Solid Surface Research Articles

The evolution process of fractures and their modification effects on the liquid–solid interface during liquid nitrogen cyclic freeze–thaw of coal and shale

Liquid nitrogen cyclic freezing-thawing fracturing (LNCFT) is an innovative method for the waterless fracturing of coal and rock, harnessing the effects of low temperature, phase change, and expansion. However, the mechanisms behind micro-fracture propagation, evolution, and surface modification during LNCFT remain elusive. This study concentrates on anthracite coal and roof shale in the Jiaozuo mining area. It conducts LNCFT experiments under various saturated water conditions and employs a stereoscopic fluorescence microscope and an optical contact angle measuring instrument for observations, analyzing the surface modification effects resulting from the propagation and evolution of fractures on solid surfaces. The study unveils the following findings: (1) LNCFT effectively creates a network of micro-fractures. The quantity and length of fractures significantly increase with the number of fracturing cycles, and the effect is more pronounced with higher water content, especially in coal compared to shale. Fracture evolution falls into three categories: extension, intersecting, and newly formed independent fractures, with the scale of extension and intersecting of the original fractures determining the modification effect. (2) The LNCFT process exhibits distinct stages and selectivity. The strength of early-stage modifications (before eight cycles) directly influences the overall modification effect. (3) Throughout the LNCFT process, the solid–liquid surface contact angle first increases and then decreases with the number of fracturing cycles. This pattern can be analyzed using the Wenzel model. Liquid nitrogen fracturing increases the surface roughness of coal and shale, leading to a transition from hydrophobicity to hydrophilicity on their surfaces. The research findings of this paper provide theoretical guidance for the modification of low-permeability reservoirs.

Emergent Dirac Fermions in Epitaxial Planar Silicene Heterostructure.

Silicene, a single layer of Si atoms, shares many remarkable electronic properties with graphene. So far, silicene has been synthesized in its epitaxial form on a few surfaces of solids. Thus, the problem of silicene-substrate interaction appears, which usually depresses the original electronic behavior but may trigger properties superior to those of bare components. We report the direct observation of robust Dirac-dispersed bands in epitaxial silicene grown on Au(111) films deposited on Si(111). By performing in-depth angle-resolved photoemission spectroscopy measurements, we reveal three pairs of one-dimensional bands with linear dispersion running in three different directions of an otherwise two-dimensional system. By combining these results with first-principles calculations, we explore the nature of these bands and point to strong interaction between subsystems forming a complex Si-Au heterostructure. These findings emphasize the essential role of interfacial coupling and open a unique materials platform for exploring exotic quantum phenomena and applications in future-generation nanoelectronics.

Hydrodynamic force on a hemispheroidal particle attached to a planar surface in linear shear flow

This paper presents a computational fluid dynamics (CFD) study of the hydrodynamic force exerted on a prolate hemispheroidal particle (as a model geometry for debris formed during glass cutting) attached to a planar solid surface under linear shear flow. The three-dimensional conservation equations for mass and momentum are solved using a finite-volume scheme on a polyhedral mesh to compute the steady flow field around the particle and determine the hydrodynamic force on the particle as a function of particle aspect ratio (ε), pitch angle (θp) with respect to the surface, and orientation angle (θf) with respect to the flow direction. The computational results are used to develop a correlation for the drag coefficient (CD) in terms of more general shape descriptors that can be used for particles of irregular shape (i.e., with no symmetry)– namely, lateral view factor (ψl), particle separation (ψs), and dimensionless hydraulic radius (ψh). Computations are also performed for several particles with irregular shapes (resembling glass debris) and the CFD results for drag coefficient are compared to predictions of the empirical correlation. The drag coefficient correlation resulting from this study will be useful for estimating the hydrodynamic drag force exerted by the flow of cleaning fluids on irregularly-shaped particles adhering to planar solid surfaces.

