Search Results (3,368)

Internal wall loss in hot-fluid pipelines is difficult to monitor during operation because weak thermal perturbations are masked by global heating, axial cooling, and external heat dissipation. This study develops an external thermometry framework combining a flexible-base fiber Bragg grating (FBG) array with residual-peak morphology analysis. A closed-loop hot-water rig with five artificial wall-loss regions was tested under exposed-air and buried-soil boundaries, and a validated conjugate heat-transfer model generated 269 controlled scenarios. Experiments showed residual anomalies above measurement uncertainty, with a maximum repeatability standard deviation of approximately 0.12 °C and the clearest signals at 90–120 s after hot-water injection. Boundary conditions strongly affected observability at 115 mm and 70 °C, and the residual peak increased from about 0–1 °C in exposed air to 8–9 °C under the buried boundary. Simulations showed that defect width expanded the disturbed region from approximately 100 to 210 mm, while peak amplitude remained coupled to width and depth. Six morphology descriptors jointly estimated position, width, and depth, with mean absolute errors (MAEs) of 0.547, 1.647, and 0.245 mm, respectively. The method provides a recalibratable early-screening route for locating suspicious wall-loss regions before confirmatory inspection. Full article

Water-soluble ZnSe quantum dots (QDs) typically suffer from limited photoluminescence (PL) efficiency and poor long-term stability due to intrinsic defects and surface traps. Here, we report a strategy combining Al³⁺ doping with stepwise multilayer ZnS shell growth. The stepwise precursor injection ensures uniform shell formation, while Al³⁺ incorporation suppresses defect-related recombination within the ZnSe core. The resulting ZnSe:Al/ZnS/ZnS/ZnS QDs exhibit a PL quantum yield of 23.24% and an average lifetime of 129.28 ns. They retain 91% of their initial PL intensity after 200 days under ambient conditions. Mechanistic analysis indicates that defect regulation and multilayer shell passivation synergistically promote band-edge radiative recombination over defect-assisted pathways. This work provides a strategy for simultaneously regulating defect states and surface stability in water-soluble semiconductor QDs. Full article

During CO₂ flooding, unfavorable mobility ratios and interlayer heterogeneity can induce preferential flow through high-permeability intervals, leaving central low-permeability intervals insufficiently swept and rich in remaining oil. To address the strong coupling among composite chemical-plugging parameters and the high computational cost of CMG-STARS simulations for individual candidate strategies, this study proposes an adaptive heterogeneous ensemble surrogate-assisted differential-evolution method (AHES-DE). The method integrates radial basis function, inverse-distance weighting, and ridge-linear surrogate models, whose predictions are dynamically weighted according to leave-one-out cross-validation errors. Explorer, Exploiter, and Robust roles are used for global search, local exploitation, and prediction-risk control, respectively, with differential-evolution offspring generation embedded in the Exploiter role. A stratified one-injector–four-producer conceptual model with a 21 × 21 × 6 grid was used to establish a numerical evaluation workflow comprising CO₂ injection, preferential-channel development, composite chemical plugging, and subsequent displacement. Mobile chemical concentration, adsorbed preformed particle gel (PPG) mass density, water-phase resistance factor, oil saturation at a common termination time, and net economic value (NEV) were used to evaluate treatment performance. Under an equal budget of 150 high-fidelity CMG-STARS evaluations per method, the reported single-seed final best-so-far NEVs were 2.45405 × 10⁹ CNY for AHES-DE, 2.44888 × 10⁹ CNY for differential evolution (DE), and 2.44698 × 10⁹ CNY for Latin hypercube sampling (LHS). The layer-resolved responses indicate more pronounced chemical transport, retention, and resistance development in the upper and lower preferential intervals, while the oil saturation in the central low-permeability interval decreased further after treatment, indicating that flow redistribution facilitated remaining-oil mobilization. A realistic geological model was further used to assess the engineering consistency of the identified flow-control mechanism. Full article

