High Altitude Areas Research Articles

Multi-Omics Analysis Uncovers the Mechanism for Enhanced Organic Acid Accumulation in Peach (Prunus persica L.) Fruit from High-Altitude Areas

The early-ripening peach industry has undergone rapid development in the Panxi region of the Sichuan Basin in recent years. However, after the introduction of some new peach varieties to the high-altitude peach-producing areas in Panxi, the titratable acid content in peach fruit has significantly increased. This study compared the fruit quality indicators of early-ripening peach varieties cultivated in Xide County (a high-altitude peach-producing area) and Longquanyi District (a low-altitude peach-producing area) in Sichuan Province and analyzed the differences in organic acid metabolism by combining primary metabolomic and transcriptomic approaches. The results showed that the ‘Zhongtaohongyu’ fruit from the high-altitude peach-producing area had a much higher accumulation of malic acid and, accordingly, a significantly higher organic acid content than the other samples. The lower annual average temperature and stronger ultraviolet radiation in high-altitude peach-producing areas may lead to the increased expression of genes (PpNAD-ME1, PpNADP-ME3, and PpPEPC1) in the organic acid synthesis pathway and the decreased expression of genes (PpACO2, PpNAD-MDH2/3/4/5, and PpPEPCK2) in the organic acid degradation pathway in peach fruit, ultimately resulting in the accumulation of more organic acids. Among them, the downregulation of the key genes PpNAD-MDH3/4/5 involved in malic acid metabolism may be the main reason for the higher malic acid accumulation in peach fruit from high-altitude peach-producing areas. Overall, this study elucidates the mechanism by which environmental factors enhance the accumulation of organic acids in peach fruit from high-altitude peach-producing areas from a multi-omics perspective, as well as providing a theoretical basis for screening key genes involved in organic acid metabolism in peach fruit.

First discovery of snow scorpionflies (Mecoptera: Boreidae) from China

Snow scorpionflies are notable for their unusual activity during the cold winter months as adults. Although widely distributed in boreal or high-altitude areas of the Palearctic and Nearctic Regions, their presence in China has not been documented until now. This paper reports the first discovery of three species of snow scorpionflies, Boreus altaicus Nikolajev, 2015, B. beybienkoi Tarbinsky, 1962, and B. transiliensis Nikolajev, 1998 from Xinjiang Uygur Autonomous Region, northwestern China, and provides new insights into their morphology and biology. These discoveries increase the number of known Mecoptera families in China from three to four.

The source of volatile organic compounds pollution and its effect on ozone in high-altitude areas

Volatile organic compounds (VOCs) are crucial precursors in the formation of ozone (O3). The sources of pollution are complex and significantly impact O3 generation. Long-term exposure to high-concentration O3 environments causes serious damage to organisms. High-altitude areas experience continuous high temperatures and strong solar radiation, which can easily produce O3 through photochemical reactions, making these areas prone to frequent air pollution. This study utilizes the National Positioning Station of the Yinchuan Urban Ecosystem in Ningxia to conduct field synchronous observations, gathering data on VOCs, meteorological variables, and O3. By employing machine learning algorithms, we examined the seasonal distribution characteristics of VOCs, their pollution sources, and their impact on O3. The results show that the seasonal distribution of VOCs areas is low in spring and autumn and high in summer and winter. The components with higher volume fraction contribution are m-tolualdehyde in spring and summer, ethane in autumn, and acetylene in winter. The main emission sources of VOCs pollution are hydrocarbon volatile emission in spring and winter, solvent volatilization emission in summer, and industrial sources in autumn. VOCs have a negative effect on O3, with a greater impact in winter and spring, evidenced by standardized effect values of −0.26 and −0.24. The key components affecting O3 in VOCs vary by season. Aromatic hydrocarbons are the key components in spring and winter, with contribution rates of 22 % and 21.3 %. Alkenes are the key components in summer and autumn (24.5 % and 26.8 %). Among meteorological variables, temperature is the key factor affecting O3, while wind speed is the key factor affecting O3 only in winter. This study aims to clarify the sources of VOCs pollution in different seasons and their impact on O3, providing a theoretical basis and technical support for the prevention and control of VOCs and O3 pollution in high-altitude areas.

