Temperature Variation Research Articles

On the thermo-visco-elastic behaviour of neat and aged PPS composites

Reinforced PPS thermoplastics exposed to variations in temperature and humidity are subject to aging and interface degradation. These phenomena can lead to ruptures due to the interphase weakening. In this study, a micromechanical model based on the equivalent inclusion model is implemented using the viscoelastic behaviours of the neat and aged grades identified by spectrometric analyses. The presented coated inclusion model allows to extract the viscoelastic behavior of the interphase in the dry-as-molded composite and in the aged composite by inverse method conducted for viscoelastic behavior. The presence of the interphase testifies to the degradation of the thermomechanical properties in the vicinity of the reinforcements. In the aged composite, the interphase also undergoes an aging phenomenon. Thus, the model compares the behavior of the interphase in the dry-as-molded and aged grades of the composite and separates the effects linked to the degradation of adhesion of the fibers from the effects linked to specific hydroscopic aging.

All-optical infrasound sensor based on a Fabry-Perot interferometer

Recent demands for infrasound measurement, whether for detecting violent atmospheric events or evaluating the environmental impact of wind farms, require new acoustic calibration standards in the frequency range below 2Hz. Expanding the frequency bandwidth of microphones remains a limited strategy since they are designed to filter out continuous components. An alternative method for measuring infrasound is proposed, which relies on a Fabry-Perot interferometer. This technique has been studied extensively for static pressure measurements with success. Therefore, adapting a Fabry-Perot refractometer to perform acoustic measurements is not only a technical challenge but also an opportunity to bridge the gap between static pressures and acoustic metrology. As acoustic movement involves both small pressure and temperature variations, it is important to account for their coupled effects in interferometer measurement results. Since the temperature variation field in the measurement system cannot be characterised experimentally, an analytical model has been developed. The chosen theoretical and technical solutions are validated by the good agreement between experimental results obtained with the refractometer carried out and other calibrated sensors in the frequency range from 40mHz to 1.5Hz. These results also highlight the improvements required to bring the device up to the level of an infrasound reference instrument.

Temperature-insensitive and cost-effective distributed NP-Doped optical fiber sensors

This paper presents the development of a cost-effective distributed optical fiber sensor for temperature-insensitive assessment of mechanical disturbances along an optical fiber cable. The proposed sensor system uses a nanoparticle (NP)-doped optical fiber with enhanced Rayleigh backscattering to provide higher sensitivity and spatial resolution using the transmission and reflection analysis (TRA) approach, where the transmitted and backscattered optical powers are analyzed as a function of the mechanical disturbance. In addition, Fiber Bragg Gratings (FBGs) are used as wavelength filters to provide the wavelength division multiplexing of the proposed device, which enable the use of 3 different NP-doped optical fiber sections for simultaneous detection of multiple curvature conditions in a cost-effective distributed sensing approach. The sensor characterization tests are performed by means of applying curvature angles from 360° to 1080° at different positions along NP-doped fibers (namely 25 mm, 100 mm and 175 mm) at 4 different temperatures of 25 °C, 30 °C, 40 °C and 50 °C. The results indicate the feasibility of the proposed approach, where the temperature variations lead only to a wavelength shift of the Bragg wavelength, whereas the mechanical disturbances (the curvatures) lead only to variations in the transmitted and reflected optical powers. Thus, by analyzing the transmitted and reflected optical powers in conjunction with the Bragg wavelength shift, it is possible to estimate both the mechanical disturbance amplitude (i.e., curvature angle) and the position along each NP-doped optical fiber section. Results indicate a relative error of around 3 % and 4 % for the mechanical disturbance location and absolute value, respectively. Moreover, the temperature cross-sensitivity in this case is below 2 % considering both amplitude and location of the mechanical disturbance. The proposed approach can be applied in structural health monitoring of different types of structures by integrating the fibers in the structures themselves with the possibility of measuring the strain distribution along the fibers (instead of in different points along the fiber) using a lower cost hardware when compared with similar distributed optical fiber sensing approaches.

