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Herein, (14,14,14)‐graphyne (GY) supported by silicon substrate is chosen to be the research object. The results demonstrate that the increasing distance between substrate and supported materials (dsub‐sup) results in the enhancement of thermal conductivity (TC) of supported GY, and the TC of supported GY is even higher than that of free‐standing GY when dsub‐sup exceeds a certain value, which means substrate plays an abnormal promoting role in the thermal transport in supported materials (SM). This phenomenon breaks the traditional cognition that the increasing dsub‐sup can only lead to the TC of SM approaching that of free‐standing model. The related mechanism can be seen as the combined impact of weak interaction of long‐dsub‐sup substrate and tensile effect led by lattice mismatch between substrate and GY. Combining with phonon analysis, it can be observed that the influence of substrate shows a closer relationship with phonon scattering, i.e., the anharmonicity, especially the anharmonicity of out‐of‐plane direction. The anomalous promoting effect of long‐dsub‐sup can be also attributed to the weaker scattering of out‐of‐plane phonon, especially the reduced four‐order phonon scattering. This research provides a new idea to suppress the negative effect of substrate on heat dissipation in electronic devices. [ABSTRACT FROM AUTHOR]

The microstrip antennas matured and improved over the last 25 years. Throughout these years, the limitations, and specifications of the said antennas have been overcome and significantly improved. Known to be lowprofile, suitable for mobile, and lightweight, these microstrip antennas are the focus of this research. In this paper, the researchers designed a microstrip antenna with varying lengths and substrates. They tested the changes and the effects in microstrip antennas of different lengths, along with altering substrates. To verify the differences, the researchers compared the performance parameters maximum gain (dBi), minimum gain (dBi), and S11 graph on each tested length and changed substrate. The rough set theory was used to determine the optimal design via MATLAB. From there, the researchers analyzed the results gathered and drew their respective conclusions. Additionally, they saw and compared each data result to know what antenna has the best performance parameters. From the results, a change in the dimension will result in a decrease in the said performance parameters. Furthermore, the change in substrate thickness also diminishes these changes. [ABSTRACT FROM AUTHOR]

Monolayer graphene absorbs 2.3 percent of the incident visible light. This "small" absorption has been used to emphasize the visual transparency of graphene, but it in fact means that multilayer graphene absorbs a sizable fraction of incident light, which causes non-negligible fluorescence. In this paper, we formulate the light emission properties of multilayer graphene composed of tens to hundreds of layers using a transfer matrix method and confirm the method's validity experimentally. We quantitatively explain the measured contrasts of multilayer graphene on SiO2/Si substrates and find sizable corrections, which cannot be classified as incoherent light emissions, to the reflectance of visible light. The new component originates from coherent emission caused by absorption at each graphene layer. Multilayer graphene thus functions as a partial coherent light source of various wavelengths, and it may have surface-emitting laser applications. [ABSTRACT FROM AUTHOR]

Platinum is known as the best catalyst for the hydrogen evolution reaction (HER) but the scarcity and high cost of Pt limit its widespread applicability. Herein, the role of the underlying substrate on the HER activity of dispersed Pt atoms is uncovered. A direct current magnetron sputtering technique is utilized to deposit transition metal (TM) thin films of W, Ti, and Ta as underlying substrates for extremely low loading of Pt (<1.5 at%). The electrocatalytic performance of as‐synthesized samples for the HER is examined in both alkali and acidic media. The results show that despite the low loading of Pt, the Pt/TM catalysts produce hydrogen at a rate comparable to that of pristine bulk Pt. Pt/TM catalysts also display good stability with less than 5% decay in performance after 10 h of continuous HER operation. Based on the computational study, the excellent performance is attributed to the modified electronic properties of the Pt atoms, offering ideal binding energy for HER due to interaction with the underlying substrates. This work provides a robust and industry‐friendly route toward designing efficient catalytic systems for important electrochemical reactions such as HER and others. [ABSTRACT FROM AUTHOR]

Here, we examine the conductance changes associated with the change in spin state in a variety of different structures, using the example of the spin crossover complex [Fe(H2B(pz)2)2(bipy)] (pz = (pyrazol-1-yl)-borate and bipy = 2,2′-bipyridine) and [Fe(Htrz)2(trz)](BF4)] (Htrz = 1H-1,2,4-triazole) thin films. This conductance change is highly variable depending on the mechanism driving the change in spin state, the substrate, and the device geometry. Simply stated, the choice of spin crossover complex used to build a device is not the only factor in determining the change in conductance with the change in spin state. [ABSTRACT FROM AUTHOR]

Platinum is known as the best catalyst for the hydrogen evolution reaction (HER) but the scarcity and high cost of Pt limit its widespread applicability. Herein, the role of the underlying substrate on the HER activity of dispersed Pt atoms is uncovered. A direct current magnetron sputtering technique is utilized to deposit transition metal (TM) thin films of W, Ti, and Ta as underlying substrates for extremely low loading of Pt (

Monolayer graphene absorbs 2.3 percent of the incident visible light. This “small” absorption has been used to emphasize the visual transparency of graphene, but it in fact means that multilayer graphene absorbs a sizable fraction of incident light, which causes non-negligible fluorescence. In this paper, we formulate the light emission properties of multilayer graphene composed of tens to hundreds of layers using a transfer matrix method and confirm the method’s validity experimentally. We quantitatively explain the measured contrasts of multilayer graphene on SiO2/Si substrates and find sizable corrections, which cannot be classified as incoherent light emissions, to the reflectance of visible light. The new component originates from coherent emission caused by absorption at each graphene layer. Multilayer graphene thus functions as a partial coherent light source of various wavelengths, and it may have surface-emitting laser applications.

