Low Temperature Environment Research Articles

Preparation and Hg0 Removal Performance of MIL-101(Cr)-Derived Carbon Matrix Composites

The temperature at which pollutants are treated varies across different industrial processes. To address the high cost of raw materials for MOFs and the low efficiency of Hg0 removal in low-temperature environments, a series of MIL-101(Cr)-derived carbon matrix composite materials were prepared by combining MIL-101(Cr) with biomass and multiple metals. These materials were synthesized through a sol-gel method followed by carbonization. This study investigates the effects of composite ratios and adsorption temperatures on Hg0 removal, utilizing XRD, BET, and other characterization techniques to elucidate the mercury-removal mechanism of the PDC-MIL composite materials. The results indicate that MIL101(Cr) significantly influences the formation of the gel skeleton. When the composite ratio of MIL-101(Cr) to biomass is 1:1, the material exhibits an optimal pore structure, leading to high Hg0 removal efficiency over a wide temperature range. The removal of Hg0 by these composite materials involves both physical adsorption and chemisorption. Low temperatures favor physical adsorption, while high temperatures promote chemisorption. The sol-gel composite method facilitates cross-linking polymerization between MOFs and SiO2, enabling better pore structure connectivity with biomass and MOFs, thereby optimizing the poor pore structure observed after pyrolysis. Consequently, the improved pore structure enhances physical adsorption at low temperatures, mitigates desorption at high temperatures, and increases the contact probability of Hg0 with active sites within the pores, significantly improving the mercury-removal ability of the material across a broad temperature range.

Geochemistry of Pyrite from the Jiaojia Gold Deposit, Jiaodong Peninsula, North China Craton: Implications for Source of Ore-Forming Fluids and Gold Precipitation

The Jiaojia gold deposit in the Jiaodong Peninsula, located in the northwestern part of the Jiaodong gold province in eastern China, has a gold reserve of over 300 t. Gold mineralization in Jiaojia deposit occurred in three stages: (1) The Pyrite–Quartz–Sericite Stage (Stage I) developed primary minerals that included quartz, sericite, and a small amount of anhedral pyrite, appearing as disseminations within milky quartz and foliated sericite. (2) The Quartz–Pyrite Stage (Stage II) developed quartz that appears smoky gray and pyrite that appears with a euhedral cubic morphology, with crystal faces oriented in a longitudinal pattern. Native gold occurs as fracture filling in pyrite. (3) The Quartz–Polymetallic Sulfides Stage (Stage III) developed polymetallic sulfides, including pyrite, chalcopyrite, galena, sphalerite, and magnetite. Native gold filled the pyrite fractures and was enclosed within the pyrite. (4) The Quartz–Carbonate Stage (Stage IV) developed the main minerals of quartz and carbonate, with scattered occurrences of pyrite. In situ geochemical analysis of pyrite, the main gold-carrying mineral from mineralization Stages I to III in the Jiaojia gold deposit, was conducted, including major element, trace element, and sulfur isotope analyses. The δ34S values of Jiaojia pyrite range from 4.5 to 8.0‰. Pyrite in Stage I (Py I) has δ34S values ranging from 4.5 to 7.4‰, with an average of 6.4‰. Pyrite in the Stage II (Py II) has δ34S values ranging from 5.9 to 8.0‰, with an average of 6.8‰. Pyrite in Stage III (Py III) has δ34S values ranging from 6.4 to 7.9‰, with an average of 7.4‰. Combined with the C-D-O-He isotopes, the ore-forming fluids of the Jiaojia gold deposit likely originated from subducted oceanic plate-related metasomatized mantle. The Co/Ni ratios of Jiaojia pyrite range from 0.50 to 1.47 in Stage I, 0.27 to 1.69 in Stage II, and 0.58 to 295 in Stage III. The Cu/Au ratios in the Jiaojia pyrite in all mineralization stages were >1. These geochemical features imply that the ore-forming fluids of the Jiaojia gold deposit were in a medium- to low-temperature reducing environment, with temperatures gradually decreasing from ore Stages I to III. The increase in Co and As in the pyrite of Stage III implies that gold precipitation resulted from fluid immiscibility caused by a decrease in pressure and temperature and an increase in the oxygen fugacity of the ore-forming fluid.

