Loose Layer Research Articles

A Novel Self-Pumping Janus Dressing for Promoting Wound Immunomodulation and Diabetic Wound Healing.

Self-pumping dressings become one of the optimal solutions for the controlled management of chronic diabetic wound exudate and wound healing. However, present self-pumping dressings are not only prone to breakage of the loose hydrophobic layer but also have cumbersome and complicated preparation steps, which hinder the application of self-pumping dressings in diabetic wound treatment. Herein, a novel self-pumping structure of superabsorbent Janus dressing is designed to improve the strength of the hydrophobic layer and promote diabetic wound healing. The Janus dressing consists of a hydrophobic layer with a drainage agent (drainage layer) and a fluffy 3D nanofiber cotton (absorbent layer). Regardless of the thickness of the drainage layer, the drainage agent in the drainage layer provides the fluid to penetrate the drainage layer to the absorbent layer for unidirectional fluid draining. In design proof, the superabsorbent Janus dressing provides unidirectional drainage of inflammatory exudate and regulation of macrophage polarization, resulting in faster diabetic wound healing than single-layer dressings. Thus, the Janus dressing demonstrates important clinical implications to offer a novel design and preparation strategy for accelerating diabetic wound healing.

Numerical investigation of jacking method for asymmetric settlement rectification in tilted concrete buildings

In the town of Fereshteh, Tabriz, Iran, there is a growing concern regarding the tilting of recently constructed buildings. This uneven settlement issue can be primarily attributed to variations in loose fill material thickness, elevated groundwater levels, and the presence of loose sandy layers intermixed with clayey layers. The challenges posed by these tilted structures are further compounded when dealing with historically significant buildings, making demolition an undesirable and wasteful solution. Therefore, alternative restoration methods must be explored. This study focuses on the application of the jacking technique to rectify the tilt observed in reinforced concrete buildings ranging from four to eight stories in height. To simulate the rectification process, numerical modeling using the finite element method was employed. The strategic placement of jacks was critical, as they applied force until the foundation achieved equal vertical displacement on both sides or until the uneven settlement was reduced to an acceptable level. Ensuring the structural integrity of the building during this rectification process was of paramount importance to prevent cracking or collapse due to the forces exerted by the jacks. Elements on the first floor experienced significantly higher internal forces compared to their counterparts on upper floors. Stress concentration was notably observed at the intersection point of the columns and the foundation surface. This highlights the critical importance of positioning the jacks directly beneath the axis of the columns or bearing elements to ensure effective rectification. Based on the results obtained for the studied structures, it becomes evident that employing the jacking method becomes unfeasible when a section of the raft experiences a settlement exceeding 10 cm. This is due to the drastic change in stress distribution conditions within the structural components under such circumstances. However, the jacking method remains a viable and effective solution for settlements below this threshold, rectifying uneven structural settlements without causing harm to the structural elements.

MR Diffusion Kurtosis Imaging (DKI) of the Normal Human Uterus in Vivo During the Menstrual Cycle.

The uterus undergoes dynamic changes throughout the menstrual cycle. Diffusion kurtosis imaging (DKI) is based on the non-Gaussian distribution of water molecules and can perhaps represent the changes of uterine microstructure. To investigate the temporal changes in DKI-parameters of the normal uterine corpus and cervix during the menstrual cycle. Prospective. 21 healthy female volunteers (26.64 ± 4.72 years) with regular menstrual cycles (28 ± 7 days). Readout segmentation of long variable echo-trains (RESOLVE)-based DKI and fast spin-echo T2-weighted sequences at 3.0T. Each volunteer was scanned during the menstrual phase, ovulatory phase, and luteal phase. Regions of interest (ROI) were manually delineated in the endometrium, junctional zone, and myometrium of the uterine body, and in the mucosal layer, fibrous stroma layer, and loose stroma layer of the cervix. The mean Kapp (diffusion kurtosis coefficient), Dapp (diffusion coefficient), and ADC (apparent diffusion coefficient) values were measured in the ROI. ANOVA with Bonferroni or Tamhane correction. Intraclass correlation coefficient (ICC) for assessing agreement. P < 0.05 was considered statistically significant. During the menstrual cycle, the highest Kapp (0.848 ± 0.184) and lowest Dapp (1.263 ± 0.283 *10-3 mm2/sec) values were found in the endometrium during the menstrual phase. The Dapp values for the myometrium were significantly higher than those of the endometrium and the junctional zone in every phase. Meanwhile, the Dapp values for the three zonal structures of the cervix during ovulation were significantly higher than those during the luteal phase. However, there was no significant difference in the ADC values of the loose stroma between ovulation and the luteal phase (P = 0.568). The reproducibility of DKI parameters was good (ICC, 0.857-0.944). DKI can show dynamic changes of the normal uterus during the menstrual cycle. 2 TECHNICAL EFFICACY: Stage 2.

