Macroscopic Level Research Articles

Hydrogel‐Based Macroscopic Click Chemistry

AbstractThe click reaction has found good utility across various fields due to the characteristics of high efficiency, atom economy, simple and mild reaction conditions. Click chemistry is usually utilized for connecting components of microscopic level, while it is still unable for joining macroscopic building blocks. Materials consisting of macroscopic building blocks realize the flexible fabrication of three‐dimensional structures at macroscopic level, exerting significance on parallel manufactures. In this work, we reported macroscopic click chemistry utilizing hydrogel as macroscopic building blocks. Hydrogels G1 and G2 were prepared by incorporating M1 (N,N′‐dimethyl‐1,2‐ethanediamine) and P1 (alkyne functionalized polyethylene glycol) respectively, where polymer chains formed through diffusion‐induced amino‐yne click reaction entangled different hydrogel networks together. Additionally, chain‐like aggregates and complicated 3D structures such as tetrahedron and quadrangular pyramid were constructed based on the adhesion of the hydrogel blocks. The approach enables us to find more possibilities in the delicate designation of 3D aggregations as well as large‐scale manufacturing.

Study on the Attenuation of Long-Term Skid Resistance of Asphalt Mixtures under Aeolian Sand Conditions

In this work, the long-term skid resistance attenuation law of asphalt mixtures in the presence of aeolian sand was studied. Four types of asphalt mixtures underwent skid resistance abrasion tests using an accelerated loading tester. The pendulum value (BPN) and structure depth (MTD) of these four mixtures were determined under various conditions of sand density and abrasion times. The correlation between the BPN and density and the number of times of abrasion were investigated, respectively, to analyze the skid resistance attenuation law at the microscopic and macroscopic levels. Our results indicate that the skid resistance of the four types of asphalt mixtures initially decreased and subsequently reached a stable state. Sand density primarily influences skid resistance during the initial stage, while the number of abrasions becomes the dominant factor affecting skid resistance in the later stages.

Study on dynamic deformation-damage-ignition mechanism of GAP/RDX/TEGDN propellant

ABSTRACT Investigations on high-energy and low-vulnerability propellants can provide a better understanding for improving the operational effectiveness and survivability of strategic and tactical missiles. In the present study, the dynamic compressive mechanical properties and damage-ignition response mechanism of the GAP/RDX/TEGDN (GRT) propellant under high strain rates have been studied using a split Hopkinson pressure bar apparatus and a high-performance high-speed camera. The experimental results suggested that the mechanical properties of the GRT propellant, in terms of yield stress, initial compressive modulus, and ultimate stress, were greatly affected by the loaded strain rate. The true stress-strain curves exhibited an initial linear elasticity region followed by yielding a subsequent strain hardening and strain softening region stage. It has been found that the yield stress and ultimate stress increased with the strain rates. Moreover, at higher strain rates, the impulse increases significantly, leading to earlier and more intense ignition. The critical strain rate and the critical impulse of the GRT propellant are 5000 s−1 and 13.28 N · s, respectively. A judgment basis for GRT propellant ignition is established. Finally, according to the high-speed images and the posttest SEM images, it has been concluded that the dominant ignition mechanism of GRT propellant is flow at the macroscopic level and internal frictional heating at the mesoscopic level.

Flexoelectricity in oxide thin films

Flexoelectric effect describes the electromechanical coupling between the strain gradient and its internal polarization in all dielectrics. Despite this universality, the resulting flexoelectric field remains small at the macroscopic level. However, in nanosystems, the size-dependent effect of flexoelectricity becomes increasingly significant, leading to a notable flexoelectric field that can strongly influence the material’s physical properties. This review aims to explore the flexoelectric effect specifically at the nanoscale. We achieve this by examining strain gradients generated through two distinct methods: internal inhomogeneous strain and external stimulation. In addition, advanced synthesis techniques are utilized to enhance the properties and functionalities associated with flexoelectricity. Furthermore, we delve into other coupled phenomena observed in thin films, including the coupling and utilization of flexomagnetic and flexophotovoltaic effects. This review presents the latest advancements in these areas and highlights their role in driving further breakthroughs in the field of flexoelectricity.

