Search Results (15,408)

This study reports on a new one-pot copolymerization process by simultaneous oxidative disulfide and β-thioester formation by reacting bifunctional monomers, 3,6-dioxa-1,8-octane-dithiol (DODT) with diacrylates, poly(ethylene glycol) diacrylate (PEGDA) and 1,6-hexanediol diacrylate (HDODA), in the presence of N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA), as the same base catalyst for both reactions, in air at room temperature with short reaction times. The resulting random copolymers consist of disulfide linkages between DODTs and β-thioester units formed by thiol-ene Michael addition click reaction. With a stoichiometric DODT/diacrylate feed ratio, diacrylate-telechelic copolymers are obtained in a single-step polymerization reaction. The T_gs of the P(DODT-co-PEGDA) copolymers are nearly constant at around −53 °C, while it decreases with increasing HDODA content in the P(DODT-co-HDODA) copolymers. Reductive degradation with thiols, such as 2-mercaptoethanol and dithiothreitol, led to chain scission via the disulfide–thiol exchange reaction. Treatment with NaOH solution resulted in further degradation by hydrolysis of the β-thioester units. These results indicate that these novel copolymers are fully degradable under mild conditions. This new process, applying simultaneous thiol oxidation and thiol-ene reactions, enables to prepare a large variety of sulfur-containing end-functional degradable copolymers useful for a broad range of advanced application possibilities. Full article

The effect of rotary swaging (RS) at room temperature and subsequent annealing at 350 °C on the microstructure, mechanical properties, and fatigue strength of Cu–35.8%Zn two-phase brass was studied. A structure with grains of α and β′ phases elongated along the deformation direction was formed after RS. It was also shown that subgrains of 200–300 nm in size, shear bands 100–200 nm wide, and deformation twins 10–30 nm wide were formed inside the α-phase grains. RS caused the increase in the yield stress (YS) from 93 ± 4 to 717 ± 6 MPa and the ultimate tensile strength (UTS) from 332 ± 2 to 744 ± 19 MPa with a decrease in ductility (El) from 71.0 ± 2.0 to 10.3 ± 1.7%. The fatigue limit also increased from 240 to 415 MPa after RS. Subsequent annealing at 350 °C induced recrystallization of the α-phase with the formation of equiaxed grains 2.2–3.6 µm in size, which resulted in a decrease in UTS to 462–466 MPa and an increase in ductility to 44–45%. Extending the annealing time to 4 h did not affect the strength and ductility values of the alloy. Full article

To mitigate clay hydration and wellbore instability during deepwater drilling, a pH/temperature dual-responsive graft copolymer, hyperbranched polyethylenimine-g-poly(2-(dimethylamino)ethyl methacrylate) (HPEI-g-PDMAEMA), was designed and synthesized via free radical polymerization. Optimized synthesis at an HPEI/DMAEMA mass ratio of 1:2 with 2.4% AIBN at 70 °C for 10 h yielded a grafting ratio of 35.2% and a molecular weight of 84.3 kDa. The copolymer exhibits a tunable lower critical solution temperature (LCST) of approximately 48 °C at pH 8, decreasing with increasing pH due to tertiary amine deprotonation. Zeta potential measurements confirm that the polymer retains a positive charge (+5 mV at pH 8) under weakly alkaline conditions, enabling strong electrostatic anchoring onto negatively charged clay surfaces. Above the LCST, dynamic light scattering reveals a sharp increase in hydrodynamic diameter from ~30 nm to >200 nm, confirming a hydrophilic-to-hydrophobic transition of PDMAEMA segments that drives the formation of a hydrophobically associated gel barrier. This thermally triggered gelation is fully reversible, as evidenced by repeated heating–cooling cycles with almost complete transmittance recovery. The gel barrier drastically reduces water uptake, with inhibition performance against clay swelling at 60 °C being 18.5 percentage points higher than that at 25 °C. Hot-rolling tests demonstrate that with only 1.5 wt% inhibitor, shale recovery reaches 94.1% at 150 °C (8.8 percentage points higher than unmodified HPEI) and remains above 60% even in 20 wt% CaCl₂ or MgCl₂ brines, highlighting exceptional resistance to divalent cations. Water contact angle on treated clay surfaces increases from 18.5° to 52.6°, confirming effective surface hydrophobization. This work provides a molecular-level gel-engineering strategy where pH governs electrostatic anchoring and temperature triggers reversible hydrophobic gelation, enabling on-demand switching of clay wettability and hydration resistance under high-temperature, high-salinity conditions. Full article

