Surface Physical Characteristics Research Articles

Comparative study of surface preparation for paint adhesion on CF-PEKK composites: Plasma, Chemical, and Flame treatment

Polyether ketone-ketone (PEKK) is a high-performance thermoplastic, and its fiber composites have various engineering applications. Fiber reinforced composites in long-term applications require a protective layer of coatings to avoid environmental degradation. In this work, the surface energy of carbon fiber-PEKK composites was modified by flame, chemical, and plasma treatments to improve paint adhesion. A detailed study was carried out to understand the physical, morphological, and chemical surface characteristics due to different surface treatments. We found through XPS that highly active surface functionalities (− C-Ȯ/−C = Ȯ) due to oxidation at the ketone/ether groups were for surface adhesion. In support of the enhanced surface functionality, we have also evaluated the wetting behavior of paint with respect to different treated surfaces using drop shape analyzer and found that the polar component of the surface free energy increased for all treatments compared to pristine. Surface crystallinity after surface treatment was assessed using XRD; flame and plasma showed reduced surface crystallinities (25.92 % and 38.18 %, respectively), compared to pristine (46.78 %), and yielded a good adherend for coatings. Surfaces with good wettability and functionalities show good adhesion between the paint and PEKK composites as found through adhesion tests following ASTM D3359. The findings demonstrate that plasma surface treatment outperformed flame and chemical treatments in terms of adhesion of the paint to the surface.

Enhanced adsorption capacity of antibiotics by calamus-biochar with phosphoric acid modification: Performance assessment and mechanism analysis

BackgroundAdsorption is one of the effective methods to remove antibiotics from water. Plant-based biochar can be effectively modified to enhance the adsorption capabilities of antibiotics. MethodsCalamus biochar (PBC) was modified by phosphoric acid to study its adsorption efficacy on erythromycin (ERY) and sulfamethoxazole (SMX). Significant FindingsPBC had a pore density of 0.771 m3·g−1, an average pore size of 5.14 nm, and an enormous surface area of 797 m2·g−1. PBC had been shown to incorporate a substantial quantity of functional groups containing oxygen by FTIR and XPS investigations. With these surface chemical and physical characteristics, PBC adsorbed 325 mg·g−1 of ERY and 216 mg·g−1 of SMX, which was tenfold higher compared to that of unmodified biochar and industrial-activated carbons. Quantitative analysis of adsorption mechanisms showed that the adsorption of ERY by PBC mainly included oxygen-containing functional group complexation and pore filling, whereas, the π-π interaction and pore filling were the leading mechanisms in the adsorption process of SMX. This research offers insights into the preparation of plant biochar with excellent antibiotic adsorption performance.

Association analysis between the distribution of surface physical characteristics and bonding performance of carbon fiber composites

AbstractEffects of plasma treatment distance on the adhesion properties of carbon fiber composites were investigated, and the association between the distribution of surface physical characteristics on the composites and their bonding properties was discussed. After plasma treatment at different distances, surface morphology of the bonding area was obtained and the roughness distribution model was established. The change in surface physical characteristics directly influences the wettability of the bonding surface and the tensile shear strength (TSS) of the bonded components. When the TSS showed an increase by 19.47% at the treatment distance of 15 mm, metallographic images indicated that the bonding layer was integrated with the composites and the joint in the component was dominated by cohesive failure. When the TSS showed a decrease by 30.72% at the treatment distance of 5 mm, metallographic images indicated that voids and delamination were introduced in the bonding layer and fiber tearing failure mode appeared in the plasma etched area. Moisture‐heat resistance of the bonded components was also considered and a noticeable increase in water absorption was observed in the case of excessive treatment at the distance of 5 mm, which was also related to the distribution of physical characteristics induced by the plasma treatment.Highlights Surface characteristic distribution of plasma‐modified composites was analyzed. State of resin and fibers on composite surface varied with the treatment distance. Semi‐annular plasma treatment traces appeared in the roughness distribution. The high roughness in the distribution played a key role in bonding properties. Performance degradation due to close treatment was also distribution‐dependent.

