Magnetic Volume Research Articles

Unsteady Free Convection of Nanofluid Past an Infinite Vertical Sheet Under the Effects of Inclined Magnetic Field and Cogley Radiation

Background: An infinite vertical sheet is the medium of inquiry for studying the copper- water nanofluid behavior with an inclined magnetic field and Cogley radiation. The research contains significant aspects. The use of this nanofluid is of great practical importance, especially in the areas of energy efficiency, thermal management, radiative cooling for space technology, environmental impact reduction, and improving heat transfer efficiency in electronic device cooling operations. Moreover, the research enhances the understanding and manipulation of sophisticated materials. The uttermost significance of this resides in its capacity to uncover issues inherent in the stages of planning, developing, analyzing, and improving manufacturing processes, possibly securing new solutions via patent protection. Objective: This research aims to provide a comprehensive analysis of the unsteady natural convection of a nanofluid along an infinite vertical sheet. The study focuses on understanding how an inclined magnetic field, Cogley radiation, heat source, and varying nanoparticle volume concentrations impact the velocity, thermal, and concentration profiles of the nanofluid. Additionally, the investigation seeks to evaluate the Nusselt number, Sherwood number, and skin friction coefficient across different concentration profiles to derive meaningful insights. Methods: The Laplace transform (L.T.) method, in combination with the MATLAB symbolic computing program, is used to develop numerical solutions for the main boundary value issues. The Laplace transform technique is used to clarify dimensionless partial differential equations (PDEs) and their limiting situations. An in-depth study is conducted on the profiles of momentum, energy, and concentration for various kinds of nanofluids with changing volume concentrations of nanoparticles. This research provides a comprehensive examination and also identifies prospective prospects in this field that might be protected by patents. Result: The work provides an in-depth understanding of how inclined magnetic fields, Cogley radiation, heat generation, and nanoparticle volume concentration affect the velocity, energy, and mass profiles of the nanofluid. Graphical representations depict these effects, offering a visual comprehension of the system's behavior. The Nusselt number and skin friction coefficient are determined by analytical and numerical methods. These findings demonstrate that the Nusselt number and skin friction coefficient have an inverse relationship with changes in concentration profiles. Conclusion: The work improves our comprehension of the fluctuating natural convection of nanofluids across an unbounded vertical surface, taking into account variables such as an inclined magnetic field, heat source, Cogley radiation, and nanoparticle volume concentration. The practical implications of the discoveries, together with the analytical and numerical results, enhance our comprehension of the dynamics of nanofluid systems. Ensuring the protection and widespread distribution of patented technology is essential for promoting sustainable advancements.

Influence of mixed particle sizes on shear yield stress of magnetorheological fluid

AbstractThis study investigated the effect of magnetic particle size and volume fraction on the shear yield stress and dynamic viscosity of magnetorheological fluids. Magnetorheological fluids with varying volume fractions of micro‐ and nanoscale magnetic particles were prepared. A plate‐on‐plate shear test bench was constructed to evaluate the fluids under a constant shear rate, with the applied current ranging from 0 A to 1.2 A. Results indicated that the shear yield stress initially increased and then decreased as the volume fraction of magnetic nanoparticles increased, reaching a maximum of 47 kPa at a volume fraction of 7 %. However, the excessive addition of magnetic particles or large‐diameter particles led to settling and reduced stability of the fluids. The findings suggest that optimizing the size and volume fraction of magnetic particles is crucial for maximizing the shear yield stress of magnetorheological fluids.

Sex/gender effects of glial reactivity on preclinical Alzheimer's disease pathology.

Glial reactivity may contribute to sex/gender differences in Alzheimer's disease (AD) pathophysiology. Here, we investigated the differential effect of cerebrospinal fluid (CSF) glial markers on AD pathology and neurodegeneration by sex/gender among cognitively unimpaired older adults at increased risk of developing AD. We included 397 participants from the ALFA+ cohort with CSF Aβ42/40, p-tau181, sTREM2, YKL40, and GFAP, magnetic resonance imaging-based hippocampal volume (n = 299), and amyloid burden (centiloids) measured with [18F] flutemetamol positron emission tomography (n = 341). We ran multiple linear regression models to assess the association between glial markers, AD pathology and hippocampal volumes and their interaction with sex/gender, usingFalse Discovery Rateto correctfor multiple comparisons. Glial markers significantly contributed to explain amyloid burden, tau pathology, and hippocampal volumes, beyond age and/or primary AD pathology in a sex/gender-specific manner. Compared to men, women showed increased amyloid burden (centiloids) and CSF p-tau181 with increasing levels of sTREM2 and YKL40, and YKL40 and GFAP, respectively. Compared to women, men with greater tau burden showed lower hippocampal volumes as CSF YKL40 levels increased. Overall, our findings suggest that glial reactivity may contribute to sex/gender differences in AD progression, mostly, downstream amyloid. Further research identifying sex/gender-specific temporal dynamics in AD development is warranted to inform clinical trials.