Blueberry juice is valued for its distinctive flavor and health-promoting bioactive compounds, but thermal processing and subsequent storage can alter its quality and aroma. While previous studies have focused on total volatile profiles, the behavior of chiral aroma compounds—particularly linalool enantiomers—during processing and storage remains poorly understood. This study aimed to investigate the effects of pasteurization (PT, 90 °C for 30 s) and ultra-high temperature processing (UHT, 135 °C for 6 s) on the physicochemical properties, bioactive compounds, antioxidant activity, volatile profiles, and sensory characteristics of blueberry juice during storage at 4, 25, and 35 °C for 4 weeks, with a special emphasis on the enantiomeric changes in linalool. A chiral column-based GC-MS method was established to quantify (R)- and (S)-linalool enantiomers, given their distinct odor thresholds and sensory contributions. The results showed that both thermal treatments ensured microbial safety, but UHT caused greater color deterioration, loss of phenolics and anthocyanins, and formation of off-flavor compounds. PT better preserved color, bioactive components, and natural fruity aroma. Storage temperature was the dominant factor driving quality decline, with 4 °C significantly retarding deterioration. Notably, the two thermal processes exhibited distinct mechanisms affecting chiral linalool stability: PT primarily induced isomerization of (R)-linalool to the (S)-form, leading to a gradual decrease in the R/S ratio, whereas UHT led to direct degradation of (R)-linalool, resulting in a more rapid shift in the R/S ratio under the same conditions. These findings highlight the importance of monitoring enantiomeric composition rather than total linalool content for flavor quality assessment. The combination of PT and refrigerated storage (4 °C) is recommended to maximize overall quality retention, as PT better preserves the natural chiral balance of linalool. This study demonstrates that appropriate thermal processing and low-temperature storage are effective strategies to maintain the quality and chiral flavor stability of blueberry juice, providing new insights into the role of enantiomer-specific changes in processed fruit products. Full article

The creep-rupture behavior and microstructural evolution of Ni–Fe-based alloy/Inconel 617 dissimilar welded joints were investigated by creep-rupture testing, interrupted creep testing, and microstructural characterization. Tests were conducted at 630–750 °C under stresses of 130–375 MPa. All joint specimens fractured in the heat-affected zone (HAZ) or base metal (BM) on the Ni–Fe-based alloy side, indicating that the Ni–Fe-based alloy side was the creep-critical region of the joint. Three failure regimes were identified according to the relative rupture lives of the joints and the Ni–Fe-based alloy BM. Fractographic observations revealed predominantly intergranular fracture, with creep cavities and cracks preferentially associated with grain-boundary discontinuous precipitation (DP) regions containing coarsened rod-like γ′ precipitates and precipitate-free zones (PFZs). Differences in DP evolution between the HAZ and BM were closely related to creep-damage localization and failure behavior. Interrupted creep tests showed that temperature was the dominant factor affecting DP formation and growth, while applied stress accelerated its evolution. DP developed rapidly during the initial exposure stage and subsequently grew more slowly. These findings clarify the relationship between grain-boundary DP evolution and creep-rupture failure in Ni–Fe-based alloy/Inconel 617 welded joints, and also provide microstructural guidance for assessing and mitigating creep degradation in dissimilar welded components used in high-temperature A-USC systems. Future work should combine longer-term creep testing, phase-resolved microstructural characterization, and predictive modeling to establish quantitative relationships among DP evolution, creep-damage accumulation, and rupture life. Full article

Lithium-ion batteries undergo coupled thermal and mechanical responses during operation, which are closely related to their safety and reliability. However, simultaneously monitoring the surface temperature and strain fields of large-format prismatic batteries remains challenging. In this study, a fiber Bragg grating (FBG) array-based dual-parameter sensing system was developed to synchronously measure the temperature and strain of a 314 Ah lithium iron phosphate battery during charge–discharge cycling under different power conditions. Continuous surface temperature and strain fields were reconstructed from the measured data to investigate their spatiotemporal evolution. The results reveal significant differences between the temperature and strain distributions as well as asynchronous dynamic responses. Spatially, with increasing power, temperature hotspots shifted toward the central region, whereas strain extrema migrated toward the positive electrode side, revealing distinct spatial heterogeneity in the thermo-mechanical response. Temporally, the strain extrema consistently appeared tens to hundreds of seconds earlier than the temperature peaks. These findings provide direct experimental evidence of the thermo-mechanical coupling behavior of large-capacity lithium-ion batteries, establish baseline temperature–strain distributions under normal operating conditions, and offer valuable guidance for battery state evaluation, thermal management, and early fault diagnosis. Full article

