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A part's mechanical life span significantly depends on its microstructure, residual stress state and material hardness. Current research shows that the mechanical surface-strengthening process of deep-rolling is a suitable method for the alteration of surface and subsurface properties with the aim of increasing strength and life span of highly stressed components. Further increase in the mechanical life span can be reached using the turning process temperature while deep-rolling. For this purpose, a turn-rolling tool has been developed. Especially concerning soft machining operations, the induced process temperatures lead to higher degrees of plastic deformation in the subsurface of the material. This results in lower surface roughness, higher hardness and an optimal residual stress state. Furthermore, the turn-rolling process leads to positive properties regarding the part's microstructure because of the increased elastic and plastic deformations in the subsurface thanks to the combination of thermo-mechanical interactions within the material. [ABSTRACT FROM AUTHOR]

Desert environments constitute one of the largest and yet most fragile ecosystems on Earth. Under the absence of regular precipitation, microorganisms are the main ecological component mediating nutrient fluxes by using soil components, like minerals and salts, and atmospheric gases as a source for energy and water. While most of the previous studies on microbial ecology of desert environments have focused on surface environments, little is known about microbial life in deeper sediment layers. Our study is extending the limited knowledge about microbial communities within the deeper subsurface of the hyperarid core of the Atacama Desert. By employing intracellular DNA extraction and subsequent 16S rRNA sequencing of samples collected from a soil pit in the Yungay region of the Atacama Desert, we unveiled a potentially viable microbial subsurface community residing at depths down to 4.20 m. In the upper 80 cm of the playa sediments, microbial communities were dominated by Firmicutes taxa showing a depth-related decrease in biomass correlating with increasing amounts of soluble salts. High salt concentrations are possibly causing microbial colonization to cease in the lower part of the playa sediments between 80 and 200 cm depth. In the underlying alluvial fan deposits, microbial communities reemerge, possibly due to gypsum providing an alternative water source. The discovery of this deeper subsurface community is reshaping our understanding of desert soils, emphasizing the need to consider subsurface environments in future explorations of arid ecosystems., (© The Author(s) 2024. Published by Oxford University Press on behalf of National Academy of Sciences.)

A prototype rover carrying an astrobiology payload was developed and deployed at analog field sites to mature generalized system architectures capable of searching for biosignatures in extreme terrain across the Solar System. Specifically, the four-legged Limbed Excursion Mechanical Utility Robot (LEMUR) 3 climbing robot with microspine grippers carried three instruments: a micro-X-ray fluorescence instrument based on the Mars 2020 mission's Planetary Instrument for X-ray Lithochemistry provided elemental chemistry; a deep-ultraviolet fluorescence instrument based on Mars 2020's Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals mapped organics in bacterial communities on opaque substrates; and a near-infrared acousto-optic tunable filter-based point spectrometer identified minerals and organics in the 1.6–3.6 μm range. The rover also carried a light detection and ranging and a color camera for both science and navigation. Combined, this payload detects astrobiologically important classes of rock components (elements, minerals, and organics) in extreme terrain, which, as demonstrated in this work, can reveal a correlation between textural biosignatures and the organics or elements expected to preserve them in a habitable environment. Across >10 field tests, milestones were achieved in instrument operations, autonomous mobility in extreme terrain, and system integration that can inform future planetary science mission architectures. Contributions include (1) system-level demonstration of mock missions to the vertical exposures of Mars lava tube caves and Mars canyon walls, (2) demonstration of multi-instrument integration into a confocal arrangement with surface scanning capabilities, and (3) demonstration of automated focus stacking algorithms for improved signal-to-noise ratios and reduced operation time. [ABSTRACT FROM AUTHOR]

Despite being considered an extreme environment, several studies have shown that life in the deep subsurface is abundant and diverse. Microorganisms inhabiting these systems live within the rock pores and, therefore, the geochemical and geohydrological characteristics of this matrix may influence the distribution of underground biodiversity. In this study, correlative fluorescence and Raman microscopy (Raman-FISH) was used to analyze the mineralogy associated with the presence of members of the genus Acidovorax , an iron oxidizing microorganisms, in native rock samples of the Iberian Pyrite Belt subsurface. Our results suggest a strong correlation between the presence of Acidovorax genus and pyrite, suggesting that the mineral might greatly influence its subsurface distribution. [ABSTRACT FROM AUTHOR]

Tracking the movement of organisms is a fundamental goal of many ecological studies. Several techniques exist in the study of terrestrial and aquatic fauna; however, to date, the ability to monitor aquatic fauna within the sediment layer efficiently and in multiple dimensions is lacking. Given the importance of subsurface sediments in supporting ecosystem functioning, this inability to observe organism behaviour represents a fundamental gap in our knowledge and limits our capability to holistically characterise the response of freshwater systems to stressors.Here we present an experimental study that employs novel transparent super absorbent polymer substrates (c. 8–12 mm in diameter) in combination with computer vision technology, which enables, for the first time, real‐time observation and tracking of organisms within the sediment layer under lotic flow conditions. Use of these substrates allowed the successful extraction of organism trajectories, which enabled the velocity and body orientation of a freshwater amphipod (Gammarus fossarum) in the sediment layer to be calculated in response to a number of vertical hydrological exchange treatments (upwelling, downwelling, and no vertical exchange).Results indicate that under vertical hydrological exchange, a higher proportion of fast velocities (both horizontal and vertical) were recorded for G. fossarum in the sediment layer compared to no vertical exchange (control) conditions. This increase was most marked for upwelling flow exchange. We also observed a change in the body orientation of individuals in the sediment layer from a vertical alignment under no vertical exchange to a more horizontal one under downwelling and more notably upwelling flow exchange. This shift in body position was exacerbated under stronger vertical exchange rates.We identified that following the flow transition of downwelling to upwelling conditions, there was an immediate shift (0–2 min) in both the orientation angle and activity level of individuals. This increased rate of activity was maintained for the individuals' velocity but not for their changing orientation angle. These trends were not apparent within the flow transition of no vertical exchange to downwelling flow.Our new methodological approach enables vital insights into the behaviour of organisms within the sediment layer. Use of super absorbent polymer substrates allows real‐time multi‐directional tracking of multiple organisms in parallel. We believe the method represents an innovative tool that can be employed to tackle a wide range of ecological questions and thereby improve our mechanistic understanding of ecological responses to biotic and abiotic processes/stressors. [ABSTRACT FROM AUTHOR]

