The Didymellaceae is one of the most species-rich families in the fungal kingdom, and includes species that inhabit a wide range of ecosystems. The taxonomy of Didymellaceae has recently been revised ...on the basis of multi-locus DNA sequence data. In the present study, we investigated 108 Didymellaceae isolates newly obtained from 40 host plant species in 27 plant families, and various substrates from caves, including air, water and carbonatite, originating from Argentina, Australia, Canada, China, Hungary, Israel, Italy, Japan, South Africa, the Netherlands, the USA and former Yugoslavia. Among these, 68 isolates representing 32 new taxa are recognised based on the multi-locus phylogeny using sequences of LSU, ITS, rpb2 and tub2, and morphological differences. Within the Didymellaceae, five genera appeared to be limited to specific host families, with other genera having broader host ranges. In total 19 genera are recognised in the family, with Heracleicola being reduced to synonymy under Ascochyta. This study has significantly improved our understanding on the distribution and biodiversity of Didymellaceae, although the placement of several genera still need to be clarified.
When tunnels are excavated in karst areas, the existence of karst caves in the surrounding rock usually results in the collapse failure of tunnels. Tunnel collapse has always been a challenging issue ...because it seriously threatens the safety of tunnel builders. To investigate the collapse of a deep tunnel under a karst cave, we constructed the collapse mechanisms of the rectangular and circular tunnels under a karst cave, and obtained the expressions of the collapse failure in tunnel considering seismic force and seepage force by means of the variational principle and limit analysis theory. Compared with previous results and numerical solutions, it is found that the results in this paper are consistent with those results and numerical solutions, which indicates that the proposed method in this work is rational. According to the analytical solutions, the shape of the collapsing blocks of the deep rectangular and circular tunnels under a karst cave are drawn, and the effects of different parameters, especially the vertical seismic coefficient kv, on the collapsing blocks are analyzed. The findings in this paper indicate that the range of collapsing blocks decreases with increased kv. The two formulas for calculating the critical height between the tunnel and the karst cave are given by derivation.
Due to insufficient research on the collapsing range of karst rectangular and circular tunnels:•We constructed a new failure mechanism of rectangular and circular tunnels under a karst cave.•The effect of seismic force is considered in this paper.•The expressions of the collapsing block of deep tunnels under a karst cave can be obtained.•The influence of various parameters on the collapsing range is demonstrated.
This paper investigates the dynamic responses of bottom karst caves on the shield tunnels under oblique SV waves according to the project of Dalian Metro Line 5. The viscous-spring artificial ...boundaries are employed and validated to assure the accuracy of seismic input. The characteristics of deformation and stress, damage evolution process and damage state of the tunnel are discussed, such as under different filling conditions of karst caves, incident angles of SV waves, the elastic modulus of grouting materials, and the combination of multiple karst caves. According to the relationship between tensile damage value and crack width, the damage state classification is divided. The results show that the tunnel’s displacement and stress increase and the damage state is from no damage to severe damage with the increasing incident angle. When the incident angle is 30°, the tunnel’s displacement and stress reach to the maximum, and the axial cracks width higher than 0.2 mm appear on the outer surface of the vault and bottom. The filling conditions of the bottom karst caves can influence the tunnel’s circumferential damage. The structural dynamic response does not change significantly when the elastic modulus of the grouting material is greater than 10 GPa. Compared with one single cave, the damage severity of the inner surface under the multiple karst caves with a large clear distance is weakened and tends to be averaged.
Prior research on excavation in dense karst cave foundation pits has primarily concentrated on evaluating the localized spatio-temporal influence and isolated geological factors. Nonetheless, this ...approach oversimplifies modeling conditions, thereby limiting its ability to provide a comprehensive understanding of the vertical displacement field. Consequently, this oversimplification can inflate the safety factor and increase project costs. Therefore, we propose a feedforward neural network (FNN), updated with the loop nested optimal iterative method (LNOIM), which incorporates the spatiotemporal characteristics of monitoring points and geological factors to analyze the engineering sensitivity of karst caves. Ultimately, the global foundation pit vertical displacement field was obtained. Our method has been demonstrated to be effective in a foundation pit in South China ((P value) P > 0.050, Cohen's d < 0.200). Furthermore, it has been validated in other cases ((Root Mean Square Error) RMSE = 1.576–2.916). This work provides a new perspective on the accurate reflection of the global vertical displacement state of a foundation pit. Additionally, it enhances the ability to sensitively identify caves in dense karst cave areas, thereby improving the safety of foundation pit works.
Abstract
This study was part of a preliminary safety assessment for a real project of existing bridge piles passing through beaded karst caves threatened by a nearby newly built embankment. To ...investigate the severity of the effect of the embankment on the performance of these piles, a series of reduced-scale model experiments of piles considering different cave numbers (n = 0, 1, 2, and 3) near surcharge loads were designed with a similarity ratio of 1:35. Two phases of loading, the vertical loading atop the pile and nearby surcharge loading, were imposed successively to explore the vertical bearing characteristic and lateral response characteristic of the piles passing through beaded karst caves. The effects of cave number, vertical load atop the pile, and nearby surcharge load on the responses of pile and soil were clarified and several fitting functions were presented to characterize the variations of responses with different cave numbers and nearby surcharge loads. The results and conclusions can provide a reference for the design and safety assessment of bridge piles in karst terrains.
