BACKGROUND Although chronic erosive gastritis(CEG)is common,its clinical characteristics have not been fully elucidated.The lack of consensus regarding its treatment has resulted in varied treatment regimens.AIM To ex...BACKGROUND Although chronic erosive gastritis(CEG)is common,its clinical characteristics have not been fully elucidated.The lack of consensus regarding its treatment has resulted in varied treatment regimens.AIM To explore the clinical characteristics,treatment patterns,and short-term outcomes in CEG patients in China.METHODS We recruited patients with chronic non-atrophic or mild-to-moderate atrophic gastritis with erosion based on endoscopy and pathology.Patients and treating physicians completed a questionnaire regarding history,endoscopic findings,and treatment plans as well as a follow-up questionnaire to investigate changes in symptoms after 4 wk of treatment.RESULTS Three thousand five hundred sixty-three patients from 42 centers across 24 cities in China were included.Epigastric pain(68.0%),abdominal distension(62.6%),and postprandial fullness(47.5%)were the most common presenting symptoms.Gastritis was classified as chronic non-atrophic in 69.9%of patients.Among those with erosive lesions,72.1%of patients had lesions in the antrum,51.0%had multiple lesions,and 67.3%had superficial flat lesions.In patients with epigastric pain,the combination of a mucosal protective agent(MPA)and proton pump inhibitor was more effective.For those with postprandial fullness,acid regurgitation,early satiety,or nausea,a MPA appeared more promising.CONCLUSION CEG is a multifactorial disease which is common in Asian patients and has non-specific symptoms.Gastroscopy may play a major role in its detection and diagnosis.Treatment should be individualized based on symptom profile.展开更多
The China Loess Plateau is subjected to severe soil erosion triggered by intense rainfall,resulting in significant harm and losses to both human society and the natural surroundings.In this study,a novel technique for...The China Loess Plateau is subjected to severe soil erosion triggered by intense rainfall,resulting in significant harm and losses to both human society and the natural surroundings.In this study,a novel technique for managing loess erosion is introduced,which involves the utilization of a combined polymer SH and ryegrass.A comprehensive series of tests were undertaken,including rainfall erosion tests,disintegration experiments,and scanning electron microscopy examinations,to assess the accumulative sediment yield(ASY),disintegration ratio,and microstructural features of both untreated and treated loess samples.The results showed a significant reduction in ASY with increased dry density of untreated loess.Furthermore,the combined technique effectively controlled erosion,limiting ASY to 266.2 g/cm^(2)in 60 minutes.This was approximately one-sixth,one-ninth,and one-fifteenth of the ASY in SH-treated loess(L-SH),ryegrass-treated loess(L-R),and untreated loess,respectively.It resisted disintegration better than ryegrass alone but slightly less than SH.This improvement was due to the combined effect of SH and ryegrass,which reduced raindrop impact,improved loess microstructure,and boosted ryegrass growth.The innovative technique holds the potential to be applied as a field-scale technique in the Loess Plateau region of China.展开更多
Erosion wear is a common failure mode in the oil and gas industry.In the hydraulic fracturing,the fracturing pipes are not only in high-pressure working environment,but also suffer from the impact of the high-speed so...Erosion wear is a common failure mode in the oil and gas industry.In the hydraulic fracturing,the fracturing pipes are not only in high-pressure working environment,but also suffer from the impact of the high-speed solid particles in the fracturing fluid.Beneath such complex conditions,the vulnerable components of the pipe system are prone to perforation or even burst accidents,which has become one of the most serious risks at the fracturing site.Unfortunately,it is not yet fully understood the erosion mechanism of pipe steel for hydraulic fracturing.Therefore,this article provides a detailed analysis of the erosion behavior of fracturing pipes under complex working conditions based on experiments and numerical simulations.Firstly,we conducted erosion experiments on AISI 4135 steel for fracturing pipes to investigate the erosion characteristics of the material.The effects of impact angle,flow velocity and applied stress on erosion wear were comprehensively considered.Then a particle impact dynamic model of erosion wear was developed based on the experimental parameters,and the evolution process of particle erosion under different impact angles,impact velocities and applied stress was analyzed.By combining the erosion characteristics,the micro-structure of the eroded area,and the micro-mechanics of erosion damage,the erosion mechanism of pipe steel under fracturing conditions was studied in detail for the first time.Under high-pressure operating conditions,it was demonstrated through experiments and numerical simulations that the size of the micro-defects in the eroded area increased as the applied stress increased,resulting in more severe erosion wear of fracturing pipes.展开更多
For the safety of railroad operations,sand barriers are utilized to mitigate wind-sand disaster effects.These disasters,characterized by multi-directional wind patterns,result in diverse angles among the barriers.In t...For the safety of railroad operations,sand barriers are utilized to mitigate wind-sand disaster effects.These disasters,characterized by multi-directional wind patterns,result in diverse angles among the barriers.In this study,using numerical simulations,we examined the behavior of High Density Polyethylene(HDPE)sheet sand barriers under different wind angles,focusing on flow field distribution,windproof efficiency,and sedimentation erosion dynamics.This study discovered that at a steady wind speed,airflow velocity varies as the angle between the airflow and the HDPE barrier changes.Specifically,a 90°angle results in the widest low-speed airflow area on the barrier’s downwind side.If the airflow is not perpendicular to the barrier,it prompts a lateral airflow movement which decreases as the angle expands.The windproof efficiency correlates directly with this angle but inversely with the wind’s speed.Notably,with a wind angle of 90°,wind speed drops by 81%.The minimum wind speed is found at 5.1H(the sand barrier height)on the barrier’s downwind side.As the angle grows,the barrier’s windproof efficiency improves,extending its protective reach.Sedimentation is most prominent on the barrier’s downwind side,as the wind angle shifts from 30°to 90°,the sand sedimentation area on the barrier’s downwind side enlarges by 14.8H.As the angle grows,sedimentation intensifies,eventually overtakes the forward erosion and enlarges the sedimentation area.展开更多
The majority of the projectiles used in the hypersonic penetration study are solid flat-nosed cylindrical projectiles with a diameter of less than 20 mm.This study aims to fill the gap in the experimental and analytic...The majority of the projectiles used in the hypersonic penetration study are solid flat-nosed cylindrical projectiles with a diameter of less than 20 mm.This study aims to fill the gap in the experimental and analytical study of the evolution of the nose shape of larger hollow projectiles under hypersonic penetration.In the hypersonic penetration test,eight ogive-nose AerMet100 steel projectiles with a diameter of 40 mm were launched to hit concrete targets with impact velocities that ranged from 1351 to 1877 m/s.Severe erosion of the projectiles was observed during high-speed penetration of heterogeneous targets,and apparent localized mushrooming occurred in the front nose of recovered projectiles.By examining the damage to projectiles,a linear relationship was found between the relative length reduction rate and the initial kinetic energy of projectiles in different penetration tests.Furthermore,microscopic analysis revealed the forming mechanism of the localized mushrooming phenomenon for eroding penetration,i.e.,material spall erosion abrasion mechanism,material flow and redistribution abrasion mechanism and localized radial upsetting deformation mechanism.Finally,a model of highspeed penetration that included erosion was established on the basis of a model of the evolution of the projectile nose that considers radial upsetting;the model was validated by test data from the literature and the present study.Depending upon the impact velocity,v0,the projectile nose may behave as undistorted,radially distorted or hemispherical.Due to the effects of abrasion of the projectile and enhancement of radial upsetting on the duration and amplitude of the secondary rising segment in the pulse shape of projectile deceleration,the predicted DOP had an upper limit.展开更多
Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of veg...Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of vegetated land into agricultural land and built-up area,stand out as primary contributors to soil erosion.The present study investigated the risk of soil erosion in the Irga watershed located on the eastern fringe of the Chota Nagpur Plateau in Jharkhand,India,which is dominated by sandy loam and sandy clay loam soil with low soil organic carbon(SOC)content.The study used the Revised Universal Soil Loss Equation(RUSLE)and Geographical Information System(GIS)technique to determine the rate of soil erosion.The five parameters(rainfall-runoff erosivity(R)factor,soil erodibility(K)factor,slope length and steepness(LS)factor,cover-management(C)factor,and support practice(P)factor)of the RUSLE were applied to present a more accurate distribution characteristic of soil erosion in the Irga watershed.The result shows that the R factor is positively correlated with rainfall and follows the same distribution pattern as the rainfall.The K factor values in the northern part of the study area are relatively low,while they are relatively high in the southern part.The mean value of the LS factor is 2.74,which is low due to the flat terrain of the Irga watershed.There is a negative linear correlation between Normalized Difference Vegetation Index(NDVI)and the C factor,and the high values of the C factor are observed in places with low NDVI.The mean value of the P factor is 0.210,with a range from 0.000 to 1.000.After calculating all parameters,we obtained the average soil erosion rate of 1.43 t/(hm^(2)•a),with the highest rate reaching as high as 32.71 t/(hm^(2)•a).Therefore,the study area faces a low risk of soil erosion.However,preventative measures are essential to avoid future damage to productive and constructive activities caused by soil erosion.This study also identifies the spatial distribution of soil erosion rate,which will help policy-makers to implement targeted soil erosion control measures.展开更多
