Heat Transfer Model for Menorrhagia

Thermal balloon ablation is a modern non surgical procedure for the treatment of menorrhagia. It works on the principle of ablating the endometrial layer beyond a point of regeneration thereby reducing blood loss. Mathematical modelling of this procedure helps in improving accuracy of the treatment which reduces adverse affects of the procedure thereby making the procedure safer. Pennes bio-heat equation is used to calculate transient temperature in the uterine cavity. Thermal injury integral is used to calculate the irreversible thermal destruction of the uterine tissue. When thermal injury integral equals to or is greater than 1, the tissue is destroyed which prevents regeneration of the endometrium. The presented mathematical model is verified with the published experimental findings to check the validity of the model. The effect of overall convective heat transfer coefficient and balloon fluid temperature on tissue damage is studied. For an overall convective heat transfer coefficient above 2000Wm-2K-1, maximum depth of ablation at 87°C was 3.77mm. For higher fluid temperature, depth of ablation is found to increase. At a fluid temperature of 93°C, depth of ablation is found to be 4.39mm for an overall convective heat transfer coefficient 1000Wm-2K-1. The temperature at the surface of endometrium is found to increase with the increase in fluid temperature and also with the increase in overall convective heat transfer coefficient. The obtained results are valid in the absence of any pathological condition. In case of existing pathological conditions, the effects caused by them are also to be included. Thus, mathematical modelling involving convective heat losses is an effective tool to make thermal balloon procedure more accurate

Spontaneous imbibition dynamics in two-dimensional porous media : a generalized interacting multi-capillary model

The capillary bundle model, wherein the flow dynamics of a porous-medium is predicted from that of a bundle of independent cylindrical tubes/capillaries whose radii are distributed according to the medium's pore size distribution, has been used extensively. The model lacks interaction between the flow channels, thus fails at predicting complex flow configuration, including those involving two-phase flow. We propose here to predict spontaneous imbibition in quasi-two-dimensional (quasi-2D) porous-media from a model based on a planar bundle of interacting capillaries. The imbibition flow dynamics, particularly, breakthrough time, global wetting fluid saturation at breakthrough, and capillary carrying the leading meniscus are governed by the distribution of the capillaries' radii and their spatial arrangement. For an 20 interacting capillary system, the breakthrough time can be 39% smaller than that predicted by the classic, non-interacting, capillary-bundle-model of identical capillary radii distribution. We propose a stochastic approach to use this model of interacting capillaries for quantitative predictions. Using the capillary diameter distribution as that of the pore sizes in the target porous medium, and computing the average behavior of a randomly-chosen samples of such interacting-capillary-bundles with different spatial arrangements, we obtain predictions of the position in time of the bulk saturating front, and of that of the visible leading front, that agree well with measurements taken from the literature. This semi-analytical model is quick to run and provides fast predictions on one-dimensional spontaneous imbibition in porous-media whose porosity structure can reasonably be considered two-dimensional, e.g., paper, thin porous-media in general, or layered aquifers

A mixed methods study to assess the effectiveness of food-based interventions to prevent stunting among children under-five years in districts Thatta and Sujawal, Sindh province, Pakistan: study protocol

