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Self-assembly exists widely in natural living system and artificial synthetic material system. Administration of self-assemblies of artificial architectures in living cells can be used to explore the molecular physicochemical fundamentals and operating mechanisms of living system, and consequently promote the development of biomedicine. In order to mimic naturally occurring self-assemblies and realize controllable functions, great efforts have been devoted to constructing dynamic assembly of artificial architectures in living cells by responding to intracellular specific stimuli, which can be used to regulate morphology, behaviors and fate of living cells. This review highlights the recent progress on artificial self-assembly in living cells. The molecular fundamentals and characteristics of intracellular environment that can induce the self-assembly of artificial architectures are introduced, and the representative work on dynamic artificial self-assembly in living cells is sketched chronologically. Moreover, intracellular stimuli-mediated pathways of artificial assembly in living cells are categorized, biological effects caused by intracellular self-assembly are summarized, and biomedical applications focusing on therapy and imaging are described. In the end, the perspective and challenges of artificial self-assembly in living cells are fully discussed. It is believed that the grand advances on artificial self-assembly in living cells will contribute to elaborate the molecular mechanisms in cells, and further promote the biological and medical-related applications in the future.

Research into organic light emitters employing multiple resonance-induced thermally activated delayed fluorescence (MR-TADF) materials is presently attracting a great deal of attention due to the potential for efficient deep-blue emission. However, the origins and mechanisms of successful TADF are unclear, as many MR-TADF materials do not show TADF behaviour in solution, but only as particular pure solids. Here, an investigation into a well-known MR-TADF material, DABNA-1, together with other new MR materials (9H-quinolino[3,2,1-kl]phenothiazin-9-one (QPO) and 9H-quinolino-[3,2,1-kl]-phenothiazin-9-one 5,5-dioxide (QP3O)), yields new insights regarding the origin of TADF. Although a material system may support the concept of MR, inefficiency in both forward and reverse intersystem crossings forbids TADF unless a suitable host material allows an exciplex-like host–emitter interaction that boosts TADF. This boosted-TADF mechanism can be generalized to any fluorescence dye that lacks TADF in the photoluminescence measurement but has a thermally accessible S1–T1 energy gap, opening the way to high-performance organic light-emitting diodes. This study reveals the importance of host–guest interactions for effective multiple-resonance thermally activated delayed fluorescence in organic light emitters.

We simulate transport for proposed low excess-noise avalanche photodiode InAlAs/InAsSb type-II superlattice materials to evaluate their impact ionization coefficients; a key metric in determining avalanche photodiode performance. The ensemble Monte Carlo method is utilized to develop a stochastic transport kernel suitable for superlattice transport in the static field approximation. The electronic band structure and impact ionization rates are computed from a 14-band superlattice envelope function $$\varvec{K}\cdot \varvec{p}$$ formalism. We reveal that band engineering through superlattice design can be utilized to enhance the electron-to-hole impact ionization ratio in the InAlAs/InAsSb superlattice material system.

Liquid crystalline elastomers (LCEs) are crosslinked polymer networks that combine the elastic properties of rubber with the anisotropic properties of liquid crystals. Multifunctionality and responsivity can be programmed into LCEs by patterning their local orientation, which is difficult to achieve in other monolithic material systems. Advances in the synthesis and alignment of LCEs have paved the way for their functional integration in robotics, optics, consumer products, energy and healthcare devices. In this Review, we discuss recent advances in materials chemistry and processing that have contributed to the resurgence in LCE research. We examine the mechanical response of LCEs to stimuli and survey approaches for mechanical alignment, surface-enforced alignment, field-induced alignment and rheological alignment. The Review concludes with an over-the-horizon outlook discussing current challenges and emerging research opportunities. Liquid crystalline elastomers are stimuli-responsive polymeric materials whose mechanical properties can be programmed by patterning their local orientation, making them promising candidates to serve as low-density actuators and functional elements in various applications. This Review discusses the synthesis and processing of liquid crystalline elastomers, with a focus on alignment methods and potential applications.

Copper (Cu) and its alloys are prospective materials in fighting covid-19 virus and several microbial pandemics, due to its excellent antiviral as well as antimicrobial properties. Even though many studies have proved that copper and its alloys exhibit antiviral properties, this research arena requires further research attention. Several studies conducted on copper and its alloys have proven that copper-based alloys possess excellent potential in controlling the spread of infectious diseases. Moreover, recent studies indicate that these alloys can effectively inactivate the covid-19 virus. In view of this, the present article reviews the importance of copper and its alloys in reducing the spread and infection of covid-19, which is a global pandemic. The electronic databases such as ScienceDirect, Web of Science and PubMed were searched for identifying relevant studies in the present review article. The review starts with a brief description on the history of copper usage in medicine followed by the effect of copper content in human body and antiviral mechanisms of copper against covid-19. The subsequent sections describe the distinctive copper based material systems such as alloys, nanomaterials and coating technologies in combating the spread of covid-19. Overall, copper based materials can be propitiously used as part of preventive and therapeutic strategies in the fight against covid-19 virus.

