbonylation with the bulky reactant trimethylamine-N-oxide. Both steps lead to the creation of metal sites that can bind CO molecules, but only the reactive decarbonylation step creates vacancies that are also able to bond to ethylene, and catalyse its hydrogenation.

  10. Development of antiferromagnetic Heusler alloys for the replacement of iridium as a critically raw material

    Science.gov (United States)

    Hirohata, Atsufumi; Huminiuc, Teodor; Sinclair, John; Wu, Haokaifeng; Samiepour, Marjan; Vallejo-Fernandez, Gonzalo; O'Grady, Kevin; Balluf, Jan; Meinert, Markus; Reiss, Günter; Simon, Eszter; Khmelevskyi, Sergii; Szunyogh, Laszlo; Yanes Díaz, Rocio; Nowak, Ulrich; Tsuchiya, Tomoki; Sugiyama, Tomoko; Kubota, Takahide; Takanashi, Koki; Inami, Nobuhito; Ono, Kanta

    2017-11-01

    As a platinum group metal, iridium (Ir) is the scarcest element on the earth but it has been widely used as an antiferromagnetic layer in magnetic recording, crucibles and spark plugs due to its high melting point. In magnetic recording, antiferromagnetic layers have been used to pin its neighbouring ferromagnetic layer in a spin-valve read head in a hard disk drive for example. Recently, antiferromagnetic layers have also been found to induce a spin-polarised electrical current. In these devices, the most commonly used antiferromagnet is an Ir-Mn alloy because of its corrosion resistance and the reliable magnetic pinning of adjacent ferromagnetic layers. It is therefore crucial to explore new antiferromagnetic materials without critical raw materials. In this review, recent research on new antiferromagnetic Heusler alloys and their exchange interactions along the plane normal is discussed. These new antiferromagnets are characterised by very sensitive magnetic and electrical measurement techniques recently developed to determine their characteristic temperatures together with atomic structural analysis. Mn-based alloys and compounds are found to be most promising based on their robustness against atomic disordering and large pinning strength up to 1.4 kOe, which is comparable with that for Ir-Mn. The search for new antiferromagnetic films and their characterisation are useful for further miniaturisation and development of spintronic devices in a sustainable manner.

  11. Substrate Arrays of Iridium Oxide Microelectrodes for in Vitro Neuronal Interfacing

    Science.gov (United States)

    Gawad, Shady; Giugliano, Michele; Heuschkel, Marc; Wessling, Börge; Markram, Henry; Schnakenberg, Uwe; Renaud, Philippe; Morgan, Hywel

    2008-01-01

    The design of novel bidirectional interfaces for in vivo and in vitro nervous systems is an important step towards future functional neuroprosthetics. Small electrodes, structures and devices are necessary to achieve high-resolution and target-selectivity during stimulation and recording of neuronal networks, while significant charge transfer and large signal-to-noise ratio are required for accurate time resolution. In addition, the physical properties of the interface should remain stable across time, especially when chronic in vivo applications or in vitro long-term studies are considered, unless a procedure to actively compensate for degradation is provided. In this short report, we describe the use and fabrication of arrays of 120 planar microelectrodes (MEAs) of sputtered Iridium Oxide (IrOx). The effective surface area of individual microelectrodes is significantly increased using electrochemical activation, a procedure that may also be employed to restore the properties of the electrodes as required. The electrode activation results in a very low interface impedance, especially in the lower frequency domain, which was characterized by impedance spectroscopy. The increase in the roughness of the microelectrodes surface was imaged using digital holographic microscopy and electron microscopy. Aging of the activated electrodes was also investigated, comparing storage in saline with storage in air. Demonstration of concept was achieved by recording multiple single-unit spike activity in acute brain slice preparations of rat neocortex. Data suggests that extracellular recording of action potentials can be achieved with planar IrOx MEAs with good signal-to-noise ratios. PMID:19194527

  12. Solvent-Dependent Thermochemistry of an Iridium/Ruthenium H2 Evolution Catalyst.

    Science.gov (United States)

    Brereton, Kelsey R; Pitman, Catherine L; Cundari, Thomas R; Miller, Alexander J M

    2016-11-21

    The hydricity of the heterobimetallic iridium/ruthenium catalyst [Cp*Ir(H)(μ-bpm)Ru(bpy)2](3+) (1, where Cp* = η(5)-pentamethylcyclopentadienyl, bpm = 2,2'-bipyrimidine, and bpy = 2,2'-bipyridine) has been determined in both acetonitrile (63.1 kcal mol(-1)) and water (29.7 kcal mol(-1)). Hydride 1 features a large increase in the hydride donor ability when the solvent is changed from acetonitrile to water. The acidity of 1, in contrast, is essentially solvent-independent because 1 remains strongly acidic in both solvents. On the basis of an X-ray crystallographic study, spectroscopic analysis, and time-dependent density functional theory calculations, the disparate reactivity trends are ascribed to substantial delocalization of the electron density onto both the bpm and bpy ligands in the conjugate base of 1, [Cp*Ir(μ-bpm)Ru(bpy)2](2+) (3). The H2 evolution tendencies of 1 are considered in the context of thermodynamic parameters.

  13. Iridium-catalysed regioselective borylation of carboranes via direct B-H activation

    Science.gov (United States)

    Cheng, Ruofei; Qiu, Zaozao; Xie, Zuowei

    2017-03-01

    Carboranes are carbon-boron molecular clusters, which can be viewed as three-dimensional analogues to benzene. They are finding many applications in medicine, materials and organometallic chemistry. On the other hand, their exceptional thermal and chemical stabilities, as well as 3D structures, make them very difficult to be functionalized, in particular the regioselective functionalization of BH vertex among ten similar B-H bonds. Here we report a very efficient iridium-catalysed borylation of cage B(3,6)-H bonds of o-carboranes with excellent yields and regioselectivity using bis(pinacolato)diboron (B2pin2) as a reagent. Selective cage B(4)-H borylation has also been achieved by introducing a bulky TBDMS (tert-butyldimethylsilyl) group to one cage carbon vertex. The resultant 3,6-(Bpin)2-o-carboranes are useful synthons for the synthesis of a wide variety of B(3,6)-difunctionalized o-carboranes bearing cage B-X (X=O, N, C, I and Br) bonds.

  14. Radiation control in the intensive care unit for high intensity iridium-192 brain implants

    Energy Technology Data Exchange (ETDEWEB)

    Sewchand, W.; Drzymala, R.E.; Amin, P.P.; Salcman, M.; Salazar, O.M.

    1987-04-01

    A bedside lead cubicle was designed to minimize the radiation exposure of intensive care unit staff during routine interstitial brain irradiation by removable, high intensity iridium-192. The cubicle shields the patient without restricting intensive care routines. The design specifications were confirmed by exposure measurements around the shield with an implanted anthropomorphic phantom simulating the patient situation. The cubicle reduces the exposure rate around an implant patient by as much as 90%, with the exposure level not exceeding 0.1 mR/hour/mg of radium-equivalent /sup 192/Ir. Evaluation of data accumulated for the past 3 years has shown that the exposure levels of individual attending nurses are 0.12 to 0.36 mR/mg of radium-equivalent /sup 192/Ir per 12-hour shift. The corresponding range for entire nursing teams varies between 0.18 and 0.26. A radiation control index (exposure per mg of radium-equivalent /sup 192/Ir per nurse-hour) is thus defined for individual nurses and nursing teams; this index is a significant guide to the planning of nurse rotations for brain implant patients with various /sup 192/Ir loads. The bedside shield reduces exposure from /sup 192/Ir implants by a factor of about 20, as expected, and the exposure from the lower energy radioisotope iodine-125 is barely detectable.

  15. Mechanism of hydrogenolysis of an iridium-methyl bond: evidence for a methane complex intermediate.

    Science.gov (United States)

    Campos, Jesús; Kundu, Sabuj; Pahls, Dale R; Brookhart, Maurice; Carmona, Ernesto; Cundari, Thomas R

    2013-01-30

    Evidence for key σ-complex intermediates in the hydrogenolysis of the iridium-methyl bond of (PONOP)Ir(H)(Me)(+) (1) [PONOP = 2,6-bis(di-tert-butylphosphinito)pyridine] has been obtained. The initially formed η(2)-H(2) complex, 2, was directly observed upon treatment of 1 with H(2), and evidence for reversible formation of a σ-methane complex, 5, was obtained through deuterium scrambling from η(2)-D(2) in 2-d(2) into the methyl group of 2 prior to methane loss. This sequence of reactions was modeled by density functional theory calculations. The transition state for formation of 5 from 2 showed significant shortening of the Ir-H bond for the hydrogen being transferred; no true Ir(V) trihydride intermediate could be located. Barriers to methane loss from 2 were compared to those of 1 and the six-coordinate species (PONOP)Ir(H)(Me)(CO)(+) and (PONOP)Ir(H)(Me)(Cl).

  16. Closed-shell and open-shell square-planar iridium nitrido complexes

    Science.gov (United States)

    Scheibel, Markus G.; Askevold, Bjorn; Heinemann, Frank W.; Reijerse, Edward J.; de Bruin, Bas; Schneider, Sven

    2012-07-01

    Coupling reactions of nitrogen atoms represent elementary steps to many important heterogeneously catalysed reactions, such as the Haber-Bosch process or the selective catalytic reduction of NOx to give N2. For molecular nitrido (and related oxo) complexes, it is well established that the intrinsic reactivity, for example nucleophilicity or electrophilicity of the nitrido (or oxo) ligand, can be attributed to M-N (M-O) ground-state bonding. In recent years, nitrogen (oxygen)-centred radical reactivity was ascribed to the possible redox non-innocence of nitrido (oxo) ligands. However, unequivocal spectroscopic characterization of such transient nitridyl {M=N•} (or oxyl {M-O•}) complexes remained elusive. Here we describe the synthesis and characterization of the novel, closed-shell and open-shell square-planar iridium nitrido complexes [IrN(Lt-Bu)]+ and [IrN(Lt-Bu)] (Lt-Bu=N(CHCHP-t-Bu2)2). Spectroscopic characterization and quantum chemical calculations for [IrN(Lt-Bu)] indicate a considerable nitridyl, {Ir=N•}, radical character. The clean formation of IrI-N2 complexes via binuclear coupling is rationalized in terms of nitrido redox non-innocence in [IrN(Lt-Bu)].

  17. An iridium oxide microelectrode for monitoring acute local pH changes of endothelial cells.

    Science.gov (United States)

    Ng, Shu Rui; O'Hare, Danny

    2015-06-21

    pH sensors were fabricated by anodically electrodepositing iridium oxide films (AEIROFs) onto microelectrodes on chips and coated with poly(ethyleneimine) (PEI) for mechanical stability. These demonstrate super-Nernstian response to pH from pH 4.0 to 7.7 in chloride-free phosphate buffer. The surface of the chip was coated with fibronectin for the attachment of porcine aortic endothelial cells (PAECs). The working capability of the pH sensor for monitoring acute local pH changes was investigated by stimulating the PAECs with thrombin. Our results show that thrombin induced acute extracellular acidification of PAECs and dissolution of fibronectin, causing the local pH to decrease. The use of PD98059, a mitogen-activated protein kinase (MAPK) inhibitor, reduced extracellular acidification and an increase in local pH was observed. This study shows that our pH sensors can facilitate the investigation of acute cellular responses to stimulation by monitoring the real-time, local pH changes of cells attached to the sensors.

  18. Theoretical studies of blue-emitting iridium complexes with different ancillary ligands.

    Science.gov (United States)

    Gu, Xin; Fei, Teng; Zhang, Houyu; Xu, Hai; Yang, Bing; Ma, Yuguang; Liu, Xiaodong

    2008-09-11

    The structural and electronic properties of two heteroleptic iridium complexes Ir(dfppy)2(pic) (FIrpic) and Ir(dfppy)2(acac) (FIracac) have been investigated theoretically, where dfppy = 2-(2,4-difluorophenyl) pyridine, pic = picolinic acid, and acac = acetoylacetonate. The geometries of ground and excited states are optimized at PBE0/LANL2DZ and CIS/LANL2DZ levels, respectively. Time-dependent density functional theory (TDDFT) method is employed to explore the absorption and emission properties. In the ground state, the highest-occupied molecular orbital has a significant mixture of metal Ir(d) and dfppy(pi), the lowest-unoccupied orbital locates primarily on pi* of pic for FIrpic and pi* of dfppy for FIracac. The luminescence of each complex originates from the lowest triplet excited state, which is assigned to the mixing of metal-to-ligand charge transfer and intraligand charge transfer characters. The effects of ancillary ligands pic and acac on absorption and emission spectra are observed by analysis of TDDFT results. The connection between the nature of excited states and the behavior of the complexes with different ancillary ligands is elucidated.

  19. BOWIEITE: A NEW RHODIUM-IRIDIUM-PLATINUM SULFIDE IN PLATINUM-ALLOY NUGGETS, GOODNEWS BAY, ALASKA.

    Science.gov (United States)

    Desborough, George A.; Criddle, Alan J.

    1984-01-01

    Bowieite (Rh,Ir,Pt)//2S//3, a new mineral species, is found in three nuggets of platinum from Goodnews Bay, Alaska. In linearly polarized reflected light, and compared to the host, higher reflecting white platinum-iridium alloy, bowieite is pale gray to pale gray-brown; neither bireflectance nor reflectance pleochroism is apparent. With polars crossed, its anisotropic rotation tints vary from gray to dark brown. Luminance values (relative to the CIE illuminant C) for R//1 and R//2, computed from full spectral data for the most bireflectant grain, are 45. 8% and 48. 2% in air, and 30. 5% and 33. 0% in oil, respectively. VHN//1//0//0 1288 (858 to 1635). Bowieite is orthorhombic, space group Pnca, with a 8. 454(7) -8. 473(8), b 5. 995(1)-6. 002(7), c 6. 143(1)-6. 121(8) A, Z equals 4. Some grains that are 2. 6 to 3. 8 atomic % metal-deficient occur as an optically coherent rim on bowieite; the rim and the bowieite grain are not optically continuous.

  20. A cultured human neural network operates a robotic actuator.

    Science.gov (United States)

    Pizzi, R M R; Rossetti, D; Cino, G; Marino, D; A L Vescovi; Baer, W

    2009-02-01

    The development of bio-electronic prostheses, hybrid human-electronics devices and bionic robots has been the aim of many researchers. Although neurophysiologic processes have been widely investigated and bio-electronics has developed rapidly, the dynamics of a biological neuronal network that receive sensory inputs, store and control information is not yet understood. Toward this end, we have taken an interdisciplinary approach to study the learning and response of biological neural networks to complex stimulation patterns. This paper describes the design, execution, and results of several experiments performed in order to investigate the behavior of complex interconnected structures found in biological neural networks. The experimental design consisted of biological human neurons stimulated by parallel signal patterns intended to simulate complex perceptions. The response patterns were analyzed with an innovative artificial neural network (ANN), called ITSOM (Inductive Tracing Self Organizing Map). This system allowed us to decode the complex neural responses from a mixture of different stimulations and learned memory patterns inherent in the cell colonies. In the experiment described in this work, neurons derived from human neural stem cells were connected to a robotic actuator through the ANN analyzer to demonstrate our ability to produce useful control from simulated perceptions stimulating the cells. Preliminary results showed that in vitro human neuron colonies can learn to reply selectively to different stimulation patterns and that response signals can effectively be decoded to operate a minirobot. Lastly the fascinating performance of the hybrid system is evaluated quantitatively and potential future work is discussed.

  1. Screening of patients for first time prostheses after amputation of lower limbs

    Directory of Open Access Journals (Sweden)

    Vetra A.

    2016-01-01

    More than 25% of those who followed the recommended treatment and rehabilitation programme to prepare the amputation stump, reduced contracture and enhanced physical working abilities were declared to be appropriate for further prostheses. This indicates serious shortcomings in medical treatments during the early post-amputation period.

  2. Observations on dental prostheses and restorations subjected to high temperatures: experimental studies to aid identification processes.

    Science.gov (United States)

    Merlati, G; Danesino, P; Savio, C; Fassina, G; Osculati, A; Menghini, P

    2002-12-01

    In large scale disasters associated with fire the damage caused by heat can make medico-legal identification of human remains difficult. Teeth, restorations and prostheses, all of which are resistant to even quite high temperatures can be used as aids in the identification process. In this project the behaviour and morphology of teeth and dental prostheses exposed to a range of high temperatures was studied. Healthy teeth, dental restorations and prostheses were placed in a furnace and heated at a rate of 30 degrees C/min and the effects of the predetermined temperatures 200, 400, 600, 800, 1000 and 1100 degrees C were examined by stereomicroscopy and scanning electron microscopy (SEM). Our observations show that some prostheses and restorative materials resist higher temperatures than theoretically predictable and that even when a restoration is lost because of detachment or change of state its ante-mortem presence can be confirmed and detected by both stereomicroscopic examination and SEM of the residual cavity. We further conclude that a reasonably reliable estimation of the temperature of exposure can be made from an analysis of the teeth and restorative materials.

  3. Intra- and extraoral prostheses retained by zygoma implants following resection of the upper lip and nose.

    Science.gov (United States)

    Gonçalves, Letícia Machado; Gonçalves, Thais Marques Simek Vega; Rodrigues, Antônio Henrique Corrêa; Lanza, Marcos Dias; do Nascimento, Paulo Roberto Gomes; Girundi, Francisco Mauro da Silva

    2015-02-01

    Upper lip cancers are infrequent lesions, being aggressive unless diagnosed and treated early. After the surgical resection, maxillofacial defects require special care in rehabilitation. This article describes the maxillofacial rehabilitation of an edentulous patient diagnosed with upper lip squamous cell carcinoma. The treatment consisted of a large amount of upper lip and nose tissue resection, followed by chemoradiotherapy. After the first surgical healing, zygoma implants were inserted in a two-step procedure. The maxillary and nasal prostheses were installed and fixed by a titanium framework. After 6 years follow-up, no recurrences were observed, and the patient did not develop metastases. Tissues around implants were in good health, and the prostheses remained well-fitted. The use of implant-retained prostheses improved the quality of life, and the patient was extremely satisfied with the final result. The implant-retained prostheses are well accepted by the patient, improving comfort and safety during function while recovering her esthetic apperance. © 2014 by the American College of Prosthodontists.

  4. Stemmed femoral knee prostheses: effects of prosthetic design and fixation on bone loss.

    NARCIS (Netherlands)

    Lenthe, G.H. van; Willems, P.C.P.H.; Verdonschot, N.J.J.; Waal Malefijt, M.C. de; Huiskes, R.

    2002-01-01

    Although the revision rates for modern knee prostheses have decreased drastically, the total number of revisions a year is increasing because many more primary knee replacements are being done. At the time of revision, bone loss is common, which compromises prosthetic stability. To improve

  5. [Image processing system of visual prostheses based on digital signal processor DM642].

    Science.gov (United States)

    Xie, Chengcheng; Lu, Yanyu; Gu, Yun; Wang, Jing; Chai, Xinyu

    2011-09-01

    This paper employed a DSP platform to create the real-time and portable image processing system, and introduced a series of commonly used algorithms for visual prostheses. The results of performance evaluation revealed that this platform could afford image processing algorithms to be executed in real time.

  6. [Technical aspects of treatments with single- and multi-unit fixed dental prostheses

    NARCIS (Netherlands)

    Wiersema, E.J.; Kreulen, C.M.; Latzke, P.; Witter, D.J.; Creugers, N.H.J.

    2014-01-01

    For the manufacture of single- and multi-unit fixed dental prostheses, effective communication between dentist and dental technician is required. Mutual insight concerning the (im)possibilities of available treatments and technical options is prerequisitefor this communication. The manufacture of

  7. [Loading and strength of single- and multi-unit fixed dental prostheses 2. Strength

    NARCIS (Netherlands)

    Baat, C. de; Witter, D.J.; Meijers, C.C.A.J.; Vergoossen, E.L.; Creugers, N.H.J.

    2014-01-01

    The ultimate strength of a dental prosthesis is defined as the strongest loading force applied to the prosthesis until afracture failure occurs. Important key terms are strength, hardness, toughness and fatigue. Relatively prevalent complications of single- and multi-unit fixed dental prostheses are

  8. [Loading and strength of single- and multi-unit fixed dental prostheses. 1. Retention and resistance

    NARCIS (Netherlands)

    Baat, C. de; Witter, D.J.; Meijers, C.C.A.J.; Vergoossen, E.L.; Creugers, N.H.J.

    2014-01-01

    The degree to which single- and multi-unit fixed dental prostheses are able to withstand loading forces is dependent, among other things, on the quality of their retention and resistance. The quality of the retention and resistance of the configuration of an abutment tooth prepared for a metal and

  9. [Aftercare for durability and profitability of single-unit and multi-unit fixed dental prostheses

    NARCIS (Netherlands)

    Baat, C. de; Loveren, C. van; Maarel-Wierink, C.D. van der; Witter, D.J.; Creugers, N.H.J.

    2013-01-01

    An important aim ofa treatment with single-unit and multi-unit fixed dental prostheses is a durable and profitable treatment outcome. That requires aftercare, too. First, the frequency of routine oral examinations should be assessed, using an individual risk profile. The objectives of the routine

  10. Clinical Fit of Partial Removable Dental Prostheses Based on Alginate or Polyvinyl Siloxane Impressions.

    NARCIS (Netherlands)

    Fokkinga, W.A.; Witter, D.J.; Bronkhorst, E.M.; Creugers, N.H.J.

    2017-01-01

    PURPOSE: The aim of this study was to analyze the clinical fit of metal-frame partial removable dental prostheses (PRDPs) based on custom trays used with alginate or polyvinyl siloxane impression material. MATERIALS AND METHODS: Fifth-year students of the Nijmegen Dental School made 25 correct

  11. Minimum jerk swing control allows variable cadence in powered transfemoral prostheses.

    Science.gov (United States)

    Lenzi, T; Hargrove, L J; Sensinger, J W

    2014-01-01

    We present a novel swing phase controller for powered transfemoral prostheses based on minimum jerk theory. The proposed controller allows physiologically appropriate swing movement at any walking speed, regardless of the stance controller action. Preliminary validation in a transfemoral amputee subject demonstrates that the proposed controller provides physiological swing timing, without speed-or patient-specific tuning.

  12. Implant retention and support for distal extension partial removable dental prostheses: satisfaction outcomes.

    Science.gov (United States)

    Gonçalves, Thais Marques Simek Vega; Campos, Camila Heitor; Garcia, Renata Cunha Matheus Rodrigues

    2014-08-01

    The rotational movements of the distal extension denture base of partial removable dental prostheses frequently harm the prosthesis stability, leading to discomfort during function. This study evaluated the use of distal implants to retain and support partial removable dental prostheses and assessed the outcomes with respect to specific aspects of patient satisfaction. Twelve participants (mean age, 62.6 ± 7.8 years) received new conventional mandibular partial removable dental prostheses and complete maxillary dentures. After 2 months of conventional prosthesis use, the participants completed a questionnaire assessing their satisfaction. Implants were then inserted bilaterally in the mandibular posterior region and, after 4 months, ball attachments were placed on the implants and on the partial removable dental prosthesis acrylic resin base. The implants and remaining teeth were followed up with clinical and image examinations. After 2 months, satisfaction was reevaluated, and the data were analyzed by the paired Student t test and the Bonferroni correction (α=.05). Clinical evaluation found stable periodontal conditions around the implants, no intrusions or mobility of teeth, and no radiographic changes in bone level. Participants reported significant improvements (Premovable prostheses improve retention and stability, minimize rotational movements, and significantly increase participant satisfaction. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  13. Neural Tube Defects

    Science.gov (United States)

    ... vitamin, before and during pregnancy prevents most neural tube defects. Neural tube defects are usually diagnosed before the infant is ... or imaging tests. There is no cure for neural tube defects. The nerve damage and loss of function ...

