Deposition Cycles Research Articles

The urgent need to reduce phosphorus discharges for sustainable mangrove wetland management

Phosphorus affects microbial metabolic activity, nitrogen and carbon cycling in mangrove sediment, but its influence on carbon stability and greenhouse gases emission remains unclear. This study compared greenhouse gases (CO2, N2O, and CH4) emissions from mangrove sediment receiving wastewater containing various phosphorus concentrations, and evaluated its long term effect on sediment carbon flux when phosphorus pollution is eliminated. Significant increases in greenhouse gases flux and decrease of total organic carbon and readily oxidizable organic carbon in the sediment were observed after phosphorus discharge. Specifically, the N2O flux was reduced significantly at high phosphorus levels while the CO2 flux and the microbial biomass organic carbon was increased. The copy numbers of ammonia oxidation (AOA-amoA, AOB-amoA) gene, denitrification (narG, nirK) gene and methanogenesis (mcrA) gene increased with the increasing phosphorus concentration. During the wastewater discharge period for 70 days, the global warming potential of sediment flux at high phosphorus discharge condition was more than 4 times that of the control group, and the loss of total organic carbon and readily oxidizable organic carbon was 4.66 % and 7.1 %, respectively. During the remediation period (71–101 days), the greenhouse gases flux decreased rapidly, ends up with a similar level of the control group. Our results indicate that using mangrove wetland for pollution minimization in the coastal aquaculture industry could increase greenhouse gases emisison significantly, it is therefore essential to reduce phosphorus discharges from various anthropogenic activities, and local authorities must set up more stringent discharge standards in the future.

Smartphone based wearable sweat glucose sensing device correlated with machine learning for real-time diabetes screening

BackgroundDiabetes is a significant health threat, with its prevalence and burden increasing worldwide indicating its challenge for global healthcare management. To decrease the disease severity, the diabetic patients are recommended to regularly check their blood glucose levels. The conventional finger-pricking test possesses some drawbacks, including painfulness and infection risk. Nowadays, smartphone has become a part of our lives offering an important benefit in self-health monitoring. Thus, non-invasive wearable sweat glucose sensor connected with a smartphone readout is of interest for real-time glucose detection. ResultsWearable sweat glucose sensing device is fabricated for self-monitoring of diabetes. This device is designed as a body strap consisting of a sensing strip and a portable potentiostat connected with a smartphone readout via Bluetooth. The sensing strip is modified by carbon nanotubes (CNTs)-cellulose nanofibers (CNFs), followed by electrodeposition of Prussian blue. To preserve the activity of glucose oxidase (GOx) immobilized on the modified sensing strip, chitosan is coated on the top layer of the electrode strip. Herein, machine learning is implemented to correlate between the electrochemical results and the nanomaterial content along with deposition cycle of prussian blue, which provide the highest current response signal. The optimized regression models provide an insight, establishing a robust framework for design of high-performance glucose sensor. SignificanceThis wearable glucose sensing device connected with a smartphone readout offers a user-friendly platform for real-time sweat glucose monitoring. This device provides a linear range of 0.1–1.5 mM with a detection limit of 0.1 mM that is sufficient enough for distinguishing between normal and diabetes patient with a cut-off level of 0.3 mM. This platform might be an alternative tool for improving health management for diabetes patients.

Geomechanical Response Characteristics of Different Sedimentary Hydrodynamic Cycles—Exampled by Xujiahe Formation of Upper Triassic, Western Sichuan Basin