Discrete dislocation structures and their evolution are known to control the mechanical properties of metal samples. However, the lack of computationally efficient and statistically rigorous descriptors for such defect systems has hindered the development and adoption of rational protocols for the optimal design of these material systems. This study presents a framework for the rigorous statistical quantification and low-dimensional representation of dislocation structures using the formalism of 2-point statistics (also called 2-point spatial correlations) along with principal component analysis. The usefulness of this basic framework for comparing and observing dislocation structures is exemplified and discussed with suitable examples.

Organic mechanochromic materials(also known as piezochromic materials), whose color or emission changes under mechanical force, have attracted great interest owing to their potential applications in pressure sensors, rewritable materials, optical storage, and security ink. Organic mechanochromic materials with aggregation-induced emission(AIE) features have better development prospects and research value owing to their excellent optical properties. To date, mechanochromism has mostly been realized by means of mechanical grinding. Nevertheless, the magnitude of the grinding force is usually uncontrollable and its direction is anisotropic, making it awkward to study the mechanism of mechanochromic materials. On the contrary, hydrostatic pressure, whose magnitude and direction are controllable, is a more valid and governable method to investigate the mechanism of mechanochromic materials, which can help us to construct a meaningful structure-property relationship and understand the latent origin of the mechanochromism. Furthermore, it is conducive to developing other mechanochromic material systems with desired chemical and physical properties. In this review, we focus on the recent progress in the mechanism of organic mechanochromic materials with AIE features under hydrostatic pressure. Four types of mechanisms are included: intermolecular interaction change, intramolecular conformation change, transformation from locally excited state to intramolecular charge-transfer state, and intra- and inter-molecular effects induced by hydrostatic pressure, respectively.

The evolution of cellular morphology during interfacial instability for liquid–solid transition for pure unary material systems is studied using the maximum entropy production (generation) rate principle (MEPR) for steady-state directional solidification. This approach is dependent on a quantity called maximum entropy production rate density which inherently contains key solidification parameters that governs cellular evolution for liquid–solid transformation. The maximum entropy production rate density is computationally measured from the solid–liquid interface in diffuse form and considers steady-state solidification at low velocities for both near and far from equilibrium conditions. The results are presented in mathematical expressions for morphological instability that corresponding to the evolution of a cellular morphology which emanates from the solid–liquid interface. The model is formulated to evaluate the solid–liquid interface thickness, the solidification velocity, grain boundary energy, and the size of the cellular morphological at instability. The results are tested with a number of pure single element materials at different temperature gradients which compare well with available experimental data.

This paper introduces a speculative method of 3D printing reinforced concrete columns called “piling and pressing.” Innovations in concrete 3D printing research are discussed, specifically those that pertain to the integration of reinforcement, the customization of printing extruders, and the development of 3D printed concrete structures as architectural components. Previous research into an experimental technique of 3D printing concrete called “pointillistic, time-based deposition” (PTBD) is introduced. Findings from research into PTBD that led to the development of the piling and pressing method are presented. The custom concrete 3D printing system that was innovated in order to develop the piling and pressing method is outlined in detail, including its material systems, mechatronic configurations, and temporal parameters. Challenges in both the prototyping of this system and the piling and pressing method are discussed. Finally, future investigations into the piling and pressing method are outlined with a particular emphasis on those that will advance this method towards full-scale architectural construction.

Automated fibre placement (AFP) is an advanced manufacturing process with a built-in heat and pressure system, an effective method for in situ consolidation of composite parts. In the present study, carbon fibre PA-6 prepregs were laminated by an IR-assisted AFP system, and the effect of process parameters on the resulting part quality was studied. Of the six fundamental process parameters, two parameters, i.e., laying speed and IR power were identified to be critical. Hence, the current study is focussed on the optimization of these two parameters while keeping the others constant. Three different combinations of IR power and laying speed were deduced to be optimised parameters for the material system used. In general, the laying speed should be increased along with the appropriate increase in IR power. Through visual and microstructural inspection, the laminate manufactured with these optimised parameters were found to have fewer defects and better consolidation when compared with samples manufactured with unoptimised combinations.

Bilinear delamination failure criteria proposed by Reeder for mixed-mode (I–II) fracture of composite laminates has four limitations: require mixed-mode (I–II) fracture data by the more complex MMB test; determination of bilinear constants by two independent curve fits; failure of bilinear equations to intersect at $$\hbox {G}_{\mathrm{I}}^{\mathrm{m}}/\hbox {G}_{\mathrm{II}}^{\mathrm{m}}=1$$; and the data representation by $$\hbox {G}_{\mathrm{I}}^{\mathrm{m}}$$ versus $$\hbox {G}_{\mathrm{II}}^{\mathrm{m}}$$ instead of the conventional $$\hbox {G}_{\mathrm{c}}^{\mathrm{m}}$$ versus $$\hbox {G}_{\mathrm{II}}^{\mathrm{m}}/\hbox {G}_{\mathrm{T}}$$. Some of these limitations were overcome by limited input bilinear criteria (LIBC) proposed by Davidson and Zhao by replacing the MMB test data by DCB, ENF, and SLB (single leg beam) test data. But the LIBC retained the two discontinuous forms of the equations for no specific reason in a continuous material system. This paper eliminates the two equations by a single power law equation that covers the whole domain of fracture as in Benzeggagh and Kenane’s empirical equation. This simplified mixed-mode delamination fracture criterion we call “Limited Input B–K (LIBK) criterion in recognition of the works of Davidson and Zhao, and Benzeggagh and Kenane. The criterion was validated by a large number of test data in the literature.

