Applied physics reviews impact factor 2019

Applied Physics Reviews (APR) is a review journal featuring reviews of important and current topics of experimental or theoretical research in applied physics and applications of physics to other branches of science and engineering. These review articles may vary in scope and length but include: Regular Reviews: Comprehensive reviews covering established areas in-depth Focused Reviews: Concise reviews covering new and emerging areas of scienceSuppressing the interlayer-gliding of layered P3-type K 0.5 Mn 0.7 Co 0.2 Fe 0.1 O 2 cathode materials on electrochemical potassium-ion storageIn recent years, potassium-ion batteries (KIBs) have emerged as a promising alternative candidate to replace lithium-ion batteries for large-scale energy storage devices owing to the natural abundance of potassium and similar mechanism as lithium-ion batteries. In particular, transition metal oxide cathode materials have attracted growing attention due to their high theoretical capacities and low cost compared with other cathode materials. Nevertheless, due to the larger ionic radius of K-ions, transition metal oxide cathode materials suffer from irreversible structural evolution and interlayer-gliding of transition metal layers in potassiation/depotassiation, which results in sluggish kinetics and structural instability. This limited capacity and unsatisfactory cycling properties inhibit the practical application of potassium-ion batteries. It still remains a challenge to develop the suitable cathode materials for potassium-ion batteries. In this work, the interlayer-gliding and irreversible P3O3 structure transition were suppressed via the replacement of cobalt and iron, and the doping mechanism was investigated by in situ x-ray diffraction. The incorporation of Co ions and Fe ions enlarges the d-space between the transition metal layers, reduces the resistance of K migration, and provides the buffer spaces to suppress the interlayer-gliding and P3O3 phase transformation in electrochemical potassium-ion storage, leading to an enhanced rate capability (58 mA h g¹ at 1 A g¹) and superior cycling stability (71% after 300 cycles at 200 mA g¹). This strategy provides a better understanding for the effect of CoFe substitution in suppressing interlayer-gliding and improving electrochemical properties for the development of a novel cathode material for potassium-ion batteries.Publishers Note: "Recent progress in III-V based ferromagnetic semiconductors: Band structure, Fermi level, and tunneling transport" [Appl. Phys. Rev. 1, 011102 (2014)]Comment on Diffusion of n-type dopants in germanium [Appl. Phys. Rev. 1, 011301 (2014)]The authors of the above paper call into question recent evidence on the properties of self-interstitials, I, in Ge [Cowern et al., Phys. Rev. Lett. 110, 155501 (2013)]. We show that this judgment stems from invalid model assumptions during analysis of data on B marker-layer diffusion during proton irradiation, and that a corrected analysis fully supports the reported evidence. As previously stated, I-mediated self-diffusion in Ge exhibits two distinct regimes of temperature, T: high-T, dominated by amorphous-like mono-interstitial clustersi-morphswith self-diffusion entropy 30 k, and low-T, where transport is dominated by simple self-interstitials. In a transitional range centered on 475 °C both mechanisms contribute. The experimental I migration energy of 1.84 ± 0.26 eV reported by the Münster group based on measurements of self-diffusion during irradiation at 550 °C < T < 680 °C further establishes our proposed i-morph mechanism.Publisher's Note: Visually aided tactile enhancement system based on ultrathin highly sensitive crack-based strain sensors [Appl. Phys. Rev. 7 , 011404 (2020)]Erratum: Aluminum textile-based binder-free nanostructured battery cathodes using a layer-by-layer assembly of metal/metal oxide nanoparticles [Appl. Phys. Rev. 8 , 011405 (2021)]Publisher's Note: Exploring the significance of structural hierarchy in material systemsA review [Appl. Phys. Rev. 1, 021302 (2014)]Erratum: Review of using gallium nitride for ionizing radiation detection [Appl. Phys. Rev. 2 , 031102 (2015)]Erratum: Magnetic and charge ordering in nanosized manganites [Appl. Phys. Rev. 1 , 031302 (2014)]Retraction: Harvest of ocean energy by triboelectric generator technology [Appl. Phys. Rev. 5 , 031303 (2018)]Erratum: Conformational state switching and pathways of chromosome dynamics in cell cycle [Appl. Phys. Rev. 7 , 031403 (2020)]Publisher's Note: High and reversible spin polarization in a collinear antiferromagnet [Appl. Phys. Rev. 7 , 031405 (2020)]Publisher's Note: Beyond solid-state lighting: Miniaturization, hybrid integration, and applications of GaN nano- and micro-LEDs [Appl. Phys. Rev. 6 , 041315 (2019)]Publisher's Note: Biomechanical factors in three-dimensional tissue bioprinting [Appl. Phys Rev. 7 , 041319 (2020)]Fundamental insights to topological quantum materials: A real-space view of 13 cases by supersymmetry of valence bonds approachWe present a real-space view of one-dimensional (1D) to three-dimensional (3D) topological materials with 13 representative samples selected from each class, including 1D trans-polyacetylene, two-dimensional (2D) graphene, and 3D topological insulators, Dirac semimetals, Weyl semimetals, and nodal-line semimetals. This review is not intended to present a complete up-to-date list of publications on topological materials, nor to provide a progress report on the theoretical concepts and experimental advances, but rather to focus on an analysis based on the valence-bond model to help the readers gain a more balanced view of the real-space bonding electron characteristics at the molecular level versus the reciprocal-space band picture of topological materials. Starting from a brief review of low-dimensional magnetism with "toy models" for a 1D Heisenberg antiferromagnetic chain, 1D trans-polyacetylene and 2D graphene are found to have similar conjugated π-bond systems, and the Dirac cone is correlated with their unconventional 1D and 2D conduction mechanisms. Strain-driven and symmetry-protected topological insulators are introduced from the perspective of material preparation and valence-electron sharing in the valence-bond model analysis. The valence-bond models for the newly developed Dirac semimetals, Weyl semimetals, and nodal line semimetals are examined with more emphasis on the bond length and electron sharing, which is found to be consistent with the band picture. The real-space valence-bond analysis of topological materials with a conjugated π-bond system suggests that these topological materials must be classified with concepts borrowed from group theory and topology, so that a supersymmetry may absorb the fluctuating broken symmetry. Restoration of a thermodynamic system with higher entropy (i.e., the lower Gibbs free energy) is more appropriate to describe such topological materials instead of the traditional material classification with the lowest enthalpy for the presumed rigid crystal structure.Tracing the 5000-year recorded history of inorganic thin films from 3000 BC to the early 1900s ADGold is very likely the first metal discovered by