Search Results (2,415)

In the context of a constantly deteriorating environmental situation, in particular due to the uncontrolled accumulation of plastic waste, the search for effective ways to recycle plastic is an urgent task. Pyrolysis of plastic waste followed by the hydrosaturation of liquid products may become a promising method for obtaining components of motor gasoline. The aim of this study is to obtain motor gasoline components from plastic waste through pyrolysis, followed by hydrogenation of the fuel fractions for their use in the production of commercial fuels. The scientific novelty of this study consists of establishing the influence of hydrosaturation process parameters on an Al-Co-Mo hydrotreating catalyst (temperature and feedstock flow rate) on the transformation of hydrocarbons present in the gasoline fraction separated from the liquid pyrolysis products of polypropylene waste. The most preferred conditions for obtaining feedstock for subsequent hydrosaturation of polypropylene waste turned out to be the pyrolysis process carried out at a temperature of 450 °C and atmospheric pressure. Based on calculations in the Compounding software, promising blending components were identified. Based on the obtained results, two samples were identified as having the greatest potential for blending commercial gasolines in terms of hydrocarbon composition and performance characteristics. The sample obtained at the hydrosaturation process parameters of 350 °C and a feedstock flow rate of 0.51 mL/min is the most preferable in terms of its composition, since it demonstrates a minimal content of olefins (18.7% vol.) and benzene (0.87% vol.) but has a relatively low octane number (RON 58.7). The sample obtained at the hydrosaturation process parameters of 300 °C and a feedstock flow rate of 0.85 mL/min has relatively higher octane characteristics (RON 72.9) and can be used as a high-octane component but requires blending with components that compensate for the increased olefin content. Also, it is shown in this work that hydrosaturation of the gasoline fraction separated from the liquid pyrolysis products of polypropylene waste enables the production of motor gasoline components whose blending rate in commercial gasolines recipes can reach up to 35% by volume. Full article

A vortex reducer is employed to reduce the pressure drop during the radially inward air bleeding process in aero-engines. The vortex reducer with deswirl nozzles (DVR) has the advantage of structural robustness; however, its complex, non-monotonic flow rate–pressure drop characteristic limits its widespread application. In an effort to resolve this issue, the current study employs both experimental and numerical methodologies to investigate the effects of nozzle geometric parameters on the flow characteristics of the DVRs, which are currently deficient. The findings indicate that, irrespective of variations in nozzle radial position or flow area, an elevation in the design point flow rate invariably results in an augmented pressure drop, and this coupling effect cannot be circumvented by modifying the geometric parameters. When the nozzle radial position is lowered to below b₁ = 130 mm or the flow area is reduced to below d₂ = 1.19 mm, the flow characteristic of the DVRs becomes monotonic; nevertheless, due to the severely limited flow capacity, such a monotonic characteristic lacks practical engineering significance. Therefore, both the nozzle radial position and the flow area should be regarded as separate independent variables in optimization calculations during the design process, necessitating the development of a rapid and accurate low-dimensional model. Full article

Background: The C-reactive protein/albumin ratio (CAR) has increasingly attracted attention as a reliable predictive marker in patients with acute myocardial infarction (AMI). Purpose: This study aimed to evaluate the predictive value of the CAR for no-reflow development. Methods: A total of 201 patients with STEMI who underwent PCI were included in the study. Admission laboratory tests included CRP, albumin, CK, CK-MB, troponin T, and other biochemical parameters. The CAR was calculated as CRP divided by albumin ×100, while the CUAR was calculated as the base-10 logarithm of CRP × UA divided by albumin. Patients were then divided into two groups based on CAR levels. Results: A total of 201 STEMI patients were included: 106 (52.7%) in the low-CAR group (≤48.4) and 95 (47.3%) in the high-CAR group (>48.4). Significant differences between groups were observed for smoking, albumin, cholesterol, CRP, CUAR, and TIMI flow grade ≤ 2. Logistic regression analysis identified albumin, cholesterol, CRP, BUN, uric acid, CK-MB, CAR, and CUAR as significant predictors of TIMI flow grade. A receiver operating characteristic (ROC) curve of CRP, albumin, CAR, and CUAR was used to plot the true positive rate against the false positive rate across various cut-off points; the area under the curve (AUC) was 0.87 (95% CI, 0.81–0.94, p < 0.0001) for CRP, 0.73 (95% CI, 0.65–0.81, p < 0.0001) for albumin, 0.9 (95% CI, 0.84–0.95, p < 0.0001) for the CAR, and 0.94 (95%, 0.89–0.99, p < 0.0001) for the CUAR. The cut-off values were 2.11 for the CUAR, 48.4 for the CAR, 18 for CRP, and 38 for albumin. Conclusions: The ratio of C-reactive protein to albumin (CAR) may serve as a reliable and clinically accessible marker associated with the no-reflow phenomenon in STEMI patients undergoing PCI. A defined CAR cut-off has been proposed to help stratify patients at increased risk of no-reflow. Full article

