•Thermal response of biological samples subjected to focused ultrasound waves.•Hyperbolic heat conduction models.•Non-Fourier effects.•Temperature distributions and thermal dosage.
The present study ...is concerned with the numerical analysis of the non-Fourier heat transfer phenomena in biological tissue samples subjected to high intensity focused ultrasound (HIFU). Due to the inherent non-homogeneous nature of biological samples, the well-known Pennes bioheat equation (PBHTE) is not strictly suitable for correctly predicting the temperature distribution in the tissue medium subjected to HIFU. In this respect, thermal wave model of bioheat transfer (TWMBT), which takes into account the finite propagation speed of thermal front, plays an important role in describing the observed wave-like behavior of heat transfer in biological tissue medium. The temperature profiles obtained from TWMBT show the presence of oscillations during the process of diffusion of thermal wave after reaching its maximum peak, depending upon the corresponding relaxation time. Results show that the thermal dosage with finite value of relaxation time gives lesser heat-affected area compared to the dosage calculated by considering the infinite propagation of thermal front as in the case of the conventional Fourier model. These observations make the present study important as otherwise, the target area is prone to remain under insufficiently heated conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
•Analytical solution of the non-Fourier bio heat transfer equation.•Finite integral transform.•Time independent/dependent boundary conditions.•Coupling of the transient RTE and non-Fourier heat ...conduction models.•Thermal analysis of laser-irradiated biological tissue phantoms.
A finite integral transform (FIT)-based analytical solution to the dual phase lag (DPL) bio-heat transfer equation has been developed. One of the potential applications of this analytical approach is in the field of photo-thermal therapy, wherein the interest lies in determining the thermal response of laser-irradiated biological samples. In order to demonstrate the applicability of the generalized analytical solutions, three problems have been formulated: (1) time independent boundary conditions (constant surface temperature heating), (2) time dependent boundary conditions (medium subjected to sinusoidal surface heating), and (3) biological tissue phantoms subjected to short-pulse laser irradiation. In the context of the case study involving biological tissue phantoms, the FIT-based analytical solutions of Fourier, as well as non-Fourier, heat conduction equations have been coupled with a numerical solution of the transient form of the radiative transfer equation (RTE) to determine the resultant temperature distribution. Performance of the FIT-based approach has been assessed by comparing the results of the present study with those reported in the literature. A comparison of DPL-based analytical solutions with those obtained using the conventional Fourier and hyperbolic heat conduction models has been presented. The relative influence of relaxation times associated with the temperature gradients (τT) and heat flux (τq) on the resultant thermal profiles has also been discussed. To the best of the knowledge of the authors, the present study is the first successful attempt at developing complete FIT-based analytical solution(s) of non-Fourier heat conduction equation(s), which have subsequently been coupled with numerical solutions of the transient form of the RTE. The work finds its importance in a range of areas such as material processing, photo-thermal therapy, etc.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The interactions of an immiscible droplet impinging on liquid pools bear significant implications across a wide array of applications, as well as in natural phenomena. In this paper, the dynamics ...associated with an immiscible droplet impinging on a liquid pool/film of varying depths have been elucidated. The study encompasses the impact of silicone oil droplets of four different viscosities (1, 10, 100 and 1000 cSt) upon a water pool of three non-dimensional pool heights
h
*
= 1, 2.5 and 5. The phenomenon of droplet impact at two Weber numbers (
We
= 50 and 100) is captured through high-speed videography. The dynamics of impingement, associated with the immiscible liquid combination, are delineated by employing Mask R-CNN machine learning (ML) model. To the best of our knowledge, this study is among the first to apply ML to this complex fluid phenomenon, offering insights into the physics and potential applications in multiphase flows. ML model-generated masks are used to quantify the dynamics of various cavity parameters. Further insights into the phenomena have been developed through a detailed energy analysis carried out pre- and post-impact. The performance of ML model is compared with the manually annotated images, exhibiting impressive level of agreement. Results reveal that during the cavity formation phase, low-viscosity droplets conform to the cavity shape during their descend into the pool. In contrast, high viscosity droplets maintain their shape during cavity formation, showing pinning at the oil–water interface. Energy analysis shows better energy transfer from droplet to the cavity for low-viscosity droplets (> 90%), while less than 50% of the impact energy is transferred for higher viscosity droplets.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Delhi is one of the most polluted cities worldwide and a comprehensive understanding and deeper insight into the air pollution and its sources is of high importance. We report 5 months of highly ...time-resolved measurements of non-refractory PM2.5 and black carbon (BC). Additionally, source apportionment based on positive matrix factorization (PMF) of the organic aerosol (OA) fraction is presented. The highest pollution levels are observed during winter in December/January. During that time, also uniquely high chloride concentrations are measured, which are sometimes even the most dominant NR-species in the morning hours. With increasing temperature, the total PM2.5 concentration decreases steadily, whereas the chloride concentrations decrease sharply. The concentrations measured in May are roughly 6 times lower than in December/January. PMF analysis resolves two primary factors, namely hydrocarbon-like (traffic-related) OA (HOA) and solid fuel combustion OA (SFC-OA), and one or two secondary factors depending on the season. The uncertainties of the PMF analysis are assessed by combining the random a-value approach and the bootstrap resampling technique of the PMF input. The uncertainties for the resolved factors range from ±18% to ±19% for HOA, ±7% to ±19% for SFC-OA and ±6 % to ±11% for the OOAs. The average correlation of HOA with equivalent black carbon from traffic (eBCtr) is R2 = 0.40, while SFC-OA has a correlation of R2 = 0.78 with equivalent black carbon from solid fuel combustion (eBCsf). Anthracene (m/z 178) and pyrene (m/z 202) (PAHs) are mostly explained by SFC-OA and follow its diurnal trend (R2 = 0.98 and R2 = 0.97). The secondary oxygenated aerosols are dominant during daytime. The average contribution during the afternoon hours (1 pm–5 pm) is 59% to the total OA mass, with contributions up to 96% in May. In contrast, the primary sources are more important during nighttime: the mean nightly contribution (22 pm–3 am) to the total OA mass is 48%, with contributions up to 88% during some episodes in April.
