Flow Conditions Research Articles

Impact of pyrolysis heating methods on biochars with enhanced CO2/N2 separation and their incorporation in 3D-printed composites

N-doped biochars, derived from chitosan sourced from waste crustaceous shells, were produced via microwave-assisted pyrolysis at temperatures ranging from 400 to 800 °C to enhance CO2 and N2 separation. Their performance was compared with biochars from conventional pyrolysis. Microwave-derived biochars exhibited superior CO2 adsorption capacity at 25 °C and 100 kPa (0.78 – 1.56 mmol g−1) compared to conventionally produced ones (0.55 – 1.43 mmol g−1). Increasing the pyrolysis temperature up to 600 °C significantly improved biochar properties, including surface area, pore volume, and CO2 adsorption capacity. Microwave-derived biochar featured enhanced surface area, larger pore volumes, and unique morphologies, requiring, on average, 61 % less preparation time. The higher ultramicroporosity and N-species concentration correlated with superior performance in the biochar produced at 600 °C. In gas mixture experiments (20 % CO2 and 80 % N2) under flow conditions, these biochars showed rapid adsorption/desorption rates due to enhanced macroporosity at samples produced at 600 and 800 °C, facilitating gas diffusion along the ultramicropores. Adsorption heat analysis indicated that the CO2 adsorption is predominantly driven by physisorption, supported by complete sample regeneration when applying N2 flux or increasing the temperature during desorption. The study also explores the feasibility of 3D-printing a composite using the most effective biochar and inorganic polymers sourced from waste, presenting potential benefits for industrial applications.

Heat Transfer Enhancement in a 3D-Printed Compact Heat Exchanger

The study describes experimental data on thermal tests during the condensation of HFE7100 refrigerant in a compact heat exchanger. The heat exchanger was manufactured using the additive 3D printing in metal. The material is AISI 316L steel. MPCM slurry was used as the heat exchanger coolant, and water was used as the reference medium. The refrigerant was condensed on a bundle of circular tubes made of steel with an internal/external diameter of di/de = 2/3 mm, while a mixture of water and phase change materials as the coolant flowed through the channels. Few studies consider the heat exchange in condensation using phase change materials; furthermore, there is also a lack of description of heat exchange in small-sized exchangers printed from metal. Most papers deal with computer research, including flow simulations of heat exchange. The study describes the process of heat exchange enhancement using the phase transition of coolant. Experimental data for the mPCM slurry coolant flow was compared to the data of pure water flow as a reference liquid. The tests were carried out under the following thermal and flow conditions: G = 10–450 [kg m−² s−1], q = 2000–25,000 [W m−²], and ts = 30–40 [°C]. The conducted research provided many quantities describing the heat exchange in compact heat exchangers, including heat exchanger heat power, heat exchange coefficient, and heat exchange coefficients for working media. Based on these factors, the thermal performance of the heat exchanger was described. External characteristics include the value of the thermal power and the heat exchange coefficient as a function of the mass flow density of the working medium and the average logarithmic temperature difference. The performance of the heat exchanger was presented as the dependencies of the heat exchange coefficients on the mass flux density and the heat flux density on the heat exchange surface. The thickness of the refrigerant’s condensate film was also determined. Furthermore, a model was proposed to determine the heat exchange coefficient value for the condensing HFE7100 refrigerant on the outer surface of a bundle of smooth tubes inside a compact heat exchanger. According to experimental data, the calculation results were in good agreement with each other, with a range of 25%. These data can be used to design mini condensers that are widely used in practice.

Electrooxidative C(sp3)‒H Cyanation of Sparteine and Lupanine in Undivided Batch and Continuous‐Flow Cells

Sparteine is widely used as a chiral ligand in asymmetric synthesis, but methods for providing efficient access to functionalized sparteine derivatives are still limited. Herein, we describe an electrochemical α‐cyanation of sparteine‐type bis‐quinolizidine alkaloids. This method features commercially available setups for batch and single‐pass continuous flow conditions, enabling easy gram scale synthesis of valuable racemic and enantiopure products. Moreover, insights into the selectivity of the reaction and overoxidation mechanisms are disclosed. This allows for the development of divergent oxidation pathways depending on the electrolysis conditions.

