bluuebunny/crossref_metadata_2025 huggingface dataset:
Werkstoffgerechte Randschichtkonzepte für die Festigkeitsgestaltung von Kurbelwellen
Authors: Conradt G.
Published: February 2022

Kurzfassungen

Unsicherheit und mangelnde Kooperation der Fachgebiete kann bei der Festigkeitsgestaltung zu überhöhter Bauteilfestigkeit und damit zu hohen Fertigungskosten führen. Für eine ausreichende aber nicht überhöhte Bauteilfestigkeit leistet die Werkstofftechnik einen wichtigen Beitrag u.a. durch werkstoffgerechte Verfahren zur Randschichtverfestigung. Die Kriterien zur Bemessung der Dauerschwingfestigkeit von Kurbelwellen – wie Lastverhältnis, Kompatibilität von Werkstoff und Randschichtkonzept, Gestaltung der Form von Lagerhohlkehlen sowie werkstofftechnische Potenziale für nachträgliche Steigerung der Bauteilfestigkeit – werden erläutert. Bei der Auswahl von Rohteil und dessen Wärmebehandlung ist besonders auf Fertigungsrisiken und Lebensdauerprognose zu achten. Die Werkstoffpalette für Kurbelwellen wird unter vorgenannten Gesichtspunkten untersucht und es werden neue Werkstoffe vorgestellt. Der Erfolg der gängigen Verfahren zur Randschichtverfestigung – wie Randschichthärten, Festwalzen, Nitrieren oder Kugelstrahlen – hängt entscheidend von Lastverhältnis und Geometrie der Lagerhohlkehlen ab. Fertigungsrisiken und Herstellkosten können durch effiziente Vorgaben für Technologie und Prüftechnik gesenkt werden. Es wird darauf hingewiesen, dass Fehlentscheidungen an interdisziplinären Schnittstellen (Kompetenzlücken) zu ungewollten Veränderungen der Bauteilfestigkeit führen können.
Wälzermüdung
Authors: Schlicht H.
Published: February 2022

Kurzfassungen

Das Besondere des Werkstoffverhaltens bei Hertz’scher Beanspruchung ergibt sich einerseits aus der Tatsache, dass die Gefügeveränderungen unter hohem hydrostatischen Druck ablaufen und andererseits daraus, dass sich während des Prozesses der Wälzermüdung der Ort größter Werkstoffbeanspruchung räumlich und zeitlich verschiebt. Hierbei dreht sich das Hauptspannungssystem. Der Ort der größten Beanspruchung (σvmax ) liegt unter der Kontaktfläche, zu Beginn des Ermüdungsprozesses senkrecht unter p0. Bei überelastischer Beanspruchung treten dort die ersten plastischen Verformungen des Gefüges auf, es entstehen Druckeigenspannungen parallel zur Kontaktfläche. Diese bewirken eine allmähliche Verschiebung des Ortes vonσvmax in Überrollungsrichtung, der Abstand zur Kontaktfläche wird kleiner. Gleichzeitig dreht die ursprünglich parallel zur Kontaktfläche liegende dominierende Zugspannung in Richtung Kontaktfläche. Untersuchungen zeigen, dass hoher hydrostatischer Druck große plastische Verformungen zulässt, ohne dass im Gefüge Mikrorisse entstehen. Die plastischen Verformungen bewirken einerseits eine Änderung der Eigenspannungen und andererseits auch eine Veränderung der Festigkeit. Das martensitische Gefüge enthält meist 10-15 Vol.-% Restaustenit; ein relativ kleiner Teil des Restaustenits wandelt zu Beginn des Ermüdungsprozesses (Phase 1) infolge der plastischen Verformung in Martensit um. Die Festigkeitssteigerung und die entstehenden Druckspannungen bringen die Gefügeveränderungen annähernd zum Stillstand (2. Phase, sog. Beharrungsphase). Zu Beginn der 3. Phase setzt am Ort größter Beanspruchung eine Beschleunigung der plastischen Verformungen ein, verbunden mit einer beschleunigten Umwandlung des Restaustenits zu Martensit. Gleichzeitig werden makroskopische Form- bzw. Gestaltänderungen beobachtet. Als Erklärung wird angenommen: Infolge der Verlagerung des Ortes größter Beanspruchung und der Drehung des Hauptspannungssystems wird aus den mikroplastischen Verformungen ein makroplastischer Vorgang. Gefügebereiche niedrigerer Festigkeit „fließen“ in Richtung Kontaktoberfläche. Es entstehen infolgedessen die thermodynamischen Voraussetzungen für eine beschleunigte Umwandlung des Restaustenits zu Martensit.
Bedeutung von Eigenspannungsabbau und mikrostrukturellen Veränderungen für die Lebensdauervorhersage schwingbeanspruchter Schweißverbindungen
Authors: Lachmann C. , Nitschke-Pagel Th. , Wohlfahrt H.
Published: February 2022

