Search Results (11,493)

CO₂-enhanced gas recovery (CO₂-EGR) is a crucial technology for achieving both natural gas production increase and CO₂ geological storage. While pure CO₂ flooding demonstrates favorable recovery performance, the technical challenges and high costs associated with purifying CO₂ remain significant. CO₂ purification from exhaust gas incurs prohibitive costs, while direct injection of an unpurified CO₂–N₂ mixture can greatly cut engineering expenditure. Nitrogen also provides synergistic pressure support, working with CO₂ to drive natural gas displacement. Therefore, from an economic and practical standpoint, employing impure CO₂ mixtures (e.g., CO₂–N₂) for flooding presents a more advantageous approach. To clarify the factors influencing the recovery enhancement in tight sandstone gas reservoirs using CO₂–N₂ mixtures, long-core flooding experiments were conducted at 100 °C. This study systematically investigates the impact patterns of three key factors—injection timing, injection rate, and injection gas composition—on the enhanced recovery of tight sandstone gas reservoirs. The experimental results indicate that: (1) Advancing the injection timing significantly improves the recovery performance for both CO₂ and N₂ flooding. However, the cumulative recovery factor (sum of the depletion recovery and the incremental recovery from gas injection) shows a declining trend. (2) The enhanced recovery effect exhibits a trend of first increasing and then decreasing with the increase in injection rate. When the injection rate exceeds 0.05 mL/min, it tends to cause premature breakthrough of the injected gas, thereby reducing the displacement efficiency. (3) As the proportion of CO₂ in the injected gas increases, the enhanced recovery effect shows a nonlinear rise. The highest incremental recovery (17.02%) was achieved with pure CO₂ flooding, while pure N₂ flooding yielded the lowest result (14.64%). The research findings, from a macroscopic perspective, elucidate the influence patterns of three distinct factors on enhancing gas recovery in tight sandstone reservoirs, thereby providing theoretical foundation and scientific guidance for the development of such reservoirs. In summary, the injection timing, injection rate and CO₂ proportion in injected gas are the key controlling factors for gas flooding enhanced recovery in tight sandstone reservoirs. This study clarifies the macroscopic influence law of each factor, and the optimized development parameters proposed can provide direct theoretical support and technical guidance for the on-site application of gas flooding in tight sandstone reservoirs. Full article

Isobutane is a key feedstock for alkylate production. For separating an equimolar isobutane/n-butane mixture with 2 mol% ethane, two conventional designs are reported in the literature: a single water-cooled condenser (SC) and a dual condenser system with refrigeration (DC). This study proposes two vapor recompression retrofit configurations, SC-VR and SC-PHVR (with preheating), to improve energy efficiency and enable electrification. Economic and environmental performance were evaluated using total annualized cost (TAC) and CO₂ emissions. Compared with SC and DC schemes, SC-VR reduces CO₂ emissions by 49 and 52%, while SC-PHVR delivers higher reductions of 64 and 66%. A sensitivity analysis of electricity prices across 3-, 5-, and 10-year payback periods indicates the most favorable performance at 10 years. At 16.67 USD/GJ, SC-PHVR lowers TAC by 22 and 25%; in contrast, SC-VR provides marginal savings. At 24.03 USD/GJ, SC-VR is not economically competitive, whereas SC-PHVR continues to outperform the conventional cases, with TAC reductions of 8% and 4%. Both retrofit options significantly reduce emissions, with SC-PHVR offering the best economic performance. Finally, the proposed configurations enable the complete electrification of the de-isobutanizer system, eliminating reliance on fossil-based thermal utilities, which allows the use of renewable sources in line with the decarbonization efforts. Full article

N,N-Dimethyl-1,3-propanediamine (DMAPA) is an important aliphatic diamine widely used in fine chemical manufacturing. Its industrial production traditionally relies on Raney nickel catalysts, which suffer from pyrophoric hazards and limited selectivity due to imine condensation side reactions. To address these challenges, we report an Al₂O₃-supported Ni-Cu alloy catalyst as an efficient alternative for the selective hydrogenation of N,N-dimethylaminopropionitrile (DMAPN). The optimized Ni₃₀Cu₅/Al₂O₃ catalyst achieves complete DMAPN conversion and over 90% DMAPA selectivity under industrially relevant conditions (120 °C, 2.5 MPa H₂). X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy analyses confirm the formation of substitutional Ni-Cu alloy nanoparticles, where Cu incorporation induces both geometric isolation of Ni ensembles and electronic modulation of surface active sites, thereby suppressing condensation-derived by-products. In addition, an NH₃/ethanol-assisted process further improves selectivity while reducing autogenous operating pressure. Overall, this work demonstrates a safe and highly selective catalytic system for primary diamine synthesis, providing a practical alternative to conventional Raney Ni-based processes. Full article