Background: Maternal and child malnutrition is widely prevalent in low and middle income countries. In Pakistan, widespread food insecurity and malnutrition are the main contributors to poor health, low survival rates and the loss of human capital development. The nutritional status trends among children exhibit a continuous deteriorating with rates of malnutrition exceeding the WHO critical threshold. With the high prevalence of maternal and child malnutrition, it is important to identify effective preventative approaches, especially for reducing stunting in children under-five years of age. The primary aim of this study is to assess the effectiveness of food-based interventions to prevent stunting in children under-five years. Methods: A mixed methods study design will be conducted to evaluate the effectiveness of food-based interventions to prevent stunting among children under-five years in districts Thatta and Sujawal, Sindh Province, Pakistan. The study will include cross sectional surveys, a community-based cluster randomized controlled trial and a process evaluation. The study participants will be pregnant women, lactating mothers and children under-five years. The cross-sectional surveys will be conducted with 7360 study participants at baseline and endline. For the randomized control trial, 5000 participants will be recruited and followed monthly for compliance of food-based supplements, dietary diversity, pregnancy outcomes, and maternal and child morbidity and mortality. Anthropometric measurements and hemoglobin levels will be measured at baseline, quarterly and at endline. The interventions will consist of locally produced lipid-based nutrient supplement (Wawamum) for children 6–23 months, micronutrient powders for children 24–59 months, and wheat soya blends for pregnant and lactating mothers. Government lady health workers will deliver interventions to participants. The effectiveness of the project will be measured in terms of the impact of the proposed interventions on stunting, nutritional status, micronutrient deficiencies, and other key indicators of the participants. The process evaluation will assess the acceptability, feasibility and potential barriers of project implementation through focus group discussions, key informant interviews and household surveys. Data analysis will be conducted using STATA version 12. Discussion: There is considerable evidence on the effectiveness of food-based interventions in managing stunting in developing countries. However, these studies do not account for the local environmental factors and widespread nutrient deficiencies in Pakistan. These studies are often conducted in controlled environments, where the results cannot be generalized to programs operating under field conditions. The findings of this study will provide sufficient evidence to develop policies and programs aimed to prevent stunting in children 6–59 months and to improve maternal and child health and growth outcomes in poor resource setting

Experimental study of miscible Rayleigh-Taylor convection in agranular porous medium

International audienceMore than 60% of greenhouse gas emissions are due to CO2 released from fossil fuels andindustrial processes [1]. It is expected that by 2035, the expected increase in CO2 emissions will be37.2 Gt/yr [2]. To reduce the resulting further adverse effects in climate changes, geologicalsequestration of CO2 provides an effective solution for carbon capture and storage (CCS) [2-4].Dissolution trapping of CO2 in deep saline aquifers is a trapping mechanism that allows for longterm storage. When CO2 is injected into the subsurface geological layers, the supercritical CO2(sCO2) dissolves into the aquifer’s aqueous solution positioned below. The formation of a layer ofCO2-enriched brine at the upper interface of the liquid domain results in unstable stratificationwhich evolves into gravitational convection [2-5].To evaluate the storage capacity and the efficiency of the trapping, it is necessary to understandthe dynamics of the instabilities and convection, and the affect of granular media properties onthem. To do so, we perform a 2D experimental study in a 3D granular medium and use Darcyscale simulations to complement our experimental findings [6]. Analog experiments areperformed by using two miscible fluids with a density contrast between them. In doing so wedecouple the gravitational instability process from the dissolution process; the latter is notmodeled in our experiment. We match the refractive index of the fluids to that of the granularmedium to allow for optical measurement of the concentration field. We observe that there issubstantial difference in convection development time scales between the experimental resultsand the Darcy scale simulations performed with the experimental macroscopic parameters(porosity, permeability, dispersivity lengths, density contrast). We attribute this to the role playedby pore scale heterogeneity of the velocity field, which cannot be predicted by Darcy scale models.This would suggest that Darcy scale simulations [2, 4,6] significantly overestimate the typical timescale of the convection.[1] Contribution of Working Group III to the Fifth Assessment Report of the IntergovernmentalPanel on Climate Change, IPCC 2014.[2] Emami-Meybodi, H., Hassanzadeh, H., Green, C. P., & Ennis-King, J. (2015). Convective dissolution of CO2 in saline aquifers: Progress in modeling and experiments. International Journalof Greenhouse Gas Control, 40, 238-266.[3] Bachu, S. (2008). CO2 storage in geological media: Role, means, status and barriers todeployment. Progress in energy and combustion science, 34(2), 254-273.[4] Pau, G. S., Bell, J. B., Pruess, K., Almgren, A. S., Lijewski, M. J., & Zhang, K. (2010). High-resolutionsimulation and characterization of density-driven flow in CO2 storage in saline aquifers. Advancesin Water Resources, 33(4), 443-455.[5] Nadal, F., Meunier, P., Pouligny, B., & Laurichesse, E. (2013). Stationary plume inducedby carbondioxide dissolution. Journal of Fluid Mechanics, 719, 203-229.[6] Dhar, J., Meunier, P., Nadal, F. & Méheust, Y. (2021). Convection dissolution of CO2 in 2D and3D porous media: the impact of hydrodynamic dispersion. Submitted to Physics of Fluids

