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Introduction: Ice plugs acts as isolate maintenance sections during pipeline repairs in nuclear power plants can effectively reduce maintenance costs, which is formed by the cooling of liquid nitrogen. The single-jacket freezing method takes a long time for the formation of ice plugs with a certain load-bearing capacity, increasing the liquid nitrogen consumption.Methods: In this study, a multiple-jacket method for the formation of ice plugs was proposed, and the numerical simulation using CFD (Computational Fluid Dynamics) was conducted. The effects of total jacket length and jacket number on freezing time and the consumption of liquid nitrogen were analyzed.Results and Discussion: Research indicated that the multiple-jacket method obtained a 11%∼15% decrease in freezing time and a 18%∼26% decrease in liquid nitrogen consumption than the single-jacket method. For the multiple-jacket method, the gap between the jackets presented a certain influence on the freezing time and liquid nitrogen consumption. As the gap between the jackets increases, there exist a small increase in the freezing time, but the liquid nitrogen consumption will be reduced by 2% to 5%.

Cryopreservation, or the storage at liquid nitrogen temperatures (-196°C), of embryogenic cells or somatic embryos allows their long-term conservation without loss of their embryogenic capacity. During the last decade, protocols for cryopreservation of embryogenic material of woody species have been increasing in number and importance. However, despite the large experimental evidence proved in thousands of embryogenic lines, the application for the large-scale conservation of embryogenic material in cryobanks is still limited. Cryopreservation facilitates the management of embryogenic lines, reducing costs and time spent on their maintenance, thus limiting the risk of the appearance of somaclonal variation or contamination. Somatic embryogenesis in combination with cryopreservation is especially useful to preserve the juvenility of lines while the corresponding clones are being field-tested. Hence, when tree performance has been evaluated, selected varieties can be propagated from the cryostock. The traditional method of slow cooling or techniques based on vitrification are mostly applied procedures. For example, slow cooling methods are widely applied to conserve embryogenic lines of conifers. Desiccation based procedures, although simpler, have been applied in a smaller number of species. Genetic stability of the cryopreserved material is supported by multiloci PCR-derived markers in most of the assayed species, whereas DNA methylation status assays showed that cryopreservation might induce some changes that were also observed after prolonged subculture of the embryogenic lines. This article reviews the cryopreservation of embryogenic cultures in conifers, fruit species, deciduous forest species and palms, including a description of the different cryopreservation procedures and the analysis of their genetic stability after storage in liquid nitrogen.

In order to promote sustainable energy development and reduce the impact of fossil fuels on the environment, it is crucial to strengthen the development and utilization of clean and renewable geothermal energy. Liquid nitrogen fracturing, as an emerging waterless fracturing technology, has outstanding advantages in rock fracturing effect and thermal exchange ability with hot dry rock and is more environmentally friendly. In order to evaluate the influence of liquid nitrogen on the mechanical properties, acoustic emission characteristics, and cross-sectional crack propagation characteristics of granite at different initial temperatures, this paper carried out three-point bending tests and acoustic emission detection on granite treated by high-temperature heating and liquid nitrogen cooling. Finally, based on the cross-sectional scanning test, the expansion characteristics of microcracks in granite were analyzed. The results show that the higher the initial temperature of granite, the stronger the cold impact of liquid nitrogen on granite, and the faster the rock's mechanical performance declines. The acoustic emission ringing count is closely related to the development of microcracks in granite, and as the initial temperature of granite increases, the more ringing counts there are, indicating that the huge temperature difference induces more microcracks inside the rock. In addition, the cold impact of liquid nitrogen can effectively promote the fracturing of granite. After liquid nitrogen treatment, the fractal dimension of the granite cross-section increases, the shape of the cross-section becomes rough, and many micropores appear. This study can provide a scientific basis for the engineering application of liquid nitrogen fracturing technology. [ABSTRACT FROM AUTHOR]

High-pressure single crystal X-ray diffraction has been used to probe framework–guest interactions in the Co-based metal–organic framework ZIF-67 during compression in 4 : 1 MeOH : EtOH and liquid nitrogen (LN2) pressure-transmitting media. On increasing pressure, the structure undergoes a gate-opening phase transition, characterised by rotation of the 2-methylimidazolate ligand, at 1.57 GPa in MeOH : EtOH and at 0.43 GPa LN2. Adsorption of N2 occurred progressively with increasing pressure into 6 adsorption sites and resulted in the first documented instance of pressure-induced solvatochromism in ZIF-67. [ABSTRACT FROM AUTHOR]

Highlights: Presenting the first investigation into the structurally bubbling-failure mechanism of graphitic film during cyclic liquid nitrogen shocks. Proposing an innovative design about seamless heterointerface constructing a Cu-modified structure. Inventing a new ultra-stable species of highly thermally conductive films to inspire new techniques for efficient and extreme thermal management. Highly thermally conductive graphitic film (GF) materials have become a competitive solution for the thermal management of high-power electronic devices. However, their catastrophic structural failure under extreme alternating thermal/cold shock poses a significant challenge to reliability and safety. Here, we present the first investigation into the structural failure mechanism of GF during cyclic liquid nitrogen shocks (LNS), which reveals a bubbling process characterized by "permeation-diffusion-deformation" phenomenon. To overcome this long-standing structural weakness, a novel metal-nanoarmor strategy is proposed to construct a Cu-modified graphitic film (GF@Cu) with seamless heterointerface. This well-designed interface ensures superior structural stability for GF@Cu after hundreds of LNS cycles from 77 to 300 K. Moreover, GF@Cu maintains high thermal conductivity up to 1088 W m−1 K−1 with degradation of less than 5% even after 150 LNS cycles, superior to that of pure GF (50% degradation). Our work not only offers an opportunity to improve the robustness of graphitic films by the rational structural design but also facilitates the applications of thermally conductive carbon-based materials for future extreme thermal management in complex aerospace electronics. [ABSTRACT FROM AUTHOR]

The implications of different liquid nitrogen freezing (LNF) temperatures (−35 °C, −65 °C, −95 °C, and −125 °C) on the ice crystal and muscle quality of white shrimp (Litopenaeus vannamei) were investigated in this essay. The results showed that better muscle quality was maintained after LNF treatment compared to that after air blast freezing (AF) treatment. As the freezing temperature of liquid nitrogen decrease, the freezing speed accelerated, with the freezing speed of LNF at −125 °C being the fastest. However, an excessively fast freezing speed was not conducive to maintaining the quality of shrimp. Among all the freezing treatments, LNF at −95 °C led to the lowest thawing losses and cooking losses, and the highest L* values, indicating that LNF at −95 °C could keep the water holding capacity of frozen shrimp better than that with other freezing methods. At the same time, LNF at −95 °C resulted in higher water holding capacity, and hardness values for shrimps than those with other frozen treatments (p < 0.05). In addition, the results of the water distribution of shrimps showed that treatment with a −95 °C LNF reduced the migration rate of bound and free water. Meanwhile, the microstructural pores of shrimps in the −95 °C LNF group were smaller, indicating that the ice crystals generated during −95 °C LNF were relatively smaller than those generated via other frozen treatments. In conclusion, an appropriate LNF temperature (−95 °C) was beneficial for improving the quality of frozen shrimp, and avoiding freezing breakage. [ABSTRACT FROM AUTHOR]

