bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating dynamic-mechanical properties of multi-layered materials for biomedical applications
Authors: Fiedler Nicklas , Arbeiter Daniela , Schümann Kerstin , Illner Sabine , Grabow Niels 
Published: February 2021

Abstract
The development and advancement of polymeric implant materials is a frequent focus in current research. The combination of polymeric materials with diverging properties provides a wide range of new materials with innovative characteristics. One technology for combining materials is to apply a coated layer onto a base material. In this work, a hyperelastic, synthetic base material was combined with a rigid biopolymer coating layer. A multilayered material with combined characteristics of both was built. In the field of processed polymers, the analysis of coating adhesion is not feasible using established methods. Therefore, a dynamic-mechanical method was investigated, which supplements the uniaxial tensile test and provides knowledge regarding mechanical resistance of the multilayered polymer structure. Furthermore, the method gets validated by SEM-imaging and evaluation of coating composition before and after testing under dynamic conditions.
Polymeric stents for the Eustachian tube: development and human cadaver study
Authors: Schümann Kerstin , Wilfling Tamara , Paasche Gerrit , Schuon Robert , Lenarz Thomas , Tautorat Carsten , Grabow Niels , Schmitz Klaus-Peter 
Published: February 2021

Abstract
Impairment of Eustachian tube function with nonsufficient ventilation of the middle ear is a main cause for chronic otitis media. To provide an effective and safe therapy, the innovative concept of Eustachian tube stenting was established. Biodegradable polymeric stents are developed to restore impaired tube function and dissolve after fulfilling their supportive purpose. To evaluate the applicability of the stents in the Eustachian tube, prototypes in conjunction with corresponding implantation instruments were tested in human cadaver studies. Radiopaque markers and a diaphanoscopic approach were tested as additional features to prove correct positioning of catheter and stent in the tube. In the current study biodegradable polymeric stents were implanted in the Eustachian tube of human cadavers without difficulty. Correct positioning of the stents in the tube was proved by diaphanoscopy during intervention and postoperative tomographic and histological analyses. Once designs are optimized on the basis of cadaver studies, preclinical safety and efficacy studies using animal models will be initiated.
Transcatheter mitral valve repair devices - in vitro studies on the influence of device-width on mitral regurgitation
Authors: Ott Robert , Kaule Sebastian , Großmann Swen , Stiehm Michael , Schmitz Klaus-Peter , Siewert Stefan , Öner Alper Ö , Ince Hüseyin , Grabow Niels 
Published: February 2021

Abstract
Mitral regurgitation (MR) is the most prevalent valvulopathy in the USA and the second most prevalent valvulopathy in Europe. Despite excellent clinical results of surgical mitral valve repair (SMVR), transcatheter-based mitral valve repair (MVR) procedures emerged as a feasible treatment option for surgically inoperable or high-risk patients suffering from clinically relevant MR. The current study investigates the impact of device-induced coaptationwidth on the hydrodynamic performance of insufficient mitral valves (MV) during left ventricular (LV) systole. A non-calcified, pathological MV model (MVM) featuring a D-shaped MV annulus with an area of 7.6 cm2 and a flail gap in the A2-P2 region was employed in an experimental setup. Pressure gradient-volumetric flow rate (Δp-Q) relations were investigated for steady-state backward flow with transvalvular pressure gradients ranging from (0.75 ≤ Δp ≤ 177.36) mmHg. Glycerol-water mixture (36 % (v/v) glycerol in water) at 37 °C with a density of (1 098.2 ± 1.3) kg·m-3 and a dynamic viscosity of 3.5 mPa∙s was used as circulatory fluid. In order to determine the impact of the width of transcatheter MVR devices during LV-systole Δp-Q relations were investigated for three MVM-configurations: (i) MVM without MVR device, (ii) MVM with one MVR device and (iii) MVM with two MVR devices implanted in the A2-P2 region. The MVR devices were manufactured from steel sheets with a thickness of 0.2 mm and feature arm lengths of 9.0 mm and a width of 5.0 mm. The conducted investigations show that the implantation of MVR devices in the A2-P2 region prevents the manifestation of an A2-P2 flail gap and thereby effectively reduces the retrograde blood flow during the LV-systole by 13 % with one MVR device and 27 % with two MVR devices implanted. Thus, the application of two MVR devices with a combined device-induced width of 10 mm results in a better MR reduction than the implantation of one MVR device with a device-induced width of 5 mm.
Integration of antimicrobial substances in 3-D printed plastics
Authors: Buhl Sebastian , Vogt J. , Stich A. , Brückner R. , Bulitta C. 
Published: February 2021

