High-altitude Conditions Research Articles

Impact of flight and equivalent short-term high-altitude exposure on ocular structures and function.

Exposure to high-altitude conditions during flight or similar activities affects many aspects of visual function, which is critical not only for flight safety but for any altitude-related activity. We aimed to summarize the available literature pertaining to ocular changes during flight or equivalent short-term high-altitude exposure (e.g., hypobaric chamber, effortless ascent lasting ≤ 24 h) and to highlight future research priorities. Using the PubMed/MEDLINE and Web of Science/ISI Web of Knowledge databases with structured search syntax, we conducted a systematic review of the literature spanning a 40-year period (January 1, 1983, to October 10, 2023). Articles pertaining to ocular changes during flight or flight-equivalent exposure to altitude were retrieved. The reference lists of retrieved studies were also searched, and citations of these references were included in the results. Of 875 relevant PubMed and ISI publications, 122 qualified for inclusion and 20 more were retrieved from the reference lists of initially selected records, for a total of 142 articles. Reported anterior segment changes included deterioration in tear film stability and increased dry eye incidence, increased corneal thickness, discomfort and bubble formation in contact lens users, refraction changes in individuals with prior refractive surgery, decreased intraocular pressure, and alterations in pupillary reaction, contrast sensitivity, and visual fields. Photoreceptor-visual pathway changes included alterations in both photoreceptors and neuro-transduction, as evidenced in dark adaptation, macular recovery time, reduction in visual field sensitivity, and optic neuritis (likely an element of decompression sickness). Retinochoroidal changes included increases in retinal vessel caliber, retinal blood flow, and choroidal thickness; central serous chorioretinopathy; and retinal vascular events (non-arteritic ischemic optic neuropathy, high-altitude retinopathy, and retinal vein occlusion). The effect of short-term high-altitude exposure on the eye is, in itself, a difficult area to study. Although serious impairment of visual acuity appears to be rare, ocular changes, including tear film stability, contact lens wear, central corneal thickness, intraocular pressure, contrast sensitivity, stability of refractive surgeries, retinal vessels, visual fields, and macula recovery time, should be considered in civilian aviators. Our report provides guidance to climbers and lowlanders traveling to altitude if they have pre-existing ocular conditions or if they experience visual symptoms while at altitude. However, key outcomes have been contradictory and comprehensive studies are scarce, especially those pertaining to the choroid and retina. Such studies could not only deepen our understanding of high-altitude ocular pathophysiology, but could also offer valuable information and treatment possibilities for a constellation of other vision-threatening diseases.

БИЙИК ТООЛУУ ШАРТТАРДА ЛЫЖА СПОРТУНА МАШЫКТЫРУУНУН АЛКАГЫНДА ЭКСПЕРИМЕНТТИК ЖАНА ТЕКШЕРҮҮЧҮ ТАЙПАЛАРДАГЫ СТУДЕНТТЕРДИН ФИЗИКАЛЫК САПАТТАРЫНЫН ӨНҮГҮҮСҮНӨ САЛЫШТЫРМА ТАЛДОО ЖҮРГҮЗҮҮ

In this article, a comparative analysis of the changes that occurred in the physical qualities of students in experimental and control groups as a result of an experimental study on the training of students in skiing in high-altitude conditions will be carried out. The author shares with the public the test results obtained from the students of these groups at the beginning of the experiment and at the end of the experiment, and draws attention to the fact that progress has been made in the development of the physical qualities of the students of the experimental group. The researcher used eight standardized tests to determine the level of physical fitness of students. Students of the experimental group regularly engaged in skiing according to the "Working program of the ski racing circle". And the students in the control group were just doing physical education. At the end of the experimental study, it was found that the training of students in skiing in high-altitude conditions is fully justified in terms of increasing their level of physical fitness, the development of physical qualities, both general and special.

