Stainless Steel Discs Research Articles

Water collection through a directional leaf vein pattern by fast laser marker ablation of stainless-steel

Inspired by the natural water harvesting mechanisms of desert beetles, cactus thorns, and leaf veins, we designed a heterogeneous wettability surface with superhydrophilic pattern integrating leaf vein as the directional water transport main channel, attached capillary triangles as auxiliary channel plus a deep rough desorption channel on an overall superhydrophobic surface for an efficient water collection. A superhydrophilic surface was initially fabricated on the stainless steel disc by laser marker ablation allowing 1 μL droplet to spread completely to 0° within 0.12 seconds, followed by fluorine-containing coating transforming superhydrophilic surface to superhydrophobic one. Directional water transport patterns were then etched on the superhydrophobic surfaces by the secondary laser marker. The surface energy gradient and Laplace pressure induced by the pattern facilitated directional fast transport and efficient desorption of droplets, thus improving water collection efficiency. The enhancement mechanism of the water harvesting behavior for such surfaces was analyzed, with one focus on enhancing collection in hydrophobic regions with capillaries to reduce bouncing off loss and the other on improving balanced cycling of the collection process. At a fog flow rate of 1500ml/h and 20cm away from the fog outlet, the directional leaf vein-patterned 19.625cm2 sized surface demonstrated a fog water collection rate (WCR) of 5.6 Kg·m-2·h-1 and first drop collection at the 49th s, an impressively short time rarely reported. Compared to the superhydrophobic, superhydrophilic samples, and the reference, WCR increased by 180%, 62%, and 59%, respectively, and the first droplet collection time decreased by 73%, 46%, and 62%, respectively. This efficient water collection method has huge potential in arid regions.

Dry Sliding Wear Behavior of Cemented Carbide at Elevated Temperatures

The material for a cutting tool needs to be carefully selected to withstand high temperatures during cutting and have good wear performance. The use of cutting tools made from cemented carbide material was studied due to its potential in terms of mechanical properties that are ideal at high temperatures up to 1000 °C and being cheaper than other materials. This investigation of the dry wear of this cutting material focused on temperatures of 25 °C, 200 °C, and 300 °C, with loads of 50 N, 100 N, and 150 N. The weight loss, friction coefficient, and change of the pin microstructure were determined. It was found that the higher the temperature and load applied to the cemented carbide pin, the more the microstructure changed, and the percentage of weight loss increased up to 0.55%. The wear rate on the cemented carbide pins was higher when applied to a stainless steel disc compared to a mild steel disc. The simulation revealed that the von Mises stress on the stainless steel disc was 51.759 Pa, while that on the mild-steel disc was 60.379 Pa. This indicates that both materials did not fail because the von Mises stress was lower than the disc yield stress.

Effect of Mechanical Compression on Ionic Conductivity of PEO-LiTFSI Solid Polymer Electrolytes

In the field of energy storage materials, the development of robust solid polymer electrolytes for lithium-ion batteries necessitates an understanding of ionic conductivity when subjected to mechanical stress. Accurate determination of ionic conductivity requires knowing the electrolyte thickness, which is subject to volumetric changes during charging and discharging of solid-state batteries. However, compressive stress reduces the thickness of the electrolyte by an indeterminate amount.This work presents experimental measurements of ionic conductivity as a function of compressive stress, using poly(ethylene oxide) and with bis(trifluoromethane) sulfonimide (PEO-LiTFSI). In this study, we not only measure the stress-strain response of the electrolytes directly, but also monitor the extent of compression during electrochemical impedance spectroscopy (EIS). Compression was applied up to 50% strain for three consecutive cycles, and the typical thickness for the fabricated electrolytes was ~50 µm. EIS testing was performed by using an impedance analyzer, with the electrolyte placed between stainless steel blocking electrodes. Bulk resistance was determined by equivalent circuit modeling of impedance between 100 Hz and 2 MHz. Ionic conductivity κ was calculated from bulk resistance Rb , electrolyte thickness h, and cross-sectional area A, according to the equation κ = h/(Rb·A).In order to measure both stress and deformation simultaneously, a custom positioning stage was engineered to apply prescribed compression. The apparatus has an in-line load cell for force measurements and a laser triangulation sensor for position tracking with submicron resolution. We found that the bulk resistance at room temperature decreases exponentially, with magnitude reduced by approximately five-fold when subjected to compressive stress up to 10 MPa. Beyond ~7 MPa, bulk resistance values were no longer dependent on the amount of applied compression.In addition to mechanical measurements, changes in crystalline and amorphous regions were correlated to the magnitude of compressive stress and the measured ionic conductivity of the electrolyte. For optical imaging with simultaneous EIS measurements, glass slides coated with an indium tin oxide (ITO) film were used instead of stainless steel disks. The extent of crystallinity was visualized by optical microscopy of spherulites through a viewing window when compressed between rigid plates.Figure 1. Apparatus (left) and representative ionic conductivity vs. compressive stress (right) data for a PEO-LiTFSI polymer electrolyte. Figure 1

