Water Immersion Experiments Research Articles

In-situ crosslinking reaction of graphene oxide & waterborne epoxy resin to construct continuous phase anticorrosive coating

The mechanism of using graphene oxide as a two-dimensional filler to increase the path length of the corrosive medium to the metal surface is limited to improving the corrosion resistance of the coating. This study propose novel dispersion and in-situ crosslinking reaction mechanism for constructing water-based heavy-duty anticorrosive coatings by using graphene oxide (GO) and waterborne epoxy resin (WEP). The results showed that GO can be uniformly dispersed directly into WEP without complex functional modifications. Oxygen-containing functional groups on moleculars structure of GO&WEP co-polymerized with diethylenetriamine (DETA) forming a continuous phase film which improved the density of the coating. Characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal conductivity measurement instrument, pencil hardness tester, adhesion tester, salt spray corrosion test chamber, and electrochemical impedance spectroscopy (EIS) were used to evaluate coating structure and performance properties. The results showed that graphene characteristics enhanced physical properties and anti-corrosion performance of composite coatings. The construction mechanism of the coating is different from that of the current GO modified and dispersed in the coating as a two-dimensional filler to extend the path length of the corrosive medium to the metal surface. The coatings prepared by adding the optimum mass ratio of 0.1–0.2 % GO to WEP have the best physical properties and anti-corrosion properties. When the GO content is 0.2 wt%, the thermal conductivity increases by 86.0 %. After added 0.025 wt% GO, the coating hardness is increased by two grades directly from 2B to HB. With the addition of GO concentration increased to 0.05 wt%, the adhesion is increased from 2 to level 1.When the GO content exceeds 0.05 %, the coating will not bulge off after 4 months of salt water immersion experiment.

Tritium Content in Komatsuna Cultivated in Tritium-Contaminated Peat Soil

Tritiated water from fusion power reactors will be the next major issue when fusion technology comes fully onstream. Effective radiation protection measures will be implemented when the scope of its behavior is well understood. To understand tritium behavior in the environment, komatsuna was cultivated in tritium-contaminated peat soil. It was indicated experimentally from water immersion experiments that the amount of tissue free water tritium in komatsuna depends on the tritium concentration in the soil and that the concentration in stems and leaves in komatsuna decreases as the tritium concentration in the soil decreases. The amounts of tritium retained in the roots were much less than that in the stems and leaves.

Study on Uniaxial Mechanical Behavior and Damage Evolution Mechanism of Water-Immersed Mudstone

The existence of mudstone weak interlayers has a significant impact on the stability of open-pit coal mine slopes. Under the combined influence of rainfall and groundwater, the mechanical properties of the mudstone of weak interlayers deteriorate, leading to a local loss of bearing capacity of the slope and further accelerating the overall instability of the slope. In order to investigate the changes of macroscopic and mesoscopic structures, mechanical failure behavior, and the damage evolution mechanism of water-immersed mudstone, non-destructive water immersion experiments and uniaxial compression experiments were conducted. The results indicate that the main causes of macroscopic structure failure of water-immersed mudstone are the initiation, propagation, and mutual penetration of micro cracks. The mesoscopic structure characteristics of water-immersed mudstone are primarily manifested by increased surface smoothness, increased occurrence of small-scale pores, the presence of a dense network of fissures on the surface, and fusion of mineral unit boundaries. With the increasing immersion time, the quality, relative water content, and peak strain increase, while the uniaxial mechanical parameters and energy parameters decrease. In addition, a statistically damaged constitutive model for mudstone considering the coupling damage of water immersion and low-stress loading was established, and the model is consistent with experimental results. Finally, the water-softening characteristics of mudstone are caused by the propensity of clay minerals to expand and disintegrate upon water contact, changes in pore structure, variations in mineral types and distributions, and the presence of pore water pressure. This study provides valuable insights into the water–rock deterioration mechanism of mudstone and the stability of slopes containing weak interlayers.