Effect of biochar aging in agricultural soil on its wetting properties and surface structure

Biochar wettability and ability to accumulate moisture inside the porous space are crucial for improving soil fertility, regulating soil water balance, and regulating nutrients. However, a long-term interaction of biochar with agricultural soils may drastically alter the wetting properties and, eventually, influence water holding capacity and the structure of soils. In this work, the structure and wetting properties of biochar samples after 6-year long exposure to a sandy loam Spodosol with a crop rotation and mineral fertilizers application were studied. It was found that the elemental composition of the aged biochars was richer and more "soil-like", which is explained by the presence of the mineral crust on the biochar surface. The temporal evolution of biochar in the soil without any mineral fertilizer application resulted in significant improvement of its surface wettability due to the effects of various environmental factors. The lateral surface of biochar after 6-year interaction with the soil changes into a loose porous layer in a form of grooved base filled with adherent mineral soil and clay particles. Contrary, the application of the mineral fertilizer to the soil resulted in decreased wettability of the biochar lateral surfaces due to a decrease in the polar component of surface energy and the crusting of the surface with fine material, which blocks the pore space of the biochar. As a result, water capacity of the biochar from the treatment with the fertilizer decreased compared to the biochar samples collected from the soil without the fertilizer application. The radial biochar surfaces of both types of samples collected from the soil were open vessels filled with soil particles that slow down complete wetting and water absorption. The treatment of the biochar samples with surfactants drastically increased wettability of lateral surface and water absorption capacity of control samples as compared to the samples collected from the soil. The obtained results support the idea that the hydrophilisation of biochar caused by the adhesion of soil particles and treatment of its pore surface with surfactants, can improve the water-holding capacity of the sandy loam Spodosol in the plant-available range of soil water.Graphical

Synergistic effect of ozone and non-oxidizing bacteriostatic agent on biofouling control of reverse osmosis membranes

Biofouling was the critical flaw of the reverse osmosis (RO) process. Both strong oxidizing and non-oxidizing bacteriostatic agents had obvious defects facing this problem. This study firstly compared the single and synergistic effect of a strong oxidizing agent (ozone) and a commercial non-oxidizing bacteriostatic agent (FR110) on RO membrane fouling control of reclaimed water, to find a more high-efficiency and practical approach. Consequently, the synergistic application of ozone and FR110 at low dosages effectively reduced the fouling of the RO membranes (18% normalized flux alleviation than the control group). Further analysis suggested that FR110 could induce a thinner fouling layer, while ozone pretreatment could lead to a loose fouling layer. The bacterial community analyses suggested that the relative abundance of biofouling-related genera was the key reason causing fouling differences. Phenotypic prediction confirmed the advantages of the synergetic application of FR110 and O3 in reducing the biofilm-forming capacity. Pure-strain experiments showed the synergetic application of FR110 and O3 could inhibit the overgrowth and secretion of certain biofilm-forming strains, such as Pseudomonas aeruginosa PAO1. In summary, synergistic disinfection was a promising way to regulate the bacterial community structure and biofilm-forming potentials, hoping for high-efficiency biofouling control in the RO system.