man, more than 11 000 years ago. However, unlike copper (9000 BC), bronze (3500 BC), and wrought iron (25003000 BC), gold is too soft for fabrication of tools and weapons. Instead, it was used for decoration, religious artifacts, and commerce. The earliest documented inorganic thin films were gold layers, some less than 3000 Å thick, produced chemi-mechanically by Egyptians approximately 5000 years ago. Examples, gilded on statues and artifacts (requiring interfacial adhesion layers), were found in early stone pyramids dating to 2650 BC in Saqqara, Egypt. Spectacular samples of embossed Au sheets date to at least 2600 BC. The Moche Indians of northern Peru developed electroless gold plating (an auto-catalytic reaction) in 100 BC and applied it to intricate Cu masks. The earliest published electroplating experiments were 1800 AD, immediately following the invention of the dc electrochemical battery by Volta. Chemical vapor deposition (CVD) of metal films was reported in 1649, atmospheric arc deposition of oxides (Priestley) in the mid-1760s, and atmospheric plasmas (Siemens) in 1857. Sols were produced in the mid-1850s (Faraday) and sol-gel films synthesized in 1885. Vapor phase film growth including sputter deposition (Grove, 1852), vacuum arc deposition (deflagration, Faraday, 1857), plasma-enhanced CVD (Barthelot, 1869) and evaporation (Stefan, Hertz, and Knudsen, 18731915) all had to wait for the invention of vacuum pumps whose history ranges from 1650 for mechanical pumps, through 1865 for mercury pumps that produce ballistic pressures in small systems. The development of crystallography, beginning with Plato in 360 BC, Kepler in 1611, and leading to Miller indices (1839) for describing orientation and epitaxial relationships in modern thin film technology, was already well advanced by the 1780s (Haüy). The starting point for the development of heterogeneous thin film nucleation theory was provided by Young in 1805. While an historical timeline tracing the progress of thin film technology is interesting of itself, the stories behind these developments are even more fascinating and provide insight into the evolution of scientific reasoning.Preface to a Special Topic: 2D Materials and ApplicationsCalcium fluoride as high-k dielectric for 2D electronicsCalcium fluoride is a dielectric material with a wide bandgap (12.1 eV) and a relatively high dielectric constant (6.8) that forms a van der Waals interface with two-dimensional (2D) materials, meaning that it contains a very low amount of defects. Thin calcium fluoride films can be synthesized using multiple techniques that are scalable to the wafer level, including molecular beam epitaxy, atomic layer deposition, and chemical vapor deposition. However, the consolidation of calcium fluoride as dielectric for 2D electronics requires overcoming some fundamental challenges related to material quality and integration, as well as carrying out advanced characterization and computational studies to evaluate its real potential. Here, we review the status of calcium fluoride dielectric films in terms of material synthesis, fundamental electrical properties, and future applications; we also discuss the most important challenges of calcium fluoride integration in 2D materialsbased, solid-state nano/micro-electronic devices, and propose several potential routes to overcome them. Our manuscript may serve as a useful guide for other scientists working on 2D electronics in general, and provides a clear pathway for calcium fluoride research in the future.Synthesis, engineering, and theory of 2D van der Waals magnetsThe recent discovery of magnetism in monolayers of two-dimensional van der Waals materials has opened new venues in materials science and condensed matter physics. Until recently, two-dimensional magnetism remained elusive: Spontaneous magnetic order is a routine instance in three-dimensional materials but it is not a priori guaranteed in the two-dimensional world. Since the 2016 discovery of antiferromagnetism in monolayer FePS3 by two groups and the subsequent demonstration of ferromagnetic order in monolayer CrI3 and bilayer Cr2Ge2Te6, the field changed dramatically. Within several years of scientific discoveries focused on 2D magnets, novel opportunities have opened up in the field of spintronics, namely spin pumping devices, spin transfer torque, and tunneling. In this review, we describe the state of the art of the nascent field of magnetic two-dimensional materials focusing on synthesis, engineering, and theory aspects. We also discuss challenges and some of the many different promising directions for future work, highlighting unique applications that may extend even to other realms, including sensing and data storage.Recent progress on 2D magnets: Fundamental mechanism, structural design and modificationThe two-dimensional (2D) magnet, a long-standing missing member in the family of 2D functional materials, is promising for next-generation information technology. The recent experimental discovery of 2D magnetic ordering in CrI3, Cr2Ge2Te6, VSe2, and Fe3GeTe2 has stimulated intense research activities to expand the scope of 2D magnets. This review covers the essential progress on 2D magnets, with an emphasis on the current understanding of the magnetic exchange interaction, the databases of 2D magnets, and the modification strategies for modulation of magnetism. We will address a large number of 2D intrinsic magnetic materials, including binary transition metal halogenides; chalogenides; carbides; nitrides; oxides; borides; silicides; MXene; ternary transition metal compounds CrXTe3, MPX3, Fe-Ge-Te, MBi2Te4, and MXY (M = transition metal; X = O, S, Se, Te, N; Y = Cl, Br, I); f-state magnets; p-state magnets; and organic magnets. Their electronic structure, magnetic moment, Curie temperature, and magnetic anisotropy energy will be presented. According to the specific 2D magnets, the underlying direct, superexchange, double exchange, super-superexchange, extended superexchange, and multi-intermediate double exchange interactions will be described. In addition, we will also highlight the effective strategies to manipulate the interatomic exchange mechanism to improve the Curie temperature of 2D magnets, such as chemical functionalization, isoelectronic substitution, alloying, strain engineering, defect engineering, applying electronic/magnetic field, interlayer coupling, carrier doping, optical controlling, and intercalation. We hope this review will contribute to understanding the magnetic exchange interaction of existing 2D magnets, developing unprecedented 2D magnets with desired properties, and offering new perspectives in this rapidly expanding field.2D coordination polymers: Design guidelines and materials perspectiveThe advent of two-dimensional (2D) organic/inorganic layered and monolayer materials has ushered in an explosion of research to understand the synthesis, underlying physics, and exciting material properties of these materials. The field to date has produced preliminary design rules related to feasible synthesis routes that can be used to design 2D materials with a range of organic ligands and metal linkers. This review seeks to extend these design rules to predict