A multi-segmented human bioheat model under immersed conditions

A multi-segmented human bioheat model was developed to characterize the heat exchange phenomena of the human body while immersed in water and to predict the body's thermoregulation and physiological reactions under immersed conditions. The model is based on the Tanabe model, which divides the human body into 15 segments according to the “Walter” thermal manikin. Each segment is made up of the core layer, muscle layer, fat layer, skin layer and central blood layer. The wet clothing model, which uses empirical equations derived from several underwater manikin experiments, is used in the multi-segmented human bioheat model to represent the mechanism of heat exchange between the human body and the outside world through wet clothing after falling into water. Ten healthy males were chosen for the water immersion experiment and placed in a climatic chamber with simulated falling water. Six different body parts' core temperatures, skin temperatures, and heat flow densities were continually monitored throughout the experiment. By contrasting the experimental results of the water immersion environment with the multi-segmented human bioheat model's predicted outcomes, the accuracy of the model was assessed. The results showed that the values predicted by the model simulation matched the results of the experiments, which indicates that the multi-segmented human bioheat model was reliable, valid, and very useful.

Controlled release fertilizer with temperature-responsive behavior coated using polyether polyol (PPG) / polycaprolactone (PCL) blend-based polyurethane performs smart nutrient release

The development of the temperature-responsive controlled release fertilizers (CRFs) can tune the nutrient release matching plant demands even when temperature fluctuates. Herein, polycaprolactone (PCL) with different molecular weights (PCL500, PCL1000, PCL2000 and PCL3000) were used as raw materials and six types of PU films as coating materials for CRFs were synthesized by reacting the polyether polyol (PPG)/PCL blends and methylene diphenyl diisocyanate (MDI). Furthermore, the CRFs coated using PU films (PUCFs) were prepared in a fluidized bed device by in-situ reaction method, and the nitrogen (N) release rate of PUCFs was measured by water immersion experiment. The temperature sensitivity and compositions of PU films were evaluated with differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Results showed that PUCFs based on PCL500 satisfied the CRF ISO standard, but the corresponding PU film had no temperature-responsive property. However, PUCFs based on PCL2000 and the corresponding PU film showed the opposite results. FTIR and XRD results showed that the PPG/PCL2000 blends could copolymerize with MDI to format the block copolymer with the two-phase structure of crystalline phase/amorphous phase. The block copolymer comprising of PPG and PCL2000 at a molar ratio of 8 to 2 was indicated to have shape memory characteristics and the CRFs coated by this copolymer had excellent N release characteristics with a controlled release period of more than 30 days. Moreover, these CRFs showed significant temperature-switch at 33 °C. In conclusion, the production of temperature-responsive PUCF which is suitable for the application into agriculture will improve nutrient availability, indicating that the stimuli-responsive system has potential application in sustainable and green development of agriculture.

Application of Digital Core Technology in Wellbore Stability Research

Using core to conduct laboratory experiments is one of the important methods for wellbore stability research. However, as the objects of petroleum exploration gradually shift to areas with complex geological conditions, core acquisition is restricted by many problems, such as irregular shapes of cores obtained, low core acquisition rate, long construction time, and increasing operational cost. In recent years, exploration work in the southwest Tarim Basin has been further strengthened. Due to the complex strata and the frequent occurrence of complex well conditions during the drilling process, the problem of on-site coring has become more prominent, which seriously limits the analysis of rock properties. Therefore, scientific and effective cuttings analysis technology is urgently needed. This paper used digital core CT scanning technology to reconstruct the rock skeleton and its mineral facies using drill cuttings. The digital core was established, and the Poisson’s ratio and elastic modulus were calculated. The wellbore stability was analyzed, and the well sections, which were prone to wellbore instability, were determined. On this basis, KCl-polysulfonate drilling fluid was introduced. The influence of drilling fluid on rock strength was evaluated by digital core technology, and water immersion experiments were introduced to verify the experimental results. The results obtained by digital core CT scanning technology were compared with those obtained by triaxial compression experiments and well-logging data calculation, and the feasibility of digital core technology in the wellbore stability study and drilling fluid evaluation was verified.

