Surfaces Of Various Materials Research Articles

ADHESIVE ABILITY OF GYPSUM-CONTAINING PLASTER COMPOSITIONS

The traditional material for the construction of buildings in the Northern Black Sea region is a cheap local stone ‒ limestone-shell rock. Most of the buildings in the central part of the city of Odesa, which are of historical and architectural value, are constructed of this material. With proper care and maintenance, these structures can perform their functions for hundreds of years, but as a result of shell rock moisture due to negligent operation and a number of other reasons, the supporting structures are damaged, followed by the collapse of the building. In many cases, the direct cause of the destruction of load-bearing walls is the damage or absence of the outer plaster layer. Repairing walls with cement compounds exacerbates the problem. The article discusses some aspects of the possible use of gypsum-based composite materials for repairing damaged walls of limestone-shell rock buildings. The requirements for the repair composition are formulated. The expediency of using gypsum as a binder for the repair plaster mixture for exterior repairs is substantiated. An ash-gypsum-cement composition was used to increase the water resistance of the plaster. Sufficient water resistance and vapor permeability of the proposed composition were confirmed. This paper presents the results of studying the adhesive strength of the contact of the developed composition with the surface of various materials. Methods and measuring equipment developed at the ODABA were used. The adhesion strength of the proposed mixture with the surface of shell rock is close to the standard strength. The use of the adhesive additive Ceresit CC 81 increases the adhesive strength of the joint of the proposed composition with shell rock by 1.5 ‒ 2 times. The optimal amount of the adhesive additive to be introduced will be determined by the results of a multifactorial experiment to study the effect of a complex of chemical additives of different functional purposes on the properties of the proposed repair composition.

Critical areas for <i>Brettanomyces bruxellensis</i> contamination and biofilm formation in the cellar: on the origin of wine spoilage

The cellar environment harbours a consortium of microorganisms on the material surfaces and in the air. Among these microorganisms, the spoilage yeast Brettanomyces bruxellensis can colonise surfaces due to its specific bioadhesive properties. In this study, air and surface samples were collected in several wineries during the winter period. B. bruxellensis was detected in the cellar environment either in the air or on the surfaces of various materials, including in tartaric acid precipitates. Difficult-to-clean tank equipment (taps, wall angles, valves) were identified as critical areas where B. bruxellensis was frequently detected. To confirm that surfaces contaminated by B. bruxellensis could be involved in wine contamination, yeast growth and volatile phenol production were monitored in wine in contact with stainless steel harbouring biofilms. The presence of bioadherent cells and biofilms in contact with the wine resulted in significant cell release into the wine, leading to population growth and the production of volatile phenols at concentrations above the olfactory detection threshold. This study demonstrates the possibility of wine spoilage by resident and adherent populations of B. bruxellensis and confirms the need to pay special attention to the hygiene of hard-to-reach areas such as valves.

Neutral beam microscopy with a reciprocal space approach using magnetic beam spin encoding

The emerging technique of neutral beam microscopy offers a non-perturbative way of imaging surfaces of various materials which cannot be studied using conventional microscopes. Current neutral beam microscopes use either diffractive focusing or pin-hole scanning to achieve spatial resolution, and are characterised by a strong dependence of the imaging time on the required resolution. In this work we introduce an alternative method for achieving spatial resolution with neutral atom beams which is based on manipulating the magnetic moments of the beam particles in a gradient field, and is characterised by a much weaker dependence of the imaging time on the image resolution. The validity of the imaging approach is demonstrated experimentally by reconstructing one dimensional profiles of the beam which are in good agreement with numerical simulation calculations. Numerical simulations are used to demonstrate the dependence of the signal to noise on the scan resolution and the topography of the sample, and assess the broadening effect due to the spread of velocities of the beam particles. The route towards implementing magnetic encoding in high resolution microscopes is discussed.

The capability of diffuse coplanar surface barrier plasma to effectively remove contaminants from surfaces of various materials

AbstractUsing the fluorescence method, the study quantifies the cleaning efficiency of flat surfaces of selected materials (steel, polymethyl methacrylate, glass) compared to the usual cleaning methods: cleaning using ultrasound and cleaning using solutions (ethanol/isopropyl alcohol – isopropanol). Cleaning using ethanol/isopropanol solutions was carried out in such a way as to simulate common procedures: rubbing, rinsing and a combination of application of the solution and ultrasound. Based on the prepared and evaluated (following the average at several places on the surface) values of fluorescence maps of material surfaces, the resulting values of fluorescence before/after cleaning or at the selected moment of degreasing/cleaning of surfaces (applies to steel) were determined. The application of diffuse coplanar surface barrier discharge plasma discharge to the surfaces of flat materials can provide: a reduction in the environmental burden (no chemicals are needed to clean the surfaces) and an improvement in the efficiency of surface cleaning in industrial/manufacturing conditions (plasma cleaning usually takes a few seconds). diffuse coplanar surface barrier discharge plasma can clean and simultaneously activate the surfaces of flat materials.

