Erosion Characteristics Research Articles

Effects of cyanobacteria- and moss-biocrusts on soil aggregate stability and splash erosion in croplands of the China Mollisols area.

To investigate the effects of biocrusts development on aggregate stability and splash erosion of Mollisols and to understand its function in soil and water conservation, we collected biocrusts (cyano crust and moss crust) samples in croplands during the growing season and measured the differences in aggregate stability between biocrusts and uncrusted soil. The effects of biocrusts on reduction of raindrop kinetic energy were determined and splash erosion amounts were obtained with single raindrop and simulated rainfall experiments. The correlations among soil aggregate stability, splash erosion characteristics, and fundamental properties of biocrusts were analyzed. The results showed that compared to uncrusted soil, the cyano crust and the moss crust decreased the proportion of soil water-stable aggregates <0.25 mm by 10.5% and 21.8%, respectively, while their soil water-stable aggregates 5-10 mm were 4.0 and 8.8 times as that of uncrusted soil. In contrast to uncrusted soil, the macroaggregate content (R0.25), mean weight diameter (MWD), and geometric mean diameter (GMD) of biocrusts were 31.5%, 76.2%, and 33.5% higher, respectively. In addition, biocrusts reduced raindrop kinetic energy by an average of 0.48 J compared to uncrusted soil. The breakthrough raindrop kinetic energy of cyano crust and moss crust were 2.9 and 26.2 times as that of uncrusted soil, while the reduction of raindrop kinetic energy by cyano crust with high biomass was 1.3 and 6.6 times as that of medium and low biomass, respectively. Under the single raindrop and simulated rainfall conditions, biocrusts reduced splash erosion amounts by 47.5% and 79.4%, respectively. The proportion of aggregates >0.25 mm in the splash soil particles of biocrusts (37.9%) was 40.3% lower than that of uncrusted soil, while the proportion of aggregates >0.25 mm decreased as biocrust biomass increased. Moreover, the aggregate stability, splash erosion amount, and fundamental properties of biocrusts were significantly correlated. The MWD of aggregates was significantly and negatively correlated with the splash erosion amount under single raindrop and simulated rainfall conditions, indicating that the improved aggregate stability of surface soil caused by biocrusts accounted for reducing splash erosion. The biomass, thickness, water content, and organic matter content of biocrusts had significant effects on aggregate stability and splash characteristics. In conclusion, biocrusts significantly promoted soil aggregate stability and reduced splash erosion, which had great significance to soil erosion prevention and the conservation and sustainable utilization of Mollisols.

Study on liquid-solid jet erosion characteristics of 316L stainless steel

Study on liquid-solid jet erosion characteristics of 316L stainless steel

SUPPORT VECTOR MACHINE LEARNING ON SLURRY EROSION CHARACTERISTICS ANALYSIS OF Ni- AND Co-ALLOY COATINGS

In this paper, a novel support vector machine (SVM) learning approach has been used to predict the silt erosion of coatings sprayed by the high-velocity oxy-fuel (HVOF) process. The silt erosion resistance of HVOF-coated Co- and Ni-alloys is studied using an erosion tester. Both of these spraying powders were deposited on the 18Cr-12Ni-2Mo austenitic steel substrate. For the erosion experiments, the fixtures were developed to test the erosion characteristics at different impingement conditions (i.e. [Formula: see text], [Formula: see text], and [Formula: see text]). The image processing technique enables an understanding of the erosion mechanisms of coatings. The support vector regression is more effective than the traditional regression models. The proposed model employs support vector regression with parameter tuning. The ideal parameters are selected with the help of the grid search method. The model is trained by supplying 70% data and validated with 15% data. Afterward, the remaining 15% is given to the prepared model as testing data. The dataset obtained is employed for building an effective support vector regression model. The predicted results are compared against the original experimental values. The developed model is also compared with other state-of-the-art machine learning techniques for showing the preciseness of the proposed model. The Ni-based HVOF coating showed superior performance ([Formula: see text]) better than the Co-based HVOF coating under similar experimental conditions. An SVM model was successfully developed to predict the erosion of coated and uncoated 18Cr-12Ni-2Mo austenitic steel. The precision performance of the SVM model was calculated in terms of [Formula: see text], RMSE, [Formula: see text], and MAE as 0.99, [Formula: see text], 0.99, and [Formula: see text], respectively.