With the continuous decline in easily recoverable reserves of conventional oil and gas, the focus of oil and gas exploration and development has gradually shifted toward complex reservoirs, such as low-permeability, tight, high-temperature and high-pressure (HTHP), and strongly heterogeneous reservoirs. Such reservoirs are characterized by complex pore–throat structures, poor seepage capacity, extreme temperature and pressure conditions, and strong heterogeneity. Traditional acidizing technologies face multiple challenges, including short effective penetration distances, system instability at high temperatures, uneven stimulation, and a tendency to induce secondary formation damage, making it difficult to meet the requirements for highly efficient reservoir stimulation. This paper systematically analyzes the petrophysical properties and acidizing challenges of four typical types of complex reservoirs. It reviews the reaction mechanisms, research and development progress, and reservoir adaptability principles of six acid systems, and elaborates on the application value of molecular simulation technology in acid–rock reaction analysis, formulation optimization, and injection regulation. The review indicates that, under extreme operating conditions, existing technologies still suffer from inadequate system stability, limited deep mass transfer, and environmental concerns. Future research should deepen the understanding of multi-scale acid–rock reaction mechanisms, develop composite acid systems tolerant to extreme conditions, and drive the development of acidizing technologies toward refinement and intelligentization. Full article

The increasing depth of oil wells and associated elevated formation temperatures pose significant challenges to conventional crosslinked polymer gels used in hydraulic fracturing, as viscosity degradation severely impairs proppant transport and stimulation efficiency. In this study, a thermally stable organic boron crosslinker was developed and evaluated in combination with hydroxypropyl guar gum (HPG). The rheological performance of the crosslinked gel system was systematically investigated under high-temperature shearing conditions. At a guar gum concentration of 0.5 wt% and a crosslinker-to-gum ratio of 100:0.5, the system maintains a viscosity of 500 mPa·s at 120 °C and 170 s⁻¹, and the viscosity remains above 300 mPa·s after 60 min of continuous shearing, demonstrating outstanding thermal resistance. (For 0.3 wt% HPG, the optimal crosslinking ratio is 100:0.3; for 0.5 wt% HPG, the optimal ratio is 100:0.5). This gel formulation achieves efficient proppant transport with minimal additives. It maintains static proppant suspension for up to 48 h. After breaking, the fluid viscosity drops to approximately 5 mPa·s. With the addition of a flowback aid, surface tension can be reduced to as low as 16.29 mN/m, while the formation matrix permeability damage rate is limited to only 20.76%. Additionally, the gel features rapid breaking and low residue generation, making it highly suitable for high-temperature fracturing operations. Full article

Oil palm empty fruit bunches (EFB) are lignocellulosic residues generated in large quantities by the palm oil industry and represent a potential biomass resource for renewable hydrogen production. This study evaluated the inherent safety of an indirect gasification process of empty fruit bunches (EFB) for hydrogen production, coupled with purification via pressure swing adsorption (PSA), using the Inherent Safety Index (ISI) methodology. The assessment considered critical operating variables, including temperature and pressure, and integrated chemical sub-indices (toxicity, flammability, chemical interaction, and corrosivity) with process sub-indices (inventory, temperature, pressure, equipment, and process structure). The analysis yielded a total ISI of 36, exceeding the reference value of 24 used in the original ISI framework and indicating an unfavorable inherent-safety profile under the evaluated conceptual design conditions. The main hazard drivers were the combined flammability, explosiveness, and toxicity contribution governed by CO; the high individual explosiveness of H₂; the toxicity of SO₂; the potential formation of explosive mixtures following air ingress; and the relatively large process inventory. The indirect gasification section, reaching a maximum verified temperature of 900 °C and a maximum operating pressure of 60 bar, governed the temperature and pressure sub-indices, respectively. These findings identify significant inherent-safety challenges that should be addressed during subsequent process development. In particular, inventory minimization, prevention of air ingress, and evaluation of less severe temperature and pressure conditions where technically feasible represent relevant priorities for inherently safer design before industrial-scale implementation. Full article

