History, advancements, and perspective of biological research in deep-underground laboratories: A brief review

[Effects of Extreme Environments on Human Sleep]

Recently, with the rapid growth of the global population and the exhaustion of resources, exploration activities in extreme environments such as the polar regions, the outer space, the deep sea, the deep underground and highlands are becoming increasingly more frequent. This in-depth exploration of the external environment and the consequent dramatic changes in lifestyles impact on sleep, a basic life activity of humans, in ways that cannot be overlooked. the basic life activity of human beings. Sleep, a basic life activity and the result of the evolution of organisms to adapt to their environment, is closely associated with sleep homeostasis and endogenous rhythms. However, external environmental changes and lifestyle shifts in extreme environments have had a significant impact on the patterns and the quality of sleep in humans. Furthermore, this impact can lead to many physiological and psychological problems, posing a great threat to human health. In this review, we delved into the specific effects of different extreme natural environments and enclosed environments on sleep, elaborating on how these environments alter the patterns and the quality of sleep in humans. In addition, we summarized the changes in human sleep under extreme environments to help gain a better understanding of the mechanisms by which these specific environments impact human sleep. It is expected that this review will provide a solid theoretical foundation for optimizing long-term survival strategies in extreme environments and help humans adapt to and overcome the challenges posed by extreme environments more effectively.

Protracted Exposure to a Sub-background Radiation Environment Negatively Impacts the Anhydrobiotic Recovery of Desiccated Yeast Sentinels

ABSTRACT

Experiments that examine the impacts of subnatural background radiation exposure provide a unique approach to studying the biological effects of low-dose radiation. These experiments often need to be conducted in deep underground laboratories in order to filter surface-level cosmic radiation. This presents some logistical challenges in experimental design and necessitates a model organism with minimal maintenance. As such, desiccated yeast ( Saccharomyces cerevisiae ) is an ideal model system for these investigations. This study aimed to determine the impact of prolonged sub-background radiation exposure in anhydrobiotic (desiccated) yeast at SNOLAB in Sudbury, Ontario, Canada. Two yeast strains were used: a normal wild type and an isogenic recombinational repair-deficient rad51 knockout strain ( rad51 Δ). Desiccated yeast samples were stored in the normal background surface control laboratory (68.0 nGy h -1 ) and in the sub-background environment within SNOLAB (10.1 nGy h -1 ) for up to 48 wk. Post-rehydration survival, growth rate, and metabolic activity were assessed at multiple time points. Survival in the sub-background environment was significantly reduced by a factor of 1.39 and 2.67 in the wild type and rad51 ∆ strains, respectively. Post-rehydration metabolic activity measured via alamarBlue reduction remained unchanged in the wild type strain but was 26% lower in the sub-background rad51 ∆ strain. These results demonstrate that removing natural background radiation negatively impacts the survival and metabolism of desiccated yeast, highlighting the potential importance of natural radiation exposure in maintaining homeostasis of living organisms.

Progress in biological and medical research in the deep underground: an update

As the growing population of individuals residing or working in deep underground spaces for prolonged periods, it has become imperative to understand the influence of factors in the deep underground environment (DUGE) on living systems. Heping Xie has conceptualized the concept of deep underground medicine to identify factors in the DUGE that can have either detrimental or beneficial effects on human health. Over the past few years, an increasing number of studies have explored the molecular mechanisms that underlie the biological impacts of factors in the DUGE on model organisms and humans. Here, we present a summary of the present landscape of biological and medical research conducted in deep underground laboratories and propose promising avenues for future investigations in this field. Most research demonstrates that low background radiation can trigger a stress response and affect the growth, organelles, oxidative stress, defense capacity, and metabolism of cells. Studies show that residing and/or working in the DUGE has detrimental effects on human health. Employees working in deep mines suffer from intense discomfort caused by high temperature and humidity, which increase with depth, and experience fatigue and sleep disturbance. The negative impacts of the DUGE on human health may be induced by changes in the metabolism of specific amino acids; however, the cellular pathways remain to be elucidated. Biological and medical research must continue in deep underground laboratories and mines to guarantee the safe probing of uncharted depths as humans utilize the deep underground space.

