The Experts below are selected from a list of 1071 Experts worldwide ranked by ideXlab platform

L M Jennings - One of the best experts on this subject based on the ideXlab platform.

  • the influence of malalignment and ageing following Sterilisation by gamma irradiation in an inert atmosphere on the wear of ultra high molecular weight polyethylene in patellofemoral replacements
    Proceedings of the Institution of Mechanical Engineers Part H: Journal of Engineering in Medicine, 2017
    Co-Authors: Raman Maiti, Raelene M Cowie, J. Fisher, L M Jennings
    Abstract:

    Complications of patellofemoral arthroplasty often occur soon after implantation and, as well as other factors, can be due to the design of the implant or its surgical positioning. A number of studies have previously considered the wear of ultra-high-molecular-weight polyethylene patellae following suboptimal implantation; however, studies have primarily been carried out under a limited number of degrees of freedom. The aim of this study was to develop a protocol to assess the wear of patellae under a malaligned condition in a six-axis patellofemoral joint simulator. The malalignment protocol hindered the tracking of the patella centrally in the trochlear groove and imparted a constant 5 external rotation (tilt) on the patella button. Following 3 million cycles of wear simulation, this condition had no influence on the wear of ultra-high-molecular-weight polyethylene patellae aged for 4 years compared to well-positioned non-aged implants (p . 0.05). However, under the malaligned condition, ultra-high-molecular-weight polyethylene patellae aged 8–10 years after unpacking (following Sterilisation by gamma irradiation in an inert atmosphere) and worn ultra-high-molecularweight polyethylene components also aged 4 years after unpacking (following the same Sterilisation Process) exhibited a high rate of wear. Fatigue failure due to elevated contact stress led to delamination of the ultra-high-molecular-weight polyethylene and in some cases complete failure of the patellae. The results suggest that suboptimal tracking of the patella in the trochlear groove and tilt of the patella button could have a significant effect on the wear of ultra-high-molecular-weight polyethylene and could lead to implant failure.

  • The influence of malalignment and ageing following Sterilisation by gamma irradiation in an inert atmosphere on the wear of ultra-high-molecular-weight polyethylene in patellofemoral replacements
    SAGE Publications, 2017
    Co-Authors: Maiti R, Rm Cowie, Fisher J, L M Jennings
    Abstract:

    Complications of patellofemoral arthroplasty often occur soon after implantation and, as well as other factors, can be due to the design of the implant or its surgical positioning. A number of studies have previously considered the wear of ultra-high-molecular-weight polyethylene patellae following suboptimal implantation; however, studies have primarily been carried out under a limited number of degrees of freedom. The aim of this study was to develop a protocol to assess the wear of patellae under a malaligned condition in a six-axis patellofemoral joint simulator. The malalignment protocol hindered the tracking of the patella centrally in the trochlear groove and imparted a constant 5 degrees external rotation (tilt) on the patella button. Following 3 million cycles of wear simulation, this condition had no influence on the wear of ultra-high-molecular-weight polyethylene patellae aged for 4 years compared to well-positioned non aged implants (p > 0.05). However, under the malaligned condition, ultra high-molecular-weight polyethylene patellae aged 8–10 years after unpacking (following Sterilisation by gamma irradiation in an inert atmosphere) and worn ultra-high-molecularweight polyethylene components also aged 4 years after unpacking (following the same Sterilisation Process) exhibited a high rate of wear. Fatigue failure due to elevated contact stress led to delamination of the ultra-high-molecular weight polyethylene and in some cases complete failure of the patellae. The results suggest that suboptimal tracking of the patella in the trochlear groove and tilt of the patella button could have a significant effect on the wear of ultra-high-molecular-weight polyethylene and could lead to implant failure

Schöning, Michael J. - One of the best experts on this subject based on the ideXlab platform.