  14. Mixed N-Heterocyclic Carbene-Bis(oxazolinyl)borato Rhodium and Iridium Complexes in Photochemical and Thermal Oxidative Addition Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Songchen [Ames Laboratory; Manna, Kuntal [Ames Laboratory; Ellern, Arkady [Ames Laboratory; Sadow, Aaron D [Ames Laboratory

    2014-12-08

    In order to facilitate oxidative addition chemistry of fac-coordinated rhodium(I) and iridium(I) compounds, carbene–bis(oxazolinyl)phenylborate proligands have been synthesized and reacted with organometallic precursors. Two proligands, PhB(OxMe2)2(ImtBuH) (H[1]; OxMe2 = 4,4-dimethyl-2-oxazoline; ImtBuH = 1-tert-butylimidazole) and PhB(OxMe2)2(ImMesH) (H[2]; ImMesH = 1-mesitylimidazole), are deprotonated with potassium benzyl to generate K[1] and K[2], and these potassium compounds serve as reagents for the synthesis of a series of rhodium and iridium complexes. Cyclooctadiene and dicarbonyl compounds {PhB(OxMe2)2ImtBu}Rh(η4-C8H12) (3), {PhB(OxMe2)2ImMes}Rh(η4-C8H12) (4), {PhB(OxMe2)2ImMes}Rh(CO)2 (5), {PhB(OxMe2)2ImMes}Ir(η4-C8H12) (6), and {PhB(OxMe2)2ImMes}Ir(CO)2 (7) are synthesized along with ToMM(η4-C8H12) (M = Rh (8); M = Ir (9); ToM = tris(4,4-dimethyl-2-oxazolinyl)phenylborate). The spectroscopic and structural properties and reactivity of this series of compounds show electronic and steric effects of substituents on the imidazole (tert-butyl vs mesityl), effects of replacing an oxazoline in ToM with a carbene donor, and the influence of the donor ligand (CO vs C8H12). The reactions of K[2] and [M(μ-Cl)(η2-C8H14)2]2 (M = Rh, Ir) provide {κ4-PhB(OxMe2)2ImMes'CH2}Rh(μ-H)(μ-Cl)Rh(η2-C8H14)2 (10) and {PhB(OxMe2)2ImMes}IrH(η3-C8H13) (11). In the former compound, a spontaneous oxidative addition of a mesityl ortho-methyl to give a mixed-valent dirhodium species is observed, while the iridium compound forms a monometallic allyl hydride. Photochemical reactions of dicarbonyl compounds 5 and 7 result in C–H bond oxidative addition providing the compounds {κ4-PhB(OxMe2)2ImMes'CH2}RhH(CO) (12) and {PhB(OxMe2)2ImMes}IrH(Ph)CO (13). In 12, oxidative addition results in cyclometalation of the mesityl ortho-methyl similar to 10, whereas the iridium compound reacts with the benzene solvent to give a rare crystallographically characterized cis

  15. A Label-Free Luminescent Switch-On Assay for ATP Using a G-Quadruplex-Selective Iridium(III) Complex

    OpenAIRE

    Ka-Ho Leung; Lihua Lu; Modi Wang; Tsun-Yin Mak; Daniel Shiu-Hin Chan; Fung-Kit Tang; Chung-Hang Leung; Hiu-Yee Kwan; Zhiling Yu; Dik-Lung Ma

    2013-01-01

    We report herein the G-quadruplex-selective property of a luminescent cyclometallated iridium(III) complex for the detection of adenosine-5'-triphosphate (ATP) in aqueous solution. The ATP-binding aptamer was employed as the ATP recognition unit, while the iridium(III) complex was used to monitor the formation of the G-quadruplex structure induced by ATP. The sensitivity and fold enhancement of the assay were higher than those of the previously reported assay using the organic dye crystal vio...

  16. Hydrogen Production from a Methanol-Water Solution Catalyzed by an Anionic Iridium Complex Bearing a Functional Bipyridonate Ligand under Weakly Basic Conditions.

    Science.gov (United States)

    Fujita, Ken-ichi; Kawahara, Ryoko; Aikawa, Takuya; Yamaguchi, Ryohei

    2015-07-27

    An efficient catalytic system for the production of hydrogen from a methanol-water solution has been developed using a new anionic iridium complex bearing a functional bipyridonate ligand as a catalyst. This system can be operated under mild conditions [weakly basic solution (0.046 mol L(-1) NaOH) below 100 °C] without the use of an additional organic solvent. Long-term continuous hydrogen production from a methanol-water solution catalyzed by the anionic iridium complex was also achieved. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Mechanochemical Iridium(III)-Catalyzed C-H Bond Amidation of Benzamides with Sulfonyl Azides under Solvent-Free Conditions in a Ball Mill.

    Science.gov (United States)

    Hermann, Gary N; Becker, Peter; Bolm, Carsten

    2016-03-07

    Mechanochemical conditions have been applied to an iridium(III)-catalyzed C-H bond amidation process for the first time. In the absence of solvent, the mechanochemical activation enables the formation of an iridium species that catalyzes the ortho-selective amidation of benzamides with sulfonyl azides as the nitrogen source. As the reaction proceeds in the absence of organic solvents without external heating and yields the desired products in excellent yields within short reaction times, this method constitutes a powerful, fast, and environmentally benign alternative to the common solvent-based standard approaches. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Enhanced anti-Diastereo- and Enantioselectivity in Alcohol Mediated Carbonyl Crotylation Using an Isolable Single Component Iridium Catalyst

    Science.gov (United States)

    Gao, Xin; Townsend, Ian A.; Krische, Michael J.

    2011-01-01

    The cyclometallated iridium complex (S)-I derived from [Ir(cod)Cl]2, 4-cyano-3-nitrobenzoic acid, allyl acetate and (S)-SEGPHOS is conveniently isolated by precipitation or through conventional silica gel flash chromatography. This single component precatalyst allows alcohol mediated carbonyl crotylations to be performed at significantly lower temperature, resulting in enhanced levels of anti-diastereo- and enantioselectivity. Most significantly, the chromatographically isolated precatalyst (S)-I enables carbonyl crotylations that are not possible under previously reported conditions involving in situ generation of (S)-I. PMID:21375283

  19. User-friendly aerobic reductive alkylation of iridium(III) porphyrin chloride with potassium hydroxide: scope and mechanism.

    Science.gov (United States)

    Zuo, Huiping; Liu, Zhipeng; Yang, Wu; Zhou, Zhikuan; Chan, Kin Shing

    2015-12-21

    Alkylation of iridium 5,10,15,20-tetrakistolylporphyrinato carbonyl chloride, Ir(ttp)Cl(CO) (1), with 1°, 2° alkyl halides was achieved to give (ttp)Ir-alkyls in good yields under air and water compatible conditions by utilizing KOH as the cheap reducing agent. The reaction rate followed the order: RCl R = alkyl), and suggests an SN2 pathway by [Ir(I)(ttp)](-). Ir(ttp)-adamantyl was obtained under N2 when 1-bromoadamantane was utilized, which could only undergo bromine atom transfer pathway. Mechanistic investigations reveal a substrate dependent pathway of SN2 or halogen atom transfer.

  20. Visual cortex responses to single- and simultaneous multiple-electrode stimulation of the retina: implications for retinal prostheses.

    Science.gov (United States)

    Shivdasani, Mohit N; Fallon, James B; Luu, Chi D; Cicione, Rosemary; Allen, Penny J; Morley, John W; Williams, Chris E

    2012-09-19

    The aim of this study was to compare simultaneous stimulation of multiple electrodes to single-electrode stimulation in a retinal prosthesis. A platinum electrode array was implanted into the suprachoroidal space in six normally sighted anesthetized cats. Multiunit activity from the primary visual cortex in response to retinal stimulation was recorded. Cortical thresholds, yield of responses, dynamic ranges, and the spread of retinal activation were measured for three modes of stimulation: single electrode, half-row (six-electrode horizontal line), and column (seven-electrode vertical line). Stimulation of the best half-rows and columns was found to elicit activity with higher yield and lower charge thresholds per electrode compared to the best single electrodes. Dynamic ranges between the three modes were similar. As expected, peak voltages measured for columns and half-rows were lower than those measured for single electrodes. Spread of retinal activation, determined by the increase in threshold with distance in the retina from the best site, was found to be similar between single- and multiple-electrode stimulation but dependent on orientation. The lower thresholds, higher yield, equivalent dynamic ranges, and equivalent spread of retinal activation observed from simultaneous stimulation of multiple electrodes may be due to current and/or neural summation within the retina. Such stimulation techniques could be useful for the presentation of lines and edges of objects using a suprachoroidal retinal stimulator with low voltage compliance. Furthermore, the results suggest that more complex visual processing strategies in addition to sequential stimulation of individual electrodes should be considered for retinal prostheses.

  1. Virus-templated iridium oxide-gold hybrid nanowires for electrochromic application

    Science.gov (United States)

    Nam, Yoon Sung; Park, Heechul; Magyar, Andrew P.; Yun, Dong Soo; Pollom, Thomas S.; Belcher, Angela M.

    2012-05-01

    A highly porous electrode comprised of biologically templated iridium oxide-gold (IrO2-Au) hybrid nanowires is introduced for electrochromic applications. A filamentous M13 virus is genetically engineered to display IrO2-binding peptides on the viral surface and used as a template for the self-assembly of IrO2 nanoclusters into a nanowire. The open porous morphology of the prepared nanowire film facilitates ion transport. Subsequently, the redox kinetics of the IrO2 nanowires seems to be limited by the electric resistance of the nanowire film. To increase the electron mobility in the nanowires, gold nanoparticles are chemically linked to the virus prior to the IrO2 mineralization, forming a gold nanostring structure along the long axis of the virus. The resulting IrO2-Au hybrid nanowires exhibit a switching time of 35 ms for coloration and 25 ms for bleaching with a transmission change of about 30.5% at 425 nm. These values represent almost an order of magnitude faster switching responses than those of an IrO2 nanowire film having the similar optical contrast. This work shows that genetically engineered viruses can serve as versatile templates to co-assemble multiple functional molecules, enabling control of the electrochemical properties of nanomaterials.A highly porous electrode comprised of biologically templated iridium oxide-gold (IrO2-Au) hybrid nanowires is introduced for electrochromic applications. A filamentous M13 virus is genetically engineered to display IrO2-binding peptides on the viral surface and used as a template for the self-assembly of IrO2 nanoclusters into a nanowire. The open porous morphology of the prepared nanowire film facilitates ion transport. Subsequently, the redox kinetics of the IrO2 nanowires seems to be limited by the electric resistance of the nanowire film. To increase the electron mobility in the nanowires, gold nanoparticles are chemically linked to the virus prior to the IrO2 mineralization, forming a gold nanostring

  2. Substrate arrays of iridium oxide microelectrodes for in vitro neuronal interfacing

    Directory of Open Access Journals (Sweden)

    Shady Gawad

    2009-01-01

    Full Text Available The design of novel bidirectional interfaces for in vivo and in vitro nervous systems is an important step towards future functional neuroprosthetics. Small electrodes, structures and devices are necessary to achieve high-resolution and target-selectivity during stimulation and recording of neuronal networks, while significant charge transfer and large signal-to-noise ratio are required for accurate time resolution. In addition, the physical properties of the interface should remain stable across time, especially when chronic in vivo applications or in vitro long-term studies are considered, unless a procedure to actively compensate for degradation is provided. In this short report, we describe the use and fabrication of arrays of 120 planar microelectrodes (MEAs of sputtered Iridium Oxide (IrOx. The effective surface area of individual microelectrodes is significantly increased using electrochemical activation, a procedure that may also be employed to restore the properties of the electrodes as required. The electrode activation results in a very low interface impedance, especially in the lower frequency domain, which was characterized by impedance spectroscopy. The increase in the roughness of the microelectrodes surface was imaged using digital holographic microscopy and electron microscopy. Aging of the activated electrodes was also investigated, comparing storage in saline with storage in air. Demonstration of concept was achieved by recording multiple single-unit spike activity in acute brain slice preparations of rat neocortex. Data suggests that extracellular recording of action potentials can be achieved with planar IrOx MEAs with good signal-to-noise ratios.

  3. Iridium oxide microelectrode arrays for in vitro stimulation of individual rat neurons from dissociated cultures

    Directory of Open Access Journals (Sweden)

    Stefan Eick

    2009-11-01

    Full Text Available We present the first in-vitro extracellular stimulation of individual neurons from dissociated cultures with iridium oxide (IrOx electrodes. Microelectrode arrays with sputtered IrOx films (SIROF were developed for electrophysiological investigations with electrogenic cells. The microelectrodes were characterized with scanning electron and atomic force microscopy, revealing rough and porous electrodes with enlarged surface areas. As shown by cyclic voltammetry and electrochemical impedance spectroscopy, the large surface area in combination with the good electrochemical properties of SIROF resulted in high charge storage capacity and low electrode impedance. Thus, we could transfer the good properties of IrOx as material for in-vivo stimulation electrodes to MEAs with electrode diameters as small as 10 µm for in-vitro applications. Single rat cortical neurons from dissociated cultures were successfully stimulated to fire action potentials using single or trains of biphasic rectangular voltage-controlled stimulation pulses. The stimulated cell’s membrane potential was simultaneously monitored using whole-cell current-clamp recordings. This experimental configuration allowed direct evaluation of the influence of pulse phase sequence, amplitude, and number on the stimulation success ratio and action potential latency. Negative phase first pulses were more effective for extracellular stimulation and caused reduced latency in comparison to positive phase first pulses. Increasing the pulse amplitude also improved stimulation reliability. However, in order to prevent cell or electrode damage, the pulse amplitude is limited to voltages below the threshold for irreversible electrochemical reactions at the electrode. As an alternative to increasing the amplitude, a higher number of stimulation pulses was also shown to increase stimulation success.

  4. Defective Metal-Organic Frameworks Incorporating Iridium-Based Metalloligands: Sorption and Dye Degradation Properties.

    Science.gov (United States)

    Fan, Kun; Nie, Wei-Xuan; Wang, Lu-Ping; Liao, Chwen-Haw; Bao, Song-Song; Zheng, Li-Min

    2017-05-11

    Artificial control and engineering of metal-organic framework (MOF) crystals with defects can endow them with suitable properties for applications in gas storage, separation, and catalysis. A series of defective iridium-containing MOFs, [Zn4 (μ4 -O)(Ir-A)2(1-x) (Ir-B)2x ] (ZnIr-MOF-dx ), were synthesized by doping heterostructured linker Ir-BH3 into the parent [Zn4 (μ4 -O)(Ir-A)2 ] (ZnIr-MOF), in which Ir-AH3 represents [Ir(ppy-COOH)3 ] (ppyCOOH=3-(pyridin-2-yl)benzoic acid) and Ir-BH3 is [Ir(ppy-COOH)2 (2-pyPO3 H)] (2-pyPO3 H2 =2-pyridylphosphonic acid). Samples with different degrees of defects were characterized by SEM, IR and NMR spectroscopy, powder XRD measurements, and thermal and elemental analyses. ZnIr-MOF-d0.3 was selected as a representative for gas (N2 , CO2 ) or vapor (H2 O, alcohol) sorption studies. The results demonstrate that defective ZnIr-MOF-d0.3 possesses multiple pore size distributions, ranging from micro- to mesopores, unlike the parent material, which shows a uniform micropore distribution. The hydrophilicity of the interior surface is also increased after defect engineering. As a result, ZnIr-MOF-d0.3 shows an enhanced adsorption capability toward n-butanol, relative to that of the parent compound. Optical studies reveal that both ZnIr-MOF and ZnIr-MOF-d0.3 have low band gaps (2.35 and 2.40 eV), corresponding to semiconductors. ZnIr-MOF-d0.3 exhibits dramatically increased photocatalytic efficiency for dye degradation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. [Neural repair].

    Science.gov (United States)

    Kitada, Masaaki; Dezawa, Mari

    2008-05-01

    Recent progress of stem cell biology gives us the hope for neural repair. We have established methods to specifically induce functional Schwann cells and neurons from bone marrow stromal cells (MSCs). The effectiveness of these induced cells was evaluated by grafting them either into peripheral nerve injury, spinal cord injury, or Parkinson' s disease animal models. MSCs-derived Schwann cells supported axonal regeneration and re-constructed myelin to facilitate the functional recovery in peripheral and spinal cord injury. MSCs-derived dopaminergic neurons integrated into host striatum and contributed to behavioral repair. In this review, we introduce the differentiation potential of MSCs and finally discuss about their benefits and drawbacks of these induction systems for cell-based therapy in neuro-traumatic and neuro-degenerative diseases.

  6. The Use of Prostheses in Pelvic Reconstructive Surgery: Joy or Toy?

    Directory of Open Access Journals (Sweden)

    Ming-Ping Wu

    2008-06-01

    Full Text Available The high recurrence rate of pelvic organ prolapse (POP of up to 30% after pelvic reconstructive surgery makes a more refined surgery imperative, as well as the need for either biological or synthetic prostheses as adjuvant treatment. Patients with recurrence risks may benefit from the adjuvant treatment: (1 to substitute for the lack of supportive tissue; (2 to reinforce inadequate tissue; (3 to induce new supportive tissue; and (4 to consolidate and complement the insufficient surgical techniques. However, some debatable issues in use of the prosthetics remain. The use of prosthetics enables the simultaneous repair of all vaginal defects of POP and concomitant anti-incontinence surgery to be faster, easier and more precise. Nevertheless, great care should be devoted to the actual and theoretical short- and long-term risks, many of which have not been fully elucidated. Despite the lack of various ideal characteristics, the type I monofilament, macroporous polypropylene, has been suggested to have the lowest incidence of infection and erosion among the nonabsorbable prostheses. There is good evidence to support the use of nonabsorbable synthetic mesh for abdominal sacrocolpopexy, while the use of prostheses for repairing isolated anterior and posterior compartment defects remains controversial. There have been no long-term studies with sufficient patient numbers to prove whether synthetic or biological prostheses are superior during vaginal surgery. Tension-free vaginal mesh techniques with procedural kits are being adopted increasingly, despite the paucity of data. Although short-term follow-up studies have shown tension-free vaginal mesh to be a safe and effective technique to correct POP, anatomic and functional results of long-term follow-up studies, however, have not yet confirmed the effectiveness and safety. Mesh erosion remains a concern, with variable rates according to different materials and approaches. Newly developed prostheses offer

  7. Safety, Healing, and Efficacy of Vascular Prostheses Coated with Hydroxypropyl-[beta]-cyclodextrin Polymer: Experimental In Vitro and Animal Studies

    National Research Council Canada - National Science Library

    Jean-Baptiste, E; Blanchemain, N; Martel, B; Neut, C; Hildebrand, H.F; Haulon, S

    2012-01-01

    Polyester vascular prostheses (PVPs) coated with a polymer of hydroxypropyl-[beta]-cyclodextrin (HP[beta]CD) have been designed to provide an in situ reservoir for the sustained delivery of one or more bioactive molecules...

  8. Safety, healing, and efficacy of vascular prostheses coated with hydroxypropyl-β-cyclodextrin polymer: experimental in vitro and animal studies

    National Research Council Canada - National Science Library

    Jean-Baptiste, E; Blanchemain, N; Martel, B; Neut, C; Hildebrand, H F; Haulon, S

    2012-01-01

    Polyester vascular prostheses (PVPs) coated with a polymer of hydroxypropyl-β-cyclodextrin (HPβCD) have been designed to provide an in situ reservoir for the sustained delivery of one or more bioactive molecules...

  9. Proposing national identification number on dental prostheses as universal personal identification code - A revolution in forensic odontology

    National Research Council Canada - National Science Library

    Baad, Rajendra K; Belgaumi, Uzma; Vibhute, Nupura; Kadashetti, Vidya; Chandrappa, Pramod Redder; Gugwad, Sushma

    2015-01-01

    .... We propose that national identification numbers be incorporated in all removable and fixed prostheses, so as to adopt a single and definitive universal personal identification code with the aim...

  10. Preliminary observations on influence of dairy products on biofilm removal from silicone rubber voice prostheses in vitro

    NARCIS (Netherlands)

    Busscher, HJ; Free, RH; Van Weissenbruch, R; Albers, FWJ; Van der Mei, HC

    We determined oropharyngeal biofilm removal from silicone rubber voice prostheses in an artificial throat after perfusion with different commercially available dairy products, including buttermilk, Lactobacillus casei Shirota fermented milk (Yakult, Yakult Netherlands BV, Almere, The Netherlands),

  11. Evaluation of various methods to quantify endothelial cells attached to vascular prostheses: Comparison with a new "gold standard" FACS method

    NARCIS (Netherlands)

    Visser, M.J.T.; Lennep, A.C.D. van; Bockel, J.H. van; Hinsbergh, V.W.M. van; Keur, M. van der; Hermans, J.

    1996-01-01

    For in vitro evaluation of functional properties of endothelial cells seeded on synthetic vascular prostheses accurate and reproducible quantification of cells is mandatory. Comparison of these properties with those resulting from other studies requires correlation of the functional parameters to

  12. The effect of buttermilk consumption on biofilm formation on silicone rubber voice prostheses in an artificial throat

    NARCIS (Netherlands)

    Busscher, HJ; Bruinsma, G; van Meissenbruch, R; Leunisse, C; van der Mei, HC; Dijk, F; Albers, FVJ

    Biofilm formation on indwelling silicone rubber voice prostheses in laryngectomized patients is still the main reason for dysfunction of the valve, leading to frequent replacements. Within patient support groups in The Netherlands, laryngectomees have suggested that the consumption of buttermilk

  13. Poly(3,4-ethylene dioxythiophene (PEDOT as a micro-neural interface material for electrostimulation

    Directory of Open Access Journals (Sweden)

    Seth J Wilks

    2009-06-01

    Full Text Available Chronic microstimulation-based devices are being investigated to treat conditions such as blindness, deafness, pain, paralysis and epilepsy. Small area electrodes are desired to achieve high selectivity. However, a major trade-off with electrode miniaturization is an increase in impedance and charge density requirements. Thus, the development of novel materials with lower interfacial impedance and enhanced charge storage capacity is essential for the development of micro-neural interface-based neuroprostheses. In this report, we study the use of conducting polymer poly(3,4-ethylene dioxythiophene (PEDOT as a neural interface material for microstimulation of small area iridium electrodes on silicon-substrate arrays. Characterized by electrochemical impedance spectroscopy, electrodeposition of PEDOT results in lower interfacial impedance at physiologically-relevant frequencies, with the 1kHz impedance magnitude being 23.3 ± 0.7 kΩ compared to 113.6 ± 3.5 kΩ for iridium oxide (IrOx on 177μm2 sites. Further, PEDOT exhibits enhanced charge storage capacity at 75.6 ± 5.4 mC/cm2 compared to 28.8 ± 0.3 mC/cm2 for IrOx, characterized by cyclic voltammetry (50 mV/s. These improvements at the electrode interface were corroborated by observation of the voltage excursions that result from constant current pulsing. The PEDOT coatings provide both a lower amplitude voltage and a more ohmic representation of the applied current compared to IrOx. During repetitive pulsing, PEDOT-coated electrodes show stable performance and little change in electrical properties, even at relatively high current densities which cause IrOx instability. These findings support the potential of PEDOT coatings as a micro-neural interface material for electrostimulation.

  14. Replacement of missing lateral incisors with lithium disilicate glass-ceramic veneer-fixed dental prostheses: a clinical report

    Science.gov (United States)

    Bissasu, Sami M; Al-houri, Nabil A

    2014-01-01

    Key Clinical Message This report describes the use of lithium disilicate glass-ceramic veneer-fixed dental prostheses in replacing congenitally missing maxillary lateral incisors. This kind of prosthesis has an advantage over a lingual-retainer resin-bonded fixed dental prosthesis in its capability of changing the color and shape of the abutment teeth. The prostheses provided an acceptable esthetics and comfort for the patient. PMID:25356269

  15. Replacement of missing lateral incisors with lithium disilicate glass-ceramic veneer-fixed dental prostheses: a clinical report

    OpenAIRE

    Bissasu, Sami M; Al-houri, Nabil A

    2014-01-01

    Key Clinical Message This report describes the use of lithium disilicate glass-ceramic veneer-fixed dental prostheses in replacing congenitally missing maxillary lateral incisors. This kind of prosthesis has an advantage over a lingual-retainer resin-bonded fixed dental prosthesis in its capability of changing the color and shape of the abutment teeth. The prostheses provided an acceptable esthetics and comfort for the patient.

  16. A Phosphorescent Iridium(III) Complex-Modified Nanoprobe for Hypoxia Bioimaging Via Time-Resolved Luminescence Microscopy.