This study delves into the geomechanical responses of different sedimentary hydrodynamic cycles in deep tight sandstone formations. Employing core observation and thin section analysis, we quantitatively identified and characterized bedding planes, sedimentary microfacies, and tectonic fractures. Then, the intricate relationships between various architectural interfaces and geomechanical parameters were elucidated. Subsequently, utilizing finite element numerical simulation software, in situ stress and fracture parameters were derived. By identifying a fracture facies zone correlated with the sedimentary hydrodynamic cycle and production data, our findings unveil several key insights: (1) Geomechanical parameters (Young’s modulus, Poisson’s ratio, brittleness index) exhibited noteworthy variations within the T3x2−5 sand group, indicative of weak elasticity and robust plasticity. (2) The effective distance, influenced by diverse reservoir architecture interfaces, displayed variability, with each transition between peak-valley-peak or valley-peak-valley pinpointed as a distinct sedimentary hydrodynamic cycle. (3) In environments characterized by strong sedimentary hydrodynamics (between two level 3 architecture interfaces), fractures with larger strike angles and lower dip angles were observed to be more prevalent. (4) Three significant fracture faces—level I, level II, and level III—were discerned within the study area. Notably, reservoirs associated with level III exhibited characteristics suggestive of medium porosity and permeability, indicative of a gas layer. By thoroughly understanding the geomechanical response characteristics of formations such as the Xujiahe Formation, it is possible to guide the exploration and development of energy resources such as oil and natural gas. This helps to improve the efficiency and safety of resource extraction, promoting the sustainable utilization of energy.

Microbially-mediated reductive dissolution of Fe-bearing minerals during freeze-thaw cycles

Constraining the role of microbes in the structural iron (Fe) reduction of iron-bearing minerals improves our understanding of sediments and ice sheets as a source of dissolved Fe (dFe) to the oceans. However, bio-mediated structural Fe-reduction has yet to be studied in cryospheric environments. Here, we show that the Fe reducing psychrophile bacterium Shewanella vesiculosa, isolated from sea ice in Antarctica, reduced structural Fe in nontronite (NAu-2) and maghemite (γ-Fe2O3), common mineral phases in glacial ice, and marine sediments in Antarctica, during two freeze–thaw cycles (−10 °C to +15 °C), resulting in the release of dFe. The modification of turbostratically disordered nontronite (ferric iron dominant phase) to discrete ordered illite-like structure (ferrous iron dominant phase), and the aggregation of altered small maghemite particles with neoformation of vivianite (Fe3(PO4)2·nH2O) indicated the microbially induced reductive dissolution of nontronite and maghemite, respectively. The biotic Fe-reduction gradually decreased and ceased as the temperature approached freezing (−8 °C), however the rection reactivated in the thawing cycle (−7 to +15 °C). No discernable biotic Fe-reduction was measured for either mineral under freezing conditions, suggesting that temperature limits the activity of the microbes. Further, and regardless of temperatures during two freeze–thaw cycles, Fe-reduction was not observed in abiotic control. Overall, these results highlight the importance of microbially induced Fe reduction during seasonal freeze–thaw cycles of ice and sediments in continuous supplying bioavailable dFe to cryospheric environments and the often Fe-limited polar oceans.

Unlocking Maximum Synergy: Screen-Printing Fabrication of Heterostructured Microsupercapacitor Stacks.

A cost-effective and scalable approach for the fabrication of heterostructured microsupercapacitors (MSCs) employing screen-printing followed by sequential electrochemical and microspray deposition techniques has been demonstrated. The microsupercapacitor electrode (MSC) that composed of stacked layers of mesoporous carbon, polyaniline (PANI), and MXene hold significant promise for wearable electronics. By adjusting the deposition and spray cycles, the MSC can be readily coated with PANI and MXene. The sequentially stacked two layers of MXene and PANI on the mesoporous carbon spheres (PMPM-MSC) yielded a specific capacitance of 1003 mF cm-2 at 0.5mA cm-2, surpassing the performance of PANI/mesoporous carbon electrode by 1.6 times (771 mF cm-2). After 10,000 cycles of charge and discharge, PMPM-MSCs retained more than 86% of their initial capacitance. In-situ Raman spectroscopy confirmedthe synergistic effects between MXene and PANI within the heterostructured stacked PMPM-MSC electrodes, including enhanced electronic conductivity and improved electrolyte ion dissociation, which aligned with the electrochemical measurement results, such as fast charge/discharge rates and reduced internal and mass transport resistance. This study demonstrates the potential of screen-printed heterostructured MSC stacks with maximum electrochemical synergy for portable and wearable energy storage devices.