The REPAIR Project, a Deep-Underground Radiobiology Experiment Investigating the Biological Effects of Natural Background Radiation: The First 6 Years

In 2017, a special edition of Radiation Research was published [Oct; Vol. 188 4.2 (https://bioone.org/journals/radiation-research/volume-188/issue-4.2)] which focused on a recently established radiobiology project within SNOLAB, a unique deep-underground research facility. This special edition included original articles, reviews and commentaries relevant to the research goals of this new project which was titled Researching the Effects of the Presence and Absence of Ionizing Radiation (REPAIR). These research goals were founded in understanding the biological effects of terrestrial and cosmic natural background radiation (NBR). Since 2017, REPAIR has evolved into a sub-NBR radiobiology research program which investigates these effects using multiple model systems and various biological endpoints. This paper summarizes the evolution of the REPAIR project over the first 6-years including its experimental scope and capabilities as well as research accomplishments.

Urine metabolomics analysis of sleep quality in deep-underground miners: A pilot study

Background

In previous questionnaire surveys of miners, sleep disorders were found among underground workers. The influence of the special deep-underground environment and its potential mechanism are still unclear. Therefore, this study intends to utilize LC-MS metabolomics to study the potential differences between different environments and different sleep qualities.

Methods

Twenty-seven miners working at 645-1,500 m deep wells were investigated in this study, and 12 local ground volunteers were recruited as the control group. The Pittsburgh Sleep Quality Index (PSQI) was used to examine and evaluate the sleep status of the subjects in the past month, and valuable basic information about the participants was collected. PSQI scores were obtained according to specific calculation rules, and the corresponding sleep grouping and subsequent analysis were carried out. Through liquid chromatography-mass spectrometry (LC-MS) non-targeted metabolomics analysis, differences in metabolism were found by bioinformatics analysis in different environments.

Results

Between the deep-underground and ground (DUvsG) group, 316 differential metabolites were identified and 125 differential metabolites were identified in the good sleep quality vs. poor sleep quality (GSQvsPSQ) group. The metabolic pathways of Phenylalanine, tyrosine and tryptophan biosynthesis (p = 0.0102) and D-Glutamine and D-glutamate metabolism (p = 0.0241) were significantly enriched in DUvsG. For GSQvsPSQ group, Butanoate metabolism was statistically significant (p = 0.0276). L-Phenylalanine, L-Tyrosine and L-Glutamine were highly expressed in the deep-underground group. Acetoacetic acid was poorly expressed, and 2-hydroxyglutaric acid was highly expressed in good sleep quality.

Conclusions

The influence of the underground environment on the human body is more likely to induce specific amino acid metabolism processes, and regulate the sleep-wake state by promoting the production of excitatory neurotransmitters. The difference in sleep quality may be related to the enhancement of glycolytic metabolism, the increase in excitatory neurotransmitters and the activation of proinflammation. L-phenylalanine, L-tyrosine and L-glutamine, Acetoacetic acid and 2-hydroxyglutaric acid may be potential biomarkers correspondingly.

An endeavor of "deep-underground agriculture": storage in a gold mine impacts the germination of canola (Brassica napus L.) seeds

Exploring and utilizing the agronomic potential of deep-underground is one of the ways to cope with the challenges of sudden environmental change on agriculture. Understanding the effects of environmental stresses on the morphological and physiological indicators of crop seeds after their storage deep-underground is crucial to developing and implementing strategies for agriculture in the deep-underground space. In this study, we stored canola seeds in tunnels with horizontal depths of 0, 240, 690, and 1410 m in a gold mine. Seeds in envelopes were retrieved at 42, 66, 90, and 227 days of storage, whereas seeds in sealed packages were retrieved at 66 and 227 days of storage. The germination tests were conducted to investigate the effects of storage depth, duration, and packing method on stored and non-stored seeds. Results showed that increased depth and duration reduced seed germination rate, with the germination and vigor indexes also descending to varying degrees. Increased hypocotyl length and biomass accumulation suggested that deep-underground environment had a more significant compensatory effect on seed germination. For all indicators, the performance of seeds sealed in packages was superior to those stored in envelopes. Regression analysis showed that it was difficult to obtain the optimal value of each indicator simultaneously. The successful germination experiment foreshadowed the possibilities of deep-underground agriculture in the future.

