Erosion Time Research Articles

Deep Radiostratigraphy Constraints Support the Presence of Persistent Wind Scouring Behavior for More Than 100 Ka in the East Antarctic Ice Sheet

The characterization of unconformities in wind-scoured areas of the Antarctic Ice Sheet (AIS) is important for the accurate estimation of Antarctic mass balance and can provide constraints on climate models. Here we apply radar data collected by the Chinese National Antarctic Research Expedition in the vicinity of the Dome A region in East Antarctica to trace six isochronous internal reflecting horizons. We identify 39 unconformities and map englacial stratigraphy 500 m below the ice surface through cross-validation among the data from several austral summer campaigns using different ice-penetrating radars. By estimating erosion time of buried unconformities using a one-dimensional ice flow model along local ice flowlines, we identify persistent wind-scoured zones on the scale of ten thousand years. We identify the earliest truncated climatic record through interpretation of the radar images and find that erosional activity can be dated back to approximately 100,000 years before present; all of the persistent wind scouring behaviors we present here began during the Last Interglacial- Last Glacial (128 ~ 10 ka B.P.). High-resolution records such as this that reveal englacial unconformities and englacial structural characteristics associated with erosion contribute to improved understanding of climate variability and ice sheet dynamics during the Late Pleistocene.

The therapeutic effects of basic fibroblast growth factor in nasal vestibulitis

ObjectiveTo observe the effect of topical application of recombinant human basic fibroblast growth factor (bFGF) in patients with nasal vestibulitis. MethodsOne hundred patients with nasal vestibulitis were randomly divided into two groups. Local application of bFGF + conventional medication was administered in the treatment group, while conventional medication was conducted in the control group. The healing of the nasal vestibular mucosa was observed. ResultsThe mucosal healing time was 18.3 ± 4.8 days in the treatment group and 36.2 ± 6.2 days in the control group. The data comparison revealed that the difference between groups was statistically significant (P < 0.01). The total effective rate was 98.0% in the treatment group and 90.0% in the control group, and the difference was not statistically significant between the two groups (P > 0.05). ConclusionTopical application of bFGF in patients with nasal vestibulitis could promote the growth of nasal mucosa, shorten the healing time of mucosal erosion, enhance the clinical treatment effect, and save a lot of treatment time for patients.

Dental Erosion Prevalence and Its Association With Obesity Among Children With and Without Special Healthcare Needs.

Dental erosion and childhood obesity are associated with a common risk factor, soft drink consumption. The present study aims to assess the prevalence of dental erosion and its association with obesity among children with and without special healthcare needs. A cross-sectional study was conducted on 1,200 school children (400 children with special needs (CSHN) and 800 children without special needs) in the age group of 6 to 16 years. Dental erosion was diagnosed according to World Health Organization (WHO) criteria. Body mass index (BMI; weight/height in kg/m2) was recorded for each child. The association of dental erosion and obesity was analysed using multivariate logistic regression analysis. A total of 331 (27.6%) children presented with dental erosion. Dental erosion prevalence among CSHN was 33.5% and among children without special needs was 24.6%. In the final fully adjusted model, children with obesity presented 2.32 times (95%CI 1.17-4.89, P = 0.001) higher odds ratio (OR) of having dental erosion than normal-weight children. Children who consumed soft drinks ≥ 1 time/day and 2-6 times a week presented with an OR of 2.65 (95%CI 1.23-5.21, P = 0.001) times of dental erosion. Children with chronic vomiting and bulimia presented with a 3.27 (95%CI 1.72-6.12, P = 0.001) times higher OR of dental erosion. Children with gastric reflux presented with a 3.21 (95%CI 1.52 - 5.86, P = 0.001) times higher OR of dental erosion. The prevalence of dental erosion was slightly higher for special needs children compared to children without special needs. The study outcome suggests that obesity, chronic vomiting, consumption of soft drinks, and gastric reflux are statistically significantly associated with dental erosion.

