Flow Analysis Research Articles

The brain-protective mechanism of fecal microbiota transplantation from young donor mice in the natural aging process via exosome, gut microbiota, and metabolomics analyses

The natural aging process is accompanied by changes in exosomes, gut microbiota, and metabolites. This study aimed to reveal the anti-aging effect and mechanisms of fecal microbiota transplantation (FMT) from young donors on the natural aging process in mice by analyzing exosomes, gut microbiota, and metabolomics. Aging-relevant telomeric length, oxidative stress indexes in brain tissue, and serum cytokine levels were measured. Flow analysis of T-regulatory (Treg), CD4+, and CD8+ cells was performed, and the expression levels of aging-related proteins were quantified. High-throughput sequencing technology was used to identify differentially expressed serum exosomal miRNAs. Fecal microbiota was tested by 16S rDNA sequencing. Changes in fecal metabolites were analyzed by UPLC-Q-TOF/MS. The results indicated that the expression of mmu-miR-7010-5p, mmu-miR-376b-5p, mmu-miR-135a-5p, and mmu-miR-3100-5p by serum exosomes was down-regulated and the abundance of opportunistic bacteria (Turicibacter, Allobaculum, Morganella.) was decreased, whereas the levels of protective bacteria (Akkermansia, Muribaculaceae, Helicobacter.) were increased after FMT. Metabolic analysis identified 25 potential biomarkers. Correlation analysis between the gut microbiota and metabolites suggested that the relative abundance of protective bacteria was positively correlated with the levels of spermidine and S-adenosylmethionine. The study indicated that FMT corrected brain injury due to aging via lipid metabolism, the metabolism of cofactors and vitamins, and amino acid metabolism.

Local nonsimilar solution and heat analysis of mixed convective flow across whole spherical shape with nonisothermal surface temperature

This study investigates the behavior of a mixed convective boundary layer flowing around a rigid spherical shape with non-isothermal wall temperature. The fluid assumed in this examination exhibits both incompressibility and viscosity. The major purpose is to examine the impact of the non-uniform surface temperature on the flow patterns, including velocity outlines and temperature outlines. An examination is conducted on the modified conservation equations of the boundary layer flow utilizing the local non-similarity method. The MATLAB built-in code bvp4c is used to find computational solutions. The outcomes are then shown for both air and water, specifically at a temperature of 21°C. The influence of several factors, such as the mixed convective variable [Formula: see text] and the exponent [Formula: see text] in the wall temperature function [Formula: see text]), is shown in velocity and temperature profiles. In addition, the study computes the local frictional force factor and local wall heat transport factor and compares these values with results from earlier research. Significantly, the study expands upon data made around the lower stagnating point to include other sites within the sphere, thereby offering a thorough comprehension of the whole flowing field.

Mapping chromium flows in China's stainless-steel product chain: A product-level substance flow analysis

Chromium (Cr) is a critical metal that supports the development of China's emerging industries. Approximately 82% of China's Cr is used to manufacture stainless steel. However, the stainless-steel product chain has often been referred to as a “black box” in Cr substance flow analysis, leading to limited guidance for Cr management. This study aims to fill this gap by analysing Cr flows and in-use stock patterns in China's stainless-steel product chain from 2012 to 2022. During this period, China's Cr consumption experienced significant growth, increasing by over 10% annually, with 90.4% being imported. The Energy Infrastructure sector emerged as the dominant consumer of Cr (8,099 kt) and in-use stock (7,702 kt), Heavy Machinery products accounting for the highest Cr consumption (3,269 kt). Conducting product-level SFA is crucial for sustainable Cr resource management and environmental policy-making.

Convergence of gradient descent for learning linear neural networks

We study the convergence properties of gradient descent for training deep linear neural networks, i.e., deep matrix factorizations, by extending a previous analysis for the related gradient flow. We show that under suitable conditions on the stepsizes gradient descent converges to a critical point of the loss function, i.e., the square loss in this article. Furthermore, we demonstrate that for almost all initializations gradient descent converges to a global minimum in the case of two layers. In the case of three or more layers, we show that gradient descent converges to a global minimum on the manifold matrices of some fixed rank, where the rank cannot be determined a priori.