Reduced Environmental Dose Rates Are Responsible for the Increased Susceptibility to Radiation-Induced DNA Damage in Larval Neuroblasts of Drosophila Grown inside the LNGS Underground Laboratory

A large amount of evidence from radiobiology studies carried out in Deep Underground Laboratories support the view that environmental radiation may trigger biological mechanisms that enable both simple and complex organisms to cope with genotoxic stress. In line with this, here we show that the reduced radiation background of the LNGS underground laboratory renders Drosophila neuroblasts more sensitive to ionizing radiation-induced (but not to spontaneous) DNA breaks compared to fruit flies kept at the external reference laboratory. Interestingly, we demonstrate that the ionizing radiation sensitivity of flies kept at the LNGS underground laboratory is rescued by increasing the underground gamma dose rate to levels comparable to the low-LET reference one. This finding provides the first direct evidence that the modulation of the DNA damage response in a complex multicellular organism is indeed dependent on the environmental dose rate.

Whole Transcriptome Analysis Revealed a Stress Response to Deep Underground Environment Conditions in Chinese Hamster V79 Lung Fibroblast Cells

Background: Prior studies have shown that the proliferation of V79 lung fibroblast cells could be inhibited by low background radiation (LBR) in deep underground laboratory (DUGL). In the current study, we revealed further molecular changes by performing whole transcriptome analysis on the expression profiles of long non-coding RNA (lncRNA), messenger RNA (mRNA), circular RNA (circRNA) and microRNA (miRNA) in V79 cells cultured for two days in a DUGL.

Methods: Whole transcriptome analysis including lncRNA, mRNAs, circ RNA and miRNA was performed in V79 cells cultured for two days in DUGL and above ground laboratory (AGL), respectively. The differentially expressed (DE) lncRNA, mRNA, circRNA, and miRNA in V79 cells were identified by the comparison between DUGL and AGL groups. Quantitative real-time polymerase chain reaction(qRT-PCR)was conducted to verify the selected RNA sequencings. Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway was analyzed for the DE mRNAs which enabled to predict target genes of lncRNA and host genes of circRNA.

Results: With |log₂(Fold-change)| ≥ 1.0 and p < 0.05, a total of 1257 mRNAs (353 mRNAs up-regulated, 904 mRNAs down-regulated), 866 lncRNAs (145 lncRNAs up-regulated, 721 lncRNAs down-regulated), and 474 circRNAs (247 circRNAs up-regulated, 227 circRNAs down-regulated) were significantly altered between the two groups. There was no significant difference in miRNA between the two groups. The altered RNA profiles were mainly discovered in lncRNAs, mRNAs and circRNAs. DE RNAs were involved in many pathways including ECM-RI, PI3K-Akt signaling, RNA transport and the cell cycle under the LBR stress of the deep underground environment.

Conclusion: Taken together, these results suggest that the LBR in the DUGL could induce transcriptional repression, thus reducing metabolic process and reprogramming the overall gene expression profile in V79 cells.

Origin, distribution, and perspective health benefits of particulate matter in the air of underground salt mine: a case study from Bochnia, Poland

The composition and distribution of airborne particles in different locations in a salt mine were determined in terms of their origin, the distance from the air inlet, and the adaptation of post-mining chambers and corridors for tourists and general audience. The composition of aerosols in air was also evaluated from the perspective of human health. Air samples were collected on filters by using portable air pumps, in a historical underground salt mine in Bochnia (Poland), which is currently a touristic and recreation attraction and sanatorium. The particulate matter (PM) concentration was determined using the gravimetric method by weighing quartz filters. The content of carbon, water-soluble constituents, trace elements, and minerals was also determined. A genetic classification of the suspended matter was proposed and comprised three groups: geogenic (fragments of rock salt and associated minerals from the deposit), anthropogenic (carbon-bearing particles from tourist traffic and small amounts of fly ash, soot, and rust), and biogenic particles (occasional pollen). The total PM concentration in air varied between 21 and 79 μg/m³ (with PM₄ constituting 4-24 μg/m³). The amount of atmospheric dust components coming from the surface was low and decreased with the distance from the intake shaft, thus indicating the self-cleaning process. NaCl dominated the water-soluble constituents, while Fe, Al, Ag, Mn, and Zn dominated the trace elements, with the concentration of majority of them below 30 ng/m³. These metals are released into air from both natural sources and the wear or/and corrosion of mining and tourists facilities in the underground functional space. No potentially toxic elements or constituents were detected. The presence of salt particles and salty spray in the atmosphere of salt mine, which may have anti-inflammatory and antiallergic properties, is beneficial to human health. This study will allow for a broader look at the potential of halotherapy in underground salt mines from a medical and regulatory point of view.