The potential of clay as a replacement for Portland cement in the manufacture of injection cement–clay mortars (ICCMs) for soil stabilization is examined in this investigation. The objective of this study is to produce environmentally friendly injection-molded mortars for soil stabilization based on Portland cement (PC) and clay (C). Experimental ICCMs with C contents ranging from 0% to 50% without the addition of microsilica (MS) and ICCMs with C contents ranging from 0% to 50% and 2% MS were produced. The evaluation included the density, water segregation, and cone spread diameter of fresh ICCMs, alongside the density, flexural strength, and compressive strength of hardened ICCMs. The findings indicated that as C content rose from 0% to 50%, fresh mortars experienced a decrease in density, flowability, and water segregation. Hardened mortars exhibited reduced density, compressive strength, and flexural strength as C content increased. Modifying mortars with MS has a positive effect on their strength properties. The reduction in flexural and compressive strength for mortars with 50% C was 54.2% and 60.1%, respectively, while for similar mortars with 2% MS, the reduction in strength was 47.9% and 51.8%, respectively. ICCM soil stabilization compositions modified with MS are the most effective in comparison with similar compositions without MS and have a homogeneous structure with pores, microcracks, and hydration reaction product zones. The optimal ratios of raw components for the production of ICCMs for soil stabilization were determined: a water–solid ratio of 0.6, PC content from 90% to 50%, C content from 10% to 50%, and an MS content of 2% of the dry component weight. This research contributes to sustainable development by reducing CO₂ emissions per 1 m³ of mixture production by up to 47.8% and by using raw materials rationally. Full article

Periprosthetic joint infection (PJI) remains one of the most serious complications of arthroplasty, largely due to the formation of microbial biofilms on implant surfaces. Biofilm-associated infections exhibit increased tolerance to antimicrobial therapy and host immune responses, making eradication difficult and often requiring repeated surgical interventions. Consequently, there is a growing need for effective local therapeutic strategies capable of delivering high concentrations of antimicrobial agents directly to the site of infection while minimizing systemic toxicity. Hydrogels have emerged as promising drug delivery platforms for the management of biofilm-associated PJI. Their biocompatibility, injectability, high water content, and tunable physicochemical properties enable controlled and localized release of therapeutic agents within the infected peri-implant environment. This narrative review summarizes recent advances in hydrogel-based approaches, including antibiotic-loaded hydrogels, systems incorporating anti-biofilm enzymes, bacteriophage-loaded formulations, and nanoparticle-enhanced platforms. It also highlights future research directions, with particular emphasis on the need for expanded clinical studies to facilitate the translation of emerging hydrogel-based therapies into clinical practice. Further development of these systems should focus on the incorporation of novel therapeutic agents into hydrogel platforms, aiming to enhance biofilm eradication and improve treatment outcomes in patients with PJI. Particular attention is given to stimuli-responsive (“smart”) hydrogels that release therapeutic payloads in response to infection-related triggers such as pH changes, with emphasis on the need for expanded clinical studies to facilitate the translation of emerging hydrogel-based therapies into clinical practice. Further development of these systems should focus on the incorporation of novel therapeutic agents into hydrogel platforms, aiming to enhance biofilm eradication and improve treatment outcomes in patients with PJI. Full article

Polyhydroxyalkanoates (PHAs) are biodegradable biopolymers with high application potential, representing an alternative to petrochemical-derived plastics. The aim of this study was to evaluate the processing and mechanical properties of the commercial PHA EM20010 material intended for injection molding. Particular attention was paid to analyzing the effect of process parameters on the material’s flowability in the injection mold and determining the basic functional properties of the resulting molded parts. The tests included a technological flowability test using an Archimedes spiral mold, a static tensile test, Charpy impact testing, Shore D hardness measurements, and water absorption assessment. The results obtained showed that the tested material was characterized by a high tensile strength of 66.8 ± 1.8 MPa and a Young’s modulus of 1322 ± 21 MPa. Elongation at maximum stress reached 5.0 ± 0.5%, indicating the relatively stiff nature of the material. The average unnotched impact strength was 24.8 ± 3.5 kJ/m², while hardness ranged from 54.6 to 55.4 ShD. Water absorption tests revealed very low water absorption of approximately 0.11% after 24 h of exposure. The flushing test confirmed the significant effect of injection temperature and pressure on the material’s flowability. The maximum spiral length of 54.8 cm was achieved at a processing temperature of 175 °C and an injection pressure of 100 bar. The tests demonstrated that this material possesses a favorable combination of high strength, good toughness, low water absorption, and good processing properties. Full article