Abstract
The risk of healthcare associated infections (HAI) is rising with the utilization of more complex medical devices. Cleaning and disinfecting measures of such devices are often insufficient leading to an increased microbiological contamination on these devices. Recent studies imply that antimicrobial coatings could present a solution for this topic. In this work a novel approach for the introduction of an antimicrobial technology into plastic granulate was tested. After 3-D printing the antimicrobial activity of the test samples was analysed. Our results show that the integration of an antimicrobial substance to ABS plastic is feasible only with sophisticated plastic processing technologies. Simple heating or mixing of the substance did not allow integration of the antimicrobial substance into the 3-D printed sample, but it was possible to integrate the antimicrobial ingredient into the raw material by compounding. The printed test samples showed strong antimicrobial activity in the standardized test procedures.
Clinical validation and efficacy of a temperature-controlled ventilation system (TcAF) in the OR to reduce surgical site infections
Authors: Bulitta Clemens , Vasiuk Sergeii , Vasylchyshyn Yaroslav , Vasyuk Volodymyr , Guttenberger Regina , Buhl Sebastian 
Published: February 2021

Abstract
Microbiological burden of room-air in operating theatres is a known risk factor for surgical site infections. However, it is unclear how to best evaluate efficacy and efficiency under routine clinical conditions. Moreover, there still is a lack of data to assess the impact on infection rates. The aim of this study was to evaluate a temperature-controlled ventilation system (TcAF) under routine clinical conditions and assess its impact on infection rates. 10 clinical installations of the TcAF system Opragon (Avidicare AB, Sweden) were assessed during live surgeries according to the Swedish SIS TS 39: 2015 standard. Furthermore, a retrospective analysis of 1,000 consecutive cases of primary total joint arthroplasty (hip, knee) before and 1000 after installation of the TcAF system was performed. Endpoints for clinical outcome were length of stay and infection rates. Our results show that requirements of the Swedish standard were met or significantly exceeded by the TcAF system reliably and robustly ensuring "ultra-clean" air in the entire operating theatre and demonstrating the capability to reduce the risk of airborne microbial transmission under routine clinical conditions. The study shows positive impact on key clinical outcome parameters in line with previous research by Charnley and Lidwell.
Relevance and implications of positioning analysis for infection-preventive effectiveness of ventilation systems with low-turbulence dis-placement flow
Authors: Bulitta Clemens , Schlautmann Burkhard 
Published: February 2021

Abstract
Ventilation technology in German operating rooms is regulated by DIN 1946-4. Since the release of the latest version in 2018, a positioning analysis (worst-case scenario with the largest space requirement) for determining the required protected area in class 1a operating rooms is mandatory. The aim of this investigation was to use typical workflow scenarios to assess existing installations regarding the match of the required and the built size of the protected area. Positioning analyses were carried out together with the on-site staff for various clinical procedures in 2 hospitals to assess the built versus required protected areas. In all cases, the positioning analysis revealed that required protected areas need to be significantly larger than provided by the existing setup. The size of the protected area that is actually required can only be determined by individual positioning analysis. Most existing installations of low turbulence displacement flow systems (TAV) are likely to be too small. The larger protected areas actually require significantly larger rooms in order to maintain proper thermodynamics. Furthermore, significantly higher volumetric flow rates are required. Finally, the current mismatch between actual and necessary protected area would be a possible explanation for the controversial data situation regarding the infection preventive effects of TAV systems.
Robust predictive control for respiratory CO2 gas removal in closed-loop mechanical ventilation: An in-silico study
Authors: Schmal Matthias , Haueisen Jens , Männel Georg , Rostalski Philipp , Kircher Michael , Bluth Thomas , Gama de Abreu Marcelo , Stender Birgit 
Published: February 2021

