Sample Temperature Research Articles

Effect of Heat Treatment on Some Thermodynamics Analysis, Crystal and Microstructures of Cu-Al-X (X: Nb, Hf) Shape Memory Alloy

Abstract: Heat treatment is an important technique that can improve the properties of shape memory alloys. In this study the effect of heat treatment at three different temperatures (973 K, 1073 K and 1173 K) on some thermodynamics parameters, crystal structure, and microstructure of Cu_86 Al_12 Nb_2 and Cu_86 Al_12 Hf_2 (mass %) Shape Memory Alloy has been investigated. After heat treatment, the change in the thermal properties of the samples was determined using Differential Scanning calorimetry (DSC). The effect of heat treatment on the crystal and microstructure of the alloy samples were determined at room temperature using X-ray diffraction (XRD), Scanning Electron microscopy (SEM) device. The DSC result showed that in both samples the temperature hysteresis was decreased after heat treatment. Also grain size was decreased by increasing the treatment temperature in both samples. And finally, optical images represented that Hafnium (Hf) is more dissolved in the alloy compared to Niobium (Nb).

Temperature and Ge fraction dependence of broad peaks observed in Ge-rich SiGe Raman spectra by oil-immersion Raman spectroscopy

Abstract We present the temperature and Ge fraction dependence of the broad peaks at the lower wavenumber side of the Ge-Ge vibration mode in Raman spectra from Ge-rich Si1−xGex thin films (x = 0.750, 0.852, and 0.918) investigated by oil-immersion Raman spectroscopy. The sample temperature was elevated by increasing laser power and estimated using the relation between Raman shift ω and temperature T (dω/dT) of Ge-Ge vibration mode. The broad peaks observed from all the Ge-rich SiGe thin films shifted toward the lower wavenumber side with increasing laser power. We confirmed that dω/dT of the broad peak differs from the Ge-Ge vibration mode and changes with increasing Ge fraction. In addition, we found that the correlation between Ge fraction and the peak intensity ratio of the broad peak and the Ge-Ge vibration mode is almost the same at various laser power conditions.

Single cell micro-absorption spectroscopy system with temperature control: System design and spectral analysis.

Micro-absorption spectroscopy is a useful tool for studying the biological characteristics of single cells. However, the weak spectral signal, due to low absorption caused by the tiny optical path length of the cell, makes the spectral data noisy and difficult to analyze. This paper describes a device for single-cell microspectroscopy measurement that integrates an optical fiber spectrometer and an image CCD within a microscopic system, allowing for the simultaneous acquisition of morphology information and the absorption spectrum of a single cell. The device utilizes an illumination source driven by modulated current sources instead of constant current sources and the corresponding spectral signal extraction method to reduce noise levels. It also features a transparent temperature-controlled sample chamber for regulating the sample's temperature, as the absorption of cells may change with temperature. Due to the unwanted baseline drift in the spectral signals, a method of analyzing the similarity degree between the measured spectrum and the standard spectrum is proposed to study the characteristic variation of cells. To verify the feasibility of this method, the device was used for the microscopic spectral measurement and analysis of single red blood cells. The results showed that the variation patterns of spectral parameters correspond to the cell's responses to changes in temperature and storage duration.

Dynamic response characteristics of coal/rock during water injection and freezing process under gas atmosphere and its control effect on gas outburst