A wide distribution of Beiji nairoviruses and related viruses in Ixodes ticks in Japan

Beiji nairovirus (BJNV), in the family Nairoviridae, the order Bunyavirales, was recently reported as a causative agent of an emerging tick-borne zoonotic infection in China. This study investigated the prevalence of BJNV in ticks in Japan. Screening of over 2,000 ticks from multiple regions revealed a widespread distribution of BJNV and BJNV-related viruses in Japan, particularly in the northern island, and in other high altitude areas with exclusive occurrence of Ixodes ticks. Phylogenetic analysis identified three distinct groups of nairoviruses in ticks in Japan: BJNV, Yichun nairovirus (YCNV) and a newly identified Mikuni nairovirus (MKNV). BJNV and YCNV variants identified in ticks in Japan exhibited high nucleotide sequence identities to those in China and Russia with evidence of non-monophyletic evolution among BJNVs, suggesting multiple cross-border transmission events of BJNV between the Eurasian continent and Japan. Whole genome sequencing of BJNV and MKNV revealed a unique GA-rich region in the S segment, the significance of which remains to be determined. In conclusion, the present study has shown a wide distribution and diversity of BJNV-related nairoviruses in Ixodes ticks in Japan and has identified unique genomic structures. The findings demonstrate the significance of BJNV as well as related viruses in Japan and highlight the necessity of monitoring emerging nairovirus infections and their potential risks to public health.

Effect of steam curing regime on the mechanical properties, drying shrinkage, and microstructure of mortar in high-altitude areas with low air pressure

Low air pressure in plateau regions impacts the microstructure and macroscopic properties of cement-based materials by altering water transport. However, the efficiency of steam curing, a frequently-used curing approach, under these conditions has been inadequately studied. This work compares the effects of steam curing on the mechanical properties, drying shrinkage, and microstructure of cement-based materials at low air pressure. Results show that low air pressure decreases the compressive strength and increases the drying shrinkage of steam-cured mortar due to reduced hydration and increased total pore volume. Optimally, a steam curing temperature of 40°C to 60°C minimizes thermal damage, and a pre-curing time of 3 hours yields the best mechanical properties and drying shrinkage. Additionally, a field case confirms the effectiveness of the proposed steam curing regime; the demolding strength of precast beams meets engineering standards, and drying shrinkage fluctuates significantly with daily temperature changes. Notably, a 25.30 % difference in 90-day drying shrinkage between steam-cured and non-steam-cured specimens underscores the necessity of steam curing in high-altitude areas. These findings are crucial for optimizing steam curing practices in low-pressure environments.

Effects of short-term exposure to high altitude on cardiac function

Abstract Background What effect does short-term high altitude exposure have on heart function? Can people exercise in the highlands? what changes occur in heart function during exercise in highland areas? This study will explore these topics. Objectives To investigate the difference of heart function between people at sea level and at high altitude, and to study the changes of short time exercise on heart function at high altitude. Methods 36 healthy subjects were recruited to go to high altitude area after underwent exercise echocardiography on a supine bicycle at sea level. They ascended to 3600m within 24 hours by bus.Another exercise echocardiography was performed on the day of arrival.Heart rate (HR), blood pressure (BP) and blood oxygen saturation (SaO2) were monitored in real time during both examinations. Parameters such as left ventricular ejection fraction, E/ E 'and mean pulmonary artery pressure (mPAP) after rest and exercise were calculated.ΔmPAP /CO was calculated by (mean mPAP at peak -mean mPAP at rest )/(mean CO at peak-mean CO at rest). Results At peak exercise,SaO2,TRV,RVD2,SPAP,mPAP,PVR, ePLAR,RVAS,ΔMpap/CO were much higher at high altitude levels. (P < 0.001); E,A,FAC,ΔS were significantly lower than that of the sea leval; at rest, HR,TRV,sPAP,mPAP ,PVR were much higher at high altitude levels than at sea leval(P < 0.001)，SaO2,RVOT ACT, were significantly lower than that of the sea leval(P < 0.001). Conclusions When healthy people are in high altitude environment, the heart function changes obviously. Supine bicycle exercise stress echocardiography can well monitor the heart function changes and provide quantitative data, providing new technical methods for future related research.