Cardiac magnetic resonance imaging-derived right ventricular volume and function, and association with outcomes in isolated tricuspid regurgitation

Cardiac magnetic resonance imaging-derived right ventricular volume and function, and association with outcomes in isolated tricuspid regurgitation

Datopotamab-deruxtecan plus durvalumab in early-stage breast cancer: the sequential multiple assignment randomized I-SPY2.2 phase 2 trial.

Sequential adaptive trial designs can help accomplish the goals of personalized medicine, optimizing outcomes and avoiding unnecessary toxicity. Here we describe the results of incorporating a promising antibody-drug conjugate, datopotamab-deruxtecan (Dato-DXd) in combination with programmed cell death-ligand 1 inhibitor, durvalumab, as the first sequence of therapy in the I-SPY2.2 phase 2 neoadjuvant sequential multiple assignment randomization trial for high-risk stage 2/3 breast cancer. The trial includes three blocks of treatment, with initial randomization to different experimental agent(s) (block A), followed by a taxane-based regimen tailored to tumor subtype (block B), followed by doxorubicin-cyclophosphamide (block C). Subtype-specific algorithms based on magnetic resonance imaging volume change and core biopsy guide treatment redirection after each block, including the option of early surgical resection in patients predicted to have a high likelihood of pathologic complete response, which is the primary endpoint assessed when resection occurs. There are two primary efficacy analyses: after block A and across all blocks for six prespecified HER2-negative subtypes (defined by hormone receptor status and/or response-predictive subtypes). In total, 106 patients were treated with Dato-DXd/durvalumab in block A. In the immune-positive subtype, Dato-DXd/durvalumab exceeded the prespecified threshold for success (graduated) after block A; and across all blocks, pathologic complete response rates were equivalent to the rate expected for the standard of care (79%), but 54% achieved that result after Dato-DXd/durvalumab alone (block A) and 92% without doxorubicin-cyclophosphamide (after blocks A + B). The treatment strategy across all blocks graduated in the hormone-negative/immune-negative subtype. No new toxicities were observed. Stomatitis was the most common side effect in block A. No patients receiving block A treatment alone had adrenal insufficiency. Dato-DXd/durvalumab is a promising therapy combination that can eliminate standard chemotherapy in many patients, particularly the immune-positive subtype.ClinicalTrials.gov registration: NCT01042379 .

A hybrid, nonlinear programming approach for optimizing passive shimming in MRI.

In magnetic resonance imaging (MRI), maintaining a highly uniform main magnetic field (B0) is essential for producing detailed images of human anatomy. Passive shimming (PS) is a technique used to enhance B0 uniformity by strategically arranging shimming iron pieces inside the magnet bore. Traditionally, PS optimization has been implemented using linear programming (LP), posing challenges in balancing field quality with the quantity of iron used for shimming. In this work, we aimed to improve the efficacy of passive shimming that has the advantages of balancing field quality, iron usage, and harmonics in an optimal manner and leads to a smoother field profile. This study introduces a hybrid algorithm that combines particle swarm optimization with sequential quadratic programming (PSO-SQP) to enhance shimming performance. Additionally, a regularization method is employed to reduce the iron pieces' weight effectively. The simulation study demonstrated that the magnetic field was improved from 462 to 3.6ppm, utilizing merely 1.2kg of iron in a 40cm diameter spherical volume (DSV) of a 7T MRI magnet. Compared to traditional optimization techniques, this method notably enhanced magnetic field uniformity by 96.7% and reduced the iron weight requirement by 81.8%. The results indicated that the proposed method is expected to be effective for passive shimming.

