Cortisol deposited in the hair can be used as a tool for the objective assessment of chronic stress. The authors compared the efficiency of cortisol extraction by several methods in different individuals. Hair samples from 20 men were either prewashed or not, and either cut into small pieces with scissors or pulverized using liquid nitrogen. Afterward, temperature (16 hours at 52°C), sonication (2 hours), or both were used to increase the efficiency of methanol extraction. Duplicate samples were analyzed using enzyme-linked immunosorbent assay for cortisol measurement (n = 480). Cortisol data had a non-normal distribution and are expressed as median. An alpha level less than 0.05 was considered significant. Hair cortisol levels were between 0.3 and 60 pg/mg and differed between the participants (P < 0.001). No significant difference was noted between prewashing and not prewashing procedures (19.5 vs. 20.6, respectively; P = 0.247). Cutting into small pieces with scissors yielded lower cortisol levels compared with pulverization (17.4 vs. 22.0 pg/mg, P = 0.002); however, no differences were observed when temperature or sonication or both were used (20.2, 19.7, and 19.6 pg/mg, respectively, P = 0.971). Overall, the technique was sensitive to detect varying levels of hair cortisol in each individual. Prewashing, temperature, and sonication were observed to be unnecessary. Although pulverization caused higher hair cortisol extraction (4.6 pg/mg), it was relatively low compared with the large interindividual differences. Thus, any of the methods could be used, especially when the time and cost of analyses are considered.

Non-biodegradable adhesives accumulate in ecosystems and contribute to contamination. They even contaminate recyclable materials, reducing the efficiency of recycling processes or rendering them impossible. Transitioning to biodegradable or recyclable adhesives is critical to mitigating these environmental impacts and advancing zero-waste initiatives. A nacre-inspired hard-soft multiphase structure is developed to serve as a heat-free adhesive system, delivering superior adhesion strength across metal, plastic, and glass substrates. Autonomous reconstruction of physically cross-linked networks and strain-induced orientation synergistically achieve up to 120 de-bonding and re-bonding cycles with progressive adhesion enhancement. Repeatable bonding with reinforcement instead of strength reduction enables error-tolerant applications. Unique thermal responsiveness that maintains exceptional adhesion performance under low-temperature conditions, especially in liquid nitrogen environments, is investigated. The dynamic equilibrium of non-covalent interactions coupled with hydrolytically sensitive ester bonds permits tunable degradation kinetics through compositional modulation. This design paradigm establishes an eco-friendly alternative to conventional adhesives, particularly suitable for applications demanding recyclability, environmental compatibility, repeated usability, and operation under ultra-low temperature conditions.

Abstract Achieving a uniform current distribution among parallel conductors is essential to prevent local heating and performance degradation in superconducting rotating machines that are used in aircraft to realize high-current operation. Although transposition methods are effective under single-phase excitation, their effectiveness under practical motor conditions remains unclear. This study investigates the current distribution characteristics of three parallel conductors transposed within an armature coil under realistic motor operating conditions involving three-phase excitation and rotor rotation. To this end, we conducted numerical simulations using finite element analysis for evaluating the effect of both the three-phase magnetic field and the rotating magnetic field of the rotor on current distribution. A previously developed transposition configuration for single-phase armature coils was applied to a three-stranded double-pancake winding, and an analysis was conducted. The results revealed that transposition significantly suppressed current imbalance even in the presence of rotor rotation, reducing the deviation from the ideal distribution to within a few percentages. Further, shielding currents induced by the magnetic field of the rotor were identified as a major factor. The effect of the shielding current on the current distribution was substantially mitigated by the transposition design. Experiments were performed in liquid nitrogen using a rotating test system for validating the method, and current distributions were measured using Rogowski coils under both static and rotating conditions. The measured results were in close agreement with the simulation results, confirming that the proposed transposition method was effective even under actual motor operating conditions. These findings confirm that transposition configurations developed under single-phase conditions can be extended to realistic motor environments, providing a robust approach for ensuring current uniformity in multistrand superconducting armature coils.

In this study, the effects of cryogenic treatment and heat treatment on the microstructural evolution and mechanical properties of type-304 austenitic stainless steel are investigated. Cryogenic treatment is conducted in a liquid nitrogen environment at -196°C, both with and without a quenching process. The experimental results indicate that traditional heat treatment processes do not lead to improvements in hardness or phase transformation. Although a modest increase in the ultimate tensile strength is observed with prolonged immersion in liquid nitrogen, deep cryogenic treatment does not produce a significant enhancement in the tensile properties of the examined material. Among the cases examined, water-quenched heat treatment without cryogenic treatment demonstrates a considerable increase in ductility. Additionally, significant differences in microstructure and hardness are observed at different locations of the tensile specimen due to martensitic transformation from the austenitic phase during plastic deformation. Consequently, improvement in the mechanical properties of the steel is not a result of the heat treatment process; rather, the heat treatment affects the stability of the austenitic phase, thereby influencing the potential for martensitic transformation during plastic deformation.

Thermoelectric materials composed of 2D structures have received extensive attention and research due to their potential properties. The development of novel 2D materials will provide many valuable technological characteristics for thermoelectric applications. Here, fast thermoelectric responses are reported from unconventional Na-I stoichiometry in reduced graphene oxide films (Na-I@rGO). The thermoelectric mechanism is based on the Seebeck effect caused by the heterogeneous structure between the rGO layers from Na2I and NaI. The formation of this heterogeneous structure is attributed to the gravity-driven ion permeation during the preparation process and cation-π interactions. Na-I@rGO film exhibits a significant thermoelectric current at a temperature difference (ΔT) of 40 K (peak current ∼650 nA). The Seebeck coefficient of Na-I@rGO film is ≈22.7 µVK-1 for a ΔT range of 2-40 K. Importantly, Na-I@rGO film has a fast response (0.6 s) as a self-powered sensing device, which is comparable to that of most other reported classical thermoelectric materials. The Na-I@rGO sensor can be suitable for fast detecting transient extreme temperature variations, such as flame and liquid nitrogen. These findings can provide inspiration for the design of 2D thermoelectric structures on graphene films.

