Surface Roughness Research Articles

Comparative evaluation of surface changes and bond strength of microabrasion bleached enamel before and after remineralization with nano-hydroxyapatite paste: In vitro study

Objectives: Comparative evaluation of surface changes and bond strength of Microabrasion Bleached enamel before and after Remineralization with Nano-hydroxyapatite paste, an In vitro study. Methods: Enamel samples were divided into - Group I - Conventional bleaching (HB), Group II - Conventional bleaching with remineralization (HB+N-Hp), Group III - Microabrasion-assisted bleaching (M+HB), and Group IV - Microabrasion-assisted bleaching with remineralization (M+HB+N Hp). Surface roughness was measured using a profilometer. Samples were stored in artificial saliva for two weeks, then bonded with nanofilled composite resin and subjected to shear bond strength (SBS) analysis. Results: Group IV (M+HB+N-Hp) showed higher surface roughness than Groups I (HB) and II (HB+N-Hp), while Group II had significantly lower surface roughness compared to Groups III (M+HB) and IV. In terms of shear bond strength (SBS), Group III exhibited significantly higher SBS than Group I, whereas Group II showed significantly reduced SBS compared to Group I. All values were statistically significant. Conclusions: Remineralization with N-Hp reduces the surface roughness caused by bleaching and microabrasion, potentially decreasing bacterial biofilm adherence. Despite increased surface roughness correlating with better bond strength, microabrasion-assisted bleaching followed by remineralization and direct composite veneering after two weeks is a promising minimally invasive treatment for severe tooth discolorations. Further studies should explore varying frequencies and concentrations of N-Hp application.

Analysis of FS and Surface Roughness in Heat-Polymerized Poly Methyl Methacrylate Acrylic Resin Reinforced with Different Concentrations of Glass Fibers and Polypropylene Fibers: A Laboratory Study Using EDX and SEM

This study aimed to evaluate the flexural strength (FS) and surface roughness (Ra) of heat-polymerized poly methyl methacrylate (PMMA) acrylic resin reinforced with glass fibers (GF) and polypropylene fibers (PPF) in different concentrations. One hundred heat-cured PMMA resin samples were prepared and randomly allocated into five groups based on fiber reinforcement (n = 20). Group 1 had no fiber reinforcement, Group 2 had 0.5% silanized GF reinforcement, Group 3 had 1% silanized GF reinforcement, Group 4 had 0.5% silanized PPF reinforcement, and Group 5 had 1% silanized PPF reinforcement. Fatigue load was applied through artificial aging. FS testing of fifty samples was performed using a universal testing machine, and Ra was analyzed using an optical interferometric profilometer. Specimens were selected for SEM and EDX analysis. To find the differences among the studied groups, one-way analysis of variance and post hoc Tukey’s test were utilized. The results showed that Group 5 (1% PPF reinforcement) presented the highest fracture resistance (90.1±9.8 MPa), while the minimum FS scores were observed in Group 1 (no reinforcement) (59.2±7.1 MPa). Group 3 (1% GF reinforcement) exhibited the highest values of surface roughness (1.99±0.1992), whereas the lowest roughness scores were observed in Group 1. The study concluded that incorporating 0.5% PPF into the resin denture is a viable option for reinforcing the prosthesis without increasing surface roughness.

Experimental study on shear transfer across interfaces with post-installed shear reinforcement

To address the fit-up issues arising from reinforcement congestion and limited seating area over precast beams, an improved joint detail characterized by post-installed interface shear reinforcement has been developed. The incorporation of post-installed narrower looped bars as an alternative to conventional protruding stirrups significantly expedites the erection of precast flooring systems. Moreover, direct shear tests are performed on 30 Z-shaped specimens to investigate the influence of joint details, surface roughness, looped bar ratio, and embedment length of post-installed bars on the interface shear behavior. Experimental results indicate that employing post-installed narrower looped bars not only ensures adequate seating length for precast flooring systems, but also prevents the splitting failure of concrete cover which can induce the degradation of dowel action. Sufficient anchorage is the prerequisite for post-installed looped bars to impose clamping stress on concrete interface, and a shallow embedment length may trigger the occurrence of pull-out failure. Surface roughness is another factor determining the interface shear resistance and stiffness. Untreated surfaces, in contrast to intentionally roughened surfaces, are susceptible to the cohesion fracture and may hinder the development of shear-friction action. Furthermore, a linear correlation exists between looped bar ratio and the shear resistance of concrete interface. Based on the experimental results, design recommendations, including the minimum required anchorage length for post-installed looped bars, are proposed for the novel joint detail.