which ligands and metals can be combined, and in what fashion, to control the thermal, mechanical, magnetic, and optoelectronic properties. Furthermore, we review the various synthetic techniques and how these can be modified to enable scalable manufacturing of 2D polymers and materials, and how this highlights the need for defect engineering and advanced characterization capabilities within the field. We conclude by discussing how together these design rules, manufacturing considerations, and characterization tools coalesce to enable new materials, applications, and fundamental insights. Particular emphasis is given to magnetism, electrical properties, and optics. Overall, this review serves as a roadmap and framework for identifying new and exciting material targets, strategies for engineering desirable properties, and conduits to streamline the manufacturing and processing of these exciting materials.Recent progress in ultrafast lasers based on 2D materials as a saturable absorberTwo-dimensional (2D) materials are crystals with one to a few layers of atoms and are being used in many fields such as optical modulator, photodetector, optical switch, and ultrafast lasers. Their exceptional optoelectronic and nonlinear optical properties make them as a suitable saturable absorber for laser cavities. This review focuses on the recent progress in ultrafast laser use 2D materials as a saturable absorber. 2D materials traditionally include graphene, topological insulators, transition metal dichalcogenides, as well as new materials such as black phosphorus, bismuthene, antimonene, and MXene. Material characteristics, fabrication techniques, and nonlinear properties are also introduced. Finally, future perspectives of ultrafast lasers based on 2D materials are also addressed.Investigating phase transitions from local crystallographic analysis based on statistical learning of atomic environments in 2D MoS 2 -ReS 2The mechanisms of phase transitions have been previously explored at various theoretical and experimental levels. For a wide variety of compounds, the majority of studies are limited by observations at fixed temperature and composition, in which case, relevant information can be determined only from the behaviors at topological and structural defects. All analyses to date utilize macroscopic descriptors derived from structural information such as polarization or octahedral tilts extracted from the atomic positions, ignoring the multiple degrees of freedom observable from atomically resolved images. In this article, we provide a solution, by exploring the mechanisms of a phase transition between the trigonal prismatic and distorted octahedral phases of layered chalcogenides in the 2D MoS2ReS2 system from the observations of local degrees of freedom, namely atomic positions by scanning transmission electron microscopy. We employ local crystallographic analysis based on statistical learning of atomic environments to build a picture of the transition from the atomic level up and determine local and global variables controlling the local symmetry breaking. We highlight how the dependence of the average symmetry-breaking distortion amplitude on global and local concentration can be used to separate local chemical as well as global electronic effects on the transition. This approach allows for the exploring of atomic mechanisms beyond the traditional macroscopic descriptions, utilizing the imaging of compositional fluctuations in solids to explore phase transitions over a range of observed local stoichiometries and atomic configurations.2D transition metal dichalcogenides, carbides, nitrides, and their applications in supercapacitors and electrocatalytic hydrogen evolution reactionThe development of renewable energy conversion and storage devices, aiming at high efficiency, stable operation, environmental friendliness, and low-cost goals, provides a promising approach to resolve the global energy crisis. Recently, two-dimensional (2D) layered materials have drawn enormous attention due to their unique layered structure and intriguing electrical characteristics, which brings the unprecedented board applications in the fields ranging from electronic, optical, optoelectronic, thermal, magnetic, quantum devices to energy storage and catalysis. Graphene-based 2D layered materials show promising applications in energy storage and conversion owing to their high specific surface area, which have been used for supercapacitor electrode materials based on the electrical double-layer capacitance model. However, graphene has a limited value of theoretical electrical double-layer capacitance when the whole surface area is fully utilized. Among several classes of 2D layered materials beyond graphene, transition metal dichalcogenides, transition metal carbides, and nitrides may exhibit excellent electrochemical properties due to the distinctive features of these 2D materials, such as large specific surface area, good hydrophilic nature, highly exposed active edge sites, and ease of intercalation and modification. Therefore, careful design and construction of these 2D compounds make them become potential candidates used for electrochemical supercapacitors and electrocatalytic hydrogen evolution. This review emphasizes the recent important advances of the 2D layered materials composed of transition metal dichalcogenides, transition metal carbides, and nitrides for supercapacitors and electrocatalysts. Furthermore, we discuss the challenges and perspectives in this energy field in terms of the classes of two-dimensional layered materials.Quantum properties and applications of 2D Janus crystals and their superlatticesTwo-dimensional (2D) Janus materials are a new class of materials with unique physical, chemical, and quantum properties. The name Janus originates from the ancient Roman god which has two faces, one looking to the future while the other facing the past. Janus has been used to describe special types of materials which have two faces at the nanoscale. This unique atomic arrangement has been shown to present rather exotic properties with applications in biology, chemistry, energy conversion, and quantum sciences. This review article aims to offer a comprehensive review of the emergent quantum properties of Janus materials. The review starts by introducing 0D Janus nanoparticles and 1D Janus nanotubes, and highlights their difference from classical ones. The design principles, synthesis, and the properties of graphene-based and chalcogenide-based Janus layers are then discussed. A particular emphasis is given to colossal built-in potential in 2D Janus layers and resulting quantum phenomena such as Rashba splitting, skyrmionics, excitonics, and 2D magnetic ordering. More recent theoretical predictions are discussed in 2D Janus superlattices when Janus layers are stacked onto each other. Finally, we discuss the tunable quantum properties and newly predicted 2D Janus layers waiting to be experimentally realized. The review serves as a complete summary of the 2D Janus library and predicted quantum properties in 2D Janus layers and their superlattices.Near-room temperature ferromagnetic behavior of single-atom-thick 2D iron in nanolaminated ternary