Background: Transcriptomic studies often require collection of fresh tissues post euthanasia. The chosen euthanasia method might have the potential to induce variations in gene expressions that are unlinked with the experimental design. The present study compared the suitability of 'nitrogen gas in foam' (ANOXIA) in comparison to a non-barbiturate anaesthetic, T-61® (T61), for euthanizing piglets used in transcriptome research. Further, the effect of common tissue storage conditions, RNAlater™ (RL) and snap freezing in liquid nitrogen (LN2), on gene expression profiles were also analysed. Results: On comparison of the 3'mRNA-Seq data generated from pituitary, hypothalamus, liver and lung tissues, no significant differential expression in the protein coding genes were detected between the euthanasia methods. This implies that the nitrogen anoxia method could be a suitable alternative for euthanasia of piglets used in transcriptomic research. However, small nuclear RNAs (snRNAs) that constitute the eukaryotic spliceosomal machinery were found to be significantly higher (log2fold change ≥ 2.0, and adjusted p value ≤ 0.1) in pituitary samples collected using ANOXIA. Non-protein coding genes like snRNAs that play an important role in pre-mRNA splicing can subsequently modify gene expression. Storage in RL was found to be superior in preserving RNA compared to LN2 storage, as evidenced by the significantly higher RIN values in representative samples. However, storage in RL as opposed to LN2, also influenced differential gene expression in multiple tissues, perhaps as a result of its inability to inhibit biological activity during storage. Hence such external sources of variations should be carefully considered before arriving at research conclusions. Conclusions: Source of biological variations like euthanasia method and storage condition can confound research findings. Even if we are unable to prevent the effect of these external factors, it will be useful to identify the impact of these variables on the parameter under observation and thereby prevent misinterpretation of our results. [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusion To describe a simple cryosurgical technique for treating canine distichiasis, its success rate and any associated complications.Clinical records from canine patients undergoing treatment for distichiasis using a specific cryotherapy technique were retrospectively reviewed. The technique employed a triple freeze–thaw cycle via a transconjunctivally applied, liquid nitrogen‐cooled, 2‐mm diameter closed cryoprobe.The cryotherapy technique was employed in 125 dogs with distichiasis over a period of 13 years, with 109 (87%) bilaterally and 16 (13%) unilaterally affected, totaling 234 eyes. The mean age at diagnosis was 1.9 years (4 months to 7.5 years), with Staffordshire bull terriers the most common breed (31%). Treatment was deemed successful if clinical signs related to distichiasis resolved, including blepharospasm, conjunctival hyperemia and excess lacrimation. A single triple‐freeze cryotherapy treatment eliminated distichiae in 195/234 (83%) eyes at a mean follow‐up of 4 months (2 weeks to 10 years). Minor recurrence of distichiae in previously treated regions was observed in 39/234 (17%) eyes. Repeat cryotherapy was required in 25/234 (11%) eyes, with the remaining eyes asymptomatic. The two most common postoperative complications were mild to moderate eyelid swelling in all eyes immediately following surgery and eyelid margin depigmentation in 59/234 eyes (25%) between two and 4 weeks postoperatively, both of which were temporary.This cryotherapy technique for treating canine distichiasis is relatively simple and safe to perform, has a high success rate and a low recorded complication rate, but would benefit from further assessment of any potential detrimental effects on qualitative tear film components. [ABSTRACT FROM AUTHOR]

Waste cold energy generated from liquid nitrogen vaporization is usually abandoned when the gas supply system is pre-designed without cold integration. This study aims to investigate the potential for energy savings in a chiller system through the integration of waste cold recovery with thermal energy storage. The cold waste recovery system captures the waste cold generated during the operation of the liquid bulk nitrogen system and transfers it to a thermal energy storage system. This stored energy can then be utilized to supplement the chiller system during the targeted periods of peak demand, reducing its load and increasing its efficiency. A time-based cascade analysis, i.e., Cold Energy System Cascade Analysis (CESCA), is developed to determine the maximum peak shave load with the minimum capacity of the TES for liquified nitrogen (LN2) cold energy recovery system for a given peak shaving duration. The proposed methodology is applied to 3 cases, with different peak shaving durations, to examine the impacts of peak shaving duration on the design of the LN2 cold energy recovery system. [ABSTRACT FROM AUTHOR]

On the basis of the weakly compressible assumption, large-eddy simulation of a high-speed centrifugal pump is performed at a rotational speed of 9685 r/min and flow rate of approximately quarter load (0.23 Qd). Three cryogenic media, namely, liquid methane (MM), liquid nitrogen (MN), and liquid oxygen (MO), are used. Results show that many of the internal flow characteristics derived and validated for normal-temperature water still hold for cryogenic media. Pump efficiency, maximum density deviation, and total entropy generation rate increase with the increase in the reference density. The dominant frequencies of the pressure spectrum are 12 and 6 times the rotation frequency and insensitive to the cryogenic media. The average amplitude of the first-order dominant frequency between MN and MO deviates from that of MM by approximately 10 %. The maximum deviations of the average amplitudes of second-order dominant and axial frequencies are 34.9 % and 32.3 %, respectively. The variation in standard deviation exceeds 40 % for all cryogenic media. [ABSTRACT FROM AUTHOR]

Liquid nitrogen (LN2) fracturing technology is a novel waterless fracturing technology that has significant potential for application in the development of coalbed methane. However, the changes in the microstructure after coal samples are treated with LN2 freeze thaw are poorly understood. Therefore, a combination of mercury intrusion porosimetry and micro-computed tomography (micro CT) was employed to investigate the evolution of pore and fracture structure of coal samples treated with LN2. The experimental results showed that the pore volume and average pore size of coal samples increase after LN2 freeze thaw. After 12 freeze thaw cycles, the change in pore volume of micropores and minipores of coal samples was not significant, while the pore volume of mesopores and macropores increased significantly before LN2 freeze thaw. The specific surface area of the pores in different size ranges of coal samples increases with the increase in the number of LN2 freeze thaw cycles; the structure of micropores and miniopores were damaged by thermal stress and frost heave force during LN2 freeze thaw; and the pore size gradually increases to form mesopores and macropores. Micro-CT images of coal samples after LN2 freeze thaw indicated the primary fractures of coal sample expanded and generated a large number of secondary fractures. The primary and secondary fractures are interconnected and ultimately form penetrated fracture enhancing the connectivity of fractures, enhancing the connectivity of the fracture structure. The key finding study is expected to provide a theoretical basis for LN2 fracturing. [ABSTRACT FROM AUTHOR]

