Biowissenschaften

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Non Thermal Plasma Sources of Production of Active Species for Biomedical Uses: Analyses, Optimization and Prospect
(London : IntechOpen, 2011) Yousfi, M.; Merbahi, N.; Sarrette, P. J.; Eichwald, O.; Ricard, A.; Gardou, J.P.; Ducasse, O.; Benhenni, M.; Fazel-Rezai, Reza
[no abstract available]
Complexes in the Photocatalytic Reaction of CO 2 and H 2O: Theoretical Studies
(Basel : Molecular Diversity Preservation International, 2010) Luo, Dongmei; Zhang, Ning; Hong, Sanguo; Wu, Huanwen; Liu, Zhihua
Complexes (H 2O/CO 2, e-(H 2O/CO 2) and h +-(H 2O/CO 2)) in the reaction system of CO 2 photoreduction with H 2O were researched by B3LYP and MP2 methods along with natural bond orbital (NBO) analysis. Geometries of these complexes were optimized and frequencies analysis performed. H 2O/CO 2 captured photo-induced electron and hole produced e-(H 2O/CO 2) and h +-(H 2O/CO 2), respectively. The results revealed that CO 2 and H 2O molecules could be activated by the photo-induced electrons and holes, and each of these complexes possessed two isomers. Due to the effect of photo-induced electrons, the bond length of C=O and H-O were lengthened, while H-O bonds were shortened, influenced by holes. The infrared (IR) adsorption frequencies of these complexes were different from that of CO 2 and H 2O, which might be attributed to the synergistic effect and which could not be captured experimentally. © 2010 by the authors; licensee MDPI, Basel, Switzerland.
Preface: In focus issue on nanoparticle interfaces
(Melville, NY : AIP, 2016) Ceccone, Giacomo; Shard, Alexander G.
[no abstract available]
The systems biology format converter
(London : BioMed Central, 2016) Rodriguez, Nicolas; Pettit, Jean-Baptiste; Dalle Pezze, Piero; Li, Lu; Henry, Arnaud; van Iersel, Martijn P.; Jalowicki, Gael; Kutmon, Martina; Natarajan, Kedar N.; Tolnay, David; Stefan, Melanie I.; Evelo, Chris T.; Le Novère, Nicolas
Background: Interoperability between formats is a recurring problem in systems biology research. Many tools have been developed to convert computational models from one format to another. However, they have been developed independently, resulting in redundancy of efforts and lack of synergy. Results: Here we present the System Biology Format Converter (SBFC), which provide a generic framework to potentially convert any format into another. The framework currently includes several converters translating between the following formats: SBML, BioPAX, SBGN-ML, Matlab, Octave, XPP, GPML, Dot, MDL and APM. This software is written in Java and can be used as a standalone executable or web service. Conclusions: The SBFC framework is an evolving software project. Existing converters can be used and improved, and new converters can be easily added, making SBFC useful to both modellers and developers. The source code and documentation of the framework are freely available from the project web site.
New Paradigm for a targeted cancer therapeutic approach: A short review on potential synergy of gold nanoparticles and Cold Atmospheric Plasma
(Basel : MDPI, 2017) Aryal, Sajesan; Bisht, Gunjan
Application of Gold nanoparticles and Cold Atmospheric plasma as a targeted therapeutic adjunct has been widely investigated separately in cancer therapy. Gold nanoparticles, with their biocompatibility, lower cytotoxicity and superior efficacy, are becoming substantially more significant in modern cancer therapy. Likewise, cold atmospheric plasma, with rich reactive species including reactive oxygen species (ROS) and reactive nitrogen species (RNS), is being explored to selectively target and kill cancer cells, making them a promising anticancer agent. Recent scientific studies have shown that there is a potential synergy between these two aspects. Induction of apoptosis/necrosis due to oxidative stress may be a probable mechanism of their cytotoxic effect. The synergetic effect of the two therapeutic approaches could be tantamount to maximized targeted efficacy on the treatment of diseases like cancer.
Provenance information as a tool for addressing engineered nanoparticle reproducibility challenges
(Melville, NY : AIP, 2016) Baer, Donald R.; Munusamy, Prabhakaran; Thrall, Brian D.
