Cryogenic Exposure Research Articles

Protective coating of steel structures from cryogenic effects based on cement slabs

Purpose of research. The use of liquefied natural gas (LNG) as an energy carrier is expanding annually. Therefore, the purpose of this article is to analyze the regulatory requirements for the structure protection from the cryogenic liquid spill such as LNG. The article also evaluates the ability of fireprotective materials to resist not only hightemperature influences, but also low-temperature ones.Methods. The article discusses the main methods of material testings to counteract the cryogenic liquid spill and the possibility of using fireprotective products as cryoprotective materials. The results of testing the protective system manufactured by LLC "PROSASK" are shown and analyzed. The object of the study is a fire-retardant structural system consisting of "PROSASK Fire Panel" plates. The protective system consists of two layers of flame-retardant plates "PROSASK Fire Panel" with a non-flammable membrane " in the middle, manufactured by LLC "PROSASK". And the subject of the research is the cryoprotective function of this system.Results. The average temperature of the sample after 60 minutes cryogenic exposure was - 53 °C, conclusions were drawn about the expediency of conducting successive tests for low-temperature and fire exposure due to the high probability of fire after the cryogenic liquid spill in the presence of a flame source.Conclusion. The article shows and analyzes the test results of the protective system manufactured by LLC "PROSASK". With the correct choice of steel grade (including the requirement for impact strength) of load-bearing structures of oil and gas facilities, it can be concluded that structures protected by a structural fire protection system with PROSASK Firepanel plates are operable after an hour of cryogenic exposure.

Pore structures and deterioration mechanism of concrete after cryogenic freeze-thaw cycles: Effects of moisture contents and aggregates

With the popularization of all-concrete liquefied natural gas (ACLNG) storage tanks, the performance of concrete after cryogenic exposure (−170 °C) has garnered significant interests from researchers. To investigate the damage mechanism of pore structures and the corresponding influencing factors, this study involved subjecting concrete with two moisture contents, namely air-dried and water-saturated to 10 cryogenic freeze-thaw cycles (CFTCs) to assess the variation laws in strengths. The mercury intrusion porosimetry (MIP), nitrogen adsorption and desorption (NAD), scanning electron microscopy (SEM), backscattered scanning electron (BSE) and low-temperature calorimeter (LTC) methods were employed to evaluate pore characteristics and the phase transition of pore water. Furthermore, pore structures were conducted using fractal dimensions based on the Zhang model and Frenkel-Halsey-Hill model. Findings indicate that there is a more pronounced reduction in strengths after 10 CFTCs in water-saturated state. Following cryogenic exposure, the porosity of paste increases from 4.97 % to 5.58 % and 7.04 %, and the porosity of mortar rises from 6.05 % to 7.20 % and 8.76 %, respectively. Aggregates in mortar contribute to more severe damage to pore structures in cryogenic circumstances, particularly capillary and macropores. The nucleation of pore water and ice contents are greatly influenced by moisture contents, and the frozen fraction is only 84.3 % in air-dried state. The destruction of gel pores is attributed to the continuous multi-order phase transition in water-saturated state. This work conducts a thorough cross-scale analysis of the pore structure in both paste and mortar, and it quantitatively evaluates the phase transition of pore water under cryogenic conditions using the LTC method. Ultimately, the influence of moisture contents and aggregates on the pore structures are evaluated, which provides deeper insights into the deterioration mechanism of concrete following cryogenic exposure.

