Search Results (856)

Liquid entrainment presents a significant challenge in wet flue gas desulfurization systems, leading to downstream corrosion and secondary pollution. This study systematically investigates the characteristics of liquid entrainment and pressure drop in a gas cyclone–liquid jet absorption separator (GLAS) through both experimental and simulation methods. The effects of inlet gas flow rate (Q_G), absorbent flow rate (Q_L), overflow pipe insertion depth, and the presence of a liquid-guiding cover (LGC) were evaluated. The results revealed that liquid entrainment initially increased and then decreased with rising Q_G, Q_L, and insertion depth of overflow pipe, given the competing effects of turbulent jet breakup and centrifugal separation. To mitigate liquid entrainment, a novel LGC was introduced at the overflow pipe outlet. This intervention resulted in a reduction in liquid entrainment by up to 23.9%, achieved through physical interception and inertial impaction, while maintaining the difference value of pressure drop of less than 302 Pa. The numerical simulations further analyzed the gas–liquid two-phase distributions in GLAS under various operating conditions, with results that align well with experimental observations. These findings offer valuable insights for mitigating liquid entrainment in GLAS and optimizing its industrial applications. Full article

Ammonia (NH₃) has emerged as a promising carbon-free fuel for next-generation green energy systems due to its high hydrogen density, ease of storage and transport, and compatibility with existing infrastructure. These attributes contrast with hydrogen, which presents major challenges related to storage, safety, and high-pressure handling. Thus, ammonia offers a more practical alternative for combustion-based applications. However, its low reactivity and complex vaporization behavior, particularly under flash-boiling conditions, pose challenges for accurate modeling. This study presents a comprehensive numerical investigation of liquid-ammonia spray behavior under a range of ambient pressures, encompassing both flash-boiling and non-flashing conditions. Simulations were conducted using the Lagrangian particle tracking method, coupled with various turbulence models (the renormalization group (RNG) family, k-ω family, ς − f, V2F models) to evaluate their predictive performance. Validation against experimental data for liquid and vapor penetration demonstrated that the V2F model achieved the best overall balance between accuracy and computational efficiency. Under strong flash-boiling conditions (2 bar), rapid droplet breakup and notable cooling were observed, with droplet temperatures decreasing to approximately 235 K within a few millimeters of the nozzle. In contrast, the cooling effect was more moderate under non-flashing conditions at higher ambient pressures (10–15 bar). Although the current findings were based on numerical simulations, experimental studies are ongoing to validate and refine the modeling framework further. This work provided valuable insights into the coupled effects of turbulence, phase change, and thermal transport in superheated ammonia sprays. Future research will build upon these results by extending the model to NH₃/H₂ dual-fuel systems, refining turbulence-phase interaction models, and exploring the potential application of ammonia-based flash-boiling cooling systems for electric vehicle (EV) battery thermal management. Full article

Ammonia, a zero carbon energy vector, is under consideration for decarbonising marine and energy storage applications due to its high mass-based energy density compared to many alternatives. In addition, there is widespread existing supply and transportation infrastructure due to ammonia’s use as a fertiliser. When injected in its liquid form, however, ammonia behaves quite differently to traditional fuels due to its high saturation pressure and enthalpy of vaporisation, amongst other things. This means that fundamental data on ammonia sprays need to be collected in order to understand ammonia spray behaviour and calibrate models of ammonia sprays needed for design in the virtual world. Previous work on ammonia sprays has mostly focused on spray morphology at a macroscopic level (such as liquid penetration length). However, there are fewer studies of ammonia sprays at a microscopic level. In this study, liquid ammonia was injected into a constant-volume chamber using a direct injector at two injection pressures (100 bar and 150 bar) and a range of ambient pressures from 3–13 bar. This range of ambient conditions spans regimes from flash-boiling to non-flash-boiling, thereby enabling systematic investigation of the transition between these regimes. A laser diffraction technique was used for measuring the droplet sizes of the spray at different locations (in a cylindrical volume with a diameter of 10 mm) within the spray plume at 10 kHz, and the nominal droplet sizes were quantified by the Sauter Mean Diameter (SMD). These SMD values provided, at a microscopic level, an insight of the atomisation of the spray as it left the nozzle and penetrated into an environment with different densities. It was found that the tested injector leads to a breakup dominant spray behaviour with liquid ammonia and hence the SMD values decrease as ambient pressure increases. In addition, the droplets are generally smaller at the outer edge of the spray plume compared to the inner part and both the injection pressure and injection duration have a strong effect on the droplet sizes. Full article

