Water Immersion Research Articles

Bonding of Beech Wood to Mortar with a Novel Epoxy Hybrid-Adhesive: Performance in Dry and Wet Conditions

Composites made of timber and cementitious materials require a rigid connection to exploit their full composite action, which can be achieved by using full-surface adhesive bonding. In this work, we investigated a novel hybrid-adhesive system consisting of a silane-terminated polyurethane (STP) and epoxy resin for the bonding of beech wood timber to fresh mortar for use in timber-mortar composites (TMC). The mechanical performance and the influence of moisture on TMC produced by the wet-in-wet process (fresh mortar) was investigated and compared to the bonding of prefabricated mortar (prefab process). The STP-epoxy hybrid-adhesive showed a suitable bonding performance of beech wood to both, fresh mortar and precured mortar with median compression shear strengths of 4.57 MPa and 6.07 MPa, respectively. The fracture pattern showed the strength of the near-surface layer in the mortar, close to the adhesive, being often decisive for the bond performance. The same failure mode predominated in TMC beams after 3-point bending tests. The stability of the composite upon the influence of moisture is especially challenging when using beech wood due to its low dimensional stability. Thus, the moisture stability of the bond was investigated by compression shear tests after water immersion. It showed superior water stability compared to composites bonded with a pure epoxy resin. Nonetheless, a clear reduction in bond strength compared to the dry state was observed, with delamination of 25% of the wet-in-wet and 17 % of the prefab specimens during water immersion. Furthermore, it was seen that the adhesive waiting time played a decisive role in the wet-in-wet produced specimens influencing both, dry and wet shear strength.

Effects of Time-Elapsed Bleaching on the Surface and Mechanical Properties of Dentin Substrate Using Hydrogen Peroxide-Free Nanohydroxyapatite Gel.

There is a critical need to address concerns surrounding the potential impact of bleaching gels specifically on the tooth substrate. Therefore, this laboratory investigation aimed to assess the impact of a hydrogen peroxide (HP)-free bleaching (HiSmileTM) in comparison to an HP-based bleaching (Opalescence RegularTM) on the surface and mechanical characteristics of tooth substrate. Sixty sound human premolar teeth were sectioned to produce dentin fragments and divided into two primary groups based on the bleaching agent used. Each group was subdivided into three subgroups (n = 10) per distinct bleaching regimens: (T1) fragments underwent a 7-day immersion in distilled water at 37°C without any bleaching treatment, (T2) fragments underwent a 7-day immersion in distilled water at 37°C, with the application of bleaching gel occurring on the seventh day for 10minutes, and (T3) fragments underwent a bleaching regimen for seven consecutive days, each session lasting for 10minutes. The initial and final evaluations of surface roughness, nano-hardness, and elastic modulus were performed. Following the bleaching regimens of T3, a composite stub was fabricated on the dentin fragments for the shear bond strength (SBS) test. Statistical testing was accomplished using the analysis of variance (P < 0.05). HP-based bleaching gel showed significant differences between measurement intervals in surface roughness, elastic modulus, and SBS parameters (P < 0.05). In contrast, HP-free bleaching gel showed insignificant differences within the group (P > 0.05). The SBS between dentin-composite was significantly affected with the use of HP-based bleaching gel, while HP-free bleaching gel showed insignificant difference between measurement intervals. The qualitative validation of the treatment's impact was further demonstrated using the scanning electron microscopy. The findings suggest that the bonding stability of composite restorations to dentin may be compromised after bleaching with an HP-based gel, whereas immediate bonding procedures can be safely conducted following the application of an HP-free bleaching gel.

Transparent composite-structure antifogging coating with mechanical abrasion resistance and environmental durability