The freezing method compensates for the defect of sacrificing coal integrity to reduce gas content, which is the case with traditional methods, achieving the improvement of coal body strength while reducing coal seam gas energy storage, improving the safety of coal and gas outburst accidents in deep coal seams during the process of rock cross-cut coal uncovering. This study conducted water injection and low-temperature freezing experiments on coal/rock samples under the gas atmosphere, analyzing the effects of water and temperature on sample temperature, deformation, and gas adsorption and desorption characteristics. The results indicate that water can displace adsorbed gas in coal/rock samples, and the relationship between the gas displacement and the water content of the sample satisfies an improved exponential function. The center temperature Tm of low water content coal/rock samples decreases with time and gradually tends to stabilize, while the Tm of high water content samples experiences a short-term deceleration or stagnation due to the phase transition heat release of water when it drops to around 0 °C. The cooling rate of samples with low water content and no gas is higher and that of rocks is higher than that of coal samples. Coal/rock samples with high water content experience frost heave during the freezing process, but the overall deformation is still dominated by cold shrinkage, and the amount of deformation is negatively correlated with temperature and water. The gas adsorption capacity of coal decreases linearly with the temperature. At the same time, an increase in water content and a decrease in freezing temperature will significantly reduce the gas desorption capacity of coal samples, effectively reducing the gas expansion energy of coal samples, especially the desorption gas expansion energy. In engineering implementation of this method, the ice phase network can fill the coal pores and cracks and improve the mechanical properties of the coal/rock mass, and the gas pressure in the coal seam and stress concentration near the coal rock interface can be reduced by low temperature and cold shrinkage, thereby achieving safe exposure of the coal seam and preventing accidents from occurring.

A simple and effective non-invasive method for the analysis of volatile organic compounds in exhaled air

Breath analysis is a cutting-edge technique that collects significant medical information by analyzing the substances found in exhaled breath. Fluctuations in the levels of chemicals such as acetone can serve as indicators of medical ailments or contact with hazardous substances such as occupational exposure. In order to detect acetone in exhaled air, techniques such as needle trap coupled with gas chromatography have been devised. This procedure involves the use of a nanocomposite called Mil101(Fe)@Fe3O4@SiO2.The nanocomposite is synthesized using a chemical hydrothermal method. In order to examine the properties of the Mil101(Fe)@Fe3O4@SiO2 nanocomposite, researchers utilized a range of analytical techniques including scanning electron microscopy (SEM), thermal analysis (TGA), x-ray analysis (EDX), Brunauer-Emmett-Teller (BET) method, and Fourier Transform Infrared Spectroscopy (FT-IR). The efficiency of the NTD-GC-FID method depends on several parameters, such as temperature, desorption time, fracture passage volume, sampling time, sample temperature, and sampling flow rate. These parameters have been studied using the simplex method to optimize the process. The optimal conditions yielded a limit of detection (LODs) of 0.4 µg/L and a limit of quantification (LOQs) of 1.1 µg/L. The calibration curve for the NTD-GC-FID method ranged from 0.011 to 10 mgl−1 with an acceptable error range. Moreover, the method demonstrated good repeatability and reproducibility, with calculated values of 3.9 and 4.6 %, respectively. The proposed method was successfully employed in this study to identify and measure acetone in the exhaled air of individuals with diabetes, yielding satisfactory results. The needle trap tool was used over 100 times without any decline in its efficiency for adsorbing acetone. In summary, this research presents a new analytical approach, namely the NTD-GC-FID method, to detect and measure acetone in exhaled air. Compared to the other methods for analyzing acetone, the application of Mil101(Fe)@Fe3O4@SiO2 nanocomposite demonstrated promising results in detection of diabetes.

Structural evolution of iron components and their action behavior on lignite combustion

Spontaneous combustion of lignite is closely related to the inherent minerals it contains, and the iron component has a remarkable influence on the combustion property of lignite. It is very important to study the influence of iron component on the combustion reaction property of lignite to reveal autoignition mechanism of lignite and reduce autoignition of lignite. In this research, FeCl3 and Fe2O3 were doped into demineralised lignite (SL+) by impregnation to research the effects of iron salts and iron oxides on the combustion properties of lignite. Based on the above, the effects of post-treatment method of the FeCl3-doped coal samples, iron-salt hydrolysis products and heat-treated temperatures on the combustion property of lignite were researched, and the microstructures of the coal samples were characterised and analysed using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope-energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results demonstrate that doping with FeCl3 increases the combustion performance of lignite, thereby reducing the ignition temperature of lignite by approximately 112 °C. In contrast, doping with Fe2O3 has a weaker combustion-promoting effect. XRD and XPS characterisation indicates that iron species in the coal samples doped with iron salts are highly dispersed and exhibit the FeOOH structure, whereas iron species in the coal samples doped with Fe2O3 exhibit the crystal form of α-Fe2O3. Doping of lignite with FeCl3 and its hydrolysis product β-FeOOH reduces the ignition temperature of the coal samples. Iron species in the FeCl3-doped coal samples after heat treatment at 300 °C-500 °C increase the combustion property of the coal samples, whereas iron species after heat treatment at 600 °C-900 °C have a much weaker or non-existent promoting effect on the combustion performance of the coal samples. The characterisation show a change in iron species in the coal samples with the rise in the heat treatment temperature. This change progresses from highly dispersed β-FeOOH below 300 °C to Fe3O4 above 400 °C. Fe3O4 is gradually reduced, with part of it further reduced to elementary iron at the same time as grain growth. It is believed that the gradual agglomeration of Fe3O4 and the appearance of elementary iron are the main reasons for the weakening or disappearance of the promoting effect on coal combustion.