Analytical model of the steady state temperature distribution in a single and multi-layer brake disc

This article focuses on the modeling and analyzing effort for the thermal analysis and design of disc brake for endurance braking scenario. Test cases of bike disc brake rotor are chosen as its unique double layered architecture has been recently proposed for thermal optimization especially. This work aims at the evaluation of the steady state temperature distribution during braking to be studied considering a constant rotation speed and localized heat sources at the brake pad area. The problem is solved analytically using variable separation and a double Fourier - Hankel transforms.The modelling strategy is developed for a single layered rotor as reference cases for various rotation speed and rotor thicknesses. The effect of the rotation speed is underlined using a representative constant heat exchange coefficient. For high rotation speed (greater than 50 rad s-1 for the studied geometry), an effective surface layer can be observed which limits the influence of the rotor thickness on the temperature level. The model is extended to a multi-layered material rotor architecture. The potential advantages of this composite structure for different layer thicknesses and materials are evaluated and discussed. It appears that the aluminium core provides the better results, yet the relative reduction of the temperature compared to a plain stainless steel disc is of about 1 % only.

Determination of “tribological performance working fields” for pure PEEK and PEEK composites under dry sliding conditions

Poly-ether-ether-ketone (PEEK) and PEEK composites are widely used polymers in many engineering applications where dry sliding is required. In this study, the influence of sliding velocity and applied load values on the friction and wear behavior of pure PEEK, 30 wt% glass fiber reinforced PEEK (PEEK-30GF), 30 wt% carbon fiber reinforced PEEK (PEEK-30CF) and 10 wt% carbon fiber+10 wt%graphite +10 wt%poly-tetra-fluoro-ethylene (PTFE) filled PEEK (ie. High (H) pressure (P) and velocity (V) resistant PEEK (PEEK-HPV)) composites rubbing against AISI 304 stainless steel disc was investigated. The experiments were carried out at room temperature under dry sliding conditions in a pin-on-disc wear rig. The applied loads ranged from 30 to 250 N, while the sliding velocities ranged from 1.0 to 4.0 m/s. At these load and velocity ranges, the friction coefficient-wear rate relationship of pure PEEK and composites was established and evaluated. In addition, the operating load-velocity limits of each material were determined and stated. The lowest coefficient of friction and wear rate were obtained in PEEK-HPV, PEEK-30CF, PEEK-30GF composites and pure PEEK polymer, respectively. In addition, it was observed that the coefficient of friction (CoF) decreased and the specific wear rate (SWR) increased with the increase in sliding velocity and applied load in all PEEK materials. The wear rate values of PEEK-HPV and PEEK-30%CF composites are in the range of 10−7 - 10−6 (mm3/Nm), while the wear rate values of pure PEEK and PEEK-30%GF are in the range of 10−6 - 10−5 (mm3/Nm). It was determined that carbon fiber, graphite and PTFE additives added to PEEK polymer as hybrid were very effective in reducing the wear rate of PEEK composite (PEEK-HPV). An adhesive wear mechanism was observed in PEEK-HPV and PEEK-30CF composites both at low load and velocity values and at high load and velocity values.

