Temperature Gradient Research Articles

Temporal and spatial dynamics of the non-indigenous bryozoan, Amathia verticillata, and its associated invertebrate community

The widespread non-indigenous bryozoan, Amathia verticillata primarily colonizes in coastal bays and harbors on anthropogenic structures. Although this habitat-forming bryozoan is widely recognized to house a variety of marine invertebrates within its structure, little is known about their spatiotemporal dynamics and their associated invertebrate community in Southern California, USA. Thus, we undertook a comprehensive yearlong study (July 2021-2022) in an urbanized estuary (Mission Bay, San Diego) to quantify A. verticillata percent cover and abiotic conditions at 6 stations with varying environmental conditions. The seasonal and spatial gradients in temperature and salinity within Mission Bay were as expected with seasonal hypersalinity typical of Mediterranean climate regions. The percent cover of A. verticillata was positively correlated with temperature with the highest percent cover found during the warmest periods, and higher average percent cover found in the warmer, eastern parts of Mission Bay. We also collected three replicate A. verticillata colonies to characterize the marine invertebrate community associated with this non-indigenous bryozoan. We identified 25 families, 24 genera, and 19 organisms to species belonging to the taxonomic groups: amphipods, isopods, tanaids, and polychaetes. Furthermore, we identified juvenile stages and ovigerous females living within A. verticillata. None of the identified invertebrate families contributed more than 21 % to the community. The seasonal growth and annual temporal patterns of A. verticillata may prevent competitively dominant species from becoming established within the invertebrate community and allow A. verticillata to harbor a diverse invertebrate community. Sphaeromatidae isopods were the most common family found in the bryozoan colonies, likely reflecting their broad environmental tolerances. Additionally, while some of the invertebrates found within A. verticillata were also non-indigenous species, more work needs to be done to determine if A. verticillata disproportionately supports these species over native species. Collectively, our results imply that A. verticillata functions as a nursery habitat on anthropogenic structures for peracarid crustaceans and polychaetes. Furthermore, A. verticillata assemble analogous communities across their distribution, which may indicate that invasions are homogenizing biota globally.

Transport coefficient sensitivities in a semi-analytic model for magnetized liner inertial fusion

Performance of magnetized liner inertial fusion (MagLIF) experiments is highly dependent on transport processes including magnetized heat flows and magnetic flux losses. Magnetohydrodynamic simulations used to model these experiments require a choice of model for the transport coefficients, which are the constants of proportionality relating driving terms, such as temperature gradients and currents, to the associated heat and magnetic field transport. The coefficients have been the subject of repeated recalculation using various methods throughout the years. Using a semi-analytic MagLIF model [McBride and Slutz, Phys. Plasmas 22, 052708 (2015)], we compare models for the transport coefficients provided by Braginskii [Reviews of Plasma Physics, edited by M. A. Leontovich (Consultants Bureau, New York, 1965), Vol. 1, p. 205], Epperlein and Haines [Phys. Fluids 29, 1029 (1986)], Ji and Held [Phys. Plasmas 20, 042114 (2013)], Davies et al. [Phys. Plasmas 28, 012305 (2021)], and Sadler et al. [Phys. Rev. Lett. 126, 075001 (2021)]. The choice of model modifies magnetic-flux losses caused by the Nernst thermoelectric effect and thermal conduction losses. We present simulated results from parameter scans conducted in order to compare the effects of the different models on parameters of interest in MagLIF. In some regions of parameter space, discrepancies of up to 38% are found in integrated quantities like the fusion yield. These results may serve as a guide for experimental validation of the various models, particularly as laser preheat energies and initial axial field strengths are increased on MagLIF experiments.