Nanoparticles of various types are of increasing research and technological importance in biological and other applications. Difficulties in the production and delivery of nanoparticles with consistent and well defined properties appear in many forms and have a variety of causes. Among several issues are those associated with incomplete information about the history of particles involved in research studies, including the synthesis method, sample history after synthesis, including time and nature of storage, and the detailed nature of any sample processing or modification. In addition, the tendency of particles to change with time or environmental condition suggests that the time between analysis and application is important and some type of consistency or verification process can be important. The essential history of a set of particles can be identified as provenance information and tells the origin or source of a batch of nano-objects along with information related to handling and any changes that may have taken place since it was originated. A record of sample provenance information for a set of particles can play a useful role in identifying some of the sources and decreasing the extent of particle variability and the lack of reproducibility observed by many researchers.
SciPy 1.0: fundamental algorithms for scientific computing in Python
(London [u.a.] : Nature Publishing Group, 2020) Virtanen, Pauli; Gommers, Ralf; Oliphant, Travis E.; Haberland, Matt; Reddy, Tyler; Cournapeau, David; Burovski, Evgeni; Peterson, Pearu; Weckesser, Warren; Bright, Jonathan; van der Walt, Stéfan J.; Brett, Matthew; Wilson, Joshua; Millman, K. Jarrod; Mayorov, Nikolay; Nelson, Andrew R. J.; Jones, Eric; Kern, Robert; Larson, Eric; Carey, C J; Polat, İlhan; Feng, Yu; Moore, Eric W.; VanderPlas, Jake; Laxalde, Denis; Perktold, Josef; Cimrman, Robert; Henriksen, Ian; Quintero, E. A.; Harris, Charles R.; Archibald, Anne M.; Ribeiro, Antônio H.; Pedregosa, Fabian; van Mulbregt, Paul; Vijaykumar, Aditya; Bardelli, Alessandro Pietro; Rothberg, Alex; Hilboll, Andreas; Kloeckner, Andreas; Scopatz, Anthony; Lee, Antony; Rokem, Ariel; Woods, C. Nathan; Fulton, Chad; Masson, Charles; Häggström, Christian; Fitzgerald, Clark; Nicholson, David A.; Hagen, David R.; Pasechnik, Dmitrii V.; Olivetti, Emanuele; Martin, Eric; Wieser, Eric; Silva, Fabrice; Lenders, Felix; Wilhelm, Florian; Young, G.; Price, Gavin A.; Ingold, Gert-Ludwig; Allen, Gregory E.; Lee, Gregory R.; Audren, Hervé; Probst, Irvin; Dietrich, Jörg P.; Silterra, Jacob; Webber, James T; Slavič, Janko; Nothman, Joel; Buchner, Johannes; Kulick, Johannes; Schönberger, Johannes L.; de Miranda Cardoso, José Vinícius; Reimer, Joscha; Harrington, Joseph; Rodríguez, Juan Luis Cano; Nunez-Iglesias, Juan; Kuczynski, Justin; Tritz, Kevin; Thoma, Martin; Newville, Matthew; Kümmerer, Matthias; Bolingbroke, Maximilian; Tartre, Michael; Pak, Mikhail; Smith, Nathaniel J.; Nowaczyk, Nikolai; Shebanov, Nikolay; Pavlyk, Oleksandr; Brodtkorb, Per A.; Lee, Perry; McGibbon, Robert T.; Feldbauer, Roman; Lewis, Sam; Tygier, Sam; Sievert, Scott; Vigna, Sebastiano; Peterson, Stefan; More, Surhud; Pudlik, Tadeusz; Oshima, Takuya; Pingel, Thomas J.; Robitaille, Thomas P.; Spura, Thomas; Jones, Thouis R.; Cera, Tim; Leslie, Tim; Zito, Tiziano; Krauss, Tom; Upadhyay, Utkarsh; Halchenko, Yaroslav O.; Vázquez-Baeza, Yoshiki
SciPy is an open-source scientific computing library for the Python programming language. Since its initial release in 2001, SciPy has become a de facto standard for leveraging scientific algorithms in Python, with over 600 unique code contributors, thousands of dependent packages, over 100,000 dependent repositories and millions of downloads per year. In this work, we provide an overview of the capabilities and development practices of SciPy 1.0 and highlight some recent technical developments.
