Surface Characteristics Research Articles

Geopolymer Paving Blocks Made From Fly Ash and Bagasse Ash Under Different Curing Conditions

This research aimed to study the geopolymer paving blocks made from fly ash and bagasse ash under different curing conditions. The fly ash was replaced by bagasse ash at 10, 20 and 30% by weight of the binder. Sodium hydroxide and sodium silicate solutions were used as activated solutions. Three curing methods were studied: curing with plastic wrap (PT), curing at 35 °C for 1 hour (OV), and curing with sunlight (SU). Compressive strength and water absorption were investigated. The surface characteristics of the geopolymer paving block were studied using microstructure techniques. Sun curing provided the highest compressive strength. The water absorption values increased with an increase in the replacement percentage of bagasse ash. The surface of the geopolymer paving blocks showed remnants of the starting materials from the reaction. The geopolymer paste from the geopolymerization reaction was also found. This indicated the beneficial use of waste materials to produce environmentally friendly building materials.

Comparative Study of Chemical Activation and Physical Activation Approach to Optimize Biomass-Based Doped Carbons for Energy Applications

Abstract Two approaches have been utilized to optimize the energy storage characteristics of doped carbon materials derived from Lignosol, a biomass product, to address the rising energy demand issues. Herein, phosphorus and nitrogen co-doped carbon (PNDC) materials with varying doping agent volumes were synthesized by utilizing microwave irradiation. Chemical activation and physical activation were employed to enhance these materials’ characteristics. Chemical activation was performed in a one-pot, single-step process, rather than a traditional multi-step protocol, using small amounts of potassium hydroxide. Furthermore, the physical activation method required multiple steps: doped carbon was prepared via microwave, exposed to water, filtered, frozen and then dried. With this, the expansion properties of water at freezing temperatures were exploited to alter the materials’ surface characteristics. All materials were characterized and compared for their physicochemical properties. All defect ratios supported the presence of doping. Additional results revealed that both chemical and physical activation approaches effectively modify the topographical features as well as the electrochemical activity (charge storage) of the doped carbon materials. The chemically activated doped carbon exhibited the highest resulting surface area of 1352 m2/g and a specific capacitance value of 347 F g-1 with excellent cycling stability as compared to other similarly synthesized materials.

An insight Into Surface and Diffusion Characteristics of UiO‐66@ZIF‐8 Core–Shell MOF for Asymmetric Supercapacitors with Unprecedented Energy Density

AbstractIn this study, nanosized zeolitic imidazolate framework‐8 (ZIF‐8) crystal has been produced on the universitetet i oslo‐66 (UiO‐66) metal–organic framework (MOF) to make core–shell structure using a layer‐by‐layer deposition method. In comparison to the pristine UiO‐66 and ZIF‐8, the core–shell MOF exhibits superior performance in terms of specific capacitance. This enhanced performance is attributed to its remarkable ability to facilitate the rapid diffusion of electrolyte ions through nanosized ZIF‐8 and enhance the electron transfer process involving the inner and outer metal ions within the UiO‐66@ZIF‐8 structure. Remarkably, the core–shell structure achieves an impressive specific capacitance of 588.8 F g−1 at a current density of 0.5 A g−1 using 1 m sulfuric acid (H2SO4) aqueous electrolyte. Additionally, the UiO‐66@ZIF‐8 core–shell material is demonstrated as a positive electrode, coupled with activated carbon (AC) derived from waste tissue paper serving as the negative electrode, in the fabrication of an asymmetric supercapacitor (ASC) device. At a power density of 400 W kg−1, this assembled asymmetric device delivers a notably high energy density of 53 Wh kg−1 along with a cyclic stability of 94.8% after 10 000 cycles. This study substantiates the superior performance of the UiO‐66@ZIF‐8 core–shell MOF structure as a highly effective supercapacitor electrode material, surpassing the performance of its pristine MOF counterparts.

Utilizing olive leaves biomass as an efficient adsorbent for ciprofloxacin removal: characterization, isotherm, kinetic, and thermodynamic analysis.