Numerical investigation of turbulent wake thermal effects on surface ships

To investigate the evolutionary mechanism of the thermal wake of surface ships, this study has proposed a numerical method for the thermal effects of turbulent wake and computed the near-wake fields for three ship schemes. The study indicates that the thermal wake, formed by vortices produced by the ship's movement and the propeller's rotation, propagates in a fine, thread-like pattern, setting it apart from the characteristic V-shaped diffusion of the Kelvin wake. The diffusion of thermal wake is divided into three distinct stages: formation, growth, and maturity. The thermal wakes generated by ships with shaftless rim-driven systems exhibit significantly lower diffusion rates, extents, and intensities compared to those created by ships with propeller propulsion systems. In summer, the center of the thermal wake exhibits a cold peak that is significantly lower than the ambient temperature. A reduction in temperature of greater than 0.05 K was observed for the three design schemes. In contrast, a warm peak that is above the environmental temperature is present at the edge of the wake. As the speed of the ship increases, the duration of each stage of the thermal wake lengthens and the diffusion range expands. When the temperature gradient is larger, the thermal wake becomes more intense. The findings of this study have revealed the evolution mechanisms of thermal effects in the wake of surface ships, thereby contributing to the advancement of knowledge in the fields of hydrodynamics and thermodynamics.

Effect of Source-Sink Misalignment and Sink Cavity Aspect Ratio on the Thermal Performance of Gallium Heat Sinks

Herein, we numerically investigated methods to improve heat dissipation from the base of a phase-change material (PCM) heat sink exposed to high heat flux (15 W/cm2). The sink cavity exhibited a rectangular cross-section with two opposite vertical walls of high thermal conductivity. These walls serve as heat-dissipating fins. We used gallium, a metallic PCM with high thermal conductivity and a low melting point to improve heat dissipation by leveraging buoyancy-driven circulations within the molten gallium. We adopted a method to position the sink base on top of the heat source surface in such a way to augment temperature gradients within the liquid to induce imbalances in gallium density and consequent internal circulations. In this technique, one vertical wall is subjected to forced-convective heat exchange with the surroundings, while the other remains adiabatic. Subsequently, for the case which showed optimum performance, we relaxed the adiabatic thermal boundary condition applied at one of the vertical walls and replaced it with convective heat transfer condition, and assessed the sink performance based on that. Further, we analyzed the impact of various aspect ratios of the sink cavity on the induced internal circulations and base cooling. Sink cavities with aspect ratios of 1.33, 0.96, and 0.64 corresponding to sink heights of 20, 17, and 14 mm, respectively, were examined under a consistent heat flux applied across a 15-mm base length. We also investigated the precise positioning of the sink base relative to the heat source surface and explored its influence on temperature gradients and gallium density imbalances crucial for induced internal circulations. Results indicate that a sink cavity aspect ratio of 0.96 yields the optimal heat dissipation from the base. Further, aligning the left bottom edge of the sink base with the left edge of the heat source surface maximizes heat dissipation to the ambient surroundings, thereby prolonging latent-heat dumping into the sink before the gallium completely melts. Any misalignment between the sink base and the surface of the heat source may have a profound impact on the temporal evolution of induced internal circulations within the molten gallium, essentially affecting heat dissipation from the sink base.

Ammonites as paleothermometers: Isotopically reconstructed temperatures of the Western Interior Seaway track global records

Ammonites are externally shelled cephalopods that were common in the North American Western Interior Seaway (WIS), and as they grew their aragonitic shells via accretion, they recorded aspects of their environment in the stable isotopic composition of their shells. While the mobility of ammonites may complicate efforts to reconstruct temperatures from their shells, they remain a potentially valuable target for paleothermometry. In this study, we reconstruct the spatial and temporal variability of WIS temperatures using a suite of ammonites (n = 113) spanning the last 25 million years of the Cretaceous along a North-South gradient ranging from the Canadian WIS to the Mississippi Embayment. We present a temporally high-resolution (~0.6 Ma) oxygen isotope record from these ammonites that indicates cooling temperatures in the WIS of comparable magnitude (~18 °C +/− 4°) to the temperature change seen in global studies, most notably cooling from the Cretaceous Thermal Maximum in the Turonian until the late Maastrichtian. Studies disagree regarding the development and strength of a latitudinal (pole-to-equator) temperature gradient during the Cretaceous; we do not see strong evidence for a latitudinal temperature gradient in the WIS. We do not observe any bias driven by ammonite morphology in our isotopic data, though we suggest that researchers consider the effects of taxonomy and ecological bias on their temperature records. As our ammonite δ18O record matches the direction and magnitude of global temperature reconstructions, our data imply that ammonites are viable targets for paleothermometry.