In‐situ thermal aging of biobased and conventional rigid polyurethane foams nanostructured with bacterial nanocellulose

AbstractThe incorporation of nanofillers and the use of biobased polyols might have a deleterious effect on the aging performance of rigid polyurethane foams (RPUFs) applied in the insulation and marine industries. To study this, RPUFs obtained from petroleum based (RPUF) and castor oil (RPUFRIC) polyols were nanostructured with bacterial nanocellulose (BNC) up to 0.3 wt%. Water immersion experiments revealed that the normalized water absorption (NWA) at the steady state was not affected by lower BNC contents (<0.2 wt%). Higher BNC contents caused a complex effect on post‐cure and foaming, generating cell size expansion as well as shrinkage. In‐situ DMA aging analysis revealed that the specific storage modulus (E'sp) under flexural conditions of the RPUFRIC and RPUF decreased by a maximum amount of 7.27% and 6.19%, respectively. The effect of BNC on the E'sp was negligible, expect for the case of the RPUF, where higher BNC concentrations (>0.2 wt%) caused a decrease of up to 13.69%. The previous results reinforce the hypothesis that the incorporation of BNC in both conventional and biobased polyurethane systems do not cause significant changes on the aging performance of the resulting foams, provided that low BNC concentrations are employed.

Analysis of enhancing moisture-proof and waterproof performance for lignite powder briquette

ABSTRACT There are abundant resources of low-rank coal powder in the world. Powder briquetting technology has opened up a new avenue for large-scale utilization of low-rank coal. Water repellency is of great importance for the storage and transportation of lignite briquettes. In this paper, different water repellents were investigated to improve the moisture and water resistance of briquettes. The results showed that the moisture-proof and waterproof effect of briquette with the silicone emulsion was better than other briquettes. After 132 h of moisture absorption experiment, the briquette with the silicone emulsion absorbed only 1.8 wt% of water finally and was less 4.7 wt% than the briquette without water repellent. After 24 h of water immersion experiment, the water absorption of briquette with the silicone emulsion reached 19.74%. The addition of water repellent improved the water immersion strength and re-drying water immersion strength, of which briquette with the silicone emulsion were 4.91 KN/piece and 9.37 KN/piece. The waterproof mechanism was explored by scanning electron microscopy and wettability. It was proved that the addition of silicone emulsion, polyurethane, and acrylic emulsion played a positive role in the waterproofing of lignite briquette.

Experimental Investigation of the Mechanical Failure Behavior of Coal Specimens With Water Intrusion

Mining fissures formed by coal mining can easily open bedrock and loose aquifers, and can thus cause water–rock interaction. The strength of coal and rock and their pore and fracture development characteristics are closely related to moisture content. Therefore, this paper studied the strength, porosity, fracture propagation, and failure characteristics of coal with different moisture contents. Six representative coal samples with different moisture contents of 0, 3.79, 6.10, 9.17, 11.01, and 11.68% were prepared by non-destructive water immersion experiment, and the samples were analyzed using. Nuclear Magnetic Resonance (NMR) and uniaxial compression acoustic emission experiments. Then, the temporal and spatial variation of the moisture contents of the coal samples and the characteristics of crack propagation and failure were studied before and after water immersion. Non-destructive water immersion and NMR analysis showed that the moisture content increases exponentially with increasing water immersion time and immersion frequency. Additionally, it was shown that with increasing water immersion time and frequency, the moisture distribution within the coal samples changes from uneven to uniform, and micro-pores and meso-pores develop into larger pores with increasing water content. A coupled uniaxial compression–acoustic emission experiment showed that acoustic emissions are closely related to the macroscopic failure mode of the coal sample. With increasing sample moisture content, the degree of sample destruction and the concentration of acoustic emissions both reduced. The increase of moisture content promotes the change of the macroscopic failure mode of the coal samples from tensile failure to tensile–shear composite failure. The results of this study have important reference value for analyzing the stability of coal pillars and surrounding rock under the action of water, and especially for the design of coal pillar dam bodies in coal mines with groundwater reservoirs.