Temperature effect on acoustic waves reflection condition in anisotropic crystals

The reflection of acoustic waves in anisotropic media has found important applications in acousto-optics (AO). It may be realized both with changing the type of acoustic mode and without it. The latter case is applied for the realization of the quasi-collinear AO diffraction geometry for which the incident light and ultrasound wave group velocity vectors are collinear. The acoustic wave involved into the AO interaction exists due to the reflection from the AO cell input optical face. Quasi-collinear configuration of AO interaction enables achieving exceptionally high spectral resolution and diffraction efficiency, therefore, it is applied for the laser pulse shaping. However, the application of AO tunable filters for such purposes requires high acoustic power values, which induce the temperature gradients in the AO crystal. Temperature variations influence the stiffness constants of the AO crystal, impacting the characteristics of incident and reflected acoustic waves, affecting the acoustic wave reflection condition and consequently, the AO diffraction characteristics. This study presents the theoretical and experimental examination of the temperature influence on the acoustic beam reflection in anisotropic crystals on the example of tellurium dioxide crystal. This paper is supported by the Russian Science Foundation, grant 23-12-00057.

The start-up characteristics of a novel loop heat pipe with stainless steel capillary wick

Loop heat pipe (LHP) is an advanced thermal management technology that utilizes liquid–vapor phase change and capillary action to achieve efficient heat transfer across long distances and in various directions. The start-up of an LHP is crucial for its reliable and stable operation. This study aims to explore the start-up characteristics and temperature variations of various components under different heating conditions by designing a cost-effective flat plate evaporator LHP with a stainless-steel casing and acetone as the working fluid. The experimental analysis examined the performance of the LHP under varying heating powers from 28 to 60 W, positions, and gravity angles. The findings revealed that the LHP successfully started at 28 W, and a temperature overshoot occured when the heating position was near the compensation chamber. Notably, the start-up time was 400 s faster compared to the heating condition near the mean pressure chamber. When the evaporator was tilted such that the compensation chamber was above the evaporator’s pressure equalization chamber, circulation within the LHP could not be established. The thermal resistance of the LHP decreased with increasing heating power, achieving a maximum reduction of 51.51 %. When both the compensation chamber and the mean pressure chamber were heated simultaneously, the impact of the gravity inclination angle on thermal resistance was minimized. This study introduces an innovative capillary wick LHP with high start-up success rates and cost-effectiveness, providing both empirical data and theoretical insights for the refinement and optimization of civilian LHP designs.

NUMERICAL MODELING OF TWO-PHASE HEAT TRANSFER DURING EVAPORATION AND CONDENSATION INSIDE A SOLAR STILL

This research presents a comparative analysis of two solar still configurations utilizing the ANSYS 2023R2 software package for computational fluid dynamics (CFD) simulations. The study employs the Volume of Fluid (VoF) model to simulate phase transitions between liquid and vapor, specifically focusing on vaporization processes. It is important to note that the VoF model used in this study primarily serves to visualize vaporization, with its numerical results aligning with theoretical expectations rather than providing practical applications. The relevance of this research is underscored by the global drinking water crisis, which drives the need to enhance the efficiency of desalination systems. Solar distillation is recognized as one of the most environmentally sustainable methods for producing clean water, making it an appropriate focus for this investigation. The primary objective of this work is to conduct a numerical analysis of the solar still, compare the performance of two different configurations, and evaluate potential modifications to improve the system's efficiency. The study simulates heat transfer processes within the distiller, the distribution of vapor volume fractions, and temperature variations over time. The findings indicate that the dual-slope configuration outperforms the single-slope configuration in terms of efficiency and productivity. Additionally, the research provides insights into the physical processes occurring within the distiller and identifies potential areas for further refinement of the system's modeling in ANSYS.

