Search Results (8,361)

Osteocytes translate fluid shear stress into biochemical signals critical for bone homeostasis. Here, we combined 3-dimensional (3D) osteocyte culture, microgravity simulation, fluid shear mimicking reloading after disuse, and real-time calcium signaling analysis to elucidate responses of osteocytes under different mechanical environments. Ocy454 cells were seeded onto 3D scaffolds and cultured under static (control) or simulated microgravity (disuse) conditions using a rotating wall vessel bioreactor. Elevated expression levels of Sost, Tnfsf11 (Rankl), and Dkk1 were detected following disuse, confirming efficacy of the microgravity model. Cell membrane integrity under mechanical challenge was evaluated by subjecting scaffold cultures to fluid shear in medium containing FITC-conjugated dextran (10 kDa). The proportion of dextran-retaining cells, indicative of transient membrane disruption and subsequent repair, was higher in microgravity-exposed osteocytes than controls, suggesting increased susceptibility to membrane damage upon reloading following disuse. Intracellular calcium signaling was assessed under a high but physiological fluid shear stress (30 dynes/cm²). Scaffolds cultured under disuse conditions demonstrated a larger sub-population of osteocytes with high calcium signaling intensity (F/Fo > 10 fold) during fluid shear. The maximum fold change in calcium signaling intensity over baseline and the duration of the peak calcium wave were greater for osteocytes cultured under disuse as compared to static controls, however the bioreactor-cultured osteocytes showed, on average, fewer calcium waves than those cultured under control conditions. Subsequent experiments demonstrated that the sub-population of osteocytes with high calcium signaling intensity following exposure to disuse were those that had experienced a transient membrane disruption event during reloading. Together, these results suggest that simulated microgravity enhances osteocyte susceptibility to formation of transient membrane damage and alters intracellular calcium signaling responses upon reloading. This integrated approach establishes a novel platform for mechanistic studies of osteocyte biology and could inform therapeutic strategies targeting skeletal disorders related to altered mechanical loading. Full article

In the present work, the turbulent wake of a circular cylinder in a confined flow environment at a blockage ratio of 14% is experimentally investigated in a wind tunnel consisting of a parallel test section followed by a constant-area distorting duct, under subcritical Re inlet conditions. The initial stage of wake development, extending from the bluff body to the end of the parallel section, is analyzed, with the use of hot-wire anemometry and laser-sheet visualization. The near field reveals partial similarity to unbounded wakes, with the principal difference being a modification of the Kármán vortex street topology, attributed to altered vortex dynamics under confinement. Further downstream, the mean and fluctuating velocity distributions of the confined wake gradually evolve toward channel-flow characteristics. To elucidate this transition, wake measurements are systematically compared with channel flow data obtained in the same configuration under identical inlet conditions and with reference channel-flow datasets from the literature. Experimental results show that a vortex-transportation mechanism exists due to confinement effect, resulting in the progressive crossing and realignment of counter-rotating vortices toward the tunnel centerline. Although wake flow characteristics are preserved, suppression of classical periodic shedding is clearly depicted. Furthermore, it is shown that the confined near-wake spectral peak persists up to x₁/d~60 as in the free case and then vanishes as the spectra broadens. Coincidentally, the confined wake exhibits a narrower halfwidth than its free wake counterpart, while a centerline shift of the shed vortices is observed. Farfield wake-flow maintains strong anisotropy, while a weaker downstream growth of the streamwise integral scale is observed when compared to channel flow. Together, these findings explain how confinement reforms the nearfield topology and reorganizes momentum transport as the flow evolves to channel-like flow. Full article

