bluuebunny/crossref_metadata_2025 huggingface dataset:
Machine learning based identification of elderly persons with cognitive impairment using dynamic time warping
Authors: Kondragunta Jyothsna , Seidel Roman , Hirtz Gangolf
Published: February 2021

Cognitive changes in general occur with normal aging. This may lead to the prevalence and effect of age associated diseases. The understanding and identification of these age-related cognitive impairments is an important aspect in elderly population. This leads in the simple case, supporting a functional independence of the elderly and in a complex case, an early identification of dementia in advance. One important change with normal aging is the decline in gait functionality. The decline in gait is more visible in the elderly with more cognitive impairment during dual cognitive tasks, multi-tasking exercises. For the classification of the healthy elderly from the elderly having cognitive impairments, the gait data of the elderly is acquired through Kinect V2. A waking trial of 5m long is used to collect the gait data. 3D based pose estimation using the depth data is performed. Gait parameters and gait cycles of the individual elderly are estimated. In this paper, Dynamic Time Warping (DTW) algorithm is used to compare the patterns of the gait cycles of the individual in different trails such as Regular Gait 1 (RG1), Regular Gait 2 (RG2), Counting Backward 1 (CB1), Counting Backward 3 (CB3), Fast Gait (FG) and Words with Special Letters (WSPL). The identified cross levels along with the estimated gait parameters are used for training the machine learning algorithm. Support Vector Machines (SVM) were used for the classification of the elderly persons with or without cognitive impairments. The experiment results proved that such a classification of cognitive impairment levels using 3D pose estimation and machine learning helps in future for the identification of dementia in advance.
Data Recording Framework for Physiological and Surgical Data in Operating Theatres
Authors: Abdulbaki Alshirbaji Tamer , Aldeen Jalal Nour , Möller Knut
Published: February 2021

Integrated operating rooms typically connect medical devices providing the clinical user a complete control over environment, device setting and digital management of intervention-related data. Consequently, the opportunity to analyse and present data from different perspectives and with different objectives has arisen. The available integrated ORs are so far designed as closed systems, thus connecting coexisting systems from different manufactures e.g. anaesthesia machines and surgical devices is demanding. The purpose of this project is to facilitate data collection from anaesthesiology, patient monitoring and surgical devices. The study is performed on laparoscopic procedures, and the data are going to be recorded at the Schwarzwald-Baar Klinikum (SBK) in Villingen-Schwenningen (Germany). Therefore, this part of the project focuses on the overall architecture for collecting data in the operating theatre at the SBK. In this work, (i) the system architecture (i.e. hardware components), (ii) software architecture and (iii) required protocols for synchronous recording of data in the OR are described. The proposed framework demonstrates that signal recording is possible with variety of devices at different sampling rates during surgical procedure.
Cell-derived Extracellular Matrix as maintaining Biomaterial for adipogenic differentiation
Authors: Kluger Petra J. , Nellinger Svenja , Heine Simon , Volz Ann-Cathrin
Published: February 2021

The extracellular matrix (ECM) naturally surrounds cells in humans, and therefore represents the ideal biomaterial for tissue engineering. ECM from different tissues exhibit different composition and physical characteristics. Thus, ECM provides not only physical support but also contains crucial biochemical signals that influence cell adhesion, morphology, proliferation and differentiation. Next to native ECM from mature tissue, ECM can also be obtained from the in vitro culture of cells. In this study, we aimed to highlight the supporting effect of cell-derived- ECM (cdECM) on adipogenic differentiation. ASCs were seeded on top of cdECM from ASCs (scdECM) or pre-adipocytes (acdECM). The impact of ECM on cellular activity was determined by LDH assay, WST I assay and BrdU assay. A supporting effect of cdECM substrates on adipogenic differentiation was determined by oil red O staining and subsequent quantification. Results revealed no effect of cdECM substrates on cellular activity. Regarding adipogenic differentiation a supporting effect of cdECM substrates was obtained compared to control. With these results, we confirm cdECM as a promising biomaterial for adipose tissue engineering.
Study of poly(L-lactide) using Fast Scanning Calorimetry
Authors: Arbeiter Daniela , Oschatz Stefan , Illner Sabine , Grabow Niels
Published: February 2021

Fast scanning calorimetry (FSC) is an effective analytical tool to characterize the thermal properties of polymers. Heating rates up to 100 000 K/s allow studies at time scales inaccessible with conventional calorimeters, whose rates are typically less than about 0.5 K/s. Recent studies have successfully demonstrated methods for obtaining quantitative analysis of thermal properties of polymer samples using chip-based FSC. Therefore very small sample sizes, such as particles or nonwovens, can be characterized. In this study, we investigated the thermal properties of poly(L-lactide) PLLA with FSC compared to the results from standard DSC methods. PLLA specimens were fabricated via solution casting and needle electrospinning. The results suggest a significant influence of heating rates on the melting temperature of PLLA. The results show that different fabrication methods lead to changes in crystallinity and that FSC results are not completely comparable with standard DSC measurements.
Wear and corrosion in medical applications
Authors: Markhoff Jana , Grabow Niels
Published: February 2021

