61 research outputs found
Novel perspectives to improve the outcome of bone impaction grafting in revision surgery of total hip arthroplasties
No full textContains fulltext :
122945.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 13 januari 2014Promotor : Buma, P. Co-promotores : Bloem, R.M., Schreurs, B.W., Pilot, P
Air quality in the periphery of operating rooms during surgery
No full textUltra-clean ventilation systems are used in the operating room (OR) to reduce the quantity of airborne bacteria in the ultra-clean area, and reduce the incidence of surgical site infections (SSIs). When the number of colony-forming units (CFUs) in the ultra-clean (protected) area is too high, this is considered a risk factor for SSIs.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Environmental & Climate DesignMedical Instruments & Bio-Inspired Technolog
The flexible asymmetric shock tube (FAST): A Ludwieg tube facility for wave propagation measurements in high-temperature vapours of organic fluids
No full textThis paper describes the commissioning of the flexible asymmetric shock tube (FAST), a novel Ludwieg tube-type facility designed and built at Delft University of Technology, together with the results of preliminary experiments. The FAST is conceived to measure the velocity of waves propagating in dense vapours of organic fluids, in the so-called non-ideal compressible fluid dynamics (NICFD) regime, and can operate at pressures and temperatures as high as 21 bar and 400 ?C, respectively. The set-up is equipped with a special fast-opening valve, separating the high-pressure charge tube from the low-pressure plenum. When the valve is opened, a wave propagates into the charge tube. The wave speed is measured using a time-of-flight technique employing four pressure transducers placed at known distances from each other. The first tests led to the following results: (1) the leakage rate of 5×10?4mbarl s?1 for subatmospheric and 5×10?2mbarl s?1 for a superatmospheric pressure is compatible with the purpose of the conceived experiments, (2) the process start-up time of the valve has been found to be between 2.1 and 9.0 ms, (3) preliminary rarefaction wave experiments in the dense vapour of siloxane D6 (dodecamethylcyclohexasiloxane, an organic fluid) were successfully accomplished up to temperatures of 300?C, and (4) a method for the estimation of the speed of sound from wave propagation experiments is proposed. Results are found to be within 2.1 % of accurate model predictions for various gases. The method is then applied to estimate the speed of sound of D6 in the NICFD regime.Aerodynamics, Wind Energy & PropulsionAerospace Engineerin
Combining bisphosphonates with allograft bone for implant fixation
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137656.pdf (Publisher’s version ) (Open Access)The aim of this review was to discuss the current state of research of combining bisphosphonates with allograft bone for implant fixation. The allograft bone can only be reached by the bisphosphonate once it has been revascularized. However, this can be circumvented by local administration of bisphosphonates. Several animal studies showed that local application of bisphosphonates might protect the graft from resorption. There seems to be an optimum concentration for local application, however, this optimum varies for all different bisphosphonates. It can be concluded that local administration of bisphosphonates might play an important role in improving stability after surgery in which a prosthesis is combined with allograft bone to restore bony defects, however caution should be taken when extrapolating results of animal research to the human clinical situation. More research is needed to study the effect of local bisphophonate use in humans and to study possible side effects
Predictors of outcome in hip fracture patients
No full textHet aantal heupfracturen zal de komende jaren stijgen. Bovendien zijn de morbiditeit en mortaliteit na een heupfractuur groot. Het eerste deel van het proefschrift gaat over prothesiologie bij heupfractuurpatiënten. Uit eerder onderzoek is gebleken dat een prothese de voorkeur heeft ten opzichte van osteosynthese. Hoofdstuk drie beschrijft een multicenter trail waarbij we 201 patiënten hebben gerandomiseerd tussen een gecementeerde en een ongecementeerde kophalsprothese. De patiënten met een gecementeerde prothese kregen minder complicaties (minder periprothetische fracturen en luxaties). In hoofdstuk twee beschrijven we de 22.675 patiënten die de afgelopen 10 jaar na een heupfractuur in het landelijk register zijn opgenomen. Uit dit hoofdstuk blijkt dat er minder re-operaties worden uitgevoerd na een gecementeerde prothesesteelfixatie en een niet-posterolaterale benadering. Het tweede deel van het proefschrift toont dat een heupfractuur een enorme impact heeft op het leven van de patiënt. Het percentage delier na de fractuur was hoog (27%) evenals het percentage mensen dat overleed binnen 30 dagen (8%). Kwaliteit van leven en dagelijks functioneren gingen fors achteruit en herstelden niet volledig. De patiënten die het meest achteruit gingen waren jong en mobiel voorafgaand aan de fractuur. We adviseren dan ook meer aandacht te hebben voor deze groep.LUMC / Geneeskunde Repositoriu
Working Fluid Design for Organic Rankine Cycle (ORC) Systems
No full textThe Organic Rankine Cycle is an energy conversion cycle similar to the conventional Rankine cycle which runs on a working fluid other than water. The selection of a working fluid is a critical part of designing an Organic Rankine Cycle (ORC) system. The number of fluid types actually used in commercial ORC power plants do not justify the number of fluid selection studies present in scientific literature. Hence the objective of this work is to develop a tool which simultaneously optimizes the energy conversion process and selects the optimum working fluid for a given heat source. It is based on a framework that uses a continuous-molecular targeting approach which allows for an integrated working fluid and system design. The process is modeled in Cycle Tempo, a modern graphical tool for thermodynamic analysis and optimization of systems for the production of electricity, heat and refrigeration. The system is simultaneously optimized with the pure component parameters of PCP-SAFT equation of state using a state-of-the-art optimization suite. The working fluid is selected by comparison of the pure component parameters of the PCP-SAFT equation of state with real fluids. A preliminary turbine model implemented directs the tool to generate suitable fluids for practically realistic systems. The tool has been tested for a waste heat recovery system for heavy-duty truck engines based on an ORC turbogenerator. The choice of working fluid is restricted to only the siloxane class which not only adheres to the technical, environmental, and toxicological requirements typical of the automotive sector but also allows for the implementation of a preliminary radial turbine model, whose shaft can be lubricated by the working fluid itself. The turbine has been modeled by applying the methodology of using non-dimensional parameters. Future work will be devoted to implement detailed component models and extending the scope of fluid selection to other organic fluid classes.Energy TechnologyProcess and EnergyMechanical, Maritime and Materials Engineerin