Crystal Self-Assembly under Confinement: Bridging Nanomaterials to Integrated Devices.

ConspectusSelf-assembly, a spontaneous process that organizes disordered constituents into ordered structures, has revolutionized our fundamental understanding of living matter, nanotechnology, and molecular science. From the perspective of nanomaterials, self-assembly serves as a bottom-up method for creating long-range-ordered materials. This is accomplished by tailoring the geometry, chemistry, and interactions of the components, thereby facilitating the efficient fabrication of high-quality materials and high-performance functional devices. Over the past few decades, we have seen controllable organization and diverse phases in self-assembled materials, such as organic crystals, biomolecular structures, and colloidal nanoparticle supercrystals. However, most self-assembled ordered materials and their assembly mechanisms are derived from constituents in a liquid bulk medium, where the effects of boundaries and interfaces are negligible. In the context of nanostructure patterning, self-assembly occurs in confined spaces, with feature sizes ranging from a few to hundreds of nanometers. In such settings, ubiquitous boundaries and interfaces can trap the system in a kinetically favored but metastable state, devoid of long-range order. This makes it extremely difficult to achieve ordered structures in micro/nano-patterning techniques that rely on sessile microdroplets, such as inkjet printing, dip-pen lithography, and contact printing.In stark contrast to sessile droplets, capillary bridges─formed by liquids confined between two solid surfaces─provide unique opportunities for understanding the long-range-ordered self-assembly of crystalline materials under spatial confinement. Because capillary bridges are stabilized by Laplace pressure, which is inversely proportional to the feature size, the confinement and manipulation of solutions or suspensions of functional materials at the nanoscale become accessible through the rational design of surface chemistry and geometry. Although global thermodynamic equilibrium is unattainable in evaporative systems, ordered nucleation and packing of constituent components can be locally realized at the contact line of capillary bridges. This enables the unprecedented fabrication of long-range-ordered micro/nanostructures with deterministic patterns.In this Account, we review the advancements in long-range-ordered self-assembly of crystalline micro/nanostructures under confinement. First, we briefly introduce crystalline materials characterized by strong intramolecular interactions and relatively weak intermolecular forces, analyzing both the opportunities and challenges inherent to self-assembled nanomaterials. Next, we delve into the construction and manipulation of confined liquids, focusing especially on capillary bridges controlled by engineered chemistry and geometry to regulate Laplace pressure. Through this approach, we have achieved capillary bridges with thicknesses on the order of a few nanometers and wafer-scale homogeneity, facilitating the self-assembly of ordered structures. Supported by factors such as local free-volume entropy, electrostatic interactions, curvilinear geometry, directional microfluidics, and nanoconfinement, we have achieved long-range-ordered, deterministic patterning of organic semiconductors, metal-halide perovskites, and colloidal nanocrystal superlattices using this capillary-bridge platform. These long-range microstructures serve as a bridge between nanomaterials and integrated devices, enabling emergent functionalities like intrinsic stretchability, giant photoconductivity, propagating and interacting exciton polaritons, and spin-valley-locked lasing, which are otherwise unattainable in disordered materials. Finally, we discuss potential directions for both the fundamental understanding and practical applications of confined self-assembly.

Experimental study on the influence of restricted distance on the discrete flame spread of different widths

