Delivery of TGFβ3 from magnetically responsive coaxial fibers reduces spinal cord astrocyte reactivity in vitro. - In: Advanced biology, ISSN 2701-0198, Bd. 0 (2024), 0, 2300531, S. 1-14
A spinal cord injury (SCI) compresses the spinal cord, killing neurons and glia at the injury site and resulting in prolonged inflammation and scarring that prevents regeneration. Astrocytes, the main glia in the spinal cord, become reactive following SCI and contribute to adverse outcomes. The anti-inflammatory cytokine transforming growth factor beta 3 (TGFβ3) has been shown to mitigate astrocyte reactivity; however, the effects of prolonged TGFβ3 exposure on reactive astrocyte phenotype have not yet been explored. This study investigates whether magnetic core-shell electrospun fibers can be used to alter the release rate of TGFβ3 using externally applied magnetic fields, with the eventual application of tailored drug delivery based on SCI severity. Magnetic core-shell fibers are fabricated by incorporating superparamagnetic iron oxide nanoparticles (SPIONs) into the shell and TGFβ3 into the core solution for coaxial electrospinning. Magnetic field stimulation increased the release rate of TGFβ3 from the fibers by 25% over 7 days and released TGFβ3 reduced gene expression of key astrocyte reactivity markers by at least twofold. This is the first study to magnetically deliver bioactive proteins from magnetic fibers and to assess the effect of sustained release of TGFβ3 on reactive astrocyte phenotype.
https://doi.org/10.1002/adbi.202300531
Simulation of heat transfer and propagation velocity for different heat loss conditions for guided propagation fronts in reactive multilayer foils. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, 2400523, S. 1-9
Engineering self-propagating reactions in reactive material systems requires an understanding of critical ignition and propagation conditions. These conditions are governed by the material properties of the reactive materials responsible for net heat generation, as well as by external environmental conditions that primarily determine net heat loss. In this study, it is aimed to utilize a numerical model to investigate the critical conditions for reaction propagation based solely on the heat-transfer equation, enabling thorough examination with significantly low computational effort. Comparing simulations with experiments demonstrates a high level of agreement in predicting reaction propagation. Additionally, this numerical model provides valuable information regarding heat distribution in substrate materials.
https://doi.org/10.1002/adem.202400523
Magnetic barium hexaferrite nanoparticles with tunable coercivity as potential magnetic heating agents. - In: Nanomaterials, ISSN 2079-4991, Bd. 14 (2024), 12, 992, S. 1-20
Using magnetic nanoparticles (MNPs) for extracorporeal heating applications results in higher field strength and, therefore, particles of higher coercivity can be used, compared to intracorporeal applications. In this study, we report the synthesis and characterization of barium hexa-ferrite (BaFe12O19) nanoparticles as potential particles for magnetic heating. Using a precipitation method followed by high-temperature calcination, we first studied the influence of varied synthesis parameters on the particles’ properties. Second, the iron-to-barium ratio (Fe/Ba = r) was varied between 2 and 12. Vibrating sample magnetometry, scanning electron microscopy and X-ray diffraction were used for characterization. A considerable influence of the calcination temperature (Tcal) was found on the resulting magnetic properties, with a decrease in coercivity (HC) from values above 370 kA/m for Tcal = 800-1000 ˚C to HC = 45-70 kA/m for Tcal = 1200 ˚C. We attribute this drop in HC mainly to the formation of entirely multi-domain particles at high Tcal. For the varying Fe/Ba ratios, increasing amounts of BaFe2O4 as an additional phase were detected by XRD in the small r (barium surplus) samples, lowering the particles’ magnetization. A decrease in HC was found in the increased r samples. Crystal size ranged from 47 nm to 240 nm and large agglomerates were seen in SEM images. The reported particles, due to their controllable coercivity, can be a candidate for extracorporeal heating applications in the biomedical or biotechnological field.
https://doi.org/10.3390/nano14120992
A new stress tensor approach for application to the conductor surface. - In: Compel, ISSN 2054-5606, Bd. 0 (2024), 0
Purpose: The purpose of this paper is to derive a new stress tensor for calculating the Lorentz force acting on an arbitrarily shaped nonmagnetic conductive specimen moving in the field of a permanent magnet. The stress tensor allows for a transition from a volume to a surface integral for force calculation. Design/methodology/approach: This paper derives a new stress tensor which consists of two parts: the first part corresponds to the scaled Poynting vector and the second part corresponds to the velocity term. This paper converts the triple integral over the volume of the conductor to a double integral over its surface, where the subintegral functions are continuous through the different compartments of the model. Numerical results and comparison to the standard volume discretization using the finite element method are given. Findings: This paper evaluated the performance of the new stress tensor computation on a thick and thin cuboid, a thin disk, a sphere and a thin cuboid containing a surface defect. The integrals are valid for any geometry of the specimen and the position and orientation of the magnet. The normalized root mean square errors are below 0.26% with respect to a reference finite element solution applying volume integration. Originality/value: Tensor elements are continuous throughout the model, allowing integration directly over the conductor surface.