Superhydrophilic SiO2 coatings offer unparalleled advantages in terms of antifogging properties. However, they show suboptimal mechanical abrasion resistance and environmental durability, limiting their application. Accordingly, research has focused on the trade-off between hydrophilicity and mechanical abrasion resistance as well as between environmental durability and visible transmittance in superhydrophilic SiO2 coatings. Herein, a composite-structure coating with a densely distributed particulate phase and enhanced crosslinking strength is developed without the use of organic compounds. The coating exhibits remarkable transparency and antifogging properties, with an average transmittance similar to that of bare glass and a water contact angle of approximately 0°. Moreover, the coating exhibits impressive hardness and adhesion of up to 4H and 5B, respectively. The coating retained its antifogging properties even after undergoing 500 cycles of wear induced using a 3000-mesh sandpaper, impact of sand (40 g) dropped from a height of 40 cm, 10 weeks of exposure to the outdoor environment, and 25 h of immersion in water. The test results demonstrate that the coating exhibits satisfactory mechanical abrasion resistance and environmental durability, which are essential for its practical applications. The composite structure formed using linear SiO2 molecules as crosslinking agents with spherical SiO2 nanoparticles considerably enhances the adhesion and abrasion resistance of the coatings. Overall, the developed composite-structure coatings will facilitate their commercial viability and expand the application of superhydrophilic materials in various research fields.

Influence of collapsible shape of Loess Foundation on high-speed railway subgrade under train vibration loading

Collapsible loess has special sensitivity to water, and its engineering mechanical properties deteriorate significantly after immersion in water, causing the foundation to sink, which seriously threatens the safety and stability of the high-speed railway subgrade under train vibration loading. Studying this effect is essential to prevent and control the disasters of high-speed railway subgrades. In this study, a model with the function of simulating foundation settlement is established to conduct disaster testing of high railway subgrade under train vibration loading. The results indicate that when different foundation shapes are settled, the surface of the subgrade under static load is gradually settled in a short time, and the settlement value of the track surface is lower than that of the corresponding subgrade surface. Under train vibration load, the maximum dynamic settlement occurs at the middle of the subgrade slope, which is smaller than the corresponding settlement under static load. The number of stabilization times required from different monitoring positions on the subgrade surface is different under different excitation forces, and the number of stabilization times required is more in the middle of the subgrade slope and the slope shoulder. The influence of train speed on subgrade has a critical respond speed that increases with increasing vibration times. There are horizontal, vertical and 45° angle cracks in the middle of subgrade slope. It is qualitatively assessed that the slope of the high-speed railway subgrade in the collapsible loess area is unstable under the effect of train load. The data and rules provided in this document provide some reference values for the construction of a high-speed railway in the collapsible loess area.

Development and evaluation of STRC coating for cooling asphalt pavement and mitigating urban heat island effects

To mitigate the negative impacts of urban heat island (UHI) effects on modern cities, this study developed and evaluated a novel cool coating, solar thermal reflective coatings (STRC), for reducing asphalt pavement temperatures. Firstly, the optical properties were characterized using UV-Vis-NIR spectroscopy, and the thermal performance of eight STRC formulations was assessed using a custom-built testing apparatus. Subsequently, the microstructure and elemental composition were examined using scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Finally, the optimized coating was applied to asphalt concrete, and its long-term performance and stability were confirmed through durability tests, including water immersion test, temperature variation endurance test, and radiation cycle test. The results showed that chromium sesquioxide (Cr₂O₃), a critical pigment of STRC, exhibited a high near-infrared reflectance of 54.76 % and a lower visible reflectance of 10.22 %. Among the eight STRC formulations, STRC5 demonstrated balanced performance with a visible reflectance of 35.69 % and a near-infrared reflectance of 71.85 %. The microstructure of STRC5 was uniform with minimal surface defects. When STRC5 was applied to asphalt concrete, it achieved significant cooling effects, maintaining a mean temperature of 49.51 °C compared to 60.07 °C for uncoated samples, resulting in a maximum temperature difference of 10.56 °C after 4 h of light exposure. Durability test results confirmed the long-term performance and stability as the coating withstood extreme temperature fluctuations from −20 °C to 60 °C and 72 h of water immersion. In conclusion, STRC5 demonstrated great potential to effectively cool asphalt pavement and mitigate UHI effects.

Optimizing mechanical and environmental degradation performance of polybutylene adipate terephthalate by adjusting polyvinyl alcohol content

Biodegradable plastics offer a promising alternative to traditional plastics in agriculture, particularly where rapid and controlled degradation is required. This study investigates the properties and degradation behavior of blends of Polybutylene Adipate Terephthalate (PBAT) and Polyvinyl Alcohol (PVA). Mechanical testing revealed that incorporating PVA significantly enhanced both tensile and flexural strengths. For example, pure PBAT had a tensile strength of 14.51 MPa, while the 20PBAT/80PVA blend achieved 53.48 MPa. However, higher PVA content led to reduced elongation at break and fracture toughness. Water immersion tests showed that PVA dissolution and PBAT degradation caused notable reductions in mechanical properties after 5 days, with blends containing 80 % PVA exhibiting an 80.1 % weight loss, and the 40PBAT/60PVA blends showing a 41.75 % weight loss after 30 days. Soil degradation experiments confirmed that the degradation rate increased with higher PVA content. These results highlight the superior degradation performance of PBAT/PVA blends and demonstrate that adjusting the PVA content effectively modulates both degradation rates and mechanical properties. This offers valuable insights for the development of environmentally friendly materials.

