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Objective: To compare the influence of coronavirus disease 2019 (COVID-19) pandemic on the student reported outcomes among dental students reading/studying different courses offered in the only dental school in Malta. Materials and methods: An anonymous questionnaire consisting of 13 closedended and open-ended questions was sent to all students (n = 97) at the Faculty of Dental Surgery at the University of Malta. Emergent themes from open-ended questions were identified and tallied. Since data were classified as categorical ranks, nonparametric tests were used to compare variables among the different courses, years of study, preclinical/clinical students, and gender categories. Results: Dental technology students were significantly less stressed about contracting COVID-19 (P = 0.005) and regarding lack of preparation due to inability to physically go to the library (P = 0.019). Female students reported significantly more anxiety for the following factors: "feeling anxious all the time" (P = 0.033), "worried about contracting COVID-19'" (P=0.012), "worried that a family member may contract COVID-19'" (P = 0.048), "more anxious about exams this year because of the challenges we are facing" (P = 0.029), and "concern about losing manual dexterity skills" (P = 0.038). Qualitative data gathered show considerable stress reported by students regarding changes in examination processes and formats and lack of timely communication. Conclusion: Students were greatly affected by the COVID-19 pandemic and this caused fear of losing their manual dexterity skills, anxiety related to its consequences on their long-term plans, and anxiety related to the examinations. Dental schools in turn should adapt rapidly and customize changes that are specific to the individual student cohort and their stage of training. [ABSTRACT FROM AUTHOR]

The objective of the present study is to review the behavior of nanobubbles with hydrophobic and hydrophilic surfaces. In most of the situations, it is desirable that the water particles adhere to the surface, called hydrophilic surface and in some cases, the water particles move away from the surface, called hydrophobic surfaces. Nanobubbles owing to their extraordinary physio‐chemical properties find their application in waste water treatment, aquaculture, cultivation of yeast, oil refineries and agriculture, etc. This review article addresses the unpredictable behavior of nanobubbles with different surfaces according to previous studies and the various procedures to confirm the existence of such bubbles on those surfaces. [ABSTRACT FROM AUTHOR]

The objective of this present study is to examine the effect of nanobubbles on the physical properties improvement in the chosen water sample. So far, the research outcomes stated that the physical properties could be enhanced by addition of nanoparticles, but very few studies were performed with nanobubbles. The unique properties of nanobubbles (70–120 nanometers) explain their use in a wide range of engineering fields. Simple method for producing nanobubbles in a variety of aqueous solutions along with examples of their use is outlined in this work. Global environmental issues, including the deterioration and depletion of water supply are driving today's need for water treatment technology. As a solution, the use of micro‐ and nano‐bubble (MNB) technologies in wastewater treatment has evolved. This page discuss the fundamentals of water treatment research, including their stability of bubbles, manufacturing processes, and chemical and physical features. [ABSTRACT FROM AUTHOR]

Ordered and well‐interconnected 3D electrode nanostructures open up exciting perspectives in catalysis, sensing and energy harvesting. Here, highly ordered 3D nano‐sized Pt mesoporous structures based on the I‐Wrapped Package (I‐WP) architecture with 13.5 nm unit cell size, previously unreported for metal nanomaterials, are presented. The samples are synthetized by soft‐template electrodeposition, using the body‐centred cubic (BCC) lyotropic crystalline micellar phase of Pluronic F68 as the template. The specific surface area of the resulting Pt nanoarchitecture is 36 ± 13 m2 g−1. The oxygen reduction reaction kinetic current is 0.98 mA cm−2; the current density normalized by the electrochemical active surface area and the weight of deposited Pt are 0.92 mA cm−2 and 153.53 A g−1, respectively, showing superior properties than conventional Pt nanostructures produced by surfactant templates. These results suggest a nanostructure based on the topology of the I‐WP minimal surface, representing the first case at this length scale from a metallic material, opening up new research directions in fundamental physics based on predicted thermal and phononic properties for this topology. The water‐based template provides a chemical‐free, eco‐friendly route for ordered mesoporous conductive nanomaterials manufacturing, inspiring future trends in the field. [ABSTRACT FROM AUTHOR]