Future Scenarios of Forest Carbon Sink in a Typical Subtropical County

In the context of achieving global carbon neutrality, forests play a pivotal role in sequestering atmospheric CO2, particularly in China, where forest management is central to national climate strategies. This study evaluates the forest carbon sink capacity in Zixi County, a subtropical region, under varying climate scenarios (SSP2-4.5 and SSP5-8.5). Using the Forest-DNDC (Denitrification–Decomposition) model, combined with high-precision climate data and a random forest model, we simulate forest carbon density and forest carbon sink under different management strategies. The results indicate that under the baseline scenario, forest carbon density in Zixi County increases by 31% over 42 years under the SSP2-4.5 climate scenario and by 28.6% under SSP5-8.5. In the enhancing economic scenario, carbon density increases by 8.5% under SSP2-4.5 and by 7.2% under SSP5-8.5. For the natural development scenario, a significant increase of 130% is observed under SSP2-4.5, while SSP5-8.5 shows an increase of 120%. Spatially, forest carbon sinks in Zixi County total 843,152 T C in 2020, 542,852 T C in 2030, and 877,802 T C in 2060 under the baseline SSP2-4.5 scenario; under SSP5-8.5, these values are 841,321 T C in 2020, 531,301 T C in 2030, and 1,016,402 T C in 2060. In the enhancing economic scenario, the total carbon sink is 34,650 T C in both 2020 and 2030, increasing to 427,351 T C in 2060 under SSP2-4.5, while under SSP5-8.5, it is 46,200 T C in 2020, 34,650 T C in 2030, and 415,801 T C in 2060. The natural development scenario shows the total carbon sink under SSP2-4.5 as 11,157,332 T C in 2020, 3,441,910 T C in 2030, and 1,409,104 T C in 2060, and under SSP5-8.5, it is 10,903,231 T C in 2020, 3,337,960 T C in 2030, and 1,131,903 T C in 2060. Spatial analysis reveals that elevation and forest type significantly affect carbon density, with high-altitude areas and forests dominated by Chinese fir and broadleaf species showing higher carbon accumulation. The findings highlight the importance of targeted forest management, prioritizing species with higher carbon sequestration potential and considering spatial heterogeneity. These strategies, applied locally, can contribute to broader national and global carbon neutrality efforts.

Study on the balance and gait characteristics of subjects with generalized joint hypermobility residing in high-altitude using wearable devices: a cross-sectional study

PurposeTo investigate the characteristics of balance and gait functions in Generalized Joint Hypermobility (GJH) subjects residing in high-altitude areas.MethodsThis study included 61 university students (28 with GJH and 33 healthy controls) all from the high-altitude region of Linzhi, Tibet Autonomous Region. The Riablo™ wearable intelligent rehabilitation assessment and training system was used to assess static balance (with eyes open and closed) and gait function (during flat walking) in both groups.ResultsCompared to healthy subjects, GJH subjects exhibited significantly impaired balance, indicated by an increased distance of the center of pressure position from the ideal center of gravity(EO: P = 0.007, EC: P = 0.031) and greater amplitude of center of pressure displacements (EO: P = 0.043, EC: P = 0.032). Gait velocity(P = 0.007), stride length(P = 0.012), and swing stance phase of the gait cycle(P = 0.046) were significantly reduced in GJH subjects compared to healthy subjects. A significant increase in the flat-foot phase of the gait cycle(P = 0.022) was observed in GJH subjects compared to healthy subjects.ConclusionThe current study demonstrated that GJH subjects residing in high-altitude areas exhibit impairments in balance and gait, providing a basis for training and prevention strategies tailored for this population. And this study used the wearable intelligent rehabilitation evaluation and training system in high-altitude areas, providing methodological references for scientific research on balance and gait function under non laboratory conditions.Trial registrationControlled Trials No.102772023RT133, Registered 13 October 2023.