Strengthening and embrittlement effect of cryogenic temperature on fiber reinforced geopolymer composite

Understanding the cryogenic behaviour of geopolymer composite (GPC) is essential to implement them in real structural elements at cryogenic temperatures. The paper presents a comprehensive investigation on the compressive strength, flexural behaviours, and energy absorption capability of both plain GPC and fiber-reinforced geopolymer composite (FRGPC) containing different fiber types and contents subjected to in-situ −170 °C. The results demonstrate that the compressive strength of plain GPC and FRGPC increases by 104.9 %–213.6 %, and the flexural strength increases by 73.4 %–212.5 %, exhibiting a significant cryogenic strengthening effect. Moreover, compared to flexural strength, compressive strength of GPCs displays a higher sensitivity to the cryogenic strengthening effect. The failure mode of FRGPCs changed from ductile failure to ductile-brittle failure at −170 °C, which is due to the decreased ductility induced by the cryogenic embrittlement effect. Additionally, cryogenic exposure has a greater impact on reducing the ductility of FRGPCs containing PP fibers than those with steel fibers. However, the negative effects of cryogenic embrittlement effect on ductility can be mitigated by incorporating steel fibers and increasing fiber content. The further analysis reveals that strengthening and embrittlement effect are associated with the increased cumulative energy and the sudden release of local energy, respectively. These findings contribute to the understanding of GPC performance at cryogenic temperature, which can guide the development of more resilient and durable GPC for cryogenic applications.

Analysis of damage and fracture characteristics for concrete subjected to cryogenic freeze-thaw cycles: An acoustic emission and digital image correlation study

This study examines concrete's performance under cryogenic (−170 °C) freeze-thaw cycles (CFTCs), inspired by the development of all-concrete liquefied natural gas (ACLNG) tanks. Focusing on plain concrete (PC) and concrete with 3 % volume content steel fiber (SFRC3), the impact of fibers and moisture content on concrete's damage and failure characteristics pre and post cryogenic exposure is investigated. The compressive strength variation laws of concrete before and after 10 CFTCs were summarized in air-dried and water-saturated condition. Acoustic emission (AE) and digital image correlation (DIC) techniques were employed in the study to delineate the variances in failure process and fracture characteristics attributed to cryogenic exposure. Findings indicate a decline in the compressive strength of both PC and SFRC3 post exposure, more pronounced in water-saturated condition. Post-cryogenic exposure, AE signals exhibit decreased activities. The failure process of concrete is categorized into four stages based on the trends of severity index Sr and historical index Hs, both of which diminished, reflecting reduced signal strength and rate of change. AE frequency-amplitude characteristics differs between PC and SFRC3 during failure, with significant reduction in high frequency signals in SFRC3, suggesting weakened fiber-matrix bonding and increased fracture scale. The rise in the number of shear cracks nearing failure is discerned from variations in rise angle (RA) and average frequency (AF), proposing the ratio of RA to AF equal to 15 as a precursor of concrete failure. The DIC analysis shows increased crack width and numbers in both PC and SFRC3 post exposure, along with localized spalling. SFRC3 can still effectively maintain the integrity without complete breakage despite severe cracks are generated.

Structural impact under accidental LNG release on the LNG bunkering ship: Implementation of advanced cryogenic risk analysis

The potential risk associated with the accidental release of Liquefied Natural Gas (LNG) is a notable concern during the design phase of gas-handling facilities. One of the risk is an excessive cryogenic exposure to structures or equipment, leading to hazardous situations. This study aims to introduce a novel method that implements Advanced Cryogenic Risk Analysis (ACRA) to enhance the safety of LNG bunkering ship structure in case of cryogenic flow leakage. The method involves evaluating thermal loads based on the preceding simulated LNG release scenarios using Computational Fluid Dynamics (CFD). These thermal parameters are then employed in structural analysis through the Finite Element (FE) approach.The integration of thermal data from CFD simulations into the FE model was achieved using the Random Forest algorithm. The LNG bunkering structure is represented using DH36-grade steel material. Furthermore, to accurately capture the mechanical properties of DH36 steel, cryogenic tensile tests were conducted across a temperature range from 298.15 K to 113.15 K. The resulting stress-strain data from these tests were utilized to establish a reliable material model for conducting FE analysis.This paper comprehensively presents a novel ACRA procedure by utilizing physical parameter of the gas release cosnequence such as the steel temperature profile to identify the brittle failure under the accidental gas release on the LNG bunkering ship. In addition, quantitative risk analysis (QRA) was also presented regarding the cryogenic spill hazard, to link the probability and consequence aspects of the LNG bunkering risk, particularly the results of steel temperature, stress, and strain experienced by the ship’s structure. Furthermore, the individual risk was also estimated. The implications of the findings are discussed in detail regarding the cryogenic risk, cryogenic tensile test and numerical analyses.