Bearing Capacity of Skirted Ring Footing on Dense Sand Overlying Loose Sand

Introduction: The ultimate bearing capacity of an unskirted/skirted ring foundation on dense sand overlying loose sand is estimated using finite element analysis in this study. Methods: The range of thickness ratio (thickness of top dense sand layer divided by external diameter of ring) was kept between 0.25 and 1.5. The friction angle of the upper dense and bottom loose sand layers was maintained between 40° and 44° and 30° and 34°, respectively. In the case of skirted ring footing, the skirts are attached at the inner edge, outer edge, and both the edges, respectively. Results: According to the results, the bearing capacity increases with an increase in either the friction angle of upper dense and lower loose sand layers or the thickness ratio. A double-skirted ring footing was observed to provide the greatest bearing capacity, followed by footing with skirts attached at the outer and inner edges, respectively. Conclusion: To sum up, the bearing capacity of the ring footing was higher than the circular footing for the given friction angle of the top and bottom layer and thickness ratio.

Study on different reinforcement methods of inclined liquefiable site

The existing earthquake damage investigations indicate that the lateral spreading of site is more likely to occur in inclined liquefiable site under earthquake, therefore the way of foundation reinforcement is often adopted to reduce the lateral spreading phenomenon of inclined liquefiable site. In order to study the reinforcement principle of inclined liquefiable site by the two reinforcement methods of concrete pile and gravel pile, based on the verified numerical model of free field model, the model of concrete pile reinforcement and crushed rock pile reinforcement was established, the dynamic response and reinforcement effect of two different reinforcement methods in inclined liquefiable site were analyzed, and the effects of buried depth and pile diameter on the earthquake dynamic response and the effects of different reinforcement models are discussed. It is found that the concrete pile has a better reinforcement effect on inclined liquefiable site than gravel pile under the same buried depth and pile diameter. When the concrete pile is adopted to reinforce the inclined liquefiable site, the reinforcement effect is better when the concrete pile are embedded in dense sand layer at a certain depth; When adopting the gravel pile to reinforce inclined liquefiable sites, the effect is better when only clay and loose sand layer are reinforced, moreover, increasing the diameter of gravel piles greatly improves the reinforcement effect of inclined liquefiable sites. The pile group reinforcement model can greatly reduce the lateral displacement of site soil compared with the single pile reinforcement model.

Engineering antifouling membrane with surface segregation agents bearing crosslinked low surface energy segments

Low surface energy material has been considered as the promising material to solve membrane fouling owing to its superior fouling releasing ability, however, its low water wettability would result in decrease of water permeability, which limits its broad application in fabrication of high-performance membranes. Herein, we prepared the amphiphilic crosslinked surface segregation agents based on hydrophilic polyethylene glycol methyl acrylate (PEGMA) segments and crosslinked low surface energy poly(hexafluorobutyl methacrylate) (PHFBM) segments to fabricate antifouling membrane via nonsolvent induced phase separation. The surface segregation of the hydrophilic segments could drag the low surface energy segments onto membrane surface, meanwhile, the crosslinked structure of the low surface energy segment could influence the phase inversion to form a loose separation layer. As a result, amphiphilic membrane surface was constructed with hydrophilic microdomains and low surface energy microdomains as well as underwater superoleophobicity, and the flux of as-prepared membrane was increased slightly with the flux recovery ratio improved from 69.3 % to 92.8 % for separation of BSA solution. Meanwhile, after three cycles of filtration, the flux recovery ratio could maintain a high level. Our study may offer a new route to utilization of low surface energy materials for fabricating antifouling membranes.

Structural model and capacity determination of underground reservoir in goaf: a case study of Shendong mining area in China

The large-scale extraction of coal resources in the western mining areas of China has resulted in a significant loss of water resources, which is a challenge for coordinating resource extraction with ecological preservation in the mining areas. Although underground reservoir technology can effectively solve this problem, measuring the storage capacity of underground reservoirs through engineering experiments is costly and time-consuming. Currently, there is a lack of accurate, reliable, and low-cost theoretical calculation solutions, which greatly restricts the promotion and application of underground reservoir technology. The theoretical calculation methods for underground reservoir capacity were studied based on parameters from the Shendong mining area in China. A water storage structure model for coal mine underground water reservoirs was established, taking into account the settlement boundaries of the bedrock and loose layers in shallow coal seams, based on the key layer theory and the spatial structure model of the mining roof. The mathematical expression for the load on the coal-rock mass in the goaf was derived considering the rock breaking characteristics of the mining roof. The model determined the range of each water storage area, including the zone of loose body, zone of gradual load, and the compacted zone, based on the strength of the water storage capacity. The key parameters for calculating the water storage capacity were determined using a modified model for shallow thick loose layers and thin bedrock movement. Finally, a calculation method for the storage capacity was obtained. Based on the real data from the 22,615 working face of a mine in the Shendong mining area, the water storage capacity of the underground reservoir in the goaf was jointly calculated using FLAC3D, Surfer 12.0 and the proposed calculation method. The calculated water storage capacity was approximately 1.0191 million m3. Although this result was 2.20% smaller than the on-site water pumping experiment data, it still verifies the feasibility of the above calculation method for determining the water storage capacity of underground water reservoirs.