Tectonic activity can induce deformation or failure of shale formations, thereby altering their macroscopic and microscopic structures to varying degrees. Naturally deformed shale samples from the Lower Cambrian Qiongzhusi Formation in the Dabashan Thrust-fold Belt, northeast Sichuan Basin, were investigated using scanning electron microscopy (SEM), low-temperature gas adsorption, and fractal analysis to characterize the nanoporous structure of organic matter. The results show the following: (1) SEM observations indicate that the organic nanopores are predominantly subcircular, with shape factors ranging from 0.736 to 0.859 and an average areal porosity of 7.678%. The pore diameters are mainly distributed within 10–50 nm, with micropores and mesopores being dominant, showing typical nanoscale pore characteristics. (2) Gas adsorption results show that the organic mesopores are mainly distributed within 20–30 nm. Their average pore volume and specific surface area are 0.169 cm³/g and 33.318 m²/g, respectively, indicating a relatively small number of mesopores and a low degree of mesopore development. The organic micropores exhibit a trimodal pore-size distribution, with peaks at 0.3–0.4 nm, 0.4–0.6 nm, and 0.75–0.85 nm. Their average pore volume and specific surface area are 0.012 cm³/g and 38.975 m²/g, respectively. (3) The fractal dimensions of the organic nanopores calculated using the box-counting method, the FHH model, and the V-S model are 1.280, 2.524, and 2.448, respectively, indicating relatively low pore-structure complexity and heterogeneity in the organic matter of the shale. Full article

The requirement of energy efficiency in designs of sustainable aquaponics has brought about the incorporation of passive solar systems and earth–air heat exchangers (EAHE). In this study, an evaluation of the physiological effects that arise from the implementation of the use of underground thermal stabilization by means of heat exchangers and the limitations of this technology will be carried out. The greatest strength of this technology is the “thermal buffer” that is created in the physiology of the fish; this technology makes the fish resilient to changes in environmental temperatures, thus reducing energy usage. However, the weakness is that there are ecological risks involved, such as moisture build-up due to low air exchange and biofilm formation in pipes, which occur when this technology is used without biological controls. This review highlights the critical balance between energy efficiency and biological safety while analyzing the impacts of these technological advantages on growth performance, metabolic regulation, and physiological stress responses in fish. This review demonstrates that, beyond improving heating and cooling efficiency, successful implementation of EAHE-assisted passive solar aquaponics depends on balancing engineering performance with biological requirements, including thermal regulation, gas exchange, humidity control, and biosecurity. Full article

Total postharvest losses of fresh fruits and vegetables in tropical and subtropical agricultural systems frequently exceed 30 percent, driven by high crop perishability, limited cold-chain infrastructure, and the geographic concentration of conventional processing facilities far from production zones. This review examines the engineering principles, operational architecture, and applied performance of mobile aseptic processing platforms (MAPPs) as a decentralized strategy for postharvest stabilization of perishable agricultural commodities. MAPPs integrate in-line homogenization, high-temperature short-time (HTST) or ultra-high-temperature (UHT) thermal treatment, clean-in-place (CIP) and sterilization-in-place (SIP) cycles, and aseptic filling within transportable, modular units engineered for field deployment. Projected MAPP capacities reach up to approximately 11,300 kg (25,000 lb) per 8 h shift, while still complying with internationally recognized food safety frameworks, including HACCP, ISO 22000, and SQF. Comparative analysis with centralized processing infrastructure and earlier decentralized initiatives, including the EU Horizon 2020 Food Processing in a Box (FOX) project, indicates that mobile aseptic systems uniquely combine field mobility with the production of ambient-stable shelf-life formats independent of refrigerated distribution. Conservative impact modeling suggests that single-unit deployments may recover on the order of 3000 t of edible product annually, with corresponding water, fertilizer, and greenhouse gas externality reductions. The review synthesizes the current state of the technology, identifies engineering and socioeconomic knowledge gaps, and proposes research priorities for scaled adoption in tropical and subtropical food systems. Full article