Mineralogical and Chemical Tracing of Dust Variation in an Underground Historic Salt Mine

The aim of this study was to investigate the causes of the evolution of atmospheric dust composition in an open-to-public subterranean site (UNESCO-recognized historic mine) at increasing distances from the air intake. The role of the components imported with atmospheric air from the surface was compared with natural and anthropogenic sources of dust from inside the mine. Samples of deposited dust were directly collected from flat surfaces at 11 carefully selected sites. The morphological, mineralogical, and chemical characteristics were obtained using scanning electron microscopy (SEM), X-ray diffraction (XRD), and inductively coupled plasma spectroscopy (ICP). The study showed that the air in the underground salt mine was free of pollutants present in the ambient air on the surface. Most of the components sucked into the mine by the ventilation system from the surface (regular dust, particulate matter, gaseous pollutants, biogenic particles, etc.) underwent quick and instantaneous sedimentation in the close vicinity of the air inlet to the mine. The dust settled in the mine interior primarily consisted of natural geogenic particles, locally derived from the weathering of the host rock (halite, anhydrite, and aluminosilicates). This was confirmed by low values of enrichment factors (EF) calculated for minor and trace elements. Only one site, due to the tourist railroad and the associated local intensive tourist traffic, represented the anthropogenic sources of elevated concentrations of ferruginous particles and accompanied metals (P, Cr, Mn, Co, Ni, Cu, As, Mo, Cd, Sn, Sb, Pb, and W). The gravitational deposition of pollutants from these sources limits the effects of the emissions to the local range. The used methodology and the results are universal and might also apply to other mines, caves, or underground installations used for museums, tourists, or speleotherapeutic purposes.

Environmental radiobiology of amphibians - knowledge gaps to be filled using cell lines

Amphibians are facing an unprecedented level of population declines worldwide. The causes run the gamut from habitat loss and succumbing to opportunistic pathogen infections to vulnerability to toxic pollutants and ultraviolet (UV)-B radiation exposure. Anthropogenic activities including Chernobyl and Fukushima nuclear disasters and radioactive waste leakage into the environment raise the background radiation levels. Their immediate and chronic effects on amphibian populations are still being studied. However, the literature on environmental radiation effects on amphibian health still requires a lot more work. Laboratory and field works need to be conducted hand in hand in order to make informative and conclusive analyses to distinguish bad from good and harm from risk or to argue for or against the linear no-threshold model in radioprotection programs. Amphibian cell lines can help seek answers to important questions pertaining environmental radiobiology and amphibian health wherever they can suitably and effectively. The purpose of this work is to show that amphibian cell lines can 'rescue' important knowledge gaps in the literature, especially in the low-dose radiation mechanisms. Presently, there are 142 amphibian cell lines developed from six urodelans and 17 anurans. Amphibian cell lines can help expand and enrich the limited literature on environmental radiation effects on amphibians. They can be used to study mechanisms of radiation actions and discover reliable biomarkers for low-dose exposure. They can be used in environmental radiation monitoring and radioprotection programs. They can be used to determine the effects of co-exposure of IR and other stressors in the environment on amphibian health. They represent an ethical choice for amphibian conservation efforts in the current global amphibian declines. Lessons learned from cellular data can be useful guides to gain a better picture of effects occurring at the amphibian population and ecosystem levels.