We investigate dynamics of water (H2O) and methanol (CH3OH and CH3OD) inside mesoporous silica materials with pore diameters of 4.0, 2.5, and 1.5 nm using low-field (LF) nuclear magnetic resonance (NMR) relaxometry. Experiments were conducted to test the effects of pore size, pore volume, type of fluid, fluid/solid ratio, and temperature on fluid dynamics. Longitudinal relaxation times (T1) and transverse relaxation times (T2) were obtained for the above systems. We observe an increasing deviation in confined fluid behavior compared to that of bulk fluid with decreasing fluid-to-solid ratio. Our results show that the surface area-to-volume ratio is a critical parameter compared to pore diameter in the relaxation dynamics of confined water. An increase in temperature for the range between 25 and 50°C studied did not influence T2 times of confined water significantly. However, when the temperature was increased, T1 times of water confined in both silica-2.5 nm and silica-1.5 nm increased, while those of water in silica-4.0 nm did not change. Reductions in both T1 and T2 values as a function of fluid-to-solid ratio were independent of confined fluid species studied here. The parameter T1/T2 indicates that H2O interacts more strongly with the pore walls of silica-4.0 nm than CH3OH and CH3OD.

Soil requires load bearing impact assessment for stability. Therefore, this study aims to utilize the multi-channel analysis surface wave (MASW) for soil subsurface investigation and profiling around Peninsular Malaysia. The standard penetration test (SPT) was conducted for comparison between factual N-value and computed N-value from shear wave velocity (Vs) obtained from MASW using the Imai and Tonouchi equation. The correlation coefficient (R) and coefficient of determination, (R2), showed strong relationship between factual N-value and computed N-value. The model of Vs and factual N-value data distribution is non-normal but the analyzed relationship shows a significant level of p-value < 0.05. The R2 for each location of Vs-N-value relationship are ranging from 0.5 to 0.9.

The availability and accessibility of oceanographic data is critical to the sustainability of our oceans into the future. Ocean temperature climatology data products utilizing long time series provide context to ocean warming and allow the identification of anomalous environmental conditions. Here we describe a new methodology to create a daily subsurface temperature climatology using data from three different sources with varying spatial and temporal coverage. The Port Hacking National Reference Station off South East Australia is the site of bottle data collected typically every 1 to 4 weeks at discrete depths between 1953 and 2010, and since 2009 near-monthly vertical profiling CTD profiles and 5 min moored data at various depths. Calculating an unbiased climatology using temperature data sets obtained via different methods, with varying resolution and uncertainty, is challenging. To account for days with limited bottle data, and thus limit the bias from more recent higher temporal resolution data, a time-centered moving window of ±2 days was used to incorporate data collected on neighboring days. To account for different data sources measured on the same date, a date-averaging method was used. As moored data between 2009 and 2019 represented 70% of data for a given day of the year but approximately 1/7 of the 66 year temperature record, a novel data source ratio was implemented to avoid bias toward warmer recent years. Data were organized into their corresponding observed years, and a ratio of 6:1 between bottle and mooring observation years was enforced. To assess the methodology, the steps provided here were tested using synthetically-created temperature data with similar properties to the real observations. The lowest root mean square errors calculated between the known synthetic climatology statistics and the different solution-dependent synthetic climatology statistics confirmed the methodology. The resulting daily temperature climatology shows the seasonal cycle as a function of depth, related to changes in stratification and vertical mixing, and allows for the identification of temperature anomalies. The methodology presented in this paper is readily applicable to other sites across Australia and worldwide where long records exist consisting of multiple data sets with varying sampling characteristics.

Serpentinite-hosted systems represent modern-day analogs of early Earth environments. In these systems, water-rock interactions generate highly alkaline and reducing fluids that can contain hydrogen, methane, and low-molecular-weight hydrocarbons-potent reductants capable of fueling microbial metabolism. In this study, we investigated the microbiota of Hakuba Happo hot springs (∼50°C; pH∼10.5–11), located in Nagano (Japan), which are impacted by the serpentinization process. Analysis of the 16S rRNA gene amplicon sequences revealed that the bacterial community comprises Nitrospirae (47%), “Parcubacteria” (19%), Deinococcus-Thermus (16%), and Actinobacteria (9%), among others. Notably, only 57 amplicon sequence variants (ASV) were detected, and fifteen of these accounted for 90% of the amplicons. Among the abundant ASVs, an early-branching, uncultivated actinobacterial clade identified as RBG-16-55-12 in the SILVA database was detected. Ten single-cell genomes (average pairwise nucleotide identity: 0.98–1.00; estimated completeness: 33–93%; estimated genome size: ∼2.3 Mb) that affiliated with this clade were obtained. Taxonomic classification using single copy genes indicates that the genomes belong to the actinobacterial class-level clade UBA1414 in the Genome Taxonomy Database. Based on metabolic pathway predictions, these actinobacteria are anaerobes, capable of glycolysis, dissimilatory nitrate reduction and CO2 fixation via the Wood–Ljungdahl (WL) pathway. Several other genomes within UBA1414 and two related class-level clades also encode the WL pathway, which has not yet been reported for the Actinobacteria phylum. For the Hakuba actinobacterium, the energy metabolism related to the WL pathway is likely supported by a combination of the Rnf complex, group 3b and 3d [NiFe]-hydrogenases, [FeFe]-hydrogenases, and V-type (H+/Na+ pump) ATPase. The genomes also harbor a form IV ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) complex, also known as a RubisCO-like protein, and contain signatures of interactions with viruses, including clustered regularly interspaced short palindromic repeat (CRISPR) regions and several phage integrases. This is the first report and detailed genome analysis of a bacterium within the Actinobacteria phylum capable of utilizing the WL pathway. The Hakuba actinobacterium is a member of the clade UBA1414/RBG-16-55-12, formerly within the group “OPB41.” We propose to name this bacterium ‘Candidatus Hakubanella thermoalkaliphilus.’