Palaeolithic cave art in Borneo Aubert, M; Setiawan, P; Oktaviana, A A ...
Nature (London),
12/2018, Letnik:
564, Številka:
7735
Journal Article
Recenzirano
Figurative cave paintings from the Indonesian island of Sulawesi date to at least 35,000 years ago (ka) and hand-stencil art from the same region has a minimum date of 40 ka
. Here we show that ...similar rock art was created during essentially the same time period on the adjacent island of Borneo. Uranium-series analysis of calcium carbonate deposits that overlie a large reddish-orange figurative painting of an animal at Lubang Jeriji Saléh-a limestone cave in East Kalimantan, Indonesian Borneo-yielded a minimum date of 40 ka, which to our knowledge is currently the oldest date for figurative artwork from anywhere in the world. In addition, two reddish-orange-coloured hand stencils from the same site each yielded a minimum uranium-series date of 37.2 ka, and a third hand stencil of the same hue has a maximum date of 51.8 ka. We also obtained uranium-series determinations for cave art motifs from Lubang Jeriji Saléh and three other East Kalimantan karst caves, which enable us to constrain the chronology of a distinct younger phase of Pleistocene rock art production in this region. Dark-purple hand stencils, some of which are decorated with intricate motifs, date to about 21-20 ka and a rare Pleistocene depiction of a human figure-also coloured dark purple-has a minimum date of 13.6 ka. Our findings show that cave painting appeared in eastern Borneo between 52 and 40 ka and that a new style of parietal art arose during the Last Glacial Maximum. It is now evident that a major Palaeolithic cave art province existed in the eastern extremity of continental Eurasia and in adjacent Wallacea from at least 40 ka until the Last Glacial Maximum, which has implications for understanding how early rock art traditions emerged, developed and spread in Pleistocene Southeast Asia and further afield.
•A biofilm-like microbial community from a pristine cave in New Guinea was studied.•Metagenomic analyses revealed the predominance of Proteobacteria and Actinobacteria.•Chemoorganotrophy was the main ...metabolism of microbial community members.•Antibiotic resistance was predicted by metagenome analysis and confirmed in vitro.•Several unassignable taxonomic entities were isolated from the community.
Caves are extreme environments inhabited by microbial communities adapted to thrive oligotrophic conditions. Cave microbes are organised in complex ecological networks and have developed survival strategies involving the production and release of a large variety of secondary metabolites, including antibiotic-like compounds. In this study, the structure and the metabolic features of a biofilm-like microbial community lining the walls of a pristine karst cavity (the Yumugi river cave) located in a remote region of the Western New Guinea were investigated. 16S rRNA and shotgun sequence analyses highlighted the prevalence of chemoorganotrophic phyla (Proteobacteria, Actinobacteria, Firmicutes and Acidobacteria), consistent with metabolic predictions inferred from the cave metagenome analysis. Few clinically relevant antimicrobial resistance genes were detected. A culture-based approach allowed the isolation of some heterotrophic members of the bacterial community, and antimicrobial susceptibility testing revealed an overall high level of resistance to different antimicrobials classes. Isolates presumptively representing new uncharacterized members of genus Pseudomonas displayed interesting antibiotic properties against Gram-positive indicator strains. Our work supports the hypothesis that caves represent a reservoir for new bacterial species and drug discovery research.
Coal is the major energy source in China. Many coal mines in Southwest China have arranged the excavation roadway system in the Maokou limestone in coal seam floor because of its special ...hydrogeological conditions. Since karst is widely distributed in Maokou limestone and water-filled karst caves are also developed commonly there, once a strongly water-filled karst cave is exposed during roadway excavation, the water inrush disaster occurs easily. In order to reveal the phenomenon of water inrush disasters from covered karst caves more effectively, the water inrush that occurred during the roadway excavation process of Jiyuan coal mine in northern Guizhou was taken as a research object in this study. Based on the regional geological structure, the hydrogeological condition and the fluid-structure interaction theory, a fluid-structure interaction model of water inrush in the roadway excavation was established, and variation laws of stress field, displacement field and seepage field of surrounding rock during the process of water inrush from karst cave were analyzed. Besides, the influence of different geological conditions on water inrush from karst cave was discussed from aspects of the size of karst cave, the water pressure of karst cave and the thickness of aquiclude.
Lampenflora as a result of karst cave equipment for excursions Pichugina, Elizaveta K.; Mazina, Svetlana E.
Vestnik Rossijskogo universiteta družby narodov. Seriâ Èkologiâ i bezopasnostʹ žiznedeâtelʹnosti,
09/2022, Letnik:
30, Številka:
3
Journal Article
Recenzirano
Odprti dostop
This review is devoted to the problem of the development of “lampenflora” - phototrophic fouling communities in karst caves’ areas with artificial lighting used for tourism purposes. The experience ...of domestic and foreign colleagues helps to understand the causes of its occurrence, the conditions for the formation and development of communities; describes the mechanisms of adaptation of individual species and communities to the complex conditions of underground ecosystems. Lampenflora is not typical for the cave environment, and in this regard, the adverse consequences of its presence are found in the form of an impact on the local biota and abiotic parameters of the environment. The review compares lampenflora and natural communities of phototrophs in the entrance zones of caves illuminated by sunlight.