Impact of Sample Storage Time and Temperature on the Stability of Respiratory Viruses and Enteric Viruses in Wastewater

Wastewater-based surveillance (WBS) has been widely used to track SARS-CoV-2 as well as many other viruses in communities during the COVID pandemic and post-pandemic. However, it is still not clear how temperature and storage time would influence the stability of viruses in wastewater. In this study, we assessed the stability of SARS-CoV-2, pepper mild mottle virus (PMMoV), influenza viruses A (IAV) and B (IBV), respiratory syncytial virus (RSV), and enteric viruses in raw wastewater stored at room temperature, 4 °C, and −20 °C for 3 and 6 days. SARS-CoV-2, PMMoV, IAV, and enteric viruses were found to be stable up to 6 days after storing at room temperature or 4 °C. SARS-CoV-2 and RSV were more susceptible to freeze–thaw cycles compared to PMMoV and enteric viruses, which were relatively stable for up to 6 days stored at −20 °C. Low detection of IBV in wastewater made it difficult to evaluate the impact. Based on our findings, we conclude that short-term storage or transportation of wastewater samples within 6 days at ambient temperature or 4 °C is acceptable for the majority of these viruses. Freezing samples at −20 °C for even short periods is not recommended for WBS of respiratory viruses. The data obtained from this study can provide guidance for quality assurance purposes from the operational aspects of wastewater surveillance.

Effect of austempering temperatures on mechanical properties of dual matrix structure austempered ductile iron

Abstract This study investigates the effect of the austempering temperatures on the microstructures and mechanical properties of austempered ductile iron with dual-matrix structure (DMS-ADI). An unalloyed ferritic ductile iron bar samples were intercritically austenitized at 810 °C for 60 min and austempered at different austempering temperatures (300 °C, 325 °C, 350 °C, and 375 °C) for 120 min. Microstructural and mechanical characterization were examined using optical microscopes, scanning electron microscopes (SEM), X-ray diffraction (XRD) analyses, hardness, and tensile tests. Experimental results showed that the DMS-ADI samples exhibit a dual-phase structure consisting of proeutectoid ferrite + ausferrite structures. The volume fraction of ausferrite (42.5–47.5 %) was almost stable in all austempering temperatures in DMS-ADI samples. The high-carbon retained austenite volume fraction, and its carbon content increased with increased austempering temperatures. At austempering temperatures up to 350 °C, strength and hardness increased, while energy at break and total elongation decreased. The strength and hardness decreased, while energy at break and total elongation increased at 375 °C austempering temperature. All DMS-ADI samples exhibited ductile fracture surfaces except for those austempered at 350 °C. The highest (σ UTS = 590 MPa and ε T = 18.8 %) and lowest (σ UTS = 434 MPa and ε T = 28.5 %) mechanical properties were obtained in DMS-ADI samples austempered at 350 °C and 300 °C, respectively.

Mechanism of Electron-Beam-Induced Structural Degradation in ZIF-8 and its Electron Dose Tolerance.