Mit Hilfe der hier vorgestellten Untersuchungen soll die Lebensdauervorhersage für Schweißverbindungen in Bauteilen durch die Erfassung ermüdungsrelevanter Werkstoffveränderungen verbessert werden. Der in den unterschiedlichen Schweißnahtbereichen von Proben und Großbauteilen sowie in Schweißsimulationsproben röntgenographisch festgestellte Eigenspannungsabbau und stattfindende mikrostrukturelle Werkstoffveränderungen lassen sich last-, gefüge- und schwingspielzahlabhängig einordnen. Die Einbeziehung örtlicher Spannungsspitzen in die Berechnung von Vergleichsspannungen und eine Erweiterung des Modellansatzes nach Bergström ermöglichen eine schlüssige Bewertung des mehrachsig stattfindenden Eigenspannungsabbaus im Schweißnahtbereich. Mittels einer Vielparameter-Regressionsanalyse mikromagnetisch gemessener Kenngrößenverläufe können ermüdungsbedingte Werkstoffveränderungen der Restlebensdauer zugeordnet werden. Auf der Basis von Wöhlerversuchen wurden Methoden entwickelt, über äquivalente Probenversuche die Restlebensdauer einer Schweißnaht im Großbauteil zu ermitteln. Die Berücksichtigung des röntgenographisch gemessenen Eigenspannungsabbaus verbessert die Vorhersagegenauigkeit einer rechnerischen Lebensdauervorhersage auf Basis des örtlichen Konzepts.
Crystal orientation and residual stress in TiN film by synchrotron radiation
Authors: Hanabusa Takao , Kusaka Kazuya , Nishida Masayuki , Matsue Tatsuya , Sakata Osami
Published: February 2022

The residual stress in a TiN film, the thickness of which is less than 1 µm, deposited by arc ion plating was measured using the SPring-8 synchrotron radiation facility installed at Japan Synchrotron Radiation Research Institute (JASRI). Films thicker than 300 nm have a {111} texture, whereas those with a thickness of 100 nm have a relatively random orientation. Instead of the conventional laboratory X-ray equipment, ultrabright synchrotron radiation can be used to precisely measure the residual stress in thin films with a thickness of 100 to 800 nm. The residual stress in thicker TiN films is about 7 GPa in compression and it is not affected by the film thickness. The slightly small compressive stress in a film of 100 nm in thickness may be due to the different crystal orientations in the film.
Fatigue crack nucleation at grain boundaries – experiment and simulation
Authors: Vehoff Horst , Nykyforchyn Andrii
Published: February 2022

Fatigue crack nucleation at grain boundaries near the endurance limit was examined combining the results of the fatigue tests with local orientation measurements and with finite element (FE) calculations. Bicrystals and coarsegrained thin sheets were examined in which the orientation and inclination of each boundary could be measured directly. These results were used as input for the FE calculation in which the stress concentrations near the boundaries were calculated. In the fatigue tests, the boundaries, at which the first cracks nucleate, where measured by a replica technique. A comparison of the experimental results with the predictions of the FE calculation yields that the cracks nucleated and propagated along the boundaries with the largest stress concentration. Cracks which hit a boundary with a lower stress concentration either stop or propagate transgranularly, depending on the local stress concentration given by the microstructure. From these results, it can be concluded that elastic strain incompatibilities combined with the microstructure (grain size and orientation) can be used to predict the crack nucleation sites and the scatter in lifetime for fatigue near the endurance limit.
Fatigue and fracture-induced defect structures of metals investigated by positron microscopy
Authors: Egger W. , Kögel G. , Sperr P. , Triftshäuser W. , Bär J. , Rödling S. , Gudladt H.-J.
Published: February 2022

Defect distributions close to cracks from monotonic and fatigue fractures have been investigated for the first time by positron lifetime studies. The positron beams probe either the depth profile of defects at sub-μm resolution or the lateral distribution of defects at a few μm spatial resolution. Both in pure Cu and in the precipitation-hardened alloy Al 6013, in addition to dislocations, large clusters of up to 30 vacancies were detected close to a fatigue crack exclusively, whereas at monotonic fractures only the annihilation characteristics of dislocations were observed. If this characteristic difference holds as a general rule, then positron lifetime microscopy will provide a simple, quantitative method to distinguish a posteriori monotonic fractures from fatigue fractures without any further fractographic studies.
Deformation and fracture of Nb/α-Al2O3 composites in compression and bending studied by optical methods
Authors: Liu Y. , Kohnle C. , Brunner D. , Rühle M.
Published: February 2022

The fracture behavior of Nb/α-Al2O3composites was investigated both in compression tests and bending tests using an optical full-field method for the observation of strain fields on the metal surfaces. Joints of polycrystalline materials were prepared by high-vacuum diffusion bonding. The building up of the strain near the interface during the tests, finally leading to the fracture, was studied by examining the strain and displacement fields of the whole metal layer. In compression tests, two types of fracture, fracture of alumina and fracture of interfaces, were detected by cross-examination of the stress –strain curve and the strain maps. The fracture of alumina in compression tests was influenced by the Nb layer thickness and can be rationalized by an extension of Cottrell’s model. For four-point bending tests, the results of the strain maps, determined experimentally by means of the optical method, confirmed the strain maps resulting from finite element simulations.
Der dynamische SD-Effekt und der Einfluss auf die Fließortkurve
Authors: Meyer Lothar W. , Hahn Frank
Published: February 2022

Biaxiale dynamische Werkstoffuntersuchungen des Einsatzstahls 20MoCrS4 werden unter kombinierter Zug/ Druck –Torsions-Belastung an dünnwandigen Rohrproben durchgeführt. Es wird eine Auswertemethode vorgestellt, mit der der Fließort bei vorgegebenem festen Verhältnis von wahrer Dehnung zur Scherung eindeutig bestimmt werden kann. Die Untersuchungen zeigen, dass der Fließort von der Formänderungsgeschwindigkeit abhängig ist. Höhere Belastungsgeschwindigkeiten führen zur Ausdehnung der Fließortkurve und zur Verschiebung des Mittelpunktes der Ellipse. Damit wird der dynamische SD (strength differential)-Effekt) auch unter biaxialer Beanspruchung nachgewiesen. Für die Finite-Elemente-Methode hat das zur Folge, dass für eine präzise Simulation plastischer Vorgänge unbedingt der Geschwindigkeitseinfluss auf die Veränderung der Fließfläche berücksichtigt werden muss.
Einfluss der Umformgeschwindigkeit und -temperatur auf das Fließverhalten metallischer Werkstoffe
Authors: El-Magd Essam , Abouridouane Mustapha
Published: February 2022