Flexural and hydrothermal aging behavior of silk fabric/glass mat reinforced hybrid composites

Recycled natural materials such as silk fabric have attracted more and more public attention over the past few years. In this research, unsaturated polyester resin was used as matrix, glass mat and silk fabric were employed as reinforcement to fabricate the laminated hybrid composites by hand lay-up method. Three-point flexural quasi-static and load-controlled low cycle bending fatigue (LCBF) tests at 55 %, 70 % and 85 % pre-set load levels were performed. The composite specimens were also subjected to hot water immersion treatment at 80 oC for different durations. The effects of the immersion treatment on the bending and impact fracture characteristics were investigated. The results showed that higher flexural modulus and strength were obtained when silk fabric layer was stacked at the middle layer. It seems that the antifatigue property was improved by the inclusion of silk fabric reinforced in glass mat hybrid composites. In the water immersion experiments, both the flexural properties and impact properties were improved initially until reaching the maximum and then decreased continuously with further increase in exposure time. These seemingly contradictory behaviors are due to relaxation of the internal stress, swelling of the silk fibers and the weakening of fiber/matrix interface.

Decohesion and rupture mechanisms of a multilayered microbattery studied by 4-point bending

Abstract This paper presents tests to characterize the mechanical resistance of the multilayers set which forms an all-solid-state lithium-ion micro battery. The system under investigation consists in five layers that were deposited successively onto a crystalline silicon substrate (100): Ti, TiOS, LiPON, aSi, Ti. The layer thicknesses are between 65 nm (amorphous silicon layer aSi) and 1400 nm (LiPON, TiOS). First, simple water immersion experiments allow internal stress to be put into evidence in the two external layers (aSi and Ti), basically a strong compressive stress in the aSi layer (at least −0.8 GPa). Afterwards, well-controlled 4-point bending tests lead to delamination of the weakest parts of the multilayer, which are the TiOS-LiPON and LiPON-aSi interfaces. The TiOS-LiPON interface is the weakest, with an adhesion energy around 2.5 J/m 2 . The TiOS layer exhibits a rather low cohesion energy, scarcely higher than 2.5 J/m 2 . The brittle character of LiPON clearly appears. By using samples of another kind (-Ti-TiOS-Ti on Si), local adhesion flaws are identified between the TiOS and underlying Ti layer. In our experiment, these local adhesion flaws lead to characteristic phenomena (formation of comet-shaped scales), which are explained in the framework of a simple mechanical model.

IDENTIFICATION OF ABNORMAL PHASE AND ITS FORMATION MECHANISM IN SYNTHESIZING CHALCOGENIDE FILMS

Chalcogenide films can be used in thin-film solar cells due to their high photoelectric conversion efficiencies. It was difficult to identify one abnormal phase with high X-ray diffraction (XRD) intensity and preferred orientation in the samples for preparing chalcogenide films by spin-coating and co-reduction on soda-lime glass ([Formula: see text]) substrates. The raw materials and reductant are metal chlorides and hydrazine hydrate respectively. In order to identify this phase, a series of experiments were done under different conditions. The phases of obtained products were analyzed by XRD and the size and morphology were characterized by scanning electron microscope (SEM) and atomic force microscopy (AFM). From the experimental results, first it was proved that the abnormal phase was water-soluble by water immersion experiment, then it was identified as NaCl crystal through XRD, energy dispersive spectrometer (EDS) and SEM. The cubic NaCl crystals have high crystallinity with size lengths of about 0.5–2[Formula: see text][Formula: see text]m and show a [Formula: see text]100[Formula: see text] preferred orientation. The reaction mechanism of NaCl crystal was proposed as follows: The NaCl crystal was formed by reaction of Na2O and HCl in a certain experimental conditions.

