Substrate Surface Research Articles

Optimizing the Morphology and Optical Properties of MoS2 Using Different Substrate Placement: Numerical Simulation and Experimental Verification

The prerequisite for rapid and steady development of TMDC-based optoelectronic devices is high efficiency in materials preparation, which relies on a mature synthesis technique and optimized production conditions. Visualization based on numerical simulation, which illustrates the impact of growth parameters on deposited products, is helpful to understand formation mechanisms and modify growth conditions. In this work, we construct two models with two different substrate placements, where the substrate is parallel or perpendicular to gas flow direction. The simulation results show more velocity distribution uniformity across a wider range from −1.4 cm to 1.4 cm for vertically placed (VP) compared to horizontally placed (HP) substrates. The calculated average velocities of 0.048, 0.053, 0.078, 0.137, and 0.391 cm/s along five different positions on the VP substrate are greater than the values of 0.027, 0.026, 0.025, 0.023, and 0.036 cm/s on the HP substrate. Comparing the precursor concentration distributions on both substrates, it is observed that the S molar concentration gradient on both substrates is negligible and the uniform Mo molar concentrations from z = −1.4 cm to 2.0 cm on the VP substrate ensure minimal change in the S/Mo ratio, which contributes to forming single-morphology domains. Furthermore, increasing the distance between the precursor inlets and the VP substrate decreases the amount of molecules on the substrate surface, achieving near-stoichiometry and promoting monolayer deposition. This is verified by the experimental result, which showed gentle morphological transformation on the VP substrate from a truncated triangle to a hexagon, and then back to a truncated triangle. By contrast, the multi-morphology and thickness of MoS2 on the HP substrate result from the complex Mo concentration along the flow direction. Moreover, PL intensities of the MoS2 domains deposited on the VP substrate are enhanced by 11.9-fold compared to the average intensity on the HP substrate. This result indicates the MoS2 grown on the VP substrate has less intrinsic defects than that grown on the HP substrate. The combination of numerical simulation with experimental methods facilitates the visualization of invisible growth conditions, which provides effective guidance for using simulation results for other TMDC materials.

AB-Type Zwitterionic Hydrogel Paint.

Zwitterionic hydrogels exhibit excellent nonfouling and hemocompatibility. However, the practical application of these materials as antifouling coatings for biomedical devices is hindered by several key challenges, including the harsh preparation conditions and the weak coating stability. Here, we present a two-component zwitterionic hydrogel paint for the in situ preparation of robust zwitterionic hydrogel coatings on various substrate surfaces without UV assistance. It is performed by the curing and adhesion of a zwitterionic hydrogel simultaneously through the ring opening reaction of epoxy and amino inspired by the successful commercial two-component epoxy structural glue. The obtained AB-type PSBMA coating can withstand water flow velocities of up to 15 m/s and still maintain its structural integrity and functional stability. It is noteworthy that the coating preparation process does not require the use of any organic solvent, which greatly simplifies the postprocessing steps for its application in medical devices. Moreover, the coating not only resists bacterial and cell adhesion but also exhibits favorable hemocompatibility. This approach offers a novel concept for the design of zwitterionic hydrogel coatings for biomedical devices.

Stretchable, Self-Healable, and Durable Conductive Elastomer Derived from a Rationally Designed Covalently Cross-Linked Network.

Silver nanowire (Ag NW)-based elastic conductors have been considered a promising candidate for key stretchable electrodes in wearable devices. However, the weak interface interaction of Ag NWs and elastic substrates leads to poor durability of electronic devices. For everyday usage, an additional self-healing ability is required to resist scratching and damage. Therefore, robust Ag NW-based elastic conductors possessing stretchability, self-healing, and stability are highly desirable and challenging. Here, we present a universal interface tailoring strategy that introduces thiols onto the dynamically cross-linked elastic substrate surface. The surface thiol groups strongly interact with Ag NWs through Ag-S bonds, forming the stable conductive layer on the elastic substrate. At elevated temperatures, the Ag NWs are partially embedded in the surface of the elastic substrate and a buffer layer is formed to release the concentrated stress. As a result, the formed Ag NW-based elastic conductor displays the combination of good conductivity, high stretchability (>1000%), efficient self-healing capability (>95%), and remarkable stability. Besides, the Ag NW-based elastic conductor combining the good properties mentioned above is suitable for fabricating a sensitive and durable strain sensor against cyclic strain. The presented strategy can be considered a versatile and effective route to generating other surface thiol-rich covalently cross-linked elastomers with dynamic disulfide bonds.