Bronchial asthma and work in high-altitude mines

In occupational health, the management of patients with preliminary and periodic medical examinations for work in harmful conditions, for example, in high-altitude conditions, can be a difficult task. Bronchial asthma is one of the unequivocal contraindications to work in the highlands, however, in light of recent successes in achieving asthma control and the introduction of new types of therapy, this issue may require additional discussion. The article presents arguments both in favor of admitting patients with bronchial asthma to the highlands and against such a decision. The first group includes the elimination of allergens, long-term successes in the treatment of bronchial asthma in the highlands, as well as the fact that the decision not to allow it was popular in the era before the introduction of effective basic therapy for bronchial asthma with inhaled corticosteroids. The group of arguments "against" includes cold air, possible compensation only at relatively low altitudes, as well as remoteness, the inability to fully control compliance with patient requirements and the presence of typical industrial hazards in the form of allergens and irritants in production. It is particularly possible to emphasize the weakness of the evidence base, the extremely scarce number of published studies and the need for careful planning and conducting high-quality prospective observations of high-altitude mine workers, which can serve as a basis for the formation of an evidence base for adjusting admission conditions in the future.
 Ethics. The study did not require permission.

Mechanical, Pneumatic and Thermal Energy Storages for Micro-Air Vehicles

The growing demand for high-power propulsion systems with high energy density for micro-air vehicles (MAVs) has motivated a worldwide search for alternatives to the present conventional propulsion units which are mainly internal combustion engines (ICEs) and electric motors. Here, we evaluate the advantages of alternative mechanical energy-based storage system having high energy density and high power density characteristics. Additional key requirements for such an alternative propulsion system are high power for taking off and maneuverability, efficient energy conversion during cruise flights, easy speed control, allowing high-altitude operation, low noise signature, low thermal signature, low pollutants emission and easy restarting when needed. The various excellent features of both the internal combustion engine and the electric motor have placed them as the leading means for propulsion systems. However, the breathing difficulties of the ICEs at high-altitude conditions, their relatively low reliability and their high noise signature encouraged the search for alternative solutions. Although electric motors overcome these major drawbacks, the energy density of their energy source is much lower than that of the hydrocarbon fuels (more than an order of a magnitude) and their ability to function in missions requiring long flight durations is significantly inferior. Here, we examine alternative means of energy storage systems. Alternative mechanical energy storages including elastic (different types of springs), compressed air, thermal (phase-change materials and cryogenic reservoirs) and kinetic (flywheels) were analyzed and examined. Promising emerging technologies which are based on exceptional materials like specially designed elastomers and carbon nanotubes (CNTs) have been critically reviewed here. The carbon nanotubes are known for their very high energy density, where the energy can be delivered directly to the aircraft propeller with a remarkably high conversion efficiency.

Role, Impact, and Effect of Angiotensin-converting Enzyme 2 (ACE2) in Patients with COVID-19 under High-altitude Conditions

Role, Impact, and Effect of Angiotensin-converting Enzyme 2 (ACE2) in Patients with COVID-19 under High-altitude Conditions

Numerical study on the injection strategy on combustion and emission characteristics of a non-road diesel engine under different altitude conditions

The combustion and emission characteristics in internal combustion engine were found to deteriorate due to poor spray atomization in the cylinder at high altitude conditions. Improving the fuel mixing efficiency method like two-stage injection strategy could elevate engine power output and reduce harmful substance emissions. A non-road diesel engine operating at different altitudes were investigated. Meanwhile, a two-times orthogonal experiment optimization was proposed to optimize the injection strategy for improving the combustion and emission characteristics. Results showed that the combustion phase can be advanced, the equivalence ratio in the cylinder becomes uniform, and the combustion was more sufficient, which was conducive to improving the power performance and fuel economy of the engine at high altitude. The emissions of HC, SOOT, and CO, especially carbon smoke emissions, were effectively reduced after two times of OED optimization, with only a small increase in NOx emissions, indicating that, the traditional trade-off between carbon smoke and NOx were broken to a certain extent by using two OED optimizations. The conclusion of the present study states that the two-stage injection strategy combining with two OED can solve the problems of power reduction and increased pollution emissions caused by insufficient intake of air in the engine.