With the large-scale development of renewable energy such as wind, solar and ocean energy, the demand for energy storage is more urgent. Pumped hydro energy storage (PHES) is one of the fundamental solutions to the problem of intermittent supply of renewable energy. The large-capacity/low-head pumped hydro energy storage (LL-PHES) system with the use of tubular pump turbine is a beneficial extension of traditional PHES systems owing to large flow rate and cheaper civil structures. However, the continuous competition between the “static water pressure difference caused by gravity” and the “pressure increase caused by accelerated impeller rotation” leads to prominent instability in the start-up process of the LL-PHES system under pump conditions. An explicit coupling algorithm is proposed for analyzing the transient characteristics in the start-up process of the LL-PHES system under pump conditions. This algorithm is based on the idea of dimensional transformation, and performs 3D flow calculations and 2D rigid body dynamics equation solution in the pump domain and the flap gate domain, respectively. This algorithm avoids the problems of high computational cost and poor convergence that exist in existing fully three-dimensional coupling algorithms and ensures the efficiency of transient hydraulic characteristic calculation. A comprehensive analysis of the transient characteristics of the LL-PHES system during pump start-up process is conducted using the proposed new algorithm. The entire process of the increase in rotational speed, valve opening, flow rate, and the continuous evolution of blade surface pressure during the start-up process is quantitatively described. The amplitude and spectral characteristics of the alternating pressure on multiple blades are clarified. The evolution law of blade load during the stage of severe pressure fluctuations during the start-up process is explained. The load distribution characteristics of “high in the leading and trailing edge areas and low in the middle” in the blade stream direction is presented. The research results have a direct guiding role in improving the hydraulic design and enhancing the operational stability of LL-PHES systems. Full article

This study presents the revision of the Rabaçal River Recreational Fishing Area Management Plan (ZPL), implemented in 2020, aiming to evaluate its effectiveness and identify the need for adjustments after five years. The study area includes part of Montesinho Natural Park, covering water bodies upstream of the Vale de Armeiro Reservoir (RH3—Douro Basin), excluding the Assureira River sub-basin. The methodology followed the initial study design, with electrofishing conducted at ten stations (30 surveys). Hydromorphological and riparian conditions were assessed using the River Habitat Survey (RHS), enabling the calculation of the Riparian Quality Index (RQI), Habitat Modification Score (HMS), and Habitat Quality Assessemt (HQA). Results indicate high habitat diversity and overall good-to-excellent hydromorphological quality, although they are locally affected by human pressures and global change. Brown trout (Salmo trutta) was recorded at all sites, showing wide spatial distribution. Population structure was dominated by young individuals (≤2 years; 70%), indicating high recruitment rates. However, growth patterns and reduced body condition suggest that habitat features, particularly flow regime and riparian quality, are influencing population dynamics, highlighting the need to explicitly integrate habitat–population relationships into management measures. A notable expansion of the invasive signal crayfish (Pacifastacus leniusculus) was also observed (now present at stations T₃, T₄, and T₅), reinforcing the need for targeted monitoring and control actions. Overall, the results support the continuation of the current management model, aligned with the conservation objectives defined in the initial plan and in project POSEUR-03-2215-FC-000096, while emphasizing the importance of habitat conservation to ensure the long-term sustainability of trout populations and aquatic ecosystems. Full article

Aiming at the characteristics of high viscosity and poor fluidity of high waxy ordinary heavy oil, a Janus silica-based nanosheet composite viscosity reducer was designed and prepared in this paper. The viscosity reducer was assembled by asymmetric Gemini viscosity reducer and silica nanosheets through dehydration condensation reaction, and its structure was verified by FT-IR, ¹HNMR, XPS and DLS. The viscosity reduction performance, emulsion stability, interfacial tension and flow performance of the viscosity reducer were systematically evaluated by taking heavy oil with wax content of 35.7% and viscosity of 237 mPa·s at 30 °C as the research object. The results showed that, at an oil-to-viscosity-reducer-solution volume ratio of 3:7 and a viscosity reducer mass fraction of 0.3%, the maximum viscosity reduction rate reached 94.5% at 30 °C, calculated relative to the viscosity of the dehydrated original heavy oil. The oil–water interfacial tension was significantly reduced, and the 24 h bleeding ratio, defined as the volume percentage of separated water relative to the initial aqueous phase volume, was only 7.3%, indicating good emulsion stability. The core flow experiment shows that the resistance coefficient is reduced to the lowest at 0.3% concentration, and the seepage capacity is significantly improved. The analysis of total hydrocarbon gas chromatography showed that the content of high-carbon wax components in the C₂₃-C₃₀ range decreased by 4.79 percentage points after treatment, indicating that the viscosity reducer preferentially interacted with high-carbon wax molecules and promoted wax-crystal dispersion, thereby weakening the three-dimensional wax-crystal network. The viscosity reducer has the synergistic effect of dispersing wax crystals, reducing interfacial tension and stabilizing emulsification, which provides a low-cost and high-performance technical approach for the efficient exploitation of high waxy ordinary heavy oil. Full article