Analytical solution for time-dependent shoreline position response to the tectonic recovery process in the Sendai Plain, Japan, after the 2011 Great East Japan Earthquake

The 2011 Great East Japan Earthquake on March 11, 2011 triggered not only giant tsunami waves, but also caused significant land subsidence followed by land rise in the Sendai Coastal Plain areas. These impacts resulted in severe damages to the coastal infrastructure and induced coastal morphology changes along Japan's northeast coast. It was observed that the maximum downward deformation in the Sendai Coastal Plain was initially about - 0.3 m. Immediately after the earthquake, the land started to rise and it has already recovered back to its original position at some locations after 10 years. Thus, the high-quality measured beach profile data sets after the 2011 Tohoku Earthquake are valuable for exploring the impact of sea level rise (SLR) on shoreline position evolution, since the bed level change is inversely related to the sea level rise process. The data also provide a unique opportunity to evaluate the Equilibrium Beach Profile (EBP) theory and validate the Bruun concept. In the present study, a new simple analytical solution for time-dependent shoreline position response to the tectonic recovery process is developed based on the convolution method. The model results are able to predict the time-dependent shoreline evolution, including the maximum potential response and the characteristic erosion time scale at which the profile evolves towards a new equilibrium state.

Investigation on Ultrasonic Cavitation Erosion of Aluminum–Titanium Alloys in Sodium Chloride Solution

Two kinds of Ti-alloys, i.e., Al–5Ti and Al–10Ti alloys, were manufactured in this study, and their ultrasonic cavitation erosion behaviors in 3.5 wt.% NaCl solution were evaluated by the cumulative mass loss, scanning electronic micrograph, and three-dimensional morphology. The results show that mass loss and surface damage of the Al, Al–5Ti, and Al–10Ti alloys obviously increased with the increasing cavitation erosion time. Compared with the pure Al, the cavitation resistance of the Al–5Ti and Al–10Ti alloys was improved because of the presence of the TiAl3 phase. In addition, the synergistic effect between cavitation and corrosion of the Al–Ti alloy in 3.5 wt.% NaCl solution was studied according to the polarization curve of the moving electrode. The mass loss caused by the synergistic effect between cavitation erosion and corrosion accounted for a large percentage, 23.59%, indicating that corrosion has a critical impact on the cavitation erosion of the Al–Ti alloys. Compared with corrosion promoted by cavitation erosion, the cavitation erosion promoted by corrosion had a larger promoting effect.

Ion incidence angle dependent pattern formation at AZ 4562® photo resist by Ar+ ion beam erosion

Interactions between ion beams and polymers have great potential to tailor the properties of the polymer surface by modifying the morphology as well as the chemical composition. The application of a wide range of ion incidence angles (0° - 75°) for the erosion of the commercially available photoresist AZ 4562® revealed a multitude of nanopatterns as investigations using atomic force microscopy and scanning electron microscopy have shown. A sequence of angle-dependent patterns (nanoholes, ripples, facets) can be observed, which are already known from inorganic materials. Additionally, the variation of the erosion time (5 min – 60 min) showed an evolution of the nanopatterns. A changed composition of the polymer surface could be detected by means of X-ray photoelectron spectroscopy.

Erosion characteristics and failure mechanism of reservoir rocks under the synergistic effect of ultrasonic cavitation and micro-abrasives

Ultrasonic cavitation erosion of reservoir rocks in distilled water with and without SiO2 micro-abrasives (mean diameter 0.5 μm, mass concentration 1–7 wt%) are conducted. The erosion characteristics of eroded rocks are measured and analyzed. Both the area of cavitation damage zones and the surface roughness are increased when rocks are eroded in water-abrasive mixture. Compared with distilled water, the mass loss in 3 wt% water-abrasive mixture has improved by 69.66–104.23% (average 81.41%) for sandstone, 495.05–665.15% (average 557.38%) for shale, and 158.49–211.92% (average 188.16%) for granite during an erosion time of 5 ∼ 60 min. The promoted erosion can be explained by the synergistic effect of cavitation and micro-abrasives. The failure mechanisms are elucidated for different types of rocks. The erosion of reservoir rocks results from the peeling-off of mineral grains and the breakdown of large mineral crystals. Numerous micro-fractures and pores are produced in the surface of the eroded rocks, creating additional permeable channels for fluid flow. The results demonstrate that the presence of micro-abrasives can increase the ultrasonic cavitation erosion of reservoir rocks, indicating that the addition of micro-abrasives is feasible to enhance the performance of ultrasonic treatment for oil wells in petroleum industry.