A novel amplitude enhancement method of EMAT for High-frequency Rayleigh-like waves in Circumferential propagation

Currently, in terms of resolution and excitation efficiency for pipeline inspection, the high-frequency Rayleigh-like wave excited by an EMAT with a traditional Rayleigh wave EMAT structure is not optimal when using the same magnet volume. This paper introduces an EMAT performance evaluation method focused on 'bandwidth' in the high-frequency-thickness region of circumferential guided waves. A wavenumber spectrum analysis method utilizing combined equivalent surface stresses is proposed to quantify this optimize design. Comparative studies, including theoretical analysis and experimental validation, demonstrate that incorporating bandwidth significantly improves the design of Rayleigh-like waves at high frequencies. The proposed EMAT achieves a performance improvement of 2.4 times for inside pipe excitation and 2.6 times for outside pipe excitation over the conventional structure. The occurrence of multiple wave packets outside the optimal excitation frequency range is acknowledged. Therefore, this method offers a new approach for optimizing EMATs for Rayleigh-like waves.

Improvement of electromagnetic torque of BLDC motor for electrical cutter application

As the advancement of brushless direct current (BLDC) motor is rising, it has been an advantage to use the motor for a wide range of applications. Its robustness and torque development have benefited small applications, such as the agriculture cutter. However, dropping performances of conventional BLDC are affected by the shape of the rotor that has unused magnetic flux. Therefore, this research aimed to analyze the electromagnetic torque by reducing the unused flux from an electromagnetic point of view. Two BLDC models with different slot-pole numbers and rotor types were modeled and simulated with equal permanent magnet volume, and magnetomotive force (MMF). Finite element method (FEM) software was used to compute back electromotive force (BEMF), cogging torque, electromagnetic torque, and magnetic flux density of the BLDC models. As a result, 9/8 slot-pole with zero ferromagnetic underneath the permanent magnet had the highest BEMF and torque produced compared to the conventional type, with a percentage difference of 27%. In conclusion, this research presents the motor that had an improvement of electromagnetic torque for electrical cutter application.

Spin order and dynamics in the topological rare-earth germanide semimetals

The REAl(Si,Ge) (RE = rare earth) family, known to break both the inversion- and time-reversal symmetries, represents one of the most suitable platforms for investigating the interplay between correlated-electron phenomena and topologically nontrivial bands. Here, we report on systematic magnetic, transport, and muon-spin rotation and relaxation (uSR) measurements on (Nd,Sm)AlGe single crystals, which exhibit antiferromagnetic (AFM) transitions at TN = 6.1 and 5.9 K, respectively. In addition, NdAlGe undergoes also an incommensurate-to-commensurate ferrimagnetic transition at 4.5 K. Weak transverse-field µSR measurements confirm the AFM transitions, featuring a ∼90% magnetic volume fraction. Zero-field (ZF) µSR measurements reveal a more disordered internal field distribution in NdAlGe than in SmAlGe, reflected in a larger transverse muon-spin relaxation rate λT at T ≪ TN. This may be due to the complex magnetic structure of NdAlGe, which undergoes a series of metamagnetic transitions in an external magnetic field, while SmAlGe shows only a robust AFM order. In NdAlGe, the topological Hall effect (THE) appears between the first and the second metamagnetic transitions for H ∥ c, while it is absent in SmAlGe. Such THE in NdAlGe is most likely attributed to the field-induced topological spin textures. The longitudinal muon-spin relaxation rate λL, diverges near the AFM order, followed by a clear drop at T < TN. In the magnetically ordered state, spin fluctuations are significantly stronger in NdAlGe than in SmAlGe. In general, our longitudinal-field μSR data indicate vigorous spin fluctuations in NdAlGe, thus providing valuable insights into the origin of THE and of the possible topological spin textures in REAl(Si,Ge) Weyl semimetals.

Entropy optimization in ternary hybrid nanofluid flow over a convectively heated bidirectional stretching sheet with Lorentz forces and viscous dissipation: A Cattaneo–Christov heat flux model