Correlating the coating cycles, integrity and magnetic properties of Fe–Ni–Mo soft magnetic composites by a powder atomic layer deposition method

Coatings play a crucial role in minimizing eddy current loss in soft magnetic composites (SMCs). The powder atomic layer deposition (PALD) technique was utilized to coat Fe–Ni–Mo soft magnetic powder in this study. The Al2O3 coating fabricated via PALD enhanced corrosion resistance and reduced core loss in SMCs. Additional deposition cycles increased the resistivity of the Fe–Ni–Mo powder and the corrosion resistance of the Fe–Ni–Mo SMCs, indicating that the density and integrity of the amorphous Al2O3 coating were enhanced. Thinner coatings (20 cycles) exhibited anodic passivation in corrosion, which was attributed to insufficient density. Nevertheless, an excessively thick coating (100 cycles) resulted in a decrease in effective permeability and an increase in hysteresis loss. The fabricated Fe–Ni–Mo SMCs (50 cycles) demonstrated a core loss of 603.1 mW/cm3 at 100 kHz/100 mT, coupled with an effective permeability of 108.5 and a Q value of 97.8 at 100 kHz.

Sedimentology, depositional processes, and sequence stratigraphy of deep lacustrine fine-grained sedimentary rocks in the lower Oligocene Xiaganchaigou Formation, Qaidam Basin, Northwestern China

Lacustrine deep-water fine-grained sedimentary rocks are characterized by high heterogeneities in lithology and lithofacies stacking patterns, controlled by sediment supply and lake level fluctuation. Despite their vital roles as source and reservoir rocks of unconventional oil and gas play, depositional processes and sedimentary sequence of lacustrine fine-grained sedimentary rocks are poorly understood compared to their extensively studied deep marine counterparts. Here, we studied lithofacies, transportation and depositional processes, depositional environments, and sedimentary cycles of deep-water fine-grained deposits of the Lower Oligocene Xiaganchaigou Formation from cored wells in the western Qaidam Basin. Nine lithofacies that stack repetitively in 6–18 m thick sedimentary cycles are identified based on petrographic observation, geochemical analysis, and scanning electron microscopy. The regressive systems tract of a sedimentary cycle is composed of detrital-rich massive fine sandstone deposited by debris flows and thin-bedded fine sandstone deposited by high-density turbidity currents. The transgressive systems tract is dominated by laminated carbonate-rich mudrock facies deposited by low-density turbidity currents. A complete sedimentary cycle is interpreted to represent a transgressive-regressive cycle controlled by fifth-order lake-level variation. Coarse-grained detrital-rich debrite and high-density turbidite were deposited in the proximal sublacustrine fan and channel during lake-level regression, with sediments mainly supplied by terrigenous siliciclastic input. Carbonate-rich low-density turbidites are deposited primarily in the distal sublacustrine fan during lake-level transgression. Thin-laminated carbonate-rich mudrock facies with high organic matter abundance and well-developed laminae-induced fractures are considered both source rocks and target reservoirs of the upper Xiaganchaigou Formation.

Lightweight titanium dioxide/carbon nanotube composites prepared by atomic layer deposition for broad-band microwave absorption

The microwave absorbing material with appropriate impedance matching and excellent attenuation ability can be applied to resist electromagnetic radiation. In this work, carbon nanotubes were modified by titanium dioxide via the atomic layer deposition method, to prepare lightweight composites with high microwave absorption performance. The impedance matching and attenuation ability of titanium dioxide/carbon nanotube (TiO2/CNT) composites could be precisely controlled by adjusting the number of titanium dioxide deposition cycles. The relationship between the microstructure and microwave absorption performance of the composite was analyzed in detail. When the number of TiO2 deposition cycles was 100, the composite displayed outstanding microwave absorption performance, due to appropriate impedance matching and strong attenuation ability. The maximum effective absorption bandwidth of the composite reached 5.19 GHz (1.6 mm), which almost covered the Ku band. The microwave attenuation mechanism of the composite has also been investigated. This work provided a new idea for fabricating lightweight microwave absorption materials.