    Science.gov (United States)

    Lv, Wen; Yang, Tianshe; Yu, Qi; Zhao, Qiang; Zhang, Kenneth Yin; Liang, Hua; Liu, Shujuan; Li, Fuyou; Huang, Wei

    2015-10-01

    Oxygen plays a crucial role in many biological processes. Accurate monitoring of oxygen level is important for diagnosis and treatment of diseases. Autofluorescence is an unavoidable interference in luminescent bioimaging, so that an amount of research work has been devoted to reducing background autofluorescence. Herein, a phosphorescent iridium(III) complex-modified nanoprobe is developed, which can monitor oxygen concentration and also reduce autofluorescence under both downconversion and upconversion channels. The nanoprobe is designed based on the mesoporous silica coated lanthanide-doped upconversion nanoparticles, which contains oxygen-sensitive iridium(III) complex in the outer silica shell. To image intracellular hypoxia without the interferences of autofluorescence, time-resolved luminescent imaging technology and near-infrared light excitation, both of which can reduce autofluorescence effectively, are adopted in this work. Moreover, gradient O2 concentration can be detected clearly through confocal microscopy luminescence intensity imaging, phosphorescence lifetime imaging microscopy, and time-gated imaging, which is meaningful to oxygen sensing in tissues with nonuniform oxygen distribution.

  17. Treatment of malignant biliary obstruction by endoscopic implantation of iridium 192 using a new double lumen endoprosthesis

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, J.H.; Lichtenstein, J.L.; Pullano, W.E.; Ramsey, W.H.; Rosenbaum, A.; Halpern, G.; Nonkin, R.; Jacob, H.

    1988-07-01

    Iridium 192 seeds contained in a ribbon were preloaded into a new double lumen 11 Fr endoprosthesis which was then inserted into malignant strictures of the bile duct and ampulla and left in place for 48 hours until 5000 rads were delivered to the tumor. The procedure was carried out in 14 patients (7 women, 7 men; mean age, 63.2 years; range, 46 to 86 years). Six patients were treated for cholangiocarcinomas, four with pancreatic carcinomas, and four with ampullary carcinomas. No complications occurred. The mean survival of the group was 7 months (range, 3 days to 27 months). This new technique provides both intraluminal brachytherapy and biliary drainage and is inserted intraduodenally across the papilla of Vater avoiding puncture of the liver and external hardware required by the percutaneous technique and hardware necessitated with a nasobiliary tube. Following removal of the iridium prosthesis, a large caliber endoprosthesis is inserted for continued decompression. Because of proven efficacy of endoprostheses, this new technique should be considered when intraluminal irradiation is indicated.

  18. Interstitial radiation therapy for carcinoma of the penis using iridium 192 wires: the Henri Mondor experience (1970-1979)

    Energy Technology Data Exchange (ETDEWEB)

    Mazeron, J.J.; Langlois, D.; Lobo, P.A.; Huart, J.A.; Calitchi, E.; Lusinchi, A.; Raynal, M.; Le Bourgeois, J.P.; Abbou, C.C.; Pierquin, B.

    1984-10-01

    From 1970 to 1979, a group of 50 patients was treated for squamous cell carcinoma of the penis by interstitial irradiation using an afterloading technique and iridium 192 wires. The group included 9 patients with T1 tumors, 27 with T2 tumors, and 14 with T3 tumors. Forty-five patients presented with no metastatic inguinal nodes (NO), 3 patients with N1 nodes, and 2 patients had N3 nodes. After treatment, 11 patients (1 T1, 6 T2 and 4 T3) developed local recurrences. Three patients developed post-therapeutic necrosis which necessitated partial amputation in 2 cases. Eight patients developed post-therapeutic urethral stenosis, which required surgical treatment in three of the cases. Twenty-one percent of the patients died of their disease. The authors advocate interstitial irradiation using iridium 192 wires for the treatment of non-infiltrating or moderately infiltrating squamous cell carcinoma of the penis in which the largest dimension does no exceed 4 cm. When regular follow-up can be assurred, it is reasonable to forgo prophylactic treatment of the inguinal nodes in patients presenting without groin metastasis.

  19. New 'aggregation induced emission (AIE)' active cyclometalated iridium(III) based phosphorescent sensors: high sensitivity for mercury(II) ions.

    Science.gov (United States)

    Alam, Parvej; Kaur, Gurpreet; Climent, Clàudia; Pasha, Saleem; Casanova, David; Alemany, Pere; Choudhury, Angshuman Roy; Laskar, Inamur Rahaman

    2014-11-21

    Design and syntheses of 'aggregation induced emission (AIE)' active blue-emitting bis-cyclometalated iridium(III) complexes with appended diphosphine ligands [Ir(F2ppy)2(L1/L2)2(Cl)] (F2ppy = 2-(2',4'-difluoro) phenylpyridine; L1 = 1,2-bis(diphenylphosphino)ethane; L2 = bis(diphenylphosphino)propane) have been realized on a suitable route. The free phosphorous donor atom present on the appended diphosphine is shown to provide selective binding to the mercuric ion (Hg(2+)). The selective binding ability of the probe molecule towards mercuric ions results in a detectable signal due to complete quenching of their AIE properties. The quenching effect of the probe molecule has been explored and found to be the result of the degradation of the probe iridium(III) complex triggered by the presence of mercuric ions due to an interplay of a soft-soft interaction between the free phosphorous atom of the probe molecule and mercuric ions. These complexes were modelled to obtain deeper understanding of excited state properties and the results were tentatively correlated with the experimental data.

  20. Dosimetry of wires and single ribbons of Iridium 192; Dosimetria de alambres y ribbons individuales de Iridio-192

    Energy Technology Data Exchange (ETDEWEB)

    Mazzucco, L.D. [Centro Medico Nuclear S.R.L. San Juan (Argentina)

    1998-12-31

    The objective of this work is in order to present in table formats the dosimetry of wires and single ribbons of Iridium with lengths 1-12 cm for each one linear source along the bisector which is perpendicular at tissue sources (water) computed for linear activity 1 mCi/cm in the case of wires, and 1 mCi/seed for ribbons. The above tables are of direct use, adaptable at particular cases so they facilitate logarithmic graphics of doses in function of the distance for interpolation and use in the treatments planning. It was shown that for two sources with identical linear activity and total length, one of the equidistant seeds at 1 cm (ribbon) and one wire on the other hand, the differences in dose rates in near positions can be about the 15% so corroborating that it is not possible to use wire tables for seeds neither vice versa. Moreover it was elaborated tables of practical direct use for dose rate in water at c Gy/hr for wires and Ribbons 1-12 cm length and from 0.5-10 cm of distance in the perpendicular bisector at the Iridium implant. (Author)

  1. pi-Conjugated chelating polymers with charged iridium complexes in the backbones: synthesis, characterization, energy transfer, and electrochemical properties.

    Science.gov (United States)

    Liu, Shu-Juan; Zhao, Qiang; Chen, Run-Feng; Deng, Yun; Fan, Qu-Li; Li, Fu-You; Wang, Lian-Hui; Huang, Chun-Hui; Huang, Wei

    2006-05-24

    A series of pi-conjugated chelating polymers with charged iridium (Ir) complexes in the backbones were synthesized by a Suzuki polycondensation reaction, leading to homogeneous polymeric materials that phosphoresce red light. The fluorene and bipyridine (bpy) segments were used as polymer backbones. 5,5'-Dibromobipyridine served as a ligand to form a charged iridium complex monomer with 1-(9'9-dioctylfluorene-2-yl)isoquinoline (Fiq) as the cyclometalated ligand. Chemical and photophysical characterization confirmed that Ir complexes were incorporated into the backbones as one of the repeat units by means of the 5,5'-dibromobipyridine ligand. Chelating polymers showed almost complete energy transfer from the host fluorene segments to the guest Ir complexes in the solid state when the feed ratio was 2 mol %. In the films of the corresponding blend system, however, energy transfer was not complete even when the content of Ir complexes was as high as 16 mol %. Both intra- and intermolecular energy-transfer processes existed in this host-guest system, and the intramolecular energy transfer was a more efficient process. All chelating polymers displayed good thermal stability, redox reversibility, and film formation. These chelating polymers also showed more efficient energy transfer than the corresponding blended system and the mechanism of incorporation of the charged Ir complexes into the pi-conjugated polymer backbones efficiently avoided the intrinsic problems associated with the blend system, thus offering promise in optoelectronic applications.

  2. Efficient and tunable white-light emission of metal–organic frameworks by iridium-complex encapsulation

    Science.gov (United States)

    Sun, Chun-Yi; Wang, Xin-Long; Zhang, Xiao; Qin, Chao; Li, Peng; Su, Zhong-Min; Zhu, Dong-Xia; Shan, Guo-Gang; Shao, Kui-Zhan; Wu, Han; Li, Jing

    2013-01-01

    Metal–organic frameworks (MOFs) are well known for their tunable structure and porosity. Many studies have shown they are promising for various important applications, for which their performance can be further enhanced by encapsulating functional species, such as luminescent guest molecules, within the frameworks. Although numerous MOFs are luminescent, very few emit white light and their quantum yield is usually low. Here we report a strategy to achieve efficient white-light emission by encapsulating an iridium complex in the MOF cavity. A mesoporous blue-emitting MOF is prepared as host to encapsulate a yellow-emitting iridium complex, [Ir(ppy)2(bpy)]+. The resultant composites emit bright white light with good colour quality (for example, Commission International de I’Eclairage coordinates, colour-rendering index and correlated colour temperature of (0.31, 0.33), 84.5 and 5409 K, respectively), and high quantum yield up to 115 °C. This strategy may open new perspectives for developing high-performance energy-saving solid-state lighting materials. PMID:24212250

  3. Study by PIXE method of trace elements transferred from prostheses to soft tissues and organs

    Energy Technology Data Exchange (ETDEWEB)

    Oudadesse, H. E-mail: hassane.oudadesse@univ-rennes1.froudadess@clermont.in2p3.fr; Guibert, G.; Chassot, E.; Irigaray, J.L.; Terver, S.; Vanneuville, G.; Tessier, Y.; Sauvage, T.; Blondiaux, G

    2002-05-01

    Some metallic prostheses inserted in human hip undergo physico-chemical modification, a few years after their implantation. Tissues surrounding these prostheses are damaged by metallic element transfer. Surgeons in Clermont-Ferrand Hospital (France) recover tissues of abnormal coloration that were in contact with metallic implants. PIXE technique (particles induced X-ray emission) with a 400 {mu}m proton beam and 3 MeV of energy is an efficient technique to analyze these tissues and to detect elements, which are transferred from prosthesis to tissues. PIXE analyses were carried at the CERI-CNRS Laboratory. We have applied this method to determine qualitatively and quantitatively trace elements migration from metallic implants to surrounding tissues and organs, like kidney, spleen, liver, lymphatic gland and lung.

  4. CT imaging features of obturator prostheses in patients following palatectomy or maxillectomy.

    Science.gov (United States)

    Kumar, V A; Hofstede, T M; Ginsberg, L E

    2011-01-01

    Palatal tumors are often treated with palatectomy or maxillectomy. The resulting surgical defect produces an oroantral communication. An obturator is a removable prosthesis used to close the palatal or maxillectomy defect. Fifteen patients who had undergone palatectomy or maxillectomy for carcinoma and subsequent obturator prosthesis placement were retrospectively studied. Obturators were characterized by Hounsfield units and were subdivided into 3 CT imaging groups: either hyperattenuated, hollow (air-containing), or heterogeneous (isoattenuated to hyperattenuated with internal foci of air). Eight patients had hyperattenuated obturators either representing acrylic resin or Trusoft. Four patients had hollow obturators also composed of acrylic resin or Trusoft. Three patients had heterogeneous obturators, which were composed of only Trusoft. The postoperative imaging of patients treated for palatal or maxillary tumors can be complicated by the presence of obturator prostheses. The intent of this article was to familiarize the reader with the CT imaging features of obturator prostheses.

  5. Integrated flexible ocular coil for power and data transfer in retinal prostheses.

    Science.gov (United States)

    Li, W; Rodger, D; Weiland, J; Humayun, M; Tai, Y

    2005-01-01

    A microfabricated and fully-implantable coil for use as a power and data transfer component for retinal prostheses is presented. Compared with traditional hand-made ocular coils, this parylene-based device is thin and flexible with 10 turns of thin-film metal wires and a thickness of less than 10 μm. In addition, the entire coil structure can be heat-formed on a mold to match the eye's curvature for extraocular implantation. Because it is made using parylene thin-film technology, this coil can be directly integrated with multielectrode arrays and with parylene-based packages incorporating application specific integrated circuits (ASICs) or discrete electrical components such as chip capacitors. This coil thus enables the fabrication and implantation of a fully microfabricated system for retinal prostheses.

  6. Cutaneous temperature measurements in men with penile prostheses: a comparison study.

    Science.gov (United States)

    Fogarty, J D; Bleustein, C B; Hafron, J M; Melman, A

    2005-01-01

    To evaluate and compare the cutaneous temperature of the penis in normal men, those with erectile dysfunction (ED), those with semirigid penile prostheses (SRPPs), and those with inflatable penile prostheses (IPPs), and those before and after trimix injection to create a penile erection. A total of 68 patients were evaluated. Five patient groups were identified, including men with normal erectile function, with ED, with SRPPs, with IPPs, and following intracavernosal injection of trimix solution. Cutaneous glans temperature increased significantly by more than 2.2 degrees C in the trimix-injected group compared with all other groups (Ptrimix. Men with normal erectile function, ED, and IPPs did not have significant cutaneous temperature differences.

  7. Full Mouth Rehabilitation with Implant-Supported Prostheses for Severe Periodontitis: A Case Report

    OpenAIRE

    Bencharit, Sompop; Schardt-Sacco, Debra; Border, Michael B.; Barbaro, Colin P

    2010-01-01

    Oral rehabilitation for a patient with severe loss of alveolar bone and soft tissue resulting from severe periodontitis presents a challenge to clinicians. Replacing loosening natural teeth with fixed prostheses supported by dental implants often requires either gingival surgery or bone grafting. The outcome of the bone grafting is sometimes unpredictable and requires longer healing time and/ or multiple surgeries. The presence of periodontal inflammation and periapical lesions often delay th...

  8. A study on reproducing silicone shade guide for maxillofacial prostheses matching Indian skin color

    OpenAIRE

    Guttal Satyabodh; Patil Narendra; Nadiger Ramesh; Kulkarni Reshma

    2008-01-01

    Aim: The value and success of a well-fitting and anatomically correct prosthesis are compromised if the color does not match the adjoining tissues. The use of powder colors to help develop a simplified silicone shade guide to aid in the fabrication of silicone facial prostheses for Indian patients has been described here. Materials and Methods: Ten powder pigments were used to fabricate the silicone samples for three different subjects having light, medium and dark complexions who were sep...

  9. Cemented, cementless, and hybrid prostheses for total hip replacement: cost effectiveness analysis

    OpenAIRE

    Pennington, Mark; Grieve, Richard; Sekhon, Jasjeet S; Gregg, Paul; Black, Nick; van der Meulen, Jan H

    2013-01-01

    OBJECTIVE To compare the cost effectiveness of the three most commonly chosen types of prosthesis for total hip replacement. DESIGN Lifetime cost effectiveness model with parameters estimated from individual patient data obtained from three large national databases. SETTING English National Health Service. PARTICIPANTS Adults aged 55 to 84 undergoing primary total hip replacement for osteoarthritis. INTERVENTIONS Total hip replacement using either cemented, cementless, or hybrid prostheses. M...

  10. On-Demand Intraoperative 3-Dimensional Printing of Custom Cranioplastic Prostheses.

    Science.gov (United States)

    Evins, Alexander I; Dutton, John; Imam, Sayem S; Dadi, Amal O; Xu, Tao; Cheng, Du; Stieg, Philip E; Bernardo, Antonio

    2018-01-13

    Currently, implantation of patient-specific cranial prostheses requires reoperation after a period for design and formulation by a third-party manufacturer. Recently, 3-dimensional (3D) printing via fused deposition modeling has demonstrated increased ease of use, rapid production time, and significantly reduced costs, enabling expanded potential for surgical application. Three-dimensional printing may allow neurosurgeons to remove bone, perform a rapid intraoperative scan of the opening, and 3D print custom cranioplastic prostheses during the remainder of the procedure. To evaluate the feasibility of using a commercially available 3D printer to develop and produce on-demand intraoperative patient-specific cranioplastic prostheses in real time and assess the associated costs, fabrication time, and technical difficulty. Five different craniectomies were each fashioned on 3 cadaveric specimens (6 sides) to sample regions with varying topography, size, thickness, curvature, and complexity. Computed tomography-based cranioplastic implants were designed, formulated, and implanted. Accuracy of development and fabrication, as well as implantation ability and fit, integration with exiting fixation devices, and incorporation of integrated seamless fixation plates were qualitatively evaluated. All cranioprostheses were successfully designed and printed. Average time for design, from importation of scan data to initiation of printing, was 14.6 min and average print time for all cranioprostheses was 108.6 min. On-demand 3D printing of cranial prostheses is a simple, feasible, inexpensive, and rapid solution that may help improve cosmetic outcomes; significantly reduce production time and cost-expanding availability; eliminate the need for reoperation in select cases, reducing morbidity; and has the potential to decrease perioperative complications including infection and resorption.

  11. Effect of beverages and mouthwashes on the hardness of polymers used in intraoral prostheses.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Dos Santos, Daniela Micheline; Andreotti, Agda Marobo; Nobrega, Adhara Smith; Moreno, Amalia; Haddad, Marcela Filié; Pesqueira, Aldiéris Alves

    2014-10-01

    The mechanical properties of acrylic resins used in intraoral prostheses may be altered by frequent exposure to liquids such as beverages and mouthwashes. This study aimed to evaluate the effect of thermocycling and liquid immersion on the hardness of four brands of acrylic resins commonly used in removable prostheses (Onda Cryl, QC-20, Clássico, Lucitone). For each brand of resin, seven specimens were immersed in each of six solutions (coffee, cola, red wine, Plax-Colgate, Listerine [LI], Oral B), and seven more were placed in artificial saliva (control). The hardness was tested using a microhardness tester before and after 5000 thermocycles and after 1, 3, 24, 48, and 96 hours of immersion. The results were analyzed using three-way repeated-measures ANOVA and Tukey's test (p hardness of the resins decreased following thermocycling and immersion in the solutions. Specimens immersed in cola and wine exhibited significant decreases in hardness after immersion for 96 hours, although the greatest significant decrease in hardness occurred in specimens immersed in LI. However, according to American Dental Association specification 12, the Knoop hardness of acrylic resins for intraoral prostheses should not be below 15. Thus, the median values of superficial hardness observed in most of the acrylic resins in this study are considered clinically acceptable. The microhardness of polymers used for intraoral prostheses decreases following thermocycling. Among specimens immersed in beverages, those immersed in cola or wine experienced the greatest decrease in microhardness. Immersion of acrylic resins in LI significantly decreased the microhardness in relation to the initial value. Among the resins assessed, QC-20 exhibited the lowest initial hardness. © 2014 by the American College of Prosthodontists.

  12. Sensory Feedback for Lower Extremity Prostheses Incorporating Targeted Muscle Reinnervation (TMR)

    Science.gov (United States)

    2016-10-01

    AWARD NUMBER: W81XWH-15-1-0417 TITLE: Sensory Feedback for Lower Extremity Prostheses Incorporating Targeted Muscle Reinnervation (TMR...SUPPLEMENTARY NOTES 14. ABSTRACT The purpose of this research is to improve stair descent for lower limb amputees by providing sensory feedback of foot placement...the site of the surgery can feel like they are originating from the amputated limb . This capability is an unprecedented opportunity to provide

  13. Progress in the clinical development and utilization of vision prostheses: an update

    OpenAIRE

    Brandli A; Luu CD; Guymer RH; Ayton LN

    2016-01-01

    Alice Brandli, Chi D Luu, Robyn H Guymer, Lauren N Ayton Centre for Eye Research Australia, Department of Surgery (Ophthalmology), The University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, VIC, Australia Abstract: Vision prostheses, or “bionic eyes”, are implantable medical bionic devices with the potential to restore rudimentary sight to people with profound vision loss or blindness. In the past two decades, this field has rapidly progressed,...

  14. PERSPECTIVE: Is acuity enough? Other considerations in clinical investigations of visual prostheses

    Science.gov (United States)

    Lepri, Bernard P.

    2009-06-01

    Visual impairing eye diseases are the major frontier facing ophthalmic research today in light of our rapidly aging population. The visual skills necessary for improving the quality of daily function and life are inextricably linked to these impairing diseases. Both research and reimbursement programs are emphasizing outcome-based results. Is improvement in visual acuity alone enough to improve the function and quality of life of visually impaired persons? This perspective summarizes the types of effectiveness endpoints for clinical investigations of visual prostheses that go beyond visual acuity. The clinical investigation of visual prostheses should include visual function, functional vision and quality of life measures. Specifically, they encompass contrast sensitivity, orientation and mobility, activities of daily living and quality of life assessments. The perspective focuses on the design of clinical trials for visual prostheses and the methods of determining effectiveness above and beyond visual acuity that will yield outcomes that are measured by improved function in the visual world and quality of life. The visually impaired population is the primary consideration in this presentation with particular emphases on retinitis pigmentosa and age-related macular degeneration. Clinical trials for visual prostheses cannot be isolated from the need for medical rehabilitation in order to obtain measurements of effectiveness that produce outcomes/evidence-based success. This approach will facilitate improvement in daily function and quality of life of patients with diseases that cause chronic vision impairment. The views and opinions are those of the author and do not necessarily reflect those of the US Food and Drug Administration, the US Department of Health and Human Services or the Public Health Service.

  15. Impact of aortic root geometry on hydrody-namic performance of transcatheter aortic valve prostheses

    Directory of Open Access Journals (Sweden)

    Kaule Sebastian

    2017-09-01

    Full Text Available Assessment of hydrodynamic performance of transcatheter aortic valve prostheses (TAVP in vitro is es-sentially in the fields of development and approval of novel implants. For the prediction of clinical performance, in vitro testing of TAVP allows for benchmarking of different devic-es, likewise. In addition to the implant itself, also the testing environment has a crucial influence on leaflet dynamics and quantitative test results like effective orifice area (EOA or aortic regurgitation.

  16. Three-dimensional printed upper-limb prostheses lack randomised controlled trials: A systematic review.

    Science.gov (United States)

    Diment, Laura E; Thompson, Mark S; Bergmann, Jeroen Hm

    2017-06-01

    Three-dimensional printing provides an exciting opportunity to customise upper-limb prostheses. This review summarises the research that assesses the efficacy and effectiveness of three-dimensional printed upper-limb prostheses. Systematic review. PubMed, Web of Science and OVID were systematically searched for studies that reported human trials of three-dimensional printed upper-limb prostheses. The studies matching the language, peer-review and relevance criteria were ranked by level of evidence and critically appraised using the Downs and Black Quality Index. After removing duplicates, 321 records were identified. Eight papers met the inclusion criteria. No studies used controls; five were case studies and three were small case-series studies. All studies showed promising results, but none demonstrated external validity, avoidance of bias or statistically significant improvements over conventional prostheses. The studies demonstrated proof-of-concept rather than assessing efficacy, and the devices were designed to prioritise reduction of manufacturing costs, not customisability for comfort and function. The potential of three-dimensional printing for individual customisation has yet to be fully realised, and the efficacy and effectiveness to be rigorously assessed. Until randomised controlled trials with follow-up are performed, the comfort, functionality, durability and long-term effects on quality of life remain unknown. Clinical relevance Initial studies suggest that three-dimensional printing shows promise for customising low-cost upper-limb prosthetics. However, the efficacy and effectiveness of these devices have yet to be rigorously assessed. Until randomised controlled trials with follow-up are performed, the comfort, functionality, durability and long-term effects on patient quality of life remain unknown.

  17. Fracture Behavior of Minimally Invasive, Posterior, and Fixed Dental Prostheses Manufactured from Monolithic Zirconia.

    Science.gov (United States)

    Bömicke, Wolfgang; Rues, Stefan; Hlavacek, Verena; Rammelsberg, Peter; Schmitter, Marc

    2016-11-12

    To compare ultimate fracture load (Fu ), load at first damage (F1d ), and fracture pattern for posterior fixed dental prostheses (FDPs) manufactured from translucent, yttria-stabilized zirconia polycrystal. Premolar-size FDPs in 4 test groups (n = 16/group) were constructed as veneered complete crown-retained (group 1), monolithic complete crown-retained (group 2), monolithic partial veneer crown-retained (group 3), or monolithic resin-bonded (group 4) prostheses with minimum zirconia wall thickness (0.5 mm). Adhesively cemented to metal abutments, half of the prostheses were artificially aged by use of 10,000 thermocycles (6.5°C/60°C) and 1,200,000 chewing cycles (F = 108 N), before fracture loading. Statistics included two-way non-parametric ANOVA and Dunn-Bonferroni post-hoc tests (α = 0.05). None of the restorations failed during artificial aging. Fu was affected by test group (p dental prostheses (FDP) manufactured from monolithic zirconia, with a retainer wall thickness of 0.5 mm, might be suitable for use as a conservative alternative to their veneered counterparts in the rehabilitation of posterior tooth loss. Monolithic zirconia resin-bonded FDP might, moreover, be a viable alternative to resin-bonded FDPs with metal adhesive retainers in posterior arches, with improved esthetics and biocompatibility. The performance of both should, however, be verified in clinical trials. (J Esthet Restor Dent 28:367-381, 2016). © 2016 Wiley Periodicals, Inc.