Effects of single- and bilateral limb immersion on systemic and cerebral hemodynamic responses to the cold pressor test.

The cold pressor test (CPT) involves cold water immersion of either the upper or lower limb(s) and elicits increases in sympathetic nervous activity (SNA), heart rate (HR), and mean arterial pressure (MAP) via stimulation of pain and cutaneous thermoreceptors. Greater pain perception during the CPT is associated with greater increases in SNA and more robust physiological responses. Due to potential differential sensitivity to both painful and thermal stimuli between upper and lower limbs, as well as potential effects of total exposure area, it is unclear whether the choice of limb(s) in CPT protocol design differentially affects systemic and cerebral hemodynamic responses. Our objective was to assess systemic and cerebral hemodynamic and ventilatory responses to different CPT protocols of the hand (CPTH), foot (CPTF), or bilateral feet (CPTBF). We hypothesized CPTBF would elicit greatest physiological responses due to increased exposure area to the cold stimulus. Twenty-eight (14 M, 14 F) healthy young adults [23.4 (SD: 2.4) yr] participated in three 3-min CPT protocols during a single visit. Blood pressure, HR, middle cerebral artery blood velocity (MCAv) and cerebrovascular conductance index, and end-tidal carbon dioxide ([Formula: see text]) were averaged over the final 30 s of each minute of the CPT for each protocol, and perceived pain was recorded at the end of each minute of the CPT. We found significant effects of the time-CPT protocol interaction on systolic blood pressure (P = 0.02), diastolic blood pressure (P < 0.01), MAP (P < 0.01), and HR (P < 0.001). There were no differences between CPT protocols on either MCAv (P = 0.4) or cerebrovascular conductance index (P = 0.1). HR responses peaked in the first minute of the CPT, and changes from baseline were greater in CPTBF [Δ14(16) beats/min] compared with CPTH [Δ5(13) beats/min; P = 0.01] and CPTF [Δ4.04(13.3) beats/min; P = 0.02]. MAP responses peaked in minute 2 of the CPT, and changes from baseline were greater in CPTH [Δ12(8) mmHg) and CPTBF (Δ13(9) mmHg] compared with CPTF [Δ8(7) mmHg; P < 0.01]. Perceived pain was significantly greater in the CPTBF [CPT1 7(2.3), CPT2 6.5(2.3), CPT3 6(3)] condition compared with CPTH [CPT1 6(1.3), CPT2 6(2.3), CPT3 6(2.3)] and CPTF [CPT1 6(3.0), CPT2 6(2.0), CPT3 5.5(3.0)] protocols at all three stages of the CPT (P ≤ 0.01). Our findings suggest choice of limb(s) in CPT protocols may lead to differences in systemic hemodynamic responses, with pain perception potentially influencing these responses. Based on our results, we suggest that choice of limb should be considered in future design of CPT studies, with hand CPT providing the best balance between participant tolerability and robust physiological responses.NEW & NOTEWORTHY Choice of limb(s) in cold pressor test (CPT) studies appears to influence systemic hemodynamics. Hand and bilateral feet induce more robust responses than single-foot CPT, potentially due to increased exposure area and pain perception. Despite no significant cerebrovascular effects, a sustained hyperventilatory response was noted in bilateral feet CPT. Hand CPTs may provide a balance between robust physiological responses and tolerability. These findings underscore the need for careful limb selection in future CPT studies.

No Effect Of Water Immersion On Training-induced Improvements In Apnea Duration

No Effect Of Water Immersion On Training-induced Improvements In Apnea Duration

Cold Exposure Alleviates T2DM Through Plasma-Derived Extracellular Vesicles.