Identification of Milankovitch sedimentary cycle in Fengcheng Formation, Mahu depression: a case study of well Maye 1

The sedimentary cycle of Fengcheng Formation in Junggar Basin changes rapidly and is difficult to identify. The low classification accuracy of high-frequency fine-grained sedimentary cycles restricts the exploration of unconventional shale oil and gas. Full-interval coring of well Maye 1 provides a solid foundation for small-layer research. In this paper, the high-frequency sedimentary cycle of Milan kovitch in Fengcheng Formation is studied by means of spectral analysis and wavelet transform, and the shale sweet spot is identified. The long period of eccentricity of 405ka, short period of eccentricity of 100ka and long period of axis slope of 42736a can be used as semi-quantitative basis for the classification of the fourth, fifth and sixth sequences. The Fengcheng Formation can be divided into 2 quaternary sequence cycles, 9 quaternary sequence cycles and 16 quaternary sequence cycles. A long period of eccentricity of 405ka can identify large-scale lake recessional and recessional, and there is a maximum lake flooding surface in the middle of the second Fengcheng Formation, which corresponds to high abundance of organic matter and high hydrocarbon generation potential. The 100ka short period eccentricity can identify the sweet spot layer, and there are 8 sweet spots in the well Maye 1, which is consistent with the results of nuclear magnetic interpretation. The research results provide a semi-quantitative basis for the classification of high-frequency sedimentary cycles and the identification of sweet spots of Fengcheng Formation in Mahu Sag, Junggar Basin.

Ultramicroporous cardo-pendant polyamide nanofilms for enhanced organic solvent nanofiltration

Permeable, selective, and stable polymeric membranes are essential for efficient molecular separation in organic solvents. Polymers of intrinsic microporosity (PIMs) with rigid and twisted chain structures offer abundant pores for high solvent permeability and are emerging as an ideal membrane material. However, guaranteeing high separation selectivity and stability is challenging owing to the wide pore size distribution and low swelling resistance in organic solvents. In this work, we developed intrinsically ultramicroporous polyamides (PAs) with cardo-pendant groups to create crosslinking, ultrathin, and defect-free nanofilms for organic solvent nanofiltration. The molecular simulation confirmed the pivotal role of cardo-pendant group structures in the amine monomers and exhibited their effect in creating pore channel structures within the PAs. Distinctive rigid fluorenyl-based cardo-pendant groups were introduced in amine monomers to finely tailor the packing of PA chains for high ultramicroporosity and a finely tuned pore size. We further achieved the growth of such PAs using a cyclic deposition strategy, in-situ generating highly crosslinking nanofilms with an ultralow thickness of 23–36 nm without structure relaxation. As such, the typically-designed PA membranes demonstrated high and stable solvent permeance (e.g., 18 L m−2 h−1 bar−1 for methanol) and high solute rejection (up to 95 % rejection of 306 Da Azure I), which is superior to its counterparts and current PIM membranes, presenting a new perspective for efficient organic solvent nanofiltration.