Loess internal erosion caused by preferential flow often leads to serious loess ground collapse,shallow loess landslides,and other geological disasters.However,there is a lack of quantitative evaluation of the interna...Loess internal erosion caused by preferential flow often leads to serious loess ground collapse,shallow loess landslides,and other geological disasters.However,there is a lack of quantitative evaluation of the internal erodibility of undisturbed loess under the action of preferential flow,and little is known about the correlation between the internal erodibility of loess and its microstructure.In this study,we carried out a series of hole erosion tests(HET)on undisturbed loess samples from 4 typical locations on China's Loess Plateau.The internal erodibility of loess was quantitatively evaluated through an improved HET method,and its association with initial water content,clay content,and initial water head difference was investigated.On the microscopic scale,the microstructure of loess with different clay content was measured by scanning electron microscopy(SEM).The correlation between pore and particle microstructure parameters and loess internal erosion parameters was established based on grey correlation theory.When the initial water content increased from 10%to 36%,the erodibility index increased from 1 to 2.5.When the clay content increased from 8%to 27.95%,the erodibility index increased 3.5 times.The increase of initial water head difference has a positive linear effect on the internal erodibility of loess.The microstructure analysis shows that with the increase of clay content,the microstructure of undisturbed loess changes from a mosaic structure to a cementation structure,which creates favourable conditions for controlling the internal erosion of loess.Through grey correlation analysis,it has been determined that the microstructure of undisturbed loess has a significant correlation with the critical shear stress,and the loess microstructure morphology strongly correlates with the erosion rate.Under normal circumstances,the higher the clay content,the better the erosion resistance,the better the mechanical stability,and the easier to form a stable cave in loess.This study can provide a reference for revealing the cave formation mechanism in the loess area in the future.展开更多
Soil pedestals have long been used as qualitative indicators of soil splash erosion.In rangelands,plant-capped pedestals,generally grass tussocks,have also been used to quantitatively estimate soil loss since the firs...Soil pedestals have long been used as qualitative indicators of soil splash erosion.In rangelands,plant-capped pedestals,generally grass tussocks,have also been used to quantitatively estimate soil loss since the first half of the twentieth century.In agricultural lands,forests,and bad-lands,stone-capped pedestals have been used as qualitative and semi-quantitative indicators of active,'extreme'erosion.Little work has been reported on using capstone pedestal data for quantifying soil loss.We postulate that three distinct capstone pedestal types may be present in any given location and that a detailed analysis of a pedestal height histogram may be used to recognize their populations.This analysis can subsequently inform if soil loss can be reliably estimated and if so,which of the existing methods using pedestal height data will provide more accurate results.The three proposed capstone pedestal types are:(1)neo-pedestals formed underneath surface stones exposed by(partial)removal of the soil surface cover;(2)endo-pedestals formed underneath stones that were buried in the soil but have been exposed by erosion;and(3)phoenix-pedestals formed underneath stones from collapsed pedestals.In the pedestal height histogram of any given location,a skew to smaller heights may indicate the existence of endo-and/or phoenix-pedestals,which may be revealed as a bi-(or tri)modal distribution when using a smaller bin size.This concept was applied to a case study where soil loss had been monitored for control plots and mulched plots during a 5-year period following wildfire in a eucalypt plantation.We measured pedestal heights and used methods to quantitatively assess soil loss from soil pedestal data in the available literature.Soil pedestal data at the end of the 5-year period under or overestimated soil loss in the control treatment,with results ranging from 60 to 115%of measured soil loss,depending on the method.It is postulated that phoenix-and endo-pedestals may be a driving factor behind the observed discrepancies.We discuss how future research may provide more insight into dominant processes,and how frequency distributions may be used to select the best methods for estimating soil loss from pedestals.展开更多
The effects of the erosion present on the leading edge of a wind turbine airfoil(DU 96-W-180)on its aerodynamic performances have been investigated numerically in the framework of a SST k–ωturbulence model based on ...The effects of the erosion present on the leading edge of a wind turbine airfoil(DU 96-W-180)on its aerodynamic performances have been investigated numerically in the framework of a SST k–ωturbulence model based on the Reynolds Averaged Navier-Stokes equations(RANS).The results indicate that when sand-induced holes and small pits are involved as leading edge wear features,they have a minimal influence on the lift and drag coefficients of the airfoil.However,if delamination occurs in the same airfoil region,it significantly impacts the lift and resistance characteristics of the airfoil.Specifically,as the angle of attack grows,there is a significant decrease in the lift coefficient accompanied by a sharp increase in the drag coefficient.As wear intensifies,these effects gradually increase.Moreover,the leading edge wear can exacerbate flow separation near the trailing edge suction surface of the airfoil and cause forward displacement of the separation point.展开更多
During the production period of shale gas, proppant particles and rock debris are produced together,which will seriously erode the elbows of gathering pipelines. In response to this problem, this paper takes the elbow...During the production period of shale gas, proppant particles and rock debris are produced together,which will seriously erode the elbows of gathering pipelines. In response to this problem, this paper takes the elbow of the gathering pipeline in the Changning Shale Gas Field as an example to test the erosion rate and material removal mechanism of the test piece at different angles of the elbow through experiments and compares the four erosion models with the experimental results. Through analysis, it is found that the best prediction model for quartz sand-carbon steel erosion is the Oka model. Based on the Oka model, FLUENT software was used to simulate and analyze the law of erosion of the elbow of the gas gathering pipeline under different gas flow velocities, gas gathering pressure, particle size, length of L1,and bending directions of the elbow. And a spiral pipeline structure is proposed to reduce the erosion rate of the elbow under the same working conditions. The results show that this structure can reduce erosion by 34%.展开更多
The cavitation cloud impingement of the jet in the rock breaking process was experimentally investigated to reveal the jet erosion mechanism in drilling of petroleum exploitation. Serial erosion tests and flow visuali...The cavitation cloud impingement of the jet in the rock breaking process was experimentally investigated to reveal the jet erosion mechanism in drilling of petroleum exploitation. Serial erosion tests and flow visualization were performed, where the cavitation cloud motion in the erosion crater was obtained with the designed transparent specimen. Various erosion patterns were identified in the whole erosion process based on the eroded specimen topography. The shallow eroded crater with a shrinking erosion area is generated by the combination of impinging and scattering cavitation clouds. The increase of l_(d) promotes the development of cavitation cloud σ_(c) but reduces the impingement frequency f_(d), suggesting that the jet aggressive ability is enhanced when the balance between σ_(c) and f_(d) is reached. The cavitation cloud motion in the erosion crater was investigated with the transparent specimen. The erosion in the crater at shorter exposure periods T_(e) is generated by the combination of impingement and restricted scattering of cavitation clouds. With the continuous development of the erosion damage, the jet's aggressive ability is diminished due to the erosion expansion on sandstone, where the cavitation clouds impinge on the target and then collapse and vanish without restricted scattering.展开更多
