The ability of superhydrophobic surfaces to stay dry, self-clean and avoid biofouling is attractive for applications in biotechnology, medicine and heat transfer
. Water droplets that contact these ...surfaces must have large apparent contact angles (greater than 150 degrees) and small roll-off angles (less than 10 degrees). This can be realized for surfaces that have low-surface-energy chemistry and micro- or nanoscale surface roughness, minimizing contact between the liquid and the solid surface
. However, rough surfaces-for which only a small fraction of the overall area is in contact with the liquid-experience high local pressures under mechanical load, making them fragile and highly susceptible to abrasion
. Additionally, abrasion exposes underlying materials and may change the local nature of the surface from hydrophobic to hydrophilic
, resulting in the pinning of water droplets to the surface. It has therefore been assumed that mechanical robustness and water repellency are mutually exclusive surface properties. Here we show that robust superhydrophobicity can be realized by structuring surfaces at two different length scales, with a nanostructure design to provide water repellency and a microstructure design to provide durability. The microstructure is an interconnected surface frame containing 'pockets' that house highly water-repellent and mechanically fragile nanostructures. This surface frame acts as 'armour', preventing the removal of the nanostructures by abradants that are larger than the frame size. We apply this strategy to various substrates-including silicon, ceramic, metal and transparent glass-and show that the water repellency of the resulting superhydrophobic surfaces is preserved even after abrasion by sandpaper and by a sharp steel blade. We suggest that this transparent, mechanically robust, self-cleaning glass could help to negate the dust-contamination issue that leads to a loss of efficiency in solar cells. Our design strategy could also guide the development of other materials that need to retain effective self-cleaning, anti-fouling or heat-transfer abilities in harsh operating environments.
The hydrothermal technique provides an excellent possibility for processing of advanced materials whether it is bulk single crystals, or fine particles, or nanoparticles. The advantages of ...hydrothermal technology have been discussed in comparison with the conventional methods of materials processing. The current trends in hydrothermal materials processing has been described in relation to the concept of soft solution processing, as a single-step low energy consuming fabrication technique. Also some recent developments in multi-energy processing of materials such as microwave-hydrothermal, mechanochemical-hydrothermal, electrochemical-hydrothermal, sonar-hydrothermal, etc. have been discussed. An overview of the past, present and future perspective of hydrothermal technology as a tool to fabricate advanced materials has been given with appropriate examples.
Core-shell nanomaterials (CSNs) have achieved huge popularity due to multifunctional properties achieved by manipulation of core or shell materials. This review highlights recent development in CSNs ...based sensing devices such as electrochemical sensors, optical sensors, wearable sensing devices, and gas adsorptive sensors, which find potential applications in numerous fields ranging from industrial, clinical, biological, environmental and food analysis. Furthermore, flexible and high deformation monitoring piezoresistive wearable sensors based on CSNs are found to be promising for monitoring of human physiological parameters and other body movements. Various synthetic strategies with a modern classification approach are explained with suitable examples. Several interesting properties of CSNs including high surface area, high conductivities, and high ion transport properties with biocompatibilities are best suited for developing ideal sensing devices. Future research directions with motivated research are highlighted in the conclusion part.
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•CSNs: Emerging materials for sensing and biosensing.•Various synthesis strategies are described.•CSNs based wearable sensors: A new generation sensing devices.•CSNs based electrochemical sensors for environmental and agriculture monitoring.•Improvement in sensing performance over conventional materials was observed.