Bidirectional stretching sheet models can represent surfaces in heat exchangers where fluids flow under continuous deformation. Ternary hybrid nanofluids could be employed in these systems to increase heat transfer rates between fluids in heat exchangers and improve the efficiency of energy conversion processes. In this work, we explore the novel application of a ternary hybrid nanofluid (water with titanium dioxide, cobalt ferrite, and magnesium oxide nanoparticles) for enhanced heat transfer in heat exchangers modeled by a bidirectional stretching sheet. This approach offers a potential advancement over traditional nanofluids (with one or two nanoparticles). Furthermore, we present a comprehensive analysis that incorporates ohmic heating, Cattaneo–Christov heat flux, thermal radiation, viscous dissipation, and irreversibility. The governing equations are transformed into a system of nonlinear ordinary differential equations using appropriate similarity transformations and then solved using the bvp4c solver, a MATLAB built-in function. This study's findings reveal that the Eckert number and radiation parameter increase fluid temperature, while the thermal relaxation parameter leads to a reduction in the temperature of the fluid. It is detected that an increase in magnetic field parameter and volume fraction of [Formula: see text] results in a decline of the skin friction factors in both directions. It is revealed that there is a reduction in the Nusselt number with the rise in Eckert number ([Formula: see text]), and the same number declines at a rate of 0.8252 when [Formula: see text]. It is noticed that the skin friction coefficient declines at a rate of 0.62179204 (in case of x-direction) and 0.621791816 (in case of y-direction), respectively, when the values of magnetic field parameter lie between 0 and 3.5. Furthermore, it is noticed that an upsurge in thermal relaxation parameter results in a fall in the temperature of the fluid.

Assessing the Efficacy of Hybrid Nanofluid within a Non-Newtonian Reiner-Philippoff Model, Incorporating MHD and Thermal Radiation Past a Stretching/Shrinking Sheet

Hybrid nanofluids are making waves in industry because of their superior thermal efficiency and innovative designs. Their usefulness extends to many other sectors and domains of study. The volume fraction of Cu–Al2O3 and Ag–TiO2 hybrid nanoparticles in nanofluids will be studied to determine their impact on heat transmission and flow. The study also considers the presence of heat radiation, a magnetic field, and other relevant factors. The non-Newtonian Reiner-Philippoff model was employed to investigate the flow's shear thickening and thinning properties. The combined effects of suction and a contracting surface form a boundary for the surface. The reduced partial differential equation (PDE) is solved using the MATLAB tool bvp4c following the similarity transformation method. The shrinking sheet shows that the dual solution converges to critical points, and the stability study verified that the first one is stable and physically trustworthy. The mathematical modelling developed for nanofluid hybrids has exhibited a significant impact on the overall heat flow, which can be attributed to the variation in the parameters that influence it. Enhancement in magnetic parameter (+2.26%), suction (+2.99%), and nanoparticle fractional volume of metal oxide (+0.4%) were identified as factors that accelerated heat transfer to the pioneering Cu–Al2O3 nanofluid hybrid, according to the study. Besides, the second hybrid of Ag–TiO2 nanofluids had a reduced heat transfer rate due to changes in thermal radiation (-2.14%) and Reiner parameter-Philippoff fluid (-0.14%).

Biological and Procedural Predictors of Outcome in the Stroke Preclinical Assessment Network (SPAN) Trial.

The SPAN trial (Stroke Preclinical Assessment Network) is the largest preclinical study testing acute stroke interventions in experimental focal cerebral ischemia using endovascular filament middle cerebral artery occlusion (MCAo). Besides testing interventions against controls, the prospective design captured numerous biological and procedural variables, highlighting the enormous heterogeneity introduced by the multicenter structure that might influence stroke outcomes. Here, we leveraged the unprecedented sample size achieved by the SPAN trial and the prospective design to identify the biological and procedural variables that affect experimental stroke outcomes in transient endovascular filament MCAo. The study cohort included all mice enrolled and randomized in the SPAN trial (N=1789). Mice were subjected to 60-minute MCAo and followed for a month. Thirteen biological and procedural independent variables and 4 functional (weight loss and 4-point neuroscore on days 1 and 2, corner test on days 7 and 28, and mortality) and 3 tissue (day 2, magnetic resonance imaging infarct volumes and swelling; day 30, magnetic resonance imaging tissue loss) outcome variables were prospectively captured. Multivariable regression with stepwise elimination was used to identify the predictors and their effect sizes. Older age, active circadian stage at MCAo, and thinner and longer filament silicone tips predicted higher mortality. Older age, larger body weight, longer anesthesia duration, and longer filament tips predicted worse neuroscores, while high-fat diet and blood flow monitoring predicted milder neuroscores. Older age and a high-fat diet predicted worse corner test performance. While shorter filament tips predicted more ipsiversive turning, longer filament tips appeared to predict contraversive turning. Age, sex, and weight interacted when predicting the infarct volume. Older age was associated with smaller infarcts on day 2 magnetic resonance imaging, especially in animals with larger body weights; this association was most conspicuous in females. High-fat diet also predicted smaller infarcts. In contrast, the use of cerebral blood flow monitoring and more severe cerebral blood flow drop during MCAo, longer anesthesia, and longer filament tips all predicted larger infarcts. Bivariate analyses among the dependent variables highlighted a disconnect between tissue and functional outcomes. Our analyses identified variables affecting endovascular filament MCAo outcome, an experimental stroke model used worldwide. Multiple regression refuted some commonly reported predictors and revealed previously unrecognized associations. Given the multicenter prospective design that represents a sampling of real-world conditions, the degree of heterogeneity mimicking clinical trials, the large number of predictors adjusted for in the multivariable model, and the large sample size, we think this is the most definitive analysis of the predictors of preclinical stroke outcome to date. Future multicenter experimental stroke trials should standardize or at least ensure a balanced representation of the biological and procedural variables identified herein as potential confounders.

