Sample Surface Research Articles

Theoretical Calculations and Experimental Study of the Nitrided Layer of 1Cr17Ni2 Steel

Due to the harsh operating conditions experienced by 1Cr17Ni2 steel, efforts were made to optimize its performance by subjecting 1Cr17Ni2 stainless steel to nitriding treatments at temperatures of 460 °C, 500 °C, and 550 °C, each for durations of 8 and 16 h. The formation state of its cross section was observed through a metallurgical microscope and scanning electron microscope, and it was characterized by hardness measurement. Through a ball-on-disk wear experiment, the adhesive wear and friction coefficient of its non-lubricated sliding were measured. The phase composition of its surface was measured by XRD. The results revealed that nitriding led to the formation of a modified layer on the surface of the samples, with a depth of 130 μm after nitriding at 550 °C for 16 h. The hardness of the modified layer exceeded that of the matrix, reaching up to 1400 Hv0.1. X-ray diffraction (XRD) analysis of the sample surfaces indicated the presence of high-hardness phases such as CrN, γ′-Fe4N, and ε-Fe2-3N. This article predicts the mechanical properties of nitrided phases in high-alloy martensitic stainless steel through first-principles computational methods. We provide a reference for improving the performance of high-alloy steel after nitriding through a combination of theoretical calculations and experiments.

Spatiotemporal Analysis of Secondary Metabolites Produced by S.coelicolor Using Automated Sampling Mass Spectrometry

Natural products (NPs) are organic compounds that are synthesized by living organisms such as bacteria. NPs and their derivatives are very useful in the medical field to develop new drugs, particularly new antibiotics which are crucial to combat developing antibiotic resistance. The current research on the secondary metabolites (SMs) produced throughout the growth cycle of bacteria is limited, as the standard procedure is to examine the SM production at the end of the bacteria’s growth cycle. Therefore, there may be many undiscovered SMs which are produced and consumed prior to analysis. A mass spectrometer (MS) can be used to track analytes of interest, such as SMs. When the MS is paired with an ambient ionization technique like the Liquid Micro-Junction Surface Sampling Probe (LMJ-SSP) it works as a minimally invasive approach to track the SMs in real time produced throughout the bacterial growth cycle. This allows for the SMs to be tracked both temporally and spatially without killing the bacteria. The process is automated using the LMJ-SSP mounted to a 3D printer, allowing for a grid-like sampling process to map NPs production. Herein, A 3D-printed growth chamber dubbed the “Washing And Sampling Agar Bacterial Inoculation” (WASABI) Box was designed to resemble a sampling grid for simpler analysis. Another key feature of the WASABI Box are washing ports, containing 70% ethanol, to sterilize the LMJ-SSP and minimize contamination between rows. The SM production of S. coelicolor in the WASABI Box was analyzed from day 4 to 7 of the bacterial growth cycle, where the data was used to generate spatial-temporal heat maps tracking metabolites including Albaflavenone (m/z 219.2), Desferrioxamine B (m/z 561.4), Germicidin B (m/z 183.1), Kalafungin (m/z 301.1), and Streptorubin B (m/z 392.3).

Content, Sources, and Ecological Risk Assessment of Heavy Metals in Soil of Typical Karst County

Soil heavy metals in karst areas have obvious high background value characteristics. Conducting county-level soil heavy metal ecological risk assessment and identifying heavy metal sources in karst areas are of great significance for soil pollution control and land resource management. Taking Pingguo City, a typical karst county in Guangxi Province, as the study object, 3 151 surface and deep soil samples were collected using the grid method and combined to form 785 analytical samples. The contents of eight heavy metal elements, including As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, were determined. The content characteristics and sources of heavy metals were analyzed using statistical analysis, interpolation analysis, factor analysis, and the absolute principal component-multiple linear regression model （APCS-MLR）. Using the content of heavy metal elements in deep soil （150-200 cm） as background values, the ecological risk assessment of heavy metals in surface soil （0-20 cm） in the study area was conducted using the geo-accumulation index （Igeo） and potential ecological risk index （RI） methods. The results showed that the average content of heavy metal elements in the deep soil of the study area was significantly higher than the background value of the C layer soil in Guangxi Province, and the average content of heavy metal elements in the surface soil was significantly higher than the background value of the A layer soil in Guangxi Province. The spatial distribution of soil heavy metal element content generally showed the characteristics of high in karst areas and low in non-karst areas. The main sources of As, Cr, Ni, Pb, and Zn were soil parent materials, with contribution rates of 74.36%, 84.59%, 93.69%, 79.67%, and 78.17%, respectively. The main sources of Cd were soil parent material sources and unknown sources, with contribution rates of 37.33% and 31.05%, respectively. The main sources of Cu were soil parent materials and unknown sources, with contribution rates of 59.07% and 40.23%, respectively. The main sources of Hg were tectonic activity and mineralization, as well as unknown sources, with contribution rates of 52.49% and 30.65%, respectively. The geo-accumulation index （Igeo） showed that the surface soil was mainly polluted by Cd, with mild or above pollution accounting for 47.78%. The potential ecological risk index （RI） showed that the proportion of surface soil heavy metal comprehensive potential ecological hazards with mild, moderate, strong, and very strong levels was 80.78%, 14.97%, 2.51%, and 1.64%, respectively.