Groundwater ingress threatens the serviceability and durability of underground structures, particularly when hydrogeotechnical conditions and waterproofing details are considered separately. This study presents a diagnosis-driven assessment of a reconstructed underground shooting range tunnel where leakage persisted despite reconstruction and previous repairs. The objectives were to identify the cause-and-effect mechanism of water ingress and select a targeted, low-impact remediation strategy. The investigation combined archival analysis, three site inspections, ultrasonic testing at 24 locations, eight tomographic scans, targeted destructive verification, and three geotechnical boreholes extending to 7.5 m. Ultrasonic measurements indicated good concrete homogeneity, with a mean estimated compressive strength of 36.9 MPa and a coefficient of variation of 5.86%. Tomography indicated a 25 cm bottom slab and a 20 cm lean concrete layer, compared with the designed 30 cm and 10 cm, respectively. The original geotechnical investigation was too shallow, and the ground conditions should have been classified as difficult, corresponding to geotechnical category II. Finally, leakage was linked to groundwater underestimation, water accumulation in the backfilled excavation, absence of drainage, waterproofing discontinuities, and ineffective previous injections. Targeted reinjection and joint sealing were selected, demonstrating how integrated diagnostics can support proportionate remediation while limiting excavation, demolition, material use, and operational disruption. Full article

Oilfield production forecasting serves as the decision-making basis for monthly production allocation and injection–production system optimization. Existing mainstream prediction methods face significant limitations: the Arps decline curve extrapolates historical production trends, yet its accuracy degrades rapidly following adjustments to injection–production regimes; machine learning methods such as XGBoost can leverage extensive dynamic data but rely heavily on manual feature engineering and offer limited decision interpretability. This paper proposes the FTT-Transformer prediction model, whose core innovation is the Feature-Time Tokenizer (FTT). The FTT projects every scalar pair (time step, feature) in a multivariate time series matrix into a token of uniform dimensionality, superimposing three types of positional information—time embedding, feature embedding, and global position encoding. On this foundation, a multi-head self-attention mechanism performs end-to-end, full-capacity learning of nonlinear interactions across both the temporal and feature dimensions. The model is lightweight, requiring only 35,361 parameters for 13 input features and is readily deployable. Validation was conducted using production data from two independent waterflooding oilfields. On Dataset 2 (60 wells, 2012–2026), the model achieved an R² of 0.819, achieving performance on par with XGBoost (0.813; DM test p = 0.620, indicating no statistically significant difference) and substantially outperforming temporal Transformer baselines PatchTST (R² = 0.683) and iTransformer (R² = 0.786). On Dataset 1 (96 wells), it reached an R² of 0.930, statistically indistinguishable from XGBoost’s 0.943 (DM test p = 0.611). Five-fold temporal cross-validation yielded a mean R² of 0.840 ± 0.036, confirming the model’s stability. Ablation experiments revealed that global position encoding contributed most significantly, with its removal causing a 3.9 percentage point reduction in R² on Dataset 2. Composite feature-importance analysis showed that monthly liquid production and water cut are identified by the model as the two most predictive features, contributing 31.93% and 30.17% of the total importance, respectively. Multi-step forecasting results demonstrated that the model retains an R² of 0.640 for predictions two months ahead, spanning one complete decision cycle of monthly production reallocation. The proposed architecture is not domain-specific; by adapting the feature embeddings and time encoding, it could potentially be extended to diverse multivariate time series forecasting applications. However, cross-domain validation remains future work. Full article

