bluuebunny/crossref_metadata_2025_split huggingface dataset:
A modular in vitro flow model to analyse blood-surface interactions under physiological conditions
Authors: Valtin Juliane , Behrens Stephan , Maitz Manfred F. , Schmieder Florian , Sonntag Frank , Werner Carsten 
Published: December 2021

Abstract
Newly developed materials for blood-contacting devices need to undergo hemocompatibility testing to prove compliance with clinical requirements. However, many current in vitro models disregard the influence of flow conditions and blood exchange as it occurs in vivo. Here, we present a flow model which allows testing of blood-surface interactions under more physiological conditions. This modular platform consists of a triple-pump-chip and a microchannel-chip with a customizable surface. Flow conditions can be adjusted individually within the physiological range. A performance test with whole blood confirmed the hemocompatibility of our modular platform. Hemolysis was negligible, inflammation and hemostasis parameters were comparable to those detected in a previously established quasi-static whole blood screening chamber. The steady supply of fresh blood avoids secondary effects by nonphysiological accumulation of activation products. Experiments with three subsequently tested biomaterials showed results similar to literature and our own experience. The reported results suggest that our developed flow model allows the evaluation of blood-contacting materials under physiological flow conditions. By adjusting the occurring wall shear stress, the model can be adapted for selected test conditions.
Fluid dynamics in the human heart: Altered vortex formation and wash-out in mitral regurgitation simulations
Authors: Brenneisen Jochen , Wentzel Carlo , Karwan Farokh , Dössel Olaf , Loewe Axel 
Published: December 2021

Abstract
Mitral regurgitation alters the flow conditions in the left ventricle. To account for quantitative changes and to investigate the behavior of different flow components, a realistic computational model of the whole human heart was employed in this study. While performing fluid dynamics simulations, a scalar transport equation was solved to analyze vortex formation and ventricular wash-out for different regurgitation severities. Additionally, a particle tracking algorithm was implemented to visualize single components of the blood flow. We confirmed a significantly lowered volume of the direct flow component as well as a higher vorticity in the diseased case.
Traditional versus Neural Network Classification Methods for Facial Emotion Recognition
Authors: Arabian Herag , Wagner-Hartl Verena , Moeller Knut 
Published: December 2021

Abstract
Facial emotion recognition (FER) is a topic that has gained interest over the years for its role in bridging the gap between Human and Machine interactions. This study explores the potential of real time FER modelling, to be integrated in a closed loop system, to help in treatment of children suffering from Autism Spectrum Disorder (ASD). The aim of this study is to show the differences between implementing Traditional machine learning and Deep learning approaches for FER modelling. Two classification approaches were taken, the first approach was based on classic machine learning techniques using Histogram of Oriented Gradients (HOG) for feature extraction, with a k-Nearest Neighbor and a Support Vector Machine model as classifiers. The second approach uses Transfer Learning based on the popular “Alex Net” Neural Network architecture. The performance of the approaches was based on the accuracy of randomly selected validation sets after training on random training sets of the Oulu-CASIA database. The data analyzed shows that traditional machine learning methods are as effective as deep neural net models and are a good compromise between accuracy, extracted features, computational speed and costs.
Quantitative assessment of ventricular far field removal techniques for clinical unipolar electrograms
Authors: Lorenz Nick Johannes , Unger Laura Anna , Luik Armin , Dössel Olaf 
Published: December 2021

Abstract
The incidence of atrial tachycardia steadily increases in industrial nations. During invasive electrophysiological studies, a catheter measures electrograms within the atrium to assist detailed diagnosis and treatment planning. With unipolar and bipolar electrograms, two different acquisition modes are clinically available. Unipolar electrograms have several advantages over bipolar electrograms. However, unipolar electrograms are more affected by noise and the ventricular far field. Therefore, only bipolar electrograms are typically used in clinical settings. A recently published ventricular far field removal technique models the ventricular far field by a set of dipoles and yielded promising results in a simulation study. However, the method lacks quantitative clinical validation. Therefore, we adapted the technique to clinical needs and applied it to data sets of two patients using four different lengths of the removal window. Results were compared quantitatively by a tailored residual error measure. The used method resulted in a median reduction of the ventricular far field by approximately 89% using a removal window of optimal length for both patients. The results showed that the dipole method provides an alternative to other VFF removal techniques in clinical practice because it can reveal AA originally hidden by VFF without leading to a prolongation of the electrophysiological study.
Rapid Prototyping of Moulds for PDMS-based Microfluidic Chips
Authors: Schmidt-Speicher Leona M. , Mellert Tobias , Hurtado Rivera Andrea C. , Länge Kerstin , Ahrens Ralf , Guber Andreas E. 
Published: December 2021