Dental infections are initiated by Streptococcus sanguinis and Streptococcus mutans through the biofilm formation. In streptococcal, the ComA enzyme catalyzes the first step to produce signalling molecules in quorum sensing that influence biofilm formation. Ocimum basilicum is one of the natural sources which is potential for antibacterial agent. This study is aimed to isolate phenolic compounds from O. basilicum leaves with antibacterial activity against oral pathogens by experimental and computational screening studies. Isolation of phenolic compounds 1–4 was carried out by bioactivity guided using column chromatography. Methylparaben (1), methyl protocatechuate (2), caffeic acid (3), and methyl caffeate (4) were characterized by 1D and 2D‐NMR. The antibacterial activity was tested by disk diffusion, microdilution methods. 1 (625 μg·mL−1) provided moderate activity, and 2 (156.3 μg·mL−1) provided strong activity against S. mutans. 3 (125 μg·mL−1) and 4 (312.5 μg·mL−1) provided strong activity against S. sanguinis. In addition, phenolic compounds and their derivatives were predicted against ComA using Autodock 4.0 tools. The activity correlated positively with in silico tests against ComA where 2 (−7.69 kcal·mol−1) had a stronger binding affinity than 1 (−6.64 kcal·mol−1). 3 (−6.86 kcal·mol−1) provided a slightly stronger bond strength than 4 (−6.65 kcal·mol−1). The strongest binding affinity of hydroxybenzoic acid derivatives is 3,5‐dihydroxybenzoic acid (−8.10 kcal·mol−1). In addition, the strongest binding affinity of hydroxycinnamic acid derivatives is chlorogenic acid (−9.16 kcal·mol−1). The pharmacokinetics were predicted by ADMET analysis, and methyl caffeate (4) showed the best potential as a drug compound. The conclusion is that phenolic compounds isolated from O. basilicum have potential as natural antibacterials. In silico tests also showed the relationship between the structure and activity by the presence of the hydroxyl group in hydroxybenzoic acid derivatives and the presence of an alkyl group in the unsaturated side chain in hydroxycinnamic acid derivatives. [ABSTRACT FROM AUTHOR]

The short history of research on Li−O2 batteries has seen a remarkable number of mechanistic U‐turns over the years. From the initial use of carbonate electrolytes, that were then found to be entirely unsuitable, to the belief that (su)peroxide was solely responsible for degradation, before the more reactive singlet oxygen was found to form, to the hypothesis that capacity depends on a competing surface/solution mechanism before a practically exclusive solution mechanism was identified. Herein, we argue for an ever‐fresh look at the reported data without bias towards supposedly established explanations. We explain how the latest findings on rate and capacity limits, as well as the origin of side reactions, are connected via the disproportionation (DISP) step in the (dis)charge mechanism. Therefrom, directions emerge for the design of electrolytes and mediators on how to suppress side reactions and to enable high rate and high reversible capacity. [ABSTRACT FROM AUTHOR]

Plate‐based single‐cell glycan and RNA sequencing (scGR‐seq) is previously developed to realize the integrated analysis of glycome and transcriptome in single cells. However, the sample size is limited to only a few hundred cells. Here, a droplet‐based scGR‐seq is developed to address this issue by adopting a 10x Chromium platform to simultaneously profile ten thousand cells' glycome and transcriptome in single cells. To establish droplet‐based scGR‐seq, a comparative analysis of two distinct cell lines is performed: pancreatic ductal adenocarcinoma cells and normal pancreatic duct cells. Droplet‐based scGR‐seq revealed distinct glycan profiles between the two cell lines that showed a strong correlation with the results obtained by flow cytometry. Next, droplet‐based scGR‐seq is applied to a more complex sample: peripheral blood mononuclear cells (PBMC) containing various immune cells. The method can systematically map the glycan signature for each immune cell in PBMC as well as glycan alterations by cell lineage. Prediction of the association between the glycan expression and the gene expression using regression analysis ultimately leads to the identification of a glycan epitope that impacts cellular functions. In conclusion, the droplet‐based scGR‐seq realizes the high‐throughput profiling of the distinct cellular glyco‐states in single cells. [ABSTRACT FROM AUTHOR]

The high overpotential of oxygen reduction reaction (ORR) prevents the wide commercialization of fuel cells and metal‐air batteries. To accelerate the reaction rate, porous electrocatalysts draw attention to obtain a higher specific surface area. However, the effect of micropores on ORR kinetics has not been understood because of the non‐uniform pore sizes, length, and tortuosity of practical electrocatalysts. In this study, we evaluate ORR activity in a micropore using platinum model electrodes with arrays of cylindrical pores with a uniform pore diameter of 1.8 nm. The model electrodes having pore lengths of 45, 100, and 380 nm are fabricated, and their ORR performances are examined by electrochemical measurements and numerical simulations in 0.1 mol dm−3 KOH aqueous solution. The intrinsic ORR activity of the micropore is successfully obtained with the electrode having a pore length of 45 nm, where oxygen transport resistance in the micropore has little effect on ORR. It is found that the intrinsic ORR activity of the micropore is higher than that of a planar Pt surface. X‐ray photoelectron spectroscopy and CO stripping voltammetry indicate a downshift of the d‐band center, which can be the origin of the high intrinsic ORR activity. [ABSTRACT FROM AUTHOR]