In this paper, the effects of varying material widths on the propagation of discrete fires within diverse confined space conditions are investigated experimentally. The width-induced mechanisms influencing the flame spread of discrete solid surfaces in distinct confined spaces are comprehensively discussed, encompassing flame characteristics, pyrolysis front dynamics, flame spread rate, and mass loss rate. The findings reveal that the dimensionless flame height and width conform to a negative power relationship at varying restricted distances. Furthermore, a positive correlation between the width of the PMMA in confined spaces and both the flame spread rate and the mass loss rate is established. Notably, when the width is fixed, the confined space plays a dominant role in the propagation of flames. As the restricted distance decreases, the flames become more slender. Additionally, flame height, flame spread rate, and mass loss rate increase with the widening of the material. However, as the restricted distance becomes smaller, the effect of width becomes less pronounced. Under conditions of same restricted distance, an increased width results in a higher radiation factor, thereby enhancing the thermal feedback of the wall to the material, which in turn accelerates the spread rate of discrete flames. Moreover, due to the dominant role of radiant heat feedback provided by the confined walls to the discrete PMMA panels, the proportion of heat transferred by convection in the flames is minimal. Consequently, the influence of the convective coefficient's width variation on flame spread is relatively minor within confined spaces. Ultimately, an energy conservation model under confined spaces was established, which facilitated the analysis of the comprehensive mechanism of flame spread influenced by varying confined spaces and material widths.

Surface effect on the phase separation in thin liquid crystal film as seen from a mean-field approach

The effect of the interplay between attractive nonlocal surface interactions and attractive pair long-range intermolecular couplings on molecular structures of liquid crystals confined in thin cells with flat solid surfaces has been studied. It has been shown, in the framework of the extended McMillan′s mean field theory, that in the confined LC system a complex orientational and translational ordering of molecules can be induced. Several scenarios of the formation of local smectic A, nematic, and isotropic phases have been shown to coexist in a certain temperature range. Due to the nonlocality of the surface interaction, an unexpected complexity of the spatial arrangement of these local phases along the direction of the normal to the surface may exhibit itself.

Enhancing the Output of Liquid-Solid Triboelectric Nanogenerators through Surface Roughness Optimization.

The advent of liquid-solid triboelectric nanogenerators (LS-TENGs) has ushered in a new era for harnessing and using energy derived from water. To date, extensive research has been conducted to enhance the output of LS-TENGs, thereby improving water utilization efficiency and facilitating their practical application. However, in contrast to intricate chemical treatment methods and specialized structures, a straightforward operational process and cost-effective materials are more conducive to the widespread adoption of LS-TENGs in practical applications. This work presents a novel method to enhance the output of LS-TENGs by increasing the liquid-solid contact area. The approach involves creating roughness on the solid surface through sandpaper grinding, which is simple in design and easy to operate and significantly reduces the cost of the experiment. The theory is applied to the solid triboelectric layer commonly used in the LS-TENG, demonstrating its universality and wide applicability to improve the output of the LS-TENG. The practical performance of the device is demonstrated by charging the capacitor and external load and driving the hygrometer and commercial 5 W LED light bulb, which can directly light up 300 commercial light-emitting diodes (LEDs) driven by a drop of water. This work provides a new method for the optimization of LS-TENGs and contributes to the wide application of LS-TENGs. This is a significant step forward in the field of energy harvesting and utilization.

Molybdenum Based Manganese Oxides as Optoelectronic Nanomaterials: Synthesis, Structural & Optical Characterization

AbstractThis work reports the synthesis of molybdenum based manganese oxide nanomaterials named as (CH1‐CH5) via a facile hydrothermal approach. Nanomaterials were characterized through Powder XRD, SEM, BET, UV‐Vis, Photoluminescence, and FTIR analysis. Structural characterization revealed triclinic crystal structure of nanomaterials having particle sizes in the range of 23.08–52.7 nm with very low levels of microstrain levels (<0.05) and dislocation densities. Surface areas were found to be in the range of 42.37–52.32 m2/g with mesoporous structures and solid bar and cross surface morphology. Optical band gaps (Eg) calculated from absorption data was found to be in the range of 4.65–4.75 eV for direct transitions whereas 4.60–4.74 eV for indirect transitions. The Eg calculated from emission data was found to be in the range of 2.42–2.67 eV. Absorption edge broadening was investigated by urbach energy (EU) calculated to be in the range of 1.23–1.51 eV whereas fermi energy (Ef) were obtained as 4.66–4.72 eV. Refractive index (n) was calculated to be in the range of 0.13–0.21 whereas high values obtained for real and imaginary parts of dielectric constants (ϵ) indicating polarization relaxation in synthesized materials. The calculated structural and optical characteristics indicates that these materials can be potential candidates for optoelectronic and catalytic applications.