Optimization of heat transfer in PCM based triple tube heat exchanger using multitudinous fins and eccentric tube

This study aims to analyze the effect of incorporating a hybrid concept of heat transfer enhancement using extended surfaces and eccentricity of the inner tube in an RT-82 phase change material-based horizontal triple tube heat exchanger. Three types of fins were used, namely longitudinal, arc and triangular shape fins, as per suitability for better heat transfer. Moreover, the concept of eccentricity was also implemented to make PCM melt faster. The novelty of the present study lies in optimizing the heat transfer enhancement by proper placement of the fins and eccentric inner tube arrangement. A conduction-convection model was used to examine the thermal performance of a triple tube heat exchanger. The natural convection of PCM was employed using the Boussinesq approximation. The governing equations were solved using finite volume-based Ansys Fluent 2021 R2 software. The performance study of phase change material was based on transient variation of liquid fraction and average temperature. The optimum model showed a 63.87 % reduction in melting time and a 175.16 % improvement in heat transfer rate compared to a simple triple tube heat exchanger to achieve the unit liquid fraction. It is also observed from the calculation of the Rayleigh number that the conduction became more dominant than the convection phenomenon in the fin based model. The main finding of the present study is the use of triangular fins on the base along with the curved fins at the lower middle section because this arrangement shows high heat penetration capability. The results indicate that fins selection and placement significantly enhance the heat transfer rate.

Residential exposure to Aspergillus spp. is associated with exacerbations in COPD.

Sensitisation to Aspergillus fumigatus is linked to worse outcomes in patients with chronic obstructive pulmonary disease (COPD), however, its prevalence and clinical implications in domestic (residential) settings remains unknown. Individuals with COPD (n=43) recruited in Singapore had their residences prospectively sampled and assessed by shotgun metagenomic sequencing including indoor air, outdoor air, and touch surfaces (total: 126 specimens). The abundance of environmental A. fumigatus and the occurrence of A. fumigatus (Asp f) allergens in the environment were determined and immunological responses to A. fumigatus allergens determined in association with clinical outcomes including exacerbation frequency. Findings were validated in 12 individuals (31 specimens) with COPD in Vancouver, Canada, a climatically different region. 157 metagenomes from 43 homes were assessed. Eleven and nine separate Aspergillus spp. were identified in Singapore and Vancouver respectively. Despite climatic, temperature, and humidity variation, A. fumigatus was detectable in the environment from both locations. The relative abundance of environmental A. fumigatus was significantly associated with exacerbation frequency in both Singapore (r=0.27, p=0.003) and Vancouver (r=0.49, p=0.01) and individuals with higher Asp f 3 sensitisation responses lived in homes with a greater abundance of environmental Asp f 3 allergens (p=0.037). Patients exposed and sensitised to Asp f 3 allergens demonstrated a higher rate of COPD exacerbations at 1-year follow-up (p=0.021). Environmental A. fumigatus exposure in the home environment including air and surfaces with resulting sensitisation carries pathogenic potential in individuals with COPD. Targeting domestic A. fumigatus abundance may reduce COPD exacerbations.

Transient temperature and pressure coupling model of cementing injection stage in ultra deep wells considering segmental rheological model, casing eccentricity and U-tube effect

The geological environments of ultra deep wells such as high temperature and high pressure (HTHP), narrow safety density window pose significant challenges to cementing operation. Considering segmental rheological model and density model, casing eccentricity, U-tube effect and viscous dissipation, this paper established a transient temperature and pressure coupling model during cementing injection stage of ultra deep wells. The segmental rheological model can describe the rheological properties of cementing fluids under HTHP much better. Considering casing eccentricity and viscous dissipation can accurately model the variation of temperature and pressure profiles. Taking U-tube effect into the model, the formation process of vacuum section at top of the casing can be simulated. The fully implicit finite-difference approach was used to solve the coupling model, and the calculation results were compared with field measurement data and simulation data to verify its accuracy. The calculation errors of the developed model are respectively 10% and 5% compared to field measurement data and Wellplan’s simulation data. Numerical simulations were conducted to reveal the cementing fluid distribution, transient temperature distribution and pressure distribution during the cementing injection stage. The simulation results show that the variety of cementing fluids with different density, rheological properties and thermophysical parameters complicates the change mechanism of temperature and pressure. The temperature and pressure distributions both present unsteady characteristics during cementing injection stage, which puts forward higher requirements of pressure control for narrow safety density window formation. The influence of temperature and pressure on rheology of cementing fluids cannot be ignored, and segmental rheological model should be considered for accurate pressure prediction. Also the casing eccentricity cannot be ignored for cementing pressure calculation in deviated or horizontal wells. Managed pressure cementing (MPC) has a greater advantage in dealing with narrow density window formation. The synergistic control of cementing fluid density and back pressure can keep the equivalent circulating density (ECD) within the safe density window. Through the application of the transient temperature and pressure coupling model, we can simulate the variations of key dynamic parameters during cementing injection stage and optimize the cementing parameters.