Working fluid design for organic rankine cycle systems (ORC)
No full textThe Organic Rankine Cycle is an energy conversion cycle similar to the conventional Rankine cycle which runs on a working fluid other than water. The selection of a working fluid is a critical part of designing an Organic Rankine Cycle (ORC) system. The number of fluid types actually used in commercial ORC power plants do not justify the number of fluid selection studies present in scientific literature. Hence the objective of this work is to develop a tool which simultaneously optimizes the energy conversion process and selects the optimum working fluid for a given heat source. It is based on a framework that uses a continuous-molecular targeting approach which allows for an integrated working fluid and system design. The process is modeled in Cycle Tempo, a modern graphical tool for thermodynamic analysis and optimization of systems for the production of electricity, heat and refrigeration. The system is simultaneously optimized with the pure component parameters of PCP-SAFT equation of state using a state-of-the-art optimization suite. The working fluid is selected by comparison of the pure component parameters of the PCP-SAFT equation of state with real fluids. A preliminary turbine model implemented directs the tool to generate suitable fluids for practically realistic systems. The tool has been tested for a waste heat recovery system for heavy-duty truck engines based on an ORC turbogenerator. The choice of working fluid is restricted to only the siloxane class which not only adheres to the technical, environmental, and toxicological requirements typical of the automotive sector but also allows for the implementation of a preliminary radial turbine model, whose shaft can be lubricated by the working fluid itself. The turbine has been modeled by applying the methodology of using non-dimensional parameters. Future work will be devoted to implement detailed component models and extending the scope of fluid selection to other organic fluid classes.Energy TechnologyProcess & EnergyMechanical, Maritime and Materials Engineerin
Experimental Observation of Non-Ideal Compressible Fluid Dynamics: with Application in Organic Rankine Cycle Power Systems
No full textFlight Performance and PropulsionEnergy Technolog
Operating room ventilation systems: recovery degree, cleanliness recovery rate and air change effectiveness in an ultra-clean area
No full textBackground: Entrainment test methods are described in most European standards and guidelines to determine the protected area for ultra-clean ventilation (UCV) systems. New UCV systems, such as temperature-controlled airflow (TcAF) and controlled dilution ventilation (cDV) systems, claim the whole operating room (OR) to be ultra-clean. However, current test standards were not developed to assess ventilation effectiveness outside the standard protected area. Aim: To assess and compare the ventilation effectiveness of four types of OR ventilation systems in the ultra-clean area using a uniform test grid.Methods: Ventilation effectiveness of four ventilation systems was evaluated for three different ultra-clean (protected) areas: the standard protected area (A); the area outside the standard protected area (B); and a large protected area (AB). Ventilation effectiveness was assessed using recovery degree (RD), cleanliness recovery rate (CRR) and air change effectiveness (ACE). Findings: RD, CRR and ACE were significantly higher for the unidirectional air flow (UDAF) system compared with the other systems in area A. In area B, the UDAF and cDV systems were comparable for RD and CRR, and the UDAF and conventional ventilation (CV) systems were comparable for ACE. In area AB, the UDAF and cDV systems were comparable for CRR and ACE, but significant differences were found in RD.Conclusion: In area A, the ventilation effectiveness of the UDAF system outperformed other ventilation systems. In area B, the cDV system was best, followed by the UDAF, TcAF and CV systems. In area AB, the UDAF system was best, followed by the cDV, TcAF and CV systems.Building ServicesMedical Instruments & Bio-Inspired TechnologySupport Biomechanical Engineerin
Effective radiation dose in radiostereometric analysis of the hip
No full textBackground and purpose - Radiostereometric analysis (RSA) is the gold standard to study micromotion of joint replacements. RSA requires the acquisition of additional radiographs increasing the radiation dose of patients included in RSA studies. It is important to keep this dose as low as possible. Effective radiation dose (ED) measurements of RSA radiographs for different joints were done by Teeuwisse et al. some years ago using conventional radiology (CR); for total hip arthroplasty (THA), Teeuwisse et al. reported an ED of 0.150 milliSievert (mSv). With the modern digital radiography (DR) roentgen technique the ED is expected to be less. Material and methods - In this phantom study, simulating a standard patient, the ED for hip RSA radiographs is determined using DR under a variety of different roentgen techniques. The quality of the RSA radiographs was assessed for feasibility in migration analysis using a (semi-)automatic RSA analysis technique in RSA software. Results - A roentgen technique of 90 kV and 12.5 mAs with additional 0.2 copper (Cu) + 1 mm aluminum (Al) external tube filters results in an ED of 0.043 mSv and radiographs suitable for analysis in RSA software. Interpretation - The accumulated ED for a standard patient in a 2-year clinical hip RSA study with 5 follow-up moments and a double acquisition is below the acceptable threshold of 1.0 mSv provided by the EU radiation guideline for studies increasing knowledge for general health.Orthopaedics, Trauma Surgery and Rehabilitatio
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