Rotating‐Electric‐Field‐Induced Carbon‐Nanotube‐Based Nanomotor in Water: A Molecular Dynamics Study

Using molecular dynamics simulations, it is shown that a carbon nanotube (CNT) suspended in water and subjected to a rotating electric field of proper magnitude and angular speed can be rotated with the aid of water dipole orientations. Based on this principle, a rotational nanomotor structure is designed and the system is simulated in water. Use of the fast responsiveness of electric‐field‐induced CNT orientation in water is employed and its operation at ultrahigh‐speed (over 10¹¹ r.p.m.) is shown. To explain the basic mechanism, the behavior of the rotational actuation, originated from the water dipole orientation, is also analyzed . The proposed nanomotor is capable of rotating an attached load (such as CNT) at a precise angle as well as nanogear‐based complex structures. The findings suggest a potential way of using the electric‐field‐induced CNT rotation in polarizable fluids as a novel tool to operate nanodevices and systems.     

Calcium‐Ion Batteries: Current State‐of‐the‐Art and Future Perspectives

Recent developments in rechargeable battery technology have seen a shift from the well‐established Li‐ion technology to new chemistries to achieve the high energy density required for extended range electric vehicles and other portable applications, as well as low‐cost alternatives for stationary storage. These chemistries include Li–air, Li–S, and multivalent ion technologies including Mg²⁺, Zn²⁺, Ca²⁺, and Al³⁺. While Mg²⁺ battery systems have been increasingly investigated in the last few years, Ca²⁺ technology has only recently been recognized as a viable option. In this first comprehensive review of Ca²⁺ ion technology, the use of Ca metal anodes, alternative alloy anodes, electrolytes suitable for this system, and cathode material development are discussed. The advantages and disadvantages of Ca²⁺ ion batteries including prospective achievable energy density, cost reduction due to high natural abundance, low ion mobility, the effect of ion size, and the need for elevated temperature operation are reviewed. The use of density functional theory modeling to predict the properties of Ca‐ion battery materials is discussed and the extent to which this approach is successful in directing research into areas of promise is evaluated. To conclude, a summary of recent achievements is presented and areas for future research efforts evaluated.     

Clay‐Inspired MXene‐Based Electrochemical Devices and Photo‐Electrocatalyst: State‐of‐the‐Art Progresses and Challenges

MXene, an important and increasingly popular category of postgraphene 2D nanomaterials, has been rigorously investigated since early 2011 because of advantages including flexible tunability in element composition, hydrophobicity, metallic nature, unique in‐plane anisotropic structure, high charge‐carrier mobility, tunable band gap, and favorable optical and mechanical properties. To fully exploit these potentials and further expand beyond the existing boundaries, novel functional nanostructures spanning monolayer, multilayer, nanoparticles, and composites have been developed by means of intercalation, delamination, functionalization, hybridization, among others. Undeniably, the cutting‐edge developments and applications of clay‐inspired 2D MXene platform as electrochemical electrode or photo‐electrocatalyst have conferred superior performance and have made significant impact in the field of energy and advanced catalysis. This review provides an overview of the fundamental properties and synthesis routes of pure MXene, functionalized MXene and their hybrids, highlights the state‐of‐the‐art progresses of MXene‐based applications with respect to supercapacitors, batteries, electrocatalysis and photocatalysis, and presents the challenges and prospects in the burgeoning field.     

Cryo‐EM‐On‐a‐Chip: Custom‐Designed Substrates for the 3D Analysis of Macromolecules

The fight against human disease requires a multidisciplinary scientific approach. Applying tools from seemingly unrelated areas, such as materials science and molecular biology, researchers can overcome long‐standing challenges to improve knowledge of molecular pathologies. Here, custom‐designed substrates composed of silicon nitride (SiN) are used to study the 3D attributes of tumor suppressor proteins that function in DNA repair events. New on‐chip preparation strategies enable the isolation of native protein complexes from human cancer cells. Combined techniques of cryo‐electron microscopy (EM) and molecular modeling reveal a new modified form of the p53 tumor suppressor present in aggressive glioblastoma multiforme cancer cells. Taken together, the findings provide a radical new design for cryo‐EM substrates to evaluate the structures of disease‐related macromolecules.     