Climate cyclicity-controlled recurrent bottom-water ventilation events in the aftermath of the Toarcian Oceanic Anoxic Event: the Jenkyns Event

AbstractEnvironmental perturbations of the Toarcian Anoxic Event and its associated carbon isotope excursion (CIE) occurred in a cyclic fashion indicating an orbital control mechanism. Sedimentary strata of the E. elegantulum ammonite subzone in the Lorraine Sub-basin, Luxembourg, exhibit eight sedimentary cycles, most of which postdate the CIE, implying that its termination did not coincide with a full recovery from environmental stress. Sea-level and temperature fluctuations of the Toarcian crisis were linked to a cryosphere demise in the Northern Hemisphere, which modulated stadial versus interstadial phases on the orbital 100 ka eccentricity frequency band. Upon stadial phases, enhanced wind strength in combination with lowered sea level disrupted stratified shelf waters and shifted the storm wave base close to the sea floor. Ventilation of bottom waters interrupted accumulation of laminated and organic-rich black shales, but formed organic-lean and non-laminated gray claystones enriched in terrigenous wax lipids and spores provided via aeolian transport from the hinterland due to the enhanced wind strength. Wind systems are assumed to have been driven by high pressure differences between the cryosphere in the North of the Tethyan shelf and the warmer costal lowland. This distinguishes the atmospheric turbulences after the CIE from the postulated intensification of the cyclones that accompanied the rapid warming at the beginning of the CIE. The deep-water ventilation event following the CIE in the Lorraine Sub-basin was accompanied by a parallel evolution in the SW German Basin, indicating a supraregional driving mechanism in paleobathymetric sub-basins susceptible to lowering of storm wave base. In sub-basins with greater water depth on the NW-Tethyan shelf, post-CIE orbitally driven atmospheric turbulences had a minor or no effect on water column stratification and deposition of organic-rich laminated black shales persisted. Graphical abstract

Stratigraphy and sequence stratigraphy of the Neoproterozoic (Cryogenian–Ediacaran) Stuart Shelf, South Australia

The Stuart Shelf is part of the Adelaide Superbasin overlying the Gawler Craton and Cariewerloo Basin in South Australia. The basin is of interest for sediment-hosted copper mineralisation known to be hosted in numerous stratigraphic intervals across the region. Therefore, facies analysis and understanding of spatial distribution of host units are essential for exploration targeting and mineral systems research. Our study presents improved and new definitions of Cryogenian and Ediacaran Stuart Shelf stratigraphy, and a detailed, regional-scale sequence stratigraphic analysis. The Cryogenian non-glacial interlude was of particular interest, as it includes the Tapley Hill Formation, a known host for copper mineralisation. The succession of Tapley Hill Formation (including Sturtian cap carbonates), Brighton Limestone and Angepena Formation represents a third-order depositional cycle, an equivalent to the lowermost cycle of the Cryogenian non-glacial interlude in the adjacent Adelaide Rift Complex. The Ediacaran post-glacial succession includes the Nuccaleena Formation and Tent Hill Formation and is interpreted as a second-order depositional cycle. The Sturtian and Marinoan cap carbonates form regional stratigraphic marker horizons and were deposited in a transgressive systems tract. Variations in facies and thickness can be linked to development of localised depocentres and topographic highs, such as the Pernatty High. Modelling of 3D surfaces reveals a shift in the basin orientation between the Cryogenian and Ediacaran sedimentation from an NNW–SSE axis towards a N–S axis. The Stuart Shelf sequence stratigraphic framework provides new insights in the basin sedimentology and evolution, which aids sediment-hosted mineral systems analysis and improves the understanding of Cryogenian and Ediacaran basin evolution in Australia.

Modified successive ionic layer adsorption and reaction for interconnected bismuth vanadate nanograins: Highly active visible light harvesting photoanodes

A modified successive ionic layer adsorption and reaction (SILAR) method is developed for depositing interconnected bismuth vanadate (BiVO4) nanoparticles with improved visible light harvesting activity. Facile control of preparative parameters like deposition cycles, anionic precursor, pH and deposition temperature significantly altered BiVO4 surface morphology. BiVO4 thin films prepared with Na3VO4 anionic precursor show dispersed nanoparticles type morphology and that deposited with NaVO3 precursor displays 3D interconnected nanoparticles morphology. The BiVO4 photoanodes with 3D interconnected nanoparticles morphology exhibits an excellent photocurrent density of 5.19 mA cm−2 at 1.23 V vs. RHE with superior photostability and improved applied bias photon to current efficiency (ABPE) (1.50 %) compared to dispersed nanostructured BiVO4 photoanodes. The excellent photoelectrochemical (PEC) characteristics of BiVO4 photoanodes with 3D interconnected nanoparticle morphology can be ascribed to porous morphology, optimum thickness, narrow band gap energy and favorable electronic band structure for water splitting. The current study illustrates the usefulness of the modified SILAR approach for depositing 3D interconnected BiVO4 nanoparticle morphology in a single step that is superior and efficient to previously reported multistep processes.