This study investigates jet plume deflection in underexpanded supersonic rectangular nozzles with aft-decks. To determine the underlying mechanism, 117 two-dimensional, Reynolds-averaged Navier–Stokes simulations were performed across a nozzle pressure ratio (NPR) range of $1.9\le \mathrm{NPR}\le 5.0$ and aft-deck length ($L_{\mathrm{aft}}/D_h$) range of $1.36\le L_{\mathrm{aft}}/D_h\le 3.37$. For each simulation, the first shock reflection $S_1$, the wall-pressure field, the vertical force $F_y$, and the presence of any separation bubble were recorded to characterize the relationships among $\mathrm{NPR}$, $L_{\mathrm{aft}}$, and $\theta$. Accordingly, a cause-and-effect path was delineated as $(\mathrm{NPR},L_{\mathrm{aft}})\to S_1\to F_y\to \theta$. A weighted regression captured 96% of the variance in the deflection angle and revealed that shifts in shock position set the wall-pressure imbalance. The imbalance fixes the vertical force and the force ultimately rotates the jet plume. Downward deflection arises when the shock reflects near the deck edge, whereas upstream reflection initiates a shock–boundary-layer interaction that forms a separation bubble and drives the jet plume upward. Between these extremes, a narrow operating band allows either outcome, explaining the divergent trends reported in prior work. The quantitative model assumes steady, two-dimensional flow and the regression prioritises illuminating the underlying physics over exact prediction of $\theta$. Nevertheless, under these assumptions, the analysis establishes a physics-based framework that reconciles earlier observations and offers a basis for understanding how nozzle pressure ratio and aft-deck length govern jet plume deflection. Full article

This study employed Computational Fluid Dynamics (CFD) simulations using FLOW-3D v11.2 software to systematically investigate the hydraulic characteristics of Asymmetric Triangular Labyrinth Weirs (ATLWs), with a comparative analysis against conventional Symmetric Triangular Labyrinth Weirs (STLWs). The Volume of Fluid (VOF) method and the Renormalization Group (RNG) k-ε turbulence model were adopted to accurately capture the free-surface and turbulence behaviors. The results demonstrate that ATLWs induce significant flow deflection, leading to the formation of distinctive local cavities and a unique flow regime characterized by the coexistence of fully aerated nappe flow and local submergence. Compared to STLWs, this asymmetric configuration generates more complex three-dimensional flow structures and altered pressure distribution patterns. Under low headwater conditions, the hydraulic performance (C_d and Q/Q_n) of both weir types is similar; however, under high headwater conditions, the C_d of STLWs is approximately 5.4–14.3% higher than that of ATLWs. A noteworthy finding is that increasing the cycle number (n) significantly enhances the discharge capacity of ATLWs, whereas this effect is not pronounced in STLWs. Based on comprehensive parametric analysis, this study developed a generalized empirical formula with exceptionally high predictive accuracy for estimating C_d, providing a practical tool for optimizing ATLW designs in engineering applications. Full article

Background/Objectives: The aim of this study was to investigate the cytotoxic, genotoxic, apoptotic, and anti-inflammatory effects of the antiseptic agent octenidine dihydrochloride (OCT-D) on the RPMI-2650 cell line derived from human nasal mucosa in vitro. Methods: RPMI-2650 cells and Human Umbilical Cord Endothelial Cells (HUVECs) were treated with various concentrations of OCT-D (0.00625–0.4%) for 12 and 24 h. Cell viability was assessed using the WST-1 assay, while DNA damage was assessed using the comet and micronucleus (MN) assays. Apoptotic activity was determined using Annexin V flow cytometry and fluorescence microscopy. Intracellular reactive oxygen species (ROS) levels were measured, and inflammatory cytokines (IL-1β, IL-6, TNF-α, and IFN-γ) were measured by Enzyme-Linked Immunosorbent Assay (ELISA). The mRNA expression of genes associated with apoptosis, oxidative stress, and inflammation was analyzed using RT-PCR. Results: OCT-D caused dose- and time-dependent cytotoxicity, and RPMI-2650 cells showed greater resistance compared to HUVECs. While a strong apoptotic response was observed in HUVECs, RPMI-2650 cells exhibited limited apoptosis. OCT-D was found to cause dose-dependent DNA damage and an increase in MN in both cell lines. OCT-D significantly reduced cytokine levels and ROS production in both cell types. RT-PCR results supported its anti-inflammatory and antioxidant effects at the molecular level. Conclusions: In conclusion, this study demonstrated that OCT-D exhibited minimal cytotoxic and apoptotic effects in RPMI-2650 cells, but affected vascular structure by inducing apoptosis in endothelial cells. These findings provide important evidence that OCT-D can be used as a potential adjunctive agent in nasal treatments, and these data need to be supported by preclinical and clinical studies. Full article

