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Copper current collectors (Cu CCs) impact the production technology and performance of many electrochemical devices by their unique properties and reliable operation. The efficiency of the related processes and the operation of the electrochemical devices could be significantly improved by optimization of the Cu CCs. Metallic Cu plays an important role in electrochemical energy storage and electrocatalysis, primarily as a conducting substrate on which the chemical processes take place. Li nucleation and growth can be influenced by the current collector by modulating the local current density and Li ion transport. For example, the commonly used planar Cu CC does not perform satisfactorily; therefore, a high number of different modifications of Cu CCs have been proposed and reported in the literature for minimizing the local current density, hindering Li dendrite formation, and improving the Coulombic efficiency. Here, we provide an updated critical overview of the basic strategies of 3D Cu CC structuring, methodologies for analyzing these structures, and approaches for effective control over their most relevant properties. These methods are described in the context of their practical usefulness and applicability in an effort to aid in their easy implementation by research groups and private companies with established traditions in electrochemistry and plating technology. Furthermore, the current overview could be helpful for specialists with experience in associated fields of knowledge such as materials engineering and surface finishing, where electrochemical methods are frequently applied. Motivated by the importance of the final application of Cu CCs in energy storage devices, this review additionally discusses the relationship between CC properties and the functional parameters of the already-implemented electrodes.

Angiography is a very informative method for physicians such as cardiologists, neurologists and neuroscientists. The current modalities experience some shortages, e.g., ultrasound is very operator dependent. The computerized tomography (CT) and magnetic resonance (MR) angiography are very expensive and near infrared spectroscopy cannot capture the deep arteries. Microwave technology has the potential to address some of these issues while compromising between operator dependency, cost, speed, penetration depth and resolution. This paper studies the feasibility of microwave signals for monitoring of arteries. To this aim, a homogenous phantom mimicking body tissue is built. Four elastic tubes simulate arteries and a mechanical system creates pulsations in these arteries. A multiple input multiple output (MIMO) array of ultra-wideband (UWB) transmitters and receivers illuminates the phantom and captures the reflected signals over the desired observation time period. Since we are only interested in the imaging of dynamic parts, i.e., arteries, the static clutters can be suppressed easily by background subtraction method. To obtain a fast image of arteries, which are pulsating with the heartbeat rate, we calculate the Fourier transform of each channel of the MIMO system over the observation time and apply delay and sum (DAS) beamforming method on the heartbeat rate aligned spectral component. The results show that the lateral and longitudinal images and motion mode (M-mode) time series of different points of phantom have the potential to be used for diagnosis.

The use of bio-based and biodegradable matrix materials in fiber-reinforced polymers (FRPs) is an approach to reduce the consumption of fossil resources and the amount of polymer waste. This study aims to assess the influence of the process parameters on the resulting mechanical properties of extruded bio-based and biodegradable continuous fiber-reinforced thermoplastics (CFRTPs) in the form of sheets. Therefore, the impregnation temperature during the production of PLA/flax fiber composites is varied between 220 ˚C and 280 ˚C, and the consolidation pressure, between 50 bar and 90 bar. A design of experiments approach is used. Fiber contents of 28.8% to 34.8% and void contents of 6.8% to 15.5% are determined for the composites by optical measurements. To assess the mechanical properties, tensile tests are performed. Using the evaluation software Minitab, a strong negative influence of the consolidation pressure on the tensile modulus and the tensile strength is observed. Increasing the pressure from 50 bar to 90 bar results in a reduction in the tensile modulus of 50.7% and a reduction in the tensile strength of 54.8%, respectively. It is assumed that this is due to fibers being damaged by the external force exerted onto the materials during the consolidation process in the calender. The influence of the impregnation temperature on the mechanical properties cannot be verified.

In metal-air batteries, the integrated solid-state cathode is considered a promising design because it can solve the problem of high interfacial resistance of conventional solid-state cathodes. However, solid discharge products cannot be efficiently decomposed in an integrated solid-state cathode, resulting in batteries that are unable to operate for long periods of time. Herein, an integrated solid-state cathode (Gel-Tempo cathode) of sodium-air batteries (SABs) capable of promoting efficient decomposition of discharge product Na2O2 is designed. The Gel-Tempo cathode is synthesized by cationic-π interaction of redox mediator 2,2,6,6-tetramethyl-1-piperidinyloxy (Tempo) and ionic liquid with carbon nanotubes. The Gel-Tempo cathode serves multiple functions as a redox mediator, flame retardancy, and high stability to air. In quasi-solid-state SABs, the Gel-Tempo cathode reduces overpotential to 1.15 V and improves coulomb efficiency to 84.5% (at a limited discharge capacity of 3000 mAh g−1) compared to gel cathodes. Experiments and density functional theory calculations indicate that Tempo significantly reduces the Gibbs free energy in the decomposition reaction of Na2O2, and high Tempo content is more conducive to enhancing the decomposition kinetics of Na2O2 and hence resulting in an ultra-long cycle life (1746 h). This work is crucial to promote practical applications of SABs, providing guidelines for functionalization design of integrated solid-state cathodes for metal-air batteries.

Cholesterin hat es bis in den Alltagssprachgebrauch gebracht. Allein deshalb ist es für Praktika im Chemiestudium ein interessanter Vertreter der Steroide. Zudem ist es einfach zu gewinnen.