Slow release fertilizers based on urea/urea–formaldehyde polymer nanocomposites

A novel nanocomposite material based on the exfoliation of montmorillonite into a matrix of urea/urea–formaldehyde polymer was developed to be used as nitrogen-loaded slow release fertilizers. The nanocomposites were produced by cold plastic extrusion, a simple and high-productive method, using a formaldehyde precursor to accomplish polymerization in situ during extrusion processing. Characterizations showed that the extruded fertilizer nanocomposites presented good mechanical resistance, and that the urea release was noticeably controlled by the extent of polymerization. Water immersion experiments demonstrated that the nanocomposite structure was responsible for the effective slow urea release behavior. A dependence of the availability of other nitrogenous compounds (NH4+ and NO3−) on the polymerization degree was also demonstrated by soil incubation tests. The urea/urea–formaldehyde polymer nanocomposites were found to be versatile and smart materials capable of supplying the enormous demand for novel efficient nitrogen fertilizers.

Altered Gravity Simulated by Parabolic Flight and Water Immersion Leads to Decreased Trunk Motion.

Gravity is one of the important environmental factors that influence the physiologies and behaviors of animals and humans, and changes in gravity elicit a variety of physiological and behavioral alterations that include impaired movement coordination, vertigo, spatial disorientation, and perceptual illusions. To elucidate the effects of gravity on human physiology and behavior, we examined changes in wrist and trunk activities and heart rate during parabolic flight and the activity of wrist and trunk in water immersion experiments. Data from 195 person-time parabolas performed by eight subjects revealed that the trunk motion counts decreased by approximately half during ascending legs (hypergravity), relative to the data acquired before the parabolic flights. In contrast, the wrist activity remained unchanged. The results from the water immersion experiments demonstrated that in the underwater condition, both the wrist and trunk activities were significantly decreased but the latter decreased to a much lower level. Together, these data suggest that gravitational alterations can result in differential influences on the motions of the wrist and the trunk. These findings might be important for understanding the degeneration of skeleton and muscular system and performance of astronauts in microgravity.

Superhydrophobicity on transparent fluorinated ethylene propylene films with nano-protrusion morphology by Ar + O2 plasma etching: Study of the degradation in hydrophobicity after exposure to the environment

Fluorinated ethylene propylene (FEP) films were made superhydrophobic by Ar + O2 plasma etching process. Field emission scanning electron microscopy and atomic force microscopy studies of the plasma-treated FEP samples detected the presence of uniformly distributed nano-protrusions exhibiting a low surface roughness necessary for maintaining the transparency of the samples. In fact, optical transmittance measurements showed an improvement in the transparency of FEP samples after plasma treatment. The X-ray photoelectron spectroscopic analysis showed the presence of –CFx–O–CFx– (x = 1, 2, or 3) linkages in both untreated and plasma-treated samples which explains the hydrophilic nature (contact angle below 90∘) of the untreated sample. Fourier transform infrared spectroscopy showed no changes in the bulk properties of the plasma-treated samples. Moreover, exposure to the environment caused the surfaces to lose their superhydrophobic property in an indefinite amount of time. This has been further studied through a water immersion experiment and explained through the wetting state transition from Cassie state to Wenzel state.

A highly thermal stable and waterproof red phosphor: Pr3+-doped Sr2Al2SiO7

The Pr3+-doped Sr2Al2SiO7 phosphors with red emission were synthesized by conventional solid-state reaction in air for the first time. The photoluminescence properties of the phosphors and structural phase were investigated. The red emission of the phosphors was observed under the range of 420–500 nm excitation, which covered the emission spectra of blue LED. The optimal emission intensity was obtained when Pr-doping content was 0.008 mol and the chromaticity coordinates of these phosphors could be slightly tuned by changing the Pr3+ concentration. Furthermore, the investigation of temperature dependence of luminescence and the water immersion experiment indicated that the Pr-doped Sr2Al2SiO7 phosphors were highly thermally stable and waterproof.

