Roughness Factor Research Articles

The Direct Cause of Amplified Wettability: Roughness or Surface Chemistry?

Higher contact angles or amplified wettability observed on surfaces of rough solid materials are typically expressed as a function of a physical dimension (roughness factor). Herein, we present a simple experimental approach that demonstrates that roughness may only magnify the inherent surface chemistry that seems to have direct influence on surface wettability. We investigate gradual change in surface chemistry (hydrophobisation) of rough and smooth glass surfaces, from a very low concentration (10−7 M) of dichlorodimethylsilane, DCDMS through various intermediate hydrophilic/hydrophobic states to when the surfaces are maximally hydrophobised with DCDMS at 0.1 M. The wettability of the modified glasses was studied by water contact angle measurements using drop shape analysis system (DSA). The data obtained indicate a deviation from Wenzel model, with the functionalized rough glass surfaces showing higher reactivity towards DCDMS when compared to the smooth glass surfaces, indicating that the two surfaces are not chemically identical. Our study reveals that just like transforming a solid material to powder, a well-divided glass (rough) surface may not only exhibit a greater surface area than the smooth counterpart as rightly predicted by the Wenzel model, but seems to be bloated with functional groups (–OH or –CH3) that can amplify surface interaction when such functional species dominate the solid surface.

Pile-soil interface characteristics in ice-poor frozen ground under varying exposure temperature

This study investigated the shear strength behavior of frozen sand and steel-frozen sand interface using the direct shear testing technique for evaluating the roughness factor “m” that correlates the adhesion of the pile-frozen soil interface with the cohesion of the frozen soil. The study also assessed the ratio between the internal friction of the frozen sand and the interface friction of the steel-frozen sand element in an attempt of defining a frictional factor analogous to the roughness factor. The test results showed that the strength and deformation at peak for all test samples increase with decreasing exposure temperature and increasing the normal stress and strain rate. The residual strength of frozen sand was dependent on temperature and normal stress, while for steel-frozen sand interface was dependent on normal stress only. The peak and residual strength of frozen sand and the peak strength of steel-frozen sand interface were resultant of cohesion/adhesion and internal/interface friction. The residual strength of steel-frozen sand interface was mainly due to the residual interface friction. The roughness factor “m” was found to decrease with decreasing the temperature recording a value of 0.68 at −10 °C and 0.82 at −1 °C. The roughness factor at the residual state was very minimal recording 0.04 indicating very low adhesion strength. A frictional factor was successfully defined and recorded a value of 0.76 which was insensitive of the freezing temperature. At the residual state, the frictional factor was 0.34 indicating a frictional dependency of the residual strength of the steel interface. The study also reports a measurement of thermally induced confining pressure around a model steel pile in frozen sand which is considered the first of its kind. This measurement along with the introduced frictional factor is expected to provide a cost-effective design of pile foundations in frozen ice-poor soils.

Rice-husk fiber reinforced composite (RFRC) drilling parameters optimization using RSM based desirability function approach

This study conducts with the drilling process optimization of rice husk fiber-reinforced polymer composite (RFRC) using the response surface method (RSM)-based desirability function approach. There were four important input factors used for the milling process performance analysis: screw speed, feed rate, type of resin, and drill bit. The results showed that spindle speed and resin type are highly influential parameters on surface roughness, however, the tool and resin type are enormously affecting on delamination. Likewise, the Kevlar drill provided better effectiveness in this cutting process. The variance analysis (ANOVA) indicates that the experimental data is well correlated achieving a 95% confidence interval. Furthermore, this technique determined the significance level according to its factors and their combinations. Hence, the optimized results showed the polyester resin composite plus rice husk, by means of the desirability of 0.678, is the best combination. The results of roughness, input, and output delamination factors were 1.167 μm, 1.3175, and 1.5348, respectively. Finally, it can be seen how the tool thrust force is the main cause of delamination by using the Scanning Electron Microscope (SEM). Additionally, a clean-cut was presented not only by the polyester matrix fiber fragility but also by the superior machinability.