Multi-crosslinked Ta4C3TX MXene composites with “interlocked structure” for efficient gamma-ray shielding, behavioural detection and thermal management in nuclear environments

Multi-crosslinked Ta4C3TX MXene composites with “interlocked structure” for efficient gamma-ray shielding, behavioural detection and thermal management in nuclear environments

Low-Temperature IR Camouflage Materials by Dual Resonances for Enhanced Thermal Management without Energy Consumption.

Due to the critical importance of carbon neutrality for the survival of humanity, passive thermal management, which manages thermal energy without additional energy consumption, has become increasingly attractive. Camouflage materials offer a promising solution for passive thermal management, as they can dissipate heat through thermal radiation, reducing the need for energy-intensive cooling systems. However, developing effective infrared (IR) camouflage solutions for low-temperature environments and small-sized applications remains a challenge because the low temperatures limit the ability to dissipate radiative energy from the surface. Moreover, conventional IR camouflage materials, typically optimized for single band (5-8 μm), face significant limitations in energy dissipation at lower temperatures, which requires a novel way to increase the energy dissipation without the additional energy consumption. Herein, we present a novel low-temperature IR camouflage material (LICM) designed to address these challenges by employing dual-band resonances in the nondetection bands, 5-8 and 14-20 μm based on the atmospheric transmittance. LICM demonstrated an increase in energy dissipation of 273 and 167% at 250 and 350 K, respectively than the conventional IR camouflage materials. Despite the enhanced dissipation, the LICM maintained an IR signature reduction of around 10% of blackbody radiation, ensuring effective IR camouflage. Thermographic measurements using an LWIR camera (7.5-14 μm) further demonstrated the LICM's superior IR camouflage performance. This dual-band resonance design not only extends IR camouflage to low-temperature environments but also facilitates significant energy savings, making it a key ingredient for broad-scale deployment in areas such as energy conversion, aerospace, and sustainable thermal management technologies.

Direct Assembly of Grooved Micro/Nanofibrous Aerogel for High-Performance Thermal Insulation via Electrospinning.

Maintaining human body temperature in both high and low-temperature environments is fundamental to human survival, necessitating high-performance thermal insulation materials to prevent heat exchange with the external environment. Currently, most fibrous thermal insulation materials are characterized by large weight, suboptimal thermal insulation, and inferior mechanical and waterproof performance, thereby limiting their effectiveness in providing thermal protection for the human body. In this study, lightweight, waterproof, mechanically robust, and thermal insulating polyamide-imide (PAI) grooved micro/nanofibrous aerogels were efficiently and directly assembled by electrospinning. The grooved micro/nanofibrous aerogels were directly prepared by controlling the relative humidity and solvent evaporation rate, as well as regulating the charge jet density and phase separation behavior. The prepared aerogel exhibited ultralight performance with a density of 4.4 mg cm-3, hydrophobic liquid-repelling performance with a contact angle of 137.4°, and ultralow thermal conductivity (0.02586 W m-1 k-1), making it an ideal material for maintaining thermal comfort in complex environments. This work provides valuable insights into the design and development of high-performance fiber insulation materials.

Modification Mechanism and Performance of High-Content Polyurethane-Modified Asphalt