Melting heat transfer and entropy analysis of MHD Casson nanofluid flow through a stretchy surface with Joule heating and complete slip

Purpose The purpose of this study is to examine the melting heat transfer of magnetohydrodynamics Casson nanofluid flow with viscous dissipation, radiation, and complete slip effects on a porous stretching sheet. Since, the study of melting heat transfer has mesmerized the attention of scientists and engineers in the sense of its enormous uses in industrial processes, solidification, casting, and technology. Design/methodology/approach Bejan number and entropy are analyzed. Exploration of irreversibility is modeled using the thermodynamics second law. There is a discussion on thermophoresis and Brownian diffusion along with first-order chemical reactions. Adequate transformations are introduced to convert the controlling partial differential equations to ordinary differential equations. The three-phase Lobatto solvers (bvp5c) are used to obtain numerical solutions of the transmitted equations. Findings The effects of various factors on temperature, velocity, concentration, Bejan number and entropy rate are shown graphically. The velocity field is enhanced by increasing the melting heat parameter, and it declines for growing magnetic parameters. Temperature is decreased for increasing parametric values of melting heat, porous and Casson parameters. A 7% decrease in the Sherwood distribution is seen when we increase the Brownian motion parameter from 0.1 to 0.2. Similarly, an 11% decrement is found in the Nusselt distribution for increasing the Brinkman number from 0.5 to 1. Originality/value Entropy and Bejan number experience dual tendencies whenever the melting heat parameter increases. Nusselt number and skin friction experience the opposite behavior for the increasing values of melting parameter. Sherwood number decreases for the increasing values of melting parameter. The velocity profile is directly related to the melting parameter and inversely related to porous and magnetic parameters. Thermophoresis and Brinkman parameters boost the temperature profile and it is controlled by melting and porous parameters. Some notable fields where the present study is used inevitably are silicon wafering, geothermal energy recovery and semiconductor manufacturing.

Measuring system resilience through a comparison of information- and flow-based network analyses

Quantifying the properties of complex, self-organizing systems is increasingly important for understanding the development and state of modern systems. Case studies have recommended sustainability frameworks predominately in literature, but little emphasis has been placed on methodological evaluation. Data availability is often an obstacle that constrains conventional flow-based network analysis, but a novel information-based technique (QtAC) developed by zu Castell and Schrenk overcomes these constraints by modelling interactions between agents as information transfers. This study compares the QtAC method to conventional flow analysis by applying both to the same 90-year dataset containing socio-economic data from the island of Samothraki, Greece. Resilience indicators, based on Ulanowicz’s ascendency analysis, are derived on both the information- and flow-based networks. We observe that the resulting dynamics of the information-based networks align closer with complex system dynamics as theorized by the adaptive cycle model. Additionally, we discuss how QtAC offers different interpretations of network indicators when compared to usual interpretations of flow analysis. Ultimately, QtAC is shown to provide an alternative for complex systems analysis if the data situation does not allow for conventional flow-analysis. Furthermore, we show that the combination of both approaches can yield valuable new insights.

Scenario Analysis of Food Phosphorus Footprint in Kisumu, a Lakeside East African City in Lake Victoria (Kenya)

Increased food production and consumption patterns have resulted in higher urban food phosphorus footprints, leading to a series of resource and environmental problems worldwide. We quantified the food phosphorus footprint of the African city of Kisumu using substance flow analysis. Our aim was to develop Kisumu’s sustainable phosphorus management framework so that the city would reduce phosphorus losses into the food system. Our results show that in the year 2023, the import and export of food phosphorus in the Kisumu food system was 2730.26 ± 2.7% t P yr−1 and 3297.05 ± 2.4% t P yr−1, respectively. There was −566.79 ± −18% t P yr−1 food phosphorus deficit in the Kisumu food system. Crop planting subsystem runoff/leaching/erosion loss, household consumption subsystem waste loss, and pit latrine subsystem blackwater loss are the major pathways of phosphorus losses into the environment and the main contributors to the food phosphorus footprint in the city. The 2030 scenario analysis shows that implementing a comprehensive scenario scheme throughout the entire lifecycle process from phosphorus input to waste disposal is the best choice for reducing phosphorus losses and suppressing the growth of food phosphorus footprint in the future. Our study shows that the food phosphorus footprint in the Kisumu food system was 0.67 kg P cap−1yr−1 in 2023, which is still at a low level but may enter a continuous upward trend with the improvement of socio-economic development of the city. In our framework, we have proposed a few essential measures that include urine separation, installation of septic tank, adjustment of dietary structure, flexible layout of sanitary disposal facilities, and separation of organic waste streams to reduce food phosphorus footprints in Kisumu. Given the similarity of cities along the shores of Lake Victoria, our calculation methods and management strategies can be applied to other cities in the region.