Characterization of thin oxide layers formed by Ti-Nb Alloy anodization

Ti-Nb alloys are gaining more prominence in the industrial and scientific environment due to their high biocompatibility, mechanical strength/weight ratio, and exceptional corrosion resistance compared to other metallic materials. Metals exhibiting this passivation characteristic are known as metal valves and may exhibit semiconductive or insulating oxides. Controlling the growth of distinct thickness layer films is possible through tunning anodization conditions. In this work, a Ti-Nb binary system is anodized, and the grown oxide layer is comprehensively characterized using ellipsometry based on its optical properties and thickness at different applied potentials. Confocal Microscopy assessed their surface roughness, and SEM/EDS probed the surface material's elemental composition. CF-LIBS successfully confirmed the 70/30 composition of the Ti-Nb alloy. Raman spectra have detected the presence of amorphous TiO2 and Nb2O5 at potentials higher than 80V, 100V, and 120V. Finally, a linear dependence of the oxide thickness with the applied potential was observed.

Maintenance of dental bleaching: A systematic review

After bleaching procedure, color pigments can adhere to the rough dental surface and can trigger more discoloration. In this sense, no standard post-bleaching maintenance technique exists. The purpose of this study was to evaluate the maintenance of enamel color after bleaching procedure through a systematic review. The research question was defined as follows: Is the tooth whitening maintenance necessary after a bleaching treatment? Two reviewers conducted the literature search in PubMed (MEDLINE), Web of Science, Scopus, EMBASE, and SciELO. Both in vitro and clinical trials reporting the color change of bleached enamel after the use of a tooth whitening agent were included in the review. The risk of bias in the included manuscripts was evaluated using the RoBDEMAT tool. A total of 11 articles were included in the qualitative analysis. Due to the lack of groups for comparison, a meta-analysis could not be conducted. The whitening maintenance procedures identified were remineralizing agents, antioxidants, over-the-counter agents, toothpaste containing Blue Covarine, casein phosphopeptide-amorphous calcium phosphate fluoride paste, 0.05% sodium fluoride mouthwash, arginine, nano-hydroxyapatite, nano-carbonate apatite, and CO2 laser. In conclusion, tooth whitening maintenance could be achieved by using some agents. The association of these agents might be beneficial for maintaining the color of the enamel throughout 12 months following bleaching procedure.

Dendritic copper nanostructures for ultrasensitive detection of rhodamine 6G and Congo red

Surface-Enhanced Raman Scattering (SERS) is a fast-responding and non-destructive ultra-sensitive detection technique that can replace traditional chromatographic and spectroscopic analysis techniques. In this experiment, dendritic copper nanostructures were prepared by the solid-state ionics method and the vacuum hot evaporation process with an applied current of I=9μA. Using them as a SERS substrate, Raman detection was performed on the dye molecules Rhodamine 6G (R6G) and Congo Red (CR) to determine SERS enhancement performance. It is found that the growth of the prepared copper nanostructures has a top-end dominant phenomenon. The fractal dimension of the copper nanostructure was calculated using fractal theory, and it was revealed to be 1.560. Scanning electron microscopy (SEM) results showed that a large number of 60-80 nm regularly arranged copper nanoparticles were attached to the surface of the dendritic copper nanostructure. This is beneficial to increase the surface roughness of the substrate and improve the detection level of dye molecules. Subsequently, copper nanostructures can sensitively detect R6G and CR solutions as low as 1×10-13 mol/L and 1×10-7 mol/L, reaching single-molecule levels. The Raman mapping experiment showed that the mean relative standard deviation (RSD) values of R6G and CR were 12.3% and 12.9%, indicating high uniformity and reproducibility of the structure. This structure effectively achieves the fusion of uniformity, repeatability, and sensitivity, and shows broad application prospects in food detection.