To explore the influence of the polyurethane blending ratio on the micro-characteristics of polyurethane-modified asphalt, three samples of the modified asphalt with different blending ratios (40%, 50%, and 60%) were prepared. Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were employed to elucidate the modification mechanism of polyurethane-modified asphalt. To investigate how the preparation method affects the performance of polyurethane-modified asphalt mixtures, two different preparation methods, namely internal blending and external blending, were adopted. The road performance of the polyurethane-modified asphalt mixtures was evaluated through the utilization of rutting tests, low-temperature trabecular bending tests, and freeze–thaw splitting tests. The FTIR test results indicate that during the modification of polyurethane, there is a change in both the intensity and position of the absorption peak, which affects the local arrangement of the molecular structure. Upon reaching a polyurethane blending ratio of 50%, a cross-linked network structure that is similar to polyurethane is formed. The results of the AFM test demonstrate that an increase in polyurethane content results in a corresponding increase in surface roughness. At a polyurethane content of 50%, the curing reaction is most effective, which is beneficial for enhancing the bonding performance between the asphalt and the aggregate, thereby enhancing the overall water stability of the mixture. The results of the scanning electron microscopy (SEM) tests indicate that the microstructure is more stable when the polyurethane content is 50%. The results of the performance test of the polyurethane-modified asphalt mixture indicate that the dynamic stability of the polyurethane-modified asphalt mixture is approximately four times that of the SBS-modified asphalt mixture. The flexural tensile strength and maximum flexural strain of the polyurethane-modified asphalt mixture are, respectively, 1.5 and 3.2 times those of the SBS-modified asphalt mixture, indicating that its anti-deformation ability is stronger in a low-temperature environment, and it is found that the low-temperature performance of the mixture prepared with the internal blending method is better than that with the external blending method. The splitting strength of the polyurethane asphalt mixture before and after freezing and thawing is greater than that of an SBS asphalt mixture: before freezing and thawing, by about 3.8 times; after freezing and thawing, by about 3 times. Although the freezing and thawing of the polyurethane mixture has damage, it still meets the requirements of the use of pavement materials. It can be observed that the incorporation of polyurethane alters the internal structure of the asphalt, which markedly enhances the properties of the asphalt mixture and offers a novel perspective on the development of modified asphalt materials.

Application of Surface-Cracking Process to Improve Impact Toughness of High-Strength BCC Steel at Low Temperatures

At very low temperatures, typically ductile materials, especially body-centered cubic (BCC) steels, often exhibit an abrupt transition to brittle fracture, significantly limiting their applicability in cryogenic and low-temperature environments. This challenge arises from the inherent properties of BCC steels, where ductility is drastically reduced, leading to unexpected failures under mechanical stress. Despite the advantages of high-strength BCC steels, including cost-effectiveness and mechanical robustness, their susceptibility to brittle fracture restricts their use in demanding low-temperature applications. To address this limitation, we developed an innovative surface-cracking process to enhance the impact toughness of BCC steels. The introduction of controlled surface cracks redistributes stress and energy dissipation mechanisms, improving the toughness of high-strength BCC steels at cryogenic temperatures. Microscopic observations and finite element analyses reveal that these surface cracks not only dissipate crack formation energy but also alter stress triaxiality at crack tips. This causes the stress state to transition toward a plane stress condition, effectively mitigating stress concentrations typically observed in plane strain states. By reducing localized stress severity and promoting uniform energy distribution, the surface cracks encourage failure mechanisms favoring ductile behavior over brittle fracture.

Binding the Power of Cycloaddition and Cross-Coupling in a Single Mechanism: An Unexpected Bending Journey to Radical Chemistry of Butadiynyl with Conjugated Dienes.

What if an experiment could combine the power of cycloaddition and cross-coupling with the in situ formation of an aromatic molecule in a single collision? Crossed molecular beam experiments augmented with electronic structure and statistical calculations provided compelling evidence on a novel radical route involving 1,3-butadiynyl (HCCCC; X2∑+) radicals synthesizing (substituted) arylacetylenes in the gas phase upon reactions with 1,3-butadiene (CH2CHCHCH2; X1Ag) and 2-methyl-1,3-butadiene (isoprene; CH2C(CH3)CHCH2; X1A'). This elegant mechanism de facto merges two previously disconnected concepts of cross-coupling and cycloaddition-aromatization in a single collision event via the formation of two new C(sp2)-C(sp2) bonds and bending the 180° moiety of the linear 1,3-butadiynyl radical out of the ordinary by 60° to 120°. In addition to its importance to fundamental organic chemistry, this unconventional mechanism links two previously separated routes of gas-phase molecular mass growth processes of polyacetylenes and polycyclic aromatic hydrocarbons (PAHs), respectively, in low-temperature environments such as in cold molecular clouds like the Taurus Molecular Cloud (TMC-1) and in hydrocarbon-rich atmospheres of planets and their moons such as Titan, which revises the established understanding of low-temperature molecular mass growth processes in the Universe.

