Search Results (235)

Centorus rufipes (Gebler, 1833) is the only tenebrionid beetle commonly found in late Pleistocene deposits of southern western Siberia. It is assumed that the reasons for its success during the Last Glacial Maximum could have been its cold resistance and/or the relatively mild conditions of its habitat, the shores of salt lakes. The cold resistance parameters of C. rufipes and their overwintering conditions were studied near Kusgan Lake (Novosibirsk Oblast, Russia). Adults and larvae of this species used a supercooling mechanism to protect themselves from sub-zero temperatures and did not tolerate freezing, just like other steppe species of Tenebrionidae. The supercooling point (SCP) for most of the individuals was around −31 °C. Measurements of low lethal temperatures (LLT) showed that 50% of individuals died after 2 days of exposure to −27 °C. The measured SCP and LLT were at least 5 °C lower than darkling beetle species from the Chuya Depression of the Altai, which is known for its extreme winter temperatures. Thus, the hypothesis of increased cold resistance of C. rufipes was confirmed. No warming effect of its salt lakeside habitats was detected. Full article

Cement-based construction in cold regions faces severe challenges due to the dramatic retardation of hydration and strength development under sub-zero temperatures. Joule curing as a novel curing method showed certain advantages in solving this problem, while the curing efficiency was low for Joule curing under severely cold temperatures. This study systematically investigates the performance of graphene nanoplatelet (GNP)-modified electrically conductive cementitious composites under sub-zero temperature curing conditions. Joule curing method was employed to ensure a high-quality curing at ambient temperatures of −20 °C, −40 °C, and −60 °C. The results demonstrate that GNP incorporation significantly enhances electro-thermal performance. For the electrical conductivity of the specimens, the specimens containing 0.5 wt% GNP showed a much stable electric resistance development under severely cold environment, illustrating the value of 1169 Ω after 1 day Joule curing at the environmental temperature of −60 °C, which was 36% lower than the Ref. group. As for the curing temperature, the specimen with 0.5 wt% GNP effectively maintained the internal temperature within 50–60 °C during the 24 h curing period, even under extreme conditions. Mechanical tests reveal that the GNP-modified specimens exhibit remarkable strength retention, with the 0.5% GNP composite maintaining 86.3% of its compressive strength and 95.9% of its flexural strength at −60 °C compared to standard curing values. Microstructural characterization through XRD and TG analyses confirms that while the crystalline phase composition remains unchanged across different curing regimes, the hydration degree directly correlates with the mechanical performance, explaining the observed strength variations. MIP analysis further proved the advantage of Joule curing on refining the microstructure for the specimens. The findings establish that GNP modification, combined with Joule curing, presents an effective strategy for winter concrete construction, ensuring adequate strength development through enhanced electrical conductivity and controlled internal curing temperature, without altering the fundamental hydration chemistry. Full article

Kidney transplantation remains the ultimate treatment option for patients with end-stage renal disease. However, the global shortage in donor kidneys, exacerbated by challenges such as ischemia–reperfusion injury (IRI), reduces renal graft viability and negatively impacts post-transplant outcomes. Static cold storage, the gold standard of organ preservation, reduces metabolic demand but increases the risk of cold-induced mitochondrial dysfunction and IRI, especially in marginal kidneys. The introduction of machine perfusion techniques allows renal grafts and other solid organ grafts to be preserved at a wider range of temperatures. Organ preservation temperatures play an important role in determining post-transplant outcomes in the transplantation of the kidney and other transplantable solid organs. Therefore, determining the optimal preservation temperature may help increase organ utilization by avoiding unnecessary graft discards and increasing the safe use of marginal organs. This review discusses the impact of various preservation temperatures and methods of preservation on post-transplant outcomes in renal grafts and other organ grafts. Drawing from preclinical, clinical, and meta-analytic studies, we compare hypothermic (0–4 °C), moderate hypothermic (10 °C), subnormothermic (20–32 °C), normothermic (35–37 °C), and subzero preservation strategies, and cellular and molecular changes that occur in renal grafts and other solid organ grafts during preservation at these temperatures. Overall, temperature-controlled machine perfusion outperforms static preservation of renal grafts and other solid organ grafts from marginal and deceased donors, potentially expanding donor pools and improving long-term graft survival, and suggests the need for future research to determine optimal preservation temperature for renal grafts and other solid organ grafts to improve viability and post-transplant outcomes. Full article

