Search Results (90)

This paper investigates the flow of a second-grade hybrid nanofluid through a Darcy–Forchheimer porous medium under Cattaneo–Christov heat and mass flux models. The hybrid nanofluid, composed of alumina and copper nanoparticles in water, enhances thermal and mass transport, while the second-grade model captures viscoelastic effects, and the Darcy–Forchheimer medium accounts for both linear and nonlinear drag. Using similarity transformations and the spectral quasilinearisation method, the nonlinear governing equations are solved numerically and validated against benchmark results. The results show that hybrid nanoparticles significantly boost heat and mass transfer, while Cattaneo–Christov fluxes delay thermal and concentration responses, reducing the near-wall temperature and concentration. The distributions of velocity, temperature, concentration, and microorganism density are markedly affected by porosity, the Forchheimer number, the bio-convection Peclet number, and relaxation times. The results illustrate that hybrid nanoparticles significantly increase heat and mass transfer, whereas thermal and concentration relaxation factors delay energy and species diffusion, thickening the associated boundary layers. Viscoelasticity, porous medium resistance, Forchheimer drag, and bio-convection all have an influence on flow velocity and transfer rates, highlighting the subtle link between these mechanisms. These breakthroughs may be beneficial in establishing and enhancing bioreactors, microbial fuel cells, geothermal systems, and other applications that need hybrid nanofluids and non-Fourier/non-Fickian transport. Full article

Thorium-rare earth-iron oxide deposits of the Lemhi Pass district, Idaho and Montana, are enriched in the middle rare earth elements (REE), and particularly neodymium (Nd). Overall, thorium (Th) and total rare earth oxide (TREO) grades of the deposits are sub equal at 0.4 wt. % but locally exceed 1 wt. % TREO. Nd-monazite, the major REE phase (35 wt. % Nd₂O₃) occurs in hydrothermal Th-REE mineralized quartz veins and biotite-rich shear zones of enigmatic origin. Hosted in Mesoproterozoic metasedimentary rocks, the deposits are modest in size but present over a large area with no obvious source pluton exposed. This paper documents the geochemistry of the monazite and provides the first geochronological data to constrain its origin. Elemental mapping and U-Th-total Pb EPMA dating of the monazite and thorite document a Paleozoic age for mineralization centered in the Late Devonian at approximately 355 Ma ± 20 Ma. A second period of volumetrically minor Th and REE remobilization is dated as Mesozoic (ca. 100 Ma). For context, a reactivated passive continental margin was present during the Devonian in eastern Idaho, while the Mesozoic was a time of major accretionary tectonics and arc magmatism further west. Nd and Pb isotopic data require a significant interaction of the fluids with an ancient crustal component represented by regional Mesoproterozoic metasedimentary rocks and granitoids. A source–transport–deposition model is hypothesized with metasomatic fractionation and enrichment of Nd during regional hydrothermal circulation. The aqueous fluids were hot, oxidizing, and likely saline, but the exact source of the Th and REEs and the mechanism of enrichment remains problematic. Additional analytical work and increased knowledge of the regional and district geology will improve this unconventional hypothesis for formation of Lemhi Pass’ unusual Nd-rich Th-REE-Fe mineralization. Full article

Axially symmetric Taylor–Couette flows of incompressible second grade fluids induced by time-dependent couples inside an infinite circular cylinder are studied under the action of an external magnetic field. The influence of the medium porosity is taken into account in the mathematical modeling. Analytical expressions for the dimensionless non-trivial shear stress and the corresponding fluid velocity were determined using the finite Hankel and Laplace transforms. The solutions obtained are new in the specialized literature and can be customized for various problems of interest in engineering practice. For illustration, the cases of oscillating and constant couples have been considered, and the steady state components of the shear stresses were presented in equivalent forms. Numerical schemes based on finite differences have been formulated for determining the numerical solutions of the proposed problem. It was shown that the numerical results based on analytical solutions and those obtained with the numerical methods have close values with very good accuracy. It was also proved that the fluid flows more slowly and the steady state is reached earlier in the presence of a magnetic field or porous medium. Full article