As one of typical areas in the world,northern Chinese Loess Plateau experiences serious wind-water erosion,which leads to widespread land degradation.During the past decades,an ecological engineering was implemented t...As one of typical areas in the world,northern Chinese Loess Plateau experiences serious wind-water erosion,which leads to widespread land degradation.During the past decades,an ecological engineering was implemented to reduce soil erosion and improve soil protection in this area.Thus,it is necessary to recognize the basic characteristics of soil protection for sustainable prevention and wind-water erosion control in the later stage.In this study,national wind erosion survey model and revised universal soil loss equation were used to analyze the spatiotemporal evolution and driving forces of soil protection in the wind-water erosion area of Chinese Loess Plateau during 2000–2020.Results revealed that:(1)during 2000–2020,total amount of soil protection reached up to 15.47×10^(8) t,which was realized mainly through water and soil conservation,accounting for 63.20%of the total;(2)soil protection was improved,with increases in both soil protection amount and soil retention rate.The amounts of wind erosion reduction showed a decrease trend,whereas the retention rate of wind erosion reduction showed an increase trend.Both water erosion reduction amount and retention rate showed increasing trends;and(3)the combined effects of climate change and human activities were responsible for the improvement of soil protection in the wind-water erosion area of Chinese Loess Plateau.The findings revealed the spatiotemporal patterns and driving forces of soil protection,and proposed strategies for future soil protection planning in Chinese Loess Plateau,which might provide valuable references for soil erosion control in other wind-water erosion areas of the world.展开更多
The unique geomorphological features and farming methods in the Mollisol region of Northeast China increase water catchment flow and aggravate the erosion of ephemeral gully(EG).Vegetation suffers from rain erosion an...The unique geomorphological features and farming methods in the Mollisol region of Northeast China increase water catchment flow and aggravate the erosion of ephemeral gully(EG).Vegetation suffers from rain erosion and damage during the growth stage,which brings serious problems to the restoration of grass in the early stage.Therefore,effects of coir geotextile and geocell on EG erosion under four confluence intensities were researched in this study.Results of the simulated water discharge erosion test showed that when the confluence strength was less than 30 L/min,geocell and coir geotextile had a good effect on controlling EG erosion,and sediment yield of geocell and coir geotextile was reduced by 25.95%–37.82%and 73.73%–88.96%,respectively.However,when confluence intensity increased to 40 L/min,protective effect of coir geotextile decreased,and sediment yield rate increased sharply by 189.03%.When confluence intensity increased to 50 L/min,the protective effect of coir geotextile was lost.On the other hand,geocell showed that the greater the flow rate,the better the protective effect.In addition,with the increase in confluence intensity,erosion pattern of coir geotextile developed from sheet erosion to intermittent fall and then to completion of main rill,and the protective effect was gradually weakened.In contrast,the protective effect of EG under geocell was gradually enhanced from the continuous rill to the intermittent rill and finally to the intermittent fall.This study shows that coir geotextile and geocell can prevent EG erosion,and the effect of geocell is better than that of coir geotextile on the surface of EG.展开更多
Soil erosion is a crucial geo-environmental hazard worldwide that affects water quality and agriculture,decreases reservoir storage capacity due to sedimentation,and increases the danger of flooding and landslides.Thu...Soil erosion is a crucial geo-environmental hazard worldwide that affects water quality and agriculture,decreases reservoir storage capacity due to sedimentation,and increases the danger of flooding and landslides.Thus,this study uses geospatial modeling to produce soil erosion susceptibility maps(SESM)for the Hangu region,Khyber Pakhtunkhwa(KPK),Pakistan.The Hangu region,located in the Kohat Plateau of KPK,Pakistan,is particularly susceptible to soil erosion due to its unique geomorphological and climatic characteristics.Moreover,the Hangu region is characterized by a combination of steep slopes,variable rainfall patterns,diverse land use,and distinct soil types,all of which contribute to the complexity and severity of soil erosion processes.These factors necessitate a detailed and region-specific study to develop effective soil conservation strategies.In this research,we detected and mapped 1013 soil erosion points and prepared 12 predisposing factors(elevation,aspect,slope,Normalized Differentiate Vegetation Index(NDVI),drainage network,curvature,Land Use Land Cover(LULC),rainfall,lithology,contour,soil texture,and road network)of soil erosion using GIS platform.Additionally,GIS-based statistical models like the weight of evidence(WOE)and frequency ratio(FR)were applied to produce the SESM for the study area.The SESM was reclassified into four classes,i.e.,low,medium,high,and very high zone.The results of WOE for SESM show that 16.39%,33.02%,29.27%,and 21.30%of areas are covered by low,medium,high,and very high zones,respectively.In contrast,the FR results revealed that 16.50%,24.33%,35.55%,and 23.59%of the areas are occupied by low,medium,high,and very high classes.Furthermore,the reliability of applied models was evaluated using the Area Under Curve(AUC)technique.The validation results utilizing the area under curve showed that the success rate curve(SRC)and predicted rate curve(PRC)for WOE are 82%and 86%,respectively,while SRC and PRC for FR are 85%and 96%,respectively.The validation results revealed that the FR model performance is better and more reliable than the WOE.展开更多
The glacial history of Pico de Orizaba indicates that during the Last Glacial Maximum,its icecap covered up to~3000 m asl;due to the air temperature increasing,its main glacier has retreated to 5050 m asl.The retracti...The glacial history of Pico de Orizaba indicates that during the Last Glacial Maximum,its icecap covered up to~3000 m asl;due to the air temperature increasing,its main glacier has retreated to 5050 m asl.The retraction of the glacier has left behind an intense climatic instability that causes a high frequency of freeze-thaw cycles of great intensity;the resulting geomorphological processes are represented by the fragmentation of the bedrock that occupies the upper parts of the mountain.There is a notable lack of studies regarding the fragmentation and erosion occurring in tropical high mountains,and the associated geomorphological risks;for this reason,as a first stage of future continuous research,this study analyzes the freezing and thawing cycles that occur above 4000 m asl,through continuous monitoring of surface ground temperature.The results allow us to identify and characterize four zones:glacial,paraglacial,periglacial and proglacial.It was found that the paraglacial zone presents an intense drop of temperature,of up to~9℃ in only sixty minutes.The rock fatigue and intense freeze-thaw cycles that occur in this area are responsible for the high rate of rock disintegration and represent the main factor of the constant slope dynamics that occur at the site.This activity decreases,both in frequency and intensity,according to the distance to the glacier,which is where the temperature presents a certain degree of stability,until reaching the proglacial zone,where cycles are almost non-existent,and therefore there is no gelifraction activity.The geomorphological processes have resulted in significant alterations to the mountain slopes,which can have severe consequences in terms of risk and water.展开更多
In most coastal and estuarine areas,tides easily cause surface erosion and even slope failure,resulting in severe land losses,deterioration of coastal infrastructure,and increased floods.The bio-cementation technique ...In most coastal and estuarine areas,tides easily cause surface erosion and even slope failure,resulting in severe land losses,deterioration of coastal infrastructure,and increased floods.The bio-cementation technique has been previously demonstrated to effectively improve the erosion resistance of slopes.Seawater contains magnesium ions(Mg^(2+))with a higher concentration than calcium ions(Ca^(2+));therefore,Mg^(2+)and Ca^(2+)were used together for bio-cementation in this study at various Mg^(2+)/Ca^(2+)ratios as the microbially induced magnesium and calcium precipitation(MIMCP)treatment.Slope angles,surface strengths,precipitation contents,major phases,and microscopic characteristics of precipitation were used to evaluate the treatment effects.Results showed that the MIMCP treatment markedly enhanced the erosion resistance of slopes.Decreased Mg^(2+)/Ca^(2+)ratios resulted in a smaller change in angles and fewer soil losses,especially the Mg^(2+)concentration below 0.2 M.The decreased Mg^(2+)/Ca^(2+)ratio achieved increased precipitation contents,which contributed to better erosion resistance and higher surface strengths.Additionally,the production of aragonite would benefit from elevated Mg^(2+)concentrations and a higher Ca^(2+)concentration led to more nesquehonite in magnesium precipitation crystals.The slopes with an initial angle of 53°had worse erosion resistance than the slopes with an initial angle of 35°,but the Mg^(2+)/Ca^(2+)ratios of 0.2:0.8,0.1:0.9,and 0:1.0 were effective for both slope stabilization and erosion mitigation to a great extent.The results are of great significance for the application of MIMCP to improve erosion resistance of foreshore slopes and the MIMCP technique has promising application potential in marine engineering.展开更多
The original online version of this article was revised.The first author is“ZHANG Weng-xiang”in the original article.The first author’s name has been corrected to“ZHANG Wen-xiang”.