Abstract
In this study a physiological closed-loop system for arterial CO2 partial pressure control was designed and comprehensively tested using a set of models of the respiratory CO2 gas exchange. The underlying preclinical data were collected from 12 pigs in presence of severe changes in hemodynamic and pulmonary condition. A minimally complex nonlinear state space model of CO2 gas exchange was identified post hoc in different lung conditions. The control variable was measured noninvasively using the endtidal CO2 partial pressure. For the simulation study the output signal of the controller was defined as the alveolar minute volume set value of an underlying adaptive lung protective ventilation mode. A linearisation of the two-compartment CO2 gas exchange model was used for the design of a model predictive controller (MPC). It was augmented by a tube based controller suppressing prediction errors due to model uncertainties. The controller was subject to comparative testing in interaction with each of the CO2 gas exchange models previously identified on the preclinical study data. The performance was evaluated for the system response towards the following five tests in comparison to a PID controller: recruitment maneuver, PEEP titration maneuver, stepwise change in the CO2 production, breath-hold maneuver and a step in the reference signal. A root mean square error of 2.69 mmHg between arterial CO2 partial pressure and the reference signal was achieved throughout the trial. The reference-variable response of the model predictive controller was superior regarding overshoot and settling time.
Actuation of a magnetically coated swimmer in viscous media with a magnetic particle imaging scanner
Authors: Bakenecker Anna C. , Chinchilla Carlos , Buzug Thorsten M. 
Published: February 2021

Abstract
Magnetic actuation of medical devices is of great interest in improving minimally invasive surgery and enabling targeted drug delivery. With untethered, magnetically coated swimmers it is aimed at reaching regions of the body difficult to access with catheters. Such a swimmer was previously presented, which is suitable for the navigation by the magnetic fields of a magnetic particle imaging (MPI) scanner. The swimmer could be imaged with MPI as well, enabling the tomographic real-time tracking of the actuation process. In this work the steerability of the swimmer is further investigated in media of varying viscosities. For this, glycerol-water-mixtures of different mixing ratios were used. The velocities of the swimmer were measured for viscosities between those of pure glycerol and pure water. The experiments were performed with an MPI scanner at maximal magnetic field strength of the actuating fields. A viscosity range was found in which the swimmer is steerable by the fields of an MPI scanner, which leads to a prediction of the applicability of the swimmer in different body fluids.
Multi-channel impedance analyzer for automated testing of networks and biomaterials
Authors: Tautorat Carsten , Kamke Frank , Pfensig Sylvia , Siewert Stefan , Schmitz Klaus-Peter , Grabow Niels , Schmidt Wolfram 
Published: February 2021

Abstract
Impedance spectroscopy represents a basic operating principle for biomedical sensors, bioimpedance spectroscopy, electrochemical analyses and for characterization of functional biomaterials. For automated long-term investigations, an impedance analyzer for multi-channel testing of up to eight passive two-pole networks is presented in this paper. Its operating system is application-specific adapted to the required test functionalities and measuring ranges. Measurements are based on a commercially available integrated impedance converter circuit. Our current analyzer setup is capable of measuring impedance values from 50 kΩ up to 10 MΩ with automated range selection for most accurate results. The impedance under test is excited with a single frequency of 1 kHz. An impedance accuracy of 1.5 % was determined in reference measurements. The presented impedance analyzer is a low cost system ready for use particularly in long-term characterization of dielectric networks, such as material properties, with multiple samples.
Composite polyelectrolyte multilayers for biofunctionalization of medical devices
Authors: Rudt Alexander , Andreeva Tonya D. , Krastev Rumen , Taneva Stefka G. 
Published: February 2021