Boulder distribution, circular polarization, and optical maturity: A survey of example lunar polar terrains for future landing sites

Boulder occurrence at the southern polar regions of the Moon was analysed to see connections between optical, radio, spectral, and topography-related roughness datasets. On optical images, boulders tend to concentrate in groups (the groups are 0.9–1.8 km diameter and cover about 9% of the surveyed regions; while boulders inside these groups have up to 6 boulder/100 m2, e.g., 60,000 boulder/km2 (54% of areal coverage), while outside these groups around 7 boulder/km2 (0.06% areal coverage). The correlation between optical boulder density and Circular Polarization Ratio: CPR (0.26) and Optical Maturity: OMAT (0.38) values are weak, while CPR and OMAT distribution patterns are elevated around fresh craters with elevated boulder density. While fresh craters with boulders coincide with elevated CPR values, but in some cases, elevated CPR is without elevated surface boulder occurrence, indicating shallow subsurface boulders. A good correlation between CPR values and surface roughness (0.68) indicates boulder exhumation at topographic differences of craters. OMAT and CPR values of fresh craters (with elevated and sharp rims) show elevated values above the adjacent regions. OMAT is elevated up to 1–3 times the crater diameter, while CPR is elevated at a smaller area than OMAT values. The CPR might partly come from boulders that could not be ejected as far as smaller regolith grains indicated by OMAT-related freshness. Boulder occurrence at fresh impact craters indicates a thickness of the loose top porous regolith layer of 6–11 m, not far from those gained by another author (5–18 m) for terrain areas.

Sumatra-fault Earthquake Source Variation for Analysis of Liquefaction in Aceh, Northern Indonesia

Introduction: Areas that are situated on active faults experience a severe risk of earthquakes. During earthquake shocks, pore water pressure increases and soil shear strength decreases, resulting in water saturation of the loose sand layer and the possibility of liquefaction. Banda Aceh is a city on Sumatra Island, northern Indonesia, located on active faults that run along Sumatra Island. Aims: To ascertain the liquefaction potential in Banda Aceh City, it is important to conduct a research analysis on the soil profile below Banda Aceh City. This research focused on earthquake acceleration to determine the strength capacity of soil to withstand loads and wave propagation to minimize infrastructure failure. Methods: The liquefaction potential of Banda Aceh was determined by analyzing N-SPT records from three sites using three different approaches. This liquefaction study considered the cyclic loading and seismic acceleration associated with the Sumatra-fault earthquake source, which has a design magnitude of Mw 9.3. Results: The results of cyclic loading showed that Banda Aceh City has liquefaction potential. Using the 3D surface approach, soil profiling gives a cross-vault-shaped soil profile that shows liquefaction potential starting at 2.5 m and the hard soil layer found at 6.0 to 10 m. Conclusion: This study examined the liquefaction potential of Banda Aceh City. The research was carried out using a simplified approach to determine the liquefaction potential index (LPI) at three-dimensional cross faults of discontinuous sand generated by the Sumatra-fault acceleration of earthquake.