Effect of Different Laser Parameters on Surface Physical Characteristics and Corrosion Resistance of 20 Steel in Laser Cleaning

The rusting of metals brings huge losses to the industry every year, and post-treatment of rusted metals to restore their properties to the initial state is a hot topic of current research. In particular, 20 steel, which is widely used in various structural components such as ships, is prone to oxidation in atmospheric environment. Therefore, in this study, a nanosecond pulsed laser was used to remove the rust layer on the surface of 20 steel. The effects of different energy densities and spot overlap rates on the roughness, surface morphology, chemical composition, microhardness and corrosion resistance of the rust layer were analyzed. The results showed that the best cleaning effect was achieved at an energy density of 4.26 J/cm2 and a spot overlap rate of 75%. Under these conditions, the rust layer was completely removed without damage to the substrate, and it even improved the corrosion resistance of 20 steel. At energy densities of 1.42 J/cm2 and 2.84 J/cm2, the rust layer was not completely removed, while at 5.68 J/cm2, the rust layer was removed but the substrate was damaged. In addition, the mechanism of rust removal and substrate damage is discussed.

The Evolution of Hillslope Hydrology: Links Between Form, Function and the Underlying Control of Geology

AbstractForm and function are two major characteristics of hydrological systems. While form summarizes the structure of the system, function represents the hydrological response. Little is known about how these characteristics evolve and how form relates to function in young hydrological systems. We investigated how form and function evolve during the first millennia of landscape evolution. We analyzed two hillslope chronosequences in glacial forelands, one developed from siliceous and the other from calcareous parent material. Variables describing hillslope form included soil physical properties, surface, and vegetation characteristics. Variables describing hydrological function included soil water response times, soil water storage, drainage, and dominant subsurface flow types. We identified links between form and hydrological function via cluster analysis. Clusters identified based on form were compared in terms of their hydrological functioning. The comparison of the two different parent materials shows how strongly landscape evolution is controlled by the underlying geology. Soil pH appears to be a key variable influencing vegetation, soil formation and subsequently hydrology. At the calcareous site, the high buffering capacity of the soil leads to less soil formation and fast, vertical subsurface water transport dominates the water redistribution even after more than 10,000 years of landscape evolution. At the siliceous site, soil acidification results in accumulation of organic material, a high water storage capacity, and in podsolization. Under these conditions water redistribution changes from vertical subsurface water transport at the young age classes to water storage in the organic surface layer and lateral subsurface water transport within 10,000 years.

Effect of Pigment-Acrylic Binder Ratio on the Surface and Physical Properties of Resin Finished Leather

The current study attempts to investigate the surface phenomenon and physical characteristics of leather finished with brown pigment and different types of acrylic binders. Using the contact angle measurements of three different liquids on the above finished leathers and films, the surface energy and work of adhesion were evaluated. The pigment to acrylic binder ratio (PABR) for best adhesion of finish film on the leather surface was optimized using the contact angle goniometer. Different types of acrylic binder films were coated and their surface behaviour was studied. The crust leather was coated with different types of pigment-acrylic binder (Very Soft, Soft and Medium Soft) finish formulations. The contact angle of both the acrylic films and the PABR finished leathers were measured against Water, Dimethyl sulfoxide (DMSO) and Hexadecane (HD). According to the study’s results, the surface properties of finished leather were directly related to the degree of wetting. The PABR was found to be effective at 1:3 for very soft binder, 1:2.5 for soft, 1:2 for medium soft binders due to higher contact angle and lower surface energy values (γsv). At 1:3 and 1:2.5, the contact angle of very soft and soft binder leather was 82.62° and 83.45° and for medium soft binder it was 82.67° at 1:2 ratio. The surface energy values of optimized PABR of very soft binder (1:3) was 28.29 (mN/M), soft binder (1:2.5) was 27.50 (mN/m) and medium soft binder (1:2) was 29.27 (mN/m). The optimized PABR work of adhesion values of very soft binder, soft binder and medium soft binder was 82.15 (mJm-2), 81.11 (mJm-2), 82.09 (mJm-2). In order to correlate the observed surface properties with leather finish properties, finished leathers were tested for finish adhesion, vamp flexing value, water vapour permeability, wet and dry rub fastness. According to the water vapour permeability, soft and medium binder showed good permeation due to the uncovering of nanopores. But the adhesion, grain crack resistance and grain smoothness were higher in the case of the soft binder. Overall leather properties divulges that the pigment to binder ratio and the type of binder plays an important role in surface properties of the finished leather. This study enables us to determine the optimal PABR for effective finish properties to meet the required leather standards for various usage, as well as better utilisation of finishing chemicals.

