Search Results (47)

In semi-arid regions of Morocco, where the majority of water withdrawals are devoted to irrigation, optimizing irrigation practices in agriculture is a national priority in the face of recurring droughts and growing pressure on groundwater resources. However, the hydrological impacts of different drip-irrigation systems in the soil–plant–atmosphere continuum remain insufficiently understood. We monitored the stable isotope composition (δ²H, δ¹⁸O) across the two agricultural plots in Marrakech (Morocco) with surface drip and subsurface drip irrigation treatments for a complete hydrologic year (June 2022 to June 2023). Weekly to daily samples of rainfall, irrigation water, groundwater, and soil at various depths (5–50 cm) were sampled, and water from branch xylem was extracted using the cryogenic vacuum distillation method. We found that the subsurface irrigation treatment, which delivered water directly to the root zone, maintained narrow isotopic ranges in water of soils beyond 30 cm, as well as in branch xylem and leaf water. By contrast, surface irrigation treatment plots showed pronounced evaporative isotopic enrichment: summer topsoil water δ¹⁸O peaked at −1.1‰ (vs. −8.7‰ in subsurface irrigation treatment), and leaf water reached +13‰ (vs. +8‰ in subsurface). Despite this larger isotopic heterogeneity in surface irrigation site, branch xylem water δ¹⁸O remained within −6 to 2.5‰ across all soil depth, similar to subsurface irrigation treatment, which ranged between −5 and 0‰. This suggests that olive roots accessed soil water uniformly from the upper 50 cm under both irrigation treatments. Seasonal xylem isotopic enrichment in spring and midsummer mirrored shifts towards shallow, evaporatively altered soil water under surface irrigation, but not under the subsurface. The results suggest that subsurface drip irrigation can significantly improve drought resilience and water-use efficiency in the expanding olive sector of the Maghreb, while continuous isotope monitoring serves as a practical approach to enhance sustainable and adaptive water management in water-limited regions. Full article

Waterfowl semen cryopreservation technology is a key link in genetic resource conservation and artificial breeding, but poultry spermatozoa, due to their unique morphology and biochemical properties, are prone to oxidative stress during freezing, resulting in a significant decrease in vitality. In this study, we first used four different freezing procedures (P1–P4) to freeze duck semen and compared their effects on duck sperm quality. Then, the changes in antioxidant indexes in semen were monitored. The results showed that program P4 (initial 7 °C/min slow descent to −35 °C, followed by 60 °C/min rapid descent to −140 °C) was significantly better than the other programs (p < 0.05), and its post-freezing sperm vitality reached 71.41%, and the sperm motility was 51.73%. In the P1 and P3 groups, the sperm vitality was 65.56% and 53.41%, and the sperm motility was 46.99% and 31.76%, respectively. In terms of antioxidant indexes, compared with the fresh semen group (CK), the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-px) in the P2 group were significantly decreased (p < 0.05), while the activities of SOD and CAT in the P4 group showed no significant changes (p > 0.05) except that the activity of GSH-px was significantly decreased (p < 0.05). And the CAT and GSH-px activities in the P4 group were significantly higher than those in the P2 group (p < 0.05). The content of malondialdehyde (MDA) in the P2 group was significantly higher than that in the fresh semen group (p < 0.05), and there was no significant difference between the P2 group and the P4 group (p > 0.05). The total antioxidant capacity (T-AOC) content of the P2 and P4 groups was significantly lower than that of the fresh semen group (p < 0.05). The staged cooling strategy of P4 was effective in reducing the exposure time to the hypertonic environment by balancing intracellular dehydration and ice crystal inhibition, shortening the reactive oxygen species accumulation and alleviating oxidative stress injury. On the contrary, the multi-stage slow-down strategy of P2 exacerbated mitochondrial dysfunction and the oxidative stress cascade response due to prolonged cryogenic exposure time. The present study confirmed that the freezing procedure directly affects duck sperm quality by modulating the oxidative stress pathway and provides a theoretical basis for the standardization of duck semen cryopreservation technology. Full article