aSoil degradation caused by soil erosion is one of the world's most critical environmental issues.Soil erosion in the Tianshan Mountains has caused various environmental problems in the surrounding areas.This stud...aSoil degradation caused by soil erosion is one of the world's most critical environmental issues.Soil erosion in the Tianshan Mountains has caused various environmental problems in the surrounding areas.This study used remote sensing data to analyze the distribution of the factors influencing soil erosion,and the revised universal soil loss equation(RUSLE)to calculate the total amount and distribution characteristics of soil erosion in the Tianshan Mountains in 2019.Due to the large error of RUSLE in soil erosion estimation in mountainous areas,this study modified RUSLE equation based on the characteristics of snow cover in the Tianshan Mountains.The results show that the average soil erosion was 1690.3 t/(km^(2)·year),of which insignificant erosion,slight erosion and moderate erosion accounted for 42,8%,22.4%and 9.9%,respectively.Severe erosion and above accounted for 13.3%.The accuracy of the soil erosion modulus calculated by the RUSLE was only 61.9%,with an average error of 1631.9 t/(km^(2)·year).The average error of the double-coefficient correction method was 1259.1 t/(km^(2)·year),and the average error of the modified formula method was reduced by 40.3%compared with the RUSLE,reaching 973.7 t/(km^(2)·year),and its accuracy reached 76.2%.Very severe erosion and catastrophic erosion are distributed on mountain ridges with higher elevation and on the northern area with higher precipitation.Snow cover has a certain inhibitory effect on soil erosion,and snow cover in alpine mountains is a factor that cannot be ignored in soil erosion research.展开更多
BACKGROUND For the treatment of gastritis,rebamipide,a mucoprotective agent,and nizatidine,a gastric acid suppressant,are commonly employed individually.AIM To compare the efficacy of Mucotra®SR(rebamipide 150 mg...BACKGROUND For the treatment of gastritis,rebamipide,a mucoprotective agent,and nizatidine,a gastric acid suppressant,are commonly employed individually.AIM To compare the efficacy of Mucotra®SR(rebamipide 150 mg)and Axid®(nizatidine 150 mg)combination therapy with the sole administration of Axid®in managing erosive gastritis.METHODS A total of 260 patients diagnosed with endoscopically confirmed erosive gastritis were enrolled in this open-label,multicenter,randomized,phase 4 clinical trial,allocating them into two groups:Rebamipide/nizatidine combination twice daily vs nizatidine twice daily for 2 weeks.The full-analysis set analysis encompassed 239 patients(rebamipide/nizatidine,n=121;nizatidine,n=118),while the per-protocol analysis included 218 patients(n=110 vs 108).Post-treatment assessments comprised primary(erosion improvement rate)and secondary(erosion and edema cure rates,erythema improvement rates,hemorrhage,and gastrointestinal symptoms)endpoints.Furthermore,drug-related adverse effects were evaluated.RESULTS Primary efficacy assessment showed a statistically significant improvement rate in mucosal erosions in the combination group compared to the control group in the full-analysis set(rebamipide/nizatidine 62.0%,nizatidine 49.2%,P=0.046),with a similar trend noted in the per-protocol analysis(62.7%vs 50.0%,P=0.058).Both groups were effective in curing erosion and edema and improvement of bleeding,erythema,and gastrointestinal symptoms,whereas no inter-group differences were noted.When confined to the participants with gastritis symptoms,improvement of erosion was more optimal in the combination group(63.0%vs 49.5%,P=0.046).No adverse events related to the drugs were observed.CONCLUSION Rebamipide/nizatidine combination is effective in treatment of erosive gastritis.展开更多
Cape Stone Forest is a group of granite rock pillars(pedestal rocks) towering over Shilin Lake, on the southern shore of Shantou Bay in eastern Guangdong, China. The rock pillars were previously identified as sea stac...Cape Stone Forest is a group of granite rock pillars(pedestal rocks) towering over Shilin Lake, on the southern shore of Shantou Bay in eastern Guangdong, China. The rock pillars were previously identified as sea stacks because they have marine notch-like concave sidewalls at their base, and more importantly, the lake is immediately adjacent to the bay, which is exposed to the open sea. However, rock pillars similar in shape and size can also be found at the top of Queshi Mountain, which is only about 300 meters northwest of the lake and about 85 meters above sea level. Therefore, the marine origin of Cape Stone Forest is seriously questioned. In this study, 3D imagery and drone technology were used to collect data in the investigations without direct manual measurements in the water or on the mountain. It shows that the concave sidewalls of the rock pillars in the lake and on the mountains occur at different heights and are exposed to different directions, while a natural sea stack on Mayu Island at the mouth of Shantou Bay has a horizontal notch parallel to the sea level, although the granite rock of the sea stack is the same as that of the lake and the mountains. The eastern side of the island, where the sea stack is located, is exposed to the open sea but blocks large waves for the rock pillars in the lake. Therefore, the origin of Cape Stone Forest cannot be explained by wave-based mechanisms. The only satisfactory explanation that takes into account all the field evidence is that the narrow rock pillars of the lake and mountain were formed by chemical weathering that penetrated closely the spaced joints of the granite rock, and the notch-like concave sidewalls were formed by more effective chemical weathering at the base of the pillars.展开更多
基金the National Key Clinical Specialty Construction Project,No.ZK108000CAMS Innovation Fund for Medical Sciences,No.2021-I2M-C&T-A-001 and No.2022-I2M-C&T-B-012.