Das Fließ- und Bruchverhalten der Al-Legierung AA7075-T7351, der Mg-Legierung AZ80 und der Ti-Legierung TiAl6V4 wird im quasistatischen und dynamischen Druckversuch bei Umformgeschwindigkeiten im Bereich 0.001 − 5000 s−1 und Temperaturen von Raumtemperatur bis zu 450 C untersucht. Zur Beschreibung des Geschwindigkeits- und Temperatureinflusses auf das mechanische Materialverhalten im Druckversuch können konstitutive Stoffgesetze, deren Parameter aus den Versuchsergebnissen bestimmt werden, herangezogen werden. Diese Stoffgesetze sollen in die Finite-Element-Simulation implementiert werden, um die lokalen Spannungs- und Verzerrungszustände zum Zeitpunkt des Bruchs zu ermitteln. Mit Hilfe der experimentell ermittelten Fließkurven wird der Einfluss von Umformgeschwindigkeit und Temperatur auf den Bruchstauchgrad bestimmt. Ergänzende metallographische Untersuchungen geben darüber hinaus Aufschluss über Schädigungsbeginn, -art und -entwicklung im verformten Material.
Thermozyklisches Kriechen einer kurzfaserverstärkten Aluminium-Kolbenlegierung
Authors: Schnabl Andreas , Degischer Hans Peter
Published: February 2022

Die mit Saffil®-Fasern verstärkte Kolbenlegierung AlSi12CuMgNi wird bei konstanten Lastniveaus im Bereich zwischen 50 und 300 °C thermisch zykliert, bis sie bricht. Durch die Widerstandserwärmung in der ,,Gleeble 1500” – Apparatur sowie durch die Abkühlung mit Druckluft können dabei Aufheiz- bzw. Abkühlraten von 12,5 K/s erreicht werden. Die Verstärkung mit Kurzfasern bewirkt bei allen Proben eine Erhöhung der Lebensdauer und eine Verringerung der minimalen Kriechrate, wobei der Einfluß der Wärmebehandlung verglichen mit den unverstärkten Proben vernachlässigbar wird. Die Wirkung der Kurzfaserverstärkung wird mit modifizierten Werkstoffgesetzen für isothermes Kriechen beschrieben.
Modeling of deformation behavior of copper under equal channel angular pressing
Authors: Baik Seung Chul , Hellmig Ralph Jörg , Estrin Yuri , Kim Hyoung Seop
Published: February 2022

The deformation behavior of copper during equal channel angular pressing (ECAP) was calculated using a three-dimensional version of a constitutive model based on the dislocation density evolution. Finite element simulations of the variation of the dislocation density and the dislocation cell size with the number of ECAP passes are reported. The calculated stress, strain and cell size are compared with the experimental data for Cu deformed by ECAP in a modified route-C regime. The results of finite element (FE) analysis were found to be in good agreement with the experiments. After a rapid initial decrease down to about 200 nm in the first ECAP pass, the average cell size was found to change little with further passes. Similarly, the strength increased steeply after the first pass, but tended to saturate with further pressings. The FE simulations also showed strain non-uniformities and the dependence of the resulting strength on the location within the workpiece.
Determination of the local oxygen distribution in a commercial titanium alloy by 3-dimensional atom probe
Authors: Reissig Lutz , Czubayko Ulrich , Wanderka Nellia , Völkl Rainer , Glatzel Uwe
Published: February 2022

The local oxygen concentration of titanium alloys, such as Ti6Al4V, is of great interest but experimentally difficult to determine. One method to measure the local distribution with atomic level resolution is the 3-dimensional atom probe. We show a way how to prepare Ti6Al4V samples and present and discuss first results.
Microstructure and electrochemical properties of FeCoNiCuZn high-entropy alloy films by DC electrodeposition
Authors: Wang Ziyao , Huo Jiaxiang , Luan Xuezhu , Sun Shineng , Ma Guofeng
Published: February 2022

High-entropy alloys show great potential for industrial application because of their excellent physical and chemical properties. In this work, a simple DC electrodeposition method was introduced to prepare FeCoNiCuZn high-entropy alloy films on a 304 steel substrate. The phase composition, micromorphology, element composition and electrochemical properties of the films were characterized, analyzed and discussed, which provided reference and inspiration for preparing high-entropy alloy two-dimensional materials by electrochemical methods.
Testing Investment Forecast Efficiency with Forecasting Narratives
Authors: Foltas Alexander
Published: February 2022

I analyze the narratives that accompany business cycle forecasting reports of three German institutes using topic models. To this end, I gather multiple similar topics into different economic subject categories, allowing me to map shifting prioritizations within and between these subjects. Subsequently, I examine whether forecasting narratives contain additional information not captured by traditional indicators and include them in a random forest-based investment-forecast efficiency analysis. I find multiple correlations between narratives and forecast errors and conclude that forecasters inefficiently incorporate qualitative information in these cases. I raise the idea that further investigations with more precise identification of forecasting narratives could improve qualitative information processing or lead to scientific guidelines for forecast adjustments.
Effect of thermal annealing on the structural and optical properties of TiO2 nanostructures**
Authors: Hassan Ahmed T. , Hassan Ehssan S. , Abdulmunem Oday M.
Published: February 2022