Modeling and Study of Different Magnet Topologies in Rotor of Low Rating IPMSMs

A study and performance analysis of magnet positions in different topology on the surface of rotor in permanent magnet synchronous motors (PMSMs) based on finite element method is observed here. A 3-phase interior PMSM is numerically simulated with ANSYS Maxwell 2018.1. Differently positioned permanent magnets improve the performance of PMSMs. Apart from handling nonlinear equations, FEM is used for simulation. ANSYS is used to analyze PMSM performance under variable conditions. This proposal examines a three-phase, 0.55 kW PMSM at 220 V, 50 Hz. Here rotor topologies of five types, namely, (i) spoke/tangential, (ii) saturable bridge / u-shape, (iii) V-shape, (iv) radial, and (v) segmented bridge permanent magnet rotor are taken for observation. The motive of this study is to analyze the performance of PMSMs in different rotor designs with different magnet positions. All topologies have been modeled and simulated with ANSYS. Each topology is compared in terms of electromagnetic and mechanical parameters. The 2D model is used to model the distribution of magnetic fields and the performance of operating parameters under transient and steady-state conditions. Magnetic flux, and efficiency are heavily influenced by the rotor shape with the volume of magnet. A study of radial force distribution and mechanical stress across rotor surface is also discussed. Motor performance is affected by the design of PMs.

Comparison of patients with chronic and episodic migraine with healthy individuals by brain volume and cognitive functions

Objectives: Migraine is a complex neurological disease. In addition to headache, individuals with migraine may develop structural changes inside the brain and cognitive impairment. There is increased evidence associated with impairments in brain volume and cognitive functions in patients with migraine. The present study aimed to investigate the impairment in memory function in individuals with migraine using brain magnetic resonance imaging, volume measurement, and neuropsychological tests. Methods: The study included 20 patients with episodic migraine, 20 patients with chronic migraine, and 20 healthy controls. Subcortical volumes of all participants were measured by FreeSurfer, an automatic segmentation method. The Wechsler Memory Scale-Revised Form (WMS-R), Stroop test, Raven’s Standard Progressive Matrices, Verbal Fluency Test, and Lines Orientation Test were applied in all the study participants. Results: Putamen volume decreased as migraine duration increased, and subcortical gray matter, left cerebellar cortex, and bilateral thalamus volumes were lower in the chronic and episodic group compared to the control group, bilateral putamen and right cerebellar cortex volumes were lower in patients with chronic migraine compared to patients in episodic migraine and control groups. Upon neuropsychological examination, delayed memory was affected as the duration of migraine increased, and there was impairment in patients with chronic migraine upon fluency tests and mental control tests. Conclusions: Changes in subcortical volume and cognitive effects in patients with migraine raise questions about whether migraine qualifies as a benign disease. Structural changes and cognitive impairment may contribute to migraine-associated disability, and therefore, these causalities should be investigated by future studies. Silent infarcts, white matter damage, and cortical spreading depression, which occur in migraine cases, may be associated with subcortical volume changes and thus, cognitive effects. In the context, studies with larger samples to achieve a better understanding are needed.