This work examined the efficacy of liquid nitrogen (LN2) both in coal fracturing, focusing on two different processes: freezing time (FT) and freezing–thawing cycle (FTC), for both dry and water-saturated specimens. Uniaxial compressive strength (UCS) with acoustic emission measurements, hardness, and modulus measurements by nanoindentation, and scanning electron microscope (SEM) imaging were conducted to comparatively analyze the cryogenic treatment efficacy of coal rocks. The outcomes indicated that in all freezing–thawing processes, water-saturated specimens have lower UCS values compared to dry ones. On the other hand, in freezing time process, water-saturated experiments have larger UCS values compared to dry ones. Moreover, it is noticed that FT experiments have greater UCS values than FTC experiments in both dry and water-saturated experiments. The hardness and reduced modulus change augment for both water-saturated and dry specimens, but in water-saturated ones, there is a sharp upward trend indicating that hardness decreases more as LN2 treatment increases. From SEM observation, it is noticed that new fractures were created, and sections of preexisting crevices expand creating fracture networks. Due to the frost force resulting from LN2 treatment, the consolidation forces among coal particles are compromised, thus creating new fractures. [ABSTRACT FROM AUTHOR]

Iron-doped binary chalcogenide crystals are very promising for tunable solid-state lasers operating over the 3~5 μm spectral range. Fe: ZnSe is one of the most important gain crystals with the obvious advantages of material characteristics and conversion efficiency. By adjusting the output mode of the pump source, an Fe: ZnSe laser can operate in two modes at liquid nitrogen temperatures: continuous wave (CW) and pulse output. In terms of CW output, the Fe: ZnSe laser obtained a maximum 2.63 W continuous power output which was confined to the power of the pump source. An optical-to-optical efficiency of 47.05% was acquired. Direct electrical modulation was applied to the pump source. The highest average power of the quasi-CW laser, whose central wavelength is 4.02 μm, has a value of 253 mW with an optical-to-optical efficiency of 42.88% and a full width at half maximum (FWHM) of 23 nm when the pulse frequency is 100 Hz of 10% duty factor. The output waveform is consistent with the modulation waveform applied to the pump source. We report to the first of our knowledge an electrically modulated quasi-CW Fe: ZnSe laser in the pulse regime, equipped with features of compactness in structure, ignoring additional modulators, convenience in control, high efficiency, and sustainable operation, of great interest for solving numerous scientific and applied problems. [ABSTRACT FROM AUTHOR]

NH2-MIL-125(Ti) is a Ti-MOFs (MOFs: metal-organic frameworks) with high adsorption properties and is therefore widely used for wastewater purification. However, the powdered MOF material suffers from the disadvantages of being difficult to separate and being potentially wasted due to easy agglomeration, which limits its application in practical applications. Here, a mesoporous Ti-MOF/polymer (PEG, PVA, and PAM) monolithic material was prepared by freeze casting in liquid nitrogen (-196 C) as an adsorbent for wastewater remediation. The composites could be easily picked up with tweezers and used for recovery tests. Characterization results such as XRD, BET, FT-IR, and SEM proved the successful synthesis of Ti-MOF/polymer. Adsorption tests using 100 mg/L methylene blue (MB) simulated wastewater showed that the Ti-MOF/PEG monolithic material had the best adsorption capacity. The order of adsorption was Ti-MOF@PEG10 (747.4 mg/g) > Ti-MOF@PVA10 (687.4 mg/g) > Ti-MOF@PAM10 (633.7 mg/g) > NH2-MIL-125(Ti) (571.4 mg/g). The effects of polymer dosage, different pollutants (methylene blue, methyl orange, indigo, actual textile wastewater), pH, anions, and cations on the adsorption effect of Ti-MOF/polymer were also investigated. It was demonstrated that all the above pollutants were well adsorbed by this Ti-MOF/polymer in the pH range 3-9. The adsorption isotherms and kinetic data are fully consistent with the Langmuir and pseudo-secondary models. This suggests that the adsorption between the pollutant and the adsorbent is a chemical interaction. Thermodynamic studies indicate that the adsorption process is exothermic and spontaneous. This work provides the potential methods to fabricate Ti-MOF/polymer monolith to avoid the pollution from powdery adsorbents that could be practical applications. [ABSTRACT FROM AUTHOR]

This study conducted a triaxial stress cycle loading–unloading experiment on anthracite coal samples to investigate the effect of different cycle numbers of liquid nitrogen cold dips (LNCDs) on the permeability characteristics of coal bodies under repeated loading–unloading conditions. The permeability of anthracite coal samples treated by LNCD and repeated loading–unloading was enhanced by 2–4 times, and the permeability evolution patterns of LNCD-damaged samples for different numbers of loading–unloading cycles were obtained. To evaluate the permeability enhancement effect of coal samples under single and multiple loading–unloading cycles, the permeability enhancement efficiency index and the LNCD influence coefficient were determined, indicating that the compound effect of LNCD treatment and repetitive stress loading–unloading significantly increased the coal's permeability. The greater the number of liquid nitrogen fracturing is, the higher the permeability of coal samples is under repetitive loading–unloading conditions. LNCD treatment advanced the transition point of coal samples from the compaction state to the enhanced permeability state. The composite repeated loading–unloading-LNCD treatment fracture was subdivided into four stages according to the internal structural changes of the coal body. The model of the composite fracture of the coal seam under the LNCD cycles and loading–unloading was constructed and experimentally validated. [ABSTRACT FROM AUTHOR]

The blooms caused by eutrophication have a serious impact on the water environment. The method of removing algae from eutrophication by microorganisms has a broad prospect. In this study, a strain of algaeclytic bacteria Serratia sp., isolated in the laboratory, was added into the algal fluids of cyanobacteria (Aphanizomenon flosaquae) and green algal (Scenedesmus quadricauda) commonly found in eutrophic water respectively. The changes of algal biomass, Chl-a, pH, total nitrogen and total phosphorus in the algal fluids were monitored, and the algaeclytic products were analyzed by spectroscopic technology. The results showed that the algaeclytic bacteria Serratia sp. had better algaeclytic effect on both species, and the higher the concentration, the better the algae-soluble effect. The removal rates of Chl-a in the experimental group with the addition of protobacterial solution were 64.3% and 85.1% respectively, and the algal cell density decreased by 71.4% and 83.9% respectively. The total nitrogen in algal liquid decreased by 17.84 mg/L and 10.82 mg/L, and the total phosphorus decreased by 7.75 mg/L and 5.68 mg/L, respectively. The total nitrogen removal effect was better. It was preliminatively concluded that the algaeclytic products contained N-H, O=N-O- (-NO2), C-H, C-N, C-O, CH2 and other bonds. Combined with the three-dimensional fluorescence scanning results, it was preliminatively concluded that the algaeclytic products were tryptophan-like substances and fumeric-acid like substances. [ABSTRACT FROM AUTHOR]