With the global advancement of carbon peaking and carbon neutrality goals, the importance of carbon capture, utilization, and storage (CCUS) technologies has become increasingly prominent. As a critical component of CCUS systems, gaseous CO₂ pipeline transportation has emerged as a research hotspot due to its efficiency and cost effectiveness. However, there are invariably corrosion problems when it comes to gaseous CO₂ pipeline transportation. These issues pose a significant threat to both the safety and economic viability of pipeline operations. Therefore, it is of importance to investigate gaseous CO₂ corrosion during pipeline transportation. In this work, based on recent domestic and international research achievements, research progress in the field of gaseous CO₂ corrosion during pipeline transportation is systematically reviewed. First, the corrosion mechanisms and corrosion characteristics during gaseous CO₂ pipeline transportation are studied, and the synergistic mechanisms by which key parameters such as impurities, temperature, pressure, flow velocity, and water content jointly influence pipeline wall corrosion behavior are elucidated. Then, corrosion products in CO₂ transportation pipelines are analyzed, and protective measures applicable to gaseous CO₂ pipeline systems are synthesized. Finally, future research goals are proposed to promote research on gaseous CO₂ corrosion during pipeline transportation: the impact of interactions among multiple impurities on corrosion behavior should be clarified; the inhibitory effects of the dynamic evolution of product films on mass transfer processes should be considered in corrosion rate calculation models; and more economical and efficient anti-corrosion technologies should be developed to meet diverse operational requirements. This work can provide guidance for the corrosion protection of gaseous CO₂ pipeline transportation. Full article

Intermittent tilting pouring is widely utilized in metal casting due to its operational simplicity and cost-effectiveness. However, this method faces challenges such as difficult manual tuning and inconsistency in achieving constant flow rates. Targeting pouring equipment at a high-purity metal smelting company, this study proposes a closed-surface flux calculation method based on the Gauss divergence theorem to determine molten metal volume at any given instant. A mathematical model for pouring processes involving ladles with non-cylindrical inner surfaces is established. Based on this model, pouring characteristics are analyzed. Through piecewise fitting, angular velocity functions for constant flow rate pouring are derived, which provides theoretical guidance for practical industrial operations. Full article

Background/Objectives: Short-term functional outcomes after outpatient pulmonary rehabilitation are heterogeneous. We examined whether a study-derived cardio-nutrition-inflammation-oxygen (CNIO) index integrating echocardiographic filling pressure, nutritional status, inflammation, and oxygen requirement was associated with 3-month functional outcomes in chronic respiratory disease. Methods: This single-center retrospective cohort study included 60 adults with chronic obstructive pulmonary disease, interstitial lung disease, or bronchiectasis who completed outpatient pulmonary rehabilitation and had baseline and 3-month functional assessments. The CNIO index was calculated as standardized E/e′ plus standardized ln(neutrophil-to-lymphocyte ratio) plus standardized resting oxygen flow rate minus standardized Geriatric Nutritional Risk Index, and the summed score was then standardized to mean 0 and SD 1. The primary outcome was 3-month 6 min walk test (6MWT) distance, and the exploratory secondary outcome was 3-month Short Physical Performance Battery (SPPB) score. The primary 6MWT analysis used multivariable analysis of covariance adjusted for baseline 6MWT, age, sex, body mass index, and diagnosis, whereas the exploratory SPPB analysis used ordinal logistic regression adjusted for baseline SPPB and the same covariates. Results: Mean 6MWT increased from 340.3 ± 61.0 m to 368.0 ± 102.0 m, corresponding to a mean change of 27.7 ± 90.3 m. Each 1-SD increase in CNIO was associated with a lower 3-month 6MWT distance (β = −43.42 m; 95% confidence interval [CI], −77.55 to −9.30; p = 0.014). In the exploratory ordinal logistic regression model for SPPB, each 1-SD increase in CNIO was associated with lower odds of being in a higher 3-month SPPB category, although the estimate was fragile and the confidence interval was close to the null (odds ratio = 0.39; 95% CI, 0.15 to 0.99; p = 0.048). Bootstrap internal stability analysis for the primary 6MWT model showed a wide percentile bootstrap 95% CI of −76.05 to −13.97 m per 1-SD increase in CNIO, supporting the need for cautious interpretation. Conclusions: In this hypothesis-generating derivation study, a higher standardized CNIO index was associated with lower 3-month 6MWT distance among adults with chronic respiratory disease who completed outpatient pulmonary rehabilitation. The association with SPPB was weaker and should be interpreted cautiously. These findings are not generalizable to patients who discontinue rehabilitation or are hospitalized for exacerbation during follow-up, and prospective external validation in larger, diagnostically stratified cohorts is required before CNIO can be considered for clinical risk stratification or rehabilitation planning. Full article