Spectroscopic determination of Deborah numbers in membrane-mimetic bolaamphiphile assemblies

The remarkable stability of Archaebacteria and their resistance to extreme environmental conditions, such as high temperature (hot springs), high salinity (salt marsh), high acidity (volcanic environment), or low temperature (Arctic or Antarctic) is mostly due to their very stable membranes. Membranes of Archaebacteria are composed of tetraethers from the lipid family of bolaamphiphiles. The concern in our laboratory is to synthesize bolaamphiphiles that could form vectors with function to carry drugs toward target cells in the body. The new family of bolamphiphiles synthesized has one polar head based on a sugar moiety and the other polar head is glycine betaine, both issued from natural sources (sugar beet, wheat). They are interconnected with a hydrocarbon chain of 12 methylène units. One side hydrocarbon chain, of 8 methylène units is attached to the anomeric position of the sugar moiety. These two molecules are named N-(12-Betainylamino-Dodecane)-octyl β-D-Glucofuranosiduronamide Chloride, abbreviated C8C12 and N-(12-Betainylamino-Dodeca-5,7-diynyl)-octyl β-D-Glucofuranosiduronamide Chloride, abbreviated C8C12X2. These bolaamphiphile molecules organize in membrane-mimetic lamellar structures (Lc, Lα, L). They undergo a thermal phase transition upon heating. When cooled back to room temperature, they remain in the undercooled high-temperature phase. To follow the relaxation back to the thermodynamically stable phase at 20 °C, the small-angle and wide-angle X-ray spectra were recorded every hour. The Deborah number (De), defined as De = time of relaxation/time of observation, is a dimensionless number often used in rheology to characterize the fluidity of materials under specific flow conditions. It was evaluated for supramolecular structures of two type of bolaamphiphiles, as the De(C8C12) = 35 and the De(C8C12X2) = 62. These values are typical for solid-like behavior, which is in accordance with the sticky, paste-like, brownish aspect of these bolaamphiphile assemblies. The time of relaxation was the time for bolaamphiphiles to regain their thermodynamically stable phase at 20 °C and the time of observation was 1 h, the typical time of recording between two subsequent spectra.

Synthesis of bicyclo[3.2.0]heptanes by organophotoredox catalytic diastereoselective anion radical [2+2] photocycloadditions of aryl‐enones under batch and flow conditions

Synthesis of bicyclo[3.2.0]heptanes by organophotoredox catalytic diastereoselective anion radical [2+2] photocycloadditions of aryl‐enones under batch and flow conditions

Investigation of the Sigma Approximation Technique for the Solution of the Time Spectral Equation System

Abstract The time spectral method is commonly utilized to analyze periodic unsteady flows within turbomachines. However, the time spectral solutions in regions with large temporal and spatial gradients, such as wakes, shocks, and boundary layers, can be plagued with unphysical oscillations, known as the Gibbs phenomenon. This paper presents an investigation into the sigma approximation technique, which is capable of significantly attenuating the Gibbs phenomenon by dampening high-frequency nonlinear components in the time spectral solutions. However, the optimal combination of the sigma factors remains to be ascertained considering the trade-off between the accuracy of solutions and the reduction of unphysical oscillations. In this study, a two-row compressor configuration is first selected, and numerical simulations are performed to evaluate the efficacy of this technique under near peak-efficiency and near-stall operating conditions. It is found that Gibbs-type unphysical oscillations can be effectively mitigated without notably compromising solution accuracy through an optimal combination of sigma factors. The NASA Stage 35 case study further verifies the effectiveness of the proposed optimal sigma factor combination in preserving the accuracy of time spectral solutions based on the data from test rig. Moreover, the von Neumann analysis reveals that the sigma approximation technique can enhance the numerical stability of the time spectral equation system, thereby allowing the use of aggressive numerical parameters to accelerate convergence. The stability analysis results are verified by a two-dimension bump under two different flow conditions and further assessed using the two-row compressor.