Background: Cytokine release syndrome (CRS) is a life-threatening systemic inflammatory condition marked by excessive cytokine production, leading to multi-organ dysfunction. It is commonly associated with T-cell-engaging therapies such as chimeric antigen receptor (CAR) T cells, T-cell receptor bispecific molecules, and monoclonal antibodies. Carfilzomib, a proteasome inhibitor, is known to cause a range of adverse effects, primarily hematologic and cardiovascular. However, multiorgan failure grade 5 (fatal), resembling CRS has not been previously reported in association with Carfilzomib. Case Report: A 74-year-old male with relapsed multiple myeloma developed grade 5 multiorgan failure 60 min after the third dose of Carfilzomib, resulting in death within 24 h of symptom onset. The patient tolerated the first doses of Carfilzomib well with only fever and headache developing post infusion. Before the second dose, the patient developed worsening pancytopenia, prompting the discontinuation of Lenalidomide. After the second Carfilzomib infusion, he experienced fever and transient encephalopathy, which resolved with acetaminophen, corticosteroids, and supportive care. However, following the third dose, he rapidly deteriorated—developing fever, tachycardia, hypotension, hypoxia, and encephalopathy. Despite aggressive management with intravenous fluids, broad-spectrum antibiotics, corticosteroids, and tocilizumab, the patient progressed to refractory shock and multi-organ failure, culminating in death within 24 h. A comprehensive infectious workup was negative, ruling out sepsis and suggesting possible Carfilzomib-induced CRS. Conclusion: Grade 5 multiorgan failure with signs and symptoms similar with CRS following Carfilzomib administration is a rare but potentially fatal adverse drug reaction. Further research is needed to better define the risk factors and optimal management strategies for Carfilzomib-induced multiorgan failure and possible CRS. Full article

A newly recognized fourth type of perivascular space has recently been described in the radiological literature. Despite its growing relevance, many radiologists are still unfamiliar with its imaging characteristics, often leading to misinterpretation as cystic neoplasms. Due to its potential for diagnostic confusion, further studies are necessary—particularly those incorporating high-quality imaging examples across various presentations—to facilitate accurate recognition and classification. Perivascular spaces (PVSs) of the brain are cystic, fluid-filled structures formed by the pia mater and located alongside cerebral blood vessels, particularly penetrating arterioles, venules, and capillaries. Under normal conditions, these spaces are small (typically <2 mm in diameter), but in rare instances, they may become markedly enlarged (>15 mm), exerting a mass effect on adjacent brain tissue. This newly identified fourth type of PVS is found in association with the M2 and M3 segments of the middle cerebral artery, typically within the anterior temporal lobe white matter. It may mimic low-grade cystic tumors on imaging due to its size and frequent presence of surrounding perifocal edema. We present two adult male patients with this rare PVS variant. The first patient, a 63-year-old, had a brain magnetic resonance imaging scan (MRI) that revealed a cystic lesion in the white matter of the right temporal lobe anterior pole, near the middle cerebral artery M2 segment, with perifocal vasogenic edema. The second patient, a 67-year-old, had a brain MRI that showed a cystic lesion in the white matter and subcortical region of the right temporal lobe anterior pole, with minimal surrounding gliosis or minimal edema. The cystic lesions in both patients remained unchanged over time on follow-up MRI. These cases illustrate the radiological complexity of this under-recognized entity and emphasize the importance of differential diagnosis to avoid unnecessary intervention. Full article