Biomaterials applied to replace or restore body functions are exposed to different mechanical forces and corrosion processes due to body fluids, which might result in the generation of corrosion products, wear debris and particles potentially leading to inflammation and inhibition or loss of function. This brief review will give a short overview about the processes of wear generation and corrosion, the occurrence of the respective wear products in different medical applications and their biological influences. Wear and corrosion are important factors that control and determine the long-term clinical performance of a biomaterial.
Development of an in vitro measurement method for improved assessment of the side branch expansion capacity
Authors: Rosam Paula , Borowski Finja , Stiehm Michael , Schmitz Klaus Peter , Keiler Jonas , Wree Andreas , Öner Alper Ö , Schmidt Wolfram
Published: February 2021

The expansion capacity and accessibility of the side branch is essential for the stenting of complex bifurcations. Since previous measurement methods only provide limited information based on geometrical data of stent cells, a new measurement approach was developed which considers the mechanical deformation capacity of the stent design. This approach provides essential information on the stent with regard to the application of bifurcation stenting. Four different commercially available coronary stents (nominal diameter 3.0 mm) were dilated and a central strut cell was over-expanded by means balloon catheters of increasing nominal diameter (2.0 to 5.0 mm). After balloon inflation, the remaining cell size was investigated for maximum cell diameter and strut fractures. Large expansion capacity without cell damage is taken as a measure of the accessibility of the side branch. In none of the expansion experiments the desired target size could be achieved, which is due to the elastic recoil of the stent cells. Deviations from the target diameter between 14-38% were determined. However, larger diameters also showed a constriction of the balloon, so that in some cases the target diameter could not be achieved at all. No strut fractures occurred even at maximum balloon diameter and pressure (5.0 mm noncompliant balloons). As a result the side branch accessibility differs depending on the individual stent designs. No particular risk for the stent was found by extensive overdilatation.
Printing of vessels for small functional tissues – a preliminary study
Authors: Polley Christian , Kussauer Sophie , David Robert , Barkow Phillip , Mau Robert , Seitz Hermann
Published: February 2021

Vascularization of bioprinted constructs to ensure sufficient nutrient supply still remains to be a significant task in the tissue engineering community. In order to mimic functional tissue, it is necessary to be able to print vessels in various size scales, which places particularly high demands on the 3D printing technology and materials. In this preliminary study, we focused on the production of small hollow structures for the application in small functional units of living tissue. To fabricate hollow structures, the freeform reversible embedding of suspended hydrogels (FRESH) - method was utilized (Hinton et al.). A sodium alginate solution (5 % w/v) was used as a bioink. The scaffolds were fabricated with the Allevi 1 (Allevi Inc., PA, USA), a pneumatic extrusion-based bioprinter and plotted into a gelatine slurry serving as fugitive support. For first cell experiments, the bioink was loaded with immortalized mouse HL1-cells. A proof of concept could be shown since we were able to reliably create vessel-like structures with an inside diameter of 1.2 to 1.6 mm, a length of up to 8 mm and a wall thickness of 0.4 to 0.6 mm. In this study, the geometric requirements to print hollow structures for small functional tissues could be achieved. To expand the field of applications the resolution of the printing process has to be further improved. Moreover, the cell density should be increased to reach physiological cell numbers and extended with endothelial cells.
Evaluation of antibacterial properties of polyelectrolyte multilayer coatings by norm tests
Authors: Djanklich Leyla , Andreeva Tonya , Xiong Xin , Krastev Rumen , Kemkemer Ralf
Published: February 2021

Medical implants play a central role in modern medicine and both, naturally derived and synthetic materials have been explored as biomaterials for such devices. However, when implanted into living tissue, most materials initiate a host response. In addition, implants often cause bacterial infections leading to complications. Polyelectrolyte multilayer (PEM) coatings can be used for functionalization of medical implants improving the implant integration and reducing foreign body reactions. Some PEMs are also known to show antibacterial properties. We developed a PEM coating suggesting that it can decrease the risk of bacterial infections occurring after implantation while being highly biocompatible. We applied two different standard tests for evaluating the PEM’s antibacterial properties, the ISO norm (ISO 22196) and one ASTM norm (ASTM E2180) test. We found a reduction of bacterial growth on the PEM but to a different degree depending on the testing method. This result demonstrates the need for defining proper method to evaluate antibacterial properties of surface coatings.
Comparison of open versus endovascular surgical treatment of abdominal aortic aneurysm
Authors: Kischkel Sabine , Bünger Carsten M.
Published: February 2021