Abstract
Polyelectrolyte multilayer coatings (PEM) are prepared by alternative layer-by-layer deposition of cationic and anionic polyelectrolyte monolayers on charged surfaces. The thickness of the coatings ranges from nm to few μm. Their properties such as roughness, stiffness, surface charge and surface energy can be precisely tuned to fulfill different technical or biological requirements. The coating process is based on self-assembly of polyelectrolytes. Advantages of these coatings are their easy handling, no harsh chemistry and the possibility for coatings on complex geometries. The PEM coatings can be prepared from a variety of suitable polyelectrolytes. Their stability varies from very durable PEM coatings that are only soluble in strong solvents to quickly degradable, which may be applied as drug release system. One example of such a degradable PEM system is the one based on the polyelectrolyte pair Hyaluronan (HA) and Chitosan (CHI). These biopolymers originate from natural sources and show low toxicity towards human cells. However, HA/CHI multilayers shows only weak adhesiveness for human umbilical vein endothelial cells (HUVEC). In this article, we summarize our approaches to enhance the HA/CHI multilayer by incorporation of a non-polymer substance -graphene oxide- to improve the cell adhesion and keep such properties as low cytotoxicity and biodegradability. Different approaches for incorporation of graphene oxide were performed and the cellular adhesion was tested by metabolic assay.
Computed fiber evaluation of SEM images using DiameterJ
Authors: Götz Andreas , Senz Volkmar , Illner Sabine , Grabow Niels 
Published: February 2021

Abstract
Fiber materials offer a high potential for improving the surface characteristics of medical implants. For quality assurance of nano- and microfiber structures the morphology is inspected by Scanning Electron Microscopy (SEM) as a standard method. Vast quantities of image data have to be evaluated. Usual practice for obtaining the fiber diameters is the manually setting of measurement points. The software DiameterJ which runs as plugin in ImageJ automatically computes fiber diameters. Here we investigated its capabilities and limitations by comparing the evaluation of selected sample SEM images of electrospun fibers. In this study the fibers of three examplary images specified by different contrast and fiber morphology were analyzed by using varied segmentation algorithms. The results are displayed in bar charts of frequency distribution. Additionally the computed fiber diameters were compared to manual measurements. Depending on various image properties the segmentation process works more or less reliable, and fault data of incomplete segmented fibers are computed. Often the results are eligible, but frequently DiameterJ generates data resembling to thin fibers, which are not present in the image. In some cases the peaks of fault data are much higher than peaks of real fibers. In consequence misinterpretation of data cannot be avoided. DiameterJ is a validated tool with the ability to generate reliable results. Future work on improving the segmentation algorithms can refine computed evaluation.
Impact of aortic annulus geometry according to ISO 5840:2019 (draft) on hydrodynamic performance of transcatheter aortic valve prostheses
Authors: Oldenburg Jan , Kaule Sebastian , Siewert Stefan , Schmitz Klaus-Peter , Stiehm Michael , Grabow Niels 
Published: February 2021

Abstract
To assess the hydrodynamic performance of transcatheter aortic valve prostheses (TAVP), in vitro test using pulse duplicators is required. Test conditions as well as minimum performance criteria are specified in ISO 5840- 3:2013 and ISO 5840-3:2019-draft. In the 2019 published draft, modifications regarding hydrodynamic testing are proposed. Among others, the geometrical configuration of the fixation has changed, with the intention to improve the anatomical representation as well as the comparability of results from different test laboratories. We analyzed the consequences of altered annulus fixations regarding native leaflets as well as a step in the proximal area of the protheses to prevent their migration. The analyses were conducted with regard to the degree of calcification of the annulus ring on hydrodynamic parameters. By using 3D stereolithography printing technology, molds for casting of silicone elastomer of annulus models with and without native leaflets were manufactured. A modular system enabled us to use the same annulus ring to model the degree of calcification as well as different step sizes. We performed in vitro hydrodynamic testing according to ISO 5840-3:2019-draft of a selfexpandable valve prototype with porcine pericardial leaflets by using a commercially available pulse duplicator system. As expected, regurgitation increases with increasing degree of calcification, whereby the use of a step has no influence on the backflow of fluid during diastole. The effective orifice area (EOA) of the valve showed a clear tendency with respect to radial protrusion of the step. The EOA decreased as the radial protrusion increased. We also present a suggestion to prevent migration without affecting the general test results, by using a novel step design. We also found that the novel annulus model with native leaflet drastically reduced the regurgitation.
Adaptable Superfibers as Implant Material
Authors: Illner Sabine , Ortelt Jonathan , Arbeiter Daniela , Khaimov Valeria , Wulf Katharina , Oschatz Stefan , Reske Thomas , Senz Volkmar , Schmitz Klaus- Peter , Grabow Niels 
Published: February 2021