Olive leaves were utilized to produce activated biomass for the removal of ciprofloxacin (CIP) from water. The raw biomass (ROLB) was activated with sodium hydroxide, phosphoric acid, and Dead Sea water to create co-precipitated adsorbent (COLB) with improved adsorption performance. The characteristics of the ROLB and COLB were examined using SEM images, BET surface area analyzer, and ATR-FTIR spectroscopy. COLB has a BET surface area of 7.763 m2/g, markedly higher than ROLB's 2.8 m2/g, indicating a substantial increase in adsorption sites. Through investigations on operational parameters, the optimal adsorption efficiency was achieved by COLB is 77.9% within 60min, obtained at pH 6, and CIP concentration of 2mg/mL. Isotherm studies indicated that both Langmuir and Freundlich models fit the adsorption data well for CIP onto ROLB and COLB, with R2 values exceeding 0.95, suggesting effective monolayer and heterogeneous surface adsorption. The Langmuir model revealed maximum adsorption capacities of 636mg/g for ROLB and 1243mg/g for COLB, highlighting COLB's superior adsorption capability attributed to its enhanced surface characteristics post-modification. Kinetic data fitting the pseudo-second-order model with R2 of 0.99 for ROLB and 1 for COLB, along with a higher calculated qe for COLB, suggest its modified surface provides more effective binding sites for CIP, enhancing adsorption capacity. Thermodynamic analysis revealed that the adsorption process is spontaneous (∆Go < 0), and exothermic (∆Ho < 0), and exhibits a decrease in randomness (∆So < 0) as the process progresses. The ΔH° value of 10.6kJ/mol for ROLB signifies physisorption, whereas 35.97kJ/mol for COLB implies that CIP adsorption on COLB occurs through a mixed physicochemical process.

Optimization of preparation conditions and performance of a new degradable soil water retaining agent

Using polyaspartic acid (PAsp) and bentonite (BT) as the main raw materials, a new type of degradable soil water retaining agent (PAsp-AA/BT) was synthesized by microwave radiation. The optimum synthesis conditions and comprehensive properties of PAsp-AA/BT were discussed and the structure and surface characteristics of PAspsp-AA/BT were characterized by FTIR, SEM, XRD and TGA in the paper. The results showed that the optimum synthesis conditions of PAsp-AA/BT were as follows: the dosages of polyaspartic acid (PAsp), bentonite (BT), initiator potassium persulfate, crosslinking agent N,N′-methylene bisacrylamide was 5, 3, 0.3, 0.03%, respectively, the neutralization degree of acrylic acid was 75%, and the microwave power was 490W. Under this condition, the absorption ratio of the synthesized PAspsp-AA/BT in deionized water and 0.9% NaCl solution was 953 and 164 g/g, respectively. The synthesized PAsp-AA/BT had a high water absorption rate, good water retention and repeated water absorption, and the degradation rate in soil within 30 days reached 32.75%, with good degradation effect. The analysis of SEM, FT-IR, XRD and TGA showed that: the surface of PAsp-AA/BT was rough and had obvious pore structure, which was conducive to the diffusion of water molecules; polyaspartic acid, bentonite and acrylic acid were polymerized; the cross-linking structure was formed between polyaspartic acid, bentonite and acrylic acid; the product of PASP-AA/BT had good thermal stability. This study provides a new soil water retaining agent, which is helpful for the better development of soil water retaining agent research.

Renewable cold plasma exposed activated carbon-derived eucalyptus leaves (EL) as electrode in fabricating low-cost energy storage devices

ABSTRACT The activated carbon made from Eucalyptus leaves was created using an environmentally friendly physical activation process, and it was then subjected with the low temperature plasma to increase its surface area and porosity, as shown by structural and morphological characteristics. The nanoparticles’ surface layers are altered by the plasma treatment, improving surface characteristics like wettability, adhesion, and surface area that were investigated using structural, morphological, and electrochemical studies. The air-plasma-treated KOH exhibits a specific capacitance of 1591 F/g for 1.5 mA, which can be utilized to prepare an electrode material for the energy storage application. The electrochemical investigation was conducted for the untreated and air, oxygen-plasma-treated carbon, demonstrating the better specific capacitance for the air plasma treatment, which can be used to prepare an electrode material for the low-cost fabrication of the devices.