Design and characterization of keratin/PVA-PLA nanofibers containing hybrids of nanofibrillated chitosan/ZnO nanoparticles

In this paper, designing electrospun composite nanofibers containing poly (lactic acid) (PLA) and keratin/poly (vinyl alcohol) (K/PVA) as the major components and natural nanofibrillated chitosan (CHNF)/ZnO nanoparticles (ZnONPs) (CSZ) combination as the nanofiller ingredient, has been investigated. PLA solution from one syringe and K/PVA from another one with incorporation of CHNF (CS), CSZ (2:1), (1:1) and (1:2) were electrospun and produced nanofibers were formed on the rotating collector. Addition of CHNF and ZnONPs amounts in CSZ combination resulted in reduction of the diameter of nanofibers. The highest hydrophilicity was reported for K/PVA/CS-PLA/CS sample with the contact angle of about 43 ± 3°. AFM results for K/PVA-PLA, K/PVA/CS-PLA/CS and K/PVA/CSZ(2:1)-PLA/CSZ(2:1), K/PVA/CSZ(1:2)-PLA/CSZ(1:2) samples indicated that the surface roughness factor for these nanofibers was about 708, 277, 378 and 658 nm, respectively. DSC analysis for K/PVA/CSZ(1:2)-PLA/CSZ(1:2) structure exhibited that the peaks related to the melting points of PLA and PVA shifted to higher temperatures. Overally, K/PVA/CSZ(2:1)-PLA/CSZ(2:1) nanofiber with diameter of 352.50 ± 31 nm, contact angle of 48 ± 3°, tensile strength of 0.96 ± 0.18 MPa is suggested as a proper wound healing scaffold that has highest antibacterial as well as potential to increase cell proliferation.

Improved Li4Ti5O12 electrodes by modified current collector surface

A copper current collector is treated by electrolytic deposition of copper dendrites at the surface of the foil. This treatment results in a more structured surface leading to an improved contact between the electrode materials and the current collector. The contact to the electrode material particles of different sizes is investigated. Active materials of submicron size exhibit a drastically reduced internal resistance and a clearly improved C-rate capability. BET surface area measurement and calculation of roughness factor resulted in the finding of dendritic copper foil to provide an 8-fold larger surface area compared to the untreated foil. A comprehensive electrochemical impedance spectroscopy study is conducted for elucidation of electrochemical utilisation of the surface area increase. As a result, both fitting parameters for capacitance and surface resistance correspond to a similar normalization shift, indicating a clear improvement in the electro-active interface area.

Comparative study of boron-doped diamond, basal-plane pyrolytic graphite, and graphite flake paste electrodes for the voltammetric determination of rivaroxaban and dabigatran etexilate in pharmaceuticals and urine samples

As anticoagulants, rivaroxaban (RIV) and dabigatran etexilate (DAB) are high-risk drugs that can cause life-threatening bleeding. They are a group of drugs that require optimal dosing, therefore their monitoring in the patient is of great importance, especially in emergencies. In this study, we developed a rapid, sensitive square-wave voltammetric (SWV) method by using boron-doped diamond, graphite flake paste, and basal-plane pyrolytic graphite electrodes (BDDE, GFPE, and BPPGE, respectively) to determine the presence of anticoagulants, namely, RIV and DAB in pharmaceutical and urine samples. The supporting electrolyte composition and SWV parameters were investigated. The sensitivity, stability, recovery, calibration curve, and limit of detection (LOD) of the developed method were evaluated. Under the optimal experimental condition, a wider linear response was achieved using BDDE in the detection of both RIV and DAB. The calibration curve for RIV was in the range of 0.5–30.0 μmol L−1 for BDDE and 1.0–10.0 μmol L−1 for GFPE. The calibration curve for DAB was in the range of 0.01–0.7 μmol L−1 for BDDE and 0.07–1.0 μmol L−1 for BPPGE, which shows a linear relationship between the concentration of DAB and the anodic current. LOD was equal to 0.145 μmol L−1 (for RIV at BDDE), 0.297 μmol L−1 (for RIV at GFPE), 2.78 nmol L−1 (for DAB at BDDE), and 16.7 nmol L−1 (for DAB at BPPGE). Finally, BDDE, GFPE, and BPPGE were applied to detect the presence of RIV and DAB in pharmaceuticals and spiked urine samples with satisfactory results (98.2–100.5% for RIV and 99.22–102.8% for DAB). Cyclic voltammetry (CV) was applied to understand the electrode mechanism of RIV and DAB oxidation. The character of RIV and DAB signals was irreversible and diffusion-controlled. In addition, the roughness factor (RF) of BDDE, GFPE, and BPPGE was investigated, which were equal to 0.367, 0.558, and 0.422, respectively.