  18. Texture analysis the evaluation of human irises reproduction in ocular prostheses and colored contact lenses

    OpenAIRE

    Herrera Ramírez, Jorge Alexis; Vilaseca Ricart, Meritxell; Arjona Carbonell, Mª Montserrat; Pujol Ramo, Jaume

    2009-01-01

    This work takes advantage of multispectral data from human irises, ocular prostheses and colored contact lenses to compare them accounting for their texture features. For this aim, several procedures from image processing were implemented: image segmentation algorithms to extract the areas of interest, statical texture analysis tools for texture description, and statistical classifiers for samples discrimination from texture descriptors. For the texture study two approaches were implemented, ...

  19. In vivo implant fixation of carbon fiber-reinforced PEEK hip prostheses in an ovine model.

    Science.gov (United States)

    Nakahara, Ichiro; Takao, Masaki; Bandoh, Shunichi; Bertollo, Nicky; Walsh, William R; Sugano, Nobuhiko

    2013-03-01

    Carbon fiber-reinforced polyetheretherketone (CFR/PEEK) is theoretically suitable as a material for use in hip prostheses, offering excellent biocompatibility, mechanical properties, and the absence of metal ions. To evaluate in vivo fixation methods of CFR/PEEK hip prostheses in bone, we examined radiographic and histological results for cementless or cemented CFR/PEEK hip prostheses in an ovine model with implantation up to 52 weeks. CFR/PEEK cups and stems with rough-textured surfaces plus hydroxyapatite (HA) coatings for cementless fixation and CFR/PEEK cups and stems without HA coating for cement fixation were manufactured based on ovine computed tomography (CT) data. Unilateral total hip arthroplasty was performed using cementless or cemented CFR/PEEK hip prostheses. Five cementless cups and stems and six cemented cups and stems were evaluated. On the femoral side, all cementless stems demonstrated bony ongrowth fixation and all cemented stems demonstrated stable fixation without any gaps at both the bone-cement and cement-stem interfaces. All cementless cases and four of the six cemented cases showed minimal stress shielding. On the acetabular side, two of the five cementless cups demonstrated bony ongrowth fixation. Our results suggest that both cementless and cemented CFR/PEEK stems work well for fixation. Cup fixation may be difficult for both cementless and cemented types in this ovine model, but bone ongrowth fixation on the cup was first seen in two cementless cases. Cementless fixation can be achieved using HA-coated CFR/PEEK implants, even under load-bearing conditions. Copyright © 2012 Orthopaedic Research Society.

  20. Dental prostheses mimic the natural enamel behavior under functional loading: A review article

    Directory of Open Access Journals (Sweden)

    Ahmed A. Madfa

    2016-02-01

    Full Text Available Alumina- and zirconia-based ceramic dental restorations are designed to repair functionality as well as esthetics of the failed teeth. However, these materials exhibited several performance deficiencies such as fracture, poor esthetic properties of ceramic cores (particularly zirconia cores, and difficulty in accomplishing a strong ceramic–resin-based cement bond. Therefore, improving the mechanical properties of these ceramic materials is of great interest in a wide range of disciplines. Consequently, spatial gradients in surface composition and structure can improve the mechanical integrity of ceramic dental restorations. Thus, this article reviews the current status of the functionally graded dental prostheses inspired by the dentino-enamel junction (DEJ structures and the linear gradation in Young's modulus of the DEJ, as a new material design approach, to improve the performance compared to traditional dental prostheses. This is a remarkable example of nature's ability to engineer functionally graded dental prostheses. The current article opens a new avenue for recent researches aimed at the further development of new ceramic dental restorations for improving their clinical durability.

  1. Interest of Flow Diversion Prostheses in the Management of Unruptured Intracranial Aneurysms

    Directory of Open Access Journals (Sweden)

    Xavier Armoiry

    2012-01-01

    Full Text Available Flow diversion prostheses represent a new endovascular approach aimed at treating patients with large wide-neck aneurysms. Our objective is to present this new technology, to review the clinical studies on efficacy, and to emphasize its current limits. Flow diversion prostheses consist of a cylinder made of a large number of braided microfilaments providing a large metallic surface when deployed and inducing a blood flow diversion outside the aneurysm. Two different brands are currently available. Clinical data supporting their efficacy are currently limited to six non comparative cohort studies that included between 18 and 107 patients. Procedural implantation was shown to be feasible in more than 90% and safe with a thirty-day mortality between 2.8 and 5.5%. Complete occlusion rates at twelve months varied between 85.7 and 100%. Even though promising, the current status of flow diversion prostheses needs further evaluation with randomized, prospective, clinical trials with comparison to conventional strategies including endovascular coiling or surgical clipping.

  2. APPLICATION OF SELECTIVE LASER MELTING IN MANUFACTURING OF FIXED DENTAL PROSTHESES

    Directory of Open Access Journals (Sweden)

    Dzhendo Dzhendov

    2016-12-01

    Full Text Available The additive technologies characterize with the building of one layer at a time from a powder or liquid that is bonded by means of melting, fusing or polymerization. They offer a number of advantages over traditional methods: production of complex personalized objects without the need of complex machinery; manufacturing of parts with dense as well as the porous structure and predetermined surface roughness; controllable, easy and relatively quick process. The methods, mostly used in prosthetic dentistry, include stereolithography, selective laser sintering, and selective laser melting. The aim of the present paper is to review the features of the Selective Laser Melting (SLM process and the possibilities of its application for production of fixed dental prostheses. The features of the SLM process, the microstructure and mechanical characteristics of dental alloys as well as the properties of fixed dental prostheses, fabricated via SLM, were discussed. It was revealed that the SLM Co-Cr dental alloys possess higher mechanical and tribo-corrosion properties, comparatively good fitting ability and higher adhesion strength of the porcelain comparing to the cast alloys. All this is a good precondition for successful application of the SLM process in the production of fixed dental prostheses, mainly of frameworks for metal-ceramic and constructions covered with polymer/composite, intended for areas with high loading.

  3. Biomedical Titanium alloy prostheses manufacturing by means of Superplastic and Incremental Forming processes

    Directory of Open Access Journals (Sweden)

    Piccininni Antonio

    2016-01-01

    Full Text Available The present work collects some results of the three-years Research Program “BioForming“, funded by the Italian Ministry of Education (MIUR and aimed to investigate the possibility of using flexible sheet forming processes, i.e. Super Plastic Forming (SPF and Single Point Incremental Forming (SPIF, for the manufacturing of patient-oriented titanium prostheses. The prosthetic implants used as case studies were from the skull; in particular, two different Ti alloys and geometries were considered: one to be produced in Ti-Gr23 by SPF and one to be produced in Ti-Gr2 by SPIF. Numerical simulations implementing material behaviours evaluated by characterization tests were conducted in order to design both the manufacturing processes. Subsequently, experimental tests were carried out implementing numerical results in terms of: (i gas pressure profile able to determine a constant (and optimal strain rate during the SPF process; (ii tool path able to avoid rupture during the SPIF process. Post forming characteristics of the prostheses in terms of thickness distributions were measured and compared to data from simulations for validation purposes. A good correlation between numerical and experimental thickness distributions has been obtained; in addition, the possibility of successfully adopting both the SPF and the SPIF processes for the manufacturing of prostheses has been demonstrated.

  4. [A preliminary study on the cavity forming of the facial prostheses based on three dimensional printing].

    Science.gov (United States)

    Sun, Jian; Zhang, Fu-qiang

    2010-12-01

    To investigate the feasibility of applying three-dimensional printing in the fabrication of facial prostheses cavity. The computer aided design (CAD) model of negative mold of a nasal prosthesis was generated with Magics RP software according to an existed CAD model of the positive pattern of nasal prosthesis (STL file). The negative mold and positive pattern of the nasal prosthesis were fabricated by three dimensional printing. The actual nasal prosthesis was produced by pouring silicon into the negative mold. The actual nasal prosthesis and rapid prototyping (RP) fabricated positive pattern were both scanned with a three-dimensional scanning system. Quantitative measurements of registration errors were calculated to evaluate the surface matching degree between the two models. The max positive error between the models of the actual silicon nasal prosthesis and the RP-fabricated positive pattern was 0.98 mm. It was located at the apex nasi area, and the max negative error was -0.64 mm. Facial prostheses cavity direct three dimensional printing can be one of the methods for automated fabrication of the facial prostheses.

  5. Visual prostheses: The enabling technology to give sight to the blind

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Maghami

    2014-01-01

    Full Text Available Millions of patients are either slowly losing their vision or are already blind due to retinal degenerative diseases such as retinitis pigmentosa (RP and age-related macular degeneration (AMD or because of accidents or injuries. Employment of artificial means to treat extreme vision impairment has come closer to reality during the past few decades. Currently, many research groups work towards effective solutions to restore a rudimentary sense of vision to the blind. Aside from the efforts being put on replacing damaged parts of the retina by engineered living tissues or microfabricated photoreceptor arrays, implantable electronic microsystems, referred to as visual prostheses, are also sought as promising solutions to restore vision. From a functional point of view, visual prostheses receive image information from the outside world and deliver them to the natural visual system, enabling the subject to receive a meaningful perception of the image. This paper provides an overview of technical design aspects and clinical test results of visual prostheses, highlights past and recent progress in realizing chronic high-resolution visual implants as well as some technical challenges confronted when trying to enhance the functional quality of such devices.

  6. PIXE characterization of tissues surrounding metallic prostheses coated with biological glasses

    Energy Technology Data Exchange (ETDEWEB)

    Barbotteau, Y. E-mail: yves.barbotteau@qse.tohoku.ac.jp; Irigaray, J.L.; Moretto, Ph

    2004-01-01

    Biological glasses can be used as coatings for metallic prostheses in order to prevent corrosion. According to their composition, these glasses have different properties. We studied, in vivo, two glasses referred to as BVA and BVH. They are used as coatings of Ti6Al4V metallic implant. BVA glass disappears after 3 months of implantation and is replaced by bone. Prostheses initially coated by this glass have a larger osseous contact perimeter compared to the uncoated prostheses. This ensures a better anchoring of the implant and limits the micro-motions which cause wear debris. BVH glass keeps a constant composition during implantation and it is used like a layer which isolates metal implant from biological environment. In order to characterize the bony environment surrounding implants, we have used PIXE and RBS methods. This paper shows results of the behavior of bony tissue under micro-beam, the quality tests of new bone which replaces the BVA glass coating and the evaluation of corrosion effects. Titanium release in bony tissues begins when the metal surface of the prosthesis is exposed to biological fluids. After a few months of implantation, the titanium contamination is stabilized and remains localized within the first tens of micrometers of surrounding bone.

  7. On the relevance of uniaxial tensile testing of urogynecological prostheses: the effect of displacement rate.

    Science.gov (United States)

    Bazi, Tony; Ammouri, Ali H; Hamade, Ramsey F

    2013-01-01

    Uniaxial tensile testing is commonly used to calculate values of mechanical properties of urogynecological prostheses used in stress urinary incontinence and pelvic organ prolapse surgery in women. Clinical behavior of these products has been linked to their mechanical properties, hence influencing the clinician's preference for one brand or another. The objective of this study is to assess the effect of displacement rate used in uniaxial tensile testing on peak load, extension at peak load, and initial stiffness of Prolene® mesh, used as a proxy for urogynecological prostheses. Strips of Prolene® mesh measuring 10 × 30 mm were submitted to uniaxial tensile testing at the following rates: 1, 10, 50, 100, and 500 mm/min. Peak load, elongation at peak load, and initial stiffness were computed from load vs displacement curves at all displacement rates. The effect of displacement rate on these parameters was estimated by fitting linear trend lines through the data. The displacement rate at which uniaxial tensile testing is performed has significant effects on the values of extension at peak load and initial stiffness, but not on the peak load. When urogynecological prostheses are submitted to uniaxial tensile testing, studies at more than one displacement rate should be performed. More importantly, these displacement rates should be within the range of applicability.

  8. Survival and complications of zirconia-based fixed dental prostheses: a systematic review.

    Science.gov (United States)

    Raigrodski, Ariel J; Hillstead, Matthew B; Meng, Graham K; Chung, Kwok-Hung

    2012-03-01

    Evidence is limited on the efficacy of zirconia-based fixed dental prostheses. The purpose of this systemic review was to assess zirconia-based FDPs in terms of survival and complications. Searches performed in PubMed databases were enriched by hand searches to identify suitable publications. The keywords used were: "zirconia" and "fixed dental prosthesis," "zirconia" and "crown," "zirconia" and "fixed partial denture" and "humans," "zirconia" and "crown" and "humans," "crown" and "all-ceramics," and "fixed partial denture" and "all-ceramics". Titles and abstracts were read to identify literature that fulfilled the inclusion criteria. Only peer reviewed clinical studies published in the English language from January 1999 through June 2011 were included. Twelve clinical studies based on zirconia, framework design, and porcelain veneering technique met the inclusion criteria. Of the studies identified, 1 was a randomized clinical study with 3-year follow-up results; the others were cohort prospective studies. Clinical complications included chipping of veneering porcelain, abutment failure, and framework fracture. One study investigated pressed ceramics as the veneering material and found no chipping of veneering porcelain after 3 years. Short term clinical data suggest that zirconia-based fixed dental prostheses may serve as an alternative to metal ceramic fixed dental prostheses in the anterior and posterior dentition. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  9. PARTICIPATORY DESIGN OF PEDIATRIC UPPER LIMB PROSTHESES: QUALITATIVE METHODS AND PROTOTYPING.

    Science.gov (United States)

    Sims, Tara; Cranny, Andy; Metcalf, Cheryl; Chappell, Paul; Donovan-Hall, Maggie

    2017-09-06

    The study aims to develop an understanding of the views of children and adolescents, parents, and professionals on upper limb prosthetic devices to develop and improve device design. Previous research has found that children are dissatisfied with prostheses but has relied heavily on parent proxy reports and quantitative measures (such as questionnaires) to explore their views. Thirty-four participants (eight children aged 8-15 years with upper limb difference, nine parents, eight prosthetists, and nine occupational therapists) contributed to the development of new devices through the BRIDGE methodology of participatory design, using focus groups and interviews. The study identified areas for improving prostheses from the perspective of children and adolescents, developed prototypes based on these and gained feedback on the prototypes from the children and other stakeholders (parents and professionals) of paediatric upper limb prostheses. Future device development needs to focus on ease of use, versatility, appearance, and safety. This study has demonstrated that children and adolescents can and should be involved as equal partners in the development of daily living equipment and that rapid prototyping (three-dimensional printing or additive manufacturing), used within a participatory design framework, can be a useful tool for facilitating this.

  10. EFFICIENCY OF PROSTHETIC TREATMENT WITH POST RESECTION PROSTHESES WITH SOLID SUBSTITUTE PART

    Directory of Open Access Journals (Sweden)

    Ivan Gerdzhikov

    2016-08-01

    Full Text Available Aim: The aim of this study is to track the effectiveness of prosthetic treatment with post resection dentures with solid substitute part and their role in the restoration of damaged functions. Materials and methods: The study included 14 patients (9 men and 5 women with different size and location of defects in the upper jaw treated in the period 2010-2016 with post resection prostheses with a solid substitute part. The impressions were taken with irreversible hydrocolloid impression material. The prostheses were completed by heat-curing acrylic with low quantity residual monomer. The effectiveness of prosthetics was evaluated by the method of Mihaylov for both oral-nasal examination of the pressure with the device "Oronasopneumotest." For objectifying and assess the occlusal-articulation ratios was held computerized occlusal analysis with the system T-SCAN 8. Results: The results showed successful obturation and sealing of defects in all patients. It was found satisfactory recovery of the speaking function and normalization of occlusal-articulation ratios. Conclusion: The prosthetic treatment with post resection prostheses with a solid substitute part allows successful recovery of the lost speech and chewing functions, helping to restore self esteem and social rehabilitation of patients.

  11. Earth Radiation Imbalance from a Constellation of 66 Iridium Satellites: Climate Science Aspects

    Science.gov (United States)

    Wiscombe, W.; Chiu, CJ. Y.

    2012-01-01

    The "global warming hiatus" since the 1998 El Nino, highlighted by Meehl et al., and the resulting "missing energy" problem highlighted by Trenberth et al., has opened the door to a more fundamental view of climate change than mere surface air temperature. That new view is based on two variables which are strongly correlated: the rate of change of ocean heat content d(OHC)/dt; and Earth Radiation Imbalance (ERI) at the top of the atmosphere, whose guesstimated range is 0.4 to 0.9 Watts per square meters (this imbalance being mainly due to increasing CO2). The Argo float array is making better and better measurements of OHC. But existing satellite systems cannot measure ERI to even one significant digit. So, climate model predictions of ERI are used in place of real measurements of it, and the satellite data are tuned to the climate model predictions. Some oceanographers say "just depend on Argo for understanding the global warming hiatus and the missing energy", but we don't think this is a good idea because d(OHC)/dt and ERI have different time scales and are never perfectly correlated. We think the ERB community needs to step up to measuring ERI correctly, just as oceanographers have deployed Argo to measure OHC correctly. This talk will overview a proposed constellation of 66 Earth radiation budget instruments, hosted on Iridium satellites, that will actually be able to measure ERI to at least one significant digit, thus enabling a crucial test of climate models. This constellation will also be able to provide ERI at two-hourly time scales and 500-km spatial scales without extrapolations from uncalibrated narrowband geostationary instruments, using the highly successful methods of GRACE to obtain spatial resolution. This high time resolution would make ERI a synoptic variable like temperature, and allow studies of ERI's response to fast-evolving phenomena like dust storms and hurricanes and even brief excursions of Total Solar Irradiance. Time permitting, we

  12. Volcanic ash layers in blue ice fields (Beardmore Glacier Area, Antarctica): Iridium enrichments

    Science.gov (United States)

    Koeberl, Christian

    samples, including Ir. Iridium determinations were made using INAA, with synthetical and natural (meteorite) standards. These findings are discussed.

  13. Biomechanical evaluation of two types of short-stemmed hip prostheses compared to the trust plate prosthesis by three-dimensional measurement of micromotions.

    Science.gov (United States)

    Fottner, Andreas; Schmid, Markus; Birkenmaier, Christof; Mazoochian, Farhad; Plitz, Wolfgang; Volkmar, Jansson

    2009-06-01

    Stemless and short-stemmed hip prostheses have been developed to preserve femoral bone stock. While all these prostheses claim a more or less physiological load transfer, clinical long-term results are only available for the stemless thrust plate prosthesis. In this study, the in vitro primary stability of the thrust plate prosthesis was compared to two types of short-stemmed prostheses. In addition to the well-established Mayo prosthesis, the modular Metha prosthesis was tested using cone adapters with 130 degrees and 140 degrees neck-shaft-angles. The prostheses were implanted in composite femurs and loaded dynamically (300-1700 N). Three-dimensional micromotions at the bone-prosthesis interface were measured. In addition, the three-dimensional deformations at the surface of the composite femur were measured to gain data on the strain distribution. For all tested prostheses, the micromotions did not exceed 150 microm, the critical value for osteointegration. The thrust plate prosthesis revealed similar motions as the short-stemmed prostheses. The short-stemmed prosthesis with the 130 degrees cone tended to have the highest micromotions of all tested short-stemmed prostheses. The thrust plate prosthesis revealed the lowest alteration of bone surface deformation after implantation. The comparably low micromotions of the thrust plate prosthesis and the short-stemmed prostheses should be conducive to osseous integration. The higher alteration of load transmission after implantation reveals a higher risk of stress shielding for the short-stemmed prostheses.

  14. Introduction to neural networks

    CERN Document Server

    James, Frederick E

    1994-02-02

    1. Introduction and overview of Artificial Neural Networks. 2,3. The Feed-forward Network as an inverse Problem, and results on the computational complexity of network training. 4.Physics applications of neural networks.

  15. Morphological neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, G.X.; Sussner, P. [Univ. of Florida, Gainesville, FL (United States)

    1996-12-31

    The theory of artificial neural networks has been successfully applied to a wide variety of pattern recognition problems. In this theory, the first step in computing the next state of a neuron or in performing the next layer neural network computation involves the linear operation of multiplying neural values by their synaptic strengths and adding the results. Thresholding usually follows the linear operation in order to provide for nonlinearity of the network. In this paper we introduce a novel class of neural networks, called morphological neural networks, in which the operations of multiplication and addition are replaced by addition and maximum (or minimum), respectively. By taking the maximum (or minimum) of sums instead of the sum of products, morphological network computation is nonlinear before thresholding. As a consequence, the properties of morphological neural networks are drastically different than those of traditional neural network models. In this paper we consider some of these differences and provide some particular examples of morphological neural network.

  16. Iridium-complex-functionalized Fe3O4/SiO2 core/shell nanoparticles: a facile three-in-one system in magnetic resonance imaging, luminescence imaging, and photodynamic therapy.

    Science.gov (United States)

    Lai, Chih-Wei; Wang, Yu-Hsiu; Lai, Cheng-Hsuan; Yang, Meng-Ju; Chen, Chun-Yen; Chou, Pi-Tai; Chan, Chi-Shun; Chi, Yun; Chen, Yu-Chun; Hsiao, Jong-Kai

    2008-02-01

    Highly uniform Fe3O4/SiO2 core/shell nanoparticles functionalized by phosphorescent iridium complexes (Ir) have been strategically designed and synthesized. The Fe3O4/SiO2(Ir) nanocomposite demonstrates its versatility in various applications: the magnetic core provides the capability for magnetic resonance imaging and the great enhancement of the spin-orbit coupling in the iridium complex makes it well suited for phosphorescent labeling and simultaneous singlet oxygen generation to induce apoptosis.

  17. New iridium complex as additive to the spiro-OMeTAD in perovskite solar cells with enhanced stability

    Directory of Open Access Journals (Sweden)

    Laura Badia

    2014-08-01

    Full Text Available A new iridium complex, IrCp*Cl(PyPyz[TFSI], has been synthesized and used as additive for the hole transporter material, spiro-OMeTAD, in perovskite solar cells. The cells prepared with this Ir additive present higher efficiency than reference cells, and similar to cells prepared with Co additive. We have determined that the presence of metal complexes as additives decreases the recombination rate, as it has been observed by impedance spectroscopy. Very interestingly, while the efficiency after 3 months decreases by 22% and 70% for reference cell and cell with Co additive, respectively, the efficiency of devices containing the Ir additive is only decreased by a 4%.

  18. Exciplex emission and Auger process assistant green organic electrophosphorescence devices with very low doped level of iridium complex

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Dongyu; Li Wenlian; Chu Bei; Li Xiao; Su Zisheng; Han Liangliang; Li Tianle; Chen Yiren; Yan Fei; Wu Shuanghong [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Zhang Zhiqiang; Hu Zhizhi [Organic Photoelectronic Materials and Technology Development Center, Liaoning University of Science and Technology, Anshan (China)], E-mail: wllioel@yahoo.com.cn, E-mail: beichu@163.com

    2008-12-21

    We demonstrate efficient and simple structure phosphorescence organic light-emitting diodes, in which 4, 4', 4''-tris[3-methyl-pheny(phenyl)-amino]triphenyl -amine (m-MTDATA) and 4,7-diphenyl-1,10-phenanthroline (Bphen) are used as hole transport and electron transport layers, respectively, accompanied by 3 wt% fac-tris(2-phenylpyridine) iridium doped in 1,3,5-tris(N-phenylbenzimidazol-2-yl)-benzene (Ir : TPBi) as the emitting layer. As a result, a 29 lm W{sup -1} peak power efficiency and 2.2 V turn-on voltage are achieved, respectively. The achievement of excellent electroluminescence (EL) properties was attributed to the contribution of exciplex formation at the interface of m-MTDATA/Ir : TPBi and the Auger-type two-step process of charge carrier injection. The competition between the interfacial exciplex and Ir-complex emissions in the EL processes was also discussed.

