Oral health experience of individuals with eating disorders.

BACKGROUND: Evidence on how persons with and in remission from an eating disorder experience their oral health is limited. Dental treatment in Sweden today is often postponed until medical rehabilitation has been completed, but this carries risks. For the patient, the risk is severely impaired oral health and additional suffering, and for both society and the patient, higher costs than might have been necessary. METHODS: Ten female informants aged 21-51 years (mean age = 36.7, standard deviation 12.7) in remission from an eating disorder with a median duration of 12.5 (range 4-25) years of illness, were questioned in semi-structured interviews about their perceptions of oral health. All participants had been referred to a specialist dental clinic and needed oral rehabilitation. 10% of the patients had been diagnosed with anorexia nervosa and 90% with bulimia nervosa. All had been in remission from the eating disorder for at least one year. Transcripts of the interviews were analyzed with thematic analysis using an inductive approach. RESULTS: One overarching theme emerged from the analysis: dental damage persisted as a visible, lingering scar during remission of the eating disorder, reminiscent of the disease and its consequences. The three major themes identified were (1) Physical impact, (2) Psychological impact, and (3) Impact on daily living. The first major theme included erosive tooth wear and impaired oral function and aesthetics. Interviewees described the second as feelings of stigma, guilt, shame, anxiety, and worry, in particular concerning self-inflicted dental damage through self-induced vomiting. The last major theme covered avoidance strategies such as limiting smiling and laughing and minimizing social situations such as eating with others, pursuing a wanted career, and meeting a partner. CONCLUSIONS: The participants in this study expressed a profound negative impact on daily life and a two-fold burden of stigma of having suffered from both an eating disorder and poor oral health.

Research has established a link between eating disorders and poor oral health, such as erosive tooth wear. One knowledge gap, however, is how patients with and after recovery from an eating disorder experience their oral health. In Sweden, dental treatment is often postponed until after medical rehabilitation, but this carries risks. For the patient, the risk is severely impaired oral health and additional suffering, and for both society and the patient, higher costs than might have been necessary. The self-reports of the patients in their interviews witnessed to their suffering from two sources: the diagnosis of a mental disorder and poor oral health. Many reported feelings of stigma, shame, and guilt over, for example, self-induced vomiting, which was a predominant factor in dental damage. Tooth damage emerged as a visible, lingering scar that reminded the patient of the disease long after remission.

Evaluating the ability of the Wind Erosion Prediction System (WEPS) to simulate near-surface wind speeds in the Inland Pacific Northwest, USA.

Wind speed is one of the main control factors of wind erosion and dust emissions, which are major problems in arid and semiarid regions of the world. Accurately simulating highly precise hourly wind speeds is critical and cost-efficient for land management decisions with the goal of mitigating wind erosion and land degradation. The Wind Erosion Prediction System (WEPS) is a process-based, daily time-step model that simulates changes in the soil-vegetation-atmosphere. However, to date, relatively few studies have been conducted to test the ability of the WEPS in simulating hourly wind speeds. In this study, the performance of the WEPS model was tested in the Inland Pacific Northwest (iPNW), where wind erosion is a serious problem. Hourly wind speeds were observed and simulated by the WEPS at 13 meteorological stations from 2009 to 2018 using the WEPS hourly wind speed probability histogram. Owing to increasing wind shear, the model is not as precise in reproducing high wind speeds. The WEPS inadequately simulated the hourly wind speeds at six of the 13 stations, with a low index of agreement (d < 0.5). The complex regional topography may be one of the reasons for this lack of agreement, because the WEPS's performance of interpolation relies on spatial distances and surface complexity. Therefore, we validated the model using another wind-speed database to eliminate the impact of spatial interpolation. The performance of the WEPS was improved after removing the impact of spatial interpolation, producing d values > 0.5 at nine of the 13 stations. Our results suggest that the WEPS can accurately simulate hourly wind speeds and assess wind erosion in the absence of interpolation, whereas the model may be uncertain when invoking spatial interpolation. Some evidence also suggests that the model may have a tendency to underestimate observed hourly wind speeds. Pragmatically, this suggests that model users should consider the possibility that WEPS may underestimate wind erosion risk in the iPNW and plan implementation of conservation practices accordingly.

The use of Shewhart control charts when conducting cavitation studies to identify and eliminate non-random causes of variability.