The Response of Living Organisms to Low Radiation Environment and Its Implications in Radiation Protection

Life has evolved on Earth for about 4 billion years in the presence of the natural background of ionizing radiation. It is extremely likely that it contributed, and still contributes, to shaping present form of life. Today the natural background radiation is extremely small (few mSv/y), however it may be significant enough for living organisms to respond to it, perhaps keeping memory of this exposure. A better understanding of this response is relevant not only for improving our knowledge on life evolution, but also for assessing the robustness of the present radiation protection system at low doses, such as those typically encountered in everyday life. Given the large uncertainties in epidemiological data below 100 mSv, quantitative evaluation of these health risk is currently obtained with the aid of radiobiological models. These predict a health detriment, caused by radiation-induced genetic mutations, linearly related to the dose. However a number of studies challenged this paradigm by demonstrating the occurrence of non-linear responses at low doses, and of radioinduced epigenetic effects, i.e., heritable changes in genes expression not related to changes in DNA sequence. This review is focused on the role that epigenetic mechanisms, besides the genetic ones, can have in the responses to low dose and protracted exposures, particularly to natural background radiation. Many lines of evidence show that epigenetic modifications are involved in non-linear responses relevant to low doses, such as non-targeted effects and adaptive response, and that genetic and epigenetic effects share, in part, a common origin: the reactive oxygen species generated by ionizing radiation. Cell response to low doses of ionizing radiation appears more complex than that assumed for radiation protection purposes and that it is not always detrimental. Experiments conducted in underground laboratories with very low background radiation have even suggested positive effects of this background. Studying the changes occurring in various living organisms at reduced radiation background, besides giving information on the life evolution, have opened a new avenue to answer whether low doses are detrimental or beneficial, and to understand the relevance of radiobiological results to radiation protection.

Underground Radiobiology: A Perspective at Gran Sasso National Laboratory

Scientific community and institutions (e. g., ICRP) consider that the Linear No-Threshold (LNT) model, which extrapolates stochastic risk at low dose/low dose rate from the risk at moderate/high doses, provides a prudent basis for practical purposes of radiological protection. However, biological low dose/dose rate responses that challenge the LNT model have been highlighted and important dowels came from radiobiology studies conducted in Deep Underground Laboratories (DULs). These extreme ultra-low radiation environments are ideal locations to conduct below-background radiobiology experiments, interesting from basic and applied science. The INFN Gran Sasso National Laboratory (LNGS) (Italy) is the site where most of the underground radiobiological data has been collected so far and where the first in vivo underground experiment was carried out using Drosophila melanogaster as model organism. Presently, many DULs around the world have implemented dedicated programs, meetings and proposals. The general message coming from studies conducted in DULs using protozoan, bacteria, mammalian cells and organisms (flies, worms, fishes) is that environmental radiation may trigger biological mechanisms that can increase the capability to cope against stress. However, several issues are still open, among them: the role of the quality of the radiation spectrum in modulating the biological response, the dependence on the biological endpoint and on the model system considered, the overall effect at organism level (detrimental or beneficial). At LNGS, we recently launched the RENOIR experiment aimed at improving knowledge on the environmental radiation spectrum and to investigate the specific role of the gamma component on the biological response of Drosophila melanogaster.

Interactive Effects of Light and Nitrogen on Pakchoi (Brassica chinensis L.) Growth and Soil Enzyme Activity in an Underground Environment

Light conditions and nitrogen fertilizer are crucial for plant growth, especially in the underground situations without sunlight and nitrogen deposition. In this paper, the effects of photoperiod (12 h and 16 h lighting time per day), light intensity (200, 300 and 400 μmol m−2 s−1) and nitrogen addition (0, 0.15, 0.3 and 0.45 g N kg−1 soil) on pakchoi growth and specific soil enzyme activity were investigated. The results demonstrated that there were strong interactive effects of light intensity and nitrogen addition on plant yield. The plant yield changed parabolically with increasing nitrogen addition when a light intensity was given between 200 and 300 μmol m−2 s−1, while the yield decreased linearly with increasing nitrogen application under the light intensity of 400 μmol m−2 s−1. The combination of 16 h photoperiod, 300 μmol m−2 s−1 light intensity and 0.3 g N kg−1 soil nitrogen addition was the best for pakchoi growth. The investigation of soil enzyme showed that the activity of urease responded negatively to nitrogen addition, whereas the activity of phosphatase had positive correlation with light intensity but was not affected by nitrogen addition. Our results suggested that the toxic effect of excessive nitrogen was a better explanation for the interactive effects of light and nitrogen than the plant-microbe interaction framework. The critical toxicity level of nitrogen for pakchoi was determined and showed negative correlation with light intensity.