The colloidal quantum dots (CQDs) are a promising nanometer-sized material system for optoelectronic applications due to the low cost, room temperature processing and substrate compatibility. Solution-processed technology such as spin-coating can make CQDs large-scale deposition on the substrates, whereas it inevitably brings about CQDs adherence to the edges even bottom of the substrates. As a result, the devices are not isolated and vertical leakage current occurs from the surface of CQDs to the substrates. In this work, two kinds of CQDs patterning techniques named etching-assisted patterning (EAP) and lift-off assisted patterning (LAP) have been put forward to significantly suppress the vertical current from several nanoampere to a few picoampere. Meanwhile, the CQDs photoconductor detectors have also been fabricated through these two patterning methods on the SiO2/Si substrates. Compared with un-patterning (UP) photodetectors, these two techniques both can enhance the photocurrent and promote the optoelectrical quality factors such as the responsivity and the specific detectivity, which make it possible to manufacture CQDs detector arrays and promote CQDs in optoelectronic applications.

A thorough study of phase separation in borosilicate glasses synthesized in the material system soda – colemanite – quartz sand was performed. The ranges of crystallization-resistant glasses and phase separation prone glasses were determined. It is shown that the complex raw material colemanite can be used to obtain glasses that are transparent or opaque in the bulk. The limiting content of raw materials in the material makeup of glass batches are recommended.

This work presents a framework for collectively modeling shear viscosities of grouped polymeric materials. The viscosity model has been derived from the multi-modal White-Metzner constitutive equation. Simplification to the multi-modal viscosity has resulted in a viscosity model that controls gradual transition between two conventional viscosity models. It facilitates mathematical representation of multiple sets of viscosity data at the same time. A conventional shear viscosity function, which is common to the group, is multiplied by a material-specific function with one or two constants to form the collective viscosity model. The proposed framework has been applied to several polymeric systems such as polymers with varying molecular weight, polymer solutions with different concentrations, polymers with different filler loadings, and polymer blends with various composition ratios. It has been shown that the K-index in the proposed viscosity model and the variable in the material system such as concentration or compounding ratio can be correlated with each other to predict the viscosities of untested cases.

Biodegradable materials, including natural and synthetic polymers and hydrolyzable metals, constitute the main components of temporary, implantable medical devices. Besides the intrinsic properties of the materials, the most critical factor determining the successful clinical outcome of implantable and degradable devices is the host response, particularly the immune response, which largely depends on the material features and degradation mechanisms. In this Review, we first survey the state of the art in terms of materials options for use in biodegradable medical devices, focusing on degradation mechanisms and their control. In particular, we highlight silk, which is emerging as an important polymer, owing to its mechanical robustness, bioactive component sequestration, degradability without problematic metabolic products and biocompatibility. We then discuss the host response to these biodegradable materials in terms of dynamic tissue–implant interfaces. Next, we examine the clinical translation of three leading biodegradable material systems — natural and synthetic biodegradable polymers and biodegradable metals — and the related challenges in the context of orthopaedic fixation devices, cardiovascular stents and biodegradable electronic devices. Looking to the future, we propose updated material design strategies to improve the clinical outcomes for these biodegradable medical devices. Clinical outcomes with implantable and degradable devices largely depend on host response. This Review surveys material options and degradation mechanisms relevant to host responses to biodegradable devices, examines clinical translation of leading biodegradable materials and proposes updated material-design strategies to improve device performance.

The dynamic fracture of high-stiffness and low-toughness materials such as soda-lime glass (SLG) typically involves crack initiation and growth prior to branching, underlying mechanics of which is not yet fully understood. Investigation of this issue using full-field optical techniques face numerous spatio-temporal challenges since crack speeds in these materials reach 1500 m/s or more and are accompanied by highly localized deformations. However, often it is tacitly assumed that most optical methods are equally capable of studying this challenging problem and it turns out not to be true. To this end, three prevalent optical techniques - transmission photoelasticity, 2D Digital Image Correlation (DIC) and transmission Digital Gradient Sensing (DGS) - are implemented concurrently to visualize crack-tip fields and quantify fracture characteristics associated with crack initiation, crack growth and macroscopic crack bifurcation in SLG plates subjected to nominally identical loading in three separate experiments. Each method is implemented in conjunction with ultrahigh-speed (1 Mfps) photography, flash/pulse illumination, and a modified-Hopkinson pressure bar for impact loading of specimens. The feasibility of measuring fracture parameters and imposed force histories along with the pros and cons of each approach for this material system are examined.