Nanoarchitectonics, a concept encompassing nanoscale microstructures and atomic arrangements in materials, enables the precise modification of materials for desired applications by controlling their physical and chemical properties, as well as surface charge or energy. Particularly in metal materials, where surface reactions play a critical role, nanoarchitecture becomes the most influential factor affecting activity, selectivity, and stability. Focusing on platinum‐group metals (PGMs) due to their inherently high efficiency in energy and environmental applications, this article provides a comprehensive review of synthetic methods for the morphological control of metal nanomaterials. The morphological control is classified into atomic arrangements in 0D, 1D, and 2D nanocrystals, as well as nanoporous structures, and the mechanisms of major reactions are covered in detail. Each chapter is supplemented with a table featuring several examples, facilitating the reader's understanding of the structural controls of PGMs. Finally, the article outlines future challenges in achieving novel metal nanoarchitecture. The hope is that this review provides valuable insights into the synthesis of PGM‐based nanomaterials and serves as a guide for designing and synthesizing innovative metal nanostructures for diverse applications. [ABSTRACT FROM AUTHOR]

Electronic paper (e‐paper) is a reflective display technology with unique advantages, such as bistability, low‐power consumption, and high ambient contrast ratio. These features make e‐paper a promising candidate for future Internet of Things applications. Among different technologies of e‐paper, electrophoretic display (EPD) is the most successful one for commercialization. However, the edge ghosting (also known as the fringing effect) still limits the performance of EPD. Herein, we established a model of particle dynamics of electrophoresis, simulated the edge ghosting of microcapsule EPD, analyzed the edge ghosting effect, and revealed the relationship between thicknesses, dielectric constants of the back binder layer, and the edge ghosting. Two EPD panels with different thicknesses of back binder layer were demonstrated, which verifies the accuracy of this simulation model. With the proposed model, many device mechanisms and product issues can be analyzed and illustrated, which is supposed to guide the researchers in optimizing the device structure design of EPD. [ABSTRACT FROM AUTHOR]

Development of porous electrode materials for high‐performance supercapacitors depends on the efficiency of pore utilization for charge storage. It remains an experimental and theoretical challenge to quantitatively relate the porous structure to charging dynamics. Here, based on a laminate‐electrode model of graphene‐based supercapacitors, we perform the equivalent circuit model to characterize the structure‐charging dynamics relationship of porous electrodes by coupling key structural features in a mathematical expression for the Resistor‐Capacitor (RC) time. This theoretical description is validated by direct numerical calculations of the Poisson–Nernst–Planck (PNP) equations. We discover that the charging dynamics of graphene‐based supercapacitors is dominated by the ion diffusion from the electrolyte region into the layered structure. The predicted charging time compares well with the experimental investigations reported in the literature on graphene‐based supercapacitors. Our work bridges nanoscopic transport behaviors with macroscopic devices, providing theoretical insights of the structure‐dependent ion transport in two‐dimensional materials‐based films for compact energy storage. [ABSTRACT FROM AUTHOR]

Tungsten is an important material for high‐temperature applications due to its high chemical and thermal stability. Its carbide, that is, tungsten carbide, is used in tool manufacturing because of its outstanding hardness and as a catalyst scaffold due to its morphology and large surface area. However, microstructuring, especially high‐resolution 3D microstructuring of both materials, is a complex and challenging process which suffers from slow speeds and requires expensive specialized equipment. Traditional subtractive machining methods, for example, milling, are often not feasible because of the hardness and brittleness of the materials. Commonly, tungsten and tungsten carbide are manufactured by powder metallurgy. However, these methods are very limited in the complexity and resolution of the produced components. Herein, tungsten ion‐containing organic–inorganic photoresins, which are patterned by two‐photon lithography (TPL) at micrometer resolution, are introduced. The printed structures are converted to tungsten or tungsten carbide by thermal debinding and reduction of the precursor or carbothermal reduction reaction, respectively. Using TPL, complex 3D tungsten and tungsten carbide structures are prepared with a resolution down to 2 and 7 μm, respectively. This new pathway of structuring tungsten and its carbide facilitates a broad range of applications from micromachining to metamaterials and catalysis. [ABSTRACT FROM AUTHOR]

Herein, an experimental investigation of an accordion‐like system with embedded magnetic inclusion is carried out. It is shown that the way that this structure deforms when subjected to an external magnetic field depends on the magnetic moment of the embedded magnets and the length of the arms. Stacking of the accordion‐like system leads to the formation of hexagonal honeycombs that can have a negative, zero, and positive Poisson's ratio. Variation in the configuration attained depends on the relative positioning of the magnetic inclusion and the applied magnetic field. In particular, one of the hexagonal honeycomb arrangements is able to switch between a conventional and a re‐entrant configuration upon the reversal of the external magnetic field. For all structures considered, the dimensions can be controlled through the external magnetic field, allowing for a high degree of turnability. Furthermore, their behavior can be altered in real time. The practical implications of the results are of interest since they indicate that these structures can be adopted in numerous applications, such in the design of scaffoldings for deployable structures, actuators, variable pored sieves, and sound proofing systems. [ABSTRACT FROM AUTHOR]