  19. Sport prostheses and prosthetic adaptations for the upper and lower limb amputees: an overview of peer reviewed literature.

    Science.gov (United States)

    Bragaru, Mihai; Dekker, Rienk; Geertzen, Jan H B

    2012-09-01

    Sport prostheses are used by both upper- and lower-limb amputees while participating in sports and other physical activities. Although the number of these devices has increased over the past decade, no overview of the peer reviewed literature describing them has been published previously. Such an overview will allow specialists to choose appropriate prostheses based on available scientific evidence rather than on personal experience or preference. To provide an overview of the sport prostheses as they are described by the papers published in peer reviewed literature. Literature review. Four electronic databases were searched using free text and Medical Subject Headings (MESH) terms. Papers were included if they concerned a prosthesis or a prosthetic adaptation used in sports. Papers were excluded if they did not originate from peer reviewed sources, if they concerned prostheses for body parts other than the upper or lower limbs, if they concerned amputations distal to the wrist or ankle, or if they were written in a language other than English. Twenty-four papers were included in this study. The vast majority contained descriptive data and consisted of expert opinions and technical notes. Data concerning the energy efficiency, technical characteristics and special mechanical properties of prostheses or prosthetic adaptations for sports, other than running, are scarce.

  20. Hydrophilic surface modification of poly(methyl methacrylate)-based ocular prostheses using poly(ethylene glycol) grafting.

    Science.gov (United States)

    Ko, JaeSang; Cho, Kanghee; Han, Sang Won; Sung, Hyung Kyung; Baek, Seung Woon; Koh, Won-Gun; Yoon, Jin Sook

    2017-10-01

    Ocular prostheses are custom-made polymeric inserts that can be placed in anophthalmic sockets for cosmetic rehabilitation. Prosthetic eye wearers have reduced tear amount, and they often experience dry eye symptoms including dryness, irritation, discomfort, and discharge. Most modern ocular prostheses are made of poly(methyl methacrylate) (PMMA), which is highly hydrophobic. Previous research has shown that improving the wettability of contact lens materials decreases its wearers discomfort by increasing lubrication. Therefore, hydrophilic modification of PMMA-based ocular prostheses might also improve patient discomfort by improving lubrication. We modified the surfaces of PMMA-based ocular prostheses using poly(ethylene glycol) (PEG), which is hydrophilic. To do this, we used two strategies. One was a "grafting from" method, whereby PEG was polymerized from the PMMA surface. The other was a "grafting to" method, which involved PEG being covalently bonded to an amine-functionalized PMMA surface. Assessments involving the water contact angle, ellipsometry, and X-ray photoelectron spectroscopy indicated that PEG was successfully introduced to the PMMA surfaces using both strategies. Scanning electron microscopy and atomic force microscopy images revealed that neither strategy caused clinically significant alterations in the PMMA surface morphology. In vitro bacterial adhesion assessments showed that the hydrophilic modifications effectively reduced bacterial adhesion without inducing cytotoxicity. These results imply that hydrophilic surface modifications of conventional ocular prostheses may decrease patient discomfort and ocular prosthesis-related infections. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Absorbed dose simulations in near-surface regions using high dose rate Iridium-192 sources applied for brachytherapy

    Science.gov (United States)

    Moura, E. S.; Zeituni, C. A.; Sakuraba, R. K.; Gonçalves, V. D.; Cruz, J. C.; Júnior, D. K.; Souza, C. D.; Rostelato, M. E. C. M.

    2014-02-01

    Brachytherapy treatment with Iridium-192 high dose rate (HDR) sources is widely used for various tumours and it could be developed in many anatomic regions. Iridium-192 sources are inserted inside or close to the region that will be treated. Usually, the treatment is performed in prostate, gynaecological, lung, breast and oral cavity regions for a better clinical dose coverage compared with other techniques, such as, high energy photons and Cobalt-60 machines. This work will evaluate absorbed dose distributions in near-surface regions around Ir-192 HDR sources. Near-surface dose measurements are a complex task, due to the contribution of beta particles in the near-surface regions. These dose distributions should be useful for non-tumour treatments, such as keloids, and other non-intracavitary technique. For the absorbed dose distribution simulations the Monte Carlo code PENELOPE with the general code penEasy was used. Ir-192 source geometry and a Polymethylmethacrylate (PMMA) tube, for beta particles shield were modelled to yield the percentage depth dose (PDD) on a cubic water phantom. Absorbed dose simulations were realized at the central axis to yield the Ir-192 dose fall-off along central axis. The results showed that more than 99.2% of the absorbed doses (relative to the surface) are deposited in 5 cm depth but with slower rate at higher distances. Near-surface treatments with Ir-192 HDR sources yields achievable measurements and with proper clinical technique and accessories should apply as an alternative for treatment of lesions where only beta sources were used.

  2. Comparison of fixed implant-supported prostheses, removable implant-supported prostheses, and complete dentures: patient satisfaction and oral health-related quality of life.

    Science.gov (United States)

    Oh, Sung-Hee; Kim, Younhee; Park, Joo-Yeon; Jung, Yea Ji; Kim, Seong-Kyun; Park, Sun-Young

    2016-02-01

    The purpose of this study was to compare patient satisfaction and oral health-related quality of life (OHRQoL) among fully edentulous patients treated with either fixed implant-supported prostheses (FP), removable implant-supported prostheses (RP), or complete dentures (CD). Eighty-six patients - 29 FP, 27 RP, and 30 CD patients - participated in this study. The survey was conducted using face-to-face interviews with a questionnaire that included a patient satisfaction scale and Oral Health Impact Profile (OHIP-14). We measured patient satisfaction after prosthetic treatments and OHRQoL before and after the treatments. After prosthetic treatments, OHRQoL increased in all three groups (P < 0.05). The FP and RP groups showed no significant difference in patient satisfaction and OHRQoL, and both groups showed greater improvement compared with the CD group. Specifically, the OHRQoL dimensions of functional limitation, physical pain, psychological discomfort, and psychological disability in the FP group, and functional limitation in the RP group, improved greatly in comparison with the CD group (P < 0.05). Although further research is still needed, prosthetic treatments may provide superior OHRQoL for fully edentulous patients. In particular, both the FP and RP treatments provided significantly greater improvement of OHRQoL and patient satisfaction than the CD treatment. Reliable information of OHRQoL and patient satisfaction helps experts and patients choose the best prosthetic treatment option. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Four-coordinate iridium(I) monohydrides: reversible dinitrogen binding, bond activations, and deprotonations.

    Science.gov (United States)

    Millard, Matthew D; Moore, Curtis E; Rheingold, Arnold L; Figueroa, Joshua S

    2010-07-07

    Detailed herein are synthetic, spectroscopic and reactivity studies for two isolable four-coordinate iridium(I) monohydride complexes of the simple formulation HIrL(3). Such complexes have been postulated as reactive species in several transformations, but definite evidence for their existence has remained elusive. To stabilize these complexes, the methyleneadamantyl substituted phosphine ligand P(CH(2)(1)Ad)(i-Pr)(2) (abbreviated L(mAd)) was employed because of the resistance of the adamantane cage toward cyclometalation reactions. Treatment of the dihydride-chloride complex, H(2)IrCl(L(mAd))(2) with PhMgBr under N(2) afforded the square planar complex HIr(N(2))(L(mAd))(2). Contrastingly, treatment of H(2)IrCl(L(mAd))(2) with Li[HBEt(3)] under N(2) generates the trihydride complex H(3)Ir(L(mAd))(2), which possesses an agostic interaction between the L(mAd) ligand and the Ir center. Dissolution of HIr(N(2))(L(mAd))(2) in Et(2)O or C(6)D(12) rapidly establishes an equilibrium mixture with the cyclometalated complex H(2)Ir(kappa(2)-P,C-L(mAd))(L(mAd)). Despite the equilibrium between HIr(N(2))(L(mAd))(2) and H(2)Ir(kappa(2)-P,C-L(mAd))(L(mAd)), addition of 2 equiv of H(2) or 1 equiv of H(2)O to the mixture cleanly generates the pentahydride complex H(5)Ir(L(mAd))(2) or the dihydride hydroxide complex H(2)Ir(OH)(L(mAd))(2), respectively. Sequential addition (n)BuLi and 12-crown-4 (12-c-4) to a HIr(N(2))(L(mAd))(2)/H(2)Ir(kappa(2)-P,C-L(mAd))(L(mAd)), mixture provides the salt [Li(12-c-4)(2)][HIr(kappa(2)-P,C-L(mAd))(L(mAd))], which contains another four-coordinate Ir(I) monohydride. (31)P{(1)H} NMR studies provide evidence that four-coordinate HIr(N(2))(L(mAd))(2) is deprotonated en route to [Li(12-c-4)(2)][HIr(kappa(2)-P,C-L(mAd))(L(mAd))]. [Li(12-c-4)(2)][HIr(kappa(2)-P,C-L(mAd))(L(mAd))] deprotonates both H(2)N(2,6-(i-Pr)(2)C(6)H(3)) and HOC(6)F(5) under an N(2) atmosphere to regenerate HIr(N(2))(L(mAd))(2)/H(2)Ir(kappa(2)-P,C-L(mAd))(L(mAd)) equilibrium mixtures.

  4. A biodegradable gentamicin-hydroxyapatite-coating for infection prophylaxis in cementless hip prostheses.

    Science.gov (United States)

    Neut, D; Dijkstra, R J; Thompson, J I; Kavanagh, C; van der Mei, H C; Busscher, H J

    2015-01-02

    A degradable, poly (lactic-co-glycolic acid) (PLGA), gentamicin-loaded prophylactic coating for hydroxyapatite (HA)-coated cementless hip prostheses is developed with similar antibacterial efficacy as offered by gentamicin-loaded cements for fixing traditional, cemented prostheses in bone. We describe the development pathway, from in vitro investigation of antibiotic release and antibacterial properties of this PLGA-gentamicin-HA-coating in different in vitro models to an evaluation of its efficacy in preventing implant-related infection in rabbits. Bone in-growth in the absence and presence of the coating was investigated in a canine model. The PLGA-gentamicin-HA-coating showed high-burst release, with antibacterial efficacy in agar-assays completely disappearing after 4 days, minimising risk of inducing antibiotic resistance. Gentamicin-sensitive and gentamicin-resistant staphylococci were killed by the antibiotic-loaded coating, in a simulated prosthesis-related interfacial gap. PLGA-gentamicin-HA-coatings prevented growth of bioluminescent staphylococci around a miniature-stem mounted in bacterially contaminated agar, as observed using bio-optical imaging. PLGA-gentamicin-HA-coated pins inserted in bacterially contaminated medullary canals in rabbits caused a statistically significant reduction in infection rates compared to HA-coated pins without gentamicin. Bone ingrowth to PLGA-gentamicin-HA-coated pins, in condylar defects of Beagle dogs was not impaired by the presence of the degradable, gentamicin-loaded coating. In conclusion, the PLGA-gentamicin-HA-coating constitutes an effective strategy for infection prophylaxis in cementless prostheses.

  5. Long-term role of external breast prostheses after total mastectomy.

    Science.gov (United States)

    Glaus, Simone W; Carlson, Grant W

    2009-01-01

    After total mastectomy, many women choose to wear external breast prosthesis rather than undergo breast reconstruction. The purpose of this study was to evaluate long-term satisfaction among external breast prosthesis wearers and the impact of satisfaction on prosthesis use. A questionnaire was designed to assess demographic information, prosthesis information provision, prosthesis use, and satisfaction with prosthesis. Fifty-nine women who had undergone total mastectomy without breast reconstruction completed the questionnaire. The majority of women (68%) were at least 5 years out from mastectomy. Approximately half (49%) of the women had received information about breast prostheses prior to mastectomy; 29% received information from the surgeon performing the operation. Frequent and prolonged prosthesis use was prevalent with 64% of participants reporting prosthesis use all the time, 6-7 days/week. Participants showed high rates (83%) of overall satisfaction. However, women who wore their prosthesis out in public only were less satisfied than more frequent wearers (50% versus 89%, chi(2) = 8.83, d.f. = 1, alpha = 0.05). Satisfaction increased over time, as women who were greater than 5 years out from mastectomy were more satisfied than women less that 5 years post-mastectomy (90% versus 67%, chi(2) = 4.43, d.f. = 1, alpha = 0.05). The vast majority of women are satisfied with their external breast prosthesis several years after mastectomy. Most women used their prosthesis all the time and overall satisfaction contributed to higher levels of prosthesis use. Given the long-term importance of external breast prostheses for women who have undergone mastectomy, a greater effort to inform patients about external breast prostheses prior to surgery is needed.

  6. Impact of fixed implant supported prostheses in edentulous patients: protocol for a systematic review.

    Science.gov (United States)

    López, Carolina S; Saka, Constanza H; Rada, Gabriel; Valenzuela, Daniela D

    2016-02-23

    Edentulism is a debilitating and irreversible condition described as the 'final marker of disease burden for oral health'. Therapy with dental implants is being used on a large scale to replace missing teeth and to rehabilitate edentulous patients with overdentures and implant supported fixed dentures as a method of solving the problem of instability and lack of retention associated with conventional removable prostheses. Fixed implant supported prostheses are an alternative for implant rehabilitation treatment that allow patients to have new fixed teeth. They can be indicated in partial or total edentulous patients, and they can replace single teeth, or teeth and supporting tissues (hybrid prosthesis). They overcome the limitations of conventional dentures, increasing stability and retention, providing functional and psychological advantages for the patients. We will electronically search for randomised controlled trials evaluating the effects of fixed implant supported prostheses in edentulous patients in the following databases: Pubmed/MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials. We will also try to obtain literature screening references of included studies, searching for trial protocols in the WHO International Clinical Trials Registry Platform, reviewing International Team for Implantology conference proceedings and searching for non-published studies through Open Gray. Two researchers will independently undertake selection of studies, data extraction and assessment of the quality of the included studies. Data synthesis and subgroup analyses will be performed using special Review Manager software. Data will be combined in a meta-analysis using a random effects model. The results will be presented as risk ratios for dichotomous data, and as mean difference or standardised mean difference for continuous data. No ethics approval is considered necessary. The results of this study will be disseminated via peer reviewed publications and

  7. Immediate loading with fixed full-arch prostheses in the maxilla: Review of the literature

    Science.gov (United States)

    Peñarrocha-Oltra, David; Covani, Ugo; Peñarrocha-Diago, Miguel

    2014-01-01

    Objectives: To critically review the evidence-based literature on immediate loading of implants with fixed full-arch prostheses in the maxilla to determine 1) currently recommended performance criteria and 2) the outcomes that can be expected with this procedure. Study Desing: Studies from 2001 to 2011 on immediate loading with fixed full-arch maxillary prostheses were reviewed. Clinical series with at least 5 patients and 12 months of follow-up were included. Case reports, studies with missing data and repeatedly published studies were excluded. In each study the following was assessed: type of study, implant type, number of patients, number of implants, number of implants per patient, use of post-extraction implants, minimum implant length and diameter, type of prosthesis, time until loading, implant survival rate, prosthesis survival rate, marginal bone loss, complications andmean follow-up time. Criteria for patient selection, implant primary stability and bone regeneration were also studied. Results: Thirteen studies were included, reporting a total of 2484 immediately loaded implants in 365 patients. Currently accepted performance criteria regarding patient and implant selection, and surgical and prosthetic procedures were deduced from the reviewed articles. Implant survival rates went from 87.5% to 100%, prosthesis survival rates from 93.8% to 100% and radiographic marginal bone loss from 0.8 mm to 1.6 mm.No intraoperative complications and only minor prosthetic complications were reported. Conclusions: The literature on immediate loading with fixed full-arch prostheses in the maxilla shows that a successful outcome can be expected if adequate criteria are used to evaluate the patient, choose the implant and perform the surgical and prosthetic treatment. Lack of homogeneity within studies limits the relevance of the conclusions that can be drawn, and more controlled randomized studies are necessary to enable comparison between the immediate and the

  8. Prevalence of peri-implantitis in patients with implant-supported fixed prostheses.

    Science.gov (United States)

    Schuldt Filho, Guenther; Dalago, Haline Renata; Oliveira de Souza, João Gustavo; Stanley, Kyle; Jovanovic, Sascha; Bianchini, Marco Aurélio

    2014-01-01

    The purpose of this study was to evaluate periimplantitis prevalence in patients using implant-supported fixed prostheses that did not have any routine maintenance care. A total of 161 implants (27 patients) were evaluated in patients using implant-supported fixed prostheses. Collected data included information related to patient general health and local factors such as characteristics of implants, time in function, type of loading, positioning, Modified Bleeding Index, bacterial plaque, bleeding on probing (BOP), marginal recession, probing depth (PD), keratinized mucosa, and radiographic bone loss (BL). Factors related to the prostheses were also evaluated. The exclusion criteria were patients that have had any follow-up visit for plaque control of the prosthesis and/or the implants. From a total of 161 implants, 116 (72%) presented without peri-implantitis (PD > 4 mm + BOP + BL > 2 mm) while 45 (28%) had some sign of the disease. Implants placed in the maxilla were 2.98 times more likely to develop the disease (P < .05). Moreover, patients aged ≤ 60 years old were 3.24 times more likely to develop peri-implantitis (P < .05). Another analysis with statistical relevance (P < .05) was that implants with less than 3 mm interimplant distance were three times more likely to have peri-implantitis. There was no statistical relevance considering other analyses. It can be concluded that patients aged ≤ 60 years have a greater chance of presenting periimplantitis, as well as for implants positioned in the maxilla and those placed with an interimplant distance < 3 mm.

  9. Immediate loading with fixed full-arch prostheses in the maxilla: review of the literature.

    Science.gov (United States)

    Peñarrocha-Oltra, David; Covani, Ugo; Peñarrocha-Diago, Miguel; Peñarrocha-Diago, Maria

    2014-09-01

    To critically review the evidence-based literature on immediate loading of implants with fixed full-arch prostheses in the maxilla to determine 1) currently recommended performance criteria and 2) the outcomes that can be expected with this procedure. Studies from 2001 to 2011 on immediate loading with fixed full-arch maxillary prostheses were reviewed. Clinical series with at least 5 patients and 12 months of follow-up were included. Case reports, studies with missing data and repeatedly published studies were excluded. In each study the following was assessed: type of study, implant type, number of patients, number of implants, number of implants per patient, use of post-extraction implants, minimum implant length and diameter, type of prosthesis, time until loading, implant survival rate, prosthesis survival rate, marginal bone loss, complications and mean follow-up time. Criteria for patient selection, implant primary stability and bone regeneration were also studied. Thirteen studies were included, reporting a total of 2484 immediately loaded implants in 365 patients. Currently accepted performance criteria regarding patient and implant selection, and surgical and prosthetic procedures were deduced from the reviewed articles. Implant survival rates went from 87.5% to 100%, prosthesis survival rates from 93.8% to 100% and radiographic marginal bone loss from 0.8 mm to 1.6 mm.No intraoperative complications and only minor prosthetic complications were reported. The literature on immediate loading with fixed full-arch prostheses in the maxilla shows that a successful outcome can be expected if adequate criteria are used to evaluate the patient, choose the implant and perform the surgical and prosthetic treatment. Lack of homogeneity within studies limits the relevance of the conclusions that can be drawn, and more controlled randomized studies are necessary to enable comparison between the immediate and the conventional loading procedures.

  10. Implant placement under existing removable dental prostheses and its effect on masticatory performance.

    Science.gov (United States)

    Wolfart, S; Wolf, K; Brunzel, S; Wolfart, M; Caliebe, A; Kern, M

    2016-12-01

    The aim of this within-subject study was to evaluate the outcome with implant-tooth-supported removable partial dental prostheses (RPDP group) and implant-supported removable complete dental prostheses (edentulous group) in terms of masticatory performance and self-assessment. Thirty patients participated in this prospective clinical study (RPDP group: n = 12; edentulous group: n = 18). The prostheses were supported in strategically advantageous regions by placing implants with ball attachments and corresponding matrices in the existing dentures. The masticatory performance was evaluated with the Swallowing Threshold Test Index (STTI), the number of chewing strokes, and the time needed until swallowing at pre-treatment and 6 weeks after integration of ball attachments. Additionally, patients scored chewing satisfaction before and after implantation on a visual analogue scale. The STTI increased significantly (p ≤ 0.05) after implant therapy in the edentulous group but not in the RPDP group. Furthermore, the STTI was significantly higher (p ≤ 0.05) in the RPDP group than in the edentulous group at pre-treatment, however, not after therapy (P > 0.05). All patients were very satisfied after therapy concerning ability of speaking, chewing, and stability of their prosthesis. Patients of the edentulous group benefit more from strategically placed implants under the existing dentures than patients from the RPDP group. However, according to the subjective assessment, the chewing satisfaction generally increased for both groups after implant therapy. Patients with a strongly reduced dentition and edentulous patients benefit from strategically placed implants under the existing removable dentures.

  11. How do the outcomes of the DEKA Arm compare to conventional prostheses?

    Directory of Open Access Journals (Sweden)

    Linda J Resnik

    Full Text Available Objectives were to 1 compare self-reported function, dexterity, activity performance, quality of life and community integration of the DEKA Arm to conventional prostheses; and 2 examine differences in outcomes by conventional prosthesis type, terminal device type and by DEKA Arm configuration level.This was a two-part study; Part A consisted of in-laboratory training. Part B consisted of home use. Study participants were 23 prosthesis users (mean age = 45 ± 16; 87% male who completed Part A, and 15 (mean age = 45 ± 18; 87% male who completed Parts A and B. Outcomes including self-report and performance measures, were collected at Baseline using participants' personal prostheses and at the End of Parts A and B. Scores were compared using paired t-tests. Wilcoxon signed-rank tests were used to compare outcomes for the full sample, and for the sample stratified by device and terminal device type. Analysis of outcomes by configuration level was performed graphically.At the End of Part A activity performance using the DEKA Arm and conventional prosthesis was equivalent, but slower with the DEKA Arm. After Part B, performance using the DEKA Arm surpassed conventional prosthesis scores, and speed of activity completion was equivalent. Participants reported using the DEKA Arm to perform more activities, had less perceived disability, and less difficulty in activities at the End of A and B as compared to Baseline. No differences were observed in dexterity, prosthetic skill, spontaneity, pain, community integration or quality of life. Comparisons stratified by device type revealed similar patterns. Graphic comparisons revealed variations by configuration level.Participants using the DEKA Arm had less perceived disability and more engagement of the prosthesis in everyday tasks, although activity performance was slower. After home use experience, activity performance was improved and activity speed equivalent to using conventional prostheses.

  12. Whole-body angular momentum during stair walking using passive and powered lower-limb prostheses.

    Science.gov (United States)

    Pickle, Nathaniel T; Wilken, Jason M; Aldridge, Jennifer M; Neptune, Richard R; Silverman, Anne K

    2014-10-17

    Individuals with a unilateral transtibial amputation have a greater risk of falling compared to able-bodied individuals, and falling on stairs can lead to serious injuries. Individuals with transtibial amputations have lost ankle plantarflexor muscle function, which is critical for regulating whole-body angular momentum to maintain dynamic balance. Recently, powered prostheses have been designed to provide active ankle power generation with the goal of restoring biological ankle function. However, the effects of using a powered prosthesis on the regulation of whole-body angular momentum are unknown. The purpose of this study was to use angular momentum to evaluate dynamic balance in individuals with a transtibial amputation using powered and passive prostheses relative to able-bodied individuals during stair ascent and descent. Ground reaction forces, external moment arms, and joint powers were also investigated to interpret the angular momentum results. A key result was that individuals with an amputation had a larger range of sagittal-plane angular momentum during prosthetic limb stance compared to able-bodied individuals during stair ascent. There were no significant differences in the frontal, transverse, or sagittal-plane ranges of angular momentum or maximum magnitude of the angular momentum vector between the passive and powered prostheses during stair ascent or descent. These results indicate that individuals with an amputation have altered angular momentum trajectories during stair walking compared to able-bodied individuals, which may contribute to an increased fall risk. The results also suggest that a powered prosthesis provides no distinct advantage over a passive prosthesis in maintaining dynamic balance during stair walking. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. High-density EMG e-textile systems for the control of active prostheses

    DEFF Research Database (Denmark)

    Farina, Dario; Lorrain, Thomas; Negro, Francesco

    2010-01-01

    Myoelectric control of active prostheses requires electrode systems that are easy to apply for daily repositioning of the electrodes by the user. In this study we propose the use of Smart Fabric and Interactive Textile (SFIT) systems as an alternative solution for recording high-density EMG signals...... for myoelectric control. A sleeve covering the upper and lower arm, which contains 100 electrodes arranged in four grids of 5 * 5 electrodes, was used to record EMG signals in 3 subjects during the execution of 9 tasks of the wrist and hand. The signals were analyzed by extracting wavelet coefficients which were...