Analysis of Sediment and Water Flow and Erosion Characteristics of Large Pelton Turbine Injector

Based on the solid–liquid two-phase flow model, SST k-ω model, and Lagrangian equation model of particle motion, numerical simulations of the sediment–water flow in the injector of a large Pelton turbine were conducted. The distribution rules of pressure, velocity, erosion rate, and erosion location of the injector were obtained by analyzing the sediment–water flow characteristics and sediment erosion distribution characteristics of the injector. The results revealed that the velocity distribution trend of the water inside the cylindrical jet exhibited a nonlinear distribution, and the phenomenon of “velocity deficit” occurred at the end of the needle guide and needle tip, resulting in a decrease in the jet quality of the injector. The sediment particle diameter affected the erosion rate of the needle and erosion location of the needle and nozzle port ring. This study provided guidance for sediment erosion analysis and the prediction of the utility of large Pelton turbines.

Application of vertebral body compression osteotomy in pedicle subtraction osteotomy on ankylosing spondylitis kyphosis: Finite element analysis and retrospective study.

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease, with pathological characteristics of bone erosion, inflammation of attachment point, and bone ankylosis. Due to the ossified intervertebral disc and ligament, pedicle subtraction osteotomy (PSO) is one of the mainstream surgeries of AS-related thoracolumbar kyphosis, but the large amount of blood loss and high risk of instrumental instability limit its clinical application. The purpose of our study is to propose a new transpedicular vertebral body compression osteotomy (VBCO) in PSO to reduce blood loss and improve stability. A retrospective analysis was performed on patients with AS-related thoracolumbar kyphosis who underwent one-level PSO in our hospital from February 2009 to May 2019.A total of 31 patients were included in this study; 6 received VBCO and 25 received eggshell vertebral body osteotomy. We collected demographic data containing gender and age at diagnosis. Surgical data contained operation time, estimated blood loss (EBL), and complications. Radiographic data contained pre-operative and follow-up sagittal parameters including chin brow-vertical angle (CBVA), global kyphosis (GK), thoracic kyphosis (TK), and lumbar lordosis (LL). A typical case with L2-PSO was used to establish a finite element model. The mechanical characteristics of the internal fixation device, vertebral body, and osteotomy plane of the two osteotomy models were analyzed under different working conditions. The VBCO could provide comparable restoring of CBVA, GK, TK, and LL in the eggshell osteotomy procedure (all p > 0.05). The VBCO significantly reduced EBL compared to those with eggshell osteotomy [800.0ml (500.0-1,439.5 ml) vs. 1,455.5 ml (1,410.5-1,497.8 ml), p = 0.033]. Compared with the eggshell osteotomy, VBCO showed better mechanical property. For the intra-pedicular screw fixation, the VBCO group had a more average distributed and lower stress condition on both nails and connecting rod. VBCO had a flattened osteotomy plane than the pitted osteotomy plane of the eggshell group, showing a lower and more average distributed maximum stress and displacement of osteotomy plane. In our study, we introduced VBCO as an improved method in PSO, with advantages in reducing blood loss and providing greater stability. Further investigation should focus on clinical research and biomechanical analysis for the application of VBCO.

Influence of Precipitation Effects Induced by Large-Scale Irrigation in Northwest China on Soil Erosion in the Yellow River Basin

