bluuebunny/crossref_metadata_2025_split huggingface dataset:
An efficient ECG Denoising method using Discrete Wavelet with Savitzky-Golay filter
Authors: Samann Fars , Schanze Thomas 
Published: September 2019

Abstract
Electrocardiogram (ECG) is a widely used tool for the early diagnosis and evaluation of cardiac disorders. The ECG signal is usually distorted during recording by different types of noise which may lead to incorrect diagnosis. Therefore, clear ECG signals are required to support good cardiac disorder diagnosing. In this paper, an efficient ECG denoising method using combined discrete wavelet with Savitzky-Golay (S-G) filter is proposed. The performance of S-G filter is studied in terms of polynomial degree and frame size, i.e. signal section. In addition, the performance of denoising wavelet is studied in term of mother wavelet type and wavelet order. The advantage of S-G filter is combined with discrete wavelet denoising method to get better denoising performance. The performance of denoising ECG are evaluated using signal to noise ratio (SNR) and percentage root mean square difference (PRD). For this we used simulated and gaussian white noise surrogated ECG signals. Our results show that combined S-G and wavelet filter denoising is noticeable better than the respective individual procedures. In addition, we found that the selection of frame size, order of the S-G filter and the wavelet type and order should be done carefully in order to get optimal results. It also holds true for the new filter that the optimal choice of filter parameters is a compromise between noise reduction and distortion.
Automatic image analysis system to measure wound area in vitro
Authors: Dawn Parente Jacquelyn , Dhamodharan Adchiya , Hensler Sabine , Kuhlbach Claudia , Mueller Margareta M. , Möller Knut 
Published: September 2019

Abstract
In-vitro wound area measurement tracks the rate of wound healing. This project develops and validates an automatic image analysis system to calculate wound area from digital images of an in-vitro 3D tissue model wounded with a biopsy punch. The algorithms were evaluated for repeatability, reliability, and reproducibility, and validated against a known area. Repeatability was checked through repeated measurements under repeated conditions. Reproducibility was evaluated using a Bland Altman plot and paired t-test. Reliability was validated using an image of a known pixel area as a control. The validated image analysis system then calculated wound area from the digital camera and microscope images obtained from an in vitro photo biomodulation treatment experiment. A total of 48 wounded tissues were grouped into red and blue light treatment groups and untreated controls. All daily images were fed into the image analysis system to calculate wound area. The wound area (normalized by day 0) is plotted along the 2-week treatment experiment period to observe wound area in time. The normalised wound area plotted across treatment days show no change in wound area during the treatment period. Future work will adapt the imaging system for visualizing the reepithelialisation cell front marked by live dyes.
Enhancing the biocompatibility of siliconepolycarbonate urethane based implant materials
Authors: Athanasopulu Kiriaki , Kutuzova Larysa , Thiel Joana , Lorenz Günter , Kemkemer Ralf 
Published: September 2019

Abstract
Polyurethane-bases block copolymers (TPCUs) are block-copolymers with systematically varied soft and hard segments. They have been suggested to serve as material for chondral implants in joint regeneration. Such applications may require the adhesion of chondrocytes to the implant surface, facilitating cell growth while keeping their phenotype. Thus, aims of this work were (i) to modify the surface of soft biostable polyurethane-based model implants (TPCU and TSiPCU) with high-molecular weight hyaluronic acid (HA) using an optimized multistep strategy of immobilization, and (ii) to evaluate bioactivity of the modified TPCUs in vitro. Our results show no cytotoxic potential of the TPCUs. HAbioactive molecules (Mw =700kDa) were immobilized onto the polyurethane surface via polyethylenimine (PEI) spacers, and modifications were confirmed by several characterization methods. Tests with porcine chondrocytes indicated the potential of the TPCU-HA for inducing enhanced cell proliferation.
Characterization of Atrial Septal Defect Occluders by right and left atrial pull-out forces
Authors: Brudsche Markus , Ismer Bruno , Haas Nikolaus A. 
Published: September 2019