One of the processes that accompanies the operation of various hydraulic systems is cavitation. This phenomenon is often accompanied by cavitation erosion, that is, the progressive loss of parent material from a solid surface due to continued exposure. The problem of obtaining accurate and reliable data when conducting cavitation studies remains relevant. This article discusses the adaptation of the use of Shewhart control charts when conducting cavitation studies, in order to determine the presence of non-random "special" causes of variability. A graph of changes in the process parameters over time was constructed to carry out statistical control of the stability of the process in order to determine the boundaries of the system variability of the process in order to predict the behavior of the process. As a result of the conducted research, recommendations were developed to increase the accuracy of output data when conducting cavitation studies. It has been confirmed that the use of control charts as a tool for quality control of laboratory measurements allows us to establish that the process has achieved a statistically controlled state, which allows us to maintain a high degree of stability and quality of the research being carried out. This method makes it possible:•to determine the presence of non-random "special" causes of variability during cavitation studies.•to quickly identify and eliminate the "special" causes of variability during cavitation studies.

Evaluation of soil erosion in the Changhua River Basin on Hainan Island based on the Chinese soil loss equation model.

Soil erosion is one of the most serious ecological and environmental problems facing southern China. The Changhua River Basin on Hainan Island is affected by soil erosion, which is causing the soil environment to become more fragile. Compared with the Revised Soil Erosion Equation (RUSLE), the Chinese Soil Loss Equation (CSLE) is based on a large amount of Chinese local data and research results, which more accurately reflect the actual situation of soil erosion in China and therefore have better accuracy and applicability in the Chinese region. By combining GIS and RS technologies, this study establishes the CSLE model of the Changhua River Basin, quantifies the soil erosion data via image elements from 2020 to 2022 using the spatial interpolation method, classifies the erosion intensity, and analyzes the spatial and temporal change characteristics of soil erosion. The statistical results show that, during the period from 2020 to 2022, the area of slight erosion in the Changhua River Basin increased by 553.25 km2, with a rate of change of 15.83 %, and the areas of mild erosion, moderate erosion, intense erosion, very intense erosion, and severe erosion decreased by 446.42 km2, 64.4 km2, 25.73 km2, 11.25 km2, and 5.45 km2, respectively, with rates of change of -31.05 %, -30.08 %, -36.58 %, -18.02 %, and -13.85 %, respectively. Slight erosion is defined as soil erosion less than the permissible soil loss and is not regarded as soil erosion, and the other erosion intensities showed a yearly decreasing trend, indicating that the soil erosion control was effective during this three-year period. In the work of soil and water conservation, it is especially necessary to determine the main factors influencing soil erosion and predict the areas that may be prone to such erosion. Therefore, on the basis of establishing a characteristic model using land use type, slope and soil type, and through superposition analysis, we obtained the spatial and temporal change characteristics of soil erosion. The research results are as follows: (1) slight erosion is mainly concentrated in forested areas, and forested land has a better capacity for soil and water conservation; (2) mild, moderate, and strong erosion mainly occur in cultivated areas and areas with a slope of 0-5°; (3) areas of built land and areas with a slope of 8°-15° are more prone to intense erosion, although they cover a smaller area; (4) when the slope is greater than 15°, the overlap range with the forest area is larger and the slope is no longer the main factor leading to soil erosion. Thus, it can be seen that forest land significantly reduces the impact of soil erosion. (5) among the different soil types, Technosol, Ferralsol and Fluvisol all have less than 55 per cent uneroded area and are generally less erosion-resistant, while Lixisol and Acrisol are relatively more susceptible to a high degree of erosion hazard (Extremely strong erosion, severe erosion).

Preventing dentin erosion with silver diamine fluoride and salivary pellicle: an in vitro study.