The Effect of Accessibility of Insoluble Substrate on the Overall Kinetics of Enzymatic Degradation

ABSTRACTThe enzymatic reaction kinetics on cellulose and other solid substrates is limited by the access of the enzyme to the reactive substrate sites. We introduce a general model in which the reaction rate is determined by the active surface area, and the resulting kinetics consequently reflects the evolving relationship between the exposed substrate surface and the remaining substrate volume. Two factors influencing the overall surface‐to‐volume ratio are considered: the shape of the substrate particles, characterized by a single numerical parameter related to its dimensionality, and the distribution of the particle sizes. The model is formulated in a form of simple analytical equations, enabling fast and efficient application to experimental data, and facilitating its incorporation into more detailed and complex models. The application of the introduced formalism exploring its potential to account for the observed reaction rate is demonstrated on two examples: the derivation of particle size distribution from experimentally determined reaction kinetics, and the prediction of reaction slowdown from experimental particle size distribution.

Dynamics of antibiotic resistance genes and bacterial community structure within substrate biofilms

Biofilms that develop on the surface of substrates are critical for treating wastewater. The accumulation of antibiotic resistance genes (ARGs) within these biofilms is particularly noteworthy. Despite their importance, studies that focus on biofilms attached to substrate surfaces remain scarce. This investigation explored the prevalence and succession of ARGs and microbial dynamics in biofilms on different substrates (ceramic, biomass filter, and steel slag) versus water biofilms over a year. Results showed distinct differences in ARG profiles between water and substrate biofilms. Multidrug ARGs constituted 39.14–46.73% of all ARGs in the substrate biofilms, with macrolide ARGs making up 11.98–14.52%. Seasonal variations influenced the diversity of the ARGs, notably increasing during the spring. The neutral community model suggested that the ARG assembly was dominantly driven by stochastic process. Proteobacteria, Actinobacteria and Campylobacter emerged as the predominant phyla within these biofilms. The microbial community distribution was predominantly influenced by ammonium nitrogen (NH4+-N) (R2 = 0.4113), temperature and total nitrogen (TN). Notably, temperature exerted a critical impact on the microbial community distribution (P = 0.001), identifying it as the principal factor for spatial arrangement. Furthermore, the structural variations of ARGs were primarily driven by total organic carbon (TOC) (R2 = 0.3988), temperature, oxidation-reduction potential (ORP) and NH4+-N. Our findings provided new insights into the optimization of substrate selection and ecological management to manage ARG enrichment, offering a promising strategy for aquatic ecological restoration and pollution control.

Cápsulas biodegradáveis podem ampliar a germinação de sementes de espécies florestais do Cerrado

ABSTRACT: A good grasp of the different facets of seed germination of the plant species native to the Cerrado will facilitate the selection of species that can be used to restore degraded ecosystems. Hence, the objective of the current study was to confirm the ways biodegradable capsules affect the germination of the seeds of three tree species typical of the physiognomies of the Cerrado forest (Enterolobium contortisiliquum, Anadenanthera colubrina and Dipteryx alata). The experiments, conducted in a greenhouse, included two treatments: seeding performed inside biodegradable capsules and direct seeding on the substrate surface. Two seeds from each of the species were sown in plastic bags containing the Quartzarenic Neosol class of substrates. Using five replicates for each treatment resulted in 20 plastic bags for each. The greenhouse conditions included controlled temperature and relative humidity. Inside the capsules, the findings revealed that the baru, angico-branco and tamboril seeds germinated at the rates of 97%, 42%, and 12%, respectively. However, during direct seeding, germination rates for baru, angico-branco and tamboril were 15%, 21% and 8%. From the findings, it is evident that when biodegradable capsules are used, the germination of all three Cerrado species investigated is favoured. Thus, both capsules and the cited species can be recommended for projects of ecological restoration.