  • Towards a biosensor to monitor the Sterilisation efficiency of aseptic filling machines
    'Wiley', 2015
    Co-Authors: Oberländer Jan, Kirchner Patrick, Keusgen Michael, Bromm Alexander, Wendeler Luisa, Iken Heiko, Durán, Marlena Palomar, Greeff Anton, Schöning, Michael J.
    Abstract:

    Sterilisation Processes are compulsory in medicine, pharmacy, and food industries to prevent infections of consumers and microbiological contaminations of products. Monitoring the Sterilisation by conventional microbiological methods is time- and lab-consuming. To overcome this problem, in this work a novel biosensor has been proposed. The sensor enables a fast method to evaluate Sterilisation Processes. By means of thin-film technology the sensor's transducer structures in form of IDEs (interdigitated electrodes) have been fabricated on a silicon substrate. Physical characterisation of the developed sensor was done by AFM, SEM, and profilometry. Impedance analyses were conducted for the electrical characterisation. As microbiological layer spores of B. atrophaeus have been immobilised on the sensing structure; spores of this type are a well-known Sterilisation test organism. Impedance measurements at a fixed frequency over time were performed to monitor the immobilisation Process. A Sterilisation Process according to aseptic filling machines was applied to demonstrate the sensor functionality. After both, immobilisation and Sterilisation, a change in impedance could successfully be detected

  • Multiple sensor-type system for monitoring the microbicidal effectiveness of aseptic Sterilisation Processes
    Elsevier Science, 2015
    Co-Authors: Reisert S, Geissler H, Weiler C, Wagner P., Schöning, Michael J.
    Abstract:

    The present work describes a novel multiple sensor-type system for the real-time analysis of aseptic Sterilisation Processes employing gaseous hydrogen peroxide (H2O2) as a sterilant. The inactivation kinetics of Bacillus atrophaeus by gaseous H2O2 have been investigated by means of a methodical calibration experiment, taking into account the Process variables H2O2 concentration, humidity and gas temperature. It has been found that the microbicidal effectiveness at H2O2 concentrations above 2% v/v is largely determined by the concentration itself, while at lower H2O2 concentrations, the gas temperature and humidity play a leading role. Furthermore, the responses of different types of gas sensors towards the influencing factors of the Sterilisation Process have been analysed within the same experiment. Based on a correlation established between the inactivation kinetics and the sensor responses, a calorimetric H2O2 sensor and a metal-oxide semiconductor (MOX) sensor have been identified as possible candidates for monitoring the microbicidal effectiveness of aseptic Sterilisation Processes employing gaseous H2O2. Therefore, two linear models that describe the relationship between sensor response and microbicidal effectiveness have been proposed

  • Monitoring the microbicidal effectiveness of gaseous hydrogen peroxide in Sterilisation Processes by means of a calorimetric gas sensor.
    Elsevier Science, 2013
    Co-Authors: Kirchner Patrick, Oberländer Jan, Suso Henri-pierre, Rysstad Gunnar, Keusgen Michael, Schöning, Michael J.
    Abstract:

    In the present work, a novel method for monitoring Sterilisation Processes with gaseous H2O2 in combination with heat activation by means of a specially designed calorimetric gas sensor was evaluated. Therefore, the Sterilisation Process was extensively studied by using test specimens inoculated with Bacillus atrophaeus spores in order to identify the most influencing Process factors on its microbicidal effectiveness. Besides the contact time of the test specimens with gaseous H2O2 varied between 0.2 and 0.5 s, the present H2O2 concentration in a range from 0 to 8% v/v (volume percent) had a strong influence on the microbicidal effectiveness, whereas the change of the vaporiser temperature, gas flow and humidity were almost negligible. Furthermore, a calorimetric H2O2 gas sensor was characterised in the Sterilisation Process with gaseous H2O2 in a wide range of parameter settings, wherein the measurement signal has shown a linear response against the H2O2 concentration with a sensitivity of 4.75 °C/(% v/v). In a final step, a correlation model by matching the measurement signal of the gas sensor with the microbial inactivation kinetics was established that demonstrates its suitability as an efficient method for validating the microbicidal effectiveness of Sterilisation Processes with gaseous H2O2

Woulfe Peter - One of the best experts on this subject based on the ideXlab platform.