Large-scale irrigation can alter the regional water cycle process, which changes the structure and spatiotemporal distribution of local and downwind precipitation, impacting soil erosion in both the irrigated areas and the surrounding regions. However, the effects of large-scale irrigation on soil erosion in downwind vulnerable areas have not been investigated. The study used the high-resolution regional climate model (RegCM4) and the revised universal soil loss equation (RUSLE) to examine the effects of irrigation-induced precipitation in Northwest China on the frequency, distribution, and intensity of precipitation in the Yellow River Basin (YRB) under different Representative Concentration Pathways (RCPs). The response characteristics of soil erosion to the irrigation-induced precipitation effects and its relationship with slope, elevation, and land use type were analyzed as well. The results indicate that soil erosion in most regions of the YRB is below moderate, covering 84.57% of the basin. Irrigation leads to a 10% increase in summer precipitation indices (e.g., total wet-day precipitation, consecutive wet days, number of wet days with precipitation ≥ 1 mm, and number of heavy precipitation days with precipitation ≥ 12 mm) in the northwest of the basin. Irrigation also leads to a change in local circulation, resulting in reduced precipitation in the southeast of the basin, particularly under the RCP8.5 scenario. The transformation of erosion intensity between low-grade and high-grade erosion is relatively stable and small under the influence of precipitation. However, soil erosion changes display strong spatial heterogeneity, inter-annual and intra-annual fluctuations, and uncertainties. The findings of this study can be helpful for policymakers and water resource managers to better understand the impacts of large-scale irrigation on the environment and to develop sustainable water management strategies.

Cavitation Erosion Characteristics of the EN AW-6082 Aluminum Alloy by TIG Surface Remelting.

Components made of aluminum alloys operating under cavitation erosion conditions have low performance and therefore a reduced lifetime. The degradation of these components is a consequence of the repetitive implosion of cavitation bubbles adjacent to the solid surface. In this paper, the effect of the rapid re-melting and solidification modification of the surface microstructure of parts of an Al-based alloy strengthened by artificial ageing on the reduction of material loss through cavitation erosion was investigated. The heat source used was the electric arc generated between a tungsten electrode and the workpiece (i.e., TIG). Local surface melting was performed at different values of linear energy (El = 6600-15840 J/cm), varying the current between 100 A and 200 A, at a constant voltage of 10 V. The obtained results showed an increase in the surface microhardness at values of 129-137 HV0.05 and a decrease in the erosion rate from 0.50 µm/min, characteristic of the artificial ageing heat treatment, to 0.10-0.32 µm/min, specific to TIG re-melted layers. For the study of the cavitational erosion mechanism, investigations were carried out by optical microscopy and scanning electron microscopy. The results showed that the improvement of the cavitational erosion resistance by surface melting was a consequence of the increase in microstructural homogeneity and grains refinement.

Understanding the slurry erosion behaviour of iron-based chromium carbide coating material during deposition via arc spray coating method

The material S235JR was spray-coated with iron-based chromium carbide in the present study. The effects of the initial surface roughness on slurry erosion were investigated. Samples with a rough surface and polished surface were used. The impact of particle concentration, impact velocity and impact angle was studied on the slurry erosion characteristics in terms of mass loss, surface roughness and surface temperature. In addition, the surfaces were analysed using a scanning electron microscope (SEM). Further, the estimation equation has been derived using response surface method (RSM) based on the data obtained in the study. The results show that velocity and concentration are the key factors in determining the mass loss and surface temperature while the impact angle has a relatively minor role. Mass losses in rough samples ranged from 8.8 mg to 40 mg; in polished samples, the range ranged from 5.6 mg to 10.9 mg.

Spatiotemporal variations of freeze-thaw erosion risk during 1991–2020 in the black soil region, northeastern China

Freeze-thaw (FT) erosion, which occurs in high-altitude and high-latitude regions, has a considerable impact on water and wind erosion. However, studies on long-term variations of FT erosion induced risks are still limited. In the present study, based on 30-year data at 247 meteorological stations, spatiotemporal FT erosion risk in the black soil region, northeastern China was evaluated through the Analytical Hierarchy Process (AHP) and Entropy-weight method (EWM). Six FT erosion-related variables, including annual FT cycle days, soil water content (SWC), fraction vegetation coverage (FVC), slope, soil bulk density (BD), and soil structural stability (SSI) were used to assess FT erosion risk in the study region. Among these variables, the slope was the most important variable (45 %), followed by annual FT cycle days (15 %), FVC (15 %), and SSI (14 %). FT erosion risk differed in different land use types. Woodland, residential land and grassland suffered severe FT erosion risk, and paddy and dryland suffered slight FT erosion risk. Complex topography areas had a higher FT erosion risk. During past 30 years, global warming mitigated the FT erosion risk. This study can help understand soil erosion characteristics and soil loss control for the Chinese black soil region and similar regions in the world.