Sustainable Heat Generation in Flow from a Molecular Solar Thermal Energy Storage System

As the global deployment of renewable technologies accelerate, finding efficient ways to store energy will aid in responding to shifting energy demands. A prospective option not only in harvesting solar energy but also in emission‐free heating is MOlecular Solar Thermal (MOST) energy storage. A central part of MOST applications is to develop methods to release the stored energy. Herein, the Quadricyclane (QC)‐to‐Norbornadiene catalyzed back reaction is explored in a specially designed packed‐bed reactor. Four distinctly sized and purposely synthesized platinum on activated carbon catalysts are studied to trigger the heat release from the energy‐dense QC isomer. The catalysts are fully characterized using a variety of structural, surface, and spectroscopic techniques. Parameters to optimize catalytic conversion and heat release in flow conditions are explored including particle size and packing behavior, flow rates, and molecular residence times. Moreover, using CO pulse chemisorption technique, site time yield values and a turnover number are reported. Complementary to the flow reactions, computational fluid dynamic simulations applying lattice Boltzmann methods to two catalytic packed beds of different size ranges are done to evaluate fluid‐dynamic behavior within the reactor bed to ascertain the ideal particle size and packing density for catalysis in MOST applications.

Application of Seagull Optimization Algorithm-BP Neural Network in Oil-Water Two-Phase Flow Pattern Forecasting

With the ongoing increase in global energy demand, the significance of innovations in oil exploration and development technologies is rising, especially in relation to the development of unconventional reservoirs. The application of horizontal wells is becoming increasingly important in this particular situation. However, accurately monitoring and analyzing fluids in horizontal wells remains challenging due to the complex and fluctuating flow patterns of oil-water two-phase flow within the wellbore. Several elements, including well slope angle, flow rate, and water content, are involved. This study aimed to explore and develop an effective method for forecasting flow patterns, improving the precision of the dynamic monitoring of oil-water two-phase flow in horizontal wells. By analyzing the flow patterns in different experimental conditions, a predictive model using the SOA-BP neural network was developed, providing a scientific basis for dynamic monitoring in actual production scenarios. Initially, the simulated experiment for oil-water two-phase flow was carried out at room temperature and pressure utilizing a multiphase flow simulator. An optically transparent wellbore, with a diameter comparable to that of a real downhole well, was utilized, and No. 10 industrial white oil and tap water were employed as the experimental fluids. The experiment considered multiple contributing factors, including different well deviation, total flow, and water cut. The flow characteristics of oil and water were observed via visual monitoring and high-definition video, followed by detailed analysis. After collecting the experimental data, flow regimes for various scenarios were classified based on the established theory of oil-water two-phase flow in horizontal wells; then, detailed flow distribution diagrams were drawn. These data and diagrams presented offer a visual representation of the behavioral patterns exhibited by oil-water two-phase flow under varying situations and form the basis for subsequent model training and testing. Subsequently, based on the experimental data, this study combined the Seagull Optimization Algorithm (SOA) with a BP neural network to effectively learn and predict the experimental data. The SOA optimized the weights and biases of the BP neural network, improving the model’s convergence speed and prediction accuracy. Through rigorous training and testing, an oil-water two-phase flow pattern forecasting model was established, effectively predicting flow patterns under different well deviation, total flow, and water cut conditions. Finally, to validate the efficiency of the established model, a total of 15 data points were chosen from a sample well for validation. By comparing the flow patterns predicted by the model with actual logging data, the results indicate that the model’s accuracy in identifying flow pattern was 86.67%. This demonstrates that the flow pattern prediction model based on the SOA-BP neural network achieved a high level of accuracy under different complicated working conditions. This model effectively fulfills the requirements for dynamic monitoring in actual production. This indicates that the SOA-BP neural network-based flow pattern forecasting method is highly valuable due to its practical application value and provides an efficient technical approach for the development of unconventional reservoirs and the dynamic monitoring of horizontal wells in the future.

The Contrasting Effects of Bothrops lanceolatus and Bothrops atrox Venom on Procoagulant Activity and Thrombus Stability under Blood Flow Conditions.