Proteomic Characterization of Proliferation Inhibition of Well-Differentiated Laryngeal Squamous Cell Carcinoma Cells Under Below-Background Radiation in a Deep Underground Environment

Background: There has been a considerable concern about cancer induction in response to radiation exposure. However, only a limited number of studies have focused on the biological effects of below-background radiation (BBR) in deep underground environments. To improve our understanding of the effects of BBR on cancer, we studied its biological impact on well-differentiated laryngeal squamous cell carcinoma cells (FD-LSC-1) in a deep underground laboratory (DUGL). Methods: The growth curve, morphological, and quantitative proteomic experiments were performed on FD-LSC-1 cells cultured in the DUGL and above-ground laboratory (AGL). Results: The proliferation of FD-LSC-1 cells from the DUGL group was delayed compared to that of cells from the AGL group. Transmission electron microscopy scans of the cells from the DUGL group indicated the presence of hypertrophic endoplasmic reticulum (ER) and a higher number of ER. At a cutoff of absolute fold change ≥ 1.2 and p < 0.05, 807 differentially abundant proteins (DAPs; 536 upregulated proteins and 271 downregulated proteins in the cells cultured in the DUGL) were detected. KEGG pathway analysis of these DAPs revealed that seven pathways were enriched. These included ribosome (p < 0.0001), spliceosome (p = 0.0001), oxidative phosphorylation (p = 0.0001), protein export (p = 0.0001), thermogenesis (p = 0.0003), protein processing in the endoplasmic reticulum (p = 0.0108), and non-alcoholic fatty liver disease (p = 0.0421). Conclusion: The BBR environment inhibited the proliferation of FD-LSC-1 cells. Additionally, it induced changes in protein expression associated with the ribosome, gene spliceosome, RNA transport, and energy metabolism among others. The changes in protein expression might form the molecular basis for proliferation inhibition and enhanced survivability of cells adapting to BBR exposure in a deep underground environment. RPL26, RPS27, ZMAT2, PRPF40A, SNRPD2, SLU7, SRSF5, SRSF3, SNRPF, WFS1, STT3B, CANX, ERP29, HSPA5, COX6B1, UQCRH, and ATP6V1G1 were the core proteins associated with the BBR stress response in cells.

Oxidative Stress From Exposure to the Underground Space Environment

There are a growing number of people entering underground spaces. However, underground spaces have unique environmental characteristics, and little is known about their effects on human health. It is crucial to elucidate the effects of the underground space environment on the health of humans and other organisms. This paper reviews the effects of hypoxia, toxic atmospheric particles, and low background radiation in the underground space environment on living organisms from the perspective of oxidative stress. Most studies have revealed that living organisms maintained in underground space environments exhibit obvious oxidative stress, which manifests as changes in oxidants, antioxidant enzyme activity, genetic damage, and even disease status. However, there are few relevant studies, and the pathophysiological mechanisms have not been fully elucidated. There remains an urgent need to focus on the biological effects of other underground environmental factors on humans and other organisms as well as the underlying mechanisms. In addition, based on biological research, exploring means to protect humans and living organisms in underground environments is also essential.