  14. Optimization of tomotherapy treatment planning for patients with bilateral hip prostheses.

    Science.gov (United States)

    Chapman, David; Smith, Shaun; Barnett, Rob; Bauman, Glenn; Yartsev, Slav

    2014-02-04

    To determine the effect of different imaging options and the most efficient imaging strategy for treatment planning of patients with hip prostheses. The planning kilovoltage CT (kVCT) and daily megavoltage CT (MVCT) studies for three prostate cancer patients with bilateral hip prostheses were used for creating hybrid kVCT/MVCT image sets. Treatment plans were created for kVCT images alone, hybrid kVCT/MVCT images, and MVCT images alone using the same dose prescription and planning parameters. The resulting dose volume histograms were compared. The orthopedic metal artifact reduction (O-MAR) reconstruction tool for kVCT images and different MVCT options were investigated with a water tank fit with double hip prostheses. Treatment plans were created for all imaging options and calculated dose was compared with the one measured by a pin-point ion chamber. On average for three patients, the D35% for the bladder was 8% higher in plans based on MVCT images and 7% higher in plans based on hybrid images, compared to the plans based on kVCT images alone. Likewise, the D35% for the rectum was 3% higher than the kVCT based plan for both hybrid and MVCT plans. The average difference in planned D99% in the PTV compared to kVCT plans was 0.9% and 0.1% for MVCT and hybrid plans, respectively. For the water tank with hip prostheses phantom, the kVCT plan with O-MAR correction applied showed better agreement between the measured and calculated dose than the original image set, with a difference of -1.9% compared to 3.3%. The measured doses for the MVCT plans were lower than the calculated dose due to image size limitations. The best agreement was for the kVCT/MVCT hybrid plans with the difference between calculated and measured dose around 1%. MVCT image provides better visualization of patient anatomy and hybrid kVCT/MVCT study enables more accurate calculations using updated MVCT relative electron density calibration.

  15. Estética en prótesis removibles The aesthetics in removable prostheses

    Directory of Open Access Journals (Sweden)

    LVM Lucas

    2010-06-01

    Full Text Available La estética actualmente recibe una importante consideración en el contexto social. Una sonrisa atractiva es aspiración de la mayoría de los pacientes que precisan tratamiento protésico. Los implantes propiciaron una mejoría significativa, con relación a las prótesis removibles, debido a su funcionalidad. El objetivo de este estudio fue explorar en la literatura científica moderna, a fin de hallar aspectos relacionados con la estética en la rehabilitación mediante prótesis removibles. Fueron encontrados factores importantes como: la selección de los dientes artificiales, la disposición de los mismos, la caracterización de la base de resina acrílica, además de los tipos de retenedores para las prótesis parciales removibles. La planificación y aplicación apropiada de este procedimiento, con criterios estéticos correctos, debe ser responsabilidad del profesional.Nowadays, aesthetics is very appreciated in the social context and a attractive smile is the object of desire in most of patients requiring prosthesis treatment. In case of removable prosthesis, total or partial, this feature is more significant since some or all teeth may be absents. Implants leading to a significant improvement in relation to function and comfort of removable prosthesis users, but the aesthetics of these prostheses had little attention in the current scientific literature. Thus, the aim of present article was to make a review of the literature on the aesthetic features related to rehabilitation with removable prostheses. In present study we found as significant factors for the aesthetics in removable partial and total prostheses: selection of artificial teeth and their arrangement, characterization of acrylic resin basis and also the types and location of retainers for the removable partial prostheses. We conclude that the involvement and the aesthetic knowledge during the appropriate planning of this process is responsibility of the professional.

  16. Early rehabilitation of facial defects using interim removable prostheses: A clinical case report

    Directory of Open Access Journals (Sweden)

    Vivekanandhan Ramkumar

    2013-01-01

    Full Text Available Surgical resection of neoplasms or malformations of the face may result in defects that are not amenable to immediate surgical reconstruction. Such defects can have a severe adverse effect on patient perceptions of body image and self-esteem. In these cases, the use of an interim removable facial prosthesis can offer a rapid alternative treatment solution. The patient may then resume social interactions more comfortably while permitting easy access to the facial defect to observe tissue healing while awaiting definitive rehabilitation. This article presents a case report describing the use of interim nasal prostheses to provide rapid patient rehabilitation of facial defects.

  17. IMPROVED HEALING OF SMALL-CALIBER POLYTETRAFLUOROETHYLENE PROSTHESES BY INDUCTION OF A CLOT LAYER - A REVIEW OF EXPERIMENTAL STUDIES IN RATS

    NARCIS (Netherlands)

    VANDERLEI, B; STRONCK, JW; WILDEVUUR, CRH

    1991-01-01

    This report reviews our experiments that have been undertaken to test the hypothesis whether the induction of a clot layer on the graft surface of small-caliber polytetrafluoroethylene ( PTFE) prostheses might improve their healing. 1 2 PTFE prostheses with a fibril length of 30-mu-m, PTFE

  18. A label-free luminescent switch-on assay for ATP using a G-quadruplex-selective iridium(III) complex.

    Science.gov (United States)

    Leung, Ka-Ho; Lu, Lihua; Wang, Modi; Mak, Tsun-Yin; Chan, Daniel Shiu-Hin; Tang, Fung-Kit; Leung, Chung-Hang; Kwan, Hiu-Yee; Yu, Zhiling; Ma, Dik-Lung

    2013-01-01

    We report herein the G-quadruplex-selective property of a luminescent cyclometallated iridium(III) complex for the detection of adenosine-5'-triphosphate (ATP) in aqueous solution. The ATP-binding aptamer was employed as the ATP recognition unit, while the iridium(III) complex was used to monitor the formation of the G-quadruplex structure induced by ATP. The sensitivity and fold enhancement of the assay were higher than those of the previously reported assay using the organic dye crystal violet as a fluorescent probe. This label-free luminescent switch-on assay exhibits high sensitivity and selectivity towards ATP with a limit of detection of 2.5 µM.

  19. A label-free luminescent switch-on assay for ATP using a G-quadruplex-selective iridium(III complex.

    Directory of Open Access Journals (Sweden)

    Ka-Ho Leung

    Full Text Available We report herein the G-quadruplex-selective property of a luminescent cyclometallated iridium(III complex for the detection of adenosine-5'-triphosphate (ATP in aqueous solution. The ATP-binding aptamer was employed as the ATP recognition unit, while the iridium(III complex was used to monitor the formation of the G-quadruplex structure induced by ATP. The sensitivity and fold enhancement of the assay were higher than those of the previously reported assay using the organic dye crystal violet as a fluorescent probe. This label-free luminescent switch-on assay exhibits high sensitivity and selectivity towards ATP with a limit of detection of 2.5 µM.

  20. A theoretically-guided optimization of a new family of modular P,S-ligands for iridium-catalyzed hydrogenation of minimally functionalized olefins.

    Science.gov (United States)

    Margalef, Jèssica; Caldentey, Xisco; Karlsson, Erik A; Coll, Mercè; Mazuela, Javier; Pàmies, Oscar; Diéguez, Montserrat; Pericàs, Miquel A

    2014-09-15

    A library of modular iridium complexes derived from thioether-phosphite/phosphinite ligands has been evaluated in the asymmetric iridium-catalyzed hydrogenation of minimally functionalized olefins. The modular ligand design has been shown to be crucial in finding highly selective catalysts for each substrate. A DFT study of the transition state responsible for the enantiocontrol in the Ir-catalyzed hydrogenation is also described and used for further optimization of the crucial stereodefining moieties. Excellent enantioselectivities (enantiomeric excess (ee) values up to 99 %) have been obtained for a range of substrates, including E- and Z-trisubstituted and disubstituted olefins, α,β-unsaturated enones, tri- and disubstituted alkenylboronic esters, and olefins with trifluoromethyl substituents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Tuning solid state luminescent properties in a hydrogen bonding-directed supramolecular assembly of bis-cyclometalated iridium(III) ethylenediamine complexes.

    Science.gov (United States)

    Talarico, Anna Maria; Szerb, Elisabeta Ildyko; Mastropietro, Teresa F; Aiello, Iolinda; Crispini, Alessandra; Ghedini, Mauro

    2012-04-28

    Synthesis, crystal structural determination and photophysical properties of a series of heteroleptic cationic cyclometalated iridium(III) derivatives of general formula [(ppy)(2)Ir(en)]X (X = ClO(4)(-) (1), PF(6)(-) (2), Cl(-) (3), BPh(4)(-) (4)), are described. The assembly of the common molecular building block allows to get highly luminescent crystalline materials or to assemble poorly luminescent supramolecular channelled architectures, for which the additional contribution of oxygen quenching effects has been observed. Moreover, the high reproducibility of the preparations of the crystalline materials in their specific crystalline phases, makes the control of the supramolecular organization of photo-active iridium(III) complexes within the crystalline structures a useful synthetic procedure for the construction of highly luminescent materials. This journal is © The Royal Society of Chemistry 2012

  2. How good are our impressions? An audit of alginate impression quality in the production of removable prostheses.

    Science.gov (United States)

    Horwitz, Richard

    2014-05-01

    Impressions are taken regularly in practice giving vital information to the dental laboratory, but are there quality assurance systems in place to make sure that they are up to a sufficient standard? As dental professionals we have to appreciate that dental technicians can only work with the information given to them. This makes the skill of taking a good impression vital in order for us as clinicians to provide prostheses of good quality. This paper outlines an audit of alginate impressions and their quality in the making of removable prostheses. To record the quality of impression taking, and how one's own ability to critique an impression may differ from that of our colleagues.

  3. Dramatic Enhancement of Power Conversion Efficiency in Polymer Solar Cells by Conjugating Very Low Ratio of Triplet Iridium Complexes to PTB7.

    Science.gov (United States)

    Qian, Min; Zhang, Ran; Hao, Jingyu; Zhang, Wenjun; Zhang, Qin; Wang, Jianpu; Tao, Youtian; Chen, Shufen; Fang, Junfeng; Huang, Wei

    2015-06-17

    Various low ratios of triplet iridium complexes (0, 0.5, 1, 1.5, 2.5, and 5 mol%) are conjugated to the backbone of the famous champion donor polymer PTB7. At the same conditions, the power conversion efficiency for polymer containing 1% of Ir increases by 45%, 39%, and 31% in three batches of devices compared with control Ir-free PTB7. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Iridium nanoparticles supported on hierarchical porous N-doped carbon: an efficient water-tolerant catalyst for bio-alcohol condensation in water

    OpenAIRE

    Liu, Di; Chen, Xiufang; Xu, Guoqiang; Guan, Jing; Cao, Quan; Dong, Bo; Qi, Yunfei; Li, Chunhu; Mu, Xindong

    2016-01-01

    Nitrogen-doped hierarchical porous carbons were synthesized successfully by a controllable one-pot method using glucose and dicyandiamide as carbon source and nitrogen source via hydrothermal carbonization process. The nitrogen-doped materials, possessing high nitrogen content (up to 7?wt%), large surface area (>320?m2 g?1) and excellent hierarchical nanostructure, were employed as catalyst supports for immobilization of iridium nanoparticles for bio-alcohol condensation in water. The introdu...

  5. A click chemistry approach to 5,5'-disubstituted-3,3'-bisisoxazoles from dichloroglyoxime and alkynes: luminescent organometallic iridium and rhenium bisisoxazole complexes.

    Science.gov (United States)

    van der Peet, Phillip L; Connell, Timothy U; Gunawan, Christian; White, Jonathan M; Donnelly, Paul S; Williams, Spencer J

    2013-07-19

    5,5'-Disubstituted-3,3'-bisisoxazoles are prepared in one step by the dropwise addition of aqueous potassium hydrogen carbonate to a mixture of dichloroglyoxime and terminal alkynes. The reaction exhibits a striking preference for the 5,5'-disubstituted 3,3'-bisisoxazole over the 4,5'-regioisomer. Organometallic iridium and rhenium bisisoxazole complexes are luminescent with emission wavelengths varying depending upon the identity of the 5,5'-substituent (phenyl, butyl).

  6. Evolvable Neural Software System

    Science.gov (United States)

    Curtis, Steven A.

    2009-01-01

    The Evolvable Neural Software System (ENSS) is composed of sets of Neural Basis Functions (NBFs), which can be totally autonomously created and removed according to the changing needs and requirements of the software system. The resulting structure is both hierarchical and self-similar in that a given set of NBFs may have a ruler NBF, which in turn communicates with other sets of NBFs. These sets of NBFs may function as nodes to a ruler node, which are also NBF constructs. In this manner, the synthetic neural system can exhibit the complexity, three-dimensional connectivity, and adaptability of biological neural systems. An added advantage of ENSS over a natural neural system is its ability to modify its core genetic code in response to environmental changes as reflected in needs and requirements. The neural system is fully adaptive and evolvable and is trainable before release. It continues to rewire itself while on the job. The NBF is a unique, bilevel intelligence neural system composed of a higher-level heuristic neural system (HNS) and a lower-level, autonomic neural system (ANS). Taken together, the HNS and the ANS give each NBF the complete capabilities of a biological neural system to match sensory inputs to actions. Another feature of the NBF is the Evolvable Neural Interface (ENI), which links the HNS and ANS. The ENI solves the interface problem between these two systems by actively adapting and evolving from a primitive initial state (a Neural Thread) to a complicated, operational ENI and successfully adapting to a training sequence of sensory input. This simulates the adaptation of a biological neural system in a developmental phase. Within the greater multi-NBF and multi-node ENSS, self-similar ENI s provide the basis for inter-NBF and inter-node connectivity.

  7. Biomechanical adaptations of transtibial amputee sprinting in athletes using dedicated prostheses.

    Science.gov (United States)

    Buckley, J G

    2000-06-01

    To determine the biomechanical adaptations of the prosthetic and sound limbs in two of the world's best transtibial amputee athletes whilst sprinting. Case study design, repeated measures. Using dedicated sprint prostheses transtibial amputees have run the 100 m in a little over 11 s. Lower-limb biomechanics when using such prostheses have not previously been investigated. Moments, muscle powers and the mechanical work done at the joints of the prosthetic and sound limbs were calculated as subjects performed repeated maximal sprint trials using a Sprint Flex or Cheetah prosthesis. An increased hip extension moment on the prosthetic limb, with an accompanying increase in the amount of concentric work done, was the most notable adaptation in Subject 1 using either prosthesis. In Subject 2, an increased extension moment at the residual knee, and an accompanying increase in the amount of total work done, was the most notable adaptation using either prosthesis. This later adaptation was also evident in Subject 1 when using his Sprint Flex prosthesis. Increased hip work on the prosthetic limb has previously been shown to be the major compensatory mechanism that allow transtibial amputees to run. The increased work found at the residual knee, suggests that the two amputee sprinters used an additional compensatory mechanism. These findings provide an insight into the biomechanical adaptations that allow a transtibial amputee to attain the speeds achieved when sprinting.

  8. Photoelastic Measurements of Polymer Insert Stress in the Knee Prostheses Designed for High/Deep Flexion

    Directory of Open Access Journals (Sweden)

    A. Lawi

    2010-01-01

    Full Text Available This paper presents the experimental results of photoelasticity for determining the magnitude and distribution of stresses on the polyethylene insert of the knee prostheses designed for high/deep knee flexion. The prostheses used in our experiment were a conventional posterior stabiliser knee, Scorpio NRG (Non-Restricted Geometry, Stryker Co., USA and CFK (Complete Flexion Knee, Japan Medical Material Co., Japan, which we have developed to enable the patient to make a complete knee flexion (i.e. seiza in Japanese. Prior to the photoelastic experiment, we had introduced the forces exerted on the knee joint during ascending from deep knee flexion. Here we took squatting as an example of deep knee flexion instead of seiza because ascending from seiza contains complex modalities. The introduced data in terms of knee angles and joint forces were applied to the photoelastic models. The results demonstrated that after the knee angle became larger than 90°, the shear stresses on the post and cam of NRG were higher than those on the ball and socket of CFK. We conclude that the design and the configuration of CFK is acceptable at deep knee flexion from a load-bearing viewpoint.

  9. Electromyography data for non-invasive naturally-controlled robotic hand prostheses

    Science.gov (United States)

    Atzori, Manfredo; Gijsberts, Arjan; Castellini, Claudio; Caputo, Barbara; Hager, Anne-Gabrielle Mittaz; Elsig, Simone; Giatsidis, Giorgio; Bassetto, Franco; Müller, Henning

    2014-01-01

    Recent advances in rehabilitation robotics suggest that it may be possible for hand-amputated subjects to recover at least a significant part of the lost hand functionality. The control of robotic prosthetic hands using non-invasive techniques is still a challenge in real life: myoelectric prostheses give limited control capabilities, the control is often unnatural and must be learned through long training times. Meanwhile, scientific literature results are promising but they are still far from fulfilling real-life needs. This work aims to close this gap by allowing worldwide research groups to develop and test movement recognition and force control algorithms on a benchmark scientific database. The database is targeted at studying the relationship between surface electromyography, hand kinematics and hand forces, with the final goal of developing non-invasive, naturally controlled, robotic hand prostheses. The validation section verifies that the data are similar to data acquired in real-life conditions, and that recognition of different hand tasks by applying state-of-the-art signal features and machine-learning algorithms is possible. PMID:25977804

  10. Comparison of mechanical energy profiles of passive and active below-knee prostheses: a case study.

    Science.gov (United States)

    Takahashi, Kota Z; Horne, John R; Stanhope, Steven J

    2015-04-01

    With the recent technological advancements of prosthetic lower limbs, there is currently a great desire to objectively evaluate existing prostheses. Using a novel biomechanical analysis, the purpose of this case study was to compare the mechanical energy profiles of anatomical and two disparate prostheses: a passive prosthesis and an active prosthesis. An individual with a transtibial amputation who customarily wears a passive prosthesis (Elation, Össur) and an active prosthesis (BiOM, iWalk, Inc.) and 11 healthy subjects participated in an instrumented gait analysis. The total mechanical power and work of below-knee structures during stance were quantified using a unified deformable segment power analysis. Active prosthesis generated greater peak power and total positive work than passive prosthesis and healthy anatomical limbs. The case study will enhance future efforts to objectively evaluate prosthetic functions during gait in individuals with transtibial amputations. A prosthetic limb should closely replicate the mechanical energy profiles of anatomical limbs. The unified deformable (UD) analysis may be valuable to facilitate future clinical prescription and guide fine adjustments of prosthetic componentry to optimize gait outcomes. © The International Society for Prosthetics and Orthotics 2014.

  11. Electromyographic evaluation of mastication and swallowing in elderly individuals with mandibular fixed implant-supported prostheses

    Directory of Open Access Journals (Sweden)

    Giédre Berretin-Felix

    2008-04-01

    Full Text Available This study evaluated the effect of implant-supported oral rehabilitation in the mandible on the electromyographic activity during mastication and swallowing in edentulous elderly individuals. Fifteen patients aged more than 60 years were evaluated, being 10 females and 5 males. All patients were edentulous, wore removable complete dentures on both dental arches, and had the mandibular dentures replaced by implant-supported prostheses. All patients were submitted to electromyographic evaluation of the masseter, superior orbicularis oris muscles, and the submental muscles, before surgery and 3, 6 and 18 months postoperatively, using foods of different textures. The results obtained at the different periods were analyzed statistically by Kruskal-Wallis non-parametric test. Statistical analysis showed that only the masseter muscle had a significant loss in electromyographic activity (p<0.001, with a tendency of similar response for the submental muscles. Moreover, there was an increase in the activity of the orbicularis oris muscle during rubber chewing after treatment, yet without statistically significant difference. Mandibular fixed implant-supported prostheses in elderly individuals revealed a decrease in electromyographic amplitude for the masseter muscles during swallowing, which may indicate adaptation to new conditions of stability provided by fixation of the complete denture in the mandibular arch.

  12. Inducing repetitive action potential firing in neurons via synthesized photoresponsive nanoscale cellular prostheses.

    Science.gov (United States)

    Lu, Siyuan; Madhukar, Anupam

    2013-02-01

    Recently we reported an analysis that examined the potential of synthesized photovoltaic functional abiotic nanosystems (PVFANs) to modulate membrane potential and activate action potential firing in neurons. Here we extend the analysis to delineate the requirements on the electronic energy levels and the attendant photophysical properties of the PVFANs to induce repetitive action potential under continuous light, a capability essential for the proposed potential application of PVFANs as retinal cellular prostheses to compensate for loss of photoreceptors. We find that repetitive action potential firing demands two basic characteristics in the electronic response of the PVFANs: an exponential dependence of the PVFAN excited state decay rate on the membrane potential and a three-state system such that, following photon absorption, the electron decay from the excited state to the ground state is via intermediate state(s) whose lifetime is comparable to the refractory time following an action potential. In this study, the potential of synthetic photovoltaic functional abiotic nanosystems (PVFANs) is examined under continuous light to modulate membrane potential and activate action potential firing in neurons with the proposed potential application of PVFANs as retinal cellular prostheses. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Female-pitched sound-producing voice prostheses--initial experimental and clinical results.

    Science.gov (United States)

    van der Torn, M; Verdonck-de Leeuw, I M; Festen, J M; de Vries, M P; Mahieu, H F

    2001-10-01

    In order to improve voice quality in female laryngectomees and/or laryngectomees with a hypotonic pharyngo-oesophageal segment, a sound-producing voice prosthesis was designed. The new source of voice consists of either one or two bent silicone lips which perform an oscillatory movement driven by the expired pulmonary air that flows along the outward-striking lips through the tracheo-oesophageal shunt valve. Four different prototypes of this pneumatic sound source were evaluated in vitro and in two female laryngectomees, testing the feasibility and characteristics of this new mechanism for alternative alaryngeal voice production. In vivo evaluation included acoustic analyses of both sustained vowels and read-aloud prose, videofluoroscopy, speech rate, and registration of tracheal phonatory pressure and vocal intensity. The mechanism proved feasible and did not result in unacceptable airflow resistance. The average pitch of voice increased and clarity improved in female laryngectomees. Pitch regulation of this prosthetic voice is possible with sufficient modulation to avoid monotony. The quality of voice attained through the sound-producing voice prostheses depends on a patient's ability to let pulmonary air flow easily through the pharyngo-oesophageal segment without evoking the low-frequency mucosal vibrations that form the regular tracheo-oesophageal shunt voice. These initial experimental and clinical results provide directions for the future development of sound-producing voice prostheses. A single relatively long lip in a container with a rectangular lumen that hardly protrudes from the voice prosthesis may have the most promising characteristics.

  14. Development of finite element model for customized prostheses design for patient with pelvic bone tumor.

    Science.gov (United States)

    Iqbal, Taimoor; Shi, Lei; Wang, Ling; Liu, Yaxiong; Li, Dichen; Qin, Mian; Jin, Zhongmin

    2017-06-01

    The aim of this study was to design a hemi-pelvic prosthesis for a patient affected by pelvic sarcoma. To investigate the biomechanical functionality of the pelvis reconstructed with designed custom-made prosthesis, a patient-specific finite element model of whole pelvis with primary ligaments inclusive was constructed based on the computed tomography images of the patient. Then, a finite element analysis was performed to calculate and compare the stress distribution between the normal and implanted pelvis models when undergoing three different static conditions-both-leg standing, single-leg standing for the healthy and the affected one. No significant differences were observed in the stresses between the normal and reconstructed pelvis for both-leg standing, but 20%-40% larger stresses were predicted for the peak stress of the single-leg standing (affected side). Moreover, two- to threefold of peak stresses were predicted within the prostheses compared to that of the normal pelvis especially for single-leg standing case, however, still below the allowable fatigue limitation. The study on the load transmission functionality of prosthesis indicated that it is crucial to carry out finite element analysis for functional evaluation of the designed customized prostheses before three-dimensional printing manufacturing, allowing better understanding of the possible peak stresses within the bone as well as the implants for safety precaution. The finite element model can be equally applicable to other bone tumor model for biomechanical studying.