Proximity hybridization-triggered cascade amplification for label-free SERS detection of Alzheimer's amyloid-β oligomers.

Most of the existing SERS systems failed to achieve satisfactory results in early diagnosis of Alzheimer's disease owing to a lack of effective signal transduction. Herein, we developed a dual signal amplification strategy for SERS detection of amyloid-β oligomers based on proximity hybridization-triggered catalyzed hairpin assembly (CHA) and hybridization chain reaction (HCR). In the presence of the target protein and two DNA-labeled antibodies, a proximate complex formed in a homogeneous solution. Each of the AβO-DNA complexes served as a catalyst to trigger and accelerate numerous hybridization processes between MB1 and MB2. Subsequently, the single-strand fragment on the electrode surface initiated HCR, resulting in the hybridization reaction to form double-strand DNA concatemers on the substrate surface. The surface became negatively charged and allowed the absorption of silver ions on the DNA skeleton. After chemical reduction by hydroquinone, the formed silver nanoparticles could be further grown with a silver enhancement step to amplify the detectable SERS signal by absorbing rhodamine 6G as a SERS reporter on the silver nanoparticle surface. This biosensing platform had potential applications in molecular diagnostics of AD serum samples.

Short-Time Peeling of Large Anodic Porous Alumina Membranes from Al Substrates by Two-Layer Anodization Using Concentrated Sulfuric Acid

Ordered anodic porous alumina membranes, which have a uniform cylindrical pore array with a high density, are promising materials for the precise filtration of target substances. We previously reported that when a sample that has undergone anodizing is re-anodized in concentrated sulfuric acid, a highly soluble alumina layer is formed at the bottom of the anodized oxide film. When the re-anodized sample was etched, the highly soluble alumina layer was selectively dissolved; thus, it was possible to obtain a large ordered anodic porous alumina membrane without cracks. In this study, we succeeded in reducing the time required for anodization and etching to obtain an alumina membrane by optimizing the anodization conditions using concentrated sulfuric acid. According to this method, after the alumina membrane was peeled off, it was possible to retain a regular pattern of depressions on the surface of the residual Al substrate, which acted as the starting points for the generation of pores during subsequent anodization. By repeating this process on a single Al substrate, we can repeatedly form an ordered anodic porous alumina membrane. The obtained ordered anodic porous alumina membranes can be used as filtration membranes, catalyst supports, and templates for preparing one-dimensional nanostructures.

Tuning of plasmonic surface lattice resonances: on the crucial impact of the excitation efficiency of grazing diffraction orders.

Metallic nanoparticles exhibit remarkable optical properties through localized surface plasmon (LSP) resonances. When arranged in arrays, nanoparticles form surface lattice resonances (SLRs) affected by inter-particle distance. SLRs can offer narrower bandwidths and stronger electric field enhancements than LSP modes, crucial for efficient optical device development. Among important aspects, grazing diffracted orders crucially impact SLR properties, facilitating long-range nanoparticle interactions. This study explores how these photonic modes propagating at the substrate surface influence SLRs, by using experimental and theoretical approaches, including Finite Difference Time Domain simulations on gold disk arrays. Results show SLR properties strongly rely on diffracted mode efficiency controlled by the grating constant along the incident polarization. Notably, large inter-particle spacing along the incident polarization can strongly reduce the SLR red-shift. Understanding and managing long-range interactions in engineered plasmonic structures are highlighted, providing insights for enhanced performance in advanced photonic and optoelectronic devices.

Evaluation of AlCoCrFeNiTi-high entropy alloy (HEA) as top coat material in thermal barrier coating (TBC) system and investigation of its high temperature oxidation behavior

