Sample Temperature Research Articles

Stability of Bipolar Plates in Proton Exchange Membrane Water Electrolysis: Dissolution Studies of Titanium and Stainless Steel

Due to its high current densities and fast system response proton exchange membrane water electrolysis (PEMWE) is an ideal system for green hydrogen production from renewable energies. However, its widespread use is still hindered by the high costs rendering the produced green hydrogen not competitive. Therefore, a cost reduction is highly needed. The bipolar plates (BPPs) are causing a colossal factor in material costs. They are usually produced from titanium and coated with even more expensive materials such as gold or platinum. A possible, cheaper alternative is stainless steel. However, it is suspected to suffer from corrosion leading to the leaching of cations that can poison the catalyst or membrane.[1] Thus, we investigated the stability of BPP materials, the currently used titanium, and its cheaper alternative stainless steel (316L).[2] Therefore, we use a modified scanning flow cell setup coupled to an inductively coupled plasma mass spectrometer for investigating the stability of both materials on-line, as well as with scanning electron microscopy. To mimic the conditions at the BPP under operation, deionized (DI) water and highly diluted (0.5 mM) H2SO4 are chosen as electrolytes combined with a sample temperature of 60 °C.For Ti, we show that the dissolution is negligible, whereas 316L corrodes. For 316L, in DI water mainly Cr dissolves, while in the H2SO4 solution, the dissolution is more pronounced, and all alloy components are detected. Besides the pH value, the applied potentials play a crucial for its stability. However, our findings suggest that the contamination for a typical full cell architecture remains below 1 ppm, even for the highest measured dissolution rate of SS 316L.These capabilities of on-line high-throughput stability tests for BPP materials are, furthermore, used to investigate the influence of contaminations, such as F- or Cl-, and of the temperature-dependence on the stability of 316L. These results give further insights into 316L stability as BPP material and therefore contribute to the development towards cost-effective PEMWE.[1] a) N. Rojas, M. Sánchez-Molina, G. Sevilla, E. Amores, E. Almandoz, J. Esparza, M. R. Cruz Vivas, C. Colominas, Int. J. Hydrogen Energy 2021, 46, 25929-25943; b) H. Becker, J. Murawski, D. V. Shinde, I. E. L. Stephens, G. Hinds, G. Smith, Sustain. Energy Fuels 2023, 7, 1565-1603.[2] L. Fiedler, T. C. Ma, B. Fritsch, J. H. Risse, M. Lechner, D. Dworschak, M. Merklein, K. J. J. Mayrhofer, A. Hutzler, ChemElectroChem 2023, e202300373. Figure 1

Comprehensive analysis of correlations between soil electrical resistivity and index geotechnical properties

This study investigates the relationships between soil electrical resistivity and key geotechnical properties to develop predictive models for designing grounding systems in electrical substations. Conducted on 30 soil samples from various different regions of Thailand, the research evaluates resistivity in relation to soil water content, plasticity index, and dry density. Using a comprehensive laboratory setup, the soil samples were evaluated under controlled conditions, including temperature, humidity, and salt content of the soil samples, to establish robust correlations between the measured resistivity and the index geotechnical parameters. The results reveal a significant inverse relationship between soil resistivity and water content, confirming that water content is a dominant factor influencing resistivity. Further analysis using multiple non-linear regression demonstrated strong correlations, indicating that a combination of water content, soil dry density, and plasticity index can predict soil resistivity with high reliability. This approach enables optimization of substation grounding designs to ensure operational safety and regulatory compliance. The study suggests that integrating these geotechnical assessments into standard grounding system design procedures can significantly improve the effectiveness and safety of electrical infrastructure. Recommendations for future research include expanding the dataset to encompass a broader range of soil types and investigating the effects of particle size and electrolyte content on soil resistivity. These enhancements aim to refine the predictive models and address the broader applicability of the results in diverse geological settings.