The tribological properties of Al-Li alloys impact the reliability of components used in different industrial sectors. In this research, the effect of normal load on friction and wear properties of the extruded spray-formed 2195-T6 Al-Li alloy is investigated by using a pin-on-disk tester. Through the microstructure of the friction subsurface, it is evaluated that the friction coefficient of 2195 alloy decreases from 0.408 to 0.306 by increasing load (25 N to 150 N), while the wear rate increases exponentially. It is also analyzed that a mild-severe wear transition occurs between 100 N and 125 N and the main wear mechanism gradually shifts from abrasive wear and oxidative wear to delamination wear (25 N ∼ 100 N), and finally attains the state of severe plastic deformation (125 N ∼ 150 N). Under the action of normal load and friction shearing force, the deformation layer in the subsurface increases from 3 μ m to 43 μ m with increasing load, and the accumulation of strain leads to cracks and holes.

Building collapse has been a recurrent environmental hazard in Nigeria in the last two decades. This is a corollary of inadequate foundation investigation prior to construction, poor government policies, and general lack of awareness on the importance of geophysical and geotechnical investigations. In this study, geological mapping and detailed geophysical investigation using Electrical Resistivity Imaging (ERI) and Vertical Electrical Sounding (VES) were carried out to understand the suitability of proposed building sites at the main campus of the Olabisi Onabanjo University (OOU), Ago-Iwoye, Nigeria for construction. Both Wenner array and dipole-dipole were used for profiling and Schlumberger for sounding. Four transverses and VES were used in each of the three areas investigated. Our results show that the subsurface of the study areas is underlain by Precambrian basement rock of Nigeria. Rocks in the study area include banded gneiss, porphyroblastic gneiss, biotite-hornblende granite and quartzite schist. The sounding stations across the three areas and 2D resistivity imaging revealed three principal geoelectric layers, the topsoil, the weathered layer and the fractured/fresh basement with varied resistivity values for each layers. At the VES stations, the three geoelectric layers have resistivity values of 62 to 1182 Ωm, 3.2 to 1360Ωm and 87 to 4680 Ωm. On the 2D resistivity imaging profiles, the resistivity of the three layers varies from 2 to 1182 Ωm, 30to 1360 Ωm, and 40 to 2904 Ωm for the topsoil, the weathered basement, and fractured/fresh bedrock. Our work demonstrates that some of the proposed sites are structurally incompetent for engineering or foundation purposes. Excavation of the topsoil and reinforcement are required to sustain the proposed structures.

The hypersaline sediment and groundwater of playa lake, Lake Lucero, at the White Sands National Monument in New Mexico were examined for microbial community composition, geochemical gradients, and mineralogy during the dry season along a meter and a half depth profile of the sediment vs. the groundwater interface. Lake Lucero is a highly dynamic environment, strongly characterized by the capillary action of the groundwater, the extreme seasonality of the climate, and the hypersalinity. Sediments are predominantly composed of gypsum with minor quartz, thenardite, halite, quartz, epsomite, celestine, and clays. Geochemical analysis has revealed the predominance of nitrates over ammonium in all of the analyzed samples, indicating oxygenated conditions throughout the sediment column and in groundwater. Conversely, the microbial communities are primarily aerobic, gram-negative, and are largely characterized by their survival adaptations. Halophiles and oligotrophs are ubiquitous for all the samples. The very diverse communities contain methanogens, phototrophs, heterotrophs, saprophytes, ammonia-oxidizers, sulfur-oxidizers, sulfate-reducers, iron-reducers, and nitrifiers. The microbial diversity varied significantly between groundwater and sediment samples as their temperature adaptation inferences that revealed potential psychrophiles inhabiting the groundwater and thermophiles and mesophiles being present in the sediment. The dynamism of this environment manifests in the relatively even character of the sediment hosted microbial communities, where significant taxonomic distinctions were observed. Therefore, sediment and groundwater substrates are considered as separate ecological entities. We hope that the variety of the discussed playa environments and the microorganisms may be considered a useful terrestrial analog providing valuable information to aid future astrobiological explorations.

Microorganisms possess a variety of survival mechanisms, including the production of antimicrobials that function to kill and/or inhibit the growth of competing microorganisms. Studies of antimicrobial production have largely been driven by the medical community in response to the rise in antibiotic-resistant microorganisms and have involved isolated pure cultures under artificial laboratory conditions neglecting the important ecological roles of these compounds. The search for new natural products has extended to biofilms, soil, oceans, coral reefs, and shallow coastal sediments; however, the marine deep subsurface biosphere may be an untapped repository for novel antimicrobial discovery. Uniquely, prokaryotic survival in energy-limited extreme environments force microbial populations to either adapt their metabolism to outcompete or produce novel antimicrobials that inhibit competition. For example, subsurface sediments could yield novel antimicrobial genes, while at the same time answering important ecological questions about the microbial community.