Toward quantitative thermoelectric characterization of (nano)materials by in-situ transmission electron microscopy

We explore the possibility to perform an in-situ transmission electron microscopy (TEM) thermoelectric characterization of materials. A differential heating element on a custom in-situ TEM microchip allows to generate a temperature gradient across the studied materials, which are simultaneously measured electrically. A thermovoltage was induced in all studied devices, whose sign corresponds to the sign of the Seebeck coefficient of the tested materials. The results indicate that in-situ thermoelectric TEM studies can help to profoundly understand fundamental aspects of thermoelectricity, which is exemplary demonstrated by tracking the thermovoltage during in-situ crystallization of an amorphous Ge thin film. We propose an improved in-situ TEM microchip design, which should facilitate a full quantitative measurement of the induced temperature gradient, the electrical and thermal conductivities, as well as the Seebeck coefficient. The benefit of the in-situ approach is the possibility to directly correlate the thermoelectric properties with the structure and chemical composition of the entire studied device down to the atomic level, including grain boundaries, dopants or crystal defects, and to trace its dynamic evolution upon heating or during the application of electrical currents.

Strategies used for knowledge dissemination and outreach in a renewable energy project

This work describes the actions carried out by participants of the Mexican Center for Innovation in Ocean Energy project (CEMIE-Océano) to disseminate their advances and results, to the general public and to the scientific community. The project was set up to assess the energy potential in Mexican coastal areas related to waves, tides and currents, and salinity and thermal gradients, and also to investigate their expected environmental and social impacts. The main actions by the CEMIE-Océano dissemination, outreach and press area, 2017 - 2023, were the design, construction and administration of the project website, the regular publication of activities and major achievements on social media via Facebook and Twitter, and the editing of 28 scientific books and nine editions of a biannual newsletter. Eight work meetings, three conferences and a range of science dissemination seminars were also organized. With the strategies presented in this work, for a value close to 3% of the total project budget, the participation of all the collaborators was achieved. In addition, the CEMIE-Océano project is widely recognised within the community of scientists from Mexico and Latin America, and others interested in renewable energies and energy transition issues. Keywords: CEMIE-Oceano project, ocean energy, dissemination, outreach.

Temperature alters antioxidant status and induces cell damage in the Amazonian fish tambaqui

Since Amazonian fish live close to their maximum thermal limits, this makes them vulnerable to the effects of global warming. The aim of this study was to evaluate the oxidative stress and antioxidant enzymatic and biochemical responses of the plasma, liver and muscle of tambaqui (Colossoma macropomum) exposed to a rising gradient of water temperature. One hundred and twenty (N=120) juvenile tambaqui were exposed to four temperature levels, these being: the environmental temperature of the season (Tenv – 25.7-30 ºC), 31 ºC, 34 ºC and 37 ºC, following a completely randomized design with three replicates for a period of 60 days. Liver and muscle samples were used to determine the levels of the enzymes superoxide dismutase (SOD), catalase (CAT) glutathione peroxidase (GPx) and lipid peroxidation (LPO). Plasma levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured. A histopathological damage assessment (HAI) was performed using liver samples and the results showed an increase in lipid peroxidation in the muscle and liver of animals kept at 37 ºC in relation to other temperatures. Enzyme responses were tissue-specific in the liver and muscle. In the liver, the reduction of CAT, SOD and GPx levels of the animals was observed at 37 ºC compared to those maintained at Tenv and SOD and GPx in relation to animals maintained at 31 and 34 ºC. The GPx enzyme showed higher activity at 34 and 37 ºC compared to the other evaluated temperatures. At 37 ºC, plasma levels of ALT and AST were higher than the other temperatures evaluated, as well as an increase in histopathological damage. In this way, in a scenario of warming of the waters of the Amazon or even of the systems used for rearing of the species, the tambaqui will be able to cope with temperatures of up to 34 ºC, without affecting its antioxidant capacity. However, at 37 ºC, oxidative stress levels and increased liver damage suggest a reduction in antioxidant capacity due to tissue impairment of the organ and general loss of animal performance as it approaches the upper thermal limit of the species.