Zr-based bulk metallic glasses in PBF-LB/M: near-polished surface quality in the as-built state

AbstractThis study investigates the relationship between varying contour scanning parameters and their impact on both surface characteristics and mechanical performance of the glass-forming Zr59.3Cu28.8Al10.4Nb1.5 produced via PBF-LB/M. Near-polished surface states with Ra values below 1 µm were achieved. The study identifies increased laser power as a key factor in reducing the surface roughness, while repetitive scanning exhibits only marginal improvements in surface quality. Partial crystallization on the surface of the amorphous samples is found on the as-built surfaces. However, it appears to be confined to depths below 50 µm. Impressively, the material showcases large mechanical strength in the as-built condition, evidenced by a high flexural strength of 2.2 GPa combined with approximately 1% plastic deformation. These findings offer initial insights into optimizing additive manufacturing processes for BMGs, guiding the enhancement of both surface quality and mechanical robustness in Zr-based metallic glass fabricated via PBF-LB/M techniques.

Evaluation of the surface characteristics and antibacterial properties of Titanium dioxide nanotube and methacryloyloxyethylphosphorylcholine (MPC) coated orthodontic brackets-a comparative invitro study.

White spot lesions are the most common iatrogenic effect observed during orthodontic treatment. This study aimed to compare the surface characteristics and antibacterial action of uncoated and coated orthodontic brackets. Sixty commercially available stainless steel brackets were coated with TiO2 nanotubes and methacryloyloxyethylphosphorylcholine. The sample was divided into Group 1: uncoated orthodontic brackets, Group 2: Stainless steel brackets with TiO2 nanotubes coating, Group 3: Stainless steel brackets with methacryloyloxyethylphosphorylcholine coating, and Group 4: Stainless steel brackets with TiO2 nanotubes combined with methacryloyloxyethylphosphorylcholine coating. Surface characterization was assessed using atomic force microscopy and scanning electron microscopy. Streptococcus mutans was selected to test the antibacterial ability of the orthodontic brackets, total bacterial adhesion and bacterial viability were assessed. The brackets were subjected to scanning electron microscopy to detect the presence of biofilm. The surface roughness was the greatest in Group 1 and least in Group 2 followed by Group 4 and Group 3 coated brackets. The optical density values were highest in Group 1 and lowest in Group 4. Comparison of colony counts revealed high counts in Group 1 and low counts in Group 4. A positive correlation between surface roughness and colony counts was obtained, however, was not statistically significant. The coated orthodontic brackets exhibited less surface roughness than the uncoated orthodontic brackets. Group 4 coated orthodontic brackets showed the best antibacterial properties. Coated orthodontic brackets prevent adhesion of streptococcus mutans and reduces plaque accumulation around the brackets thereby preventing formation of white spot lesions during orthodontic treatment.

Melting phenomenon of thermally stratified MHD Powell–Eyring nanofluid with variable porosity past a stretching Riga plate

Abstract Recently, experts have become particularly interested in the treatment of disorders caused by magnesium shortage. Hypomagnesemia is produced by a magnesium deficit in the blood, which is an additional stimulation for different diseases such as vomiting, drowsiness, nausea, loss of appetite, and so on. To compensate for this shortage, magnesium is injected as a nanoparticle in the blood (base fluid). The properties of these magnesium nanoparticles specifically their size, dispersion, and surface characteristics are crucial for optimizing their bioavailability and therapeutic efficacy. Advanced material characterization techniques ensure the stability and enhanced performance of these nanoparticles in the physiological environment. Based on these applications, the current research aims to address magnesium deficiency via Powell–Eyring nanofluid flow distorted by the linearly stretchable sheet in the region of the stagnation point. Linear thermal stratification, viscous dissipation, and Joule heating are used to reveal the heat transport features. The magnetic field is applied to the nanofluid at an angle α to further control the fluid dynamics and nanoparticle behavior. Transformations are used to create a set of dimensionless governing equations. Comparative graphs are used to explain the physical behaviors of temperature and velocity fields, demonstrating how material properties impact fluid dynamics. The well-known convergence method (homotopy analysis method) is used to solve the model by comparing graphs.

A Comparative Evaluation of Surface and Elemental Changes in Stainless Steel and Titanium Orthodontic Mini-screw Implants: A Multi-arm Randomized Control Trial.

