Effect Of Water Immersion Research Articles

Effect of water immersion on pore structure of bituminous coal with different metamorphic degrees

It is important to understand the disaster-causing mechanism of dried water-immersed coal by investigating the influence of water immersion on the coal pore structure. In this study, low-temperature nitrogen adsorption experiments of eight bituminous coals with different metamorphic degrees and their dried water-immersed coals were carried out to analyze the adsorption/desorption mechanism and investigate the effects of water immersion on the pore shape, pore-structure parameters, and fractal dimension of coal. The results showed that adsorption of nitrogen on coal mainly includes micropore filling, monolayer adsorption, multilayer adsorption, and capillary condensation. The pores of coal were a continuous system from nanometer pores to relatively unlimited size pores. Water immersion did not significantly affect the pore shape of the coal, decreased the specific surface area and adsorption capacity, and increased the total pore volume and average pore diameter. It had the greatest effect on the average pore size of moderately metamorphosed coals, which may accelerate the oxidation process of coal and aggravate gas emission. The fractal results showed that water immersion reduced the surface fractal dimension of higher and lower metamorphic coal, while it increased that of moderately metamorphic coal, and it had the opposite effect on the structural fractal dimension.

Shear Strength Performance of Electrokinetic Geosynthetics Treated Soft Clay after Water Immersion

The strength aspect of clay soil is a critical concern in practical engineering design. Electroosmosis (EO) has been adopted as a foundation treatment technology in some projects to increase the strength of soft clay. In order to widen the understanding on shear strength performance of EO-treated soil, the behavior of EO-treated soft clay using electrokinetic geosynthetics (EKG) as electrodes under the effect of water immersion was evaluated and compared with that of vacuum preloading (VP) treated soft clay under similar conditions. The main finding was that the EO-treated soil when immersed in water offered more resistance to the change in average water content than VP-treated soil. The average shear strength of EO-treated soil fell by 36.6% during 4 extra days of immersion. When the immersion time was extended to 10 days, the average shear strength fell by 65.4%. In contrast, the immersion time had little influence on the shear strength of VP-treated soil. Hence, if EO-treated soft clays are to be subjected to short-term water immersion, the shear strength of the treated foundations should be reappraised to ensure the safety of the engineering projects.

Quantitative evaluation of the degradation amount of the silane coupling layer of CAD/CAM resin composites by water absorption.

Degradation of silane coupling layers by water ingress in computer-aided design/computer-aided manufacturing (CAD/CAM) of resin composites has been reported qualitatively. In this study, we quantitatively evaluated how water absorption of CAD/CAM resin composites affects the silane coupling layer by in vitro and in silico methods. A Katana Avencia block (KAB) and an experimental matrix block composed of only a matrix resin were used to evaluate the effect of water immersion for seven days on the elastic modulus. X-ray photoelectron spectroscopy (XPS) with fluorine-labeling of the KAB was performed to evaluate the atomic percentage of F1s, which represents the hydrolysis amount by water immersion. In silico analysis of the three-dimensional model of the KAB was performed to determine the coupling ratios before and after water immersion. The elastic modulus of the KAB was 8.2 GPa before and 6.9 GPa after immersion in water. The atomic percentages of F1s in the after- and before-immersion groups were 14.31% and 11.52%, respectively, suggesting that hydrolysis of the silane coupling layer occurred during water immersion. From in silico analysis of the three-dimensional model of the KAB, the coupling ratio was predicted to be 78.2% before water immersion. After water immersion, the coupling ratio was predicted to be 68.4%. The in vitro and in silico approaches established in this study were able to predict the silane coupling ratios of CAD/CAM resin composites, and they showed that the silane coupling ratio decreased by water absorption.

Investigation of waste clay brick as partial replacement in geopolymer binder

This study investigates waste clay brick (WCB) as partial binder replacement in geopolymers with fly ash and/or slag. The properties investigated include setting time, flowability, strength, water absorption, volume of permeable voids (VPV), water absorption rate, effect of long-term immersion in water, and sulfate attack. For all WCB-based geopolymer mortar samples tested, the short- and long-term compressive strengths remained between 42 MPa and 62 MPa. Water absorption and VPV were found to be between 6.4–7.1 % and 11.9–13 %, respectively. Compared to OPC, geopolymers investigated here showed enhanced resistance to sulfate attack considering both post-exposure length expansion and strength deterioration.