Organic Rankine Cycle (ORC) power plants represent one of the most suitable technologies for the recovery and conversion of low-grade thermal energy. Coupling a micro-scale ORC system with parabolic trough collectors (PTCs) as a thermal energy source can effectively meet the electrical and thermal demands of a domestic user. This study presents the development process of the micro-ORC system, detailing both the results of the numerical model and the implementation of the test prototype. Particular attention is given to the instrumentation and sensors installed on the test bench, the monitoring and data acquisition software, and the error propagation analysis applied to the experimental data. In order to develop a micro-scale ORC plant, a commercial hermetic scroll compressor was tested as an expander with HFC-245fa working fluid. The test campaign required the construction of a dedicated experimental setup, equipped with comprehensive monitoring and control systems. While the first part of this research focused on evaluating the use of a scroll compressor as an expander, the second part aims to thoroughly describe the design of the test bench and the numerical model employed, the boundary conditions adopted, and the optimization strategies implemented to enhance system performance. This paper also describes in detail the measurement methodology and the associated error analysis to ensure comparability between experimental and numerical data. The numerical model was experimentally validated by incorporating the actual measured efficiency of the pump system, estimated at 12%. The comparison revealed a deviation between the experimental and simulated absorbed power of the pump—expressed as a function of the evaporation pressure—of less than 10% in the majority of the tested operating conditions. This confirms the reliability of the model and supports its use in future optimization studies. Full article

Axial Couette flows of electrically conducting incompressible second grade fluids are analytically and numerically investigated through a porous medium in the presence of a constant magnetic field. General exact analytical expressions are derived for the dimensionless velocities corresponding to unidirectional unsteady motions in an infinite circular cylinder and between two infinite coaxial circular cylinders. They can be immediately particularized to give similar results for Newtonian fluids in same flows. Exact expressions for steady velocities of a large class of flows were provided. Due to the generality of boundary conditions the problems in discussion are completely solved. For illustration, some case studies with engineering applications are considered and the corresponding velocity fields are provided. Their correctness is graphically proved. It was also proved that the fluid flows slower and the steady state is rather touched in the presence of a magnetic field or porous medium. Moreover, the steady state is rather touched in the case of the motions between circular coaxial cylinders as compared with same motions in an infinite circular cylinder. Full article

The isothermal motion of incompressible second-grade fluids induced by an infinite circular cylinder that rotates around its symmetry axis is analytically and numerically investigated when the magnetic and porous effects are taken into consideration. General closed-form expressions are established for the dimensionless velocity field and the corresponding motion problem is completely solved. For illustration, some special cases are considered, and the results’ correctness is graphically proved. Based on a simple but important observation, the obtained results have been used to provide a general expression for the shear stress corresponding to MHD motions of the same fluids through a porous medium induced by a longitudinal shear stress on the boundary. Finally, graphical representations are used to bring to light the influence of the magnetic field and porous medium on the fluid behavior. It was found that the fluid flows slower and the steady state is reached earlier in the presence of a magnetic field or porous medium. Full article

While our world consistently presents complicated, interdisciplinary problems with STEM foundations, most pre-university curricula do not encourage drawing on multidisciplinary knowledge in the sciences and engineering to create solutions. We developed an instructional approach, Iterative Science and Engineering (ISE), that cycles through scientific investigation and engineering design and culminates in constructing a solution to a local environmental challenge. Next, we created, revised, and evaluated a six-week ISE curricular program, Invasive Insects, culminating in 6th–9th-grade students building traps to mitigate local invasive insect populations. Over three Design-Based Research (DBR) cycles, we gathered and analyzed identical pre and post-test data from 554 adolescents to address the research question: what three-dimensional (3D) science and engineering knowledge do adolescents demonstrate over three DBR cycles associated with a curricular program following the Iterative Science and Engineering instructional approach? Results document students’ significant statistical improvements, with differential outcomes in different cycles. For example, most students demonstrated significant learning of 3D science and engineering argument construction in all cycles—still, students only significantly improved engineering design when they performed guided reflection on their designs and physically built a second trap. Our results suggest that the development, refinement, and empirical evaluation of an ISE curricular program led to students’ design, building, evaluation, and sharing of their learning of mitigating local invasive insect populations. To address complex, interdisciplinary challenges, we must provide opportunities for fluid and iterative STEM learning through scientific investigation and engineering design cycles. Full article