Annealing Time Dependence on Creation of SiV, GeV, and SnV in Diamond by Atmospheric Annealing at 1800 °C

The creation of SiV−, GeV−, and SnV− are presented by the atmospheric annealing in the argon flow. Compared to high‐pressure annealing, in which gas cannot flow, atmospheric annealing with an inert gas flow not only causes less degradation of the sample surface but also has the advantage of reducing equipment cost and preparation time. Excessive annealing time has been shown to reduce the amount of centers created. The optimal annealing time that maximizes formations depends on the type of diamond sample and the implanted ions. Furthermore, inspired by the split‐vacancy structure of the group IV–V centers, atmospheric pre‐annealing at 600 °C to increase the amount of di‐vacancy is demonstrated, followed by annealing at 1800 °C for 1 min. A shorter duration of high‐temperature annealing is expected to qualitatively reduce stress and deterioration of the crystallinity of the diamond sample.

Levels, enrichment characteristics, and health risks of halogenated and parent polycyclic aromatic hydrocarbons in traditional smoked pork

Chinese traditional smoked pork was contaminated with polycyclic aromatic hydrocarbons (PAHs) and chlorinated and brominated PAHs (ClPAHs and BrPAHs; XPAHs) during the smoking process. Therefore, our study investigated the concentrations, enrichment characteristics, and health risks associated with PAHs, as well as ClPAHs and BrPAHs in Chinese traditional smoked pork. The total concentrations of PAHs, ClPAHs and BrPAHs in traditional smoked pork ranged from 90.0 to 79200 ng/g fat weight (fw), 23.6–2340 pg/g fw and 0.550–200 pg/g fw, respectively, which were significantly higher than their levels found in raw pork. Additionally, the concentrations of PAHs and XPAHs in the surface of smoked pork were higher than those in the inner parts. High-ring PAHs exhibited a greater enrichment compared to low-ring PAHs, and BrPAHs exhibited greater enrichment ability than ClPAHs in smoked pork. Furthermore, the ability of individual congeners to migrate from the surface to the inner parts of the smoked pork were varied. When the smoking fuels were similar, a longer smoking time resulted in higher concentrations of PAHs and XPAHs in smoked pork, while casing effectively reduced their concentrations. The correlation between XPAH and parent PAH concentrations indicated that chlorination of PAHs was one of the primary formation mechanisms of some monochlorinated PAHs. Over half of the smoked pork samples posed a potential carcinogenic risk, particularly the surface samples. It is recommended to remove the surface parts when consuming smoked pork and to improve traditional smoking methods to mitigate the health risks.

Investigating Flow-Induced Corrosion of Magnesium in Ophthalmological Milieu.

