Arindam Bit

The design, development, and validation of a physiological pulsatile cardiovascular flow simulator to analyse the hemodynamic behaviour in stenosed blood vessels is studied. The simulator consists of an innovative arrangement of peristaltic pumps to reproduce realistic arterial pulse waveforms, incorporating the higher harmonic components of physiological flow. Experimental investigations were performed using a laser Doppler velocimetry (LDV) system to evaluate the axial velocity, the wall shear stress (WSS), the turbulence intensity, and related flow parameters in vessels with varying stenosis severities (12.5, 25, and 50%). The observed results indicated that stenosis severity critically influences the flow structure, with higher blockages inducing significant velocity skewness, increased oscillatory WSS, and sustained post-stenotic disturbances. Flow reversal, vortex formation, and prolonged laminar recovery were observed downstream of severe stenoses. Comparative analyses with theoretical models validated the experimental accuracy, particularly in central and mid-radial zones. The study also introduced a method for determining the oscillatory shear index (OSI) and the relative residence time (RRT), identifying regions susceptible to atherogenesis. The simulator provides a reliable platform for replicating in vivo-like flow patterns in vitro, providing the valuable insights into the disease progression mechanisms and enabling future development of diagnostic and interventional strategies in cardiovascular medicine.

Microchannels possess enhanced thermal convection due to its greater surface-to-volume ratio. Empirical evidence depicts that flows in microchannels are an effective means of dissipating heat flux from small, localized heat source points over a larger surface area. It formulates symmetric heat distribution, holding promising applications for tiny biological regulators. The size, shape, structures, and density distribution of heat sources in microchannels greatly influence heat distribution, whereas the medium of heat transfer was found to have a marginal effect in the case of a minute viscosity difference between two fluids. The thermo-fluid coupling effects in microchannels are highlighted to evaluate the modulation of temperature and variations of velocity within the working fluid. The effect of heat distributions on fluid flow in the presence of micro-fins within a microchannel was studied numerically in the presence of both Newtonian and non-Newtonian fluid, while considering the case of two different fin configuration conditions, i.e., decreasing inter-fin distance with decreasing fin height, and increasing inter-fin distance with increasing fin height. The flow domain was considered to have inlet boundary conditions: pulsatile flow (time varying inlet velocity and fin's temperature). Whereas, fins of different shapes: rectangular, elliptical, and conical shapes, were considered in the study. The local Nusselt number was found to be influenced by the effective surface area and boundary layer thickness linked to the varied micro-fin structures, as well as the pressure drop caused by the varying fin separation lengths. In the case of decreasing inter-fin distance, the highest Nu was found to be 30.41 and the lowest Nu was found to be 7.19 for non-Newtonian fluid for conical fins. In the case of increasing inter-fin distance, the highest Nu was found to be 30.40 and the lowest Nu was found to be 7.20 for non-Newtonian fluid for conical fins.

Objectives: Emotional task execution is a mid-level cognitive activity of the human brain. Higher cognitive load causes parasympathetic exertion. This hinders the formation of an exact execution pathway for the exposed emotional task. The human mind redistributes parasympathetic exertion by regulating peripheral pressure. This aids in allocating cognitive load in the brain. Materials and Methods: Here, the relationship between foot pressure and the cognitive burden of attention in the human brain was investigated while performing an emotional task under the effect of an attentional paradigm. Results: The results indicated gender differences in attention and emotion processing, suggesting that females have responded to local attentional stimuli along with emotional stimuli more quickly and accurately than males. Electroencephalography (EEG) results revealed that the early sensory components of N100 and P100 were modulated by global attention and happy emotion. Further, we found that global attention and happy emotion were marked by increased theta and alpha band oscillation networks. Conclusion: This study explores the neurocognitive mechanisms that improve the ability to manage conflicting tasks involving emotion–attention alongside cognitive load. The findings contribute to creating a novel approach to enhancing cognitive function associated with attentional stimuli.