Системы огнезащиты стальных конструкций с цементными плитами и противопожарным барьером при криогенном и Jet-Fire воздействиях

Purpose. The article presents the outcomes of experimental studies of steel structures samples with fire protection systems based on cement binder under cryogenic and hydrocarbon Jet-Fire exposure. Methods. Experimental studies of the fire protection system for steel structures with cement slabs and a fire barrier under cryogenic exposure were carried out according to the methodology, the main provisions of which are harmonized with ISO 20088-1 “Determination of the resistance to cryogenic spillage of insulation materials - Part 1: Liquid phase”, and samples of the system fire protection tested according to the method harmonized with ISO 22899-1 “Determination of the resistance to jet fires of passive fire protection materials. Part 1: General requirements”. Findings. Tests on cryogenic impact on a fire protection system sample consisting of Prozask Firepanel slabs on a cement binder, a fire protection mat Ignis-mat SV and a fire barrier Promizol-DSH Proplate-60/5/10L, made it possible to come to the conclusion based on the results of a 60-minute exposure to hydrocarbon Jet-Fire, that the temperature on the sample on an unheated surface reached 47.73 °C; during cryogenic exposure, the temperature on the sample reached –49 °C after 53 minutes. Research application field. The outcomes obtained can be applied when planning fire protection in the field of fire safety at oil and gas facilities and in tunnel structures as well. Conclusions. It has been found out that fire-retardant boards with a cement binder are quite effective under cryogenic exposure to hydrocarbons; they also show high resistance to hydrocarbon Jet-Fire in a system with a fire barrier made of superthin basalt fiber and a fire-retardant ceramic mat.

Examination of cryogenic durability in self-consolidating concretes through mechanical and fracture mechanics approaches

Thermal shocks under extreme conditions, such as leakage in concrete-enclosed tanks, which are a popular choice for cryogenic liquid storage, may lead to undesirable effects on the structures. In this study, the effects of cyclic cryogenic exposures have been investigated using both mechanical and fracture mechanics approaches. To ensure durable concrete, self-consolidating concretes have been chosen in the mix design. While previous studies have primarily investigated the effects of a single cryogenic exposure on conventional concrete, this study focuses on repetitive exposure to cryogenic effects on self-consolidating concretes. Furthermore, the self-consolidating concretes were subjected to two different curing conditions: air curing and water curing, before cryogenic processing, in order to consider real application conditions and laboratory circumstances. After the first and fifth cryogenic exposures, fundamental engineering properties and fracture mechanics parameters were evaluated. To determine the fracture mechanics parameters, beams of three different dimensions were produced, with three different notch lengths for each dimension. The dynamic modulus of elasticity, ultrasonic pulse velocity, compressive strength, and bending strength of self-consolidating concretes were examined after 0, 1, and 5 cycles of cryogenic exposure. As a result, the air-cured samples exhibited greater resistance to cryogenic cycles than the water-cured samples. The KIC and CTODC values increased after one cycle of cryogenic exposure, as noted in the literature. However, the results obtained in this study demonstrate a decrease in KIC and CTODC values after five cycles compared to one cycle of cryogenic exposure.