Coating of the Surface of 316L Stainless Steel with Hydroxyapatite Produced from Eggshell Using the Sol-Gel Method

In this study, the production of high-yield and purity calcium nitrate from eggshell, a biological waste, and the usability of the obtained calcium nitrate in the production of hydroxyapatite (HAP) by the sol-gel method were investigated. In addition, the obtained HAP was used to coat 316L steel using the dip coating method. For this purpose, calcium nitrate, which will be used as a precursor in HAP production, was produced from chicken eggshells with high calcium carbonate content. The surface of 316L stainless steel discs was coated with sol-gel obtained from a mixture of calcium nitrate and triethyl phosphite by dip-coating method. Then, the 316L discs were dried and heat treated at 500 °C to form HAP on their surfaces. XRD and SEM techniques were used for the characterization of the obtained HAP structure. Unlike previous studies, it has been shown that chicken eggshell, a biological waste, can be used to produce HAP, a biocompatible material, and the surface of 316L stainless steel can be coated with the produced HAP.

Study of tribological performance and corrosion resistance of aluminum alloy 6063 composites enhanced with a combination of silicon carbide and tungsten disulfide particles

This research explores the effects of wear on a 6063 aluminum alloy matrix combined with silicon carbide (SiC) and tungsten disulfide (WS2) particulates. Dry friction wear tests were conducted on three materials: pure 6063 aluminum alloy, a composite with 4 wt% SiC and 4 wt% WS2 reinforcement, and another composite with 6 wt% SiC and 4 wt% WS2 reinforcement. These materials were tested against AISI410 stainless steel discs under varying loads (10N, 20N, and 30N) and sliding rates (0.5, 1.0, and 1.5 ms−1) following a Taguchi L27 orthogonal experimental plan. Main effect graphs (S/N ratios) and ANOVA analysis were utilized to determine optimal parameter combinations, and confirmation tests were carried out to validate the Taguchi results. Scanning electron microscope (SEM) images of wear areas showed that incorporating SiC and WS2 significantly enhanced the wear resistance of the aluminum alloy. This indicates that incorporating SiC and WS2 reinforcement has the potential to enhance the wear resistance of aluminum alloys, making them suitable for applications such as piston rings in internal combustion engines, which is in line with the requirements of engine performance. Furthermore, potentiodynamic polarization studies evaluated the corrosion resistance of the Metal Matrix Composites AA6063 in 3.5% NaCl. Results indicated that the AA6063 + 6 wt% SiC + 4 wt% WS2 composite exhibited superior corrosion resistance compared to AA6063 alone.

NUMERICAL SOLUTION OF COUPLED HEAT TRANSFER WITH PHASE CHANGE AND THERMITE REACTION

The thermite reaction is a self-sustained exothermic reaction commonly employed in welding processes of railway tracks, material synthesis, pyrotechnics, etc. More recently, this reaction has been assessed to plug depleted oil wells. The investigated geometry is modeled as a two-dimensional axisymmetric domain with a thermite mixture compressed between a polymethylmethacrylate (PMMA) lid and a stainless steel disk. First-order kinetic is assumed for the chemical kinetics model. The governing equations are discretized with the finite-volume approach. Experimental validation is performed by comparing numerical combustion velocities and peak temperatures with the experimental data in the literature. The results demonstrate a remarkable thermal gradient through the longitudinal direction, displaying higher thermal losses next to the thermite-steel interface. These heat losses also affect the melting of species, as a small portion of alumina remains entirely solid during the reaction.

Development and validation of a gel wax phantom to evaluate geometric accuracy and measurement of a hyperechoic target diameter in diagnostic ultrasound imaging.

Diagnostic ultrasound (US) scanners are generally evaluated using proprietary quality assurance (QA) phantoms, but their prohibitively high cost may prevent organizations to perform the necessary tests. This study aimed to develop a low-cost gel wax phantom with targets to determine the lateral and axial resolution and diameter of a hyperechoic target in an US scanner. The acoustic property (AP) of gel wax, which includes the speed of sound (cus), acoustic impedance (Z), and attenuation coefficient (µ), were determined for multiple transducers operating at 2.25, 5, 10, 15, and 30MHz. These results were compared to the AP of soft tissue. Two polytetrafluoroethylene (PTFE) rectangular frames with holes separated by 5, 10, and 20mm were constructed. Nylon filaments and stainless-steel disc (SS disc) (diameter = 16.8mm) were threaded through the frames and suitably placed in gel wax to obtain orthogonal targets in the phantom. The target dimensions obtained from computerized tomography (CT) and US images of the phantom were compared for phantom validation. The average cus=1431.4m/s, mass density ρ = 0.87g/cm3, Z = 1.24 MRayls, and µ ranged from 0.7 to 0.98 dB/cm/MHz for gel wax at 22°C. The US image measurement exhibited a maximum error in determining the diameter of the SS disc, resulting in a value of 18mm instead of its actual value of 16.8mm. The phantom volume decreased by 1.8% in 62 weeks. The present phantom is affordable, stable, customizable, and can be used to evaluate diagnostic US scanners across multiple centers.