Experimental study of miscible Rayleigh-Taylor convection in agranular porous medium

International audienceMore than 60% of greenhouse gas emissions are due to CO2 released from fossil fuels andindustrial processes [1]. It is expected that by 2035, the expected increase in CO2 emissions will be37.2 Gt/yr [2]. To reduce the resulting further adverse effects in climate changes, geologicalsequestration of CO2 provides an effective solution for carbon capture and storage (CCS) [2-4].Dissolution trapping of CO2 in deep saline aquifers is a trapping mechanism that allows for longterm storage. When CO2 is injected into the subsurface geological layers, the supercritical CO2(sCO2) dissolves into the aquifer’s aqueous solution positioned below. The formation of a layer ofCO2-enriched brine at the upper interface of the liquid domain results in unstable stratificationwhich evolves into gravitational convection [2-5].To evaluate the storage capacity and the efficiency of the trapping, it is necessary to understandthe dynamics of the instabilities and convection, and the affect of granular media properties onthem. To do so, we perform a 2D experimental study in a 3D granular medium and use Darcyscale simulations to complement our experimental findings [6]. Analog experiments areperformed by using two miscible fluids with a density contrast between them. In doing so wedecouple the gravitational instability process from the dissolution process; the latter is notmodeled in our experiment. We match the refractive index of the fluids to that of the granularmedium to allow for optical measurement of the concentration field. We observe that there issubstantial difference in convection development time scales between the experimental resultsand the Darcy scale simulations performed with the experimental macroscopic parameters(porosity, permeability, dispersivity lengths, density contrast). We attribute this to the role playedby pore scale heterogeneity of the velocity field, which cannot be predicted by Darcy scale models.This would suggest that Darcy scale simulations [2, 4,6] significantly overestimate the typical timescale of the convection.[1] Contribution of Working Group III to the Fifth Assessment Report of the IntergovernmentalPanel on Climate Change, IPCC 2014.[2] Emami-Meybodi, H., Hassanzadeh, H., Green, C. P., & Ennis-King, J. (2015). Convective dissolution of CO2 in saline aquifers: Progress in modeling and experiments. International Journalof Greenhouse Gas Control, 40, 238-266.[3] Bachu, S. (2008). CO2 storage in geological media: Role, means, status and barriers todeployment. Progress in energy and combustion science, 34(2), 254-273.[4] Pau, G. S., Bell, J. B., Pruess, K., Almgren, A. S., Lijewski, M. J., & Zhang, K. (2010). High-resolutionsimulation and characterization of density-driven flow in CO2 storage in saline aquifers. Advancesin Water Resources, 33(4), 443-455.[5] Nadal, F., Meunier, P., Pouligny, B., & Laurichesse, E. (2013). Stationary plume inducedby carbondioxide dissolution. Journal of Fluid Mechanics, 719, 203-229.[6] Dhar, J., Meunier, P., Nadal, F. & Méheust, Y. (2021). Convection dissolution of CO2 in 2D and3D porous media: the impact of hydrodynamic dispersion. Submitted to Physics of Fluids

Experimental characterization of Rayleigh-Taylor convection in granular media for CO2 sequestration by dissolution trapping