Cold Plasma, a New Hope in the Field of Virus Inactivation
(Amsterdam [u.a.] : Elsevier Science, 2020) Filipić, Arijana; Gutierrez-Aguirre, Ion; Primc, Gregor; Mozetič, Miran; Dobnik, David
Viruses can infect all cell-based organisms, from bacteria to humans, animals, and plants. They are responsible for numerous cases of hospitalization, many deaths, and widespread crop destruction, all of which result in an enormous medical, economical, and biological burden. Each of the currently used decontamination methods has important drawbacks. Cold plasma (CP) has entered this field as a novel, efficient, and clean solution for virus inactivation. We present recent developments in this promising field of CP-mediated virus inactivation, and describe the applications and mechanisms of the inactivation. This is particularly relevant because viral pandemics, such as COVID-19, highlight the need for alternative virus inactivation methods to replace, complement, or upgrade existing procedures.
A Methodology for Vertical Translation Between Molecular and Organismal Level in Biological Feedback Loops
(Cold Spring Harbor : Cold Spring Harbor Laboratory, NY, 2021-09-15) Dietrich, Johannes W.
Feedback loops are among the primary network motifs in living organisms, ensuring survival via homeostatic control of key metabolites and physical properties. However, from a scientific perspective, their characterization is unsatisfactory, since the usual modelling methodology is incompatible with the physiological and biochemical basis of metabolic networks. Therefore, any “vertical translation”, i.e. the study of the correspondence between molecular and organismal levels of causality, is difficult and in most cases impossible. As a viable solution, we demonstrate an alternative modelling platform for biological feedback loops that is based on key biochemical principles, including mass action law, enzyme kinetics, binding of mediators to transporters and receptors, and basic pharmacological properties. Subsequently, we show how this framework can be used for translating from molecular to systems-level behaviour. Basic elements of the proposed modelling platform include Michaelis-Menten kinetics defining nonlinear dependence of the output y(t) on an input signal x(t) with the Hill-Langmuir equation y(t) = G * x(t)^n / (D + x(t)^n), non-competitive inhibition for linking stimulatory and inhibitory inputs with y(t) = G + x1(t) / ((D + x1(t) * (1 + x2(t) / KI)) and processing structures for distribution and elimination. Depending on the structure of the feedback loop, its equifinal (steady-state) behaviour can be solved in form of polynomials, with a quadratic equation for the simplest case with one feedback loop and a Hill exponent of 1, and higher-grade polynomials for additional feedback loops and/or integer Hill exponents > 1. As a companion to the analytical solution, a flexible class library (CyberUnits) facilitates computer simulations for studying the transitional behaviour of the feedback loop. Unlike other modelling strategies in biocybernetics and systems biology, this platform allows for straightforward translation from the statistical properties of single molecules on a “microscopic” level to the behaviour of the whole feedback loop on an organismal “macroscopic” level. An example is the Michaelis constant D, which is equivalent to (k–1 + k2) / k1, where k1, k–1 and k2 denote the rate constants for the association and dissociation of the enzyme-substrate or receptor-hormone complex, respectively. From the perspective of a single molecule the rate constants represent the probability (per unit time) that the corresponding reaction will happen in the subsequent time interval. Therefore 1/k represents the mean lifetime of the complex. Very similar considerations apply to the other described constants of the feedback loop. In summary, this modelling technique renders the translation from a molecular level to a systems perspective possible. In addition to providing new insights into the physiology of biological feedback loops, it may be a valuable tool for multiple disciplines of biomedical research, including drug design, molecular genetics and investigations on the effects of endocrine disruptors.
P4-Endokrinologie – Kybernetische Perspektiven eines neuen Ansatzes
(Berlin : Leibniz-Sozietät der Wissenschaften zu Berlin, 2024-12-10) Dietrich, Johannes W.