Development of Virtual Laboratory for the Study of Centrifugal Pump Cavitation and Performance in a Pipeline Network

The conventional method of conducting laboratory experiments in engineering becomes a serious challenge asa result of the COVID-19 pandemic; the development of a virtual laboratory is considered a suitable substitute to real laboratory. In this work, a virtual laboratory for a family of centrifugal pumps has been developed. Cavitation development within the centrifugal pumps and the pumps performances in pipeline networks were studied. Negative potential head and high fluid temperature increased early cavitation incidence, while low fluid temperature, as well as positive potential head reduced it. The choice of pipe diameter and its roughness factor played significant roles in the pumps’ performance. The study shows that virtual laboratory represents a good training environment that enables precise pipeline and pump flow matching.

Modelling the Diffusion Coefficients of Dilute Gaseous Solutes in Hydrocarbon Liquids

In this work, we present a model, based on rough hard-sphere theory, for the tracer diffusion coefficients of gaseous solutes in non-polar liquids. This work extends an earlier model developed specifically for carbon dioxide in hydrocarbon liquids and establishes a general correlation for gaseous solutes in non-polar liquids. The solutes considered were light hydrocarbons, carbon dioxide, nitrogen and argon, while the solvents were all hydrocarbon liquids. Application of the model requires knowledge of the temperature-dependent molar core volumes of the solute and solvent, which can be determined from pure-component viscosity data, and a temperature-independent roughness factor which can be determined from a single diffusion coefficient measurement in the system of interest. The new model was found to correlate the experimental data with an average absolute relative deviation of 2.7 %. The model also successfully represents computer-simulation data for tracer diffusion coefficients of hard-sphere mixtures and reduces to the expected form for self-diffusion when the solute and solvent become identical.

MEASUREMENT OF SURFACE QUALITY AND OPTIMIZATION OF CUTTING PARAMETERS IN SLOT MILLING OF GFRP COMPOSITE MATERIALS WITH DIFFERENT FIBER RATIOS PRODUCED BY PULTRUSION METHOD

The final shape of fiber-reinforced polymer (FRP) materials is usually given by machining. However, machining FRP materials is complex and difficult. Appropriate cutting tools and cutting parameters should be determined to overcome these difficulties. In this work, glass fiber-reinforced polymer (GFRP) materials with 60% and 68% fiber ratio, produced by pultrusion method, were machined. End of the milling, surface roughness (Ra), delamination damage factor (Fdd), sound and vibration results were analyzed. Experiments were carried out with Taguchi L[Formula: see text] mixed design and the results were analyzed by Taguchi, ANOVA and Pareto charts. In Taguchi and Pareto analyses, the most effective parameter for surface roughness and delamination damage factor was the feed rate, and the cutting velocity for sound and vibration. Different regression models have been tried. Linear regression was found as most suitable. The significance values of the regression models are 92.04% for surface roughness, 87.12% for delamination damage factor, 98.64% for sound and 73.27% for vibration.