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•Over 65% of the daily PM2.5 concentrations exceed the national air quality standard.•Exceptionally high chloride contribution during early mornings in the cold period•Significant solid fuel combustion contribution throughout the full campaign•PMF uncertainty assessment
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Abstract
The present work reports real-time observations of the phenomena of partial crystallization of one of the glass-forming materials, namely enstatite (MgSiO
3
) from its supercooled liquid ...droplet. Initially, the molten droplet has been held under purely non-contact conditions using the aerodynamic levitation technique. The desired levels of undercooling have been achieved by deliberately making the levitated molten droplet touch a thin molybdenum wire and hence to initiate heterogeneous nucleation from the point of contact. Influence of thermal parameters like undercooling, cooling rates and recalescence on the process of crystallization is investigated. To understand and report the morphological properties and extent of crystallinity, the solidified enstatite samples have been characterized using optical/scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively, which confirmed the formation of partially crystallized enstatite spherules and fully glass spherules. XRD showed sharp peaks of enstatite, which confirm crystallinity and a halo profile confirms the amorphous phase of enstatite. Based on the observations of several experiments, we propose the effect of thermal parameters such as levels of undercooling and recalescence on the partial crystallization, as well as partial glass formation from the initially molten droplets of enstatite composition.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
•Single bubble-based nucleate pool boiling under saturated bulk conditions.•Rainbow schlieren-based non-intrusive measurements.•Direct visualization of phenomena such as bubble nucleation and its ...growth, scavenging of super heat layer etc.•Plausible explanations of mechanisms governing the bubble dynamics.
Real time non-intrusive diagnostics of thermal gradients around a single vapor bubble in isolated nucleate pool boiling with water as the working fluid have been presented. Direct visualization of transient evolution of temperature gradients in the vicinity of the heated substrate and around the single bubble as it undergoes various sub-processes has been performed using rainbow schlieren deflectometry. Boiling experiments have been conducted under saturated conditions. Results have been presented in the form of two-dimensional rainbow schlieren images wherein the degree of color re-distribution gives a direct measure of the strength of thermal gradients. Through the real time experimental images, various sub-processes/phenomena associated with boiling heat transfer such as development of superheat layer in the vicinity of the heated substrate, inception and further growth of the vapor bubble followed by scavenging of the superheat layer as the vapor bubble departs into the bulk fluid have been discussed. The profiles of hue distribution near the triple contact line brought out the presence of near stagnant fluid zone in which the heat transfer phenomenon was seen to be primarily diffusion-dominated. Beyond this narrow region, significant bulk fluid movement was observed on the basis of the spatial distributions of hue values recorded in the form of real time schlieren images. The experiments further revealed an instantaneous localized bending of the superheat layer as the bubble leaves the heater surface and subsequent shedding of the wake vortices from the edges of the departing bubble as it moves upwards in the bulk fluid.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Asthma, a chronic respiratory disease is characterized by airway inflammation, remodelling, airflow limitation and hyperresponsiveness. At present, it is considered as an umbrella diagnosis ...consisting several variable clinical presentations (phenotypes) and distinct pathophysiological mechanisms (endotypes). Recent evidence suggests that oxidative stress participates in airway inflammation and remodelling in chronic asthma. Opioids resembled by group of regulatory peptides have proven to act as an immunomodulator. β-Endorphin a natural and potent endogenous morphine produced in the anterior pituitary gland play role in pain modulation. Therapeutic strategy of many opioids including β-Endorphin as an anti‑inflammatory and antioxidative agent has not been yet explored despite its promising analgesic effects. This is the first study to reveal the role of β-Endorphin in regulating airway inflammation, cellular apoptosis, and oxidative stress via Nrf-2 in an experimental asthmatic model. Asthma was generated in balb/c mice by sensitizing with 1% Toulene Diisocyanate on day 0, 7, 14 and 21 and challenging with 2.5% Toulene Diisocyanate from day 22 to 51 (on every alternate day) through intranasal route. β-Endorphin (5 µg/kg) was administered through the nasal route 1 h prior to sensitization and challenge. The effect of β-Endorphin on pulmonary inflammation and redox status along with parameters of oxidative stress were evaluated. We found that pre-treatment of β-Endorphin significantly reduced inflammatory infiltration in lung tissue and cell counts in bronchoalveolar lavage fluid. Also, pre-treatment of β-Endorphin reduced reactive oxygen species, Myeloperoxidase, Nitric Oxide, Protein and protein carbonylation, Glutathione Reductase, Malondialdehyde, IFN-γ, and TNF-α. Reversely, β-Endorphin significantly increased Superoxide dismutase, Catalase, glutathione, Glutathione-S-Transferase, and activation of NF-E2-related factor 2 (Nrf-2) via Kelch-like ECH-associated protein 1 (Keap1), independent pathway in the lung restoring architectural alveolar and bronchial changes. The present findings reveal the therapeutic potency of β-END in regulating asthma by Keap-1 independent regulation of Nrf-2 activity. The present findings reveal the therapeutic potency of β-Endorphin in regulating asthma.