OBJECTIVES: To investigate the preventive and discoloring effects of a single and two weekly applications of 38% silver diamine fluoride (SDF) against dentin erosion. MATERIALS AND METHODS: 180 dentin blocks were divided into four groups. Group 1 (SDF2) received two weekly applications of 38% SDF. Group 2 (SDF1) received a single application of 38% SDF. Group 3 (SNF) received a daily application of stannous chloride/amine fluoride/sodium fluoride (standard of care for dental erosion). Group 4 (DW) received a daily application of deionized water. The treated blocks were subjected to a 14-day erosive challenge. Crystal characteristics, elemental composition, surface morphology, percentage of surface microhardness loss (%SMHL), surface loss, and color change (ΔE) were investigated using X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), scanning electron microscopy (SEM), hardness testing, profilometry, and digital spectrophotometry, respectively. RESULTS: XRD and EDS showed dentin surfaces had silver compounds in SDF2 and SDF1, and stannous chloride in SNF. SEM revealed less dentin demineralization with tubular occlusion in SDF2, SDF1, and SNF, but severe demineralization in DW. The %SMHL of SDF2, SDF1, SNF, and DW were 10.8 ± 2.1, 15.7 ± 2.1, 17.9 ± 2.1, and 28.7 ± 2.0 (SDF2 < SDF1 < SNF < DW, p < 0.05). Surface loss (µm) of SDF2, SDF1, SNF, and DW were 5.0 ± 0.6, 6.0 ± 0.6, 6.0 ± 0.7, and 9.0 ± 0.5 (SDF2 < SDF1 = SNF < DW, p < 0.001). ΔE of SDF2, SDF1, SNF, and DW were 26.0 ± 3.4, 12.1 ± 3.8, 6.9 ± 3.5, and 3.9 ± 3.6 (SDF2 > SDF1 > SNF = DW, p < 0.001). CONCLUSION: 38% SDF with two weekly applications provided better preventive effects against dentin erosion, but it might discolor dentin. CLINICAL RELEVANCE: The increased 38% SDF application showed a better anti-erosive potential against dentin erosion. However, SDF caused black staining on the dentin.

Orbital Cholesterol Granuloma : A Rare Case Report.

Cholesterol Granuloma is a rare lesion which occurs at locations like ear, peritoneum, lungs, breast etc. and formed due to interaction of Cholesterol and living tissue. But Cholesterol Granuloma occurring in the orbit is a very rare entity and so we authors present a case of Cholesterol Granuloma of the orbit.

Erosive Effect of Canned Juices and Soft Drinks on Surface Roughness of Restorative Materials Used in Pediatric Dentistry: An Ex Vivo Study.

Aim: To evaluate and compare the effect of fruit juice (orange) and cola drink (noncarbonated) on the surface texture of composite (3M ESPE Filtek Bulk Fill) and glass ionomer cement (GIC) (ChemFil Superior). Materials and methods: A total of eighty pellets each were prepared with composite (3M ESPE Filtek Bulk Fill) and GIC (ChemFil Superior) material using a brass mold with an inner diameter of 3 mm and a thickness of 3 mm according to the manufacturer's instructions. Around 10 pellets of each material were placed in airtight plastic containers. The baseline surface texture value was obtained by profilometer. An 8-day immersion regime was carried out according to Maupome et al. After the 8-day test period, pellets were reevaluated for surface texture final value. The values were statistically analyzed. Results: A statistically significant lower surface roughness of composite restorative material was observed when treated with high-concentration orange juice and medium-concentration. Conversely, a statistically significant lower surface roughness of GIC restorative material was observed when it was treated with the low-concentration group, high-concentration orange juice, and medium-concentration orange juice. Conclusion: The surface roughness patterns of restorative materials increased as the number of immersion regimes increased. How to cite this article: Vishwanathaiah S, Maganur PC, Khabrany HM, et al. Erosive Effect of Canned Juices and Soft Drinks on Surface Roughness of Restorative Materials Used in Pediatric Dentistry: An Ex Vivo Study. Int J Clin Pediatr Dent 2024;17(7):807-811.

Evaluation of effect of various drinks on tooth surface morphology under scanning electron microscope.