The specific heat capacity of skinned muscle in an adhering rigor solution was studied with differential scanning calorimetry (DSC) heating runs to search for a heat sink in the sarcomere of the muscle. To elucidate the contribution of major myoproteins to heat capacity, myosin and actin were partially removed by high-KCl and gelsolin treatments, respectively. Differential heat denaturation of myosin (together with α-actinin) and actin was induced to confirm their contributions. On the DSC curve, aside from the endothermic peaks representing ice melting and protein denaturation, the steady baseline level showed a significant increase in basal heat capacity in the presence of skinned muscle compared to the rigor solution alone. In the physiological temperature range from 10 to 25 °C, untreated skinned muscle in the native state (non-denatured) introduced an extra basal heat capacity of 0.4 J K⁻¹ (g evaporable weight)⁻¹, which was diminished by both removing and denaturing actin and was additionally increased by removing myosin; myosin denaturation had little effect on the basal heat capacity. Based on these results, we considered actin to be the fundamental source of extra basal heat capacity, which was partly suppressed by the thermally stable region of myosin under rigor conditions. This extra basal heat capacity was roughly preserved at sub-zero temperatures, suggesting the involvement of non-freezing water molecules. The extra basal heat capacity may have contributed to thermal buffering during muscle function via actin-associated hydration. As a supplemental result, we found a small reversible endothermic peak around −21 °C, which was suppressed in the presence of skinned muscle. Heating beyond the denaturing temperatures reduced this suppression effect. Full article

The solidified natural gas (SNG) technology presents a prospective strategy for CH₄ storage and transportation. Low gas storage capacity and slow formation rate remain the key challenges for its field applications. This study suggested a compound system of cyclopentane (CP) + graphite nanoparticle (GNP) nanofluid to enhance the formation kinetics of CH₄ hydrate. Results indicated that both gas consumption and hydrate formation rate were higher at a higher CP concentration, peaking at 14 wt%, where t₉₀ (the time to reach 90% of the final gas uptake) was 65.7 min, and the gas uptake reached 0.1346 mol/mol. However, an excessive CP (21 wt%) negatively affected CH₄ hydrate generation kinetics due to the excessive cage occupancy of CP in 5¹²6⁴ cavities. A lower temperature was determined to be more favorable for CH₄ hydrate formation within nanofluids, which was visually demonstrated by the denser hydrate crystals formed at 275.15 K. Moreover, storage stability analysis revealed that CH₄ hydrate formed in CP + GNP nanofluids can be preserved at atmospheric pressure and 268.15 K without significant decomposition. This work provides a superior scheme for hydrate-based CH₄ storage, offering great contributions to SNG technology advancement. Full article

A new composite microwave–dielectric system, (1 − x)Li_2.08TiO₃-xLi₂ZnTi₃O₈ (x = 0.3–0.7), was systematically investigated to identify the optimal composition for low-temperature co-fired ceramic (LTCC) applications by correlating sintering behavior, microstructural evolution, and microwave–dielectric properties. Although the undoped compositions exhibited excellent intrinsic dielectric performance, they required sintering at 1100 °C, making them incompatible with Ag-based LTCC processing. Among the investigated formulations, 0.6Li_2.08TiO₃–0.4Li₂ZnTi₃O₈ was identified as the most suitable base composition. To reduce the sintering temperature, 0.3–1.0 wt.% V₂O₅ was introduced as a sintering aid, enabling densification at 900 °C for 30 min (97.0% relative density) while preserving the coexistence of Li_2.08TiO₃ and Li₂ZnTi₃O₈ without XRD-detectable secondary phases. Microstructural observations indicated that V₂O₅ promoted liquid-phase sintering, leading to enhanced densification and Li_2.08TiO₃-selective abnormal grain coarsening without altering the intrinsic permittivity. Complementary dilatometry provided process-level evidence for this liquid-phase sintering mechanism: large total shrinkage at 900 °C ($∆L/L_o$≈ −17–19%), earlier ${\mathrm{T}}_{\mathrm{o}\mathrm{n}\mathrm{s}\mathrm{e}\mathrm{t}}$/${\mathrm{T}}_{\mathrm{p}\mathrm{e}\mathrm{a}\mathrm{k}}$ with ${\mathrm{T}}_{\mathrm{p}\mathrm{e}\mathrm{a}\mathrm{k}}$ lowered by ~250 °C, and an increased ${\mathrm{R}}_{\mathrm{p}\mathrm{e}\mathrm{a}\mathrm{k}}$, collectively supporting 900 °C/30 min as the practical firing window. The optimized 0.6Li_2.08TiO₃–0.4Li₂ZnTi₃O₈ composition containing 0.3 wt.% V₂O₅ exhibits excellent microwave–dielectric properties (${\epsilon }_{\mathit{r}}$ = 23.32, Q × f = 68,400 GHz, and ${\tau }_{\mathit{f}}$ = −1.55 ppm/°C). Higher V₂O₅ contents (>0.3 wt.%) caused a gradual reduction in Q × f due to increasing microstructural non-uniformity. Ag co-firing tests confirmed electrode stability with no interfacial reactions at 900 °C for 30 min. Overall, 0.3 wt.% V₂O₅-assisted 0.6Li_2.08TiO₃–0.4Li₂ZnTi₃O₈ provides a practical sub-950 °C processing window that satisfies key LTCC requirements, including moderate permittivity, high Q × f, near-zero ${\tau }_{\mathit{f}}$, and compatibility with Ag electrodes. Full article