Zeolitic-imidazolate frameworks (ZIFs) are crystalline microporous materials with promising potential for gas adsorption and catalysis application. Further research advances include studies on integrating ZIFs into nanodevice concepts. In detail for the application, e.g., electron-beam-assisted structural modifications or patterning, there is a need to understand potential structural degradation processes caused by such electron beams. Advanced transmission electron microscopy (TEM) has demonstrated its ability to study structures at the nanoscale. Here, we systematically investigated electron-beam-induced loss in crystallinity in ZIF-8 under various experimental conditions, using as measure the attenuation of the relative intensity and the relative displacement of electron diffraction Bragg planes with increasing cumulative electron dose. The {110} Bragg planes reflect the overall stability of the ZIF-8 unit-cell structure, while the {431} Bragg planes assess the stability of its micropore structure. We considered a relative loss of Bragg plane intensity of 37% as the threshold for determining the critical electron dose, which varied for different Bragg planes, with 35.6 ± 8.4 e-Å-2 for {110} and 11.4 ± 3.0 e-Å-2 for {431}. However, the critical dose per breakage of N-Zn bonds in a ZnN4 tetrahedra per different Bragg plane was found to be ∼3 e-Å-2, which indicates continuous, simultaneous breakage of N-Zn bonds throughout the crystal, confirming radiolysis as the dominant damage mechanism. In addition, we investigated the effects of TEM experiment parameters, including acceleration voltage, electron dose rate, cryogenic sample temperature, in situ sample drying, and change in conductivity of the sample substrate (e.g., graphene). Our results unravel the degradation mechanisms in ZIF-8 and provide threshold parameters for maximizing resolution in electron-beam-assisted experiments and processes.

Thermal evolution of helium bubbles in tungsten by GISAXS and TDS

Grazing-incidence small-angle x-ray scattering (GISAXS) and thermal desorption spectroscopy (TDS) were used to study the thermal evolution of helium (He) bubbles in tungsten (W). W samples were exposed to a low ion energy (∼20 eV, sheath accelerated) He plasma at two sample temperatures: 573 K (low-temperature) and 1050 K (high-temperature). They were then annealed to temperatures of 773 K, 873 K and 998 K. GISAXS analysis showed an increase in the median bubble radius of the high-temperature samples from 6.42 Å to 12.87 Å as a result of annealing to 998 K. No changes in the bubble radii distributions were observed for the low-temperature samples and the median radius remained at ∼4 Å even after annealing. TDS showed that the desorption behaviour of He in W has a dependence on the sample temperature during plasma irradiation. The higher-temperature sample experienced a maximum desorption rate that is an order of magnitude larger than the low-temperature sample. The desorption profile of the high-temperature sample spanned a wider temperature range, 500 K - 1500 K, than the low-temperature sample, 500 K - 750 K. The formation and thermal evolution of He bubbles in W have a clear dependence on sample temperature during plasma exposure. The differences in annealing behaviour observed in this work agree with prior in-situ TEM annealing experiments and help explain macroscopic plasma-material interaction effects such as recrystallisation suppression.

An Experimental Study on Deuterium Production from Titanium Hydride Powders Subjected to Thermal Cycles

An extensive multi-year experimental study was conducted to investigate the potential production of deuterium from titanium hydride TiHx powders subjected to specific thermal cycles. Mass spectrometry was performed, focusing on the variation in signal intensities at m/z = 2, 3, 4, 18, 19, 20, and 21, corresponding to fragments primarily involving deuterium, during the degassing of titanium hydride powders as the sample temperature was raised from room temperature to approximately 1100 °C. The results reveal an anomaly in the deuterium-to-hydrogen ratios, with the analysis indicating an increase in deuterium concentration by a factor of approximately 280 compared to its natural concentration on Earth. Three independent methods confirmed the excess deuterium. Simultaneously, flow calorimetry was performed during the degassing process, which did not show any measurable excess heat produced in the configuration used. This study was motivated by our novel theoretical predictions, based on the standard electroweak theory with gauge symmetry, suggesting the generation of slow neutrons within metal hydrides when exposed to coherent excitations. Our findings align with direct measurements of neutron emission by TiHx powders under cavitation in liquid water, as recently published by Fomitchev-Zamilov.