Analysis of the Characteristics of Hybrid Vehicles and Low-Viscosity Lubricating Oil Based on Real Road Tests in Four Extreme Environments

<div>As countries around the world attach more importance to carbon emissions and more stringent requirements are put forward for vehicle emissions, hybrid vehicles, which can significantly reduce emissions compared with traditional fuel vehicles, as well as low-viscosity lubricating oil, have become significant trends in the industry.</div> <div>In this article, a total of nine vehicles of 48 V mild-hybrid models and full-hybrid models are tested. Using three kinds of low-viscosity lubricating oil and driving a total of 120,000 km in environments with low temperature, high humidity, high temperature, or high altitude, the engines are then disassembled and scored. The effects of the four extreme environments on the engine starts–stops, ignition advance angle, engine power, state of charge (SOC), acceleration performance, and oil consumption characteristics of hybrid vehicles are studied; the oxidation characteristics and iron content change characteristics of low-viscosity lubricating oil are analyzed; and how lubricating oil protects the engine in durability tests are verified.</div> <div>According to the test results, in the low-temperature environment, for full-hybrid models, the number of engine starts–stops and the running time are significantly increased, while the SOC is generally high. In the high-temperature environment, for full-hybrid models, the ignition advance angle of the engine is reduced, which inhibits the risk of pre-ignition; the characteristics of the SOC are similar to those in the high-humidity and standard-temperature WLTC working conditions; the oxidation rate of lubricating oil has almost no effect on full-hybrid models; for mild-hybrid models, oil is prone to oxidation and decay. In the high-humidity environment, the oil consumption rate deteriorates with the increase in relative humidity under the same load and engine speed, and the accumulation rate of iron content in oil increases compared with that in the high-temperature and high-altitude environments. In the high-altitude environment, with the increase in altitude, the engine power of full-hybrid models decreases at the same engine speed, resulting in a decrease in the engine’s charging efficiency to the battery, so that the battery level could not be relatively stable. The acceleration performance of both hybrid models decreases significantly with an increase in altitude. After the engines are disassembled, it is found out that with the protection of low-viscosity lubricating oil, the wear of engine parts is very small, and the deposit control is good.</div>

All-solid-state batteries designed for operation under extreme cold conditions

A pressing need for enhancing lithium-ion battery (LIB) performance exists, particularly in ensuring reliable operation under extreme cold conditions. All-solid-state batteries (ASSBs) offer a promising solution to the challenges posed by conventional LIBs with liquid electrolytes in low-temperature environments. In this study, leveraging the benefits of amorphous solid-state electrolytes (SSEs) xLi3N-TaCl5 (1 ≤ 3x ≤ 2), we develop ASSBs capable of functioning effectively under extreme cold conditions. The designed ASSBs, employing LiCoO2 positive electrode with a mass loading of 4.46 mg cm‒2 and a Li-In negative electrode, demonstrate initial discharge capacities of 183.19, 164.8 and 143.78 mAh g‒1 under 18 mA g‒1 at ‒10, ‒30, and ‒40 °C, respectively, and exhibit a final discharge capacity of 137.6 mAh g‒1 at 18 mA g‒1 and ‒30 °C in the 100th cycle. Moreover, the ASSBs demonstrate an initial discharge capacity of 51.94 mAh g‒1 at 18 mA g‒1 and ‒60 °C with cycling over 200 h.

Effect of different cold acclimation methods on the exercise capacity of mice in low-temperature environments.

This study aimed to evaluate the effects of different cold acclimation strategies on exercise performance in male mice exposed to low-temperature environments. Male mice were subjected to five distinct acclimation regimens over 8 weeks: immersion at 10°C (10 °CI) or 20°C (20 °CI), swimming at 10°C (10 °CS), 20°C (20 °CS), or 34°C (34 °CS). During the first 2 weeks, the acclimation time progressively decreased from 30min to 3min per day, and the water temperatures were lowered from 34°C to the target levels, followed by 6 weeks of consistent exposure. Body weight, food intake, and rectal temperature were monitored throughout the study. Post-acclimation assessments included low-temperature exhaustion exercise ability testing; 16S rDNA sequencing of gut microbiota; and quantification of gene expression related to brown adipose thermogenesis, skeletal muscle synthesis, and degradation. (1) After 8 weeks of acclimation, neither serum adrenaline nor angiotensin II levels significantly increased in mice exposed to 10°C or 20°C water. (2) Cold acclimation extended the endurance time under low-temperature conditions, notably in the 20 °CI, 10 °CS, and 20°CS groups. (3) Compared with the control (C) group, the 20 °CI and 10°CS groups showed significantly increased UCP1, IGF-1, AKT, and mTOR gene expression levels (P<0.05). The expression levels of MAFbx and MuRF1 genes in the 10°CS and 20°CS groups significantly decreased compared with those in the C group (P<0.05). (4) Compared with the C group, the 20 °CI, 10 °CS, and 20°CS groups demonstrated significant changes in intestinal microbiota diversity. Specifically, the abundance of Akkermansia strains significantly increased in the 20 °CI and 10°CS groups. The abundance of Ruminococcus and Prevotellaceae_UCG-001 significantly increased in the 20°CS group. Exercise in cold environments can activate genes related to heat production and skeletal muscle synthesis and increase the abundance of beneficial bacteria producing short-chain fatty acids, thereby modulating host metabolism, accelerating the formation of cold acclimation, and enhancing exercise capacity in low-temperature environments.