Purpose: Cancer vaccine (CV) has thrived as a promising tool for cancer prevention and treatment. However, how to maintain the integrity and diversity of individualized vaccine antigens and activate the adaptive immune system is still challenging. Methods: Herein, a preventive and therapeutic vaccine platform for in situ effective multi-model synergistic therapy is developed. In our study, we process B16F10 cells by liquid nitrogen frozen (LNF) to obtain LNF cells, the characterization of LNF cells were conducted. Moreover, the anti-tumor effect and immune activation ability were studied, and the role as a CV were investigated. Results: The LNF cells preserve intact cellular structure and tumor-associated self-antigen gp100. Moreover, LNF cells have the ability of loading and releasing doxorubicin (DOX). Except for the anti-tumor effect of chemotherapy brought by DOX, the LNF cells can promote the maturation of dendritic cells (DCs) and induce immune response by activating CD4+ and CD8+ T cells, particularly with the existence of adjuvant, R848. Specifically, the CD8+ T cells of mice in LNF-DOX/R848 group are 6 times of that in PBS group in tumor microenvironment, and twice in spleen. Therefore, LNF cells can also be utilized as a CV. Vaccination with LNF/R848 cells effectively suppress the tumor growth in mice by fivefold as compared to the control group. Conclusion: In this work, we obtain the LNF cells with a simple procedure. The LNF cells not only provides a tumor cells-based multi-modal system for cancer therapy but inspires new insights into future development of individualized CVs strategies. This study processes live B16F10 cells by liquid nitrogen frozen to obtain LNF cells, which preserve cell integrity and homologous targeting ability. The LNF cells can load and deliver drug and can serve as tumor vaccine. Results demonstrated the LNF cells have effective prophylactic ability, and ideal anti-tumor ability with the loaded drug and adjuvant. [ABSTRACT FROM AUTHOR]

As novel stress‐sensing materials, the reported mechanoluminescence (ML) phosphors work only at or above room temperature. Herein, the ML response to low temperatures (77 K) is extended by employing ultra‐shallow traps. Strong ML stimulated by handwriting force followed by persistent luminescence is observed in BaSi2O2N2:Eu2+ (BSON) at 77 K. The UV pre‐irradiated BSON can still keep the characteristics of ML with 45% intensity after 300 min. Abundant ultra‐shallow traps with depth of ≈0.19 eV are found and revealed to be responsible for the low‐temperature ML and persistent luminescence. Manipulation of the ultra‐shallow traps is realized by doping Ge, Er, and Ce ions in BSON, leading to significant ML enhancement at 77 K. Together with ML, the ultra‐shallow traps also exhibit force memory ability to replicate the pre‐applied force pattern simply by afterglow. The finding advances the state‐of‐the‐art in force sensing under low temperature conditions. [ABSTRACT FROM AUTHOR]

Ceramic aerogels are highly efficient, lightweight, and chemically stable thermal insulation materials but their application is hindered by their brittleness and low strength. Flexible nanostructure-assembled compressible aerogels have been developed to overcome the brittleness but they still show low strength, leading to insufficient load-bearing capacity. Here we designed and fabricated a laminated SiC-SiOx nanowire aerogel that exhibits reversible compressibility, recoverable buckling deformation, ductile tensile deformation, and simultaneous high strength of up to an order of magnitude larger than other ceramic aerogels. The aerogel also shows good thermal stability ranging from −196 °C in liquid nitrogen to above 1200 °C in butane blow torch, and good thermal insulation performance with a thermal conductivity of 39.3 ± 0.4 mW m−1 K−1. These integrated properties make the aerogel a promising candidate for mechanically robust and highly efficient flexible thermal insulation materials. Mechanically robust, flexible and thermally insulating ceramic aerogels are challenging to obtain due to the conflicting nature of these properties. Here the authors resolved these contradictions and developed a strong yet flexible aerogel, for application in extreme conditions, by laminated structure design. [ABSTRACT FROM AUTHOR]

Turbopumps in reusable and low-cost liquid rocket engines require compact and simple hydrostatic (i.e., externally pressurized) bearings to support large static and dynamic loads at high shaft speeds with no bearing DN (diameter in millimeters times rpm) life limitation. Hydrostatic bearings are one of the key mechanical components for cryogenic turbopumps to improve their reliability and reusability. Hydrostatic bearings offer significantly enhanced durability with very low friction and wear while providing accurate rotor positioning as well as large load and static stiffness characteristics even working with low-viscosity liquids. This work measures static load characteristics of hydrostatic journal bearings in air (25 °C), water (from 25 °C to 70 °C), and liquid nitrogen (-197 °C). Air, water, and liquid nitrogen are used as test fluids for the test bearing to evaluate the effects of fluid properties and temperatures on the bearing performance. A complete set of applied static load, bearing eccentricity, and bearing supply pressure for each test fluid (i.e., air, water, and liquid nitrogen) is presented for the test hydrostatic bearing. Measurements show that the applied static load on the test bearing significantly affects the recorded journal eccentricity ratio, bearing flow rate, and bearing static stiffnesses. Predictions are in good agreement with measurements. The predictable performance of hydrostatic journal bearings in air, water, and liquid nitrogen can further their application in various cryogenic turbopumps for liquid rocket engines. [ABSTRACT FROM AUTHOR]

The needle‐based biopsy procedure is common in cancer detection and patient‐specific targeted therapy, wherein a tissue sample from the potential diseased site is acquired and frozen instantly with the help of a coolant medium. While liquid nitrogen (LN2) is the most widely used coolant for preserving the acquired sample and performing biopsy tests on the same at a later time, cold ischemia leads to inevitable cell degradation beyond a threshold time. In an effort to circumvent this challenge, here we aim to put forward the concept of an integrated biopsy sample acquisition and cryotherapy procedure, by incorporating an exclusively designed cooling circuit in a conventional biopsy‐needle for freezing the sample in vivo as soon as it is acquired, while causing cryoablation in the surrounding tissues simultaneously. An enthalpy‐based approach is employed to develop a bioheat transfer model for the cryotherapy design, with illustrative simulation data presented for breast cancer. Our model is demonstrated by considering a constant LN2 cooling temperature of 77.15 K, and cooling powers ranging from 2 to 10 W. The model results elucidate procedure‐specific insights such as the thermal penetration depth and the cooling time on being subjected to the cryoablation. The cooling rates thus obtained are further assessed from the simultaneous considerations of cryopreservation and cryosurgery, deriving critical insights on tissue survival and damage for acting as a precursor to patient‐specific treatment planning. [ABSTRACT FROM AUTHOR]

Background: The use of liquid fertilizer is an effective measure to increase rice yield and nitrogen use efficiency. There has been a lack of information regarding the effects on the grain yield, biomass accumulation, and nutrient uptake in late‐season indica fragrant rice of split fertilizer application and of nitrogen management in liquid fertilizer application. Results: A 2‐year field experiment was carried out during 2019 and 2020 with two fragrant rice cultivars grown under differing fertilizer management treatments. Results showed that the fertilization treatments affected the grain yield, yield components, biomass accumulation, and nutrient accumulation significantly. The mean nitrogen recovery efficiency with liquid fertilizer management was greater than in a control treatment corresponding to a practice commonly used by farmers (H2). The effects of nitrogen metabolism enzymes in the leaves of both rice cultivars were stronger with liquid fertilizer treatments than with H2. Grain yield was positively associated with the effective panicle number, spikelets per panicle, dry matter accumulation, N and K accumulation, and the nitrogen metabolism enzymes. Conclusions: Optimized liquid fertilizer management increases biomass accumulation, nitrogen utilization efficiency, and nitrogen metabolism. It stabilizes yields and increases the economic benefits of late‐season indica fragrant rice. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The effect of small impurities of reduced graphene oxide (rGO) on microhardness of polyethylene (PЕ) and polypropylene (PP) matrices and the reaction of these nanocomposites and initial polymers on the influence of localized load in the temperature range of 77–295 K were studied. When rGO was introduced, PE practically did not change its properties, whereas the introduction of 0.3 wt% rGO into the PP matrix was accompanied by a significant increase in microhardness, especially in the room temperature range (by approximately 70%). A transition to reversible deformation was detected when the indenter impressions applied in liquid and gaseous nitrogen at temperatures below the threshold (T < 174.5 K for PP and T < 226.5 K for nanocomposite PP + 0.3 wt% rGO) were not fixed on the surface of the samples after their heating in the measuring device to room temperature. [ABSTRACT FROM AUTHOR]