Finite element method (FEM) is considered as a powerful tool for predicting the mechanical behavior of complex structures. However, the commercially available numerical packages based on FEM are mainly limited to the evaluation of multiphysical properties at the continuum scale and are unable to accurately evaluate the response of nanomaterials since the dominant surface effects in nanoscale analysis are overlooked. In this study, our introduced numerical methodology not only incorporates the effects of surface residual stress and surface tensile stiffness based on the Gurtin–Murdoch surface elasticity but also takes into account the bending stiffness of nanosurfaces in the numerical analysis. The computational results reveal that the stress concentration in nanoporous metallic materials is affected by the void geometry and is enhanced by the surface bending stiffness. In addition, the effect of void geometrical parameters on the elastic properties of nanoporous metallic metamaterials with negative Poisson's ratio is studied and the mechanism of surface tensile/bending stiffness is revealed in detail. The results show that the surface bending stiffness increases the effective Young's modulus of nanoarchitected metallic materials with negative Poisson's ratio and randomly distributed nanopores. [ABSTRACT FROM AUTHOR]

Electrohydrodynamic jet (e‐jet) printing technology overcomes some limitations such as the viscosity and resolution of the traditional ink‐jet printing by breaking surface tension of the droplets with high voltage and the formation of Taylor cone. The technique is becoming more and more popular because it can be widely used in the fabrication of the conductive line of electronics, electrode, transistor, sensor, and other electronics as microelectrode, microlen, and heater. This review provides insight into the effect of the influence factors such as voltage, speed, nozzle, jetting ink characteristics, and the representative conductive materials of the ink as metal nanoparticles (NPs) and carbon materials, or organic conductive polymers on the fabrication of the different electronics by the e‐jet printing technology. Specially, the characteristics of different resultant electronics are compared and the possible mechanisms are analyzed. Finally, the challenge and development trend of the e‐jet printing technology are discussed, which will shed a light on the fabrication of the next‐generation flexible electronics with better performance. [ABSTRACT FROM AUTHOR]

The present paper describes an experimental study on mechanical properties of additively manufactured anti‐tetrachiral auxetic structures under shear and flexural loading. Specimens of ABS material are fabricated using material extrusion technique of additive manufacturing. Experiments are planned using central composite design method. Three process factors, namely, slice thickness, print speed, and contour width, are considered to study their influence on modulus, strength, and specific energy absorption (SEA) of fabricated structures. To perform shear testing on specimen, a novel fixture is designed and fabricated. Flexural properties are measured using three‐point bending test on universal testing machine. It is found that all three process factors significantly affect modulus, strength, and SEA of the structure under shear and flexural loading. Mechanical properties improve with increase in slice thickness, print speed, and contour width. Regression models are developed to predict the response characteristics. In addition, optimized values of process factors are determined to maximize the mechanical properties of the structure. [ABSTRACT FROM AUTHOR]

Shape‐morphing capabilities of metamaterials can be expanded by developing approaches that enable the integration of different types of cellular structures. Herein, a rational material design process is presented that fits together auxetic (anti‐tetrachiral) and non‐auxetic (the novel nodal honeycomb) lattice structures with a shared grid of nodes to obtain desired values of Poisson's ratios and Young's moduli. Through this scheme, deformation properties can be easily set piece by piece and 3D printed in useful combinations. For example, such nodally integrated tubular lattice structures undergo worm‐like peristalsis or snake‐like undulations that result in faster speeds than the monophasic counterpart in narrow channels and in wider channels, respectively. In a certain scenario, the worm‐like hybrid metamaterial structure traverses between confined spaces that are otherwise impassable for the isotropic variant. These deformation mechanisms allow us to design shape‐morphing structures into customizable soft robot skins that have improved performance in confined spaces. The presented analytical material design approach can make metamaterials more accessible for applications not only in soft robotics but also in medical devices or consumer products. [ABSTRACT FROM AUTHOR]

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The use of nanoparticles and nanostructured electrodes are abundant in electrocatalysis. These nanometric systems contain elements of nanoconfinement in different degrees, depending on the geometry, which can have a much greater effect on the activity and selectivity than often considered. In this Review, we firstly identify the systems containing different degrees of nanoconfinement and how they can affect the activity and selectivity of electrocatalytic reactions. Then we follow with a fundamental understanding of how electrochemistry and electrocatalysis are affected by nanoconfinement, which is beginning to be uncovered, thanks to the development of new, atomically precise manufacturing and fabrication techniques as well as advances in theoretical modeling. The aim of this Review is to help us look beyond using nanostructuring as just a way to increase surface area, but also as a way to break the scaling relations imposed on electrocatalysis by thermodynamics. [ABSTRACT FROM AUTHOR]