Effect of the threaded nozzle on delamination and surface texture of PEEK CF30 composite machined by abrasive jet

Purpose The purpose of this study is to bring out the machining characteristics of abrasive jet machining on carbon fibre reinforced thermoplastic composites utilized in aerospace and biomedical applications. Biocompatibility materials such as carbon fibres and polyether thermoplastics, like polyether ether ketone (PEEK) are widely used in trauma and orthopaedic surgery. Due to the heterogeneity, layered construction of reinforcing phase bonds with a resin matrix and abrasiveness of the reinforcing fibre, traditional drilling of carbon fibre-reinforced composites (CFRPs) are always challenging task. Design/methodology/approach An investigation is carried out using abrasive jet machine for drilling PEEK filled with 30 Wt.% carbon fibre (CF 30) using threaded and unthreaded nozzle to study the effect of abrasive jet process variables on surface roughness (Ra) and delamination factor (DF). Pressure (P) and stand-off distance (SOD) as important technological abrasive jet factors were evaluated. It is found that higher abrasive jet pressure and minimum SOD maybe selected to achieve minimum delamination. Findings The study further reported that the threaded nozzle minimized the surface roughness by 43% and delamination factor up to 12%. Originality/value This study of experimenting and observing the machining characteristics of CF30 by using a threaded nozzle is being tried for the first time and the results are deliberated.

Femtosecond Laser Engraving of Deep Patterns in Steel and Sapphire.

Femtosecond laser engraving offers appealing advantages compared to regular laser engraving such as higher precision and versatility. In particular, the inscription of deep patterns exhibits an increasing interest in industry. In this work, an optimization protocol based on constraining overlap ratio and scan number is demonstrated. The proposed method allows changing overlap ratio while maintaining depth in the same range, which reduces the sampling number. This study WAS applied to stainless steel 316 L and sapphire for engravings deeper than 100 m. Results exhibit overall depths higher than threshold values and allowed to determine optimized engraving quality, for instance, roughness in steel can be reduced while maintaining depth and taper angle by reducing overlap ratio. The optimized laser parameters such as roughness and taper angle factors for sapphire were also found to be as follows: 200 kHz, 86% overlap and 12 J/cm. As a demonstration, a logo engraving is illustrated at the end.

Development of Bio‐inspired Composite Materials for the Detection of Traces of Silver Present in Water: Use of Taguchi Methodology to Design Low‐cost Carbon Paste Electrodes

AbstractCarbon Paste Electrodes (CPE) modified with Grapefruit‐Peels (GP) functionalized with Urea (GPU) and, Melamine (GPM) were designed for the detection of Ag+ in water. Taguchi L9 methodology was used to determine the optimal graphite‐Active material ratio. The best electrochemical response was for CPE‐GPU with an 80 : 20 ratio. The results obtained showed a linear detection range between 0.5 to 28 μg L−1, with a detection limit of 0.73 μg L−1 and a limit of quantification of 1.04 μg L−1. Attributable to CPE‐GPU characteristics: electroactive surface area 0.175 cm2, roughness factor 3.87, resistance 0.09 Ω and, mostly −NH2 groups on its surface. The composite material offers a viable option to be used for the determination of silver traces in situ in industrial processes.

Azithromycin electrochemical detection using a VO2 thin film

Vanadium dioxide (VO2) films were successfully synthesized by hydrothermal treatment and used as a sensing material for the detection of azithromycin (AZI) antibiotics. The VO2 thin film was characterized by electrochemical studies at different scan rates, pH values, and AZI concentrations. The roughness factor results demonstrated that the electrode surface has a large active surface area per unit and elevated active sites influenced by the high porosity of the sensing material on the electrode. The VO2 thin film was investigated as a sensing material in the pH range of 5–8 and presented sensitivities of 61.5 and 60.0 mV pH–1 for cyclic voltammetry (CV) and square-wave voltammetry (SWV) studies, respectively, demonstrating high sensitivity and stability for AZI determination. Under different concentrations of AZI (from 1.0 to 80 μmol L−1), the LOD and LOQ values were 0.02 and 0.06 µmol L–1, respectively, for CV and 0.025 and 0.084 µmol L–1, respectively, for SWV. The excellent sensitivity and facile operation of this sensor give it the potential to serve as an alternative method for the analysis of pharmaceutical products and aquatic environments.