To obtain compatible properties of high-temperature performance and mechanical strength properties, AlCoCrFeNiTi high-entropy alloy (HEA) was designed as a new candidate material for metal-based thermal barrier coating (TBC) systems. The aim of this study is to investigate potential applications of AlCoCrFeNiTi-HEA as a coating material for TBC systems and to determine its behavior under high temperature conditions. CoNiCrAlY bond coatings were produced on the Inconel-718 substrate surface using high-velocity oxygen fuel (HVOF) technique. AlCoCrFeNiTi-HEAs were produced on CoNiCrAlY bond coatings using atmospheric plasma spray (APS) technique and a typical TBC system structure was obtained. The produced AlCoCrFeNiTi-HEA TBC system was exposed to oxidation at temperatures of 1000 °C and 1100 °C for time periods of 5 h, 25 h, 50 h and 100 h in order to determine the oxidation resistance under isothermal conditions and to investigate formation and growth behavior of oxide structures formed at the coating interface. As a result of oxidation tests, the growth behavior of the thermally grown oxide (TGO) layer formed between the coating interfaces and the microstructural changes occurring in the coating system were investigated depending on temperature and time processes. In the TBC system with Ti-containing HEA content, a transformation from body-centered cubic (BCC) structure to rhombohedral crystal lattice structure occurred as a result of increasing temperature. Many spinel compound forms were formed at the coating interface. It was observed that the coating system with AlCoCrFeNiTi-HEA content maintained its structural integrity without any damage such as microstructural and mechanical spalling and cracking under conditions of high temperature and different time periods.

Research on controllable texturing and performance of hybrid laser cleaning on magnesium alloy substrate surfaces

Research on controllable texturing and performance of hybrid laser cleaning on magnesium alloy substrate surfaces

The magnesium sulfate whisker/Al2O3 superhydrophobic composite coating exhibits robust, corrosion-resistant, and delayed icing properties

Superhydrophobic coatings exhibit paramount significance in practical applications, yet they often confront durability challenges, notably their propensity to detach. In this study, by using epoxy resin as the intermediate layer, the upper coating consists of epoxy resin, micron-sized alkali magnesium sulfate whiskers and nanosized alumina. Using a simple spraying method, the contact angle of the composite coating was measured to be 154.8°, and the rolling angle was 3.5°. The results show that the prepared coatings are still superhydrophobic after 100 tape stripping and 1600cm sandpaper abrasion distance, proving that the coatings have good mechanical durability. Furthermore, in electrochemical tests superhydrophobic coating achieved 98.94% retardation efficiency compared to bare copper sheet. The delayed icing time of the superhydrophobic coated copper sheet is 7 times and 3.5 times longer at -15℃ and -20℃, respectively, compared with the bare copper sheet. Additionally, the coating has excellent self-cleaning and stain resistance properties and is suitable for use on a wide range of substrate surfaces.

Light energy-driven carbonic anhydrase mediate CO2 sequestration system with variable-temperature adaptability.

The escalating atmospheric CO₂ concentration urgently demands ecologically friendly mitigation strategies. Compared to alternative catalysts, carbonic anhydrase (CA) demonstrates exceptionally high catalytic efficiency in CO₂ hydration reactions. Nevertheless, traditional CA immobilization techniques exhibit peak enzymatic activity exclusively at optimal temperatures, consequently constraining their effective application across diverse environmental thermal conditions in industrial settings. Inspired by the adaptive mechanisms of plant leaves, which modulate enzymatic environmental adaptability through photonic flux variations, we propose an innovative photoenergy-driven CA-mediated CO₂ sequestration system characterized by temperature adaptability. Titanium carbide (MXene), amino-functionalized multi-walled carbon nanotubes (AMWCNTs), and gelatin (Gel) are utilized as substrates for the immobilization of CA to fabricate MAG-CA. Upon illumination, MAG-CA engenders a Substrate surface temperature above ambient level. By modulating light intensity in accordance with natural environmental temperatures, CA within MAG-CA can be perpetually maintained at its optimal temperature on the surface of the support, culminating in efficient carbon capture across a range of ambient temperatures (20-40°C). Moreover, the carbon capture efficiency of MAG-CA (under illumination at 25°C) is more than twice that of free CA (without illumination at 40°C), which provides a new perspective for the industrial application of enzyme-mediated carbon capture.