  15. Electromyography data for non-invasive naturally-controlled robotic hand prostheses.

    Science.gov (United States)

    Atzori, Manfredo; Gijsberts, Arjan; Castellini, Claudio; Caputo, Barbara; Hager, Anne-Gabrielle Mittaz; Elsig, Simone; Giatsidis, Giorgio; Bassetto, Franco; Müller, Henning

    2014-01-01

    Recent advances in rehabilitation robotics suggest that it may be possible for hand-amputated subjects to recover at least a significant part of the lost hand functionality. The control of robotic prosthetic hands using non-invasive techniques is still a challenge in real life: myoelectric prostheses give limited control capabilities, the control is often unnatural and must be learned through long training times. Meanwhile, scientific literature results are promising but they are still far from fulfilling real-life needs. This work aims to close this gap by allowing worldwide research groups to develop and test movement recognition and force control algorithms on a benchmark scientific database. The database is targeted at studying the relationship between surface electromyography, hand kinematics and hand forces, with the final goal of developing non-invasive, naturally controlled, robotic hand prostheses. The validation section verifies that the data are similar to data acquired in real-life conditions, and that recognition of different hand tasks by applying state-of-the-art signal features and machine-learning algorithms is possible.

  16. [Failure of zirconia-based prostheses on natural teeth and implants: focus on risk factors].

    Science.gov (United States)

    Dupont, N; Koenig, V; Vanheusden, A; Mainjot, A

    2014-01-01

    Cohesive fracture of the veneering ceramic (chipping) is the first cause of failure of zirconia-based prostheses on natural teeth and implants. Besides risk factors related to the material (thermal stresses generated during the manufacturing process, framework inappropriate design), there are some clinical risk factors, which can influence the restoration prognosis. Indeed, unfavorable occlusal relationships and/or the presence of parafunctions such as bruxism and clenching, which are frequent pathologies, engender significant overloading. A retrospective study was performed at the University Hospital Center (CHU) of Liege on 147 dental and implants prostheses, placed between May 2003 and January 2012. This study highlighted a significant correlation between chipping and the absence of an occlusal nightguard (p = 0.0048), the presence of a ceramic restoration as an antagonist (p = 0.013), the presence of occlusal parafunctions (p = 0.018), and the presence of implants as support of the restorations (p = 0.026). These results underline the importance of external stress and occlusal risk factors diagnosis, as the need to perform an occlusal nightguard to patients with parafunctions.

  17. Thermal-induced residual stresses affect the fractographic patterns of zirconia-veneer dental prostheses.

    Science.gov (United States)

    Belli, Renan; Petschelt, Anselm; Lohbauer, Ulrich

    2013-05-01

    Veneer fractures in dental zirconia-veneer prostheses are more frequent clinically than in conventional metal-ceramic systems. This is thought to be due to the increased residual stresses generated within the veneer during fabrication when zirconia is the infrastructure material. This investigation aimed to analyze the fractographic features of fractured zirconia-veneer dental crowns submitted to a load-to-failure test and to a more clinically relevant in vitro chewing simulation fatigue test. As-sintered and sandblasted zirconia copings were veneered with glass-ceramic with different coefficients of thermal expansion and cooled following two cooling rates, creating, this way, different levels of stresses within the veneer. Crowns with different thermal mismatch combinations and different cooling rates were hypothesized to present particular fracture patterns. A careful examination of >1000 scanning electron microscopy images of the fracture surfaces was conducted in search of characteristic fractographic markings of fracture mechanisms connected to the stress state of the veneer. Distinctive structural features could be observed between groups veneered with the two different glass-ceramics and between fractured crowns under static and cyclic loading. The presence/absence of residual stresses zones within the veneer have shown to play the major role in the fracture pattern of zirconia-veneer dental prostheses. For the fatigue crowns, the zirconia core was never exposed, either for sandblasted and as-sintered groups. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Clinical study on the success of posterior monolithic zirconia crowns and fixed dental prostheses: preliminary report

    Directory of Open Access Journals (Sweden)

    Merve Bankoğlu Güngör

    2017-09-01

    Full Text Available Objective: The purpose of this report was to present preliminary clinical results regarding the success rates and technical outcomes of posterior monolithic zirconia single tooth crowns (STs and fixed dental prostheses (FDPs. Materials and Method: Thirty-four patients received 43 posterior monolithic zirconia restorations as single tooth crowns (STs and/or fixed dental prostheses (FDPs, which were fabricated using a CAD-CAM (Computer Aided Design - Computer Aided Manufacturing system. At baseline and every 6 months, the restorations were examined for survival and technical outcomes. Success of the restorations was defined as the restoration remaining in situ, with no need for removal or replacement at follow-up visits. Technical outcomes were evaluated with a modified version of the United States Public Health Services criteria. Survival of restorations was estimated by using the Kaplan-Meier survival analysis. For each restoration, duration of follow-up was calculated from the time of placement to the date of its first failure. Results: After a mean observation period of 18.6 ± 3.9 months (between 8-24 months, cumulative survival rates were 86.7% and 92.3% for STs and FDPs, respectively. Technical evaluation revealed good marginal adaptation and crown contours; however, modifications were needed for shade and occlusion of restorations. Conclusion: These preliminary results revealed high survival rate and generally successful technical outcomes for posterior monolithic zirconia STs and FDPs.

  19. Mandibular flexure and its significance on implant fixed prostheses: a review.

    Science.gov (United States)

    Law, Constance; Bennani, Vincent; Lyons, Karl; Swain, Michael

    2012-04-01

    The aims of this review are to determine the effect of mandibular flexure on the "implant-framework system," and analyze the existing literature on the topic. A MEDLINE and PubMed search was conducted to identify any articles in English related to the topic published up to May 2010 using the search words "mandible,"dental implants,"dental impression technique,"jaw movement,"dental stress analysis," and "mechanical stress." The search identified 40 and 36 articles from MEDLINE and PubMed, respectively. Twenty articles met the inclusion criteria. Mandibular flexure is a multifactorial phenomenon, and the effect of the implant-framework system in this is unclear. Studies have focused mainly on the fully edentulous mandible. These have found that mandibular flexure should be taken into consideration when designing a prosthesis and have suggested that dividing the prosthesis at the symphysis region, or into multiple implant fixed dental prostheses, may minimize the effect of mandibular flexure on the implant prosthesis. At this time, no studies have investigated the effect of mandibular flexure on long-span, unilateral, implant fixed prostheses. The clinical significance of mandibular flexure on the success of dental implant treatment is at this time unclear, and further research is needed. © 2011 by the American College of Prosthodontists.

  20. Noncontact Capacitive Sensing-Based Locomotion Transition Recognition for Amputees With Robotic Transtibial Prostheses.

    Science.gov (United States)

    Zheng, Enhao; Wang, Qining

    2017-02-01

    Recent advancement of robotic transtibial prostheses can restore human ankle dynamics in different terrains. Automatic locomotion transitions of the prosthesis guarantee the amputee's safety and smooth motion. In this paper, we present a noncontact capacitive sensing-based approach for recognizing locomotion transitions of amputees with robotic transtibial prostheses. The proposed sensing system is designed with flexible printed circuit boards which solves the walking instability brought by our previous system when using robotic prosthesis and improves the recognition performance. Six transtibial amputees were recruited and performed tasks of ten locomotion transitions with the robotic prosthesis that we recently constructed. The capacitive sensing system was integrated on the prosthesis and worked in combination with on-prosthesis mechanical sensors. With the cascaded classification method, the proposed system achieved 95.8% average recognition accuracy by support vector machine (SVM) classifier and 94.9% accuracy by quadratic discriminant analysis (QDA) classifier. It could accurately recognize the upcoming locomotion modes from the stance phase of the transition steps. In addition, we proved that adding capacitance signals could significantly reduce recognition errors of the robotic prosthesis in locomotion transition tasks. Our study suggests that the fusion of capacitive sensing system and mechanical sensors is a promising alternative for controlling the robotic transtibial prosthesis.

  1. Consciousness and neural plasticity

    DEFF Research Database (Denmark)

    In contemporary consciousness studies the phenomenon of neural plasticity has received little attention despite the fact that neural plasticity is of still increased interest in neuroscience. We will, however, argue that neural plasticity could be of great importance to consciousness studies....... If consciousness is related to neural processes it seems, at least prima facie, that the ability of the neural structures to change should be reflected in a theory of this relationship "Neural plasticity" refers to the fact that the brain can change due to its own activity. The brain is not static but rather...... a dynamic entity, which physical structure changes according to its use and environment. This change may take the form of growth of new neurons, the creation of new networks and structures, and change within network structures, that is, changes in synaptic strengths. Plasticity raises questions about...

  2. Fuzzy and neural control

    Science.gov (United States)

    Berenji, Hamid R.

    1992-01-01

    Fuzzy logic and neural networks provide new methods for designing control systems. Fuzzy logic controllers do not require a complete analytical model of a dynamic system and can provide knowledge-based heuristic controllers for ill-defined and complex systems. Neural networks can be used for learning control. In this chapter, we discuss hybrid methods using fuzzy logic and neural networks which can start with an approximate control knowledge base and refine it through reinforcement learning.

  3. What Is Neural Plasticity?

    Science.gov (United States)

    von Bernhardi, Rommy; Bernhardi, Laura Eugenín-von; Eugenín, Jaime

    2017-01-01

    "Neural plasticity" refers to the capacity of the nervous system to modify itself, functionally and structurally, in response to experience and injury. As the various chapters in this volume show, plasticity is a key component of neural development and normal functioning of the nervous system, as well as a response to the changing environment, aging, or pathological insult. This chapter discusses how plasticity is necessary not only for neural networks to acquire new functional properties, but also for them to remain robust and stable. The article also reviews the seminal proposals developed over the years that have driven experiments and strongly influenced concepts of neural plasticity.

  4. Neural Systems Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — As part of the Electrical and Computer Engineering Department and The Institute for System Research, the Neural Systems Laboratory studies the functionality of the...

  5. A neural flow estimator

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur; Bruun, Erik

    1995-01-01

    is implemented using switched-current technique and is capable of estimating flow in the μl/s range. The neural estimator is built around a multiplierless neural network, containing 96 synaptic weights which are updated using the LMS1-algorithm. An experimental chip has been designed that operates at 5 V......This paper proposes a new way to estimate the flow in a micromechanical flow channel. A neural network is used to estimate the delay of random temperature fluctuations induced in a fluid. The design and implementation of a hardware efficient neural flow estimator is described. The system...

  6. Current approaches to model extracellular electrical neural microstimulation

    Directory of Open Access Journals (Sweden)

    Sébastien eJoucla

    2014-02-01

    Full Text Available Nowadays, high-density microelectrode arrays provide unprecedented possibilities to precisely activate spatially well-controlled central nervous system (CNS areas. However, this requires optimizing stimulating devices, which in turn requires a good understanding of the effects of microstimulation on cells and tissues. In this context, modeling approaches provide flexible ways to predict the outcome of electrical stimulation in terms of CNS activation. In this paper, we present state-of-the-art modeling methods with sufficient details to allow the reader to rapidly build numerical models of neuronal extracellular microstimulation. These include 1 the computation of the electrical potential field created by the stimulation in the tissue, and 2 the response of a target neuron to this field. Two main approaches are described: First we describe the classical hybrid approach that combines the finite element modeling of the potential field with the calculation of the neuron’s response in a cable equation framework (compartmentalized neuron models. Then, we present a whole finite element approach allows the simultaneous calculation of the extracellular and intracellular potentials, by representing the neuronal membrane with a thin-film approximation. This approach was previously introduced in the frame of neural recording, but has never been implemented to determine the effect of extracellular stimulation on the neural response at a sub-compartment level. Here, we show on an example that the latter modeling scheme can reveal important sub-compartment behavior of the neural membrane that cannot be resolved using the hybrid approach. The goal of this paper is also to describe in detail the practical implementation of these methods to allow the reader to easily build new models using standard software packages. These modeling paradigms, depending on the situation, should help build more efficient high-density neural prostheses for CNS rehabilitation.

  7. The Ball Welding Bar: A New Solution for the Immediate Loading of Screw-Retained, Mandibular Fixed Full Arch Prostheses.

    Science.gov (United States)

    Bacchiocchi, Danilo; Guida, Andrea

    2017-01-01

    To present a new intraoral welding technique, which can be used to manufacture screw-retained, mandibular fixed full-arch prostheses. Over a 4-year period, all patients with complete mandibular edentulism or irreparably compromised mandibular dentition, who will restore the masticatory function with a fixed mandibular prosthesis, were considered for inclusion in this study. The "Ball Welding Bar" (BWB) technique is characterised by smooth prosthetic cylinders, interconnected by means of titanium bars which are adjustable in terms of distance from ball terminals and are inserted in the rotating rings of the cylinders. All the components are welded and self-posing. Forty-two patients (18 males; 24 females; mean age 64.2 ± 6.7 years) were enrolled and 210 fixtures were inserted to support 42 mandibular screw-retained, fixed full-arch prostheses. After two years of loading, 2 fixtures were lost, for an implant survival rate of 97.7%. Five implants suffered from peri-implant mucositis and 3 implants for peri-implantitis. Three of the prostheses (3/42) required repair for fracture (7.1%): the prosthetic success was 92.9%. The BWB technique seems to represent a reliable technique for the fabrication of screw-retained mandibular fixed full-arch prostheses. This study was registered in the ISRCTN register with number ISRCTN71229338.

  8. The Ball Welding Bar: A New Solution for the Immediate Loading of Screw-Retained, Mandibular Fixed Full Arch Prostheses

    Directory of Open Access Journals (Sweden)

    Danilo Bacchiocchi

    2017-01-01

    Full Text Available Purpose. To present a new intraoral welding technique, which can be used to manufacture screw-retained, mandibular fixed full-arch prostheses. Methods. Over a 4-year period, all patients with complete mandibular edentulism or irreparably compromised mandibular dentition, who will restore the masticatory function with a fixed mandibular prosthesis, were considered for inclusion in this study. The “Ball Welding Bar” (BWB technique is characterised by smooth prosthetic cylinders, interconnected by means of titanium bars which are adjustable in terms of distance from ball terminals and are inserted in the rotating rings of the cylinders. All the components are welded and self-posing. Results. Forty-two patients (18 males; 24 females; mean age 64.2±6.7 years were enrolled and 210 fixtures were inserted to support 42 mandibular screw-retained, fixed full-arch prostheses. After two years of loading, 2 fixtures were lost, for an implant survival rate of 97.7%. Five implants suffered from peri-implant mucositis and 3 implants for peri-implantitis. Three of the prostheses (3/42 required repair for fracture (7.1%: the prosthetic success was 92.9%. Conclusions. The BWB technique seems to represent a reliable technique for the fabrication of screw-retained mandibular fixed full-arch prostheses. This study was registered in the ISRCTN register with number ISRCTN71229338.

  9. Antibacterial Efficacy of a New Gentamicin-Coating for Cementless Prostheses Compared to Gentamicin-Loaded Bone Cement

    NARCIS (Netherlands)

    Neut, Danielle; Dijkstra, Rene J. B.; Thompson, Jonathan I.; van der Mei, Henny C.; Busscher, Henk J.

    2011-01-01

    Cementless prostheses are increasingly popular but require alternative prophylactic measures than the use of antibiotic-loaded bone cements. Here, we determine the 24-h growth inhibition of gentamicin-releasing coatings from grit-blasted and porous-coated titanium alloys, and compare their

  10. Interference in adhesion of bacteria and yeasts isolated from explanted voice prostheses to silicone rubber by rhamnolipid biosurfactants

    NARCIS (Netherlands)

    Rodrigues, LR; Banat, IM; van der Mei, HC; Teixeira, JA; Oliveira, R

    Aims: The effects and extent of adhesion of four different bacterial and two yeast strains isolated from explanted voice prostheses to silicone rubber with and without an adsorbed rhamnolipid biosurfactant layer obtained from Pseudomonasaeruginosa DS10-129 was studied. Methods and Results: The

  11. In vitro and in vivo microbial adhesion and growth on argon plasma-treated silicone rubber voice prostheses

    NARCIS (Netherlands)

    Everaert, EPJM; Van de Belt-Gritter, B; Van der Mei, HC; Busscher, HJ; Verkerke, GJ; Dijk, F; Mahieu, HF; Reitsma, A

    Patients who undergo a total laryngectomy usually receive a silicone rubber voice prosthesis for voice rehabilitation. Unfortunately, biofilm formation on the esophageal side of voice prostheses limits their lifetime to 3-4 mon on average. The effects of repeated argon plasma treatment of medical

  12. Comparison of a saliva wetness tester and a moisture-checking device in patients with maxillary obturator prostheses.

    Science.gov (United States)

    Murakami, Mamoru; Nishi, Yasuhiro; Kamashita, Yuji; Nagaoka, Eiichi

    2014-06-01

    Examination of dry mouth in postoperative oral tumour patients should ideally be performed simply and quickly at the chair side. Moisture-checking devices and saliva wetness testers are available for such moisture measurement. Previous studies have reported that moisture-checking devices are useful to examine dry mouth in patients with maxillary obturator prostheses. However, because the measurement principles of saliva wetness testers differ from those of moisture-checking devices, diagnosis by the two devices may result in diagnostic disagreement. The purpose of the present study was to compare the usefulness of a saliva wetness tester with a moisture-checking device for patients with maxillary obturator prostheses. Oral moisture was measured with a moisture-checking device and a saliva wetness tester in 30 subjects with maxillary obturator prostheses. These measurements were performed five times at the lingual mucosa, and mean values of each measurement were calculated. The reference value for moisture measurements with the moisture-checking device was 29%, and that with the saliva wetness tester was 3 mm. Subjects were classified as having dry mouth when their moisture measurements were less than the reference values. The diagnostic results of the saliva wetness tester were in agreement with those of the moisture-checking device. The respective moisture measurements showed a significant positive correlation (r=0.88, ptesters are as useful as moisture-checking devices to examine dry mouth in patients with maxillary obturator prostheses. © 2013 The Gerodontology Society and John Wiley & Sons A/S.

  13. Sport prostheses and prosthetic adaptations for the upper and lower limb amputees : an overview of peer reviewed literature

    NARCIS (Netherlands)

    Bragaru, Mihai; Dekker, Rienk; Geertzen, Jan H. B.

    Background: Sport prostheses are used by both upper- and lower-limb amputees while participating in sports and other physical activities. Although the number of these devices has increased over the past decade, no overview of the peer reviewed literature describing them has been published

  14. [The conventional and the digital impression method for single-unit and multi-unit fixed dental prostheses

    NARCIS (Netherlands)

    Wiersema, E.J.; Kreulen, C.M.; Creugers, N.H.J.

    2013-01-01

    To manufacture single-unit and multi-unit fixed dental prostheses, an accurate cast is required. Casts can be obtained either by the conventional or the digital impression method. For both methods, dry tooth surfaces and a well exposed finish line of the tooth preparation are required. The

  15. Effect of treatment with fixed and removable dental prostheses. An oral health-related quality of life study

    DEFF Research Database (Denmark)

    Øzhayat, Esben Boeskov; Gotfredsen, Klaus

    2012-01-01

    and mastication. Additionally, the purpose of the study was to identify aspects of impairment and improvement that the treatments caused. Fixed dental prostheses treatment was performed in 200 patients and RDP treatment in 107 patients. Gender, age, region of replacement, and number of teeth present and replaced...

  16. Modeling and analysis of individual with lower extremity amputation locomotion using prosthetic feet and running-specific prostheses.

    Science.gov (United States)

    Murai, Akihiko; Hobara, Hiroaki; Hashizume, Satoru; Kobayashi, Yoshiyuki; Tada, Mitsunori

    2017-07-01

    Prostheses have enabled individuals with lower extremity amputation (ILEAs) to accomplish many daily activities. Prosthetic feet allow ILEA to locomote and improves their quality of life. Carbon-fiber running-specific prostheses (RSPs) with energy storing capabilities support ILEAs to perform sprinting by partly providing spring-like properties in their amputated legs. Previous studies declare the spring-like RSP behavior and stiffness regulation during ILEA sprinting using RSP, though little is known about the behavior of the whole system that is a complex combination of human body and prostheses. This paper models this combined system with human and prosthetic foot and RSP using the digital human technology, then, analyzes the ILEA walking using the prosthetic foot and sprinting using RSP. We develop models that are combinations of human and prostheses by individualizing a linkage structure and inertial parameters of the digital human model. Then, locomotion of ILEA is analyzed based on measurements with optical motion capture system and force plates, and kinematics and dynamics computation. This modeling and computational technique can be applied to the locomotion of ILEA as well as a human motion using tools, and expanded to an analysis and improvement of system involving human.

  17. [Determining and recording maxillomandibular relationships for the fabrication of single-unit and multi-unit fixed dental prostheses

    NARCIS (Netherlands)

    Wiersema, E.J.; Kreulen, C.M.; Baat, C. de; Witter, D.J.; Creugers, N.H.J.

    2013-01-01

    In a correctly functioning occlusal system, the design of the occlusal parts of single-unit and multi-unit fixed dental prostheses is generally determined by the maximum intercuspation. Determining and recording the maxillomandibular relationships is only required in case the adjacent teeth do not

  18. [A study on individual mandibular prostheses according to 3D reconstruction of CT images and CNC simulation method].

    Science.gov (United States)

    Pan, Liu-guo; Sun, Li-qun

    2007-03-01

    The new method of manufacturing individual mandibular prostheses, in combination with CT data and CNC technique, can duplicate bone tissues accurately, and can have the individual mandibular prosthesis made to order, and repair the mandibular defect (especially the lager mandibular segmental defect).

  19. The Reality of Myoelectric Prostheses: Understanding What Makes These Devices Difficult for Some Users to Control.

    Science.gov (United States)

    Chadwell, Alix; Kenney, Laurence; Thies, Sibylle; Galpin, Adam; Head, John

    2016-01-01

    Users of myoelectric prostheses can often find them difficult to control. This can lead to passive-use of the device or total rejection, which can have detrimental effects on the contralateral limb due to overuse. Current clinically available prostheses are "open loop" systems, and although considerable effort has been focused on developing biofeedback to "close the loop," there is evidence from laboratory-based studies that other factors, notably improving predictability of response, may be as, if not more, important. Interestingly, despite a large volume of research aimed at improving myoelectric prostheses, it is not currently known which aspect of clinically available systems has the greatest impact on overall functionality and everyday usage. A protocol has, therefore, been designed to assess electromyographic (EMG) skill of the user and predictability of the prosthesis response as significant parts of the control chain, and to relate these to functionality and everyday usage. Here, we present the protocol and results from early pilot work. A set of experiments has been developed. First, to characterize user skill in generating the required level of EMG signal, as well as the speed with which users are able to make the decision to activate the appropriate muscles. Second, to measure unpredictability introduced at the skin-electrode interface, in order to understand the effects of the socket-mounted electrode fit under different loads on the variability of time taken for the prosthetic hand to respond. To evaluate prosthesis user functionality, four different outcome measures are assessed. Using a simple upper limb functional task prosthesis users are assessed for (1) success of task completion, (2) task duration, (3) quality of movement, and (4) gaze behavior. To evaluate everyday usage away from the clinic, the symmetricity of their real-world arm use is assessed using activity monitoring. These methods will later be used to assess a prosthesis user cohort to

  20. [Results after replacement of femoral neck prostheses - thrust plate prosthesis (TPP) versus ESKA cut prosthesis].