Integration of ML methods with CR model-based optical diagnostic for the estimation of electron temperature in Ga laser produced plasma

Accelerated diagnostic of plasma plays a significant role in controlling and optimizing plasma-mediated processing, particularly for plasma with higher temporal and spatial gradients, such as laser produced plasma (LPP). In the present work, two advanced machine learning (ML) algorithms, random forest regression, and gradient boosting regression are integrated with noninvasive collisional radiative (CR) model-based optical diagnostics to facilitate accurate diagnostics. A comprehensive fine-structure resolved CR model framework is developed by incorporating our consistent cross section data obtained from the Relativistic Distorted Wave method [Suresh et al., “Fully relativistic distorted wave calculations of electron impact excitation of gallium atom: Cross sections relevant for plasma kinetic modelling,” Spectrochim. Acta B: At. Spectrosc. 213, 106860 (2024)]. An extensive dataset of CR model simulated intensities is created to train and test the ML methods. The present CR model is applied to characterize the Gallium LPP coupling with the optical emission spectroscopic measurements of Guo et al. [“Time-resolved spectroscopy analysis of Ga atom in laser induced plasma,” Laser Phys. 19, 1832–1837 (2009)] at different delay times. Further, a detailed correlation study of the line intensity ratios is performed to observe the qualitative behavior of the plasma parameters. The electron temperature results obtained from the CR model, ML, and line ratio methods were compared and found to be in excellent agreement. Overall, the present study demonstrates diagnostic approaches that can benefit the LPP community significantly by providing a rapid understanding of the plasma behavior across various operating conditions.

Ion-pair reversed-phase chromatography analysis of oligonucleotides using ultra-short (20 x 2.1 mm) columns. Tutorial

With this work, we present a comprehensive tutorial for the analysis of oligonucleotides (ONs, 5 to 100 mer) using ion-pair reversed-phase liquid chromatography (IP-RPLC) on ultra-short columns (20 × 2.1 mm). We explore the impact of ion-pairing (IP) agents on ON retention and demonstrate that while IP agents significantly influence absolute retention, their effect on selectivity is often minimal. Our findings emphasize the utility of systematic method development, including software-assisted retention modeling, to optimize gradient steepness and temperature such that resolution can be optimized for both sequence and length variants. We recommend the use of low-adsorption column hardware to minimize nonspecific interactions, which is to the benefit of improving method robustness, peak shapes and recovery (especially of shortmer impurities). Our results confirm the utility of so-called ultra-short column formats as is demonstrated by way of the example, quick run time separations and high-throughput ON analyses. The study establishes practical guidelines for developing robust, reproducible, and high-efficiency IP-RPLC methods for ONs which will be of assistance to analysts working on new therapeutics and new sequencing and diagnostic reagents alike.

Ion temperature gradient mode mitigation by energetic particles, mediated by forced-driven zonal flows

Ion temperature gradient mode mitigation by energetic particles, mediated by forced-driven zonal flows

Achieving an appropriate polarization-breakdown synergy of multilayer films for dielectric energy storage through temperature gradient annealing

Large polarization and high breakdown strength are the key to achieving an idea energy storage density in dielectric capacitors, but unfortunately the trade-off problem between them is difficult to evade, particularly for those dielectrics with different crystalline degrees. Herein, we propose an appropriate polarization-breakdown synergistic strategy of dielectric multilayer films through temperature gradient annealing. The dielectric properties of a serials of (Pb, La)(Zr, Ti)O3/SrTiO3/(Pb, La)(Zr, Ti)O3 (PLZT/STO/PLZT) structures with different annealing temperature for each layer are compared. The optimum recoverable energy density of 57.9 J/cm3 is achieved at a high breakdown electric field of 5.78 MV/cm and a moderate maximum polarization of 22.5 μC/cm2. In addition to the role of suppressing the carriers transport of interlayer STO, the balance between polarization and breakdown strength in bottom and top PLZT layers with individual dielectric characteristics should be responsible for the enhanced energy storage performance (ESP). The results suggest that it is a feasible way to optimize the ESP of dielectric multilayer films through designing different stacking layer via temperature gradient annealing heat treatment.