Cement-Formation Debonding Due to Temperature Variation in Geothermal Wells: An Intensive Numerical Simulation Assessment

Cement-Formation Debonding Due to Temperature Variation in Geothermal Wells: An Intensive Numerical Simulation Assessment

Design, fabrication, and calibration of a micromachined thermocouple for biological applications in temperature monitoring

This paper presents a microneedle thermocouple probe designed for temperature measurements in biological samples, addressing a critical need in the field of biology. Fabricated on a Silicon-On-Insulator (SOI) wafer, the probe features a doped silicon (Si)/chrome (Cr)/gold (Au) junction, providing a high Seebeck coefficient, rapid response times, and excellent temperature resolution. The microfabrication process produces a microneedle with a triangular sensing junction. Finite Element Analysis (FEA) was employed to evaluate the thermal time constant and structural integrity in tissue, supporting the probe's suitability for biological applications. Experimental validation included temperature measurements in ex-vivo tissue and live Xenopus laevis oocytes. Notably, intracellular thermogenesis was detected by increasing extracellular potassium concentration to depolarize the oocyte membrane, resulting in a measurable temperature rise. These findings highlight the probe's potential as a robust tool for monitoring temperature variations in biological systems.

Temperature variations and frozen zone migration: assessing the influence of climate change on fatigue cracking in roadway asphalt pavements – a case study of seven provinces in China

Both temperature fluctuations and migrations in frozen zone distribution resulting from climate change can influence fatigue cracking in asphalt pavement. This study focused on seven provinces in China, utilising climate prediction data from 2021 to 2100 to analyse temperature variations and frozen zone migrations over the next 80 years. The study calculated the fatigue cracking of asphalt pavements on freeways and secondary roadways under the influence of these two factors. Additionally, a Fatigue Cracking Climate Index (FCCI) was introduced to reflect the extent of climate change impact on fatigue cracking. Research findings indicate that the rising temperatures associated with climate change adversely affect fatigue cracking. Conversely, the migration of frozen zones tends to alleviate this adverse impact. Overall, fatigue cracking is gradually exacerbated under the influence of climate change. In the region of interest, a majority of the asphalt pavements experience negative effects from climate change on fatigue cracking.

Weak signal ultrafast interrogation of a micro-nano FBG probe sensor based on the hybrid amplified dispersion Fourier-transform method

To elucidate the thermal transport mechanisms at interfaces in micro- and nanoscale electronic devices, real-time monitoring of temperature variations at the microscopic and nanoscopic levels is crucial. Micro-nano fiber Bragg grating (FBG) sensors have been demonstrated as effective in-situ optical temperature probes for measuring local temperatures. Time-stretch dispersion Fourier transform (TS-DFT) that enables fast, continuous, single-shot measurements in optical sensing has been integrated with a micro-nano FBG probe (FBGP) for local temperature sensing. However, its temperature sensitivity and interrogation resolution are limited by the detection sensitivity. In this paper, we propose a hybrid amplified dispersion Fourier transform (ADFT) method to achieve ultrafast interrogation of FBGP’s weak signal. Thanks to the combined effect of TS-DFT and hybrid optical amplification, the reflection signal of the FBGP is amplified, and the wavelength shift of the FBGP sensor is converted to a temporal spacing change between two dispersed pulses through dispersion-induced wavelength-to-time mapping. The proposed method uses a homemade dissipative soliton mode-locked laser as the light source. The hybrid optical amplification technique comprises a L-band erbium-doped fiber amplifier and a distributed Raman amplifier. Their noise figure and net gain for the FBGP are 4.81 dB and 15.93 dB, respectively. In addition, the temperature calibration experiments show that a sampling rate of 51.43 MHz and the maximum temperature measurement error of 1.98°C are achieved within the temperature range of 20.3°C to 97°C. The stability of the net gain provided by the hybrid ADFT system is demonstrated by the coefficient of variation, which ranges from 2.22% to 2.95% in the peak voltage signal of the FBGP. This approach applies to scenarios requiring the handling of weak optical signals, particularly in temperature measurement at the micro-nano scale.