Abstract
Occluders made of the shape memory alloy Nitinol are commonly used to close Atrial Septal Defects (ASD). Until now, standard parameters are missing defining the mechanical properties of these implants. In this study, we developed a special measuring setup for the determination of the mechanical properties of customly available occluders (i.e. Occlutech Figulla® Flex II 29ASD12 and AGA AMPLATZER™ 9-ASD-012).
Development of an in vitro test procedure for the characterization of left atrial appendage occluder devices
Authors: Borowski Finja , Kaule Sebastian , Siewert Stefan , Schmitz Klaus-Peter , Stiehm Michael , Öner Alper Ö , Grabow Niels , Schmitz Klaus-Peter 
Published: September 2019

Abstract
The implantation of an occluder in the left atrial appendage (LAA) is an emerging therapy for the treatment of patients suffering from atrial fibrillation and with a contraindication to oral anticoagulation. The LAA occluder (LAAO) provides a reduction of the potential risk of strokes by thromboembolism. Currently, only a few CE-approved devices are available on the market and the number of clinical trials is comparatively low. Furthermore, there is currently no standardized test method available for testing functionality of the occluder, especially for testing safe anchorage and permeability. Therefore, the aim of this study is to establish an in vitro test method to prove anchorage mechanism and permeability regarding thromboembolism of the LAAO under physiological conditions. A standardized technical and fully parameterized silicone model of a LAA, based on studies of different morphologies and sizes, was developed. The LAA model was mounted onto the left atrial chamber of a commercial pulse duplicator system to simulate physiological hemodynamic conditions. The test was performed using the Watchman device (Boston Scientific, USA; size: 31 mm). The inner implantation diameter of the LAA model was designed according to a target compression of 10% for the Watchman device in the implanted configuration. Furthermore, thrombus-like particles (n=150, d=1,7±0,05 mm) were added to represent the flushing of thrombi out of the LAA after device implantation. Within several cycles it was confirmed that no particles were washed out of the LAA model with the implanted occluder leading to a full protection against thromboembolism. It could also be shown that the occluder is firmly anchored in the LAA. Pressure measurements with sensors in the left atrium and in the LAA distal to the occluder could also show that the occluder has no influence on the pressure conditions in the LAA.
Non-destructive analysis of drug content in polymer coatings with Raman spectroscopy
Authors: Reske Thomas , Wulf Katharina , Eickner Thomas , Grabow Niels , Schmitz Klaus-Peter , Siewert Stefan 
Published: September 2019

Abstract
The analysis of device drug content typically is carried out by means of chromatographic methods such as high performance liquid chromatography (HPLC) or liquid chromatography-mass spectrometry (LCMS). These approved methods are particularly fast, cost-efficient and ubiquitous in chemical-analytical laboratories. However, these quantitative methods necessitate the drug being eluted, which represents a destructive process. A novel alternative to these well-established methods [1, 2] is the Raman spectroscopy, which is fast and cost-efficient, as well [3]. Additionally, it offers the advantage of nondestructive analysis without the need for a special sample preparation. Within the current investigation we applied Raman spectroscopy for the qualitative and quantitative analysis of dexamethasone (DMS), a glucocorticoid, incorporated in a silicone matrix. The investigation was conducted in a rectangular area on the sample surface. The required number of measuring points (spectra) was determined. Calibration was performed with samples containing different amounts of DMS. The evaluation of Raman spectra is based on the analysis of the peak areas of the bands at 795 rel. cm-1(silicone) and 1,663 rel. cm-1(DMS). Remarkably, next to a precise overview of DMS distribution, an exact and reproducible quantification of incorporated DMS could be obtained.
Method for the improvement of mechanical properties of biodegradable polymeric scaffolds
Authors: Schümann Kerstin , Arbeiter Daniela , Grabow Niels , Schmitz Klaus-Peter 
Published: September 2019