Background/Objectives: During cataract surgery, topical anesthesia is routinely achieved through the instillation of topical anesthetic eye drops, while different agents may be applied to the corneal surface during the procedure to support lubrication and protection. The impact of these intraoperative strategies on corneal integrity and postoperative ocular surface recovery remains an area of clinical interest. This study aimed to compare the intraoperative and postoperative effects of applying a topical anesthetic gel (Ophtesic, Horus Pharma) on the corneal surface versus the use of balanced salt solution (BSS) during cataract surgery. Methods: In this longitudinal, observational prospective study, 24 eyes of 24 patients undergoing phacoemulsification received either topical anesthetic gel (n = 15) or BSS irrigation (n = 9). Central corneal thickness (CCT) and epithelial thickness were measured preoperatively and on postoperative days 1, 5, and 15 using anterior segment optical coherence tomography (AS-OCT). Basal epithelial cell (BEC) density was assessed by in vivo confocal microscopy (IVCM), while OSDI score, non-invasive breakup time (NI-BUT), and Schirmer test I values were evaluated preoperatively and on postoperative days 5 and 15. Patient and surgeon satisfaction were rated using a Likert-like scale. Results: Both groups showed increased CCT and epithelial thickness at day 1. In the gel group, CCT returned to baseline by day 15 (p = 0.361), and epithelial thickness normalized by day 5 (p = 0.066). In the BSS group, CCT remained elevated at day 15 (p < 0.05), and epithelial thickness decreased at day 5 (p < 0.05) before returning to baseline. BEC density normalized at day 15 in the gel group (p = 0.107) but remained altered in the BSS group (p < 0.05). NI-BUT Schirmer I, and OSDI showed a trend toward faster recovery in the gel group than in the BSS group. Conclusions: In this exploratory study, intraoperative application of a topical anesthetic gel appeared to support early normalization of corneal and tear film parameters while providing effective anesthesia. Further studies are warranted to confirm these observations and evaluate potential long-term benefits. Full article

The dynamic evolution of microbubbles under ultrasonic excitation is fundamental to applications ranging from targeted drug delivery to acoustic cleaning. This study employs a synchronous high-speed microscopic imaging system to systematically investigate the size-dependent stability and fragmentation of air microbubbles (R₀ = 25–82.5 μm) in a free field at a driving frequency of 16.6 kHz. Our results demonstrate a clear mechanistic transition from stable radial oscillations to complex surface instabilities and, eventually, deterministic fragmentation. Smaller bubbles (R₀ < 55 μm) exhibit long-term stability, transitioning through higher-order surface modes (n = 3 to n = 4) as surface energy accumulates. In contrast, larger bubbles (R₀ > 60 μm) undergo violent non-spherical deformations characterized by centripetal necking and high-speed micro-jetting. Notably, we identify an inverse relationship between initial radius and fragmentation onset time, with larger bubbles reaching instability thresholds significantly earlier. Furthermore, a transition from stochastic breakup to bimodal, volume-symmetric splitting was observed as R₀ increased, where daughter bubbles reached comparable volumes. These findings provide a theoretical and empirical basis for the controlled generation of monodisperse microbubble clouds, offering significant potential for enhancing the efficacy of ultrasonic contrast agents and therapeutic cavitation. Full article

Background/Objectives: Conjunctival closure may influence early postoperative comfort and wound healing after pediatric strabismus surgery. We compared fibrin glue with absorbable sutures using anterior segment optical coherence tomography (AS-OCT)-based conjunctival thickness, serial clinical scores, ocular-surface screening, and operative time. Methods: We retrospectively reviewed 82 children (5–15 years) who underwent bilateral medial rectus recession. The conjunctiva was closed with 8-0 polyglactin 910 (Vicryl) (suture group, n = 40) or fibrin glue (fibrin group, n = 42) according to routine practice; right eyes were analyzed. Conjunctival thickness was measured by AS-OCT preoperatively and at week 6. The comfort questionnaire (CQ) score and inflammation score (IS) were recorded on postoperative day 1 and weeks 1, 2, and 6. Total operative time and closure time were obtained from surgical video recordings. Ocular Surface Disease Index-6 (OSDI-6) and non-invasive keratographic break-up time (NIKBUT) were assessed preoperatively and at week 6 in cooperative children (n = 62). Results: Conjunctival thickness increased in both groups and was slightly higher at week 6 with sutures (p < 0.001), with a slightly greater percentage increase (p = 0.001). CQ and IS were worse with sutures through week 2 (all p < 0.05) and converged by week 6 (both p > 0.05). Fibrin glue shortened total operative time (32.75 vs. 35.46 min; p < 0.05) and closure time (3.90 vs. 5.35 min; p < 0.001). In the ocular-surface subset, OSDI-6 and NIKBUT did not differ between groups at week 6. No infections or granulomas occurred; two early conjunctival wound gaps occurred in the fibrin group and one resolved with topical management, while the other met the dehiscence definition (≥2 mm) and required re-suturing, and both healed without sequelae. Conclusions: In pediatric strabismus surgery, fibrin glue demonstrated better early comfort with a modest difference in conjunctival thickness at week 6 along with slightly shorter operative time while clinical scores converged by week 6, and ocular-surface screening outcomes were similar. Full article