Consumption coagulopathy and hemorrhagic syndrome are the typical features of Bothrops sp. snake envenoming. In contrast, B. lanceolatus envenoming can induce thrombotic complications. Our aim was to test whether crude B. lanceolatus and B. atrox venoms would display procoagulant activity and induce thrombus formation under flow conditions. Fibrin formation in human plasma was observed for B. lanceolatus venom at 250-1000 ng/mL concentrations, which also induced clot formation in purified human fibrinogen, indicating thrombin-like activity. The degradation of fibrinogen confirmed the fibrinogenolytic activity of B. lanceolatus venom. B. lanceolatus venom displayed consistent thrombin-like and kallikrein-like activity increases in plasma conditions. The well-known procoagulant B. atrox venom activated plasmatic coagulation factors in vitro and induced firm thrombus formation under high shear rate conditions. In contrast, B. lanceolatus venom induced the formation of fragile thrombi that could not resist shear stress. Our results suggest that crude B. lanceolatus venom displays amidolytic activity and can activate the coagulation cascade, leading to prothrombin activation. B. lanceolatus venom induces the formation of an unstable thrombus under flow conditions, which can be prevented by the specific monovalent antivenom Bothrofav®.

Dynamics of Thrombogenicity and Platelet Function and Correlation with Bleeding Risk in Patients Undergoing M-TEER Using the PASCAL System.

Transcatheter mitral valve repair is performed in a patient population at risk for thrombotic and bleeding events. The effects on platelet function and reactivity and their association with bleeding events after mitral transcatheter edge-to-edge therapy (M-TEER) have not been systematically examined. We sought to investigate the association of different parameters of platelet function and thrombogenicity with bleeding events post M-TEER. In this single-center study, 100 consecutive patients with mitral regurgitation receiving TEER were analyzed. Blood was taken directly from the guide-catheter in the left atrium before and after placing the device. Blood samples were analyzed using impedance aggregometry (Multiplate) and TEG6s. The results were compared pre- and postprocedural. The primary outcome was any bleeding complication according to the Bleeding Academic Research Consortium classification within 6 months. A total of 41 patients experienced bleeding events. TEG analysis showed a significant decrease in ADP aggregation and increase in ADP inhibition. In ROC-analysis, TEG ADP aggregation and inhibition and Multiplate ADP aggregation showed moderate predictive values for bleeding events. The delta-ADP-Test (Multiplate) showed the strongest prediction of bleeding (area under the curve: 0.69). Adding platelet function and TEG markers to a model of clinical bleeding risk factors improved the prediction for bleeding events. This study indicates that thrombogenicity might be affected immediately after M-TEER probably due to changes in flow conditions. In particular, platelet aggregation involving the ADP receptor pathway significantly correlated with postprocedural bleeding events. Whether these results could guide peri-interventional antithrombotic therapy and improve peri- and postprocedural outcome requires further investigation.

An efficient product design tool for aftertreatment system

A numerical simulation technique based on the conservation of mass and energy in the gas phase has been developed to optimize the aftertreatment system with the lowest costs. Both oxygen storage capacity model and catalyst deterioration model have been integrated into the three-way catalyst performance model. Applications have been discussed, including XY-L 1.5L I3 gasoline turbocharged direct injection (GTDI) production hybrid vehicle, BY-L 1.5L I4 GTDI hybrid vehicle, XY-L (overseas version) 1.5L I4 GTDI hybrid vehicle, and G-L7 1.5L I4 GTDI hybrid vehicle. Vehicle tests in support of the proposed model have been described. The developed model covers the complete range of the cold start, high temperature and volume flow conditions. To optimize a three-way catalyst performance, this work simulated the effect of air fuel ratio, space velocity, temperature, biasing adjustment on the catalyst efficiency. The simulations presented the technique’s capability of well predicting emissions on fresh and full useful life aged aftertreatment systems, respectively, and carried out under transient conditions. The investigation indicated that excess fueling was used upon engine start to heat the catalyst up to its full operating temperature of greater than 350°C. The model results prompted a redesign of the I3 and I4 1.5L GTDI China 6b, Euro VId and Tier 3/SULEV30 exhaust systems over the world light vehicle test procedure (WLTP) and federal test procedure (FTP) cycles, respectively, for example, the model suggested that the latest design for the SULEV30 aftertreatment system on XY-L (overseas version) 1.5L I4 GTDI hybrid vehicle with the revised calibrations in the areas of cold-start and closed-loop fuel treated emissions of NMOG, NOx, and CO to the 70% of the SULEV30 standards with a $64 cost reduction relative to the baseline.