Although the impact of local fluid dynamics in the biodegradation of magnesium is well known, currently no studies in the literature address the degradation effects of ocular vitreous on bioresorbable devices made of magnesium, which could be developed as drug delivery carriers. The aim of this study was to investigate the flow-induced corrosion mechanism of magnesium in an ophthalmological environment for future applications in ophthalmic drug delivery. To achieve this, experimental and computational methods were combined. Specifically, a CFD model was employed to design experimental conditions that replicate the ocular flow-induced shear stress (FISS) on manufactured magnesium samples. Pure Mg samples were tested in a bioreactor system capable of imposing the ocular CFD calculated values of FISS on the Mg samples' surface by varying the pump flow rate. Optimal flow rates for a range of different FISS values specific to the ophthalmological fluid dynamics affecting the device were indeed determined before running the experiments. After conducting customized corrosion tests, morphological observations and profilometric maps of the eroded surfaces of Mg samples were obtained using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). These maps were then post-processed for the parametric evaluation of corrosion rates. Pre-existing localized superficial defects did affect the final corrosion pattern. SEM images and CLSM data confirmed a uniform corrosion mechanism, with corrosion rates of 1.9, 2.7, and 3.4 μm/day under different shear stress conditions (0, 0.01, and 0.032 Pa, respectively). More generally, uniform corrosion on pure Mg samples increased with higher FISS values, and at higher shear stress values (FISS = 0.032 Pa), a notable washing-out effect of the corrosion products was observed. The removal of corrosion products at higher shear stresses suggests that the dynamic ocular environment, influenced by saccadic movements, plays a significant role in the corrosion mechanism of pure magnesium. The corrosion rates determined in this study, in conjunction with clinical drug release requirements, are crucial for designing potential drug-release devices for ocular applications.

Investigation of mechanical and wettability properties of commercial pure titanium by surface mechanical attrition treatment

The examination of mechanical and wettability properties of commercial pure titanium (CP-Ti) introduced a novel challenge. The microstructure of samples was analyzed by using OM and SEM micro-images. In this study, the hardness of the surface and cross section of samples was evaluated, and the effect of several surface mechanical attrition treatments (SMATed) on samples was examined. Also, the tensile test was done to compare the effect of SMAT duration on mechanical properties of samples. The contact angle method was then employed to investigate the impact of SAMT duration on the wettability trend. According to results, as the treatment time increases, twins become evident in the deeper layers of the samples. In contrast, the near-surface twins are shorter than those found in the deeper material, signifying the presence of finer grains. Moreover, the elevated hardness in SMATed samples can be attributed to several key factors, including cold work, a rise in defects and twins, and grain refinement. The surface hardness increases across the sample series (up to Ti6) due to the substantial energy input. Nevertheless, it is anticipated that further continuation of the process will result in a constant surface hardness. The increased strength observed in SMATed samples can be attributed to factors such as reduction in grain size and the formation of twins. The wettability results show that the treated surfaces exhibited a significant change in wettability compared to the untreated samples, with a 25% reduction in the contact angle. This is attributed to the surface modifications induced by the treatment process, which introduced more hydrophilic functional groups. The results also show that after 4 h of treatment, the contact angle increases, suggesting that the trend may plateau with additional treatment time.

Experimental study of wear and rolling contact fatigue in railway wheel steels coupled with various brake block materials: Insights from innovative small-scale testing

This study presents a comprehensive analysis using an innovative testing method of two wheel steels paired with cast iron and organic composite brake block materials. By conducting tests under consistent conditions and varying in duration, the study examines temperature profiles, friction coefficients, surface characteristics, weight loss, and microstructural changes in wheel samples, emphasizing the distinct behaviour of these materials in braking applications and the damage evolution over time. The results demonstrate that organic composite brake samples outperform those in cast iron, showcasing smoother wheel sample surfaces and stable friction coefficients. Weight loss analysis reveals the environmental benefits of organic composite brakes, emitting fewer particulates than cast iron counterparts. Microstructural examinations uncover the formation of a Thermal White Etching Layer (T-WEL) on wheel samples tested with cast iron samples, leading to cracks and material detachment. Conversely, extended use of organic composite samples led to a "thermal fuse effect", impacting their efficiency and suggesting the need of careful temperature management in sustained braking scenarios. Despite significant differences in wheel steels, the study underscores the critical role of brake material in braking improvements. The findings not only enhance the scientific understanding of brake material behaviour but also introduce an innovative, cost-effective, and fast 4-contact machine testing method.

An attention-based architecture for predicting thermal stress on turbine blade film hole surface using partial temperature data

The thermal stress of film holes is crucial for the life of turbine blades with double-wall cooling systems. Finite Element Analysis (FEA) is widely used for thermal stress analysis, which requires the entire temperature field as input. However, only partial temperature data can be measured in engineering experiments, which is insufficient for FEA. This study proposed an attention-based deep learning architecture to map partial temperature data to film hole surface thermal stress. A thermal stress dataset with 300 samples of double-wall cooling units was constructed using conjugate heat transfer and FEA simulations and the thermal stress prediction model was trained using this dataset. Compared with the simulation results, the mean relative error (MRE) of the predicted results on the test dataset is 7.43%, and the MRE of peak thermal stress is 2.16%. The impact of the model input composed of different surface groups and sampling schemes on prediction performance was analyzed, and a reference for temperature measurement arrangement that balances accuracy and cost-effectiveness was proposed. Additionally, The impact of input noise on model performance was explored and the results demonstrate that the model trained with noise demonstrated significantly enhanced resistance to noise, and the MRE was about 8%.