    Science.gov (United States)

    Ishaque, B A; Gils, J; Wienbeck, S; Donle, E; Basad, E; Stürz, H

    2009-01-01

    The aim of this study was to analyse and evaluate comparatively loosening mechanisms, failure frequency, surgical changing strategies and results after replacement of thrust plate prostheses (TPP) and ESKA Cut prostheses. Between 1993 und 2007, 465 TPP and in the years 2000 and 2001 82 ESKA Cut prostheses were performed and evaluated prospectively. Until 2007 46 change interventions of the TPP and 35 of the CUT prosthesis became necessary. All patients who received a stem revision procedure in our hospital were included within this study. Besides the evaluation of clinical results according to the criteria of the Harris Hip Score on the average at 15.6 months (+/- 14.4) postoperatively, radiological loosening processes and surgical difficulties were registered. Furthermore, an analysis of perioperative data was performed according to some criteria of the German Federal Office of Quality Assurance (BQS), such as duration of the surgery, intraoperative blood loss and complications. Statistical investigations for comparative analysis as well as survival analysis of both groups were calculated using SPSS for Windows 13.0. The mean age of the 46 patients who had to undergo revision surgery after TPP was 60.1 years, that of 35 patients in whom revision surgery was necessary after receiving an ESKA Cut femoral neck stem was 56.6 years. The survival rate analysis according to Kaplan-Meier at 13 years was 89.4 % (TPP) and 53.6 % at 66 months (ESKA Cut). In all cases the partial osteointegration of the tripod surface of the loosened Cut prosthesis complicated the explantation. It led on the one hand to a significant difference of the surgery duration and on the other hand to an increased frequency of fractures of the trochanteric region. The conversion of the TPP on standard type stems was usually free of problems. The HHS increased significantly to the averages of 86.6 (TPP) or, respectively, 91.69 (ESKA Cut) after revision. In comparison with the usually problem

  1. Simulation of epiretinal prostheses - Evaluation of geometrical factors affecting stimulation thresholds

    Directory of Open Access Journals (Sweden)

    Bertsch Arnaud

    2011-08-01

    Full Text Available Abstract Background An accurate understanding of the electrical interaction between retinal prostheses and retinal tissue is important to design effective devices. Previous studies have used modelling approaches to simulate electric fields generated by epiretinal prostheses in saline and to simulate retinal ganglion cell (RGC activation using passive or/and active biophysical models of the retina. These models have limited scope for studying an implanted human retinal prosthesis as they often do not account for real geometry and composition of the prosthesis-retina interface. This interface consists of real dimensions and location of stimulation and ground electrodes that are separated by the retinal tissue and surrounded by physiological fluids. Methods In this study, we combined the prosthesis-retina interface elements into a framework to evaluate the geometrical factors affecting stimulation thresholds for epiretinal prostheses used in clinical human trials, as described by Balthasar et al. in their Investigative Ophthalmology and Visual Science (IOVS paper published in 2008 using the Argus I epiretinal implants. Finite element method (FEM based computations were used to estimate threshold currents based on a threshold criterion employing a passive electric model of the retina. Results Threshold currents and impedances were estimated for different electrode-retina distances. The profiles and the values for thresholds and impedances obtained from our simulation framework are within the range of measured values in the only elaborate published clinical trial until now using Argus I epiretinal implants. An estimation of resolution for the electrodes used in these trials was provided. Our results reiterate the importance of close proximity between electrodes and retina for safe and efficient retinal stimulation. Conclusions The validation of our simulation framework being relevant for epiretinal prosthesis research is derived from the good

  2. Simulation of epiretinal prostheses - evaluation of geometrical factors affecting stimulation thresholds.

    Science.gov (United States)

    Kasi, Harsha; Hasenkamp, Willyan; Cosendai, Gregoire; Bertsch, Arnaud; Renaud, Philippe

    2011-08-19

    An accurate understanding of the electrical interaction between retinal prostheses and retinal tissue is important to design effective devices. Previous studies have used modelling approaches to simulate electric fields generated by epiretinal prostheses in saline and to simulate retinal ganglion cell (RGC) activation using passive or/and active biophysical models of the retina. These models have limited scope for studying an implanted human retinal prosthesis as they often do not account for real geometry and composition of the prosthesis-retina interface. This interface consists of real dimensions and location of stimulation and ground electrodes that are separated by the retinal tissue and surrounded by physiological fluids. In this study, we combined the prosthesis-retina interface elements into a framework to evaluate the geometrical factors affecting stimulation thresholds for epiretinal prostheses used in clinical human trials, as described by Balthasar et al. in their Investigative Ophthalmology and Visual Science (IOVS) paper published in 2008 using the Argus I epiretinal implants. Finite element method (FEM) based computations were used to estimate threshold currents based on a threshold criterion employing a passive electric model of the retina. Threshold currents and impedances were estimated for different electrode-retina distances. The profiles and the values for thresholds and impedances obtained from our simulation framework are within the range of measured values in the only elaborate published clinical trial until now using Argus I epiretinal implants. An estimation of resolution for the electrodes used in these trials was provided. Our results reiterate the importance of close proximity between electrodes and retina for safe and efficient retinal stimulation. The validation of our simulation framework being relevant for epiretinal prosthesis research is derived from the good agreement of the computed trends and values of the current study with

  3. The reality of myoelectric prostheses: Understanding what makes these devices difficult for some users to control

    Directory of Open Access Journals (Sweden)

    Alix Chadwell

    2016-08-01

    Full Text Available Users of myoelectric prostheses can often find them difficult to control. This can lead to passive-use of the device or total rejection, which can have detrimental effects on the contralateral limb due to overuse.Current clinically available prostheses are ‘open loop’ systems, and although considerable effort has been focused on developing biofeedback to close the loop, there is evidence from laboratory-based studies that other factors, notably improving predictability of response, may be as, if not more, important. Interestingly, despite a large volume of research aimed at improving myoelectric prostheses, it is not currently known which aspect of clinically available systems has the greatest impact on overall functionality and everyday usage. A protocol has therefore been designed to assess EMG skill of the user and predictability of the prosthesis response as significant parts of the control chain, and to relate these to functionality and everyday usage. Here we present the protocol and results from early pilot work.A set of experiments has been developed. Firstly to characterize user skill in generating the required level of EMG signal, as well as the speed with which users are able to make the decision to activate the appropriate muscles. Secondly, to measure unpredictability introduced at the skin-electrode interface, in order to understand the effects of the socket mounted electrode fit under different loads on the variability of time taken for the prosthetic hand to respond.To evaluate prosthesis user functionality, four different outcome measures are assessed. Using a simple upper limb functional task prosthesis users are assessed for (1 success of task completion, (2 task duration, (3 quality of movement, and (4 gaze behavior. To evaluate everyday usage away from the clinic, the symmetricity of their real-world arm use is assessed using activity monitoring.These methods will later be used to assess a prosthesis user cohort, to

  4. Implant loading protocols for edentulous patients with fixed prostheses: a systematic review and meta-analysis.

    Science.gov (United States)

    Papaspyridakos, Panos; Chen, Chun-Jung; Chuang, Sung-Kiang; Weber, Hans-Peter

    2014-01-01

    To report on the effect of immediate implant loading with fixed prostheses compared to early and conventional loading on implant and prosthesis survival, failure, and complications. An electronic and manual search was conducted to identify randomized controlled clinical trials (RCTs) as well as prospective and retrospective studies involving rough surface implants and implant fixed complete dental prostheses for edentulous patients. The 62 studies that fulfilled the inclusion criteria featured 4 RCTs, 2 prospective case-control studies, 34 prospective cohort studies, and 22 retrospective cohort studies. These studies yielded data from 2,695 patients (2,757 edentulous arches) with 13,653 implants. Studies were grouped according to the loading protocol applied; 45 studies reported on immediate loading, 8 on early loading, and 11 on conventional loading. For the immediate loading protocol with flap surgery, the implant and prosthesis survival rates ranged from 90.1% to 100% and 93.75% to 100%, respectively (range of follow-up, 1 to 10 years). When immediate loading was combined with guided flapless implant placement, the implant survival rates ranged from 90% to 99.4%. For the early loading protocol, the implant and prosthesis survival rates ranged from 94.74% to 100% and 93.75% to 100%, respectively (range of follow-up, 1 to 10 years). For the conventional loading protocol, the implant and prosthesis survival rates ranged from 94.95% to 100% and 87.5% to 100%, respectively (range of follow-up, 2 to 15 years). No difference was identified between maxilla and mandible. When selecting cases carefully and using dental implants with a rough surface, immediate loading with fixed prostheses in edentulous patients results in similar implant and prosthesis survival and failure rates as early and conventional loading. For immediate loading, most of the studies recommended a minimal insertion torque of 30 Ncm. The estimated 1-year implant survival was above 99% with all three

  5. Neural Networks: Implementations and Applications

    NARCIS (Netherlands)

    Vonk, E.; Veelenturf, L.P.J.; Jain, L.C.

    1996-01-01

    Artificial neural networks, also called neural networks, have been used successfully in many fields including engineering, science and business. This paper presents the implementation of several neural network simulators and their applications in character recognition and other engineering areas

  6. Studying the glial cell response to biomaterials and surface topography for improving the neural electrode interface

    Science.gov (United States)

    Ereifej, Evon S.

    grown on PMMA resembled closely to that of cells grown on the control surface, thus confirming the biocompatibility of PMMA. Additionally, the astrocyte GFAP gene expressions of cells grown on PMMA were lower than the control, signifying a lack of astrocyte reactivity. Based on the findings from the biomaterials study, it was decided to optimize PMMA by changing the surface characteristic of the material. Through the process of hot embossing, nanopatterns were placed on the surface in order to test the hypothesis that nanopatterning can improve the cellular response to the material. Results of this study agreed with current literature showing that topography effects protein and cell behavior. It was concluded that for the use in neural electrode fabrication and design, the 3600mm/gratings pattern feature sizes were optimal. The 3600 mm/gratings pattern depicted cell alignment along the nanopattern, less protein adsorption, less cell adhesion, proliferation and viability, inhibition of GFAP and MAP2k1 compared to all other substrates tested. Results from the initial biomaterials study also indicated platinum was negatively affected the cells and may not be a suitable material for neural electrodes. This lead to pursuing studies with iridium oxide and platinum alloy wires for the glial scar assay. Iridium oxide advantages of lower impedance and higher charge injection capacity would appear to make iridium oxide more favorable for neural electrode fabrication. However, results of this study demonstrate iridium oxide wires exhibited a more significant reactive response as compared to platinum alloy wires. Astrocytes cultured with platinum alloy wires had less GFAP gene expression, lower average GFAP intensity, and smaller glial scar thickness. Results from the nanopatterning PMMA study prompted a more thorough investigation of the nanopatterning effects using an organotypic brain slice model. PDMS was utilized as the substrate due to its optimal physical properties

  7. Microchip-Embedded Capacitors for Implantable Neural Stimulators

    Science.gov (United States)

    Auciello, Orlando

    Miniaturization of microchips for implantation in the human body (e.g., microchip for the artificial retina to restore sight to people blinded by retina photoreceptors degeneration) requires the integration of high-capacitance (≥ 10 μF) energy-storage capacitors into the microchip. These capacitors would be based on high-dielectric constant layers, preferably made of materials that are bioinert (not affected by human body fluids) and are biocompatible (do not elicit adverse reactions in the human body). This chapter focuses on reviewing the work being done at Argonne National Laboratory (Materials Science Division and Center for Nanoscale Materials) to develop high-capacitance microchip-embedded capacitors based on novel high-K dielectric layers (TiAlOx or TiO2/Al2O3 superlattices). The microchip-embedded capacitor provides energy storage and electromagnetic signal coupling needed for neural stimulations. Advances in neural prostheses such as artificial retinas and cochlear implants require miniaturization of device size to minimize tissue damage and improve device/tissue interfaces in the human body. Therefore, development of microchip-embedded capacitors is critical to achieve full-implantable biomedical device miniaturization.

  8. Diamonds from the iridium-rich K-T boundary layer at Arroyo el Mimbral, Tamaulipas, Mexico

    Science.gov (United States)

    Hough, R. M.; Gilmour, I.; Pillinger, C. T.; Langenhorst, F.; Montanari, A.

    1997-11-01

    Diamonds, up to 30 μm in size, were found in the iridium-rich layer from the K-T boundary site at Arroyo El Mimbral and the spherule bed from Arroyo El Peñon, northeastern Mexico. Stepped heating experiments indicate two or more isotopically distinct diamond components with carbon isotopic compositions characteristic of a mixture of carbon sources. The diamonds' crystal form is cubic—not the hexagonal polymorph of diamond, lonsdaleite, which has been used previously to infer formation due to shock transformation of graphite. The size, crystallography, and mineralogic associations of K-T diamonds are similar to those of impact-produced diamonds from the Ries crater in Germany where both shock transformation of graphite and a mode of formation by condensation from a vapor plume have been inferred. The discovery of impact-produced diamonds in association with high Ir contents for these sediments supports their impact origin, K-T age, and the inference that their source was from the buried impact crater of Chicxulub on the Yucatan peninsula, Mexico.

  9. Metallurgical Evaluation of Grit Blasted Versus Non-Grit Blasted Iridium Alloy Clad Vent Set Cup Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ulrich, George B [ORNL; Longmire, Hu Foster [ORNL

    2010-02-01

    Metallurgical evaluations were conducted to determine what, if any, grain size differences exist between grit blasted and non-grit blasted DOP-26 iridium alloy cup surfaces and if grit blasting imparts sufficient compressive cold work to induce abnormal grain growth during subsequent temperature exposures. Metallographic measurements indicated that grit blasting cold worked the outside cup surface to a depth of approximately 19 {micro}m. Subsequent processing through the air burn-off (635 C/4h) and vacuum outgassing (1250 C/1h) operations was found to uniformly recrystallize the cold worked surface to produce grains with an average diameter of approximately 8.5 {micro}m (American Society for Testing and Materials (ASTM) grain size number 11). Follow-on heat treatments at 1375 C, 1500 C, and 1900 C for durations ranging from 1 min to 70 h yielded uniform grain sizes and no abnormal grain growth from grit blasting. Abnormal grain growth was noted at the 1500 C and 1900 C heat treatments in areas of cold work from excessive clamping during sample preparation.

  10. Tuning the Emission of Cationic Iridium (III) Complexes Towards the Red Through Methoxy Substitution of the Cyclometalating Ligand

    Science.gov (United States)

    Hasan, Kamrul; Bansal, Ashu K.; Samuel, Ifor D.W.; Roldán-Carmona, Cristina; Bolink, Henk J.; Zysman-Colman, Eli

    2015-01-01

    The synthesis, characterization and evaluation in solid-state devices of a series of 8 cationic iridium complexes bearing different numbers of methoxy groups on the cyclometallating ligands are reported. The optoelectronic characterization showed a dramatic red shift in the absorption and the emission and a reduction of the electrochemical gap of the complexes when a methoxy group was introduced para to the Ir-C bond. The addition of a second or third methoxy group did not lead to a significant further red shift in these spectra. Emission maxima over the series ranged from 595 to 730 nm. All complexes possessing a motif with a methoxy group at the 3-position of the cyclometalating ligands showed very short emission lifetimes and poor photoluminescence quantum yields whereas complexes having a methoxy group at the 4-position were slightly blue shifted compared to the unsubstituted parent complexes, resulting from the inductively electron withdrawing nature of this directing group on the Ir-C bond. Light-emitting electrochemical cells were fabricated and evaluated. These deep red emitters generally showed poor performance with electroluminescence mirroring photoluminescence. DFT calculations accurately modelled the observed photophysical and electrochemical behavior of the complexes and point to an emission from a mixed charge transfer state. PMID:26179641

  11. Histidine-iridium(III) coordination-based peptide luminogenic cyclization and cyclo-RGD peptides for cancer-cell targeting.

    Science.gov (United States)

    Ma, Xiaochuan; Jia, Junli; Cao, Rui; Wang, Xiaobo; Fei, Hao

    2014-12-24

    In the field of peptide drug discovery, structural constraining and fluorescent labeling are two sought-after techniques important for both basic research and pharmaceutical development. In this work, we describe an easy-to-use approach for simultaneous peptide cyclization and luminescent labeling based on iridium(III)-histidine coordination (Ir-HH cyclization). Using a series of model peptides with histidine flanking each terminus, the binding activity and reaction kinetics of Ir-HH cyclization of different ring sizes were characterized. In the series, Ir-HAnH (n = 2, 3) with moderate ring sizes provides appropriate flexibility and proper distance between histidines for cyclic formation, which leads to the best binding affinity and structural stability in physiological conditions, as compared to other Ir-HH-cyclized peptides with smaller (n = 0, 1) or larger (n = 4, 5) ring sizes. Ir-HRGDH, an Ir-HH-cyclized peptide containing integrin targeting motif Arg-Gly-Asp (RGD), showed better targeting affinity than its linear form and enhanced membrane permeability in comparison with fluorescein-labeled cyclic RGDyK peptide. Cell death inducing peptide KLA-linked Ir-HRGDH (Ir-HRGDH-KLA) showed dramatically enhanced cytotoxicity and high selectivity for cancer cells versus noncancer cells. These data demonstrate that the method conveniently combines structural constraining of peptides with luminescent imaging capabilities, which facilitates functional and intracellular characterization of potential peptide-based drug leads, thus introducing a new tool to meet emerging needs in medicinal research.

  12. Effect of Trace Levels of Si on Microstructure and Grain Boundary Segregation in DOP-26 Iridium Alloy

    Science.gov (United States)

    Pierce, Dean; Muralidharan, Govindarajan; Heatherly, Lee; Fox, Ethan

    2017-10-01

    The thermodynamics and kinetics of Silicon (Si) segregation to grain boundaries in Iridium alloy DOP-26 with added trace levels of Si of 6, 11, 29, and 36 wppm was studied by Auger Electron Spectroscopy. The four alloys were annealed at 1500 or 1535 °C for 19 or 76 hours followed by cooling at three different rates. Si enrichment at the grain boundaries (GB) increased with increasing bulk Si content, with the grain boundary Si enrichment factors ranging from 62 to 344, depending on the bulk Si content and the cooling rate. Grain boundary Si contents increased with decreasing cooling rate in all alloys, indicating that Si GB segregation is influenced by both thermodynamic and kinetic factors in the alloys and temperature ranges of the study. A Langmuir-McLean isotherm-based model was successfully used to predict the temperature dependence of GB Si segregation in DOP-26 alloys with Si additions and estimate the temperature independent free energy of Si segregation to grain boundaries in DOP-26.

  13. Design and Synthesis of Pyrimidine-Based Iridium(III) Complexes with Horizontal Orientation for Orange and White Phosphorescent OLEDs.

    Science.gov (United States)

    Cui, Lin-Song; Liu, Yuan; Liu, Xiang-Yang; Jiang, Zuo-Quan; Liao, Liang-Sheng

    2015-05-27

    Two phosphorescent Ir(III) complexes Ir(ppm)2(acac) and Ir(dmppm)2(acac) were synthesized and characterized with emission ranged at 584/600 nm and high photoluminescence quantum yields (PLQYs) of 0.90/0.92, respectively. The angle-dependent PL spectra analysis reveals that the two orange iridium(III) complexes embodied horizontal orientation property. The high photoluminescence quantum yield and high horizontal dipoles ratio determine their excellent device performance. The devices based on Ir(ppm)2(acac) and Ir(dmppm)2(acac) achieved efficiencies of 26.8% and 28.2%, respectively, which can be comparable to the best orange phosphorescent devices reported in the literature. Furthermore, with the introduction of FIrpic as sky-blue emitter, phosphorescent two-element white organic light-emitting devices (OLEDs) have been realized with external quantum efficiencies (EQEs) as high as 25%, which are the highest values among the reported two-element white OLEDs.

  14. Iridium oxide pH sensor for biomedical applications. Case urea-urease in real urine samples.

    Science.gov (United States)

    Prats-Alfonso, Elisabet; Abad, Llibertat; Casañ-Pastor, Nieves; Gonzalo-Ruiz, Javier; Baldrich, Eva

    2013-01-15

    This work demonstrates the implementation of iridium oxide films (IROF) grown on silicon-based thin-film platinum microelectrodes, their utilization as a pH sensor, and their successful formatting into a urea pH sensor. In this context, Pt electrodes were fabricated on Silicon by using standard photolithography and lift-off procedures and IROF thin films were growth by a dynamic oxidation electrodeposition method (AEIROF). The AEIROF pH sensor reported showed a super-Nerstian (72.9±0.9mV/pH) response between pH 3 and 11, with residual standard deviation of both repeatability and reproducibility below 5%, and resolution of 0.03 pH units. For their application as urea pH sensors, AEIROF electrodes were reversibly modified with urease-coated magnetic microparticles (MP) using a magnet. The urea pH sensor provided fast detection of urea between 78μM and 20mM in saline solution, in sample volumes of just 50μL. The applicability to urea determination in real urine samples is discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Critical Branching Neural Networks

    Science.gov (United States)

    Kello, Christopher T.

    2013-01-01

    It is now well-established that intrinsic variations in human neural and behavioral activity tend to exhibit scaling laws in their fluctuations and distributions. The meaning of these scaling laws is an ongoing matter of debate between isolable causes versus pervasive causes. A spiking neural network model is presented that self-tunes to critical…

  16. Kunstige neurale net

    DEFF Research Database (Denmark)

    Hørning, Annette

    1994-01-01

    Artiklen beskæftiger sig med muligheden for at anvende kunstige neurale net i forbindelse med datamatisk procession af naturligt sprog, specielt automatisk talegenkendelse.......Artiklen beskæftiger sig med muligheden for at anvende kunstige neurale net i forbindelse med datamatisk procession af naturligt sprog, specielt automatisk talegenkendelse....

  17. A review of scalp camouflaging agents and prostheses for individuals with hair loss.

    Science.gov (United States)

    Donovan, Jeff C H; Shapiro, Ron L; Shapiro, Paul; Zupan, Matt; Pierre-Louis, Margareth; Hordinsky, Maria K

    2012-08-15

    Hair loss is a common problem for both men and women and may impact negatively on self-esteem. A variety of medical and surgical treatment options are available depending on the type of alopecia. Many patients also seek the advice of their physicians about options to hide or reduce the appearance of hair loss with hair prostheses (wigs, hairpieces, and extensions) or hair camouflaging agents (hair fibers, powder cakes, lotions, sprays, hair crayons, and scalp tattooing). Herein, we review current methods to hide or reduce the appearance of hair loss and discuss their associated costs, advantages, and disadvantages. Knowledge of products available to cover scalp, eyebrow, and eyelash hair loss may not only better equip clinicians to respond to questions from concerned patients, but may provide additional options to help these patients best cope with their hair loss.

  18. Sparse generalized volterra model of human hippocampal spike train transformation for memory prostheses.

    Science.gov (United States)

    Song, Dong; Robinson, Brian S; Hampson, Robert E; Marmarelis, Vasilis Z; Deadwyler, Sam A; Berger, Theodore W

    2015-01-01

    In order to build hippocampal prostheses for restoring memory functions, we build multi-input, multi-output (MIMO) nonlinear dynamical models of the human hippocampus. Spike trains are recorded from the hippocampal CA3 and CA1 regions of epileptic patients performing a memory-dependent delayed match-to-sample task. Using CA3 and CA1 spike trains as inputs and outputs respectively, second-order sparse generalized Laguerre-Volterra models are estimated with group lasso and local coordinate descent methods to capture the nonlinear dynamics underlying the spike train transformations. These models can accurately predict the CA1 spike trains based on the ongoing CA3 spike trains and thus will serve as the computational basis of the hippocampal memory prosthesis.

  19. Features and management of an acute allergic response to acrylic ocular prostheses.

    Science.gov (United States)

    Patel, Vikesh; Allen, David; Morley, Ana M S; Frcophth, Raman Malhotra

    2009-01-01

    To report the occurrence, causes and treatment of an acute allergic response to the acrylic resin used in ocular prostheses. Retrospective review of presenting history, clinical findings and treatment of two cases. Both patients developed an acute onset hypersensitivity reaction thought to be due to the acrylic resin found in the ocular prosthesis. The first patient was successfully switched to a glass eye. The prosthesis of the second patient was treated with an extra long curing cycle, after which, the patient was able to tolerate their prosthesis with no complications. The residual unpolymerized monomer that is present within poly-methylmethacrylate (PMMA) can rarely cause an allergic reaction. As an alternative to a glass eye the prosthesis may be subjected to an extended curing cycle converting more of the monomer to polymer.

  20. Development and evaluation of new coupling system for lower limb prostheses with acoustic alarm system.

    Science.gov (United States)

    Eshraghi, Arezoo; Osman, Noor Azuan Abu; Gholizadeh, Hossein; Ahmadian, Jalil; Rahmati, Bizhan; Abas, Wan Abu Bakar Wan

    2013-01-01

    Individuals with lower limb amputation need a secure suspension system for their prosthetic devices. A new coupling system was developed that is capable of suspending the prosthesis. The system's safety is ensured through an acoustic alarm system. This article explains how the system works and provides an in vivo evaluation of the device with regard to pistoning during walking. The system was designed to be used with silicone liners and is based on the requirements of prosthetic suspension systems. Mechanical testing was performed using a universal testing machine. The pistoning during walking was measured using a motion analysis system. The new coupling device produced significantly less pistoning compared to a common suspension system (pin/lock). The safety alarm system would buzz if the suspension was going to fail. The new coupling system could securely suspend the prostheses in transtibial amputees and produced less vertical movement than the pin/lock system.