Abstract Belonging to the Cameroon Volcanic Line (CVL), the western part of Cameroon is an active volcanic zone with volcanic eruptions and deadly gas emissions. The volcanic flows generally cover areas and bury structural features like faults. Terrestrial gravity surveys can hardly cover entirely this mountainous area due to difficult accessibility. The present work aims to evaluate gravity data derived from the geopotential field model, EGM2008 to investigate the subsurface of the CVL. The methodology involves upward continuation, horizontal gradient, maxima of horizontal gradient–upward continuation combination and Euler deconvolution techniques. The lineaments map inferred from this geopotential field model confirms several known lineaments and reveals new ones covered by lava flows. The known lineaments are interpreted as faults or geological contacts such as the Foumban fault and the Pan-African Belt–Congo craton contact. The lineaments highlighted coupled with the numerous maar lakes identified in this volcanic sector attest of the vulnerability of the CVL where special attention should be given for geohazard prevention.

Abstract An ever increasing community of earth system modelers is incorporating new physical processes into numerical models. This trend is facilitated by advancements in computational resources, improvements in simulation skill, and the desire to build numerical simulators that represent the water cycle with greater fidelity. In this quest to develop a state‐of‐the‐art water cycle model, we coupled HydroGeoSphere (HGS), a 3‐D control‐volume finite element surface and variably saturated subsurface flow model that includes evapotranspiration processes, to the Weather Research and Forecasting (WRF) Model, a 3‐D finite difference nonhydrostatic mesoscale atmospheric model. The two‐way coupled model, referred to as HGS‐WRF, exchanges the actual evapotranspiration fluxes and soil saturations calculated by HGS to WRF; conversely, the potential evapotranspiration and precipitation fluxes from WRF are passed to HGS. The flexible HGS‐WRF coupling method allows for unique meshes used by each model, while maintaining mass and energy conservation between the domains. Furthermore, the HGS‐WRF coupling implements a subtime stepping algorithm to minimize computational expense. As a demonstration of HGS‐WRF's capabilities, we applied it to the California Basin and found a strong connection between the depth to the groundwater table and the latent heat fluxes across the land surface.

Model tests and field measurements were carried out to study the mechanical behavior of cobble-rich soil in response to shield tunneling. In particular, an experimental investigation was carried out using a laboratory-scale model. The model used includes a miniature shield machine that can approximate real tunnel construction, replicating the in-situ methods of excavation and support. The surface settlement and subsurface deformation were analyzed, and these data were compared with predictions based on previous studies. The results confirm that the model tests can effectively simulate the principal operations of a real earth-pressure-balance machine. The observed surface settlement troughs in both the transverse and longitudinal directions were found to be narrower than in clay or sandy soils. With respect to subsurface deformation, the deformation zone width decreases almost linearly as a function of depth. [ABSTRACT FROM AUTHOR]

Eutrophication of natural water bodies is moderated by transformation of nitrate (NO3−) in riparian wetlands, which serve as filters of infiltrating drain water from upland agricultural areas. The present study comprised field observations, laboratory experiments and metagenomic studies to describe NO3− removing transformation pathways and interactions with the cycling of iron (Fe) in a temperate riparian wetland soil profile down to 1 m depth. Water samples from piezometers showed a distinct plume of NO3− in the subsurface soil where agricultural drain water was infiltrating. However, within a distance of few meters in the water flow direction, NO3− was depleted from the percolating water. Sampling and analyses of soil from the active zone of the biogeochemical NO3− removal showed that denitrifying enzyme activity was ~ tenfold higher in the upper 0–25 cm than in the lower 25–100 cm. Yet, net transformation of NO3− was substantial also at 25–100 cm when assayed with relatively undisturbed soil samples and by 15N tracer techniques in soil slurries. Transformation pathways of dissimilatory nitrate reduction to ammonium and anaerobic ammonium oxidation were identified, but were quantitatively minor as compared to denitrification. Heterotrophic denitrification and denitrification mediated by oxidation of ferrous iron, Fe(II), were identified as important processes in the wetland soil. The latter was substantiated by geochemical observations, by rates of NO3− depletion in slurry incubations with added FeCl2, and by identification of microorganisms with known capacity of NO3− reduction coupled to Fe(II) oxidation (Acidovorax sp.). The transformation pathway of iron-mediated NO3− reduction could involve biotic and abiotic reactions, and N2O, which is a potent greenhouse gas, was a major product of the process. It remains to be seen under field conditions if N2O emission hotspots are linked to specific sites of dynamic NO3− reduction coupled to Fe(II) oxidation. [ABSTRACT FROM AUTHOR]

Ground movement is common around hilly areas; as such, there is a need to investigate the activities of the ground surface and subsurface of such regions. This research presents an application of the Permanent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technique and electrical resistivity (ER) method for the measurement of ground deformations and investigation of the subsurface features, respectively, at Paya Terubong, Penang Island. The PS-InSAR is an instrument for detecting patterns of deformation over a wide region, while the ER approach is used to image subsurface characteristics and measure the resistivity of the rock formation. Satellite data obtained from Sentinel-1A (S-1A) were used to detect some active ground deformation zones. The velocity of − 41 mm/Yr was discovered along the line of sight (LOS) of the system, indicating subsidence. An ER survey was performed at the topsoil within 5 m depth based on the ground deformation patterns detected through the InSAR technique. Two-dimensional (2-D) resistivity lines were laid using the ABEM SAS4000 Terameter and a dipole–dipole array with an electrode spacing of 2.5 m. The areas with low values of resistivity ranging between 0 and 20 Ωm were classified as saturated zones. The efflux and influx of subsurface water when the layers of rocks are lubricated and downcutting of steep slopes are among the suspected causes of deformation. The application of the two techniques has improved the understanding of both the surface and subsurface mechanisms, reduced variation in the results, and allowed the investigation of active landslide areas. [ABSTRACT FROM AUTHOR]