Thermal Characteristics of Epoxy Fire-Retardant Coatings under Different Fire Regimes

Different systems of fire protection coatings are used to protect the metal structures of stories and trestles at oil and gas facilities from low (when filling cryogenic liquids) and high temperatures (in case of the possible development of a hydrocarbon fire regime). This paper presents the results of experiments of fireproof coatings on an epoxy binder after the simulation of a liquefied hydrocarbons spill and subsequent development of a hydrocarbon fire regime at the object of protection and exposure of structures to a standard fire regime. According to the experimental results, the temperatures on the samples at the end of the cryogenic exposure were determined and the time from the beginning of the thermal exposure to the limit state of the samples at a hydrocarbon and standard temperature fire regime was determined. As a result, temperature–time curves in the hydrocarbon and standard fire regimes were obtained, showing good convergence with the simulation results. The solution of the inverse task of heat conduction using finite element modeling made it possible to determine the thermophysical properties of the formed foam coke at the end of the fire tests of steel structures with intumescent coatings. It was determined that an average of 12 mm of intumescent coating thickness is required to achieve a fire protection efficiency of 120 min and for the expected impact of the hydrocarbon fire regime, the coating consumption should be increased by 1.5–2 times compared to the coating consumption for the standard regime.

Exposure of Maize Seeds to Liquid Nitrogen Modifies the Morphology and Hormonal Response of Young Plants

BACKGROUND: Cryopreservation currently represents the most suitable strategy for the long-term conservation of plant germplasm. While much effort has focused on the development of protocols to enable successful cryostorage, there are few, if any reports, that consider the effect of cryogenic temperatures on the phytohormone status of the seed and developing seedlings. OBJECTIVE: To investigate the effect of cryopreservation on external seed coat features as well as levels of indole-3- acetic acid (IAA), abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylic acid (ACC) in maize. MATERIALS AND METHODS: Two groups of seeds at 6% moisture content were compared: one was maintained at 4°C (control) while the other was exposed to LN within cryo-vials. RESULTS: Seeds exposed to cryogenic temperatures were characterized by the presence of large cracks in the seed coat compared with control seeds. Cryogenic exposure also resulted in a reduction in biomass and plant height. Results from the phytohormone analysis showed an initial reduction in the levels of IAA, ABA and ACC after 7 days of growth followed by sharp increase in levels relative to the control by 14 days. Whilst the roles of ABA and ethylene (and by extension, its precursor ACC) are well studied as stress response molecules, much less is known about the potentially vital role of auxins in regulating plant growth under conditions of low temperature stress. CONCLUSION: It is postulated that the interaction of all three hormones modulate crosstalk between various stress responses and recovery pathways to ameliorate the damage caused by freezing stress and enable plant survival. Given the dearth of information on phytohormones in cryobiology, more studies are needed to fully elucidate these relationships in the context of freezing stress caused by liquid nitrogen.

Approaches to outpatient cryodestruction as a method of choice for the treatment of recurrent basal cell carcinoma of the scalp

Skin cancer ranks second among the most common types of malignant neoplasms in Russia. Radiation therapy, surgery, and combination therapy are commonly used for the treatment of skin cancer. Unfortunately, the above methods are not always successful. The reason for the incomplete effect of surgical treatment may be insufficient radicality of the intervention due to the surgeon's desire to inflict the least trauma on the surrounding healthy tissues in order to obtain a good cosmetic result. Selective destruction of tumor tissue during cryogenic exposure with minimal damage to surrounding healthy tissues is accompanied by a hemostatic effect, which is especially important in the treatment of both primary and recurrent disintegrating tumor ulcers. The aim was to determine the expediency of cryodestruction as a method of choice for outpatient treatment. The study was controlled and non-randomized. The criterion for inclusion in the study was the diagnosis of recurrent basal cell carcinoma and subsequent cryogenic treatment at the outpatient clinic of the State Budgetary Institution of the Rostov Region «Rostov Oncological Dispensary», Novocherkassk Branch. The patient underwent tumor cryodestruction in several freeze-thaw cycles, lasting 2–3 minutes. The result of this study, i.e. complete recovery, indicates high efficiency of cryodestruction. Subsequently, the patient did not experience continued growth or new relapses. In the presence of recurrent basal cell skin cancer, cryogenic exposure is effective and is the method of choice for treatment on an outpatient basis.