The growing global demand for electricity, driven by the development of electromobility, data centers, and smart technologies, necessitates innovative approaches to energy generation. Wind power, as a clean and renewable energy source, plays a pivotal role in the global transition towards low-carbon power systems. This paper presents a comprehensive review of generator technologies used in wind turbine applications, ranging from conventional synchronous and asynchronous machines to advanced concepts such as low-speed direct-drive (DD) generators, axial-flux topologies, and superconducting generators utilizing low-temperature superconductors (LTS) and high-temperature superconductors (HTS). The advantages and limitations of each design are discussed in the context of efficiency, weight, reliability, scalability, and suitability for offshore deployment. Special attention is given to HTS-based generator systems, which offer superior power density and reduced losses, along with challenges related to cryogenic cooling and materials engineering. Furthermore, the paper analyzes selected modern generator designs to provide references for enhancing the performance of grid-synchronized hybrid microgrids integrating solar PV, wind, battery energy storage, and HTS-enhanced generators. This review serves as a valuable resource for researchers and engineers developing next-generation wind energy technologies with improved efficiency and integration potential. Full article

With the development of the agro-processing industry, the efficient cryogenic treatment and resource utilization of porcine bile—a high-value byproduct—has received increasing attention. This study investigates the dynamic behaviour and freezing characteristics of porcine bile droplets upon impact on cold substrates under varying conditions of surface temperature (−10 °C to −20 °C) and impact velocity (0.18–0.59 m/s). The effects of droplet size, dimensionless numbers (Weber, Reynolds, Bond, Ohnesorge, and Prandtl), and thermal gradients were systematically analyzed. A thermoelectric cooling substrate combined with high-speed imaging was used to quantitatively characterize the spreading ratio, retraction ratio, and freezing time of droplets. The results show that the maximum spreading ratio increases with higher impact velocity but decreases with lower substrate temperature. Lower substrate temperatures significantly shorten the freezing time, with a maximum reduction of up to 45%, particularly for smaller droplets. Droplets with high Weber numbers (We > 3) form flattened ice layers with preserved retraction patterns, while those with low Weber numbers (We < 1) generate smooth, hemispherical ice caps. For the first time, the thermophysical properties of porcine bile were incorporated into the framework of droplet impact dynamics on cryogenic surfaces. The findings reveal multiscale freezing mechanisms of biological fluids at low temperatures and provide a theoretical basis for optimizing processes such as freeze-drying and cryogenic sterilization in agro-product processing. Full article

Background and objectives: Decompressive craniectomy (DC) is a surgical procedure, useful for relieving the intracranial pressure following trauma. Following reduction in cerebral oedema, the bone is placed back to cover the defect. During the interim period, the bone flap may be preserved using cryopreservation or in subcutaneous tissue. This leads to a need to determine the benefits and risks involved in preservation of bone flap in a subcutaneous pocket or conventional freezer following decompressive craniectomy in traumatic brain injury. Materials and methods: An open randomized controlled trial was conducted at a level one trauma centre from July 2023 to December 2024. Simple randomization was performed in order to allocate patients into the subcutaneous preservation group and the cryogenic preservation group. Patients underwent cranioplasty after 3 months and were followed up post-operatively for complications and Glasgow Outcome Scale assessment. Results: The study initially recruited a total of 158 patients, out of which 104 patients remained eligible for the final analysis. The patients with cryopreserved flaps were found to have a higher rate of surgical site infection (31.3%) as compared to those with subcutaneously preserved flaps (5.6%), with the differences being statistically significant (p < 0.001). Among the 87 patients who had a poorer Glasgow Outcome Scale (GOS) score before the intervention, 55 (63.2%) patients had at least some improvement in GOS over a period of one month. Conclusion: The use of subcutaneous preservation of bone is more beneficial in resource-limited settings as compared to conventional freezer storage. Full article