Experimental study of the fuel spray and ignition characteristics in an aeroengine afterburner under subatmospheric pressure

The fuel atomization and ignition characteristics of an afterburner under subatmospheric pressure are important foundations for expanding the operating range of the afterburner at high flight altitudes. In this work, the lean ignition limits of the afterburner at subatmospheric pressure were obtained through experiments, and the fuel droplet size distribution and ignition process in the afterburner were acquired using a laser particle sizer and a high-speed camera. The results showed that the ignition equivalence ratio increased as the inlet pressure decreased and was lowest when the flame stabilizer blockage ratio was 0.3. When the inlet pressure of the combustor decreased from high pressure to subatmospheric pressure, the Sauter mean diameter (SMD) range of the fuel droplets increased from 60∼110 μm to 100∼190 μm due to the increase in the ignition equivalence ratio and the deterioration of the fuel atomization characteristics. Under subatmospheric pressure, the flame residence phase time in the ignition process decreases significantly, while the flame intensity fluctuates more dramatically during the flame growth phase due to the decrease in the equivalence ratio of the gaseous phase, the larger fuel droplet size, and the uneven fuel distribution. When the inlet pressure is high pressure, the flame propagates from the ignition position to the trailing edge of the flame stabilizer first and anchors within the shear layer behind the flame stabilizer, whereas under subatmospheric pressure, the flame does not propagate to the anchoring point in the first place, which is one reason for the difficulty of ignition of combustors under high-altitude conditions.

THE CATALYTIC PROPERTIES OF LACTATE DEHYDROGENASE IN SKELETAL MUSCLES AND LIVER OF THE MARSH FROG (PELOPHYLAX RIDIBUNDUS) DEPEND ON ITS ECOLOGICAL AND GEOGRAPHICAL LOCATION

The marsh frog (Pelophylax ridibundus) has a widespread distribution range, which is due to a variety of adaptations that contribute to the development of tolerance to a wide range of physicochemical environmental factors. Of particular interest are the adaptations of these animals to different levels of oxygen in mid- and high-altitude conditions. In this work, a comparative analysis of the kinetic parameters of lactate dehydrogenase (LDH) in the liver of marsh frogs living in the mountainous and lowland regions of Dagestan was carried out. Animals caught in their habitats were decapitated, the liver and calf muscles were isolated, and they were placed in liquid nitrogen. In the laboratory, the selected tissues were homogenized and mitochondria-free cytosol was obtained by differential centrifugation, in which LDH activity was determined. It was found that LDH activity is significantly higher in the tissues of frogs from mountainous regions: by 42.4% in the muscles and 2.38 times in the liver (p 0.05). The high efficiency of catalysis is ensured due to significant changes in the catalytic parameters of the enzyme: an increase in Vmax (50.9% in muscles and 70% in the liver (p 0.05)) and a decrease in Km. (45.9% in muscles and 69% in liver, (p 0.05)). A more pronounced difference, compared to muscles, between LDH activity in the liver of foothill and lowland populations of frogs suggests that the sensitivity of liver LDH to changes in oxygen tension is higher. The vector of a number of other kinetic parameters of LDH (Ki, Sopt, Δ) in the liver of animals from mountainous landscapes is absolutely opposite to that of skeletal muscles. High activity and modifications of the catalytic properties of LDH in the tissues of marsh frogs living in mid-mountain areas may play an important role in the adaptation of these animals to conditions of oxygen deficiency.

Pitch Mathematical Modeling and Dynamic Analysis of a HALE UAV with Moving Mass Control Technology

Moving mass control (MMC) is considered a promising approach to regulating the attitude of an aircraft via the motion of internal moving masses. The present investigation proposes a moving mass control scheme for a high-altitude long-endurance (HALE) unmanned aerial vehicle (UAV) with a single slider moving longitudinally. To that end, a longitudinal nonlinear motion model is established, and pitch dynamics are analyzed. Furthermore, the influence of the slider parameters on the dynamic characteristics of the UAV and the change in control efficiency with speed are analyzed. Finally, a detailed root-locus-based stability and sensitivity analysis of the proposed control scheme is formulated. At an altitude of 20,000 m, the MMC scheme’s efficiency coefficient was 200% of that of elevator scheme at the cruise speed. The simulation results show that the control efficiency of the moving mass control scheme was significantly higher than that of the traditional elevator control scheme under the conditions of high altitude and low speed.

