Abstract Hydrogen storage is a materials science challenge because, for all six storage methods currently being investigated, materials with either a strong interaction with hydrogen or without any reaction are needed. Besides conventional storage methods, i.e. high pressure gas cylinders and liquid hydrogen, the physisorption of hydrogen on materials with a high specific surface area, hydrogen intercalation in metals and complex hydrides, and storage of hydrogen based on metals and water are reviewed. The goal is to pack hydrogen as close as possible, i.e. to reach the highest volumetric density by using as little additional material as possible. Hydrogen storage implies the reduction of an enormous volume of hydrogen gas. At ambient temperature and atmospheric pressure, 1 kg of the gas has a volume of 11 m3. To increase hydrogen density, work must either be applied to compress the gas, the temperature decreased below the critical temperature, or the repulsion reduced by the interaction of hydrogen with another material.
Eight structural elements in biological materials are identified as the most common amongst a variety of animal taxa. These are proposed as a new paradigm in the field of biological materials science as they can serve as a toolbox for rationalizing the complex mechanical behavior of structural biological materials and for systematizing the development of bioinspired designs for structural applications. They are employed to improve the mechanical properties, namely strength, wear resistance, stiffness, flexibility, fracture toughness, and energy absorption of different biological materials for a variety of functions (e.g., body support, joint movement, impact protection, weight reduction). The structural elements identified are: fibrous, helical, gradient, layered, tubular, cellular, suture, and overlapping. For each of the structural design elements, critical design parameters are presented along with constitutive equations with a focus on mechanical properties. Additionally, example organisms from varying biological classes are presented for each case to display the wide variety of environments where each of these elements is present. Examples of current bioinspired materials are also introduced for each element.
The goal of the current publication is to provide a comprehensive literature review on the topic of dental implant materials. The following paper focuses on conventional titanium implants and more recently introduced and increasingly popular zirconia implants. Major subtopics include the material science and the clinical considerations involving both implant materials and the influence of their physical properties on the treatment outcome. Titanium remains the gold standard for the fabrication of oral implants, even though sensitivity does occur, though its clinical relevance is not yet clear. Zirconia implants may prove to be promising in the future; however, further in vitro and well-designed in vivo clinical studies are needed before such a recommendation can be made. Special considerations and technical experience are needed when dealing with zirconia implants to minimize the incidence of mechanical failure.
Abstract Two-dimensional materials (2DMs), possessing atomic-scale thickness, are prone to brittle fracture under loading conditions, which can lead to catastrophic failure. As their structural dimensions approach the nanoscale, conventional linear elastic fracture mechanics (LEFM) based on continuum assumptions is deficient in capturing the underlying failure mechanisms and accurately predicting potential crack instability. This limitation emphasizes the critical need for a new theoretical approach suited to the fracture behavior of 2DM systems. We propose a unified fracture mechanics (UFM) criterion that systematically incorporates two key physical mechanisms governing brittle fracture in 2DMs at the nanoscale, namely nonlinear elasticity and atomic-scale discreteness. By introducing two corrective parameters, for nonlinearity and quantization, the UFM model successfully resolves the limitations of LEFM in predicting failure. This is particularly important in the short crack regime, as small defects are frequent in 2DMs. The theoretical predictions show excellent agreement with molecular dynamics simulations of five different types of 2DMs and accurately capture the fracture strength of both cracked and defect-free structures. In addition, we present an empirical method that allows the fracture behavior of 2DMs to be estimated directly from their intrinsic structural and elastic properties. The unified theoretical framework is applicable not only to the materials simulated in this study but may also be applied to a broader class of atomically thin brittle systems.