Spotting ignition of plastic foam by a fast-moving hot metal particle

Spotting ignition involves dynamic interaction between fuel bed and hot particles, but the scientific understanding of the ignition by a fast-moving hot particle is still limited. Herein, a hot steel particle with various horizontal velocities, temperatures, and sizes is shot to ignite vertically oriented low-density expandable polystyrene foam. A high-speed particle can directly get embedded into the foam to achieve flash-point, fire-point, or no ignition, while a low-speed particle bounces away from the foam without ignition. Results show that for a particle of 1150 °C, its minimum velocity for embedding is 12.00 m/s. Such a critical velocity for hot-particle embedded or ignition slightly decreases as particle temperature increases. Minimum ignition temperature of these high-speed particles is 200 °C higher than that of near-static or with a low free-fall velocity, due to the shorter residence time and insufficient to produce a flammable mixture. Moreover, when the particle is neither too slow to bounce away nor too fast to get embedded, it will be partially embedded on the sample surface to burnout the fuel, posing the biggest fire hazard. It deepens our knowledge of the complex interaction between hot moving particles and insulation foam to reduce spotting fire risk for building façade.

The Seasonal Characterization and Temporal Evolution of Nitrogen, Phosphorus and Potassium in the Surface and Groundwater of an Agricultural Hydrographic Basin in the Midwestern Brazilian Savanna

The Brazilian savanna (Cerrado Biome) is one of the most important regions in the world in terms of food production, with the use of fertilizers based on nitrogen, phosphorus and potassium (NPK). When not applied properly, fertilizers can alter and affect water quality. The objective of this study was to evaluate the presence of these compounds in surface and groundwater in the Upper Jardim River Hydrographic Unit, Federal District, thus characterizing seasonal variations during the dry and rainy seasons in two periods. A total of 207 groundwater samples and 23 surface water samples were collected in the years 2014, 2015, 2019 and 2020. The parameters analyzed were pH and nitrate, nitrite, ammonium, phosphate and potassium ions. In groundwater samples, pH values were significantly higher and ion levels lower in samples collected during the early years (except for nitrate), and the ammonium concentrations were lower in the dry season than the rainy (in 2014 and 2019). In surface samples, total phosphorus levels were significantly higher in the rainy/2019 compared to the rainy/2020 season, while this tendency was inverted for potassium during the dry season. The use of NPK-based fertilizers has increased considerably in recent years in the region due to the expansion of the agricultural area, and although the results of the study show that concentrations in water are much lower than the maximum values allowed by Brazilian legislation, continuous monitoring is necessary to guarantee water quality.

Novel hybrid interference and atomic force microscopy

Abstract A novel hybrid microscope which combines an interference microscopic (IM) and an atomic force microscopic (AFM) measurement mode is introduced. It is realised by adding an AFM probe to an IM, where the AFM probe can be mechanically switched in or out of the beam path of the IM. When the AFM cantilever is out of the beam path, the system works in the IM measurement mode for noncontact and fast optical measurements. When the AFM cantilever is in the beam path, it works in the AFM measurement mode, where the AFM tip interacts with sample surfaces for measurements. The deformation of the AFM cantilever induced by the tip-sample interaction force is detected from interference fringes, which are formed by the interference of the light beam reflected from the backside of the AFM cantilever and a reference beam in the IM. This novel design has a high-level synergy of AFM and IM technologies and provides several promising application potentials. For instance, it can bring high-resolution AFM measurements whenever and wherever needed in IM measurements, thus, to complement the lateral resolution limits of IM; The AFM measurement mode can provide measurement results with higher topography fidelity, thus, to offer in-situ reference areal surface metrology for IM measurements. In the paper, design concept, realisation of a prototype instrument, and experimental results illustrating the performance of the prototype instrument are detailed. 