Two-dimensional (2D) materials
and the associated van der Waals (vdW) heterostructures
have provided great flexibility for integrating distinct atomic layers beyond the traditional limits of ...lattice-matching requirements, through layer-by-layer mechanical restacking or sequential synthesis. However, the 2D vdW heterostructures explored so far have been usually limited to relatively simple heterostructures with a small number of blocks
. The preparation of high-order vdW superlattices with larger number of alternating units is exponentially more difficult, owing to the limited yield and material damage associated with each sequential restacking or synthesis step
. Here we report a straightforward approach to realizing high-order vdW superlattices by rolling up vdW heterostructures. We show that a capillary-force-driven rolling-up process can be used to delaminate synthetic SnS
/WSe
vdW heterostructures from the growth substrate and produce SnS
/WSe
roll-ups with alternating monolayers of WSe
and SnS
, thus forming high-order SnS
/WSe
vdW superlattices. The formation of these superlattices modulates the electronic band structure and the dimensionality, resulting in a transition of the transport characteristics from semiconducting to metallic, from 2D to one-dimensional (1D), with an angle-dependent linear magnetoresistance. This strategy can be extended to create diverse 2D/2D vdW superlattices, more complex 2D/2D/2D vdW superlattices, and beyond-2D materials, including three-dimensional (3D) thin-film materials and 1D nanowires, to generate mixed-dimensional vdW superlattices, such as 3D/2D, 3D/2D/2D, 1D/2D and 1D/3D/2D vdW superlattices. This study demonstrates a general approach to producing high-order vdW superlattices with widely variable material compositions, dimensions, chirality and topology, and defines a rich material platform for both fundamental studies and technological applications.
The production of biochar from sewage sludge pyrolysis is a promising approach to transform the waste resultant from wastewater treatment plants (WWTPs) to a potential adsorbent. The current review ...provides an up-to-date review regarding important aspects of sewage sludge pyrolysis, highlighting the process that results major solid fraction (biochar), as high-value product. Further, the physio-chemical characteristics of sewage-sludge derived biochar such as the elemental composition, specific surface area, pore size and volume, the functional groups, surface morphology and heavy metal content are discussed. Recent progress on adsorption of metals, emerging pollutants, dyes, nutrients and oil are discussed and the results are examined. The sewage sludge-derived biochar is a promising material that can make significant contributions on pollutants removal from water by adsorption and additional benefit of the management of huge volume of sewage. Considering all these aspects, this field of research still needs more attention from the researchers in the direction of the technological features and sustainability aspects.
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•Sewage sludge utilized as potential precursor for biochar production.•Pyrolysis approach and process conditions for biochar production.•Characterization aspects of sewage-sludge derived biochar.•Mechanisms associated with the adsorptive removal of water pollutants.
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With a continuously increasing aging population and the improvement of living standards, large demands of biomaterials are expected for a long time to come. Further development of ...novel biomaterials, that are much safer and of much higher quality, in terms of both biomedical and mechanical properties, are therefore of great interest for both the research scientists and clinical surgeons. Compared with the conventional crystalline metallic counterparts, bulk metallic glasses have unique amorphous structures, and thus exhibit higher strength, lower Young’s modulus, improved wear resistance, good fatigue endurance, and excellent corrosion resistance. For this purpose, bulk metallic glasses (BMGs) have recently attracted much attention for biomedical applications. This review discusses and summarizes the recent developments and advances of bulk metallic glasses, including Ti-based, Zr-based, Fe-based, Mg-based, Zn-based, Ca-based and Sr-based alloying systems for biomedical applications. Future research directions will move towards overcoming the brittleness, increasing the glass forming ability (GFA) thus obtaining corresponding bulk metallic glasses with larger sizes, removing/reducing toxic elements, and surface modifications.
Bulk metallic glasses (BMGs), also known as amorphous alloys or liquid metals, are relative newcomers in the field of biomaterials. They have gained increasing attention during the past decades, as they exhibit an excellent combination of properties and processing capabilities desired for versatile biomedical implant applications. The present work reviewed the recent developments and advances of biomedical BMGs, including Ti-based, Zr-based, Fe-based, Mg-based, Zn-based, Ca-based and Sr-based BMG alloying systems. Besides, the critical analysis and in-depth discussion on the current status, challenge and future development of biomedical BMGs are included. The possible solution to the BMG size limitation, the brittleness of BMGs has been proposed.
Metallopolymers have emerged as a new type of advanced materials for multiple applications, involving nanoscience, energy storage and conversion, catalysis, as well as biomedicine. Metal components ...play a significant role in the performances and functionalities of metallopolymers, and can endow metallopolymers with unique optical, magnetic, electronic, catalytic and redox characteristics. In addition, the polymer backbones also provide good mechanical, processing and soluble properties to broaden the practicability of metallopolymers. Metal centers can be incorporated into polymer main chain, side chain or network to produce various metallopolymers. The current research interests are to design and develop functional metallopolymers with specific structures and required properties for valuable applications. This review focuses on recent advances of metallopolymers for multiple applications, such as self-assembly, biomaterials, optoelectronic materials, catalysis, smart gels and microgels, and ion-exchange membranes. This review is expected to give some insight into metallopolymers for developing the desired functional materials.