Endocrine diseases convey far-reaching consequences for individual health, ranging from a reduced quality of life over an increased risk of serious secondary diseases to acutely life-threatening conditions. In recent decades, endocrinology has faced considerable progress, for example in molecular biological research, assay technology and therapeutic options. However, serious gaps remain open that prevent the derivation of a unified endocrine theory and the development of a predictive, preventive, personalised and participatory medicine (P4 medicine). As a possible brick for a solution, we have developed the universal non-linear "MiMe-NoCoDI" platform for formulating cybernetic models of endocrine networks. It allows the development of mathematical "high fidelity" descriptions as well as the implementation of simulations on digital and analog computers. In addition, it provides the basis for new diagnostic procedures in the form of calculated biomarkers (structure parameter inference approach-SPINA) and approaches to therapy planning (set point optimisation and targeting-SPOT), which are superior to previous methods of clinical endocrinology. This progress paves the way for a future precision endocrinology with applications ranging from vertically integrated physiology over individually planned patient treatment to macro-strategies in the public healthcare system.
Engineered living materials for the conversion of a low-cost food-grade precursor to a high-value flavonoid
(Lausanne : Frontiers Media, 2023) Riedel, Florian; Bartolomé, Maria Puertas; Enrico, Lara Luana Teruel; Fink-Straube, Claudia; Duong, Cao Nguyen; Gherlone, Fabio; Huang, Ying; Valiante, Vito; Del Campo, Aránzazu; Sankaran, Shrikrishnan
Microbial biofactories allow the upscaled production of high-value compounds in biotechnological processes. This is particularly advantageous for compounds like flavonoids that promote better health through their antioxidant, anti-bacterial, anti-cancer and other beneficial effects but are produced in small quantities in their natural plant-based hosts. Bacteria like E. coli have been genetically modified with enzyme cascades to produce flavonoids like naringenin and pinocembrin from coumaric or cinnamic acid. Despite advancements in yield optimization, the production of these compounds still involves high costs associated with their biosynthesis, purification, storage and transport. An alternative production strategy could involve the direct delivery of the microbial biofactories to the body. In such a strategy, ensuring biocontainment of the engineered microbes in the body and controlling production rates are major challenges. In this study, these two aspects are addressed by developing engineered living materials (ELMs) consisting of probiotic microbial biofactories encapsulated in biocompatible hydrogels. Engineered probiotic E. coli Nissle 1917 able to efficiently convert cinnamic acid into pinocembrin were encapsulated in poly(vinyl alcohol)-based hydrogels. The biofactories are contained in the hydrogels for a month and remain metabolically active during this time. Control over production levels is achieved by the containment inside the material, which regulates bacteria growth, and by the amount of cinnamic acid in the medium.
NERNST: a genetically-encoded ratiometric non-destructive sensing tool to estimate NADP(H) redox status in bacterial, plant and animal systems
([London] : Springer Nature, 2023) Molinari, Pamela E.; Krapp, Adriana R.; Weiner, Andrea; Beyer, Hannes M.; Kondadi, Arun Kumar; Blomeier, Tim; López, Melina; Bustos-Sanmamed, Pilar; Tevere, Evelyn; Weber, Wilfried; Reichert, Andreas S.; Calcaterra, Nora B.; Beller, Mathias; Carrillo, Nestor; Zurbriggen, Matias D.
NADP(H) is a central metabolic hub providing reducing equivalents to multiple biosynthetic, regulatory and antioxidative pathways in all living organisms. While biosensors are available to determine NADP+ or NADPH levels in vivo, no probe exists to estimate the NADP(H) redox status, a determinant of the cell energy availability. We describe herein the design and characterization of a genetically-encoded ratiometric biosensor, termed NERNST, able to interact with NADP(H) and estimate E NADP(H). NERNST consists of a redox-sensitive green fluorescent protein (roGFP2) fused to an NADPH-thioredoxin reductase C module which selectively monitors NADP(H) redox states via oxido-reduction of the roGFP2 moiety. NERNST is functional in bacterial, plant and animal cells, and organelles such as chloroplasts and mitochondria. Using NERNST, we monitor NADP(H) dynamics during bacterial growth, environmental stresses in plants, metabolic challenges to mammalian cells, and wounding in zebrafish. NERNST estimates the NADP(H) redox poise in living organisms, with various potential applications in biochemical, biotechnological and biomedical research.