In situ Raman analysis of reduced-graphene oxide-based electroactive nanofluids

This study investigates the effect of an applied stationary voltage on the vibrational properties of 1 M H2SO4 and H2SO4-based reduced-graphene oxide (rGO) nanofluids, commonly used as electrolytes in electrochemical cells. Our findings indicate that the energy of the symmetric stretching vibrations of H2SO4 remains unaffected by the electric field. However, a slight deviation toward lower energy and an enhancement of Raman intensity are observed in the asymmetric stretching vibration of H2SO4 due to the applied voltage. Furthermore, the addition of rGO to the base fluid produces a significant redshift in the symmetric stretching bands, indicating that the presence of rGO produces important changes at the macroscopic level in the base fluid. Synchronous and asynchronous maps further uncover the positive correlations between the D and G bands as well as between rGO and the base fluid bands. Specifically, the asynchronous map revealed complex dynamics between the rGO and H2SO4 bands and only positive correlations between H2SO4 bands. These results demonstrate the potential of Raman spectroscopy as a non-invasive technique to systematically study the influence of electric fields on the vibrational properties of fluids and nanofluids, which can ultimately lead to the development of significantly more efficient electrochemical cells.

Molecular dynamics simulation of the heterostructure of the CoCrFeMnNi high entropy alloy under an impact load

There have been numerous experimental studies conducted on the CoCrFeMnNi high entropy alloys (HEAs) at the macroscopic level. However, it is challenging to quantitatively analyze the shock behavior of the HEAs from a microscopic level through experiments. In this study, we construct single-crystal, twin-crystal, multilayer, hole, and two-phase structures of the CoCrFeMnNi HEAs using the molecular dynamics method. The effects of impact loading on the microscopic level are investigated for CoCrFeMnNi HEAs with different structures. By analyzing the evolution of their microstructure and the changes in physical parameters, the response laws and propagation characteristics of shock waves in various heterogeneous of CoCrFeMnNi HEAs are revealed at the atomic scale.

Kinetic- and Strain-Energy Approaches in the Thermal Analysis of Constrained Mechanical Systems: A Comparative Study

Abstract Despite the unconstrained thermal expansion is assumed stress-free, the conventional FE approach requires formulating elastic forces, and this in turn leads to elastic stresses. A displacement-based formulation, on the other hand, can be used to address this limitation by converting the thermal energy to kinetic energy instead of strain energy. The fundamental differences between the strain- and kinetic-energy approaches are discussed. It is shown that the unconstrained thermal expansion predicted using the kinetic-energy approach is independent of the continuum constitutive model, and consequently, such a formulation can be used for both solids and fluids. The displacement (kinetic) and strain (stress) formulations are discussed to shed light on the mechanism of thermal expansion at the macroscopic level. The thermal-expansion displacement formulation (TEDF) and position-gradient multiplicative decomposition into thermal and mechanical parts are used to compute the thermal stresses due to boundary and motion constraints (BMC). TEDF implementation issues are discussed and constant matrices evaluated at a preprocessing stage after applying sweeping matrix technique to eliminate rigid-body thermal-displacement translational modes are identified. Furthermore, the softening effect due to the constitutive-model dependence on the temperature is investigated at high temperatures. Numerical results are presented to show fundamental differences between the TEDF approach that converts heat energy to kinetic energy and conventional FE approach that converts heat energy to strain energy that produces elastic stresses.

Multiwalled carbon nanotubes as hard templates to yield advanced geopolymer-based self-assembled nanostructured ceramics