Research progress on photocatalytic reduction of CO2 based on ferroelectric materials.

Transforming CO2 into renewable fuels or valuable carbon compounds could be a practical means to tackle the issues of global warming and energy crisis. Photocatalytic CO2 reduction is more energy-efficient and environmentally friendly, and offers a broader range of potential applications than other CO2 conversion techniques. Ferroelectric materials, which belong to a class of materials with switchable polarization, are attractive candidates as catalysts due to their distinctive and substantial impact on surface physical and chemical characteristics. This review provides a concise overview of the fundamental principles underlying photocatalysis and the mechanism involved in CO2 reduction. Additionally, the composition and properties of ferroelectric materials are introduced. This review expands on the research progress in using ferroelectric materials for photocatalytic reduction of CO2 from three perspectives: directly as a catalyst, by modification, and construction of heterojunctions. Finally, the future potential of ferroelectric materials for photocatalytic CO2 reduction is presented. This review may be a valuable guide for creating reasonable and more effective photocatalysts based on ferroelectric materials.

Fabricating chitosan/low-density polyethylene (CS-LDPE) films and its efficacy to prolong shelf life of rainbow trout fish

This study aimed to explore how fabrication methods can influence surface morphology, physical, and mechanical characteristics of chitosan and low-density polyethylene (CS-LDPE) films to fulfill requirements of sustainable food packaging. The efficacy of CS-LDPE film for improving shelf life of rainbow trout fish products was also investigated. The field emission scanning electron microscopy assessment revealed that employing the two-step fabrication approach in the presence of grafted maleic anhydride (PE-g-MA) as a compatibilizer modified the surface morphology of the films, implying a better miscibility of constituents. Adding chitosan adversely influenced the thermal, mechanical, and morphological characteristics of the CS-LDPE films, which were mitigated by reducing chitosan size and application of 10 % PE-g-MA compatibilizer. According to the experimental assessments, two-step fabricated films consisting of 15 % chitosan and 10 % grafted maleic anhydride (PE-g-MA) was the best sustainable composite displaying the closest properties compared with the conventionally utilized LDPE films. Exploring several biochemical indices, including pH, peroxide level, membrane integrity (TBARS), free fatty acids (FAAs), and total volatile basic nitrogen (TVB-N) manifested that packaging fish samples with CS-LDPE improved the shelf life. The most pronounced differences between two packaging types were observed in the sixth day of storage time. Moreover, total viable count, Pseudomonas spp. count, and Enterobacteriaceae count markers revealed that the employing CS-LDPE film declined in the microbial proliferation rate, thereby prolonging shelf life of fishes. This study underlined the significance of CS-LDPE films to fulfilling needs for sustainable food packaging, conferring competitive advantage, and prolonging the food shelf life.

Engineered hydrochar production methodologies, key factors influencing agriculture wastewater treatment, and life cycle analysis: A critical review

For intensive food production, a range of chemical compounds are used to increase production, reduce the amount of weeds, and prevent pest infestation. Therefore, agricultural wastewater discharge to water bodies creates human health and environmental risks. This highlights the need for technologies to remove organic and inorganic pollutants, where adsorption using carbon-based materials has emerged as a cost-effective and promising alternative for agricultural wastewater treatment with high removal efficacy and alignment with the circular economy concept by generating value-added products, achieving energy conservation and reducing the environmental footprint. Among the different adsorbent materials, hydrochar (HC) has attracted attention because, compared to the thermal processes used for synthesizing other carbon-based materials, it requires relatively milder production conditions and possesses higher adsorption capability for water pollutants. Although HC holds advantages for the adsorption of water pollutants, HC modification using different methods has been found to improve the properties, including adsorption capacity. Accordingly, engineered hydrochar (EHC) has attracted research attention. However, past research publications show that the investigations have focused on material characterization and removal rates, with little knowledge created of the environmental impacts of HC production, application, and disposal. This study reviews current knowledge on EHC synthesis, characteristics, water treatment applications, and life cycle analysis. Initially, production methodologies were investigated to understand their influence on key surface physical and chemical characteristics. This was followed by assessing EHC efficacy for water and wastewater treatment. Finally, the environmental footprint of EHC production, application, and disposal was evaluated to identify critical knowledge gaps and to provide recommendations for future research.