Abstract
At present, a main focus in the field of stent technologies is on the development of biodegradable polymeric stents. Due to inferior material characteristics of polymers compared to permanent metals stents require thicker stents struts to accomplish adequate mechanical properties. Therefore, a thermo-mechanical treatment of polymeric stents was tested, which showed a positive effect on mechanical stent characteristics.
Pressure sensor emulator to improve longterm stability of heart valve testing systems
Authors: Tautorat Carsten , Kaule Sebastian , Kaminsky Jörg , Schmitz Klaus-Peter , Grabow Niels , Schmidt Wolfram 
Published: September 2019

Abstract
Fluid mechanical characterization of artificial heart valve prostheses requires reliable measurement of temperature, flow and pressure at normal heart rate. In vitro fatigue test procedures of artificial heart valve prostheses can take several months with up to 400 million cycles to assess valve performance and durability under simulated cardiac conditions at increased pulse frequency. In both cases, a minimum of user interventions for recalibration are required. In these tests, pressure data are collected for hydrodynamic heart valve characterization and for closed-loop control of pressure loading. In our study, the improvement of commercial heart valve testing systems (Vivitro Pulse Duplicator, Vivitro Labs Inc. and VDT-3600i, BDC Laboratories) is considered by substituting the built-in disposable pressure sensors (lifetime: one week) by longterm stable sensors. The selected highly accurate sensors (86A, TE Connectivity Corp.) provide amplified, linearized, calibrated and temperature compensated analog output signals. Their stainless steel construction allows for high media compatibility with corrosive liquids. Due to different sensitivity characteristics, these sensors are not fully compatible to the testing devices. To overcome this limitation, application-specific emulator interfaces were developed to connect the new sensors to the data acquisition part of the validated valve testing systems. To stay consistent with manufacturer’s device and software specification, we utilized fast analog signal conditioning, including scaling, offset calibration, out of range alarm and status indication. Compared to the originally equipped pressure sensors, emulator parameters, such as pressure range, precision, resolution and accuracy remained unchanged or even improved. For system verification the response characteristic, long-term stability and dynamic properties were examined in comparative studies
Experimental and numerical investigations of a small animal coil for ultra-high field magnetic resonance imaging (7T)
Authors: Garcia Maíra M. , Oliveira Tiago R. , Papoti Daniel , Chaim Khallil T. , Otaduy Maria C. G. , Erni Daniel , Zylka Waldemar 
Published: September 2019

Abstract
The purpose of this work was to develop and investigate a radiofrequency (RF) coil to perform image studies on small animals using the 7T magnetic resonance imaging (MRI) system, installed in the imaging platform in the autopsy room (Portuguese acronym PISA), at the University of Sao Paulo, Brazil, which is the unique 7T MRI scanner installed in South America. Due to a high demand to create new specific coils for this 7T system, it is necessary to carefully assess the distribution of electromagnetic (EM) fields generated by the coils and evaluate the patient/object safety during MRI procedures. To achieve this goal 3D numerical methods were used to design and analyse a 8-rungs transmit/receive linearly driven birdcage coil for small animals. Calculated magnetic field (B1) distributions generated by the coil were crosschecked with measured results, indicating good confidence in the simulated results. Electric field results were post-processed and predictions of local specific absorption rate (SAR) values were achieved for a spherical phantom filled with muscle-like tissue, indicating that the sample would not suffer any unsafe deposition of energy. Post mortem abdomen images obtained from a rat presented good image quality and no artifacts related to field non-homogeneity were observed.
A step towards enzyme-free tissue dissociation
Authors: Scheuermann Stefan , Schäfer Armin , Langejürgen Jens , Reis Christian 
Published: September 2019