In this work, TiO nanostructure films were deposited via vacuum thermal evaporation at a temperature of 80°C. The TiO thin films were annealed under vacuum for 1 h at three different degrees (200, 300, and 400°C) in addition to the thin film prepared at 80°C. X-ray Diffraction (XRD) showed that all the deposited and annealed TiO films had anatase polycrystalline diffraction patterns with a predominant reflection of the (200) plane. As a result, the particle size increased with annealing temperature. Scanning Electron Microscopy (SEM) measurements showed that at the annealed temperature of 200°C, the shape of the TiO nanostructures began to change from a condensed cluster distribution to a conical shape. As the annealing temperature was increased to 400°C, all the conical shapes transformed into clear spherical shapes. The spherical shapes recorded 45 (nm) height and (20) (nm) base width. Optical measurements were performed using Ultraviolet-Visible spectroscopy (UV-Vis). The transmittance is reduced from 79.63% for the TiO sample prepared at 80°C to 71.91% for the TiO sample annealed at 400°C. The optical energy gap values decrease from 3.279 eV for the prepared TiO sample at 80°C to 3.115 eV for the TiO sample annealed at 400°C.
Forming evolution of titanium grade2 sheets
Authors: Tekin Merve , Ertan Rukiye , Özgül Hande Güler
Published: February 2022

Titanium and its alloys take attention, especially in aerospace, automotive, and biomedical applications because of their strength, corrosion resistance, and biocompatibility. Titanium components, in general, are produced by sheet metal forming. However, the springback effect is a critical problem in the forming process due to difficult formability of titanium sheets. In the present study, the hot forming process was applied to sheets to investigate the effect of deformation temperature on microstructure, mechanical properties, and springback behavior of commercially pure grade 2 titanium sheets. The springback angles were measured at the CAD model after the sheets were scanned by the 3D scanner. The tensile test, hardness measurements, and microstructural analysis were examined by using specimens that were cut from the sidewall and the bottom of the deformed sheet as U-profile. The results reveal that the microstructure is substantially changed, and the springback is reduced with increasing temperature; thus, optimum results were obtained compared to the data obtained at room temperature.
Effect of Cloisite 15A on the mechanical properties of an abaca-based composite
Authors: Anandraj Mohan Kumar , Rathanasamy Rajasekar , Rathinasamy Parameshwaran , Palaniappan Sathish Kumar
Published: February 2022

The combined effect of resin containing nanoclay along with natural fibers elevates the mechanical properties. In addition, the dispersion of nanoclay at the fiber-matrix interface would create strong physical interaction between the two. The significant enhancement in mechanical properties is achieved for the composite containing 30 wt.% abaca fiber content and 2 wt.% nanoclay, which is treated by 8 vol.% NaOH concentration. The enhancement in the mechanical properties can be attributed to the wettability of fiber by the matrix, homogeneous distribution of fibers and nanoclay in the matrix phase and physical interaction between reinforcement and matrix. Increase in the addition of abaca fiber and nanoclay beyond the above mentioned content leads to drop in the mechanical properties. This can be due to many nanoclay agglomerates are not broken down to nano scale during preparation, it may also be the reason for drop in the mechanical properties.
Effect of austempering treatment on metallurgical structure of Ce inoculated X210Cr12 cold work tool steel
Authors: Teker Tanju , Yilmaz S. Osman , Eruslu S. Özmen
Published: February 2022

The effect of austempering treatment on metallurgical structure of X210Cr12 cold work tool steel inoculated with Ce was researched. Microstructural changes, elemental characterizations, and phase formations of the samples were examined by using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, elemental mapping, and microhardness test. Ce inoculation reduced the grain size, and the austenitizing temperature had a huge effect on the austenitizing process. The austenitizing process increased the hardness by reducing the retained austenite, but the degree was dependent on the austenitization temperature. The austempering treatment improved the hardness resistance by depositing more equal carbides composed of nano-sized carbides. High austempering period and increase of austempering temperature decreased the homogeneity and hardness of the microstructure.
Analysis of residual stresses and distortions of a titanium alloy ring-stiffened cylindrical shell
Authors: Ge Keke , Yu Yue , Xu Qiang , Zhang Aifeng , Feng Shichao
Published: February 2022

Ring-stiffened cylindrical shell is the main pressure structure of underwater carrier equipment, and the residual stress and deformation introduced by welding of ring-ribbed frame and cylinder body pose a great threat to the performance and safety of the structure. In this paper, finite element software is used to numerically simulate the residual stress and deformation caused by fillet welding. The influence of welding position, constraint tooling and post-weld heat treatment PWHT on the residual stress and deformation is analyzed systematically. The results show that the gravity has little effect on the welding residual stress and deformation, but it has a significant impact on deformation uniformity. Under the action of restraint, the welding distortion is effectively controlled, but it will lead to the increase of the overall stress level of the structure simultaneously. Heat treatment can dramatically diminish the welding residual stress at the expense of deformation, which may result in structural maladjustment.
Corrosion behavior of 316 stainless steel, copper, and brazed joint in lithium bromide solution at different temperatures
Authors: Zhang Xiang , Qiu Yunlong , Zhu Weifei , Yu Xinhua , Cao Yanan , Wang Xiaohuan , Liang Yanqin
Published: February 2022