Machine learning (ML) has revolutionized disciplines within materials science that have been able to generate sufficiently large datasets to utilize algorithms based on statistical inference, but for many important classes of materials the datasets remain small. However, a rapidly growing number of approaches to embedding domain knowledge of materials systems are reducing data requirements and allowing broader applications of ML. Furthermore, these hybrid approaches improve the interpretability of the predictions, allowing for greater physical insights into the factors that determine material properties. This review introduces a number of these strategies, providing examples of how they were implemented in ML algorithms and discussing the materials systems to which they were applied.

Organoids are 3D cell culture systems that mimic some of the structural and functional characteristics of an organ. Organoid cultures provide the opportunity to study organ-level biology in models that mimic human physiology more closely than 2D cell culture systems or non-primate animal models. Many organoid cultures rely on decellularized extracellular matrices as scaffolds, which are often poorly chemically defined and allow only limited tunability and reproducibility. By contrast, the biochemical and biophysical properties of engineered matrices can be tuned and optimized to support the development and maturation of organoid cultures. In this Review, we highlight how key cell-matrix interactions guiding stem-cell decisions can inform the design of biomaterials for the reproducible generation and control of organoid cultures. We survey natural, synthetic and protein-engineered hydrogels for their applicability to different organoid systems and discuss biochemical and mechanical material properties relevant for organoid formation. Finally, dynamic and cell-responsive material systems are investigated for their future use in organoid research.

This paper presents an experimental study for the assessment of a three-dimensional Progressive Fatigue Damage Model (PFDM) with a carbon fiber/epoxy (AS4/3501–6) material system. Specimens with a central circular hole were selected to represent notched composite structures. Digital Image Correlation (DIC) was used to monitor the surface strain evolution throughout the fatigue lifetime. The PFDM model was implemented in the commercial finite element software ABAQUS using the user material (UMAT) utility. Residual stresses from the composite manufacturing cycle are included in the fatigue damage modeling. Results are presented that compare experimental and predicted strain distributions and fatigue lives. Comparisons between the experimental and simulated response highlight the value of the PFDM model while demonstrating its shortcomings.

Many materials systems comprise complex structures where multiple materials are integrated to achieve a desired performance. Often in these systems, it is a combination of both the materials and their structure that dictate performance. Here the authors layout an integrated computational–statistical–experimental methodology for hierarchical materials systems that takes a holistic design approach to both the material and structure. The authors used computational modeling of the physical system combined with statistical design of experiments to explore an activated carbon adsorption bed. The large parameter space makes experimental optimization impractical. Instead, a computational–statistical approach is coupled with physical experiments to validate the optimization results.

Rechargeable batteries have a profound impact on our daily life so that it is urgent to capture the physical and chemical fundamentals affecting the operation and lifetime. The phase-field method is a powerful computational approach to describe and predict the evolution of mesoscale microstructures, which can help to understand the dynamic behavior of the material systems. In this review, we briefly introduce the theoretical framework of the phase-field model and its application in electrochemical systems, summarize the existing phase-field simulations in rechargeable batteries, and provide improvement, development, and problems to be considered of the future phase-field simulation in rechargeable batteries.

Nonreciprocal directional dichroism in multiferroics, namely magnetoelectric coupling in the dynamic regime, is endowed with rich physics and promising applications, which are entangled with fundamental physical components, such as spin, orbital, lattice, charge, and topology. Such a linear nonreciprocal response behavior in the GHz-THz frequency range, represented by optical magnetoelectric effect and magnetochiral dichroism, occurs ubiquitously in material systems with the spontaneous breaking of space-time symmetry, and is subject to Onsager’s reciprocal theorem in the thermodynamic limit. Microscopically, these nonreciprocal responses are usually encoded by toroidization (chirality) and electromagnon (quasiparticle), thus establishing a comprehensive understanding of magnetoelectric coupling and irreversible dynamics. Herein, the basic mechanisms and emergent nonreciprocal directional dichroism in single-phase multiferroics are summarized. We expect that the present review will stimulate diverse possibilities toward nonreciprocal directional dichroism within and beyond multiferroics.

A new specialised finite element for simulating the cracking and healing behaviour of quasi-brittle materials is presented. The element employs a strong discontinuity approach to represent displacement jumps associated with cracks. A particular feature of the work is the introduction of healing into the element formulation. The healing variables are introduced at the element level, which ensures consistency with the internal degrees freedom that represent the crack; namely, the crack opening, crack sliding and rotation. In the present work, the element is combined with a new cohesive zone model to simulate damage-healing behaviour and implemented with a crack tracking algorithm. To demonstrate the performance of the new element and constitutive models, a convergence test and two validation examples are presented that consider the response of a vascular self-healing cementitious material system for three different specimens. The examples show that the model is able to accurately capture the cracking and healing behaviour of this type of self-healing material system with good accuracy.