Aim and Objectives: The study aimed to evaluate and compare the effect of various beverages carbonated drinks, i.e., thumps up, fresh fruit juice (apple and pomegranate) and packaged fruit juice (apple and pomegranate) on tooth surface morphology under scanning electron microscope. Materials and Methods: Thirty recently extracted intact caries-free human permanent teeth were disinfected with 5.25% of sodium hypochlorite solution and autoclaved at 240°F, 20 psi pressure for 40 min. Each tooth was sectioned into 4 enamel sections yielding 120 sections which were embedded in resin using a prefabricated mold. Prepared samples were immersed as Group I - thumps up, Group II - fresh apple juice, Group III - packaged apple juice, Group IV - fresh pomegranate juice, Group V - packaged pomegranate juice, and Group VI - normal saline. Each immersion was done daily for 30 min over 14 days after which samples were scanned under scanning electron microscope (SEM). The data obtained were subjected to statistical analysis using Statistical Package for the Social Sciences (SPSS Version 23; Chicago Inc., IL, USA). Results: The highest surface roughness was noted in the fresh pomegranate and packaged pomegranate groups with a mean of 2.9000 ± 0.30779 followed by thumbs up group. The greatest mean of cracks was noted in thumbs up group with a mean of 2.500 ± 0.51299 which was significant at P = 0.000. The greatest mean of score was noted in thumbs up group with a mean of 2.3000 ± 0.65695 which was significant at P = 0.000. Conclusion: The present study demonstrated that all drinks were erosive in nature with thumps and pomegranate juice showing significantly higher erosiveness than apple juice (P < 0.01).

Effects of Dentifrices With Antierosive Potential on the Surface of Bovine Enamel Submitted to Acidic Beverage.

OBJECTIVES: To evaluate the effects of dentifrices containing sodium fluoride (NaF) combined with NovaMin (Sensodyne Repair & Protect-SRP), NaF combined with stannous fluoride (SnF2, Oral-B Pro-Gengiva-OBP), and amine fluoride (AmF, Colgate Elmex-ELM) on enamel subjected to simulated erosive cycling. MATERIALS AND METHODS: Bovine enamel-dentin discs (n = 10/group) were subjected to erosive cycling with orange juice (pH = 3.29, 5 min, 3x/day), artificial saliva (SA-2 h, 3x/day and overnight) and treated with dentifrice (2 min, 2x/day) or without treatment (CONT). Surface microhardness (SMH) was evaluated at baseline (T0), on the first (T1) and fifth (T5) days. SMH loss (%SHL) was calculated. Surface roughness (Ra, µm) was determined at T0 and T5. Morphology and mineral content were evaluated under scanning electron microscopy and energy-dispersive x-ray spectroscopy. Data were analyzed using ANOVA/Tukey or Bonferroni (α = 5%). RESULTS: No differences in %SHL were detected among groups at T1. At T5, OBP promoted %SHL, Ra, and ΔRa significantly lower than all the other groups (p < 0.05). All groups exhibited morphological changes in topography and similar Ca/P means before and after treatments. CONCLUSIONS: Dentifrice containing SnF2 minimized the negative effects on the SMH and Ra caused by exposure to orange juice after 5 days of simulated cycling. CLINICAL RELEVANCE: Patients who are more exposed to risk factors for dental erosion could benefit from the use of dentifrice containing SnF2.

Soil erodibility mapping using remote sensing and in situ soil data with random forest model in a mountainous catchment of Indian Himalayas.

Land degradation is accelerating in the Himalayan ecosystem, resulting in the loss of soil nutrients due to severe erosion. Soil erosion presents a significant environmental challenge, resulting in both on-site and off-site consequences, such as reduced soil productivity and siltation in reservoirs. Soil erodibility (K factor), an inherent soil property, determines the susceptibility of soils to erosion. Sampling across hilly and mountainous terrain pose challenges due to its complex landscape. Despite these challenges, it is essential to study K factor variations in different land use/land cover types to comprehend the threat of erosion. Digital soil mapping offers an opportunity to overcome this limitation by providing spatial predictions of soil properties. The objective of our study is to map the spatial distribution of soil erodibility using the Random Forest (RF) model, a machine learning method based on sampled in situ soil data and environmental covariates. We collected 556 surface soil samples from the mountainous catchment (Tehri dam catchment) using the stratified random sampling approach. The model performed satisfactorily in both training (r2 = 0.91; RMSE = 0.00185) and testing (r2 = 0.45; RMSE = 0.00318) phases. Subsequently, we generated a digital map with a resolution of 12.5 m to depict the distribution of the K factor. Our analysis revealed that key environmental variables influencing the prediction of the K factor included geology, mean NDVI, and climatic factors. The average K factor value was estimated at 0.0304 and ranging from 0.0251 to 0.0400 t ha h ha-1 MJ-1 mm-1. A higher K factor was observed in the barren land (0.0344) primarily located in the higher and trans-Himalayan region of seasonally snow-covered areas. These areas typically feature young soils with weak soil formation and unstable soil aggregates. Subsequently cropland/cultivated soils (0.0307) exhibited higher K factor values due to the breakdown of soil aggregates by ploughing activities and exposing carbon to decomposition. The average K factor value of evergreen (0.0294) and deciduous (0.0295) forests were the lowest compared to other land use/land cover types indicating the role of forests in resisting soil erosion. By assessing and predicting soil erodibility, land planners and farmers can implement erosion control measures to protect soil health, prevent sedimentation in water bodies, and sustain agricultural productivity in the Himalayas.