Analysis of unsteady flow of [formula omitted] based nanoparticle of different shapes in the presence of joule heating over stretching surface

This work investigates the unsteady flow behavior of variously shaped Cunanoparticles based EG-nanofluid in the presence of Joule heating across a stretched surface. The study's objective is to comprehend and explore how the geometry of nanoparticles affects the thermal behavior and velocity field of a nanofluid flow. The matter is significant because it has an impact on industrial processes, thermal management systems, and cooling technologies. Moreover, the influence of joule heating on convective heat transfer is examined. In order to account for unsteadiness and shape-dependent nanoparticle features, numerical solutions are derived for the major equations of corresponding thermal phenomenon of nanofluid flow. The acquired results shed important light on how the form of nanoparticles and Joule heating affect the properties of heat transfer across the stretching sheet. Meanwhile, friction coefficient and local Nusselt number are calculated numerically and tabulated for discussion. Cu nanoparticles in various forms and other relevant parameters are investigated for their effects on flow, joule heating properties, and heat transmission. Significant evidence shows that using spherical nanoparticles instead of cylindrical or platelet-shaped ones results in a 15 % boost in heat transmission rates. Moreover, Joule heating has significant effect over thermal boundary layer and can generally boost heat transfer by up to 20 %. It is argued that the thermal efficiency of nanofluid systems can be greatly increased by optimizing the form of nanoparticles and taking Joule heating into account. This work is novel due to it fully examines the combined impact of Joule heating and nanoparticle morphology on unstable nanofluid flow, offering new perspectives beyond previous studies that mostly focused on steady-state conditions or disregarded the shape aspect. Through a deeper comprehension of nanofluid behavior in dynamic environments, our work opens the door to more efficient thermal management system design.

Thermal analysis of Casson nanofluid flow over exponentially/horizontally stretching cylinders with physical conditions

Thermal analysis of Casson nanofluid flow over exponentially/horizontally stretching cylinders with physical conditions

A combined radio-immunotherapy regimen eradicates late-stage tumors in mice

BackgroundThe majority of experimental approaches for cancer immunotherapy are tested against relatively small tumors in tumor-bearing mice, because in most cases advanced cancers are resistant to the treatments. In this study, we asked if even late-stage mouse tumors can be eradicated by a rationally designed combined radio-immunotherapy (CRI) regimen.MethodsCRI consisted of local radiotherapy, intratumoral IL-12, slow-release systemic IL-2 and anti- CTLA-4 antibody. Therapeutic effects of CRI against several weakly immunogenic and immunogenic mouse tumors including B78 melanoma, MC38 and CT26 colon carcinomas and 9464D neuroblastoma were evaluated. Immune cell depletion and flow cytometric analysis were performed to determine the mechanisms of the antitumor effects.ResultsTumors with volumes of 2,000 mm3 or larger were eradicated by CRI. Flow analyses of the tumors revealed reduction of T regulatory (Treg) cells and increase of CD8/Treg ratios following CRI. Rapid shrinkage of the treated tumors did not require T cells, whereas T cells were involved in the systemic effect against the distant tumors. Cured mice developed immunological memory.ConclusionsThese findings underscore that rationally designed combination immunotherapy regimens can be effective even against large, late-stage tumors.