The paper presents the results of metallographic analysis of the microstructure of high-alloy Uddeholm Sverker 3 steel (AISI Type D2). Cold treatment of high-alloy steels is used as a way to reduce the amount of retained austenite and, as a consequence, to stabilize the mechanical properties and dimensions of precision parts. In this work, we have used deep cold treatment by immersion in liquid nitrogen after heat treatment according to the traditional technology (quenching for primary hardness and low tempering). Exposure to liquid nitrogen has been carried out for 24 h. At the end of the exposure, the parts have been removed from liquid nitrogen and kept at room temperature until they reached room temperature. Then, the parts have been subjected to tempering at a low temperature of 170°C. The cryogenically treated sample has more noticeable fluctuations in the chemical composition and a larger amount of the carbide phase (30 and 27 vol %, respectively). Fluctuations in the chemical composition are expressed in more intense coloring of carbide particles using color etching, which indicates differences in their chemical composition. In the case of cryogenic treatment, the average specific size of carbides is less than in the absence of it. In addition, an increase in the content of ultrafine carbides is observed in the cold-treated sample, which is logically explained by their precipitation from retained austenite during its decomposition at cryogenic temperatures, decay of retained austenite and, as a result, the release of additional volumes of carbide particles. Particles formed during cryogenic treatment can be classified as ultrafine, with an average diameter of about 1 μm. [ABSTRACT FROM AUTHOR]

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Cryotherapy is commonly regarded as the primary treatment method for plantar warts. A new medical device called nitric–zinc complex solution (NZCS) has also emerged as a potential alternative for wart treatment. The main aim of this study was to analyze and compare the effectiveness of cryotherapy using liquid nitrogen and NZCS in treating plantar warts. We conducted a randomized and controlled clinical trial involving patients with plantar warts. A total of 62 patients were enrolled in the study and monitored for 12 weeks or until their warts were completely resolved. The patients received either cryotherapy or NZCS, with a maximum of six treatment applications. The cure rate was 65.5% in the group treated with cryotherapy and 56.6% in the group treated with NZCS. The average number of treatment applications required for curing warts was significantly lower in the cured group (3.28 ± 1.63) than in the group with unresolved warts (5.5 ± 1.27) (p < 0.01). Moreover, the average number of applications was lower in the cryotherapy group (3.6 ± 1.8) than in the NZCS group (4.8 ± 1.8) (p < 0.01). Based on the findings, NZCS could be considered a favorable first‐line treatment option for plantar warts. [ABSTRACT FROM AUTHOR]

The fracturing process of sandstone is inherently complex due to its loose internal structure and deformation adaptability. Liquid nitrogen pre-injection has emerged as a promising approach to damage reservoir rocks, effectively reducing fracture pressure and establishing intricate fracture networks, thus offering a potential solution for reservoir reconstruction. To unravel the fundamental mechanisms governing sandstone fracturing behaviors following liquid nitrogen pre-injection, sandstone fracturing experiments were conducted under varying durations of liquid nitrogen injection, rock temperature, and in-situ stress conditions. The experiments showcased the evolution of injection pressure and fracture characteristics under different testing conditions, complemented by electron microscope analysis to elucidate the factors driving the complex fracture characteristics of sandstone. The findings revealed a significant decrease in fracture pressure after liquid nitrogen pre-injection, accompanied by a notable increase in the complexity of the fracture network and the roughness of the fracture surface. Moreover, prolonging the duration of liquid nitrogen injection and elevating reservoir temperature further contributed to reducing fracture pressure, consequently enhancing fracture complexity and surface roughness. Conversely, the application of confining pressure amplified fracture pressure while intensifying the degree of fracturing. Notably, the investigation highlighted the increased presence of microcracks in sandstone resulting from liquid nitrogen pre-injection, facilitating fluid diffusion during fracturing and yielding lower fracture pressures, thereby enhancing the effectiveness of sandstone reservoir reformation. The research results can provide theoretical guidance for geothermal reservoir reconstruction. [ABSTRACT FROM AUTHOR]

In this study, a super-insulated pipe incorporating Multi-Layer Insulation (MLI) and vacuum is numerically analyzed to overcome the challenges faced during the transportation of cryogenic fluids like nitrogen. A super-insulated pipe incorporating an inner process pipe of SS 304 L insulated by twenty-four consecutive layers has been used. Each layer consists of aluminized mylar (as a radiation shield) and dacron netting (as a spacer material). High vacuum (10-9 torr) is applied and numerically analyzed at multiple flow rates, i.e., 250 LPH, 500 LPH and 1000 LPH. The results show a gradual increase in temperature along the flow direction from 77 K to 79 K at the most. Moreover, the temperature increases with the increase in the length of the pipe and decreases with the increase in the flow rate of LN2. [ABSTRACT FROM AUTHOR]

The pursuit of enhanced cooling and lubrication methods for machining processes that are energy-efficient, environmentally friendly, and cost-effective is receiving significant attention from both academia and industry. The reduction of CO2 emissions is closely tied to electrical and embodied energy consumption. This study introduces a novel LN2 oil-on-water (LNOoW) cooling/lubrication (lubricooling) approach for the machining of Ti-6Al-4V alloy. Machinability aspects, energy-related aspects, environmental-related aspects, and economic aspects are measured and compared. More specifically, surface quality, electrical energy, cutting forces, and tool wear were measured in machinability aspects. Similarly, specific total energy and specific cumulative Energy Demand (S_CED), specific carbon emission, and production costs were measured to investigate the energy and environmental and economic aspects, respectively. The LNOoW provided the best machinability results compared with other approaches. Result found that LNOoW produced 37.5% better surface quality, removed 159.17% more material, and reduced 50.56% specific cutting energy and 53.63% specific costs as compared to traditional dry cutting conditions. The 39% increment in specific carbon emissions observed in the LN2 oil-on-water (LNOoW) approach in comparison to the dry-cutting method can be mitigated through the implementation of sustainable practices in the production of liquid nitrogen (LN2). The information provided in this study serves as a valuable resource for the development of environmentally friendly machining processes. The study also helps get the sustainable development goals (SDGs) of the United Nations. [ABSTRACT FROM AUTHOR]