Lithium bromide (LiBr) corrosion on austenitic 316 stainless steel (AISI 316) and copper will largely determine the overall performance of refrigeration compression systems. In this work, the corrosion behavior of AISI 316, copper, and brazed joint was studied in LiBr solution at different temperatures by using the polarization curve and electrical impedance spectroscopy. The morphology and chemical composition of the samples before and after corrosion were characterized to elucidate the corrosion mechanism. The passivation film of AISI 316 stainless steel is more prone to breakdown as the temperature increases, and the corrosion resistance of copper and brazed joint also decreases with the increasing temperature. Zero-resistance ammeter technology was employed to analyze the effect of temperature on galvanic corrosion. The degree of galvanic corrosion increases with temperature for all galvanic pairs (AISI 316-Cu, AISI 316-brazed joint, and Cu-brazed joint). For AISI 316-Cu and AISI 316-brazed joint galvanic pairs, AISI 316 functions as the cathode, while copper or brazed joint serves as the anode. For the Cu-brazed joint pair, the brazed joint is preferred to be corroded at room temperature, whereas at 50 and 75 °C, copper corrosion occurs in priority.
Control of the bainitic structure for a wear-resisting hard-faced rail track
Authors: Suwanpinij Piyada , Thonondaeng Thanaporn , Kumma Parinya , Suksawat Bandit , Lothongkum Gobboon
Published: February 2022

Carbide-free bainite with filmlike retained austenite structure has been reported for its higher wear resistance and toughness compared with conventional bainite and pearlite structure. In order to take advantage from such beneficial structure, this study employs the surface welding method with self-shielded wire electrode containing low carbon (0.15 mass%), high silicon, and nickel on two pearlitic rail steels, R260 and R350HT. The preheating temperature and other welding parameters were carefully selected to avoid too high dilution, which leads to martensite formation. The weld metal, heat-affected zone, and base material were investigated by scanning electron microscopy. Microhardness and wear tests were carried out to ensure improved properties after the surface repair. The results show significant improvements in hardness and wear rate in weld metal compared with the base material.
Online monitoring of 3D printing of steel via optical emission spectroscopy
Authors: Pignatelli Giuseppe , Strasse Anne , Gumenyuk Andrey , Gornushkin Igor
Published: February 2022

Additive manufacturing by laser metal deposition (LMD) requires continuous online monitoring to ensure quality of printed parts. Optical emission spectroscopy (OES) is proposed for the online detection of printing defects by monitoring minute variations in the temperature of a printed spot during laser scan. A two-lens optical system is attached to a moving laser head and focused on a molten pool created on a substrate during LMD. The light emitted by the pool is collected by an ultraviolet–visible (UV–vis) spectrometer and processed. Two metrics are used to monitor variations in the surface temperature: the spectrally integrated emission intensity and correlation coefficient. The variations in the temperature are introduced by artificial defects, shallow grooves, and holes of various widths and diameters carved on a substrate surface. The metrics show sufficient sensitivity for revealing the surface defects, except for the smallest holes with an under-millimeter diameter. Additionally, numeric simulations are carried out for the detection of emission in the UV–vis and near-infrared (NIR) spectral ranges at various surface temperatures. It is concluded that both the metrics perform better in the NIR range. In general, this work demonstrates that spectrally resolved OES suits well for monitoring surface defects during 3D metal printing.
Meta-lens light-sheet fluorescence microscopy for in vivo imaging
Authors: Luo Yuan , Tseng Ming Lun , Vyas Sunil , Hsieh Ting-Yu , Wu Jui-Ching , Chen Shang-Yang , Peng Hsiao-Fang , Su Vin-Cent , Huang Tzu-Ting , Kuo Hsin Yu , Chu Cheng Hung , Chen Mu Ku , Chen Jia-Wern , Chen Yu-Chun , Huang Kuang-Yuh , Kuan Chieh-Hsiung , Shi Xu , Misawa Hiroaki , Tsai Din Ping
Published: February 2022

Light-sheet fluorescent microscopy has become the leading technique for in vivo imaging in the fields of disease, medicine, and cell biology research. However, designing proper illumination for high image resolution and optical sectioning is challenging. Another issue is geometric constraints arising from the multiple bulky components for illumination and detection. Here, we demonstrate that those issues can be well addressed by integrating nanophotonic meta-lens as the illumination component for LSFM. The meta-lens is composed of 800-nm-thick GaN nanostructures and is designed for a light-sheet well-adapted to biological specimens such as the nematode Caenorhabditis elegans (C. elegans). With the meta-lens, the complexity of the LSFM system is significantly reduced, and it is capable of performing multicolor fluorescent imaging of live C. elegans with cellular resolution. Considering the miniature size and plane geometry of the meta-lens, our system enables a new design for LSFM to acquire in vivo images of biological specimens with high resolution.
Crystal structure of a second modification of Pachypodol, C18H16O7
Authors: Xu Chuan-Yan , Dong Ming-Hong , Ye Jiang-Hai , Zhao Chen-Liang , Zou Juan , Zhang Jing-Jie
Published: February 2022

C18H16O7, monoclinic, P21/c (no. 14), a = 7.3948(3) Å, b = 24.2947(9) Å, c = 17.3201(6) Å, β = 93.063(1)°, V = 3107.2(2) Å3, Z = 4, R

gt
(F) = 0.0427, wR

ref
(F
2) = 0.1241, T = 300(2) K.
The crystal structure of catena-poly[(m2-4,4′-bipyridine-κ2
N:N)-bis(6-phenylpyridine-2-carboxylato-κ2
N,O) zinc(II)], C34H24N4O4Zn
Authors: Wang Li-Hua , Tai Xi-Shi , Xia Yu-Pei
Published: February 2022