Thermal rock magnetic cycling (TRMC): a method to track thermal alteration details for palaeointensity interpretations

SUMMARY Accurate absolute palaeointensity is essential for understanding dynamo processes on the Earth and other planetary bodies. Although great efforts have been made to propose techniques to obtain magnetic field strength from rock samples, such as Thellier-series methods, the amount of high-fidelity palaeointensities remains limited. One primary reason for this is the thermal alteration of samples that pervasively occurred during palaeointensity experiments. In this study, we developed a comprehensive rock magnetic experiment, termed thermal rock magnetic cycling (TRMC), that can utilize measurements of critical rock magnetic properties at elevated temperatures during multiple heating-cooling cycles to track thermal changes in bulk samples and individual magnetic components with different Curie temperatures in samples for palaeointensity interpretations. We demonstrate this method on a Galapagos lava sample, GA 84.6. The results for this specimen revealed that GA 84.6v underwent thermophysical alteration throughout the TRMC experiment, resulting in changes in its remanence carrying capacity. These findings were then used to interpret the palaeointensity results of specimen GA 84.6c, which revealed that the two-slope Arai plot yielded two linear segments with distinct palaeointensity values that were both biased by thermophysical alteration. To further test the TRMC method, we selected another historical lava sample (HS 2) from Mt Lassen, detecting slight thermal-physical changes after heating the specimen HS 2–8C to a target temperature of 400 °C. We also isolated a stable magnetic component with a Curie temperature below 400 °C using the TRMC method, which may provide a more reliable palaeointensity estimate of 51 μT. By providing a method for tracking thermal alteration independent of palaeointensity experiments, the TRMC method can explore subtle, unrecognizable thermal alteration processes in less detailed palaeointensity measurements, which can help to assess the thermal stability of the measured samples and interpret the changes in the TRM unblocking spectrum and palaeointensity estimates, facilitating the acquisition of more reliable records for constrain the formation of the inner core and the evolution of Earth's magnetic field.

Characterization of the Core Face Irradiation Fixture at the Pennsylvania State University Breazeale Reactor

An efficient stacking method was applied to a multi-foil activation characterization of a core face fixture in Penn State’s TRIGA reactor using STAYSL PNNL software. The adjusted neutron energy spectra from the STAYSL PNNL software are in good agreement with the input MCNP models. The validated MCNP model was then used to predict the neutron energy spectrum within the core face fixture with a new lead shielding assembly in between the fixture and the core. Additional irradiation environment details such as the estimated gamma ray dose rates and sample temperatures provide a more comprehensive view of the core face fixture beyond the neutron energy spectrum, especially for more sensitive materials.

Experimental Study on Preparation of Inorganic Fibers from Circulating Fluidized Bed Boilers Ash.

The ash generated by Circulating Fluidized Bed (CFB) boilers is featured by its looseness and porosity, low content of glassy substances, and high contents of calcium (Ca) and sulfur (S), thus resulting in a low comprehensive utilization rate. Currently, the predominant treatment approach for CFB ash and slag is stacking, which may give rise to issues like environmental pollution. In this paper, CFB ash (with a CaO content of 7.64% and an SO3 content of 1.77%) was used as the main raw material. The high-temperature melting characteristics, viscosity-temperature characteristics, and initial crystallization temperature of samples with different acidity coefficients were investigated. The final drawing temperature range of the samples was determined, and mechanical property tests were conducted on the prepared inorganic fibers. The results show that the addition of dolomite powder has a significant reducing effect on the complete liquid phase temperature. The final drawing temperatures of the samples with different acidity coefficients range as follows: 1270-1318 °C; 1272-1351 °C; 1250-1372 °C; 1280-1380 °C; 1300-1382 °C; and 1310-1384 °C. The drawing temperature of this system is slightly lower than that of basalt fibers. Based on the test results of the mechanical properties of inorganic fibers, the Young's modulus of the inorganic fibers prepared through the experiment lies between 55 GPa and 74 GPa, which basically meets the performance requirements of inorganic fibers. Consequently, the method of preparing inorganic fibers by using CFB ash and dolomite powder is entirely feasible.