A Photoreceptor-Based Hydrogel with Red Light-Responsive Reversible Sol-Gel Transition as Transient Cellular Matrix
(Weinheim : Wiley, 2023) Hörner, Maximilian; Becker, Jan; Bohnert, Rebecca; Baños, Miguel; Jerez‐Longres, Carolina; Mühlhäuser, Vanessa; Härrer, Daniel; Wong, Tin Wang; Meier, Matthias; Weber, Wilfried
Hydrogels with adjustable mechanical properties have been engineered as matrices for mammalian cells and allow the dynamic, mechano-responsive manipulation of cell fate and function. Recent research yields hydrogels, where biological photoreceptors translated optical signals into a reversible and adjustable change in hydrogel mechanics. While their initial application provides important insights into mechanobiology, broader implementation is limited by a small dynamic range of addressable stiffness. Herein, this limitation is overcome by developing a photoreceptor-based hydrogel with reversibly adjustable stiffness from ≈800 Pa to the sol state. The hydrogel is based on star-shaped polyethylene glycol, functionalized with the red/far-red light photoreceptor phytochrome B (PhyB), or phytochrome-interacting factor 6 (PIF6). Upon illumination with red light, PhyB heterodimerizes with PIF6, thus crosslinking the polymers and resulting in gelation. However, upon illumination with far-red light, the proteins dissociate and trigger a complete gel-to-sol transition. The hydrogel's light-responsive mechanical properties are comprehensively characterized and it is applied as a reversible extracellular matrix for the spatiotemporally controlled deposition of mammalian cells within a microfluidic chip. It is anticipated that this technology will open new avenues for the site- and time-specific positioning of cells and will contribute to overcome spatial restrictions.
SEC14-GOLD protein PATELLIN2 binds IRON-REGULATED TRANSPORTER1 linking root iron uptake to vitamin E
(Oxford : Oxford University Press, 2023) Hornbergs, Jannik; Montag, Karolin; Loschwitz, Jennifer; Mohr, Inga; Poschmann, Gereon; Schnake, Anika; Gratz, Regina; Brumbarova, Tzvetina; Eutebach, Monique; Angrand, Kalina; Fink-Straube, Claudia; Stühler, Kai; Zeier, Jürgen; Hartmann, Laura; Strodel, Birgit; Ivanov, Rumen; Bauer, Petra
Organisms require micronutrients, and Arabidopsis (Arabidopsis thaliana) IRON-REGULATED TRANSPORTER1 (IRT1) is essential for iron (Fe2+) acquisition into root cells. Uptake of reactive Fe2+ exposes cells to the risk of membrane lipid peroxidation. Surprisingly little is known about how this is avoided. IRT1 activity is controlled by an intracellular variable region (IRT1vr) that acts as a regulatory protein interaction platform. Here, we describe that IRT1vr interacted with peripheral plasma membrane SEC14-Golgi dynamics (SEC14-GOLD) protein PATELLIN2 (PATL2). SEC14 proteins bind lipophilic substrates and transport or present them at the membrane. To date, no direct roles have been attributed to SEC14 proteins in Fe import. PATL2 affected root Fe acquisition responses, interacted with ROS response proteins in roots, and alleviated root lipid peroxidation. PATL2 had high affinity in vitro for the major lipophilic antioxidant vitamin E compound α-tocopherol. Molecular dynamics simulations provided insight into energetic constraints and the orientation and stability of the PATL2-ligand interaction in atomic detail. Hence, this work highlights a compelling mechanism connecting vitamin E with root metal ion transport at the plasma membrane with the participation of an IRT1-interacting and α-tocopherol-binding SEC14 protein.