Novel multifunctional construction materials are needed to promote resilient infrastructure in the face of climate change and extreme weather. Nanostructured materials such as geopolymer reinforced with carbon-based nanomaterials are a promising way to reach that goal. In recent years, several studies have investigated the influence of nanomaterials on the physical properties of geopolymer composites such as compressive strength and fracture toughness. Yet, a fundamental understanding of the influence of nanomaterials on the nanoscale and micron-scale structure has been elusive so far. Our research objective is to understand how multiwalled carbon nanotubes (MWCNT) can help tailor the microstructure of geopolymers to yield architected multifunctional nanocomposites. We synthesized geopolymer nanocomposites reinforced with 50-nm thick multiwalled carbon nanotubes with mass fractions in the range of 0.1 wt%, 0.2 wt%, and 0.5 wt%. Our major finding is that MWCNTs act as hard templates that promote geopolymer formation via self-assembly. Geopolymer nanoparticle growth is observed along the walls of MWCNTs. A refinement in grain size is observed: increasing the fraction of MWCNTs by 0.5 wt% leads to a reduction in grain size by 54%. Similarly, increasing the mass fraction of MWCNTs leads to a densification of the geopolymer matrix as demonstrated by the Fourier transform infrared spectroscopy results and the statistical deconvolution analysis. Mercury intrusion porosimetry shows a nanoscale tailoring of the pore size distribution: a 26% decrease in porosity is observed as the fraction of MWCNTs is increased to 0.5 wt%. As a result of these nanoscale structural changes, a greater resistance to long-term deformation is observed for MWCNT-reinforced geopolymers, as the creep modulus increases both locally and macroscopically. At the macroscopic level, a 42% increase in the macroscopic logarithmic creep modulus is observed as the fraction of MWCNTs is increased to 0.5 wt%. These findings and the supporting methodology are important to understand how to manipulate matter below 100 nm. This research also paves the way for the design of resilient infrastructure materials with tailored microstructure and mechanical properties.

Observing the primary steps of ion solvation in helium droplets.

Solvation is a ubiquitous phenomenon in the natural sciences. At the macroscopic level, it is well understood through thermodynamics and chemical reaction kinetics1,2. At the atomic level, the primary steps of solvation are the attraction and binding of individual molecules or atoms of a solvent to molecules or ions of a solute1. These steps have, however, never been observed in real time. Here we instantly create a single sodium ion at the surface of a liquid helium nanodroplet3,4, and measure the number of solvent atoms that successively attach to the ion as a function of time. We found that the binding dynamics of the first five helium atoms is well described by a Poissonian process with a binding rate of 2.0 atoms per picosecond. This rate is consistent with time-dependent density-functional-theory simulations of the solvation process. Furthermore, our measurements enable an estimate of the energy removed from the region around the sodium ion as a function of time, revealing that half of the total solvation energy is dissipated after four picoseconds. Our experimental method opens possibilities for benchmarking theoretical models of ion solvation and for time-resolved measurements of cation-molecule complex formation.

Multi-Scale Engineered 2D Carbon Polyhedron Array with Enhanced Electrocatalytic Performance.

Electrocatalyst engineering from the atomic to macroscopic level of electrocatalysts is one of the most powerful routes to boost the performance of electrochemical devices. However, multi-scale structure engineering mainly focuses on the range of atomic-to-particle scale such as hierarchical porosity engineering, while catalyst engineering at the macroscopic level, such as the arrangement configuration of nanoparticles, is often overlooked. Here, a 2D carbon polyhedron array with a multi-scale engineered structure via facile chemical etching, ice-templating induced self-assembly, and high-temperature pyrolysis processes is reported. Controlled phytic acid etching of the carbon precursor introduces homogeneous atomic phosphorous and nitrogen doping, as well as a well-defined mesoporous structure. Subsequent ice-templated self-assembly triggers the formation of a 2D particle array superstructure. The atomic-level doping gives rise to high intrinsic activity, while the well-engineered porous structure and particle arrangement addresses the mass transport limitations at the microscopic particle level and macroscopic electrode level. As a result, the as-prepared electrocatalyst delivers outstanding performance toward oxygen reduction reaction in both acidic and alkaline media, which is better than recently reported state-of-the-art metal-free electrocatalysts. Molecular dynamics simulation together with extensive characterizations indicate that the performance enhancement originates from multi-scale structural synergy.