Study on the erosion wear in pipe fittings

In the pipeline system for slurry, local erosion wear failure has become the main damage mechanism of pipe in the fracturing operations of oil-gas engineering. Computational Fluid Dynamics simulation is performed to determine the evolutionary process of erosion wear in tubing connector, which is the resistance of pipeline system, and a new way to predict the pipeline longevity is provided. Based on the Euler equation, solid particle concentration in the slurry and interphase momentum exchange are included in the liquid flow equations due to the influence of dense particle on slurry (slurry is a two-phase flow), and the particle trajectory were calculated in the Lagrange frame by analyzing the forces from the interaction of liquid and particle and particles impact. With the erosion damage model, the erosion rate/depth in the connector was calculated to reconstruct the mesh model of shoulder with 5 tori. Torus 1 is closest to axis while torus 5 is on the outmost wall of the connector. During the erosion event, greatest erosion and hence surface deformation occurs on tori 1 and 2, and this affects the surrounding flow and particle movement. After 10 hours of erosion, there was a dramatic drop in the maximum erosion rate, which illustrated a conservative prediction for pipeline service life if the initial erosion rate was used. An erosion experimental setup was also performed to identify the weight loss and erosion characteristic of the inner surface with erosion time of 55 hours. It was observed that the erosion simulations provided relative errors within 18% for erosion length and weight loss compared to the experimental values and a closed form equation for the erosion rate was proposed to predict the erosion life of tubing connector

An asymptomatic child of pre-perforation erosion after transcatheter closure of atrial septal defect

BackgroundFatal pericardial tamponade caused by aortic or atrial perforation due to erosion of atrial septal occluders has been reported previously, but the timing of erosion is uncertain, and the process is also unclear.Case presentationWe present a case of a 5-year-old boy with erosion of the aorta and atrium by the occluder not leading to perforation or pericardial tamponade because of early detection and timely surgery. A small amount of pericardial effusion may be the only manifestation of early erosion. This case firstly revealed the early process of device erosion in children.ConclusionsAn absent aortic rim may be a higher risk factor for erosion than oversized device for a child, and it is wise to choose a relatively small occluder or change to surgery. This may be helpful for preventing and treating serious complications caused by erosion of the occluder.

Experimental study on stiffness degradation and monotonic response of reconstituted volcanic ash induced by internal erosion

Volcanic ash soils are a common geological body in earthquake prone regions, and they are widely used as construction materials. The present study discusses the contribution of initial density, stress state and seepage time on seepage-induced internal instability, stiffness degradation, and monotonic response of volcanic ash collected from Satozuka, Japan. Reconstituted specimens are tested using an erosion triaxial apparatus. The results exhibit that the rate of erosion is influenced by initial density, stress state and hydraulic gradient. The mercury intrusion porosimeter tests are conducted to explore the distribution of constriction sizes after erosion. Post-erosion stress-strain responses are also affected by the stress state during erosion, initial density and seepage time. Particularly, internal erosion affects the dilatancy response of relatively loose specimens and has an impact on the critical state line, brittleness, and peak strength. Further, the maximum shear modulus of eroded soil is found to be greater than that of non-eroded soil, mainly due to the particle rearrangement and removal of fines. However, a sharp reduction in stiffness during monotonic shearing is maybe evidence that temporary reinforced soil packing collapses at a large strain. This indicates that the elastic yield surface has expanded for eroded soils.