Attentional paradigm can have a significant influence on the processing and experience of positive and negative emotions. Attentional mechanism refers to the tendency to selectively attend to a particular stimulus while ignoring others. In the context of emotions, individuals may exhibit attentional biases towards either positive or negative emotional stimuli. By directing attention towards a specific stimulus, individuals can modulate their emotional responses. When attention is directed towards negative or threatening stimuli, it can intensify negative emotions such as fear, sadness, anger and anxiety. Conversely, directing attention away from negative stimuli can reduce emotional reactivity and promote emotional regulation. Similarly, paying attention to positive stimuli can amplify positive emotions and facilitate positive emotional experiences. Attentional paradigms are also responsible for cognitive appraisal of emotional stimuli. The allocation of attention can shape how emotional stimuli are evaluated and categorized, influencing the subsequent emotional response. Since the relationship between attention and emotions is complex and can vary across individuals and contexts, it is important to understand the underlying cognitive neural dynamics of the same. Custom rank allocation model (CRAM) was used to decode the underlying neural dynamics of cognitive and emotional resource sharing through the non-significant EEG channels. During the main effect of global–local (GL), CRAM ranks and scores indicated that the EEG channels C4, PZ, OZ, and P4 were found to be the most non-significant channels. Similarly, CRAM ranks and scores of the interaction effects between global–local and positive emotion-negative emotion and the interaction effects between global–local and frequent-deviant-equal indicated midline central EEG channels CZ, PZ, FZ and OZ to be the main contributor of the cognitive and emotional resources to others. Understanding the dynamics of attention-emotion conflicts with reference to significant and non-significant channels is important to gain insights into the complex computational interplay between attention and emotion, leading to a deeper understanding of human cognition and emotion regulation.

The analysis of degradation in the presence of cell death and migration is a critical aspect of research in various biological fields, such as tissue engineering, regenerative medicine, and disease pathology. In present study, numerical study of degradation of scaffold were performed in present of cells, cell apoptosis and cell migration. A poly electrolyte complex (PEC) silk fibroin scaffold was used for degradation study. Degradation study in the presence of cells and migration were performed at fixed pH concentration 7.2. Similarly, degradation study of scaffold were performed at different pH cell apoptosis. A transient analysis of scaffold was evaluated in COMSOL 5.5 in presence of cryogenic temperature at different temperature gradient. The parameters; temperature, stress, strain tensor and deformation gradient associated with the degradation of polyelectrolyte complex scaffold were evaluated. Result shows that in both geometries minimum temperature had been achieved as 230.051 K at point P4 in series view and parallel view and at a point P3 for cell migration study for −5 k min⁻¹ and −1 k min⁻¹, respectively. The maximum stress had been generated for 5.57 × 10⁷ N m⁻² for the temperature gradient of −2 K min⁻¹ at T cycle in the case of cell migration study. In contrast in series view the maximum stress 2.9 × 107 N m⁻² were observed at P4 which was higher as compare to P3. Similarly, for a parallel view, maximum stress (3.93 × 107 N m⁻²) was obtained for point P3. It had been observed that the maximum strain tensor 5.21 × 10⁻³, 5.15 × 10⁻³ and 5.26 × 10⁻³ was generated in series view at 230 k on a point P3 for − 1, −2 and −5 K min⁻¹, respectively. Similarly, the maximum strain tensor 8.16 × 10⁻³, 8.09 × 10⁻³ and 8.09 × 10⁻³ was generated in parallel view at 230 k on a point P3 for −1, −2 and −5 K min⁻¹, respectively. In the presence of cells, at a point P4 for temperature gradient of −1 and −2 K min⁻¹, it had been closed to the scaffold wall, which had a different temperature profile than the point P3 and scaffold comes to the contact with the cells. The analysis of PEC scaffold degradation in the presence of cells, including cell apoptosis and migration, offers significant insights into the relationship between scaffold properties, cell behaviour, and tissue regeneration.