Three‐dimensional brittle fracture: configurational‐force‐driven crack propagation

This paper presents a computational framework for quasi‐static brittle fracture in three‐dimensional solids. The paper sets out the theoretical basis for determining the initiation and direction of propagating cracks based on the concept of configurational mechanics, consistent with Griffith's theory. Resolution of the propagating crack by the FEM is achieved by restricting cracks to element faces and adapting the mesh to align it with the predicted crack direction. A local mesh improvement procedure is developed to maximise mesh quality in order to improve both accuracy and solution robustness and to remove the influence of the initial mesh on the direction of propagating cracks. An arc‐length control technique is derived to enable the dissipative load path to be traced. A hierarchical hp‐refinement strategy is implemented in order to improve both the approximation of displacements and crack geometry. The performance of this modelling approach is demonstrated on two numerical examples that qualitatively illustrate its ability to predict complex crack paths. All problems are three‐dimensional, including a torsion problem that results in the accurate prediction of a doubly‐curved crack. Copyright © 2013 John Wiley & Sons, Ltd.     

Chemical‐to‐Electricity Carbon: Water Device

The ability to release, as electrical energy, potential energy stored at the water:carbon interface is attractive, since water is abundant and available. However, many previous reports of such energy converters rely on either flowing water or specially designed ionic aqueous solutions. These requirements restrict practical application, particularly in environments with quiescent water. Here, a carbon‐based chemical‐to‐electricity device that transfers the chemical energy to electrical form when coming into contact with quiescent deionized water is reported. The device is built using carbon nanotube yarns, oxygen content of which is modulated using oxygen plasma‐treatment. When immersed in water, the device discharges electricity with a power density that exceeds 700 mW m^?2, one order of magnitude higher than the best previously published result. X‐ray absorption and density functional theory studies support a mechanism of operation that relies on the polarization of sp² hybridized carbon atoms. The devices are incorporated into a flexible fabric for powering personal electronic devices.     

Metall‐Kunststoff‐Verbunde: Modellversuche zur Optimierung

Metal plastic hybrids will become more important as components for lightweight constructions. It is reported about optimisation of making three layer hybrids consisted of a steel plate, an adhesion layer based of uretdione powder coating material and a flexible component polyurethane in model experiments. Hybrid formation is performed in a compression moulding process. The adhesion layer and the polyurethane are modified to increase the hybrid bond strength. Peel test are conducted to quantitatively characterize the bond strength and an apparent energy release rate is calculated based on the peel force. For hybrids with widths of 2 mm polyurethane stripes it is possible to increase the apparent energy release rate for about 30 % to 16 N/mm in comparison with a hybrid with unmodified components. These hybrids have the same high bond strength level as the strongest hybrids reported in literature. Concluding the optimisation results are discussed related to their relevancy for the interpretation of the adhesion mechanisms in the interface between adhesion layer and polyurethane.     

Organ‐on‐a‐Chip Systems: Microengineering to Biomimic Living Systems

“Organ‐on‐a‐chip” systems integrate microengineering, microfluidic technologies, and biomimetic principles to create key aspects of living organs faithfully, including critical microarchitecture, spatiotemporal cell–cell interactions, and extracellular microenvironments. This creative platform and its multiorgan integration recapitulating organ‐level structures and functions can bring unprecedented benefits to a diversity of applications, such as developing human in vitro models for healthy or diseased organs, enabling the investigation of fundamental mechanisms in disease etiology and organogenesis, benefiting drug development in toxicity screening and target discovery, and potentially serving as replacements for animal testing. Recent advances in novel designs and examples for developing organ‐on‐a‐chip platforms are reviewed. The potential for using this emerging technology in understanding human physiology including mechanical, chemical, and electrical signals with precise spatiotemporal controls are discussed. The current challenges and future directions that need to be pursued for these proof‐of‐concept studies are also be highlighted.