Degradation of Plasticised Poly(lactide) Composites with Nanofibrillated Cellulose in Different Hydrothermal Environments

In this study, bionanocomposite films based on poly(lactide) (PLA) plasticised with poly(ethylene glycol) (PEG) (7.5 wt%) and reinforced with various contents of nanofibrillated cellulose (NFC) (1, 3, 5 wt%) were prepared. The hydrothermal degradation was investigated through immersion in several aqueous environments at temperatures of 8, 23, 58, and 70 °C as a function of time (7, 15, 30, 60, 90 days). The effect of water immersion on the physicochemical properties of the materials was assessed by monitoring the changes in the morphology, thermo-oxidative stability, thermal properties, and molar mass through field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The hydrothermal degradation behaviour was not critically affected regardless of the nanofibrillated cellulose content. All the materials revealed certain integrity towards water immersion and hydrolysis effects at low temperatures (8 and 23 °C). The low hydrothermal degradation may be an advantage for using these PLA biocomposites in contact with water at ambient temperatures and limited exposure times. On the other hand, immersion in water at higher temperatures above the glass transition (58 and 70 °C), leads to a drastic deterioration of the properties of these PLA-based materials, in particular to the reduction of the molar mass and the disintegration into small pieces. This hydrothermal degradation behaviour can be considered a feasible option for the waste management of PLA/PEG/NFC bionanocomposites by deposition in hot aqueous environments.

Effect of Water Immersion on Compressive Properties of Coir Fiber Magnesium Phosphate Cement.

Magnesium phosphate cement (MPC) is a new type of inorganic cementitious rapid repair material, but it has poor toughness and is easy to crack. According to our previous research, these problems can be ameliorated by adding natural coir fiber (CF) into MPC. As coir fiber magnesium phosphate cement (CF-MPC) may be used in humid or rainy areas, its water resistance is an important property in consideration. However, at present, little research has focused on this aspect to provide a good theoretical and experimental basis for the practical application of CF-MPC. In this paper, static compression test and solubility test were used to study the mechanical properties and solubility of CF-MPC under water. At the same time, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to test the changes of hydration composition and microstructure of the test specimen, so as to understand the deterioration mechanism of CF-MPC in water. The results suggested that, when compared with CF-MPC cured in air, CF-MPC cured in water is more prone to encounter oblique cracks and through cracks in the compression process. Moreover, with the extension of curing time, the compressive strength and elastic modulus of CF-MPC cured in water will continue to decrease, the concentrations of PH, K+, and Mg2+ in the curing solution will change significantly, resulting in the gradual decrease in the mass ratio of MgO and MgKPO4·6H2O in CF-MPC matrix, cracks and pores, and looseness in the microstructure.

Study on bending properties of coir fiber magnesium phosphate cement immersed in water

Magnesium phosphate cement (MPC), possessing the characteristics of fast setting and early strength, but has the disadvantages of poor toughness and easy cracking. Our previous studies found that these shortcomings could be improved by adding coir fiber (CF). In practical projects, chances are that CF-MPC might work in watery environment like rainy day. Therefore, it is important to understand the effect of water on the properties of CF-MPC. This paper was then committed to investigate the effect of water immersion on the bending performance of CF-MPC. A three-point bending test was employed to capture the flexural strength, flexural stiffness, and toughness of MPC with different CF contents cured in air and water respectively. The results demonstrated that CF-MPC cured in water and in air displayed a similar failure mode. Specimens’ failure mode varied from brittle failure to ductile failure with CF content increasing. Moreover, the first and second peak loads of specimen load-displacement curves gradually decreased as the water curing time increased. The flexural strength dropped, different from the performances observed in specimens cured in air. But when CF content was smaller than 3%, this flexural property deterioration of specimens in water was relieved as CF content increases.

Thermal effects of water immersion on spray cooling in non-boiling zone

Spray cooling shows significant advantages in thermal control of high heat flux components. However, rapid drainage problem with the spray chamber can affect the reliability and stability of the cooling system. It can be solved by means of immersion. The focus of this paper is to conduct a comparative study of the heat transfer performance between spray cooling (SC) and immersed spray cooling (ISC). It is proved that with reasonable control of immersion state and spray pressure, the immersion does not worsen the heat transfer, but even helps to enhance it with a maximum enhancement ratio of 12.2%. The immersion water temperature and spray pressure play a vital role in the ISC. Wide-angle nozzles are not suitable for ISC applications. The immersion deteriorates the spray cooling by up to 50.1% when the spray angle is 83°. This paper can be a guide to the structural design of the spray chamber.