Interfacial characterization and erosive wear performance of zirconia toughened alumina ceramics particles reinforced high chromium white cast irons composites

To investigate the erosive wear-corrosion behavior of ZTAP ceramic reinforced high chromium cast iron matrix composites in two types of sand at various rotational speeds, the ZTAP/Fe composites were fabricated. The interface characteristics, erosion wear-corrosion and erosive wear mechanism have been investigated in a slurry condition at various erosion rotational speeds. The chemical composition of the matrix material was determined using a spark spectrometer. SEM, TEM, 3D laser scanning microscope and AFM were used to analyze the microstructure characteristics and worn surface morphology of the composites. Furthermore, the wear loss rate and relative erosive wear resistance of ZTAP/Fe composites and Cr15 standard specimen measurements were conducted. The results showed that the interface between the ZTAP ceramics and the Cr15 matrix exhibits a continuous transition layer without visible defects and close contacts. In the case of SiO2 and SiC abrasive sand, the wear rate of ZTAP/Fe composites and Cr15 standard specimens increases with erosion time. The wear rate of ZTAP/Fe against SiO2 sand is lower than that of against SiC sand. ZTAP/Fe composites was found to exhibit a better corrosion resistance property than that of Cr15 standard specimens.

Experimental Study on the Effect of Hardness on the Erosion Resistance of Coatings and Rubber for Hydropower Applications

Abstract Polymeric coatings are used to protect concrete hydropower structures from damage by particle-laden, fast-moving water. In this research, a new experimental method is proposed to simulate this tribosystem. Test materials are submerged in an agitated vessel containing basalt particles and abraded for a fixed time. This paper describes the use of this test to screen polyurea coatings of various types of hardness. The use of such test on rubbers is also described. Results present that the wear process of the polyurea is stable and the wear loss is linear with the erosion time. When the hardness of the polyurea or seal rubber increases, the erosion resistance indicates a downward trend and the surface becomes smooth from rough. A polyurea hardness of Shore D30 and a seal rubber hardness of Shore A70 produce the best slurry erosion resistance. The erosion resistance of the polyurea is much better than that of the high-performance concrete. If the wear thickness is regarded as the evaluation indicator, then the erosion resistance of the polyurea of Shore D30 is approximately 60 times more than that of the high-performance concrete.

Response and Deterioration Mechanism of Bitumen under Acid Rain Erosion.

Acid rain as an important environmental issue has a negative impact on bitumen performance, thereby shortening the service life of asphalt pavements. Thus, this research aims to investigate the response of bitumen to acid rain and its deterioration mechanism. For this purpose, the simulated acid rain was prepared to erode neat bitumen and short-term aged bitumen. The hydrogen ion concentration of the acid rain, and the morphological, physical, chemical, and rheological properties of the bitumen were evaluated by means of a pH meter, scanning electron microscopy, physical tests, Fourier transform infrared radiation with attenuated total reflectance, and dynamic shear rheometer. The results showed that bitumen properties were severely affected by acid rain, and the changes in bitumen properties were highly related to the erosion time, leading to a reduction in pH value by 0.2 of residual acid rain, rougher bitumen surface, and stiffer bitumen with more oxygen-containing functional groups and fewer carbonyl acid groups (around 10% decrement) after 90 days erosion. These changes contributed to two deterioration mechanisms: oxidation and dissolution of carbonyl acid. Oxidation and dissolution are, respectively, the dominant actions for neat bitumen and aged bitumen during the erosion process, which eventually leads to various responses to acid rain.

English

In regulated and targeted drug distribution, biodegradable polymers have played a significant portion. Poly-lactic-co-glycolic acid (PLGA) has been an important desirable polymer in tissue engineering to meet a new drug delivery system. PLGAs, show a broad spectrum of erosion cycles and have tuning mechanical characteristics. Poly-lactic-co-glycolic acid (PLGA) has been the most successful polymeric biomaterial for use in controlled drug delivery systems. PLGA has been extensively studied, in particular, in the production of equipment for controlled distribution in industrial and research applications of small molecules, protein, and other macromolecules. PLGA is biocompatible and biodegradable, exhibits a wide range of erosion times, has tunable mechanical properties and most importantly, is a FDA approved polymer. PLGA has many properties such as controlled and sustained release, low cancerinducing, long-standing biomedical applications, biocompatibility with tissues and cells, and prolonged residence time. It is otherwise called as 'Smart Polymer' because improvements are fragile to conduct PLGA that has been widely examined in industrial and academic applications to produce instruments for the target delivery of tiny molecular drugs, proteins, and other large molecules. An introduction about the chemistry, physicochemical properties, manufacturing techniques of the devices, toxicity, and the reason influencing their decrease and release of the drug was given in the present study. Mathematical modelling is a useful tool for identifying, characterizing, and predicting the mechanisms of controlled release. Mathematical modelling applied against the target from PLGA – the devices has been clarified by discussing in the review, by explaining the underlying mathematical models and how this is used. KEY WORDS Biodegradable Polymers, PLGA, Biodegradability, Macromolecules