There is an underuse of geological knowledge in society. Therefore, an unused potential of more informed decision-making and planning as well as improved solutions on societal challenges exist. The aim of this study was to better understand the geological map user and to improve the usability of geological map products. With the aim of improving graphical communication through maps and images, visual research methods are used. The sketch map method, which has been used since the 1960s, is used here to elicit information about people and their image subsurface geology of a city. The participants include students in area planning and experts within geology. Content, semiotic and visual analyses were performed on the sketches produced by the participants. The results show limited knowledge of geology and a lack of common geological language, both graphical and linguistic. Improved ways of representing the subsurface are identified, which can be used as input to more intuitive future designs. Adapting to the user's image of subsurface geology, usability could be increased by using plain language, adding landmarks, pictographic symbols and patterns to geological visualizations. This could potentially lower the user threshold, trigger interest and raise the awareness of local urban geology. [ABSTRACT FROM AUTHOR]

The Wenner - Schlumberger array was used for Constant Separation Traversing (CST) to investigate subsurface lithology in Auchi Polytechnic, Auchi. All the traverses were carried out with electrode spacing of 5 m with a spread of 200 m. The data was obtained using Pasi terrameter (16-GL) and processed with the Dipro software. The subsurface resistivity values ranged from 207 Om - 8357 Om. The results obtained from this survey classified the subsurface lithology into topsoil, clayey sand, sandy clay and sand. The maximum depth penetrated was 50 m. [ABSTRACT FROM AUTHOR]

Serpentinite-hosted systems represent modern-day analogs of early Earth environments. In these systems, water-rock interactions generate highly alkaline and reducing fluids that can contain hydrogen, methane, and low-molecular-weight hydrocarbons-potent reductants capable of fueling microbial metabolism. In this study, we investigated the microbiota of Hakuba Happo hot springs (∼50°C; pH∼10.5–11), located in Nagano (Japan), which are impacted by the serpentinization process. Analysis of the 16S rRNA gene amplicon sequences revealed that the bacterial community comprises Nitrospirae (47%), "Parcubacteria" (19%), Deinococcus-Thermus (16%), and Actinobacteria (9%), among others. Notably, only 57 amplicon sequence variants (ASV) were detected, and fifteen of these accounted for 90% of the amplicons. Among the abundant ASVs, an early-branching, uncultivated actinobacterial clade identified as RBG-16-55-12 in the SILVA database was detected. Ten single-cell genomes (average pairwise nucleotide identity: 0.98–1.00; estimated completeness: 33–93%; estimated genome size: ∼2.3 Mb) that affiliated with this clade were obtained. Taxonomic classification using single copy genes indicates that the genomes belong to the actinobacterial class-level clade UBA1414 in the Genome Taxonomy Database. Based on metabolic pathway predictions, these actinobacteria are anaerobes, capable of glycolysis, dissimilatory nitrate reduction and CO2 fixation via the Wood–Ljungdahl (WL) pathway. Several other genomes within UBA1414 and two related class-level clades also encode the WL pathway, which has not yet been reported for the Actinobacteria phylum. For the Hakuba actinobacterium, the energy metabolism related to the WL pathway is likely supported by a combination of the Rnf complex, group 3b and 3d [NiFe]-hydrogenases, [FeFe]-hydrogenases, and V-type (H+/Na+ pump) ATPase. The genomes also harbor a form IV ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) complex, also known as a RubisCO-like protein, and contain signatures of interactions with viruses, including clustered regularly interspaced short palindromic repeat (CRISPR) regions and several phage integrases. This is the first report and detailed genome analysis of a bacterium within the Actinobacteria phylum capable of utilizing the WL pathway. The Hakuba actinobacterium is a member of the clade UBA1414/RBG-16-55-12, formerly within the group "OPB41." We propose to name this bacterium ' Candidatus Hakubanella thermoalkaliphilus.' [ABSTRACT FROM AUTHOR]

Measurements of ground compliance at the InSight landing site—describing the surface response to pressure loading—are obtained from seismic and meteorological data. Compliance observations show an increase with frequency indicating the presence of a stiffer rock layer beneath the exposed regolith. We performed a Markov chain Monte Carlo inversion to investigate the vertical profile of the elastic parameters down to 20 m below InSight. Compliance was inverted both freely and assuming prior knowledge of compaction in the regolith, and the limitations and strengths of the methods were assessed on the basis of theoretical considerations and synthetic tests. The inverted Young modulus exhibits an increase by a factor of 10–100 over the first 10–15 m, compatible with a structural discontinuity between 0.7 and 7 m. The proposed scheme can be used for joint inversion of other seismic, geological, or mechanical constraints to refine the resulting vertical section. Plain Language Summary: Pressure fluctuations of the Mars' atmosphere induce tiny deformations of the ground that can be measured by the very sensitive seismometer of the InSight mission. The amount of deformation depends on the elastic properties of the sandy regolith (the surface layer exposed and highly fractured by impacts) and of the underlying rocks and can thus be used to explore beneath the surface. In this work, we review the theory describing the ground motion caused by moving pressure perturbations, and we analyze the effect of various parameters (wind speed and layering in the subsurface). We then develop a method to retrieve a vertical profile of the elastic parameters beneath the lander from the measurements. After testing the method on ideal cases, we apply it to data from Mars: The results show that the regolith becomes stiffer with depth and that a layer of harder rock may be present below, with the interface possibly located between 0.7 and 7 depth. Determining the structure of the near surface provides constraints on the geologic history of the landing site and contributes to the explanation of measured seismic signals. Key Points: Ground compliance measurements by InSight depend on the elastic properties in the near surface of MarsObserved compliance from convective vortex encounters and other pressure fluctuations opens the way to the exploration of the near surfaceMarkov chain Monte Carlo inversion for the Young modulus profile suggests stratification within and below the regolith [ABSTRACT FROM AUTHOR]