Rainfall retention and runoff detention are the key hydrological processes that reduce runoff from green roofs. This study aims to quantify and model the hydrological response of nine combinations of growing substrates and drainage layers for extensive green roofs. Retention and detention capacities were evaluated using laboratory column experiments under two extreme initial moisture conditions—air-dried (D) and field capacity (W)—and three rainfall intensities (30, 60, and 100 mm h⁻¹). Regardless of the substrate–drainage combination, retention capacity, W_R, was significantly higher under dry conditions than under wet ones. Under wet conditions and rainfall intensity of 30 mm h⁻¹ (30 W tests), the mean W_R value (5.2 mm) was significantly lower than those recorded at higher intensities (14.3 and 14.2 mm, for 60 W and 100 W tests, respectively). Detention capacity, W_D, was less influenced by initial moisture and rainfall intensity, with mean values ranging from 7.4 to 10.9 mm. The distinct hydrological responses of green roof columns in the two antecedent moisture conditions were attributed to contrasting infiltration mechanisms: capillary flow dominated under dry conditions, while gravity-driven preferential flow prevailed under wet conditions. The application of a simple reservoir-routing model revealed that the AgriTerram (AT)—expanded perlite (EP) combination achieved the greatest reduction in total outflow volume and peak runoff. Under wet initial conditions, no single configuration clearly outperformed the others. This study highlights how the combined use of simulated rainfall experiments and a reservoir-routing model enables the identification of the most effective combination of substrate and drainage system to improve the hydrological performance of green roofs. Full article

This study investigates the durability challenges of 3D-printed concrete (3DPC) and examines the effect of silica fume (SF) on its performance, focusing on mechanical properties and selected durability tests as key indicators of mix suitability for 3D printing applications. Five low-carbon mixes were prepared with 50% GGBS replacement and varying silica fume contents (2.5–10%), and were evaluated through slump, compressive strength, rapid chloride migration, and accelerated carbonation tests. The addition of GGBS reduced the concrete’s shape retention, but incorporating silica fume improved flow behaviour, resulting in a more stable mix. The inclusion of GGBS and silica fume initially reduced 1-day strength but led to significant gains by 28 days, with the 5% SF low-carbon mix achieving the highest compressive strength. The low-carbon mixes showed superior chloride resistance, further enhanced by silica fume, though their carbonation resistance decreased with GGBS and SF addition. Overall, the 5% SF low-carbon mix demonstrated the best balance of strength, chloride resistance, and carbon reduction, despite minor trade-offs in early strength and carbonation resistance. Full article

Probiotic enumeration in foods and beverages remains anchored in culture dependent colony-forming unit (CFU) counts, the regulatory gold standard for label compliance. However, culturability does not fully equate to viability as environmental stresses can convert probiotic cells into a viable but non-culturable (VBNC) state, where they remain metabolically active but undetectable by CFU counts. Microencapsulation can provide a degree of protection to probiotics against stress; nevertheless, this blind spot in quantification forces manufacturers to overdose formulations or risk non-compliance with health benefits claims. Thus, the efficacy of probiotics may be underestimated when evaluation relies solely on CFU, creating a false dichotomy between VBNC and non-viable cells. Culture-independent methods, including flow cytometry quantification of active fluorescent units (AFUs), viability PCR/dPCR, and rRNA-targeted Flow-FISH, can aid closing this gap by detecting metabolically active cells non-detectable by culturing, providing complementary quantification data to CFU counts alone. Understanding the relationship between quantification by culture and culture-independent methods provides a more accurate measure of probiotic dose delivery in functional foods and beverages. This review covers the current understanding of VBNC state, including induction, detection, and resuscitation in probiotics, with emphasis on experimental controls that differentiate true VBNC resuscitation from population growth. Case studies in Lactobacillus and Bifidobacterium illustrate triggers, molecular mechanisms, and methodological advances. Finally, guidance is provided for the development of an integrated quantification approach that reconciles culture-dependent and culture-independent data, ultimately aiming to improve CFU count accuracy through the controlled resuscitation of VBNC cells. Full article