  • Optical fbre based real‑time measurements during an LDR prostate brachytherapy implant simulation: using a 3D printed anthropomorphic phantom
    'The Nature Conservancy', 2021
    Co-Authors: Woulfe Peter, O\u27sullivan F. J., Byrne L., Doyle A. J., Kam W., Martyn Michael, O\u27keeffe S.
    Abstract:

    An optical fibre sensor based on radioluminescence, using the scintillation material terbium doped gadolinium oxysulphide (Gd2O2S:Tb) is evaluated, using a 3D printed anthropomorphic phantom for applications in low dose-rate (LDR) prostate brachytherapy. The scintillation material is embedded in a 700 µm diameter cavity within a 1 mm plastic optical fibre that is fixed within a brachytherapy needle. The high spatial resolution dosimeter is used to measure the dose contribution from Iodine-125 (I-125) seeds. Initially, the effects of Sterilisation on the sensors (1) repeatability, (2) response as a function of angle, and (3) response as a function of distance, are evaluated in a custom polymethyl methacrylate phantom. Results obtained in this study demonstrate that the output response of the sensor, pre- and post-Sterilisation are within the acceptable measurement uncertainty ranging from a maximum standard deviation of 4.7% pre and 5.5% post respectively, indicating that the low temperature Sterilisation Process does not damage the sensor or reduce performance. Subsequently, an LDR brachytherapy plan reconstructed using the VariSeed treatment planning system, in an anthropomorphic 3D printed training phantom, was used to assess the suitability of the sensor for applications in LDR brachytherapy. This phantom was printed based on patient anatomy, with the volume and dimensions of the prostate designed to represent that of the patient. I-125 brachytherapy seeds, with an average activity of 0.410 mCi, were implanted into the prostate phantom under transrectal ultrasound guidance; following the same techniques as employed in clinical practice by an experienced radiation oncologist. This work has demonstrated that this sensor is capable of accurately identifying when radioactive I-125 sources are introduced into the prostate via a brachytherapy needl

  • Optical fbre based real‑time measurements during an LDR prostate brachytherapy implant simulation: using a 3D printed anthropomorphic phantom
    'Springer Science and Business Media LLC', 2021
    Co-Authors: Woulfe Peter, Byrne L., Doyle A. J., Kam W., Martyn Michael, O'sullivan F. J., O'keeffe S.
    Abstract:

    peer-reviewedAn optical fibre sensor based on radioluminescence, using the scintillation material terbium doped gadolinium oxysulphide (Gd2O2S:Tb) is evaluated, using a 3D printed anthropomorphic phantom for applications in low dose-rate (LDR) prostate brachytherapy. The scintillation material is embedded in a 700 µm diameter cavity within a 1 mm plastic optical fibre that is fixed within a brachytherapy needle. The high spatial resolution dosimeter is used to measure the dose contribution from Iodine-125 (I-125) seeds. Initially, the effects of Sterilisation on the sensors (1) repeatability, (2) response as a function of angle, and (3) response as a function of distance, are evaluated in a custom polymethyl methacrylate phantom. Results obtained in this study demonstrate that the output response of the sensor, pre- and post-Sterilisation are within the acceptable measurement uncertainty ranging from a maximum standard deviation of 4.7% pre and 5.5% post respectively, indicating that the low temperature Sterilisation Process does not damage the sensor or reduce performance. Subsequently, an LDR brachytherapy plan reconstructed using the VariSeed treatment planning system, in an anthropomorphic 3D printed training phantom, was used to assess the suitability of the sensor for applications in LDR brachytherapy. This phantom was printed based on patient anatomy, with the volume and dimensions of the prostate designed to represent that of the patient. I-125 brachytherapy seeds, with an average activity of 0.410 mCi, were implanted into the prostate phantom under transrectal ultrasound guidance; following the same techniques as employed in clinical practice by an experienced radiation oncologist. This work has demonstrated that this sensor is capable of accurately identifying when radioactive I-125 sources are introduced into the prostate via a brachytherapy needl

Kirchner Patrick - One of the best experts on this subject based on the ideXlab platform.