Background/Objectives: Acceleration of orthodontic tooth movement remains a major challenge in clinical orthodontics. Evidence suggests that increased local blood flow around the alveolar bone is key to bone remodeling and potentially reflects early biological responses associated with accelerated orthodontics. This study aimed to investigate the effects of non-invasive physical stimuli on gingival microcirculation. Methods: Eight healthy adult male volunteers were included in the analysis. Gingival blood flow was assessed using laser Doppler flowmetry under the following conditions: no-stimulation condition (None) and four types of stimuli: thermal stimulation (THM), electric field stimulation (ELF), vibration stimulation (VIB), and far-infrared stimulation (FIR). Gingival blood flow was recorded before and after each stimulation, and the rate of change was calculated. Statistical analysis was performed using a linear mixed-effects model with Type III ANOVA (Satterthwaite approximation), followed by Dunnett-adjusted comparisons. Results: A statistically significant difference was observed between stimulation conditions (p = 0.0087). VIB significantly increased gingival blood flow compared with the no-stimulation condition (p = 0.0041), whereas ELF showed a trend toward increased blood flow (p = 0.0936); THM and FIR showed no statistically significant effects. Conclusions: The findings of this study suggest that non-invasive physical stimuli, particularly vibration stimulation, can enhance gingival microcirculation. Although tooth movement was not directly evaluated, the observed hemodynamic changes may represent short-term physiological responses to non-invasive physical stimulation. Full article

Airflow is widely used in grain cleaning and sorting processes to separate grains according to their aerodynamic properties. However, separation efficiency depends on airflow parameters and grain physical characteristics. The aim of this study was to evaluate the movement and sorting of wheat grains under different airflow conditions and to compare the effects of vertical and horizontal airflows on grain separation efficiency. A theoretical analysis was conducted to investigate grain motion in laminar and turbulent airflows by determining grain displacement and displacement differences. Theoretical calculations were used to predict the displacement behavior and separation potential of grains with different critical velocities under various airflow conditions. To evaluate these predictions, laboratory experiments were conducted in a horizontal airflow sorting chamber at grain feed rates of 1 and 2 kg min⁻¹. The experimentally observed grain distributions were then compared with the theoretical predictions, allowing comparison between predicted and experimentally observed grain movement patterns. The average critical velocity of wheat grains was found to be 10.35 m s⁻¹ at 14.2% moisture content, while the floating coefficient was approximately 0.092. The theoretical analysis showed that displacement differences between grains with different aerodynamic properties ranged from 0.103 to 0.185 m within 1 s, depending on airflow conditions. Experimental results revealed a non-uniform distribution of grains within the sorting chamber, with the majority of grains collected in the first boxes. Increasing the grain feed rate reduced separation efficiency to approximately 55%, indicating a significant influence of grain flow intensity on the separation process. The results demonstrate that efficient grain sorting requires the optimization of both airflow parameters and grain feeding conditions. The findings of this study may contribute to the design and improvement of grain cleaning and sorting equipment. Full article

Cells operate as open thermodynamic systems where energy transformations and transport processes occur across membranes, exhibiting distinct thermo-electro-biochemical behaviours in healthy versus diseased states. Living organisms generate waste heat due to internal irreversibility, which dissipates into the environment and serves as an observable flow of information. By analysing this heat loss and its changes under external influences, new insights into cellular behaviour can be gained. This paper highlights recent advances in this thermodynamic approach, which frames living systems as black boxes, focusing on their input–output dynamics and introducing the emerging field of bioengineering thermodynamics. A key challenge in applying extremely low-frequency electromagnetic fields (ELF-EMF) to proliferative disorders has been the empirical selection of effective field parameters. To address this, we employed a bio-thermodynamic engineering model to calculate the ELF frequency that maximizes mean entropy changes based on cellular biophysical parameters. This entropy change corresponds to a metabolic shift that reduces cell proliferation. Experimental validation was performed on six human cancer cell lines, where proliferation rates served as indicators confirming the model’s predictions. For the first time, this approach enabled the calculation and experimental validation of ELF frequencies selectively effective on different cell types, demonstrating a promising method for targeted therapeutic applications. Full article