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This paper presents an investigation about fatigue behaviour of an aluminium triply periodic minimal surface lattice structures, printed with Selective Laser Melting. Aim of the paper is to ...experimentally characterize constant and variable amplitude fatigue strength and to assess if current methodologies for predicting random fatigue strength of solid materials can be extended also to lattice structures, in a homogenized setting. The investigation is complemented by a detailed analysis of samples fracture surface, corroborated by numerical analyses, and a comprehensive discussion on the evolution of the damage observed in the experiments.
•Fatigue strength of a TPMS lattice structure manufactures in AlSi10Mg by L-PBF.•Constant amplitude fatigue characterization at different stress ratios.•Random fatigue characterization at different RMS levels.•Detailed characterization of the failure mechanisms.•Fatigue life under variable amplitude well predicted by the Miner’s rule.
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•Among the hazardous VOCs, formaldehyde (FA) is well-known for its carcinogenic potential.•In this review, the adsorption capacities of FA by various advanced materials are ...explored.•Performance of diverse materials was assessed on a parallel basis using partition coefficients.•This study provides a useful guide to future researches in development of advanced materials.
As formaldehyde (FA) is well-known for its carcinogenic potential, various techniques for its removal have been developed based on recovery (e.g., adsorption/absorption and condensation) or destructive treatment (e.g., incineration and thermal/ catalytic oxidation). Among them, adsorption has been one of the most preferable options due to its low price and simplicity. In this review, we summarize state-of-the-art knowledge about adsorption mechanisms with respect to its key controlling variables (e.g., surface chemical properties of adsorbent, temperature, and relative humidity) and adsorption performance of materials with particular emphasis on advanced materials (e.g., carbon nanotubes, metal-organic frameworks, graphene oxides, and porous organic polymers) and their modified forms in comparison with conventional sorbents (e.g., AC and zeolite). However, it is yet difficult to assess the adsorption capacity of each material on a parallel basis because adsorption experiments of each material were conducted under different conditions (e.g., large differences in the initial loading concentrations). The partition coefficient (PC) was employed for evaluating adsorption performance between different materials at an equivalent level to overcome the limitation based on adsorption capacity concept. For instance, among the list of the surveyed materials, the highest PC was recorded by γ-CD-MOF-K (31.2 mol kg−1 Pa−1). This study should offer valuable insights into the selection and development of outstanding materials for the sorptive removal of FA.
Soft materials capable of transforming between three-dimensional (3D) shapes in response to stimuli such as light, heat, solvent, electric and magnetic fields have applications in diverse areas such ...as flexible electronics
, soft robotics
and biomedicine
. In particular, magnetic fields offer a safe and effective manipulation method for biomedical applications, which typically require remote actuation in enclosed and confined spaces
. With advances in magnetic field control
, magnetically responsive soft materials have also evolved from embedding discrete magnets
or incorporating magnetic particles
into soft compounds to generating nonuniform magnetization profiles in polymeric sheets
. Here we report 3D printing of programmed ferromagnetic domains in soft materials that enable fast transformations between complex 3D shapes via magnetic actuation. Our approach is based on direct ink writing
of an elastomer composite containing ferromagnetic microparticles. By applying a magnetic field to the dispensing nozzle while printing
, we reorient particles along the applied field to impart patterned magnetic polarity to printed filaments. This method allows us to program ferromagnetic domains in complex 3D-printed soft materials, enabling a set of previously inaccessible modes of transformation, such as remotely controlled auxetic behaviours of mechanical metamaterials with negative Poisson's ratios. The actuation speed and power density of our printed soft materials with programmed ferromagnetic domains are orders of magnitude greater than existing 3D-printed active materials. We further demonstrate diverse functions derived from complex shape changes, including reconfigurable soft electronics, a mechanical metamaterial that can jump and a soft robot that crawls, rolls, catches fast-moving objects and transports a pharmaceutical dose.
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