Application of In Silico Trials for the Investigation of Drug Effects on Cardiomyopathy-Diseased Heart Cycle Properties

In this paper, we present the abilities of an in silico platform used to simulate the effects of different drugs on heartbeat cycle performance. The platform is based on a finite element modelling approach with the fluid–solid interaction implemented using a loose coupling procedure. Active mechanical stresses are calculated using the Hunter excitation model while the passive mechanical stresses are calculated using a recently introduced experiment-based material model for the heart tissue. The applicability of the platform is illustrated using a simple parametric model of the left ventricle. The simulations are performed using parameters that are specific to drugs such as digoxin, mavacamten, 2-deoxy adenosine triphosphate, and disopyramide, with the concentration of calcium in the cardiac cells affected by these drugs given as an input function. The results are obtained for two geometries mimicking patients with hypertrophic and dilated cardiomyopathy, and also for different inlet/outlet boundary conditions simulating different drug effects at the macroscopic level. Using in silico simulations with virtual patients, it is possible to evaluate the influence of different drugs on cardiac output and ejection fraction. This approach can significantly reduce computational costs with an acceptable solution accuracy compared to approaches coupling finite element and biophysical muscle model methods that are used to calculate drug effects at the micro level.

Decomposition Is All You Need: Single-Objective to Multi-Objective Optimization towards Artificial General Intelligence

As a new abstract computational model in evolutionary transfer optimization (ETO), single-objective to multi-objective optimization (SMO) is conducted at the macroscopic level rather than the intermediate level for specific algorithms or the microscopic level for specific operators; this method aims to develop systems with a profound grasp of evolutionary dynamic and learning mechanism similar to human intelligence via a “decomposition” style (in the abstract of the well-known “Transformer” article “Attention is All You Need”, they use “attention” instead). To the best of our knowledge, it is the first work of SMO for discrete cases because we extend our conference paper and inherit its originality status. In this paper, by implementing the abstract SMO in specialized memetic algorithms, key knowledge from single-objective problems/tasks to the multi-objective core problem/task can be transferred or “gathered” for permutation flow shop scheduling problems, which will reduce the notorious complexity in combinatorial spaces for multi-objective settings in a straight method; this is because single-objective tasks are easier to complete than their multi-objective versions. Extensive experimental studies and theoretical results on benchmarks (1) emphasize our decomposition root in mathematical programming, such as Lagrangian relaxation and column generation; (2) provide two “where to go” strategies for both SMO and ETO; and (3) contribute to the mission of building safe and beneficial artificial general intelligence for manufacturing via evolutionary computation.

Study on filtration equations based on filtrate viscosity

ABSTRACT Classical filtration equations incorporate microscopic parameters, which pose challenges when applied in industrial settings. Previous extensive research has established the impact of filter cake thickness and variations in filtration pressure on the filtration rate. Moreover, the thickness of the filter cake is influenced by various factors, such as the filtration chamber’s design dimensions and the coal slurry’s properties. Thus, by expressing the properties of the coal slurry at a macroscopic level, it becomes possible to achieve a macroscopic representation of the filtration rate. This study presents the derivation of a macroscopic filtration equation that relies on the viscosity of the filtrate. The derivation process is mainly based on Darcy’s law, analyzing the relationship between the permeability of each layer and the permeability of cake under constant pressure and explaining and analyzing the method of determining the equation parameters.

Creating frames of reference for chert exploitation during the Late Pleistocene in Southwesternmost Iberia.

Southwestern Iberia has played a key role in characterizing Late Pleistocene human ecodynamics. Among other aspects of human behavior, chert procurement and management studies in this region have received increasing attention in the past two decades, especially focusing on the sites showing repeated human occupation, such as the case of Vale Boi (Southern Portugal). However, these studies have been very limited in their geographical scope, and mostly focused on brief macroscopic descriptions of the raw materials. To further our knowledge of the relationship between regional availability of raw materials and its impact on human adaptations and mobility, a more detailed approach to characterizing geological sources is needed. This paper characterizes chert raw materials location, diversity, and availability in a geologically well-defined region of southern Portugal - the Algarve. Through macroscopic and petrographic approaches, we provide a detailed characterization of geological chert sources to build a frame of reference for chert exploitation in the region. Our results show that there are four main chert formations in Algarve, and that despite the within-source variability, sufficient differences at macroscopic and petrographic levels are present to allow clear source attribution. These results provide a baseline for raw material studies in archaeological assemblages across southwestern Iberia, that will be essential to further characterize the dynamics of human behavior in some of the most important eco-cultural niches.