Human Bodies in Extreme Environments

Human habitation and adaptation to extreme environments have a deep history in anthropological research. Anthropologists’ understanding of these ecological pressures and how humans respond to them has grown substantially over the last 100+ years. This review covers long-standing knowledge on adaptation to classic extreme conditions of heat, cold, and high altitude, while also updating the areas in which recent research has broadened our understanding of human adaptation, acclimatization, and resilience. Unfortunately, the intersecting stresses of structural inequality and climate change have made these extremes more extreme, with drastic negative impacts on health and well-being. Future research will need to explore how extreme environments, structural inequality, and climate change are embodied as well as mitigated so that humans are better prepared to face a rapidly changing world.

AI-Enabled Interference Mitigation for Autonomous Aerial Vehicles in Urban 5G Networks †

Integrating autonomous unmanned aerial vehicles (UAVs) with fifth-generation (5G) networks presents a significant challenge due to network interference. UAVs’ high altitude and propagation conditions increase vulnerability to interference from neighbouring 5G base stations (gNBs) in the downlink direction. This paper proposes a novel deep reinforcement learning algorithm, powered by AI, to address interference through power control. By formulating and solving a signal-to-interference-and-noise ratio (SINR) optimization problem using the deep Q-learning (DQL) algorithm, interference is effectively mitigated, and link performance is improved. Performance comparison with existing interference mitigation schemes, such as fixed power allocation (FPA), tabular Q-learning, particle swarm optimization, and game theory demonstrates the superiority of the DQL algorithm, where it outperforms the next best method by 41.66% and converges to an optimal solution faster. It is also observed that, at higher speeds, the UAV sees only a 10.52% decrease in performance, which means the algorithm is able to perform effectively at high speeds. The proposed solution effectively integrates UAVs with 5G networks, mitigates interference, and enhances link performance, offering a significant advancement in this field.

Enteric glial cells aggravate the intestinal epithelial barrier damage by secreting S100β under high-altitude conditions

Damage to the intestinal epithelial barrier (IEB) has been reported under high-altitude (HA) conditions and may be responsible for HA-associated gastrointestinal (GI) disorders. However, this pathogenetic mechanism does not fully explain the GI stress symptoms, such as flatulence and motility diarrhea, which accompany the IEB damage under HA conditions, especially for the people exposed to HA acutely. In the present study, we collected the blood samples from the people who lived at HA and found the concentration of enteric glial cells (EGCs)-associated biomarkers increased significantly. HA mouse model was then established and the results revealed that EGCs were involved in IEB damage. Zona occludens (ZO)-1, occludin, and claudin-1 expression was negatively correlated with that of glial fibrillary acidic protein (GFAP) and S100β under HA conditions. In order to learn more about how EGCs influence IEB, the in vitro EGC and MODE-K hypoxia experiments that used hypoxic stimulation for simulating in vivo exposure to HA was performed. We found that hypoxia increased S100β secretion in EGCs. And MODE-K cells cultured in medium conditioned by hypoxic EGCs showed low ZO-1, occludin, and claudin-1 levels of expression. Furthermore, treatment of MODE-K cells with recombinant mouse S100β resulted in diminished levels of ZO-1, occludin, and claudin-1 expression. Thus, HA exposure induces greater S100β secretion by EGCs, which aggravates the damage to the IEB. This study has revealed a novel mechanism of IEB damage under HA conditions, and suggest that EGCs may constitute a fresh avenue for the avoidance of GI disorders at HA.

Bioprospecting of Actinobacterial Diversity and Antibacterial Secondary Metabolites from the Sediments of Four Saline Lakes on the Northern Tibetan Plateau.