https://doi.org/10.1108/COMPEL-10-2023-0543
Uncertainty of surface temperature measurement in coordinate measuring machines :
Unsicherheit der Oberflächentemperaturmessung in Koordinatenmessgeräten. - In: Technisches Messen, ISSN 2196-7113, Bd. 0 (2024), 0, S. 1-10
In der Präzisionslängenmesstechnik ist die Werkstücktemperatur aufgrund der Temperaturabhängigkeit der Materialeigenschaften eine wichtige Einflussgröße und liefert einen Beitrag zur Messunsicherheit. Neben den Einflüssen der Umgebung wie Temperaturschwankungen oder Bodenschwingungen auf das Koordinatenmessgerät selbst spielen auch die Einflüsse der Umgebung auf das Werkstück eine wichtige Rolle. Hierzu zählt neben den Temperaturschwankungen im Raum auch die jeweilige Vortemperierung der Werkstücke. Insbesondere führen die vorherige Bearbeitung und die Lagerung des Werkstücks zu Unterschieden zwischen der Oberflächen- und der Innentemperatur. Je größer die Genauigkeit der Temperaturbestimmung ist, desto kleiner sind die Messabweichungen. Deshalb wird zum Beispiel in Koordinatenmessgeräten während der Längenmessung die Temperatur im Messraum überwacht sowie die Temperaturen an der Oberfläche der Längenmesssysteme an den Messachsen und an der Oberfläche des Werkstücks erfasst und zur Onlinekorrektur der Messwerte verwendet. Zur Bestimmung der Werkstückoberflächentemperatur und der Kompensation dieser Temperatureinflüsse werden sowohl an den Werkstücken statisch, durch Magnete, befestigte Werkstücktemperatursensoren (Magnetfühler) verwendet als auch vor der Längenmessung automatisch einwechselbare Werkstücktemperatursensoren (Taster). Die Messunsicherheit dieser Temperatursensoren wird meist durch Kalibrierung in Flüssigkeitsbädern bestimmt. Dabei werden jedoch die Messunsicherheitsanteile, die durch das Aufsetzen auf die Oberfläche entstehen, nicht berücksichtigt. Diese Messunsicherheitsanteile wurden umfassend untersucht und werden im Beitrag vorgestellt.
https://doi.org/10.1515/teme-2024-0036
A bright future for electrodeposition. - In: The Electrochemical Society interface, ISSN 1944-8783, Bd. 33 (2024), 2, S. 45-46
The Electrodeposition Division, which was founded in 1922 as the second ECS division, celebrated their centennial anniversary at the 242nd ECS Fall meeting in Atlanta. For the occasion, the division organized several sessions with invited contributions to honor the achievements of 100 years of electrodeposition, but also to take a closer look at the present trendsetters and give a perspective on future challenges and opportunities in this thriving field. Our then newly established Electrodeposition Early Career Forum (ECF, founded in Spring 2022) organized a full day symposium with contributions from outstanding early-career researchers involved in cutting-edge research across a broad range of areas of active electrodeposition research. It turned out to be a fantastic day with invigorating talks full of ideas. The ELDP division decided to share some of the excitement with the ECS community and asked our ECF members to suggest topics and participate in the articles for this summer edition of Interface dedicated to Electrochemical and Electroless deposition. Dr. Kent Zheng, assistant professor at the University of Texas and Dr. Martin Leimbach, postdoc at TU Ilmenau, Germany, took up the challenge. Together with us, humble guest editors, four articles have been selected centred around three important topics: (1) electrodeposition for manufacturing and sustainability, edited by Prof. Luca Magagnin; (2) electrodeposition for energy applications, edited by Prof. Natasa Vasiljevic; and (3) new electrodeposition approaches extending the material library, edited by Prof. Philippe Vereecken.
https://doi.org/10.1149/2.F08242IF
Temporal and spatial determination of solidification rate during pulsed laser beam welding of hot-crack susceptible aluminum alloys by means of high-speed synchrotron X-ray imaging. - In: Journal of advanced joining processes, ISSN 2666-3309, Bd. 10 (2024), 100235, S. 1-11
Richtiger Name des 4. Verfassers: Christian Diegel
Pulsed laser beam welding is primarily used to join thin-walled components. The use of 6xxx group aluminum alloys is characterized by good mechanical properties but these alloys are prone to hot cracking during solidification, i.e., requirements regarding strength and tightness, as increasingly important for electromobility related applications, cannot be fulfilled. The solidification rate has been identified as dominant factor in pulsed conduction welding which can be adjusted by the pulse shape, i.e., by varying the beam power over time for a single pulse. Pulse shapes with different, linear ramp-down slopes were studied to describe the interaction between beam power and resulting solidification rate for spot welds. Based on rotationally symmetric conditions of the spot welds, the solidification rate can be measured in radial and vertical directions. The welding process of EN AW 6082 alloy was examined by in situ high-speed synchrotron X-ray imaging at the European Synchrotron Radiation Facility (ESRF) for this reason. Frame rates up to 120,000 Hz and subsequent image analysis allowed in-depth analysis of the solidification processes, their dependence on different spatial directions, and the resulting effects on hot crack formation.