Synthetic magnetic resonance-based relaxometry and brain volume: cutoff values for predicting neurocognitive outcomes in very preterm infants

BackgroundEarly neurorehabilitation can enhance neurocognitive outcomes in very preterm infants (<32 weeks), and conventional magnetic resonance imaging (MRI) is commonly used to assess neonatal brain injury; however, the predictive value for neurodevelopmental delay is limited. Timely predictive quantitative biomarkers are needed to improve early identification and management of infants at risk of neurodevelopmental delay.ObjectiveTo evaluate the potential of quantitative synthetic MRI measurements at term-equivalent age as predictive biomarkers of neurodevelopmental impairment and establish practical cutoff values to guide clinical decision-making.Materials and methodsThis retrospective study included 93 very preterm infants who underwent synthetic MRI at term-equivalent age between January 2017 and September 2020. Clinical outcomes were assessed using the Bayley-III scale of infant development (mean age 2.1 years). The predictive value for impaired development was analyzed using receiver operating characteristic curves for synthetic MRI-based volumetry and T1 and T2 relaxation measurements.ResultsThe T1 relaxation time in the posterior limb of the internal capsule was a potent predictor of severe (sensitivity, 92%; specificity, 80%; area under the curve (AUC), 0.91) and mild or severe (AUC, 0.75) developmental impairment. T2 relaxation time in the posterior limb of the internal capsule was a significant predictor of severe impairment (AUC, 0.76), whereas the brain parenchymal volume was a significant predictor of severe (AUC, 0.72) and mild or severe impairment (AUC, 0.71) outperforming the reported qualitative MRI scores (AUC, 0.66).ConclusionThe proposed cutoff values for T1 relaxation time in the posterior limb of the internal capsule and for total brain volume measurements, derived from synthetic MRI, show promise as predictors of both mild and severe neurodevelopmental impairment in very preterm infants.Graphical

Numerical simulation and mathematical modeling of biomechanical stress distribution in poroelastic tumor tissue via magnetic field and bio-ferro-fluid

Based on scientific evidence, it seems that bio-magnetic systems can change the process of cancer cell death by affecting the distribution of pressure and mechanical stress in the tumor tissue. Already most of the research has been done experimentally and few mathematical modeling and numerical simulations have been done to investigate the relationship between the magnetic parameters and the mechanical stress of the tumor tissue. This is despite the fact that in order to be able to make new equipment with the help of medical engineering methods, it is definitely necessary that the mathematics governing the problem and changes in the effective magnetic parameters (such as the shape of the magnetic source, magnetic flux density, magnetic source distance and ferro-fluid volume fraction) should be studied as much as possible. In this research, using numerical simulation and mathematical modeling, four common geometrical shapes (rectangular and circular) of the static magnetic field source were used to investigate the relationship between the change of the effective magnetic parameters and the mechanical stress created in the tumor tissue. The results of this research showed that when the magnetic flux density and ferro-fluid volume fraction and also the distance between the magnet and the tissue are kept constant, as well as without spending any extra energy, for a rectangular magnet, just by changing the way the source is placed on the tissue, the average biomechanical stress inside the tumor tissue causes a 25 % change. Also, for a circular magnet, just by doubling the radius of the magnet, the average biomechanical stress inside the tumor tissue causes a 73 % change.

Effects of magnetic fields and nanoparticle concentration on hydro-thermal performance of a surface enhanced microchannel

This article numerically investigates fluid flow and heat transfer in plain wall (PWMC) and oblique fin (OFMC) microchannels under varying magnetic fields using water- Al2O3 nanofluid as a working fluid. Effects of magnetic flux (Hartmann number, Ha = 0–30), fluid velocity (Reynolds number, Re = 100–500), and nanoparticle volume fraction (ϕ = 0%–2%) on the overall thermo-fluid performance are analyzed. Magnetic fields can significantly improve the heat transfer in OFMC in a higher rate compared to the PWMC. Also, there is a less increment on the pressure drop in the OFMC in comparison to PWMC. In addition, individual, as well as combined effect of Joule and viscous heating on the thermo-fluid performance is investigated. Due to the combined effect of Joule and viscous heating, the Performance Evaluation Criterion (PEC) in OFMC can be improved by 21%. However, the PEC in OFMC can be enhanced by 55% without considering the combined effect. The detailed characteristics flow and heat transfer are also studied by analyzing the velocity contours, isotherms, streamlines, friction factors, and Nusselt numbers. The present study concludes the importance of consideration of Joule and viscous heating for an accurate modeling, where the viscous heating plays the dominant role. The present findings can be instrumental in enhancing the performance of micro heat sinks to optimize hydrothermal performance in high powered motors, nuclear fusion reactors etc., where magnetic field is present.