Research Results of the Improved Coulter Group of the Planter

Introduction. The article substantiates the design schemes of coulters and, in general, coulter groups of potato planters based on the morphological features of the potato plant, its requirements for growing conditions and ensuring the high-quality performance of the planting process. The purpose of the coulter groups is to form a bed for placing seed tubers with a loose soil layer of 5–8 cm and to cover seed tubers with loose soil to a certain depth. Aim of the Article. The study is aimed at developing technological scheme and substantiating constructive parameters of coulter groups of potato planters, which meet most requirements for the conditions of potato plant growing. Materials and Methods. A comparative analysis of force estimation of furrow-opening working bodies is carried out and qualitative indicators of technological process of planting are determined. There is developed an experimental design of coulter groups of potato planters with the system for automatic maintenance of the depth of potato planting by correcting the angle of coulter attack if there are the field relief irregularities. Results. Experimental studies optimized the parameters of a coulter suspension providing automatic maintenance of the depth of potato planting while detecting field micro-relief irregularities up to 20 cm deep within the initial requirements for potato planters. Discussion and Conclusion. The coulters with an individual floating suspension and an acute angle of entry into the soil most fully meet the requirements for the growing conditions of a potato plant. Automatic maintenance of the specified coulter travel depth within the initial requirements (±2 cm) with field micro- relief irregularities up to 200 mm is provided by a coulter group with a suspension aspect ratio of 150:200:400:400 cm.

Microplastic pollution in the groundwater under a bedrock island in the South China sea

Groundwater is the only freshwater resource on islands. Research on microplastic pollution in groundwater on islands is scarce. This study is the first to explore microplastic pollution in the groundwater under a bedrock island (Dawanshan Island) located in the South China Sea. The influence of hydrogeological factors on the distribution, source, and ageing features of microplastics in the groundwater were investigated. Despite the small scale of industrial and agricultural activities on the island, the amount of microplastics in the groundwater ranged from 34 to 64 particles/L, with over 80% of the microplastics being polyester fibres with diameters smaller than 2 mm, which is comparable to those in coastal cities. These microplastics were originated from inland plastic usage, rather than from the surrounding sea, which was confirmed by the lack of seawater intrusion on the island. Owing to the low permeability of granite, microplastics were mainly distributed in the water of the loose layer of porous sediment, and their quantity decreased with depth. In addition, the abundance of microplastics in pore groundwater increased with an increase in the velocity of groundwater flow. The severity of microplastic pollution in the groundwater increased with an increase and decrease in the content of total dissolved solids and dissolved oxygen, respectively. The microplastics originated from plastic waste disposed of on the island, rather than from seawater intrusion. Also, through groundwater infiltration into exposed soil at recharge areas, artificial wells at residential areas, and water exchange with surface water at valley areas. Microplastics buried in the groundwater aged faster along the migration path of the groundwater. These microplastics threaten the safety of people and plants on the island through exposure resulting from the extraction of groundwater for irrigation, while they endanger marine life through submarine groundwater discharge.

Effect of human chorionic gonadotrophin (HCG) and luteinizing hormone releasing hormone A3 (LHRH-A3) on reproduction and development of brood pouch in Hippocampus erectus

Syngnathid fishes (seahorses and pipefish) are unique in reproduction, with males becoming pregnant and giving birth. The brood pouch provides osmoregulation, gas exchange, waste transport, immunoprotection and nutrition supply. However, the function of hormone trafficking is rarely studied. By injecting the mixture liquor of human chorionic gonadotrophin (HCG, 2 IU/g) and luteinizing hormone-releasing hormone A3 (LHRH-A3, 5 ng/g) into the brood pouch of Hippocampus erectus, we found the reproductive interactions accelerated dramatically, and 4 pairs were successfully mated. After 24 h, the inner epithelium was highly folded and the loose connective tissue layer was highly distended. In the inner tissue layer of the brood pouch, fibroblasts secreted vigorously, blood vessels multiplied and expanded, indicating the physiological structure of the brood pouch modified hastily from the unpregnant stage to the progravid phase. Correspondingly, transcriptome results revealed the gene expression of circadian, epitheliogenesis, angiogenesis, lipid transfer, and spermiogenesis were significantly up-regulated. We innovatively found that macromolecule exogenous hormone (HCG) can be not only efficiently transported from brood pouch to body, but also promote mating and the physiological changes of the brood pouch.

Verification of Reinforced Surface Loose Layer of Zinc-Aluminum-Magnesium Steel Plate.