Abiotic stresses including drought, salinity, heat, cold, and heavy metal toxicity severely constrain plant productivity worldwide. Nitrogen (N), beyond its fundamental nutritional role, has emerged as a central regulator of plant stress responses through its involvement in metabolic reprogramming, osmotic adjustment, antioxidant defense, and hormonal signaling. This review synthesizes current advances in understanding how nitrogen availability and form influence plant tolerance to major abiotic stresses. Particular emphasis is placed on nitrogen-mediated modulation of reactive oxygen species (ROS) scavenging systems, nitrogen–carbon metabolic coordination, phytohormonal crosstalk, osmoprotectant biosynthesis, and regulation of stress-responsive gene expression. Recent molecular insights highlight the role of nitrogen transporters, nitrate signaling pathways, and nitrogen-use efficiency in stress adaptation mechanisms. Furthermore, agronomic and biotechnological strategies aimed at optimizing nitrogen management to enhance stress resilience are discussed, including precision fertilization, integrated nutrient management, and genetic approaches targeting nitrogen-responsive regulatory networks. By integrating physiological, biochemical, and molecular perspectives, this review provides a comprehensive framework for understanding nitrogen-driven mitigation strategies under abiotic stress conditions and outlines future research directions for sustainable crop production in changing environments. Full article

To address the complex dynamic mechanisms and lack of static operation data in trench-digging for transverse planting of Salix psammophila sand barriers, a transverse trench-digging device was designed. Based on the discrete element method, the Hertz–Mindlin with JKR Cohesion model was used to simulate sandy soil. The Box–Behnken experiment was adopted to optimize the single auger structure with helix angle and soil-cutting angle as factors and trench depth and working torque as indices, yielding the optimal parameters of 30° soil-cutting angle and 20.37° helix angle (5.52 cm trench depth, 2.6 N·m maximum torque). The optimized auger was integrated into the device, and a further Box–Behnken experiment was conducted under a 20 cm fixed descending depth of the lifting platform. With auger rotation speed, shaft spacing and lifting speed as factors, and trench depth, soil compaction and Salix psammophila insertion depth as indices, the optimal operating parameters were determined as 257.25 r/min, 7 cm and 9 cm/s, corresponding to 6.7 cm trench depth, 33.37 kPa soil compaction and 14.87 cm insertion depth. This study clarifies the effects of auger and operation parameters on trench-digging quality, provides a basis for the design and parameter matching of dynamic continuous operation equipment, and offers a reference for the R&D of mechanized transverse planting equipment for Salix psammophila sand barriers, which is of practical value for reducing sand control costs and improving efficiency. Full article

Traditional oxidative dehydrogenation of n-butene has typically required relatively high operating temperatures (400–500 °C), which has driven increasing interest in the development of catalysts capable of delivering high activity at lower temperatures. In this study, zinc ferrite (ZnFe₂O₄-ST) was successfully synthesized via hydrothermal hydrolysis of Zn–Fe oleate and demonstrated remarkable catalytic performance for the oxidative dehydrogenation of n-butene under mild conditions. At 300 °C, ZnFe₂O₄-ST achieved a conversion of 72.9% with 92.1% selectivity toward 1,3-butadiene, a result that, to the best of our knowledge, ranks among the best reported in the literature. By contrast, ZnFe₂O₄ prepared by conventional coprecipitation (17.2% conversion with 91.3% selectivity) and sol-gel (10.1% conversion with 86.4% selectivity) methods showed much lower activities, highlighting the critical influence of synthesis strategy on catalytic performance. To better understand the origin of these differences, a detailed structural and physicochemical characterization was undertaken using X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), N₂ adsorption–desorption, X-ray photoelectron spectroscopy (XPS), H₂-temperature-programmed reduction (H₂-TPR), temperature-programmed re-oxidation (TPRO), and NH₃-temperature-programmed desorption (NH₃-TPD). These analyses revealed that the as-synthesized ZnFe₂O₄-ST possessed a significantly smaller average particle size, a larger specific surface area, and superior reducibility compared with the other samples. These properties are believed to be the key factors underpinning its outstanding catalytic behavior and provide important insights into the design of efficient low-temperature catalysts for selective oxidative dehydrogenation Full article