We examine how the Arctic Oscillation (AO) shapes winter sea-surface-temperature (SST) variability in the East/Japan Sea, with a focus on sub-seasonal SST memory (how long anomalies persist) and air–sea coupling (where SST and atmospheric anomalies co-vary). Using daily OISST v2.1 and ERA5 reanalysis for 1993–2022, we first analyze winter persistence of SST and key atmospheric drivers and identify East Korea Bay and the Subpolar Front as hotspots of long-lived SST anomalies. A rank-reduced multivariate maximum covariance analysis then extracts the leading coupled mode between SST and a set of atmospheric fields under positive and negative AO phases; in both phases the coupled mode is front-anchored, but its amplitude and spatial focus differ. Finally, to quantify the mixed-layer memory, we construct Ornstein–Uhlenbeck-like time-integrated responses of the atmospheric principal components. The effective integration timescales, determined by maximizing zero-lag correlations with the SST mode, cluster at approximately 2–3 weeks for wind-stress curl and near-surface variables and 4–7 weeks for sea-level pressure and meridional wind, with longer timescales during negative AO. The time-integrated atmospheric responses exhibit SST-like persistence, confirming the mixed layer’s role as a stochastic integrator. These AO-conditioned memory windows define practical lead times over which integrated atmospheric indices can act as predictors of winter marine heatwaves and cold-surge-impacted SST anomalies. Full article

Polyampholytes combine cationic and anionic groups in one macromolecular platform and are emerging as versatile components for energy storage and conversion. This review synthesizes how their charge balance, hydration, and architecture can be engineered to address ionic transport, interfacial stability, and safety across batteries, supercapacitors, solar cells, and fuel cells. We classify annealed, quenched, and zwitterionic systems, outline molecular design strategies that tune charge ratio, distribution, and crosslinking, and compare device roles as gel or solid electrolytes, eutectogels, ionogels, binders, separator coatings, and interlayers. Comparative tables summarize ionic conductivity, cation transference number, electrochemical window, mechanical robustness, and temperature tolerance. Across Li and Zn batteries, polyampholytes promote ion dissociation, homogenize interfacial fields, suppress dendrites, and stabilize interphases. In supercapacitors, antifreeze hydrogels and poly(ionic liquid) networks maintain conductivity and elasticity under strain and at subzero temperature. In solar cells, zwitterionic interlayers improve work function alignment and charge extraction, while ordered networks in fuel cell membranes enable selective ion transport with reduced crossover. Design rules emerge that couple charge neutrality with controlled hydration and dynamic crosslinking to balance conductivity and mechanics. Key gaps include brittleness, ion pairing with multivalent salts, and scale-up. Opportunities include soft segment copolymerization, ionic liquid and DES plasticization, side-chain engineering, and operando studies to guide translation. Full article