In the present work, an experimental investigation is performed to study the influence of process parameters on mechanical properties of tetra‐anti‐chiral auxetic structures manufactured by material extrusion (ME) technique of additive manufacturing (AM). Process parameters namely layer height, print speed, and print temperature are considered, while responses are compressive strength (σ), modulus (E), and specific energy absorption (SEA). Specimens of acrylonitrile‐butadiene‐styrene (ABS) polymer are fabricated and then tested under compressive loading. From the experimental results, it is observed that all process parameters significantly influence the mechanical properties of the structure. Scanning electron microscope (SEM) is used to study microstructural defects of the tested specimen. To maximize the responses, optimization of process parameter is performed using desirability function approach. Regressive models are developed to predict the mechanical properties. [ABSTRACT FROM AUTHOR]

Toxicity characteristic leaching procedure (TCLP) leached biochar is studied for adsorption of methylene blue (MB). Rice straw biochar obtained from slow pyrolysis at 400, 500, and 600 °C, respectively, is TCLP leached to furnish leached biochar, BL4, BL5, and BL6. The leached biochar BL4–6 have been characterized for pH, CHN analysis, ash, zeta potential, surface area morphology and functional groups. Batch adsorption studies are optimized for pH (3–9), adsorbent dose (0.5–4 g L−1), and initial MB concentration (20–135 mg L−1). Nonlinear fitting to Langmuir, Freundlich, and Redlich‐Peterson adsorption isotherm with due statistical treatment and error function analysis is carried out. Leached biochar, BL4, BL5, and BL6, is characterized by the dominance of carboxylic acid, lactone, and phenols moieties, respectively. The MB adsorption on leached biochar exhibits maximum adsorption of 26.87, 51.34, and 18.83 mg g−1 for BL4, BL5, and BL6, respectively. The underlying mechanism for adsorption of MB using BL5, is characterized by non‐ionic lactone ring opening in presence of MB under alkaline conditions that is supported by X‐ray photoelectron spectroscopy(XPS) and Fourier transformed infrared spectroscopy (FTIR) studies. Desorption of MB and regeneration from BL5 is studied with methanol and 0.1 m HCl as stripping solvent for four cycles. Recovery of MB is better with methanol in comparison to 0.1 m HCl. [ABSTRACT FROM AUTHOR]

Auxetics display the anomalous property of expanding laterally when uniaxially stretched, that is, a negative Poisson's ratio, a property that arises from 1) the presence of specific geometric features within the nano/macrostructure of the material and 2) amenable deformations in response to the applied stimulus. Herein, how ancient symmetrical esthetic artifacts have been transformed to functional auxetics through mechanisms that have ripened the field of "mechanical metamaterials" and "architected materials" in the last decades is explored. In particular, the important role and various implementations, both in 2D and 3D, of "rotating rigid units," which range from "rotating squares" to much more complex renditions at various scales of structure, are looked at. The role of rotating rigid units to generate negative thermal expansion and negative compressibility is also delved into. [ABSTRACT FROM AUTHOR]

This study puts forward a method of reconstruction of the suboptimal isotropic truss microstructures for the known distribution of Young's modulus and Poisson's ratio predicted by the Isotropic Material Design (IMD) method of minimizing the compliance (maximizing the stiffness) of a 2D elastic body. The varying underlying microstructures corresponding to the optimal designs are recovered by matching the values of the optimal elastic moduli with the values of the effective moduli of the representative volume elements (RVE) computed by the asymptotic homogenization method. The used hexagonal shape of the RVE with its specific internal symmetry provides the assumed isotropy of the periodic body. Hexagonal periodic cells are made up of 3 or 12 pin‐jointed families of bars with different stiffness characteristics. Combining these families into two or three groups with identical bar stiffnesses in a group allows for the exact reproduction of Poisson's ratio for each point of the body. The ability to model an auxetic behavior within the subdomains where the optimal Poisson's ratio assumes negative values is also shown. The effective value of the Young's modulus is scaled independently of the value of the effective Poisson's ratio by selecting the cross section of the bars in the group. [ABSTRACT FROM AUTHOR]

An analytical model for a general Star‐4 system, having different ligament lengths, angles, and ligament thickness, is derived using Castigliano's second theorem. The analytical model is validated through finite element analysis and experimental work. The results obtained show that, depending on the parameters used, the general Star‐4 system can show a wide range of Poisson's ratios with the potential of obtaining giant negative Poisson's ratios (in the order of −8) for certain conformations. The wide range of Poisson's ratio is explained in terms of the different geometrical conformations obtainable by the system, where the star‐ligaments can also describe rhombi, irregular octagons, rectangles, and accordion‐like systems, together with changes in the deformation mechanism due to variations in parameters. For example, if one set of star‐ligaments is much thicker than the other, the deformation of the star would be akin to that of the hexagonal reentrant unit cell. [ABSTRACT FROM AUTHOR]