Bulk thermal conductivity of malting barley

A thin-wall steel can was filled with grain of barley and submerged into a water immersion unit containing hot water. The water immersion experiments and an inverse modeling method were used to derive the bulk thermal conductivity of barley (var. Mauritia) dependent on the bulk temperature and grain moisture content. Arrhenius-type equation was applied to describe temperature and moisture content influence on barley bulk thermal conductivity. The thermal conductivity increases with increasing moisture content and temperature and the values ranged from 0.124 to 0.155W/mK. The results are of the same order as the published data received for varieties of barley different than those applied in the present study.

Hydrolytic degradation and functional stability of a segmented shape memory poly(ester urethane)

In order to understand the effects of water and hydrolytic ageing on semi-crystalline poly(ester urethane) and its shape memory functionality, water immersion experiments at elevated temperature have been performed on a model substance and various parameters were monitored: change of the melting/crystallisation temperatures, substantial increase in crystallinity, temperature dependence of the water diffusion coefficient and solubility, hydrogen-bonding index and phase mixing by peak deconvolution of the FT-IR carbonyl region and day-to-day tensile and thermo-mechanical cyclic tensile tests. A rising fraction of freezable water agglomerates in the polymer was found for specimens cooled from the immersion temperature. The degradation process could be divided into three phases: an induction phase, a phase of continuous degradation and a phase of accelerated degradation. Shape recovery remains fairly constant during phase one and decreases slowly during phase two. The increase in crystallinity in phase two is accompanied by an increase in shape fixing ability.

Potassium Depletion and Salt Sensitivity in Essential Hypertension

To evaluate the actual role of potassium depletion on blood pressure, 11 hypertensive patients were placed on a 10-day isocaloric diet providing a daily potassium intake of either 18 or 80 mmol, with each subject serving as his or her own control; the intake of sodium (220 mmol/day) and other minerals was kept constant. On day 11 each patient was also subjected to central volume expansion by water immersion associated with either normal or low potassium intake. After a 10-day period of low potassium intake, systolic blood pressure increased (P < 0.02) by 5 mm Hg, whereas serum potassium decreased (P < 0.001) by 0.9 mmol/L; no significant changes in urinary sodium and a marked increase in urinary calcium excretion (P < 0.001) were found during the 10-day low potassium intake. PRA (P < 0.02) and plasma aldosterone (P < 0.04) concentrations also decreased during low potassium intake in hypertensive patients. Even though an identical natriuretic response was found during the water immersion experiments with either high or low potassium in the whole hypertensive group, the evaluation of hypertensive subjects in relation to salt sensitivity enabled us to disclose pronounced differences in the natriuretic and calciuretic response. In fact, although an impaired natriuretic ability and moderate calcium loss were particularly found during water immersion in those hypertensive subjects exhibiting a lower salt sensitivity index, a predominant calcium depletion appeared to be the most important consequence of potassium depletion in the hypertensive subjects with a higher salt sensitivity index. By confirming that potassium depletion may exacerbate essential hypertension, our data also suggest that not only sodium restriction, but also potassium and calcium supplementation, could be particularly advisable in salt-sensitive hypertensive patients.

Antimonic acid and sulfonated polystyrene proton-conducting polymeric composites

Polymer composites formed of a proton conductor and polyvinylidene fluoride (PVDF) are prepared. Sulfonated polystyrene (SPS) and antimonic acid (AAc) are used as organic and inorganic proton conductor, respectively. PVDF is the insulating matrix used as a binder to improve the mechanical stability of the composites compared with the pure proton conductors. The effect of the SPS and/or AAc on both the glass transition temperature, T g, and the melting temperature, T m, of the PVDF is studied. The ionic conductivity of the composites, after water vapor exposure at r.t., and after water immersion at 50°C, is measured at room temperature. The overall conductivity of the composite increases with time up to saturation, which is attained: (i) after 17 h for the water vapor exposure experiment and (ii) after ≈10 min, for the water immersion experiment. The ionic conductivity of the composites is smaller than that of the pure protonic conductors, but the composites show high-dimensional stability. The shape of the conductivity curve depends on the proton conductor chosen.