The Tibetan Plateau, known as the "Roof of the World" and "The Third Pole", harbors numerous saline lakes primarily distributed in the Northern Tibetan Plateau. However, the challenging conditions of high altitude, low oxygen level, and harsh climate have limited investigations into the actinobacteria from these saline lakes. This study focuses on investigating the biodiversity and bioactive secondary metabolites of cultivable actinobacteria isolated from the sediments of four saline lakes on the Northern Tibetan Plateau. A total of 255 actinobacterial strains affiliated with 21 genera in 12 families of 7 orders were recovered by using the pure culture technique and 16S rRNA gene phylogenetic analysis. To facilitate a high-throughput bioactivity evaluation, 192 isolates underwent OSMAC cultivation in a miniaturized 24-well microbioreactor system (MATRIX cultivation). The antibacterial activity of crude extracts was then evaluated in a 96-well plate antibacterial assay. Forty-six strains demonstrated antagonistic effects against at least one tested pathogen, and their underlying antibacterial mechanisms were further investigated through a dual-fluorescent reporter assay (pDualrep2). Two Streptomyces strains (378 and 549) that produce compounds triggering DNA damage were prioritized for subsequent chemical investigations. Metabolomics profiling involving HPLC-UV/vis, UPLC-QTOF-MS/MS, and molecular networking identified three types of bioactive metabolites belonging to the aromatic polyketide family, i.e., cosmomycin, kidamycin, and hedamycin. In-depth analysis of the metabolomic data unveiled some potentially novel anthracycline compounds. A genome mining study based on the whole-genome sequences of strains 378 and 549 identified gene clusters potentially responsible for cosmomycin and kidamycin biosynthesis. This work highlights the effectiveness of combining metabolomic and genomic approaches to rapidly identify bioactive chemicals within microbial extracts. The saline lakes on the Northern Tibetan Plateau present prospective sources for discovering novel actinobacteria and biologically active compounds.

Stem Cells from Human Exfoliated Deciduous Teeth Alleviate High-Altitude Cerebral Oedema by Shifting Microglial M1/M2 Polarisation.

To explore the high-efficiency and low-risk prevention and treatment strategies for stem cells from human exfoliated deciduous teeth (SHED) for high-altitude cerebral oedema. A low-pressure and low-oxygen tank mimicking high-altitude conditions was used to establish the high-altitude cerebral oedema animal model. The preventive effects of SHED for cerebral oedema were then evaluated by haematoxylin and eosin (H&E) and histological staining. In vitro, SHED was co-cultured with BV-2 to analyse the effects of SHED by western blot and immunofluorescence staining. SHED can prevent and treat cerebral oedema in a high altitude rat animal model. Mechanistically, SHED treatment can protect brain cells from apoptosis induced by high altitude condition. Moreover, SHED treatment can inhibit M1-type polarisation and promote M2-type polarisation of microglia cells via the suppression of hypoxia inducible factor (HIF)- 1α-mediated extracellular signal-regulated kinase (ERK) signalling activated in high altitude condition. SHED treatment can relieve high-altitude cerebral oedema via inhibiting HIF- 1α-mediated ERK signalling, which indicates that SHED is a promising alternative strategy to prevent and treat high-altitude cerebral oedema.

Comparative analyses reveal potential genetic mechanisms for high-altitude adaptation of Schizopygopsis fishes based on chromosome-level genomes.

The schizothoracine fishes, widely distributed in the Qinghai-Tibetan Plateau and its adjacent areas, are considered as ideal models for investigation of high-altitude adaptation. Schizophygopsis are one group of the highly specialized schizothoracine fishes, and the genetic basis for their high-altitude adaptation is poorly understood. In this study, we performed comparative genomics analyses to investigate the potential genetic mechanisms for high-altitude adaptation of Schizopygopsis malacanthus and Schizopygopsis pylzovi based on the chromosome-level genomes. Functional enrichment analysis revealed that many expanded gene families in Schizopygopsis were associated with immune response while many contracted gene families were functionally associated with olfaction. Among the 123 positively selected genes (PSGs), angpt2a was detected in HIF-1 signaling pathway and possibly related to the hypoxia adaptation of Schizopygopsis. Furthermore, two PSGs cox15 and ndufb10 were distributed in thermogenesis, and there was a Schizopygopsis-specific missense mutation in cox15 (Gln115Glu), which possibly contributed to the cold temperature adaptation of the Schizopygopsis. Kyoto Encyclopedia of Genes and Genomes enrichment of the PSGs revealed three significant pathways including metabolic pathways, cell cycle, and homologous recombination and Gene Ontology enrichment analysis of the PSGs revealed several categories associated with DNA repair, cellular response to DNA damage stimulus, and metabolic process. Chromosome-scale characterization of olfactory receptor (OR) repertoires indicated that Schizopygopsis had the least number of OR genes, and the OR gene contraction was possibly caused by the limited food variety and the environmental factors such as lower air pressure, lower humidity, and lower temperature. Our study will help expand our understanding of the potential adaptive mechanism of Schizopygopsis to cope with the high-altitude conditions.