A Millimeter‐Scale Micro Crawling Robot with Fast‐Moving Driven by a Miniature Electromagnetic Linear Actuator

The micro crawling robot exhibits significant potential applications in various fields such as fault detection, disaster relief, and environmental monitoring. This article introduces a high‐performance millimeter scale crawling robot driven by a miniature electromagnetic linear actuator (MELA) with a body length of 5–6 mm and a mass of 80 mg. In this article, the working principle of the micro robot is analyzed and validated, and the influence of current, frequency, and angle α between the direction of actuator's force and the crawling surface on the crawling speed are analyzed through experiments. Results show that the optimal α ranges from 50° to 55°, and a specific current and frequency are identified to achieve maximum crawling speed for robot with particular α. When α is 50°, with a current of 300 mA and a frequency of 200 Hz, the robot reached the maximum speed of 20.2 Body Length s−1(BL s−1). The proposed robot can crawl at 12 BL s−1 with a load of 110 mg, and support a maximum load of 400 mg. Additionally, the robot demonstrated diverse capabilities such as climbing on a 10° slope with a load of 110 mg, jumping on a 1 mm obstacle, and crawling on surfaces of various materials.

Morphological study of depth-controlled high quality holes and lines fabricated on a metal substrate with a thin metal film by picosecond laser pulses

Laser micromachining is a convenient technique to structure and/or functionalize the surfaces of various materials. The use of ultrashort laser pulses has an obvious advantage to minimize the heat effect, which results in the formation of a hole without rims. Nevertheless, it is still difficult to fabricate a line without rims even with ultrashort laser pulses, because multiple irradiation of ultrashort laser pulses with a sufficient spatial overlap promotes the formation of rims and undesired structures. In this work we employ a metal substrate with a thin metal film, and demonstrate the fabrication of depth-controlled high quality lines, not to mention holes, through the selective removal of the film by picosecond laser pulses without forming rims and undesired structures. Morphological study of the target surface reveals that the fabricated structures have unprecedentedly flat bottoms with nearly vertical sidewalls to the surface.

Preparation and applicability of a flexible PDMS superhydrophobic layer

Superhydrophobic surfaces have broad application prospects in the fields of self-cleaning, anti-icing, and fluid drag reduction. In this study, a convenient and environmentally friendly method was used to prepare a flexible PDMS superhydrophobic surface, and the effect of different spraying times on surface wettability was studied. On this basis, the applicability of the PDMS superhydrophobic surface was evaluated by high and low temperature environment experiments. The results show that the better spraying times are 3 times, the contact angle is 165.52°, and the rolling angle is 2.06°. The flexible superhydrophobic surface can be applied to the surface of various materials and structures with good waterproof and antifouling properties. In the high-temperature environment of 100 °C, it can effectively improve the flooding problem of fuel cell bipolar, and it is still effective after one month. In the low-temperature environment of −30 °C, it can effectively inhibits the surface frosting and the surface composite powder is well bonded to the substrate.

Ignition of Carbon Black during Nanosecond Diffuse and Spark Discharges in Air at Atmospheric Pressure

Many scientific teams are currently studying the effects of plasma generated by nanosecond diffuse discharges on the surfaces of various materials in order to modify their properties. To achieve this, uniform plasma is required to act on the target being treated, which is often an electrode in a discharge system. Previously, the surface treatment uniformity of flat electrodes during a nanosecond discharge in a point-to-plane gap was studied by applying a carbon black layer, and a discharge mode was identified in which there was no erosion on the treated electrode. In this study, it was established that during a nanosecond discharge in air at atmospheric pressure in a non-uniform electric field, carbon black deposited on the surface of a flat anode can ignite. The conditions and dynamics of carbon black ignition during the nanosecond discharge were determined. It was observed that the carbon black is ignited on the surface and continues to combust in the gap in the form of flame plumes for tens of milliseconds. It was also found that the combustion of carbon black can occur in both diffuse and spark discharges.

Layer-by-layer thinning of two-dimensional materials.