Driven by China’s “Dual Carbon” strategy, medium-deep closed-loop geothermal energy has become a mainstream clean heating technology owing to the advantage of “heat extraction without groundwater production”. However, its large-scale application is restricted by low single-well heat output and an unclear matching mechanism between working fluids and wellbores. Taking sandstone geothermal reservoirs in Dezhou, Northwestern Shandong Depression, as the research object, a 3D coupled heat transfer model of the wellbore–reservoir was established via COMSOL Multiphysics. The heat transfer characteristics of water and CO₂ under variable injection temperature, mass flow rate and wellbore layout were compared. The results show that: (1) injection temperature dominates the heat extraction performance of water, which matches branched wells and delays overall reservoir thermal depletion during long-term exploitation; (2) CO₂ performance is highly sensitive to mass flow rate and suitable for connected wells, and an asymmetric geothermal field with “cooled injection zone and heated production zone” forms under a high flow rate; (3) limited by low specific heat capacity, CO₂ delivers lower heat power at an identical flow rate, while equivalent heat yield can be achieved when its flow rate doubles that of water. This study clarifies matched development schemes for two working fluids and provides a theoretical reference for optimized exploitation of closed-loop geothermal systems in sandstone reservoirs in Northwestern Shandong. Full article

Complex narrow-channel reservoirs are strongly constrained by depositional architecture, resulting in highly nonuniform areal waterflood sweep, and pronounced water-cut variations among different channel types. These characteristics pose substantial challenges to stabilizing oil production and controlling water cut at high water-cut stages. To elucidate how narrow-channel planform architecture controls waterflood sweep, gel-assisted flow-field regulation by heterogeneous-phase composite flooding (HPCF), and remaining-oil mobilization, three representative configurations were reproduced in two-dimensional visual physical models. Sequential waterflood–HPCF–post-waterflood experiments were conducted, and time-lapse images and dynamic production data were integrated to characterize sweep evolution and remaining-oil mobilization across displacement stages. The results demonstrate that narrow-channel architecture exerts primary control on preferential flow-path development, gel migration and retention, spatial fluid redistribution, and displacement performance. During waterflooding, injected water preferentially migrated through high-permeability zones along channel centerlines, leaving channel margins, branch termini, and poorly connected regions insufficiently swept. After HPCF injection, the gel-containing composite system preferentially entered the established dominant flow paths. Gel retention and accumulation selectively increased flow resistance in these pathways, while mobility control induced subsequent fluids to divert toward bypassed regions, thereby enlarging the macroscopic swept volume and improving local displacement efficiency. A low injection rate promoted sustained gel-assisted flow diversion within bifurcated channels, whereas a high injection rate facilitated gel-slug propagation against the geometric constraints of highly sinuous channels and expanded its spatial coverage. Compared with waterflooding alone, HPCF increased the ultimate oil recovery of the three channel models by 19.23–26.47 percentage points. These findings clarify the coupled effects of narrow-channel architecture, gel transport and injection parameters on the profile-control and oil-recovery performance of HPCF, providing a mechanistic basis for water control and development optimization in high-water-cut narrow-channel reservoirs. Full article

In femtosecond-laser processing of titania in water, light can induce reduction and oxidation simultaneously. We follow this redox energy partitioning, in this perspective, from colloidal titania synthesis to hot-electron devices. Femtosecond ablation/fragmentation of an aqueous anatase suspension (515 nm, 230 fs, $5\mathsf{\mu }$J, fluence $F\approx 25.5$ J cm⁻²/pulse at clamped intensity ∼${10}^{13}$ W cm⁻²) yields surface-reduced, Ti³⁺-rich bluish TiO_2−x, while the same optical breakdown generates reactive oxygen species (ROS), among them H₂O₂ and HO^• radicals, which compete by re-oxidising Ti³⁺. When the reduced titania is decorated with plasmonic nanoparticles (e.g., Au), an n-type plasmonic photo-electrode is realised: $sp$ hot electrons are injected over the Schottky barrier, while the deep d-band supplies oxidising holes. The oxygen evolution reaction (OER) proceeds in stages at potentials well above the formal $1.23$ V via the two-electron peroxide route (∼$1.77$ V) or, for sufficiently energetic holes, via the one-electron HO^• route (∼$2.7$ V). In a biased cell, H₂ evolves on Pt through the adsorbed (H₂⁺)_ad intermediate. The same Au/semiconductor physics on silicon enables sub-band-gap hot-electron photo-detection. Energy-level diagrams (flat-band and in-contact) and the $sp$- vs. d-band origin of the injected carriers are discussed. Full article