Evolution and simulation optimization of rural settlements in urban-rural integration areas from a multi-gradient perspective: A case study of the Lan-Bai urban agglomeration in China

With the rapid growth of global urbanization, rural land has been continuously occupied, which has brought about profound changes in human-land relationship. As a rural regional system in the frontier area of urbanization, the rural settlements in the urban-rural integration area (URIA) are in a profound transformation due to multiple disturbances such as internal natural factors and social and economic factors brought about by external urbanization. Based on the internal and external system factors of rural settlements, this paper constructs an analytical framework to explore the spatial and temporal evolution pattern of URIA rural settlements from 2000 to 2020, and then summarizes its evolution model, and predicts the situation of rural settlements in different scenarios in 2030. Finally, the optimal control strategy is proposed. The results show that: (1) From 2000 to 2020, affected by the gradient of natural environment, the scale of rural settlements in URIA shows a trend of decreasing in low-altitude areas near rivers and increasing in high-altitude areas far from rivers. Under the socio-economic gradient, there is a phenomenon that the scale of rural settlements in the inner edge of URIA with better socio-economic environment decreases and the scale of settlements in the outer area of URIA with poor socio-economic environment increases. (2) Based on different environmental factors, in the internal natural environment, it shows the evolution mode of “terrain containment” and “water source guidance”, while in the socio-economic environment, it shows the evolution mode of “urban sprawl encroaches rural”, “population decrease and land increase”. (3) The simulation results of rural settlements in 2030 show that the scale of rural settlements in the periphery of URIA continues to increase under the natural development (ND) scenario, while the scale of rural settlements in the inner edge decreases and the distribution is scattered. Under the urban-rural integration development (URD) scenario, rural settlements are mainly concentrated in the core area of URIA, and the area of rural settlements turning into urban land has dropped significantly. (4) Based on different gradients, the settlements are divided into three types: centralized development type, restricted development type and migration remediation type. Patch reconstruction is carried out by gravity model, which can theoretically save land and vacate 327 hm2 of construction land index. Compared with the extensive development model of the ND scenario, the URD scenario has important theoretical significance in limiting the blind expansion of the city and realizing the integration of urban and rural development in Lanbai.

Change in the prevalence of anemia in children aged 6-59 months using the new World Health Organization 2024 criteria.

The World Health Organization (WHO) has published new hemoglobin cutoff points for defining anemia and its measurement. This change could impact the prevalence of anemia, particularly in countries with populations living in high-altitude areas. This study estimates the national prevalences of anemia in children aged 6-59 months using Centers for Disease Control and Prevention (CDC) 1989 and WHO 2024 criteria. Data from 406,106 children in 48 countries (45 Demographic and Health Surveys [DHS Program] and 3 Andean [Ecuador, Bolivia, and Peru]) were analyzed. The pooled prevalence of anemia was 61.4% according to the WHO 2024 criteria. Three countries showed changes in anemia prevalence, with shifts of 10 or more percentage points (Uganda, Rwanda, and Jordan). Across all the studied countries, the prevalence of anemia was higher at greater altitudes, rural areas, and children from households of low wealth quintiles, regardless of the criteria used. Moreover, changes in anemia prevalence were identified when stratified by altitude of residence, showing differences in the levels of public health significance across various political-administrative regions in Andean countries. Overall, these findings provide valuable insights into the epidemiology of anemia and highlight the need for continued surveillance and targeted interventions to effectively address this global health challenge.