Evaluation of two implant-supported fixed partial denture abutment designs: Influence on screw surface characteristics.

To compare screw surface characteristics between hemi-engaging and non-engaging implant-supported fixed partial denture (FPD) designs after cyclic loading. Twenty-four implants measuring 4.3 × 10mm were mounted on acrylic resin blocks. Specimens were divided into two groups. An experimental group included twelve 3-unit FPD with a hemi-engaging design; a control group included twelve 3-unit FPDs with the conventional design of two non-engaging abutments. Both groups were subjected to two types of cycling loading (CL), first axial loading, and then lateral loading at 30°. Load was applied to the units one million times (1.0 × 106 cycles) for each loading axis. Data on screw surface roughness in three locations and screw thread depth were collected before (BL) and after (AL) each loading type. Screw surface roughness was measured in μm using a mechanical digital surface profilometer and optical profiler. To evaluate screw thread depth in μm, an upright optical microscope Axio-imager 2 was used. To confirm readings made from the optical microscope, four random samples were selected from each group for scanning electron microscopy (SEM) analysis. The effect of cyclic loading was evaluated by averaging values across the two screws within each specimen, then calculating difference scores (DL) between BL and AL (DL = AL - BL). Additional difference scores were computed between the non-engaging screws in each experimental group specimen, and one randomly selected non-engaging screw in each control specimen. This difference was referred to as the non-engaging DL. Statistical significance was assessed using Mann-Whitney U tests (α = 0.05). Comparisons of DL and non-engaging DL by loading type revealed one significant difference regarding surface roughness at the screw thread. Significantly greater mean changes were observed after axial loading compared to lateral loading regarding both DL (axial M = -0.36 ± 0.08; lateral M = -0.21 ± 0.09; U = 20; p = 0.003) and non-engaging DL (axial M = -0.40 ± 0.22; lateral M = -0.21 ± 0.11; U = 29; p = 0.013). No significant differences in screw surface roughness in other sites or thread depth were found between the experimental and control abutment designs in DL or in non-engaging DL. No significant differences were found for DL (axial U = 13, p = 0.423; lateral U = 9, p = 0.150;) or non-engaging DL (axial U = 13, p = 0.423; lateral U = 18, p = 1.00). Results suggest that overall, changes in screw surface physical characteristics did not differ between hemi-engaging and non-engaging designs after evaluating screw surface roughness and thread depth before and after axial and lateral cyclic loading.

Physical characteristics of soil-biodegradable and nonbiodegradable plastic mulches impact conidial splash dispersal of Botrytis cinerea.

Botrytis cinerea causes gray mold disease of strawberry (Fragaria ×ananassa) and is a globally important pathogen that causes fruit rot both in the field and after harvest. Commercial strawberry production involves the use of plastic mulches made from non-degradable polyethylene (PE), with weedmat made from woven PE and soil-biodegradable plastic mulch (BDM) as emerging mulch technologies that may enhance sustainable production. Little is known regarding how these plastic mulches impact splash dispersal of B. cinerea conidia. The objective of this study was to investigate splash dispersal dynamics of B. cinerea when exposed to various plastic mulch surfaces. Mulch surface physical characteristics and conidial splash dispersal patterns were evaluated for the three mulches. Micrographs revealed different surface characteristics that have the potential to influence splash dispersal: PE had a flat, smooth surface, whereas weedmat had large ridges and BDM had an embossed surface. Both PE mulch and BDM were impermeable to water whereas weedmat was semi-permeable. Results generated using an enclosed rain simulator system showed that as the horizontal distance from the inoculum source increased, the number of splash dispersed B. cinerea conidia captured per plate decreased for all mulch treatments. More than 50% and approximately 80% of the total number of dispersed conidia were found on plates 10 and 16 cm away from the inoculum source across all treatments, respectively. A significant correlation between the total and germinated conidia on plates across all mulch treatments was detected (P<0.01). Irrespective of distance from the inoculum source, embossed BDM facilitated higher total and germinated splashed conidia (P<0.001) compared to PE mulch and weedmat (P = 0.43 and P = 0.23, respectively), indicating BDM's or embossed film's potential for enhancing B. cinerea inoculum availability in strawberry production under plasticulture. However, differences in conidial concentrations observed among treatments were low and may not be pathologically relevant.