Using infrared imaging to measure the friction coefficient during pin-on-disk sliding wear tests

In a standard pin on a disk tribometer, the friction coefficient under a sliding wear configuration is commonly obtained from the experimental measurement of the tangential force, which is usually achieved through either a load cell attached to the pin holder or a torque meter attached to the disk shaft. This paper presents an alternative method to measure the friction coefficient using a combination of thermal imaging and a reverse thermal model.The measurement of the temperature evolution of the pin, allow to solve the friction heat generation problem between the mating surfaces. Heat generation is influenced by the friction coefficient and the test parameters, whilst conduction is also significantly affected by the thermophysical properties of the materials. Experimental tests with PTFE pins with lamellar bronze filler and Cr2O3-coated stainless steel disks showed an average difference of the friction coefficient of about 12% between the new thermal and the standard measurement.

Titanium Dioxide/Graphene Oxide Composite Coatings for 316 Stainless Steel Dental Implants.

Stainless steel has been used in orthopedics and orthodontic fields. However, it cannot be used for fabrication of dental implants due to its inertness, low biocompatibility and weak resistance to corrosion. A composite coating of titanium oxide /graphene oxide has been prepared for stainless steel to improve its biological properties. Stainless steel discs were polished, cleaned and pre-treated with a mixture of HNO3 and HF acid for 15 min. The composite coating composed of TiO2 produced by sol-gel technique and doped with 0.75 wt% graphene oxide. XRD, SEM-EDX and AFM were employed to characterize the composite coating. The anti-bacterial action of the composite coating was investigated against S. aureus and E. coli. The corrosion resistance of coated and noncoated samples was assessed in SBF using electrochemical technique. Cytotoxicity was assessed using osteoblast-like cells. The wettability was determined by contact angle, and bioactivity assessed by immersion in SBF. The results revealed that the composite coating was dense with few micro-cracks, and was not cytotoxic to osteoblast-like cells. The composite coating reduced bacterial colonies and the corrosion rate of the steel was improved. The wettability of the sample was increased with the composite coating and apatite formation appeared after 21 days.

Mechanical cleaning of food soil from a solid surface: A tribological perspective

In this work, a tribological approach was used to distinguish the synergistic effects of mechanical removal and chemical removal (i.e. dissolution) of a layer of representative food soil from a solid surface, using a tribometer, Mini Traction Machine (MTM). Gravimetric and wear measurements of the soil were used to calculate the cleaning rates of burnt tomato puree on a stainless-steel disc, and the corresponding frictional characteristics offers insight of the mechanical removal. The cleaning due to soil dissolution (chemical removal) was quantified by UV–Vis measurements. The overall cleaning rates of food soil featured a linear reduction in mass over time, with a scaled removal rate k = 0.0046 s−1 (5 N applied force and 100 mm s−1 relative velocity), for most cases studied. It was observed that the cleaning rate can be improved with an increasing mechanical load or speed (50% from 1 to 2.5 N and 13% from 50 to 100 mm s−1), but is independent of the initial mass. UV–Vis measurements show that by increasing the load or speed the removal of chunks of burnt tomato puree was enhanced more than removal attributed to dissolution. Similar values of cleaning rates for most experimental parameters were extracted from both the gravimetric and wear measurements. Adhesion and cohesion measurements of the burnt tomato puree were conducted with a micromanipulator. It was found that adhesion forces are higher than cohesion for short soaking times, but for longer times the adhesion forces became weaker and with the additional shear rate in the MTM cleaning experiment, adhesion failure was observed in many cases by the end of the experiment. Indentation measurements showed the change in mechanical properties of the food foulant with a few minutes of soaking in water.