Experimental research on the erosion characteristics of organ-pipe cavitating jet for hydrate-bearing sediments

Cavitating jet is regarded as a promising breaking rate improvement technology in both the marine natural gas hydrate (NGH) fluidization exploitation method and the integrated radial jet drilling and completion method. Experimental studies on the influences of standoff distance, erosion time, inlet flow rate and hydrate saturation on hydrate-bearing sediments (HBS) breakage by organ-pipe cavitating jet (OPCJ) were conducted. The methane HBS synthesized in laboratory were employed as the experimental samples. The breaking effect were evaluated by four quantifiable indicators: erosion pit volume and maximum depth, and jet specific energy and specific cutting energy. Results show that under the same inlet flow rate, the standoff distance and erosion time have significant influences on the erosion pit shape. For the erosion pit volume and depth, the optimal standoff distances are respectively 4 mm and 5 mm (the diameter of nozzle is 1 mm), in which condition the OPCJ efficiencies of erosion and penetration on HBS are greatly improved. The ultimate erosion depth is 215 mm at an inlet flow rate of 0.085 L/s. The critical breaking velocities of OPCJ and conical jet (CJ) on HBS with hydrate saturation of 50% are respectively estimated to be 17.8 m/s and 24.2 m/s. Increasing hydrate saturation significantly decreases the erosion efficiency of OPCJ on HBS. The inlet flow rate is the most significant factor for the erosion pit volume and depth. This study provides a reference on the potential field applications for the NGH fluidization exploitation method and the integrated radial jet drilling and completion method.

Spatiotemporal Variation of Soil Erosion Characteristics in the Qinghai Lake Basin Based on the InVEST Model

The present study aims to quantitatively assess soil erosion intensity (SEI) and amounts in the Qinghai Lake Basin (QLB) over the 1990-2020 period using the Integrated Valuation Ecosystem Services and Tradeoffs (InVEST) model based on multi-source data. In addition, the changing trends and driving factors of soil erosion (SE) in the study area were systematically analyzed. The result showed: (1) An increasing-decreasing trend in the total soil erosion amount (SEA) in the QLB over the 1990-2020 period, with an average SEI of 579.52 t/km2. In addition, very low and low erosion classes covered 94.49% of the total surface area, while areas with high SEI were mainly distributed in alpine areas with low vegetation coverage (VC). (2) The highest average SEI was observed in bare land, while grassland and unused land were the main land use (LU) types where SE mainly occurred, with the ratio of the two being 95.78%. (3) The average value of SEI was positively correlated with altitude values below 4800 m. In addition, areas with altitude ranges of 4000-4400 m, 3600-4000 m, and 4400-4800 m were the main areas where SE occurred, with an average total soil erosion ratio (SER) value of 88.73%. (4) The average SEI was directly proportional to the slope degrees. SE occurred mainly in the areas with slope degree ranges of 15-25°, 25-35°, 8-15°, and >35°, accounting for 93.16% of the average total SER value. (5) The q value of the two-factor interaction was greater than that of the single-factor interaction. In addition, the areas with a high SE risk were mainly those with 1220-2510 m rainfall, <0.104 VC, the land use/land cover (LULC) type bare land, the altitude range 4400-4800 m, and a slope of >35°. The interaction between rainfall, VC, LULC, elevation, and slope had a significant impact on the spatial distribution of SEI.