Abstract
Electrospun fiber nonwoven materials of different polymer classes provide promising perspectives in almost all fields of application, including medical science. In this paper we present the fiber generation of selected biostable polymers (PBT, TPC-ET, PA 6.12 and PVDF) by direct electrospinning, as an extremely powerful tool for manufacturing of new superfiber implant materials. This initial study includes the variation of some relevant process parameters, such as polymer concentrations or electrode spacing. The influence on fiber morphology, tensile strength and biocompatibility is shown. The results presented indicate that the choice and combination of materials is crucial for the application on load-bearing implants, independent of the processing technology and thus of the fiber bonding, delamination or fiber strength.
Use of artificial intelligence and neural networks for analysis and gesture detection in electrical impedance tomography
Authors: Gibas Christian , Mülln Luca , Brück Rainer 
Published: February 2021

Abstract
Artificial intelligence and neural networks are getting more and more relevant for several types of application. The field of prosthesis technology currently uses electromyography for controllable prosthesis. The precision of the control suffers from the use of EMG. More precise and more collected data with the help of EIT allows a much more precise analysis and control of the prosthesis. In this paper a neural network for gesture detection using EIT is developed and presented in a user-friendly way.
Quantification of Interpatient 12-lead ECG Variabilities within a Healthy Cohort
Authors: Nagel Claudia , Pilia Nicolas , Loewe Axel , Dössel Olaf 
Published: February 2021

Abstract
The morphology of the electrocardiogram (ECG) varies among different healthy subjects due to anatomical and structural reasons, such as for example the shape of the heart geometry or the position and size of surrounding organs in the torso. Knowledge about these ECG morphology changes could be used to parameterize electrophysiological simulations of the human heart. In this work, we detected the boundaries of ECG waveforms, i.e. the P-wave, the QRS-complex and the T-wave, in 12- lead ECGs from 918 healthy subjects in the Physionet Computing in Cardiology Challenge 2020 Database with the IBT openECG toolbox. Subsequently, we obtained the onset, the peak and the offset of each P-wave, QRS-complex and T-wave in the signal. In this way, the duration of the P-wave, the QRScomplex and the T-wave, the PQ-, RR- and the QT-interval as well as the amplitudes of the P-wave, the Q-, R- and Speak and the T-wave in each lead were extracted from the 918 healthy ECGs. Their statistical distributions and correlation between each other were assessed. The highest variabilities among the 918 healthy subject were found for the RR interval and the amplitudes of the QRScomplex. The highest correlation was observed for feature pairs that represent the same feature in different leads. Especially the R-peak amplitudes showed a strong correlation across different leads. The calculated feature distributions can be used to optimize the parameters of populations of cardiac electrophysiological models. In this way, realistic in-silico generated surface ECGs can be simulated in large scale and could be used as input data for machine learning algorithms for a classification of cardiovascular diseases.
Diagnostic Capabilities of a Smartphone- Based Low-Cost Microscope
Authors: Hasselbeck Dorina , Schäfer Max B. , Stewart Kent W. , Pott Peter P. 
Published: February 2021

Abstract
Microscopy enables fast and effective diagnostics. However, in resource-limited regions microscopy is not accessible to everyone. Smartphone-based low-cost microscopes could be a powerful tool for diagnostic and educational purposes. In this paper, the imaging quality of a smartphone-based microscope with four different optical parameters is presented and a systematic overview of the resulting diagnostic applications is given. With the chosen configuration, aiming for a reasonable trade-off, an average resolution of 1.23 μm and a field of view of 1.12 mm2 was achieved. This enables a wide range of diagnostic applications such as the diagnosis of Malaria and other parasitic diseases.