Abdominal aortic aneurysm (AAA) is a common condition of increasing prevalence, particularly among older men. An AAA is defined as a permanent dilation of the abdominal aorta, with a diameter greater than 30 mm or a diameter greater than 50% of the aortic diameter at the level of the diaphragm. As the size of the aneurysm increases, so does the risk of rupture. Therefore, prophylactic repair with insertion of a prosthetic graft is offered. Since 1951 traditional open aneurysm repair (OAR) was reported and minimally invasive endovascular repair (EVAR) was first reported in 1986. Data from four randomized controlled trials (EVAR-1, DREAM, OVER, ACE) for abdominal aortic aneurysm, which enrolled almost 3000 patients, in a period from 1999 to 2008, were summarized. In addition, registry databases on the treatment of AAA of average 4000 patients per year, based from 2015 to 2018 of the German Institute for Vascular Medicine Healthcare Research of the German Society for Vascular Surgery and Vascular Medicine, were compared. The EVAR procedure for AAA showed a lower risk of perioperative mortality but was associated with a higher cardiovascular and aneurysm-related complication rate. In particular, patients aged 80 years or older benefited from EVAR since the 30-day mortality of patients receiving OAR was higher. In mid-term and long-term follow-up there were no differences in survival after endovascular and open aortic repair. Overall, it depends on the respective underlying disease and anatomy which of the two approaches is to be preferred. In conclusion, both treatment options can be considered as equal and can be offered to patients.
Polyimide-based Thin Film Conductors for High Frequency Data Transmission in Ultra- Conformable Implants
Authors: Szabo Benedikt , Gueli Calogero , Eickenscheidt Max , Stieglitz Thomas
Published: February 2021

Application-specific integrated circuits (ASICs) embedded in polymers have been subject in implant manufacturing for the recent years. The increased functionality combined with good biocompatibility due to flexibility of thin implants makes them interesting for further studies. Thin-film ASICs can be used for the recording and processing of a high amount of biological signals, improving the performance of neural implants. Fabrication and analysis of gold and platinum thin-film connections are subject of this study, especially their capability as high frequency data transmission lines. Three layers of polyimide are used as flexible substrate and insulator of the traces. Various test structures were designed and fabricated, to investigate the resistance and reactance up to GHz frequencies, crosstalk and influence of vias between metallization layers. All conducting structures have a comparable design with a length of 50 mm and a metal thickness of 300 nm, while the line widths were varied. In this configuration gold and platinum thinfilm conductors are both suitable for high-frequency data transmission up to 100 MHz. This transmission frequency limit and impedances are unaffected by a wet environment and in accelerated aging tests. However, both metals show a high pass filter behavior, whose frequency behavior is mostly dependent by the self-inductance and resistance. A simplified ideal transmission model predicts the electrical behavior sufficiently and can be used to design the favored line impedance matching input impedances of the connected ASICs.
Deep learning-based recognition of cell structures in fluorescence microscopy sequences with respect to their morphology on cells infected with Marburg virus
Authors: Schmidt Dennis , Rausch Andreas , Schanze Thomas
Published: February 2021

The Institute of Virology at the Philipps-Universität Marburg is currently researching possible drugs to combat the Marburg virus. This involves classifying cell structures based on fluoroscopic microscopic image sequences. Conventionally, membranes of cells must be marked for better analysis, which is time consuming. In this work, an approach is presented to identify cell structures in images that are marked for subviral particles. It could be shown that there is a correlation between the distribution of subviral particles in an infected cell and the position of the cell’s structures. The segmentation is performed with a "Mask-R-CNN" algorithm, presented in this work. The model (a region-based convolutional neural network) is applied to enable a robust and fast recognition of cell structures. Furthermore, the network architecture is described. The proposed method is tested on data evaluated by experts. The results show a high potential and demonstrate that the method is suitable.
Continuous signal quality estimation for robust heart rate extraction from photoplethysmographic signals
Authors: Massmann Jonas , Tigges Timo , Orglmeister Reinhold
Published: February 2021

This study presents a novel method for estimating the signal quality of photoplethysmographic (PPG) signals. For this purpose a robust classifier is implemented and evaluated by using finger- and inear-PPG. A new procedure is proposed, which uses feature reduction to determine the Mahalanobis distance of the PPG-pulses to a statistical reference model and thus facilitates a robust heart rate extraction. The evaluation of the algorithm is based on a classical binary classification using a manually annotated gold standard. For the finger-PPG a sensitivity of 86 ± 15 % and a specificity of 94 ± 13 % was achieved. Additionally, a novel classification method which is based on a continuous signal quality index is used. Pulse rate estimation errors greater than 5 BPM can be detected with a sensitivity of 91 ± 13 % and a specificity of 91 ± 15 %. Also, a functional correlation between the signal quality index and the standard deviation of the pulse rate error is shown. The proposed classifier can be used for improving the heart rate extration in pulse rate variability analysis or in the area of mobile monitoring for battery saving.
An introduction to Acoustic Emission Analysis (AEA) based medical diagnostic techniques: Screening and Monitoring of cartilage defects in knee joint osteoarthrosis
Authors: Joerg Subke , Sabine Krueger , Heinz-Otto Junker , Hans-Joachim Schwalbe , Ralf-Peter Franke , Udo Wolf
Published: February 2021

Clinical studies have shown that during standardized movements the Acoustic Emission (AE) from lesions in articular cartilage can be assessed. Specific lesions produce specific acoustic signals, therefore it is possible to evaluate the character of cartilage damage. Consequently it is possible to evaluate the condition of the joint cartilage in order to enhance therapy. Patients performed series of knee bends, first on a plane surface in order to assess the cartilage lesions. Then patients performed knee bends on boards simulating orthopaedic insoles by means of inner and outer edge elevations. Insoles aim at relieving the lesioned areas of cartilage from loads and strain. AEA monitoring reveals the effects of a shift of the zone of load transfer immediately and is an adequate tool for the diagnosis as well as the monitoring of therapeutic measures.
Extension of the Stoichiometric Calibration of CT Hounsfield values to Metallic Materials
Authors: Ese Zehra , Zylka Waldemar
Published: February 2021