A novel bionic lotus leaf channel liquid cooling plate for enhanced thermal management of lithium-ion batteries

Battery Thermal Management Systems (BTMS) are pivotal in safeguarding the safety, efficiency, and lifespan of electric vehicles. In this study, we propose a bionic lotus leaf (BLL) channel liquid-cooled plate to mitigate temperature accumulation issues observed during lithium-ion battery (LIB) discharge. The primary objective is to enhance heat dissipation and achieve uniform temperature distribution within LIBs. We investigated the impact of different interior configurations and mass flow rates on individual lithium-ion battery (LIB) temperatures using single-variable analysis. Our findings indicate that higher inlet mass flow rates effectively lower the temperature increase in individual LIBs, albeit at the cost of inducing a significant pressure drop.The optimal parameter combination is determined through orthogonal analysis. Specifically, the channel angle (α) and inlet mass flow rate (M) are found to significantly influence the maximum temperature (Tmax) of LIBs. The number of channels (N) is optimized to enhance temperature distribution and reduce maximum temperature variation (ΔTmax) within LIBs. Furthermore, adjusting the channel width (D) substantially mitigated pressure drop (ΔP) in the BLL channel liquid cooling plate, thereby improving hydraulic pump efficiency. The identified optimal combination (M = 1.0 g s-1, N = 4, D = 2.5 mm, α = 90°) ensures that Tmax remains below 29.732 °C even during a 5C discharge, a critical requirement. Compared to a traditional serpentine channel with equivalent heat transfer area and inlet mass flow, the optimized BLL channel showed a decrease in Tmax by 0.776 °C, ΔTmax reduction by 2.445 °C, and ΔP reduced to only 43.44 % of that in the serpentine channel. The BLL channel proposed in this research can serve as a valuable reference for BTMS.

Optimization of solid oxide electrolysis cells using concentrated solar-thermal energy storage: A hybrid deep learning approach

The Solid Oxide Electrolysis Cell (SOEC) represents a cutting-edge solution for the conversion of CO2 and H2O into syngas, offering significant economic and environmental benefits. However, the process requires substantial high-temperature heat inputs, traditionally supplied by electricity. This study introduces a novel approach leveraging concentrated solar radiation as a renewable heat source for SOEC, addressing the challenge of its inherent fluctuations through the integration of Thermal Energy Storage (TES) systems. We propose a hybrid model that combines multi-physics simulation with a deep learning algorithm, enabling rapid optimization of the electrolysis process under real-time direct normal irradiance conditions. Our findings demonstrate that the inclusion of TES within the system architecture results in a remarkable 53 % reduction in temperature variation rate at the SOEC inlet, ensuring operational stability and efficiency. Furthermore, by fine-tuning capacity parameters, we have developed a control strategy that harmonizes efficiency with safety performance. The robustness of our system is underscored by its resilience to step changes, achieving a 75 % reduction in temperature fluctuations. This research contributes a pioneering method for the real-time optimization and control of SOEC systems, harnessing the power of TES to drive sustainable energy conversion with enhanced reliability and economic viability, facilitating precise and swift predictive capabilities even under dynamic operating conditions.

Temperature-Driven Stopped-Flow Experiments for Investigating the Initial Aggregation of the α-Synuclein Amyloid Protein, Focusing on Active and Inactive Phases.