Abstract
To shorten the production time for PDMS-moulds by additive manufacturing (AM) several 3D printers have been investigated in comparison to standard micro-milling by producing benchmark structures. These are evaluated regarding their shape accuracy, the transparency of the casted PDMS which is linked to the surface quality of the mould, and the production time until the moulds are ready to use. Even though the additively manufactured moulds showed significantly better surface quality and shorter production time, the necessary shape accuracy for non-square-structures or structures with < 250 μm edge length could not be achieved due to limiting factors like nozzle diameter, size of the digital micromirror device or spot size of the LCD-panel.
How to Support Students in Maximizing their Outcome with Online Cooperation?
Authors: Benninghoff Mark J. , Isfort Peter , Baumann Martin 
Published: December 2021

Abstract
During the last year, student cooperation has shifted to the digital space. Chats, videoconferencing and online collaboration tools replace physical meetings and face-to-face interactions. While many online tools provide sophisticated technologies to share screens and co-edit manuscripts, the support of collaborative thinking, learning and even fooling around is still underdeveloped, but remains a valuable resource. This study traces whether the given level of instruction details influences the collaboration effectiveness among student working groups in a practical course in Biomedical Engineering. Within the semester’s practical course of Introduction into Medicine, participating students were divided into three groups (A, B and C) of each 4 to 6 students and had to collaborate on a clinical case. Groups A received detailed information and rules on online collaboration, B less detailed information and C only basic technical information. Each group was asked to fulfil an additional pre- and post-task before and after the semester’s practical course. These tasks consisted of solving combinatory puzzles based on isolated information bits and hints that were distributed among the group members. The groups differed only in the instructions they received to fulfil the task. During their work phases, all groups were observed. The study was conducted twice with different student cohorts. School grades were assigned representing 1 for the best up to 6 for the worst performance. The following averaged results were found: Groups B received the best grades (average 1,5 for winter term and average 1,6 for summer term). Second best performance was shown by the groups A (average 2,14 for winter term and average 1,75 for summer term) and finally groups C performed worst (average 2.10 for winter term and average 1,85 for summer term). In the taken times to solve the puzzle tasks, groups B showed up to be best in the summer term and groups A in the winter term. In all categories, groups C delivered the worst grades in average. The results of this study support that it is most reasonable to aid student online collaboration by providing detailed instructions or at least a few hints and instruct them to create their own rules for online collaboration. The results further support that the cooperation gets worse without suggesting any rules or instructions and that student age possesses a negligible influence.
Electrical Impedance Tomography might be a Practical Tool to Provide Information about COVID-19 Pneumonia Progression
Authors: Chen Rongqing , Lovas András , Benyó Balázs , Moeller Knut 
Published: December 2021

Abstract
COVID-19 induced acute respiratory distress syndrome (ARDS) could have two different phenotypes, which might have different response and outcome to the traditional ARDS positive end-expiration pressure (PEEP) treatment. The identification of the different phenotypes in terms of the PEEP recruitment can help improve the patients’ outcome. In this contribution we reported a COVID-19 patient with seven-day electrical impedance tomography monitoring. From the conductivity distribution difference image analysis of the data, a clear course developing trend can be observed in addition to the phenotype identification. This case might suggest that EIT can be a practical tool to identify phenotypes and to provide progressive information of COVID-19 pneumonia.
Carotid Sound Signal Artifact Detection based on Discrete Wavelet Transform Decomposition
Authors: Fuentealba Patricio , Salvi Rutuja , Henze Jasmin , Burmann Anja , Boese Axel , Ataide Elmer , Spiller Moritz , Illanes Alfredo , Friebe Michael 
Published: December 2021

Abstract
Auscultation methods allow a non-invasive diagnosis of cardiovascular diseases like atherosclerosis based on blood flow sounds of the carotid arteries. Since this process is highly dependent on the clinician’s experience, it is of great interest to develop automated data processing techniques for objective assessment. We have recently proposed a computerassisted auscultation system that we use to acquire carotid blood flow sounds. In this work, we present an approach for detecting artifacts within the blood flow sound caused by swallowing or coughing events. For this purpose, we first decompose the signal using a discrete wavelet transform (DTW). Then, we compute an energy ratio between the DWT scales associated with the signal information with and without artifacts using a sliding window of 1 s length. Evaluation based on Kruskal-Wallis and Wilcoxon rank-sum tests shows a statistically significant difference (p-value<.0001) between the signal with and without artifact. Therefore, the proposed method allows the identification of the studied signal artifacts.
A multi-purpose phantom kit for magnetic particle imaging
Authors: Löwa Norbert , Hoffmann Rebecca , Gutkelch Dirk , Kosch Olaf , Dutz Silvio , Wiekhorst Frank 
Published: December 2021