Nowadays, patients with metallic implants undergoing radiotherapy may suffer from inaccuracy in the treatment plan caused by the implant. To ensure a precise plan an accurate relation between Hounsfield values of the computer tomographic (CT) images and the electron density of the elements and material mixtures is indispensable. In order to extend the stoichiometric calibration approach known for tissues to the regime of metallic materials, the basic physical equations as well as approximations in the parametrization and fitting are carefully reviewed. CT images of a standard calibration phantom and pure metallic samples up to the atomic number Z = 29 were acquired for various energies. Hounsfield values were determined on an extended Hounsfield scale which allows the mapping of material having high atomic number Z. It is found that from basic physics an empirical factorization of the cross-sections into a function of Z and a function of photon energy E is not allowed over a wide range of Z. Specifically, the parameterization for tissue like materials cannot be prolonged to materials with high-Z. Thus, the calibration is subdivided into regions of materials and its accuracy is quantified in each region. It depends, among others, on the knowledge of the X-ray photon spectra, the segmentation of the material samples and the empirical parameterization of the linear-attenuation coefficient.
Determination of the Cavitation Pressure Threshold in Focused Ultrasound Wave Fields applied to Sonosensitive, Biocompatible Nanoparticles for Drug Delivery Applications
Authors: George Benedikt , Lehner Markus , Fink Michael , Rupitsch Stefan J. , Ermert Helmut , Hiltl Pia T. , Savšek Ula , Lee Geoffrey
Published: February 2021

Employing sonosensitive nanoparticles as carriers of active pharmaceutical ingredients emerges in ultrasonic Drug Delivery. Drug release can be initiated by focused ultrasound via the effect of inertial cavitation in certain target areas of particle loaded tissue. For stimulating inertial cavitation, a specific peak rarefaction pressure threshold must be exceeded. This pressure threshold has to be determined in order to estimate the risk of tissue damage during the drug release procedure. Therefore, this study provides a method to reliably verify the cavitation pressure threshold of sonosensitive and biocompatible nanoparticles.
Validating a Numerical Simulation of Human Heart Motion Using Clinical Data
Authors: Müller Armin , Kovacheva Ekaterina , Fritz Marc Alexander , Dössel Olaf , Loewe Axel
Published: February 2021

Numerical simulations are increasingly often involved in developing new and improving existing medical therapies. While the models involved in those simulations are designed to resemble a specific phenomenon realistically, the results of the interplay of those models are often not sufficiently validated. We created a plugin for a cardiac simulation framework to validate the simulation results using clinical MRI data. The MRI data were used to create a static wholeheart mesh as well as slices from the left ventricular short axis, providing the motion over time. The static heart was a starting point for a simulation of the heart’s motion. From the simulation result, we created slices and compared them to the clinical MRI slices using two different metrics: the area of the slices and the point distances. The comparison showed global similarities in the deformation of simulated and clinical data, but also indicated points for potential improvements. Performing this comparison with more clinical data could lead to personalized modeling of elastomechanics of the heart.
Simulation system for intraoperative neuromonitoring
Authors: Thiel Robert , Haupt Peter , Jäkel Jens
Published: February 2021

This paper presents a simulation system (“patient model”) for intraoperative neuromonitoring (IONM) applied to mastoidectomy. IONM is an electrophysiological method for monitoring the integrity and localization of nerve tracts, which helps the surgeon to avoid injuries and damage to neural risk structures (e.g. facial nerve) during surgery. To use the IONM successfully, the surgeon needs appropriate training and experience. The presented simulation system provides training possibilities in a realistic, cost-efficient and reproducible way. In the simulation system, the position of the probe during training is determined by a magnetic tracking method. Depending on the distance to the virtual nerve, a synthetic electromyogram (EMG) signal is sent to a real neuromonitor. The trainee learns to interpret the output of the neuromonitor. The trainer can choose different training scenarios, such as localization of the nerve, milling or coagulating, using a web application.
Transverse dose profile simulation of extruded lines for a 3D printed models for superficial skin cancer therapy
Authors: Pashazadeh Ali , Friebe Michael
Published: February 2021

The short-range and sharp dose fall-off of beta particles in tissue make them an interesting option for use in the radiation therapy of superficial skin tumors. This can be used to protect bony or other sensitive structures located right beneath the tumor. In a previous study, we studied the feasibility of using 3D printing technology to create 2D radioactive models for the treatment of skin tumors. In the current study, the Monte Carlo method was used to simulate the transverse dose profile form 3D printed extruded line containing yttrium-90 (Y-90) particles. The time and activity required for treating a superficial skin tumor using these extruded lines were also calculated.
Web-based Prostate Visualization Tool
Authors: Oyarzun Cristina Laura , Hartwig Katrin , Hertlein Anna-Sophie , Jung Florian , Burmeister Jan , Kohlhammer Jörn , Wesarg Stefan , Sauter Guido
Published: February 2021