Boron arsenate (BAsO4) is a β‐cristobalite‐like material, which crystallizes in the I4¯ space group. However, unlike β‐cristobalite itself, BAsO4 is well characterized and known to be stable and at ambient conditions. This work presents the results of extensive density functional theory (DFT)‐based simulations aimed at elucidating the nanoscale deformations that such crystals undergo when subjected to uniaxial tensile and compressive loads along their crystallographic [001] c‐direction. It is shown that such uniaxial loading results primarily in intra‐tetrahedral deformations rather than their tilting/rotations (which causes the auxeticity in the (001) plane). Through their analysis in isolation from other modes of deformation, this study gives a much better insight into such intra‐tetrahedral deformations and helps explain better the cause of the measured negative linear compressibility in the c‐direction at elevated pressures, which recently has been attributed to a "demi wine‐rack" mechanism caused by the same intra‐tetrahedral deformations. [ABSTRACT FROM AUTHOR]

Phenylacetylene as an impurity in styrene is poisonous to catalysts for styrene polymerization in the production of polystyrene plastics. The selective hydrogenation of phenylacetylene to styrene is an industrially promising route to overcome this challenge yet lacks cost‐effective catalysts to prevent the overhydrogenation of styrene to ethylbenzene. In this work, we report an efficient and robust copper‐decorated Rh/TiO2 catalyst for the selective hydrogenation of phenylacetylene to styrene. By optimizing the copper coverage on TiO2 supported Rh nanoparticles, we achieved a selectivity of 83% towards styrene formation at a phenylacetylene conversion of 93%. The appropriate Cu coverage is found to modulate the electronic states of surface Rh atoms and changes the Rh exposed active sites, weakening the binding strength of alkene and hydrogen intermediates on Rh and thus mitigating the overhydrogenation and enhancing the selectivity for styrene generation. This work offers insights on the rational design of efficient Rh‐based bimetallic catalysts for selective hydrogenation of phenylacetylene to styrene. [ABSTRACT FROM AUTHOR]

The development of heterogeneous catalysts for asymmetric synthesis is one of the most challenging topics in chemistry, as it allows obtaining enantiomerically pure compounds. Recently, metal layers incorporating molecular chiral cavities, obtained by electroreduction of a metal source in the simultaneous presence of a non‐ionic surfactant and asymmetric molecules, have been proposed for a wide range of applications, including enantioselective electroanalysis and electrosynthesis, as well as chiral separation. In contrast to this previous work, solely based on electrochemical phenomena, herein we designed and employed nanostructured chiral encoded Pt−Ir alloys, supported on high surface area nickel foams, as heterogeneous catalysts for the asymmetric hydrogenation of aromatic ketones. Fine‐tuning the experimental conditions allows achieving very high enantioselectivity (>80%), combined with improved catalyst stability. [ABSTRACT FROM AUTHOR]

Mechanical metamaterials with negative Poisson's ratio (NPR) effect possess important practical applications in aerospace, nanotechnology, and other fields. The microstructure and its deformation mode directly determine the NPR ability and mechanical performance of auxetic metamaterials. Herein, inspired by the double‐negative‐index ceramic aerogels, a novel NPR structural model is proposed in which symmetric reentrant oblique ligaments and short transversal ligaments constitute the main framework inside a square, which is different from the traditional reentrant structure due to the hyperbolic‐like skeleton and deformation modes. The influence of structural parameters on the NPR effect is investigated using the Timoshenko beam model and finite element simulations. The structural model is then extended to design multiple reentrant structures and assembled structures, respectively. The multiple reentrant structures include multiple pairs of symmetrically hyperbolic‐like skeletons, and the distribution of horizontal ligaments can be regulated to achieve a better NPR effect. For assembled structures under compression, the local rotational deformation and buckling result in structural instability, demonstrated by inflection points in the NPR curves. Moreover, one special assembled structure is found for which there is a linear relationship between the compressive strain and NPR value. The insights should be significant for designing mechanical metamaterials with the NPR effect. [ABSTRACT FROM AUTHOR]

The electrochemical preparation of a novel composite glassy carbon/betaine/platinum (GC/BT/Pt) electrode with meso‐ nano Pt globules dispersed on the outer surface and betaine, as intermediate layer, electrodeposited on GC by Cyclic Voltammetry (CV) or Pulsed Potential (PP) techniques, is presented. Surface analysis by Scanning Electron Microscopy (SEM) and X‐ray Photoelectron Spectroscopy (XPS) confirms the strategic role of grafted betaine in modulating GC/BT‐ interaction sites and the range of potentials for adequate platinum CV electrodeposition. The GC/BT/Pt performance, concerning sensitivity, linearity, work potentials and repeatability tests with Flow Injection Analysis (FIA), was ascertained for the detection of vitamins B1 and B6. [ABSTRACT FROM AUTHOR]