The primary objective of this research is to further examine the events occurring during the active or burst phase by focusing on the aggregation of the Syn amyloid protein. Regarding this aspect, it was initially conducted rapid temperature variations using stopped-flow spectrometry and tyrosyl group fluorescence emission detection, within the initial 500 milliseconds in buffered Syn solutions at pH 7, exploring various temperature ranges to investigate protein aggregation. The results obtained were contrasted with results obtained for the Nα-acetyl-L-tyrosinamide (NAYA) parent compound in the same conditions. The utilization of the NAYA compound is suitable as it mimics the peptide bonds in proteins and contains a tyrosyl group resembling the four tyrosyl groups found in the Syn protein structure (the protein has no tryptophan residues). Furthermore, the NAYA compound adopts an intramolecularly hydrogen-bonded structure even in an aqueous solution, similar to the interactions seen in the hydrophilic face of β-sheets. Additionally, the Syn protein system can exhibit the presence of β-sheets as a result of the existence of very low abundant Syn amyloid precursor forms or nuclei during the initial stages of the protein aggregation. Thus, a relationship is present between the molecular processes in the NAYA and Syn protein systems, making the NAYA's application crucial in this research. Moreover, to aid in understanding the results, it was also compared the events during the quiescent or inactive phase (30-500 milliseconds) with those in the burst phase (up to 10 milliseconds) using stopped-flow spectrometry conditions. Steady-state measurements were beneficial in comprehending the occurrences in both the quiescent and burst phases examined. Although protein aggregation and disaggregation were observed during the quiescent phase, determining these processes in the burst phase was more challenging. In the latter case, the aggregation of the Syn protein is actually initiated by the interaction of the intrinsically disordered Syn monomers. In the quiescent phase, first-order rate constants were measured and analysis showed that Syn protein aggregation and disaggregation occur simultaneously. At lower temperatures, early protein disaggregation outweighs protein aggregation whereas at higher temperatures protein disaggregation and aggregation are rather similar. It is also need to highlight that the burst phase, while distinct from the quiescent phase, can be considered as a possible structural phase for obtaining details about the aggregation of this specific disordered protein in solution on a very short timescale.

Feasibility Study of Rubber Seeds from North Sumatra, Indonesia as Biodiesel Feedstock; Production and Characterization

Abstract There are 5.5 million tons of rubber seeds produced annually on the 3.6 million hectares of rubber plantations that are located in Indonesia. Based on current estimates, 2.4 million tons of biodiesel may be produced if the rubber seeds are utilized as the primary raw material. Rubber seeds are a product of rubber plantations that have not been exploited; to obtain them, there is no need for new land or planting new trees. Rubber seeds are also non-edible, so their use does not conflict with foodstuffs. The purpose of this study was to assess the feasibility of rubber seed as a raw material for biodiesel and to produce and characterise biodiesel from rubber seed. The rubber seeds that have been collected from smallholder plantations in the northern Sumatra region of Indonesia are peeled to separate them from the kernels. Rubber seed kernels are boiled for 4 hours to separate the sap. Kernels that have been boiled are drained and then dried in the sun for 2 days in sunny weather. Kernels that had been dried in the sun were pressed using a screw press, and crude rubber seed oil was obtained. This crude oil is produced into biodiesel through degumming, esterification, and trans-esterification stages. Biodiesel production was carried out with variations in the catalyst ratios of 0.25, 0.5, 0.75, and 1, variations in the ratio of oil/methanol (w/v) of 1:1.25, 1:1.5, 1:1.75 (g/ml), and 1:2, variations in temperature of 50 °C, 60 °C, 70 °C, and 80 °C, and reaction times of 70 minutes, 80 minutes, 90 minutes, and 100 minutes. For each of these variables, the yield of biodiesel produced was calculated. Then the resulting biodiesel is characterised by testing its psychochemical properties against ASTM standards, which include calorific value, oxidation stability, viscosity, density, acid content, cetane number, and flash point. In the experiment on the effect of the amount of catalyst, the largest yield of 85% was obtained when the catalyst ratio (%v/v) was 0.75; in the investigation of the effect of the molar ratio of oil and methanol, the largest yield of 88% was obtained at a ratio of 1.75; the maximum yield of 85% was also obtained at a reaction temperature of 60 °C and 89% at a reaction time of 100 minutes. Almost all of the properties meet ASTM standards, except for the acid value of 0.53 mg KOH/g, which is 0.03 mg KOH/g higher, whereas according to the ASTM D6751-D 664 standard, the maximum acid value is 0.5 mg KOH/g.