Materials of engineering and construction. Mechanics of materials, Computer software
Abstract Aqueous zinc sulfur batteries promise low−cost and safe grid−scale energy storage, but face challenges due to sluggish interfacial Zn2+ transfer and H2O−induced ZnS disproportionation reactions at the interface of sulfur positive electrode. Here, we develop a hybrid electrolyte by introducing ZnI2 and organic N,N−dimethylformamide cosolvent, in which iodide species contribute to catalytic oxidation of ZnS, while N,N−dimethylformamide cosolvent can effectively facilitate sulfur reduction reaction. By combining operando Raman spectroscopy with non−destructive electrochemical impedance spectroscopy and theoretical calculations/simulations, it demonstrates that N,N−dimethylformamide molecules preferentially adsorb on sulfur electrode surface and strongly interact with Zn2+, thereby reconstructing interfacial electric double layer with H2O−poor inner Helmholtz plane and Zn2+−rich outer Helmholtz plane, which not only favors interfacial Zn2+ transfer to promote sulfur conversion reaction, but also suppresses H2O−induced side reactions. Through an additional constant voltage charge procedure to avoid I−/I3 − redox shuttle, the assembled Zn||S batteries can exhibit a voltage hysteresis of 0.326 V and a long−term cycling stability with a capacity fading of 0.034% per cycle after 1000 cycles at 2 C (i.e., 3.34 A g−1), even enabling a high areal capacity of 7.68 mAh cm−2 and a stable low−temperature performance with a specific capacity of 500 mAh g−1 at −10 °C.
Houman Kholafazad, Mahdiyeh Pazhuhi, Mohammad Hasanzadeh
et al.
Microneedles (MNs) have emerged as a cutting-edge sensing approach due to their enhanced surface area, improved sample penetration, localized detection, and potential for enhanced sensitivity. However, some MN manufacturing methods involve complex procedures, costly equipment, and non-biocompatible materials. Additionally, challenges in integrating MNs into existing technologies hinders their application in rapid and low-cost sensor technology. This study reports the development of innovative MNs fabricated using readily available cellulosic-based paper fibers, in which fibers from Whatman paper mixed with 1 % polyvinyl alcohol (PVA) were shaped using a polydimethylsiloxane (PDMS) mold. The MNs operate based on both physical penetration force and fluidic absorption via capillary action in the porous cellulosic matrix. The MNs exhibit low reagent and sample volume requirements along with flexibility and ease of penetration into samples, and filtration capabilities that allow efficient detection with minimal interference. The structure of MNs was investigated by field emission scanning electron microscopy (FE-SEM), revealing a conical shape with an average height of ∼750 µm and a diameter of ∼500 µm. The performance of the MN sensors was validated by colorimetric detection of heavy metals in fish, demonstrating linear ranges of 0.6 to 8 mg/L, 0.2 to 4 mg/L, and 0.3 to 6 mg/L for copper Cu(II), chromium Cr(VI), and nickel Ni(II), respectively. The colorimetric detection, combined with smartphone-based digital image analysis, exhibited lower limit of quantification (LLOQ) of 0.6, 0.2, and 0.3 mg/L for Cu(II), Cr(VI), and Ni(II), respectively, with no significant interference in the presence of potential interfering ions.
Stephen Price, Kiran Judd, Kyle Tsaknopoulos
et al.
Abstract Powder properties, particularly their morphology (which includes size, shape, surface roughness, etc.), play a critical role in the quality of cold spray additively manufactured materials. A change in feedstock powder morphology can impact flowability and deposition quality, deposition efficiency, and porosity. Image analysis can be used to quantify a powder’s morphology, but performing this analysis with manual visual inspection can be laborious and time-consuming. Alternatively, computer vision techniques have shown promise in automating powder morphology analysis, reducing the work and time required to quantify a powder’s morphology. However, the capabilities of these models are limited to the quality of their training data, which can be equally difficult and expensive to collect and annotate. Thus, this work presents DualSight, a novel multi-stage computer vision framework that improves metallic powder segmentation quality without requiring additional data or model training. With this framework, powder morphology can be extracted more accurately from scanning electron microscope images, enabling a more informed manufacturing process.