Introduction. Pyogenic granuloma (PG) is a common condition characterized by the appearance of a small raspberry-like vascular growth that may appear on any part of the skin. PG usually occurs secondary to acute or chronic trauma. The primary treatment for PG is noninvasive therapy. In refractory cases, surgical resection is an alternative. Superficial radiation therapy system (SRT-100) is a new technology that uses low-energy radiotherapy to treat nonmelanoma skin cancers. SRT may also be used for the treatment of patients with PG who are unwilling to undergo surgery. Case Presentation. A 27-year-old woman presented with a recurrent neoplasm in the middle finger of the left hand after surgical resection. She refused to undergo reoperation or other aggressive options such as electrocautery or liquid nitrogen cryotherapy, so we prescribed only superficial radiotherapy (SRT-100) alone, with a total dose of 14 Gy in four fractions. Conclusion. The neoplasm gradually flattened after treatment with 14 Gy in four fractions and disappeared completely 3 months after completion of treatment. [ABSTRACT FROM AUTHOR]

The utilization of liquid nitrogen as a sustainable and water-free fracturing medium exhibits immense promise in engineering applications. In this investigation, Brazilian split tests and acoustic emission tests were conducted to explore the impact of liquid nitrogen cooling on the internal structure and mechanical properties of rock specimens. To examine the influence of liquid nitrogen cooling on the tensile strength of rocks, displacement-load curves were obtained from samples subjected to varying cycles of high-temperature liquid nitrogen cooling using Brazilian split tests. Acoustic emission experiments were conducted to investigate the characteristics of granite samples exposed to various cycles of high-temperature liquid nitrogen cooling. Based on these findings, the impact of liquid nitrogen cooling on the internal structure of rock masses was analyzed. The findings of this study demonstrate that high-temperature liquid nitrogen thermal treatment significantly modifies the microscopic structure and mechanical properties of rocks, with potential implications for overall stability and reliability. Notably, an observable decline in tensile strength was observed as the number of cycles of high-temperature liquid nitrogen treatment increased. These findings underscore the substantial impact of liquid nitrogen cooling on the behavior of rocks. High-temperature liquid nitrogen treatment effectively promotes the generation of microcracks within rocks, thereby increasing their permeability. During the experiment, granite specimens primarily exhibited shear-type fractures when subjected to high-temperature freeze-thaw cycles induced by liquid nitrogen. [ABSTRACT FROM AUTHOR]

In microbiome studies, fecal and oral samples are stored and processed in different ways, which could affect the observed microbiome composition. In this study, we compared storage and processing methods applied to samples prior to DNA extraction to determine how each affected microbial community diversity as assessed by 16S rRNA gene sequencing. We collected dental swabs, saliva, and fecal samples from 10 individuals, with three technical replicates per condition. We assessed four methods of storing and processing fecal samples prior to DNA extraction. We also compared different fractions of thawed saliva and dental samples to fresh samples. We found that lyophilized fecal samples, fresh whole saliva samples, and the supernatant fraction of thawed dental samples had the highest levels of alpha diversity. The supernatant fraction of thawed saliva samples had the second highest evenness compared to fresh saliva samples. Then, we investigated the differences in observed community composition at the domain and phylum levels and identified the amplicon sequence variants (ASVs) that significantly differed in relative abundance between the conditions. Lyophilized fecal samples had a greater prevalence of Archaea as well as a greater ratio of Firmicutes to Bacteroidetes compared to the other conditions. Our results provide practical considerations not only for the selection of storage and processing methods but also for comparing results across studies. Differences in processing and storage methods could be a confounding factor influencing the presence, absence, or differential abundance of microbes reported in conflicting studies. [ABSTRACT FROM AUTHOR]

In recent years, biotechnology has had a significant impact on the aquaculture industry, particularly in the field of breeding. Molecular selection breeding has emerged as a novel approach to breeding. Reducing the cost of genetic information for individuals with desirable traits after breeding has become an important research direction. Cryopreservation technology allows bypassing time and space constraints in genetic breeding, simplifying broodstock management. This study presents a detailed cryopreservation method for black seabream sperm, evaluating extender type, glucose concentration, cryoprotectant type and concentration, sperm-dilution ratio, and cooling protocols. Sperm motility parameters were analyzed using computer-assisted sperm analysis (CASA) before and after two days of freezing. This involved using an RS solution with a glucose concentration of 15 g/L and adding a 5% final concentration of EG as the sperm cryoprotectant. After mixing the sperm and solution at a ratio of 1:2, we subjected it to 5 min fumigation at 5 cm above the liquid nitrogen surface before plunging it into the nitrogen. Sperm motility reached 85.46 ± 7.32% after two days. Various enzymatic activities showed changes over 20 days post-cryopreservation. This improved cryopreservation protocol for black seabream sperm is beneficial for genetic breeding and reproduction and provides reference for studying the cryodamage mechanisms of black seabream sperm. • A systematic cryopreservation protocol for blackhead seabream sperm was developed. • Enzyme and CASA observations reveal sperm physiological changes pre/post-freezing. • Providing a new approach to preserve superior individual genetic information. [ABSTRACT FROM AUTHOR]

Measures of fecal bacterial abundance and taxonomic composition are commonly used as proxies for gut microbial diversity in studies of free-living mammals. Because methods of sample collection and storage may affect measures of bacterial diversity, we evaluated the effects of several procedures on fecal bacterial diversity in a free-living population of California ground squirrels (Otospermophilus beecheyi). Replicate fecal samples from 12 adult female squirrels were collected either from the soil beneath traps in which individuals had been captured or from tubs placed under squirrels during handling. Samples were then either frozen immediately in liquid nitrogen or stored on ice for several hours before being transferred to a −80°C freezer. Sequencing of the bacterial 16s RNA gene revealed no differences among methods with regard to sequence read depth (number of sequences recovered per animal) or alpha (within-individual) diversity of bacterial taxa. While our collection-storage procedures had a significant effect on one of the metrics of beta (among-individual) bacterial diversity examined, this effect was small compared to that of individual identity. Date of sample collection affected alpha and beta diversity; samples collected only 1 week apart differed significantly in bacterial diversity. Overall, these findings suggest that the collection and storage methods employed yield generally comparable information and are capable of capturing potentially important patterns of fecal bacterial composition and diversity in free-living mammals. [ABSTRACT FROM AUTHOR]

Cryogenic cavitation exhibits complexities primarily represented by the coupled interactions of thermodynamic effects, vortices, and cavities during the cavitation process. To further investigate this coupling mechanism, this study employed the DDES turbulence model and Sauer–Schnerr cavitation model to perform unsteady numerical simulations of liquid nitrogen cavitation flow around the NACA0015 Hydrofoil. Numerical validation of the model utilized a symmetrical Hord hydrofoil. The results reveal that the upstream development of the recirculation flow under inverse pressure gradients is the fundamental cause of the detachment in the primary cavitation region. At a cavitation number of 0.616, thermodynamic effects noticeably suppress the formation of cavities and alter the range of adverse pressure gradients, consequently influencing the detachment behavior in the primary cavitation region. [ABSTRACT FROM AUTHOR]