A 2D numerical model for viscous flow is established in OpenFOAM version 10 to analyze the hydrodynamic response of submarine power cables for offshore wind turbines under combined wave–current conditions. It focuses on analyzing the effect of the cable suspension ratio e/D and the current-to-wave velocity ratio U_c/U_m on the Morison coefficient of the suspended cable. The results indicate that for the cable suspension ratio e/D of less than 0.5, the strength of the dependence of both the drag coefficient C_d and inertia coefficient C_M on the cable suspension ratio e/D is significantly influenced by the current-wave-ratio U_c/U_m, while this dependence becomes less pronounced for e/D greater than 0.5. And the inertia force coefficient C_M decreases monotonically with the current-to-wave velocity ratio U_c/U_m, while the drag force coefficient C_d demonstrates a more complex, non-monotonic relationship with it. Based on the simulation results in this paper, a quantitative relationship between C_d, C_M, and the key governing parameters is established using a two-layer feedforward neural network model, providing a method for predicting wave–current forces on subsea suspended cables. Full article

Flow cytometry typically reveals two heterotrophic prokaryote (HP) subpopulations when stained with SYBR Green: high nucleic acid (HNA) and low nucleic acid (LNA) cells. Evidence suggests these populations have distinct physiological and ecological roles with implications for mortality. We assessed HP abundance, production, the relative proportion of HNA and LNA, virus-mediated mortality, and the distribution of lytic versus lysogenic strategies within HP host communities across a latitudinal gradient in the North Atlantic during spring. The study area, characterized by dynamic physicochemical conditions consistent with the onset of seasonal stratification, was divided into three regions based on bio-physicochemical properties: Pre-bloom, Bloom, and Oligotrophic. Multivariant analysis showed these regions significantly structured HPs, as well as influenced the relative abundance and production of virus subpopulations (i.e., V1 and V2). Specifically, V1 viruses increased with the potential of encountering HNA hosts, which were elevated in the surface waters of stratified Oligotrophic and Bloom regions. In contrast, V2 abundance and production correlated with LNA cells, more prominent in DEEP samples and in surface waters of the deeper mixed Pre-bloom region. Lysogeny occurred across all regions, with the percentage of lysogens within the HP community, increasing (largely V1-driven) with HP-specific growth rate until reaching a threshold of 0.1 d⁻¹, after which it declined. We discuss the potential ecological underpinnings driving these patterns and implications for carbon flux. Full article

In the booming digital economy, data circulation—particularly for massive multimodal data generated by IoT sensor networks—faces critical challenges: ambiguous ownership and broken cross-domain traceability. Traditional property rights theory, ill-suited to data’s non-rivalrous nature, leads to ownership fuzziness after multi-source fusion and traceability gaps in cross-organizational flows, hindering marketization. This study aims to establish native ownership confirmation capabilities in trusted IoT-driven data ecosystems. The approach involves a dual-factor system: the collaborative extraction of text (from sensor-generated inspection reports), numerical (from industrial sensor measurements), visual (from 3D scanning sensors), and spatio-temporal features (from GPS and IoT device logs) generates unique SHA-256 fingerprints (first factor), while RSA/ECDSA private key signatures (linked to sensor node identities) bind ownership (second factor). An intermediate state integrates these with metadata, supported by blockchain (consortium chain + IPFS) and cross-domain protocols optimized for IoT environments to ensure full-link traceability. This scheme, tailored to the characteristics of IoT sensor networks, breaks traditional ownership confirmation bottlenecks in multi-source fusion, demonstrating strong performance in ownership recognition, anti-tampering robustness, cross-domain traceability and encryption performance. It offers technical and theoretical support for standardized data components and the marketization of data elements within IoT ecosystems. Full article

The design of diffusers is a critical aspect of compressor performance, directly influencing pressure recovery, flow stability, and overall stage efficiency and operating range. This review paper provides an analysis of diffuser design principles, methodologies, and practical considerations in turbomachinery applications. The importance of diffusers in compressors is discussed, and the main types of diffusers are presented, highlighting, for each type of diffuser, their aerodynamic characteristics and operational advantages. Traditional empirical correlations and analytical models for diffuser geometry generation are reviewed, emphasizing their role in guiding preliminary design decisions. The integration of one-dimensional (1D) performance analysis methods with computational fluid dynamics (CFD) simulations is also discussed, illustrating how these approaches improve performance prediction and optimization accuracy. Design constraints are analyzed alongside performance trade-offs, highlighting the need to balance efficiency and stability. Overall, this review synthesizes existing knowledge on diffuser design in compressors, providing a structured framework for engineers and researchers to understand the key factors affecting performance and guiding the development of efficient, reliable diffuser configurations for real-world turbomachinery applications. Full article