Numerical investigation of drag reduction effects on a track bicycle fork using wings with a wavy leading edge

AbstractReynolds‐averaged Navier–Stokes (RANS) and large‐eddy simulations (LES) of the flow around wings with a wavy leading edge (WLE) are conducted in order to assess the capabilities of a passive flow control strategy for drag reduction. The intended application is indoor track cycling with controlled flow conditions. A section of a single fork rod is investigated in order to make the numerical simulations feasible. The present study reveals that net drag reduction is possible by a nonsinusoidal modification of the leading edge of the wing. However, the drag reduction effect remains limited to a few percent. While RANS and LES yield the same drag coefficient for a reference case, RANS underestimates the drag reduction effect for a longer wing and the WLE cases, but exhibits otherwise a qualitatively similar trend as the LES. With the aid of RANS, an optimal geometry is obtained defined by the wavelength‐to‐chord length ratio of and the amplitude‐to‐chord length ratio of . Corresponding LES results give an indication of the origin of drag reduction by a hampered vortex shedding. The generation of smaller and more streamwise oriented vortical flow structures at the trailing edge and behind the WLE wing is correlated with significantly reduced lift fluctuations and drag reduction.

Comparative investigation on heat transfer augmentation in a liquid cooling plate for rectangular Li-ion battery thermal management

This work conducted a numerical study with experimental validation to improve the performance of a rectangular multi-channel cooling plate utilised for cooling lithium batteries. Seven different designs on a cold plate for laminar flow conditions were evaluated using numerical modelling simulations in the 3D ANSYS program. Three cooling plate designs were proposed with channel arrangements: arc, convergent–divergent and different channel widths (narrow central channels and wide peripheral channels). The other four proposed cooling plate designs included representations of variable-sized pin fins with different shapes: oval, drop, rhombus and trapezoidal within different channel widths. Real experiments were conducted on a manufactured conventional cooling plate to verify the results of the numerical simulation. Results indicated that all proposed designs improved the heat transfer of the cooling plate. The percentage of enhancement in Nusselt number due to the presence of rhombus-shaped pin fins inside different channel widths is approximately 95.5 %, which is about three times the enhancement in pin fins that used only smooth different channel widths, which is approximately 33.5 %. Amongst the studied designs, incorporating different channel widths with the addition of rhombus-shaped pin fins exhibited the largest heat dissipation capacity and the best thermal–hydraulic performance. The highest temperature uniformity enhancement ratio and performance evaluation parameter for this case reached about 71.96 % and 1.68, respectively.

Comparative Performance Assessment between Incompressible and Compressible Solvers to Simulate a Cavitating Wake

To study the effects of fluid compressibility on the dynamics of a cavitating vortex street flow in a regime where the vortex shedding frequency increases as a result of the cavitation increase, the cavitating wake behind a wedge was simulated employing both incompressible and compressible solvers. To do this, a compressible cavitation model was implemented, modifying the Zwart-Gerber-Belamri (ZGB) incompressible solver and including a pressure limit and absorbing boundary conditions to prevent a non-physical pressure field. To validate the performance of the compressible model, preliminary simulations were carried out on a 1D Sod cavitating tube and the cavitating vortex shedding behind a circular body at laminar flow conditions. The results of the cavitating wake behind the wedge with the incompressible and the compressible solvers showed similar predictions in terms of pressure, vortex shedding frequency, and instantaneous and average vapor volume fraction profiles. In spite of this, differences were obtained in the energy content of the fluid force fluctuations on the body at higher frequencies, which appear to be better resolved and amplified when the compressibility model is considered. Overall, both solvers provided comparable results in terms of cavitation phenomena that are well aligned with experimental observations.