Abstract
The future of personalized diagnostics commences on the single cell level. Even high-end technologies like Next Generation Sequencing can be improved if applied on pure single cell populations (e.g., tumor cells without contaminating stromal cells) or on a single cell level (DNA/RNA sequencing). The vast majority of these technologies need individual and preferably undistorted cells for the analytical process. Thus, decisive prerequisite for high-end analytics is to remove cells from their tissue matrix as gently as possible. This can be accomplished by an enzyme-free, fast and reproducible approach of generating pure and individual single cells from tissue samples. In this study we demonstrate the utility of a semi-automated Tissue Grinder that is compatible with standard 50 ml centrifuge tubes and standard cell strainer for mechanically, nonenzymatic and parallel processing of tissue samples. We show that without enzymatic treatment viable single-cell yields match or exceed reference enzymatic methods, while reducing processing time by at least 80%.
A new approach to quickly edit geometries and estimate stresses and displacements of implants in real-time
Authors: Fleischmann Christopher , Leher Irina , Hartwich Reinhold , Hainke Marc , Sesselmann Stefan 
Published: September 2019

Abstract
Although osteosynthesis plates rarely break, such cases still occur. Since the construction of these plates is mainly focussing on the best fit for anatomical structures, they may not provide optimal mechanical stability. It should be considered whether they might be changed in terms of e.g. hole size and number. Finite element analysis can help to estimate whether the plates will withstand loads or break. However, these analyses can be very time-consuming. To counteract this problem, a new software solution (ANSYS Discovery Live) has been established for estimation of stresses in real time. In this study the accuracy of the new software was compared to a conventional finite element analysis software solution to investigate whether this software solution provides appropriate accuracy to be used for medical applications.
MRI flow measurements with a flexible stenosis phantom
Authors: Ibbeken Alina , Gurumurthy Pragathi , Zell Fenja , Hagen Christina , Koch Martin A. , Buzug Thorsten M. 
Published: September 2019

Abstract
Obstructive sleep apnea (OSA) is a common sleep disorder caused by the collapse of the upper airway during sleep due to a shift of soft tissues. To optimise the treatment, one needs a better understanding of the patient-specific causes of OSA. As a first step, a flexible tube with a stenosis was manufactured, representing a simple model of the pharynx geometry. The phantom has been used to carry out magnetic resonance imaging (MRI) flow sensitive measurements, to investigate the flow conditions that lead to the collapse. This contribution is concerned with the comparison and analysis of the flow and phantom deformation using varying boundary conditions, such as the Reynolds number and transmural pressure.
Development of a constitutive law for numerical simulation of artificial leaflet-structures for transcatheter heart valve prostheses
Authors: Pfensig Sylvia , Arbeiter Daniela , Kohse Stefanie , Grabow Niels , Schmitz Klaus-Peter , Kaule Sebastian , Stiehm Michael , Siewert Stefan 
Published: September 2019

Abstract
While the current generation of devices for minimally invasive treatment of severe symptomatic aortic valve stenosis is based on xenogenic leaflet-material, artificial polymeric leaflet-structures represent a promising approach for future improvement of heart valve performance. For enhanced long-term success of polymeric leafletstructures, limitations regarding calcification and durability have to be addressed. The objective of the presented study was the development of a constitutive law representing the material properties of artificial polymeric leaflet-structures of transcatheter heart valve prostheses in numerical simulation to assess the in silico leaflet-performance. Mechanical characterization of cast films and nonwoven specimens of a polycarbonate based silicone elastomer were conducted by means of uniaxial tension and planar shear testing, respectively. For validation purposes, experimental data were compared with the results of finite-element analysis (FEA) using different hyperelastic models. Strain energy function for third-order ogden hyperelastic model achieved the best fit of the non-linear stress-strain behavior of the isotropic polymeric material with the experimental data. It was chosen for further FEA of valve leaflet-performance under physiological pressurization to analyze the suitability of various manufacturing processes for polymeric leafletstructures. Therefore a specific leaflet-design with a wall thickness of 400 μm was used. As a result of FEA, time dependent leaflet-deformation, leaflet coaptation surface area (CSA) and leaflet opening area (LOA) of cast and nonwoven leaflet-structures were calculated. While LOA was comparable for cast and nonwoven leaflet-structures, obtained leaflet-dynamics in a cardiac cycle under physiological pressurization demonstrated crucial influence of the manufacturing process. For nonwoven leafletstructures, an enhanced CSA could be demonstrated in comparison to cast structures. FEA using a validated hyperelastic constitutive law represents a useful tool for in silico performance evaluation of polymeric leaflet-structures under physiological loading and proves the suitability of the polymeric artificial leaflet-material for percutaneous heart valve prostheses.
Investigation of the Inertial Cavitation Activity of Sonosensitive and Biocompatible Nanoparticles for Drug Delivery Applications Employing High Intensity Focused Ultrasound
Authors: George Benedikt , Fink Michael , Ermert Helmut , Rupitsch Stefan J. , Hiltl Pia T. , Lee Geoffrey 
Published: September 2019