Children remain underrepresented in environmental health studies, and evidence on how climate-related exposures affect pediatric health and school absenteeism is limited. This pilot cross-sectional study reports pediatric symptoms, school attendance, and perceptions of climate change among 300 Bangladeshi children ages 6–12 years old in three sites: Barhatta, Galachipa, and Sarankhola. Health status, climate-related perception, and educational disruption were assessed with validated questionnaires. Clinical staff measured peak expiratory flow rate, hemoglobin, and blood lead concentrations. Rash (48%), asthma (21%), and positive screening for epilepsy (17%) were most prevalent in Sarankhola. Mean hemoglobin was lower in Sarankhola (11.0 g/dL) than in the other sites. Awareness of climate change was 100% in Galachipa and Sarankhola, while 32% in Barhatta, with television and health workers being the common sources of information. Almost one in every three children missed at least three days of school in the last month with illness, climate-related emergencies, and unexpected school closures being frequent causes. These findings indicate that Bangladeshi children, especially those living in coastal areas, face the health and educational risks related to climate change, and that longitudinal and environmental monitoring studies are needed. Full article

This numerical investigation employs a two-dimensional unsteady Reynolds-averaged Navier–Stokes (URANS) approach with the k-ω SST turbulence model to systematically evaluate the impact of bleed-feed channel geometry (with three width variations: 0.2D, 0.25D, and 0.3D) on double feedback fluidic oscillator performance. The focus is on improving oscillation frequency and heat transfer while reducing pressure drop, which are critical parameters in fluidic oscillator-driven jet impingement cooling applications. Addressing these challenges is essential to enhance cooling performance, minimize energy consumption, and enable reliable thermal management in advanced engineering systems. The study analyzes key performance parameters, including oscillation frequency, pressure drop, and heat transfer characteristics, comparing channel-enhanced designs against a baseline smooth oscillator. Results demonstrate that incorporating a bleed-feed channel significantly enhances performance, with the 0.3D width emerging as optimal, delivering a 150% increase in oscillation frequency and a 3.2% reduction in pressure drop compared to the smooth design. These improvements are attributed to the channel’s ability to strengthen feedback flow, thereby accelerating jet switching while minimizing energy losses. Thermally, the 0.3D configuration achieves a 7.3% higher Nusselt number than the smooth oscillator, resulting from combined effects of higher oscillation frequency (intensifying boundary layer disruption) and increased jet momentum from reinforced feedback flow. The progressive performance enhancement across the three channel widths (0.2D to 0.3D) reveals clear geometry–performance relationships. These findings provide valuable insights for optimizing fluidic oscillator designs in applications requiring high-frequency oscillations and targeted cooling, such as electronics or gas turbine blade cooling. Full article

Low-permeability reservoirs play a crucial role in global energy supply, yet their efficient development is hindered by complex seepage mechanisms and strong nonlinear flow behavior. This study systematically investigates the characteristics of oil–water relative permeability curves and the associated non-Darcy flow phenomena in low-permeability sandstone reservoirs. Through unsteady-state water flooding experiments on native cores with permeabilities ranging from 2.99 to 34.40 mD, we analyzed the influence of permeability on relative permeability curves and categorized the water-phase curves into concave-downward and linear types. A dynamic quasi-threshold pressure gradient model was established, incorporating the corrected permeability and water saturation. Furthermore, a novel relative permeability calculation model was derived by integrating the threshold pressure gradient into the non-Darcy flow framework. Validation against the traditional Johnson–Bossler–Naumann (JBN) method demonstrated that the proposed model more accurately captures the flow behavior in low-permeability media, showing lower oil-phase permeability and higher water-phase permeability. The findings provide a reliable theoretical basis for optimizing water flooding strategies and enhancing recovery in low-permeability reservoirs. Full article