The corrosion resistance of zinc-aluminum-magnesium steel plates (Zn-Al-Mg steel plates) is significantly higher than that of galvanized steel plates. However, the unsatisfactory bonding performance of Zn-Al-Mg steel plates significantly limits their widespread application. In this study, X-ray photoelectron spectroscopy is employed to detect changes in the surface oxygen content of Zn-Al-Mg steel plates after different temperature treatments to confirm the existence of surface loose layers. In particular, changes in the surface oxygen content of the Zn-Al-Mg steel plates after the oxide layer is removed are investigated under saturated H2O vapor and O2 environmental conditions, and the cause of the formation of loose surface layers is determined. The uneven distribution of elements on the surface of the Zn-Al-Mg steel plates is investigated with scanning electron microscopy and energy dispersive spectroscopy. Nuclear magnetic resonance is employed to determine the size of the network spatial structure formed by silane coupling agents under different hydrolysis conditions and to further investigate the bonding performance of hydrolysate-modified Zn-Al-Mg steel plates. Several typical automotive adhesives are utilized to compare and examine the changes in the tensile strength of the Zn-Al-Mg steel plate bonding before and after modification with the silane coupling agent and analyze the structural damage of the adhesive at the bonding interface. The results confirm that the silane coupling agent strengthens the loose layer on the surface of the Zn-Al-Mg steel plate.

Ecotoxicological effects of co-exposure biodegradable microplastics polylactic acid with cadmium are higher than conventional microplastics polystyrene with cadmium on the earthworm

Microplastics (MPs) are plastic fragments with particle sizes <5 mm, ubiquitously distributed in terrestrial environments. However, the negative effects of MPs, such as joint-pollution with heavy metals on soil fauna remain controversial. This study investigated survival rate, growth, reproduction, avoidance behavior, histology, biochemical assays, comet assay, qPCR, Cd content, and IBR index. We found that six types of traditional MPs (PC, PP, PVC, LDPE, PET and PS, and PLA (a biodegradable microplastics)) had no adverse effects on earthworm growth, survival and reproduction. Moreover, we found that earthworms exhibit an avoidance behavior towards PLA. Both PS and PLA can exacerbated Cd pollution, leading to loose circular muscle layer, DNA damage in coelomocytes, and impaired antioxidant system due to increased reactive oxygen species (ROS). mRNA level of HSP70 increased under joint-pollution of both PS and Cd or PLA and Cd compared to Cd treatment alone. MPs enhanced Cd accumulation in earthworms in Cd-contaminated soil. Notably, the Integrated Biomarkers Response index revealed that the toxicity of joint PLA and Cd was greater than the joint effect of PS and Cd, which might violate the original intention of biodegradable plastics having non-toxic influence on the soil fauna. Our findings provide new insights into the ecotoxicological effects of MPs, the joint ecotoxicological effects of MPs and Cd on earthworms, and the ecological risks of MPs to soil fauna.

Characteristics of overlying strata and mechanisms of arch beam failure in shallowly buried thick bedrock coal seams: A case study in western China

AbstractThe Yangjiacun coal mine, located in western China, exhibits distinctive characteristics, such as its shallow depth, thick bedrock, thin loose layer, and unique roof strata breaking movement. In this research, a comprehensive analysis of previous exploration data, subsequent mechanical testing, key stratum theory, natural equilibrium arch theory, and simulation tests and numerical simulations has been conducted to investigate the failure behavior of the overlying rock strata in the Yangjiacun Coal Mine. Specifically, the load‐bearing capacity of the key stratum structure in the bedrock and the morphological properties of the arch‐beam structure have been thoroughly examined. A mechanical model of the roof rock arch‐beam structure has been established, and an analytical formula for the limit size and stability criterion of the arch‐beam structure has been derived. The mining‐induced rock arch‐beam structure plays a crucial role in transferring the load of the upper strata to the surrounding goaf, thereby preventing subsidence and deformation of the overlying strata. However, the arch‐beam structure periodically experiences instability during the advancement of the working face, gradually progressing towards the upper layer until the main key stratum is breached and the arch‐beam structure collapses. Based on the characteristics of weathered rock and the arch‐beam failure model in the Yangjiacun Coal Mine, quantitative backfilling mining methods have been proposed to either compensate for the mining void created by coal extraction or limit the size of exposed key strata through strip mining, ensuring the stability of the R6 key stratum. This study represents a significant contribution to understanding the intricate failure behavior of overlying rock strata in coal mines and provides a valuable framework for the responsible and efficient extraction of coal resources in similar environments.

Endogenous mucin conveyed to the mucosa with microbes can assure lumen fermentation and large intestinal security-swine versus fowl.