Herbivores can benefit both plants and their pathogens through selective herbivory on diseased tissue

Abstract Infectious disease can shape community structure, particularly when pathogens affect foundation species. Seagrasses are foundation species that form meadows along coasts worldwide, controlling sediment deposition and biogeochemical cycling while supporting a diverse community of fish and invertebrates. These plants are hosts to wasting diseases that cause necrotic tissue lesions, which could alter seagrass value as food, habitat and mediators of ecosystem processes. However, such biotic interactions and influences on disease dynamics are still not well understood. We investigated whether a common herbivore affected the development of wasting disease on eelgrass. We measured the severity and prevalence of eelgrass wasting disease in a meadow across two summers through repeated field surveys. We assessed the role of the eelgrass herbivore on disease spread and growth using microcosm and mesocosm experiments. We further explored herbivore feeding preferences in a choice trial, which was paired with chemical analysis of plant tissue and analysed using a structural equation model. While the herbivore facilitates the growth of new disease lesions among isolated leaves, on balance they reduce lesion severity by more than 50% in comparison with no‐herbivore controls in field‐realistic settings. This was likely because the herbivore strongly prefers to eat diseased rather than healthy tissue, consuming nearly twice as much lesion area in choice trials. This preference arises from pathogen‐driven changes in the host plant; lesioned tissue requires less force to penetrate than non‐lesioned tissue. Additionally, as lesions increase in size, their polyphenolic concentrations drop, which further increases the magnitude of preference for lesioned tissue. Synthesis: These results suggest that these herbivores could help maintain disease in this system at a high prevalence (by facilitating disease development) but low severity (through preferential consumption), which is consistent with our field observations of nearly 100% prevalence and low severity in a natural bed where herbivore density is high. Describing such multi‐species interactions in marine systems will advance our predictions of future disease states, as current understandings focus primarily on how environmental change contributes to pathogen outbreaks.

Genome-based analysis of the family Paracoccaceae and description of Ostreiculturibacter nitratireducens gen. nov., sp. nov., isolated from an oyster farm on a tidal flat.

Two bacterial strains, designated FR2A1T and MT2-5-38, were isolated from the surface sediments of an oyster farm on a tidal flat in Quanzhou Bay, China. Both strains were Gram-stain-negative, rod-shaped, aerobic, catalase-positive, and oxidase-positive. The 16S rRNA gene sequences of the two strains were 100% identical and had the highest similarity (97.1%) with Phaeovulum vinaykumarii JA123T. The average nucleotide identity (ANI) value and digital DNA-DNA hybridization (DDH) value indicated that the two strains belonged to a single species. Gene annotation revealed that the two strains contained a gene cluster for nitrate reduction and a gene cluster for sulfur oxidation, indicating a possible role in N and S cycling in the tidal flat sediment. The phylogeny inferred from the 16S rRNA gene and 120 conserved proteins indicated that the two strains formed a distinct monophyletic clade within the family Paracoccaceae. The respiratory quinone was Q-10. The major fatty acids consisted of summed feature 8 (C18:1ω7c and/or C18:1ω6c) and C18:0. The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, and several unidentified phospholipids. Based on the above characteristics, strains FR2A1T and MT2-5-38 represent a novel genus and a novel species, for which we propose the name Ostreiculturibacter nitratireducens gen. nov., sp. nov. The type strain is FR2A1T (=MCCC 1K08809T = KCTC 8317T). Phylogenomic analysis of 1,606 high-quality genomes of the family Paracoccaceae, including type strains, non-type strains, and uncultivated bacteria, was performed using the Genome Taxonomic Database Toolkit (GTDB-Tk), and the average amino acid identity (AAI) value of the phylogenetic clade was estimated. We found that 35 species of the family Paracoccaceae needed re-classification, and an AAI value of 70% was chosen as the genus boundary within the family Paracoccaceae.