MAX phasesMn+1AXn (MAX) phases' nanolaminated ternary carbides or nitrides possess a unique crystal structure in which single-atom-thick A sublayers are interleaved by alternative stacking of a Mn+1Xn sublayer; these materials have been investigated as promising high-safety structural materials for industrial applications because of their laminated structure and metal and ceramic properties. However, limited of A-site elements in the definition of Mn+1AXn phases, it is a huge challenge for designing nanolaminated ferromagnetic materials with single-atom-thick two-dimensional iron layers occupying the A layers in the Mn+1AXn phases. Here, we report three new ternary magnetic Mn+1AXn phases (Ta2FeC, Ti2FeN, and Nb2FeC) with A sublayers of single-atom-thick two-dimensional iron through an isomorphous replacement reaction of Mn+1AXn precursors (Ta2AlC, Ti2AlN, and Nb2AlC) with a Lewis acid salts (FeCl2). All these Mn+1AXn phases exhibit ferromagnetic behavior. The Curie temperatures of the Ta2FeC and Nb2FeC Mn+1AXn phases are 281 and 291 K, respectively, i.e., close to room temperature. The saturation magnetization of these ternary magnetic MAX phases is almost two orders of magnitude higher than V2(Sn,Fe)C, whose A-site is partially substituted by Fe. Theoretical calculations on magnetic orderings of spin moments of Fe atoms in these nanolaminated magnetic Mn+1AXn phases reveal that the magnetism can be mainly ascribed to an intralayer exchange interaction of the two-dimensional Fe atomic layers. Owing to the richness in composition of Mn+1AXn phases, our work provides a large imaginary space for constructing functional single-atom-thick two-dimensional layers in materials using these nanolaminated templates.Synthesis and emerging properties of 2D layered IIIVI metal chalcogenidesAtomically thin layered IIIVI metal chalcogenides are an emerging class of 2D materials that have attracted increasing attention in recent years due to their remarkable physical properties and technological applications. Thanks to the recently developed theoretical and experimental methods, a number of exciting discoveries for these materials have revealed their new phases, a unique Mexican hat-shaped electronic band structure, and superior optical and electronic properties that distinguish them from other 2D materials such as transition metal dichalcogenides. This review summarizes the novel properties, structures, and synthesis strategies for these materials and emphasizes the most cutting-edge and seminal achievements in this rapidly growing field in order to provide input for future research works. We first present the rich crystal structure and phases that have been found in these materials, with an emphasis on the possibility of phase engineering. Then, we discuss the synthesis strategies for 2D layered IIIVI metal chalcogenides from the top-down, bottom-up, and template-based chemical conversion approaches. We focus on the highly controlled synthesis methods that provide fine-tuning of the thickness, phase, edge structure, and other morphological characteristics. Third, we discuss the properties and applications of these materials, focusing on their unique electronic structure including the Mexican hat-shaped valence band, their superior nonlinear optical properties, high-performance electronic devices, promising photoelectrochemical properties, and emerging quantum properties such as quantum emission, exciton condensation, ferromagnetism, and topological quantum phase transition. Finally, we provide our perspective on the current challenges and future directions in this field.3D bioprinting for high-throughput screening: Drug screening, disease modeling, and precision medicine applicationsHigh-throughput technologies have become essential in many fields of pharmaceutical and biological development and production. Such technologies were initially developed with compatibility with liquid handling-based cell culture techniques to produce large-scale 2D cell culture experiments for the compound analysis of candidate drug compounds. Over the past two decades, tools for creating 3D cell cultures, organoids, and other 3D in vitro models, such as cell supportive biomaterials and 3D bioprinting, have rapidly advanced. Concurrently, a significant body of evidence has accumulated which speaks to the many benefits that 3D model systems have over traditional 2D cell cultures. Specifically, 3D cellular models better mimic aspects such as diffusion kinetics, cell-cell interactions, cell-matrix interactions, inclusion of stroma, and other features native to in vivo tissue and as such have become an integral part of academic research. However, most high throughput assays were not developed to specifically support 3D systems. Here, we describe the need for improved compatibility and relevant advances toward deployment and adoption of high throughput 3D models to improve disease modeling, drug efficacy testing, and precision medicine applications.Stabilization strategies in extrusion-based 3D bioprinting for tissue engineeringThree dimensional (3D) printing is a revolutionizing technology, which endows engineers, designers, and manufacturers with the ability to rapidly translate digital sketches into physical objects. The advantages that lie in the high resolution and accuracy of this technique were not concealed from the eyes of tissue engineers that soon harnessed this power for fabrication of complex biological structures. Nevertheless, while the conventional 3D printing scheme is oriented to yield durable and sturdy structures, the delicate nature of the substances used in 3D bioprinting results in fragile and mechanically unstable constructs. This poses a significant restriction that needs to be overcome in order to successfully complete the printing of intact, accurate, and biologically relevant constructs with desirable properties. To address these complications, advanced means of stabilization which are applied during and/or following the printing procedure are constantly being developed. In this review, the rational and principles behind widely used stabilization strategies in extrusion-based bioprinting will be covered. Examples of implementation of these strategies in recently published research in the field of tissue engineering will also be presented and discussed.Modulating physical, chemical, and biological properties in 3D printing for tissue engineering applicationsOver the years, 3D printing technologies have transformed the field of tissue engineering and regenerative medicine by providing a tool that enables unprecedented flexibility, speed, control, and precision over conventional manufacturing methods. As a result, there has been a growing body of research focused on the development of complex biomimetic tissues and organs produced via 3D printing to serve in various applications ranging from models for drug development to translational research and biological studies. With the eventual goal to produce functional tissues, an important feature in 3D printing is the ability to tune and modulate the microenvironment to better mimic in vivo conditions to improve tissue maturation and performance. This paper reviews various strategies and techniques