Electrocatalytic performance of NiNH2BDC MOF based composites with rGO for methanol oxidation reaction

Present work comprehensively investigated the electrochemical response of Nickel-2 Aminoterephthalic acid Metal–Organic Framework (NiNH2BDC) and its reduced graphitic carbon (rGO) based hybrids for methanol (CH3OH) oxidation reaction (MOR) in an alkaline environment. In a thorough analysis of a solvothermally synthesized Metal–Organic Frameworks (MOFs) and its reduced graphitic carbon-based hybrids, functional groups detection was performed by FTIR, the morphological study by SEM, crystal structure analysis via XRD, and elemental analysis through XPS while electrochemical testing was accomplished by Chronoamperometry (CA), Cyclic Voltametric method (CV), Electrochemically Active Surface Area (EASA), Tafel slope (b), Electron Impedance Spectroscopy (EIS), Mass Activity, and roughness factor. Among all the fabricated composites, NiNH2BDC MOF/5 wt% rGO hybrid by possessing an auspicious current density (j) of 267.7 mA/cm2 at 0.699 V (vs Hg/HgO), a Tafel slope value of 60.8 mV dec−1, EASA value of 15.7 cm2, and by exhibiting resistance of 13.26 Ω in a 3 M CH3OH/1 M NaOH solution displays grander electrocatalytic activity as compared to state-of-the-art platinum-based electrocatalysts.

Prediction of rock mass quality index in the Q-system by multivariate regression using the most influential parameters

The extensive use of underground spaces is an index of development in countries. Choosing the right supporting system to achieve a safe and stable space is an important issue in tunnel construction. One of the methods used to classify rock masses is the Q-system. The Q-system depends on rock quality designation, joint strength, joint roughness, joint alteration, groundwater, and stress reduction factor, which are not always available. Sometimes it is not possible to access all the parameters of the Q-system due to time and cost. This paper aims to obtain the value of the rock quality index in the Q system using the most important parameters affecting it. Therefore, using the Pearson analysis method and SPSS software, the Q-system's most effective parameters are identified. In this regard, three models were selected to determine Q. The first and second models have three input parameters and one output parameter, and the third model has four input parameters and one output parameter. Using multivariate regression, a relationship to predict the Q-value using the most effective parameters is proposed. For this purpose, 140 experimental data were used, and 34 test data checked the results' accuracy. Determining the Q-value using three or four parameters instead of the six most effective parameters is the novelty of this paper. Comparing the results of the proposed relationship and the actual values obtained from the field measurements show that these results are in good agreement with each other. The results show that the second model with a correlation coefficient of 0.81 for the initial data and 0.8 for the test data and the root mean square error of 2.68 for the initial data and 2.55 for the test data has the best performance.

Femtosecond and picosecond laser fabrication for long-term superhydrophilic metal surfaces

This paper reports the femtosecond (fs) laser and picosecond (ps) laser fabrications to create superhydrophilic surfaces. Subsequently, investigations of the surface morphologies and the surface chemistry using EDS, XRD, and FTIR-spectroscopy are carried out. Due to significant variations in the formation of micro-nano structure and molecular compositions, fs laser and ps laser fabricated surfaces exhibited a noteworthy difference in surface wettability by controlling the laser parameters. It is evident from experimental results that ps laser structured surfaces show efficient superhydrophilic nature (0° contact angle with 300 ± 18 ms spreading time) than the fs laser (0° contact angle with 400 ± 18 ms spreading time) due to higher surface roughness factor and surface energy resulted from laser-induced thermalization. Nevertheless, all fabricated surfaces convert from superhydrophilic to superhydrophobic due to chemisorbed hydroxyl (–OH) and C–C(H) functional group contamination. An eco-friendly zeolite (Na-based ZSM-5) coating is used on such ultrafast laser fabricated surfaces to maintain the superhydrophilic property for more than 14 months. The proposed investigation provides an innovative approach for producing long-term stable superhydrophilic metal surfaces, which are useful for water treatment, microfluidics, and heat transfer applications.