Advanced modeling of segmented Halbach cylinder for ironless brushless permanent-magnet two-phase motor

Compared with conventional permanent magnet (PM) cylinders, Halbach magnet cylinders have the advantage of strengthening the magnetic field on one side and canceling the field on the other side of the magnet structure. Outer-rotor radial-flux brushless ironless PM machines using a Halbach cylinder, therefore, can have a higher torque density compared with the ironless PM machines using a conventional magnet cylinder with the same magnet and coil volume and same air gap. For outer-rotor Halbach cylinder motors, existing designs usually take advantage of the fundamental harmonics of the magnetic field to obtain a linear toque model and to avoid the torque ripples from the higher-order field harmonics. To achieve this, the Lorentz coils must be placed where the fundamental harmonics of the field is dominant and the higher order harmonics can be negligible. With this, the coils should be sufficiently far from the magnet cylinder’s surface. However, how far the coils should be (from the magnet) is not clarified from the reported designs. To provide guidance on where to optimally place the Lorentz coils and to make the best use of the Halbach cylinders, there is a critical need for a simple but comprehensive analysis to find out all the field harmonics everywhere for both the ideal and segmented Halbach cylinders. This work is to provide that analysis.

Subcortical Brain Volumes and Neurocognitive Function in Children With Perinatal HIV Exposure: A Population-Based Cohort Study in South Africa.

Children who are HIV-exposed and uninfected (HEU) are at risk for early neurodevelopmental impairment. Smaller basal ganglia nuclei have been reported in neonates who are HEU compared to HIV-unexposed (HU); however, neuroimaging studies outside infancy are scarce. We examined subcortical brain structures and associations with neurocognition in children who are HEU. This neuroimaging study was nested within the Drakenstein Child Health Study birth cohort in South Africa. We compared (T1-weighted) magnetic resonance imaging-derived subcortical brain volumes between children who were HEU (n = 70) and HU (n = 92) at age 2-3 years using linear regression. Brain volumes were correlated with neurodevelopmental outcomes measured with the Bayley Scales of Infant and Toddler Development III. Compared to HU children, on average children who were HEU had 3% lower subcortical grey matter volumes. Analyses of individual structures found smaller volume of the putamen nucleus in the basal ganglia (-5% difference, P = .016) and the hippocampus (-3% difference, P = .044), which held on adjustment for potential confounders (P < .05). Maternal viremia and lower CD4 count in pregnancy were associated with smaller child putamen volumes. Children who were HEU had lower language scores than HU; putamen and hippocampus volumes were positively correlated with language outcomes. Overall, children who are HEU had a pattern of smaller subcortical volumes in the basal ganglia and hippocampal regions compared to HU children, which correlated with language function. Findings suggest that optimizing maternal perinatal HIV care is important for child brain development. Further studies are needed to investigate underlying mechanisms and long-term outcomes.

Numerical solution of an unsteady nanofluid flow with magnetic, endothermic reaction, viscous dissipation, and solid volume fraction effects on the exponentially moving vertical plate

This study analyzes the unsteady nanofluid flow phenomenon adjacent to an accelerating vertical plate under the influence of magnetic fields, chemical reactions,viscous dissipation and solid volume fraction factors. The analysis motivates the understanding of the behavior of complex fluids to improve existing processes and develop new technologies. The finite difference technique, with the help of the boundary and initial conditions, was employed for the numerical result. The numerical solutions were graphically analyzed through MATLAB software. The results reveal intricate flow behaviors, including the influence of magnetic fields and solid volume fraction in reducing the velocity of the nanofluid. Interestingly, a magnetic field drops the temperature of the nanofluid, which can be observed in a particular case. The chemical reaction is found to absorb the heat, leading to a decline in the velocity and concentration due to temperature drop and solute destruction factors. The viscous dissipation raises the temperature of the nanofluid, but the heat sink affects the temperature oppositely. The Soret number essentially quantifies the phenomenon known as thermophoresis, where solutes concentrate more in cooler regions. This analysis provides valuable insights into the design and optimization of systems involving nanofluids subjected to external magnetic fields, with implications for various engineering applications such as thermal management systems and nanofluid-based heat exchangers.