Proteomics provides insights into the inhibition of Chinese hamster V79 cell proliferation in the deep underground environment

As resources in the shallow depths of the earth exhausted, people will spend extended periods of time in the deep underground space. However, little is known about the deep underground environment affecting the health of organisms. Hence, we established both deep underground laboratory (DUGL) and above ground laboratory (AGL) to investigate the effect of environmental factors on organisms. Six environmental parameters were monitored in the DUGL and AGL. Growth curves were recorded and tandem mass tag (TMT) proteomics analysis were performed to explore the proliferative ability and differentially abundant proteins (DAPs) in V79 cells (a cell line widely used in biological study in DUGLs) cultured in the DUGL and AGL. Parallel Reaction Monitoring was conducted to verify the TMT results. γ ray dose rate showed the most detectable difference between the two laboratories, whereby γ ray dose rate was significantly lower in the DUGL compared to the AGL. V79 cell proliferation was slower in the DUGL. Quantitative proteomics detected 980 DAPs (absolute fold change ≥ 1.2, p < 0.05) between V79 cells cultured in the DUGL and AGL. Of these, 576 proteins were up-regulated and 404 proteins were down-regulated in V79 cells cultured in the DUGL. KEGG pathway analysis revealed that seven pathways (e.g. ribosome, RNA transport and oxidative phosphorylation) were significantly enriched. These data suggest that proliferation of V79 cells was inhibited in the DUGL, likely because cells were exposed to reduced background radiation. The apparent changes in the proteome profile may have induced cellular changes that delayed proliferation but enhanced survival, rendering V79 cells adaptable to the changing environment.

A Comprehensive Set of Cooling Measures for the Overall Control and Reduction of High Temperature-Induced Thermal Damage in Oversize Deep Mines: A Case Study

The mining process in deep mines occurs at elevated temperatures and thus is significantly jeopardized by the thermal damage. In this study, the main factors causing high-temperatures under particular mining geological and prevailing conditions of coal mine production, namely for the Longgu Coal Mine (LCM) in Shandong Province of China, were specified and analyzed in detail. This included exothermic heat from the surrounding rock of an underground roadway, inflow of high-temperature water, seasonal temperature rise, mechanical and electrical equipment operation, and airflow compression in the mine. The integrated artificial cooling mode was implemented on the basis of the original normal ventilation and cooling facilities of the LCM, which involved cooling by mobile refrigeration units, water source heat pump refrigeration units, and a ground centralized ice-cooling radiation system, as well as the underground centralized cooling system provided by Wärme-Austausch-Technik (WAT) GmbH. Eventually, a comprehensive set of measures for the overall control and reduction of high-temperature-induced damage was realized, which ensured more effective cooling of the LCM. Thus, the average temperature of the main operation sites was reduced by 8 K, while that of the underground working faces was maintained at 299.15 K. These measures also resulted in excellent technical and economic benefits: the total three-year increase in revenue and savings reached 76.3 million USD, hence relevant findings of the study are expected to provide technical guidance on the treatment of high-temperature-induced damage in deep mines.

Physical symptoms and mental health status in deep underground miners: A cross-sectional study

The aim of the present study was to reveal the physical symptom changes and their correlations with mental health status in deep underground miners.A total of 286 deep underground miners completed a cross-sectional questionnaire study at China Pingmei Shenma mine complex. The questionnaire included sociodemographics, self-reported physical symptoms, underground adverse environmental factors, and the Symptom Checklist-90-Revised (SCL-90-R). Five environmental parameters of 1 deep mine were also measured.Data from 266 valid questionnaires were analyzed. The 3 most frequent complaints about underground adverse conditions were moisture [62.03% (165/266)], dim light [45.86% (122/266)], and high temperature [42.11% (112/266)]. Fatigue [40.22% (107/266)], hearing loss [34.96% (93/266)], and tinnitus [31.58% (84/266)] were reported to be the three most common physical symptoms. Insomnia was reported in 204 participants (76.69%) mainly due to the difficulty of falling asleep [42.35% (84/204)] and dreams [39.70% (81/204)]. Mean scores of SCL-90-R subscales including somatization, anxiety, phobic anxiety, psychoticism, and paranoid ideation were elevated compared to Chinese norms, while there was diminished interpersonal sensitivity. Univariate analyses indicated that the 3 most common physical symptoms were associated with poorer SCL-90-R scores. With increasing depth below ground, air pressure, relative humidity, CO2 concentration and temperature rose, while total gamma radiation dose-rate decreased.The physical and mental health status of deep underground miners was poorer than the general Chinese male population. Some adverse environmental factors were identified that may have influenced health status. Measures are suggested to improve the deep underground working environment.