Drought extent and severity have increased and are predicted to continue to increase in many parts of the world. Understanding tree vulnerability to drought at both individual and species levels is key to ongoing forest management and preparation for future transitions in community composition. The influence of subsurface hydrologic processes is particularly important in water‐limited ecosystems, and is an under‐studied aspect of tree drought vulnerability. With California's 2013–2016 extraordinary drought as a natural experiment, we studied four co‐occurring woodland tree species, blue oak (Quercus douglasii), valley oak (Quercus lobata), gray pine (Pinus sabiniana), and California juniper (Juniperus californica), examining drought vulnerability as a function of climate, lithology and hydrology using regional aerial dieback surveys and site‐scale field surveys. We found that in addition to climatic drought severity (i.e., rainfall), subsurface processes explained variation in drought vulnerability within and across species at both scales. Regionally for blue oak, severity of dieback was related to the bedrock lithology, with higher mortality on igneous and metamorphic substrates, and to regional reductions in groundwater. At the site scale, access to deep subsurface water, evidenced by stem water stable isotope composition, was related to canopy condition across all species. Along hillslope gradients, channel locations supported similar environments in terms of water stress across a wide climatic gradient, indicating that subsurface hydrology mediates species' experience of drought, and that areas associated with persistent access to subsurface hydrologic resources may provide important refugia at species' xeric range edges. Despite this persistent overall influence of the subsurface environment, individual species showed markedly different response patterns. We argue that hydrologic niche segregation can be a useful lens through which to interpret these differences in vulnerability to climatic drought and climate change. [ABSTRACT FROM AUTHOR]

A new analysis modality in Raman microscopy, Micro-Spatially Offset Raman Spectroscopy (micro-SORS) to explore the subsurface of materials in non-destructive and non-invasive way has been developed recently at ICVBC – CNR. Micro-SORS facilitates the investigation of the chemical composition of subsurface, micrometre-scale-thick diffusely scattering layers at depths more than an order of magnitude larger than those accessible with the depth resolving power of conventional confocal Raman microscopy, avoiding need to resort to cross sectional analysis or sampling. In the state of the art paragraph an overall overview of research carried out at CNR-ICVBC in the last five years concerning the development, optimization and application of micro-SORS to Cultural Heritage materials is provided. Additionally, we present new data achieved from the application of micro-SORS to illustrative micro-samples obtained from mediaeval polychrome sculptures of the Parma baptistery and Ferrara cathedral, highlighting further its potential in Cultural Heritage sciences. [ABSTRACT FROM AUTHOR]

An additive/subtractive hybrid manufacturing (ASHM) combines the advantages of both additive and subtractive processes for fabricating complex parts of a better quality. While in an additive manufacturing process, temperature buildup is fast because of heat accumulation from a laser or electron beam, which exerts a great influence on the successive subtractive process. This study firstly measures the temperature variation of a Ti-6Al-4V workpiece in the direct material deposition (DMD) process, and then designs a heating device for a milling experiment at elevated temperatures. The effect of temperature buildup on milling forces is investigated through the experiment and a 2D thermal-mechanical coupling model. For work hardening effect and rapid tool wear, the milling forces are hardly decreased when the preheating temperature is lower than 300 °C. At a preheating temperature of 300 °C or higher, a significant reduction in milling forces is recorded, which may be attributed to the thermal softening effect on the workpiece material. The decreasing trend is more obvious at a larger feed-per-tooth. The thermal softening effect is reflected in the deformation layer in the subsurface of the machined workpiece. The study provides a guide to the determination of ASHM process parameters for Ti-6Al-4V. [ABSTRACT FROM AUTHOR]

Earth subsurface recognition through describing the underground layers can be carried out using physical measurements to obtain clearer and more accurate subsurface model. This can be conducted applying well logging method. Among various information that can be provided by different well logging sensors, neutron, density and gamma-ray data are the most considerable in subsurface type determination. However, current analysis of these data stills a subjective task which adds a variable confidence interval to the obtained results. In this study, a real time decision level fusion system uses fuzzy logic approach is introduced to incorporate neutron, density, and gamma-ray information in order to provide more specific interpretation of the subsurface structures. Results of the proposed approach agreed well with the results of an offline subsurface determination program, with an average ratio of about 89.75%. The suggested approach was evaluated against real data from eight wells, and the results were promising to yield more objective interpretation. [ABSTRACT FROM AUTHOR]

When components are drilled for use in critical applications, some components might undergo surface defects and subsurface deformations. These defects arise due to microstructural and microhardness variations. This leads to sudden failure of these components. The present investigation focuses on Al/B4C/Mica hybrid composites and Al/B4C composites specimen with drilled surface and sub-surfaces. The goal is to identify measures to reduce surface integrity issues like microhardness, drilled surface morphology, and chip morphology on these specific components. Moreover, as a novel research, elemental and microstructural characterization of mica particles is carried out. The evaluation techniques used are Optical, EDX, SEM, and Vickers microhardness test. The stir cast specimens are drilled with process parameters of weight % B4C and mica at specified cutting speed and feed rate. Tungsten carbide twist drill of 8 mm diameter is used. The investigation reveals that addition of mica particles causes reduction in the microhardness of drilled surfaces. The % of reduction observed is up to 13.7, 5.2 and 3 (in Hv) on 4%, 8%, and 12% B4C reinforced Al/B4C/3%mica hybrid composites, respectively, in comparison with that of Al/B4C composites. [ABSTRACT FROM AUTHOR]

In this work, a reconnaissance study is presented to delineate the subsurface and lithological interpretation of the aeromagnetic data. To achieve this goal, several enhancement techniques and filtering processes were carried out on these maps. At first, the total intensity aeromagnetic map is processed through the application of reduction to the magnetic equator technique. Six aeromagnetic data sheets covering some parts of the Sokoto Basin were used. These maps were digitized on a TMI grid. An analysis of the total magnetic field over the area of study was carried out using the aeromagnetic data sets. The following deduction were made: the interpreted lineaments follow a predominantly EW- and NSW-trending orientation, while other orientations in the survey area include NW-, ENE- and, more rarely E-trending structures, the existence of several high short wavelength magnetic closures with steep gradients near the geologic boundary is a strong indication that the basin may not be as large as shown by the geologic map. The residual magnetic field values were employed to obtain the two-dimensional Fourier transforms from which the radial spectrum was extracted. The slopes of the graph of spectral energy against frequency of nine sections were obtained and used to estimate the depth values. The results suggested that the deeper depth of the study area ranges from 1.99 km – 2.83 km while the shallow depth ranges from 0.78 km – 1.25 km in conformity to the delineation of favourable lithological units between cretaceous meta-sediments and Eocene boundary. Finally, the study reveals that structural interpretation based on aeromagnetic data is an efficient tool for frontier exploration for hydrocarbon accumulation and/or other mineralization. [ABSTRACT FROM AUTHOR]