Electric field enhanced diffusion welding of alloy 617: Microstructural characteristics and mechanical properties

This study investigated the microstructural characteristics and mechanical behavior of diffusion welded nickel-based Alloy 617 obtained by electric field-assisted sintering (EFAS) using various parameters. The interfacial microstructure exhibited different characteristics including good grain boundary (GB) migration across the interface in the samples diffusion-welded at 1100 °C and a flat interface in the samples joined at 1000 °C and 1050 °C. The interface consisted of fine Al2O3 oxides, while precipitation of interfacial M23C6 carbides was not observed. Grain boundaries migrated across the Al2O3 oxides, leaving these oxides within the grains. Graded grain size was observed, with grain coarsening being more significant near the sample surface due to the temperature gradient induced by EFAS. Tensile testing revealed that the specimens fractured in the matrix away from the interface, indicting strong diffusion-welded joints. The peak tensile strength of 807 MPa was obtained in the samples welded at 1000 °C due to minimal grain growth. The materials obtained at 1100 °C exhibited reduced tensile strength but improved ductility. Strain maps revealed by digital image correlation showed alternating high and low strain segments in the samples produced at 1000 °C and 1050 °C, indicating that the flat interfaces with no GB migration were less ductile compared to the matrix. A greater strain uniformity was observed along the bond interfaces with improved GB migration. The hardness reduced near the sample surfaces due to enlarged grains induced by temperature gradient. This study demonstrates that GB migration and enhanced mechanical strength can be achieved in diffusion-welded Alloy 617.

Environmental bacterial load during surgical and ultrasound procedures in a Swedish small animal hospital

BackgroundEnvironmental bacteria in animal healthcare facilities may constitute a risk for healthcare-associated infections (HAI). Knowledge of the bacterial microflora composition and factors influencing the environmental bacterial load can support tailored interventions to lower the risk for HAI. The aims of this study were to: (1) quantify and identify environmental bacteria in one operating room (OR) and one ultrasound room (UR) in a small animal hospital, (2) compare the bacterial load to threshold values suggested for use in human healthcare facilities, (3) characterise the genetic relationship between selected bacterial species to assess clonal dissemination, and (4) investigate factors associated with bacterial load during surgery.Settle plates were used for passive air sampling and dip slides for surface sampling. Bacteria were identified by Matrix Assisted Laser Desorption—Time Of Flight. Antimicrobial susceptibility was determined by broth microdilution. Single nucleotide polymorphism-analysis was performed to identify genetically related isolates. Linear regression was performed to analyse associations between observed explanatory factors and bacterial load.ResultsThe bacterial load on settle plates and dip slides were low both in the OR and the UR, most of the samples were below threshold values suggested for use in human healthcare facilities. All settle plates sampled during surgery were below the threshold values suggested for use in human clean surgical procedures.Staphylococcus spp. and Micrococcus spp. were the dominating species. There was no indication of clonal relationship among the sequenced isolates. Bacteria carrying genes conveying resistance to disinfectants were revealed.Air change and compliance with hygiene routines were sufficient in the OR. No other factors possibly associated with the bacterial load were identified.ConclusionsThis study presents a generally low bacterial load in the studied OR and UR, indicating a low risk of transmission of infectious agents from the clinical environment. The results show that it is possible to achieve bacterial loads below threshold values suggested for use in human healthcare facilities in ORs in small animal hospitals and thus posing a reduced risk of HAI. Bacteria carrying genes conveying resistance to disinfectants indicates that resistant bacteria can persist in the clinical environment, with increased risk for HAI.

Oxidation kinetics of Ti6Al4V alloy deposited by wire arc additive manufacturing using argon gas as processing atmosphere

Ti6Al4V alloy is currently the most common metal alloy of the α+β phase type, its application is increasing as it has excellent properties at elevated temperatures. The main users of Ti6Al4V alloy are industries like of aerospace, naval, and biomedical; therefore, Ti6Al4V alloys one of the most studied material worldwide. One of the great advantages that Ti6Al4V alloy offers is the possibility of manufacturing components in situ by means of additive technologies.. Similar studies, in additive manufacturing, have reported the formation of titanium oxide on the surface of the material, followed by an oxygen-enriched region called "α-case". By means of thermogravimetric analysis, the oxidation effect on the surface of Ti6Al4V samples, obtained by wire arc additive manufacturing as well as samples from conventional manufacture, were studied. Argon gas, with an oxygen partial pressure of 1x10-5 atm, was used as the oxidation atmosphere within a range of 550°C to 950°C and oxidatión times of 60 min and 180 min. For the oxidation reaction, the kinetic analyses led to calculate the activation energy as 250 kJ/mol and 166 kJ/mol for the Ti6Al4V alloy processed by conventinal and additive manufacturing, respectively. The results of the of thermogravimetric analysis were fitted to a parabolic-type kinetic model. Furthemore, a mathematical model was proposed to predict the oxidation kinetics. The experimental data were fitted to the mathematical model in the range of 750 - 950°C for Ti6Al4V alloy by wire arc additive manufacturing. The oxidized microstructures were analized by optical and electronic microscopy finding α-case on the surface of the samples.