The present study aimed to compare and quantify the surface changes seen in two most commonly used orthodontic miniscrew implants (MSI) materials; titanium and stainless steel after their clinical use. 40 MSIs (20 titanium and 20 stainless steel) were retrieved from the maxillary arch of 20 subjects (13 females and 7 males) in the age group of 18 - 27 years (mean age=22.4 ± 3.83 years) after their intended use. 40 (20 titanium and 20 stainless steel) asreceived MSIs were used as control. All the MSIs were analyzed under a Scanning Electron Microscope (SEM) for the characterization of their morphological condition (blunting of tip, surface defects and corrosion). Furthermore, Energy Dispersive X-ray (EDX) microanalysis was carried out to study the changes in surface characterization. When imaged using SEM, as-received Titanium and Stainless Steel MSIs demonstrated a relatively smooth surface with no surface defects. However, the retrieved titanium and stainless-steel implants showed increased surface defects (both corrosion and cracks) with the difference being statistically significant. The retrieved Titanium MSIs (115.31±24.38μm) showed 4 times more blunting compared to the retrieved Stainless-steel MSIs (29.74±8.56 μm), with the latter showing 2-3 times more surface corrosion. Clinical usage had pronounced effects on both Titanium and Stainless steel MSI alloys in terms of changes in the surface characteristics. While stainless steel MSIs are more susceptible to surface corrosion, Titanium MSIs exhibit greater alterations in the form of tipblunting and cracks in screw threads.

Comparative Evaluation of Icon Resin Infiltration and Clinpro XT Varnish Effects on Surface Characteristics in Artificially Induced White Spot Lesions

Comparative Evaluation of Icon Resin Infiltration and Clinpro XT Varnish Effects on Surface Characteristics in Artificially Induced White Spot Lesions

Implementing robust outlier detection to enhance estimation accuracy of GNSS-IR based seasonal snow depth retrievals

ABSTRACT Monitoring snow depth variations aligned with the seasonal cycle is crucial for studies on climate change and its impacts due to global warming. Especially in terms of snow hydrology, the determination and continuous monitoring of snow depth to determine snow water equivalent is a priority in climate, water science, drought, flood, and inundation prediction studies, particularly in the water cycle. Recently, the so-called Global Navigation Satellite Systems – Interferometric Reflectometry (GNSS-IR) method enables to extract environmental radiometric and geometric characteristics of surface where the signals transmitted from the satellites reflect. The reflected signal follows an extra path than the direct one and causes a major error source for accurate point positioning but a useful tool for sensing the environment. However, outliers remain a challenge in long-term GNSS-IR estimations. In this study, we proposed a median-based robust outlier detection (ROD) approach for identifying outliers in long-term GNSS-IR snow depth estimations. To validate our approach, we analysed 5-year GNSS L1 SNR and L2 SNR data from 1 January 2015 to 31 December 2019 provided by AB33 and AB39 GNSS stations in Alaska, U.S.A. using the GNSS-IR method. We validated GNSS-IR estimations using snow depth measurements from the Coldfoot and Fort Yukon stations in the SNOTEL network. Applying ROD to long-term snow depth estimates increased the highest correlation from 91.58% to 94.93%, and reduced the lowest RMSE from 8.6 cm to 6.7 cm. In addition, the improvement rates calculated to assess the contribution of ROD to the results showed improvements of up to 6.9% in correlation and 26.1% in RMSE. Overall, the results demonstrate that ROD can be effectively used to detect outliers in long-term GNSS-IR snow depth time series.

Wear performance of Ti-based alloy coatings on 316L SS fabricated with the sputtering method: Relevance to biomedical implants.

This investigation was conducted to encapsulate 316L SS with a Ti-based alloy coating. The aim was to fabricate a coating using TiN, TiO2, and TiCoCr powders on 316L SS through the physical vapor deposition (PVD) sputtering process. The powders were consecutively coated on 316L SS through the PVD sputtering process with coating durations of 30, 60, and 90 min. Further microhardness, surface roughness, microabrasion, and adhesion strength tests were also carried out. A 60% improvement in abrasion resistance was observed in TiCoCr-coated samples compared to the uncoated substrate. The X-ray diffraction results confirmed the optimal formation of Ti alloy coatings with corresponding orientation over the SS substrates. Moreover, TiCoCr with a 90 min coating duration had much better surface characteristics than TiO2 and TiN. The 90 min coating duration should be optimal for coating in steel for bio-implants.