Climatic fluctuations, geographic features, and evolutionary forces: Shaping high genomic diversity and local adaptation in Muntiacus reevesi

AbstractAimGenetic diversity is crucial for species adaptability. Understanding the mechanisms behind its formation and maintenance is essential for effective conservation. Recent studies have demonstrated that despite experiencing severe population bottlenecks, Muntiacus reevesi retains high genetic diversity and continues its northward migration, indicative of ongoing adaptive evolution. However, our comprehension of this phenomenon remains incomplete. The objective of this study is to explore the mechanisms underlying the formation of high genetic diversity and the genomic characteristics associated with local adaptation, using M. reevesi as a case study.LocationSouthern China.MethodsWe analysed resequencing data from 62 genomes and identified 29,124,081 high‐quality single‐nucleotide polymorphisms (SNPs). We used population genetics, demographic history, population differentiation, gene flow analysis software, and genotype‐environment association (GEA) models to assess the factors that have contributed to high genetic diversity and environmental adaptability in the historical climate and geographical context.ResultsThe study identified that during Pleistocene climatic fluctuations, M. reevesi diverged into eastern (DB and WJW populations) and western lineages (WL, BA, and QL populations), all displayed high genetic diversity. Historically, M. reevesi maintained large effective populations, but contemporary human‐induced threats have led to a significant decline. Population differentiation models suggest distinct expansion pathways for eastern and western lineages, resulting in population admixture, with mountain corridors facilitating gene flow and maintaining high genetic diversity. Additionally, environmental‐genotype analysis revealed local adaptation in the QL‐BA population, highlighting candidate adaptive genes (ME3 and PRKG1) potentially linked to cold adaptation and foraging behaviour.ConclusionThis study enhances our understanding of the mechanisms behind the high genetic diversity and environmental adaptability of M. reevesi, offering insights into how bottleneck populations maintain diversity, crucial for biogeographic research and conservation strategies for similar species.

Phosphorus Flow Analysis in Lithuania

Substance flow analysis was used to analyze phosphorus (P) flows, accumulations and losses in Lithuania. P and phosphate rock are included in the list of EU critical raw materials, showing their importance for the EU economy, especially agriculture, and supply risks. It is important to minimize P losses as much as possible, avoid inefficient use, and maximize the potential of secondary P. The analysis showed Lithuania’s huge dependence on P imports, which occurred because one of the largest P fertilizer factories operates in the country, and the country also grows and exports a significant amount of cereals. In total, 69% of P addition to soil is from mineral fertilizers. The potential of secondary P is only partially used, mainly via manure, which constitutes 83% of the recycled P and adds 26% of P to agricultural soil. In total, 58% of P “waste” is either lost or accumulated, largely in phosphogypsum stacks. If this P was fully utilized, the country could reduce the current usage of mineral fertilizers by 71%; without P in phosphogypsum, the reduction would be just 7.2%. The P balance in Lithuanian soil is close to neutral. Agricultural leaching and erosion are the main reasons for P entering water bodies (78% of P) and, therefore, should be further reduced.

Fractional analysis of unsteady magnetohydrodynamics Jeffrey flow over an infinite vertical plate in the presence of Hall current

The impact of Hall current on the multiphase thermal transfer of an incompressible electrically conductive Jeffrey flow over an infinitely vertical plate when heat absorption and chemical reaction are present has been examined. Partial differential equations have been used to describe the process, accounting for heat and mass transfer effects. This study uses extended Fourier's and Fick's laws together with the recently announced constant proportional Caputo (CPC) fractional operator. The fractional model is converted into a nondimensional form by applying some appropriate quantities. The nondimensional produced fractional model for momentum, heat, and diffusion equations based on the CPC fractional operator has been calculated semi‐analytically by applying the Laplace method. The Mathcad 15 software to sketch the graphs for several factors, like the Grashof number, mass Grashof number, Schmidt number, Prandtl number, Hall, and magnetic field parameters, is used to describe the velocity profile. Additionally, a graphical explanation is provided for the influence of the appeared parameters, particularly the effect of the fractional parameters. It is concluded that the result of the fluid model developed by the generalized constitutive relations is more accurate and generalized than the results of the artificially contracted fractional model. A fractional derivative is therefore the ideal option to achieve controlled concentration, temperature, and velocity. The current study is immediately relevant to geophysical, cosmically fluid dynamics, medical, biological, and any other processes that are significantly enhanced by a low gas density and a high magnetic field.