Cold and longevity: Can cold exposure counteract aging?

Aging is a multifaceted biological process characterized by a progressive decline in physiological functions and heightened vulnerability to diseases, shaped by genetic, environmental, and lifestyle factors. Among these, cold exposure has garnered interest for its potential anti-aging benefits. This review examines the impact of cold exposure on aging, focusing on key physiological processes such as inflammation, oxidative stress, metabolic regulation, and cardiovascular health. Cold exposure has been shown to reduce chronic inflammation, enhance antioxidant defenses, and improve metabolic health by activating brown adipose tissue. Furthermore, findings from hibernating mammals and model organisms suggest a connection between lower environmental temperatures and increased longevity. However, the potential long-term health risks of extended cold exposure, particularly in older adults, remain a significant concern. Epidemiological studies reveal increased rates of mortality and morbidity in populations living in cold climates, emphasizing the complexity of the relationship between cold exposure and aging. This review underscores the need for further research to elucidate the long-term effects of cold exposure on aging and to establish guidelines for leveraging its benefits while mitigating cold-induced risks.

Efficient degradation of corn straw at low temperature using anovelco-culturedconsortium LHWA.

Straw degradation was slow under low temperature environments. A cold-tolerant consortium LHWA was constructed by Bacillus cereus, Acinetobacter lwoffii, Penicillium griseofulvum, and Talaromyces funiculosus. The consortium and culture conditions were optimized. Under 4°C cultivation, liquid fermentation showed a 55.52% straw weight loss rate after 30 days with inoculum (8.4%, w/v), peptone (0.4%, w/v) and Fe2+ concentration (0.06%, w/v); solid fermentation showed 58.36% straw weight loss rate after 60 days. According to transcriptomic analysis, the mechanism of cold resistance in B.cereus is to improve the fluidity of the cell membrane, including changing the composition of fatty acids, increasing the expression of cold stress response proteins and cold shock proteins. The constructed consortium LHWA significantly improved the straw degradation efficiency under cold environments.

Experimental investigation on mechanical properties and strength criteria of frozen soft rock.

Excavation of underground engineering structures involving deeply buried water-rich soft rocks is generally carried out using the artificial freezing method. A series of undrained uniaxial and triaxial shear and creep tests were conducted on soft rocks under different confining pressures (0, 0.2, 0.5, and 1.0 MPa) at different freezing temperatures (room temperature, -5°C, -10°C, and -15°C). Test results indicate that the frozen soft rocks show strain softening characteristics. The stress-strain curve changes from a straight line to a curve as deviatoric stress constantly increases, while it decreases abruptly after the deviatoric stress reaches the peak and is slightly affected by the freezing temperature. At the same temperature, shear strength increases at a rate of 5.6 MPa/°C with increasing confining pressure; as freezing temperature decreases, the shear strength increases at 0.34 MPa/°C, and cohesion increases at 0.6 MPa/°C. Under the same confining pressure, the failure strain of soft rock decreases with the decrease of temperature. The Mohr-Coulomb (M-C) criterion can accurately describe the failure process of frozen soft rocks in the pre-peak stage, with a correlation coefficient greater than 0.98. Within the test stress range, soft rocks display attenuated stable creep deformation. Acoustic emission (AE) tests were conducted to further verify that the soft rocks show shear failure under load, with a shear plane showing an angle of 45° with the horizontal. The research findings provide technical support and theoretical reference for studying rock mechanical properties as well as for designing and carrying out underground freezing of rocks in a low-temperature environment.