Decarbonization of siderite in the water-rich upper mantle

The aqueous fluids within subducted slabs have the potential to influence the form of carbonate presence and the carbon cycling process. Experiments were performed on resistive heating diamond anvil cell using siderite crystals and grains with water under conditions of pressure as high as 11.4 GPa and temperatures reaching up to 530 °C. These experiments aimed to simulate geological reactions that may occur within a depth range of 340 km in subducted slabs. Raman spectroscopy was employed to monitor the reactions and microscale phenomena within the sample chamber as pressure and temperature increase. The recovered products were analyzed using scanning electron microscopy and transmission electron microscopy. The results indicate that at 0.8 GPa and 108°C, a Fischer-Tropsch Type (FTT) reaction occurred on the sample surface, resulting in the formation of organic compound formaldehyde, followed by the observation of formic acid. At higher pressures and temperatures (3.5 GPa, 420°C), the formation of γ-Fe2O3 and γ-FeOOH was observed on the sample surface, accompanied by the release of CO2 and H2. Transmission electron microscope analysis of the quenched product powders indicated that the generated iron oxides were consistent with the phases observed at high pressure and temperature conditions. High pressure and temperature dissolution experiments of siderite in water reveal that carbon may be released into the mantle wedge entirely in the form of CO2 in warm subducted slabs and cold subducted slabs that subduct to depths of 75 km. The released CO2 participates in the carbon cycle of the island arc volcanic systems in the upper mantle at depths of 70–120 km and accelerates the transfer of subducted carbon to the Earth’s surface.

International inter-laboratory comparison of solar heat gain coefficient of building-integrated photovoltaic modules results of tests with or without power generation and tests with PV cell coverage ratios

The solar heat gain coefficient is one of the important indicators to evaluate the performance of the building envelope components. In a BIPV module, secondary heat transfer to the indoors is reduced, compared to conventional glazing, due to the shielding effect of the PV cells and energy conversion by power generation. There is a difference in SHGC between power-generating (MPP) and effectively open-circuit (OC) states. In this paper, in order to prepare a calorimetric SHGC evaluation methodology for BIPV modules, we documented the current status of the experimental calorimetric test methods and test apparatus adopted by test laboratories in four different countries and identified the differences. Differences between the test laboratories were found in to the applied test methods, solar simulator types, spectral distributions, DC or AC power supplies for the solar simulator, irradiation inhomogeneity on the light-receiving surface of the test sample, temperature conditions between the test chamber and the metering box, and surface heat transfer coefficients. Especially, the round-robin test results obtained in an interlaboratory comparison clarified that the differences in the characteristics of the Calorimetic Hot Box and the Heat Flux Metering methodologies with a cooled plate, the differences in irradiation inhomogeneity on the light-receiving surface of the test sample and differences in surface heat transfer coefficients significantly affect the SHGC evaluation for BIPV modules. In addition, for the SHGC test in the MPP state, it was confirmed that an absolute SHGC reduction effect of 0.02 to 0.04 was obtained for a PV laminate with 81 % cell coverage, for all SHGC test methods and test apparatus. Pe characterises the effect of converting part of the sunlight absorbed by the PV cell into electric power and extracting it from the BIPV module, reducing the heat re-radiated indoors compared to the OC state. Due to this mechanism, the reduction effect Pe always occurs during power generation, regardless of the type of PV cell technology and whether the PV cells are opaque or transparent. In addition, the decrease in SHGC for a given glazing configuration was found to be proportional to the increase in PV cell coverage ratio. SHGC tests with four different cell coverage ratios confirmed that the relationship between PV cell coverage ratio and SHGC is linear to a high degree of accuracy when no electric power is extracted (OC state), provided that the incident radiation is spatially homogeneous. The results obtained will be useful when proposing a calorimetric SHGC evaluation methodology for international standardization, as they document the differences due to a range of test facilities and testing conditions, differences caused by power generation and extraction, and the effect of varying PV cell coverage ratios. The insights gained were valuable in identifying which aspects of test methodology and boundary conditions must be specified with particular attention to detail when calorimetric testing standards are extended to explicitly address the SHGC determination of BIPV modules.

