Fast charging is considered to be a key requirement for widespread economic success of electric vehicles. Current lithium‐ion batteries (LIBs) offer high energy density enabling sufficient driving ...range, but take considerably longer to recharge than traditional vehicles. Multiple properties of the applied anode, cathode, and electrolyte materials influence the fast‐charging ability of a battery cell. In this review, the physicochemical basics of different material combinations are considered in detail, identifying the transport of lithium inside the electrodes as the crucial rate‐limiting steps for fast‐charging. Lithium diffusion within the active materials inherently slows down the charging process and causes high overpotentials. In addition, concentration polarization by slow lithium‐ion transport within the electrolyte phase in the porous electrodes also limits the charging rate. Both kinetic effects are responsible for lithium plating observed on graphite anodes. Conclusions drawn from potential and concentration profiles within LIB cells are complemented by extensive literature surveys on anode, cathode, and electrolyte materials—including solid‐state batteries. The advantages and disadvantages of typical LIB materials are analyzed, resulting in suggestions for optimum properties on the material and electrode level for fast‐charging applications. Finally, limitations on the cell level are discussed briefly as well.
The limited fast‐charging capabilities of state‐of‐the‐art lithium‐ion batteries hinder market adoption of electric vehicles. In this review, the physicochemical basics influencing fast charging are elucidated and material aspects are analyzed, resulting in lithium transport within the electrodes (active materials and electrolyte therein) as the crucial rate‐limiting process. Thus, ways to improve materials regarding their fast‐charging capabilities are suggested.
Recent discoveries of novel thermoelectric materials largely rely on an intrinsic low lattice thermal conductivity. This results from various mechanisms including low sound velocity, complex crystal ...structure, liquid‐like ions, and lattice anharmonicity. Here semiconducting Ag9AlSe6 with many weakly bonded and highly disordered cations is shown to be a promising novel thermoelectric material, due to its ultralow lattice thermal conductivity (κL) of ≈0.3 W m−1 K−1 in the entire temperature range. Such a low κL is believed to be a result of its (1) complex crystal structure for a small population of acoustic phonons, (2) soft bonding for an overall low sound velocity (1300 m s−1), and (3) massive disordering of Ag ions. Its electronic transport properties can be well understood by a single parabolic band model with acoustic scattering. The achieved thermoelectric figure of merit (zT) can be as high as unity, which is unlike conventional thermoelectric materials, which rely heavily on a high power factor. This work not only demonstrates Ag9AlSe6 as a promising thermoelectric material, but also paves the way for the exploration of novel thermoelectrics with a complex crystal structure with weakly bonded and highly disordered constituent elements in the structure.
A complex crystal structure, soft bonding, and disordering lead to an ultralow lattice thermal conductivity in a novel thermoelectric material Ag9AlSe6 showing a peak zT of unity. This paves the way for the exploration of novel thermoelectrics via a crystal structure design.
The preparation of absorber layers composed of methylammonium tin iodide (CH3NH3SnI3) in a two‐step process was investigated. This material is designed as a less toxic alternative to CH3NH3PbI3 which ...is commonly used as active material in perovskite solar cells. Tin(II) iodide (SnI2) layers prepared by physical vapor deposition were converted to CH3NH3SnI3 by reaction with a spin‐coated solution of methylammonium iodide (MAI). The perovskite particles formed in this process were over 200 nm in size and reached full surface coverage. A band gap of 1.23 eV was determined and the material, thus, absorbs over a broad part of the solar spectrum, broader even than CH3NH3PbI3. The chemical composition and solid state structure of the prepared films were analyzed by X‐ray photoelectron spectroscopy and X‐ray diffraction, respectively. The films turned out to be remarkably stable, another key prerequisite for applications as absorber layers in perovskite solar cells.
Organic metal halides provide absorber layers for solar cells, which may not only revolutionize the fundamental view on solution‐processed semiconductor materials but also the feasibility of sustainable large‐scale photovoltaics. Presently the chemical instability of these materials and the toxicity of predominantly used lead hinder commercialization. Replacement of lead and preparation of chemically more stable materials may represent a significant step towards a technical realization of perovskite solar cells.