SERENADE. II. An ALMA Multiband Dust Continuum Analysis of 28 Galaxies at 5 < z < 8 and the Physical Origin of the Dust Temperature Evolution

We present an analysis of the Atacama Large Millimeter-submillimeter Array (ALMA) multiband dust continuum observations for 28 spectroscopically confirmed bright Lyman break galaxies at 5 < z < 8. Our sample consists of 11 galaxies at z ∼ 6 newly observed in our ALMA program, which substantially increases the number of 5 < z < 8 galaxies with both rest-frame 88 and 158 μm continuum observations, allowing us to simultaneously measure the IR luminosity and dust temperature for a statistical sample of z ≳ 5 galaxies for the first time. We derive the relationship between the ultraviolet (UV) slope (β UV) and infrared excess (IRX) for the z ∼ 6 galaxies, and find a shallower IRX–β UV relation compared to the previous results at z ∼ 2–4. Based on the IRX–β UV relation consistent with our results and the β UV–M UV relation including fainter galaxies in the literature, we find a limited contribution of the dust-obscured star formation to the total star formation rate density, ∼30% at z ∼ 6. Our measurements of the dust temperature at z ∼ 6–7, Tdust=40.9−9.1+10.0K on average, support a gentle increase of T dust from z = 0 to z ∼ 6–7. Using an analytic model with parameters consistent with recent James Webb Space Telescope results, we discuss that the observed redshift evolution of the dust temperature can be reproduced by an ∼0.6 dex decrease in the gas depletion timescale and ∼0.4 dex decrease in the metallicity. The variety of T dust observed at high redshifts can also be naturally explained by scatters around the star formation main sequence and average mass–metallicity relation including an extremely high dust temperature of T dust > 80 K observed in a galaxy at z = 8.3.

Estimating the firing temperature of a brick sample from a church convento archway ruin in Quipayo, Camarines Sur, Philippines

Estimating the firing temperature of a brick sample from a church convento archway ruin in Quipayo, Camarines Sur, Philippines

Characterization of Sequential Trial‐Curable Off‐Stoichiometric Amine‐Epoxy Thermosets with Ionic Liquids

This work aims to develop sequential trial‐curable off‐stoichiometric thermosets, patterning the approach upon the dual‐curing processing, which is a promising method to tailor material properties by combining two polymerization reactions. The presented epoxy resin systems are based on diglycidyl ether of bisphenol A (DG) as an epoxy resin, Gaskamine 240 (G) as a low‐temperature amine curing agent, and 1‐ethyl‐3‐methylimidazolium dicyanamide (IL) as an ionic liquid, which is known by its potential efficient latency. Therefore, three curing polymerization reactions take place, in contrast to common dual‐curable formulations. In this study, the target is to still separate the first curing process – which is the epoxy‐amine condensation reaction – from the remaining two curing processes, which are triggered by IL. The trial‐curable systems offer the possibility to achieve different intermediate materials, from highly viscous through shape‐conformable to rigid. This is attained by changing the relative contribution of the first and the other two curing steps, e.g. the change in the amount of G. Another motivation to use IL is to enhance the glass transition temperature of final samples; the values are between 84.4 and 152.2 °C.

Variation in elastic constants of plumbene with sample size and temperature estimated using bending and oscillation approaches: A Molecular dynamics simulation study

Two-dimensional (2D) nanomaterials, now days are attracting researchers round the globe for their irreconcilable structure and outstanding properties. Plumbene, referred as the cousin of graphene is the single-layered, hexagonally arranged atomic structure of lead. Previously bending and oscillation modeling were implemented to evaluate elastic constants of plumbene. We have studied the effect of increasing temperature and sample size on plumbene using the same loading methods. To perform our molecular dynamics (MD) simulation study a plumbene sheet is designed adopting multi-scale modeling. For the purpose of parroting an unfathomable perspective of elastic constants of the material for potent utilization in technological fields, under inconsistent loading situations scrutinization of plumbene sheets are overdone by molecular dynamics (MD) simulation. Current impetrated practices will rav experimental wriggle of designing plumbene sheets with meticulous elastic constants for coveted applications. Earlier Young’s modulus (E) of plumbene is estimated using bending and oscillation modeling of plumbene under variable loading conditions. Here, we have studied variation of elastic constants {i.e. Young’s modulus (E), Modulus of rigidity (G) and Bulk modulus (K)} of plumbene under the same loading conditions (i.e. bending and oscillation) with change in sample size and temperature using non-equilibrium molecular dynamics (NEMD) simulation technique.

Observation of the Liquid-Liquid Phase Separation of FUS-LC Using Vacuum-Ultraviolet Circular Dichroism Spectroscopy.