Polyvinyl alcohol (PVA) films: insights from crosslinking and plasticizer incorporation

Abstract The properties of polyvinyl alcohol (PVA) films are intricately influenced by factors such as polymer structure, fabrication method, the addition of plasticizers, and the molecular weight of monomers. In this research, we explore the implication of PVA films using a solution casting method to crosslink the polymer with boric acid (H3BO4), glycerol, and citric acid. This approach is compared with pure PVA films, establishing a valuable benchmark. High-concentration PVA membranes, incorporating glycerol as a plasticizer at specific concentrations, were also fabricated to broaden the experimental scope. Tensile strength tests, physicochemical property measurements, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were conducted to gain insights into the microstructure, surface characteristics, and mineral composition of the films. This comprehensive approach aims to enhance our understanding of the intricate relationship between PVA, plasticizers, and crosslinking agents, providing valuable insights for applications across diverse industries, including packaging, construction, and biomedical fields. The overarching objective of this research is to revolutionize the construction industry by developing polymer films that serve as the foundation for self-healing materials, fostering durability and innovation.

Efficient sequestration of plutonium from aqueous medium using nitrogen doped graphene nano walls

AbstractNitrogen doped graphene nanowall(s) deposited on carbon paper is employed in sequestration of trace-level plutonium from aqueous solution using batch adsorption technique. Surface and structural characteristics of the sorbent are studied using SEM and Raman spectroscopy, respectively. Radiometric α-counting of the supernatant solution showed &gt; 90% sorption at pH &gt; 7. Visual Minteq modelling revealed that Pu(OH)4 species is responsible for high sorption. Freundlich model evolved as the best fit, implying multilayer deposition on a heterogeneous surface as the mechanism of sorption. The combination of 10 M HNO3 and EDTA resulted in 75% desorption. The results are promising for the sequestration of trace-level plutonium.

Enhancing Surface Integrity and Quality through Roller Burnishing: A Comprehensive Review of Parameters Optimization, and Applications.

Surface integrity is a critical aspect in ensuring the quality of components or products, particularly in industries such as automotive, aerospace, and machinery where superior surface finish and prolonged functionality of cylindrical parts are essential. Burnishing, a chip-less cold working finishing process, enhances the surface finish of machined workpieces through plastic deformation. This review paper delves into various aspects of the burnishing process and its impact on surface properties, drawing insights from multiple research projects. It explores topics including residual stresses, surface roughness, microhardness, cooling strategies, and modeling techniques. Key findings underscore the influence of burnishing parameters such as speed, feed rate, penetration depth, and number of passes on surface roughness and microhardness. Moreover, the process induces compressive residual strains on the workpiece surface, with their magnitude varying based on operational parameters. The choice of cooling methods, including kerosene, minimum quantity lubrication (MQL), cryogenic cooling, and hybrid cooling, significantly affects surface integrity. Various modeling approaches, such as Artificial Neural Networks (ANN), Adaptive Neuro-Fuzzy Inference Systems (ANFIS), and Response Surface Methodology (RSM), aid in predicting and optimizing surface characteristics. Despite the extensive discussion on surface roughness, microhardness, residual stresses, cooling methods, and modeling, out-of-roundness in the burnishing process remains understudied and warrants further investigation. This review contributes valuable insights for enhancing surface qualities in manufacturing applications and deepening our understanding of the burnishing process.

A survey of methane point source emissions from coal mines in Shanxi province of China using AHSI on board Gaofen-5B