International audienceA large fraction of greenhouse gases (about 60%) released into the atmosphere are due to CO2 emissions from industrial processes and the burning of fossil fuels [1]. One of the strategies employed to reduce the emissions is rapping them securely in the subsurface [2-4]. Dissolution trapping, in particular, involves injection of CO2 into the subsurface where the supercritical CO2 (sCO2) dissolves in the aquifer brine and forms a CO2 enriched layer within solution. The interface between the high density CO2 rich brine on the top and the ambient low density aquifer water below results in destabilization of the aforementioned layer [2-4]. This leads to a gravitational instability which then causes a natural convection of CO2 rich brine to lower layers, thereby accelerating further dissolution of the sCO2 into the fresh brine.The study of Brouzet et al. shows that traditional continuume scale, Darcy law-governed, models underestimate the timescales of the convective dissolution’s dynamics, owing to local heterogeneity in the pore-scale flow, and that it may thus be necessary to take pore-scale fluctuations into account [5]. We present here a 2D experimental study using miscible analog fluids with a contrast in densities to understand the convective transport of the dissolved sCO2. The fluids and the granular media are refractive index matched, which renders the medium transparent and helps in accurate quantification of experimental findings at various Rayleigh (Ra) and Darcy numbers (Da). Darcy scale simulations are used to complement the two-dimensional experimental measurements and it was found that Darcy scale simulations underpredict the experimental findings by several orders of magnitude, which is consistent with the findings by Brouzet et al. We investigate convective dynamics for various values of the number by changing the density of fluids, the properties of the granular medium (permeability, size of the granular medium) which determines the size of the instability with respect to pore size. When that number is much smaller than 1, obvious causes for the failure of the continuum scale description can be excluded, yet discrepancies remain between the experimental results and the simulations.References:[1] Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, IPCC 2014.[2] Emami-Meybodi, H., Hassanzadeh, H., Green, C. P., & Ennis-King, J. (2015). Convective dissolution of CO2 in saline aquifers: Progress in modeling and experiments. International Journal of Greenhouse Gas Control, 40, 238-266.[3] Pau, G. S., Bell, J. B., Pruess, K., Almgren, A. S., Lijewski, M. J., & Zhang, K. (2010). High-resolution simulation and characterization of density-driven flow in CO2 storage in saline aquifers. Advances in Water Resources, 33(4), 443-455.[4] Meunier, P., & Nadal, F. (2018). From a steady plume to periodic puffs during confined carbon dioxide dissolution. Journal of Fluid Mechanics, 855, 1-27.[5] Brouzet, C., Méheust, Y., & Meunier, P. (2022). CO2 convective dissolution in a three-dimensional granular porous medium: An experimental study. Physical Review Fluids, 7(3), 033802

Experimental study of miscible Rayleigh-Taylor convection in agranular porous medium