The tight sandstone gas reservoir in Qingshimao gas field has the characteristics of complex gas–water distribution, low reservoir quality, low porosity, low permeability and high water saturation. Single-well productivity is low, the production and pressure decrease rapidly, the stable production period is short and economically viable development remains challenging. Therefore, considering the reservoir physical properties and development characteristics of the Qingshimao area, physical experiments and numerical simulations were conducted to investigate the reserve utilization characteristics of complex tight water-bearing gas reservoirs and to evaluate the effectiveness of CO₂ injection in restoring reservoir pressure and enhancing gas recovery after depletion. The results show that: (1) The movable-water saturation of Type I and Type II reservoirs ranged from 2 to 18% and 3–21%, respectively, while increasing water saturation reduced cumulative gas production and increased gas-flow resistance. Type III and Type IV reservoirs are limited by low permeability and fine pore throat. The movable-water saturation is less than 8% and 6% respectively under high water saturation conditions, and the gas–water flow is obviously limited. (2) Both continuous CO₂ injection and post-injection soaking can promote residual-gas recovery after depletion. Post-injection soaking prolongs the contact time between CO₂ and residual methane, whereas fractured cores exhibit more rapid pressure recovery but earlier CO₂ breakthrough. (3) Pore scale and two-dimensional visualization experiments show that after CO₂ injection, the pressure is transferred from the injection inlet to the production outlet, and the depleted low-pressure area is supplemented. The incremental recovery factor of the two-dimensional models after CO₂ injection ranged from 22.81 to 25.28 percentage points. (4) The numerical simulation results show that permeability, water saturation, and the injection and production rates jointly control pressure restoration and gas recovery during CO₂ injection. The high-permeability reservoir achieves a higher recovery factor but experiences earlier CO₂ breakthrough. High water saturation and high injection and production rates will weaken the effective sweep. In field application, the layers with good connectivity and moderate water saturation should be preferred, and the injection and production rates should be reasonably controlled to reduce the risk of gas channeling. Overall, post-depletion CO₂ injection can effectively restore reservoir pressure, mobilize residual methane, and enhance gas recovery in tight water-bearing gas reservoirs. The experimental results support post-depletion CO₂ injection as a potential approach for improving the development performance of tight water-bearing gas reservoirs. Full article

In the development of carbonate reservoirs via water flooding huff-n-puff, the osmotic pressure effect is frequently overlooked, and existing models inadequately quantify the matrix imbibition and oil expulsion driven by salinity gradients. To address this issue, this study establishes a coupled oil–water two-phase huff-n-puff flow model for carbonate reservoirs that incorporates the interplay between salt concentration and osmotic pressure, which, for the first time, fully couples the van ’t Hoff osmotic pressure equation with solute transport equations for fractured-vuggy carbonate huff-n-puff, filling the gap that prior tight/shale reservoir low-salinity flow models fail to adapt to cyclic injection-soaking production regimes of carbonates. Based on the IMPES (implicit pressure–explicit saturation) numerical simulation method, an equivalent single-nucleus model is adopted to characterize the fractured-vuggy reservoir architecture. The model integrates the osmotic pressure formula, solute transport equation, and two-phase seepage governing equations, enabling a systematic analysis of the mechanisms by which osmotic pressure affects the multi-stage seepage process and the influence of key parameters on development performance. Quantitative simulation reveals three core laws controlled by salinity-induced osmosis: first, osmotic pressure drives water molecules to spontaneously migrate from the high-permeability fracture inner core toward the tight matrix pores, thereby modifying the water saturation distribution, expanding the water sweep region, and smoothing the saturation gradient between the inner and outer cores, which effectively mitigates water channeling in fractured reservoirs. Under the base case (injected water salinity = 1000 mg/L, inner-core permeability = 1000 mD, shut-in time = 80 d), the oil recovery factor with osmotic pressure considered reaches 13.46%, representing a 3.50% increment over the case without osmotic pressure. The recovery factor decreases monotonically with increasing injected water salinity, while it increases with longer shut-in time and higher inner-core permeability, both exhibiting pronounced diminishing marginal returns; the optimal shut-in time is approximately 80 d under the simulated conditions. This work delivers a fully coupled numerical tool and quantitative evaluation standard for osmotic imbibition mechanisms in fractured-vuggy carbonates. The quantified recovery increment and optimal soaking window established herein can directly guide field parameter optimization of injection water salinity, shut-in cycle and fracture reconstruction scale, balancing oil increment revenue and water treatment/well shutdown operation costs for on-site low-salinity huff-n-puff design. Full article