27Al, 51V, 52Cr, 55Mn, 56Fe and 58Ni nuclei are some structural fusion substances. The neutron incident energy around 14–15 MeV is adequate to excite the nucleus for the reactions such as (n, p), (n, d), (n, 2n), (n, t), and (n, α). For fusion reactor technology, the reaction cross-sectional data have a critical importance in fusion reactors and development. Neutron irradiation produces considerable modifications in the mechanical and physical properties of each of the structural fusion material systems raising feasibility questions and design limitations. In this paper, for some structural fusion materials (n, α) reactions such as 52Cr(n, α)49Ti, 51V(n, α)48Si, 27Al(n, α)24Na, 58Ni(n, α)55Fe, 56Fe(n, α)53Cr and 55Mn(n, α)52V were done up to 40 MeV incident neutron energy. In the calculations, the equilibrium and pre-equilibrium impacts have been used. Calculations have been carried out with TALYS 1.9 and EMPIRE 3.2 (Malta) nuclear model codes. Results from performed calculations have been compared with the experimental nuclear reaction data, ENDF/B-VII.b4, JENDL-4.0 and JEFF-3.2 evaluated data.

Any mechanical modeling of matter depends primarily on the chosen spatial and temporal observation scales. Roughly speaking, there are three such scales, microscopic for quantum, mesoscopic for statistical, and macroscopic for continuum mechanics. This by itself demands for adequate scale-bridging procedures. This paper focuses on the passage from molecular to continuum formulations of the basic balance laws of linear momentum and energy, kinetic, internal, and total. The procedure used is a modification of that introduced by Irving & Kirkwood (J. Chem. Phys. 18(6):817–829, 1950), as improved by Noll (Indiana Univ. Math. J. 4:627–646, 1955); alternative procedures are mentioned. The proposed modification consists primarily in equipping provisionally the target continuum balances with internal-source terms accounting at the macroscopic scale for microscopic motion randomness, when, e.g., a loosely aggregated material system evolves at relatively high temperature. Attention is also devoted to those continuum notions that either are hardly given a universally accepted molecular counterpart or even cannot and ultimately need not be given one, such as the notion of material point.

A material system known as magic-angle twisted trilayer graphene exhibits superconductivity. The observation that this superconductivity persists under a strong magnetic field could lead to advances in quantum computation. Evidence of spin-triplet superconductivity in a quasi-2D system.

Intense efforts are underway to produce circuits that integrate a technologically relevant number of qubits. Although qubit control in most material systems is by now mature, device variability is one of the main bottlenecks in qubit scalability. How do we characterize and tune millions of qubits? Machine learning might hold the answer.

Large piezoelectricity (d33) and high Curie temeprature (TC) are highly expected to attain in alkaline niobate-based piezoceramics, which is of high significance in the practical applications. For the compositionally optimized composition, we achieved both large d33 (~ 395 pC/N) and high TC (~ 342 °C) in (0.995-x)K0.485Na0.485Li0.03NbO3–xBi0.5(Na0.8K0.2)0.5ZrO3–0.005BiScO3 (0 ≤ x ≤ 0.06) (KNNL–xBNKZ–BS) lead-free ceramics through the construction of rhombohedral–orthorhombic–tetragonal (R–O–T) phase boundary. A systematic study of the effect of phase boundary on resulting piezoelectric, ferroelectric, and strain properties in the ceramics was investigated. The KNNL–xBNKZ–BS ceramics with x = 0.04 exhibited an enhanced unipolar strain properties (strain ~ 0.161%, d33*~402 pm/V) and thermal stability of d33 (Ta ≤310 °C, normalized d33 ≥ 84.6%), which was mainly ascribed to the R–O–T phase boundary and high TC respectively. Therefore, a balanced development of the parameters (e.g., d33, TC) can be well realized in KNNL–xBNKZ–BS ceramics, we believe that such a material system opens a window for the practical applications.

The Ag–Cu–In thermodynamic material system is of interest for brazing alloys and chalcopyrite thin-film photovoltaics. To advance these applications, Ag–Cu–In was assessed and a Calphad model was developed. Binary Ag–Cu and Cu–In parameters were taken from previous assessments, while Ag–In was re-assessed. Structure-based models were employed for β-bcc(A2)-Ag3In, γ-Ag9In4, and AgIn2 to obtain good fit to enthalpy, phase boundary, and invariant reaction data for Ag–In. Ternary Ag–Cu–In parameters were optimized to achieve excellent fit to activity, enthalpy, and extensive phase equilibrium data. Relative to the previous Ag–Cu–In assessment, fit was improved while fewer parameters were used.

Perovskite solar cells have achieved power-conversion efficiency values approaching those of established photovoltaic technologies, making the reliable assessment of their operational stability the next essential step towards commercialization. Although studies increasingly often involve a form of stability characterization, they are conducted in non-standardized ways, which yields data that are effectively incomparable. Furthermore, stability assessment of a novel material system with its own peculiarities might require an adjustment of common standards. Here, we investigate the effects of different environmental factors and electrical load on the ageing behaviour of perovskite solar cells. On this basis, we comment on our perceived relevance of the different ways these are currently aged. We also demonstrate how the results of the experiments can be distorted and how to avoid the common pitfalls. We hope this work will initiate discussion on how to age perovskite solar cells and facilitate the development of consensus stability measurement protocols.