Compost-derived humic acids (HAs) and fulvic acids (FAs) play an essential role in enhancing soil microbial diversity and activity by facilitating metabolic processes through electron transfer. Herein, the effect of bioleaching dewatered sludge (BDS) in comparison with filter press dewatered sludge (FDS) on the electron transfer capacity (ETC) of humic substances during composting was investigated as a novel attempt. A variety of characterization methods including UV-Vis, FTIR, 3D-EEM, and electrochemical measurements, were used to explore the change in humic substances during composting. The results indicated that bioleaching treatment significantly influenced the organic matter composition and hindered the accumulation of redox-active functional groups during composting. Notably, the ETC of HA increased by 24.07% in the FDS group but declined by 40.62% in the BDS group. This divergence stemmed from the organic matter loss during bioleaching, leading to reduced quinone-like and tryptophan-like substances associated with electron transfer in HA during composting. Furthermore, BDS showed lower pH, water content, and organic matter, but higher concentrations of ammonium nitrogen (${\mathrm{NH}}_4^{+}\text{-}\mathrm{N}$) and ammonia nitrogen ${\mathrm{NH}}_3^{-}\text{-}\mathrm{N}$, all of which potentially influenced humification efficiency. These findings not only clarify the electron-transfer dynamics of humic fractions but also highlight the importance of optimizing sludge pretreatment for improved composting performance and resource recovery. Full article

Proiphys amboinensis has considerable potential as a commercial ornamental plant due to its attractive foliage, distinctive flowers, and long flowering period. This study established an in vitro micropropagation protocol and evaluated the genetic fidelity of regenerated bulblets using Inter Simple Sequence Repeat (ISSR) markers and flow cytometry. Twin-scale explants were cultured on Murashige and Skoog (MS) medium supplemented with 0, 0.5, 1.0, and 2.0 mg/L N⁶-benzyladenine (BA) for 12 weeks. Bulblet formation efficiency ranged from 60.00 ± 16.33% to 70.00 ± 11.55%, with no significant differences among treatments. A significant increase in bulblet number was observed at 1.0 mg/L BA compared with the control and 0.5 mg/L BA; however, bulblet fresh weight did not differ significantly among these treatments. Sucrose concentrations (30–90 g/L) had no significant effects on bulblet weight and diameter. Root induction was evaluated using indole-3-butyric acid (IBA) and α-naphthaleneacetic acid (NAA) at concentrations of 0–1.0 mg/L, with 0.5 mg/L IBA identified as the optimal treatment. Following acclimatization, regenerated bulblets exhibited high survival rates (90–100%). ISSR and flow cytometric analyses revealed no detectable genetic variation, with a consistent genome size between regenerated bulblets and the mother plants, indicating high genetic uniformity. The protocol provides a micropropagation system for P. amboinensis with high genetic fidelity, supporting its commercial and research potential. Full article

The non-repeatability of the internal combustion engine’s cycle-by-cycle (CCN-R) operation directly affects pollutant emissions, fuel consumption, and energy efficiency. Reducing this non-repeatability is an important part of efforts to improve the environmental performance of power units. Cycle variability analysis allows the identification of engine operating areas that promote unstable combustion and increased emissions of harmful exhaust components. The aim of the study was to quantitatively assess the cycle-to-cycle non-repeatability COV of selected operating parameters of the Perkins 1104D-E44TA diesel engine. The analyses covered the maximum cylinder pressure (p_max), the mean indicated pressure (IMEP), and the crankshaft rotation angle corresponding to the occurrence of maximum pressure (α). The measurements were carried out on an engine dynamometer at 25 operating points, covering speeds 1000–2200 r./min and load torques 200–400 N × m, recording 500 consecutive operating cycles at each point. The results showed that the most stable engine operation occurred at medium rotational speeds and moderate loads, where COV_pmax values did not exceed 0.5% and COV_IMEP values were lower than 1.0%. Increased pmax non-repeatability (up to 2.10%) and very high α angle variability (up to 100–140%) were observed at high rotational speeds and high loads. Only in the case of COV_IMEP was a significant reduction in repeatability observed compared to idling. The results obtained from cycle-by-cycle non-repeatability analyses can ultimately, after being supplemented with exhaust gas composition testing, be used as tools to support engine control optimization in order to reduce pollutant emissions and improve combustion efficiency. Full article