Investigation of the Effects of Different Phases of TiO2 Nanoparticles on PVA Membranes

Introduction: PVA/TiO2 nanocomposite membranes are prepared by solution casting technique where different phases of TiO2 nanoparticles like brookite, brookiterutile and rutile are dispersed in PVA matrix. Sol-gel method was employed to prepare TiO2 nanoparticles, while different phases of TiO2 have been obtained by controlling the calcination temperature. Methods: PVA/TiO2 nanocomposite membranes were characterized by XRD, FTIR, AFM, TEM, UV-visible and PL techniques. XRD results confirmed the presence of different phases of TiO2, exhibiting 3.3 nm, 8.4 nm, and 35.7 nm mean crystalline size. The XRD studies also confirmed that TiO2 nanoparticles became properly dispersed to the PVA matrix, leading to increased PVA crystallinity after doping of different phases of TiO2 nanoparticles. UV-visible analysis revealed an increase in absorption intensity and peak position shifts slightly towards longer wavelengths, which indicates that nanofillers tuned the band gap of PVA. The doping of the TiO2 (brookite) phase in the PVA matrix results in a decreased in PL intensity. Results: This suggests that the PVA/TiO2 (brookite) membrane exhibits a greater degree of photocatalytic activity in comparison to the other two composites. According to the FTIR investigation, the hydroxyl (OH) groups present in PVA interact with the dopants Ti+ ions via intra- and intermolecular hydrogen bonds to produce charge transfer complexes (CTC). The AFM study shows surface roughness details for PVA and PVA/TiO2 composite membranes. The average grain size of TiO2 nanoparticles calculated from TEM images is in good agreement with the grain size calculated by XRD. Conclusion: By adjusting the phase of TiO2 nanoparticles into PVA matrix, composites can be developed that are optimized for a variety of applications such as water purification, UV protection, self-cleaning surfaces, lithium-ion batteries, and optoelectronic devices.

Multiscale evaluation of sand-geomaterial interface shear response in terms of material geometry effects

This study evaluates the effects of particle and surface geometric features on the interface shear behavior of sand-geomaterial. Particle shape and size were adjusted for the sand, and surface roughness form and height were set for the geomaterial part. 3D printing technology was used to produce geomaterials in the desired form. A custom-made transparent interface shear box was developed to perform digital image processing. For macroscale response, peak and residual strengths and dilation angle were measured. Sliding percentage and shear band thickness were determined from digital image correlation analyses for the mesoscale response. The experimental results showed that the macroscale response parameters increased as the overall regularity of the sand particles decreased. The increase in mean particle size and roughness height led to an increase in macroscale parameters. Digital image correlation analyses showed that the sliding percentage had an inverse correlation with the shear band thickness in terms of the particle shape and the roughness height effects. The roughness form controlled the trend of mean particle size effects on the sliding percentage. Overall, the mesoscale parameters revealed the traces of interlocking response, particle kinematics, and the failure mechanism in the interface region. Thus, a bridge was established between meso- and macro-scale responses.