With piezoelectric small-volume composites gaining importance in smart device applications and nanoindentation being recognized as a versatile method for assessing the properties of layer materials, the present study is focused on the indentation response of the small-volume piezoelectric structures multi-layered composites. In particular, the effects of the nature of the substrate and surrounding materials, on the indentation response of piezoelectric nanocomposites, such as nanoislands, nanowires, and multi-layered composites are investigated. By developing three-dimensional finite element modeling, the complex interaction between the fundamental elastic, piezoelectric and dielectric properties of the piezoelectric materials and the elastic, plastic and electrically conducting or insulating properties of the surrounding materials, on the indentation response of the layered composites is analyzed. It is found that: (i) a substrate material that is elastically stiffer enhances the mechanical indentation stiffness and the electric indentation stiffness while plastic deformation in the substrate causes a reduction in the mechanical and electrical indentation stiffness; (ii) the effective piezoelectric and mechanical indentation stiffnesses of piezoelectric multi-layered composites are bounded by the corresponding characteristics of the bulk material counterparts from which the individual layers are constructed; (iii) electrically conducting surrounding materials produce a softening effect while insulating materials enhance the electrical indentation stiffness resulting in more charges being accumulated during the indentation process.

Investigating coherent acoustic vibrations in nanostructured materials provides fundamental insights into optomechanical responses and microscopic energy flow. Extensive measurements of vibrational dynamics have been performed for a wide variety of nanoparticles and nanoparticle assemblies. However, virtually all of them show that only the dilation modes are launched after laser excitations, and the acoustic bending and torsional motions, which are commonly observed in photoexcited chemical bonds, are absent. Unambiguous identification and refined characterization of these "missing" modes have been a long-standing issue. In this report, we investigated the acoustic vibrational dynamics of individual Au nanoprisms on free-standing graphene substrates using an ultrafast high-sensitivity dark-field imaging approach in four-dimensional transmission electron microscopy. Following optical excitations, we observed low-frequency multiple-mode oscillations and higher superposition amplitudes at nanoprism corners and edges on the subnanoparticle level. In combination with finite-element simulations, we determined that these vibrational modes correspond to out-of-plane bending and torsional motions, superimposed by an overall tilting effect of the nanoprisms. The launch and relaxation processes of these modes are highly pertinent to substrate effects and nanoparticle geometries. These findings contribute to the fundamental understanding about acoustic dynamics of individual nanostructures and their interaction with substrates. [ABSTRACT FROM AUTHOR]

Quantum emitters (QEs) based on deep-level defects in hexagonal boron nitride (hBN) layers are promising alternatives to other qubit-candidates in three-dimensional wide bandgap semiconductors. The two-dimensional (2D) form factor of hBN allows the possibility of near-deterministic placement of quantum emitters and an ease of property-tuning via different means, such as application of strain. However, the 2D nature of hBN also results in a unique set of challenges, including a sensitivity of the QEs to their environment that can influence their different properties, such as their emission frequencies and brightness. In particular, although observed experimentally, theoretical works thus far have ignored substrate-induced modulation of hBN's QE properties. As a result, to date, the magnitude of substrate effects and the underlying mechanism(s) involved in the modulation of QE properties remain unknown. In our density functional theory-based work, we use silicon dioxide as a prototype substrate to demonstrate that the substrate effects can indeed have a significant impact on ground- and excited-state properties of defects responsible for quantum emission. Our analysis shows large structural distortions at the defect sites due to substrate interactions, resulting in significant changes in quantum emission frequencies. These calculations reveal that accounting for substrate effects is critical to the successful use of hBN in quantum sensing and quantum computing. [ABSTRACT FROM AUTHOR]

Here, we examine the conductance changes associated with the change in spin state in a variety of different structures, using the example of the spin crossover complex [Fe(H2B(pz)2)2(bipy)] (pz = (pyrazol-1-yl)-borate and bipy = 2,2′-bipyridine) and [Fe(Htrz)2(trz)](BF4)] (Htrz = 1H-1,2,4-triazole) thin films. This conductance change is highly variable depending on the mechanism driving the change in spin state, the substrate, and the device geometry. Simply stated, the choice of spin crossover complex used to build a device is not the only factor in determining the change in conductance with the change in spin state.

Artificially-induced defects in the lattice of graphene are a powerful tool for engineering the properties of the crystal, especially if organized in highly-ordered structures such as periodic arrays. A method to deterministically induce defects in graphene is to irradiate the crystal with low-energy (<20 keV) electrons delivered by a scanning electron microscope. However, the nanometric precision granted by the focused beam can be hindered by the pattern irradiation itself due to the small lateral separation among the elements, which can prevent the generation of sharp features. An accurate analysis of the achievable resolution is thus essential for practical applications. To this end, we investigated patterns generated by low-energy electron irradiation combining atomic force microscopy and micro-Raman spectroscopy measurements. We proved that it is possible to create well-defined periodic patterns with precision of a few tens of nanometers. We found that the defected lines are influenced by electrons back-scattered by the substrate, which limit the achievable resolution. We provided a model that takes into account such substrate effects. The findings of our study allow the design and easily accessible fabrication of graphene devices featuring complex defect engineering, with a remarkable impact on technologies exploiting the increased surface reactivity. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides are an exciting class of new absorber materials for photovoltaic applications due to their unique optoelectronic properties in the single to few-layer regime. In recent years, these materials have been intensively studied, often utilizing conventional substrates such as sapphire and silicon dioxide on silicon. This study investigates the optical properties of molybdenum disulfide (MoS2) mono-, bi-, and multilayer films prepared by flake exfoliation and atomic layer deposition (ALD). These films are transferred to different photovoltaic relevant carrier-selective contacts, such as titanium oxide, titanium-titanium oxide, molybdenum oxide, and silicon-silicon dioxide reference substrates. Raman and photoluminescence (PL) spectra of single-crystalline exfoliated MoS2 flakes and ALD-grown MoS2 films on different substrates are compared in order to investigate the influence of the different contact materials on the corresponding optical transitions in MoS2. It is demonstrated that the different substrates influence the Raman and PL spectra of MoS2 layers due to doping and charge transfer effects, and similar effects are observed in both the exfoliated single-crystalline flakes and ALD-grown MoS2 layers. [ABSTRACT FROM AUTHOR]