Effect of a soluble subgrade on leakage through a geomembrane defect

Leakage and erosion of a soluble subgrade overlain by a geomembrane with a 70-mm-long slit defect is examined. The subgrade (gypsum) solubility and its rate of dissolution from a solid state in contact with various solutions are investigated. In the absence of flow, the rate of dissolution is negligible. However, when there is flow there is dissolution, and if the flow is high enough, erosion. Erosion greatly increases fluid migration. The presence of an interface between the subgrade and a dissimilar material (e.g. a geomembrane) facilitates flow, dissolution, and erosion as the interface becomes an ever increasing preferential flow path, leading to a much greater leakage and erosion feature. The findings from this study highlight the risk of having a soluble subgrade below a single geomembrane used alone and exposed for the containment of liquids.

Study on the Influence of Initial State on Loess Erosion Characteristics and Microscopic Mechanism

Because of its loose, porous, and vertical structure, loess easily absorbs water, and it contains a large amount of soluble material, making it susceptible to erosion by water flow from rainfall or irrigation, with potentially disastrous consequences. Damage can result especially from loess slope erosion. In this paper, physical tests and microscopic analysis are used to study loess erosion. The purpose is to explore the internal structure of the soil caused by the infiltration of the water body when it flows through the loess slope, and thus to learn more about the internal mechanisms of surface erosion caused by the migration and relocation of the soil particles on the surface of the slope. Erosion tests of samples with different dry density and water content were carried out. It was found that the amount of erosion decreases with an increase of dry density and increases with an increase of water content. Through physical simulation tests combined with field investigation and analysis, the entire erosion process is divided into four erosion characteristic stages: uniform surface erosion; micro drop pit erosion; micro drop pit bead erosion; and rill erosion. The erosion mechanism and micro mechanism of different erosion characteristics are analyzed and summarized. The influences of different dry density and water content on the erosion process are analyzed and summarized, and the internal mechanism of erosion is revealed from the perspective of microstructure, thereby providing a sound basis for engineering construction and erosion-related disaster management in the Loess Plateau.

Numerical and experimental investigation on the effect of surface curvature and slope angle on the material removal characteristics in fluid jet polishing

Fluid jet polishing (FJP) has been extensively utilized in the ultra-precision manufacturing of freeform optical components and molds. The form accuracy is mainly improved by controlling the polishing dwell time at different positions, which is determined by the deconvolution of the initial form error and tool influence function (TIF). However, in previous studies, the erosion-induced TIF is considered constant without accounting for the freeform surfaces' curvature and slope angle variations. Due to the deviation of TIF, it is still a challenge to achieve a high form accuracy for freeform surface polishing. In this paper, the TIFs in freeform surface polishing have been modeled by computational fluid dynamics (CFD) analysis. A series of spot polishing experiments subsequently were conducted on the surfaces with different curvature radii and slope angles. The experimentally measured data including cross-section profiles of polishing spots, Peak-to-valley (PV) value, and material removal rate are found to agree well with the model simulation results, which verified the effectiveness of the CFD model. The effect of surface curvature and slope angle on the material erosion distribution was investigated and revealed by the fluid flow field distribution, abrasive impact, and abrasive trajectories. This paper not only provides a deep scientific understanding of the material erosion characteristics in FJP of freeform surfaces, but also offers a simple and cost-effective solution to build the database of TIFs on freeform surfaces under various conditions, which is beneficial for the ultra-precision form control during FJP of freeform surfaces.

Spatial distribution characteristics of sediment connectivity and soil erosion in small watershed in brown soil hilly region of low mountains in western Liaoning Province, China.

Understanding the spatial distribution characteristics of soil erosion and sediment connectivity is important for formulating integrated watershed management measures. Based on the InVEST sediment delivery ratio model, we used the connectivity index and soil loss model to measure the spatial distribution characteristics of sediment connectivity and soil erosion in Erdaoling watershed of brown soil hilly region of low mountains in western Liaoning. By exploring slope, aspect and land use characteristics under different sediment connectivity levels and soil erosion levels, we analyzed the relationships among topography, land use, sediment connectivity, and soil erosion. The results showed that the average sediment connectivity in the watershed was -3.79, and that the average soil erosion was 614 t·km2·a-1. High connectivity was mainly found in sloping farmland, while low connectivity was mainly found in forest and grassland. The soil erosion intensity of 93.3% of the watershed area was below moderate, with only 1.1% of the area being above extremely strong. The higher the sediment connectivity level, the higher the proportion of the area <5° slope, while the area proportion of the rest slope was relatively stable. The proportion of cultivated land area increased, while the proportion of forest and grassland land area decreased. The area proportion on negative slope decreased, while that on positive slope increased. With increasing soil erosion intensity, the area proportion of slope <8° increased and the area proportion of the rest slope was relatively stable. The proportion of forest and grassland area decreased, while the proportion of other land use area increased. The proportion of slope area on positive slope increased, while that on negative slope decreased. Land use was a key factor influencing the spatial response relationship between soil erosion and sediment connectivity in this watershed.