Investigation of the high temperature molten salt corrosion properties of Inconel625 alloy with Al

The Inconel625 (In625) alloy is one of the main materials in heat receivers of concentrated solar power (CSP). To further improve the corrosion resistance of heat receivers in molten salt, Al element that can form an oxide film was added into In625 alloy. In this study, In625 alloy with 3 wt% Al was prepared, and its corrosion resistance in carbonate (Li2CO3-Na2CO3-K2CO3) at 650 °C was studied. Results showed that a continuous dense oxide protective film (Al2O3 + LiAlO2) in surface of sample was formed by adding Al element during high temperature molten salt corrosion, which reduced the corrosion rate of In625 alloy. The corrosion rate of In625 alloy with 3 wt% Al corroded for 48 h and 120 h were 44 μm/year and 89 μm/year, respectively.

Evaluation of nanohardness, elastic modulus, and surface roughness of fluoride-releasing tooth colored restorative materials.

Recently, interest in tooth-colored fluoride-releasing dental materials has increased. Although physical and mechanical properties such as surface hardness, elastic modulus and surface roughness of the restorative materials have been investigated, the effect of different immersion media on these properties is still controversial. The aim of this study was to evaluate the nanohardness, elastic modulus and surface roughness of the fluoride release of tooth-colored restorative materials after immersion in acidic beverages. Prepared samples of three restorative materials (a highly viscous glass ionomer (EQUIA Forte; GC, Tokyo, Japan), a compomer (Dyract XP; Dentsply, Weybridge, UK), and a bioactive restorative material (Activa BioACTIVE; Pulpdent, MA, USA)) were randomly divided and immersed in distilled water, a cola and an orange juice for one week. The HYSITRON T1 950 TriboIndenter device (Hysitron, USA) with the Berkovich diamond indenter tip was used for all measurements. The nanohardness and elastic modulus of the samples were measured by applying a force of 6000 μN to five different points on the sample surface. Surface roughness measurements were evaluated on random samples by scanning five random 40 × 40 μm areas. The properties were measured at the initial and one week after immersion. The values of nanohardness, elastic modulus and surface roughness were tested for significant differences using a two-way analysis of variance (ANOVA) with repeated measures (p < 0.05). Tukey's honest significant difference (HSD) test was used for multiple comparisons. AB (Activa BioACTIVE) had the highest initial mean values for nanohardness. After post-immersion, the highest mean value for elastic modulus was the initial AB value. The lowest mean value for roughness of 100.36 nm was obtained for the initial DX (Dyract XP) measurement. Acidic beverages had a negative effect on the nanohardness, elastic modulus and surface roughness of the restorative materials.

Effects of air damping on quality factors of different probes in tapping mode atomic force microscopy

Abstract The AFM probe in tapping mode is a continuous process of energy dissipation, from moving away from to intermittent contact with the sample surfaces. At present, studies regarding the energy dissipation mechanism of this continuous process have only been reported sporadically, and there are no systematic explanations or experimental verifications of the energy dissipation mechanism in each stage of the continuous process. The quality factors can be used to characterize the energy dissipation in TM-AFM systems. In this study, the vibration model of the microcantilever beam was established, coupling the vibration and damping effects of the microcantilever beam. The quality factor of the vibrating microcantilever beam under damping was derived, and the air viscous damping when the probe is away from the sample and the air squeeze film damping when the probe is close to the sample were calculated. In addition, the mechanism of the damping effects of different shapes of probes at different tip–sample distances was analyzed. The accuracy of the theoretical simplified model was verified using both experimental and simulation methods. A clearer understanding of the kinetic characteristics and damping mechanism of the TM-AFM was achieved by examining the air damping dissipation mechanism of AFM probes in the tapping mode, which was very important for improving both the quality factor and the imaging quality of the TM-AFM system. This study’s research findings also provided theoretical references and experimental methods for the future study of the energy dissipation mechanism of micro-nano-electromechanical systems.