The future of fuel cells technology will require porous or very organized multicomponent catalytic layers that can be prepared by thin film growth methods. Reducing the cost of these energy systems will also necessitate that the catalytic layers be binderless and contain low amount of the noble catalyst until efficient non‐noble catalysts are discovered. To address these requirements, monolayered SnO2, Pt and Rh, bi‐layered Pt/SnO2 and Rh/Pt and novel tri‐layered Rh (various thicknesses)/Pt/SnO2 catalysts supported on carbon paper are synthesized at room temperature via pulsed laser deposition. The catalysts are evaluated for their catalytic performance for the ethanol oxidation reaction (EOR), durability, and tolerance to CO‐poisoning. All the Rh/Pt/SnO2 catalysts produce high CO‐tolerance, high EOR catalytic activity and durability as compared to pure Pt. The possible mechanism by which SnO2 and Rh atoms enhanced the performance is also considered herein, and an optimal Rh/Pt/SnO2 structure having a 10 nm thickness of Rh layer offers a promising anode catalyst for ethanol fuel cells. Notably, the onset potential for CO oxidation is extraordinarily 430 mV lower than on Pt, and the mass activity for EOR and durability are 2.25 and 4.2 times higher than on Pt. [ABSTRACT FROM AUTHOR]

Atomic force microscopy (AFM) is a powerful tool to investigate interaction forces at the micro and nanoscale. Cantilever stiffness, dimensions and geometry of the tip can be chosen according to the requirements of the specific application, in terms of spatial resolution and force sensitivity. Colloidal probes (CPs), obtained by attaching a spherical particle to a tipless (TL) cantilever, offer several advantages for accurate force measurements: tunable and well‐characterisable radius; higher averaging capabilities (at the expense of spatial resolution) and sensitivity to weak interactions; a well‐defined interaction geometry (sphere on flat), which allows accurate and reliable data fitting by means of analytical models. The dynamics of standard AFM probes has been widely investigated, and protocols have been developed for the calibration of the cantilever spring constant. Nevertheless, the dynamics of CPs, and in particular of large CPs, with radius well above 10 μm and mass comparable, or larger, than the cantilever mass, is at present still poorly characterized. Here we describe the fabrication and calibration of (large) CPs. We describe and discuss the peculiar dynamical behaviour of CPs, and present an alternative protocol for the accurate calibration of the spring constant. [ABSTRACT FROM AUTHOR]

This article presents the review of the research papers concerning nanobubble generation. In main section of this article, numerous methods of nanobubble generation have been discussed pinpointing the differences in results obtained in similar experimental setups. Different generation methods have been tabularized to present the composition of phases, the diameter of generated bubbles as well as the commentary concerning discrepancies within one method. The number of nanobubble applications in environmental processes is increasing in the last year; however, the thorough investigation of their generation methods is not covered in literature. This review article is gathering knowledge about nanobubble generation methods and is comparing results obtained by different research teams. It should lay foundation for future research concerning nanobubbles, what will lead to increasing the efficiency of various environmental processes, including wastewater flotation, metal recovery, and soil and groundwater remediation. [ABSTRACT FROM AUTHOR]

The flexing of the ligaments at the edge of a finite hexagonal honeycomb array is studied using analytical and numerical methods. It is shown that when compressed axially, the ligaments on the border of a hexagonal honeycomb array bend outwardly in contrast to the interior ligaments that bend to a negligible extent, if at all. This boundary effect reduces the overall auxeticity of re‐entrant hexagonal honeycombs. Analytical expressions that account for the edge effects on the Poisson's ratio and Young's modulus are obtained using Castigliano's second theorem. These are then tested against numerical simulations showing good agreement at least for the values of the parameters used. Additional investigations indicate that the use of a larger ligament thickness for the ligaments residing on the border of the system mitigates this edge effect on the Poisson's ratio. [ABSTRACT FROM AUTHOR]

The mechanical properties of the anti‐tetrachiral structure having the thickness of the ligament changing symmetrically around the center are investigated using analytical and numerical methods. For the purpose of deriving a theoretical model, the Euler–Bernoulli beam theory is used to determine the relation among the acting moment, the angle of rotation of the nodes, and the bending energy stored. Analysis of the results indicates that a change in geometry has a minor effect on Poisson's ratio, if any at all; however, it can result in relatively large changes in Young's modulus. Hence, it is shown that the mechanical properties can be altered selectively by adjusting the geometric features of chiral structures. The indications of the analytical model are validated using numerical methods for different values of the geometric parameters and are found to be in good agreement. In the process, it is shown that there are regions of the parameter space where the mechanical properties of the anti‐tetrachiral are insensitive to variations in certain geometric dimensions. [ABSTRACT FROM AUTHOR]

