TY  - JOUR
A1  - Topçu, Murat
A1  - Madabhushi, Gopal S.P.
A1  - Staat, Manfred
T1  - A generalized shear-lag theory for elastic stress transfer between matrix and fibres having a variable radius
JF  - International Journal of Solids and Structures
N2  - A generalized shear-lag theory for fibres with variable radius is developed to analyse elastic fibre/matrix stress transfer. The theory accounts for the reinforcement of biological composites, such as soft tissue and bone tissue, as well as for the reinforcement of technical composite materials, such as fibre-reinforced polymers (FRP). The original shear-lag theory proposed by Cox in 1952 is generalized for fibres with variable radius and with symmetric and asymmetric ends. Analytical solutions are derived for the distribution of axial and interfacial shear stress in cylindrical and elliptical fibres, as well as conical and paraboloidal fibres with asymmetric ends. Additionally, the distribution of axial and interfacial shear stress for conical and paraboloidal fibres with symmetric ends are numerically predicted. The results are compared with solutions from axisymmetric finite element models. A parameter study is performed, to investigate the suitability of alternative fibre geometries for use in FRP.
KW  - Natural fibres
KW  - Polymer-matrix composites
KW  - Biocomposites
KW  - Stress concentrations
KW  - Finite element analysis
Y1  - 2022
U6  - https://doi.org/10.1016/j.ijsolstr.2022.111464
SN  - 0020-7683
VL  - 239–240
IS  - Art. No. 111464
PB  - Elsevier
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Mandekar, Swati
A1  - Holland, Abigail
A1  - Thielen, Moritz
A1  - Behbahani, Mehdi
A1  - Melnykowycz, Mark
T1  - Advancing towards Ubiquitous EEG, Correlation of In-Ear EEG with Forehead EEG
JF  - Sensors
N2  - Wearable EEG has gained popularity in recent years driven by promising uses outside of clinics and research. The ubiquitous application of continuous EEG requires unobtrusive form-factors that are easily acceptable by the end-users. In this progression, wearable EEG systems have been moving from full scalp to forehead and recently to the ear. The aim of this study is to demonstrate that emerging ear-EEG provides similar impedance and signal properties as established forehead EEG. EEG data using eyes-open and closed alpha paradigm were acquired from ten healthy subjects using generic earpieces fitted with three custom-made electrodes and a forehead electrode (at Fpx) after impedance analysis. Inter-subject variability in in-ear electrode impedance ranged from 20 kΩ to 25 kΩ at 10 Hz. Signal quality was comparable with an SNR of 6 for in-ear and 8 for forehead electrodes. Alpha attenuation was significant during the eyes-open condition in all in-ear electrodes, and it followed the structure of power spectral density plots of forehead electrodes, with the Pearson correlation coefficient of 0.92 between in-ear locations ELE (Left Ear Superior) and ERE (Right Ear Superior) and forehead locations, Fp1 and Fp2, respectively. The results indicate that in-ear EEG is an unobtrusive alternative in terms of impedance, signal properties and information content to established forehead EEG.
KW  - in-ear EEG
KW  - correlation
KW  - forehead EEG
KW  - impedance spectroscopy
KW  - biopotential electrodes
Y1  - 2022
U6  - https://doi.org/10.3390/s22041568
SN  - 1424-8220
VL  - 22
IS  - 4
SP  - 1
EP  - 19
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Defosse, Jerome
A1  - Kleinschmidt, Joris
A1  - Schmutz, Axel
A1  - Loop, Torsten
A1  - Staat, Manfred
A1  - Gatzweiler, Karl-Heinz
A1  - Wappler, Frank
A1  - Schieren, Mark
T1  - Dental strain on maxillary incisors during tracheal intubation with double-lumen tubes and different laryngoscopy techniques - a blinded manikin study
JF  - Journal of Cardiothoracic and Vascular Anesthesia
KW  - anaesthetic complications
KW  - dental trauma
KW  - difficult airway
KW  - double-lumen tube intubation
KW  - videolaryngoscopy
Y1  - 2022
U6  - https://doi.org/10.1053/j.jvca.2022.02.017
SN  - 1053-0770
VL  - 36
IS  - 8, Part B
SP  - 3021
EP  - 3027
PB  - Elsevier
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Bhattarai, Aroj
A1  - May, Charlotte Anabell
A1  - Staat, Manfred
A1  - Kowalczyk, Wojciech
A1  - Tran, Thanh Ngoc
T1  - Layer-specific damage modeling of porcine large intestine under biaxial tension
JF  - Bioengineering
N2  - The mechanical behavior of the large intestine beyond the ultimate stress has never been investigated. Stretching beyond the ultimate stress may drastically impair the tissue microstructure, which consequently weakens its healthy state functions of absorption, temporary storage, and transportation for defecation. Due to closely similar microstructure and function with humans, biaxial tensile experiments on the porcine large intestine have been performed in this study. In this paper, we report hyperelastic characterization of the large intestine based on experiments in 102 specimens. We also report the theoretical analysis of the experimental results, including an exponential damage evolution function. The fracture energies and the threshold stresses are set as damage material parameters for the longitudinal muscular, the circumferential muscular and the submucosal collagenous layers. A biaxial tensile simulation of a linear brick element has been performed to validate the applicability of the estimated material parameters. The model successfully simulates the biomechanical response of the large intestine under physiological and non-physiological loads.