Objective In order to reduce the equipment investment and energy loss of extracting helium from natural gas by using a single low-temperature method, a new natural gas helium extraction combined with LNG production process is provided. Methods Based on the data of low helium feed gas from a domestic gas field, the characteristics and adaptability of this new process have been simulated and analyzed, and the refrigeration cycle of the mixed refrigerant has been optimized by genetic algorithm. Results（1） Characteristic analysis shows that the lower the temperature before throttling and the higher the throttling pressure, the better the concentration effect of the flash tank on helium gas. At the same time, nitrogen products with a purity of 99.9 mol% can be produced, and liquid nitrogen products can be produced by itself;（2） The new process has strong adaptability to changes in nitrogen and helium content in the feed gas, as well as the pressure of the feed gas. The higher the feed gas pressure and the lower the nitrogen and helium content, the lower the compressor shaft power;（3） Through analysis of characteristics and adaptability, as well as optimization of mixed refrigerant refrigeration process parameters, it can be obtained that the temperature before throttling in the flash tank is-150 ℃, the throttling pressure is 350 kPa, the pressure of the helium extraction tower is 3 200 kPa, the number of plates in both the denitrification and helium extraction towers is 12,the optimal boost pressures for the first and second stages of the mixed refrigerant compressor are 1 341 kPa and 2 767 kPa, respectively, and the circulation rate of the mixed refrigerant is 1 722.67 kmol/h, the total compressor shaft power is 3 765 kW, the cooling water consumption is 6 474 t/d, the comprehensive energy consumption and unit energy consumption are 1 097 216.00 MJ/d and 3.66 MJ/m~3, respectively. Conclusions The helium recovery rate is more than 98%, and the crude helium purity is higher than 70 mol% for the new process. It can produce refrigerants by itself and obtain high-purity nitrogen and liquid nitrogen products, and has good adaptability to the gas quality conditions of the feed gas [ABSTRACT FROM AUTHOR]

Liquid nitrogen is a widely used cryogenic fluid in various industrial and scientific applications. Film boiling is inevitable when a hot surface is exposed to a cryogenic fluid like liquid nitrogen. This mode of boiling can affect the heat transfer rate and cooling efficiency of the process. The present study investigated the effect of operating pressure on film boiling characteristics of liquid nitrogen using continuum-based numerical simulations. Simulations were performed at atmospheric, intermediate, and near-critical pressures using a coupled level-set and volume of fluid method of interface tracking. Bubble dynamics and heat flux variations were examined at different degrees of wall superheat. The results show that the pressure condition significantly affects the bubble dynamics and boiling of liquid nitrogen. At higher pressure, the specific heat of the vapor phase increases, resulting in a higher heat transfer rate. It was also noted that at high levels of superheat, the bubbles detach from the heating surface faster, resulting in a higher transfer of heat. The effect of pressure on the number of bubble formation sites was also investigated. The simulations also reveal that the local thermodynamic conditions, such as pressure, temperature, and vapor concentration, significantly influence the bubble size. [ABSTRACT FROM AUTHOR]

Liquid nitrogen fracturing has emerged as a promising technique in fluid fracturing, providing significant advantages for the utilization and development of geothermal energy. Similarly to hydraulic fracturing in reservoirs, liquid nitrogen fracturing entails a common challenge of fluid–rock interaction, encompassing the permeation and diffusion processes of fluids within rock pores and fractures. Geomechanical analysis plays a crucial role in evaluating the transfer and diffusion capabilities of fluids within rocks, enabling the prediction of fracturing outcomes and fracture network development. This technique is particularly advantageous for facilitating heat exchange with hot dry rocks and inducing fractures within rock formations. The primary objective of this study is to examine the effects of liquid nitrogen fracturing on hot dry rocks, focusing specifically on granite specimens. The experimental design comprises two sets of granite samples to explore the impact of liquid nitrogen cooling cycles on the mode I fracture characteristics, acoustic emission features, and rock burst tendency of granite. By examining the mechanical properties, acoustic emission features, and rock burst tendencies under different cycling conditions, the effectiveness of liquid nitrogen fracturing technology is revealed. The results indicate that: (1) The ultimate load-bearing capacity of the samples gradually decreases with an increase in the number of cycling times. (2) The analysis of acoustic emission signals reveals a progressive increase in the cumulative energy of the samples with cycling times, indicating that cycling stimulates the release of stored energy within the samples. (3) After undergoing various cycling treatments, the granite surface becomes rougher, exhibiting increased porosity and notable mineral particle detachment. These results suggest that the cyclic application of high-temperature heating and liquid nitrogen cooling promotes the formation of internal fractures in granite. This phenomenon is believed to be influenced by the inherent heterogeneity and expansion–contraction of internal particles. Furthermore, a detailed analysis of the morphological sections provides insights into the structural changes induced by liquid nitrogen fracturing in granite samples. [ABSTRACT FROM AUTHOR]

The following article proposes the design of a bi-centrifugal atomizer that allows the interaction of sprays from two fluids (water and liquid nitrogen). The liquid nitrogen (LN2) is below −195.8 °C, a temperature low enough for the nitrogen, upon contact with the atomized water, to cause heat loss and bring it to its freezing point. The objective is to convert the water droplets present in the spray into ice. Upon falling, the ice particles can be dispersed, covering the largest possible area of the seafood products intended for cold preservation. All these phenomena related to the interaction of two fluids and heat exchange are due to the bi-centrifugal atomizer, which positions the two centrifugal atomizers concentrically, resulting in the inevitable collision of the two sprays. Each of these atomizers will be designed using a mathematical model and CFDs tools. The latter will provide a better study of the flow behavior of both fluids inside and outside the bi-centrifugal atomizer. Hence, the objective revolves around confirming the validity of the mathematical model through a comparison with numerical simulation data. This comparison establishes a strong correlation (with a maximum variance of 1.94% for the water atomizer and 10% for the LN2 atomizer), thereby ensuring precise manufacturing specifications for the atomizers. It is important to highlight that, in order to achieve the enhanced resolution and comprehension of the fluid both inside and outside the duplex atomizer, two types of meshes were utilized, ensuring the utilization of the optimal option. Similarly, the aforementioned meshes were generated using two distinct software platforms, namely ANSYS Meshing (tetrahedral mesh) and ANSYS ICEM (hexahedral mesh), to facilitate a comparative analysis of the mesh quality obtained. This comprehension facilitated the observation of water temperature during its interaction with liquid nitrogen, ultimately ensuring the freezing of water droplets at the atomizer's outlet. This objective aligns seamlessly with the primary goal of this study, which revolves around the preservation of seafood products through cold techniques. This particular attribute holds potential for various applications, including cooling processes for food products. [ABSTRACT FROM AUTHOR]