Liquid hydrogen is regarded as a key energy source and propellant for lunar bases due to its high energy density and abundance of polar water ice resources. However, its low boiling point and high latent heat of vaporization pose severe challenges for storage and management under the extreme lunar environment characterized by wide temperature variations, low pressure, and low gravity. This paper reviews the strategies for siting and deployment of liquid hydrogen storage systems on the Moon and the technical challenges posed by the lunar environment, with particular attention for thermal management technologies. Passive technologies include advanced insulation materials, thermal shielding, gas-cooled shielding layers, ortho-para hydrogen conversion, and passive venting, which optimize insulation performance and structural design to effectively reduce evaporation losses and maintain storage stability. Active technologies, such as cryogenic fluid mixing, thermodynamic venting, and refrigeration systems, dynamically regulate heat transfer and pressure variations within storage tanks, further enhancing storage efficiency and system reliability. In addition, this paper explores boil-off hydrogen recovery and reutilization strategies for liquid hydrogen, including hydrogen reliquefaction, mechanical, and non-mechanical compression. By recycling vaporized hydrogen, these strategies reduce resource waste and support the sustainable development of energy systems for lunar bases. In conclusion, this paper systematically evaluates passive and active thermal management technologies as well as vapor recovery strategies along with their technical adaptability, and then proposes feasible storage designs for the lunar environment. These efforts provide critical theoretical foundations and technical references for achieving safe and efficient storage of liquid hydrogen and energy self-sufficiency in lunar bases. Full article

The conventional pyrolysis of tar-rich coals faces limitations in maximizing tar yield and optimizing tar composition, often resulting in inefficient resource utilization and elevated emissions of CO₂. This study investigates a novel cryogenic pretreatment method using liquid nitrogen to enhance pyrolysis efficiency, aiming to improve tar yield and transform tar quality for sustainable coal utilization. Three tar-rich coals underwent cryogenic pretreatment at varying temperatures (0 to −90 °C) via liquid nitrogen, followed by pyrolysis. The product distribution (tar, gas) and quality were analyzed and compared to conventional pyrolysis and the Gray–King assay. The cryogenic pretreatment increased the tar yield by 25.8–44.6% compared to conventional methods, achieving a maximum yield of 7.8–16.0 wt% at −90 °C. The emissions of CO₂ decreased by 12.7–27.4%, while CH₄ and H₂ proportions rose by 15.1–60.2%, enhancing gas energy content. The pretreatment reduced benzene compounds by 4.4–13.9 wt% and increased aromatic derivatives by 13.9–20.5 wt%, indicating a shift toward higher-value chemicals. The cryogenic approach demonstrates the dual benefits of boosting tar productivity while reducing carbon emissions, offering a promising path for cleaner and more efficient coal pyrolysis. Full article

In recent years, the disposal of agricultural lignocellulosic residues has been accompanied by problems such as resource waste and environmental pollution. Therefore, the development of valorization technologies has emerged as a strategic priority in sustainable materials science. This study pioneered the use of corncob cellulose as the substrate (a representative agricultural lignocellulosic residue) and transformed it into ionized cellulose by grafting methacryloxyethyl trimethyl ammonium chloride (DMC) via atom transfer radical polymerization (ATRP) and UV-initiated polymerization. Characterizations demonstrated exceptional properties: robust mechanical strength (1.28 MPa tensile strength with 573% elongation); outstanding thermal stability (stable to 278 °C); cryogenic tolerance (retaining flexibility at −25 °C); and universal adhesion capability (4.23 MPa to glass substrates, with adequate interfacial bonding across diverse surfaces). Meanwhile, the ionogel exhibited exceptional sensing sensitivity (gauge factor, GF = 1.23–2.08), demonstrating versatile application potential in wearable electronics. It achieved the precise detection of subtle strains (1–5% strain range) and the high-fidelity acquisition of electrocardiogram (ECG) signals. This study broadens the design paradigm of agricultural lignocellulosic residue-based functional materials. It also provides a novel technical pathway to develop eco-friendly intelligent sensors. Full article