Superhydrophobic poly(lactic acid) membrane prepared with the induction of modified carbon dots for efficient separation of water-in-oil emulsions

Superhydrophobic separation membranes are considered to be one of the most promising technologies for oil-water separation. However, the plastic waste generated from discarded membranes poses a challenge to the preparation of degraded superhydrophobic separation membranes for achieving eco-friendly separation. In this study, superhydrophobic poly(lactic acid) (PLA) membranes were fabricated using a non-solvent induced phase separation method assisted by l-cysteine modified carbon dots (Cys-CDs). The synergistic effect of Cys-CDs-induced crystallization behavior of PLA and the phase separation process results in the evolution of the surface of the PLA-based membrane from a pistil-like structure to a multi-level micro-nano structure composed of dense lamellar nanofibers and microspheres with an increase in Cys-CDs content. At a Cys-CDs content of 5 wt%, the surface roughness of PLA-based separation membrane reached its maximum, and the water contact angle was as high as 159°. Remarkably, the superhydrophobic Cys-CDs/PLA membrane exhibited promising performance in the separation of water-in-oil emulsions, with a rejection rate of 99.98 % and a flux of 315.74 L·m−2·h−1·bar−1. Additionally, the superhydrophobic Cys-CDs/PLA separation membrane also demonstrates impressive properties such as acid-alkali resistance and rapid recycling into high-value chemicals. Consequently, this rapidly recoverable superhydrophobic porous Cys-CDs/PLA membrane shows great potential for practical applications in actual oil-water separation.

Comparative study on machinability and surface integrity of γ-TiAl alloy in laser assisted milling

γ-TiAl alloy, as a typical difficult-to-cut material, is considered to have great potential in aero-engine manufacturing. However, it is difficult to achieve high-quality processing of γ-TiAl alloy using traditional cutting processes, due to the room temperature brittleness and high strength of theγ-TiAl alloy. This study proposes a fiber laser assisted machining (LAM) method to improve the cutting quality of γ-TiAl alloy, which attempts to address current challenges in applications of aero-engine manufacturing. The machinability and surface integrity of γ-TiAl specimens using LAM method and conventional milling are analyzed and discussed. Through cutting force testing, chip morphology research, surface hardness testing, and microstructure observation, it is found that the LAM method significantly improves the machinability and machined surface integrity of γ-TiAl specimens. Furthermore, the cooling strategies in LAM is discussed through comparative cutting experiments. During continuous LAM processing, it is found that the rapid heat accumulation effect induces tool adhesive wear, which leads to the decline of cutting quality and tool failure. The experimental results indicate that liquid cooling is an available strategy to reduce tool wear. However, it should be noted that periodic thermal shock by liquid cooling causes surface roughness to increase in continuous LAM processing. Through this work, it is proved that the LAM method can improve machinability and surface integrity of γ-TiAl specimens, which has great potential and worths further studies.

Direct near-infrared laser ignition of CL-20 by introducing DATNBI as a bi-functional additive: Energetic photosensitizer and self-assembly stimulator

The ignition strategy of energetic materials using low-energy near-infrared (NIR) laser has garnered significant attention due to its enhanced safety and reliability. This study explores the use of a relatively photosensitive but mechanical insensitive energetic material, DATNBI, to facilitate the self-assembly of nano-CL-20 crystals into polycrystalline particles though solvothermal induction, yielding a rough structure conducive to NIR laser ignition. The findings demonstrate that by adjusting the content of DATNBI, it is possible to achieve micro-nano controllable spherical CL-20/DATNBI (C/D) particles, with CL-20 as the primary component and DATNBI as the auxiliary component. The incorporation of DATNBI and the rough surface structure enhance the light absorption of C/D particles in the NIR band. Additionally, the unique synergistic effect between CL-20 and DATNBI during thermal decomposition further promotes NIR laser ignition. As expected, the C/D particles achieved self-sustained combustion and exhibited excellent combustion performance under a 1064 nm laser, which is challenging to be achieved with raw CL-20 or raw DATNBI. Furthermore, the relatively insensitive DATNBI and spherical structure reduced the impact sensitivity of the C/D particles. This multifunctional material strategy, integrating energy, safety environment-friendliness, and laser ignition performance, offers a novel approach for laser ignition of energetic materials.