Ontogeny and associated changes of the extinct sloth Simomylodon uccasamamensis (Xenarthra, Mylodontidae) from the Pliocene of the eastern Puna, Argentina.

Within Xenarthra (Eocene-Recent), Folivora developed (late Eocene-Recent) a remarkable diversity with respect to ecology and taxonomy over its evolutionary history. Knowledge of the diversity achieved by members of this clade in high-altitude areas of South America (i.e., Altiplano and Puna regions of Peru, Bolivia, and northwestern Argentina) has been improved in recent decades. A particular example involves the late Neogene Mylodontidae Simomylodon uccasamamensis, known mostly from multiple specimens recovered from the Bolivian Altiplano. Although several anatomical descriptions of this ground sloth have been published, almost nothing is known about its ontogenetic development and the associated morphological changes. Here we describe and compare new specimens of S. uccasamamensis from the upper level of the Tafna Formation (Pliocene) in the eastern Puna (ca. 3800 masl), Argentina, representing the southernmost record of this species. The new material is represented by specimens showing different ontogenetic stages, from infant to adult. One subadult specimen reached an estimated body mass of ca. 232 kg. The comparative study of external and internal morphology (the latter obtained from CT scans and radiography) shows remarkable changes in the mandible and molariforms associated with ontogeny; in addition, evidence suggests that the mfs2-3 are the first functional teeth, followed by mf1 and cf1. Based on our body mass estimates (ca. 232 kg.), we inferred an average lifespan of 14 years, 9-month gestation time, and sexual maturation at 4.1 years, quite similar to the values we obtained based on estimated body masses of adult specimens from Bolivia published by previous authors. Along its latitudinal distribution (ca. 14° S-21° S) S. uccasamamensis co-occurred with other ground sloths (e.g., Megatheriinae, Thalassocninae, and Scelidotheriinae), suggesting niche partitioning. The presence of this medium-sized ground sloth is consistent with the similarity between the faunas of eastern Puna and the Bolivian Altiplano during the Pliocene, which is also concordant with what was observed in other clades, such as Rodentia and Notoungulata.

Conformal SnO2 and NiOx charge transport layers for pragmatic air-processed perovskite solar cells

The industrialization of perovskite (PVK) solar cells (PSCs) necessitates simple manufacturing, cheapness, nontoxicity, high efficiency, and stability. We report an air-processed lead halide PSCs with cheap, nontoxic, stable NiOx and SnO2 as the hole and electron transport layers separately, to meet all the above commercial requests. By preparing the NiOx (water-dispersible) and SnO2 (oil-dispersible) quantum dots (QDs) with good conductivity and energy band matched well with that of PVK, we fabricate inverted PSCs (ITO/NiOx/PVK/SnO2/Ag) with efficiency up to 20.1/14.6% for active areas of 0.0707/1 cm2, under 1 sun simulated illumination with enhanced UV light ratio. The UV-light resistant PSCs reported here will impel their application in the high altitude areas with strong UV light. Importantly, the monodisperse size and dominant (110) plane of SnO2 QDs achieved by controlling the solvothermal parameters, realize the conformal deposition and defect prevention of SnO2, respectively, thus improving the PSC efficiency and stability.

Combined endovascular interventions for pulmonary embolism at high altitude in Tibet.

Managing pulmonary embolism (PE) at extremely high altitudes poses unique challenges due to harsh environmental conditions and limited healthcare resources. This study retrospectively analyzed Tibetan PE patients in the Tibet Autonomous Region of China to evaluate the effectiveness and safety of combined endovascular interventional therapy in high-altitude areas. The average altitude of long-term residence for Tibetan patients was 3,863.4 ± 317.4 m, with an average age of 62.0 ± 16.0 years, and the time from computed tomography pulmonary angiography (CTPA) diagnosis to interventional treatment averaged 2.8 ± 2.2 days. The operation time for these patients was 106.1 ± 22.2 min, and the intraoperative dose of alteplase used was 23.3 ± 5.0 mg. All 9 patients reported profound remission of dyspnea and chest pain after endovascular interventions. The heart rate (p < 0.05) and respiratory rate (p < 0.001) of all enrolled patients were significantly decreased, and the peripheral capillary oxygen saturation (SpO2) was significantly increased (p < 0.05) after interventions. No severe complications, such as bleeding, occurred in any patient. This study demonstrated the potential clinical benefits and feasibility of combined endovascular interventional therapy for treating acute PE in extreme high-altitude regions.