Effect of heterogeneity on the diffusion of Pb in apatite for petrochronological applications: A multiscale approach to characterizing the influence of apatite chemistry and anisotropy on Pb diffusion

The investigation of various factors effecting the Lead (Pb) diffusion in phosphate minerals such as apatite is still challenging in the interpretation of (UTh)/Pb geochronology. For (UTh)/Pb system, apatite minerals have closure temperatures in the range of 375 to 600 °C and therefore can be used for the investigation of mid-temperature thermochronological and/or petrochronological questions i.e., the reconstruction of thermal events in Earth's crust. There is still uncertainty whether Pb diffusion in apatite is characterized by thermally activated volume and/or anisotropic diffusion profiles or is instead impacted by novel growth processes and recrystallization (chemical substitutions). As the apatite structure support extensive compositional variability, including partial or total substitution of both the cationic and anionic sites and forms solid solutions therefore, it necessitates a thorough examination of these effects and anisotropy on Pb diffusivity and (UTh)/Pb geochronometric system. For this, a multi-scale study is carried out to examine the effects of chemical composition, anisotropy, and growth structure on the diffusion of Pb in order to better understand the behaviour of Pb diffusion in apatite. This study employed computational techniques like Density Functional Theory (DFT) and Transition State Theory (TST) at the atomic level and integrates it with the Kinetic Monte Carlo (KMC) simulations at the macroscopic level. Models of this study shows that Pb diffusion is completely anisotropic along the preferred z-axis or [001] direction and Pb readily escapes faster from Na-substituted apatite when compared to pure F-apatite and Cl-substituted apatite. Because of this anisotropy and chemical substitutions, Pb diffusivity in apatite either increases by opening of diffusion channels or decreases by blocking the diffusion channels depending on the site and type of chemical substitution. Further, in case of blocking effect the Pb diffusion occurs through workaround pathways and approaches towards the isotropic diffusion. For Na-substituted apatite, the impact of Na occupation on anisotropic Pb diffusion is significantly greater while in case of Cl-substituted apatite the Cl occupation mostly leads towards isotropic diffusion by opening the diffusion paths along other directions (mostly along the in-plane direction). Furthermore, the high closure temperatures (Tc) (e.g., ∼1370 °C) of the modelled apatites (except the perfect Na-substituted apatite e.g., ∼500 °C) of this study when compared to the Tc of Durango apatite obtained experimentally for the effective grain size of 100 μm and cooling rates of 10 °C/Ma indicate that the effective closure temperature dominantly depends on the degree and types of chemical substitutions and play a crucial role for the closure or opening of Pb diffusion/loss in apatites.

Upcycling fish scales through heating for steganography and Rhodamine B adsorption application

With increasing population and limited resources, a potential route for improving sustainability is increased reuse of waste materials. By re-looking at wastes, interesting properties and multifunctionalities can be discovered in materials previously explored. Despite years of research on bio-compatible fish scales, there is limited study on the fluorescence property of this abundant waste material. Controlled denaturation of collagen and introduction of defects can serve as a means to transform the fluorescence property of these fish scale wastes while providing more adsorption sites for pollutant removal, turning multifunctional fish scales into a natural steganographic material for transmitting text and images at both the macroscopic and microscopic levels and effectively removing Rhodamine B pollutants (91 % removal) within a short contact time (10 minutes). Our work offers a glimpse into the realm of engineering defects-induced fluorescence in natural material with potential as bio-compatible fluorescence probes while encouraging multidimensional applicability to be established in otherwise overlooked waste resources.

Enhanced performance of cutting angle cylinder piezoelectric energy harvester via coupling vortex-induced vibration and galloping

This paper proposes a novel flow-induced vibration piezoelectric energy harvester with various cutting angle cylinders (FIVPEH-C), for coupling vortex-induced vibration and galloping as well as improving the energy harvesting efficiency. The conceptual designing of the piezoelectric energy harvester with different cutting angle cylinders is conducted, the theoretical models of fluid–structure-electric multi-physical coupled fields are derived, the aerodynamic parameters are solved by three-dimensional computational fluid dynamics (CFD) simulation, and the experimental prototypes of the harvester system are fabricated. The accuracy of the theoretical model is verified by the experimental results. The flow field reveals the vortex shedding characteristics and mode conversion mechanisms. The cutting angle cylinder bluff body transforms the formation mode, initial shape, and intensity of the vortices at the microscopic level, which in turn affects the shedding mode and distance of the vortices at the macroscopic level. When α = 0° and β = 0°, the maximum output voltage of the FIVPEH-C is 13.36 V, and the enhancement ratio reaches up to 108.01 % over the conventional one, which verifies better harvesting performance. This work provides important guidance for designing more efficient piezoelectric energy harvesters via various cutting angle cylinders.