Performance of soil and water conservation practices in the erosion evolution process, runoff dynamics and surface roughness

AbstractSoil and water conservation practices are used widely to prevent soil erosion and protect soil and water resources, which is significant for ecological restoration and food security. However, rill evolution processes, erosion and deposition characteristics and critical hydrodynamic parameters need more research. In order to investigate the effect of soil and water conservation practices on soil erosion dynamics, simulated rainfall experiments were undertaken in a laboratory on 15° loess slopes with engineering measures (fish‐scale pits, FSPs), tillage measures (artificial digging, AD; contour ploughing, CP) and bare slope (CK). The results showed that: (1) during rill erosion, hillslopes with FSPs, CP and AD were more likely to develop wide and shallow rills, while a bare slope (CK) was more likely to develop narrow and deep rills. At the end of the experiment (cumulative rainfall was about 150 mm), headward retreat erosion dominated the AD slope (maximum rill length: 3.27 m), side‐wall expansion erosion dominated the CP slope (maximum rill width: 0.522 m) and bed incision erosion dominated the CK (maximum rill depth: 0.09 m); (2) soil and water conservation practices reduced surface erosion and sediment transport and runoff velocity. However, the positive effects disappeared when rainfall amounts exceeded 82.5, 105 and 127.5 mm for FSPs, CP and AD, respectively; (3) for runoff kinetic energy and runoff shear strength of 3 J and 1.5 N/m2, respectively, soil and water conservation measures had greater anti‐erosion abilities than CK; (4) as rainfall duration increased, surface roughness, runoff rate and sediment concentration increased on the CK and FSP treatments, but decreased on the CP and AD treatments. This study has important implications for managing different soil and water conservation measures based on rainfall conditions and offers a deeper understanding of soil erosion processes.

Assessing the erosion characteristics and relationship with geotechnical properties for soils at the Red Riverbank, Hanoi, Vietnam

Assessing the erosion characteristics and relationship with geotechnical properties for soils at the Red Riverbank, Hanoi, Vietnam

Effect of exposed roots on the erosion characteristics of sloped land based on close-range photogrammetry in a karst rocky desertification region

On sloped land in karst rocky desertification regions, some roots gradually become exposed to the surface due to the low soil-forming rate of the parent rock and shallow natural soil layer. The spatial orientation of these roots varies with the terrain as the plants grow and the surrounding surface erodes. In previous studies, the exposed roots were often used to estimate erosion intensity, but little is known about how exposed roots influence the erosional characteristics of sloped land. In this study, the effects of the orientation of the exposed roots (vertical slope arrangement, parallel slope arrangement, transverse slope arrangement) on the erosion characteristics of sloped land were investigated based on close-range photogrammetry and simulated rainfall experiments. The results showed that there were differences in the responses of the sloped land to erosion based on the different orientations of the exposed roots. In the first four rainfall events, the surface runoff rate was the highest for the parallel slope arrangement, followed by the vertical slope arrangement and transverse slope arrangement. With the occurrence of intermittent rainfall events, this difference gradually decreased. The exposed roots affected the erosional characteristics of sloped land by interfering with the runoff flow path. In most rainfall events, the general trend of eroded sediment yield was parallel slope arrangement > vertical slope arrangement > transverse slope arrangement. The digital elevation model (DEM) constructed by close-range photogrammetry showed that the surface microtopography changed during intermittent rainfall, which resulted in the difference in the relief of sloped land with different exposed root distribution patterns. The volume of soil detached and transported along slopes with parallel slope arrangement was more severe than that on transverse and vertical slopes because the shallow gullies between exposed roots provided a good transport channel for runoff along sloped land. These results provide a reference for understanding the relationship between plant roots and erosion processes in regions of karst rocky desertification.