Etching technology - one of the representative modern semiconductor device makers - serves as a broad descriptor for the process of removing material from the surfaces of various materials, whether partially or entirely. Meanwhile, thinning technology represents a novel and highly specialized approach within the realm of etching technology. It indicates the importance of achieving an exceptionally sophisticated and precise removal of material, layer-by-layer, at the nanoscale. Notably, thinning technology has gained substantial momentum, particularly in top-down strategies aimed at pushing the frontiers of nano-worlds. This rapid development in thinning technology has generated substantial interest among researchers from diverse backgrounds, including those in the fields of chemistry, physics, and engineering. Precisely and expertly controlling the layer numbers of 2D materials through the thinning procedure has been considered as a crucial step. This is because the thinning processes lead to variations in the electrical and optical characteristics. In this comprehensive review, the strategies for top-down thinning of representative 2D materials (e.g., graphene, black phosphorus, MoS2, h-BN, WS2, MoSe2, and WSe2) based on conventional plasma-assisted thinning, integrated cyclic plasma-assisted thinning, laser-assisted thinning, metal-assisted splitting, and layer-resolved splitting are covered in detail, along with their mechanisms and benefits. Additionally, this review further explores the latest advancements in terms of the potential advantages of semiconductor devices achieved by top-down 2D material thinning procedures.

Enhanced interfacial boiling of impacting droplets upon vibratory surfaces

HypothesisDespite the flourishing studies of droplet interfacial boiling, the boiling upon vibratory surfaces, which may cause vigorous liquid–vapor-solid interactions, has rarely been investigated. Enhanced boiling normally can be gained from rapid removal of vapor and disturbance of liquid–vapor interface. We hypothesize that the vibratory surfaces enhance both effects with new intriguing phenomena and thus, attain an enhanced boiling heat transfer. ExperimentsWe experimentally investigated the impacting fluid dynamics and coupled heat transfer patterns of multiple droplets and a single droplet impinging on still and vibratory surfaces of various materials and different wettability. FindingsThe boiling under vibratory surfaces with increased vibration velocity amplitude and enhanced wettability can be enhanced by 80% in heat transfer coefficient and Nusselt number, which is attributed to several reasons: shortened bubble lifespan, thinner and smaller bubbles, and enhanced disturbances in liquid–vapor interfaces. The vibration also delays the Leidenfrost point when the droplet impacts a descending surface, which shows that the droplet impact moment (vibration phase angle) is particularly crucial. The descending surface releases the generated vapor actively and facilitates liquid–solid contact, thereby delaying the Leidenfrost. From fundamentals to application, this article strengthens our understanding of vibrated interfacial boiling in scenarios closer to multiple natural processes and practical industries.

Some Features of Quantitative Analysis of Surface Compounds by Laser Desorption Mass Spectrometry

The results of quantitative analysis of widely used surface samples are shown. Corrosion damage to copper and steel surfaces can be analyzed quantitatively using cobalt chloride as the internal standard. The study also demonstrates the feasibility of comparative quantitative analysis of blue ink using methylene blue homologues as standards. When conducting quantitative analysis on surfaces with inhomogeneous morphology, it has been observed that direct analysis is not possible because of uneven ionization of the sample. It has been found that when analyzing such surfaces, it is necessary to exclude points with a low signal-to-noise ratio from consideration. The work highlights the extensive possibilities of utilizing quantitative analysis in mass spectrometric visualization of the surface. The work is aimed at demonstrating the capabilities of the laser desorption mass spectrometric method for analyzing the surfaces of various materials, which will make this method universal for searching for a wide range of contaminants on the surface of materials of various nature.

Method for fabrication of laser-induced periodic surface structures on vascular stents

Abstract Laser-induced periodic surface structures (LIPSS) provide the possibility to functionalize the surface of various materials, which can be used to control the wettability of metal surfaces or influence cell adhesion. LIPSS thus offer great potential for application on implant surfaces if their fabrication process is compatible with standard implant fabrication techniques. Here we demonstrate an easy-to-use two-step fabrication method for stents with different types of LIPSS. The separation between the fabrication of the stent structure and the surface structuring process allows the implementation of any stent structure finishing technique without affecting the LIPSS. The suggested fabrication method may be a step further in implementing laser machining-based surface functionalization in commercial implants.