We report dependence of random lasing performance of directly spin-coated multicrystalline thin films of an organic–inorganic hybrid, halide perovskite CH3NH3PbBr3 (MAPbBr3), on different substrates. It was discovered that random lasing performance is strongly dependent on the surface energy properties of the substrate, which determine the morphology and crystallization properties of the spin-coated film, and will consequently determine its optical scattering and emission properties. Using indium–tin oxide (ITO)-coated glass, fused silica, and tricyclo[5.2.1.02,6] decanedimethanol diacrylate (ADCP)-coated fused silica as the substrate materials, we compared the spectroscopic response of the random lasers and thus justified the photophysical mechanisms involved. The modification of the surface properties of the substrate enables controlling of the MAPbBr3 crystallization and leads to the changing of the random lasing properties. The discoveries herein are also important for the construction of other types of laser devices, where the substrate effects should be considered during the design and preparation of the micro-/nano structures. [ABSTRACT FROM AUTHOR]

A wristwatch-style wearable dielectric resonator antenna (DRA) is proposed for the 2.45-GHz ISM band and sub-6 GHz 5G NR bands around 2.5 GHz, such as the commercial band for China Mobile Communications Corporation. The antenna is designed for applications on forearms and ankles. Practical concerns, including the aligning method, platform size, specific absorption rate, and user effects are investigated. Coplanar feeding structure is applied for alignment and isolation. Analysis of the watchband-like substrate is highlighted to avoid performance degradation. Given that platform configurations are not discretionary in actual devices, parasitic loading is introduced to attain desirable substrate effects and suppress unwanted ones. The user-device interplay is studied in light of actual application scenarios. The specific absorption rate is calculated through multilayer biological tissue models. Meanwhile, radiation variation caused by users is estimated based on human phantom models and measurements.

Artificially-induced defects in the lattice of graphene are a powerful tool for engineering the properties of the crystal, especially if organized in highly-ordered structures such as periodic arrays. A method to deterministically induce defects in graphene is to irradiate the crystal with low-energy (

We report dependence of random lasing performance of directly spin-coated multicrystalline thin films of an organic–inorganic hybrid, halide perovskite CH3NH3PbBr3 (MAPbBr3), on different substrates. It was discovered that random lasing performance is strongly dependent on the surface energy properties of the substrate, which determine the morphology and crystallization properties of the spin-coated film, and will consequently determine its optical scattering and emission properties. Using indium–tin oxide (ITO)-coated glass, fused silica, and tricyclo[5.2.1.02,6] decanedimethanol diacrylate (ADCP)-coated fused silica as the substrate materials, we compared the spectroscopic response of the random lasers and thus justified the photophysical mechanisms involved. The modification of the surface properties of the substrate enables controlling of the MAPbBr3 crystallization and leads to the changing of the random lasing properties. The discoveries herein are also important for the construction of other types of laser devices, where the substrate effects should be considered during the design and preparation of the micro-/nano structures.

Thin polymeric coatings are commonly used for altering surface properties and modulating the interfacial performance of materials. Possible contributions from the substrate to the interfacial forces and effects are, however, usually ignored and are not well understood, nor is it established how the coating thickness modulates and eventually eliminates contributions from substrates to the van der Waals (vdW) interfacial force. In this study we quantified, by colloid-probe atomic force microscope (AFM) and by theoretical calculations, the interfacial vdW contributions from substrates acting through ethanol plasma polymer (EtOHpp) coatings of a range of thicknesses on Au and Si bulk materials. In approach force curves against EtOHpp-coated Au substrates the magnitude of the vdW force decreased as the EtOHpp coating thickness increased to 18 nm and then plateaued with further increases in coating thickness, providing direct evidence for a contribution to the total interfacial vdW force from the Au substrate acting through thin coatings. The experimental observations accord with theoretical calculations of the thickness dependence of Hamaker coefficients derived from rigorous simulation using the Lifshitz theory. In addition, the measured forces agree well with theoretical predictions including correction for finite roughness. Thus, our experimental and theoretical results establish how the thickness of polymer thin film coatings modulates the total interfacial vdW force and how this can be used to tune the net vdW force so as to either contain a large substrate contribution or arise predominantly from the polymeric overlayer. Our findings enable rational design of coating thickness to tailor interfacial interactions and material performance. [ABSTRACT FROM AUTHOR]

Dielectric nanoparticles are expected to complement or even replace plasmonic nanoparticles in many optical and optoelectronic applications, because they exhibit small absorption losses and support strong electric and magnetic resonances simultaneously. Dielectric nanoparticles need to be deposited on various substrates in many applications. Understanding the substrate effect on the electromagnetic resonances of dielectric nanoparticles is of great importance for engineering their resonance properties and designing optical devices. In this study, moderate‐refractive‐index cuprous oxide nanospheres with uniform sizes and shapes are synthesized. The scattering spectra and images of the nanospheres deposited on three types of substrates are analyzed experimentally and theoretically. When supported on indium tin oxide–coated glass slides and Si wafers, the color of the nanospheres varies from blue, cyan, green, yellow, orange and red, covering almost the entire visible region. When deposited on gold films, the electromagnetic resonances of the nanospheres redshift intensively and a new effective magnetic resonance mode appears. The enhanced Raman scattering reveals that large electromagnetic field enhancements are produced in the gap region between the nanosphere and the substrate. The results shed light on the manipulation of the electromagnetic responses of dielectric nanoparticles and the design of dielectric metamaterials in the presence of various substrates. [ABSTRACT FROM AUTHOR]