Predicting the impact of land-use changes on soil erosion rates in the three small sub-catchments of Larona Catchment

This study aims to predict the amount of soil erosion in the three sub-catchments of Larona Catchment, which are Larona, Balambano, and Karebbe sub-catchments. The USLE method is used to predict soil erosion rates in 2009 and 2015 by using rainfall data of 13 rainfall stations, soil maps, DEM data for generating LS factors, Landsat 8 Imageries, and land use maps create CP factors. Four thematic maps (R, K, LS, and CP) were overlaid and clustered using ArcGIS 10.4. The results show that soil erosion rates in the period of 6 years have changed in the three sub-catchments. The erosion rate in Larona and Karebbe sub-catchment slightly increased from 43,092 tons to 50,982 and 155,005 tons to 224,757 tons, respectively, from 2009 to 2015. In the Balambano sub-catchment, the value of erosion rate increased dramatically during the period. Total erosion this sub-catchment in 2015 became 5 to 7 times of the total erosion in 2009. The change of land use caused the increased sediment yields in the three cascade-reservoirs in Larona Catchment and land cover, mostly the result of increasing agricultural activities and not due to mining development.

Zero deforestation in the Amazon: The Soy Moratorium and global forest governance

AbstractDeforestation in the Brazilian Amazon has recently increased, and one of the main drivers is the expansion of soy production for international markets. The Soy Moratorium (SM) is a market‐based, zero‐deforestation commitment banning traders from purchasing soy produced in the Amazon’s deforested land after July 2008. Combined with public conservation policies, the SM has contributed to a decrease in the direct conversion of forests for soy production. This article considers the SM’s links with global forest protection, revealing that measures to protect forests at local levels are consistent with global trends. Specifically, the article suggests that the SM exemplifies the growing importance of non‐State actors in global environmental protection, the close relationship between forest protection and climate change goals, and the reconciliation of environmental practices with economic growth. As such, the article helps explain how the SM advance global forest governance at a time of erosion of environmental protection.

Evaluating the effect of drill string rotation and change in drilling fluid viscosity on hole cleaning

The most primitive hole challenge is cleaning the hole, which is more severe in deviated wells. This problem was tackled in this research via experimental analysis and graphical evaluations. To hit this aim, rheological parameters were experimentally obtained, and Noah’s model was used to determine cutting bed erosion time at varying heights. A graphical evaluation was done using a case study of deviated wells X and Y from a Niger Delta field. The result shows that low-viscosity fluid, KCL polymer fluid and high-viscosity fluid take 124, 283 and 342 min, respectively, to erode equal height as graphical evaluation shows that hole cleaning will grow complex on deviation. Thus, the deduction from this work in reducing non-productive time (NPT) related to hole cleaning in drilling operation is first, prior to making a trip, pumping low-viscosity fluid at a high flow rate. Secondly, during drilling, increasing drill string rotation in deviated wells can effectively stir the cuttings into the annulus above the low session of the hole.