Local path tracking is a critical challenge for autonomous vehicles, requiring precise trajectory following under nonlinear dynamics, strict constraints, and real-time execution. While Nonlinear Model Predictive Control (NMPC) has emerged as a leading approach, many existing methods decouple velocity planning from tracking, lack formal stability guarantees, or do not demonstrate feasibility on embedded platforms. We present a unified NMPC framework that integrates curvature-aware velocity adaptation directly into the cost function. The controller makes use of cubic spline paths, recursive feasibility constraints, and Lyapunov-based terminal costs to ensure stability. The nonlinear optimization problem is implemented in CasADi and solved using IPOPT, with warm-starting and efficient discretization techniques enabling real-time performance. Our approach has been validated in the CARLA simulator across a variety of urban scenarios, including straight roads, intersections, and roundabouts. The controller achieves a mean cross-track error of 0.10 m on straight roads, 0.44 m on roundabouts, and 1.36 m on tight intersections, while maintaining smooth control inputs and bounded actuator effort. A curvature-aware cost term yields a 14.4% reduction in lateral tracking error compared to the curvature-unaware baseline. Benchmarking results indicate that the Raspberry Pi 5 outperforms the NVIDIA Xavier AGX by 1.5–1.6×, achieving mean execution times of 38–45 ms across all scenarios. This demonstrates that advanced NMPC can run in real time on low-cost consumer hardware ($80 vs. $700). Systematic ablation studies reveal the critical role of state weighting (Q) and input regularization (R): removing Q degrades tracking by 10% and destabilizes control effort (+54% acceleration, +477% steering), while omitting R induces oscillatory behavior with +907% acceleration effort. Euler integration provides no computational benefit (+8% solver time) while degrading accuracy by 25%, confirming RK4 as strictly superior. Sensitivity analysis via Latin Hypercube Sampling identifies the prediction horizon (N) and discretization timestep ($\mathrm{\Delta }t$) as dominant parameters. Per-scenario Pareto analysis yields a balanced operating point ($N=15, \mathrm{\Delta }t=0.055$ s) used for all primary evaluations, while a global sweep identifies a robust alternative ($N=12, \mathrm{\Delta }t=0.086$ s) suitable for general deployment tuning. This framework bridges the gap between spline-based local planning and stability-guaranteed NMPC, offering a simulation-validated, real-time solution for embedded autonomous driving research. Future work will focus on hardware-in-the-loop and full-vehicle deployment, integration with high-level decision-making, and learning-enhanced MPC. Full article

In this work, hydrogenated amorphous silicon carbide (a-SiC_x:H) and hydrogenated amorphous silicon oxide (a-SiO_x:H) films with similar optical bandgaps (E_g), refractive indices (n), and extinction coefficients (k) were fabricated using pulse-wave modulation (PWM) plasma technology by controlling the plasma turn-on to turn-off time ratio (t_on/t_off). These films were placed at the 1/5 position of the p/i and i/n interfaces of hydrogenated amorphous silicon (a-Si:H) p-i-n solar cells to investigate their influence on solar cell performance. The experimental results confirmed that the deviations in E_g, n, and k were controlled to within 0.2%, 1.4%, and 4.1%, respectively. Under these conditions, placing a-SiC_x:H and a-SiO_x:H films at the p/i and i/n interfaces successfully increased the open-circuit voltage (V_oc). However, this also led to a decrease in the short-circuit current due to valence band (ΔE_v) or conduction band (ΔE_c) offsets. The reduction in cell fill factor (FF) and efficiency (η) caused by placing a-SiC_x:H and a-SiO_x:H films at the p/i interface was greater than that caused by placing them at the i/n interface. Placing the a-SiC_x:H film at the p/i interface significantly improved the V_oc to 0.8998 V. Due to the n-type doping effect of oxygen atoms, the a-SiO_x:H film exhibited the lowest FF of 43.99% and η of 4.850% at the p/i interface; however, when placed at the i/n interface, it yielded an FF of 67.38% and an η of 7.43%, which are comparable to the standard cell. Appropriately placing the a-SiC_x:H film at the p/i interface and the slightly n-type a-SiO_x:H film at the i/n interface can effectively improve the V_oc, FF, and η of p-i-n solar cells. Full article