C34H24N4O4Zn, monoclinic, I2/a (no. 15), a = 18.2546(14) Å, b = 11.0510(7) Å, c = 16.1874(15) Å, β = 119.605(11)°, V = 2839.2(5) Å3, Z = 4, R

gt
(F) = 0.0302, wR

ref
(F
2) = 0.0694, T = 200 K.
The crystal structure of (4SR)-7-(3,4-dichlorobenzyl)-4,8,8-trimethyl-7,8-dihydroimidazo[5,1c][1,2,4]triazine-3,6(2H,4H)-dione, C15H16Cl2N4O2
Authors: Tzvetkov Nikolay T. , Peeva Martina I. , Tsakovska Ivanka , Milella Luigi , Pajeva Ilza , Stammler Hans-Georg
Published: February 2022

C15H16Cl2N4O2, monoclinic, P21/c (no. 14), a = 26.2014(7) Å, b = 7.59320(10) Å, c = 17.9766(4) Å, β = 109.217(3)°, V = 3377.20(14) Å3, Z = 8, R

gt
(F) = 0.0503, wR

ref
(F
2) = 0.1411, T = 100.0(1) K.
Caves, Senses, and Ritual Flows in the Iberian Iron Age: The Territory of Edeta
Authors: Machause López Sonia , Skeates Robin
Published: February 2022

This article seeks to contribute to recent scholarship on ritual performances in caves, sensory archaeology and ritual journeys, and to stimulate fresh questions and debate about society, ritual, and mobility in the Iberian Iron Age. It uses an updated methodology for recording and interpreting – more contextually, holistically, and systematically – the multisensory affordances of caves and their landscapes on embodied human movements, experiences, and perceptions. It applies this approach to two caves situated in the territory thought by archaeologists to have been controlled by the Iberian Iron Age oppidum of Edeta/Tossal de Sant Miquel in the Valencia province: both interpreted as the destination for “pilgrimages” and related ritual performances, especially during the fifth to third centuries BC. In particular, the study presents a thick and multifaceted interpretative scenario of ritual flows to, through, and from these underground places, divided analytically into successive experiential stages. It concludes by questioning the current model of Iberian Iron Age ritual as an elite-dominated process and instead emphasises variability in multisensory ritual decision-making, practices and experiences over space, time, and culture.
ACTIVATE! Change Drivers: blame-attribution and active citizenship on a South Africa youth blog
Authors: Conradie Marthinus Stander
Published: February 2022

Processes of blame-attribution can be conceptualised as socially-situated and discursively-mediated events that feature attempts to assign meaning to harmful (or at least potentially harmful) occurrences. Part of the process involves the search for culprits and subsequent argumentation as to the blameworthiness of those singled out for blame. This study conducts a discourse analysis of blame-attribution in 33 online opinion pieces, posted on the website of the civil society organisation: ACTIVATE! Change Drivers. It concentrates on arguments that address the nexus between youth activism, active citizenship, the legacy of Apartheid and blame for the numerous problems afflicting the South African youth. The most recurring arguments hinged on constructions of the South African government as responsible to supporting the capacity of the contemporary youth to participate effectively in democracy, particularly since the youth continue to endure the repercussions of Apartheid. My analysis details the discursive repertoires through which this proposition is made, and considers its implications for research into contemporary online youth cultures and democratic argumentation.
Education in the Anthropocene: From Theorists towards Young Climate Activists
Authors: Kairė Sandra
Published: February 2022

This paper continues the scientific discussion on education in the Anthropocene and focuses on the complexity of future education from the learner’s perspective. The first part of the paper explores proposals for education in the Anthropocene from the posthumanist perspective, based on the critical remarks and ideas of different theorists, such as Annette Gough, Nathan Snaza, and Brad Petitfils. The second part focuses on the children of the Anthropocene as the reality of today’s education. The third part looks at the case of young climate activists, who can be considered to be children of the Anthropocene, and how their relationship with education is changing. Young climate activists experience doubts, distrust, and disappointment over formal education, its practice, and its future. Therefore, climate activism movements can be treated as a unique learning environment for young people that also compensates what children of the Anthropocene are missing in formal education.
An Encounter between a Teacher and Child with ASD in a Pre-School Environment
Authors: Juškienė Vaiva , Voidogaitė Viktorija
Published: February 2022

The article focuses on the phenomenon of the first meeting between an educator and a child on the autism spectrum and the an educator’s experiences during the encounter. An analysis of the scientific literature shows that the number of autistic children in Lithuania is increasing. The text describes a meeting between a pre-school and a pre-primary school educator and a child with autism spectrum disorders. The analysis unfolds the experience of particular educators when they meet a child with ASD in an ordinary pre-school group. During a hermeneutical phenomenological analysis, the experience of the educators are based on two existential subjects: experienced relationship and experienced body. During the first meeting with a child with ASD, educators attempted to establish a relationship with the child. Although each participant of the analysis experienced this beginning individually, all of them were confronted with a challenge in communication while establishing these relationships. Autistic children avoided the methods of relation contracting that were usual to educators. When educators contacted with the autistic children, their experience unfolded through the children’s bodily experience (appearance and behaviour).
An Architectural Model for the 21st Century School: Synthesis of Research Results
Authors: Vilbikienė Grėtė
Published: February 2022