Study on the Instability Activation Mechanism and Deformation Law of Surrounding Rock Affected by Water Immersion in Goafs

Large-scale goafs are left after coal seam mining. Due to the low-lying terrain, the goaf will be filled and soaked by groundwater, which may lead to instability of the remaining coal pillars in the goaf and cause uneven settlement of the overlying rock. Consequently, there may be overlying rock movement and surface subsidence, which endangers the safety of the building (structure) above the goaf. Considering the strip goaf of Dai Zhuang coal pillar as an example, this study investigated the evolution of instability and deformation of surrounding rocks affected by water immersion using the similar material simulation test method. The results of the study reveal that under the effect of prolonged water immersion in the goaf, the damage to the coal pillar in the strip underwent a stagewise evolution process of several instances of creep damage at the edge of coal pillar followed by overall destabilization damage, and the overburden movement revealed stage characteristics of small step subsidence several times followed by sudden large subsidence. Furthermore, based on Wilson’s coal pillar instability theory, the instability mechanism of the strip coal pillar under the action of water immersion was found to be triggered by the reduced strength of the coal pillar from the effect of water immersion, the continuous creep damage to the strip coal pillar from outside to inside, and the continuous shortening of the elastic zone of the coal pillar until its bearing capacity was lower than the load it was carrying. The research results are expected to serve as theoretical guidance for the study of coal pillar stability and the development and utilization of surface construction above goafs.

An update on environment-induced pulmonary edema - "When the lungs leak under water and in thin air".

Acute pulmonary edema is a serious condition that may occur as a result of increased hydrostatic forces within the lung microvasculature or increased microvascular permeability. Heart failure or other cardiac or renal disease are common causes of cardiogenic pulmonary edema. However, pulmonary edema may even occur in young and healthy individuals when exposed to extreme environments, such as immersion in water or at high altitude. Immersion pulmonary edema (IPE) and high-altitude pulmonary edema (HAPE) share some morphological and clinical characteristics; however, their underlying mechanisms may be different. An emerging understanding of IPE indicates that an increase in pulmonary artery and capillary pressures caused by substantial redistribution of venous blood from the extremities to the chest, in combination with stimuli aggravating the effects of water immersion, such as exercise and cold temperature, play an important role, distinct from hypoxia-induced vasoconstriction in high altitude pulmonary edema. This review aims at a current perspective on both IPE and HAPE, providing a comparative view of clinical presentation and pathophysiology. A particular emphasis will be on recent advances in understanding of the pathophysiology and occurrence of IPE with a future perspective on remaining research needs.

Effect of water immersion on the AC-WC mixture utilizing elastomeric modified asphalt to compressive strength, elastic modulus and durability

Indonesia has relatively high rainfall with a long duration of rain. It can result in a flood on the surface of the road. A flood can reduce the strength of materials from the asphalt mixture and cut the life of the road plan. Therefore, it is necessary to conduct a study that can measure the durability level of the asphalt material mixture on the surface layer of the road to the flood water bath. The study used an Asphalt Concrete-Wearing Course (AC-WC) mixture with Elastomeric Modified Asphalt (EMA), and an Upper Limit (UL), Middle Range (MR), and Lower Limit (LL) gradation based on specification. The Optimum Bitumen Content (OBC) value was obtained from each gradation by applying the Marshall test. The value of the OBC was used to create specimens that had a diameter of 3 inches and a height of 6 inches, and they were using an Unconfined Compression Strength (UCS) test. This study measures the durability of compressive strength and elastic modulus from a mixture of flood water immersion for 1, 2, 4, and 7 days. To calculate the durability using Retained Strength Index (RSI), First Durability Index (r), and Second Durability Index (a). The results showed that there was a decrease in the compressive strength of the mixture on gradations of UL, MR, and LL on days 1, 2, 4, and 7. It meant that the longer the immersion time more reduced the compressive strength of the mixture. The UL-gradedraded mixture had the best durability when it was compared to the MR and LL gradations up to the 7th-day immersion, with an RSI of 91.19%, (r) of 7.44%, and (a) of 6.93%. At the same time, in the elastic modulus of the mixture, there was no significant effect on the duration of immersion because it had a fluctuating value of the elastic modulus to the duration of immersion.