Effects of phenolic acids on tetramethylpyrazine formation via room temperature spontaneous ammoniation of acetoin.

In this study, we aim to investigate the effects of phenolic acids on tetramethylpyrazine (TTMP) formation in low-temperature environments and discuss its possible mechanism. The results demonstrate that TTMP formation kinetics via acetoin (ACT) ammonification was determined to be pseudo-zero-order reaction, which transitions to a pseudo-first-order kinetic model upon high gallic acid concentrations. The TTMP formation in samples spiked with phenolic acids was significantly higher than the control group. The response surface results that the production of TTMP increases with the extension of time align with the TTMP content trend in vinegar aging. At pH7.0, TTMP formation was 56 and 70 times higher than at pH3.0 and pH11.0, respectively. The findings indicate that phenolic acids can alter reactive imine intermediates associated with the formation of pyrazinyl radicals. This study provides valuable insights into enhancing the characteristic pyrazine flavor and improving quality control in fermented foods.

Anti-freezing conductive hydrogels with exceptional mechanical properties and stable sensing performance at -30 °C.

Conductive hydrogels with stable sensing performance are highly required in soft electronic devices. However, these hydrogels tend to solidify and experience structural damage at sub-zero temperatures, leading to material breakdown and device malfunction. The main challenge lies in effectively designing the micro/nano-structure to enhance mechanical properties and stable strain sensing while preventing freezing in hydrogels. Here, we present a rapid strategy for developing a MXene bridging double-network structure-based strain sensor using polyacrylamide and agar hydrogels that can maintain stable functionality even at an extremely low temperature of -30 °C. By incorporating MXenes as a catalyst to expedite free radical polymerization, we achieve outstanding mechanical and strain sensing properties at room temperature (a high response range of 1000%, a response signal linearity of 0.998, and a gauge factor (GF) value of 1.41). This sensing performance surpasses those reported for many other hydrogels. Importantly, we also observe that the stable micro-nanostructure in the hydrogel at an extreme temperature of approximately -30 °C results in exceptional strain-detection performance (a stable response range of up to 250%) with a linearity of 0.995 and a GF value of 1.25 due to its remarkably low freezing point (<-80 °C). These findings highlight the application of our hydrogel-based tactile sensor in low-temperature environments.

Research on the Improvement and Application of State Estimation Algorithm for Lithium Iron Phosphate Batteries in Low-Temperature Environments

Research on the Improvement and Application of State Estimation Algorithm for Lithium Iron Phosphate Batteries in Low-Temperature Environments

Environmentally tolerant multifunctional eutectogel for highly sensitive wearable sensors.

Flexible hydrogel sensors have found extensive applications. However, the insufficient sensing sensitivity and the propensity to freeze at low temperatures restrict their use, particularly in frigid conditions. Herein, a multifunctional eutectogel with high transparency, anti-freezing, anti-swelling, adhesive, and self-healing properties is prepared by a one-step photopolymerization of acrylic acid and lauryl methacrylate in a binary solvent comprising water and deep eutectic solvent (DES). The results from the molecular dynamics simulations and density functional theory indicate that the hydrogen bonds between DES and water mixtures possess better stability than those between water molecules. On the other hand, DES breaks down hydrogen bonds in water, providing eutectogels with excellent anti-freezing even at -60 °C. Cetyltrimethylammonium bromide is incorporated to establish stable hydrophobic interactions and electrostatic attractions with polymer chains in the eutectogel network, resulting in superior mechanical (elongation at break of 2890%) and anti-swelling (only 2% swelling in water over 7 days) properties. The eutectogel-based strain sensors exhibit remarkable sensitivity, achieving a gauge factor of up to 15.4. The multifunctional eutectogel sensors can monitor motion and transmit encrypted information at low temperatures, demonstrating considerable potential for applications in flexible electronics within low-temperature environments.

Gradient design for Si-based microspheres as ultra-stable Li-storage anode

Gradient design for Si-based microspheres as ultra-stable Li-storage anode

A Greener Solution to Direct Low-Temperature Incorporation of Selenium in Chalcogenide Solar Absorber

A Greener Solution to Direct Low-Temperature Incorporation of Selenium in Chalcogenide Solar Absorber