Cfd-based optimization of Direct evaporative cooling systems for canarian greenhouses in Semi-Arid regions

Direct Evaporative Cooling Systems (DECS) offer a promising solution for mitigating heat stress in greenhouses located in arid and semi-arid regins. To implement DECS efficiently in these regions, it is crucial to understand their impact on greenhouse microclimate parameters. This study investigates the influence of DECS on the microclimate within a canarian greenhouse and identifies key factors affecting their efficiency. Through Computational Fluid Dynamics (CFD) simulations using Ansys, we examined the effects of DECS on temperature, relative humidity, and air velocity within the greenhouse under semi-arid conditions.The results indicate that DECS efficiency is affected by several factors, including fan placement, evaporative pad height, fan spacing, and inlet air fan speed. Higher fan placement cools the upper canopy but increases humidity near the ceiling, whereas lower placement improves temperature uniformity but may require additional humidification. Closer fan spacing results in uneven air velocity, while wider spacing leads to stagnant zones within the greenhouse. Optimal placement of the the evaporative pad is crucial for maximizing the cooling coverage area and minimizes the temperature gradients. Inlet air fan speed also significantly impacts the microclimate, with higher speeds reducing both temperature and humidity. By optimizing these parameters, the DECS system was able to significantly decrease air temperature, increase humidity, and improve air velocity inside the greenhouse. With a pad height of 1.5 m, fans positioned at a height of 2 m, a distance of 6 m between each fan, and an air speed of 1.5 m/s at the entrance – the DECS enhances the local climate. Under these conditions, the mean air temperature drops from 40°C −in greenhouse with natural ventilation- to 21 °C using DECS, while relative humidity increases from 23 % −in greenhouse with natural ventilation- to 67 % using DECS, creating a more favorable environment for plant growth and potentially increasing crop yield and quality. Additionally, energy and environmental analyses show that implementing DECS in Canarian greenhouses, instead of traditional electrical cooling systems, results in substantial energy savings of 123,818.112 kWh/year annually and reduces carbon dioxide emissions by approximately 1.785 tons/year over a 20-year operational lifespan in a semi-arid climate.

Identification of flow patterns in an opaque condenser tube by distributed fiber Bragg gratings

Two-phase loops with phase change heat transfer are pivotal for cooling electronics under high heat flux and for thermal control in spacecraft. Numerous studies aim to clarify the mechanisms behind these loops to enhance cooling capacity and stability, which are closely tied to flow patterns. However, conventional flow pattern identification methods, requiring transparent tubes for direct observation, are impractical for simultaneous heat transfer measurement, especially during condensation. This paper introduces a novel approach for identifying flow patterns within an opaque, vertical condensation tube using embedded distributed fiber Bragg gratings (DFBGs) for R134a. The method involves a “fingerprint” derived from temperature profile derivatives and additional criteria based on temperature variation characteristics. These include the relative deviation from saturation temperature, the relative spatial temperature gradients, and the relative amplitude of temperature fluctuations. Validation against high-speed camera images confirms the method’s efficacy. It enables the determination of flow pattern lengths, the endpoint of condensation, and the construction of a flow regime map. Additionally, it allows for the measurement of vapor velocity in slug flow, facilitating the calculation of slip ratio and void fraction, which correlates reasonably with the Zuber-Findlay model, with systematic positive deviations up to 30%. This method also paves the way for simultaneous measurement of in-tube condensation heat transfer characteristics for various flow patterns.