Lateral shoreline erosion and shore-proximal sediment deposition on a coastal marsh from seasonal, storm and decadal measurements

The persistence of coastal marsh is dependent on its ability to maintain elevation relative to sea level, particularly for marshes experiencing high rates of shoreline erosion due to wave-attack, storms, and sea level rise. Sediments eroded at the marsh edge are either delivered onto the marsh platform or into the estuary, the latter resulting in a net loss of marsh sediments and soil carbon. Knowledge on the timing, pattern, and quantity of sediment deposition versus shoreline erosion along the marsh-estuary interface is critical for evaluating the overall health and vulnerability of coastal marshes to future scenarios of sea level rise and for estimating sediment budgets. Here we examined marsh shoreline erosion and sediment deposition for marsh sites experiencing a range of shoreline erosion rates and different levels of wind-wave exposure within the Grand Bay National Estuarine Research Reserve and Wildlife Refuge in Mississippi. We developed a method for calculating an erosion-deposition sediment budget using marsh elevation profiles, shoreline erosion rate, and sediment deposition measurements. Sediment budgets were calculated at four sites with varying shoreline erosion rates. Much of the sediment eroded at the marsh edge can be accounted for as marsh platform deposition, except at the most erosive site, suggesting a possible erosion threshold where eroded sediment mass is greater than platform deposition. Consistent with other studies of marsh creeks, sediment delivery to the marsh platform appears to be largely driven by wave climate. These data suggest that for erosive bay-estuarine shorelines, sediment delivered into the marsh is largely concentrated near the marsh shoreline, although shoreline erosion does not always result in a net loss of sediments from the marsh system in either decadal or annual assessments.

Analysis of plume–lunar surface interaction and soil erosion during the Chang’E-4 landing process

When the lander approaches the lunar surface, the rocket exhaust will erode the surface and eject massive high-speed dust, which could damage the payloads on the lander or interfere with subsequent surface operations. This process also provides a unique opportunity to study the plume–dust interaction and the wind erosion on the surface of airless body such as the Moon. Previously, limited knowledge was obtained from Apollo landing images and a simplified erosion model is built to study the erosion process. With high-quality data acquired in the landing process of Chang’E-4 (CE-4) mission, for the first time, we aim to quantify the dust ejection angle and erosion depth for a low-thrust lander, test the effectiveness of the current erosion model, and provide reference information for future landing missions. We use image measurement methods to extract key parameters such as dust ejection angle and erosion depth from the landing image of CE-4. For comparison with the observation, we also employ an erosion model to estimate the erosion thickness. The dust appears at about 7 s before the lander touch the surface, with a height of 13 m above the surface. When the nozzle altitude was about 0.6 m, the dust ejection angle is measured to be above 7°, while the dust ejection angle calculated by the particle trajectory method is less than 4.3°for particle sizes smaller than 1 mm. For the first time, an average erosion depth of 0.7 cm is measured between 1.12 m and 2 m from the nozzle centerline for a low-thrust lander. The measurement corresponds to an erosion time duration from 1.1 s before landing to 0.4 s after landing. The measured erosion range using CE-4 data is much larger than the estimated erosion radius given by the previous erosion model. It indicates that the dust’s angular distribution, local topography of the landing area, and other factors are important in improving the precision of the erosion model.

The effects of process parameters on the rock-breaking efficiency of multi-nozzle jet

This paper examines the effect of multi-nozzle bit on sandstone specimens by means of numerical simulation and experiment, and the rationality is verified. Numerically, the effects of jets with different diameters and angles on rock were simulated by using LS-DYNA, and the rock-breaking shapes of jets with different angles are analyzed. Experimentally, the effects of jet pressure, impact standoff distance, erosion time and rotation speed on the crushing effect of sandstone are studied by building an experimental platform of high-pressure water jet impacting sandstone. The research shows that the rock-breaking depth decreases with the increase of the inclination angle, and the rock-breaking width increases with the increase of the inclination angle. Through comparing the rock-breaking depth and width, the reasonable structure of nozzle with diameter of 1.0 mm and inclination angle of 20°, 30° and 60° are determined. The volume of broken rock gradually increases with the increase of jet pressure, and the numerical simulation results are consistent with the experimental results. Meanwhile, the rock-breaking efficiency gradually decreases with the increase of the standoff distance, and gradually increases with the increase of the erosion time, and finally stabilizes. Through experiments, it is found that the rock-breaking depth, width and volume decrease with the increase of the rotation speed. The optimal standoff distance for the rock-breaking efficiency is 3 mm, the erosion time is no less than 60 s, and the critical rotation speed is 300 rpm.