employed in 3D printing from the perspective of achieving control over physical, chemical, and biological properties to provide a conducive microenvironment for the development of physiologically relevant tissues. We will also highlight the current limitations associated with attaining each of these properties in addition to introducing challenges that need to be addressed for advancing future 3D printing approaches.Rapid 3D nanoscale coherent imaging via physics-aware deep learningPhase retrieval, the problem of recovering lost phase information from measured intensity alone, is an inverse problem that is widely faced in various imaging modalities ranging from astronomy to nanoscale imaging. The current process of phase recovery is iterative in nature. As a result, the image formation is time consuming and computationally expensive, precluding real-time imaging. Here, we use 3D nanoscale X-ray imaging as a representative example to develop a deep learning model to address this phase retrieval problem. We introduce 3D-CDI-NN, a deep convolutional neural network and differential programing framework trained to predict 3D structure and strain, solely from input 3D X-ray coherent scattering data. Our networks are designed to be physics-aware in multiple aspects; in that the physics of the X-ray scattering process is explicitly enforced in the training of the network, and the training data are drawn from atomistic simulations that are representative of the physics of the material. We further refine the neural network prediction through a physics-based optimization procedure to enable maximum accuracy at lowest computational cost. 3D-CDI-NN can invert a 3D coherent diffraction pattern to real-space structure and strain hundreds of times faster than traditional iterative phase retrieval methods. Our integrated machine learning and differential programing solution to the phase retrieval problem is broadly applicable across inverse problems in other application areas.Self-aligned myofibers in 3D bioprinted extracellular matrix-based construct accelerate skeletal muscle function restorationTo achieve rapid skeletal muscle function restoration, many attempts have been made to bioengineer functional muscle constructs by employing physical, biochemical, or biological cues. Here, we develop a self-aligned skeletal muscle construct by printing a photo-crosslinkable skeletal muscle extracellular matrix-derived bioink together with poly(vinyl alcohol) that contains human muscle progenitor cells. To induce the self-alignment of human muscle progenitor cells, in situ uniaxially aligned micro-topographical structure in the printed constructs is created by a fibrillation/leaching of poly(vinyl alcohol) after the printing process. The in vitro results demonstrate that the synergistic effect of tissue-specific biochemical signals (obtained from the skeletal muscle extracellular matrix-derived bioink) and topographical cues [obtained from the poly(vinyl alcohol) fibrillation] improves the myogenic differentiation of the printed human muscle progenitor cells with cellular alignment. Moreover, this self-aligned muscle construct shows the accelerated integration with neural networks and vascular ingrowth in vivo, resulting in rapid restoration of muscle function. We demonstrate that combined biochemical and topographic cues on the 3D bioprinted skeletal muscle constructs can effectively reconstruct the extensive muscle defect injuries.3D bioprinting: Physical and chemical processesCatalytically mediated epitaxy of 3D semiconductors on van der Waals substratesThe formation of well-controlled interfaces between materials of different structure and bonding is a key requirement when developing new devices and functionalities. Of particular importance are epitaxial or low defect density interfaces between two-dimensional materials and three-dimensional semiconductors or metals, where an interfacial structure influences electrical conductivity in field effect and optoelectronic devices, charge transfer for spintronics and catalysis, and proximity-induced superconductivity. Epitaxy and hence well-defined interfacial structure has been demonstrated for several metals on van der Waals-bonded substrates. Semiconductor epitaxy on such substrates has been harder to control, for example during chemical vapor deposition of Si and Ge on graphene. Here, we demonstrate a catalytically mediated heteroepitaxy approach to achieve epitaxial growth of three-dimensional semiconductors such as Ge and Si on van der Waals-bonded materials such as graphene and hexagonal boron nitride. Epitaxy is transferred from the substrate to semiconductor nanocrystals via solid metal nanocrystals that readily align on the substrate and catalyze the formation of aligned nuclei of the semiconductor. In situ transmission electron microscopy allows us to elucidate the reaction pathway for this process and to show that solid metal nanocrystals can catalyze semiconductor growth at a significantly lower temperature than direct chemical vapor deposition or deposition mediated by liquid catalyst droplets. We discuss Ge and Si growth as a model system to explore the details of such hetero-interfacing and its applicability to a broader range of materials.Tracing the 4000 year history of organic thin films: From monolayers on liquids to multilayers on solidsThe recorded history of organic monolayer and multilayer thin films spans approximately 4000 years. Fatty-acid-based monolayers were deposited on water by the ancients for applications ranging from fortune telling in King Hammurabi's time (1800 BC, Mesopotamia) to stilling choppy waters for sailors and divers as reported by the Roman philosopher Pliny the Elder in 78 AD, and then much later (1774) by the peripatetic American statesman and natural philosopher Benjamin Franklin, to Japanese floating-ink art (suminagashi) developed 1000 years ago. The modern science of organic monolayers began in the late-1800s/early-1900s with experiments by Lord Rayleigh and the important development by Agnes Pockels, followed two decades later by Irving Langmuir, of the tools and technology to measure the surface tension of liquids, the surface pressure of organic monolayers deposited on water, interfacial properties, molecular conformation of the organic layers, and phase transitions which occur upon compressing the monolayers. In 1935, Katherine Blodgett published a landmark paper showing that multilayers can be synthesized on solid substrates, with controlled thickness and composition, using an apparatus now known as the Langmuir-Blodgett (L-B) trough. A disadvantage of LB films for some applications is that they form weak physisorbed bonds to the substrate. In 1946, Bigelow, Pickett, and Zisman demonstrated, in another seminal paper, the growth of organic self-assembled monolayers (SAMs) via spontaneous adsorption from solution, rather than from the water/air interface, onto SiO2 and metal substrates. SAMs are close-packed two-dimensional organic crystals which exhibit strong covalent bonding to the substrate. The first multicomponent adsorbed monolayers and multilayer SAMs were produced in the early 1980s. Langmuir monolayers, L-B multilayers, and self-assembled mono- and