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The Brazil nut effect (BNE) is a counter-intuitive process of segregation of a large object inside a vibrated granular medium (GM), which has been studied widely by subjecting GMs to various kinds of ...shears and vibrations. In this article, we report a new kind of BNE which occurs as a consequence of granular fluctuations induced by microbe-generated gas bubbles. We call it the 'microbial Brazil nut effect'. The paper demonstrates microbial BNE for a bidisperse granular mixture as well as for intruder segregation. Furthermore, using X-ray μCT and a simple scaling argument for segregation velocity, the paper clarifies the transport mechanics of an intruder inside a bubbly granular bed. We think the reported phenomenon should be ubiquitous in the microbe-populated wet sandy floors of waterbodies and may have some implication on the distribution of material near the floors.
The work reports a new kind of Brazil nut effect (a non-intuitive granular segregation phenomenon) which occurs due bubbles that are produced by buried microbes inside a completely submerged granular bed.
•Detailed PIV study on pulse jet over a wide range of parameters; among the first studies.•Length of fully developed zone and vortex size found to depend on frequency of pulsation.•Formation ...frequency of vortices increases and shifts towards the nozzle with pulsation.•The optimal Strouhal number for mixing is 0.44 for Reynolds number 3300–7500.•A rapid change in conditional velocity and vorticity occurs across turbulent/non-turbulent interface.
Pulsating jets can be more useful for enhancing mixing and heat transfer than steady jets; however, their flow physics is still not clear. In this work, particle image velocimetry based measurements have been undertaken to investigate the flow structure and mixing characteristics of axisymmetric pulsating jets. This experimental study deals with flow characterization of 20mm diameter of axisymmetric submerged water jet over a wide range of test parameters. The purpose of this study is to understand the influence of frequency and amplitude on the flow characteristics, and the characteristics of turbulent/non turbulent (T/NT) interface of a pulsating jet. The flow characteristics across the T/NT interface has been compared for potential core, transition zone and fully developed zone. The introduction of pulsation results in widening of the jet and shortening of the potential core length as compared to steady jets. It is also observed that shear layer in pulsating jet oscillates with lower frequency as compared to the jet frequency, while the amplitude depends on the location in the flow field. Further, entrainment and mixing of surrounding fluid increases up to an optimal frequency. These results should eventually lead to a better understanding of the physical phenomena responsible for enhanced mixing and heat transfer in pulsating jets.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
Oxidative stress and inflammation are hypothesised as the main contributor for Chronic Obstructive Pulmonary Disease (COPD). Cigarette smoke (CS), a major cause of COPD leads to inflammation ...resulting in recruitment of neutrophils and macrophages which are rich sources of oxidants. Activation of these cells produces excess oxidants and depletes antioxidants resulting in stress. Presently, effective drug for COPD is limited; therefore, novel compounds from natural sources, including plants are under exploration. The present study aims to investigate the protective effect of Ocimum sanctum leaf extract (OLE) in CS - induced model of COPD. Exposure to CS was performed thrice a week for 8 weeks and OLE (200 mg/kg and 400 mg/kg) was administered an hour before CS exposure. Control group (negative control) were exposed to ambient air while COPD group was exposed to CS (positive control). Administration of OLE doses reduced inflammation, decreased oxidant concentration and increased antioxidant concentration (p < 0.01). Molecular docking studies between the major phytocompounds of OLE (Eugenol, Cyclohexane and Caryophyllene) and antioxidant enzymes Superoxide dismutase (SOD), Catalase, Glutathione peroxidase (GPx), Glutathione reductase (GR) and Glutathione S Transferase (GST) showed strong binding interaction in terms of binding energy. In vivo and in silico findings for the first time indicates that OLE extract significantly alleviates oxidative stress by its potent free radical scavenging property and strong interaction with antioxidant enzymes. OLE extract may prove to be a therapeutic option for COPD prevention and treatment.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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