PVDF Composite Membranes with Hydrophobically-Capped CuONPs for Direct-Contact Membrane Distillation.

Water scarcity is an imminent problem that humanity is beginning to attempt to solve. Among the several technologies that have been developed to mitigate water scarcity, membrane distillation is of particular note. In the present work, CuO nanoparticles capped with 1-octanethiol (CuONPs@CH) or 1H,1H,2H,2H-perfluorodecanethiol (CuONPs@CF) are prepared. The nanoparticles are characterized by FT-IR and TGA methods. Two weight losses are observed in both cases, with the decomposition of the organic fragments beginning at 158 °C and 230 °C for CuONPs@CF and CuONPs@CH, respectively. Flat sheet PVDF composite membranes containing nanoparticles are prepared by the casting solution method using nanoparticle concentrations that ranged between 2–20% with a non-woven polyester fabric as support. The obtained membranes showed a thickness of 240 ± 40 μm. According to water contact angle (87° for CuONPs@CH and 95° for CuONPs@CF, both at 10% w.t) and roughness (12 pixel for CuONPs@CH and 14 pixels for CuONPs@CF, both at 10% w.t) determinations, the hydrophobicity of membranes changed due to a decrease in surface energy, while, for naked CuONPs, the roughness factor represents the main role. Membranes prepared with capped nanoparticles showed similar porosity (60–64%). SEM micrographs show asymmetric porous membranes with a 200-nm surface pore diameter. The largest finger-like pores in the membranes prepared with CuONPs, CuONPs@CH and CuONPs@CF had values of 63 ± 10 μm, 32 ± 8 μm, and 45 ± 10 μm, respectively. These membranes were submitted to a direct contact membrane distillation module and flux values of 1.8, 2.7, and 3.9 kg(m2·h)−1 at ΔT = 30 °C were obtained for the CuONPs, CuONPs@CH, and CuONPs@CF, respectively. The membranes showed 100% salt rejection during the testing time (240 min).

Contribution of Superhydrophobic Surfaces and Polymer Additives to Drag Reduction

AbstractDrag reduction has constantly received great attention due to its extensive range of applications in fluid transportation and vehicle industries. The vital role of two different additive and non‐additive techniques (polymer additives and superhydrophobic surfaces) to reduce the drag force experienced by underwater vehicles, fluid flow through pipes, ducts, open or closed channels, and other wall‐bounded laminar and turbulent flows is highlighted. Reducing the drag resistance can significantly enhance the performance of immersed vehicles and results in saving the energy consumed on a large scale. The progress in theoretical modeling, experimental and computational studies of both techniques are reviewed, together with the surface design, wettability, and influence of the roughness factor of superhydrophobic surfaces and the effect of polymer drag‐reducing agents for wall‐bounded flows and multiphase flows. General formulations, potential applications, and major issues involved in the aforementioned approaches are summarized.

Effect of Climate Changes and Coefficient of Surface Roughness on Soil Loss by Wind Erosion in Some Central and Southern Iraq