Enhancing thermal dissipation ability and electrical performance in GaN-on-GaN HEMTs through stepped-carbon buffer design

This study investigates the thermal dissipation ability and electrical performance of GaN-on-GaN HEMTs through a stepped-C buffer design. We analyzed the relationship between impurity (C and Fe) concentrations and the thermal conductivity of the GaN material by fitting Debye–Callaway model. A stepped-C buffer design is proposed to avoid the Fe impurity and its tailing effect on thermal conduction in GaN epitaxial layers. In addition, the high concentration of C doping is designed to suppress the epitaxial interface leakage in GaN-on-GaN structures. The transducer-less transient thermoreflectance (TL-TTR) technique revealed that the stepped-C structure significantly improves thermal conductivity of epitaxial layers compared with that of Fe/C co-doped structure. Due to the optimization of heat dissipation ability, the peak temperature of the stepped-C sample decreased by ∼30 °C compared to the Fe/C co-doped sample at PDC = 10.4 W/mm. Consequently, the GaN-on-GaN HEMTs with the stepped-C buffer achieved a record output power density (Pout) of 14.8 W/mm and a power-added efficiency (PAE) of 48.2% at 3.6 GHz, underscoring the critical role of thermal management in advancing GaN-on-GaN HEMT RF performance.

The effect of ultrasound-assisted freezing, metal plate assisted freezing and conventional freezing on the quality characteristics of beef samples

In this study, the effects of household refrigerator freezing (control group), ultrasound-assisted freezing at different power levels (40 %, 70 %, and 100 %) and metal plate assisted freezing on the quality characteristics of beef samples were investigated. While the freezing time decreased for the fillet samples with ultrasound-assisted freezing (40 % and 70 %, respectively) and for all samples with metal plate assisted freezing, the weight loss and cooking loss values generally decreased compared to control samples. The total color values of the ultrasound-assisted frozen samples were higher than those of the control samples, while the metal plate assisted frozen samples were lower than those of the control samples. The TBARS values were found to be lower in both methods compared to control samples. The hardness values of control samples were generally lower than the samples subjected to both methods after or before cooking. The protein denaturation temperatures of the metal plate-assisted frozen samples were generally higher than others. As a result, ultrasound and metal plate assisted freezing processes preserved the quality characteristics of beef and had significant effects on several quality characteristics of beef. The application of ultrasound at 40 % provides a significant advantage in terms of quality characteristics. The effects of conduction heat transfer with metal plate-assisted freezing processes also provides the positive impact on the freezing of beef samples. Thus, the use of innovative technologies during the freezing of food in household refrigerators were evaluated within the study which brings new idea to integrate them in the production of household refrigerators.

Effect of temperature and capillary number on wettability and contact angle hysteresis of various materials. Modeling taking into account porosity

The effect of surface temperature and laser texturing on the wettability and contact angle hysteresis of Cu, Cu/G, AlMg3, Cu-SiC was considered. Modeling using molecular dynamics qualitatively confirms the experimental results: 1) an increase in the contact angle hysteresis on a textured surface; 2) influence of the surface wettability on contact angle hysteresis; 3) influence of the contact line velocity on contact angle hysteresis. Heating the sample of different composite materials can lead to either an increase in the contact angle or a decrease. It was shown that after laser texturing, a system of nano-micro pores was formed in the surface layer of the material, which leads to an abnormally high contact angle hysteresis on the Cu-SiC composite. A new model is proposed that explains the different qualitative behavior of the contact angle hysteresis in different studies with increasing capillary number (Ca), as well as with increasing sample temperature.

The effect of D[formula omitted] partial pressure, deposition rate, and sample temperature on D retention in W codeposited layers

Hydrogen-isotope (HI) fuel retention in the walls of magnetic fusion devices must be minimized to achieve tritium self-sufficiency and for safety considerations. Retention in codeposited layers (i.e., layers formed from eroded material while simultaneously exposed to HIs) is projected to be a dominant source. This work investigates retention in tungsten (W)–deuterium (D) codeposited films as a function of D2 partial pressure. Tungsten films were deposited onto quartz substrates via magnetron sputtering in an Ar-D2 mixed background with the D2 partial pressure, pD2, varied from 0.13 to 1.6 Pa; the substrate temperature, Ts, varied from 310 K to 623 K; and the W deposition rate, rd, varied from ∼1.0 to 4.2×1019 m−2s−1. After deposition, D release was measured using thermal desorption spectroscopy (TDS). For films deposited at Ts∼ 310 K, D/W increased from 0.13 to 0.44 Pa, was constant to 0.89 Pa, and decreased at 1.6 Pa. However, the TDS spectra for films at all pD2 showed a similar distribution of D in traps, with a single release peak at 400–700 K. For films with pD2 = 0.89 Pa, D/W decreased exponentially with increasing Ts, in agreement with the Ts scaling in the literature, while the release peak in the TDS spectra shifted to higher desorption temperatures. For films deposited near room temperature, the measured D/W ratio decreased by 3× as rd increased, in agreement with the rd−0.8 scaling in the literature, while the tail of the D release increased from 700 to 1200 K for the higher rd. Hence, retention mitigation strategies for ITER (e.g., baking of the vacuum vessel at 493 K) may not be sufficient, especially for films formed with high rd.