To reveal the structural mechanism by which the low-complexity domain of the fused in sarcoma protein (FUS-LC) mediates liquid-liquid phase separation (LLPS), we conducted a vacuum-ultraviolet circular dichroism (VUV-CD) spectroscopic study, a technique to analyze the secondary structures of proteins. The VUV-CD measurements were performed at the BL12 VUV-CD station at the Hiroshima Synchrotron Radiation Center (HiSOR) in Japan. CD spectra were measured between 180 and 260 nm while controlling the temperature of samples from 37°C to 5°C to obtain the LLPS of FUS-LC. The CD spectrum obtained at 37°C exhibited a large negative peak at 195 nm and a small negative shoulder near 220 nm. The peak intensity around 195 nm decreased as the sample temperature decreased. The spectral changes originated from the LLPS formation.

Effect of Different Types of Emulsifiers on the Physical Characteristics and Fat Bloom Stability of Dark Chocolate with Cocoa Butter Alternatives

An emulsifier is incorporated to delay the fat bloom formation and improve the overall quality of dark chocolate. This study aims to investigate the effects of different emulsifiers on the physical properties and stability of fat bloom in dark chocolate with cocoa butter alternatives (CBAs). Dark chocolate formulations were prepared containing different emulsifiers like lecithin, glycerol monostearate and a combination of both with CBAs like cocoa butter substitute (CBS) and cocoa butter replacer (CBR). Physical property analyses included hardness, snap texture, melting behaviour, pH, and water activity. The whiteness index was used to measure fat maturity. The results showed that the addition of lecithin, CBS, and CBR decreased the hardness value. Meanwhile, samples of chocolate formulation with the addition of glycerol monostearate (CB+GMS), and chocolate formulation with the addition of lecithin and glycerol monostearate (CB+2E), increased the hardness and snap texture. Besides, CBR increased the peak temperature, and emulsifiers increased the peak temperature in samples with CB and CBR while decreasing the melting enthalpy. Furthermore, the addition of CBA and emulsifiers improved the stability of the fat bloom. Therefore, mixed emulsifiers, which have favourable physical properties and higher fat bloom stability, are ideal for use in chocolate production. CBAs have the potential for practical application in chocolate production to improve fat bloom stability.

Thermal Behaviour of Cool-Pavement Materials Development using Palm Oil Shell Aggregate

Cool-pavement technology has emerged as a potential solution to environmental issues posed by the urban heat island phenomenon, with surface temperature acting as a vital parameter in the evaluation of its thermal performance. This study focuses on the thermal performance results of modified asphalt concrete mix, wherein palm oil shell (POS) serves as a replacement for fine aggregate. Modified asphalt samples prepared using the Marshall Mix Design, with varying degrees of fine aggregate substitution (0%, 10%, 20%, 30%, 40%, and 50%), underwent a 24-hour continuous surface temperature measurement over a span of 20 days, under real-world tropical climate conditions. The findings demonstrated that sample P5, comprising 50% fine aggregate substitution, exhibited the highest reduction in surface temperature when compared to control sample P0, registering a significant decrease of up to 3.29°C during the period of peak solar intensity. ANOVA test-based statistical analyses confirmed significantly lower temperatures for all test samples, barring sample P1 (10% aggregate replacement), relative to the control sample. The results highlight the efficacy of POS as a fine aggregate substitute in asphalt concrete, significantly lowering asphalt pavement surface temperature, thereby endorsing the potential use of POS-modified asphalt in cool-pavement applications.

Effect of intermediate processing treatment on the structure and mechanical properties of Al–4 wt%Cu–3 wt%Mn alloy manufactured by electromagnetic casting followed by high-pressure torsion (HPT)

In this work, a thermally stable model Al–4Cu–3Mn (wt%) alloy has been manufactured by electromagnetic casting (EMC), followed by compression, intermediate heat treatment and high-pressure torsion (HPT). Structural changes of the alloy during subsequent processing stages have been analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the X-ray diffraction (XRD). The results indicate that variations in the intermediate heat treatment temperature of the compressed samples lead to a significant difference in strain hardening and thermal stability after HPT. According to microstructure investigations the hardening of samples processed by HPT resulted from formation of mixture of grains and subgrains with high dislocation density as well as mechanical fragmentation of eutectic Al2Cu particles and precipitation of nanoscale Mn-rich dispersoids which are identified as Al6Mn. The intermediate heat treatment of the EMC rod at 350 ºC for 3 hours and heat treatment of HPT sample at 250 ºC for 5 hours exhibited the best mechanical properties in terms of ultimate tensile strength (UTS), yield strength (YS) and elongation (El), reaching 610 MPa, 560 MPa and 10 % respectively. At the same time intermediate annealing at 450 °C makes the HPT processing ineffective.