  • Towards a biosensor to monitor the Sterilisation efficiency of aseptic filling machines
    'Wiley', 2015
    Co-Authors: Oberländer Jan, Kirchner Patrick, Keusgen Michael, Bromm Alexander, Wendeler Luisa, Iken Heiko, Durán, Marlena Palomar, Greeff Anton, Schöning, Michael J.
    Abstract:

    Sterilisation Processes are compulsory in medicine, pharmacy, and food industries to prevent infections of consumers and microbiological contaminations of products. Monitoring the Sterilisation by conventional microbiological methods is time- and lab-consuming. To overcome this problem, in this work a novel biosensor has been proposed. The sensor enables a fast method to evaluate Sterilisation Processes. By means of thin-film technology the sensor's transducer structures in form of IDEs (interdigitated electrodes) have been fabricated on a silicon substrate. Physical characterisation of the developed sensor was done by AFM, SEM, and profilometry. Impedance analyses were conducted for the electrical characterisation. As microbiological layer spores of B. atrophaeus have been immobilised on the sensing structure; spores of this type are a well-known Sterilisation test organism. Impedance measurements at a fixed frequency over time were performed to monitor the immobilisation Process. A Sterilisation Process according to aseptic filling machines was applied to demonstrate the sensor functionality. After both, immobilisation and Sterilisation, a change in impedance could successfully be detected

  • Monitoring the microbicidal effectiveness of gaseous hydrogen peroxide in Sterilisation Processes by means of a calorimetric gas sensor.
    Elsevier Science, 2013
    Co-Authors: Kirchner Patrick, Oberländer Jan, Suso Henri-pierre, Rysstad Gunnar, Keusgen Michael, Schöning, Michael J.
    Abstract:

    In the present work, a novel method for monitoring Sterilisation Processes with gaseous H2O2 in combination with heat activation by means of a specially designed calorimetric gas sensor was evaluated. Therefore, the Sterilisation Process was extensively studied by using test specimens inoculated with Bacillus atrophaeus spores in order to identify the most influencing Process factors on its microbicidal effectiveness. Besides the contact time of the test specimens with gaseous H2O2 varied between 0.2 and 0.5 s, the present H2O2 concentration in a range from 0 to 8% v/v (volume percent) had a strong influence on the microbicidal effectiveness, whereas the change of the vaporiser temperature, gas flow and humidity were almost negligible. Furthermore, a calorimetric H2O2 gas sensor was characterised in the Sterilisation Process with gaseous H2O2 in a wide range of parameter settings, wherein the measurement signal has shown a linear response against the H2O2 concentration with a sensitivity of 4.75 °C/(% v/v). In a final step, a correlation model by matching the measurement signal of the gas sensor with the microbial inactivation kinetics was established that demonstrates its suitability as an efficient method for validating the microbicidal effectiveness of Sterilisation Processes with gaseous H2O2

  • Thin-film calorimetric gas sensors for hydrogen peroxide monitoring in aseptic food Processes
    Philipps-Universität Marburg, 2013
    Co-Authors: Kirchner Patrick
    Abstract:

    The Sterilisation of the packaging material is the essential step in aseptic food Processes to ensure safely packed products, which are microbiologically stable throughout their shelf life. Today, gaseous hydrogen peroxide (H2O2) in the range of several volume percent and at elevated temperature is the preferred sterilant due to its strong microbicidal efficiency and its decomposition in environment-friendly products, namely water vapour and oxygen. In order to obtain a high degree of sterility, the initial H2O2 concentration has to be high enough and uniformly distributed over the package's inner surface. To ensure that the packaging surface is thoroughly treated by H2O2, a gas sensor is required that detects the present H2O2 concentration on selected locations of the package's surface while it is sterilised. The present thesis describes the realisation and characterisation of thin-film gas sensors based on an “on chip” differential set-up for monitoring the H2O2 gas concentration during the Sterilisation of the packaging material. The differential set-up contains a catalytically active sensor segment, where H2O2 decomposes in an exothermic reaction causing a temperature increase towards a passive sensor segment, where a surface reaction is inhibited. In a first sensor arrangement, thin-film thermopiles have been fabricated on a single silicon chip, respectively, and their response behaviour has been characterised in H2O2 atmosphere. In a further arrangement, thin-film resistances have been built up as temperature-sensitive transducer platform on a silicon chip. On this platform, different catalytically active materials – platinum black, palladium and manganese oxide – have been tested with regard to their response against H2O2, wherein all of them showed a linear response characteristic, but manganese oxide posseses the highest sensitivity. Furthermore, three temperature-stable polymeric materials – fluorinated ethylene propylene, perfluoralkoxy and epoxy-based SU-8 photoresist – have been tested for the encapsulation of the sensor surface in terms of their chemical inertness against H2O2. Therein, all of them have shown a high resistivity against H2O2 underlining their suitability for sensor passivation. Within the frame of this work, the sensor set-up has further been realised on a thin polyimide foil because of its high temperature endurance, its chemical stability and particularly, its low thermal conductivity allowing an improved thermal separation of the active and passive sensor segment. As a result, the sensitivity of the polyimide-based sensor was strongly increased compared to the concentration-dependent response of the silicon-based sensors. Microbiological experiments with bacterial spores of Bacillus atrophaeus have demonstrated that the microbicidal effectiveness of the Sterilisation Process depends on the present H2O2 concentration in first order as well as on the contact time between the item that has to be sterilised and the gaseous H2O2. By means of sensor measurements conducted at the same time, a correlation model between the microbial inactivation kinetics and the sensor response was established that allows to use the sensor not only for concentration measurements, but also for the quantification and control of the degree of the package's sterility. In order to determine the present H2O2 concentration spatially resolved over the package surface during the short Sterilisation cycle, a wireless sensor electronic based on the industrial ZigBee standard was developed. The sensor electronic contains a remote unit, which is connected to one of the calorimetric gas sensors fixed on a test package, and an external base unit connected to a laptop computer. For real-time measurements, a novel sensor read-out strategy was established, wherein the sensor response is measured within the short Sterilisation time and correlated with both the present H2O2 concentration as well as the microbicidal effectiveness. As a result, this kind of “intelligent” package represents a novel instrumentation to monitor the package Sterilisation in aseptic food Processes under real-time conditions