The tropical instability waves (TIWs) in the eastern tropical Pacific have generally been considered as surface‐intensified structures resembling the first baroclinic mode. Here, we report on the existence of subsurface‐intensified TIWs on the equator. These TIWs are primarily manifested in zonal velocities, inducing maximum velocity oscillations at 70–90 m depth with amplitudes of 0.1–0.2 m/s and periods of 5–20 days. They account for ~20% of the variance at 5‐ to 30‐day periods, with another ~50% being contributed by the surface‐intensified TIWs. These waves are most significant during the TIW seasons; they are energized in part by barotropic instabilities and usually last for 3–7 months. Via interacting with the mean flow, they can induce strong out‐of‐phase shear changes between ~50‐m depth and just above the Equatorial Undercurrent core and may lead to complex diapycnal mixing structures. Their horizontal structures, generation mechanism(s), and large‐scale impacts remain to be disclosed. Plain Language Summary: The eastern equatorial Pacific is an area of intense ocean heat uptake due to the strong equatorial Sun. The fate of this heat depends on turbulent mixing processes in the upper ocean: heat may be returned quickly to the atmosphere or be carried into the deeper ocean and stored for many years, with obvious consequences for climate. The same is true of other important water properties such as CO2 content. Equatorial turbulence originates largely with vertically sheared currents. One important mechanism for this is tropical instability waves (TIWs), 1,000‐km waves that generate and amplify vertical shear (i.e., vertical differences in the horizontal current), which in turn generates the turbulence that mixes heat downward. Previous studies have shown that TIWs concentrated at the ocean surface carry the most energy. Here, we show that TIWs focused below the surface, while less energetic, can carry a disproportionate fraction of the shear, and it is of course that shear that drives turbulence and the resulting fluxes of heat, CO2 and other properties. We describe the times of the year when these subsurface TIWs are strongest, the periods at which they oscillate, and the depths at which they generate enhanced shear. Key Points: Subsurface tropical instability waves, with zonal velocity oscillation peaking at 70–90 m, are identified in the eastern equatorial PacificThe waves have periods of 5–20 days and amplitudes of 0.1–0.2 m/s and can persist for 3–7 months from July to the following FebruaryThe waves can induce periodically enhanced and reduced shear and hence mixing at ~50 m and above the core of the Equatorial Undercurrent [ABSTRACT FROM AUTHOR]

Microorganisms possess a variety of survival mechanisms, including the production of antimicrobials that function to kill and/or inhibit the growth of competing microorganisms. Studies of antimicrobial production have largely been driven by the medical community in response to the rise in antibiotic-resistant microorganisms and have involved isolated pure cultures under artificial laboratory conditions neglecting the important ecological roles of these compounds. The search for new natural products has extended to biofilms, soil, oceans, coral reefs, and shallow coastal sediments; however, the marine deep subsurface biosphere may be an untapped repository for novel antimicrobial discovery. Uniquely, prokaryotic survival in energy-limited extreme environments force microbial populations to either adapt their metabolism to outcompete or produce novel antimicrobials that inhibit competition. For example, subsurface sediments could yield novel antimicrobial genes, while at the same time answering important ecological questions about the microbial community. [ABSTRACT FROM AUTHOR]

Evidence and observations favoring the hypothesis that Venus is habitable, and the celestial mechanisms promoting the interplanetary transfer of life, are reviewed. Venus may have been contaminated with Earthly life early in its history via interplanetary transfer of microbe-laden bolide ejecta; and this seeding with life may have continued into the present via spacecraft and due to radiation pressure and galactic winds blowing microbial-laden dust ejected from the stratosphere via powerful solar winds, into the orbit and atmosphere of Venus. Venus may have had oceans and rivers early in its history until 750 mya, and, hypothetically, some of those species which, theoretically, colonized the planet during that time, may have adapted and evolved when those oceans evaporated and temperatures rose. Venus may be inhabited by a variety of extremophiles which could flourish within the lower cloud layers, whereas others may dwell 10 m below the surface where temperature may be as low as 200 ∘C—which is within the tolerance level of some hyperthermophiles. Speculation as to the identity of mushroom-shaped specimens photographed on the surface of Venus by the Russian probe, Venera 13 support these hypotheses. [ABSTRACT FROM AUTHOR]

The South China Sea (SCS) is the largest semi-enclosed marginal sea in the North Pacific. Salinity changes in the SCS play an important role in regional and global ocean circulation and the hydrological cycle. However, there are few studies on salinity changes over the SCS due to lack of high-quality and long-term observations. In the past decade, the deployment of floats from the Argo program in the SCS and their accumulated temperature and salinity profiles have made it possible for us to examine salinity changes over the entire basin. In this study, salinity changes were investigated with Argo and underwater glider temperature and salinity observations and gridded temperature-salinity objective analyses (UK Met Office Hadley Centre EN4.2.1 objective analysis and China Argo Real-time Data Center BOA_Argo). The results indicated that the subsurface water in the entire SCS became significantly saltier during 2016–2017. The most significant salinity increase was found during 2016 in the northeastern SCS. The subsurface water in the northeastern SCS exhibited a salinity maximum above 35, which was recorded by three Argo floats during 2015–2016. Such high salinity water was rarely observed and reported prior to the Argo era. Average salinity of 2016–2017 along the 25.5σθ−23.5σθ isopycnal surfaces in the whole SCS is 0.014−0.130 higher than the climatology. Increases in subsurface salinity started from the northeastern SCS and extended southwestward gradually. Moreover, the subsurface salinity changes, especially in the northern SCS, exhibited a semiannual lead behind the subsurface Luzon Strait transport. Further analysis indicated that the predominance of advection, driven by subsurface Luzon Strait transport, led to salinification along the western boundary of the SCS. In other parts of the SCS, negative wind stress curl trends tended to preserve the high salinity characteristics of the subsurface water. [ABSTRACT FROM AUTHOR]