Piezoceramic sensor and actuator assemblies are of increasing interest for various fields of application and attractive as part of lightweight design. As for the latter, polymers and fiber‐reinforced ...composites are appropriate as functional materials. Numerical simulations can be performed to predict mechanical and electrical performance of such active structure assemblies. Precise material parameters, however, are indispensable to obtain reliable simulation results. Manufacturer data is often not sufficient since it leads to major deviations between numerical simulation results and measurements. To enable reliable numerical simulations, the authors present a simulation‐based characterization approach for isotropic, transverse isotropic, and orthotropic polymer materials by means of adapting material parameters through an optimization algorithm. Frequency response function measurements of beam‐shaped test samples serve as input values. Thus, it is possible to identify values for linear viscoelastic material models and to provide direction‐dependent material parameters.
Frequency‐dependent material parameter identification by simulation‐based inverse method approach utilizing measurements of frequency response function for cantilever samples. Investigations comprise viscoelastic material models for polymers and characterization of orthotropic compound materials with respect to fiber orientation to increase accuracy of numerical simulations. Contribution deals with description of complete characterization approach and features identification of exemplary materials. (Photo: Kurt Fuchs).
The implementation of High-Speed Rail (HSR) is often expected to enhance urban development in municipalities benefitting from improved accessibility. This paper examines HSR as a driver of urban ...development and provides insights into the underlying interdependencies of urban planning practices and the impacts on urban development achieved or not yet realised. Our study investigates to what extent and in which ways HSR promotes spatial development in small-scale station areas. Thus, we carried out eight contrasting case studies in Germany. By extending previous research, we focussed on spatial impacts in narrowly defined HSR station areas and especially on their municipal planning governance by analysing the respective binding land-use plans (BLUP). As we will show, impacts are spatially and temporally varied but mainly limited to the immediate station areas, fostering agglomeration effects and new centralities. The case-dependent constraints observed and inherent preconditions witness the need for accompanying municipal planning governance to gain urban development impacts from the HSR-related accessibility improvements. Furthermore, the analyses presented underpin findings for research and practice, e.g. concerning the lack of integration of rail operations and local urban planning and the importance of consciously embedding HSR in local strategic concepts. Also, we use a new methodical approach to assess the possible impacts of HSR. Against the backdrop of further HSR expansion in Germany, anticipated but more strategically coordinated urban planning seems promising to exploit the potential for urban development in the station areas.
The need for tissue contact makes photoacoustic imaging not applicable for special medical applications like wound imaging, endoscopy, or laser surgery. An easy, stable, and contact-free sensing ...technique might thus help to broaden the applications of the medical imaging modality. In this work, it is demonstrated for the first time that remote photoacoustic sensing by speckle analysis can be performed in the MHz sampling range by tracking a single speckle using a four quadrant photo-detector. A single speckle, which is created by self-interference of surface back-reflection, is temporally analyzed using this photo-detector. Phantoms and skin samples are measured in transmission and reflection mode. The potential for miniaturization for endoscopic application is demonstrated by fiber bundle measurements. In addition, sensing parameters are discussed. Photoacoustic sensing in the MHz sampling range by single speckle analysis with the four quadrant detector is successfully demonstrated. Furthermore, the endoscopic applicability is proven, and the sensing parameters are convenient for photoacoustic sensing. It can be concluded that a single speckle contains all the relevant information for remote photoacoustic signal detection. Single speckle sensing is therefore an easy, robust, contact-free photoacoustic detection technique and holds the potential for economical, ultra-fast photoacoustic sensing. The new detection technique might thus help to broaden the field of photoacoustic imaging applications in the future.