Synthesis of azelaic acid copolyester plasticizers and their application in PVC.

A series of 2-methyl-1,3-propanediol (MPO) modified azelaic acid and hexylene glycol copolyester (PHMAZ) plasticizers with varying contents were synthesized using a direct esterification melt polycondensation method, and their structures were characterized systematically. Analysis using infrared spectroscopy and nuclear magnetic resonance spectroscopy confirmed the synthesis of the designed copolyester structure. Gel permeation chromatography (GPC) tests indicated that the number average molecular weight of each copolyester sample ranged between 2000 and 3000. These copolyesters were used to plasticize polyvinyl chloride (PVC) resin, and the glass transition temperature of the plasticized PVC samples was tested using a differential scanning calorimeter (DSC). Further characterization of the plasticizing effects was conducted using an electronic universal testing machine. The research results showed that as the content of MPO increased, the plasticizing effect of the copolyester initially increased and then decreased. Specifically, the copolyester containing 45% MPO, PHMAZ-45, demonstrated the best plasticizing effect on PVC, with the glass transition temperature of the plasticized PVC system around -35 °C, elongation at break at 908.4%, and a plasticizing efficiency of 254.5%. Additionally, this new type of copolyester plasticizer uses bio-based raw materials, exhibits excellent plasticizing effects, and the preparation process is stable and controllable. It holds promising potential to replace traditional volatile and toxic phthalate esters, presenting significant industrial application value.

Effects of Lime Powder on the Properties of Portland Cement-Sulphoaluminate Cement Composite System at Low Temperature.

In order to reduce the risk of early freezing damage to cement-based materials in winter construction, lime powder was used to improve the properties of the Portland cement-sulphoaluminate cement (PC-CSA) composite system at low temperatures. In this study, the effects of lime powder dosage on the properties of a PC-CSA blended system with two proportions (PC:CSA = 9:1 and 7:3) at -10 °C were investigated, and the mechanisms of improvement were revealed. The results showed that the compressive strength of the PC-CSA composite system was effectively improved, and the setting time was shortened by the addition of lime powder. Lime powder could effectively act as an early heating source in the PC-CSA composite system, as the maximum temperature of samples exposed to sub-zero temperatures was increased and the time before dropping to 0 °C was prolonged by the addition of lime powder. The extra CH generated by the hydration of lime powder provided an added hydration path for C4A3S¯, which accelerated the formation of AFt at each stage. Frozen water as well as the early frost damage were effectively decreased by lime powder because of the faster consumption of free water at an early stage. The modification of the hydration products also contributed to the denseness of the microstructure.

Approaching the emissivity of CMAS at high temperatures by convenient thermocouple-based infrared thermography

It remains a grand challenge to probe the emissivity of calcium-magnesium-alumina-silicates (CMAS) at high temperatures. Herein, an innovative thermocouple-based infrared thermography (TBIT) method that combines a double hot thermocouple system and infrared (IR) camera is proposed to enable convenient measurement for CMAS emissivity at temperature >800 °C. To improve the measurement accuracy, a heat transfer model accounting for the possible uncertainty in temperature measurement is also developed to correct the real sample temperature on the hot thermocouple. On this basis, the feasibility of the TBIT method is verified by using the platinum-rhodium alloy as the benchmark. As a proof-of-principle demonstration, four different sets of CMAS samples, i.e., blast furnace (BF) slag are considered with their temperature-dependent emissivities characterized experimentally. It is found that the BF-like CMAS features an emissivity of 0.5–0.9 at 800–1500 °C. This research provides a fast, accurate and low-cost experiment effort to probe CMAS emissivity at high temperatures, which enriches the thermophysical properties of the CMAS materials.