Auxetic materials behave unconventionally under deformation, which enhances material properties such as resistance to indentation and energy absorption. Auxetics, therefore, have the potential to enhance sporting protective equipment. Herein, finite element modeling, additive manufacturing and impact testing of three auxetic lattices, and a conventional equivalent, with a view to advance auxetic implementation within sports equipment, are explored. The lattices are modeled and impacts are simulated between 1 and 5 J, for flat and hemispherical drop hammers. Simulation outputs including peak impact force, impact duration, maximum axial strain, and Poisson's ratio are compared with experimental results from equivalent impact energies on additively manufactured lattices, using an instrumented drop tower and a high‐speed camera. The simulation and experimental results show broad agreement for all lattices and scenarios, demonstrated by comparative force versus time plots and maximum compression images. The benefits of developing and validating finite element models of three auxetic lattices (and the conventional honeycomb lattice) under various impact scenarios, as a process, are discussed, including material characterization of an exemplar thermoplastic polyurethane. Future work can use the models to further investigate auxetic lattices, selecting and tailoring candidates to further explore their potential application to specific personal protective equipment in sport. [ABSTRACT FROM AUTHOR]

Two of the most prominent 2D auxetic mechanisms, namely, the rotating rigid unit and the chiral systems, work, at least partly, by converting linear to rotational motion. This property can be harnessed by introducing a system that can convert back the rotational motion to a linear displacement so as to induce an expansion or a compression in the out‐of‐plane direction. The push drill mechanism offers an effective way of providing this capability. It is, hence, possible to couple 2D rotating rigid unit or chiral structures to the push drill mechanism to create novel 3D auxetic structures. The resultant Poisson's ratio in the out‐of‐plane direction can be both negative and positive depending on the connectivity. Herein, the concept is illustrated with the use of rotating squares. An analytical model is derived to determine the parameters on which Poisson's ratio and Young's moduli depend. Subsequently, the analytical results are compared with those obtained from experimental testing of different sample structures with the two showing good agreement. Further considerations indicate that it is possible to design 2D and 3D auxetic systems with the push drill as the only deformation mechanism. [ABSTRACT FROM AUTHOR]

The concept of encoding molecular information in bulk metals has been proposed over the past decade. The structure of various types of molecules, including enantiomers, can be imprinted in achiral substrates. Typically, to encode metals with chiral information, several approaches, based on chemical and electrochemical concepts, can be used. In this Minireview, recent achievements with respect to the development of such materials are discussed, including the entrapment of chiral biomolecules in metals, the chiral imprinting of metals, as well as the combination of imprinting with nanostructuring. The features and potential applications of these designer materials, such as chirooptical properties, enantioselective adsorption and separation, as well as their use for asymmetric synthesis will be presented. This will illustrate that the development of molecularly encoded metal structures opens up very interesting perspectives, especially in the frame of chiral technologies. [ABSTRACT FROM AUTHOR]

The processing of pure tungsten encounters a substantial challenge due to its high melting point and intrinsic brittleness. Selective laser melting (SLM) technique is gaining popularity and offers an excellent processing approach for refractory metals. Herein, dense pure tungsten specimens are produced by optimizing SLM processing parameters. The mechanical property of the SLM‐produced tungsten with an ultimate compressive strength of about 1200 MPa, which is obviously superior to that reported in other literature, is achieved. The increased laser energy input is instrumental in raising density and surface roughness of tungsten specimens. Interestingly, additional remelting of processed layers during SLM improves the surface quality and the microstructure and achieves the highest relative density (98.4% ± 0.5%). After laser remelting, the surface roughness is reduced by 28% and a large number of fine grains are obtained. The flow of fluids caused by remelting plays a decisive role in the formation of fine grains and the defect level. Therefore, these findings offer a new insight into SLM of pure tungsten. [ABSTRACT FROM AUTHOR]

In this paper, a slip length model is proposed to analyze the enhanced flow based on the Hagen–Poiseuille equation. The model considers the multimechanisms including wall-water molecular interactions, pore dimensions, fractal roughness, and temperature. The increasing wall-water interactions result in the greater slip length and flow enhancement factor. The increased temperature enhances the kinetic energy of water molecules that leads to great surface diffusion coefficient and small work of adhesion. The wall roughness can decrease the slip length and flow enhancement factor in hydrophilic nanopores. This work studies the effects of multimechanisms on slip length and flow enhancement factor theoretically, which can accurately describe the liquid flow in nanopores. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting is a crucially important process for energy conversion and storage. In this context, we report the synthesis of hierarchical multiporous nickel nanosheets obtained by a templated two‐step electrodeposition of nickel in the presence of silica beads and an assembly of nonionic surfactant in order to generate a combined macro‐ and mesoporous structure. Interestingly, the synergistic effect of these highly ordered meso‐ and macroporous structures promotes the catalytic performance for oxygen evolution reaction with one order of magnitude higher current densities and a better stability of the electrodes compared to flat nickel or electrodes having a single type of porosity. This example illustrates a promising strategy for the rational design of high‐performance porous metals, not only in the frame of water electrolysis, but also for other electrocatalytic applications. [ABSTRACT FROM AUTHOR]