Study of the uroantiseptic activity of the complex of glycosides of phenolic compounds from lingonberry leaves in complex with the arginine amino acid

The aim of the work – study the uroantiseptic activity of a complex of glycosides of phenolic compounds from lingonberry leaves in a complex with the amino acid arginine.
 Materials and methods. The object of the study was a phytosubstance, which is a complex of glycosides of phenolic compounds from lingonberry leaves in combination with the amino acid arginine (CGPA). Female laboratory rats were given a cleansing enema twice, after which the rats were provided with adequate sedation by injecting IV XYLA 2 % for anesthesia, then rectally injected 1000 μl of Escherichia coli strain at a concentration of 109 CFU/ml. The next day after infection, the animals were subjected to cryogenic action - acute cold stress at a temperature of 0+2 °C for 2.5 hours, promoting the development of the infectious and inflammatory process. The uroantiseptic effect was studied according to the following parameters: the number of leukocytes in the urine, the number of colony-forming microorganisms E.coli in 1 ml of urine (CFU/ml).
 Results. According to the obtained results of the experiment, it was established that the complex of glycosides of phenolic compounds from the leaves of lingonberry in a complex with the amino acid arginine (CGPA) showed a high uroantiseptic effect in the experimental treatment of urinary tract infection caused by E. coli ATCC 25922, which was manifested in the sanitation of the urinary tract from the uropathogen E. Coli.
 Conclusions. Analyzing the results, it can be concluded that on the model of urinary tract infection against the background of cryogenic exposure, CGPA at a dose of 100 mg/kg showed a uroantiseptic effect, which was stronger than the comparison drug "Inurek" and contributed to a faster disappearance of the titer of colony-forming microorganisms in 1 ml of urine about 2 days earlier than in the group that received dietary supplements of herbal origin "Inurek" and the disappearance of leukocyturia 3 days earlier compared to the group that received therapy with the comparison drug "Inurek". The obtained results indicate the prospects of further research of CGPA with the aim of creating new effective uroantiseptic agents of plant origin based on it

Numerical determination of the required insulation thickness for steel protection against accidental cryogenic exposure

Cryogenic spill protection by insulation is widely used as one of the most effective risk-mitigation measures to protect steel structures against accidental cryogenic spills. This study proposed, for the first time, a numerical method for predicting the insulation thickness. The method is a combination of an optimization technique and the solution to the heat conduction problem. The major difficulty lies in the boundary condition at the boiling surface, which has not been clearly stated in the literature. To accurately determine the boundary condition, the effect of the insulation thickness on the transient pool boiling heat transfer of a cryogenic liquid on an insulated steel flat plate was first studied. It was determined that the boiling resistance generally decreased with increasing insulation thickness, which suggested that the liquid and boiling surfaces could be assumed to have perfect thermal contact. Subsequently, the assumption of perfect thermal contact was proven to be a valid boundary condition for sufficiently thick insulation layers. The developed method was verified and used to draw the correlations of the insulation thickness with the period of resistance and metal thickness. The findings of this study are expected to aid in the design of steel structure’s cryogenic spill protection systems.

Assessment of cryogenic pretreatment for simulating environmental weathering in the formation of surrogate micro- and nanoplastics from agricultural mulch film