Microvesicle-Embedded Solid-liquid Composite Coating for the Tribological Behavior Regulation and Long-Acting Lubrication.

Friction interfaces in liquid-embedded composite lubrication coatings commonly comprise a combination of discontinuous fluid films and rough solid contact surfaces, which together ensure easy shearing and a prolonged wear life. However, achieving high efficacy in mixed lubrication poses a challenge due to the conflicting nature of enhanced migration freedom for the liquid lubricant and increased mechanical strength of the solid matrix. Recent efforts have focused on incorporating reinforcing fillers to develop multicomponent, multiphase composites that can address this paradox. Here, we describe a modified attapulgite (APT) with strong biphasic wettability via the oil decompressive osmosis treatment on APT nanocontainers grafted with long nonpolar alkyl chains. This modified APT enables control over the size, distribution, and mobility of lubricant droplets by constructing a Pickering emulsion and toughens the solid-phase matrix through dispersion strengthening. Additionally, the introduction of APT induces the formation of a solid tribofilm during friction, which possesses a higher oil adsorption capacity, as verified through first-principles calculations based on density functional theory (DFT). Consequently, the fluid films can be replenished by the fracture of nanocontainers and adsorption from the bulk phase; further comprehensive and effective regulation of the friction interface leads to low friction and wear.

Integrative studies of ionic liquid interface layers: bridging experiments, theoretical models and simulations.

Ionic liquids (ILs) are a class of salts existing in the liquid state below 100 °C, possessing low volatility, high thermal stability as well as many highly attractive solvent and electrochemical capabilities, etc., making them highly tunable for a great variety of applications, such as lubricants, electrolytes, and soft functional materials. In many applications, ILs are first either physi- or chemisorbed on a solid surface to successively create more functional materials. The functions of ILs at solid surfaces can differ considerably from those of bulk ILs, mainly due to distinct interfacial layers with tunable structures resulting in new ionic liquid interface layer properties and enhanced performance. Due to an almost infinite number of possible combinations among the cations and anions to form ILs, the diversity of various solid surfaces, as well as different external conditions and stimuli, a detailed molecular-level understanding of their structure-property relationship is of utmost significance for a judicious design of IL-solid interfaces with appropriate properties for task-specific applications. Many experimental techniques, such as atomic force microscopy, surface force apparatus, and so on, have been used for studying the ion structuring of the IL interface layer. Molecular Dynamics simulations have been widely used to investigate the microscopic behavior of the IL interface layer. To interpret and clarify the IL structure and dynamics as well as to predict their properties, it is always beneficial to combine both experiments and simulations as close as possible. In another theoretical model development to bridge the structure and properties of the IL interface layer with performance, thermodynamic prediction & property modeling has been demonstrated as an effective tool to add the properties and function of the studied nanomaterials. Herein, we present recent findings from applying the multiscale triangle "experiment-simulation-thermodynamic modeling" in the studies of ion structuring of ILs in the vicinity of solid surfaces, as well as how it qualitatively and quantitatively correlates to the overall ILs properties, performance, and function. We introduce the most common techniques behind "experiment-simulation-thermodynamic modeling" and how they are applied for studying the IL interface layer structuring, and we highlight the possibilities of the IL interface layer structuring in applications such as lubrication and energy storage.

Influence of organic matters on the adsorption-desorption of 1,2-dichloroethane on soil in water and model saturated aquifer.