Atmospheric Moisture Decreases Midlatitude Eddy Kinetic Energy

Abstract There is compelling evidence that atmospheric moisture may either increase or decrease midlatitude eddy kinetic energy (EKE). We reconcile these findings by using a hierarchy of idealized atmospheric models to demonstrate that moisture energizes individual eddies given fixed large-scale background winds and temperatures but makes those background conditions less favorable for eddy growth. For climates similar to the present day, the latter effect wins out, and moisture weakens midlatitude eddy activity. The model hierarchy includes a moist two-layer quasigeostrophic (QG) model and an idealized moist general circulation model (GCM). In the QG model, EKE increases when moisture is added to simulations with fixed baroclinicity, closely following a previously derived scaling. But in both models, moisture decreases EKE when environmental conditions are allowed to vary. We explain these results by examining the models’ mean available potential energy (MAPE) and by calculating terms in the models’ Lorenz energy cycles. In the QG model, the EKE decreases because precipitation preferentially forms on the poleward side of the jet, releasing latent heat where the model is relatively cold and decreasing the MAPE, hence the EKE. In the moist GCM, the MAPE primarily decreases because the midlatitude stability increases as the model is moistened, with reduced meridional temperature gradients playing a secondary role. Together, these results clarify moisture’s role in driving the midlatitude circulation and also highlight several drawbacks of QG models for studying moist processes in midlatitudes. Significance Statement Dry models of the atmosphere have played a central role in the study of large-scale atmospheric dynamics. But we know that moisture adds much complexity, associated with phase changes, its effect on atmospheric stability, and the release of latent heat during condensation. Here, we take an important step toward incorporating moisture into our understanding of midlatitude dynamics by reconciling two diverging lines of literature, which suggest that atmospheric moisture can either increase or decrease midlatitude eddy kinetic energy. We explain these opposing results by showing that moisture not only makes individual eddies more energetic but also makes the environment in which eddies form less favorable for eddy growth. For climates similar to the present day, the latter effect wins out such that moisture decreases atmospheric eddy kinetic energy. We demonstrate this point using several different idealized atmospheric models, which allow us to gradually add complexity and to smoothly vary between moist and dry climates. These results add fundamental understanding to how moisture affects midlatitude climates, including how its effects change in warmer and moisture climates, while also highlighting some drawbacks of the idealized atmospheric models.

Investigation of coupled thermo-hydro-mechanical processes on soil slopes in seasonally frozen regions

Freeze-thaw cycles significantly affect slope stability in seasonally frozen regions, posing serious threats to the functionality and safety of infrastructure. This study developed a coupled thermo-hydro-mechanical (THM) model of frozen soils that accounts for water migration, water-ice phase change, groundwater recharge, frost heave and thaw settlement deformation. The accuracy and reliability of the model was verified based on soil column test results. The change of temperature, water content, and displacement of a soil slope during freeze-thaw process was investigated. The results show that the water-heat transfer and deformation mainly occur in the shallow soils of the slope with changes in air temperature. The temperature fluctuations at the shoulder and face of the slope are more pronounced than those at the toe and crest of the slope. Water migration from the unfrozen zone to the freezing front due to the temperature gradient results in an increase in water content in the frozen zone. The slope shoulder exhibits the largest temperature fluctuations, leading to increased water migration and greater deformation. The rising groundwater table increases the total water content at the slope toe and base, exacerbating the frost heave and thaw settlement deformation, and reasonable groundwater table control intervals are provided. This study elucidates the thermo-hydro-mechanical coupling process and deformation mechanism of seasonally frozen soil slopes, and summarizes the failure modes, which provides a reference for the stability assessment and disaster prevention of soil slopes in cold regions.

Experimental and statistical investigation on temperature gradient of CFST truss chords

Experimental and statistical investigation on temperature gradient of CFST truss chords

Responses of vegetation low-growth to Extreme Climate Events on the Mongolian Plateau