Stepwise grafting polyethyleneimine onto silica surface for Cu(II) removal

Polyethyleneimine (PEI) is a novel polymer that contains multiple amine groups that are suitable for chelation with many heavy metal ions (HMI). Anchoring PEI onto the surface of a solid substrate has been widely adopted to develop adsorbent materials with the hope of combining the HMI chelating ability of PEI with the heterogeneity of the substrate. Herein, the preparation of PEI grafted SiO2 (PEI/SiO2) has been demonstrated by a stepwise method in which SiO2 nanoparticles were functionalized with 3-glycidoxypropyltrimethoxysilane (KH560) followed by refluxing with PEI. The method could provide PEI/SiO2 material with 23.4% of PEI by weight. Studying the adsorption properties of PEI/SiO2 with Cu(II) revealed that the adsorption of Cu(II) ions on PEI/SiO2 followed Langmuir and Dubinin-Radushkevich models and included both chemisorption and physisorption. The adsorption capacity was about 25.3-27.3 mg/g. The stepwise method demonstrated in this study may be adopted to fabricated PEI based materials for HMI removal.

RADIO-ABSORBING MATERIALS BASED ON GRAPHITE PARTICLES IN EPOXY RESIN

This paper presents the results of a study on radio-absorbing materials in the ultra-high frequency range of 78-118 GHz. Crystalline graphite powder (particle size 0.1 mm) was considered as the main radio-absorbing material. Epoxy resin was used as a substrate and a binder. The samples were prepared by dispersing the graphite powder across the surface of the epoxy resin substrate. The most effective working thickness of epoxy resin has been established experimentally. The geometric dimensions of the arrangement of the installation components at which the most effective signal recording is observed are calculated. The results of the studies showed that a film consisting of graphite particles on the surface of epoxy resin effectively shields radio emissions in the 3-millimeter range.

ENHANCEMENT OF POWER CONVERSION EFFICIENCY OF DYE-SENSITIZED SOLAR CELLS VIA INCORPORATION OF GAN SEMICONDUCTOR MATERIAL SYNTHESIZED IN HOT-WALL CHEMICAL VAPOR DEPOSITION FURNACE

This study discusses the results of plasma enhanced chemical vapor deposition synthesis of GaN on sapphire and silicon substrates using specific parameters: a forward output voltage of 150 watts, a N2 gas flow rate of 60 standard cubic centimeters per minute, a chamber pressure of 2.48 mmHg, and a synthesis time of 2hours. Characterization by scanning electron microscope, Raman and energy dispersive X-ray revealed the non-stoichiometric formation of GaN, with Ga clearly predominating in the composition. scanning electron microscope analysis of the substrate surface morphology revealed the presence of small islands, which are considered to be the first step in the chemical vapor deposition process. The research also examined the effects of incorporating GaN into the photoanode of dye-sensitized solar cells. The study investigated the optimal amount of GaN powder in the TiO2 matrix. The initial experiments used commercial GaN powder to determine the optimal weight percentage. Four different weight percentages (wt%) 10 wt%, 20 wt%, 30wt % and 40 wt% GaN were selected for the study. Among them, the 20 wt% GaN had the highest power conversion efficiency of 0.75%. The fill factor values ​​showed a tendency to decrease as the weight fraction of GaN increased.

Displacement-controlled coining of large arrays of gold stud bumps

Abstract Novel, simple, and low-cost, displacement-controlled coining (DCC) process is developed for coining of gold stud bumps. A bottom mold made of aluminium which contains an array of geometrically well-defined cavities (nests) with known and pre-defined depth values in each nest, is designed and manufactured to adjust areas of coined surfaces and heights of coined stud bumps during sequential displacement-controlled coining processes. A double-side polished, and thick Borosilicate glass substrate is used as a flat surface to be in direct contact with the tails of the stud bumps to be coined. Above the double side polished glass substrate, another thick and rigid mold is positioned to uniformly apply the displacement-controlled deformation force to the stud bumps via the polished surface of the glass substrate. With the proposed displacement-controlled coining process, height and bonding surface area of the stud bumps can be tailored for flip-chip bonding (FCB) processes, especially when the maximum applicable force configuration of a FCB tool is limited (maximum of 20 N) during thermo-sonic flip chip bonding (TSFCB) processing. The proposed technique can be used to simultaneously coin arrays of stud bumps with high precision, providing an alternative, cost-effective, precise, time-efficient processing of stud bumps prior to TSFCB applications.