Gelation Kinetics and Mechanical Properties of Thiol-Tetrazole Methylsulfone Hydrogels Designed for Cell Encapsulation
(Weinheim : Wiley-VCH, 2022) de Miguel‐Jiménez, Adrián; Ebeling, Bastian; Paez, Julieta I.; Fink‐Straube, Claudia; Pearson, Samuel; del Campo, Aránzazu
Hydrogel precursors that crosslink within minutes are essential for the development of cell encapsulation matrices and their implementation in automated systems. Such timescales allow sufficient mixing of cells and hydrogel precursors under low shear forces and the achievement of homogeneous networks and cell distributions in the 3D cell culture. The previous work showed that the thiol-tetrazole methylsulfone (TzMS) reaction crosslinks star-poly(ethylene glycol) (PEG) hydrogels within minutes at around physiological pH and can be accelerated or slowed down with small pH changes. The resulting hydrogels are cytocompatible and stable in cell culture conditions. Here, the gelation kinetics and mechanical properties of PEG-based hydrogels formed by thiol-TzMS crosslinking as a function of buffer, crosslinker structure and degree of TzMS functionality are reported. Crosslinkers of different architecture, length and chemical nature (PEG versus peptide) are tested, and degree of TzMS functionality is modified by inclusion of RGD cell-adhesive ligand, all at concentration ranges typically used in cell culture. These studies corroborate that thiol/PEG-4TzMS hydrogels show gelation times and stiffnesses that are suitable for 3D cell encapsulation and tunable through changes in hydrogel composition. The results of this study guide formulation of encapsulating hydrogels for manual and automated 3D cell culture.
Revealing the Meissner Corpuscles in Human Glabrous Skin Using In Vivo Non-Invasive Imaging Techniques
(Basel : Molecular Diversity Preservation International, 2023) Infante, Victor Hugo Pacagnelli; Bennewitz, Roland; Klein, Anna Lena; Meinke, Martina C.
The presence of mechanoreceptors in glabrous skin allows humans to discriminate textures by touch. The amount and distribution of these receptors defines our tactile sensitivity and can be affected by diseases such as diabetes, HIV-related pathologies, and hereditary neuropathies. The quantification of mechanoreceptors as clinical markers by biopsy is an invasive method of diagnosis. We report the localization and quantification of Meissner corpuscles in glabrous skin using in vivo, non-invasive optical microscopy techniques. Our approach is supported by the discovery of epidermal protrusions which are co-localized with Meissner corpuscles. Index fingers, small fingers, and tenar palm regions of ten participants were imaged by optical coherence tomography (OCT) and laser scan microscopy (LSM) to determine the thickness of the stratum corneum and epidermis and to count the Meissner corpuscles. We discovered that regions containing Meissner corpuscles could be easily identified by LSM with an enhanced optical reflectance above the corpuscles, caused by a protrusion of the strongly reflecting epidermis into the stratum corneum with its weak reflectance. We suggest that this local morphology above Meissner corpuscles has a function in tactile perception.
Self-Healing Iron Oxide Polyelectrolyte Nanocomposites: Influence of Particle Agglomeration and Water on Mechanical Properties
(Basel : MDPI, 2023) Oberhausen, Bastian; Plohl, Ajda; Niebuur, Bart-Jan; Diebels, Stefan; Jung, Anne; Kraus, Tobias; Kickelbick, Guido
Self-healing nanocomposites can be generated by organic functionalization of inorganic nanoparticles and complementary functionalization of the polymer matrix, allowing reversible interactions between the two components. Here, we report on self-healing nanocomposites based on ionic interactions between anionic copolymers consisting of di(ethylene glycol) methyl ether methacrylate, sodium 4-(methacryloyloxy)butan-1-sulfonate, and cationically functionalized iron oxide nanoparticles. The materials exhibited hygroscopic behavior. At water contents < 6%, the shear modulus was reduced by up to 90%. The nanoparticle concentration was identified as a second factor strongly influencing the mechanical properties of the materials. Backscattered scanning electron microscopy and small-angle X-ray scattering measurements showed the formation of agglomerates in the size range of 100 nm to a few µm in diameter, independent of concentration, resulting in the disordering of the semi-crystalline ionic polymer blocks. These effects resulted in an increase in the shear modulus of the composite from 3.7 MPa to 5.6 MPa, 6.3 Mpa, and 7.5 MPa for 2, 10, and 20 wt% particles, respectively. Temperature-induced self-healing was possible for all composites investigated. However, only 36% of the maximum stress could be recovered in systems with a low nanoparticle content, whereas the original properties were largely restored (>85%) at higher particle contents.