1,2-Dichloroethane (1,2-DCA) is a typical organic chlorinated compound largely utilized in chemical manufacturing and industrial production and also a common pollutant in organically contaminated sites. The adsorption of 1,2-DCA on soil grains significantly influences its environmental fate and removal process. This study investigated the influence of fulvic acid (FA) and humic acid (HA) on the adsorption-desorption of 1,2-DCA in solid-liquid interfaces in water or constructed porous media. Experimental findings demonstrated the influence of organic matter on the adsorption of 1,2-DCA at the solid-water interface. 1,2-DCA adsorption increased in the FA or HA-treated soils when organic matter was present on the solid surfaces. The 1,2-DCA adsorption in the mixture of FA and HA was slightly lower than that in single organic acids, depending on the binding of FA and HA to the soil grains/colloids. Basic conditions reduced the adsorption of 1,2-DCA on soils, whereas acidic conditions enhanced adsorption due to the increased interactions via adsorption sites and hydrogen bonds. Conversely, the presence of organic matter in solutions (liquid phase in constructed porous media) will reduce the adsorption of 1,2-DCA on solid surfaces and increase the transport in the model aquifer. The combination of FA, HA, and rhamnolipids is helpful for the removal of 1,2-DCA from solid surfaces. Additionally, because of the enhanced desorption, the risk of 1,2-DCA contamination in groundwater can be increased when the organic matter or surfactant is present in the liquid phase if the eluent is not collected. This study helps to better understand the cooperative interaction of soil organic matter and chlorinated hydrocarbons at solid-water interfaces and the environmental fate and potential removal strategies of chlorinated hydrocarbons in contaminated sites.

Structure and migration mechanism of thin liquid film in vicinity of advancing contact line

Thin liquid film near the gas-liquid-solid three phase contact line is the core area of oil and gas production, phase-change heat transfer, and material synthesis systems. Although there are many experimental studies on fluid dynamics in the contact line region, the prediction of contact angle is still difficult, and the bottleneck lies in the special structure of thin liquid film in the contact line region. Because the microstructure of thin liquid film is not well understood, the prediction of dynamic contact angle is always controversial. At present, the main controversial points focus on whether the microscopic contact angle changes with speed, and whether the microscopic contact angle is the same as the macroscopic contact angle. Therefore, it is crucial to monitor the dynamic process of the microscopic contact angle in the thin liquid film region of the contact line. In this work, the wetting system of 50 nm liquid droplets on different solid surfaces is constructed by molecular dynamics simulation, and the structure and migration mechanism of thin liquid film are studied. The structure of the precursor liquid film in the completely wetting droplet advancing contact line region and the nanoscale convex structure in the partially wetting droplet advancing contact line region are obtained. The precursor liquid film is 2–3 molecular layers in thickness, leading the droplet to move forward. However, there is no precursor liquid film in a partially wetting system, and the convex nano-bending larger than 10 nm is formed in the wetting process, resulting in the microscopic contact angle. By comparing the difference between the absolute smooth surface dynamic wetting process and the actual solid surface dynamic wetting process, the dynamic evolution law of the micro contact angle and the macro contact angle with time are obtained for the first time in the simulation. The liquid molecules in the contact line region are tracked and statistically analyzed by means of particle tracer. It is revealed that the liquid molecules in thin liquid film change from sliding mode to rolling mode with speed increasing under the action of solid surface friction, and then the air entrainment at the bottom of the contact line leads to slip and sputtering. The research results are expected to provide theoretical guidance for the following three directions: 1) improving heat transfer efficiency of micro and nano device based on wettability control; 2) improving the imbibition displacement efficiency of shale oil micro-nano matrix based on wettability regulation; 3) constructing universal contact angle prediction model.

Spreading dynamics of a droplet upon impact with a liquid film containing solid particles.