Microplastics (MPs) and nanoplastics (NPs) from mulch films and other plastic materials employed in vegetable and small fruit production pose a major threat to agricultural ecosystems. For conducting controlled studies on MPs' and NPs' (MNPs') ecotoxicity to soil organisms and plants and fate and transport in soil, surrogate MNPs are required that mimic MNPs that form in agricultural fields. We have developed a procedure to prepare MPs from plastic films or pellets using mechanical milling and sieving, and conversion of the resultant MPs into NPs through wet grinding, both steps of which mimic the degradation and fragmentation of plastics in nature. The major goal of this study was to determine if cryogenic exposure of two biodegradable mulch films effectively mimics the embrittlement caused by environmental weathering in terms of the dimensional, thermal, chemical, and biodegradability properties of the formed MNPs. We found differences in size, surface charge, thermal and chemical properties, and biodegradability in soil between MNPs prepared from cryogenically treated vs. environmentally weathered films, related to the photochemical reactions occurring in the environment that were not mimicked by cryogenic treatment, such as depolymerization and cross-link formation. We also investigated the size reduction process for NPs and found that the size distribution was bimodal, with populations centered at 50 nm and 150–300 nm, and as the size reduction process progressed, the former subpopulation's proportion increased. The biodegradability of MPs in soil was greater than for NPs, a counter-intuitive trend since greater surface area exposure for NPs would increase biodegradability. The result isassociated with differences in surface and chemical properties and to minor components that are readily leached out during the formation of NPs. In summary, the use of weathered plastics as feedstock would likely produce MNPs that are more realistic than cryogenically-treated unweathered films for use in experimental studies.

Outpatient cryodestruction as a method of choice in the treatment of recurrent skin cancer

Skin cancer is one of the most common types of malignant neoplasms in Russia. As a rule, radiation therapy, surgery, and combined modality treatment are used for skin cancer treatment. Unfortunately, the above methods are not always successful. The reason for the incomplete effect of surgical treatment may be insufficient radicalism of the intervention, due to the doctor's desire to inflict the least trauma on the surrounding healthy tissues to obtain a good cosmetic result. Selective destruction of tumor tissue during cryogenic exposure with minimal damage to surrounding healthy tissues is accompanied by a hemostatic effect, which is especially important in the treatment of both primary and recurrent disintegrating tumor ulcers. The aim of the study was the determination of the expediency of cryodestruction as a method of choice for outpatient treatment. It was a controlled, non-randomized study. The criterion for inclusion in the study was the diagnosis of recurrent skin cancer upon the first visit and subsequent treatment at the outpatient clinic of the State Budgetary Institution of the Rostov Region “Oncological Dispensary of Novocherkassk” from 2016 to 2021. The patients were planned to undergo tumor cryodestruction in several freeze-thaw cycles, lasting 2-5 minutes. The results of this study indicate the high efficiency of cryodestruction. Complete recovery was noted in 625 (84.1%) patients. 119 (15.9%) patients, who had continued growth and repeated relapses in the period from 1 to 18 months, underwent repeated cryodestruction. Subsequently, continued growth and new relapses were not observed in 104 patients. In the presence of limited recurrences of skin cancer of various localizations, cryogenic treatment is effective (recovery is the outcome in 98%) in patients of different sexes and ages, regardless of the location and extent of the tumor process, and it is the method of choice for treatment on an outpatient basis.

Flexural response of glass/epoxy composites to thermal shocks and conditioning environment in varying loading rate

The structural integrity of composites faces severe challenge in the form of environmental extremes. Therefore, its performance in those cases were of great interest. In the present work, flexural strength of glass/epoxy composites were analysed in the environment of thermal shock generated by cryogenic exposure as well by thermal conditioning. Four cases were chosen, room temperature (RT), cryogenic conditioning (LN), thermal conditioning below (BG) and above glass transition temperature (AG). The exposure time for all the environments was kept constant at 24 hours. These responses are investigated with two sets of loading rates (i) 1 mm/minute and (ii) 10 mm/min. The experimental results indicate that; all three scenarios deeply impact the flexural response of the specimen. The first set experiences changes in flexural strength, strain, and chord modulus by (2.75, -8.52, 11.32), (21.36, 39.75, -6.47), (-35.8, -11.37, -22.94) % with LN, BG and AG condition respectively. Moreover, with high rate of loading these responses change by (-23.89, -28.41, -5.17), (-37.45, -43.56, -1.86), (-19.4, -27.46, 16.37) % respectively. The prolonged exposure indicates a strain hardening phenomenon in LN specimen, which improves the flexural strength with a 1 mm/min loading rate. However, this plasticization of the specimen was unable to bear the load at an elevated rate of loading, and therefore a loss in all the properties is seen with a 10 mm/min loading rate. Therefore, it is anticipated that the properties will further deteriorate with a higher rate of loadings.