Heat transfer and fluid flow analysis of PCM-based thermal energy storage concept for double pass solar air heater

Solar air heaters (SAHs) are flat plate collectors used for drying applications without causing any negative impact to the environment. However, SAH suffers from two drawbacks: first is the low convective heat transfer due to formation of boundary layer along the absorber plate, and second is the low thermal efficiency resulting from the lack of solar energy available after sunshine hours. The present study aims to examine the heat transfer and friction factor characteristics of double-pass SAH using two composite roughness geometries: perforated baffles and semicylindrical PCM tubes. The study is conducted at design parameters: blockage ratio (eb/Hd) of 0.4 to 0.8 and tube radius ratios (rt/Hd) of 0.2 to 0.5 under different Reynolds numbers (Re) from 3000 to 13,000. The maximum Nusselt number (Nu) and friction factor (f) are determined to be 200 at Re of 13,000 and 0.629 at Re of 3000, respectively, for the constant value of rt/Hd as 0.3 and eb/Hd as 0.8. In the range of parameters analyzed, maximum increase in Nu and f is determined to be 5.08 times and 65.80 times, respectively, over the smooth duct. Furthermore, correlations are derived for Nu and f with mean absolute error of 4.7% and 3.8%, respectively.

Robust analysis of microcirculatory flowmotion during post-occlusive reactive hyperemia

BackgroundFlowmotion analysis of the microcirculatory blood flow is a method to extract information about the vessel regulatory function. It has previously shown promise when applied to measurements during a post-occlusive reactive hyperemia. The reperfusion peak and the following monotonic decline introduces false low frequencies that should not be interpreted as rhythmic vasomotion effect. AimTo develop and validate a robust method for flowmotion analysis of post-occlusive reactive hyperemia signals. MethodThe occlusion-induced reperfusion response contains a typical rapid increase followed by a monotonic decline to baseline. A mathematical model is proposed to detrend this transient part of the signal to enable further flowmotion analysis. The model is validated in 96 measurements on healthy volunteers. ResultsApplying the proposed model corrects the flowmotion signal without adding any substantial new false flowmotion components. ConclusionFuture studies should use the proposed method or equivalent when analyzing flowmotion during post-occlusive reactive hyperemia to ensure valid results.

Experimental and CFD analysis of fluid flow through nanofiber filter media

This work presents a novel approach to investigating the slip effect in nanofiber filter media. Electrospun nanofiber media with high efficiency and low pressure drop were produced at different concentrations and durations. The surface and cross-sectional morphology of nanofiber media were studied using FE-SEM. Fiber orientation and diameter distributions were also examined. The 3D virtual nanofiber media was modeled using this information along with the experimentally measured porosity and thickness of the media. The effect of the slip phenomenon in nanofiber media was studied numerically, and the results were compared to experimental data. Excellent agreements were found between the measured and simulation results. Additionally, filtration simulations considering aerosols injected with airflow through the nanofibrous filter media were conducted by considering the slip effect, and the effect of filter structure on filtration performance (removal efficiency and pressure drop) was investigated.

Heat flow analysis and description of the cooperation of the heat exchange station with heat exchange substations located in apartments

Heat flow analysis and description of the cooperation of the heat exchange station with heat exchange substations located in apartments

Flow analysis of a two-layered micropolar fluid in a catheterized oesophageal tube under the influence of a dilating amplitude: Application to pre-diagnosis of oesophageal motility disorder

This study employs the Homotopy perturbation method to analyze the behavior of immiscible, incompressible fluids within a cylindrical coaxial tube, focusing on scenarios relevant to physiological fluid dynamics, particularly in the catheterized oesophagus and similar biological systems. Adopting long-wavelength and low Reynolds number approximations, a two-layered model is proposed with a micropolar fluid in the core and a Newtonian fluid in periphery regions. Parameters such as velocity, flux, friction, pressure, and impedance variations are formulated, particularly under the influence of dilating wave amplitude. Generally, when a catheter is introduced, pressure rises. It is further found that while pressure falls with increasing micropolar parameter, it rises with coupling number upon catheter insertion. Thus feeding patients with micropolar fluids during catheter-assisted pre-diagnosis is impractical due to associated pressure rise. Observations suggest a complex pressure profile during bolus passage through the oesophagus due to the broadening of the catheter size. Additionally, impedance exponentially increases with catheter size, influenced by the micropolar parameters and the coupling numbers, with micropolar fluids exhibiting higher impedance than that with Newtonian fluids. However, this study underscores the significant impact of catheterization on physiological fluid dynamics, notably increasing oesophageal impedance by two to threefold. This highlights the critical role of catheters in altering flow characteristics, emphasizing the need for a careful medical intervention during pre-diagnostic assessments.