CT Imaging, Macroanatomical and Morphometric Analysis of Os penis in Brown Bear (Ursus arctos)

The aim of this study is to reveal the macroscopic features of the brown bear (Ursus arctos) os penis (baculum), as well as its morphometric measurements with the help of computerized tomography and digital electronic caliper. The study material was obtained from an adult male brown bear weighing approximately 400 kg, which was brought to the Wildlife Protection and Rehabilitation Unit of Kafkas University and died as a result of a traffic accident in the Sarıkamış district of Kars. After the skin and soft tissues around the baculum were removed, they were kept in hydrogen peroxide for 2-3 hours. In the macroscopic examination, it was determined that the baculum was straight, close to the pen, except for a slight curve in the distal part, and ended with a small tubercle at the distal end. A small notch was found in the proximal part. In addition to the prominent sulcus urethralis in the ventral of the baculum, a short groove was also detected in its lateral. In addition to the prominent sulcus urethralis in the ventral of the baculum, a short groove was also detected in its lateral. A cartilage tissue of 11.08 mm in length and 4.67 mm in thickness was determined in the distal of the bone. In the morphometric measurements made with a digital electronic caliper, the length of the baculum was 148.95 mm, while the diameters were measured as 4.58 mm in the distal and 13.72 mm in the proximal, respectively. In computed tomography, baculum length was 148.84 mm, distal diameter length was 5.63 mm, and proximal diameter length was 13.12 mm. In addition, computed tomography measured the length of the cortex as 0.76 mm, the length of the medulla as 5.74 mm in the distal, and the cortex length of 0.77 mm and the medulla length of 5.32 mm in the proximal region. As a result, in this study, the macroanatomical and morphometric features of the brown bear baculum, which live in high altitude and cold climate conditions, were revealed.

Mode decomposition based large margin distribution machines for sediment load prediction

Precise suspended sediment load (SSL) prediction is essential for irrigation, hydropower and river management practices. But due to some external factors such as high altitude, heavy monsoon and tropical climate conditions, the data we collect may contain noisy samples. Hence, it becomes a challenging task to accurately predict the SSL in rivers. Therefore, to diminish the influence of noise, the empirical mode decomposition (EMD) -based techniques can be adopted. Moreover, the large margin distribution machine-based regression (LDMR) can deal efficiently with noisy datasets as it simultaneously minimizes the insensitive loss as well as quadratic loss. The significance of this work lies in its contribution to improving the accuracy of suspended sediment load (SSL) prediction in rivers, which has practical implications for various applications such as irrigation, hydropower, and river management. We recognize the challenges posed by external factors, which introduce noise into the collected data, making accurate prediction of SSL difficult. Overall, the significance of this work lies in its novel integration of EMD-based techniques and LDMR-based models, which address the challenges posed by noisy and non-stationary sediment load data. The findings contribute to the field of SSL prediction, offering practical solutions for managing and utilizing river resources more effectively in various domains. The main advantage of the least squares LDMR (LS-LDMR) approach is that it solves a system of linear equations rather than solving a large QPPs unlike SVR, TSVR, LDMR, which makes it computationally efficient. It is well known that the sediment load data is complex and non-stationary in nature. Therefore, for daily SSL prediction, the LDMR and least squares LDMR (LSLDMR) models are embedded with two different decomposition techniques, EMD and ensemble EMD (EEMD), to handle the nonlinear and non-stationary characteristics of sediment load data on the forecasted outputs and to increase prediction ability. The results of the proposed EMD-LDMR, EEMD-LDMR, EMD-LSLDMR and EEMD-LSLDMR are compared with the conventional support vector regression (SVR), twin SVR (TSVR), LDMR and LSLDMR. The performance of the evaluated using the best-fit model using the mean absolute error (MAE), root mean square error (RMSE), symmetric mean absolute percentage error (SMAPE), Willmott’s index (WI), correlation coefficient (CC) and R2. Better or comparable results specify the efficiency of the suggested models. For graphical visualization, scatterplots, prediction error plots and violin plots are shown. Numerical results show that these hybrid models show excellent prediction performance. The overall analysis of the results suggests using EEMD-LSLDMR for SSL estimation.