文摘BACKGROUND Although chronic erosive gastritis(CEG)is common,its clinical characteristics have not been fully elucidated.The lack of consensus regarding its treatment has resulted in varied treatment regimens.AIM To explore the clinical characteristics,treatment patterns,and short-term outcomes in CEG patients in China.METHODS We recruited patients with chronic non-atrophic or mild-to-moderate atrophic gastritis with erosion based on endoscopy and pathology.Patients and treating physicians completed a questionnaire regarding history,endoscopic findings,and treatment plans as well as a follow-up questionnaire to investigate changes in symptoms after 4 wk of treatment.RESULTS Three thousand five hundred sixty-three patients from 42 centers across 24 cities in China were included.Epigastric pain(68.0%),abdominal distension(62.6%),and postprandial fullness(47.5%)were the most common presenting symptoms.Gastritis was classified as chronic non-atrophic in 69.9%of patients.Among those with erosive lesions,72.1%of patients had lesions in the antrum,51.0%had multiple lesions,and 67.3%had superficial flat lesions.In patients with epigastric pain,the combination of a mucosal protective agent(MPA)and proton pump inhibitor was more effective.For those with postprandial fullness,acid regurgitation,early satiety,or nausea,a MPA appeared more promising.CONCLUSION CEG is a multifactorial disease which is common in Asian patients and has non-specific symptoms.Gastroscopy may play a major role in its detection and diagnosis.Treatment should be individualized based on symptom profile.
基金supported by the Natural Science Foundation of Qinghai Province(Grant No.2024-ZJ-987).
文摘The China Loess Plateau is subjected to severe soil erosion triggered by intense rainfall,resulting in significant harm and losses to both human society and the natural surroundings.In this study,a novel technique for managing loess erosion is introduced,which involves the utilization of a combined polymer SH and ryegrass.A comprehensive series of tests were undertaken,including rainfall erosion tests,disintegration experiments,and scanning electron microscopy examinations,to assess the accumulative sediment yield(ASY),disintegration ratio,and microstructural features of both untreated and treated loess samples.The results showed a significant reduction in ASY with increased dry density of untreated loess.Furthermore,the combined technique effectively controlled erosion,limiting ASY to 266.2 g/cm^(2)in 60 minutes.This was approximately one-sixth,one-ninth,and one-fifteenth of the ASY in SH-treated loess(L-SH),ryegrass-treated loess(L-R),and untreated loess,respectively.It resisted disintegration better than ryegrass alone but slightly less than SH.This improvement was due to the combined effect of SH and ryegrass,which reduced raindrop impact,improved loess microstructure,and boosted ryegrass growth.The innovative technique holds the potential to be applied as a field-scale technique in the Loess Plateau region of China.
基金supported by the National Natural Scienceof China (No.52175208)Scientific Research and Technology Development Project of CNPC (No.2023ZZ11)+1 种基金Fundamental Research and Strategic Reserve Technology Research Fund Project of CNPC (No.2023DQ03-03)Study on Key Technologies of Production Increase and Transformation of Gulong Shale Oil (2021ZZ10-04)。
文摘Erosion wear is a common failure mode in the oil and gas industry.In the hydraulic fracturing,the fracturing pipes are not only in high-pressure working environment,but also suffer from the impact of the high-speed solid particles in the fracturing fluid.Beneath such complex conditions,the vulnerable components of the pipe system are prone to perforation or even burst accidents,which has become one of the most serious risks at the fracturing site.Unfortunately,it is not yet fully understood the erosion mechanism of pipe steel for hydraulic fracturing.Therefore,this article provides a detailed analysis of the erosion behavior of fracturing pipes under complex working conditions based on experiments and numerical simulations.Firstly,we conducted erosion experiments on AISI 4135 steel for fracturing pipes to investigate the erosion characteristics of the material.The effects of impact angle,flow velocity and applied stress on erosion wear were comprehensively considered.Then a particle impact dynamic model of erosion wear was developed based on the experimental parameters,and the evolution process of particle erosion under different impact angles,impact velocities and applied stress was analyzed.By combining the erosion characteristics,the micro-structure of the eroded area,and the micro-mechanics of erosion damage,the erosion mechanism of pipe steel under fracturing conditions was studied in detail for the first time.Under high-pressure operating conditions,it was demonstrated through experiments and numerical simulations that the size of the micro-defects in the eroded area increased as the applied stress increased,resulting in more severe erosion wear of fracturing pipes.
基金financially supported by the Natural Science Foundation of Gansu Province,China(22JR5RA050,20JR10RA231)the fellowship of the China Postdoctoral Science Foundation(2021M703466)the Basic Research Innovation Group Project of Gansu Province,China(21JR7RA347).
文摘For the safety of railroad operations,sand barriers are utilized to mitigate wind-sand disaster effects.These disasters,characterized by multi-directional wind patterns,result in diverse angles among the barriers.In this study,using numerical simulations,we examined the behavior of High Density Polyethylene(HDPE)sheet sand barriers under different wind angles,focusing on flow field distribution,windproof efficiency,and sedimentation erosion dynamics.This study discovered that at a steady wind speed,airflow velocity varies as the angle between the airflow and the HDPE barrier changes.Specifically,a 90°angle results in the widest low-speed airflow area on the barrier’s downwind side.If the airflow is not perpendicular to the barrier,it prompts a lateral airflow movement which decreases as the angle expands.The windproof efficiency correlates directly with this angle but inversely with the wind’s speed.Notably,with a wind angle of 90°,wind speed drops by 81%.The minimum wind speed is found at 5.1H(the sand barrier height)on the barrier’s downwind side.As the angle grows,the barrier’s windproof efficiency improves,extending its protective reach.Sedimentation is most prominent on the barrier’s downwind side,as the wind angle shifts from 30°to 90°,the sand sedimentation area on the barrier’s downwind side enlarges by 14.8H.As the angle grows,sedimentation intensifies,eventually overtakes the forward erosion and enlarges the sedimentation area.
基金the National Natural Science Foundation of China(Grant No.12102050)the Open Fund of State Key Laboratory of Explosion Science and Technology(Grant No.SKLEST-ZZ-21-18).
文摘The majority of the projectiles used in the hypersonic penetration study are solid flat-nosed cylindrical projectiles with a diameter of less than 20 mm.This study aims to fill the gap in the experimental and analytical study of the evolution of the nose shape of larger hollow projectiles under hypersonic penetration.In the hypersonic penetration test,eight ogive-nose AerMet100 steel projectiles with a diameter of 40 mm were launched to hit concrete targets with impact velocities that ranged from 1351 to 1877 m/s.Severe erosion of the projectiles was observed during high-speed penetration of heterogeneous targets,and apparent localized mushrooming occurred in the front nose of recovered projectiles.By examining the damage to projectiles,a linear relationship was found between the relative length reduction rate and the initial kinetic energy of projectiles in different penetration tests.Furthermore,microscopic analysis revealed the forming mechanism of the localized mushrooming phenomenon for eroding penetration,i.e.,material spall erosion abrasion mechanism,material flow and redistribution abrasion mechanism and localized radial upsetting deformation mechanism.Finally,a model of highspeed penetration that included erosion was established on the basis of a model of the evolution of the projectile nose that considers radial upsetting;the model was validated by test data from the literature and the present study.Depending upon the impact velocity,v0,the projectile nose may behave as undistorted,radially distorted or hemispherical.Due to the effects of abrasion of the projectile and enhancement of radial upsetting on the duration and amplitude of the secondary rising segment in the pulse shape of projectile deceleration,the predicted DOP had an upper limit.