DHI-GHM: Real-time and forecasted hydrology for the entire planet

An operational global hydrological model (DHI-GHM) has been developed that provides historical, real-time, 10-day and seasonal forecast simulations at the global scale. DHI-GHM is comprised of a distributed gridded rainfall-runoff model with a spatial resolution of 0.1° and an agile kinematic routing model that moves water between model grid cells and sub-catchments and in the river system. Model output includes gridded hydrological variables, such as soil moisture content and different runoff components, and discharge at more than 1 million river points globally. DHI-GHM uses a novel parameterization scheme, where global data products of land surface physical characteristics are used to establish relations with model parameters, and thus DHI-GHM does not rely on local discharge data for model calibration. Multiple forcing datasets were tested, and the combination of ERA5 precipitation and Priestley-Taylor potential evaporation yielded the overall best results with a median KGE of 0.51 and average water balance error of 0.78% based on data from 1667 discharge stations worldwide. The model results and the operational system are particularly relevant for organizations with national, regional, or global scope who need information on large areas at once and for data scarce areas or projects without resources for local scale models.

Adsorption-Desorption Behavior and Pesticide Bioavailability of Biochar in Soil

Biochar is a porous carbon-rich substance generated by anoxic pyrolysis of biomass. Biochar has a high adsorption capacity for organic contaminants in water and soil environmental media due to its large specific surface area and surface physical and chemical characteristics. The effects of biochar application on the adsorption-desorption behavior and bioavailability of pesticides in soil are illustrated in this paper; biochar can strongly adsorb pesticides in soil due to its loose and porous properties, large specific surface area and surface energy, and highly aromatic structure. Residual pesticide pollutants are reduced, as is desorption hysteresis, which reduces pesticide desorption. Furthermore, the use of biochar reduced the absorption and efficacy of pesticides in soil. At the same time, it describes the present gaps in research on the influence of biochar on pesticide migration mechanisms and its application in pesticide pollution control, and it identifies the major scientific issues that need to be addressed. Finally, the potential application of biochar in pesticide pollution management is discussed.

Secondary silane grafting on aramid fibers improves the interfacial bonding performance in textile composite materials

To improve the chemical and physical surface features of aramid fibers and the bonding quality at the interface, carbon nanotubes, dopamine and silane coupling reagent KH560 were used to modify the surface of aramid fibers. The fiber surface was characterized by FTIR, XPS, SEM and AFM. The single-fiber specific strength, surface roughness, wettability and interfacial shear strength of the modified fiber were quantified. Finally, the uniaxial tensile behaviour of the textile composite laminate with the modified fibers was tested. The experimental results show that: after the grafting of silane coupling reagent as a second modification step, the amount of oxygen-containing groups on the surface of aramid fibers, and the surface roughness, and the ability to impregnate resin are further improved. The single-fiber specific strength, the interfacial shear strength by fiber pull-out tests, and the tensile strength of the laminate are increased by 21.62%, 73.57%, and 51.60%, respectively. This work demonstrates a general surface modification strategy working for diverse types of fibers, synthetic or natural. The present findings help to develop a broad range of high-performance textile composites to address long-term challenges in structural engineering.

Reversible Self-Assembled Monolayers with Tunable Surface Dynamics for Controlling Cell Adhesion Behavior.