• For the first time, first-principles calculations are used to predict the lattice thermal conductivity of free-standing monolayer XS2 (X = mo and W) and monolayer XS2 supported on SiC (0001) and ZnO (0001) substrates. • The lattice thermal conductivity of monolayer XS2 supported on SiC (0001) and ZnO (0001) substrates show a significant decrease, and the decrease is even greater for the monolayer XS2 supported on ZnO (0001) substrates, reaching about 65–70 %. • The substrate drives softening of the acoustic branch, making the low-frequency phonon group velocity decrease and the three-phonon scattering enhance. • From the perspective of atomic bonding, the substrate breaks the symmetry of bonding of monolayer XS2, which leads to the increase of phonon anharmonicity and ultimately to a decrease in thermal conductivity of monolayer XS2. Thermoelectric materials have properties such as direct conversion of waste heat into electricity and environmental friendliness, which make them promising for renewable energy utilization, however, the lower conversion efficiency limits the large-scale application of thermoelectric materials. Monolayer transition metal dichalcogenides (TMDs) are candidates for thermoelectric materials due to their high power factor, but their higher thermal conductivity (TC) limits the further improvement of the figure of merit (ZT). Here, we employ first-principles calculations and solve the Boltzmann transport equation (BTE) to compare the lattice TC of free-standing monolayer XS 2 (X = Mo and W) and monolayer XS 2 supported on SiC (0001) and ZnO (0001) substrates. We find that the lattice TC of monolayer XS 2 supported on SiC (0001) and ZnO (0001) substrates are sharply reduced. Especially supported on the ZnO (0001) substrate, the lattice TC of XS 2 reduce by 65 %–70 %, which is expected to improve the thermoelectric properties of monolayer XS 2. In addition, we report the underlying cause of this significant reduction in TC. Firstly, the substrate drives softening of the acoustic branch, which leads to a decrease of phonon group velocity in the low-frequency and an enhancement of the three-phonon scattering. Then, the asymmetric bonding of XS 2 is induced by the substrates, which enhance phonon anharmonicity and reduce the phonon lifetime. Our results demonstrate that the lattice TC of monolayer XS 2 can be tuned by adjusting the substrate, which has certain reference values for the thermoelectric design of XS 2. SiC (0001) and ZnO (0001) substrates break the symmetry of the monolayer XS 2 (X = Mo and W) bonding, resulting in an increase in phonon anharmonicity, which reduces the contribution of the low-frequency acoustic branch of monolayer XS 2 to the thermal conductivity. [Display omitted] [ABSTRACT FROM AUTHOR]

• Initial coating preferentially formed on defects and scratches, and around bubbles on the surface. • Induction time was influenced by initial deposition, and not just by local composition, as demonstrated experimentally. • Coating deposition was favored for areas with a high local current density. The purpose of this study was to develop a detailed understanding of the initial stages of coating electrodeposition. Of particular interest were the changes that take place during the induction period before a steep change in the voltage at constant current is observed. Experiments designed to elucidate the role of concentration buildup clearly showed that a local change in concentration was not solely responsible for the observed induction period. This conclusion is further supported by experiments where the induction time at a specified current was observed to vary with the type of substrate used for deposition. Consequently, scanning electron microscopy was used to study the morphology of the initial deposit on different substrate surfaces including bare steel, galvanized steel, and phosphated steel. It was found that the initial film formed preferentially at specific locations on the metal surfaces, such as on defects or scratches, where the local current density was likely to be higher. The initial film also appeared to form around gas bubbles that were present on the substrate surface. Preferential film deposition at areas of high local current density was observed directly in experiments with intentionally scratched surfaces. The additional insight provided by this study will help to improve our ability to model accurately the early stages of E-coat deposition and, eventually, the accuracy of large-scale simulations for process performance prediction and optimization. [ABSTRACT FROM AUTHOR]

Diamond is the new substrate of choice for high power/frequency AlGaN/GaN high electron mobility transistors (HEMTs). Due to its high thermal conductivity, diamond presents improvements in removing concentrated heat from the electron channel, a necessity for reliable performance of these devices. Previous thermal performance comparison studies of GaN-on-SiC and GaN-on-diamond devices are limited to devices with often large and identical heat source regions due to modeling and experimental limitations. Analytical procedure presented in this study overcome these limitations and provide a more comprehensive thermal spreading performance analysis of GaN-on- SiC and GaN-on-diamond HEMTs with localized Joule heating. Important thermal spreading factors such as thermal boundary resistance, GaN buffer layer thickness, and multifinger arrangements are also investigated in this study. [ABSTRACT FROM AUTHOR]

Glass fragments are often recovered from garments worn by the authors of certain types of crimes and are useful as they present strong connections to the scene at both the source and activity level. It is known that the transfer of glass fragments is impacted when recipient garments are dampened, such as by rain, however, the details of the effect are not clear. This research aimed to determine the impact of substrate dampness on glass retention. Across the three test garments, a cotton t-shirt was found to increase in retentiveness with increasing dampness, while a wool/polyester blend jumper and a cotton hoodie were both found to increase only to a point, before decreasing again when the garment was saturated. This is attributed to the construction of the fabrics, as it does not appear to be related to the identity of the textile itself. It was also found that the size distribution of fragments changed with dampness. All the garments retained a smaller proportion of fragments less than 0.5 mm in size when saturated or dampened than when dry, along with an increase in the proportion of fragments in the 1–1.5 mm and greater than 1.5 mm size categories. These results indicate that is important to consider the impact of substrate dampening when relevant, and that this consideration must be done holistically as different substrates respond to dampening in different ways. It also indicates that consideration of the size distribution in fragment populations may reveal additional information in complex scenarios. • Not all garments exhibit consistent behaviour in all dampening conditions. • Differences between substrates seem to be linked to fabric construction, not textile type. • Saturated garments retain a smaller proportion of small fragments and more large ones. [ABSTRACT FROM AUTHOR]