Endogenous protein leaving the ileum largely consists of accrued mucins from the upper gastrointestinal tract (GIT) that had resisted digestion. The amounts released rely on their mucosal generation during enteral feeding which vary with age as well as diet. These digestion resistant proteins of endogenous origin continue to be unavailable in the large intestine, whereas those of dietary origin provide amino acids that largely support the existing microbial population while denying limited amounts for absorption. Other mucins pre-exist within the large intestine as two layers at the lumen surface. A loose layer harboring a diverse microbial population is superimposed on the unstirred water layer (USWL) which simultaneously acts as an obstacle to microbes at the loose layer while performing as a molecular sieve for nutrients. The USWL is formed through interplay between enterocyte and goblet cells; however, the basis for presence of the loose layer is elusive. Large intestinal fermentation predominates within the colon of swine, whereas fowl employ their ceca. Motility within the colon of swine segregates fine materials into haustrae out-pocketings that parallel their placement within the ceca of fowl. Viscous mucins from small intestinal endogenous losses may envelop microbes within the large intestinal lumen to present successive adherents on the USWL that assemble its loose layer. The loose layer continually functions as a microbial reservoir in support of lumen fermentation. Microbial catabolism of mucin within the loose layer is known to be slow, but its proximity to the enterocyte is of advantage to enterocyte absorption with by-product amino acids fostering the USWL.

Influence of external insert angle on structural deformation of long pipe shed with shallow hole

The long pipe shed advanced support has the characteristics of large construction difficulty, wide support range, and easy deviation. The difference in construction dip angle will produce a different plastic zone of surrounding rock and supporting effects, and the rationality of advanced support design plays an important role in the safety of tunnel opening excavation. Based on the Tianshan Tunnel project, this paper aims at the problems of the loose pebble layer structure, poor cohesion, strong permeability, shallow excavation is not easy to form a confined arch, and easy to causes surrounding rock deformation and failure. Combined with the new method theory, the finite difference software FLAC3D was used to simulate seven excavation schemes of the shallow tunnel entrances. The mechanism and effect of advance support and the influence of construction angle on support effect are analyzed, and the simulation values are compared with the measured data. The results show that using long pipe shed advanced support can effectively reduce the disturbance of excavation to lose pebble rock mass and reduce the convergence value of surrounding rock. The plastic zone of surrounding rock produced by different angles can be divided into three parts. The structural stability difference of the C1 zone is small, and that of the C3 zone is large. The bending moment, shear force, and shape variables of the pipe shed decrease with the increase of the dip angle, while the axial force increases with the increase of the dip angle. According to the similarity between the simulated curve and the measured curve, the best supporting effect can be achieved when the dip angle of the pre-supporting pipe shed is set in the range of 0° ~ 3°.

Three-dimensional finite element analysis of the effect of soil liquefaction on the seismic response of a single pile

Soil liquefaction is considered as one of the most significant issues that leads to failure of shallow and deep foundations. However, the effect of liquefaction on the seismic response of piles still poorly understood. Therefore, this research examines the seismic response of a pile embedded in soil stratum of saturated fine-grained soils. Midas GTS/NX is used to carry out the number assessment. In addition, the modified UBCSAND soil constitutive model is used to depict the nonlinear features of saturated sand during earthquake waves. The developed three-dimensional model is first validated using the results of a shaking table test of a pile embedded in coarse-grained soil, where good agreement is obtained between the finite element model and the experimental results for the displacement, acceleration, and liquefaction ratio demonstrated good agreement. Furthermore, the orientations of the vectors produced by the numerical study, that matched a global circular flow characteristic, reflected the movement of the liquefied soil all around pile. The findings showed a considerable decrease in the pile frictional resistance during the seismic events as a consequence of increasing the pore water pressure and subsequent liquefaction. Regarding this, before the soil was entirely softened, resistance due to friction was observed near the ground, in correspondence with the loose sand layer. In addition, the pile showed excessive settling, which is due to the decrease of the soil stiffness caused by the increase of the pore water pressure. The results of this research provide an insight into the mechanism of the behavior of pile in saturated coarse-grained soils and thus, it helps to improve future research on the topic and also achieve better design of piles embedded in saturated coarse-grained soils.