Effect of ultrasonic treatment on tin recovery from decommissioned displays in sulphuric, hydrochloric, and methanesulphonic acid solutions

The study investigates the physicochemical patterns of tin leaching from the surface of glass substrates from decommissioned displays in hydrochloric, sulphuric, and methanesulphonic acids. The effects of acid concentration (0.1–1.0 N), duration (10–60 min), temperature (298–353 K), and ultrasonic treatment intensity (UST) (120–300 W/cm2) on leaching performance were evaluated. It was demonstrated that ultrasonic treatment positively impacts sulphuric acid leaching of tin, increasing its recovery by 14–16 %. However, during leaching in hydrochloric and methanesulphonic acid solutions, UST led to a reduction in tin recovery to 28 % and 1.7 %, respectively, due to acid decomposition under ultrasound. The partial reaction orders for tin leaching in HCl, H2SO4, and CH3SO3H were determined to be 0.8, 1.4, and 1.1, respectively, and changed to 1.5, 1.1, and 0.3 under ultrasound for the corresponding acids. An increase in temperature from 298 K to 333 K significantly improved tin recovery in sulphuric and hydrochloric acids. However, raising the temperature to 353 K led to a decrease in tin ion concentration after 10–20 min, likely due to tin hydrolysis and precipitation. The calculated apparent activation energies of tin oxide dissolution in HCl solutions were 40.4 kJ/mol without UST and 22.9 kJ/mol with UST. For H2SO4, the apparent activation energy was 4.0 kJ/mol, increasing to 29.0 kJ/mol under ultrasonic treatment. Therefore, the study showed that tin leaching from glass substrates of decommissioned displays proceeds in a kinetic regime when HCl is used and in a diffusion regime in H2SO4 solutions, with ultrasonic treatment facilitating the transition to a mixed regime.

Perspective of Tribological Mechanisms for α-Alkene Molecules with Different Chain Lengths from Interface Behavior.

Three α-alkene lubricants, differentiated by chain length, were selected as model compounds to investigate the influence of chain length on tribological properties. The novelty of this study lies in setting chain length as the sole variable to explore its impact on surface and adsorption energy. Based on the above findings, the study provides a unique explanation of the intrinsic relationship between chain length and tribological performance. The tribological properties of the three α-alkenes were compared, and subsequent characterization methods elucidated the wear mechanisms and explored tribochemical reactions. The study employed the Owens-Wendt-Rabel-Kaelble (OWRK) method and density functional theory (DFT) to investigate each compound's surface energy and adsorption energy. Experimental results revealed that the average friction coefficients (abridged as COF) for 1-decene, 1-tetradecene, and 1-octadecene decreased sequentially to 0.125, 0.099, and 0.075, respectively. The wear volume of 1-tetradecene decreased by 53.2% and that of 1-octadecene decreased by 64.0% compared to 1-decene. This can be attributed to the simultaneous enhancement of the surface energy and adsorption energy with increasing chain length. On the one hand, the increase in surface energy facilitates tribochemical reactions positively influencing the formation of tribofilms. On the other hand, the increase in adsorption energy enhances the adsorption of lubricants on the substrate surface. The synergy of these two effects allows 1-octadecene and 1-tetradecene (long-chain α-alkenes) to exhibit superior tribological performance compared to that of 1-decene (short-chain α-alkenes). Ultimately, this study offers unique insights into understanding lubrication mechanisms.

Tight Binding Molecular Dynamics Study of Growth of Nanostructure Materials

Abstract The growth dynamics of mixed In and Se films on the MoSe2 substrate is modeled using quantum mechanical tight-binding-based molecular dynamics simulations. The substrate temperature, the ratio of In and Se, and the deposition flux are chosen to mimic the experimental conditions as closely as possible. The conversion of individual adatoms and clusters into alternate layers of Se-In-
Se is captured during our simulations. One of the main outcomes of our model is that we are able to identify and obtain energy barriers for the concerted motion of some species on the substrate surface. Such kind of estimates of energy barriers are important for larger scale kinetic Monte Carlo simulations. Furthermore, we have identified different diffusion regimes of In and Se.