Offshore high-water-rate gas wells can often sustain stable production for a considerable period after liquid first appears at the wellhead. Unlike conventional onshore gas wells with relatively low liquid production, these wells can remain in stable production during the middle and late production stages even when the gas velocity in the wellbore has fallen far below the critical value predicted by conventional liquid-carrying criteria. Under such conditions, the wellbore flow pattern commonly shifts from annular mist flow to churn flow and slug flow, and liquid transport becomes governed by a dynamic balance jointly controlled by pressure differential and gas entrainment. As a result, conventional critical liquid-carrying theory alone is no longer sufficient for accurate production state identification. To address this issue, this study proposes a production state identification method for offshore high-water-rate gas wells based on dynamic pressure profile calibration and nodal analysis. In this method, the wellbore pressure profile serves as the key link between outflow capacity and production state evaluation. Measured data from flowing pressure tests are used to calibrate the pressure profile within the selected multiphase flow correlation by introducing two calibration coefficients, namely the liquid holdup calibration coefficient and the two-phase friction calibration coefficient. Gaussian process regression is then applied to model the temporal evolution of the calibration coefficients, generate their fitted trajectories, and predict their values at the next time step. By using the predicted calibration coefficients to recalibrate the pressure profile, dynamic calibration of the wellbore pressure profile is achieved. Field applications to four offshore high-water-rate gas wells show that the calibrated pressure profiles are in closer agreement with the measured pressure points. The accuracy of production-state identification is also significantly improved, and the gas production rates calculated from calibrated nodal analysis are closer to the values reported in daily production records than those obtained before calibration. These results demonstrate that the proposed method effectively improves both wellbore pressure profile prediction and production-state identification for offshore high-water-rate gas wells. The study provides a practical method for production state evaluation and production management of offshore high-water-rate gas wells during the middle and late stages of field development. Full article

This study aims to demonstrate the feasibility of controlling particle size through a mathematical model in the design of industrially applicable ultrasonic spray nozzles by utilizing the vibrational characteristics of piezoelectric ceramics. A piezoelectric ceramic composition with a low sintering temperature and excellent thermal stability (Curie temperature above 300 °C) was developed and used as a ceramic vibrator. Furthermore, the resonance frequency and nozzle displacement were calculated using the COMSOL program and applied to a mathematical model to design an ultrasonic nozzle capable of producing a spray particle diameter of approximately 30 μm. The designed ultrasonic nozzle was fabricated, and its spray characteristics were analyzed. The consistency of the spray characteristics was examined by comparing them with the mathematical model based on changes in ultrasonic nozzle length, resonance frequency, and fluid viscosity. When the ultrasonic nozzle horn length was 22 mm, the resonance frequency was found to be 42.1 kHz, and at a flow rate of 65 mL/min. the average spray particle size was approximately 30–40 μm, indicating fine and uniform particles. In addition, it can be seen that as the length of the nozzle horn increases, the resonance frequency decreases, reducing the supply energy delivered to the liquid, and the particle size increases as shown in the mathematical analysis. The theoretical separation energy required to atomize pure water at a flow rate of 65 mL/min. is 2100 J, which was found to be greater than all energy loss occurring during the atomization process. However, it can be seen that as the length of the ultrasonic nozzle increases, the maximum atomization volume increases, and as viscosity increases, the energy required to separate a single atomized particle becomes greater. Full article

Multiphase flow involving fluids and particles is inherently complex due to the coupled effects of viscosity, capillary forces, and particle-scale friction. The fluids exhibit viscous behavior, which manifests as instabilities at the interface; changes in fluid viscosity also significantly affect the interface. In this study, we injected aqueous solutions of varying viscosities into a layer of dry, hydrophobic particles. As the viscous and frictional forces changed, we observed alterations in the number and width of the finger-like invasion patterns. When the pressure gradient exceeds a critical threshold, the finger-like structures expand radially outward. The fractal dimension of the invasion patterns was calculated using the standard box-counting method applied to binarized invasion masks, allowing the space-filling degree and morphological transition of the patterns to be quantified under different particle layer filling ratios, injection rates, particle sizes, and liquid viscosities. Full article