https://doi.org/10.1016/j.jajp.2024.100235
Advancements in electrodeposition for precise manufacturing and sustainability. - In: The Electrochemical Society interface, ISSN 1944-8783, Bd. 33 (2024), 2, S. 47-54
Simply expressed, the circular economy implies that the people living on Earth should reuse and recycle the products that are currently in use as long as possible and reduce the waste produced, thus reducing CO2 emissions. The latter goal is fundamental from the perspective of mitigating the well-known greenhouse effect and the consequent global warming observed at the planetary scale. Under these conditions, advanced electrodeposition processes can play a fundamental role in the optimization of materials use and in the reduction of the energetic footprint for a wide variety of industrial processes. The aim of the present paper is precisely to suggest how this is possible, showing readers the potential that electrodeposition holds for efficient manufacturing of many different products that have a huge significance for industry.
https://doi.org/10.1149/2.F09242IF
Efficient tuning of the selectivity of Cu-based interface for electrocatalytic CO2 reduction by ligand modification. - In: Materials today, ISSN 2468-6069, Bd. 44 (2024), 101620, S. 1-12
The development of efficient strategies to tune the CO2RR selectivity of Cu-based catalytic interfaces, especially on specific domains, such as Cu (200) facets with high activity toward competitive hydrogenation evolution reaction (HER), remains a challenging task. In this work, Cu-based catalytic layers with thiocyanate (-SCN), cyanide (-CN), or ethylenediamine (-NH2R) coordination linkages are prepared on Cu nanocolumns arrays (Cu NCAs) with predominant (200) exposed facets. The coordination of these ligands induces more Cu+ species and inhibits the adsorption of H∗ on the Cu (200) facet, leading to enhanced CO2RR performance and substantially suppressing the competitive HER. The faradaic efficiency (FE) of Cu–SCN, Cu–CN, and Cu–NH2R NWAs for producing HCOOH, C2H4, and C1 mixture products (HCOOH and CO) reach to 66.5%, 21.1%, and 57.1%, respectively. In situ spectroscopic studies reveal Cu–SCN, Cu–CN, and Cu–NH2R exhibit more reasonable adsorption energy toward ∗OCHO, ∗CO, and ∗COOH intermediates, promoting the HCOOH, C2H4, and C1 mixture generation, respectively. This study might provide a new perspective for the development of high-performance Cu-based CO2RR catalytic electrodes based on the combination of various commercial free-standing Cu substrates and organic/inorganic ligands.
https://doi.org/10.1016/j.mtener.2024.101620
Tailoring phosphine ligands for improved C-H activation: insights from Δ-machine learning. - In: Digital discovery, ISSN 2635-098X, Bd. 0 (2024), 0, insges. 15 S.
Transition metal complexes have played crucial roles in various homogeneous catalytic processes due to their exceptional versatility. This adaptability stems not only from the central metal ions but also from the vast array of choices of the ligand spheres, which form an enormously large chemical space. For example, Rh complexes, with a well-designed ligand sphere, are known to be efficient in catalyzing the C-H activation process in alkanes. To investigate the structure-property relation of the Rh complex and identify the optimal ligand that minimizes the calculated reaction energy ΔE of an alkane C-H activation, we have applied a Δ-machine learning method trained on various features to study 1743 pairs of reactants (Rh(PLP)(Cl)(CO)) and intermediates (Rh(PLP)(Cl)(CO)(H)(propyl)). Our findings demonstrate that the models exhibit robust predictive performance when trained on features derived from electron density (R2 = 0.816), and SOAPs (R2 = 0.819), a set of position-based descriptors. Leveraging the model trained on xTB-SOAPs that only depend on the xTB-equilibrium structures, we propose an efficient and accurate screening procedure to explore the extensive chemical space of bisphosphine ligands. By applying this screening procedure, we identify ten newly selected reactant-intermediate pairs with an average ΔE of 33.2 kJ mol−1, remarkably lower than the average ΔE of the original data set of 68.0 kJ mol−1. This underscores the efficacy of our screening procedure in pinpointing structures with significantly lower energy levels.
https://doi.org/10.1039/D4DD00037D