The substitution of petroleum-based polymers with naturally derived biopolymers may be a good alternative for the conservation of natural fossil resources and the alleviation of pollution and waste disposal problems. However, in order to be used in a wide range of applications, some biopolymers’ properties should be enhanced. In this study, biocompatible, non-toxic, and biodegradable chitosan (CS) film and CS reinforced with 10 wt% of cellulose nanocrystals (CN–CS) were coated with amorphous hydrogenated carbon layers (a–C:H) of different thickness. To investigate the effect of the nano-reinforcement on the a–C:H layer applied, mild radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) was used to coat the CS and its CN–CS bio-nanocomposite film. Both the surface characteristics and the chemical composition were analyzed. The surface morphology and wettability were examined by ex-situ atomic force microscopy (AFM) and contact angle measurements (CA), respectively. Hereby, the relationship between sp2/sp3 ratios on a macroscopic scale was also evaluated. For the investigation of the chemical composition, the surface sensitive synchrotron X-ray radiation techniques near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) as well as diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) were used.

We investigated the optical behaviors of vanadium dioxide (VO 2 ) films through the semiconductor-to-metal (STM) phase transition using spectroscopic ellipsometry. Correlations between film thickness and refractive index were observed resulting from the absorbing nature of these films. Simultaneously analyzing data at multiple temperatures using Kramers-Kronig consistent oscillator models help identify film thickness. Nontrivial variations in resulting optical constants were observed through STM transition. As temperature increases, a clear increase is observed in near infrared absorption due to Drude losses that accompany the transition from semiconducting to metallic phases. Thin films grown on silicon and sapphire substrate present different optical properties and thermal hysteresis due to lattice stress and compositional differences. [ABSTRACT FROM AUTHOR]

Graphene has been considered as a promising active material for electric double-layer capacitors (EDLCs), primarily owing to its extraordinary monolayer properties, whereas the interfacial behaviors are conspicuously impacted by underlying substrates. In this work, substrate effects on the interfacial wettability, EDL structure, and capacitive behavior of graphene-based EDLCs are delineated with numerical simulation. Unlike previous studies, a partial wetting transparency of topmost graphene is recognized for hydrophilic supports. In particular, a virtually identical capacitance is demonstrated for graphene with various supports, albeit the substantially different EDL structures stemmed from substrate effects. The achieved invariant capacitance is prominently attributed to the counterbalancing correlations between ions and proximal solvents, going beyond traditional views of modulating capacitance preferentially through ion structural evolutions. Specifically, the suppressed permittivity of apparently ordered water dipoles (i. e. detrimental solvent effects) attenuates the beneficial ionic influences (i. e. reinforced population and closer approach) on shielding the external electric fields. The as-obtained findings demonstrate the paramount importance of the substrate in mediating interfacial behaviors within electrified EDLC systems and highlight that exploiting the pivotal interplay between ions and solvents could be a novel avenue to further manipulate electrochemical performances. [ABSTRACT FROM AUTHOR]

Due to their exceptional electrical, thermal, and optical properties, low-dimensional (LD) materials are very promising for many applications, such as nanoelectronic devices, energy storage, energy conversion, and thermal management. The thermal performance of LD materials is often an important consideration in these applications. Although freestanding LD materials exhibit interesting thermal properties, they are almost never used in such a form. Instead, they are often integrated into a certain environment; for example, in a composite material or on a substrate. Due to the large surface-to-volume ratio of LD materials, the environment usually has a strong impact on the thermal transport properties of these materials. The thermal behavior of the LD materials can be completely different from the freestanding form. The effect of environmental perturbation on thermal transport properties has recently attracted a lot of research interest. In this article, we aim to provide a comprehensive review of how the typical external perturbations, including tensile strain, substrate, and clustering, can affect the thermal transport properties of LD materials. Emphasis will be placed on how these perturbations affect the lattice structure, phonon dispersion, lattice anharmonicity, and thermal conductivity. We will also summarize the achievements and the remaining challenges on this research topic. [ABSTRACT FROM PUBLISHER]

Classical molecular dynamics simulations with modified embedded atom method model has been carried out to understand the interfacial behavior of a gold(Au) nano-cluster on a silicon(Si) surface. For illustration, a gold nano-cluster (NC) consisting of 108 atoms has been chosen on the Si (001) surface. We have investigated on the process of melting of this NC, the temperature dependent intermixing of Au and Si, and the diffusion of Au atoms into the Si substrate. It has been observed that the NC becomes semi-spherical around the room temperature and the melting process started around 450 K. In order to examine the substrate effect on the melting point temperature of the gold NC, a similar NC has been studied in vacuum. The melting point temperature of this free NC is found to be around 480 K. The observed suppression of melting temperature (by ~30 K) for the supported NC can be understood in terms of substrate induced change in morphology. We observe inter-diffusion between gold and silicon atoms for temperatures greater than 650 K. [ABSTRACT FROM AUTHOR]

Investigations of the fundamental properties of graphene have leveraged the versatility of the CMOS fabrication platform early on by using oxidized semiconductor substrates with a highly doped back gate to behave as a metal gate down to cryogenic temperatures. For future applications at room temperature and co-integration with standard silicon circuits, standard substrates should be considered and modeled. Therefore, we investigate the impact of using standard lightly doped silicon as a back gate by building upon existing drift-diffusion models for the 3-terminal monolayer graphene field effect transistor. Typical measurements of the back-gate transfer characteristics exhibit a kink/plateau around 0 V. This effect is explained by the proposed model and corresponds to a loss of gate control occurring during the formation of the depletion layer in the substrate. The impact is increased at low temperature, for thin oxides or under transient conditions. [ABSTRACT FROM AUTHOR]