Structural and Thermal Diffusivity Analysis of an Organoferroelastic Crystal Showing Scissor-Like Two-Directional Deformation Induced by Uniaxial Compression.

A two-directional ferroelastic deformation in organic crystals is unprecedented owing to its anisotropic crystal packing, in contrast to isotropic symmetrical packing in inorganic compounds and polymers. Thereby, finding and constructing multidirectional ferroelastic deformations in organic compounds is undoubtedly complex and at once calls for deep comprehension. Herein, we demonstrate the first example of a two-directional ferroelastic deformation with a unique scissor-like movement in single crystals of trans-3-hexenedioic acid by the application of uniaxial compression stress. A detailed structural investigation of the mechanical deformation at the macroscopic and microscopic levels by three distinct force measurement techniques (including shear and three-point bending test), single crystal X-ray diffraction techniques, and polarized synchrotron-FTIR microspectroscopy highlighted that mechanical twinning promoted the deformation. The presence of two crystallographically equivalent faces and the herringbone arrangement promoted the two-directional ferroelastic deformation. In addition, anisotropic heat transfer properties in the parent and the deformed domains were investigated by thermal diffusivity measurement on all three axes using microscale temperature-wave analysis (μ-TWA). A correlation between the anisotropic structural arrangement and the difference in thermal diffusivity and mechanical behavior in the two-directional organoferroelastic deformation could be established. The structural and molecular level information from this two-directional ferroelastic deformation would lead to a more profound understanding of the structure-property relationship in multidirectional deformation in organic crystals.

Extended Theory and Analysis of Potential Applications of Gauss's Law

This article analyzes and discusses the extended theory of Gauss's law and its potential applications in different fields. In the theoretical foundation section, the article elaborates on the definition, theory, and formulas of the traditional Gauss's law, providing mathematical derivations. Additionally, it reviews the applications of Gauss's law in electrostatics and gravitational fields, including aspects such as electric field flux, electric potential displacement, gravitational field, and mass distribution. In the potential application analysis section, the article explores the potential applications of Gauss's law in fields such as communications, acoustics, and medicine The expanded theories and potential applications of Gauss's theorem provide us with a unified mathematical framework at the macroscopic level for describing and explaining physical phenomena in different fields. By applying Gauss's theorem and its extended forms, we can better understand and explore various phenomena in the natural world, applying them to acoustics, medicine, and scientific research, thus advancing technological development and addressing practical problems.

Compressive and Shear Strength of Kevlar based Nano Composites

The Fibre Reinforced Composite (FRC) material consists of building materials in macroscopic level by having fibres and resin as reinforcement and matrix material respectively. It has different physical and chemical properties that were bonded together in order to get new material with different required characteristics from individual components. The properties of the composites are largely depending on the matrix and reinforcement materials. The matrix strengthening process by introduction of fine nano particles in composite laminate was done in this work. In order to study the effect of nano particles, the composite consists of Kevlar- 49 (K49) fibre in woven form with epoxy resin as matrix was considered. All the test specimens have been prepared with 12 layers of K49 to build 3mm thickness using vacuum bag moulding method. The K49 fibre in form of plain-woven type were chosen as reinforcement material. The nano fillers such as Titanium dioxide (TiO2), Calcium Carbonate (CaCO3) and Graphite powder (Gr) were used as nanomaterial added in the matrix and was compared with pure K49 reinforced composites for better performance. The TiO2, CaCO3 and GR nano fillers were constituted on various weight ratios in FRC. The structural properties like compression and shear strengths were determined as per ASTM standards. The fracture behaviour for all the categories of laminate has been detailed and reported using scanning electron microscope.