In this review article, we present and discuss recent mesoscale modeling studies of slip transmission of dislocations through biphase interfaces. Specific focus is given to fcc/fcc material systems. We first briefly review experimental, atomistic, and continuum-scale work that has helped to shape our understanding of these systems. Then several mesoscale methods are discussed, including Peierls–Nabarro models, discrete dislocation dynamics models, and phase field-based techniques. Recent extensions to the mesoscale mechanics technique called phase field dislocation dynamics are reviewed in detail. Results are compiled and discussed in terms of the proposed guidelines that relate composite properties to the critical stress required for a slip transmission event.

Avoiding the catastrophic failure of a large structure demands the material’s microstructure be designed in such as a way as to render any crack present innocuous thereby raising the integrity of that structure. Structural integrity of a composite material embraces contributions from: materials science and engineering; processing science; design and fabrication technology. It combines a number of interacting factors: the criticality of the application; the accessibility for and ability to inspect vital parts and components; the intended use including load spectrum and time; the consequences of impact, fatigue, temperature and hostile environment; the nature of inherent flaws; the constituent properties of the material system utilized; and it takes into account human factors.

This paper presents a framework for the modeling and analysis of material systems that exhibit uncertainties in their constituents at all scales. The framework integrates multiscale formalism with a polynomial chaos construction enabling an explicit representation of quantities of interests, at any scale, in terms of any form of underlying uncertain parameters, a key feature to model multiscale dependencies. It is demonstrated how the framework can successfully tackle settings where a hierarchy of scales must be explicitly modeled. The application of this framework is illustrated in the construction of stochastic models of mesoscale and macroscale properties of non-crimp fabric composites. Joint statistical properties of upscaled components of the composite, including properties of tow, laminae and laminate, are computed.

A living electrode construct that enables integration of cells within bionic devices has been developed. The layered construct uses a combination of non-degradable conductive hydrogel and degradable biosynthetic hydrogel to support cell encapsulation at device surfaces. In this study, the material system is designed and analyzed to understand the impact of the cell carrying component on electrode characteristics. The cell carrying layer is shown to provide a soft interface that supports extracellular matrix development within the electrode while not significantly reducing the charge transfer characteristics. The living layer was shown to degrade over 21 days with minimal swelling upon implantation.

Material systems that reside far from thermodynamic equilibrium have the potential to exhibit dynamic properties and behaviours resembling those of living organisms. Here we realize a non-equilibrium material characterized by a bandgap whose edge is enslaved to the wavelength of an external coherent drive. The structure dynamically self-assembles into an unconventional pseudo-crystal geometry that equally distributes momentum across elements. The emergent bandgap is bestowed with lifelike properties, such as the ability to self-heal to perturbations and adapt to sudden changes in the drive. We derive an exact analytical solution for both the spatial organization and the bandgap features, revealing the mechanism for enslavement. This work presents a framework for conceiving lifelike non-equilibrium materials and emphasizes the potential for the dynamic imprinting of material properties through external degrees of freedom.

One challenge in adapting welding processes to dissimilar material joining is the diversity of melting temperatures of the different materials. Although the use of mechanical fasteners and adhesives have mostly paved the way for near-term implementation of dissimilar material systems, these processes only accentuate the need for low-cost welding processes capable of impartially joining dissimilar material components regardless of alloy, properties, or melting temperature. Friction stir scribe technology was developed to overcome the challenges of joining dissimilar material components where melting temperatures vary greatly, and properties and/or chemistry are not compatible with more traditional welding processes. Although the friction stir scribe process is capable of joining dissimilar metals and metal/polymer systems, a more detailed evaluation of several aluminum/steel joints is presented herein to demonstrate the ability to both chemically and mechanically join dissimilar materials.

The microstructural evolvement and friction performance of Cu/FeS self-lubricating composites within electric field were studied by molecular dynamics simulation. The atoms distribution and movement of the Cu/FeS composite under different electric field strengths were considered. The results show that some Fe atoms and S atoms break away from the original structure and move along the electric field, but the movement of Fe atoms and S atoms is not synchronized in stronger electric field strength. Thus, the whole material system becomes chaotic and its temperature rises. The unevenly electric field force appears in the material for the nonuniform FeS distribution, so the internal stress of the composite is generated. For the internal solid lubricating phases move along the direction of the electric field to the surface of the composite, the adhesive wear and the friction coefficient reduce. The movement of the phases leaves over some voids in the composite, which induces arc wear easily.