This study examines how a deionized water droplet behaves when it centrally collides with a liquid film containing TiO2 nanoparticles at low impact velocities, aiming to understand how nanoparticles affect droplet spreading, in particular its maximum spreading diameter. Typically, we found that both the spreading velocity and dynamic contact angle of the droplet would be similarly affected by increasing TiO2 nanoparticle concentration. During retraction, the droplet's dimensionless spreading diameter oscillates, with more pronounced oscillations at higher nanoparticle concentrations. Moreover, both the droplet's maximum dimensionless rebound height and dynamic contact angle show similar trends with increasing TiO2 nanoparticle concentration. Interestingly, we proved that the influence of the solid-liquid interaction (Stokes force) on the fluid during the spreading process accounts for less than 2% of the surface energy when the droplet reaches its maximum spreading diameter, indicating a negligible effect on droplet spreading. We hypothesize that the droplet's initial energy is fully converted into surface energy and viscous dissipation at maximum spreading diameter, which involves viscous dissipation both between the fluid and the solid wall surface and the fluid and solid particle surface. Based on this, we developed a model for predicting the droplet's maximum spreading diameter that includes parameters associated with the solid particles. Compared to models in the literature that do not consider the effect of solid particles, our model aligns more closely with experimental data. The results indicate that adding solid particles leads to increased viscous dissipation, which in turn reduces the droplet's maximum spreading diameter.

Effect of closed-loop nanochannels on the onset of explosive boiling: a molecular dynamics simulation study

As a primary boiling mode, explosive boiling has shown a promising future in many applications and received much research attention. The topology of the solid surface in contact with the liquid, particularly nanostructured surfaces, significantly affects the onset time of explosive boiling of a liquid nanofilm. Most studies investigated explosive boiling on non-closed-loop (parallel) nanochannel surfaces. Here, for the first time, explosive boiling in a closed-loop nanochannel was studied by the non-equilibrium molecular dynamics simulation method. Explosive boiling of liquid argon nanofilm on solid copper surfaces with different topologies, including an ideally smooth, a non-closed-loop, and a closed-loop nanochannel, was simulated. The results showed that, compared with the ideally smooth surface, the onset time of explosive boiling decreased for the non-closed-loop and closed-loop nanochannel surfaces. However, it turned out that compared to the non-closed-loop nanochannel, using the closed-loop nanochannel has an adverse effect on heat flux and the onset time of explosive boiling.

Uranyl (UO22+) structuring and dynamics at graphene/electrolyte interface.

The physicochemical phenomena at the solid/electrolyte interfaces govern various industrial processes ranging from energy generation, storage, and catalysis to chemical separations and purification. Adsorption-based solid/liquid extraction methods are promising for the selective and rapid separation of nuclear (such as uranium) and other critical materials. In this study, we quantified the adsorption, complexation, and dynamics of UO22+ ions on the graphene surface in various electrolyte media (LiNO3, NaNO3 and CsNO3) using all-atom molecular dynamics simulations, in combination with network theory based subensemble analysis, enhanced sampling, and temporal analysis. We observe that the choice of background electrolyte impacts the propensity of UO22+ adsorption on the graphene surface, with LiNO3 being the most favorable at both low and high uranyl-nitrate concentrations. Even though UO22+ primarily retained its coordination with water and interacted via the outer-sphere mechanism with graphene, the interfacial segregation of NO3- increased the number of contact ion pairs (CIPs) between UO22+ and NO3- ions, and the residence times of UO22+ within the interfacial region. This study provides a fundamental understanding of the structure and dynamics of UO22+ on the solid surface necessary to design advanced adsorption-based separation methods for energy-relevant materials.

Chemical properties of superatomic Li3O clusters from a density functional theory perspective: formation of chloride and adsorption behavior on graphynes.

Superatomic clusters have received a lot of attention due to their ability to mimic the electronic configurations of individual atoms. Despite numerous studies of these clusters, their ability to mimic the chemical properties of individual atoms is still unclear. This also applies for Li3O/Li3O+ clusters which simulate the Na atom and its ion, but their capabilities to form a salt or be adsorbed on surfaces remain unexplored. In this work, a density functional theory investigation was performed to study the chemical formation and adsorption behavior of the superatomic Li3O cluster. The results show that Li3O mimics the chemical properties of the sodium element to form Li3O chloride and be adsorbed on graphdiyne and γ-graphyne with similar binding energy as the sodium adsorbate cases. Beyond the isolated cluster individuals, superatoms are demonstrated as elements from the 3D periodic table to construct compounds and attach onto solid surfaces.