Monolayer MoS 2 is an emerging two-dimensional semiconductor with wide-ranging potential applications in the next generation electronic and optoelectronic devices. Understanding the influences of the supporting substrates on the physical properties of grown MoS 2 is an important step toward its applications. Here we synthesized two typical rhomboid shaped MoS 2 on MoO 2 and triangle shaped MoS 2 on SiO 2 /Si substrates and characterized them by multiple means of X-Ray Photoemission Spectroscopy, Atomic Force Microscopy, Electrostatic Force Microscopy, Raman and Photoluminescence techniques. We found that triangle shaped MoS 2 exhibits different core level spectra compared with rhomboid shaped MoS 2 , attributed to dissimilar charge transfer with the underlying SiO 2 substrate. Interestingly, the triangle shaped MoS 2 single crystals exhibit distinct electrostatic and photoluminescence properties at center and edges. The underlying mechanism is proposed that partial decoupling of MoS 2 at edges from SiO 2 substrate induces different doping level and strain effects, resulting in anomalous physical properties at edges. The results reported here demonstrate that doping and strain effects induced by substrates have a significant influence on physical properties of monolayer triangle shaped MoS 2 ，which can be generally applicable to other transition metal dichalcogenides materials. [ABSTRACT FROM AUTHOR]

Biodiversity patterns (alpha-, beta- and gamma-diversity, abundance, community structure) of oribatid mites were investigated in six sites in a tropical montane forest in the Central Highlands region of Southern Vietnam. The diversity patterns in oribatid communities were investigated in relation to substrate (leaf litter vs. soil) and forest type (conifer-dominated vs. broadleaf-dominated). The density and species richness of oribatid mites in the soil were greater in the conifer-dominated sites. The community structure was also different between conifer-dominated and deciduous tree-dominated sites. Species from families Galumnidae, Otocepheidae, Haplozetidae and Scheloribatidae were dominant in each plot. In conclusion, density and species richness of Oribatida were influenced by both forest type and substrate, and community composition was strongly influenced by the substrate. [ABSTRACT FROM AUTHOR]

Single layers of transition metal dichalcogenides (TMDCs), such as WSe 2 have gathered increasing attention due to their intense electron-hole interactions, being considered promising candidates for developing novel optical applications. Within the few-layer regime, these systems become highly sensitive to the surrounding environment, enabling the possibility of using a proper substrate to tune desired aspects of these atomically-thin semiconductors. In this scenario, the dielectric environment provided by the substrates exerts significant influence on electronic and optical properties of these layered materials, affecting the electronic band-gap and the exciton binding energy. However, the corresponding effect on the luminescence of TMDCs is still under discussion. To elucidate these impacts, we used a broad set of materials as substrates for single-layers of WSe 2 , enabling the observation of these effects over a wide range of electrical permittivities. Our results demonstrate that an increasing permittivity induces a systematic red-shift of the optical band-gap of WSe 2 , intrinsically related to a considerable reduction of the luminescence intensity. Moreover, we annealed the samples to ensure a tight coupling between WSe 2 and its substrates, reducing the effect of undesired adsorbates trapped in the interface. Ultimately, our findings reveal how critical the annealing temperature can be, indicating that above a certain threshold, the heating treatment can induce adverse impacts on the luminescence. Furthermore, our conclusions highlight the influence the dielectric properties of the substrate have on the luminescence of WSe 2 , showing that a low electrical permittivity favours preserving the native properties of the adjacent monolayer., (© 2023 IOP Publishing Ltd.)

Investigating coherent acoustic vibrations in nanostructured materials provides fundamental insights into optomechanical responses and microscopic energy flow. Extensive measurements of vibrational dynamics have been performed for a wide variety of nanoparticles and nanoparticle assemblies. However, virtually all of them show that only the dilation modes are launched after laser excitations, and the acoustic bending and torsional motions, which are commonly observed in photoexcited chemical bonds, are absent. Unambiguous identification and refined characterization of these "missing" modes have been a long-standing issue. In this report, we investigated the acoustic vibrational dynamics of individual Au nanoprisms on free-standing graphene substrates using an ultrafast high-sensitivity dark-field imaging approach in four-dimensional transmission electron microscopy. Following optical excitations, we observed low-frequency multiple-mode oscillations and higher superposition amplitudes at nanoprism corners and edges on the subnanoparticle level. In combination with finite-element simulations, we determined that these vibrational modes correspond to out-of-plane bending and torsional motions, superimposed by an overall tilting effect of the nanoprisms. The launch and relaxation processes of these modes are highly pertinent to substrate effects and nanoparticle geometries. These findings contribute to the fundamental understanding about acoustic dynamics of individual nanostructures and their interaction with substrates.