This study presents the design and validation of an open-source framework for biomedical signal acquisition and interoperable data exchange based on the Health Level Seven—Fast Healthcare Interoperability Resources (HL7 FHIR) standard. The proposed system enables secure, wireless transmission of physiological data from distributed sensing nodes toward a locally hosted monitoring platform. The hardware architecture integrates ESP32-WROOM-32 microcontrollers for multi-parameter acquisition, the MQTT protocol for low-latency communication, and a Home Assistant (Nabu Casa, San Diego, CA, USA)–InfluxDB (InfluxData, San Francisco, CA, USA)–Grafana (Grafana Labs, New York, NY, USA) stack for real-time visualization. The novelty of this work lies in the full-stack implementation of HL7 FHIR Observations within a reproducible, open-source environment, ensuring semantic interoperability without reliance on proprietary middleware or cloud services. A case study involving multi-sensor acquisition of electrocardiographic (ECG), photoplethysmographic (PPG), temperature, and oxygen saturation signals was conducted to evaluate system performance. Validation results confirmed consistent end-to-end data flow, sub-second latency, zero packet loss, and accurate semantic preservation across all processing stages. These findings demonstrate the feasibility of implementing standardized, open, and scalable biomedical Internet of Medical Things (IoMT) systems using non-proprietary components. The proposed framework provides a reproducible foundation for future telemedicine and continuous patient-monitoring applications, aligning with FAIR data principles and the ongoing digital transformation of healthcare. Full article

This study explores the effects of low temperatures on the performance of various lithium-ion batteries (LIBs), comparing different sizes and chemical compositions. Experiments were conducted in a sub-zero temperature environment, examining discharge behavior, internal resistance, and capacity retention. The findings reveal that smaller-sized batteries (18650, 21700) have a marked resilience to cold, outperforming larger 26650 cells, with smaller average capacity declines noted in both LiCoO₂ and LiMn₂O₂ chemistries. The study also introduces a new adaptive filtering technique for better battery behaviour analysis at low temperatures, which avoids distortion of important electrochemical signals. Full article

Partially frozen soil (PFS) is comprises of coexisting unfrozen water and ice within its pores at subzero temperatures. The review paper examines how unfrozen water content (UWC) and pore ice content interact during phase changes under near-freezing conditions, governed by microscopic thermodynamic equilibrium. Key theories describing why UWC persists (premelting, disjoining pressure) and the soil freezing characteristic curve (SFCC), along with measurement techniques, including the gravimetric approach to advanced nuclear magnetic resonance for characterization of water content. The influence of the water–ice phase composition on mechanical behavior is discussed, signifying pore pressure and effective stress. Various modelling approaches categorized into empirical SFCC, physio-empirical estimations, and emerging machine learning and molecular simulations are evaluated for capturing predictions in PFS behavior. The relevance of PFS to infrastructure foundation, tailings dams, permafrost slope stability, and climate change impacts on cold regions’ environmental geotechnics is also highlighted as a challenges in practical application. Hence, understanding pore pressure dynamics and effective stress in PFS is critical when assessing frost heave, thaw weakening, and the overall performance of geotechnical structures in cold regions. By combining micro-scale phase interaction mechanisms and macro-scale engineering observations, this review paper provides a theoretical understanding of the underlying concepts vital for future research and practical engineering in cold regions. Full article

Ti-6Al-4V is valued for its strength-to-weight ratio in engineering applications. Cryo-rolling at sub-zero temperatures enhances strength and hardness through grain refinement and dislocation build-up. The present study investigates the role of cryo-rolling on the microstructural characteristics and mechanical properties of the alloy, which undergoes various degrees of deformation followed by heating at 900 °C for selected samples. Microstructural analysis reveals grain elongation, sub-grain formation, deformation bands, and dislocation densification with increasing thickness reduction. Twinning dominates deformation at low strain, while dislocation slips take over at high strain because of the decrease in grain size, which makes the formation of new twins progressively more challenging. No metastable phase appears during cryo-rolling or heat treatment, as confirmed by X-ray diffraction. Cryo-rolled samples exhibit about 45% and 29% reduction in grain size and crystallite size, and 160% intensification in dislocation density. This leads to rises of 19%, 23%, and 10% in yield strength, tensile strength, and hardness, respectively, while ductility remains nearly constant across all cryo-rolled conditions. Cryo-rolling inhibits dynamic recovery and recrystallisation, so strengthening mainly results from grain refinement and dislocation accumulation. These findings suggest that cryo-rolling can improve the strength and hardness of Ti-6Al-4V, while maintaining ductility and providing new processing insights. Full article