Assessment of water quality and emerging pollutants in two fish species from the mallorquin swamp in the Colombian Caribbean

The Mallorquín Swamp, an important ecosystem in Atlántico, Colombian Caribbean, underwent environmental monitoring at eight points during rainy, transition, and dry seasons. This was to assess water quality, seasonal variation, and the bioaccumulation of metals, emerging pollutants, and organic compounds in the fish Ariopsis canteri and Mugil incilis. Water parameters were analyzed using descriptive statistics and multifactorial ANOVA with the Tukey HSD test for seasonal differences. Normality and variance of the fish results were verified, and differences between groups were evaluated using ANOVA or Kruskal-Walli's method when data transformation failed. Spearman correlation was used to relate the results. Water sampling revealed variations in temperature, dissolved oxygen, salinity, and nutrient levels. Significant differences in alkalinity and hardness were observed across seasons and sample points. The most probable number (MPN) levels of Total coliform and E. coli peaked near areas with domestic wastewater inputs, reaching 5.4x106 and 4.0x106 MPN, respectively, indicating potential microbiological contamination of water. Fish samples revealed high concentrations of persistent substances such as methylmercury, polycyclic aromatic hydrocarbons (PAHs), and emerging pollutants. Heavy metal analysis showed elevated iron levels (5.28 ± 0.657 mg/L), while emerging pollutants, including ibuprofen (218 μg/L) and naproxen (343.89 μg/L), exhibited high concentrations near human settlements. Ariopsis canteri showed higher bioconcentration tendencies for methylmercury (238.5 ± 100 μg/kg), and acenaphthene (7782 ± 4123.8 μg/kg), possibly influenced by its feeding habits and habitat preferences. In contrast, Mugil incilis exhibited higher bioaccumulation trends of PAH (2376.23 ± 599.63 μg/kg acenaphthene) and emerging pollutants like galaxolide (139.49 ± 34.98 μg/kg), possibly due to its mobility and exposure to various contaminants in their environment. These findings emphasize the need to monitor and manage aquatic ecosystems' health to mitigate anthropogenic influences on water quality and biodiversity. This research serves as a reference for global conservation efforts, emphasizing the need for comprehensive monitoring and regulatory frameworks to protect aquatic environments and ensure their sustainability for future generations.

A numerical method for simulating variable density flows in membrane desalination systems

We present a novel method for simulating unsteady, variable density, fluid flows in membrane desalination systems. By assuming the density varies only with concentration and temperature, the scheme decouples the solution of the governing equations into two sequential blocks. The first solves the governing equations for the temperature and concentration fields, which are used to compute all thermophysical properties. The second block solves the conservation of mass and momentum equations for the velocity and pressure. We show that this is computationally more efficient than schemes that iterate over the full coupled equations in one block. We verify that the method achieves second-order spatial–temporal accuracy, and we use the method to investigate buoyancy-driven convection in a desalination process called vacuum membrane distillation. Specifically, we show that with gravity properly oriented, variations in temperature and concentration can trigger a double-diffusive instability that enhances mixing and improves water recovery. We also show that the instability can be strengthened by providing external heating.

Survival strategies of microalgae in response to fluctuating brine environments in Saroma-ko Lagoon sea ice, Hokkaido, Japan.

This study investigated the changes in sea ice temperature, microalgae species distribution, shape changes, and photosynthetic activity observed in the first-year ice that forms in winter in Saroma-ko Lagoon, Hokkaido, Japan. Temperatures at the bottom of the ice remained constant at -1.7°C, near the freezing point, while they varied between -6 and -1°C with diel fluctuations at the surface layer. Carefully collected algal samples showed high photosynthetic quantum yield and acclimation to the light intensities of individual ice layers; this indicates that the algal photosynthetic activity responds to dynamic changes in the ice environment, such as variations in temperature, salinity, and brine space. The algal communities consisted of more than 95% diatoms. Smaller algal cells were distributed in the upper layer of the sea ice compared to the lower layers. Chaetoceros sp., the dominant small-cell species, was evenly distributed throughout the layers. In contrast, Detonula confervacea, the dominant large-cell species, was unevenly distributed in the lower layer, with smaller colony size and cell volume in the upper layer. The shape differences observed in this species were thought to be a response to the changing environment within the first-year sea ice.