The global plastic pollution crisis demands a fundamental re-evaluation of materials systems beyond incremental improvements to fossil fuel-based polymers. Bioplastics, polymers derived from renewable biological feedstocks, biodegradable under defined conditions, or both, offer a chemically diverse and rapidly evolving platform for transitioning toward circular materials economies in which the value of carbon, energy, and material is retained across multiple use cycles. This review provides a comprehensive and critically organized account of the bioplastics field, spanning three generations of feedstock development from food crops through lignocellulosic residues to algae and waste streams; primary production pathways including microbial fermentation, ring-opening polymerization, and biosynthesis; forming processes from extrusion and injection molding to additive manufacturing; and the mechanical, thermal, and barrier properties that determine application fitness. Particular emphasis is placed on life cycle assessment, which reveals that bioplastics’ climate benefits are conditional on feedstock choice, land-use management, energy source at manufacturing, and end-of-life pathway, and that burden-shifting from greenhouse gas emissions to land use, water consumption, and eutrophication is a systematic risk requiring integrated LCA evaluation rather than single-metric optimization. The review further examines end-of-life recycling, composting, and biodegradation pathways; market applications across packaging, agriculture, automotive, biomedical, and electronics sectors; and the growing role of artificial intelligence and machine learning in accelerating materials design, process optimization, and lifecycle data management. Critical barriers to scale, such as cost premiums of 20–75% over conventional plastics, inadequate composting infrastructure, recycling stream contamination, regulatory fragmentation, and consumer labeling confusion, are systematically analyzed alongside mitigation strategies. The review concludes with a forward-looking discussion of emerging feedstocks, smart and functional bioplastics, and the policy and infrastructure investments required to translate the environmental promise of bio-based polymers into realized circular economy impact. Full article

Carbon dioxide water-alternating-gas (CO₂-WAG) flooding simultaneously enables carbon emission mitigation, improved oil displacement efficiency, and expanded gas sweep coverage. Nevertheless, the field performance of this technology remains significantly constrained by gravity override effects, especially in ultra-thick oil reservoirs. In this work, a synthetic heterogeneous dipping mechanistic reservoir model is constructed. Using a quantitative metric for gravity override index in WAG processes, the variation patterns of gravity override under various operational factors are systematically analyzed. Furthermore, the eXtreme Gradient Boosting (XGBoost) machine learning algorithm is employed to conduct feature importance analysis of the controlling factors, identifying parameters with the most substantial impacts. The results indicate that well spacing, oil production rate, WAG injection strategy, and WAG slug duration all exert pronounced effects on both gravity override index and oil recovery factor. Gravity override is confirmed as the dominant factor governing the production performance of WAG flooding in ultra-thick reservoirs. In addition, an optimal combination of operational parameters exists that counterbalances the adverse effects of gravitational and viscous forces, thereby maximizing gas sweep efficiency, delaying gas breakthrough, and enhancing oil recovery. This study provides valuable insights and technical guidance for gas channeling mitigation, vertical gas sweep improvement, and efficient development of analogous ultra-thick reservoirs. Full article