This paper is intended to identify the most relevant and most frequently discussed research topics in the literature, including pedagogy and the physical learning environment. It can be stated that the goals and objectives of education may even indirectly be related to the physical learning environment; therefore, it is relevant to analyze the ways, means, aspects and methodologies of this interface in the research works of other researchers. To achieve this goal, the article presents a systematic analysis of literature sources. Based on the conclusions of the systematic analysis and the goals and objectives of modern education, the model of a good school in the general case was formed and presented in the article. This is the 21st century school model that reveals those factors and characteristics of the physical learning environment that would help create a physical learning environment corresponding to modern education.
Knowledge Valorisation in Doctoral Studies in Latvia: Entrepreneurship and the Development of Research Competencies in the Study Process
Authors: Slišāne Agnese , Lāma Gatis , Bernande Māra
Published: February 2022

The purpose of this paper is to analyse the self-assessment data of Latvian doctoral students relating to their entrepreneurship and research competencies and to explore how it correlates and what can be done to promote valorisation during the study process.An online survey using the QuestionPro platform was used to collect the data. The survey was fully completed by 43 doctoral students from various higher education institutions, and it consisted of 123 statements in which doctoral students assessed their competencies on a 7-point Likert scale. Five structured interviews were conducted in order to identify the supporting environment and other aspects that have an impact on the development of entrepreneurship and research competencies.The results of the research demonstrate a relatively low self-assessment of entrepreneurship competencies, which points to why doctoral students are unable to commercialise their knowledge. Unlike entrepreneurship competencies, research competencies can be considered as very high. According to the data, there is no clear correlation between entrepreneurship competence and research competence. The results also point to the fact that it is not sufficient to develop only one of the two competencies to ensure the valorisation of knowledge.For data to be fully representative, a higher number of respondents would have been desirable as well as a greater diversity of study programs represented, assuming that knowledge valorisation approaches and opportunities differ across sectors.Nonetheless, the results can be used for the development and implementation of the valorisation initiatives of higher education institutions.
Language Learning Attitudes of Young Learners: Differences between Syrian Refugee Learners and Turkish Learners
Authors: Asmali Mehmet , Sayın Sanem Dilbaz
Published: February 2022

Welcoming more than 1.7 million refugee and asylum-seeker children, Turkey has put a considerable effort in turning this tragedy into an advantage for these children in terms of their education. Language teaching has played a remarkable role in this effort. Turkey has offered both Turkish and English language courses to these people. Considering the significance of English as a global language for social integration and future studies, this study attempted to investigate young Syrian refugee students’ attitudes toward English language and their reasons to learn English. Moreover, their perspectives were compared with Turkish young learners. Thirty-eight Turkish and 26 Syrian 5th graders (aged 10–11) voluntarily participated in this study. The findings indicated that learning English makes Syrian students happy, whereas Turkish students enjoy the fun activities in English classes. Learning English is considered both relatively easy and important by both groups. Turkish and Syrian young learners’ reasons to learn English differed slightly. Suggestions were provided for refugee young learners to overcome the potential problems regarding language learning.
Pupils’ Literacy Problems in the Essays of Lithuanian Language and Literature State Matura Examinations: Gaps in the Knowledge of Syntax
Authors: Bučienė Laimutė
Published: February 2022

Based on the syntactic analysis of the essays composed in the course of the matura examination in 2019, the article seeks to answer the following major questions: How well are 12th grade pupils capable of observing the syntactic norms while writing a fluent text? Which syntactic phenomena do pupils find the most troublesome?A quantitative study revealed that the pupils have an insufficient knowledge of syntactic norms. Pupils find case government, the combinability of words, the choice of word forms in a phrase and in a sentence the most troublesome. The greatest syntactic problem is the incorrect use of cases. What is most obvious and problematic concerning case-related mistakes is the use of the instrumental case to express a state instead of the second component of double cases. The expression of the indefinite amount of things and the whole is also rather troublesome (the use of the accusative case instead of the genitive case expressing an indefinite amount or a part). In their essays, pupils often make mistakes in the use of the gerund. The mistakes related to the composition of the complex sentence are also rather numerous.It should be noted that the teaching of language system-related topics should pay adequate attention to the practical issues of language teaching as well as to tasks focusing on the correct usage of the spoken and written language.The errors made by 12th grade pupils show that it is essential to improve the skills of the correct usage of syntactic constructions in the final grades with due regard to the individual needs of pupils and the class.
Teachers’ Attitudes on the Development of Critical Thinking by Experiential Learning
Authors: Pongračić Luka , Marinac Ana Maria
Published: February 2022

The content that is taught in school, but also outside it, needs to be connected with real (everyday) life. Teachers need to turn content into experience for their students, which is no easy task. The aim of this research is to determine the extent to which primary school teachers, secondary school teachers, and higher education teachers use this method in their work in order to develop critical thinking in their students and how much importance they attach to it during their work in teaching. A questionnaire on critical thinking and experiential learning (N = 168) was conducted, the results of which were analyzed with regard to gender, level of education, work experience, diluted to teach the work environment. The results show that the method of experiential learning with the aim of developing critical thinking is used to a greater extent in teaching (mean = 4.17, SD = 0.55). Differences were observed only with respect to work experience, where teachers with more work experience work statistically significantly more (F = 0.027; t = 3.31; p < 0.01) on developing critical thinking. On the other hand, the need for further awareness, especially of younger teachers, on how to apply experiential learning and what it is important for has been proven. This research has shown the already recognized importance and aspiration to develop critical thinking in students at all levels of education, which will ultimately result in both developed and self-aware individuals and society. It is worrying that about 40% of teachers still do not conduct interactive learning on a regular basis, but it is encouraging that most teachers still recognize how important it is and apply it on a daily basis.
Técnico-administrativos em educação das IFES: carreira e institucionalidade
Authors: Basso dos Reis Guilherme , Valéria Paixão Márcia
Published: February 2022