Food grade disinfectants based on hydrogen peroxide/peracetic acid and sodium hypochlorite interfere with the adhesion of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes to stainless steel of differing surface roughness

This study aimed to evaluate the potential of the bacterium Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes to adhere to stainless steel discs with differing degrees of surface roughness (Ra = 25.20–961.90 nm). Stainless steel is a material commonly used in the food industry for processing equipment, which is regularly exposed to cleaning procedures. The investigation included the commercial disinfectants hydrogen peroxide/peracetic acid and sodium hypochlorite which were evaluated for their antibacterial and anti-adhesion activity. The adhesion was assessed by the standard plate count method, while the broth microdilution method CLSI M07-A10 was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the disinfectants. Based on the MIC values, both disinfectants exerted significant inhibitory effects with MIC values for hydrogen peroxide/peracetic acid and sodium hypochlorite of 250 µg ml−1 and 500 µg ml−1, respectively. Whereas the MBC values were equal to the MIC for all bacteria except for E. coli with values 2-fold higher than the MIC. Obtained results also revealed that all tested bacteria were able to adhere to stainless steel surfaces, although differences were found for strains and surface roughness. The lowest adhesion rate of each strain was recorded on the roughest stainless steel disc at a Ra of 961.90 nm. Further, at a concentration of 1 MIC, the disinfectant sodium hypochlorite reduced initial bacterial adhesion to stainless steel surfaces to a significantly greater extent than the disinfectant hydrogen peroxide/peracetic acid. These findings are consistent with the results obtained by Scanning Electron Microscopy (SEM) analysis, which indicates the great applicability of the tested disinfectants for the control of bacterial adhesion in the food industry.

Tribological responses of steels to different surface films generated in oil lubricants

PurposeThe aim of this study is to experimentally analyze the friction and wear responses of different steels to different surface films generated in oil-lubricated tribological contacts.Design/methodology/approachTribological experiments were conducted using a 100Cr6 bearing ball sliding against a V155 carbon steel disk and 316L stainless steel disk, respectively. Lubricants with additives known to form zinc dialkyl-dithiophosphate (ZDDP) or Ca tribofilms were used.FindingsBoth of the ZDDP and Ca tribofilms helped stabilize the friction coefficient of the carbon steel and stainless steel. The ZDDP tribofilm could effectively protect the carbon steel from wear, in contrast to the stainless steel, whereas the wear of both carbon steel and stainless steel could be significantly reduced by the Ca tribofilm. In the case of neither ZDDP nor Ca tribofilms formation, the 100Cr6 ball was worn by the V155 disk and generated a special surface topography. A polishing wear mechanism was proposed to explain the wear of the 100Cr6 ball.Originality/valueThis study clearly shows the different friction and wear responses of steels to the different surface films and the response is dependent on the tested steel.

Inhibitor activity of lactiplantibacillus plantarum LP5 on thermotolerant campylobacter with different biofilm-forming capacities.

To evaluate the biofilm-forming capacity of thermotolerant Campylobacter (TC) strains from poultry production and to analyse the inhibitory capacity of Lactiplantibacillus plantarum LP5 against TC on different materials. Biofilm-forming capacity by Campylobacter jejuni and Campylobacter coli was analysed by cell adhesion in polystyrene plates. TC were classified as non-biofilm-forming (NBF, 1.3%), weak biofilm-forming (WBF, 68.4%), moderate biofilm-forming (MBF, 27.6%), and strong biofilm-forming (SBF, 2.7%). The inhibitory capacity of L. plantarum LP5 against TC was tested on stainless-steel, nylon, aluminium, and glass disks (treated group) and compared with biofilm-forming TC (control group). L. plantarum LP5 was inoculated, and then TC. Biofilm was removed in both experimental groups and TC and LP5 bacterial counts were performed. The L. plantarum LP5 presence reduced the formation of TC biofilm (P<0.001). The material type and strain category influenced biofilm formation, with stainless-steel and the SBF strain being the material and TC having the highest adhesion (P<0.001). L. plantarum LP5 formed similar biofilm on all materials (P=0.823). This trial showed very promising results; L. plantarum LP5 could be incorporated as a bio-protector of TC on different surfaces.