Reisert S - One of the best experts on this subject based on the ideXlab platform.

  • Multiple sensor-type system for monitoring the microbicidal effectiveness of aseptic Sterilisation Processes
    'Elsevier BV', 2015
    Co-Authors: Reisert S, Geissler H, Weiler C, Wagner, Patrick Hermann, Mj Schoening
    Abstract:

    The present work describes a novel multiple sensor-type system for the real-time analysis of aseptic Sterilisation Processes employing gaseous hydrogen peroxide (H2O2) as a sterilant. The inactivation kinetics of Bacillus atrophaeus by gaseous H2O2 have been investigated by means of a methodical calibration experiment, taking into account the Process variables H2O2 concentration, humidity and gas temperature. It has been found that the microbicidal effectiveness at H2O2 concentrations above 2% v/v is largely determined by the concentration itself, while at lower H2O2 concentrations, the gas temperature and humidity play a leading role. Furthermore, the responses of different types of gas sensors towards the influencing factors of the Sterilisation Process have been analysed within the same experiment. Based on a correlation established between the inactivation kinetics and the sensor responses, a calorimetric H2O2 sensor and a metal-oxide semiconductor (MOX) sensor have been identified as possible candidates for monitoring the microbicidal effectiveness of aseptic Sterilisation Processes employing gaseous H2O2. Therefore, two linear models that describe the relationship between sensor response and microbicidal effectiveness have been proposed. © 2014 Elsevier Ltd.status: publishe

  • Multiple sensor-type system for monitoring the microbicidal effectiveness of aseptic Sterilisation Processes
    Elsevier Science, 2015
    Co-Authors: Reisert S, Geissler H, Weiler C, Wagner P., Schöning, Michael J.
    Abstract:

    The present work describes a novel multiple sensor-type system for the real-time analysis of aseptic Sterilisation Processes employing gaseous hydrogen peroxide (H2O2) as a sterilant. The inactivation kinetics of Bacillus atrophaeus by gaseous H2O2 have been investigated by means of a methodical calibration experiment, taking into account the Process variables H2O2 concentration, humidity and gas temperature. It has been found that the microbicidal effectiveness at H2O2 concentrations above 2% v/v is largely determined by the concentration itself, while at lower H2O2 concentrations, the gas temperature and humidity play a leading role. Furthermore, the responses of different types of gas sensors towards the influencing factors of the Sterilisation Process have been analysed within the same experiment. Based on a correlation established between the inactivation kinetics and the sensor responses, a calorimetric H2O2 sensor and a metal-oxide semiconductor (MOX) sensor have been identified as possible candidates for monitoring the microbicidal effectiveness of aseptic Sterilisation Processes employing gaseous H2O2. Therefore, two linear models that describe the relationship between sensor response and microbicidal effectiveness have been proposed