Geothermal energy can be obtained from hot dry rock (HDR). The target temperatures for heat extraction from HDR range from 100 to 400 °C. Artificial fracturing is employed to stimulate HDR and create a network of fractures for geothermal resource extraction. Liquid nitrogen (LN₂) is environmentally friendly and shows better performance in reservoir stimulation than does conventional fracturing. In this study, triaxial compression experiments and acoustic emission location techniques were used to evaluate the impacts of temperatures and confining pressures on the mechanical property deterioration caused by LN₂ cooling. The numerical simulation of LN₂ fracturing was performed, and the results were compared with those for water and nitrogen fracturing. The results demonstrate that the confining pressure mitigated the deterioration effect of LN₂ on the crack initiation stress, crack damage stress, and peak stress. From 20 to 60 MPa, LN₂-induced reductions in these three stress parameters ranged between 7.73–18.51%, 3.46–12.15%, and 2.51–8.50%, respectively. Cryogenic LN₂ increased the number and complexity of cracks generated during rock failure, further enhancing the fracture performance. Compared with those for water and nitrogen fracturing, the initiation pressures of LN₂ fracturing decreased by 61.54% and 68.75%, and the instability pressures of LN₂ fracturing decreased by 20.00% and 29.41%, respectively. These results contribute to the theoretical foundation for LN₂ fracturing in HDR. Full article

Cryogenics is the science and technology of very low temperatures, typically below 120 K. The most common applications are liquified natural gas carriers, ground-based tanks, and propellant tanks for space launchers. A crucial aspect of cryogenic technology is effective insulation to minimise boil-off from storage tanks and prevent frost build-up. Rigid closed-cell foams are prominent in various applications, including cryogenic insulation, due to their balance between thermal and mechanical properties. Polyurethane (PU) foam is widely used for internal insulation in cryogenic tanks, providing durability under thermal shocks and operational loads. External insulation, used in liquified natural gas carriers and ground-based tanks, generally demands less compressive strength and can utilise lower-density foams. The evolution of cryogenic insulation materials has seen the incorporation of environmentally friendly blowing agents and bio-based polyols to enhance sustainability. Fourth-generation physical blowing agents, such as HFO-1233zd(E) and HFO-1336mzz(Z), offer low global warming potential and improved thermal conductivity. Additionally, bio-based polyols from renewable resources like different natural oils and recycled polyethylene terephthalate (PET) are being integrated into rigid PU foams, showing promising properties for cryogenic applications. Research continues to optimise these materials for better mechanical performance and environmental impact. Full article

Common challenges in cryogenic electron microscopy, such as orientation bias, conformational diversity, and 3D misclassification, complicate single particle analysis and lead to significant resource expenditure. We previously introduced an in silico method using the maximum Feret diameter distribution, the Feret signature, to characterize sample heterogeneity of disc-shaped samples. Here, we expanded the Feret signature methodology to identify preferred orientations of samples containing arbitrary shapes with only about 1000 particles required. This method enables real-time adjustments of data acquisition parameters for optimizing data collection strategies or aiding in decisions to discontinue ineffective imaging sessions. Beyond detecting preferred orientations, the Feret signature approach can serve as an early-warning system for inconsistencies in classification during initial image processing steps, a capability that allows for strategic adjustments in data processing. These features establish the Feret signature as a valuable auxiliary tool in the context of single particle analysis, significantly accelerating the structure determination process. Full article

Due to the extensive utilization of liquid nature gas (abbreviated as LNG) resources and a multitude of considerations, LNG storage tanks are gradually transitioning towards smaller footprints and heightened safety standards. Consequently, underground LNG storage tanks are being designed and constructed. However, underground LNG storage tanks release a considerable quantity of cold into the ground under both accidental and normal conditions. The influence of cold results in the ground freezing, which further compromises the safety of the structure. Existing research has neglected to consider the effects of this. This oversight could potentially lead to serious safety accidents. In this work, a complete set of experiments using a novel LNG underground storage tank fluid-solid-thermal coupled cryogenic leakage scale model were conducted for the first time to simulate the effect of the tank on the soil temperature field, stress field, and displacement field and to analyze the development of the three fields and the results of the effect. This research helps the related personnel to better design, construct, and evaluate the LNG underground storage tanks to avoid the catastrophic engineering risks associated with cryogenic leakage and helps to improve the design process of LNG underground storage tanks. Full article