Proper treatment of prostate cancer is essential to increase the survival chance. In this sense, numerous studies show how important the communication between all stakeholders in the clinic is. This communication is difficult because of the lack of conventions while referring to the location where a biopsy for diagnosis was taken. This becomes even more challenging taking into account that experts of different fields work on the data and have different requirements. In this paper a web-based communication tool is proposed that incorporates a visualization of the prostate divided into 27 segments according to the PI-RADS protocol. The tool provides 2 working modes that consider the requirements of radiologist and pathologist while keeping it consistent. The tool comprises all relevant information given by pathologists and radiologists, such as, severity grades of the disease or tumor length. Everything is visualized using a colour code for better undestanding.
Progressive Dynamic Time Warping for Noninvasive Blood Pressure Estimation
Authors: Pielmus Alexandru-Gabriel , Klum Michael , Tigges Timo , Orglmeister Reinhold , Urban Mike
Published: February 2021

Arterial blood pressure is one of the most important cardiovascular parameters. Yet, current-generation devices for continuous, noninvasive acquisition are few, expensive and bulky. Novel signal processing applied to easily acquired unimodal signals can alleviate this issue, reducing size, cost and expanding the use of such devices to ambulatory, everyday settings. The features of pulse waves acquired by photo- or impedance-plethysmography can be used to estimate the underlying blood pressure. We present a progressive dynamic time warping algorithm, which implicitly parametrizes the morphological changes in these waves. This warping method is universally applicable to most pulse wave shapes, as it is largely independent of fiducial point detection or explicit parametrization. The algorithm performance is validated in a feature selection and regression framework against a continuous, noninvasive Finapres NOVA monitor, regarding systolic, mean and diastolic pressures during a light physical strain test protocol on four clinically healthy subjects (age18- 33, one female). The obtained mean error is 2.13 mmHg, the mean absolute error is 5.4 mmHg and the standard deviation is 5.6 mmHg. These results improve on our previous work on dynamic time warping. Using single-sensor, peripherally acquired pulse waves, progressive dynamic time warping can thus improve the flexibility of noninvasive, continuous blood pressure estimation.
Endoscopic filter fluorometer for emission detection of Protoporphyrin IX and its direct precursors in PDT and PDD
Authors: Boese Axel , Wagner Alexander , Friebe Michael , Bernd Liehr Uwe , Wendler Jakob Johann
Published: February 2021

Photodynamic therapy (PDT) is a potential option for treatment of cancer since it can be performed non- invasive for superficial cancers or minimal-invasive with low traumatization. But PDT is intrinsically inefficient due to the complex accumulation of the photosensitizing drug inside the tumor and the processes of heme syntheses to create the needed cell killing components. To optimize the outcome of PDT and increase acceptance as viable option it is necessary to predict the optimal time for the start of the treatment based on measurable precursors. A former cell study proposed a new filter fluorometer in a complex and sensitive setup. In this work we now designed and tested a simplified system that can be used in combination with standard endoscopic imaging systems. This system will be used as base to prove viability of this approach for a future clinical study.
Workflow and Human-Centered Risk Analysis for Novel Mechatronic Rescue Aids II.
Authors: Drobinsky Sergey , Verjans Mark , Schleer Philipp , Kolk Benedikt , Bensiek Henrike , Radermacher Klaus , Janß Armin
Published: February 2021

Paramedics face rising numbers of deployments every year. As obstacles like stairs occur often, paramedics must frequently manually carry patients and are thereby exposed to loads multitudes higher than recommended. This creates the need for patient transport aids (PTA), which can physically support paramedics in a wide variety of transport situations, without slowing down the transport. In this paper a workflow analysis for transport missions in an urban context and basic tasks for PTAs are presented. Subsequently, the high-level task modelling and human-centered risk analysis according to the HiFEM method are presented for the use case of a patient transport over stairs with a passive PTA, like a rescue chair, and an active PTA like the novel SEBARES prototype. The analysis shows that conventional PTA’s have a simple linear use process, however, impose excessive physical workloads, which cause risks like the paramedic or the PTA falling down the stairs. Contrary, active PTA’s reduce physical workloads, however, introduce additional concurrent steps, like identifying and correcting misalignments, which create further risks. In order to mitigate risks with active, stair climbing PTAs, either new kinematic designs or intelligent assistance functions, like automatic stair detection, are necessary.
Microstructured ceramic and metallic implant surfaces and their impact on the viscosity of a synovia fluid substitute
Authors: Philipp Drescher , Seitz Hermann , Oldorf Paul , Peters Rigo
Published: February 2021

