DESIGN AND OPTIMIZATION OF PERISTALTIC MICROPUMPS USING EVOLUTIONARY ALGORITHMS

A design optimization based on coupled solid–fluid analysis is investigated in this work to achieve specific flow rate through a peristaltic micropump. A micropump consisting of four pneumatically actuated nozzle/diffuser shaped moving actuators on the sidewalls is considered for numerical study. These actuators are used to create pressure difference in the four pump chambers, which in turn drives the fluid through the pump in one direction. Genetic algorithms along with artificial neural networks are used for optimizing the pump geometry and the actuation frequency. A simple example with moving walls is considered for validation by developing an exact analytical solution of Navier–Stokes equation and comparing it with numerical simulations. Possible applications of these pumps are in microelectronics cooling and drug delivery. Based on the results obtained from the fluid–structure interaction analysis, three optimized geometries result in flow rates which match the predicted flow rates with 95% accuracy. These geometries need further investigation for fabrication and manufacturing issues

Multiscale methods for transport phenomena

In this thesis, we discuss the development of high fidelity multiscale methods to understand fluid flow past solid interfaces. Because of the dominant surface effects at the nanoscale, the classical field based continuum models break down. Particle-based methods offer accurate insights into the flow physics but are computationally expensive. Also, the ratio of pertinent to total information (particle trajectories) from these simulations is minimal. This research entails bridging these two descriptions of the flow physics at different scales to a unified, field-based quasi-continuum framework that can provide atomic level accuracy with continuum level efficiency. First, we discuss the construction of the transport model where fluid density and transport parameters such as viscosity are assumed to be varying across the confinement. These are, in turn, incorporated using Empirical Quasicontinuum Theory (EQT) and Local Average Density Model (LADM). We elucidate the failure of the "no-slip" boundary condition at the nanoscale and its estimation using the collective diffusion coefficient from Equilibrium Molecular Dynamics (EMD) calculations. Further, we reinterpret the slip phenomenon originating from liquid-solid interfacial friction. In this context, we discuss the Generalized Langevin Equation (GLE) based single particle dynamical framework that is consistent with the EMD simulations. Our adsorption based understanding of the flow physics elucidated that the slip length does not change with the slit width. Next, the methodology of multiscale dynamical "coarse-grained" (CG) framework is further refined to incorporate multi-physics to make it viable for a variety of fluid flow situations, such as Poiseuille flow of binary mixtures and nanochannel electroosmosis. The resultant suite of multiscale models significantly reduced the computational burden from tens of thousands of hours to seconds, without trading off the accuracy of the conventional transport parameters. Finally, we demonstrate the failure of local constitutive laws in fluids when strain-rate changes appreciably compared to the fluid molecular diameter, under extreme confinement. Here, a genuinely non-local constitutive relationship between the stress and strain-rate is more appropriate, and the viscosity is interpreted as a non-local kernel instead of a material property defined pointwise. The results indicate that a non-local model performs appreciably well in capturing the strain-rate sign reversals observed from Non-Equilibrium Molecular Dynamics calculations

DESIGN AND INVESTIGATION OF WEIGHT BUNDLE SIMULATOR FOR INDIAN PHWR USING APDL - A THERMAL ASPECT

Under a postulated scenario of Loss of Coolant Accident (LOCA) with un-availability of emergency core cooling system (ECCS) for Indian Pressurized Heavy Water Reactor (IPHWR), the channel integrity needs to be assured. An experimental facility is presently being developed at Indian Institute of Technology Roorkee (IIT R) India to study such a severe event. In this study a CFD simulation of fuel bundle weight simulator is being carried out using ANSYS 19.0 in transient thermal analysis using ANSYS Parametric Design Language (APDL) solver. The test facility aims to estimate the thermal aspect of weight bundle simulator which is the source of heat generation for pressure tube. Thermo-mechanical deformation of pressure tube will depend on the heat source, therefore it is of great importance to check the thermal integrity of weight bundle fuel simulator. Power requirement, weight, and dimensions of weight bundle fuel simulator is similar to the actual fuel bundle used in 700 MWe IPHWR. Simulation was done for 3 % and 2% decay heat. From analysis it was found that the rate of temperature rise in pressure tube with 3 % decay heat reached a maximum of 2 0C/sec and average rate of temperature rise was around 1 0C/sec whereas with 2% decay heat, pressure tube maximum temperature rise was 1.5 0C/sec and average rate 0.8 0C/sec. Results obtained will be further used for designing of 700 MWe full length channel set-up

DESIGN AND INVESTIGATION OF WEIGHT BUNDLE SIMULATOR FOR INDIAN PHWR USING APDL - A THERMAL ASPECT

Under a postulated scenario of Loss of Coolant Accident (LOCA) with un-availability of emergency core cooling system (ECCS) for Indian Pressurized Heavy Water Reactor (IPHWR), the channel integrity needs to be assured. An experimental facility is presently being developed at Indian Institute of Technology Roorkee (IIT R) India to study such a severe event. In this study a CFD simulation of fuel bundle weight simulator is being carried out using ANSYS 19.0 in transient thermal analysis using ANSYS Parametric Design Language (APDL) solver. The test facility aims to estimate the thermal aspect of weight bundle simulator which is the source of heat generation for pressure tube. Thermo-mechanical deformation of pressure tube will depend on the heat source, therefore it is of great importance to check the thermal integrity of weight bundle fuel simulator. Power requirement, weight, and dimensions of weight bundle fuel simulator is similar to the actual fuel bundle used in 700 MWe IPHWR. Simulation was done for 3 % and 2% decay heat. From analysis it was found that the rate of temperature rise in pressure tube with 3 % decay heat reached a maximum of 2 0C/sec and average rate of temperature rise was around 1 0C/sec whereas with 2% decay heat, pressure tube maximum temperature rise was 1.5 0C/sec and average rate 0.8 0C/sec. Results obtained will be further used for designing of 700 MWe full length channel set-up