Os técnico-administrativos em educação (TAEs) representam uma das três categorias que compõe a comunidade acadêmica das Instituições Federais de Ensino Superior (IFES), junto aos docentes e discentes. Este trabalho apresenta o desenvolvimento histórico desta carreira, em sua relação com as disputas na sociedade brasileira, a legislação e o contexto institucional. A pesquisa bibliográfica e documental (legislação) desenvolvida aponta que a conquista do Plano de Carreira dos Cargos Técnico-Administrativos em Educação (PCCTAE), obtida através de processos de luta, reivindicação e negociação da categoria, apresenta-se como um momento importante e fundamental na definição de identidade da categoria. O mesmo se dá com os avanços obtidos na legislação de criação dos Institutos Federais e em seus regulamentos próprios. Desta forma, através destas conquistas, o desenvolvimento da carreira dos servidores TAEs passa a ser associado ao planejamento institucional e aos projetos e políticas públicas nacionais.
De la hacienda, el hato y la roza a la mesa: productividad, mercantilización y consumo de alimentos en las Gobernaciones de Santa Marta y Cartagena vista por viajeros, 1820-1900
Authors: Sánchez Mejia Hugues Rafael
Published: February 2022

Este artículo busca construir, a partir de las descripciones que, sobre la producción, venta y consumo de alimentos, realizaron un grupo de viajeros que visitaron el Caribe colombiano durante el siglo XIX, una narrativa que permita dar una historicidad a dichos eventos y el acto de alimentarse. Estos viajeros, de diversas nacionalidades y profesiones, con sus imágenes aportan al conocimiento particular de sucesos que, conectados, permiten realizar una lectura bien particular sobre la forma como los habitantes de la región Caribe enfrentaban las durezas de un ecosistema y el hecho de llevar los alimentos de las unidades productivas a la mesa. Se hace énfasis en la venta de alimentos en los mercados, el lugar donde se producían y las presunciones que los viajeros tenían sobre el trabajo de campesinos y pescadores.
Imágenes y representaciones de España en el México independiente: una mirada desde la prensa oficial (1821-1823)
Authors: Escrig Rosa Josep
Published: February 2022

En este artículo se analiza el discurso de la Gaceta Imperial de México, medio de comunicación gubernamental, durante el periodo del Primer Imperio. Se busca identificar los sentidos de la imagen negativa de España y su proyección sobre la política interna del país independiente. El periodo del Trienio Liberal español fue presentado como un momento anárquico de guerra civil entre liberales y contrarrevolucionarios, así como una etapa destinada a acabar con la religión. Esta representación sirvió para insistir en la justicia y moderación de la independencia mexicana, criticar la supuesta deriva radical del liberalismo hispano y, en su momento, reforzar la posición del emperador Agustín de Iturbide.
El puñal en la garganta del opresor. Intelectuales y violencia política en la Colombia actual
Authors: Vanegas Useche Isidro
Published: February 2022

Este artículo reconstruye el lugar que una parte de los intelectuales colombianos, los que podrían denominarse como progresistas, le dieron a la violencia como instrumento de acción política, en el periodo comprendido entre 1985 y la actualidad. Constata cómo entre ellos disminuyeron los apologistas de la violencia como agente creador de un nuevo orden, pero cómo esa actitud no dio lugar a un rechazo absoluto de ella, pues pasó a ser justificada como garante de unos cambios, imprescindibles, que por la vía normal supuestamente no eran posibles.
Cultura cinematográfica en Cartagena 1958 – 1971: Palacios populares, cineclubes y subjetividades fílmicas
Authors: Chica Geliz Ricardo
Published: February 2022

Artículo resultado de la investigación “Cultura cinematográfica en Cartagena 1958 – 1971” y analiza la experiencia de ver cine en la ciudad, durante los años sesenta, según el enfoque metodológico de la historia social del cine. Se pretende seguir la pista histórica de la expectativa, como un aspecto clave en la formación de las subjetividades fílmicas frente a la cartelera cinematográfica de entonces. Una expectativa relativa a la tensión entre el cine de las lágrimas, el melodrama; y el cine de avanzada, en especial, el nuevo cine latinoamericano. Una tensión entre el palacio popular y el cineclub en un contexto de contracultura.
Visually Grounded Models of Spoken Language: A Survey of Datasets, Architectures and Evaluation Techniques
Authors: Chrupała Grzegorz
Published: February 2022

This survey provides an overview of the evolution of visually grounded models of spoken language over the last 20 years. Such models are inspired by the observation that when children pick up a language, they rely on a wide range of indirect and noisy clues, crucially including signals from the visual modality co-occurring with spoken utterances. Several fields have made important contributions to this approach to modeling or mimicking the process of learning language: Machine Learning, Natural Language and Speech Processing, Computer Vision and Cognitive Science. The current paper brings together these contributions in order to provide a useful introduction and overview for practitioners in all these areas. We discuss the central research questions addressed, the timeline of developments, and the datasets which enabled much of this work. We then summarize the main modeling architectures and offer an exhaustive overview of the evaluation metrics and analysis techniques.