International audienceMore than 60% of greenhouse gas emissions are due to CO2 released from fossil fuels andindustrial processes [1]. It is expected that by 2035, the expected increase in CO2 emissions will be37.2 Gt/yr [2]. To reduce the resulting further adverse effects in climate changes, geologicalsequestration of CO2 provides an effective solution for carbon capture and storage (CCS) [2-4].Dissolution trapping of CO2 in deep saline aquifers is a trapping mechanism that allows for longterm storage. When CO2 is injected into the subsurface geological layers, the supercritical CO2(sCO2) dissolves into the aquifer’s aqueous solution positioned below. The formation of a layer ofCO2-enriched brine at the upper interface of the liquid domain results in unstable stratificationwhich evolves into gravitational convection [2-5].To evaluate the storage capacity and the efficiency of the trapping, it is necessary to understandthe dynamics of the instabilities and convection, and the affect of granular media properties onthem. To do so, we perform a 2D experimental study in a 3D granular medium and use Darcyscale simulations to complement our experimental findings [6]. Analog experiments areperformed by using two miscible fluids with a density contrast between them. In doing so wedecouple the gravitational instability process from the dissolution process; the latter is notmodeled in our experiment. We match the refractive index of the fluids to that of the granularmedium to allow for optical measurement of the concentration field. We observe that there issubstantial difference in convection development time scales between the experimental resultsand the Darcy scale simulations performed with the experimental macroscopic parameters(porosity, permeability, dispersivity lengths, density contrast). We attribute this to the role playedby pore scale heterogeneity of the velocity field, which cannot be predicted by Darcy scale models.This would suggest that Darcy scale simulations [2, 4,6] significantly overestimate the typical timescale of the convection.[1] Contribution of Working Group III to the Fifth Assessment Report of the IntergovernmentalPanel on Climate Change, IPCC 2014.[2] Emami-Meybodi, H., Hassanzadeh, H., Green, C. P., & Ennis-King, J. (2015). Convective dissolution of CO2 in saline aquifers: Progress in modeling and experiments. International Journalof Greenhouse Gas Control, 40, 238-266.[3] Bachu, S. (2008). CO2 storage in geological media: Role, means, status and barriers todeployment. Progress in energy and combustion science, 34(2), 254-273.[4] Pau, G. S., Bell, J. B., Pruess, K., Almgren, A. S., Lijewski, M. J., & Zhang, K. (2010). High-resolutionsimulation and characterization of density-driven flow in CO2 storage in saline aquifers. Advancesin Water Resources, 33(4), 443-455.[5] Nadal, F., Meunier, P., Pouligny, B., & Laurichesse, E. (2013). Stationary plume inducedby carbondioxide dissolution. Journal of Fluid Mechanics, 719, 203-229.[6] Dhar, J., Meunier, P., Nadal, F. & Méheust, Y. (2021). Convection dissolution of CO2 in 2D and3D porous media: the impact of hydrodynamic dispersion. Submitted to Physics of Fluids

Pharmacologically active flavonoids from the anticancer, antioxidant and antimicrobial extracts of Cassia angustifolia Vahl

Background: Cassia angustifolia Vahl. (commonly known as senna makkai or cassia senna), native to Saudi Arabia, Egypt, Yemen and also extensively cultivated in Pakistan, is a medicinal herb used traditionally to cure number of diseases like liver diseases, constipation, typhoid, cholera etc. This study was conducted to evaluate the in-vitro antimicrobial, antioxidant and anticancer assays and phytochemical constituents of aqueous and organic extracts of C. angustifolia leaves. Methods: The antimicrobial activities of C. angustifolia aqueous and organic (methanol, ethanol, acetone, ethyl acetate) extracts were investigated by the disk diffusion method. These extracts were further evaluated for antioxidant potential by the DPPH radical scavenging assay. Anticancer activities of the extracts were determined by the MTT colorimetric assay. The total phenolic and flavonoid contents of C. angustifolia extracts were evaluated by the Folin-Ciocalteu method and aluminum chloride colorimetric assay, respectively. The structures of the bioactive compounds were elucidated by NMR and ESI-MS spectrometry. Results: Bioactivity-guided screening of C. angustifolia extracts, led to the isolation and identification of three flavonoids quercimeritrin (1), scutellarein (2), and rutin (3) reported for the first time from this plant, showed significant anticancer activity against MCF-7 (IC50, 4.0 mu g/mu L), HeLa (IC50, 5.45 mu g/mu L), Hep2 (IC50, 7.28 mu g/mu L) and low cytotoxicity against HCEC (IC50, 21.09 mu g/mu L). Significant antioxidant activity was observed with IC50 2.41 mu g/mL against DPPH radical. Moreover, C. angustifolia extracts have the potential to inhibit microbial growth of E. cloacae, P. aeruginosa, S. mercescens and S. typhi. Conclusion: C. angustifolia extracts revealed the presence of quercimeritrin (1), scutellarein (2), and rutin (3), all known to have useful bioactivities including antimicrobial, antioxidant and anticancer activities.Research Directorate, National University of Sciences and Technology (NUST), Islamabad, Pakistan [H-12]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]