Anecdotal reports have praised the benefits of cold exposure, exemplified by activities like winter swimming and cold water immersion. Cold exposure has garnered acclaim for its potential to confer benefits and potentially alleviate diabetes. We posited that systemic cold temperature (CT, 4-8°C) likely influences the organism's blood components through ambient temperature, prompting our investigation into the effects of chronic cold exposure on type 2 diabetic (T2DM) mice and our initial exploration of how cold exposure mitigates the incidence of T2DM. The effects of CT (4-8°C) or room temperature (RT, 22-25°C) on T2DM mice were investigated. Mice blood and organ specimens were collected for fully automated biochemical testing, ELISA, HE staining, immunohistochemistry, and immunofluorescence. Glucose uptake was assessed using flow cytometry with 2-NBDG. Changes in potential signaling pathways such as protein kinase B (AKT), phosphorylated AKT (p-AKT), insulin receptor substrates 1 (IRS1), and phosphorylated IRS1 (p-IRS1) were evaluated by Western blot. CT or CT mice plasma-derived extracellular vesicles (CT-EVs) remarkably reduced blood glucose levels and improved insulin sensitivity in T2DM mice. This treatment enhanced glucose metabolism, systemic insulin sensitivity, and insulin secretion function while promoting glycogen accumulation in the liver and muscle. Additionally, CT-EVs treatment protected against the streptozocin (STZ)-induced destruction of islets in T2DM mice by inhibiting β-cell apoptosis. CT-EVs also shielded islets from destruction and increased the expression of p-IRS1 and p-AKT in adipocytes and hepatocytes. In vitro experiments further confirmed its pro-insulin sensitivity effect. Our data indicate that cold exposure may have a potentially beneficial effect on the development of T2DM, mainly through the anti-diabetic effect of plasma-derived EVs released during cold stimulation. This phenomenon could significantly contribute to understanding the lower prevalence of diabetes in colder regions.

Phase-contrast Magnetic Resonance Angiography of Foot at Ultra-high field 5 T System: Visualization of Distal Small Vessels and Enhancement by Warm Water Immersion

Ultra-high field strength MR system has been proved to offer improved visualization of the distal intracranial vessels and branches, but its effectiveness on peripheral vasculatures was not investigated. We aim to assess the visualization of lower-extremity vessels using three-dimensional phase contrast MR angiography (3D PC-MRA) at 5T field-strength through the feet with warm water immersion (WWI). Participants were prospectively recruited and underwent 3T, 5T 3D PC-MRA on feet with and without WWI (water temperature between 40 to 45 ℃ for a duration of 10minutes). Patients with suspected lower-extremity vessel diseases underwent CTA for lesion identification. Signal-to-noise ratio (SNR), subjective scoring, quantitative vessel segmentation and flow velocity were performed to assess vessel visualization before and after WWI. Friedman's test was conducted to determine statistical significance. Out of thirty participants (mean age, 46.2±5.9; males, 20; lower-extremity vessel disease, 10), 900 vessel segments were available for evaluation. 5T images showed significantly higher scores of image quality and foot vessel visualization than 3T (all P <.05). WWI further improved the visualizing scores (percentage of score 3: 40.2% vs 66.2%, P =.008), SNR (44.27 vs 67.78, P <.001), total branch count (151.92 ± 29.17 vs 225.63 ± 16.76; P <.001), and the flow velocity (0.72 ± 0.03 vs 0.48 ± 0.11cm/s; P <.001). 3D PC-MRA at 5T effectively visualizes foot vessels in patients with lower-extremity disease. Furthermore, WWI can significantly enhance the depiction of distal and small vessels.

Effects of water immersion on immune, intestinal flora and metabolome of Chinese mitten crab (Eriocheir sinensis) after air exposure