The modified second-grade fluid flow across a plate of semi-infinite extent, which is initiated by the plate’s movement, is considered herein. The relaxation parameters and fractional parameters are introduced to express the generalized constitutive relation. A convolution-based absorbing boundary condition (ABC) is developed based on the artificial boundary method (ABM), addressing issues related to the semi-infinite boundary. We adopt the finite difference method (FDM) for deriving the numerical solution by employing the L1 scheme to approximate the fractional derivative. To confirm the precision of this method, a source term is added to establish an exact solution for verification purposes. A comparative evaluation of the ABC versus the direct truncated boundary condition (DTBC) is conducted, with their effectiveness and soundness being visually scrutinized and assessed. This study investigates the impact of the motion of plates at different fluid flow velocities, focusing on the effects of dynamic elements influencing flow mechanisms and velocity. This research’s primary conclusion is that a higher fractional parameter correlates with the fluid flow. As relaxation parameters decrease, the delay effect intensifies and the fluid velocity decreases. Full article

A 10-field theory for second-grade viscoelastic fluids is developed in the framework of Rational Extended Thermodynamics. The field variables are the density, the velocity, the temperature and the stress tensor. The particular case of an adiabatic fluid is considered. The field equations are determined by use of physical universal principles such as the Galileian and the Entropy Principles. As already proved, Rational Extended Thermodynamics is able to eliminate some inconsistencies with experiments that arise in Classical Thermodynamics. Moreover, the paper shows that, if the quadratic terms are taken into account, the classical constitutive relations for a second-grade fluid can be obtained as a limit case of the field equations of the present theory. Full article

Pancreatic cancer is on track to become the second leading cause of cancer-related deaths by 2030, yet there is a lack of accurate diagnostic tests for early detection. Intraductal papillary mucinous neoplasms (IPMNs) are precursors to pancreatic cancer and are increasingly being detected. Despite the development and refinement of multiple guidelines, diagnosing high-grade dysplasia or cancer in IPMNs using clinical, radiologic, endosonographic, and cyst fluid features still falls short in terms of accuracy, leading to both under- and overtreatment. EUS-guided needle-based confocal laser endomicroscopy (nCLE) is a novel technology that allows real-time optical biopsies of pancreatic cystic lesions. Emerging data has demonstrated that EUS-nCLE can diagnose and risk stratify IPMNs more accurately than conventional diagnostic tools. Implementing EUS-nCLE in clinical practice can potentially improve early diagnosis of pancreatic cancer, reduce unnecessary surgeries of IPMNs with low-grade dysplasia, and advance the field of digital pathomics. In this review, we summarize the current evidence that supports using EUS-nCLE as a diagnostic imaging biomarker for diagnosing IPMNs and for risk stratifying their degree of neoplasia. Moreover, we will present emerging data on the role of adding artificial intelligence (AI) algorithms to nCLE and integrating novel fluid biomarkers into nCLE. Full article

In this study, the Kevin–Voigt viscoelastic constitutive relationship is used to investigate the vibration characteristics and stability of a functionally graded viscoelastic(FGV) fluid-conveying pipe with initial geometric defects under thermal–magnetic coupling fields. First, the nonlinear dimensionless differential equations of motion are derived by applying Timoshenko beam theory. Second, by solving the equilibrium position of the system, the nonlinear term in the differential equations of motion is approximated as the sum of the longitudinal displacement at the current time and longitudinal displacement relative to the position, and the equations are linearized. Third, these equations are discretized using the Galerkin method and are numerically solved under simply supported conditions. Finally, the effects of dimensionless temperature field parameters, dimensionless magnetic field parameters, thermal–magnetic coupling, initial geometric defect types, and the power-law exponent on the complex frequency of the pipe are examined. Results show that increasing the magnetic field intensity enhances the critical velocity of first-order mode instability, whereas a heightened temperature variation reduces the critical velocity of first-order diverge instability. Under thermal–magnetic fields, when the magnetic field intensity and temperature difference are simultaneously increased, their effects on the complex frequency can partially offset each other. Increasing the initial geometric defect amplitude increases the imaginary parts of the complex frequencies; however, for different types of initial geometric defect tubes, it exhibits the most distinct influence only on a certain order. Full article