Abstract. Satellite-based detection of methane (CH4) point sources is crucial in identifying and mitigating anthropogenic emissions of CH4, a potent greenhouse gas. Previous studies have indicated the presence of CH4 point source emissions from coal mines in Shanxi, China, which is an important source region with large CH4 emissions, but a comprehensive survey has remained elusive. This study aims to conduct a survey of CH4 point sources over Shanxi's coal mines based on observations of the Advanced Hyperspectral Imager (AHSI) on board the Gaofen-5B satellite (GF-5B/AHSI) between 2021 and 2023. The spectral shift in centre wavelength and change in full width at half-maximum (FWHM) from the nominal design values are estimated for all spectral channels, which are used as inputs for retrieving the enhancement of the column-averaged dry-air mole fraction of CH4 (ΔXCH4) using a matched-filter-based algorithm. Our results show that the spectral calibration on GF-5B/AHSI reduced estimation biases of the emission flux rate by up to 5.0 %. We applied the flood-fill algorithm to automatically extract emission plumes from ΔXCH4 maps. We adopted the integrated mass enhancement (IME) model to estimate the emission flux rate values from each CH4 point source. Consequently, we detected CH4 point sources in 32 coal mines with 93 plume events in Shanxi province. The estimated emission flux rate ranges from 761.78 ± 185.00 to 12 729.12 ± 4658.13 kg h−1. Our results show that wind speed is the dominant source of uncertainty contributing about 84.84 % to the total uncertainty in emission flux rate estimation. Interestingly, we found a number of false positive detections due to solar panels that are widely spread in Shanxi. This study also evaluates the accuracy of wind fields in ECMWF ERA5 reanalysis by comparing them with a ground-based meteorological station. We found a large discrepancy, especially in wind direction, suggesting that incorporating local meteorological measurements into the study CH4 point source are important to achieve high accuracy. The study demonstrates that GF-5B/AHSI possesses capabilities for monitoring large CH4 point sources over complex surface characteristics in Shanxi.

Investigation of the surface characteristics of WC–Co structures under Local E-beam irradiation via experiments and molecular dynamics simulations

Investigation of the surface characteristics of WC–Co structures under Local E-beam irradiation via experiments and molecular dynamics simulations

One‐Step Synthesis of Thiol‐Functional Mesoporous Silica Nanospheres and Selective Removal of Cationic Dyes

AbstractThe surface characteristics of nanoparticles have a huge impact on adsorption effects. In this paper, thiol‐functional mesoporous silica nanospheres (MSNs−SH) are successfully prepared through simple one‐step hydrolysis and co‐condensation of tetraethyl orthosilicate and (3‐mercaptopropyl) triethoxysilane with hexadecyltrimethylammonium bromide and sulfobetaine 12 as dual‐template. The obtained MSNs−SH have high surface area (1260 m2 g−1), accessible mesopores (2.2 nm), great pore volume (1.7 cm3 g−1), and uniform adjustable diameter (90 nm). Furthermore, the diameter and pore‐size of MSNs−SH can be controlled via adjusting the ethanol content in the synthesis system. MSNs−SH exhibit a fast adsorption kinetics, marked adsorption capacity of cationic rhodamine B (RB 534.2 mg g−1), and remarkable selective adsorption for cationic dyes. Theoretical analysis reveals the adsorption behavior of RB on MSNs−SH follows the Langmuir isotherm models and pseudo‐second‐order kinetic. Additionally, the thermodynamic results indicate that the adsorption process is a spontaneous process driven by temperature. The results demonstrate that MSNs−SH are greatly potential for effectively removing cationic dyes from wastewater, with the advantages of simple preparation, high adsorption performance and perfect selectivity.

Equipment design and parameters recommendation of rubber modified 3D printed asphalt in pavement maintenance

As an advanced technology for pavement crack maintenance with high automation level, high precision and high efficiency, 3D asphalt printing technology can effectively improve worker safety and ensure the stability of maintenance quality. In order to optimize the printing parameters of rubber modified 3D printed asphalt (R-3DPA), a three-axis asphalt 3D printer was developed in this study through the design and selection of each component, and it was used for the 3D printing of R-3DPA strips, layers, and structures. Based on the comparison of continuity, uniformity, and width of R-3DPA strips, the recommended extrusion nozzle diameter, printing temperature, and printing speed parameter combinations were superiorly selected. According to the analysis of filling degree, width error and thickness of R-3DPA layers, the optimal printing strip width was recommended. Through the evaluation of integrity, surface characteristics and accuracy of R-3DPA structures, the suitable printing layer thickness was determined. The test results showed that the three-axis asphalt 3D printer can be used to measure the parameters of R-3DPA, and the printing accuracy and scale meet the requirements. The recommended parameters for R-3DPA are an extrusion nozzle diameter of 2 mm, a printing temperature of 180 °C, a printing speed of 20 mm/s, a printing strip width of 2.25 mm and a printing layer thickness of 0.4 mm, resulting in structures with good integrity and precision.