To reveal the evolution of the North China Craton (NCC) and the breakup process of the Columbia supercontinent, this study conducted zircon geochronology and garnet mineralogical analyses on kimberlites from the Bayan Obo area, on the northern margin of the NCC. Zircon U-Pb dating yielded four groups of concordant ages: 2505 ± 46 Ma, 2210 ± 57 Ma, 1928 ± 58 Ma, and 1455 ± 88 Ma. Among these, 1455 ± 88 Ma represents the formation age of the kimberlite, corresponding to a regional extensional tectonic setting. The other three groups are xenocrystic zircon ages, recording the formation of the Archean basement of the NCC, extensional magmatic activity in the middle Paleoproterozoic, and collisional metamorphic events in the late Paleoproterozoic, respectively. The major element characteristics of the garnets indicate they are granulite-facies crust-derived garnets (G4 type), formed under temperature and pressure conditions of 791 ± 50–876 ± 50 °C and 14 ± 3.0 kbar. This corresponds to a mantle heat flow value of approximately 60 ± 5 mW/m², suggesting an unstable state of the lithosphere in the study area. Combined with the regional geological background, the depositional age of the Bilute Formation in Bayan Obo is determined to be between 1455 and 1524 Ma. The emplacement of kimberlite is related to extensional rifting driven by the breakup of the Columbia supercontinent, and garnets hosted in kimberlite record the crustal extension and mantle magma underplating during the rift-spreading stage of this period. This study provides key petrological and chronological evidence for the tectonic evolution of the northern margin of the NCC and the breakup of the Columbia supercontinent. Full article

The presence of ice cover significantly alters the hydraulic characteristics of river channels, and the evolutionary law of ice drift velocity is crucial for understanding the ice-jam floods (IJFs) formation mechanism during the spring IJFs breakup period. Based on miniature ice buoy locators and Sentinel-2 satellite remote sensing data, this study systematically analyzes the channel characteristics of the upper Heilongjiang River and the regulatory effect of channel morphology on ice drift velocity. The results show that the river width of the upper Heilongjiang River exhibits a widening trend, with a variation range of 212 to 1292 m, characterized by large longitudinal dispersion and significant spatial variability. During the 2024 spring IJFs breakup period, the ice drift velocity ranges from 0.57 to 3.48 m/s with an average of 1.92 m/s, and a significant decreasing trend is observed when the ice drift passes through the entrances/exits of meandering bends and the confluences of distributaries in braided channels. The longitudinal distribution law of ice drift velocity revealed in this study can provide key data support and scientific reference for the accurate prediction of IJFs and the prevention and control of IJFs. Full article