[Display omitted] • Subsurface hydrogen production technologies were introduced. • The potential of the approach to significantly reduce CO 2 emissions was highlighted. • An overview of major barriers to subsurface technologies was provided. • Finally, the operational challenges faced in subsurface hydrogen production were addressed. Subsurface technologies present an excellent opportunity to produce hydrogen from hydrocarbon resources. It refers to the production of hydrogen directly from underground resources, particularly hydrocarbon resources. This method often involves injecting steam or oxygen into the reservoirs to initiate reactions that produce hydrogen. In some cases, subsurface method can also involve the process of in-situ gasification (ISG), and in-situ combustion (ISC) (also known as subsurface combustion and gasification). The produced hydrogen is extracted from the reservoir, leaving the carbon dioxide and other byproducts underground. This approach could offer a sustainable and carbon-free pathway to produce hydrogen because of reduced CO 2 emissions compared to conventional methods. A comprehensive review of the status and progress of ISC and ISG of hydrocarbon for hydrogen production is presented. The advantages and limitations of the technologies were discussed as well as the underlying reaction mechanism. Techno-economic and lifecycle assessment studies of ISG and ISC are presented. One of the main economic limitations of subsurface hydrogen production is the high cost of building and operating the required infrastructure. However, utilizing pre-existing horizontal wells for air or oxygen injection can significantly reduce the initial infrastructure investment costs. Moreover, the overall process cost of ISG can vary significantly due to various factors, including membrane costs, oxygen production costs and the cost of hydrocarbon. The findings from the environmental evaluation indicate that the primary contributors to greenhouse gas emissions in subsurface technologies are the CO 2 emissions produced during gas combustion for heat generation and the electricity consumed during the gasifying agents' preparation stage. Subsurface methods for producing hydrogen encounter numerous challenges, including choosing the right locations and selecting cost-effective drilling techniques. [ABSTRACT FROM AUTHOR]

Pipelines transport natural gas (NG) in all stages between production and the end user. The NG composition, pipeline depth, and pressure vary significantly between extraction and consumption. As methane (CH 4), the primary component of NG is both explosive and a potent greenhouse gas, NG leaks from underground pipelines pose both a safety and environmental threat. Leaks are typically found when an observer detects a CH 4 enhancement as they pass through the downwind above-ground NG plume. The likelihood of detecting a plume depends, in part, on the size of the plume, which is contingent on both environmental conditions and intrinsic characteristics of the leak. To investigate the effects of leak characteristics, this study uses controlled NG release experiments to observe how the above-ground plume width changes with changes in the gas composition of the NG, leak rate, and depth of the subsurface emission. Results show that plume width generally decreases when heavier hydrocarbons are present, the leak rate is reduced, and as leak depth decreases from 0.9 to 0.6 m. The study illustrates that heavy gas leaks from flowlines and gathering lines could currently be more challenging to detect than leaks from distribution pipelines as the plume is trapped close to the ground. Further, this study shows that leaks from pipelines laid in covers meeting minimum depth requirements of 0.9 m could be easier to detect compared to those buried shallower. Overall, this study illustrates that leak survey protocols for flowlines and gathering lines should be different from distribution pipelines and tailored to the compositions of the transported NG to report emissions accurately. The study aims to improve the understanding of flowline/gathering line leaks to prevent fatal accidents, such as the 2017 explosion from a gathering line in Firestone, Colorado, that resulted in two fatalities and one injury. • The impact of leak variation on natural gas detection is investigated. • Gas density, leak rate, and depth significantly impact leak detection. • Flowlines/gatherings could be more challenging to detect than distribution lines. • Pipelines in complex regions could be more challenging to detect than in croplands. [ABSTRACT FROM AUTHOR]

Land surface models (LSMs) simulate water and energy cycles at the atmosphere–soil interface, however, the physical processes in the subsurface are typically oversimplified and lateral water movement is neglected. Here, a cross-evaluation of land surface model results (with and without lateral flow processes), the National Aeronautics and Space Administration (NASA) Soil Moisture Active/Passive (SMAP) mission soil moisture product, and cosmic-ray neutron sensor (CRNS) measurements is carried out over a temperate climate region with cropland and forests over western Germany. Besides a traditional land surface model (the Community Land Model (CLM) version 3.5), a coupled land surface-subsurface model (CLM-ParFlow) is applied. Compared to CLM stand-alone simulations, the coupled CLM-ParFlow model considered both vertical and lateral water movement. In addition to standard validation metrics, a triple collocation (TC) analysis has been performed to help understanding the random error variances of different soil moisture datasets. In this study, it is found that the three soil moisture datasets are consistent. The coupled and uncoupled model simulations were evaluated at CRNS sites and the coupled model simulations showed less bias than the CLM-standalone model (−0.02 cm3 cm−3 vs. 0.07 cm3 cm−3), similar random errors, but a slightly smaller correlation with the measurements (0.67 vs. 0.71). The TC-analysis showed that CLM-ParFlow reproduced better soil moisture dynamics than CLM stand alone and with a higher signal-to-noise ratio. This suggests that the representation of subsurface physics is of major importance in land surface modeling and that coupled land surface-subsurface modeling is of high interest.