Modeling and Prediction of Surface Roughness in Ball End Milling of Oxygen-Free High Conductivity Copper Using Adaptive Neuro Fuzzy Inference System

Oxygen Free High Conducting Copper (OFHC) is one of the reasons materials for numerous applications due to its high thermal conductivity, great machinability, and great quality In this paper, an adaptive neuro-fuzzy inference system (ANFIS) is developed as a predicting model of the machining performance of OFHC measured for surface roughness in terms of process parameters, namely, the cutting feed rate or feed per tooth, axial depth of cut, radial depth of cut, and the cutting speed.

Optimal Suppression of Photocatalytic Activity of Hybrid TiO2 Particles in Epoxy Thin Film by Using Taguchi Method

In this study, two different Al2O3-TiO2 and SiO2-TiO2 hybrid TiO2 particles were synthesised by using silica (SiO2) and alumina (Al2O3) to suppress the photocatalysis of TiO2. Key variables such as the concentration of the hybridization material (C), heating temperature (Th), and calcinating temperature (Tc) were selected with performance measured by photodegradation rate. The Taguchi L9 orthogonal array, a systematic approach used in the design of experiments (DOE), confirmed A333 (Al2O3-TiO2) achieved 99% photodegradation suppression with photodegradation rate reduced significantly from 0.01305 min−1 to 0.00009 min−1 and improved yellowing resistance by 63%, while S323 (SiO2-TiO2) achieved 75% suppression with photocatalysis activity decreased from 0.01305 min−1 to 0.0033 min−1 and 42% improved resistance. X-ray Diffraction (XRD) analysis showed A333 had a higher rutile phase (40.1% vs. 10.2% for S323), and Fourier Transform Infra Red (FTIR) and Field Emission Scanning Electron Microscopy (FESEM) analyses revealed A333's rougher surface and lower surface area compared to S323 and pure TiO2. Overall, A333 effectively suppressed photocatalysis and improved yellowing resistance of epoxy thin film. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Remotely Controlled Armed Surveillance Rover

A remotely operated ground vehicle was designed and developed for use in counter terrorism and counter-insurgency operations by the Indian Army. The Rover can traverse difficult terrain, extreme slopes, inspect suspicious objects (e.g. improvised explosive devices) with a robotic weapon with a camera(even when hidden under a bridge), and give visual feedback to an operator away at a safe distance of certain range. It can be operated using mobile and can be self-triggered when a command is given. Militaries are now equipped with various types of rovers. Rover for assistance and spy purposes are developing. This project represents an application of Rover in the military. This rover is 4-wheeled developed on a rocker-bogie mechanism. According torecent Rover developments, rovers with rocker-bogie mechanismscan glide on rough surfaces, sand, and loose soil easily. Thedegree of freedom for the rover is 4 with the ability to rotate 360°.This rover is equipped with frequency hopping which makes it ananti-hack device. This project is useful for attacking the opponentsin the war without losing our army officers. So by using thisproject we can do war without losing human life on our side.

High-speed turning of AISI 4340 alloy steel using carbide tools in a sustainable minimum quantity lubrication environment