KW  - biaxial tensile experiment
KW  - anisotropy
KW  - hyperelastic
KW  - constitutive modeling
KW  - damage
Y1  - 2022
U6  - https://doi.org/10.3390/bioengineering9100528
SN  - 2306-5354
N1  - Der Artikel gehört zum Sonderheft "Computational Biomechanics"
VL  - 9
IS  - 10, Early Access
SP  - 1
EP  - 17
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Colombo, Daniele
A1  - Drira, Slah
A1  - Frotscher, Ralf
A1  - Staat, Manfred
T1  - An element-based formulation for ES-FEM and FS-FEM models for implementation in standard solid mechanics finite element codes for 2D and 3D static analysis
JF  - International Journal for Numerical Methods in Engineering
N2  - Edge-based and face-based smoothed finite element methods (ES-FEM and FS-FEM, respectively) are modified versions of the finite element method allowing to achieve more accurate results and to reduce sensitivity to mesh distortion, at least for linear elements. These properties make the two methods very attractive. However, their implementation in a standard finite element code is nontrivial because it requires heavy and extensive modifications to the code architecture. In this article, we present an element-based formulation of ES-FEM and FS-FEM methods allowing to implement the two methods in a standard finite element code with no modifications to its architecture. Moreover, the element-based formulation permits to easily manage any type of element, especially in 3D models where, to the best of the authors' knowledge, only tetrahedral elements are used in FS-FEM applications found in the literature. Shape functions for non-simplex 3D elements are proposed in order to apply FS-FEM to any standard finite element.
KW  - distorted element
KW  - ES-FEM
KW  - FS-FEM
KW  - non-simplex S-FEM elements
KW  - S-FEM
Y1  - 2022
U6  - https://doi.org/10.1002/nme.7126
SN  - 1097-0207
VL  - 124
IS  - 2
SP  - 402
EP  - 433
PB  - Wiley
CY  - Chichester
ER  - 
TY  - JOUR
A1  - Maurischat, Andreas
T1  - Algebraic independence of the Carlitz period and its hyperderivatives
JF  - Journal of Number Theory
KW  - Drinfeld modules
KW  - Periods
KW  - t-modules
KW  - Transcendence
KW  - Higher derivations
Y1  - 2022
U6  - https://doi.org/10.1016/j.jnt.2022.01.006
SN  - 0022-314X
VL  - 240
SP  - 145
EP  - 162
PB  - Elsevier
CY  - Orlando, Fla.
ER  - 
TY  - JOUR
A1  - Molinnus, Denise
A1  - Janus, Kevin Alexander
A1  - Fang, Anyelina C.
A1  - Drinic, Aleksander
A1  - Achtsnicht, Stefan
A1  - Köpf, Marius
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Thick-film carbon electrode deposited onto a biodegradable fibroin substrate for biosensing applications
JF  - Physica status solidi (a)
N2  - This study addresses a proof-of-concept experiment with a biocompatible screen-printed carbon electrode deposited onto a biocompatible and biodegradable substrate, which is made of fibroin, a protein derived from silk of the Bombyx mori silkworm. To demonstrate the sensor performance, the carbon electrode is functionalized as a glucose biosensor with the enzyme glucose oxidase and encapsulated with a silicone rubber to ensure biocompatibility of the contact wires. The carbon electrode is fabricated by means of thick-film technology including a curing step to solidify the carbon paste. The influence of the curing temperature and curing time on the electrode morphology is analyzed via scanning electron microscopy. The electrochemical characterization of the glucose biosensor is performed by amperometric/voltammetric measurements of different glucose concentrations in phosphate buffer. Herein, systematic studies at applied potentials from 500 to 1200 mV to the carbon working electrode (vs the Ag/AgCl reference electrode) allow to determine the optimal working potential. Additionally, the influence of the curing parameters on the glucose sensitivity is examined over a time period of up to 361 days. The sensor shows a negligible cross-sensitivity toward ascorbic acid, noradrenaline, and adrenaline. The developed biocompatible biosensor is highly promising for future in vivo and epidermal applications.