It is demonstrated that the luminescence efficiency of monolayers composed of MoS2, WS2, and WSe2 is significantly limited by the substrate and can be improved by orders of magnitude through substrate engineering. The substrate affects the efficiency mainly through doping the monolayers and facilitating defect-assisted nonradiative exciton recombinations, while the other substrate effects including straining and dielectric screening play minor roles. The doping may come from the substrate and substrate-borne water moisture, the latter of which is much stronger than the former for MoS2 and WS2 but negligible for WSe2. Using proper substrates such as mica or hexagonal boron nitride can substantially mitigate the doping effect. The defect-assisted recombination depends on the interaction between the defect in the monolayer and the substrate. Suspended monolayers, in which the substrate effects are eliminated, may have efficiency up to 40% at room temperatures. The result provides useful guidance for the rational design of atomic-scale light emission devices. [ABSTRACT FROM AUTHOR]

Modification of the plasmonic response of a metal nano‐object due to interaction with a substrate is experimentally investigated measuring the quantitative optical extinction spectra of individual nano‐objects with various elongated shapes (bipyramids and rods) deposited on a dielectric (silica) or absorbing (carbon) membrane. Apart from the expected dependence of the nanoparticle surface plasmon resonance (SPR) frequency on the nature of the substrate, large substrate and particle shape dependent modifications of its SPR width are demonstrated. These dependencies are ascribed to strong localization of the electromagnetic field associated with the longitudinal SPR of an elongated nano‐object around its tips, leading to different interaction with the substrate depending on the particle shape and 3D orientation relative to the substrate. Both parameters have been precisely determined by electron tomography, permitting excellent reproduction of the experimental data. Experiments performed on silver‐encapsulated bipyramids, whose shape evolves from a pyramidal one towards a cylindrical one, further confirm this effect. [ABSTRACT FROM AUTHOR]

The effects of topographic variables (elevation above sea level, slope position, topographic (wetness) index, and global solar radiation) on mite abundances and on quantitative composition of Oribatida communities in soil and litter have been studied in six sites along a hill slope in a tropical lowland forest in the Bu Gia Map National Park, Southern Vietnam. A positive relationship existed between abundance and species richness of Oribatida in soil cores, and global solar radiation (W h m) which quantifies the total sun energy available to the local ecosystem. There was no significant relationship between abundance of Mesostigmata and topographic variables. The Oribatida community composition in soil and in litter was significantly different, with a large number of species unique to either litter or soil. The canonical correspondence analysis (CCA) showed that the topographic variables together explained 75 % (in litter) and 83 % (in soil) of the variation in Oribatida community structure. The species-topography relationship was globally significant in the litter, weaker in the soil; the eigenvalue of the CCA axis 1 (related to elevation and global solar radiation) was significant in both substrates. CCA ordinations identified groups of species associated with high landscape positions (hill crest, high elevation, high global solar radiation) versus species associated with low-lying landscape positions, where moisture tends to accumulate (hill footslope, low elevation, low solar radiation, high topographic index values). The importance of relief and geographical position for soil Oribatida is discussed. [ABSTRACT FROM AUTHOR]

A growing literature directly connects historical demographic patterns to the emergence of new dialects or languages. This article moves beyond the usual macro view of such data, relying on simple numbers of speakers and similar information, to focus on the input to new generations of speakers in a so-called substrate setting. The English now spoken in eastern Wisconsin shows a range of influences from German, and we work to reconstruct the kinds of input that the first large generation of English L1, mostly monolingual English-speaking children in the community,likely received at the level of the household and the individual. Evidence strongly suggests that most children in the community would have been widely exposed to heavily German-influenced English, in part due to a critical moment of shift from German to English as the home language in many households. [ABSTRACT FROM AUTHOR]

The lattice density functional theory (LDFT) is used to describe the substrate effect on the phase behavior of polymer brush grafted on different substrates. The LDFT predicts that: both attractive and repulsive interactions between the substrate and the polymer chains have effects on the thickness of brushes; when the short-range monomer-substrate interaction is larger than a certain value, the thickness and density profiles of polymer brushes almost do not change. And also an attractive substrate can increase the critical grafting density of pancake to brush transition. For temperature responsive polymer brushes, the temperature transition points are almost the same with different substrates, however, an attractive substrate can increase the swelling ratio and a repulsive substrate can decrease the swelling ratio. We also find that an increasing grafting density can decrease the substrate effect on the swelling behavior of temperature responsive polymer brushes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Use of continuum crystal plasticity models for Berkovich indentation of Cu crystals. [•] Effect of crystallography on hardness evolutions in thin films during nanoindentation. [•] Evolution of the indentation modulus with indented film depending on the crystallography. [Copyright &y& Elsevier]

Desiccation cracking is ubiquitous in many materials of practical importance, such as in mud, clay soil, pavement, and concrete, and understanding its dynamics and formation is essential for developing an effective means of its prevention or utilization. We report on a phenomenological investigation aimed at delineating the effect of a coarse-textured substrate on the cracking dynamics and morphology of an overlying kaolinite clay layer. Drying experiments were carried out using a glass container mounted on a digital balance, packed with a thin layer of kaolinite clay overlying seven types of sand that differed in their particle size distributions. An automatic imaging system recorded the dynamics of cracking at the evaporating surface. Dynamic analysis suggests a decreased duration of cracking with increased substrate particle size and substrate-independent initial crack propagation. Analysis of the cracking morphology indicates a decreased crack density and larger crack length, and an increased crack width mean and standard deviation with increased substrate particle size. Scanning electron microscopy results, used to study the extent of cracking over various length scales, indicate that only macroscopic cracks formed on the kaolinite clay surface. Fractal and density correlation function analysis of the final crack networks indicate the dependency of the fractal dimension on the substrate particle size, and a crossover length scale ξ that separates the fractal regime from the uniform crack density regime. For length scales greater than ξ, the density correlation function asymptotically approaches the crack density at the surface of the clay. [ABSTRACT FROM AUTHOR]