基金the financial support received from the University Grants Commission (UGC) in the form of a Junior Research Fellowship (JRF)。
文摘Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of vegetated land into agricultural land and built-up area,stand out as primary contributors to soil erosion.The present study investigated the risk of soil erosion in the Irga watershed located on the eastern fringe of the Chota Nagpur Plateau in Jharkhand,India,which is dominated by sandy loam and sandy clay loam soil with low soil organic carbon(SOC)content.The study used the Revised Universal Soil Loss Equation(RUSLE)and Geographical Information System(GIS)technique to determine the rate of soil erosion.The five parameters(rainfall-runoff erosivity(R)factor,soil erodibility(K)factor,slope length and steepness(LS)factor,cover-management(C)factor,and support practice(P)factor)of the RUSLE were applied to present a more accurate distribution characteristic of soil erosion in the Irga watershed.The result shows that the R factor is positively correlated with rainfall and follows the same distribution pattern as the rainfall.The K factor values in the northern part of the study area are relatively low,while they are relatively high in the southern part.The mean value of the LS factor is 2.74,which is low due to the flat terrain of the Irga watershed.There is a negative linear correlation between Normalized Difference Vegetation Index(NDVI)and the C factor,and the high values of the C factor are observed in places with low NDVI.The mean value of the P factor is 0.210,with a range from 0.000 to 1.000.After calculating all parameters,we obtained the average soil erosion rate of 1.43 t/(hm^(2)•a),with the highest rate reaching as high as 32.71 t/(hm^(2)•a).Therefore,the study area faces a low risk of soil erosion.However,preventative measures are essential to avoid future damage to productive and constructive activities caused by soil erosion.This study also identifies the spatial distribution of soil erosion rate,which will help policy-makers to implement targeted soil erosion control measures.
基金funded by the Natural Science Foundation of China(Grants No.42041006,42377158,42377163)the Provincial Key R&D Project(211426230324).
文摘Loess internal erosion caused by preferential flow often leads to serious loess ground collapse,shallow loess landslides,and other geological disasters.However,there is a lack of quantitative evaluation of the internal erodibility of undisturbed loess under the action of preferential flow,and little is known about the correlation between the internal erodibility of loess and its microstructure.In this study,we carried out a series of hole erosion tests(HET)on undisturbed loess samples from 4 typical locations on China's Loess Plateau.The internal erodibility of loess was quantitatively evaluated through an improved HET method,and its association with initial water content,clay content,and initial water head difference was investigated.On the microscopic scale,the microstructure of loess with different clay content was measured by scanning electron microscopy(SEM).The correlation between pore and particle microstructure parameters and loess internal erosion parameters was established based on grey correlation theory.When the initial water content increased from 10%to 36%,the erodibility index increased from 1 to 2.5.When the clay content increased from 8%to 27.95%,the erodibility index increased 3.5 times.The increase of initial water head difference has a positive linear effect on the internal erodibility of loess.The microstructure analysis shows that with the increase of clay content,the microstructure of undisturbed loess changes from a mosaic structure to a cementation structure,which creates favourable conditions for controlling the internal erosion of loess.Through grey correlation analysis,it has been determined that the microstructure of undisturbed loess has a significant correlation with the critical shear stress,and the loess microstructure morphology strongly correlates with the erosion rate.Under normal circumstances,the higher the clay content,the better the erosion resistance,the better the mechanical stability,and the easier to form a stable cave in loess.This study can provide a reference for revealing the cave formation mechanism in the loess area in the future.
基金supported by CESAM by FCT/MCTES (UIDP/50017/2020+UIDB/50017/2020+LA/P/0094/2020)and MED (UIDB/05183/2020)to FCT/MEC through national fundsthe co-funding by the FEDER,within the PT2020 Partnership Agreement and Compete 2020,and projects FIRECNUTS (PTDC/AGRCFL/104559/2008)+2 种基金CASCADE (ENV.2011.2.1.4-2/283068),which is funded by the European Unionthe FCT CEEC funding of Frank G.A.Verheijen (CEECIND/02509/2018),Sergio A.Prats (CEECIND/01473/2020),funded by national funds (OE)the SOILCOMBAT project (PTDC/EAM-AMB/0474/2020)through the Portuguese Foundation for Science and Technology (FCT/MCTES).
文摘Soil pedestals have long been used as qualitative indicators of soil splash erosion.In rangelands,plant-capped pedestals,generally grass tussocks,have also been used to quantitatively estimate soil loss since the first half of the twentieth century.In agricultural lands,forests,and bad-lands,stone-capped pedestals have been used as qualitative and semi-quantitative indicators of active,'extreme'erosion.Little work has been reported on using capstone pedestal data for quantifying soil loss.We postulate that three distinct capstone pedestal types may be present in any given location and that a detailed analysis of a pedestal height histogram may be used to recognize their populations.This analysis can subsequently inform if soil loss can be reliably estimated and if so,which of the existing methods using pedestal height data will provide more accurate results.The three proposed capstone pedestal types are:(1)neo-pedestals formed underneath surface stones exposed by(partial)removal of the soil surface cover;(2)endo-pedestals formed underneath stones that were buried in the soil but have been exposed by erosion;and(3)phoenix-pedestals formed underneath stones from collapsed pedestals.In the pedestal height histogram of any given location,a skew to smaller heights may indicate the existence of endo-and/or phoenix-pedestals,which may be revealed as a bi-(or tri)modal distribution when using a smaller bin size.This concept was applied to a case study where soil loss had been monitored for control plots and mulched plots during a 5-year period following wildfire in a eucalypt plantation.We measured pedestal heights and used methods to quantitatively assess soil loss from soil pedestal data in the available literature.Soil pedestal data at the end of the 5-year period under or overestimated soil loss in the control treatment,with results ranging from 60 to 115%of measured soil loss,depending on the method.It is postulated that phoenix-and endo-pedestals may be a driving factor behind the observed discrepancies.We discuss how future research may provide more insight into dominant processes,and how frequency distributions may be used to select the best methods for estimating soil loss from pedestals.
基金Natural Science Foundation of Liaoning Province(2022-MS-305)Foundation of Liaoning Province Education Administration(LJKZ1108).
文摘The effects of the erosion present on the leading edge of a wind turbine airfoil(DU 96-W-180)on its aerodynamic performances have been investigated numerically in the framework of a SST k–ωturbulence model based on the Reynolds Averaged Navier-Stokes equations(RANS).The results indicate that when sand-induced holes and small pits are involved as leading edge wear features,they have a minimal influence on the lift and drag coefficients of the airfoil.However,if delamination occurs in the same airfoil region,it significantly impacts the lift and resistance characteristics of the airfoil.Specifically,as the angle of attack grows,there is a significant decrease in the lift coefficient accompanied by a sharp increase in the drag coefficient.As wear intensifies,these effects gradually increase.Moreover,the leading edge wear can exacerbate flow separation near the trailing edge suction surface of the airfoil and cause forward displacement of the separation point.
基金supported by the Petrochina's “14th Five-Year plan” Project(2021DJ2804)Sichuan Natural Science Foundation(2023NSFSC0422)。
文摘During the production period of shale gas, proppant particles and rock debris are produced together,which will seriously erode the elbows of gathering pipelines. In response to this problem, this paper takes the elbow of the gathering pipeline in the Changning Shale Gas Field as an example to test the erosion rate and material removal mechanism of the test piece at different angles of the elbow through experiments and compares the four erosion models with the experimental results. Through analysis, it is found that the best prediction model for quartz sand-carbon steel erosion is the Oka model. Based on the Oka model, FLUENT software was used to simulate and analyze the law of erosion of the elbow of the gas gathering pipeline under different gas flow velocities, gas gathering pressure, particle size, length of L1,and bending directions of the elbow. And a spiral pipeline structure is proposed to reduce the erosion rate of the elbow under the same working conditions. The results show that this structure can reduce erosion by 34%.