Phenomenological Study of the Atomization Process in Pre‐Filming Nozzles Typically Used for Steel Atomization

Liquid steel atomization using close‐coupled nozzles is highly dependent on the relationship between momentum flux ratio, gas–liquid ratio, aspiration pressure, and operating pressure of inert gases. A strong correlation between these parameters and the final powder must be assumed. Understanding these parameters, their influence on the process, and their interactions with each other is indispensable for efficient powder production. In particular, the industrial application of close‐coupled atomization nozzles, which develop a thin pre‐film on the nozzle tip, is not yet fully understood. A model experiment is presented to investigate interactions between the flow conditions of the gaseous and liquid phases, focusing on recirculation phenomena inside the atomization zone. The experiments show the influence of liquid and gas flow conditions on the spray geometry and the liquid core length, as well as the strong dependence of the liquid mass flux on the gas flow. The aspiration pressure below the liquid nozzle is sensitive to gas pressure and has a major influence on the development of the liquid core and the pre‐film, as it increases the liquid mass flux. For practical application, the results confirm an optimal operating point of interacting system parameters, which leads to high‐quality atomization with minimal use of resources.

A meshless model for three-dimensional direct numerical simulation of local scour around cylinder bridge foundation

A meshless local scour model for cylinder bridge foundation based on the smoothed particle hydrodynamics (SPH) method is proposed in this paper. Differing from the traditional Eulerian mesh model used for monopile local scour, it overcomes the high requirements of mesh quality and density for capturing large deformations at the fluid interface. Unlike the transient sediment erosion SPH model used for dam-break, sediment flushing, and water jet, the meshless approach is innovatively applied to the continuous simulation of bridge local scour under steady flow conditions. The present SPH model is established based on the SPH multi-phase fluid model, integrating a classical fluid model combined with numerical stabilization algorithms to govern water particle motion and a sediment model from Zhang et al. (2024) to govern sediment evolution, and tests a new scheme for boundary treatment in the model based on DualSPHysics. Furthermore, a novel scour visualization method that aims at extracting both visible and actual bed surfaces from discrete particles is proposed. The model is validated through comparison with rigid bed and live bed experiments, demonstrating favorable agreement in terms of flow and scour simulation. Importantly, the model results reveal a discrepancy between the elevation of the post-scour visible bed surface derived from the conventional Eulerian mesh model and experimental data, compared to the actual bed surface unaffected by water flow erosion. This indicates the necessity for incorporating a safety margin in foundation design when utilizing experimental results to determine the maximum scour depth.

Mini-cores of activated carbon block simulate full-sized performance for removing organics and arsenate from drinking water✰

Activated carbon block (ACB) filters are widely used in point-of-use (POU) drinking technology to remove tastes, odors, and organic compounds from drinking water, and when modified can even remove inorganic pollutants (e.g., arsenate, lead, copper). To introduce ACB technologies to the POU market, thorough assessment and testing are required to meet the National Sanitary Foundation 53 certification. Testing to gain this certification can be costly and time-consuming and is usually only done on the final product before commercial distribution. We developed and explored how a cylindrical “plug” cored from an ACB can be used in a mini-core apparatus with low water volumes, to mimic full-sized ACB performance. These mini-cores allow the same outside-in radial flow conditions as the full-sized ACB. After addressing potential hydraulic channeling problems, tests with chloroform or arsenate confirmed the ability of the mini-core ACB “plugs” to mimic the performance of full-sized cartridge unit. The benefit of the mini-core ACB “plug” lab-scale approach lays the foundation for testing methodologies that can evaluate a range of pollutants, water chemistries, or material modifications using a small fraction of water compared to full-sized ACB filter. Overall, the development of a mini-core ACB testing apparatus is a key advancement towards sustainable water purification, impacting environmental health, resource conservation, and global access to safe water.