Analyses of Jet Buoyant Flow in a Multicompartment Containment Using an Open-Source Solver

Hydrogen mixing and distribution in a nuclear power plant containment during a postulated severe accident is a phenomenon with high safety relevance for current and advanced light water reactors. The Organisation for Economic Co-operation and Development (OECD)/Nuclear Energy Agency (NEA) SESAR Thermal-Hydraulics (SETH) project was carried out to generate experimental data on basic containment phenomena with the required instrumentation to assess computational fluid dynamics (CFD) and lumped parameter codes. In this paper, we analyze the PANDA SETH Test 16 of the OECD/NEA SETH project using containmentFOAM, which is a tailored open-source CFD code package for containment analysis developed at Forschungszentrum Jülich GmbH based on OpenFOAM.® SETH Test 16 addressed steam-air mixture transport driven by jets and plumes in the multicompartment PANDA facility (two vessels and an interconnecting pipe) at the Paul Scherrer Institut in Switzerland. Steam as a wall plume was injected at 0.040 kg/s and 140°C in vessel 1, which was initially filled with dry air at 108°C. The steam-air mixture was vented out from the top of vessel 2. The system pressure was constant at 1.3 bar for the whole test duration (4000 s). To simulate SETH Test 16, the k-ω shear stress transport turbulence model was adopted with the generalized gradient diffusive hypothesis buoyancy turbulence model. The simulation represented the experimental phenomenology reasonably well. The trends for the calculated temperature distribution were similar to those of the experiments and only yielded a slight discrepancy of about 2.7%. In addition, the distribution of the steam molar fraction was well predicted above the injection tube in vessel 1. However, below the injection tube in vessel 1, some discrepancies between the simulations and the experimental results were observed. These may have been caused by the higher turbulent mass diffusivity in the physical model and the challenge of the mesh resolution in the middle region of vessel 1.

Valuation of cyclical assets and exit value

PurposeOrdinary direct capitalization is normally considered procyclical in its present form (De Lisle Grissom, 2011); for this reason, an alternative approach to direct capitalization may be useful in the determination of a robust opinion of value. The valuation standards propose an alternative determination of terminal value in the discounted cash flow analysis, recommending that for cyclical assets, the terminal value should consider … “the cyclical nature of the asset and should not be performed in a way that assumes “peak” or “trough” levels of cash flows in perpetuity” (IVS 105 Valuation Approaches and Methods para 50.21 lett e).Design/methodology/approachThe introduction in International Valuation Standards (IVS) of Cyclical Assets raises several questions for the community of real estate professionals and academicians (IVS, 2022, 105 Valuation Approaches and Methods para 50.09 lett d). Cyclical assets can be defined as property whose value is “influenced by upturn and downturn of the market in a significant way” (d’Amato et al., 2019).FindingsThe paper proposes different solutions to the problem. The determination of the exit value using cyclical capitalization allows for a prudent assessment of the value and may be used either as a valuation procedure or a risk analysis method.Research limitations/implicationsThe valuation comparison with the traditional valuation techniques will be based on an iteration of exit value in order to determine the effects of the valuation procedure on the opinion of value.Practical implicationsThe implication of the valuation procedure is the introduction of a countercyclical valuation method to determine the exit value in order to reach stable and reliable valuations for income-producing properties.Social implicationsThese models may have a social implication, providing valuation for income-producing properties that may deal with the property market cycle in a more efficient way, providing efficient valuation for banks and institutions.Originality/valueThe paper is the first application of such a valuation procedure to the determination of exit value.