Copyright of Modern Food Science & Technology is the property of Editorial Office of Modern Food Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As an anhydrous fracturing method, liquid nitrogen jet fracturing technology is expected to become an efficient development method for shale gas resources. In order to explore the influence of the pressurization effect in the liquid nitrogen jet channel, the flow field in the perforation tunnel during the liquid nitrogen jet fracturing process was simulated by computational fluid dynamics, and the complex flow mechanism of liquid nitrogen in the perforation tunnel was analyzed. The pressurization effect of liquid nitrogen jet and water jet fracturing was compared, and the influence of various parameters on the pressurization effect of liquid nitrogen jet fracturing was studied. The research results indicate that under the same conditions, liquid nitrogen jets have a pressurization effect comparable to water jets, and the difference between the pressurization values of the liquid nitrogen jet and the water jet in the perforation tunnel is not more than 0.4 MPa under different nozzle pressure drop conditions. The larger the nozzle pressure drop and nozzle diameter, the greater the pressure increase value in the perforation tunnel of liquid nitrogen jet fracturing, which decreases with the increase in casing hole diameter. Further analysis shows that the pressurization effect is most affected by the two parameters of casing hole diameter and nozzle diameter. The essential reason for its influence on the pressurization value is the squeezing effect of the jet on the perforation tunnel fluid and the sealing effect of the shrinking part of the perforation tunnel on the backflow. The ambient pressure, the temperature of liquid nitrogen, and the diameter of the wellbore have no obvious effect on the pressurization effect. Therefore, through the reasonable combination of casing hole diameter and nozzle diameter, the sealing effect of the contraction part of the perforation tunnel on the fluid and the squeezing effect on the fluid in the perforation tunnel will be affected, which will significantly improve the pressurization effect of the liquid nitrogen jet in the perforation tunnel. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of high-temperature treatment and liquid nitrogen quenching on the strength characteristics and ultrasonic pulse velocity of granite and sandstone were detailed in this study. The samples were subject to varying duration of furnace treatment and quenching in liquid nitrogen (LIN) and measured for their strength properties and pulse velocity at normal temperature. The results indicate that the treatment can reduce the mechanical strength and pulse velocity of granite and sandstone. The results reveal that rock pre-treatments illustrate a declining tendency in both strength properties of rock specimens. Granite samples indicate a reduction in UCS of 57% and BTS of 71%, while LIN tensile samples also showed decreases in 75% of UCS and 63% of BTS. Similarly, the strength properties are decreased with the duration of pre-treatment for sandstone. The influence of both the treatments on UPV and scanning electron microscope (SEM) tests of rock has been investigated in detail. In comparison to untreated samples, very low pulse velocity values have been observed in the treated rock samples. [ABSTRACT FROM AUTHOR]

In cryogenic fracturing, a rock surface exposed to cryogenic fluids undergoes a large thermal gradient, and the resultant local tensile stress overcomes rock strength and initiates fractures. This study investigates the development of cracks generated from the cryogenic treatment of a borehole under no external confining stress on specimens. The experiments were performed on transparent PMMA specimens to observe fracture proliferation around boreholes. Liquid nitrogen was flowed through the boreholes to cool the borehole surface. The results show that initial fracture growth is characterized by abrupt starts and stops, and as the fracture propagates outward, the growth appears more continuous. In an early stage, horizontal/radial fractures and vertical fractures are the defining patterns. Horizontal fractures tend to be separated by a specific exclusion distance (i.e., spacing between cracks). While distinct horizontal/vertical fractures and exclusion distance manifest themselves at an early stage, fractures resulting from fracture interactions and curvatures can develop into complex shapes at later stages. Cryogenic thermal loading induces distinctively curved fractures. The tendency of curvature may prevent greater penetration. An increase in the borehole pressure during liquid nitrogen flow, however, can lessen fracture tortu-osity and facilitate radial propagation. A high flow pressure and rate are also advantageous in that they accelerate cooling and fracture propagation.

Epitaxially grown superconductor/dielectric/superconductor trilayers have the potential to form high-performance superconducting quantum devices and may even allow scalable superconducting quantum computing with low-surface-area qubits such as the merged-element transmon. In this work, we measure the power-independent loss and two-level-state (TLS) loss of epitaxial, wafer-bonded, and substrate-removed Al/GaAs/Al trilayers by measuring lumped element superconducting microwave resonators at millikelvin temperatures and down to single-photon powers. The power-independent loss of the device is (4.8 ± 0.1) × 10 − 5 , and the resonator-induced intrinsic TLS loss is (6.4 ± 0.2) × 10 − 5 . Dielectric loss extraction is used to determine a lower bound of the intrinsic TLS loss of the trilayer of 7.2 × 10 − 5 . The unusually high power-independent loss is attributed to GaAs's intrinsic piezoelectricity. [ABSTRACT FROM AUTHOR]

In order to study the influence of liquid nitrogen cracking time on mechanical properties and permeability of coal samples, the independently developed WYS-800 triaxial gas seepage test device and acoustic emission detection system were used to conduct triaxial mechanical seepage tests on four groups of coal samples treated with different cracking time and collect acoustic emission signals. The mechanical properties and permeability of coal samples in triaxial mechanical seepage experiment were analyzed, and the characteristics of acoustic emission signals were described. Based on boiling heat transfer theory, one-dimensional cylinder heat conduction theory and thermal stress theory, the cracking mechanism was analyzed, and the thermal stress under different cracking time was calculated. The relationship between average temperature drop, average thermal stress, initial permeability and cracking time was revealed by data fitting. The results show that: ① Liquid nitrogen fracturing time have different influence on the mechanical properties of coal samples, the compressive strength and elastic modulus with the increase of the crack time shows the tendency of increase with the decrease of the first, the poisson's ratio are increased after the first decreases, coal sample triaxial loading when the axial stress and axial strain curve of the periodic evolution has obvious difference, associated with the change of mechanical parameters. ② The permeability of coal samples with different cracking time changes in u-shape during the triaxial loading process. The initial permeability, minimum permeability and maximum permeability increase with the increase of cracking time, and the increase rate is 119.05%, 437.5% and 146.49% when the cracking time is 30min. Acoustic emission signals are not active in compaction and elastic stages, and are mainly generated in yield and failure stages. The peak value of acoustic emission ringing count of coal samples after cracking is generated near the failure point, which is more than 20000 times. ③ The film boiling heat transfer coefficient between the coal sample and liquid nitrogen is 570.4 W/(m2·K). The average temperature drop of the coal sample is related to the cracking time, and the average thermal stress and initial permeability play a leading role. The average temperature drop of the coal sample can reach 213.63 K and the average thermal stress can reach 5.85 MPa after 30 min of cracking. ④ There is a linear relationship between initial permeability and average temperature drop, and a negative exponential relationship between initial permeability and cracking time of coal samples after liquid nitrogen treatment. Changing the parameter value can be extended to other similar coal samples or actual production evaluation.

The article explores the use of indirect immunofluorescence on salt-split skin sections to diagnose bullous pemphigoid (BP) and mucous membrane pemphigoid (MMP) in patients. The study compares the sensitivity and specificity of human and monkey skin samples in detecting autoantibodies from BP and MMP patients. While human skin proved more sensitive in detecting BP autoantibodies, monkey skin showed higher sensitivity for MMP autoantibodies due to differences in antigen expression. The study suggests carefully selecting the appropriate substrate to enhance the diagnostic performance of the immunofluorescence technique. [Extracted from the article]