This study evaluates the effect of ring-shaped microstructures on the rheological properties of a synovial fluid substitute. Two different materials that are frequently used in endoprostheses have been chosen in order to study the lubricating effect of femtosecond-laser microstructured implant surfaces by measuring the apparent dynamic viscosity of the lubrication fluid. The two different materials are the ceramic Al2O3 and the metal alloy CoCrMo. The results show that an increase in the viscosity of the synovia fluid substitute can be achieved by specific microstructuring. An increase of viscosity of up to 40% compared to an unstructured reference was observed with ring-shaped microstructures with a diameter of 100 μm, a texture area density of 2.5 % and an aspect ratio of 0.66. The measurements have also shown that the ceramic material resulted in slightly higher viscosity values, compared to the metal alloy which can explained by dimensional deviations of the microstructures caused by the laser microstructuring.
Strong convergence of an inertial extrapolation method for a split system of minimization problems
Authors: Gebrie Anteneh Getachew , Wangkeeree Rabian
Published: February 2021

In this article, we propose an inertial extrapolation-type algorithm for solving split system of minimization problems: finding a common minimizer point of a finite family of proper, lower semicontinuous convex functions and whose image under a linear transformation is also common minimizer point of another finite family of proper, lower semicontinuous convex functions. The strong convergence theorem is given in such a way that the step sizes of our algorithm are selected without the need for any prior information about the operator norm. The results obtained in this article improve and extend many recent ones in the literature. Finally, we give one numerical example to demonstrate the efficiency and implementation of our proposed algorithm.
Comparison of maternal third trimester hemodynamics between singleton pregnancy and twin pregnancy
Authors: Sima Romina-Marina , Findeklee Sebastian , Bădărău Ioana-Anca , Poenaru Mircea-Octavian , Scheau Cristian , Pleș Liana
Published: February 2021

Objectives

The impedance cardiography (ICG) technique measures the variation of impedance in the thorax due to the physical contractile activity of the heart. Twin pregnancy is characterized by greater maternal hemodynamic changes than a singleton pregnancy.

Methods

In a study on 121 pregnant women in the last trimester we performed ICG, evaluating the following hemodynamic parameters: stroke volume, heart rate, cardiac output, ventricular ejection time, left ventricular ejection time, thoracic impedance, and systemic vascular resistance.

Results

The study included singleton and twin pregnancies. Heart rate values in women with single fetus was lower than in those carrying twins (85 vs. 100 beats/min, p=0.021) as were the stroke volume values (64 vs. 83 mL, p=0.010) and the cardiac output (p<0.0001). Systemic vascular resistance decreased in twin pregnancies compared to singleton pregnancy (p=0.023).

Conclusions

ICG studies are rare, and the validation of their results is an ongoing process. However, the ICG technique is applicable in the third trimester of pregnancy and can yield important information regarding the hemodynamic profile of singleton and twin pregnancies, revealing maternal heart changes specific to twin pregnancies.
Effect of extruded low-density polyethylene on the microstructural and mechanical properties of hot-press produced 3105 aluminum composites
Authors: Wapande Sadam Hamis , Elibol Cagatay , Konar Murat
Published: February 2021

This study was conducted to investigate the effect of low-density polyethylene on the microstructural and mechanical properties of 3105 aluminum composites produced by the continuous hot-press method. This production method ensures superior flatness to the composite and excellent peel strength between the composite plies. To this end, the bond between AA3105 and low-density polyethylene was initially characterized using a T-Peel stripping test. Tensile tests were performed on AA3105, low-density polyethylene and 3105 aluminum composites for determining mechanical behavior. A scanning electron microscope was used to characterize the cross-sectional cuts of the 3105 aluminum composite specimens obtained from the tensile tests. The microstructural analysis shows that low-density polyethylene and AA3105 exhibit a good interfacial adhesion bond before the fracture of the first AA3105 sheet. The results of the tensile tests clearly show that the uniform elongation at maximum load (Ag) of the 3105 aluminum composite is higher than that of AA3105. Furthermore, AA3105 exhibits negative strain rate sensitivity due to dynamic strain aging while 3105 aluminum composite exhibits a higher strain-hardening exponent than AA3105. Due to the higher strain rate sensitivity and strain hardening exponent, the 3105 aluminum composite exhibits higher formability than AA3105. This is of crucial importance for the manufacturing process.
Wear resistance of HVOF sprayed NiSiCrFeB, WC-Co/NiSiCrFeB, WC-Co, and WC-Cr3C2-Ni rice harvesting blades
Authors: Khuengpukheiw Ronnarit , Saikaew Charnnarong , Wisitsoraat Anurat
Published: February 2021

In this work, NiSiCrFeB, WC-Co/NiSiCrFeB, WC-Co, and WC-Cr3C2-Ni coatings were sprayed on rice harvesting blade surfaces using a high velocity oxygen fuel (HVOF) process. Each of the rice harvesting blades was sprayed with one of four coating materials using different spraying durations. The effects of coating materials and spraying durations on the average values of coated blade volume loss, hardness and surface roughness (Ra) were studied through real rice-harvesting field tests. Analysis of variance (ANOVA) and a multiple comparison approach with Tukey’s test were used in order to conduct a comparative performance analysis of the coating materials of rice harvesting blades. The experimental results indicated that the NiSiCrFeB coating exhibited the highest volume loss compared with all others. In addition, the WC-Co-coated blade had significantly greater hardness than those coated with NiSiCrFeB, WC-Co/NiSiCrFeB, or WC-Cr3C2-Ni. The rice harvesting blade coated with either WC-Co/NiSiCrFeB, WC-Co, or WC-Cr3C2-Ni using the shortest spraying duration was recommended for installation in rice harvesting machines.
The crystal structure of N-(2-chloroethyl)-N,N-diethylammonium chloride, C6H15Cl2N
Authors: Muller Kina , Hosten Eric C. , Betz Richard
Published: February 2021