Global oil and gas exploration and development are gradually expanding into deep and ultra-deep formations. Deep limestone exists in a long-term multi-field coupled environment featuring high temperature, high in situ stress and high pore pressure, which brings great challenges to reservoir stimulation and wellbore stability. To investigate the effects of confining pressure and pore pressure on limestone under high temperatures, triaxial compression tests were conducted on limestone at various temperatures (25~150 °C) using the GCTS RTR-2000 rock mechanics testing system. This paper investigates the evolution laws of strength and deformation parameters of limestone under varied temperature, confining pressure and pore pressure. The results indicate that: (1) Within the 25~150 °C range, the peak strength and elastic modulus of limestone exhibit a “decrease-then-increase” trend, with a strength rebound occurring at 150 °C driven by the “thermal expansion and compaction” effect. (2) Under a pore pressure of 50 MPa, temperature and confining pressure exert a significant coupled control effect on the mechanical properties of the rock, characterized by a critical confining pressure threshold of approximately 100–110 MPa. Below this threshold, high temperature acts as a weakening factor, whereas above it, high temperature acts as a strengthening factor and induces intense brittle failure under high pressure. (3) In the pore pressure coupling tests, the rock undergoes ductile failure as confining pressure increases at normal/room temperature, while a temperature of 100 °C strengthens the rock under high confining pressure. (4) Energy evolution analysis reveals that within the 75~125 °C range, the thermal pressurization of pore water and local thermal stresses induce massive microcracks, causing the dissipated energy to surge sharply to nearly 80%. The research findings provide a theoretical basis for wellbore stability analysis and fracturing parameter optimization in deep carbonate reservoirs. Full article

Winter wheat is a cornerstone of China’s grain production, contributing substantially to national food security and overall cereal output. This study modeled the nonlinear associations between multitemporal remote sensing variables and winter wheat yield. To produce high-spatiotemporal-resolution inputs, we used the Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model (ESTARFM) to integrate Sentinel-2 normalized difference vegetation index (NDVI) data with MODIS NDVI data, generating NDVI composites at 8-day intervals with a 10-m spatial resolution. The NDVI, actual evapotranspiration (ET), land surface temperature (LST), precipitation (PRE), and soil moisture (SM) were selected as predictors for yield estimation because they are closely associated with winter wheat growth and yield formation during primary growth stages. By integrating the local temporal feature-learning capacity of a one-dimensional convolutional neural network (1-D CNN) with the strength of a bidirectional long short-term memory (BiLSTM) model in capturing temporal dependencies within time series, a BiLSTM–CNN model was constructed for wheat yield estimation and prediction. The BiLSTM–CNN model showed higher estimation accuracy than individual BiLSTM and 1-D CNN models, with an R² of 0.69 and root mean square error (RMSE) of 478.68 kg/hm². The use of all the parameters produced the best estimation performance among all the parameter combinations. Approximately two months before harvest, the model still provided satisfactory yield prediction accuracy. This study provides an important theoretical basis for high-accuracy regional winter wheat yield estimation and pre-harvest forecasting. Full article

Three-dimensionally (3D)-printed alpha-tricalcium phosphate (α-TCP) scaffolds, fabricated through a low-temperature hydrothermal dissolution-precipitation process, replicate the structural and compositional features of native bone. Reinforcing hydrothermally processed α-TCP with poly(lactic-co-glycolic acid) (PLGA) as a binder has previously been shown to confer distinct mechanical advantages, supporting its potential as a viable material for bone regenerative scaffolds. Although the hydrothermal processing of α-TCP scaffolds and PLGA-based mechanical reinforcement have each been characterized individually in earlier studies, this work represents the first pre-clinical in vivo assessment of osseoconduction and biocompatibility of 3D-printed, PLGA-reinforced, self-hardening calcium phosphate scaffolds in a large translational animal model. A ceramic ink suitable for extrusion was prepared by combining a 30 wt/vol% poloxamer 407 solution with α-TCP powder at a 0.45 wt/wt ratio (CTRL). A second extrudable ink, consisting of an α-TCP ceramic suspension incorporating a 35 wt/wt% PLGA binder, was formulated at a 0.5 wt/wt ratio (EXP). Cylindrical scaffolds (6 mm × 6 mm) were fabricated at room temperature using a custom-built Direct Ink Write 3D printer, then hydrothermally treated via submersion in water and thermal consolidation at 121 °C. Osteotomies were created in the ilium of adult sheep, with two cylindrical defects (7 mm × 6 mm) per animal, each receiving either a CTRL or EXP scaffold. Animals were euthanized at 3 and 12 weeks post-surgery (n = 6 animals per time point), and samples were collected en bloc for analysis. For both scaffold formulations, hard tissue formed by 12 weeks displayed high cellularity and active vascularization, consistent with early woven bone formation. Quantitative analysis revealed no significant between-group differences in bone formation at either time point (p > 0.05). These findings indicate that 3D-printed, PLGA-reinforced, self-hardening α-TCP scaffolds are osseoconductive and biocompatible, supporting their potential use in orthopedic and craniomaxillofacial bone defect repair. Full article