Magnetoencephalography (MEG) non-invasively provides important information about human brain electrophysiology. The growing use of optically pumped magnetometers (OPM) for MEG, as opposed to fixed arrays of cryogenic sensors, has opened the door for innovation in system design and use cases. For example, cryogenic MEG systems are housed in large, shielded rooms to provide sufficient space for the system dewar. Here, we investigate the performance of OPM recordings inside of a cylindrical shield with a 1 × 2 m² footprint. The efficacy of shielding was measured in terms of field attenuation and isotropy, and the value of post hoc noise reduction algorithms was also investigated. Localization accuracy was quantified for 104 OPM sensors mounted on a fixed helmet array based on simulations and recordings from a bespoke current dipole phantom. Passive shielding attenuated the vector field magnitude to 50.0 nT at direct current (DC), to 16.7 pT/√Hz at power line, and to 71 fT/√Hz (median) in the 10–200 Hz range. Post hoc noise reduction provided an additional 5–15 dB attenuation. Substantial field isotropy remained in the volume encompassing the sensor array. The consistency of the isotropy over months suggests that a field nulling solution could be readily applied. A current dipole phantom generating source activity at an appropriate magnitude for the human brain generated field fluctuations on the order of 0.5–1 pT. Phantom signals were localized with 3 mm localization accuracy, and no significant bias in localization was observed, which is in line with performance for cryogenic and OPM MEG systems. This validation of the performance of a small footprint MEG system opens the door for lower-cost MEG installations in terms of raw materials and facility space, as well as mobile imaging systems (e.g., truck-based). Such implementations are relevant for global adoption of MEG outside of highly resourced research and clinical institutions. Full article

To investigate the potential of an affordable cryotherapy device for the accessible treatment of breast cancer, the performance of a novel carbon dioxide-based device was evaluated through both benchtop testing and an in vivo canine model. This novel device was quantitatively compared to a commercial device that utilizes argon gas as the cryogen. The thermal behavior of each device was characterized through calorimetry and by measuring the temperature profiles of iceballs generated in tissue phantoms. A 45 min treatment in a tissue phantom from the carbon dioxide device produced a 1.67 ± 0.06 cm diameter lethal isotherm that was equivalent to a 7 min treatment from the commercial argon-based device, which produced a 1.53 ± 0.15 cm diameter lethal isotherm. An in vivo treatment was performed with the carbon dioxide-based device in one spontaneously occurring canine mammary mass with two standard 10 min freezes. Following cryotherapy, this mass was surgically resected and analyzed for necrosis margins via histopathology. The histopathology margin of necrosis from the in vivo treatment with the carbon dioxide device at 14 days post-cryoablation was 1.57 cm. While carbon dioxide gas has historically been considered an impractical cryogen due to its low working pressure and high boiling point, this study shows that carbon dioxide-based cryotherapy may be equivalent to conventional argon-based cryotherapy in size of the ablation zone in a standard treatment time. The feasibility of the carbon dioxide device demonstrated in this study is an important step towards bringing accessible breast cancer treatment to women in low-resource settings. Full article

The combined application of steel–FRP composite bars (SFCBs) and seawater sea-sand concrete (SSSC) in marine engineering not only solves the problem of resource scarcity and reduces the construction cost but also avoids the problems of chloride corrosion of steel reinforcement in seawater sea-sand concrete and the lack of ductility of FRP bars. At the same time, the addition of glass fiber (GF) and expansion agent (EA) in appropriate amounts improves the crack resistance and seepage resistance of concrete. However, the durability of SFCB with GF- and EA-reinforced SSSC in freezing–thawing environment remains unclear, which limits its potential application in cryogenic marine engineering. This study investigates the bonding properties between SFCB and GF-EA-SSSC interfaces using eccentric pullout experiments under different thicknesses of concrete protective cover and a number of freezing–thawing cycles. The results showed that the compressive strength and dynamic elastic modulus of SSSC decrease, while the mass loss increases with an increasing number of freezing–thawing cycles. Additionally, the bond strength and stiffness between SFCB and SSSC decrease, leading to an increase in relative slip. However, the rate of bond strength and stiffness loss decreases with an increase in the thickness of the concrete protective cover. Furthermore, formulas for bond strength, relative slip, and bond stiffness are established to quantify the effects of the thickness of the concrete protective cover and the number of freezing–thawing cycles. The experimental values obtained verify the accuracy of these formulas, with a relative error of less than 5%. Moreover, a bond stress–slip constitutive model is developed for SFCB and GF-EA-SSSC, and the fitting results closely resemble the experimental values, demonstrating a high level of model fit. Full article