Tunneling spectroscopy of field-induced superconductivity in molybdenum disulfide using top metal contacts

Field-induced superconductivity has been observed on the surfaces of various materials; however, the underlying mechanism of this two-dimensional superconductivity remains elusive. While tunneling spectroscopy measurements provide valuable insights into the microscopic nature of the superconducting state, there is a scarcity of tunneling spectroscopy measurements specifically focused on field-induced superconductivity when compared to transport measurements. In this study, we present a novel approach for tunneling spectroscopy using top metal contacts on field-induced superconducting MoS2. Our experimental findings, including the energy gap values, are consistent with those of a previous study conducted using a different device configuration. The observed energy-dependent density of states cannot be explained by the conventional BCS mechanism. We address the impact of inhomogeneity within the superconducting phase and discuss potential methods for its suppression. The proposed tunneling spectroscopy technique offers simplicity and ease of implementation, making it applicable for investigating other two-dimensional superconducting systems.

Identifying the influence of bubble size and position on crater formation during underwater nanosecond laser ablation of stainless steel

Underwater laser ablation can be employed both as a means to produce nanoparticles and to texturize surfaces of various materials. In this approach, a stationary or flowing water layer above the target surface confines laser induced plasma which cools to form short lived cavitation bubbles, positively influencing the amount of removed material per laser pulse. Plasma and cavitation bubble evolution additionally give rise to bubbles which may persist in the water throughout the ablation process. These bubbles are known to have a detrimental effect on material removal rates particularly in stationary water, but the quantitative influence of bubble dimensions and position on removed material volume is currently unknown. Here we show the laser intensity profile changes induced by bubbles located at 0–0.4 Rayleigh lengths above a stainless steel surface and couple these changes to removed crater volume. Our results show that water flowing at Reynolds numbers in the range of 1–100 positively contribute to crater volumes for pulse frequencies up to 1 kHz. At 1 kHz, it was found bubbles have insufficient time to flow from the vicinity of the laser spot, regardless of the Reynolds number within the range investigated. These conclusions assist in selecting an appropriate combination of laser and flow conditions to optimize laser ablation material removal rate.

Emergence of the clinical rdar morphotype carbapenem-resistant and hypervirulent Klebsiella pneumoniae with enhanced adaption to hospital environment

Klebsiella pneumoniae has evolved into strains of various phenotypes that pose a grave threat to human health in the past few decades. This study investigated a novel morphotype of K. pneumoniae with enhanced adaption to the hospital environment. Clinical K. pneumoniae were characterized by different genotypic and phenotypic tests. Gene knockout and complementation experiments were used to confirm the genetic changes that led to the morphological changes. ST15 carbapenem-resistant and hypervirulent (CR-hvKP) clinical strains with the “red, dry and rough” (rdar) morphotype were increasingly detected in hospitals in China. Strains with the rdar phenotype were found to be less virulent compared with that with typical morphologies but exhibit enhanced ability to adhere to the surface of various materials, and hence a dramatically increased rate of survival on various materials commonly found in the hospital environment. Comparative genomics analysis and gene function studies suggested the rdar morphotype was due to a G579D substitution in the BcsA protein which enabled the strain to produce a large amount of cellulose. These findings show evolutional phenotypic change enables K. pneumoniae strains to better survive both in human and hospital environments, facilitating its persistence and further dissemination.

Tuning the Wettability of a Commercial Silane Product to Induce Superamphiphobicity for Stone Protection

Silane-based materials are used for the protection of heritage and modern buildings. A versatile method is developed to tune the wetting properties of a typical silane-based material from hydrophobicity to superamphiphobicity, thus enhancing the protective efficacy against rainwater and organic pollutants. A commercially available silane product is blended with a fluoropolymer to lower the surface energy and silica (SiO2) nanoparticles to affect the surface morphologies of the produced coatings on marble. Contact angles of water and oil drops are measured on the coating surfaces which were prepared using 16 different combinations of fluoropolymer and nanoparticle concentrations. It is shown that the synergistic effect of surface structure and chemistry can lead to the production of coatings that possess superamphiphobic properties. The wetting properties of a selected non-wettable coating are further characterised using a custom-made, fully-automated device (Kerberos) which monitors simultaneously the deformation of the liquid interface, spreading and sliding of the drop along the sample surface during tilting. Several tests are carried out to evaluate the durability of the selected superamphiphobic coating, offering overall promising results. The versatile method can be used to impart superamphiphobicity to the surfaces of various materials. The method developed herein can be adopted to tune the wetting properties of other silane-based commercial products which are used for the protection of buildings.