Despite decades of studies on symmetric impinging-jet atomization, the combined role of controlled pre-impingement asymmetry and viscosity in setting the instability pathways and droplet statistics of laminar microjets remains insufficiently quantified. The effects of pre-impingement jet-length difference and liquid viscosity on the flow morphologies, instability dynamics, and atomization behavior of laminar impinging microjets are investigated experimentally using high-speed imaging. By systematically varying the jet-length asymmetry and viscosity over a range of Weber numbers, the evolution of liquid-sheet motion and breakup is resolved from synchronized front- and side-view observations. Specifically, the scientific objective of this work is to elucidate how pre-impingement jet-length asymmetry and liquid viscosity jointly regulate the dynamical behavior of laminar impinging microjets, with particular emphasis on regime transitions of liquid-sheet morphologies, the coupling between upper-sheet oscillations and rim instabilities revealed by synchronized multi-view imaging and POD-based frequency analysis and the resulting droplet-size statistics. These aspects address physical questions that have not been systematically resolved in classical impinging-jet studies, which predominantly focus on symmetric configurations or performance-oriented atomization. With increasing Weber number, the flow undergoes a sequence of regime transitions, including merged-jet, liquid-chain, wavy-rim, fishbone, closed-rim, open-rim, and arc-shaped atomization states. The presence and extent of the closed-rim regime depend sensitively on both jet-length asymmetry and liquid viscosity. Increasing jet-length difference accelerates transitions between these regimes, whereas increasing liquid viscosity stabilizes the liquid sheet and shifts the onset of unsteady breakup to higher Weber numbers. Proper orthogonal decomposition is applied to time-resolved image sequences to extract dominant oscillatory modes and their characteristic frequencies. Within the fishbone regime, the oscillation frequency of rim deformation either coincides with that of the upper region of the liquid sheet or appears as its subharmonic, indicating period-doubling behavior under specific combinations of Weber number and jet-length asymmetry. These frequency characteristics govern the spatiotemporal organization of ligament formation and detachment along the sheet rim. In the arc-shaped atomization regime, droplet-size distributions follow a log-normal form, and at sufficiently high Weber numbers, the mean droplet diameter shows only a weak dependence on jet-length asymmetry. These findings provide microscale-regime guidance for tunable droplet formation in open microfluidic jetting and related small-scale multiphase flows. The innovation of this study lies in the systematic use of synchronized multi-view imaging combined with POD-based frequency analysis and droplet statistics to directly connect liquid-sheet oscillations, rim instability dynamics, and breakup organization under controlled geometric asymmetry and viscosity variations. This approach enables a unified physical interpretation of regime transitions and instability mechanisms that cannot be resolved from single-view observations or morphology-based classification alone. Full article

The Southwest China vortex (SWV) is a high-impact mesoscale cyclonic vortex that typically originates over Sichuan Province, China, and frequently produces hazardous rainfall. Yet systematic knowledge of the structural and microphysical properties of SWV precipitation remains insufficiently quantified. Using Global Precipitation Measurement Dual-frequency Precipitation Radar (GPM/DPR) observations from 2014 to 2022, this study investigates the vertical structure and macro- and microphysical characteristics of SWV precipitation, and quantifies their differences across life-cycle stages and precipitation types. The mature stage is characterized by higher echo tops, stronger radar reflectivity, higher strong-echo altitudes, and larger near-surface rainfall, together with a clearer melting-layer bright band and a stronger post-melting shift toward larger drops and lower number concentrations. The developing stage is weakest and shows the largest fraction of coalescence–breakup balance signatures, whereas the dissipating stage features enhanced evaporation- and breakup-related signals. Among precipitation types, deep strong convection exhibits the greatest vertical extent with enhanced ice/mixed-phase growth; stratiform precipitation produces stronger radar echoes and higher rainfall rates than deep weak convection despite similar echo-top heights; and shallow precipitation is characterized by smaller drops, higher concentrations, and active warm-rain spectral evolution. These findings provide satellite-based constraints for microphysics parameterization evaluation and improved numerical prediction of SWV-related rainfall over complex terrain. Full article

Understanding the dynamic characteristics of droplets in the orientated flow channels of Proton Exchange Membrane Fuel Cells (PEMFCs) is crucial for their effective heat and water management and bipolar plate design. Therefore, the transient transport dynamics of liquid water within orientated gas flow channels (OGFCs) of PEMFCs are investigated, and a two-phase model based on the volume of fluid (VOF) method is established in the current study. Moreover, the impacts of the size of droplets and the geometrical parameters of baffles on the removal dynamics of liquid water are examined. The results show that baffles effectively promote droplet breakup and accelerate their detachment from the Gas Diffusion Layer (GDL) surface by increasing flow instability and local shear forces. The morphology of water is altered by the high velocity of gaseous flow, which can break up into several smaller droplets and distribute them on the surface of GDL by the gas flow. The shape of the liquid water film changes from a regular cuboid to a big droplet due to the surface tension of the liquid water droplets and the hydrophobicity of the GDL surfaces. Increasing the baffle height can reduce the time needed for the removal of droplets. With the increase in L1* from 0.25 to 0.75, the drainage time decreases slightly; however, for L1* increasing from 0.75 to 1.25, the drainage time remains almost the same. The impacts of different leeward lengths, L2*, on the water coverage ratio and pressure drop are minor. Full article