Experimental study of shock pressure and erosion characteristics of high‐pressure gas–liquid two‐phase jet: Exploration for improving coalbed methane extraction efficiency

AbstractCoalbed methane extraction promotes energy exploitation and alleviates the greenhouse effect. This study aimed to analyze the technical potential of a high‐pressure gas–liquid two‐phase jet in increasing coalbed permeability and promoting coalbed methane extraction. A well‐designed experimental setup was used to investigate the erosion characteristics of a high‐pressure gas–liquid two‐phase jet. Through the shock pressure monitoring and erosion tests of the jet, the effects of pump pressure, mixer structure, and nozzle structure on the shock pressure and rock‐breaking performance were studied, and the rock‐breaking mechanism of the high‐pressure gas–liquid two‐phase jet was examined. The results showed that the nonuniformity of mixing and the expansibility of high‐pressure gas continually alters high‐pressure gas–liquid two‐phase jets between single and multiple streams, which makes the jet show obvious pulse effects and considerably improves the rock‐breaking performance. Furthermore, reasonable air pump pressure and water pump pressure settings significantly increase the shock area, whereas the maximum shock pressure only decreases slightly. Although the shock pressure of a high‐pressure gas–liquid two‐phase jet decreases with the increase in air pump pressure, its shock efficiency first increases and then decreases with the increase in air pump pressure. To improve the erosion efficiency of a high‐pressure gas–liquid two‐phase jet, the settings of the air pump pressure and water pump pressure is crucial, but the optimal air pump pressure differs for different water pump pressures. Additionally, the greater the angle between the gas and liquid inlets, the greater the energy loss of the fluid during the mixing. Finally, the rock‐breaking performance showed that the optimal nozzle structure is the single‐cone nozzle.

TET1 and TDG Suppress Inflammatory Response in Intestinal Tumorigenesis: Implications for Colorectal Tumors With the CpG Island Methylator Phenotype

Aberrant DNA methylation is frequent in colorectal cancer (CRC), but underlying mechanisms and pathologic consequences are poorly understood. We disrupted active DNA demethylation genes Tet1 and/or Tdg from ApcMin mice and characterized the methylome and transcriptome of colonic adenomas. Data were compared to human colonic adenocarcinomas (COAD) in The Cancer Genome Atlas. There were increased numbers of small intestinal adenomas in ApcMin mice expressing the TdgN151A allele, whereas Tet1-deficient and Tet1/TdgN151A-double heterozygous ApcMin colonic adenomas were larger with features of erosion and invasion. We detected reduction in global DNA hypomethylation in colonic adenomas from Tet1- and Tdg-mutant ApcMin mice and hypermethylation of CpG islands in Tet1-mutant ApcMin adenomas. Up-regulation of inflammatory, immune, and interferon response genes was present in Tet1- and Tdg-mutant colonic adenomas compared to control ApcMin adenomas. This up-regulation was also seen in murine colonic organoids and human CRC lines infected with lentiviruses expressing TET1 or TDG short hairpin RNA. A 127-gene inflammatory signature separated colonic adenocarcinomas into 4 groups, closely aligned with their microsatellite or chromosomal instability and characterized by different levels of DNA methylation and DNMT1 expression that anticorrelated with TET1 expression. Tumors with the CpG island methylator phenotype (CIMP) had concerted high DNMT1/low TET1 expression. TET1 or TDG knockdown in CRC lines enhanced killing by natural killer cells. Our findings reveal a novel epigenetic regulation, linked to the type of genomic instability, by which TET1/TDG-mediated DNA demethylation decreases methylation levels and inflammatory/interferon/immune responses. CIMP in CRC is triggered by an imbalance of methylating activities over demethylating activities. These mice represent a model of CIMP CRC.