Development of electrode by using gold-platinum alloy nanopar¬ticles for electrochemical detection of serum amyloid A protein

Gold-platinum alloy nanoparticles (AuPtNP) were electrochemically deposited on the surface of indium-tin-oxide (ITO) modified with (3-aminopropyl)triethoxysilane (APTES), after optimizing deposition conditions for the electroplating solution and number of deposition cycles. Different part ratios of Au/Pt used were 4/0, 3/1, 2/2, 1/3 and 0/4 (AuNP, Au3Pt1, Au2Pt2, Au1Pt3 and PtNP, respectively) in preparation of 1 mM solutions. FE-SEM, EDAX and XRD surface characterization techniques were used to confirm the presence of deposited AuPt alloy nanoparticles on the modified ITO surface. Electrochemical methods (CV, DPV and EIS) were used to investigate the electrochemical properties of prepared electrodes in the presence of ferri/ferrocyanide redox couple, which indicated the following increasing order of electrocatalytic peak current: Au < Au2Pt2 < Pt < Au1Pt3 < Au3Pt1. The most active electrode, Au3Pt1NP/APTES/ITO (with Au/Pt part ratio 3:1), was further used to fabricate the immunoelectrode SAA-Ab/Au3Pt1NP/APTES/ITO. The prepared immunoelec­trode was tested for detection of serum amyloid A protein biomarker (APO-SAA) by immobilising SAA-specific antibodies (SAA ½ Ab) on its surface. Sensing studies on this immunoelectrode, performed by DPV technique, revealed the SAA biomarker detection in the linear range of 10 to 106 fg ml-1. The limit of detection was calculated as 7.0 fg ml-1.

Fracture identification in shale reservoir using a deep learning method: Chang 7 reservoirs, Triassic Yanchang formation

Natural fractures in shale oil formations play a significant role in fluid flow channels. However, their identification can be difficult due to the problems of subtle log responses of fractures and impact of sedimentary cycles on logging curve. To address these issues, a fracture identification method (FRNN) based on deep learning is proposed. FRNN combines window sliding and bidirectional recurrent neural networks (BiLSTM). A large number of sequence data samples from logs are obtained through window sliding, denoted with fracture labels based on rock core observations or borehole image log interpretation. BiLSTM processes sequences bidirectionally to mitigate the impact of sedimentary cycles on well logging curves and amply log responses caused by fractures. The integration of the sliding process and BiLSTM endeavors to address the challenge of fracture identification, which is often marked by significant uncertainty and subtle log responses. The experiments employ a dataset from Triassic Yanchang Formation's Chang 7 reservoirs in Q Oilfield, China, which contains shales and sandstones formed in braided river delta lacustrine systems that act as oil reservoirs. The statistical analysis and blind well test show that the fracture identification by the proposed FRNN method is consistent with those of core descriptions. Furthermore, examination of wellbore cross-sections reveals a congruence between the anticipated vertical distribution of fractures and the influencing factors thereof, thus validating the efficacy of the proposed methodology. The findings of this study can provide assistance in subsurface fracture modeling and hydraulic fracturing operations, etc.