Cells adhering onto surfaces sense and respond to chemical and physical surface features. The control over cell adhesion behavior influences cell migration, proliferation, and differentiation, which are important considerations in biomaterial design for cell culture, tissue engineering, and regenerative medicine. Here, we report on a supramolecular-based approach to prepare reversible self-assembled monolayers (rSAMs) with tunable lateral mobility and dynamic control over surface composition to regulate cell adhesion behavior. These layers were prepared by incubating oxoacid-terminated thiol SAMs on gold in a pH 8 HEPES buffer solution containing different mole fractions of ω-(ethylene glycol)2-4- and ω-(GRGDS)-, α-benzamidino bolaamphiphiles. Cell shape and morphology were influenced by the strength of the interactions between the amidine-functionalized amphiphiles and the oxoacid of the underlying SAMs. Dynamic control over surface composition, achieved by the addition of inert filler amphiphiles to the RGD-functionalized rSAMs, reversed the cell adhesion process. In summary, rSAMs featuring mobile bioactive ligands offer unique capabilities to influence and control cell adhesion behavior, suggesting a broad use in biomaterial design, tissue engineering, and regenerative medicine.

Impact of an engineered micro-patterned interface on chitosan/glycerol membranes for wound healing

Biomimetic materials are of great significance in wide applications. As a bioactive polysaccharide, chitosan (CS) has attracted much attention in multiple fields. Inspired by the natural shark skin interface, herein, we proposed a methodology to obtain serial biomimetic CS/glycerol membranes via a facile mold casting and solvent evaporation process under mild aqueous conditions. The surface morphology, chemical structures, and physical characteristics of the developed membranes were determined by scanning electron microscopy, Fourier transformed infrared spectroscopy, tensile measurement, water vapor transmission rate, liquid uptake behavior, solubility, and dynamic water contact angle tests. Furthermore, in vitro and in vivo biological assays were performed, including antibacterial ability, hemostatic performance, hemolytic reaction, cytotoxicity evaluation, and contaminated wound healing assessment. Compared with the flat membranes, the micro-patterned CS/glycerol membranes show the higher water-absorbing ability (up to ca. 26-fold@30 min), moderate tensile strength (8.5–14.7 MPa), superior bacteriostasis (84.9% to 98.6% against S. aureus, 84.3% to 99.6% against E. coli), decent hemostat efficacy (within 75.7 s), low hemolysis rates (less than 0.5%), and benign cytotoxicity (84.2% to 98.4% of viability), which favor promoting contaminated wound healing. Thus, the biomimetic micro-patterned membranes improve bioactive performance and show the merits of simple operation, low cost, and easy scale-up. All these properties indicate that the hybrid micro-patterned membrane could be used as a suitable candidate for dermal wound dressings and open up the insights for developing other bionic interfaces in future potential applications.

Potocatalytic antifouling membrane with dense nano-TiO2 coating for efficient oil-in-water emulsion separation and self-cleaning

Herein, a dense rutile nano-titanium dioxide (TiO2) coating was constructed on the nonwoven fabric (NWF) membrane surfaces via the bio-inspired TiO2 sol-gel method. The mineralization of nano-TiO2 was large-scale and uniform on the non-woven fabrics (NWF) surface, reducing membrane surface roughness and pore sizes; nevertheless, largely improving the dynamic water super-wetting, water penetration, and underwater oil repellency due to the excellent water affinity. Nuclear magnetic resonance (NMR) revealed the hydration layer of the NWF was reinforced by the surface-mineralized nano-TiO2, thus preventing the bovine serum albumin (BSA) and emulsified oil droplets from fouling. Even after the 180 min of continuous emulsion separation, the mineralized NWF (TiO2-PDA/PEI-NWF-M) only suffered from the mild decline of permeation fluxes from ∼55 L/m2•h to ∼43 L/m2•h and oil rejection from ∼94% to ∼83%, respectively. After illuminated under UV light, it was recovered successfully because of the in-situ generation of reactive species (e.g. •OH, •O2− and 1O2) on TiO2 weakened the interaction of foulants on the membrane surface. The photoactive self-cleaning provided the TiO2-PDA/PEI-NWF-M with better efficiency of oil-fouling reduction, permeation fluxes recovery, and oil removal than those of simple water and harsh NaClO washing. Most importantly, the TiO2-PDA/PEI-NWF-M maintained its surface physical and chemical characteristics after vigorous cross-flow shearing for 48 h. It provided the practical potential in developing the high-efficient and free-chemical self-cleaning with the high and stable flux recovery for the tricky crude oil/water emulsion remediation.