As the metal additive manufacturing (AM) industry moves towards industrial production, the need for qualification standards covering all aspects of the technology becomes ever more prevalent. While some standards and specifications for documenting the various aspects of AM processes and materials exist and continue to evolve, many such standards still need to be matured or are under consideration/development within standards development organizations. An important subset of this evolving the standardization domain has to do with critical property measurements for AM materials. While such measurement procedures are well documented, with various legacy standards for conventional metallic material forms such as cast or wrought structural alloys, many fewer standards are currently available to enable systematic evaluation of those properties in AM-processed metallic materials. This is due in part to the current lack of AM-specific standards and specifications for AM materials and processes, which are a logical precursor to the material characterization standards for any material system. This paper summarizes some of the important standardization activities, as well as limitations associated with using currently available standards for metal AM with a focus on measuring mission-critical properties. Technical considerations in support of future standards development, as well as a pathway for qualification/certification of AM parts enabled by the appropriate standardization landscape, are discussed.

By applying computer vision and machine learning methods, we develop a system to characterize powder feedstock materials for metal additive manufacturing (AM). Feature detection and description algorithms are applied to create a microstructural scale image representation that can be used to cluster, compare, and analyze powder micrographs. When applied to eight commercial feedstock powders, the system classifies powder images into the correct material systems with greater than 95% accuracy. The system also identifies both representative and atypical powder images. These results suggest the possibility of measuring variations in powders as a function of processing history, relating microstructural features of powders to properties relevant to their performance in AM processes, and defining objective material standards based on visual images. A significant advantage of the computer vision approach is that it is autonomous, objective, and repeatable.

In the canton of Geneva, public authorities use infrastructural and persuasive instruments to favour household waste sorting. The cantonal fund for waste management (CFWM) partly finances these policy instruments. The aim of this study is to assess household waste management (WM) in Geneva with a focus on waste sorting and the operation of the CFWM. This study relies on a new assessment method which combines material system analysis and policy analysis. This combination analyses how the resources used for household WM influence the state of the WM system. The assessment shows that the resources used by public authorities led to a growth in waste sorted and a decrease in waste incinerated in Geneva over the period 2002–2013. This trend, combined with a strong decrease in imported waste, induced the monopolisation by waste collection centres of the available funds in the CFWM budget at the expense of cantonal raising awareness. The assessment leads to two recommendations for decision makers. First, a policy instrument mix based on infrastructural and persuasive instruments constitutes an effective approach to favour waste sorting by households. Second, the use of a “disposal tax” does not constitute a sustainable approach to finance the operating costs of the sorting infrastructure.

Mesoscale interfaces and interphases play a central role in controlling the many macroscale mechanical properties and performance characteristics of structural materials. Modern instrumented indenters present an unprecedented opportunity to measure, reliably and consistently, the local mechanical responses at a multitude of length scales ranging from tens of nanometers to hundreds of microns. When these high-fidelity measurements are combined with rigorous data analyses protocols, it is possible to systematically study the mechanical role of individual mesoscale interfaces and quantify their contributions to the overall mechanical response of the material system . The advantages of these new measurement and analyses protocols as well as the potential for development and implementation of novel high-throughput assays is discussed.

Three-dimensional (3D) printing of metallic materials involves the layerwise consolidation of feedstock materials in the form of powder, wire, or sheet using various energy sources to form complex shapes. The past two decades have witnessed significant advances in the field, in terms of both technologies and materials for metal 3D printing. This has led to widespread exploration and adoption of the technologies across industry, academia, and R&D organizations. This article presents an overview of the field of metal 3D printing. A brief history of metal 3D printing is followed by an overview of metal 3D printing methods and metallic material systems used in these methods. Microstructure and properties, and their relationship to process parameters are discussed next, followed by current challenges and qualification issues. The article concludes with future trends and a brief description of the invited articles included in this special issue.

We present a review of our recent studies of Bias Temperature Instability (BTI) in Metal-Oxide-Semiconductor Field-Effect-Transistors (MOSFETs) fabricated with different material systems, highlighting the reliability opportunities and challenges of each novel device family. We discuss first the intrinsic reliability improvement offered by SiGe and Ge p-channel technologies, if a Si cap is used to passivate the channel, in order to fabricate a standard SiO2/HfO2 gate stack. We focus on SiGe gate stack optimizations for maximum BTI reliability, and on a simple physics-based model able to reproduce the experimental trends. This model framework is then used to understand the suboptimal BTI reliability and excessive time-dependent variability induced by oxide defect charging in different high-mobility channel gate stacks, such as Ge/GeOx/high-k and InGaAs/high-k. Finally we discuss how to pursue a reduction of charge trapping in alternative material systems in order to boost the device reliability and minimize time-dependent variability.

A literature review on the thermal spray deposition of metals onto polymer-based structures is presented. The deposition of metals onto polymer-based structures has been developed to enhance the thermal and electrical properties of the resulting metal-polymer material system. First, the description of the thermal spray metallization processes and technologies for polymer-based materials are outlined. Then, polymer surface preparation methods and the deposition of metal bond-coats are explored. Moreover, the thermal spray process parameters that affect the properties of metal deposits on polymers are described, followed by studies on the temperature distribution within the polymer substrate during the thermal spray process. The objective of this review is devoted to testing and potential applications of thermal-sprayed metal coatings deposited onto polymer-based substrates. This review aims to summarize the state-of-the-art contributions to research on the thermal spray metallization of polymer-based materials, which has gained recent attention for potential and novel applications.