3,600 years of human adaptation to drought intensification on the southern Tibetan Plateau

The development of adaptive survival strategies is crucial for human occupation of the high-altitude areas of the Tibetan Plateau (TP). However, the history of this adaptation and its driving mechanisms are poorly understood. We used records of pollen, coprophilous fungal spores, and charcoal from a well-dated, high-resolution lake sediment core from the Southern Tibetan Plateau (STP) to investigate the history of high-altitude survival strategies, including arable agriculture and pastoralism, spanning the past 3600 years. The results revealed that survival strategies were dominated by arable agriculture, supplemented by pastoralism, from ~3600 to 1800 cal yr BP. However, after 1800 cal yr BP, this strategy shifted to low-level arable agriculture with intensified pastoralism. Comparison of our findings with regional paleoclimatic and archaeological records revealed that this transformation was an adaptive response to drought intensification. This adaptive resilience was a key aspect of human occupation of the high-altitude regions of the TP during the late Holocene.

Effects of Climate Changes and Crop Phenological Responses on Soil Organic Carbon of Cultivated Land in Fujian Province

Research on the mechanism of how climate change affects cultivated soil organic carbon is the basis for the management of cultivated land quality in the context of climate change. Crop phenological responses to climate change have an important effect on cultivated soil organic carbon as well. However, previous research primarily focused on the independent effects of climate change or crop phenological responses on the changes in soil organic carbon, and few studies have analyzed the changes in cultivated soil organic carbon under the combined influence of both factors or quantified their contribution rates to the changes in cultivated soil organic carbon. Based on topsoil samples in 2008 and 2021, annual pre-season and mid-season climate data from 2008 to 2021, and the phenological parameters extracted from the enhanced vegetation index （EVI） time series from 2007 to 2022, a soil organic carbon predictive model was constructed using the random forest algorithm. The total change in soil organic carbon from 2008 to 2021, the change in soil organic carbon under climate change alone, and the change in soil organic carbon under the synergistic influence of climate change and crop phenological responses were simulated. Furthermore, the contributions of climate change and crop phenological responses to the changes in cultivated soil organic carbon were distinguished and quantified. Moreover, the dominant influencing factors of soil organic carbon changes and their spatial distributions were identified and analyzed. The results were as follows： ① Under the synergistic influence of climate change and crop phenological responses, a decrease was observed in soil organic carbon in 74.15% of the cultivated land area in Fujian Province during the years 2008-2021, with an average decrease of 2.20 g·kg-1. Additionally, there was an increase in soil organic carbon in 25.85% of the cultivated area, with an average increase of 1.48 g·kg-1. ②The average contribution rates of pre-season climate, crop phenological responses to climate change, mid-season climate, and phenological changes resulting from cultivars shifts or other adjustments of agricultural measures to soil organic carbon changes were 34.08%, 28.56%, 22.75%, and 14.61%, respectively. Overall, climate change had a greater impact on the changes in cultivated soil organic carbon in Fujian Province than the crop phenological response to climate change. ③ The regions where climate change and phenological response jointly acted as dominant influencing factors held the largest area, accounting for 47.06% of the total cultivated land area in Fujian Province, and the regions where climate change was the dominant influencing factor alone held the second-largest area, accounting for 28.64% of the total cultivated land area. ④ Higher contribution rates of pre-season climate factors and phenological changes resulting from cultivar shifts or other adjustments of agricultural measures tended to be distributed in higher-altitude areas, whereas higher contribution rates of mid-season climate factors and phenological responses to climate change tended to be distributed in lower-altitude areas. These research findings can provide a theoretical basis for decision making regarding the management of cultivated land quality and the safeguarding of food security in the context of climate change.