multilayers have found an extraordinarily broad range of applications including controlled wetting, adhesion, electrochemistry, biocompatibility, molecular recognition, biosensing, cell biology, non-linear optics, molecular electronics, solar cells, read/write/erase memory, and magnetism.Bone tissue engineering via application of a collagen/hydroxyapatite 4D-printed biomimetic scaffold for spinal fusionThe fabrication of biomimetic scaffolding is a challenging issue in tissue engineering. Scaffolds must be designed with micrometer precision to enable cell proliferation and tissue growth, requiring customization based on the type of tissue being developed. Biomimetic scaffolds have attracted interest for their potential in spinal fusion applications. By providing a structured environment to promote osteogenesis, these materials offer a robust and minimally invasive means to fuse vertebrae. The present study describes the successful preparation of a biomimetic collagen/hydroxyapatite hierarchical scaffold, with each strut having several microchannels via 3D printing, leaching, and coating processes (i.e., one-way shape morphing, 4D printing). The biophysical properties of the scaffold were analyzed, as were its various cellular activities, using human adipose stem cells. This biomimetic microchannel scaffold demonstrated great potential for osteogenic activities in vitro and significantly increased new bone formation and ingrowth of blood vessels in vivo in a mouse model of posterolateral lumbar spinal fusion. These in vitro and in vivo results suggest that the microchannel collagen/hydroxyapatite scaffold could act as a potential bone graft substitute to promote high rates of successful fusion.ChemInform Abstract: Magnetic and Charge Ordering in Nanosized ManganitesPerovskite manganites exhibit a wide range of functional properties, such as colossal magneto-resistance, magnetocaloric effect, multiferroic property, and some interesting physical phenomena including spin, charge, and orbital ordering. Recent advances in science and technology associated with perovskite oxides have resulted in the feature sizes of microelectronic devices down-scaling into nanoscale dimensions. The nanoscale perovskite manganites display novel magnetic and electronic properties that are different from their bulk and film counterparts. Understanding the size effects of perovskite manganites at the nanoscale is of importance not only for the fundamental scientific research but also for developing next generation of electronic and magnetic nanodevices. In this paper, the current understanding and the fundamental issues related to the size effects on the magnetic properties and charge ordering in manganites are reviewed, which covers lattice structure, magnetic and electronic properties in both ferromagnetic and antiferromagnetic based manganites. In addition to review the literatures, this article identifies the promising avenues for the future research in this area.Analog architectures for neural network acceleration based on non-volatile memoryAnalog hardware accelerators, which perform computation within a dense memory array, have the potential to overcome the major bottlenecks faced by digital hardware for data-heavy workloads such as deep learning. Exploiting the intrinsic computational advantages of memory arrays, however, has proven to be challenging principally due to the overhead imposed by the peripheral circuitry and due to the non-ideal properties of memory devices that play the role of the synapse. We review the existing implementations of these accelerators for deep supervised learning, organizing our discussion around the different levels of the accelerator design hierarchy, with an emphasis on circuits and architecture. We explore and consolidate the various approaches that have been proposed to address the critical challenges faced by analog accelerators, for both neural network inference and training, and highlight the key design trade-offs underlying these techniques.Challenges in the design of concentrator photovoltaic (CPV) modules to achieve highest efficienciesConcentrator photovoltaics (CPV) is a special high efficiency system technology in the world of PV-technologies. The idea of CPV is to use optical light concentrators to increase the incident power on solar cells. The solar cell area is comparatively tiny, thus saving expensive semiconductor materials and allowing the use of more sophisticated and more costly multi-junction solar cells. The highest CPV module efficiency achieved is 38.9%. This CPV module uses four-junction III-V-based solar cells. Moreover, mini-modules have already achieved an efficiency of 43.4%. The interaction between optics, cells, and layout of the module and tracker determines the overall field performance. Today, some utility scale CPV plants are installed. The CPV technology allows for many technical solutions for system designs and for optimizing performance while maintaining the economics. This paper will review the achievements and discuss the challenges for the CPV module technology and its components. We discuss the different components and the most important effects regarding the module design. Furthermore, we present the module designs that have shown the highest efficiencies.Tailoring magnetic order via atomically stacking 3 d /5 d electrons to achieve high-performance spintronic devicesThe ability to tune magnetic orders, such as magnetic anisotropy and topological spin texture, is desired to achieve high-performance spintronic devices. A recent strategy has been to employ interfacial engineering techniques, such as the introduction of spin-correlated interfacial coupling, to tailor magnetic orders and achieve novel magnetic properties. We chose a unique polarnonpolar LaMnO3/SrIrO3 superlattice because Mn (3d)/Ir (5d) oxides exhibit rich magnetic behaviors and strong spinorbit coupling through the entanglement of their 3d and 5d electrons. Through magnetization and magnetotransport measurements, we found that the magnetic order is interface-dominated as the superlattice period is decreased. We were able to then effectively modify the magnetization, tilt of the ferromagnetic easy axis, and symmetry transition of the anisotropic magnetoresistance of the LaMnO3/SrIrO3 superlattice by introducing additional Mn (3d) and Ir (5d) interfaces. Further investigations using in-depth first-principles calculations and numerical simulations revealed that these magnetic behaviors could be understood by the 3d/5d electron correlation and Rashba spinorbit coupling. The results reported here demonstrate a new route to synchronously engineer magnetic properties through the atomic stacking of different electrons, which would contribute to future applications in high-capacity storage devices and advanced computing.Liquid metal actuation by electrical control of interfacial tensionBy combining metallic electrical conductivity with low viscosity, liquid metals and liquid metal alloys offer new and exciting opportunities to serve as reconfigurable components of electronic, microfluidic, and electromagnetic devices. Here, we review the physics and applications of techniques that utilize voltage to manipulate the