CDC14A codes for a conserved proline‐directed phosphatase, and mutations in the gene are associated with autosomal‐recessive severe to profound deafness, due to defective kinocilia. A role of CDC14A ...in cilia formation has also been described in other organisms. However, how human CDC14A impacts on cilia formation remains unclear. Here, we show that human RPE1 hCDC14APD cells, encoding a phosphatase dead version of hCDC14A, have longer cilia than wild‐type cells, while hCDC14A overexpression reduces cilia formation. Phospho‐proteome analysis of ciliated RPE1 cells identified actin‐associated and microtubule binding proteins regulating cilia length as hCDC14A substrates, including the actin‐binding protein drebrin. Indeed, we find that hCDC14A counteracts the CDK5‐dependent phosphorylation of drebrin at S142 during ciliogenesis. Further, we show that drebrin and hCDC14A regulate the recruitment of the actin organizer Arp2 to centrosomes. In addition, during ciliogenesis hCDC14A also regulates endocytosis and targeting of myosin Va vesicles to the basal body in a drebrin‐independent manner, indicating that it impacts primary cilia formation in a multilayered manner.
Synopsis
Human CDC14A negatively regulates primary cilia length in a multilayered manner by dephosphorylating actin‐associated proteins, including DBN1. Serine 142 of DBN1 is dephosphorylated by hCDC14A, thereby counteracting the cilia length promoting activity of CDK5.
hCDC14A localizes to the basal body and the actin cytoskeleton during ciliogenesis.
hCDC14A regulates the phosphorylation of DBN1, thereby contributing to cilia length control.
hCDC14A and DBN1 regulate the actin nucleator Arp2 at basal bodies.
Endocytosis and transport of myosin Va vesicles to the basal body is a DBN1‐independent function of hCDC14A during ciliogenesis.
Human CDC14A negatively regulates primary cilia length in a multilayered manner by dephosphorylating actin‐associated proteins, including DBN1. Serine 142 of DBN1 is dephosphorylated by hCDC14A, thereby counteracting the cilia length promoting activity of CDK5.
The specific manufacturing processes of fiber‐reinforced plastics (FRP) enable a seamless integration of sensors and actuators, allowing realization of tasks that are additional to the main load ...bearing functionality, for example, obstacle distance sensing. Through the integration of several distributed piezoelectric actuators into a FRP component and their time‐shifted actuation, a directional plate wave can be generated. The interaction of the plate wave with the surrounding medium induces a sound wave, which − reflected from an obstacle − returns toward the component and forms a plate wave, that is, detected by another integrated transducer array. Since the time between the generation of the initial wave and the reflected wave appearance is a linear function of the distance to the obstacle, an appropriate evaluation enables the realization of the obstacle distance sensing functionality. Presented experimental investigations are conducted to confirm the feasibility of the above described operational principle. It is shown that a directional generation of plate waves and their radiation in surrounding medium can be achieved using a suitable actuator‐sensor arrangement. The operating principle is successfully demonstrated for exemplary textile‐reinforced composite plate with integrated piezoceramic actuator‐sensor transducer arrays.
Through the integration of distributed piezoelectric transducers and their appropriate actuation, a directional plate wave is generated. The interaction of the plate wave with the surrounding medium induces a sound wave which reflected from an obstacle returns and forms a plate wave detected by the transducer array. An analysis of the wave flight time allows distance detection to an obstacle.
Aiming at the generation of a high strontium‐containing degradable bone substitute, the exchange of calcium with strontium in gelatin‐modified brushite was investigated. The ion substitution showed ...two mineral groups, the high‐calcium containing minerals with a maximum measured molar Ca/Sr ratio of 80%/20% (mass ratio 63%/37%) and the high‐strontium containing ones with a maximum measured molar Ca/Sr ratio of 21%/79% (mass ratio 10%/90%). In contrast to the high‐strontium mineral phases, a high mass loss was observed for the calcium‐based minerals during incubation in cell culture medium (alpha‐MEM), but also an increase in strength owing to dissolution and re‐precipitation. This resulted for the former in a decrease of cation concentration (Ca + Sr) in the medium, while the pH value decreased and the phosphate ion concentration rose significantly. The latter group of materials, the high‐strontium containing ones, showed only a moderate change in mass and a decrease in strength, but the Ca + Sr concentration remained permanently above the initial calcium concentration in the medium. This might be advantageous for a future planned application by supporting bone regeneration on the cellular level.
PDF