Since the discovery of high‐temperature superconductivity, in addition to its widespread application in the superconducting coils and cables, there is a field known as, what we call, “bulk magnets,” in which the bulk crystals are grown from the powder materials by heat treatments. Bulk magnets are used as pseudo‐permanent magnets, and used for non‐contact magnetic levitation, which is unique to high‐temperature superconductivity, and are expected to have wide industrial applications in the future. This report introduces the pulsed field magnetizing method as a simple way to activate the bulk magnets, and refers to the research results. As for the application of strong magnetic field we refer to the studies on TD‐NMR using a single magnetic pole, the magnetic separation of Ni‐plating wastes, and the applications to rotating machines. As for the magnetic levitation, we take the human levitation models, the transport devices, and the non‐contact bearings. In all the above application, the important thing we would propose is to utilize not only liquid nitrogen but also small and easy‐to‐use cryocoolers, which could enhance the performance of the devices, broadening options into the technologies that are expected to have wide markets in the future. © 2025 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Numerical simulation method for thermal-seepage coupling in artificial ground freezing using liquid nitrogen under high-seepage conditions

Use of cryopreserved whole blood samples in the Comet assay for detection of DNA damage in human population studies.

The objective of the study was to investigate the vanillic acid's (VA) protective effects, a phenolic compound, on the ram semen after freeze-thaw. Semen was obtained from Ramlıç rams and was diluted with control (0 μg/mL VA) and VA-supplemented Tris-based extenders at concentrations of 1, 10 and 50 μg/mL. The diluted semen was equilibrated for 2 h at +4°C, filled into 0.25 mL straws and frozen in liquid nitrogen vapour. It was then stored in a liquid nitrogen container at -196°C. For analysis, the samples were thawed at 37°C for 30 s in a water bath. There was no difference detected among total and progressive motility as well as velocity parameters (p > 0.05) except for rapid progressive motility (p < 0.05). The findings support the idea that VA has an outstanding effect on reducing DNA damage (p < 0.001). While there was no positive development with regard to total oxidant status (p > 0.05), VA enhanced the antioxidant defences of total antioxidant status (p < 0.05). VA administered at doses of 10 and 50 μg increased total antioxidant status (p < 0.01). Lipid peroxidation was not directly affected by VA application (p > 0.05); otherwise, 10 and 50 μg VA treatments showed a positive effect on viability (p < 0.001). Based on findings, it was concluded that although VA was put in the semen extender, it did not have an ameliorative potency on sperm motility and velocity properties except for specific sub-parameters such as rapid progressive motility. All applied doses reduced DNA damage, and 10 and 50 μg doses supported cellular viability.

Interrupted slow cooling of mouse cardiac endothelial cell monolayers.

Improving non-contact cooling rate with liquid nitrogen by hierarchical surface structures

Ultra-rapid freezing in spheres yields a higher cryoresistance than in straws but remains inferior to conventional slow freezing of stallion sperm.

Impact of direct/indirect freezing and pulsed electric field-assisted thawing on the techno-functional properties of cassava starch (Manihot esculenta Crantz).

State of the art and application of gamete and reproductive tissue banking in wildlife conservation.

Simmondsia chinensis, commonly known as jojoba, is an important renewable source of liquid wax esters valued for its unique seed oil that is used in several industries. Elite jojoba germplasm needs to be conserved owing to its overexploitation, climate variability and excessive dependence of selected cultivars. This study presents a straightforward and efficient droplet vitrification-based cryopreservation protocol in jojoba. Shoot tips isolated from eight-week-old cultures were cultured for two days on high sucrose (0.3M) enriched medium and then treated with loading solution containing 0.4M sucrose and 2M glycerol, followed by PVS2 exposure for 30min at room temperature. Vitrified shoot tips were then directly frozen in liquid nitrogen by placing them on aluminium foil strips. Frozen shoot tips were rewarmed in an unloading solution containing 1.2M sucrose for 15min, and then cultured on regeneration medium consisting of Murashige and Skoog medium (MS) supplemented with 4.97µM benzyl-amino purine (BAP) and 0.28 µM gibberellic acid (GA3). The protocol was optimized in one accession, where as high as 85.7% post-thaw survival and 76.1% regrowth were observed. The developed protocol was then tested for its efficacy and reproducibility on eleven other accession, and high post-thaw regrowth, ranging from 50 to 76.13% was observed. This study presents a broad spectrum, reproducible and efficient protocol for the conservation of jojoba genetic resources. This is the first report on cryopreservation of jojoba germplasm for its long-term conservation, providing a technical platform to set up cryobanks of valuable material of this important commercial crop.

Experimental study on real-time seepage-heat transfer characteristics of fractured granite during the cyclic liquid nitrogen injecting the hot dry rock reservoir

Liquid nitrogen quenching treatment stabilizes high-spin V ions in V2C/V1.156Se2 heterostructure for enhanced sodium ions capture in membrane capacitive deionization

Effects of desiccation and liquid nitrogen exposure on seeds of dragon fruit (Hylocereus costaricensis)

Experimental investigation of a single-stage micro pulse tube cryocooler operating at 59 Hz with liquid nitrogen precooling: Achieving 14.8 K under 5 W input power

Liquid nitrogen spray characterization in ambient and development of correlations for droplet diameter and velocity