C6H15Cl2N, triclinic, P

1
‾

$‾{1}$

(no. 2), a = 6.9579(4) Å, b = 8.1852(5) Å, c = 8.7912(5) Å, α = 66.606(2)°, β = 86.105(3)°, γ = 89.834(2)°, V = 458.30(5) Å3, Z = 2, R

gt
(F) = 0.0226, wR
ref(F
2) = 0.0599, T = 200 K.
Blanchot y la lógica de la desapropiación
Authors: Espinosa Proa Guillermo Sergio
Published: February 2021

Frente a Hegel y la dialéctica, algunos autores como Maurice Blanchot contraponen la amistad como relación humana esencial y la experiencia estética como paradigma de la acción, relegando el trabajo, que es servil siempre, como modelo decaído de la misma. En este ensayo se ahonda en la cuestión privilegiando dos textos, aparecidos en 1969 y 1971, en donde Maurice Blanchot se plantea explícitamente la diferencia entre la dialéctica y la tragedia como formas antitéticas de plantear la realidad de lo humano.
Seafloor and sediment characteristics of pulp mill waste discharges in the 20th century: Framework data for Boat Harbour, Nova Scotia, remediation projects and for baseline surveys of new pulp waste outfall installations in Northumberland Strait
Authors: Schafer Charles T.
Published: February 2021

During the 20th century, contamination of marine environments by Canadian pulp and paper mill effluent (PPE) resulted in the imposition of federal government regulations in 1971 that were revised and strengthened in 1992. This report reviews seafloor sediment features for three marine settings (intertidal, subtidal and prodelta) arising from 20th century PPE discharges from four pulp and paper mills, one located near New Richmond, Quebec, and three situated along the lower reaches of the Saguenay River, Quebec. The four mills began operations between 1965 and the early 1900’s. Observations of their proximal and distal sediment and Foraminifera characteristics in relation to PPE discharge outfalls offer guidance for the remediation of potentially toxic, multi-decadal waste accumulations in several lagoons of Boat Harbour, Nova Scotia. Seafloor environmental data discussed for a fifth mill’s subtidal outfall, located on the eastern shore of Canso Strait, may be particularly germane for selecting the site and baseline environmental survey criteria for a new PPE submarine outfall that has been proposed (presently rejected) by Northern Pulp Company for the Caribou Harbour area of the Northumberland Strait coast, in the event that the currently closed mill is permitted to be reactivated in the future. Keywords: effluent, environmental effects, organic matter, pulp mill waste, sediments
Social Insurance for Doctoral Students of Doctoral Schools
Authors: Ryś Krystian
Published: February 2021

The reform of the doctoral student education system, resulting in a departure from conducting third degree studies in favour of doctoral schools, resulted in changes in the field of social security law. The status of a doctoral student receiving a doctoral scholarship has become independent grounds for compulsory retirement, disability and accident insurance. At the same time, it is the basis for voluntary sickness insurance. The author criticises the granting of doctoral students the right to acquire cover under this type of insurance. Their actual situation when receiving a doctoral scholarship is far different from the situation of other persons (grounds) covered by sickness insurance. The author also discusses the issue of coincidences of grounds for social insurance of doctoral students. The legislator categorised the collection of a doctoral scholarship in the group of absolute grounds for insurance. Unfortunately, it omitted in the regulation of Art. 9 sec. 1a of the Act on Social Insurance System a reference to the basis of the contributions on the received scholarship, which in extreme cases may lead to a significant extension of the doctoral student’s social insurance obligation.
Granting the Academic Title of Professor. Some Reflections on the Regulations Contained in Law on Higher Education and Science
Authors: Sieniuć Magdalena
Published: February 2021

The Law on Higher Education and Science of 20 July 2018, entered into force on 1 October 2018, introduced changes concerning the prerequisites for the acquisition of the academic title of professor and the procedure for awarding it. The stage of proceedings before the board of an organisational unit (e.g. Faculty Council) was also abandoned, which in fact led the procedure beyond the ‘walls of the university’ and limited it to the stage of proceedings before the Council of Scientific Excellence. The author considers selected issues relating to the Professor’s academic title, concerning the premise for awarding it, the course of the proceedings in this subject and the entities taking part in them, as well as the role played by the President of the Republic of Poland in these proceedings. As a result of the considerations conducted, the author assumed that the most far-reaching change was the legislator’s resignation from the stage of proceedings before the council of the entity from which the candidate for the title of professor had come from, assuming that the role of the President of the Republic of Poland in this process had not undergone any significant changes. He remains bound by the opinions of the reviewers appointed by the Council of Scientific Excellence and its position expressed in the administrative decision issued on the application for the academic title. In accordance with the viewpoint of the author, due to the resignation of the legislator from the stage of proceedings before an individual’s council, the opinions of the reviewers expressed in the justification of the Council of Scientific Excellence decision are now, in principle, the only emanation of the assessment of the scientific community expressed in this procedure.
Healthy ageing and spermatogenesis
Authors: Pohl Eva , Gromoll Jörg , Wistuba Joachim , Laurentino Sandra
Published: February 2021