Disinfectant control in drinking water networks: Integrating advection–dispersion–reaction models and byproduct constraints

Effective disinfection is essential for maintaining water quality standards in distribution networks. Chlorination, as the most used technique, ensures safe water by maintaining sufficient chlorine residuals but also leads to the formation of disinfection byproducts (DBPs). These DBPs pose health risks, highlighting the need for chlorine injection control (CIC) by booster stations to balance safety and DBPs formation. Prior studies have followed various approaches to address this research problem. However, most of these studies overlook the changing flow conditions and their influence on the evolution of the chlorine and DBPs concentrations by integrating simplified transport-reaction models into CIC. In contrast, this paper proposes a novel CIC method that: (i) integrates multi-species dynamics, (ii) allows for a more accurate representation of the reaction dynamics of chlorine, other substances, and the resulting DBPs formation, and (iii) optimizes for the regulation of chlorine concentrations subject to EPA mandates thereby mitigating network-wide DBPs formation. The novelty of this study lies in its incorporation of time-dependent controllability analysis that captures the control coverage of each booster station. The effectiveness of the proposed CIC method is demonstrated through its application and validation via numerical case studies on different water networks with varying scales, initial conditions, and parameters.

Evaluation of stress in farmed Atlantic salmon (Salmo salar) using different biological matrices

Atlantic salmon were subjected to an acute crowding scenario, and their subsequent stress responses were observed under three distinct swimming speed/water flow (WF) conditions: 0.5, 1, and 1.5 body lengths per second (BL/s). Feces, dermal mucus, and plasma were collected for analysis at 1, 6, and 24 h (h) post-stress. Additionally, the head kidney and two regions of the brain (pituitary and POA) were collected for transcript expression analysis. Fish swimming at 0.5 BL/s exhibited higher pre-stress (baseline) cortisol levels. Across all groups and matrices, the highest cortisol/cortisol metabolites (CM) levels were observed at the 1 h post-stress sampling point. At 6 h (second sampling time point), a clear decline toward baseline levels were observe in all groups. Significant increases in mean plasma glucose levels were observed at 1 h post-stress for all groups. The mean plasma lactate levels varied based on WF treatments, with a significant increase observed at 1 h only for the 1.5 BL/s group. Additionally, significant decreases in mean plasma lactate were noted at 6 and 24 h post-stress for some groups. The mRNA abundances of the tested genes (star, cyp17a1, hsd11β2, srd5a1) increased following the stress events. These changes were not uniform across all groups and were tissue dependent. In summary, the results indicate that mucus and feces can be used as potentially less invasive matrices than blood for evaluating stress and, consequently, the welfare of Atlantic salmon in captivity.

Subendometrial blood flow detected by Doppler ultrasound associates with pregnancy outcomes of frozen embryo transfer in patients with thin endometrium.

Multiple factors have been shown to influence the rate of clinical pregnancy after FET in IVF treatment, including embryo quality, synchronization of embryo and endometrium, and endometrial receptivity (ER). The subendometrial blood flow conditions could also contribute potentially major effects toward the establishment and maintenance of pregnancy. We conducted a retrospective cohort study to examine the correlation between subendometrial blood flow, as determined by Doppler ultrasound, and pregnancy outcomes in IVF patients with a thin endometrium (endometrium thickness [EMT] ≤ 0.7cm). This was a retrospective cohort study conducted at a university-affiliated reproductive hospital from January 2017 to April 2023. The EMT and subendometrial blood flows were assessed using transvaginal color Doppler ultrasound and evaluated by experienced clinical ultrasound physicians on the endometrial transformation day. The pregnancy outcomes were followed up and documented in clinical medical records through the IVF cohort study at our center. In the patients with 0.5cm ≤ EMT ≤ 0.7cm, the embryo implantation rate was statistically significant increased in the patients with the presence of subendometrial blood flow (OR 1.484; 95% CI, 1.001-2.200; P = 0.049; aOR 1.425; 95% CI, 1.030-2.123; P = 0.003). Patients with discernible subendometrial blood flow have superior live birth (P = 0.028), clinical pregnancy (P = 0.049), and embryo implantation (P = 0.027) compared to the patients without subendometrial blood flow when the EMT is ≤ 0.7cm. The presence of subendometrial blood flow detected by ultrasound was positively associated with successful embryo implantation and favorable pregnancy outcomes in patients with thin endometrium undergoing FET.