Drop impact dynamics of complex fluids: a review.

The impact of fluid drops on solid substrates has widespread interest in many industrial coating and spraying applications, such as ink-jet printing and agricultural pesticide sprays. Many of the fluids used in these applications are non-Newtonian, that is they contain particulate or polymeric additives that strongly modify their flow behaviour. While a large body of experimental and theoretical work has been done to understand the impact dynamics of Newtonian fluids, we as a community have much progress to make to understand how these dynamics are modified when the impact fluid has non-Newtonian rheology. In this review, we outline recent experimental, theoretical, and computational advances in the study of impact dynamics of complex fluids on solid surfaces. Here, we provide an overview of this field that is geared towards a multidisciplinary audience. Our discussion is segmented by two principal material constitutions: polymeric fluids and particulate suspensions. Throughout, we highlight promising future directions, as well as ongoing experimental and theoretical challenges in the field.

A weakened Fermi level pinning induced adsorption energy non-charge-transfer mechanism during O2 adsorption in silicene/graphene heterojunctions.

Understanding the mechanisms of gas adsorption on a solid surface and making this process tunable are of great significance in fundamental science and industrial applications. Bond creation and charge transfer are often used to explain the origin of adsorption energy (Ead). However, in this study, a new mechanism is observed in O2 adsorption on pure silicene (PS) and silicene/graphene heterojunction (SGH) surfaces, in which the charge distribution remains almost unchanged, but Ead still has a significant change in the order of 0.3 eV. The weakened Fermi level pinning effect is found to be responsible for this interesting behavior and the variation of Ead is approximately equal to the change of work function. Furthermore, this effect is independent of the twist angles in the van der Waals SGH. Our results are consistent with experimental observations in overcoming the degradation of silicene in air.

Diffractive mirrors for neutral-atom matter-wave optics.

Mirrors for atoms and molecules are essential tools for matter-wave optics with neutral particles. Their realization has required either a clean and atomically smooth crystal surface, sophisticated tailored electromagnetic fields, nanofabrication, or particle cooling because of the inherently short de Broglie wavelengths and strong interactions of atoms with surfaces. Here, we demonstrate reflection of He atoms from inexpensive, readily available, and robust gratings designed for light waves. Using different types of blazed gratings with different periods, we study how microscopic and macroscopic grating properties affect the mirror performance. A holographic grating with 417 nm period shows reflectivity up to 47% for He atoms, demonstrating that commercial gratings can serve as mirrors for thermal energy atoms and molecules. We also observe reflection of He2 and He3 which implies that the grating might also function as a mirror for other breakable particles that, under typical conditions, do not scatter nondestructively from a solid surface such as, e.g., metastable atoms or antihydrogen atoms.

Comparative Heat Transfer Performance of TPMS Structures: Spotlight on Fisch Koch S versus Gyroid, Diamond and SplitP Lattices

This study assesses the thermal behavior of different TPMS configurations, specifically examining the Fischer Koch S lattice in comparison to Gyroid, Diamond, and SplitP lattices. Utilizing numerical simulations alongside experimental validation, the research delves into the efficacy of different TPMS designs in enhancing convective heat transfer and fluid dynamics. Results indicate that the Fischer Koch S lattice outperforms other models, exhibiting enhanced convective heat transfer rates and increased Nusselt numbers due to greater areas of contact between the fluid and the solid surfaces and optimized flow patterns. Nevertheless, it also demonstrates significant pressure drops at high Reynolds numbers. These findings underscore the necessity for further research to refine performance based on these insights.