Use of double short tandem scleral tunnels for repairing eroded ahmed glaucoma valve tubes.

PURPOSE: To evaluate the effectiveness and safety of a method for repairing an eroded Ahmed glaucoma valve (AGV) tube using two short scleral tunnels made in tandem with a 22G needle instead of covering the eroded tube with another scleral graft. METHODS: From May 12, 2015, to July 27, 2019, we retrospectively reviewed eight patients at Ningbo Aier Eye Hospital who developed AGV tube erosion secondary to necrosis of their overlying conjunctiva and scleral grafts. This defect was repaired in all the patients using the double short tandem scleral tunnel technique, which involved the creation of double short tandem scleral tunnels made by a 22G needle. Two parallel-to-limbus scleral incisions were made 3 mm and 6 mm from the limbus first, then a curved 22G needle was inserted between the two scleral cuts to make one scleral tunnel, the other scleral tunnel was completed during the first surgery, inserted the tube into the two tunnels. The mean length of time between the AGV placement and the first erosion was 12.25 ± 6.36 months (3-24 months). The mean age of the patients was 65.50 ± 11.70 years (49-78 years). RESULTS: The surgical outcome was assessed in terms of the tectonic integrity of the conjunctiva over the follow-up period (12 months). There was no AGV tube erosion, scleral thinning, or ocular infection after a mean of 41.25 ± 26.54 months of follow-up in all eight patients. CONCLUSION: AGV tube erosion following shunt surgery can be successfully managed using the improved double short tandem scleral tunnel technique.

Dental Caries and Erosive Tooth Wear Among 12-Year-Old Hong Kong Children.

OBJECTIVE: This study is to investigate the dental caries, erosive tooth wear status, and oral health-related habits of 12-year-old Hong Kong children. METHODS: This cross-sectional survey recruited 12-year-old children using clustered random sampling from three main districts. The trained examiner examined the children's caries status using the criteria recommended by the World Health Organization and recorded their caries experience using the decayed, missing, and filled tooth (DMFT) index. The children's tooth wear status was determined using the Basic Erosive Wear Examination (BEWE) index. Their oral hygiene practice was collected using a self-administered questionnaire. RESULTS: We recruited 445 children and 396 children participated (response rate: 89%). Their mean DMFT was 0.29 ± 0.73. Seventy children (18%, 70/396) had caries experience (DMFT > 0) and they had 116 teeth suffered from caries. Among these 116 carious teeth, 75 teeth (65%, 75/116) were filled (FT), one tooth (1%, 1/116) was extracted (MT), and 40 teeth (34%, 40/116) were carious (DT). Five children had more than one decayed tooth (DT > 1), and one child had the highest number of decayed teeth (DT) at 4. BEWE results showed 284 (72%, 284/396) children had no erosive tooth wear (BEWE = 0). No child had severe erosive tooth wear (BEWE = 3). However, children consuming lemon tea or lemonade and vitamin C drinks 3 times a week or more showed significantly higher BEWE scores. Additionally, 380 (96%, 380/396) children brushed their teeth daily and 116 children (29%, 116/396) flossed their teeth. CONCLUSION: Most 12-year-old Hong Kong children had neither caries experience nor tooth wear, and their oral health-related habits were satisfactory. SIGNIFICANCE: This study updated the caries status of the permanent dentition of 12-year-old Hong Kong children. The information offers updated oral health data for the local, regional, and global authorities for planning effective public health programmes to improve the oral health of children.

PD-DEM hybrid modeling of leading edge erosion in wind turbine blades under controlled impact scenarios.