Abstract
An approach to improve chemotherapy, while minimizing side effects, is a local drug release close to the tumorous tissue. For this purpose, the active drug component is often bound to nanoparticles employed as drug carriers. In the present study, we investigate sonosensitive, biocompatible poly-(L)-lactic acid (PLA) nanoparticles, which shall be used as drug carriers. For drug release, High Intensity Focused Ultrasound (HIFU) will be employed to introduce inertial cavitation, which separates the active drug component from the drug carrier. The cavitation effect generates an acoustic noise signal, which characterizes the cavitation activity and is expected to serve simultaneously as an indicator for the release of the active drug component. Depending on the ultrasound frequency, different acoustic levels of the inertial cavitation activity were measured. Investigations using a setup for passive cavitation detection (PCD) deliver quantitative results regarding the frequency dependence of the cavitation activity level of nanoparticles and reference media.
Analysis of regulatory requirements of medical devices and in-vitro diagnostics worldwide for the development of an efficient procedure of registration for manufacturers of medical products
Authors: Kedwani Magdalena , Schröttner Jörg , Baumgartner Christian 
Published: September 2019

Abstract
Due to globalization and the quick development of technology, each government aims to ensure the safety and performance of products brought to their markets to protect its population. The peoples’ health state is of great significance and influenced easily by the quality of medical products. Therefore governments enact laws, directives and regulations to assure that quality. Nevertheless, these regulations can impede innovation and create trade barriers which result in an adverse effect on national economies. Where in some states no regulatory system is installed, others have highly sophisticated registration requirements that must be met. These diversities result in a challenge especially for small and medium sized companies, whose resources are often limited. [1] Manufacturers must control these diverse regulatory requirements by analyzing each market. Therefore an efficient procedure of registration should be defined that streamlines different registration requirements and ensures regulatory compliance. Next to regulatory authorities describing these requirements also harmonization groups play an important role in the design of the global regulatory landscape. Therefore also the most important harmonization groups and their current activities were investigated. The analysis showed that the impact of harmonization groups can be identified easily since new defined or updated regulatory requirements are oriented on their guideline. Still the harmonization of regulatory requirements in the medical device sector is not sufficiently enhanced. Thus the confrontation with each national regulatory system is inevitable.
Individual Avatar Feedback Creation for Assisted Motion Control
Authors: Lehmann Lars , Wiede Christian , Hirtz Gangolf 
Published: September 2019

Abstract
In Medical Training Therapy (MTT), the precise execution of the training exercises is of decisive importance for the success of the therapy. Currently, a therapist has to treat up to 15 patients simultaneously on an outpatient basis. We propose, an assistance system, can evaluate both quantity and quality of the movement performed using a target-oriented model and give recommendations for action directly to the patient by means of feedback. An avatar in traffic light colours signals in which body region an error has occurred. The individualisation of the underlying three-dimensional avatar increases the willingness of the patients to participate in the exercises without the supervision of therapist. The monitored error frequency was decreased by 50% by the assistance system.