Spatiotemporal Eolution and Prediction of Ecosystem Service Value in Taihang Mountains Based on MCCA Land Use Scenario Simulation

Ecosystem service value （ESV） is an important indicator related to regional ecological well-being, and understanding its evolution can provide references for regional ecological civilization construction and sustainable development. The Taihang Mountains, an important ecological security barrier in North China, were taken as an example. Based on land use data from 2000 to 2020, this study revealed the changes in land use and ecosystem service value in the Taihang Mountains and conducted multi-scenario simulations of ESV in 2035. Additionally, the land use transfer matrix, improved equivalent factor method, and mixed-cell cellular automata model were used. The results showed that： ① From 2000 to 2020, the main land use types in the Taihang Mountains were cropland, forest land, and grassland. The area of cropland and grassland significantly decreased, whereas the area of forest land and construction land remained stable. The scale of land use transfer was 2.06×104 km2, with a high intensity of transfer from cropland and grassland to other areas, mainly guided by ecological construction. ② The ecosystem service functions in the Taihang Mountains were mainly dominated by regulation services, and the overall ESV showed a stable upward trend, increasing by 1.51×1010 RMB from 2000 to 2020. The spatial distribution of ESV was uneven, and the polarization phenomenon was evident, with high-value areas concentrated in the high-altitude areas in the northern and central-southern parts and low-value areas mostly located in the flat foothills and central plateaus on both sides. They were greatly influenced by human activities. ③ By 2035, compared with that in 2020, the ESV in the Taihang Mountains was projected to increase by 5.37 billion RMB in the natural growth scenario, 4.34 billion RMB in the urban development scenario, and 7.64 billion RMB in the ecological tourism scenario, mainly due to the conversion from cropland and grassland to forest land. The natural growth scenario showed a high intensity of spatial transformation of ESV, the urban development scenario experienced severe ESV loss in cropland, and the ecological tourism scenario showed a significant increase in ESV, which was an effective path for promoting green development in the Taihang Mountains. The research results can provide scientific references for the healthy management and sustainable development of the ecosystem in the Taihang Mountains.

Dominant influence of biomass combustion and cross-border transport on nitrogen-containing organic compound levels in the southeastern Tibetan Plateau

Abstract. The Tibetan Plateau (TP) is highly susceptible to climate change, and nitrogen-containing organic compounds (NOCs) in fine particulate matter (PM2.5) represent one of the largest uncertainties with respect to their impact on the climate in high-altitude areas. Previous studies have shown that NOCs play a vital role in the nitrogen budget of PM2.5. However, our understanding of the composition and sources of NOCs in PM2.5, particularly in the TP, is limited. Here, we aim to enhance our understanding of NOCs in the TP region by examining their identification, concentration levels, sources, and origins. We conducted field sampling at a regional background sampling site in Gaomeigu, in the southeastern margin of the TP from 11 March to 13 May 2017, followed by laboratory analysis of the NOCs collected on the filters. The daily mass concentrations of NOCs ranged from 714.4 to 3887.1 ng m−3, with an average of 2119.4 ± 875.0 ng m−3 during the campaign. This average concentration was approximately 40 % higher than that reported at a typical regional site in the North China Plain (NCP), highlighting a more significant presence of NOCs in the Tibetan area. Biomass burning and secondary sources were identified as the major contributors to total NOCs. This was further substantiated by a regional air quality model, which indicated that over 80 % of the aerosol in the southeast of the TP originated from neighboring countries. This study improves our understanding of NOCs' contribution to PM2.5 in the TP and their potential impacts on climate stability in high-altitude areas.