interfacial tension of liquid metals; such techniques include electrocapillarity, continuous electrowetting, electrowetting-on-dielectric, and electrochemistry. These techniques lower the interfacial tension between liquid metals and a surrounding electrolyte by driving charged species (or in the case of electrochemistry, chemical species) to the interface. The techniques are useful for manipulating and actuating liquid metals at sub-mm length scales where interfacial forces dominate. We focus on metals and alloys that are liquid near or below room temperature (mercury, gallium, and gallium-based alloys). The review includes discussion of mercurydespite its toxicitybecause it has been utilized in numerous applications and it offers a way of introducing several phenomena without the complications associated with the oxide layer that forms on gallium and its alloys. The review focuses on the advantages, applications, opportunities, challenges, and limitations of utilizing voltage to control interfacial tension as a method to manipulate liquid metals.Electrolyte-gated transistors for synaptic electronics, neuromorphic computing, and adaptable biointerfacingFunctional emulation of biological synapses using electronic devices is regarded as the first step toward neuromorphic engineering and artificial neural networks (ANNs). Electrolyte-gated transistors (EGTs) are mixed ionicelectronic conductivity devices capable of efficient gate-channel capacitance coupling, biocompatibility, and flexible architectures. Electrolyte gating offers significant advantages for the realization of neuromorphic devices/architectures, including ultralow-voltage operation and the ability to form parallel-interconnected networks with minimal hardwired connectivity. In this review, the most recent developments in EGT-based electronics are introduced with their synaptic behaviors and detailed mechanisms, including short-/long-term plasticity, global regulation phenomena, lateral coupling between device terminals, and spatiotemporal correlated functions. Analog memory phenomena allow for the implementation of perceptron-based ANNs. Due to their mixed-conductivity phenomena, neuromorphic circuits based on EGTs allow for facile interfacing with biological environments. We also discuss the future challenges in implementing low power, high speed, and reliable neuromorphic computing for large-scale ANNs with these neuromorphic devices. The advancement of neuromorphic devices that rely on EGTs highlights the importance of this field for neuromorphic computing and for novel healthcare technologies in the form of adaptable or trainable biointerfacing.Optical trapping gets structure: Structured light for advanced optical manipulationThe pace of innovations in the field of optical trapping has ramped up in the past couple of years. The implementation of structured light, leading to groundbreaking inventions such as high-resolution microscopy or optical communication, has unveiled the unexplored potential for optical trapping. Advancing from a single Gaussian light field as trapping potential, optical tweezers have gotten more and more structure; innovative trapping landscapes have been developed, starting from multiple traps realized by holographic optical tweezers, via complex scalar light fields sculpted in amplitude and phase, up to polarization-structured and highly confined vectorial beams. In this article, we provide a timely overview on recent advances in advanced optical trapping and discuss future perspectives given by the combination of optical manipulation with the emerging field of structured light.Rapid 3D nanoscale coherent imaging via physics-aware deep learningPhase retrieval, the problem of recovering lost phase information from measured intensity alone, is an inverse problem that is widely faced in various imaging modalities ranging from astronomy to nanoscale imaging. The current process of phase recovery is iterative in nature. As a result, the image formation is time consuming and computationally expensive, precluding real-time imaging. Here, we use 3D nanoscale X-ray imaging as a representative example to develop a deep learning model to address this phase retrieval problem. We introduce 3D-CDI-NN, a deep convolutional neural network and differential programing framework trained to predict 3D structure and strain, solely from input 3D X-ray coherent scattering data. Our networks are designed to be physics-aware in multiple aspects; in that the physics of the X-ray scattering process is explicitly enforced in the training of the network, and the training data are drawn from atomistic simulations that are representative of the physics of the material. We further refine the neural network prediction through a physics-based optimization procedure to enable maximum accuracy at lowest computational cost. 3D-CDI-NN can invert a 3D coherent diffraction pattern to real-space structure and strain hundreds of times faster than traditional iterative phase retrieval methods. Our integrated machine learning and differential programing solution to the phase retrieval problem is broadly applicable across inverse problems in other application areas.3D bioprinting: Physical and chemical processesCatalytically mediated epitaxy of 3D semiconductors on van der Waals substratesThe formation of well-controlled interfaces between materials of different structure and bonding is a key requirement when developing new devices and functionalities. Of particular importance are epitaxial or low defect density interfaces between two-dimensional materials and three-dimensional semiconductors or metals, where an interfacial structure influences electrical conductivity in field effect and optoelectronic devices, charge transfer for spintronics and catalysis, and proximity-induced superconductivity. Epitaxy and hence well-defined interfacial structure has been demonstrated for several metals on van der Waals-bonded substrates. Semiconductor epitaxy on such substrates has been harder to control, for example during chemical vapor deposition of Si and Ge on graphene. Here, we demonstrate a catalytically mediated heteroepitaxy approach to achieve epitaxial growth of three-dimensional semiconductors such as Ge and Si on van der Waals-bonded materials such as graphene and hexagonal boron nitride. Epitaxy is transferred from the substrate to semiconductor nanocrystals via solid metal nanocrystals that readily align on the substrate and catalyze the formation of aligned nuclei of the semiconductor. In situ transmission electron microscopy allows us to elucidate the reaction pathway for this process and to show that solid metal nanocrystals can catalyze semiconductor growth at a significantly lower temperature than direct chemical vapor deposition or deposition mediated by liquid catalyst droplets. We discuss Ge and Si growth as a model system to explore the details of such hetero-interfacing and its applicability to a broader range of materials.3D bioprinting for high-throughput screening: Drug screening, disease modeling, and precision medicine applicationsHigh-throughput technologies have become essential in many fields of pharmaceutical and biological development and production. Such technologies