Modelling in the frame of hydro-mechanical infiltration column experi-ment to study the behaviour of binary mixtures of bentonite MX80

Binary mixtures of high-density MX80 bentonite pellets (80% mass ratio at a dry density of 2.0 Mg/m3) and powder (dry density of 1.1 Mg/m3) at hygroscopic water contents are studied by the French Institute of Radiation Protection and Nuclear Safety (IRSN) as an alternative in engineered barrier systems for the long-term disposal of radioactive wastes. The MX80 bentonite was studied by many authors [1–4] with this aim. These mixtures show a dry density around 1.49 Mg/m3 on pouring into infiltration column experiment tests.&#x0D; An infiltration column cell (100 mm in diameter and 350 mm high) has been developed at a reduced scale of 1/100 of the VSS (i.e., at 1/10 of the in situ VSEAL test) to reproduce asymmetric hydration using independent top (fast injection) and radial (slow injection) water pressure systems, which will undergo fast hydration from the calcareous Oxfordian formation at the top and a slower one by water reaching radially through the Callovo-Oxfordian formation. It also allows performing gas injections at different locations of the core of the bentonite mixture (top and bottom boundaries) and under various hydraulic states. The infiltration column is composed of four transparent cylinders, made of Perspex to visualise processes occurring at the interface during the hydration and gas injection phases (Figure 1a). This cell has been assembled with three stainless-steel injection rings that ensure slow radial water injection through three independent automatic pressure/volume controllers. These stainless-steel injection rings also hold the different lateral transducers (six total stress cells and three water pressure transducers embedded in the soil and three relative humidity probes installed in small dismountable chambers) (Figure 1a). The assembled cell is inserted into a rigid frame composed of two stainless steel disks on the two sides of the cylinder connected by four metallic rods.&#x0D; A numerical model has been developed to better understand the coupled hydro-mechanical response of this multi-porosity mixture and particularly of its constitiuents upon hydration.The characterisation of pellet and powder components have been focused on their water retention properties, water permeability, compressibility on loading and on suction changes, as well as on their swelling pressure response and the progressive changes of their pore size distribution on wetting. This information at component scale has allowed the upscaling into a 2D plane-strain numerical model based on the discretisation of pellets and inter-pellet powder using Code_Bright FEM [5]. This plane-strain model captures the pellet shape effect without changing the geometry of the pellets.The geometry used in the simulations corresponds to an infiltration column at constant volume mimicking the actual asymmetric hydraulic conditions of the VSS. Figure 2b presents the geometry of the model used at constant volume based on the discretisation of pellets and powder (252 pellets of 8 mm diameter and surrounded by powder filling the entire inter-pellet volume).The generated numerical mixture has a mass-basis proportion of 77.6% pellets and 22.5% powder, which is close to the mixture proportion. Figure 1b shows the three lateral slow-rate hydration boundaries, as well as the fast-rate hydration boundary at the top. The modelling has focused on analysing the global and particularly the local responses: water mass transfer between powder and pellets, evolution of local degrees of saturation and porosities (inside pellets and powder), and mean stress evolution in the pellet and powder domains. Water retention and permeability properties of the components are dependent on porosity and the degree of saturation.&#x0D; A non-linear elastic model has been considered for the components, in which volumetric deformations are induced by net mean stress and suction changes. Therefore, the pellets and powder have different hydraulic and mechanical properties as a consequence of the different initial properties, but they share the same constitutive relationship of a single structured material. Figure 1c presents the time evolution of porosities (inside the pellets and powder), showing that the mixture tends towards a more homogeneous distribution of porosity as the pellets expand and compress the highly deformable clay powder. During the transient hydration stage, the expansion of pellets at the top of the column evolves faster due to the proximity of the hydration front. Figure 1d shows the water retention curves of the pellets and powder at the initial state and after hydration as predicted by the model, compared to experimental data [6,7]. The predicted water retention curves of the pellets and powder adequately follow the trend of the data reported by [7] and also seem to reproduce the mixture model data suggesting a homogenisation of the retention properties of the material after hydration.