This paper addresses the critical issue of leading edge erosion (LEE) on modern wind turbine blades (WTBs) caused by solid particle impacts. LEE can harm the structural integrity and aerodynamic performance of WTBs, leading to reduced efficiency and increased maintenance costs. This study employs a novel particle-based approach called hybrid peridynamics-discrete element method (PD-DEM) to model the impact of solid particles on WTB leading edges and target material failure accurately. It effectively captures the through-thickness force absorption and the propagation of stresses within the leading edge coating system composed of composite laminates. The amount of mass removed and the mean displacement of the target material points can be reliably calculated using the current method. Through a series of tests, the research demonstrates the method's ability to predict impact force changes with varying particle size, velocity, impact angles and positions. Moreover, this study offers a significant improvement in erosion prediction capability and the development of design specifications. This work contributes to the advancement of WTB design and maintenance practices to mitigate LEE effectively.

Experimental study of liquid drop impact on granular medium: Drop spreading/splashing and particle ejection.

The impact of a liquid drop on a granular medium is a common phenomenon in nature and engineering. The possible splashing droplets and ejected particles could pose a risk of pathogen transmission if the water source or granular medium is contaminated. This work studies the liquid drop impact on the granular medium using high-speed photography and considers the effects of liquid properties, drop impact characteristics, and granular medium properties. Four flow regimes, including direct penetration, prompt splashing, spreading, and corona splashing, are observed and a regime map is created to identify their thresholds. The spreading regime can eject a large number of particles, and the corona splashing regime can produce splashing droplets in addition to the ejected particles. For the splashing droplets, their median diameters and velocities are in the ranges 0.11 to 0.21 and 0.15 to 0.37 of the diameter and velocity of the impact drop, and their median splashing angles range from 14° to 27°. Two particle ejection mechanisms are observed, falling squeeze and forward collision, driven by the collapsing and forward spreading of the liquid lamella, respectively. The particles ejected by the latter mechanism have larger ejection velocities, angles and distances from the impact center, which can facilitate their long-range transmission. In addition, the process of spreading and retracting of the lamella formed by the drop impact is also studied, and it is found that the maximum spreading diameter of the lamella is proportional to the crater diameter. These results improve the understanding of the phenomenon after the drop impact on the granular medium and the characteristics of the splashing droplets and ejected particles, contributing to the prediction and risk assessment of contaminated particle transmission.

Advances in Highly Ductile Concrete Research.

In recent years, high-ductility concrete (HDC) has gradually become popular in the construction industry because of its excellent ductility and crack resistance. Concrete itself is a kind of building material with poor tensile properties, and it is necessary to add a large number of steel bars to improve its tensile properties, which increases the construction cost of buildings. However, most of the research studies on high-ductility concrete are scattered. In this paper, the basic mechanical properties of high-ductility concrete and the effects of dry and wet cycles, freeze-thaw cycles, and salt erosion on the durability of high-ductility concrete are obtained by comprehensive analysis. The results show that the tensile properties of HDC can be significantly improved by adding appropriate fiber. When the volume fraction of steel fiber is 2.0%, the splitting tensile strength of concrete is increased by 98.3%. The crack width threshold of concrete chloride erosion is 55-80 µm, and when the crack width threshold is exceeded, the diffusion of CL-1 will be accelerated, and the HDC can control the crack within the threshold, thereby improving the durability of the concrete. Finally, the current research status of high-ductility concrete is analyzed, and the future development of high-ductility concrete is proposed.

Drying-Wetting Correlation Analysis of Chloride Transport Behavior and Mechanism in Calcium Sulphoaluminate Cement Concrete.

In response to rising CO2 emissions in the cement industry and the growing demand for durable offshore engineering materials, calcium sulphoaluminate (CSA) cement concrete, known for its lower carbon footprint and enhanced corrosion resistance compared to Ordinary Portland Cement (OPC), is increasingly important. However, the chloride transport behavior of CSA concrete in both laboratory and marine environments remains underexplored and controversial. Accordingly, the chloride ion transport behaviors and mechanisms of CSA concrete in laboratory-accelerated drying-wetting cyclic environments using NaCl solution and seawater, as well as in marine tidal environments, were characterized using the rapid chloride test (RCT), X-ray diffraction (XRD), mercury infiltration porosimetry (MIP), and thermogravimetric analysis (TGA). The results reveal that CSA concrete accumulates more chloride ions in NaCl solution than in seawater, with concentrations 2-3.5 times higher at the same water-cement ratio. Microscopic analysis indicates that calcium and sulfate ions present in seawater facilitate the regeneration of ettringite, thereby increasing the density of the surface pore structure. The hydration and repair mechanisms of CSA concrete under laboratory conditions closely resemble those in marine tidal conditions when exposed to seawater. Additionally, this study found that lower chloride ion concentrations and pH levels inhibit the formation of Friedel's salt. Therefore, laboratory experiments with seawater can effectively simulate CSA concrete's chloride transport properties in marine tidal environments, whereas NaCl solution does not accurately reflect actual marine conditions.