Air exposure stress can induce stress response of Eriocheir sinensis and affect its normal life activities. The goal of this study was to investigate the effects of water immersion on the recovery of hepatopancreas immune-related enzyme activity, intestinal microbial diversity and metabolic level of Chinese mitten crabs after exposure to air. The results show that immersion can effectively alleviate the adverse effects of air exposure on the antioxidant capacity and immune capacity of Chinese mitten crabs, and the longer the time of immersion, the more obvious the recovery effect. Among them, the levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and acid phosphatase significantly increased after exposure to air (P < 0.05), reached a peak at 3 h, began to decline after immersion, and returned to a level close to the initial value at 24 h (P < 0.05). In addition, after exposure to air, the glucose and total cholesterol in haemolymph of Eriocheir sinensis were significantly different from the initial values (P < 0.05), gradually recovered to the initial level after re-immersion. However, changes in intestinal flora and hepatopancreas metabolism caused by air exposure did not fully recover after water exposure, and its negative effects did not completely disappear. The sequencing results showed that the species composition and diversity of intestinal microorganisms of Chinese mitten crab changed after air exposure and immersion treatment. The relative abundance of Actinomycetes increased significantly, while that of Proteobacteria and Firmicutes decreased significantly. Metabolomics analysis showed that air exposure and immersion destroyed the metabolic balance of amino acids and carnitine, reduced the level of carnitine metabolism, hindered the absorption of nutrients, and led to the accumulation of harmful substances.

Influence of low voltage programmed thawing on the quality of frozen pork and its myofibrillar protein

This study explored the effects of low voltage programmed thawing (LVPT) on thawing period, water status, current density as well as physicochemical properties of porcine longissimus dorsi muscle, considering air thawing (AT), water immersion thawing (WT) and cold storage thawing (CST) for the comparison, additionally making fresh meat (FM) as the control. The thawing process used current limiting to gradually reduce the maximum output current to 500, 200 and 100 mA, respectively, by applying a safe voltage of 35 V in a home defrosting apparatus. Using two pairs of foil plate, the thawing (LVPT-2) with dual current loop accelerated the melting of ice crystals than the process with one pair of polar plate (LVPT-1) with one current loop. From −18 °C to −1 °C, the thawing period of LVPT-2 was reduced by 14.54 %, 11.72 %, and 15.95 % compared with that of LVPT-1 for samples within the thickness of 2, 3 and 4 cm, respectively. During the process, the intensity and density of the current loaded on the frozen meat gradually increased. LVPT-1 retained water and reduced its migration inside the meat, and protein solubility was better maintained. As the thickness increased, the effect of LVPT-2 on the moisture distribution and protein solubility of the sample decreased. LVPT-1 treatment resulted in less fat oxidation as well as stable secondary and tertiary structures of myofibrillar proteins compared to other treatments. At low voltage, the ability of LVPT −2 to maintain meat quality was reduced due to the increase in current density. In addition, LVPT-1 reduced muscle damage because of rapid melting of ice crystals. In contrast, LVPT-2 was conductive the formation of hot spots due to dual current loop passed through the pork in final phase of thawing, which would adversely influence the quality of thawed meat. Finally, LVPT could improve the rate of thawing, water binding capacity and meat quality, especially, there was no overheating effect on the meat because of current limiting.

Latex-Bridged Inverse Pickering Emulsion for Durable Superhydrophobic Coatings with Dual Antibacterial Activity.

There is agreement that every colloidal structure produces its own set of unique characteristics, properties, and applications. A colloidal phenomenon of latex-bridged water in a dimethyl carbonate (DMC) Pickering emulsion stabilized by R202 hydrophobic silica was investigated for its ability to act as a superhydrophobic coating (SHC) for cellulose substrates. First, various emulsion compositions were screened for their stability and droplet size. The final composition was then cross-examined by cryogenic scanning electron microscopy and optical and fluorescent microscopy to verify the colloidal structure. The drying pattern of the coating was investigated by using labeled samples under a fluorescent microscope and by scanning electron microscopy on a paper substrate. After the final ∼3 μm of dry coating was applied, it exhibited superhydrophobicity (advancing contact angle = 155°) and full functionality after 5 min at room temperature (RT). Coated samples maintained superhydrophobicity after 20 abrasion cycles and mechanical integrity after 50 s of water immersion. The SHC-coated paper demonstrated compatibility with a standard laser printer, and the coated paper demonstrated superhydrophobicity after printing. Finally, a propolis/DMC extract was produced and then analyzed by gas chromatography-mass spectroscopy (GC-MS) and infused into the SHC (PSHC). The newly formed PSHC demonstrated its ability to act effectively against E. coli biofilm and S. aureus planktonic cells and reduce their viability by over 90% and 99.99%, respectively.

Effect of Phosphoric Acid and Soluble Phosphate on the Properties of Magnesium Oxychloride Cement.