Topotaxis of Active Particles Induced by Spatially Heterogeneous Sliding along Obstacles
(Ithaca, NY : Cornell University, 2023) Sadjadi, Zeinab; Rieger, Heiko
Many biological active agents respond to gradients of environmental cues by redirecting their motion. Besides the well-studied prominent examples such as photo- and chemotaxis, there has been considerable recent interest in topotaxis, i.e.\ the ability to sense and follow topographic environmental cues. We numerically investigate the topotaxis of active agents moving in regular arrays of circular pillars. While a trivial topotaxis is achievable through a spatial gradient of obstacle density, here we show that imposing a gradient in the characteristics of agent-obstacle interaction can lead to an effective topotaxis in an environment with a spatially uniform density of obstacles. As a proof of concept, we demonstrate how a gradient in the angle of sliding around pillars -- as e.g.\ observed in bacterial dynamics near surfaces -- breaks the spatial symmetry and biases the direction of motion. We provide an explanation for this phenomenon based on effective reflection at the imaginary interface between pillars with different sliding angles. Our results are of technological importance for design of efficient taxis devices.
Structural Behaviour and Charge-Compensation Mechanism in Li2Fe1−xCoxSeO Solid Solutions during Reversible Delithiation
(Basel : MDPI, 2024) Gorbunov, Mikhail V.; Mikhailova, Daria
The constantly growing demand for renewable electrical energy keeps the continuation of battery-related research imperative. In spite of significant progress made in the development of Na- and K-ion systems, Li-ion batteries (LIBs) still prevail in the fields of portative devices and electric or hybrid vehicles. Since the amount of lithium on our planet is significantly limited, studies dedicated to the search for and development of novel materials, which would make LIBs more efficient in terms of their specific characteristics and life lengths, are necessary. Investigations of less industry-related systems are also important, as they provide general knowledge which helps in understanding directions and strategies for the improvement of applied materials. The current paper represents a comprehensive study of cubic Li2Fe1−xCoxSeO compounds with an anti-perovskite structure. These solid solutions demonstrate both cationic and anionic electrochemical activity in lithium cells while being applied as cathodes. Cobalt cations remain inactive; however, their amount in the structure defines if the Se0/Se2− or Fe3+/Fe2+ redox couple dominates the charge compensation mechanism upon (de)lithiation. Apart from that, cobalt affects the structural stability of the materials during cycling. These effects were evaluated by means of operando XRD and XAS techniques. The outcomes can be useful for both fundamental and practice-relevant research.
Steering of Vortices by Magnetic Field Tilting in Open Superconductor Nanotubes
(Basel : MDPI, 2024) Bogush, Igor; Fomin, Vladimir M.; Dobrovolskiy, Oleksandr V.
In planar superconductor thin films, the places of nucleation and arrangements of moving vortices are determined by structural defects. However, various applications of superconductors require reconfigurable steering of fluxons, which is hard to realize with geometrically predefined vortex pinning landscapes. Here, on the basis of the time-dependent Ginzburg–Landau equation, we present an approach for the steering of vortex chains and vortex jets in superconductor nanotubes containing a slit. The idea is based on the tilting of the magnetic field (Formula presented.) at an angle (Formula presented.) in the plane perpendicular to the axis of a nanotube carrying an azimuthal transport current. Namely, while at (Formula presented.), vortices move paraxially in opposite directions within each half-tube; an increase in (Formula presented.) displaces the areas with the close-to-maximum normal component (Formula presented.) to the close(opposite)-to-slit regions, giving rise to descending (ascending) branches in the induced-voltage frequency spectrum (Formula presented.). At lower B values, upon reaching the critical angle (Formula presented.), the close-to-slit vortex chains disappear, yielding (Formula presented.) of the (Formula presented.) type ((Formula presented.) : an integer; (Formula presented.) : the vortex nucleation frequency). At higher B values, (Formula presented.) is largely blurry because of multifurcations of vortex trajectories, leading to the coexistence of a vortex jet with two vortex chains at (Formula presented.). In addition to prospects for the tuning of GHz-frequency spectra and the steering of vortices as information bits, our findings lay the foundation for on-demand tuning of vortex arrangements in 3D superconductor membranes in tilted magnetic fields.

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