Investigation of Effect of Nozzle Numbers on Diesel Engine Performance Operated at Plateau Environment

The effect of nozzle number on the combustion and emission characteristics of diesel engines operating at high altitudes was investigated in this study. A three-dimensional computational fluid dynamics model was developed to simulate the spray spatial distribution, which is closely related to the nozzle number. The intake pressure was identified as the dominant factor under varying altitudes, while the fuel mass, injection timing and temperature were maintained constant. Altitudes of 3000 m were chosen to represent typical high-altitude conditions, and sea level cases were simulated for comparison. The results demonstrated that high-altitude operation reduced the air utility in the combustion chamber, leading to suppressed soot oxidization and worse soot emissions. Moreover, more injection nozzles will decrease the fuel injection pressure, resulting in inadequate fuel diffusion and detrimental effects on the combustion efficiency and soot control. However, too few nozzles may cause wall collisions and worsen the combustion conditions. The number of nozzles also influences the combustion, with a higher number of nozzles exacerbating poor combustion conditions. The optimal number of nozzles for the engine studied is determined to be six. Hence, determining the optimal nozzle number plays a vital role in achieving the optimal performance of highland diesel engines. This study provides valuable guidance for the development of diesel engines in high-altitude environments, where controlling the fuel consumption and soot emissions is challenging.

Influence of Extreme Factors of High Mountains on the Ultrastructure of Rat Blood Leukocytes

This paper presents the results of a study on the ultrastructure of white blood cells under the influence of high-altitude factors in combination with cold. Materials and methods: 70 outbred male laboratory rats weighing 200-300 g; method of electron microscopic examination, statistical methods. Research results. It has been established that in rats, during adaptation to high altitude conditions, in combination with exposure to cold, there are sharp changes in the ultrastructure of leukocytes. In experimental animals on the 3rd day of observation, the level of volumetric density of mitochondria increased almost 2 times in neutrophils, 1.5 times in eosinophils, and 1.4 times in monocytes and medium lymphocytes. With an increase in the length of stay in the highlands in combination with cold exposure, the volumetric density of mitochondria continued to increase in all types of white blood cells, and on the 30th day of adaptation it remained statistically significantly higher both in comparison with the control and in comparison, with the indices of the animal group on the 3rd and day of adaptation. The volumetric density of ribosomes also increased statistically significantly on the 3rd day of adaptation to high mountains in combination with cold in neutrophils, eosinophils, and lymphocytes, and continued to increase by the 30th day of observation. A trend towards an increase in bulk density was also noted in cell vacuoles: on the 3rd day of adaptation, an increase in the volumetric density of vacuoles was recorded compared to the control in neutrophils. By the 30th day of adaptation, the bulk density of vacuoles, compared with animals on the 3rd day of adaptation, statistically significantly decreased, although it did not reach the indicators of animals in the control group. The bulk density of specific granites on the 3rd day of stay in the mountains in neutrophils and eosinophils decreased by almost 100%.

Cerenerlal remodeling after cranio-brain injury in high mountains

The article discusses the presentation of the features of cerebellar remodeling after traumatic brain injury (TBI) in the highlands. The experiment was carried out on 106 outbred male rats weighing 210290 g in compliance with the rules of laboratory practice. In high-altitude conditions, in contrast to low-altitude conditions, significant changes occur in the cerebellum, namely, changes in the membrane potential of cells, ectopia of Purkinje cells, pronounced changes in molecular and granular layers.