Oral antioxidant edaravone protects against cognitive deficits induced by chronic hypobaric hypoxia at high altitudes

Chronic hypobaric hypoxia at high altitudes can impair cognitive functions, especially causing deficits in learning and memory, which require therapeutic intervention. Here, we showed that mice subjected to hypobaric hypoxia (simulating an altitude of 5000 m) for one month experienced significant cognitive impairment, accompanied by increased biomarker levels of oxidative stress in the brain and blood. Oral administration of a novel formulation of edaravone, a free radical scavenger approved for the treatment of ischaemic stroke and amyotrophic lateral sclerosis, significantly alleviated oxidative stress and cognitive impairments caused by chronic hypobaric hypoxia. Furthermore, oral edaravone treatment also mitigated neuroinflammation and restored hippocampal neural stem cell exhaustion. Additionally, periostin (Postn) is vital in the cognitive deficits caused by chronic hypobaric hypoxia and may be a molecular target of edaravone. In conclusion, our results suggest that oxidative stress plays a crucial role in the cognitive deficits caused by chronic hypobaric hypoxia and that oral edaravone is a potential medicine for protecting against cognitive deficits caused by chronic hypobaric hypoxia in high-altitude areas.

Research on temperature rise performance of DC universal disconnect switch at high altitude

Abstract Low Voltage appliances are used more and more widely in high altitude areas, but the research on their temperature rise performance is still insufficient. Aiming at this problem, a high altitude temperature rise simulation model is established and verified by experiment, and the temperature rise performance is studied. Firstly, a DC universal isolation switch with a rated current of 1600A was used as the carrier to build an electro-thermal coupling calculation model of high-altitude temperature rise. Secondly, the temperature rise experiment of the isolation switch in high altitude environment was carried out to verify the effectiveness of the simulation model. Finally, the temperature fields of the DC universal isolation switch at different altitudes are simulated, and the change of convective heat transfer coefficient is calculated, and the temperature rise performance of the isolation switch at high altitudes is analyzed. With the increase of altitude, the temperature rise of the conductor is significantly higher than that of the insulation shell, and the heat dissipation capacity of the aluminum radiator decreases significantly at high altitude. The model and conclusion can provide reference for the use of low voltage electrical apparatus in high altitude environment.

Diversity of Orchid in Abies nephrolepis Nature Reserve in Shanxi, China.

Abies nephrolepis Nature Reserve has complex habitats and rich species diversity but lacks systematic ecological surveys. We focused on Orchid in Abies nephrolepis Nature Reserve, investigated and analyzed Orchid diversity and changes in community structure according to the characteristics of the alpine valleys in the study area, in terms of altitude gradient and habitat type, using the sample line method and the quadrat method. The results showed that 11 genera and 13 species of Orchidaceae were found in the survey, among which the species richness of Malaxis monophyllos was the highest, Neottia puberula was the second highest, and the species richness of Tulotis ussuriensis was the lowest, and the species with relative plurality ≥ 10% were Malaxis monophyllos (51.69%), Neottia puberula (14.77%), and Cypripedium guttatum (11.15%). The results of diversity analysis showed that Orchidaceae species were rich and the diversity index were the highest in the middle altitude area of 1950-2250 m; the distribution of Orchidaceae in the low altitude area was obviously clustered, and the similarity with the high altitude area was low. With the increase in altitude, the number of species showed an increase and then a decrease, showing a single-peak state, which was in line with the theory of "Intermediate altitude expansion hypothesis". The species and number of Orchidaceae in different habitats of Abies nephrolepis Nature Reserve also varied considerably, with Shannon-Wiener diversity index being the highest in EV4 (Abies nephrolepis + Picea meyeri + Picea wilsonii + Larix gmelinii var. principis-rupprechtii-Lonicera hispida-Carex lanceolata community) and EV5, and the smallest in EV1 habitats, Pielow evenness index being the highest in EV5 habitats and the lowest in EV1 habitats, and Simpson's index being the highest in EV5 habitats and the lowest in EV1 habitats. This study provides a scientific basis for strengthening regional monitoring of species diversity and protecting biodiversity.