Unveiling the impact of microplastics with distinct polymer types and concentrations on tidal sediment microbiome and nitrogen cycling

Microplastics (MPs) are distributed widely in the ocean surface waters and sediments. Increasing MPs contamination in intertidal zone profoundly impacts microbial ecosystem services and biogeochemical process. Little is known about the response of tidal sediment microbiome to MPs. We conducted a 30-day laboratory microcosm study using five polymers (PE, PBS, PC, PLA and PET) at three concentrations (1 %, 2 % and 5 %, w/w). High throughput sequencing of 16 S rRNA, qPCR and enzyme activity test were applied to demonstrate the response of microbial community and nitrogen cycling functional genes to MPs. MPs reduced the microbial alpha diversity and the microbial dissimilarity while the effects of PLA-MPs were concentration dependent. LEfSe analysis indicated that the Proteobacteria predominated for all MP treatments. Mantel’s test, RDA and correlation analysis implied that pH may be the key environmental factor for causing microbial alterations. MPs enhanced nitrogen fixation in tidal sediment. PLA levels of 1 % but not 5 % produced the most significant effects in nitrogen cycling functional microbiota and genes. PLS-PM revealed that impacts of MPs on tidal sediment microbial communities and nitrogen cycling were dominated by indirect effects. Our study deepened understanding and filled the knowledge gap of MP contaminants affecting tidal sediment microbial nitrogen cycling.

Atomic layer annealing for spatial tailoring in sub-4 nm AlN RRAM devices with low-voltage operation

This article investigates the spatial tailoring of nitrogen vacancies by atomic layer annealing (ALA) on resistive random access memory (RRAM) devices with an AlN resistive switching layer. The ALA technique involves the in-situ layer-by-layer He/Ar plasma treatment in the cycle of atomic layer deposition for AlN. The AlN RRAM devices prepared with the ALA treatment near the TiN electrode have significantly superior uniformity of the operation voltages and the switching resistances, along with a lower cycle-to-cycle variation in endurance. This enhancement could be attributed to the relatively stable location of rupture and formation of conductive filaments, as a result of the film densification and the suppression of nitrogen vacancies in the AlN region treated with the ALA process. The AlN RRAM devices also demonstrate excellent retention of more than 106 seconds at 125°C. In addition, the ultra-thin 3.3 nm AlN switching layer contributes to low operation voltages of AlN RRAM. The outcomes manifest that the ALA technique could effectively improve the properties of nanoscale materials through precise spatial tailoring, with an accuracy up to atomic scale.

Quantitative characterization of thin-interbedded coal measure reservoir configurations in the Wujiu depression, inner Mongolia: Sedimentary controlling mechanisms

Thin-interbedded coal measure reservoirs are important unconventional gas reservoirs. The lithology of these reservoirs is complicated, with rapid vertical changes, making accurate description difficult. Based on the thin-interbedded coal-bearing strata in the Wujiu Depression in eastern Inner Mongolia, China, this study constructs changes in lithofacies based on a Markov mathematical and statistical model. The Shengli subdepression mainly features a lithofacies sequence of uniform coal-mud-sand cycles and other small-scale symmetrical sedimentary cycles. In the Moguai–Shiwalu subdepression, lake hydrodynamics primarily affect coal–mudstone and mudstone–sandstone double-cycle lithofacies sequences and small-scale asymmetric sedimentary cycles. The Markov model and the Ward minimum variance method were used to quantitatively couple a reservoir lithologic sequence and bed thickness configuration, and five basic configurations of the composite reservoir of the Damoguaihe Formation in the study area were obtained: (1) multiseam interbedded configuration, (2) multiseam interbedded configuration with an intermediate number of seams, (3) interbedded configuration with an intermediate number or few seams (with thick mudstone or sandstone layers), (4) interbedded configuration with few seams (large spacings between adjacent coal seams) and (5) thickly interbedded configuration. The sedimentary facies mechanism controlling the spatial distribution pattern of composite reservoirs is discussed. It is concluded that the sedimentary system domain and lake size have a significant effect on the configuration of composite reservoirs. For small terrestrial lakes, the stability of sedimentary environment and the rapid and frequent rise and fall of the lake surface results in significant differences in coal accumulation in a short distance from the edge to the center.