Purpose This study aims to investigate the machining performance of CVD-coated carbide tools by considering most crucial machinability aspects: cutting force, tool life, surface roughness and chip morphology in high-speed hard turning of AISI 4340 alloy steel under a sustainable minimum quantity lubrication (MQL) environment. Design/methodology/approach The purpose of this study is to analyze the performance of coated carbide tools under MQL environment therefore, machining tests were performed in accordance with the Taguchi L9 orthogonal array, accommodating the three crucial machining parameters such as cutting speed (V = 300–400 m/min), feed rate (F = 0.1–0.2 mm/rev) and depth of cut (DOC = 0.2–0.4 mm). The measured or calculated values obtained in each experimental run were validated for normality assumptions before drawing any statistical inferences. Taguchi signal-to-noise (S/N) ratio and analysis of variance methodologies were used to examine the effect of machining variables on the performance outcomes. Findings The quantitative analysis revealed that the depth of cut exerted the most significant influence on cutting force, with a contributing rate of 60.72%. Cutting speed was identified as the primary variable affecting the tool life, exhibiting a 47.58% contribution, while feed rate had the most dominating impact on surface roughness, with an overall contributing rate of 89.95%. The lowest cutting force (184.55 N) and the longest tool life (7.10 min) were achieved with low machining parameters at V = 300 m/min, F = 0.1 mm/rev, DOC = 0.2 mm. Conversely, the lowest surface roughness (496 nm) was achieved with high cutting speed, low feed rate and moderate depth of cut at V = 400 m/min, F = 0.1 mm/rev and DOC = 0.3 mm. Moreover, the microscopic examination of the chips revealed a serrated shape formation under all machining conditions. However, the degree of serration increased with an incremental raise with cutting speed and feed rate. Research limitations/implications The study is limited to study the effect of machining parameters within the stated range of cutting speed, feed rate and depth of cut as well as other parameters. Practical implications Practitioners may consider to adopt this machining technique to create more sustainable working environment as well as eliminate the disposal cost of the used metal cutting fluid. Social implications By applying this machining technique, diseases caused by metal cutting fluid to the mechanist will be significantly reduced, therefore creating better lifestyles. Originality/value Hard turning is commonly carried out with advanced cutting tools such as ceramics, cubic boron nitride and polycrystalline cubic boron nitride to attain exceptional surface finish. However, the high cost of these tools necessitates exploration of alternative approaches. Therefore, this study investigates the potential of using cost-effective, multilayer-coated carbide tools under MQL conditions to achieve comparable surface quality. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0013/

Multi-Electrode Extended Gate Field Effect Transistors Based on Laser-Induced Graphene for the Detection of Vitamin C and SARS-CoV-2.

Despite the clinical data showing the importance of ascorbic acid (AA or vitamin C) in managing viral respiratory infections, biosensors for their simultaneous detection are lacking. To address this need, we developed a portable and wireless device for simultaneous detection of AA and SARS-CoV-2 virus by integrating commercial transistors with printed laser-induced graphene (LIG) as the extended gate. We studied the effect of laser printing pass number and showed that with two laser printing passes (2-pass LIG), the sensor sensitivity and limit of detection (LOD) for AA improved by a factor of 1.6 and 12.8, respectively. Using complementary characterization methods, we attribute the improved response to a balanced interplay of crystallinity, defect density, surface area, surface roughness, pore density and diameter, and mechanical integrity/stability. These factors enhance analyte transport, reduce noise/variability, and ensure consistent sensor performance, making 2-pass LIG the most effective material in this work. Our sensors exhibit promising performance for detecting AA with a selective response in the presence of common salivary interfering molecules, with sensitivity and LOD of 73.67 mV/dec and 54.04 nM in 1× phosphate buffered saline and 81.05 mV/dec and 78.34 nM in artificial saliva, respectively. We also showed that functionalization of the 2-pass LIG gate with S-protein antibody enables the detection of SARS-CoV-2 protein antigens with an ultralow LOD of 52 zg/mL─an improvement of more than 10-fold compared to 1-pass LIG─and 4 particles/mL for virion mimics with a selective response against influenza virus and multiple human coronavirus strains. With low signal drift/hysteresis and wireless capabilities, the developed device holds great potential for improving at-home monitoring and clinical decision-making.

The Weathering of the Beech and Spruce Wood Impregnated with Pigmented Linseed Oil

This research aimed to examine the effects of a deep impregnation technique (Royal process) and surface coating using a linseed oil-based product, enhanced with small amounts of brown and grey pigments, on the natural and artificial weathering of wood. The treated and reference samples underwent natural weathering for five years and artificial weathering for 1900 h. Changes in color and surface roughness were assessed during weathering. For the artificially weathered samples, liquid water absorption was measured both before and after exposure. The impregnated and coated samples gradually lost their brown color, turning grey over time. More pronounced differences were observed during natural weathering, with the coated samples showing greater structural changes on the wood surface. In contrast, impregnated samples slowed down structural alterations compared to the reference samples. Both treatments effectively reduced water absorption before weathering, although this effect diminished after exposure. The treatments did not significantly impact the fire resistance of spruce and beechwood.