Delayed family planning and increased parental age increase the risk for infertility and impaired offspring health. While the impact of ageing on oogenesis is well studied, this is less understood on spermatogenesis. Assessing ageing effects on the male germline presents a challenge in differentiating between the effects of ageing-associated morbidities, infertility and ‘pure’ ageing. However, understanding the impact of ageing on male germ cells requires the separation of age from other factors. In this review, we therefore discuss the current knowledge on healthy ageing and spermatogenesis. Male ageing has been previously associated with declining sperm parameters, disrupted hormone secretion and increased time-to-pregnancy, among others. However, recent data show that healthy ageing does not deteriorate testicular function in terms of hormone production and spermatogenic output. In addition, intrinsic, age-dependent, highly specific processes occur in ageing germ cells that are clearly distinct from somatic ageing. Changes in spermatogonial stem cell populations indicate compensation for stem cell exhaustion. Alterations in the stem cell niche and molecular ageing signatures in sperm can be observed in ageing fertile men. DNA fragmentation rates as well as changes in DNA methylation patterns and increased telomere length are hallmarks of ageing sperm. Taken together, we propose a putative link between the re-activation of quiescent Adark spermatogonia and molecular changes in aged sperm descending from these activated spermatogonia. We suggest a baseline of ‘pure' age effects in male germ cells which can be used for subsequent studies in which the impact of infertility or co-morbidities will be studied.
Clinical, Socio-Demographic Profile and Stressors in Patients with Conversion/Dissociative Disorders: An Exploratory Study from Southern India
Authors: Bashar Abu
Published: February 2021

Background Patients present with ‘conversion disorder’ as a response to the underlying stressful conditions. It is clinically important to evaluate the presence, type, and temporal relation of the stressors resulting in conversion. Further knowing the Socio-demographic and psychological profile of the conversion patient helps in their better management. Aim To study the clinical features and presentations, Socio-demographic characteristics, and underlying psychosocial stressors associated with conversion disorder.Material & Methods Fifty patients admitted to the department of psychiatry, NRI Medical College and Hospital, Vishakhapatnam, India from 1st January 2013 to 31st December, 2014 who fulfilled the inclusion criteria of the study were evaluated for socio-demographic characteristics, clinical presentations, and stressors on a semi-structured proforma.Results Majority of the patients with conversion symptoms were children and young adults (74.0%), females (62.0%), students (46.0%), currently married (54.0%) and those living in nuclear families (78.0%) and having rural background (62.0%). Socioeconomic status wise, majority (66.0%) of the patients belonged to middle class. Majority of the patients (92.0%) had a recognizable precipitating factor, of which family-related/marital (36.0%) and education/school-related (18.0%) problems accounted for the major types. Purely motor symptoms were the predominant presentation (84.0%) with unresponsiveness /syncopal attack and pseudo seizure being the commonest.Conclusion Conversion disorders are commonly seen in females, children and young adults, students and in those people belonging to middle class in socioeconomic status and rural areas. Underlying psychosocial stressors could be identifiable in majority of the cases of conversion disorder.
Use of sweet sorghum bagasse (Sorghum bicolor (L.) Moench) for cellulose acetate synthesis
Authors: Neto José M. da Silva , Oliveira Líbia de S. C. , da Silva Flávio L. H. , Tabosa José N. , Pacheco José G. A. , da Silva Márcio J. V.
Published: February 2021

The objective of this work was to synthesize cellulose acetate from sorghum bagasse, a promising raw material for the production of chemical inputs, both from a photosynthetic point of view and the maturation speed compared with that of sugarcane. The bagasse was treated with hydrogen peroxide, and then cellulose was isolated using sodium chlorite, acetic acid, and sodium hydroxide. The cellulose was subjected to an acetylation reaction, from which cellulose triacetate was obtained. By means of statistical analysis, it was observed that the conditions that generated the highest solubilization of lignin (62%) and higher yield from cellulose extraction (39.5%) were 60 °C, a 6% peroxide concentration, and 4 h. Cellulose acetate was obtained with a degree of substitution of 3.66 at 25 °C and 24 h. Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry, differential thermogravimetry, and differential scanning calorimetry analyses confirmed that the obtained cellulose presented specific characteristics of this material. Also, the reaction of acetylation was confirmed through these techniques.
Effect of nonstoichiometric defects and Cr ions on the photoconductivity of Bi12SiO20 crystals
Authors: Panchenko T. V. , Karpova L. M.
Published: February 2021

The results of an experimental study of the effect of nonstoichiometric defects in oxygen and the Bi:Si ratio, as well as Cr ions, on the photoconductivity of Bi12SiO20 crystals are presented. It is shown that varying the annealing conditions allows one to modify the spectral distribution and quantitative characteristics of photoconductivity substantially.