Dedicated satellite remote sensing combined with global navigation satellite system data used to remotely measure the status of land desertification

Desert use and its management play a significant role in the conservation of land resources. The premise of developing and using deserts based on local conditions includes managing the physical characteristics of sandy desert land. We explore the various achievements of remote sensing of bare soil moisture and, specifically, employ two methods involving the remote sensing of surface physical characteristics, dynamic measurements, and Global Navigation Satellite System-Reflectometry (GNSS-R) sensing by satellite. Some observation parameters of the Earth’s surface emissivity are summarized, which were attained through remote observations. In addition, the bright temperature inversion model on the soil temperature, moisture content, and texture, and the GNSS-R soil moisture sensor and inversion model were analyzed. The influence of horizontal polarization of the surface roughness on the results of dedicated satellite measurement of emissivity was also analyzed. Further, a sensing separation model of soil moisture particle size for GNSS-R was derived. Soil moisture is related to soil reflectivity. The soil particle size determines soil porosity, which is directly related to the evaporation rate of water and affects the surface temperature, thereby affecting soil emissivity. We determined that a level of complementarity exists between the enhancement of emissivity and attenuation of reflectivity by roughness as well as between the emissivity of dedicated satellite measurement line polarization and the reflectivity of GNSS-R measurement with circular polarization. Based on this complementarity, a method of GNSS-R and dedicated satellite collaborative measurement of soil texture using satellite data is proposed. The experimental results show that the two methods are sensitive to the soil moisture content, but the sensitivity to the mixed components of sandy soil is very poor. Both the sensitivity of GNSS-R sensing to sand particle size and sand surface temperature are better than those of dedicated satellite sensing.

Effect of laser energy density on surface physical characteristics and corrosion resistance of 7075 aluminum alloy in laser cleaning

In this paper, the pulsed laser cleaning technology was used to remove the oxide film on the surface of 7075 aluminum alloy. The effects of different laser energy density on the surface morphology, surface composition, microhardness and corrosion resistance of 7075 aluminum alloy were analyzed. The removal mechanism of oxide film on 7075 aluminum alloy surface by laser cleaning was studied. The results show that laser cleaning 7075 aluminum alloy oxide film is mainly based on gasification mechanism and shock wave generated by explosion. After laser cleaning, the surface microhardness of 7075 aluminum alloy increases from 158.5HV to 171.9HV. After removing the oxide film on the surface of aluminum alloy by laser, the corrosion resistance of the surface decreases, and surface melting also affect the corrosion resistance of the cleaned surface. In this study, when the energy density is in the range of 1.43 J/cm2 to 1.82 J/cm2, the oxide film can be largely removed without damaging the substrate. At the same time, the corrosion resistance of the surface is ensured as much as possible. When the energy density reaches 1.82 J/cm2 in this research, the mass percentage of oxygen on the cleaned surface is reduced to 2.03%, and the microhardness is 167.7HV.

A Study on the Physical Properties and Surface Characteristics of Hanji by the Treatment of Soybean Juice

Hanji has hydrophilicity due to the hydroxyl group (-OH) in cellulose fibers, and has a porous structure due to micropores between fibers. To complement these features, treatment is essential on the surface of Hanji. As a surface treatment method, a common method uses glue and alum, and in addition, there are soybean juice and perilla oil treatment methods. Among them, the soybean juice treatment method is to treat the soybean juice on the surface of Hanji, so that a coating film is formed on the surface, resulting in waterproofing and ink settling without spreading. However, there are currently insufficient scientific studies on the method of making and treating soybean juice, material characteristics, and the properties of Hanji after soybean juice treatment. Therefore, in this study, after applying soybean juice by concentration and number of applications the physical properties and surface characteristics of Hanji coated with soybean juice were evaluated. As a result, as the concentration of soybean juice and the number of treatments increased, the smoothness increased as the coating formed on the surface of Hanji, and the sizing effect was also observed. It was also observed that the spread of ink decreased. However, as the concentration and the number of treatments increased, the tensile strength became weaker, but the flexibility tended to increase.