Measurements of gas-liquid two-phase flow dynamics using high-speed neutron imaging

Gas-liquid two-phase flow appears in many heat-exchanging devices. The two-phase flow dynamics should be clarified to understand the phenomena in such devices. Although many measurement techniques have been applied to two-phase flow experiments, measuring the gas-liquid interfacial structure is difficult, which changes temporally and spatially. In this study, high-speed neutron imaging is used to measure two-phase flow dynamics, and the accuracy of the void fraction measurement is investigated. In high-speed neutron imaging, image blurring and distortion occur due to light and object motion intensifying. As a result, the quantitative accuracy might decrease. So, the rotating stainless-steel calibration disk, which simulates the bubble behavior in water, is observed by high-speed neutron imaging. Several noise reduction filters are tested to remove the blur and noise in the acquired images. Finally, the air-water two-phase flow is visualized by high-speed neutron imaging, and noise filtering is applied.

Effects of trace moisture content on tribofilm formation, friction and wear of CF-filled PTFE in hydrogen

This study investigated the effects of trace moisture in hydrogen gas on the tribological behavior of carbon fiber (CF)-filled polytetrafluoroethylene (PTFE) composites by examining 20 wt% polyacrylonitrile-based CF-reinforced PTFE composites against stainless-steel disks in gaseous hydrogen environments, where moisture content was controlled at 1, 10, 20, and 40 ppm. The results revealed tribological characteristics of the sliding couples were significantly affected by the moisture content. Wear rates of pin specimens tended to increase gradually with moisture content. Similarly, average coefficient of friction increased as moisture content increased from 1 to 20 ppm. However, it decreased upon further increasing the water content. Moreover, surface analyses of the formed tribofilms at varying moisture contents revealed significant variations in terms of the amount and structure.

Virucidal activity of oral, hand, and surface disinfectants against respiratory syncytial virus

Respiratory syncytial virus (RSV) is known as a major cause of respiratory tract infection in adults and children. Human to human transmission occurs via droplets as well as direct and indirect contact (e.g. contaminated surfaces or hands of medical staff). Therefore, applicable hygiene measures and knowledge about viral inactivation are of utmost importance. Here, we evaluated the virucidal efficacy of oral rinses specifically designed for children, WHO-recommended hand rub formulations and ethanol as well as 2-propanol against RSV in a quantitative suspension test (EN14476). Furthermore, we assessed the stability of RSV on stainless steel discs and investigated its inactivation by different surface disinfectants (EN16777). We observed that all tested oral rinses except one reduced infectious viral titres to the lower limit of quantification. The two WHO-recommended hand rub formulations as well as 30% ethanol and 2-propanol completely abolished the detection of infectious virus. Infectious RSV could still be recovered after several days on stainless steel discs. However, RSV could efficiently be inactivated by all tested surface disinfectants based on alcohol, aldehyde, or hydrogen peroxide. In conclusion, oral rinses, all tested hand rub formulations as well as surface inactivation reagents were sufficient for RSV inactivation in vitro.

A study on the effect of plasticity on the measurement of residual stresses using ultrasound technique

Residual stresses can have detrimental effect on the life cycle of engineering components and can affect the accuracy of the fatigue life prediction models. Accurate measurement of these stresses are therefore crucial. . However, destructive and semi-destructive methods of measuring residual stresses often cause damage to the components. In contrast, the non-destructive ultrasonic method allows for intact measurement of residual stresses even, in situation where portability is not feasible. Various waves can be utilized in the ultrasonic method for measuring residual stresses. In this study, longitudinal critically refracted (LCR) waves were employed due to their higher sensitivity, larger scanning area, and lower sensitivity to texture effect, making them preferable over other waves. The purpose of this study was to investigate the influence of plasticity on the measurement of residual stresses using the ultrasonic method. To achieve this, two stainless steel disks were subjected to quenching at temperatures of 300 °C and 700 °C to induce different levels of residual stresses and plasticity. The material properties of the disks were determined through standard tensile tests to facilitate numerical simulations. Tensile test specimens were extracted from the initial sheet to measure the yield stress and modulus of elasticity. The coefficient of acoustoelasticity, was determined by subjecting the tensile test specimens to different stress levels and recording the wave flight time. The coefficient of acoustoelasticity for stainless steel 316Lwas obtained using the slope of and (E(t-t0))/t0,. Residual stresses were experimentally measured using both the ultrasonic method and the center-hole drilling method, and the results were compared with those obtained from numerical analyses. The findings from center-hole drilling method, ultrasonic method, and numerical simulation were then compared and discussed. Different levels of plasticity were considered, and the accuracy of measuring residual stresses was analyzed and evaluated.