Nucleation is the first step in the formation of many materials; understanding its microscopic dynamics is crucial for improving synthesis of existing materials and predicting under what conditions novel materials will form. The simple picture of nucleation that prevailed for more than a century does not account for complex nucleation pathways observed in recent years in experiments and simulations. A more general framework is needed to explain reported phenomena; such a framework must account for the peaks and valleys in the free-energy landscape across which nucleation takes place and for the microscopic dynamic factors that dictate how a system explores this landscape. The articles of this issue illustrate and describe the many complex nucleation pathways seen across a range of material systems.

A comprehensive investigation of the interfacial misfit (IMF) array formation has been carried out. The studies were based on the static phase diagram for GaAs (001) surface and As2 dimers on the surface. Prior to the initiation of the GaSb growth two attempts of the temperature decreasing were performed: before and after the GaAs termination. The GaAs was grown in the optimal conditions for GaSb material. The influence of the interruption time on GaSb/GaAs heterostructure parameters was examined. Two cases were investigated: with and without Sb-soaking of the GaAs surface. The periodic array of edge dislocations at GaSb/GaAs interface was confirmed using Burger’s circuit theory. Careful examination of misfit surroundings revealed one uncompleted Burger’s vector that indicated one dislocation of mixed type among eight of the edge type. The distance between lattice sites of dislocations was 5.51 nm on average. The crystal quality of 5.0 µm GaSb layer was characterized by FWHM2θ/ω = 42 arcsec, FWHMRC = 125 arcsec. The EPD = 4 × 106 cm− 2 was estimated after etching in FeCl3:HCl solution. The Δqz/Δqx ratio of 0.60 for 5.0 µm GaSb layer was higher than for 2.5 µm GaSb layer of 0.59. The probable reason was the thickness-dependent 60° dislocation density. The electrical parameters measured for 2.5 µm GaSb were: p = 4.0 × 1016cm−3 (2.0 × 1016cm−3) and µ = 599 cm2/V s (3420 cm2/V s) at 300 K (77 K).

Over the last decade, the explosion in research and Development associated with nanoscalar materials has continued apace. In parallel with this has been the rapid rise of both sustainable materials and, as a consequence, Natural, Cellular and Responsive material systems. Many of these originate from inorganic, inorganic-organic hybrid composites and polymeric and bio-nano polymeric systems which exhibit intrinsic physico-chemical properties that can be classed as ‘soft’. That is flexible, malleable, lightweight, transparent or semi-transparent and stretchable in character and which can also offer both biocompatible and bioresorbable characteristics essential to useable and sustainable material systems.\ud This paper describes some of the ways in which we are beginning to understand, explain and exploit ‘soft’ technology. In particular the interactive role of creative design and innovative material science linked through new fabrication methodologies that have, as their common purpose, a focus on compelling Human centred needs. Examples are health, wellness, ambient assistance and urgent improvements in cleanliness, hygiene and nutrition.

As one of the most important semiconductor materials, silicon (Si) has been widely used in current energy and optoelectronic devices, such as solar cells and photodetectors. However, the traditional Si p–n junction solar cells need complicated fabrication processes, leading to the high cost of Si photovoltaic devices. The wide applications of Si-based photodetectors are also hampered by their low sensitivity to ultraviolet and infrared light. Recently, two-dimensional (2D) layered materials have emerged as a new material system with tremendous potential for future energy and optoelectronic applications. The combination of Si with 2D layered materials represents an innovative approach to construct high-performance optoelectronic devices by harnessing the complementary advantages of both materials. In this review, we summarize the recent advances in 2D layered material/Si heterojunctions and their applications in photovoltaic and optoelectronic devices. Finally, the outlook and challenges of 2D layered material/Si heterojunctions for high-performance device applications are presented.

Harnessing big data, deep data, and smart data from state-of-the-art imaging might accelerate the design and realization of advanced functional materials. Here we discuss new opportunities in materials design enabled by the availability of big data in imaging and data analytics approaches, including their limitations, in material systems of practical interest. We specifically focus on how these tools might help realize new discoveries in a timely manner. Such methodologies are particularly appropriate to explore in light of continued improvements in atomistic imaging, modelling and data analytics methods.

Molecular beam epitaxy (MBE) growth of HgCdTe (MCT) on alternative substrates enables production of both cheaper and more versatile (third-generation) infrared (IR) detectors. After rapid progress in the development of MBE-grown MCT on GaAs in recent years, the question of whether the considerable benefits of this material system are also applicable to high-operating-temperature (HOT) applications demands attention. In this paper, we present a mid-wavelength-IR 640 × 512 pixel, 15-μm-pitch focal-plane array with operability of 99.71% at operating temperature of 120 K and low dark current density. In the second part of the paper, MBE growth of short-wavelength IR material with Cd fraction of up to 0.8 is investigated as the basis for future evaluation of the material for low-light-level imaging HOT applications.