Imaging the Dynamics of Metal Ion-Coupled Electron Transfer on Material Surfaces with Redox/Photo Active Chelators

Metal ions on surfaces of various materials as bulk matrices, doped structural units, or functionalized active sites play critical roles in the establishment of physical and chemical properties. Characterization of surface-bound metal ions and metal ion-coupled electron transfer are urgently needed for the determination of material structures as well as for understanding the relationship to macroscopic properties and technological applications. We present here a mass spectrometric (MS) technique that allows the monitoring of metal ion-coupled electron transfer along with spatial distributions, identities, quantities, valences, redox activities, and associated anions. It is based on the coordination of metal ions with chelators that are redox/photo active. Upon the irradiation of a focused laser beam, metal ions on material surfaces that are covered with chelators are evaporated, ionized, and detected with MS. This technique clearly reveals ligand-metal/metal-ligand and ligand-bridged electron transfers through MS or tandem MS/MS experiments. MS images of metal ions on material surfaces with the spatial resolution down to the sub-micrometer level have been obtained. It has been applied to the monitoring of hot electron transfer, leftover positive metal ions in localized surface plasmon resonance, and photocatalytic activities of crystalline facets of TiO2.

Superhydrophobic coatings from macromolecular fluorinated silica nanoparticles through START polymerization and “grafting onto” strategy

Fluorinated substances are often introduced to enhance the hydrophobicity of surfaces of various materials. In this work, fluorinated macromolecular coupling agents (AB)nA-b-PIPMSAm are prepared via successive step transfer-addition and radical-termination (START) polymerization and photocontrolled iodine-mediated reversible deactivation radical polymerization (RDRP) at room temperature, which is then decorated on the surface of silica nanoparticles followed by iodine removal for preparing iodine-free macromolecular fluorinated silica nanoparticles (macro-F-SiNPs-I). Superhydrophobic coatings were produced simply by spin coating of the macro-F-SiNPs-I onto glass or dip coating on cotton substrates. The effect of a variety of parameters on surface superhydrophobicity, such as the solvent for spinning coating, concentration of macro-F-SiNPs-I, size of silica nanoparticles and chemical structures of (AB)nA-b-PIPMSAm, were studied in detail, and the superhydrophobic surfaces with water contact angle (WCA = 172.6°) could be facilely achieved under optimum conditions. In addition, the resultant macro-F-SiNPs-I coatings are quite stable against acidic (pH = 1), basic (pH = 13) or high salty solutions, and their excellent superhydrophobic performance was also confirmed by self-cleaning and oil/water separation experiments, which displayed fascinating promise in practical applications on a large scale.

Efficient Broadband Light-Trapping Structures on Thin-Film Silicon Fabricated by Laser, Chemical and Hybrid Chemical/Laser Treatments

Light-trapping structures formed on surfaces of various materials have attracted much attention in recent years due to their important role in many applications of science and technology. This article discusses various methods for manufacturing light-trapping "black" silicon, namely laser, chemical and hybrid chemical/laser ones. In addition to the widely explored laser texturing and chemical etching methods, we develop a hybrid chemical/laser texturing method, consisting in laser post-texturing of pyramidal structures obtained after chemical etching. After laser treatments the surface morphology was represented by a chaotic relief of microcones, while after chemical treatment it acquired a chaotic pyramidal relief. Moreover, laser texturing of preliminarily chemically microtextured silicon wafers is shown to take five-fold less time compared to bare flat silicon. In this case, the chemically/laser-treated samples exhibit average total reflectance in the spectral range of 250-1100 nm lower by 7-10% than after the purely chemical treatment.

Surface Activation of Wax-Based Additives to Enhance Asphalt Rheological Properties via Rotating Plasma Treatment

Wax-based additives have been widely used in asphalt pavement for their preferable environmental benefits. However, poor compatibility between wax-based warm mix additives and asphalt easily leads to precipitation of wax and cracking of asphalt pavement. Plasma treatment can effectively modify the surface of various materials. This study applies plasma treatment to improve the surface properties of wax-based additives for compatibility improvement in asphalt binder. Compatibility of two different wax-base additives in asphalt binder before and after surface treatment is investigated via cigar tube test and morphology test. In parallel, rheological properties of wax-modified asphalt are characterized from the perspectives of rotational viscosity, rutting resistance, and fatigue performance. Results show the enhanced surface roughness and chemical activity of wax-based additives after plasma treatment. The adhesion between waxes and the asphalt matrix is significantly improved. Waxes within binder are uniformly dispersed after plasma treatment. The incorporation of surface activated wax helps to promote the viscosity reduction of asphalt binder. Furthermore, the high-temperature performance of wax-based asphalt after surface activation treatment of wax is significantly improved, especially for fatty acid amide waxes. As for fatigue performance, plasma treatment improves the fatigue resistance from a compatibility perspective. Therefore, plasma has great promise for facilitating wax-modified asphalt properties from a compatibility perspective.