Effect of various storage media on the physicochemical properties of plasma-treated dental zirconia

This study investigated the effect of various storage media on the physicochemical properties of plasma-treated 3-mol% yttria-stabilized tetragonal zirconia: air, vacuum, deionized water (DIW), and plasma-activated water (PAW). Each group was divided into five subgroups based on storage periods: immediately after NTP irradiation (T0), and after 1 week (T1), 2 weeks (T2), 3 weeks (T3), and 4 weeks (T4). The control group (C) received no treatment. The storage groups were monitored weekly using various analytical techniques, including contact angle measurements, scanning electron microscopy (SEM), focused ion beam (FIB)-SEM, confocal laser scanning microscopy (CLSM), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD). Our results demonstrate that plasma-treated zirconia surfaces stored in DIW retained or even increased their hydrophilicity due to the formation of hydrogen bonds and preservation of nitrogen functionalities. In contrast, surfaces stored in air exhibited significant hydrophobic recovery. FIB-SEM analysis showed no adverse internal structural changes regardless of storage medium. The roughness of the zirconia surface slightly increased after plasma treatment and was generally retained across all storage groups for 4 weeks, except for the air storage group. This study concludes that storage in DIW effectively preserves the enhanced surface properties of plasma-activated zirconia for up to 4 weeks.

Large eddy simulation of near-surface boundary layer dynamics over patchy snow

The near-surface boundary layer over patchy snow is highly heterogeneous and dynamic. Layers of opposing stability coexist within only a few horizontal meters. Conventional experimental methods to investigate this layer suffer from limitations related to the fixed positions of eddy covariance sensors. To overcome these difficulties, we set up a centimeter-resolution large eddy simulation of flow across an idealised transition from bare ground to snow. We force the simulation with high-frequency eddy covariance data recorded during a field campaign. We show that the model can represent the real flow by comparing it to independent eddy covariance data. However, the simulation underestimates vertical wind speed fluctuations, especially at high frequencies. Sensitivity analyses show that this is influenced by grid resolution and surface roughness representation but not much by subgrid-scale parameterization. Nevertheless, the model can reproduce the experimentally observed plumes of warm air intermittently detaching from bare ground and being advected over snow. This process is highly dynamic, with time scales of only a few seconds. We can show that the growth of a stable internal boundary layer adjacent to the snow surface can be approximated by a power law. With low wind speeds, deeper stable layers develop, while strong wind speeds limit the growth. Even close to the surface, the buoyancy fluxes are heterogeneous and driven by terrain variations, which also induce the frequent decoupling of a thin layer adjacent to the snow surface. Our simulations point the path towards generalizing point-based and aerial measurements to three dimensions.

Effect of additives on the microstructure and properties of pulsed electrodeposited copper foils

ABSTRACT A low-roughness ultra-thin copper foil was prepared by pulsed electrodeposition with a duty cycle 60%, pulse frequency of 600 Hz on titanium. The influence of sodium 3,3'-dithiodipropane sulphonate (SPS), hydroxyethyl cellulose (HEC), gelatin and collagen additives on the microstructure, mechanical properties and electrochemical behaviour of electrolytic copper foil was explored. Furthermore, the reaction mechanism of SPS and collagen additives on electrodeposited copper were discussed. The results showed that at 0.08 g L−1 collagen concentration, the lowest thickness, the highest microhardness and the optimal surface roughness were achieved (5.12 μm, 279.63 HV and 1.885 μm, respectively). X-ray diffraction results confirmed that electrolytic copper foils prepared when SPS was introduced into the blank solution had a preferred orientation of (220) texture, which benefitted from the synergistic effect of copper ions and additives. The intermediates formed by the additive and Cu+ occupied the active sites on the cathode surface that increased the nucleation sites for deposition. In addition, the formed complexes can act as a barrier to narrow ion deposition channels and inhibit the growth of Cu ions.