Fire Protection of Steel Structures with Epoxy Coatings under Cryogenic Exposure

Cases of fire with highly flammable, combustible liquids and combustible gases with high potential heat emission at oil and gas facilities are assumed to develop as a hydrocarbon fire, which is characterized by the temperature rising rapidly up to 1093 ± 56 °C within five minutes from the test start and staying within the same range throughout the test, as well as by overpressure being generated. Although various fireproof coating systems are commonly used to protect steel structures from high temperatures, a combination of fire protection and cryogenic spillage protection, i.e., protection from liquefied natural gas (LNG), is rather an international practice novelty regulated by standards ISO 20088. Thanks to their outstanding features, i.e., ability to sustain chemical and climatic impact, these epoxy-based materials are able to ensure positive fireproof performance for steel structures in the case of potential cryogenic impact. The article discusses tests on steel structures coated with epoxy fireproof compounds, specifically PREGRAD-EP, OGRAX-SKE and Chartek 2218. The test records show the time from the start of cryogenic exposure to the said sample reaching the limit state, as well as the time from the start of heat impact to the sample reaching the limit state in case of hydrocarbon fire temperature.

Cryodestruction of recurrent malignant skin tumors of different localizations in polyclinics

Introduction. Skin cancer is one of the most common types of malignant neoplasms in Russia. Radiation therapy, surgical intervention, and combined treatment are usually used for skin cancer. Unfortunately, the above methods are not always successful. The reason for the incomplete effect of surgical treatment may be insufficient radicalism of the intervention due to the doctor's desire to cause the least trauma to the surrounding healthy tissues in order to obtain a good cosmetic result. Selective destruction of tumor tissue in cryogenic exposure with minimal damage to surrounding healthy tissues is accompanied by a hemostatic effect, which is especially important in the treatment of both primary and recurrent decaying tumor ulcers. Aim — to evaluate the effectiveness of cryodestruction as the method of choice in the outpatient treatment of recurrent skin cancer. Materials and methods. The study was controlled, non-randomized. The criterion for inclusion in the study was the establishment of the diagnosis of recurrent skin cancer at the application and subsequent treatment in the outpatient clinic of the State Budgetary Institution "Oncologic Dispensary" in Novocherkassk from 2016 to 2020. A total of 532 patients were studied. Patients were planned to undergo tumor cryodestruction with several freeze-thaw cycles, lasting 2-5 minutes. Results. The results of the study indicate high efficiency of cryodestruction. Complete recovery in the treatment of recurrent skin cancer was observed in 446 (83.4%) patients. Repeated cryodestruction was performed in 86 (16.6%) patients, who experienced continued growth and recurrence after cryodestruction within 1 to 18 months. Subsequently, 38 of 86 patients (7.2%) did not experience continuation of growth and new recurrences. Discussion. Based on the literature data and our treatment results it was determined that cryodestruction is the most acceptable and simple method of treatment for this category of patients. Conclusion. In the presence of limited recurrences of skin cancer of various localizations, cryogenic exposure is effective (in 90.6% of the outcome — recovery) in patients of different sex and age, regardless of the location and prevalence of the tumor process and is the method of choice of treatment in an outpatient setting.