Enhancing CO2 capture performance through activation of olive pomace biochar: A comparative study of physical and chemical methods

This work contributes understanding technical feasibility use of an agro-industrial waste as raw material for CO2 capture. Physical and chemical activation treatments to enhance adsorption properties of exhausts olive pomace biochar were investigated. Innovatively, the effects of different kinds of activating agents (steam, CO2, H3PO4 and KOH) on activated biocarbon's properties were deeply examined, also through an original high-pressure thermobalance, that is enabled higher initial sample weights, temperatures, and pressures compared to those employed in conventional methods.The activation conditions significantly affect the biochar morphology and CO2 adsorption capacity. Chemical activation, particularly with KOH, produced highly microporous structures, greatly enhancing CO2 adsorption. Specifically, KOH activation achieved adsorption capacities of up to 3.04 mmol/g at 30 °C and 10 bar. Textural analysis showed that KOH activation primarily increased microporosity, while other methods produced both micropores and mesopores. Interestingly, acid and physical activations were less effective, as they reduced CO2 adsorption due to changes in the internal structure. Thus, olive pomace proves to be a promising precursor for developing efficient biochar adsorbents. The use of KOH as an activating agent particularly stands out, achieving notable CO2 adsorption capacities.

Abstract A069: Effect of different voided urine sample storage time and temperature, and preservatives, on analysis with the multiplex bead-based Oncuria® bladder cancer immunoassay

Abstract Urinalysis accuracy requires reliable sample stability that is dependent on the chosen collection and storage conditions. If urine sample storage at room temperature (20°C) does not affect sample quality, this may reduce laboratory handling time and expense. This study evaluated whether different voided urine sample collection and storage parameters affected subsequent biomarker analysis by the multiplex Oncuria® bladder cancer immunoassay. The Oncuria® immunoassay simultaneously quantifies 10 protein analytes in urine to generate a bladder cancer diagnostic signature. Samples were stored at varied temperatures (20°C, 4°C, -80°C) for up to 1 month. The effects of adding two commercial urine sample stabilizers and antibiotics (trimethoprim) were also assessed. Subsequently, multiple potential biospecimen stabilizers were added to urine samples and evaluated with Oncuria® in hopes of allowing the urine sample to remain at room temperature for extended periods of time. First, it was demonstrated that voided urine samples stored at room temperate without such stabilizers had different levels of the 10 analytes associated with the Oncuria® test compared to voided urine samples stored at 4°C. Next, we evaluated the effects of commercially available biospecimen stabilizers. Despite the addition of these stabilizers, the levels of the 10 analytes were altered when the samples were stored at room temperature for prolonged periods of time. Therefore, we could not identify a suitable biospecimen stabilizer that would not require sample refrigeration. In conclusion, to minimize sample degradation/alteration after collection, voided urine samples should be refrigerated until analyzed with Oncuria® as the refrigeration is advantageous for the storage and the transport of these urine samples. Citation Format: Sunao Tanaka, Kaoru Murakami, Toru Sakatani, Riko Lee, Wayne Hogrefe, Fernando Siguencia, Steven M Smith, Charles J Rosser, Hideki Furuya. Effect of different voided urine sample storage time and temperature, and preservatives, on analysis with the multiplex bead-based Oncuria® bladder cancer immunoassay [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A069.