Ultrasonic Cavitation Erosion Behavior of GX40CrNiSi25-20 Cast Stainless Steel through Yb-YAG Surface Remelting.

Laser beam remelting is a relatively simple and highly effective technique for the physical modification of surfaces to improve resistance to cavitation erosion. In this study, we investigated the effect of laser remelting on the surface of cast stainless steel with 0.40% C, 25% Cr, 20% Ni, and 1.5% Si on cavitation erosion behavior in tap water. The investigation was conducted using a piezoceramic crystal vibrator apparatus. Base laser beam parameters were carefully selected to result in a defect-free surface (no porosity, material burn, cracks) with hardness capable of generating better resistance to cavitation erosion. The experimental results were compared with those of the reference material. Surface morphology and microstructure evolution after cavitation tests were analyzed using an optical metallographic microscope (OM), scanning electron microscope (SEM), and hardness tests to explore the mechanism of improving surface degradation resistance. The conducted research demonstrated that surfaces modified by laser remelting exhibit a 4.8-5.1 times greater increase in cavitation erosion resistance due to the homogenization of chemical composition and refinement of the microstructure, while maintaining the properties of the base material.

Research on the Erosion Law and Protective Measures of L360N Steel for Surface Pipelines Used in Shale Gas Extraction.

The erosion of surface pipelines induced by proppant flowback during shale gas production is significant. The surface pipelines in a shale gas field in the Sichuan Basin experienced perforation failures after only five months of service. To investigate the erosion features of L360N, coatings, and ceramics and optimize the selection of two protective materials, a gas-solid two-phase flow jet erosion experimental device was used to explore the erosion resistance of L360N, coatings, and ceramics under different impact velocities (15 m/s, 20 m/s, and 30 m/s). An energy dispersive spectroscope, a scanning electron microscope, and a laser confocal microscope were employed to analyze erosion morphologies. With the increase in flow velocity, the erosion depth and erosion rate of L360N, coating, and ceramic increased and peaked under an impact velocity of 30 m/s. The maximum erosion rate and maximum erosion depth of L360N were, respectively, 0.0350 mg/g and 37.5365 µm. Its primary material removal mechanism was the plowing of solid particles, and microcracks were distributed on the material surface under high flow velocities. The maximum erosion rate and maximum erosion depth of the coating were, respectively, 0.0217 mg/g and 18.9964 µm. The detachment of matrix caused by plowing is the main material removal mechanism. The maximum erosion rate and maximum erosion depth of ceramics were, respectively, 0.0108 mg/g and 12.4856 µm. The erosion mechanisms were micro-cutting and plowing. Under different particle impact velocities, different erosion morphologies were observed, but the primary erosion mechanism was the same. The erosion resistance of the ceramics was higher than that of the coatings. Therefore, ceramic lining materials could be used to protect the easily eroded parts, such as pipeline bends and tees, and reduce the failure rate by more than 93%. The study provided the data and theoretical basis for the theoretical study on oil and gas pipeline erosion and pipeline material selection.

Numerical Analysis of Cavitation Erosion in 316L Steel with CrN PVD Coating.

The erosion process of a 4 µm monolayer CrN coating deposited on 316L stainless steel due to cavitation was investigated using finite element analysis (FEA). To estimate load parameters from cavitation pit geometry resulting from high impact velocity and high strain rate, the explicit dynamic solver was employed. Water microjet impacts at velocities of 100, 200 and 500 m/s were simulated to recreate different cavitation erosion intensities observed in the experiment. The resulting damage characteristics were compared to previous studies on uncoated 316L steel. The relationship between impact velocity and postimpact geometry was examined. Simulations revealed that only impact at 500 m/s can exceed the maximum yield stress of the substrate without penetrating the coating. Subsequent impacts on the same zone deepen the impact pit and penetrate the coating, leading to direct substrate degradation. The influence of impact velocity on the coating degradation process is discussed.