基金funded by the National Key R&D Program of China (Grant No. 2021YFB3401500)Engineering research 2023-GCKY-001the National Natural Science Foundation of China(Grant Nos. 52004018, 52304119)。
文摘The cavitation cloud impingement of the jet in the rock breaking process was experimentally investigated to reveal the jet erosion mechanism in drilling of petroleum exploitation. Serial erosion tests and flow visualization were performed, where the cavitation cloud motion in the erosion crater was obtained with the designed transparent specimen. Various erosion patterns were identified in the whole erosion process based on the eroded specimen topography. The shallow eroded crater with a shrinking erosion area is generated by the combination of impinging and scattering cavitation clouds. The increase of l_(d) promotes the development of cavitation cloud σ_(c) but reduces the impingement frequency f_(d), suggesting that the jet aggressive ability is enhanced when the balance between σ_(c) and f_(d) is reached. The cavitation cloud motion in the erosion crater was investigated with the transparent specimen. The erosion in the crater at shorter exposure periods T_(e) is generated by the combination of impingement and restricted scattering of cavitation clouds. With the continuous development of the erosion damage, the jet's aggressive ability is diminished due to the erosion expansion on sandstone, where the cavitation clouds impinge on the target and then collapse and vanish without restricted scattering.
基金funded by the National Key Research and Development Program of China(2023YFF1305304)the National Natural Science Foundation of China(41801007)+3 种基金the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0201)the Science Technology Project of Hebei Academy of Sciences(2024PF11)the Basic Research Program of Shanxi Province(202203021211258,202103021223248)the Science and Technology Strategy Project of Shanxi Province(202304031401073).
文摘As one of typical areas in the world,northern Chinese Loess Plateau experiences serious wind-water erosion,which leads to widespread land degradation.During the past decades,an ecological engineering was implemented to reduce soil erosion and improve soil protection in this area.Thus,it is necessary to recognize the basic characteristics of soil protection for sustainable prevention and wind-water erosion control in the later stage.In this study,national wind erosion survey model and revised universal soil loss equation were used to analyze the spatiotemporal evolution and driving forces of soil protection in the wind-water erosion area of Chinese Loess Plateau during 2000–2020.Results revealed that:(1)during 2000–2020,total amount of soil protection reached up to 15.47×10^(8) t,which was realized mainly through water and soil conservation,accounting for 63.20%of the total;(2)soil protection was improved,with increases in both soil protection amount and soil retention rate.The amounts of wind erosion reduction showed a decrease trend,whereas the retention rate of wind erosion reduction showed an increase trend.Both water erosion reduction amount and retention rate showed increasing trends;and(3)the combined effects of climate change and human activities were responsible for the improvement of soil protection in the wind-water erosion area of Chinese Loess Plateau.The findings revealed the spatiotemporal patterns and driving forces of soil protection,and proposed strategies for future soil protection planning in Chinese Loess Plateau,which might provide valuable references for soil erosion control in other wind-water erosion areas of the world.
基金supported by the National Natural Science Foundation of China(41907047)the China Scholarship Council(202106515016)the Strategic International Collaboration of Scientific and Technological Innovation for the National Key Research and Development Plan(2016YFE0202900).
文摘The unique geomorphological features and farming methods in the Mollisol region of Northeast China increase water catchment flow and aggravate the erosion of ephemeral gully(EG).Vegetation suffers from rain erosion and damage during the growth stage,which brings serious problems to the restoration of grass in the early stage.Therefore,effects of coir geotextile and geocell on EG erosion under four confluence intensities were researched in this study.Results of the simulated water discharge erosion test showed that when the confluence strength was less than 30 L/min,geocell and coir geotextile had a good effect on controlling EG erosion,and sediment yield of geocell and coir geotextile was reduced by 25.95%–37.82%and 73.73%–88.96%,respectively.However,when confluence intensity increased to 40 L/min,protective effect of coir geotextile decreased,and sediment yield rate increased sharply by 189.03%.When confluence intensity increased to 50 L/min,the protective effect of coir geotextile was lost.On the other hand,geocell showed that the greater the flow rate,the better the protective effect.In addition,with the increase in confluence intensity,erosion pattern of coir geotextile developed from sheet erosion to intermittent fall and then to completion of main rill,and the protective effect was gradually weakened.In contrast,the protective effect of EG under geocell was gradually enhanced from the continuous rill to the intermittent rill and finally to the intermittent fall.This study shows that coir geotextile and geocell can prevent EG erosion,and the effect of geocell is better than that of coir geotextile on the surface of EG.
基金The authors extend their appreciation to Researchers Supporting Project number(RSP2024R390),King Saud University,Riyadh,Saudi Arabia.
文摘Soil erosion is a crucial geo-environmental hazard worldwide that affects water quality and agriculture,decreases reservoir storage capacity due to sedimentation,and increases the danger of flooding and landslides.Thus,this study uses geospatial modeling to produce soil erosion susceptibility maps(SESM)for the Hangu region,Khyber Pakhtunkhwa(KPK),Pakistan.The Hangu region,located in the Kohat Plateau of KPK,Pakistan,is particularly susceptible to soil erosion due to its unique geomorphological and climatic characteristics.Moreover,the Hangu region is characterized by a combination of steep slopes,variable rainfall patterns,diverse land use,and distinct soil types,all of which contribute to the complexity and severity of soil erosion processes.These factors necessitate a detailed and region-specific study to develop effective soil conservation strategies.In this research,we detected and mapped 1013 soil erosion points and prepared 12 predisposing factors(elevation,aspect,slope,Normalized Differentiate Vegetation Index(NDVI),drainage network,curvature,Land Use Land Cover(LULC),rainfall,lithology,contour,soil texture,and road network)of soil erosion using GIS platform.Additionally,GIS-based statistical models like the weight of evidence(WOE)and frequency ratio(FR)were applied to produce the SESM for the study area.The SESM was reclassified into four classes,i.e.,low,medium,high,and very high zone.The results of WOE for SESM show that 16.39%,33.02%,29.27%,and 21.30%of areas are covered by low,medium,high,and very high zones,respectively.In contrast,the FR results revealed that 16.50%,24.33%,35.55%,and 23.59%of the areas are occupied by low,medium,high,and very high classes.Furthermore,the reliability of applied models was evaluated using the Area Under Curve(AUC)technique.The validation results utilizing the area under curve showed that the success rate curve(SRC)and predicted rate curve(PRC)for WOE are 82%and 86%,respectively,while SRC and PRC for FR are 85%and 96%,respectively.The validation results revealed that the FR model performance is better and more reliable than the WOE.
基金support from the Programa de Apoyos para la Superación del Personal Académico (DGAPA)the support by the Alexander von Humboldt Foundationpart of the SIREI project num 531062023178 developed at CCT-UV
文摘The glacial history of Pico de Orizaba indicates that during the Last Glacial Maximum,its icecap covered up to~3000 m asl;due to the air temperature increasing,its main glacier has retreated to 5050 m asl.The retraction of the glacier has left behind an intense climatic instability that causes a high frequency of freeze-thaw cycles of great intensity;the resulting geomorphological processes are represented by the fragmentation of the bedrock that occupies the upper parts of the mountain.There is a notable lack of studies regarding the fragmentation and erosion occurring in tropical high mountains,and the associated geomorphological risks;for this reason,as a first stage of future continuous research,this study analyzes the freezing and thawing cycles that occur above 4000 m asl,through continuous monitoring of surface ground temperature.The results allow us to identify and characterize four zones:glacial,paraglacial,periglacial and proglacial.It was found that the paraglacial zone presents an intense drop of temperature,of up to~9℃ in only sixty minutes.The rock fatigue and intense freeze-thaw cycles that occur in this area are responsible for the high rate of rock disintegration and represent the main factor of the constant slope dynamics that occur at the site.This activity decreases,both in frequency and intensity,according to the distance to the glacier,which is where the temperature presents a certain degree of stability,until reaching the proglacial zone,where cycles are almost non-existent,and therefore there is no gelifraction activity.The geomorphological processes have resulted in significant alterations to the mountain slopes,which can have severe consequences in terms of risk and water.