KW  - biocompatible materials
KW  - biodegradable electronic devices
KW  - biosensors
KW  - carbon electrodes
KW  - glucose
Y1  - 2022
U6  - https://doi.org/10.1002/pssa.202200100
SN  - 1862-6319
N1  - Corresponding author: Michael J. Schöning
VL  - 219
IS  - 23
SP  - 1
EP  - 9
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Schüller-Ruhl, Aaron
A1  - Dinstühler, Leonard
A1  - Senger, Thorsten
A1  - Bergfeld, Stefan
A1  - Ingenhag, Christian
A1  - Fleischhaker, Robert
ED  - Mackenzie, Jacob
T1  - Direct fabrication of arbitrary phase masks in optical glass via ultra-short pulsed laser writing of refractive index modifications
JF  - Applied Physics B
N2  - We study the possibility to fabricate an arbitrary phase mask in a one-step laser-writing process inside the volume of an optical glass substrate. We derive the phase mask from a Gerchberg–Saxton-type algorithm as an array and create each individual phase shift using a refractive index modification of variable axial length. We realize the variable axial length by superimposing refractive index modifications induced by an ultra-short pulsed laser at different focusing depth. Each single modification is created by applying 1000 pulses with 15 μJ pulse energy at 100 kHz to a fixed spot of 25 μm diameter and the focus is then shifted axially in steps of 10 μm. With several proof-of-principle examples, we show the feasibility of our method. In particular, we identify the induced refractive index change to about a value of Δn=1.5⋅10−3. We also determine our current limitations by calculating the overlap in the form of a scalar product and we discuss possible future improvements.
Y1  - 2022
U6  - https://doi.org/10.1007/s00340-022-07928-2
SN  - 1432-0649 (Online)
SN  - 0946-2171 (Print)
N1  - Corresponding author: Robert Fleischhaker
VL  - 128
IS  - Article number: 208
SP  - 1
EP  - 11
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Eggert, Mathias
A1  - Kreuzer, Vincent
T1  - Sprachsteuerung im Gesundheitswesen – Anforderungen und Auswahl geeigneter Anbieter
T1  - Voice control in healthcare—requirements and provider selection
JF  - HMD Praxis der Wirtschaftsinformatik
N2  - Das Gesundheitswesen ist konfrontiert mit steigenden Kosten und einer immer schwieriger werdenden Personalsituation. Zeitgleich versprechen moderne Sprachsteuerungssysteme Prozesse in Arztpraxen und Krankenhäusern zu verschlanken und Vorgänge zu beschleunigen. Dennoch wird derzeit der Einsatz von Sprachsteuerungssystemen in Arztpraxen oder Krankenhäusern nur selten beobachtet, was auch an den besonders strengen Datenschutzauflagen der Datenschutzgrundverordnung (DSGVO) liegt. Darüber hinaus wirft die niedrige Nutzungsrate die Frage nach den konkreten Anforderungen und ihrer Umsetzbarkeit auf, was durch den vorliegenden Beitrag adressiert wird, indem die Ergebnisse von Interviews mit acht medizinischen Fachexperten ausgewertet werden. Ergänzend wird die technische Umsetzbarkeit einzelner Anforderungen mit unterschiedlichen Cloud-Anbietern erprobt.
KW  - Gesundheitswesen
KW  - Sprachsteuerung
KW  - Sprachassistent
KW  - Anforderungen
KW  - Umsetzbarkeit
Y1  - 2022
SN  - 2198-2775
U6  - https://doi.org/10.1365/s40702-022-00919-z
SN  - 1436-3011
N1  - Corresponding author: Mathias Eggert
VL  - 59
SP  - 1640
EP  - 1652
PB  - Springer Vieweg
CY  - Wiesbaden
ER  - 
TY  - JOUR
A1  - Philipp, Mohr
A1  - Efthimiou, Nikos
A1  - Pagano, Fiammetta
A1  - Kratochwil, Nicolaus
A1  - Pizzichemi, Marco
A1  - Tsoumpas, Charalampos
A1  - Auffray, Etiennette
A1  - Ziemons, Karl
T1  - Image reconstruction analysis for positron emission tomography with heterostructured scintillators
JF  - IEEE Transactions on Radiation and Plasma Medical Sciences
N2  - The concept of structure engineering has been proposed for exploring the next generation of radiation detectors with improved performance. A TOF-PET geometry with heterostructured scintillators with a pixel size of 3.0×3.1×15 mm3 was simulated using Monte Carlo. The heterostructures consisted of alternating layers of BGO as a dense material with high stopping power and plastic (EJ232) as a fast light emitter. The detector time resolution was calculated as a function of the deposited and shared energy in both materials on an event-by-event basis. While sensitivity was reduced to 32% for 100 μm thick plastic layers and 52% for 50 μm, the CTR distribution improved to 204±49 ps and 220±41 ps respectively, compared to 276 ps that we considered for bulk BGO. The complex distribution of timing resolutions was accounted for in the reconstruction. We divided the events into three groups based on their CTR and modeled them with different Gaussian TOF kernels. On a NEMA IQ phantom, the heterostructures had better contrast recovery in early iterations. On the other hand, BGO achieved a better contrast to noise ratio (CNR) after the 15th iteration due to the higher sensitivity. The developed simulation and reconstruction methods constitute new tools for evaluating different detector designs with complex time responses.
KW  - TOF PET
KW  - Heterostructure
KW  - Metascintillator
KW  - Multiple TOF kernels
KW  - Image Reconstruction
Y1  - 2022
U6  - https://doi.org/10.1109/TRPMS.2022.3208615
SN  - 2469-7311
SN  - 2469-7303
VL  - 7
IS  - 1
SP  - 41
EP  - 51
PB  - IEEE
CY  - New York, NY
ER  -