"act Woodruff and siddoway, 1965, established an equation for the estimation of soil Loss by wind erosion called Wind Erosion Equation (WEQ); solution of this equation gives the maximum amount of wind erosion under certain field conditions and is considered evidence in identifying the necessary methods for treating wind erosion in those conditions (Eltaif et al.,1991). This study aims to find out the extent to which climate change in the Samawah region of southern Iraq and Baghdad in central Iraq over a period of 34 years has affected values of soil losing by wind erosion using equation of (woodruff and siddoway, 1965) and effectiveness of this changes in soil surface roughness factor in reducing or increasing these loss. Two sites were selected located within central and southern regions of Iraq, one in Al-Jadiriya area in Baghdad governorate and the other in Samawah area in Al-Muthanna governorate. The results showed that estimated soil losing for years (1980-2013) in Al-Jadiriya decrease annually by 10-30 kg.hec.-1.year-1, while samawah increase by 240-760 kg.hec.-1.year-1. The effect of surface roughness factor was significant in reducing soil loss during period of study. Roughness factor for ridge (0.5) has reduced soil losing by 2.6 times compared to non-ridge soils (1).The ratio in semi-bridge soil (0.75) was 65%. This is due to the impact of bridge in reducing wind speed and reducing its erosivity. The general direction of soil loss indicates decrease in Al-Jadiriya area and increase in Samawah area with the case of fluctuation in soil loss between high and low of general direction line due to climate factor (C) in general equation of soil loss and it reflects ability of wind erosion, so decreased when wet conditions improved, by increased rainfall, reduced evaporation and increasing when dry conditions dominate Corresponding author: E-mail( mohammed.alrawi@coagri.uobaghdad.edu.iq ) All rights reserved AlMuthanna University"

(Invited) ORR in Ca2+ Containing DMSO on Pt and Au Electrodes – Reaction Mechanism Studied By Dems, AFM and XPS and Varied Surface Structure

Though Ca-O2 batteries show rising interest in the battery society due to their attractive energy density and availability of materials, the fundamental mechanisms of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in aprotic electrolytes are scarcely understood. This and preceding studies[1-3] aim at the investigation of the ORR mechanism especially on well-defined electrodes (single crystalline surfaces or those with adjusted roughness). Here we investigated the ORR in 0.1 M Ca(ClO4)2 in DMSO, as under convection for this system no deactivation is observed on Au and Pt electrodes. From earlier results[3, 4] we know, that on Au electrodes a slowly dissolving peroxide is formed, until a closed CaO2/CaO adsorbate layer is built up in a competing process, which inhibits further peroxide formation. The layer was characterized by XPS and AFM. An astonishing finding is that on Au electrodes of electrode roughness factor (fR) > 10 under convection, formation of superoxide is a diffusion limited process on top of the CaO2/CaO adsorbate layer (although peroxide formation is inhibited). In this study we also investigate the ORR/OER mechanism in the same system on Pt electrodes and compare the results to those, which we obtained from experiments on Au electrodes, as we found predominant superoxide formation on Pt electrodes in earlier studies[1]. This study shows, that also on Pt electrodes a CaO2/CaO adsorbate layer is the reason for predominant superoxide formation under convection. We found, that as one increases the electrode roughness, the ORR becomes more and more dominated by formation of adsorbed peroxide. Thus for low electrode roughness, we have to conclude that the in fact diffusion limited superoxide formation occurs through a CaO2/CaO adsorbate layer, which also on Pt electrodes inhibits further peroxide formation. As peroxide formation leads to almost complete electrode blocking in other M-O2 battery systems further leading to surface limited charges, one might think of utilizing the selective process inhibiting nature of the CaO2/CaO adsorbate layer to tackle those problems. Thus, in this study we will further show the influence of a CaO2/CaO adsorbate layer on Pt electrodes to the ORR in Li+ containing DMSO, as it is known, that Li2O2 effectively blocks the electrode.[1] P. Reinsberg, C. J. Bondue, H. Baltruschat, Journal of Physical Chemistry C 2016, 120, 22179.[2] P. Reinsberg, A. A. Abd-El-Latif, H. Baltruschat, Electrochimica Acta 2018, 273, 424.[3] P. P. Bawol, P. H. Reinsberg, A. Koellisch-Mirbach, C. J. Bondue, H. Baltruschat, ChemRxiv (Preprint) 2020.[4] A. Koellisch-Mirbach, I. Park, H. Baltruschat*, In preparation.