Hysteresis of unfrozen water content of tailing mud with freeze-thaw and its correlation with electrical conductivity

Identifying the correlation between the hysteresis of unfrozen water content and the electrical conductivity (EC) of tailing mud with freeze-thaw is essential for determining the range of frost hazards in tailings ponds by field conductivity measurement and enabling targeted treatment in coastal and seasonally frozen areas. In this study, dynamics of unfrozen water content and temperature of saturated tailing mud samples with 0.0–5.0 % NaCl were evaluated with 5TM sensor while the EC with the frequency domain reflectometry (FDR) sensor. Results show that unfrozen water hysteresis of tailing mud with freeze-thaw occurred below phase-change temperatures, with the cooling section above the warming. The area of hysteresis curve rose upon higher salinity or fewer freeze-thaw cycles. Phase-change temperatures of tailing mud, including freezing and thawing points, depressed with higher salinity but were less affected by freeze-thaw cycles, with the former coinciding with the liquidus line of NaCl solution while the latter located above. The EC curve also exhibits hysteresis with freeze-thaw and the initial salinity determines both the maximum EC value and the slope logEC/T below phase-change temperatures. It was concluded that the unfrozen water content, converted salt concentration and EC of frozen tailing mud show synchronous changes. A modified Michalowski model, with phase-change temperatures and residual unfrozen water content respectively simplified as proportional and exponential functions of initial salinity, was established to characterize the unfrozen water hysteresis of tailing mud with freeze-thaw cycles. A simple EC model with hysteresis was then developed by approximating the EC of frozen tailing mud as a power function of the converted salt concentration, which was applied to the tailing mud with 0.5–5.0 % NaCl in the range of −20 °C up to phase-change temperatures.

Practical considerations for plunge freezing samples over 40 °C for Cryo-EM

Cryo-EM is now an established tool for examining samples in their native, hydrated states—a leap made possible by vitrification. Utilising this sample preparation method to directly visualise temperature-responsive samples allows for deeper insights into their structural behaviours under functional conditions. This requires samples to be plunge-frozen at elevated temperatures and presents additional challenges, including condensation within the blotting chamber and difficulties in maintaining a stable sample temperatures. Here, we address these challenges and suggest practical strategies to minimise condensation and reduce temperature fluctuations during the plunge-freezing of samples at elevated temperatures (>40 °C). By preheating equipment and reducing chamber humidity and blotting times, we can improve sample preservation and grid reproducibility. These considerations are then demonstrated on poly(N-isopropylacrylamide) microgels, which exhibit a volume phase transition due to temperature changes.

Effect of stabilizers on the detection of swine influenza A virus (swIAV) in spiked oral fluids over time

BackgroundAggregated samples such as oral fluids (OFs) display an animal friendly and time and cost-efficient sample type for swine Influenza A virus (swIAV) monitoring. However, further molecular and biological characterization of swIAV is of particular significance. The reportedly inferior suitability of aggregated samples for subtyping of swIAV presents a major drawback compared to nasal swabs, still considered the most appropriate sample type for this purpose (Garrido-Mantilla et al. BMC Vet Res 15(1):61, 2019). In addition, the viral load in the original sample, storage conditions and characteristics of different swIAV strains might further compromise the eligibility of aggregated samples for molecular detection and subtyping. Therefore, the present study aimed to evaluate the suitability of stabilizing media to minimize the degradation of viral RNA and thus increase the detection and subtyping rate of swIAV by RT-qPCR in spiked OFs under different conditions (virus strain, storage temperature and viral load in the original sample) over a time span of 14 days.ResultsThe use of stabilizing media in spiked OFs resulted in a significant higher probability to detect swIAV RNA compared to OFs without stabilizers (OR = 46.1, p < 0.001). In addition, swIAV degradation over time was significantly reduced in samples suspended with stabilizer (OR = 5.80, p < 0.001), in samples stored at 4 °C (OR = 2.53, p < 0.001) and in samples spiked with the avian derived H1N2 subtype (OR = 2.26, p < 0.01). No significant differences in swIAV RNA detection and degradation of swIAV RNA in spiked OFs over time were observed between the three different stabilizing media.ConclusionAddition of stabilizers and storage of samples under cooled conditions significantly improved detection and subtyping of swIAV in spiked OFs.