Modulation of Leukocyte Subsets Mobilization in Response to Exercise by Water Immersion Recovery.

Purpose: To investigate the effect of different water immersion temperatures on the kinetics of blood markers of skeletal muscle damage and the main leukocyte subpopulations. Methods: Eleven recreationally trained young men participated in four experimental sessions consisting of unilateral eccentric knee flexion and 90 min of treadmill running at 70% of peak oxygen uptake, followed by 15 min of water immersion recovery at 15, 28 or 38°C. In the control condition participants remained seated at room temperature. Four hours after exercise recovery, participants completed a performance test. Blood samples were obtained before and immediately after exercise, after immersion, immediately before and after the performance test and 24 h after exercise. The number of leukocyte populations and the percentage of lymphocyte and monocytes subsets, as well as the serum activity of creatine kinase and aspartate aminotransferase were determined. Results: Leukocytosis and increase in blood markers of skeletal muscle damage were observed after the exercise. Magnitude effect analysis indicated that post-exercise hot-water immersion likely reduced the exercise-induced lymphocytosis and monocytosis. Despite reduced monocyte count, recovery by 38°C immersion, as well as 28°C, likely increased the percentage of non-classical monocytes in the blood. The percentage of CD25+ cells in the CD4 T cell subpopulation was possibly lower after immersion in water at 28 and 15°C. No effect of recovery by water immersion was observed for serum levels of creatine kinase and aspartate aminotransferase. Conclusions: Recovery by hot-water immersion likely attenuated the leukocytosis and increased the mobilization of non-classical monocytes induced by a single session of exercise combining resistance and endurance exercises, despite no effect of water immersion on markers of skeletal muscle damage. The monocyte response mediated by hot water immersion may lead to the improvement of the inflammatory response evoked by exercise in the skeletal muscle.

Sustainable reuse of excavated soil and recycled concrete aggregate in manufacturing concrete blocks

This paper investigates the properties of concrete blocks manufactured with excavated soil (ES) and recycled concrete aggregates (RCAs). The influences of cement dosage and RCAs (or ES) content on the physical and mechanical properties of the concrete blocks were evaluated. Effects of water immersion and wetting–drying cycles on the compressive strength of the concrete blocks were also investigated, followed by a microstructural characterization on the reaction products. Finally, a cradle-to-gate Life Cycle Assessment (LCA) was conducted to assess the environmental benefits of the green concrete blocks. The results indicate that increasing either the cement dosage or the RCA content can improve the physical and mechanical properties of the concrete blocks. Concrete blocks with a higher cement content or RCA content show better water resistance and only 10% reduction in compressive strength after a 24-hour water immersion. Whereas, the compressive strength of ES-based concrete blocks is enhanced by 20% to 80% after exposing to wetting–drying cycles, particularly for those with a higher ES content. This is mainly attributed to the pozzolanic reaction of smectite in the ES, as evidenced by the enhanced cumulative hydration heat after the incorporation of ES as well as the reduced peak intensities of smectite and calcium hydroxide in XRD results. The LCA demonstrates that increasing the RCA content in concrete blocks increases the energy consumption and global warming potential, but decreases the saved land occupation and transformation. These findings open up new possibility to manufacture eco-friendly concrete blocks containing ES and RCAs considering their mechanical properties and environmental benefits.

Systematic review and meta-analysis to examine intrapartum interventions, and maternal and neonatal outcomes following immersion in water during labour and waterbirth

ObjectivesWater immersion during labour using a birth pool to achieve relaxation and pain relief during the first and possibly part of the second stage of labour is an increasingly popular...

Rationale and current evidence of aquatic exercise therapy in venous disease: A narrative review.

Chronic venous disorders (CVD) of the lower limbs can be treated with different strategies. Typically, conservative management is based on compression therapy, anticoagulants and venoactive drugs. Endovenous treatments remain the gold standard to treat saphenous insufficiency, with sclerotherapy and surgery maintaining a role in selected cases. In addition, several 'unconventional' approaches have been proposed to prevent CVD progression and complications, minimize symptoms and improve the quality of life and postoperative outcomes. Among these, balneotherapy and aquatic exercises are proving as valid and effective supporting treatments, as mentioned in a growing number of scientific publications. Moreover, aquatic protocols have been studied for both venous and lymphatic insufficiency. For these reasons, they were mentioned in the last CVD guidelines provided by the European Society for Vascular Surgery. The aim of this narrative review is to overview and summarize current literature evidences on the role and effectiveness of aquatic rehabilitative protocols in CVD, reviewing old and current literature. Furthermore, the physical basis of the effects of water immersion on lower limb venous and tissues modifications are also described.