Background: During the early stages of human fetal development, the fetal skeleton system is chiefly made up of cartilage, which is gradually replaced by bone. Fetal bone development is mainly regulated by the parathyroid hormone parathormone (PTH) and PTH-related protein, with specific calprotectin playing a substantial role in cell adhesion and chemotaxis while exhibiting antimicrobial activity during the inflammatory osteogenesis process. The aim of our study was to measure the levels of PTH and calprotectin in early second trimester amniotic fluid and to carry out a comparison between the levels observed among normal full-term pregnancies (control group) and those of the groups of embryos exhibiting impaired or enhanced growth. Methods: For the present prospective study, we collected amniotic fluid samples from pregnancies that underwent amniocentesis at 15 to 22 weeks of gestational age during the period 2021–2023. Subsequently, we followed up on all pregnancies closely until delivery. Having recorded fetal birthweights, we then divided the neonates into three groups: small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA). Results: In total, 64 pregnancies, including 14 SGA, 10 LGA, and 40 AGA fetuses, were included in our study. Both substances were detected in early second trimester amniotic fluid in both groups. Concentrations of calprotectin differed significantly among the three groups (p = 0.033). AGA fetuses had a lower mean value of 4.195 (2.415–6.425) IU/mL, whereas LGA fetuses had a higher mean value of 6.055 (4.887–13.950) IU/mL, while SGA fetuses had a mean value of 5.475 (3.400–9.177) IU/mL. Further analysis revealed that only LGA fetuses had significantly higher calprotectin concentrations compared to AGA fetuses (p = 0.018). PTH concentration was similar between the groups, with LGA fetuses having a mean value of 13.18 (9.51–15.52) IU/mL, while SGA fetuses had a mean value of 14.18 (9.02–16.00) IU/mL, and AGA fetuses had similar concentrations of 13.35 (9.05–15.81) IU/mL. The differences in PTH concentration among the three groups were not statistically significant (p = 0.513). Conclusions: Calprotectin values in the amniotic fluid in the early second trimester were higher in LGA fetuses compared to those in the SGA and AGA categories. LGA fetuses can possibly be in a state of low-grade chronic inflammation due to excessive fat deposition, causing oxidative stress in LGA fetuses and, eventually, the release of calprotectin. Moreover, PTH concentrations in the amniotic fluid of early second trimester pregnancies were not found to be statistically correlated with fetal growth abnormalities in either LGA or SGA fetuses. However, the early time of collection and the small number of patients in our study should be taken into account. Full article

This paper deals with an initial-boundary value problem modeling the unidirectional pressure-driven flow of a second grade fluid in a plane channel with impermeable solid walls. On the channel walls, Navier-type slip boundary conditions are stated. Our aim is to investigate the well-posedness of this problem and obtain its analytical solution under weak regularity requirements on a function describing the velocity distribution at initial time. In order to overcome difficulties related to finding classical solutions, we propose the concept of a generalized solution that is defined as the limit of a uniformly convergent sequence of classical solutions with vanishing perturbations in the initial data. We prove the unique solvability of the problem under consideration in the class of generalized solutions. The main ingredients of our proof are a generalized Abel criterion for uniform convergence of function series and the use of an orthonormal basis consisting of eigenfunctions of the related Sturm–Liouville problem. As a result, explicit expressions for the flow velocity and the pressure in the channel are established. The constructed analytical solutions favor a better understanding of the qualitative features of time-dependent flows of polymer fluids and can be applied to the verification of relevant numerical, asymptotic, and approximate analytical methods. Full article