Efficient liquid storage of turkey semen is critical for artificial insemination, but its use is limited by bacteriospermia and oxidative damage. This study evaluated the effects of gentamicin supplementation in Glutac and Sperm Motility Medium (SMM) on bacterial load and sperm quality after 2 and 24 h of liquid storage. Semen from turkeys (n = 40) was assessed for motility, viability, plasma membrane and acrosome integrity, mitochondrial and metabolic activity, oxidative profile, apoptosis, DNA integrity, and microbiological status. The sperm motility and kinematic parameters declined significantly after 24 h in all the groups. However, both extenders (particularly SMM) maintained significantly higher motility than the untreated control. Gentamicin further improved the motility, viability, and plasma membrane and acrosome integrity. The mitochondrial activity and mitochondrial membrane potential were significantly higher in the extender-treated groups than in the controls at 2 and 24 h, whereas the superoxide and total ROS production were significantly higher in the controls. The total antioxidant capacity declined markedly in the untreated controls, especially after 24 h. Gentamicin significantly reduced bacterial load, most effectively in SMM, and decreased DNA fragmentation compared with the untreated controls. In conclusion, gentamicin supplementation—particularly in SMM—reduces bacteriospermia and oxidative stress while preserving turkey sperm quality during liquid storage. Full article

g-C₃N₄ has emerged as a promising metal-free semiconductor for optoelectronic applications due to its suitable bandgap, excellent stability, and low cost. However, enhancing its photoresponse efficiency in practical devices remains a challenge. In this work, a high-performance self-powered photodetector was developed using a g-C₃N₄/textured Si n-n heterojunction fabricated via a simple solution process. The device exhibits excellent diode characteristics with a rectification ratio of ~4.9 × 10² and an ideality factor of 1.41. It achieves broadband detection from 405 to 980 nm, a high responsivity of 3.2 A/W, a specific detectivity of 1.9 × 10¹⁴ Jones, and fast response speeds of 44/36 ms at 650 nm under zero bias. Significantly, the textured Si-based device shows approximately tenfold higher performance than its planar Si counterpart, owing to enhanced light absorption from the textured surface. The combination of excellent photoresponse and simple fabrication makes the g-C₃N₄/textured Si n-n heterojunction a promising candidate for low-cost, high-performance optoelectronic applications. Full article

This study examines administrative employees’ perceptions of integrating Artificial Intelligence (AI) into the administration of Greek public universities. Using a cross-sectional online questionnaire administered across three universities (N = 127), we map perceptions across five domains: (i) perceived efficiency/effectiveness contributions, (ii) perceived automation benefits, (iii) perceived adoption challenges, (iv) perceived ethics and data protection requirements, and (v) perceived skills development needs. Results indicate a generally supportive climate for AI use in university administration, but support is conditional: ethics and data protection are prioritized most strongly, whereas perceived efficiency/effectiveness gains are closer to neutral-to-slightly positive. Respondents endorse task-level automation more than broad organizational performance claims and emphasize training and human oversight as enabling conditions for responsible deployment. These findings suggest that a governance-first and capacity-first implementation pathway may be more aligned with staff priorities in the Greek public university context. The study provides an exploratory baseline for future evaluative research on AI-enabled administrative modernization. Full article

Hydrogen storage vessels are critical components in hydrogen energy systems, and improving their manufacturing efficiency and structural performance is essential for next-generation Type IV vessel designs. Compared with conventional wet filament winding, towpreg dry filament winding offers higher efficiency, reduced environmental impact, and better adaptability to complex structures. In this study, key process parameters, including winding tension, heating temperature, and winding speed were systematically optimized using the tensile strength and interlaminar shear strength of NOL ring specimens as evaluation metrics. A response surface methodology (RSM) regression model was established to correlate process variables with mechanical properties, followed by multi-objective optimization using the non-dominated sorting genetic algorithm II (NSGA-II) and final parameter selection through the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. The results indicate that shear strength is primarily affected by heating temperature, whereas tensile strength is mainly governed by winding tension. The optimal parameter combination (79 N, 360 °C, and 11 m/min) yielded tensile and shear strengths of 2462.2 MPa and 64.4 MPa, respectively, with prediction errors below 0.5%. A 9 L Type IV hydrogen storage vessel manufactured under these conditions showed approximately 15.4% lower mass and about 17% higher gravimetric hydrogen storage efficiency than a comparable wet wound vessel. Full article