Liquid coolant jets are commonly used to remove excess heat from workpieces during grinding. There is a pressing need to reduce energy waste that contributes to environmental heat pollution and to limit the spread of oil-based coolants and mist formation. As a liquid jet issues from a nozzle and enters the surrounding air, surface instabilities develop, causing the jet to break into droplets. This breakup diminishes the jet’s ability to deliver maximum momentum to the workpiece and grinding wheel in grinding operations, thereby reducing cooling efficiency. The presence of moving ambient air near the workpiece and rotating grinding wheel further complicates cooling. First, the study investigates jet breakups in stationary air, predicting breakup lengths with reasonable agreement to experiments at varying jet velocities using the Reynolds Averaged Navier–Stokes (RANS) method equipped with Shear Stress Transport (SST) k-ω model of turbulence. The coolant jet breakup length for a jet normal to the grinding wheel is different from that for a free jet and affected by the proximity of grinding wheel to nozzle that was not evaluated in prior studies. Simulations were performed using Ansys Fluent software 2023R1, with careful tuning of numerical schemes and selection of breakup criteria. The results include analysis of jet breakup phenomena in presence of rotating grinding wheel and workpieces, determination of breakup lengths across a range of Weber numbers, and effects of nozzle design. Full article

Background/Objectives: SA001, a mofetil-ester prodrug of rebamipide, was developed to enhance gastrointestinal absorption and systemic exposure, which was confirmed in a prior Phase 1 study. Given the limited efficacy of current symptomatic therapies for primary Sjögren’s syndrome (pSS), this trial aimed to assess whether the improved bioavailability of SA001 could translate into clinical benefits. Methods: This multicenter, randomized, double-blind, placebo-controlled Phase 2a study enrolled adults who met the 2016 ACR–EULAR criteria for pSS. The participants were randomly assigned to one of four groups: SA001 at 360, 720, or 1080 mg/day (administered twice daily for 8 weeks) or placebo. Exploratory ocular assessments included tear break-up time, ocular surface staining, the Schirmer test, and the Standard Patient Evaluation of Eye Dryness. Oral endpoints included unstimulated whole salivary flow and the Xerostomia Inventory. Anti-SSA(Ro) antibodies were assessed both quantitatively and qualitatively. Safety evaluations comprised adverse events (AEs), ophthalmic examinations, laboratory tests, and vital signs. The efficacy outcomes were exploratory, and this study was not powered to formally test efficacy hypotheses. Results: Twenty-eight women (mean age 58.54 ± 9.29 years; range 41–75 years) were enrolled in this study and randomly assigned to one of the study groups. SA001 showed no statistically significant improvements versus placebo in ocular or oral endpoints, and no consistent dose–response relationship was observed. The anti-SSA(Ro) findings did not differ meaningfully across the groups. SA001 was generally well-tolerated, with infrequent, mostly mild-to-moderate AEs; however, one serious AE occurred in the placebo group. No clinically relevant ophthalmic or laboratory safety signals were detected. Conclusions: Despite the fact that markedly increased systemic exposure has been demonstrated previously, SA001 did not improve the dryness outcomes in pSS. These findings suggest that systemic exposure alone may be insufficient in established glandular disease and highlight the need for tissue-exposure-driven strategies and biomarker-informed patient selection in future studies. Predefined primary efficacy endpoints and objective, gland-proximal measures of target engagement (e.g., standardized salivary gland ultrasonography and salivary or tear fluid biomarker assessments) may help to better interpret local pharmacodynamic activity and the likelihood of a clinically meaningful benefit. Full article

Background and Objectives: This study evaluates the safety, tolerability, and efficacy of preservative-free Dorzolamide 2%-Timolol 0.5% (PF-DT), with a focus on improving the ocular microenvironment in a real-world transition setting. Materials and Methods: A prospective, multicenter, open-label study involving thirty patients with dry eye disease previously treated with BAK-DT was conducted. Participants were transitioned to PF-DT, and evaluated at weeks 4, 12, and 24. The primary endpoint was the Ocular Surface Disease Index (OSDI) score. Secondary outcomes included Break-Up Time (BUT), Schirmer test results, corneal staining, conjunctival hyperemia, intraocular pressure (IOP), and patient satisfaction. Results: Twenty-five patients completed the study. The OSDI improved from 21.5 to 12.5 (p < 0.001), with 60.0% of patients showing improvement and 52.0% achieving complete symptom resolution. Among eyes with corneal staining, 78.4% demonstrated a reduction of at least one grade, and 50.0% of those with conjunctival redness showed similar improvement. By week 24, 78.0% exhibited no corneal staining, and 50.0% had no conjunctival redness. BUT increased from 5.0 to 7.0 (p < 0.01), while IOP decreased by 1 mmHg (p < 0.01). Satisfaction regarding comfort (≥80%) and handling (≥50%) was high, with 88.0% preferring PF-DT. Conclusions: Transitioning to PF-DT improved ocular surface health while maintaining IOP control, supporting the benefits of preservative-free formulations in restoring microenvironment homeostasis and enhancing tolerability and patient satisfaction. Full article