This study investigates the effects of phosphoric acid (H3PO4), potassium dihydrogen phosphate (KH2PO4) and sodium dihydrogen phosphate (NaH2PO4) admixtures on the setting time, compressive strength and water resistance of magnesium oxychloride cement (MOC). MOC samples incorporating different admixtures are prepared, and their hydration products and microstructures are studied via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that the addition of H3PO4, KH2PO4 and NaH2PO4 reduces the initial and final setting times and decreases the compressive strength. However, the compressive strength of MOC is higher than 30.00 MPa with the addition of 2.0 wt.% phosphoric acid and its phosphate after 14 days of air curing. The water resistance of modified MOC slurries is significantly improved. The softening coefficient of MOC with 2.0 wt.% H3PO4 is 1.2 after 14 days of water immersion, which is 3.44 times higher than that of the neat MOC. The enhancement in water resistance is attributed to the formation of amorphous gel facilitated by H3PO4, KH2PO4 and NaH2PO4. Furthermore, the improvement in water resistance is manifested as H3PO4 > KH2PO4 > NaH2PO4.

Time-dependent mechanical behavior analysis using Weibull models of cellulose hollow fiber membranes produced by green solvent

The mechanical behavior of sustainable (“green”), bio-based cellulose hollow fiber membranes (hereafter, hollow fiber) produced using green solvent, which is potential for desalination and solvent-resistant nanofiltration, can be evaluated either in dry or water-conditioned (wet) states. However, the effect of conditioning time on the mechanical behavior of hollow fibers has not been conclusive. In this work, an extensive evaluation involving an experimental campaign and rigorous application of statistical models for cellulose hollow fibers produced using green solvent (1-ethyl-3-methylimidazolium diethyl phosphate or [EMIM][DEP]) via a dry-jet spinning technique is reported. First, we evaluated the microstructures and separation performance (water permeation, solute rejection) of hollow fibers made of different cellulose concentrations (10–15 wt%) in both pristine and conditioned states. Then, the strength, stiffness, and ductility of hollow fiber samples of different gauge lengths (25 and 50 mm) were measured by a standard tensile test device. Here, the effect of conditioning time on mechanical properties was evaluated after the hollow fiber samples were water-immersed at different times (from 30 s to 2 months). The strength distribution of conditioned hollow fibers was modeled and analyzed using two-parameter and three-parameter Weibull models. Our results showed that the cellulose content of 15 wt% in the hollow fibers produced a denser microstructure, providing the lowest molecular weight cut-off (MWCO). The cellulose content and gauge length slightly modified the mechanical properties of hollow fibers when they were evaluated in pristine, dry conditions. The mechanical properties of hollow fibers were drastically reduced after 10 min of water immersion, beyond which their properties were stabilized. Weibull modeling of mechanical reliability showed that two- or three-parameter Weibull could estimate the failure probability of hollow fibers quite well. Nonetheless, the three-parameter Weibull is better than the two-parameter one in terms of accuracy in determining the threshold strength located at the “lower-end tail.” Our analysis provides a rigorous demonstration of Weibull modeling in evaluating the time-dependent mechanical behavior of ductile, cellulose-based hollow fiber membranes, which is essential to support the design and development of future hollow fiber membranes in desalination industries.

Design and Implementation of an Ultra-Wideband Water Immersion Antenna for Underwater Ultrasonic Sensing in Microwave-Induced Thermoacoustic Tomography

Microwave-induced thermoacoustic tomography (MITAT) holds significant promise in biomedical applications. It creates images using ultrasonic sensors to detect thermoacoustic signals induced by microwaves. The key to generating thermoacoustic signals that accurately reflect the fact is to achieve sufficient and uniform microwave power absorption of the testing target, which is closely tied to the microwave illumination provided by the antenna. In this article, we introduce a novel design and implementation of an ultra-wideband water immersion antenna for an MITAT system. We analyze and compare the advantages of selecting water as the background medium. Simulations are conducted to analyze the ultra-wideband characteristics in impedance matching, axial ratio, and radiation pattern of the proposed antenna. The measured |S11| shows good agreement with the simulated results. We also simulate the microwave power absorption of tumor and brain tissue, and the uniform microwave power absorption and high contrast between the tumor and brain indicate the excellent performance of the proposed antenna in the MITAT system.

Direct Measurement of the Diffusion Coefficient of Adhesives from Moisture Distribution in Adhesive Layers Using Near-Infrared Spectroscopy.