Structural Fire Protection of Steel Structures in Arctic Conditions

Most structures in the Arctic and Antarctic for oil and gas production are offshore stations, tankers, modules, steel supporting, and enclosing structures, which need to be protected against both cryogenic spills and fire exposure. Oil and gas industry facilities have products of high flammability and explosiveness, which in the case of ignition make it possible to develop a fire along the hydrocarbon curve, accompanied by a sharp jump in temperature and the formation of excessive pressure. This article discusses possible structural fire protection for metal structures in the Arctic region. Three different structural fireproofing materials are presented using super-thin basalt fiber (STBF) as an example. Tests of steel structures with fire protection are demonstrated, as a result of which the time from the beginning of cryogenic exposure to the limit state of samples is determined, and after the time from the beginning of thermal exposure to the limit state of samples under the hydrocarbon temperature regime is determined. An assessment of various flame retardants with values up to 120 min, which can be used in arctic climate conditions, was carried out. It was found that the most effective coatings are materials prepared on the basis of STBF.

Влияние криоконсервации на выживаемость семян Chamomilla reticuta сорта «Подмосковная» и химический состав эфирного масла

The article examines the effect above critical low temperatures on the quantitative and qualitative composition of essential oil of Chamomilla reticuta varia «Podmoskovnaya». Seeds of the studied plant species were treated with ultra-low temperature (–196 ºC) before planting in open ground and the viability of the seeds was determined under laboratory conditions. Cryo processing was carried out by direct immersion of seeds in plastic tubes in Dewar vessels with liquid nitrogen. Cryoprotectants were not used. Cryo processing duration was 1 hour, 3 hour and step freezing. Step freezing of seeds was performed in the following sequence: 1 hour in the refrigerating compartment (+ 4 ºC), 1 hour in the freezing compartment (–8 ºC) and 1 hour in liquid nitrogen. In all cases of the experiment, a slow thawing regime was applied. After cryogenic exposure, the material was planted into open ground. Recovery of essential oil was carried out by hydro distillation on a Clevenger apparatus. The component composition of the essential oils was determined on a Clarus-SQ 8 gas chromatograph with a mass spectrometric detector. As a result of the study, it was found that the effect of ultra-low temperatures on the seed material of the Moscow Region chamomile did not negatively affect the quantitative and qualitative composition of the essential oil of the pharmacy chamomile. On the contrary, this method of treating seeds has had a positive effect on the quantitative composition of the essential oil during the growth of the plant and in some cases has even increased the percentage of certain components, such as αfarnesene, β-farnesene, spatulenol, cis-en-in-dicycloether.

FREEZING DYNAMICS 10% CALCIUM CHLORIDE SOLUTION WITH LIQUID NITROGEN IN VITRO

Relevance. Cryosurgical method is method of ultra-low temperatures local application for complete destruction of the pathological focus. Nowadays, question of cryosurgery radicality remains unsolve, because of inability to achieve lethal for tumor cells temperatures in depth from cryoapplicator.That`s why, attempts of cryodestruction improving are still keep going by developing methods of ultra-low temperatures cytodestructive effect potentiation, particulary, by their combination with chemical agents. Objective of the study was to determine the peculiarities of changes in temperature indices 10 % CaCl2 solution freezing in comparison with 0,9 % sodium chloride solution (0,9 % NaCl) in vitro. Materials and methods. Dynamic of low-temperatures changes were measured at control depths of 3, 8, 13, and 18 mm in 10% СаСl2 and 0.9% NaCl solutions by a four-channel measuring thermocouple complex KIIT-4. Cryo-tool of the original design was used for freezing. Cryoagent - liquid nitrogen (temperature -1800C). The temperature indices were detected during 10-minute exposure to liquid nitrogen. Results. During cryogenic exposure for 10 minutes at a distance of 13 and 18 mm from the cryoprobe, the mean temperatures in 10 % CaCl2 were significantly lower than 0,9 % NaCl (p <0,05). At control depths from 5th and 10th minute of exposure in 10 % CaCl2 the temperatures were significantly lower than 0,9 % NaCl (p <0,001). Conclusion. Consequently, 10 % CaCl2 can potentiate in vitro freezing processes and can be used to further improvemnt cryosurgery efficiency in vivo.