Abstract
Phantoms are essential tools for the development and characterization of Magnetic Particle Imaging (MPI), an imaging technique that can quantitatively map the spatial distribution of magnetic nanoparticles (MNP). The objective of this study was to develop and validate a modular MPI phantom kit with high versatility for platform-independent quality assurance and the assembling of defined geometries in MPI. It was shown that the developed MPI phantom kit can be used for both application scenario testing and quality assurance in MPI which provides the basis for future reference phantoms to directly compare existing scanners within the MPI community.
Physical characterization of biomedical magnetic nanoparticles using multi-detector centrifugal field-flow fractionation
Authors: Remmo Amani , Löwa Norbert , Peter Julija , Wiekhorst Frank 
Published: December 2021

Abstract
The unique magnetic properties of magnetic nanoparticles (MNP) combined with their small size already led to numerous medical applications. Accurate determination of their magnetic properties is a key requirement enquired by users, that is impeded by the ever-present distribution of MNP sizes. Field flow fractionation (FFF) techniques may help to overcome these limitations by first separating the particles before characterization. In this study, we demonstrate the use of centrifugal FFF coupled to online detectors for fractionation, structural, and magnetic characterization of MNP. The primary goal is to establish a reproducible centrifugal FFF (CF3) method for MNP fractionation We show that CF3 has the same capability as other FFF techniques in resolving the bimodal hydrodynamic size distribution present in the commercial MNP system Resovist® but is faster and more straightforward through its technical approach.
Twisted string actuation with position feedback for robotic endoscopy
Authors: Schlesiger Davina , Giacoppo Giuliano A. , Schäfer Max B. , Pott Peter P. 
Published: December 2021

Abstract
A twisted string actuator (TSA) is a small, strong, lightweight, and low-cost gear, transforming rotation into a linear pulling movement. The TSA consists of two or more strings that are twisted along their common longitudinal axis. The helix formed in this process becomes shorter the further the bundle is twisted. A possible application is a tendon-based endoscopic robot. To control the movement of the endoscope, a precise contraction of the tendon is necessary. Since the strings of the TSA show an elastic behaviour, position feedback is needed to determine the exact movement of the TSA. In this paper, a TSA with a closed-loop position control by a low-cost displacement sensor is presented.
Nintedanib suppresses expression of extracellular matrix proteins in TGF-β1-stimulated primary human fibroblasts of the Tenon
Authors: Brietzke Andreas , Guthoff Rudolf F. , Grabow Niels , Stahnke Thomas 
Published: December 2021

Abstract
The development of strategies for fibrosis prevention is a perpetual cutting the edge challenge, especially in ophthalmologic fistulating surgery. Stenosis of liquid draining implants but also fibrotic activation of implant-associated tissues are major clinical examples for fibrosis induced implant failure. Implant coating or incorporation of antifibrotic agents offer a promising approach to minimise failure rates. Nintendanib is a drug that has been successfully used for the treatment of ideopathic pulmonary fibrosis since 2015. In this study, we evaluated the suitability of Nintedanib for ophthalmic therapeutic treatment. Therefore, the antifibrotic potential of the active substance was tested with a fibrotic cell culture model on primary fibroblasts of the Tenon (hTF) in vitro. The concentration of 10μM Nintedanib demonstrated a marginal effect on cell viability but coincidently diminished cell proliferation remarkably. Both, immunocytochemical and Western blot analyses revealed a significant inhibitory effect of Nintedanib on the TGF-β1 induced expression of the extracellular matrix (ECM) components fibronectin and collagen. Moreover it supressed the expression and formation of stress fibres of the fibrotic marker protein alpha smooth muscle actin (α-SMA).
Drug-eluting coating of extruded polymeric tubular microstructures
Authors: Sahmel Olga , Siewert Stefan , Bajer Dalibor , Reske Thomas , Arbeiter Daniela , Friederike Kreiner Christine , Guthoff Rudolf , Schmitz Klaus-Peter , Grabow Niels 
Published: December 2021

Abstract
Extrusion is a common manufacturing process for semi-finished polymer products in various biomedical applications. Extrusion enables processing of a wide range of biomaterials, as well as different cross-sectional geometries. Furthermore, feasibility of drug elution, as it is used for a variety of medical devices, for example microstents for minimally invasive glaucoma therapy, was assessed. The current study deals with manufacturing of polymeric microtubes by extrusion processing. Semi-finished products were made of biodegradable poly-L-lactide (PLLA) and a non-biodegradable polycarbonate-based silicone elastomer (SIL) and covered with a polymer/drug combination, with resveratrol as active ingredient. Three different concentrations of polymer/resveratrol were applied by means of spray-coating. The release behavior of active ingredient was analyzed in vitro at 37°C and showed a correlation between the amount of drug and release time. With higher drug content, a faster release was observed. In addition, the release from SIL was faster compared with PLLA.
Investigation of auditory neuronal survival and outgrowth using a cochlear implant in an artificial cochlear model
Authors: Abdoul Tchadarou , Schwieger Jana , Lenarz Thomas , Nogueira Waldo , Scheper Verena 
Published: December 2021