Despite the fact that liquid fuel spills present a potential fire hazard in numerous industrial and residential settings there has been minimal research conducted to understand the spill and burning dynamics of these types of scenarios (Gottuk et al., NRL/MR/6180-00-8457, 2001; Putorti, NIJ-604-00, 2001; Mealy et al., NIJ-2008-DN-BX-K168, 2010; Ma et al., Fire Technol 40:227-246, 2004). While the findings of these studies were significant in that they demonstrated a substantial decrease in the peak fire size achieved in spill fire scenarios compared to pool fires, the empirical data sets collected were not sufficient to fully understand the phenomena causing this reduction. In general, both studies attributed the decrease to thermal losses to the substrate but indicated that further investigation was required. In order to address this general lack of empirical data, a research program was conducted to characterize fuel spill fire dynamics with respect to the key variables that potentially impact these types of fires. A discussion of the test results is presented in two parts: the first being the development of a liquid spill, specifically spill depths and spill progression, and the second being fuel burning dynamics, specifically the impacts of substrate, ignition delay, and substrate temperature. The development of a spill and the associated liquid depths are described for various fuels and fuel simulants, whose properties provide bounding spill scenarios for most fuels of interest. The burning dynamics of various fuel spill scenarios are evaluated relative to numerous substrates, ignition delay times ranging from 30 s to 300 s, and substrate temperatures ranging from 12°C to 38°C (54°F to 100°F). The impact of these variables was evaluated relative to the heat release and mass burning rates measured during these tests. [ABSTRACT FROM AUTHOR]

Considering germanium (Ge) material with one of the highest refractive index and semi-metal properties, the light scattering properties of Ge trimer and its metasurface structures are studied theoretically in this paper. In contrast to other dielectric materials, for which the magnetic-type resonance is commonly dominant, Ge has a strong electric-type resonance due to its semi-metal properties, which can be seen in the visible and near-infrared spectral range. The influence of the unique feature on the Fano line shapes can be reflected in the scattering spectra. Simultaneously, taking into account the substrate effects, we show that the behavior of the light scattering anisotropy exhibits a big difference in the presence of the different substrates, which can be manipulated to some extent. The results can provide a feasible way to control the "hot spots" in the local light field. Our work in this paper shows that Ge trimers as an excellent candidate can be applied to enhanced spectroscopy, directional sources, and other nanometer photonic devices, as well as on metasurface structures. • By light scattering from Ge trimer and its metasurface structures, good spectral line shape can be obtained. • The hot spots of scattering field can be effectively manipulated and located based on the substrate effects. • Metasurface structures formed by Ge trimer arrays can lead to scattering spectra with the band-pass and band-stop. • The enhanced backward scattering from Ge trimer metasurface at 785 nm wavelength is significant to the SERS application. [ABSTRACT FROM AUTHOR]

Instrumented indentation is a technique that can be used to measure the elastic properties of soft thin films supported on stiffer substrates, including polymer films, cellulosic sheets, and thin layers of biological materials. When measuring thin film properties using indentation, the effect of the substrate must be considered. Most existing models for determining the properties of thin films from indentation measurements were developed for metal and dielectric films bonded to semiconductor substrates and have been applied to systems with film-substrate modulus ratios between 0.1 and 10. In the present work, flat punch indentation of a thin film either bonded to or in contact with a substrate is examined using finite element modeling. A broad range of film-substrate modulus ratios from 0.0001 to 1 are investigated. As the substrate is effectively rigid compared to the film when the film-substrate modulus ratio is less than 0.0001, the results are also useful for understanding systems with lower film-substrate modulus ratios. The effects of the contact radius, film thickness, elastic properties, and friction between the film and the substrate on the measured stiffness were quantified using finite element modeling in order to understand how the elastic properties of the film can be extracted from indentation measurements. A semi-analytical model was developed to describe the finite element modeling results and facilitate the use of the results to analyze experimental measurements. The model was validated through analysis of indentation measurements of thin polyethylene sheets that were supported on substrates of various stiffness. [ABSTRACT FROM AUTHOR]

Atomically thin two-dimensional (2D) materials are excellent candidates for utilization as a solid lubricant or additive at all length scales from macro-scale mechanical devices to micro/nano-electromechanical systems (MEMS/NEMS). In such applications, wear resistance of ultrathin 2D materials is critical for sustained lubrication performance. Here, we investigated the wear of fluorinated graphene (FG) nanosheets deposited on silicon surfaces using atomic force microscopy (AFM) and discovered that the wear resistance of FG improves as the FG thickness decreases from 4.2 to 0.8 nm (corresponding to seven layers to single layer) and the surface energy of the substrate underneath the FG nanosheets increases. On the basis of density function theory (DFT) calculations, the negative correlation of wear resistance to FG thickness and the positive correlation to substrate surface energy could be explained with the degree of interfacial charge transfer between FG and substrate which affects the strength of FG adhesion to the substrate.

Diamond-like carbon (DLC), a thin amorphous carbon film, has many uses in tribological systems. Exploiting alternative substrates and interlayers can enable the control of the hardness and modulus of the multilayer system and improve wear or friction properties. We used XPS and atomic force microscopy to examine DLC that had been concurrently coated on an epoxy interlayer and a steel substrate by plasma-enhanced chemical vapour deposition. sp2/sp3 ratios were calculated both by the deconvolution of the XPS C1s line and by the analysis of the C KLL Auger spectrum. Altering the substrate causes changes in the carbon bonding configuration, evident with the same trend through both analysis methods, although with differing absolute values, related to hydrogen and oxygen content. There is significant variation in the microscale surface texture, exhibited by both average roughness values and size and uniformity of surface asperities. This suggests that alteration to the film surface structure is a factor to be considered in addition to interface adhesion, hardness and elastic modulus in investigating substrates and interlayers for tribological coatings. Examination of a DLC film separately produced on a steel substrate, in comparison with that produced concurrently with a DLC coating on epoxy, shows the possibility of effects on the chemistry of the film through transfer of material from adjacent samples within the plasma deposition, related to heating, outgassing or sputtering processes. The possibility of such contamination has implications in coating parameter design and coating of multiple samples with plasma-enhanced chemical vapour deposition. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]