In this study, we used near-infrared spectroscopy to measure the moisture penetration in epoxy adhesives and investigated the difference in the diffusion coefficients between the bulk and the adhesive layer. Moisture diffusion was evaluated under 100% RH and water immersion conditions. First, the effects of the curing agents and additives on moisture diffusion in the bulk were gravimetrically evaluated using epoxy-coated quartz glass plates. Different diffusion behaviors were observed depending on the curing agent used. The presence of additives resulted in higher diffusion coefficients, whereas the overall moisture content was low. Next, the moisture distribution in the adhesive layer was visualized using a specimen sandwiched between the quartz glass plates, and the diffusion coefficient of the adhesive layer was calculated. The diffusion coefficient in the adhesive layer was larger than that in the bulk. For adhesives cured with hydrophobic diamine, the diffusion coefficient within the adhesive layer increased by approximately 1.5 times compared with that in the bulk, regardless of the exposure environment. The adhesive, composed of a resin, Dicyandiamide, and additives, showed a 2-fold increase in the diffusion coefficient under high-humidity exposure conditions but no significant change under the water immersion condition. Therefore, these results suggest that, for an accurate analysis of moisture distribution, it is important to measure the diffusion coefficient of the adhesive layer directly rather than using the diffusion coefficient of the material itself.

Radiation stability and durability of magnesium phosphate cement for radioactive reactive metals encapsulation

The encapsulation of Radioactive Reactive Metallic Waste (RRMW) in ordinary Portland cement poses significant challenges due to its incompatibility with the alkaline environment of the matrix. To address this issue, magnesium phosphate cements (MPC) emerge as potential solutions for the safe and effective immobilisation of RRMWs. The radiation stability and durability of an optimised formulation have been examined for samples irradiated up to 1000 kGy, in particular concerning the leaching behaviour of the three main constituents of the cement hydration products, and on four artificially added elements used to simulate radionuclides commonly found in radioactive waste (caesium, strontium, europium, and cobalt). The mortars exhibited excellent leaching behaviour and a high mechanical resistance, even after irradiation, freeze-thaw cycles, and water immersion. No significant radiation-induced effects were observed in the mineralogical and microstructural properties of the mortars, thus supporting their stability at the examined doses. Having verified the compliance with the main Italian waste acceptance criteria, the results of this research represent an encouraging step for the future implementation of MPCs for RRMWs conditioning.

Cold water immersion as an effective recovery method: its impact on heart rate and lactate levels post exercise

Cold water immersion as an effective recovery method: its impact on heart rate and lactate levels post exercise

Effects of Water Immersion Versus Epidural as Analgesic Methods during Labor among Low-Risk Women: A 10-Year Retrospective Cohort Study

Background: Adequate pain relief during childbirth is a very important issue for women and healthcare providers. This study investigates the effects on maternal and neonatal outcomes of two analgesic methods during labor: water immersion and epidural analgesia. Methods: In this retrospective observational cohort study at a first-level hospital, in Spain, from 2009 to 2019, 1134 women, low-risk singleton and at term pregnancy, were selected. Among them, 567 women used water immersion; 567 women used epidural analgesia for pain control. Maternal outcomes included mode of birth and perineum condition. Neonatal outcomes included 5 min Apgar score, umbilical cord arterial pH, and Neonatal Intensive Care Unit admissions. Chi-square tests and Mann–Whitney U tests, together with their effect sizes (Cramer’s V, odds ratio, and Cohen’s d) were used to test the main hypotheses. Results: Spontaneous vaginal birth was almost 17 times more likely in the water immersion group (OR = 16.866 [6.540, 43.480], p &lt; 0.001), whereas the odds of having a cesarean birth were almost 40 times higher in the epidural group (OR = 39.346 [3.610, 429.120], p &lt; 0.001). The odds of having an intact perineum were more than two times higher for the water immersion group (OR = 2.606 [1.290, 5.250], p = 0.007), whereas having an episiotomy was more than eight times more likely for the epidural group (OR = 8.307 [2.800, 24.610], p &lt; 0.001). Newborns in the water immersion group showed a better 5 min Apgar score and umbilical cord arterial pH and lower rates in admissions at the Neonatal Intensive Care Unit. Conclusions: Women choosing water immersion as an analgesic method were no more likely to experience adverse outcomes and presented better results than women choosing epidural analgesia.