Since the 21st century began, the frequency and intensity of extreme climate events have significantly increased globally, becoming a widely recognized phenomenon of global change. These extreme events, including droughts and heatwaves, have profound impacts on the structure and function of ecosystems. This study focuses on the Mongolian Plateau. It utilizes meteorological and remote sensing vegetation data, combined with consistency and sensitivity analyses. These approaches aim to provide an in-depth understanding of the relationship between various extreme climate events and vegetation low-growth. The study found that extreme drought and extreme heat events are the primary drivers affecting vegetation low-growth on the Mongolian Plateau. The analysis results indicate that the sensitivity of vegetation to these extreme climate events is regulated by regional hydrothermal conditions, with vegetation in long-term drought areas being more susceptible to the suppression of extreme drought, while humid areas exhibit some resistance. As the temperature gradient increases, the sensitivity of vegetation to extreme high temperatures increases, while sensitivity to extreme low temperatures decreases. Furthermore, the study also revealed differences in the responses of different vegetation types to extreme events under the same climatic conditions, highlighting the ecological basis of ecosystem resilience and adaptability. This research not only enhances our understanding of vegetation dynamics under the influence of extreme climate events but also provides scientific evidence for ecological management and climate adaptation in the Mongolian Plateau region.

Bacterial Diversity Along the Geothermal Gradients: Insights from the High-altitude Himalayan Hot Spring Habitats of Sikkim

Geothermal habitats present a unique opportunity to study microbial adaptation to varying temperature conditions. In such environments, distinct temperature gradients foster diverse microbial communities, each adapted to its optimal niche. However, the complex dynamics of bacterial populations in across these gradients high-altitude hot springs remain largely unexplored. We hypothesize that temperature is a primary driver of microbial diversity, and bacterial richness peaks at intermediate temperatures. To investigate this, we analysed bacterial diversity using 16S rRNA amplicon sequencing across three temperature regions: hot region of 56-65°C (hot spring), warm region of 35-37°C (path carrying hot spring water to the river), and cold region of 4-7°C (river basin). Our findings showed that Bacillota was the most abundant phylum (45.51%), followed by Pseudomonadota (32.81%) and Actinomycetota (7.2%). Bacillota and Chloroflexota flourished in the hot and warm regions, while Pseudomonadota thrived in cooler areas. Core microbiome analysis indicated that species richness was highest in the warm region, declining in both cold and hot regions. Interestingly, an anomaly was observed with Staphylococcus, which was more abundant in cases where ponds were used for bathing and recreation. In contrast, Clostridium was mostly found in cold regions, likely due to its viability in soil and ability to remain dormant as a spore-forming bacterium. The warm region showed the highest bacterial diversity, while richness decreased in both cold and hot regions. This highlights the temperature-dependent nature of microbial communities, with optimal diversity in moderate thermal conditions. The study offers new insights into microbial dynamics in high-altitude geothermal systems.

Effect of wall thickness on the precipitation behavior, microstructure, electrical conductivity and mechanical properties of copper alloy prepared by electron beam powder bed fusion

Electron beam powder bed fusion (EB-PBF) is one of the most promising technologies for preparing thin-walled copper alloy, because copper alloy have a high energy absorption rate for electron beam, and high preheating temperature can reduce the solidification temperature gradient and reduce the deformation of thin-walled parts. At present, there are few reports on the systematic research work on the EB-PBF of thin-walled CuCrZr alloy parts, and it's impossible to effectively supervise the production of complex thin-walled CuCrZr alloy parts. This work aims to investigate the effect of thickness on the microstructure and mechanical properties of CuCrZr alloy produced by EB-PBF. As the wall thickness decreases from 5.0 mm to 0.3 mm, the grain sizes of the XY and YZ planes decreased from 20.4 μm and 43.1 μm to 14.5 μm and 21.5 μm respectively, and the texture intensity decreased from 16.04 and 23.57 to 7.62 and 10.99. The analysis showed that Cr2O3 nanoprecipitates were precipitated in situ in the sample, and their average size decreased from 65.8 nm to 21.6 nm. Due to the reduction in grain and nanoprecipitate size, the performance of thin-walled samples is significantly enhanced, with yield strength (YS) increasing from 112 MPa to 165 MPa and conductivity increasing from 71.7 %IACS to 86.1 %IACS. Finally, the main contributions to the YS of specimens with different wall thicknesses was discussed. Precipitation strengthening and dislocation strengthening are the main strengthening mechanisms in thin-walled samples, and the gradual refinement of nano-precipitates is the main reason for the improvement of mechanical properties as the wall thickness decreases.