were initially developed with compatibility with liquid handling-based cell culture techniques to produce large-scale 2D cell culture experiments for the compound analysis of candidate drug compounds. Over the past two decades, tools for creating 3D cell cultures, organoids, and other 3D in vitro models, such as cell supportive biomaterials and 3D bioprinting, have rapidly advanced. Concurrently, a significant body of evidence has accumulated which speaks to the many benefits that 3D model systems have over traditional 2D cell cultures. Specifically, 3D cellular models better mimic aspects such as diffusion kinetics, cell-cell interactions, cell-matrix interactions, inclusion of stroma, and other features native to in vivo tissue and as such have become an integral part of academic research. However, most high throughput assays were not developed to specifically support 3D systems. Here, we describe the need for improved compatibility and relevant advances toward deployment and adoption of high throughput 3D models to improve disease modeling, drug efficacy testing, and precision medicine applications.Tracing the 4000 year history of organic thin films: From monolayers on liquids to multilayers on solidsThe recorded history of organic monolayer and multilayer thin films spans approximately 4000 years. Fatty-acid-based monolayers were deposited on water by the ancients for applications ranging from fortune telling in King Hammurabi's time (1800 BC, Mesopotamia) to stilling choppy waters for sailors and divers as reported by the Roman philosopher Pliny the Elder in 78 AD, and then much later (1774) by the peripatetic American statesman and natural philosopher Benjamin Franklin, to Japanese floating-ink art (suminagashi) developed 1000 years ago. The modern science of organic monolayers began in the late-1800s/early-1900s with experiments by Lord Rayleigh and the important development by Agnes Pockels, followed two decades later by Irving Langmuir, of the tools and technology to measure the surface tension of liquids, the surface pressure of organic monolayers deposited on water, interfacial properties, molecular conformation of the organic layers, and phase transitions which occur upon compressing the monolayers. In 1935, Katherine Blodgett published a landmark paper showing that multilayers can be synthesized on solid substrates, with controlled thickness and composition, using an apparatus now known as the Langmuir-Blodgett (L-B) trough. A disadvantage of LB films for some applications is that they form weak physisorbed bonds to the substrate. In 1946, Bigelow, Pickett, and Zisman demonstrated, in another seminal paper, the growth of organic self-assembled monolayers (SAMs) via spontaneous adsorption from solution, rather than from the water/air interface, onto SiO2 and metal substrates. SAMs are close-packed two-dimensional organic crystals which exhibit strong covalent bonding to the substrate. The first multicomponent adsorbed monolayers and multilayer SAMs were produced in the early 1980s. Langmuir monolayers, L-B multilayers, and self-assembled mono- and multilayers have found an extraordinarily broad range of applications including controlled wetting, adhesion, electrochemistry, biocompatibility, molecular recognition, biosensing, cell biology, non-linear optics, molecular electronics, solar cells, read/write/erase memory, and magnetism.Bone tissue engineering via application of a collagen/hydroxyapatite 4D-printed biomimetic scaffold for spinal fusionThe fabrication of biomimetic scaffolding is a challenging issue in tissue engineering. Scaffolds must be designed with micrometer precision to enable cell proliferation and tissue growth, requiring customization based on the type of tissue being developed. Biomimetic scaffolds have attracted interest for their potential in spinal fusion applications. By providing a structured environment to promote osteogenesis, these materials offer a robust and minimally invasive means to fuse vertebrae. The present study describes the successful preparation of a biomimetic collagen/hydroxyapatite hierarchical scaffold, with each strut having several microchannels via 3D printing, leaching, and coating processes (i.e., one-way shape morphing, 4D printing). The biophysical properties of the scaffold were analyzed, as were its various cellular activities, using human adipose stem cells. This biomimetic microchannel scaffold demonstrated great potential for osteogenic activities in vitro and significantly increased new bone formation and ingrowth of blood vessels in vivo in a mouse model of posterolateral lumbar spinal fusion. These in vitro and in vivo results suggest that the microchannel collagen/hydroxyapatite scaffold could act as a potential bone graft substitute to promote high rates of successful fusion.ChemInform Abstract: Magnetic and Charge Ordering in Nanosized ManganitesPerovskite manganites exhibit a wide range of functional properties, such as colossal magneto-resistance, magnetocaloric effect, multiferroic property, and some interesting physical phenomena including spin, charge, and orbital ordering. Recent advances in science and technology associated with perovskite oxides have resulted in the feature sizes of microelectronic devices down-scaling into nanoscale dimensions. The nanoscale perovskite manganites display novel magnetic and electronic properties that are different from their bulk and film counterparts. Understanding the size effects of perovskite manganites at the nanoscale is of importance not only for the fundamental scientific research but also for developing next generation of electronic and magnetic nanodevices. In this paper, the current understanding and the fundamental issues related to the size effects on the magnetic properties and charge ordering in manganites are reviewed, which covers lattice structure, magnetic and electronic properties in both ferromagnetic and antiferromagnetic based manganites. In addition to review the literatures, this article identifies the promising avenues for the future research in this area.Analog architectures for neural network acceleration based on non-volatile memoryAnalog hardware accelerators, which perform computation within a dense memory array, have the potential to overcome the major bottlenecks faced by digital hardware for data-heavy workloads such as deep learning. Exploiting the intrinsic computational advantages of memory arrays, however, has proven to be challenging principally due to the overhead imposed by the peripheral circuitry and due to the non-ideal properties of memory devices that play the role of the synapse. We review the existing implementations of these accelerators for deep supervised learning, organizing our discussion around the different levels of the accelerator design hierarchy, with an emphasis on circuits and architecture. We explore and consolidate the various approaches that have been proposed to address the critical challenges faced by analog accelerators, for both neural network inference and training, and highlight the key design trade-offs underlying these techniques.Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed.

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