基金funded by the National Natural Science Foundation of China(Grant No.51578147)Fundamental Research Funds for the Central Universities(Grant No.2242020R20025)Ningxia Science and Technology Department(Grant No.2020BFG02014).
文摘In most coastal and estuarine areas,tides easily cause surface erosion and even slope failure,resulting in severe land losses,deterioration of coastal infrastructure,and increased floods.The bio-cementation technique has been previously demonstrated to effectively improve the erosion resistance of slopes.Seawater contains magnesium ions(Mg^(2+))with a higher concentration than calcium ions(Ca^(2+));therefore,Mg^(2+)and Ca^(2+)were used together for bio-cementation in this study at various Mg^(2+)/Ca^(2+)ratios as the microbially induced magnesium and calcium precipitation(MIMCP)treatment.Slope angles,surface strengths,precipitation contents,major phases,and microscopic characteristics of precipitation were used to evaluate the treatment effects.Results showed that the MIMCP treatment markedly enhanced the erosion resistance of slopes.Decreased Mg^(2+)/Ca^(2+)ratios resulted in a smaller change in angles and fewer soil losses,especially the Mg^(2+)concentration below 0.2 M.The decreased Mg^(2+)/Ca^(2+)ratio achieved increased precipitation contents,which contributed to better erosion resistance and higher surface strengths.Additionally,the production of aragonite would benefit from elevated Mg^(2+)concentrations and a higher Ca^(2+)concentration led to more nesquehonite in magnesium precipitation crystals.The slopes with an initial angle of 53°had worse erosion resistance than the slopes with an initial angle of 35°,but the Mg^(2+)/Ca^(2+)ratios of 0.2:0.8,0.1:0.9,and 0:1.0 were effective for both slope stabilization and erosion mitigation to a great extent.The results are of great significance for the application of MIMCP to improve erosion resistance of foreshore slopes and the MIMCP technique has promising application potential in marine engineering.
文摘The original online version of this article was revised.The first author is“ZHANG Weng-xiang”in the original article.The first author’s name has been corrected to“ZHANG Wen-xiang”.
基金supported by the Third Xinjiang Scientific Expedition and Research Program (Grant No. 2022xjkk0602)National Cryosphere Desert Data Center (No. 2021kf02)Xinjiang Jiaotou’s Unveiling and Commanding System Project in 2021 (ZKXFWCG 2022060004)。
文摘aSoil degradation caused by soil erosion is one of the world's most critical environmental issues.Soil erosion in the Tianshan Mountains has caused various environmental problems in the surrounding areas.This study used remote sensing data to analyze the distribution of the factors influencing soil erosion,and the revised universal soil loss equation(RUSLE)to calculate the total amount and distribution characteristics of soil erosion in the Tianshan Mountains in 2019.Due to the large error of RUSLE in soil erosion estimation in mountainous areas,this study modified RUSLE equation based on the characteristics of snow cover in the Tianshan Mountains.The results show that the average soil erosion was 1690.3 t/(km^(2)·year),of which insignificant erosion,slight erosion and moderate erosion accounted for 42,8%,22.4%and 9.9%,respectively.Severe erosion and above accounted for 13.3%.The accuracy of the soil erosion modulus calculated by the RUSLE was only 61.9%,with an average error of 1631.9 t/(km^(2)·year).The average error of the double-coefficient correction method was 1259.1 t/(km^(2)·year),and the average error of the modified formula method was reduced by 40.3%compared with the RUSLE,reaching 973.7 t/(km^(2)·year),and its accuracy reached 76.2%.Very severe erosion and catastrophic erosion are distributed on mountain ridges with higher elevation and on the northern area with higher precipitation.Snow cover has a certain inhibitory effect on soil erosion,and snow cover in alpine mountains is a factor that cannot be ignored in soil erosion research.
文摘BACKGROUND For the treatment of gastritis,rebamipide,a mucoprotective agent,and nizatidine,a gastric acid suppressant,are commonly employed individually.AIM To compare the efficacy of Mucotra®SR(rebamipide 150 mg)and Axid®(nizatidine 150 mg)combination therapy with the sole administration of Axid®in managing erosive gastritis.METHODS A total of 260 patients diagnosed with endoscopically confirmed erosive gastritis were enrolled in this open-label,multicenter,randomized,phase 4 clinical trial,allocating them into two groups:Rebamipide/nizatidine combination twice daily vs nizatidine twice daily for 2 weeks.The full-analysis set analysis encompassed 239 patients(rebamipide/nizatidine,n=121;nizatidine,n=118),while the per-protocol analysis included 218 patients(n=110 vs 108).Post-treatment assessments comprised primary(erosion improvement rate)and secondary(erosion and edema cure rates,erythema improvement rates,hemorrhage,and gastrointestinal symptoms)endpoints.Furthermore,drug-related adverse effects were evaluated.RESULTS Primary efficacy assessment showed a statistically significant improvement rate in mucosal erosions in the combination group compared to the control group in the full-analysis set(rebamipide/nizatidine 62.0%,nizatidine 49.2%,P=0.046),with a similar trend noted in the per-protocol analysis(62.7%vs 50.0%,P=0.058).Both groups were effective in curing erosion and edema and improvement of bleeding,erythema,and gastrointestinal symptoms,whereas no inter-group differences were noted.When confined to the participants with gastritis symptoms,improvement of erosion was more optimal in the combination group(63.0%vs 49.5%,P=0.046).No adverse events related to the drugs were observed.CONCLUSION Rebamipide/nizatidine combination is effective in treatment of erosive gastritis.
基金funded by the Natural Science Foundation of China (Grants No. 42171007)。
文摘Cape Stone Forest is a group of granite rock pillars(pedestal rocks) towering over Shilin Lake, on the southern shore of Shantou Bay in eastern Guangdong, China. The rock pillars were previously identified as sea stacks because they have marine notch-like concave sidewalls at their base, and more importantly, the lake is immediately adjacent to the bay, which is exposed to the open sea. However, rock pillars similar in shape and size can also be found at the top of Queshi Mountain, which is only about 300 meters northwest of the lake and about 85 meters above sea level. Therefore, the marine origin of Cape Stone Forest is seriously questioned. In this study, 3D imagery and drone technology were used to collect data in the investigations without direct manual measurements in the water or on the mountain. It shows that the concave sidewalls of the rock pillars in the lake and on the mountains occur at different heights and are exposed to different directions, while a natural sea stack on Mayu Island at the mouth of Shantou Bay has a horizontal notch parallel to the sea level, although the granite rock of the sea stack is the same as that of the lake and the mountains. The eastern side of the island, where the sea stack is located, is exposed to the open sea but blocks large waves for the rock pillars in the lake. Therefore, the origin of Cape Stone Forest cannot be explained by wave-based mechanisms. The only satisfactory explanation that takes into account all the field evidence is that the narrow rock pillars of the lake and mountain were formed by chemical weathering that penetrated closely the spaced joints of the granite rock, and the notch-like concave sidewalls were formed by more effective chemical weathering at the base of the pillars.