Hydrogels with excellent flexibility and conductivity have attracted intensive attention in wearable human monitoring and energy harvesting devices. However, hydrogels containing plenty of water inevitably freeze at subzero temperatures, which deteriorates flexibility and conductivity and limits their practical applications. Herein, an anti-freezing ionic conductive hydrogel is developed by introducing Na⁺ into the gellan gum/hydrophobically associated polyacrylamide double network. The optimized anti-freezing hydrogel AICH₃ achieves outstanding mechanical properties (fracture stress 1.1 MPa and fracture strain 1700%), remarkable conductivity (2.2 S/m), and impressive strain sensitivity (GF = 7.4) at −20 °C. Benefiting from excellent flexibility, conductivity and strain sensitivity, the assembled AICH₃-based strain sensor can accurately sense the bending movement of the bionic finger at −20 °C. In addition, the AICH₃ can also be used as a stretchable electrode of a triboelectric nanogenerator (TENG), and the assembled AICH₃-based TENG can effectively harvest energy and power electronic devices at −20 °C. The comprehensive mechanical and conductive properties of AICH₃ at subzero temperatures might be attributed to the multifunctionality of Na⁺, which not only promotes the fabrication of physically crosslinked gellan gum/hydrophobically associated polyacrylamide double network but also suppresses the formation of ice crystals. Full article

Rapid heating strategies are essential for the cold-start of lithium-ion batteries at subzero temperatures to avoid severe performance losses. This study explores different external and battery-powered heating strategies and evaluates the time required for 21700 lithium-ion battery modules to reach the minimum safe-operating temperature. Three heating strategies were simulated: battery discharge, external heating, and combined configurations at ambient temperatures of −20 to 0 °C with initial state of charges (SOCs) of 20–80%. Results show that with discharge-only heating, the module heated up slowly and was unable to completely discharge at −20 °C and 20% SOC. Yet when the external surface-heating strategy was applied, the module was heated up 75–86% faster to reach the safe-operating temperature, which allowed the module to discharge completely under all conditions. Furthermore, in a combined configuration strategy where the external surface-heating is applied while the module discharges, the module achieved an additional 7–21% faster temperature rise. Lastly, at −20 °C and 20% SOC, external heater energy exceeded the module’s usable output, while at 0 °C and moderate SOC, heater demand was only 2–3% of available battery capacity. Overall, findings show combining external heating discharge enables a reliable cold-start for the battery modules studied. Full article

Asynchronous flowering between male and female date palms (Phoenix dactylifera L.) makes pollen storage a practical necessity for growers, especially for cultivars like ‘Mejhoul’, which require artificial pollination. This study examined the stainability of pollen as an indicator of cytoplasmic integrity, from four male date plant pollen donor genotypes (‘Mejhoul’, ‘Deglet Nour’, ‘Khadrawy’, and ‘Zahidi’) stored at 4 °C for different durations (fresh, one-year, and two-year storage) and their effects on fruit set and physical fruit characteristics of the Mejhoul cultivar in Mexico. Pollen stainability was assessed in vitro using 1% acetocarmine. Fruit and seed set percentages were evaluated as indicators of the practical effectiveness of stored pollen under field conditions, but not as direct measures of viability. Results showed that fresh pollen exhibited the highest stainability (91.2–95.6%), followed by one-year-stored pollen (59.4–68.3%), and two-year-stored pollen (38.8–45.4%). Fruit set percentages were highest with fresh pollen (63.8–81.7%), decreasing with storage duration. ‘Deglet Nour’ pollen consistently showed superior compatibility with ‘Mejhoul’ females. Physical fruit characteristics (weight, length, diameter) and seed traits were minimally affected by reduced pollen stainability, indicating that there were enough viable grains for effective pollination. The study also observed Metaxenia and Xenia effects, where pollen genotypes influenced fruit and seed size. Overall, these findings suggest that pollen stored at 4 °C for short and medium terms can be used in Mejhoul production, but longer storage significantly reduces efficacy, recommending sub-zero temperatures for extended preservation. Full article