Abstract
Cochlear implants (CI) can restore hearing to people suffering from sensorineural hearing loss. The CI uses an array of electrodes inserted in the scala tympani to stimulate the spiral ganglion neurons (SGN), which are located in the bony axis of the inner ear. The spatial distance between the electrodes and the SGN results in spread of excitation and unfocused stimulation. This distance could be bypassed by a neurite outgrowth towards the CI. In order to establish a culture system for the development of novel strategies for CI optimization, a neurite outgrowth chamber (NOC) allowing clinically relevant electrical stimulation paradigms was developed using fused deposition modelling. It was made out of biocompatible UV-curing silicone. The NOC was equipped with a slot to insert the electrode array into a scala tympani compartment whereas SGN isolated from postnatal rats were cultured in a neighbouring region mimicking the Rosenthal’s canal. Sound delivered through loudspeakers playing a radio program was captured by the CI sound processor, positioned outside the NOC, for 17 hours daily during a four-day period. The NOCs were tightly sealed and the electrode array could be positioned in the scala tympani compartment. The experimental setup allowed cell cultivation and the stimulation resulted in a significantly increased neurite length of around 36% while explant area and neurite number did not differ to the negative control (NC). A new in vitro testing system which considers the anatomy of the cochlea and clinic stimulation conditions has been developed and validated. The validation experiments resulted in increased neurite length. This indicates a progress in bridging the anatomical gap between electrode and stimulated neurons.
In vitro release of chlorhexidine from UV-cured PEGDA drug delivery scaffolds
Authors: Rekowska Natalia , Riess Alexander , Mau Robert , Eickner Thomas , Seitz Hermann , Grabow Niels , Teske Michael 
Published: December 2021

Abstract
Drug delivery systems (DDS) are suitable for controlled local drug release in order to ensure safety and effectiveness of medical treatment. The choice and characterization of biomaterials that can be used as a DDS is a challenging step in the administration of drugs. Novel 3D printing photopolymerization-based techniques create the possibility for designing individual, patient-tailored DDS. Poly(ethylene glycol) diacrylate`s (PEGDA`s) chemical and biological properties make it a suitable photopolymerisable resin for the creation of DDS. This study describes the in vitro release of the antiseptic drug chlorhexidine (CHX) from UV-cured PEGDA and its copolymers (butanediol diacrylate, pentaerythritol triacrylate and pentaerythritol tetraacrylate) samples. A substantial decrease in CHX release with increasing concentration of the copolymers in comparison to pure PEGDA was obtained only for butanediol diacrylate. For pentaerythritol triacrylate and pentaerythritol tetraacrylate only a tendency of decreased CHX release with increasing concentration was detected. Therefore, release profiles of the low molecular drug CHX from PEGDA samples could be modified by the addition of copolymers with a different number of acrylate groups and PEGDA can be considered as a promising candidate for the preparation of novel DDS.
Pandemic Robot
Authors: Bauer Jochen , Dengler Simon , Faubel Leoni , Franke Jörg , Ristok Bruno , Struck Matthias , Frischholz Robert , Wittenberg Thomas 
Published: December 2021

Abstract
Robot-based service platforms are currently establishing themselves as new and affordable variants for supporting care in elderly, retirement and nursing homes. Many are open multifunctional platforms, which can potentially be integrated into such environments, if the necessary infrastructure is available. Furthermore, many services can be realized on these platforms, which can be used to foster distant interactions between inhabitants and care-providers, while simultaneously keeping up the quality of life of the inhabitants. Open mobile robotic platforms allow the extension with adequate new sensors. To detect infectious diseases of residents and healthcare-professionals, optical sensors can be used for the assessment of vital data such as heartrate and heartrate variability, respiratory rate, SpO2 or temperature. Additionally, you can consider demographic data (age, gender, constitution) of the observed person for the optical assessment, i.e. obtained by facial image analysis. As these mobile platforms are also equipped for telepresence, in case of detecting an infected person, these systems support video conferencing with their built-in cameras and microphones. Finally, the interaction with the electronic care record is necessary to upload all acquired vital data and further relevant information. All the named technologies have been under investigation in the past years and are currently moving from laboratory settings to real-world scenarios. Nevertheless, the smooth integration of all components into one system architecture in combination with (AI-based) data analysis are still open issues.