Temperature calibration of sample rods for neutron diffraction apparatus in the range of 6–473 K

Abstract Internal stresses play a crucial part in determining a material’s properties, which emphasizes the significance of accurate stress measurement and analysis. Neutron diffraction technology is a very promising approach to studying the complex microstructural properties of many materials, especially with the growing demand for cryogenic studies. This new device has a robust load capacity of 50 kN and works smoothly in a wide temperature range of 6 K–473 K. Furthermore, the diffraction angle is 47 degrees broader. Regardless of the samples, we observed that a thermal balance point existed close to 180 K. Importantly, thermal resistance was eliminated by the use of an analytical method, which has an extraordinarily small error of 2%. Using this exact calibration methodology ensures that the sample temperature is accurate during the experiments. This work presents a crucial apparatus for investigating the complexity of internal stresses in materials and offers an effective method for estimating and managing sample temperatures while doing research.

Effect of heat treatment conditions on the phase transformation characteristics of nitinol

Nitinol is the most widely used shape memory alloy in medical applications. In this study, the effect of different heat treatment conditions on the phase transformation characteristics of medical-grade nitinol was investigated. Nickel-rich nitinol wires containing 50.6% nickel with a diameter of 120 μm were used in the experimental studies. The nitinol wires were heat treated for 10 minutes at heat treatment temperatures between 540 and 570 °C. Then, nitinol wires were heat treated at a heat treatment temperature of 550 °C between 8 and 14 minutes. The austenitic and martensitic transition temperatures of these samples were measured using differential scanning calorimetry (DSC). In the experiments with 10 minutes of heat treatment time, transition temperatures decreased, and hysteresis increased with the increase in heat treatment temperature. This is related to the amount of precipitates in the structure. In the experiments carried out at 550 °C, transition temperatures decreased, and hysteresis increased with increasing heat treatment time. Experimental studies showed that the austenite finish (Af) temperature of all nitinol wire samples was below 37 °C, and they will exhibit superelasticity in the human body.

Innovative strategies in yacon drying: Ethanol pretreatment and intermittent microwave drying.

The yacon roots are rich in fructooligosaccharides (FOS) and highly perishable. Drying is crucial for food quality and extending shelf life. However, preserving thermosensitive compounds, such as FOS, poses a challenge in conventional drying methods. In this regard, microwave drying and ethanol pretreatment (ET) have emerged as promising solutions for maintaining nutrients and reducing drying time (DT). The objective of this study was to assess how ET and sample temperature affect quality and process parameters during intermittent microwave drying of yacon. Drying at 52°C treated with ethanol was the one that stood out for presenting the highest fructan retention (64.1%), low DT, lower energy consumption (EC) (364.00±5.03kWhkgwater-1), higher retention of antioxidant capacity (73.9%) and total phenolic content (77.5%), and slight variation in color parameters. Therefore, microwave drying with a controlled temperature of yacon pretreated with ethanol effectively reduces DT and EC by maintaining quality parameters.

Methods for Color Center Preserving Hydrogen‐Termination of Diamond

AbstractChemical functionalization of diamond surfaces by hydrogen is an important method for controlling the charge state of near‐surface fluorescent color centers, an essential process in fabricating devices such as diamond field‐effect transistors and chemical sensors, and a required first step for realizing families of more complex terminations through subsequent chemical processing. In all these cases, termination is typically achieved using hydrogen plasma sources that can etch or damage the diamond, as well as deposited materials or embedded color centers. This work explores alternative methods for lower‐damage hydrogenation of diamond surfaces, specifically the annealing of diamond samples in high‐purity, non‐explosive mixtures of nitrogen and hydrogen gas, and the exposure of samples to microwave hydrogen plasmas in the absence of intentional stage heating. The effectiveness of these methods are characterized by x‐ray photoelectron spectroscopy (XPS), and comparison of the results to density‐functional modelling of the surface hydrogenation energetics implicates surface oxygen ligands as the primary factor limiting the termination quality of annealed samples. Finally, photoluminescence (PL) spectroscopy is used to verify that both the annealing and reduced sample temperature plasma methods are non‐destructive to near‐surface ensembles of nitrogen‐vacancy (NV) centers, in stark contrast to plasma treatments that use heated sample stages.