Effects of Immersion in Water, Alkaline Solution, and Seawater on the Shear Performance of Basalt FRP Bars in Seawater–Sea Sand Concrete

Effects of Immersion in Water, Alkaline Solution, and Seawater on the Shear Performance of Basalt FRP Bars in Seawater–Sea Sand Concrete

Post-Exercise Cold- and Contrasting-Water Immersion Effects on Heart Rate Variability Recovery in International Handball Female Players.

This study aimed to investigate the effect of water immersion (WI) on cardiac parasympathetic reactivation during recovery from handball training sessions in elite female players during a two-week training camp. On the first three days of both weeks, players completed a crossover design with one of three 60-min delayed post-exercise WI protocols or passive rest (PAS). Recovery interventions consisted of a period of 6-min cold-WI (10°C; CWI6) and two contrasting periods cold- and hot-WI (36°C): one session included 3 min cold + 2 min hot + 3 min cold and the other session 5 × 2 min with cold at the very end. Short-term measures of heart rate variability (HRV) were collected before and after handball training sessions, and after WI. Derived parasympathetic HRV indices collected daily showed lower values post-training compared to pre-training values (p < 0.0001, large ES). Individual handball training sessions revealed similar clear depression of the vagal tone throughout the training camp. The comparison between each WI protocol and PAS revealed significant time × condition interaction particularly for CWI6. All parasympathetic indices revealed higher post-recovery values in CWI6 than PAS (p < 0.001 –p < 0.0001, with large ES ranging from 0.86 to 0.94). Surprisingly, 60-min delayed post-training WI revealed for most of parasympathetic HRV indices higher values than pre-training. This study highlighted that post-exercise parasympathetic disruption was exacerbated in response to handball training, and the 60-min delayed WI recovery interventions improved parasympathetic reactivity. Cardiac vagal tone can be highly improved with CWI6 compared to PAS. For the purpose of HRV modulations, CWI6 is recommended for short-term recovery.

Mechanical properties of carbon/glass fiber reinforced polymer plates with sandwich structure exposed to freezing-thawing environment: Effects of water immersion, bending loading and fiber hybrid mode

In this article, two kinds of carbon/glass fiber hybrid rod with the sandwich structures were designed and developed through the pultrusion technology, including the fiber random hybrid (RH) mode with multi-layer sandwich structure and fiber core-shell hybrid (CH) mode with single-layer sandwich structure. The hybrid sandwich-structure plates were prepared from the rod and immersed in bending loading, temperature alternating and sustained water immersion as long as 360 days. The effect of fiber hybrid mode/sandwich structure on the degradation mechanism of mechanical properties was revealed through the digital image correlation and thermogravimetric analysis. Through the fiber hybrid design, the strength improvement percentages of RH plates with multi-layer sandwich structure were up to ∼50% (tensile strength), 30 ∼ 40% (flexural strength) and 18% (in-plane shear strength) compared to CH plates with single-layer sandwich structure. Higher bending loading level brought about the decrease of flexural strength and in-plane shear strength close to 18% and 19%, respectively. During the immersion, microcracks or microvoids formed and expanded in the resin tensile area under the bending loading and water diffusion, leading to the uncoordinated stress concentration for single-layer sandwich-structure CH plate. By uniformly dispersing carbon fibers into glass fibers, the uneven interface stress concentration can be effectively alleviated for multi-layer sandwich-structure RH plates. The comparison of mechanical properties with the others’ work showed the interface shear strength was more sensitive to the bending loading and immersion temperature. The long-term life prediction showed the maximum increase percentages of mechanical properties of multi-layer sandwich structure were 435.4% (tensile strength) and 149.2% (flexural strength) and 110.7–114.2% (shear strength) compared to the single-layer sandwich structure.

Effect of Water Immersion on Compressive Properties of Coir Fiber Magnesium Phosphate Cement

Effect of Water Immersion on Compressive Properties of Coir Fiber Magnesium Phosphate Cement

Effect of Water Immersion on the Oxidative Combustion Characteristics of Long-Flame Coal Under Different Conditions

Effect of Water Immersion on the Oxidative Combustion Characteristics of Long-Flame Coal Under Different Conditions