Non-Diabetic Kidney Disease in Type 2 Diabetes Mellitus: A Changing Spectrum with Therapeutic Ascendancy

Background and objectives: Owing to changing epidemiology and therapeutic practices, a change in the spectrum of renal involvement in Type-2 diabetes mellitus (T2DM) has also been noted. The treatment of non-diabetic kidney disease (NDKD) differs from diabetic kidney disease (DKD) and the reversibility of NDKD in many cases to normal, prompts biopsy for rapid and accurate diagnosis. Data are scarce on kidney biopsy findings in T2DM. Study design & setting: In this observational study, we prospectively collected the data of kidney biopsies of patients aged ≥ 18 years with T2DM admitted between 1 August 2005 and 31 July 2022. The clinical, demographic and histopathological data were evaluated. The spectrum of kidney involvement in the form of DKD and/or NDKD was studied. The impact of these findings with the use of drugs retarding disease progression was also analyzed. Results: A total of 5485 biopsies were performed during the study period and of these 538 patients had T2DM. The mean age of the study population was 56.9 ± 11.5 years and 81% were males. The mean duration of DM was 6.4 ± 6.1 years. Diabetic retinopathy (DR) was noted in 29.7%. The most common indication for biopsy was an acute rise in creatinine (147, 27.3%). Amongst the 538 diabetic patients who underwent biopsy, histological features only of DKD were noted in 166 patients (33%), NDKD alone in 262 (49%) and NDKD with DKD lesions in 110 (20%). On multivariate analysis, duration of DM less than 5 years, absence of CAD, absence of DR, oliguria at presentation, an acute rise in creatinine and low C3 were associated with NDKD. Conclusions: The prevalence of NDKD among diabetics and ATIN in particular might be on an increasing trend in the current era of changing T2DM epidemiological patterns. The use of anti-pro-teinuric agents was associated with lesser degrees of histopathological chronicity in T2DM

Humoral Immune Response of SARS-CoV-2 Infection and Anti-SARS-CoV-2 Vaccination in Renal Transplant Recipients

Vaccination-induced SARS-CoV-2 neutralizing antibodies are required for herd immunity. Vaccine availability and poor vaccine response in renal transplant recipients (RTRs) remain a concern. There is no report on the efficacy of Covaxin and Covishield vaccines in RTRs. We recruited 222 live donors RTRs and analyzed the serum titer of anti-SARS-CoV-2 spike protein antibody by chemiluminescent magnetic microparticle immunoassay. Patients were categorized into three groups: group1 with SARS-CoV-2 infection and no vaccination (n = 161); group 2 with only vaccination and no SARS-CoV-2 infection (n = 41); and group 3 with both vaccination and SARS-CoV-2 infection (n = 20). Overall seroconversion rate was 193/222 (86.9%) with a median titer 1095.20 AU/mL. The median IgG titer value in group 1 was 647.0 AU/mL; group 2 was 1409.0 AU/mL; and group 3 was 1831.30 AU/mL. Covaxin associated seroconversion was observed in 16/19 (84.21%), with a median titer of 1373.90 AU/mL compared to that of Covishield 32/42 (76.19%), whose median titer was 1831.10 AU/mL. The seroconversion rate due to SARS-CoV-2 infection was 145 (90.06%), it was lowest with the vaccination-only group (70.7%), and with both vaccination and SARS-CoV-2 infection group it was highest (95%). In RTRs, SARS-CoV-2 infection and both Covaxin and Covishield vaccination effectively induce a humoral immune response against the SARS-CoV-2 spike protein; however, seroconversion rate was lower and the antibody titer was higher with vaccine than infection

Antibody Response to ChAdOx1 nCoV-19 (AZD1222) Vaccine in Kidney Transplant Recipients

Kidney transplant recipients (KTRs) are at a much higher risk of complications and death following COVID-19 and are poor vaccine responders. The data are limited on the immune response to Covishield® in KTRs. We prospectively recruited a cohort of 67 KTRs aged >18 between April 2021 and December 2021. Each participant was given two intramuscular doses of Covishield®, each of 0.5 mL, at an interval of 12 weeks. A blood specimen of 5.0 mL was collected from each participant at two points within a few days before administering the first dose of the vaccine and at any time between 4–12 weeks after administering the second dose. The sera were tested for anti-RBD antibody (ARAb) titre and neutralising antibody (NAb). An ACE2 competition assay was used as a proxy for virus neutralization. According to the prior COVID-19 infection, participants were grouped as (i) group A: prior symptomatic COVID-19 infection, (ii) group B: prior asymptomatic COVID-19 infection as evidenced by detectable ARAb in the prevaccination specimen, (iii) Group C: no prior infection with COVID-19, (iv) group D: Unclassified, i.e., participants had no symptoms suggestive of COVID-19, but their prevaccination specimen was not available for ARAb testing before vaccination. Fifty of sixty-seven participants (74.6%) provided paired specimens (group A 14, group B 27, and group C 9) and 17 participants (25.4%) provided only postvaccination specimens (group D). In the overall cohort (n = 67), 91% and 77.6% of participants developed ARAb and NAb, respectively. Their ARAb titre and NAb proportion were 2927 (520–7124) U/mL and 87.9 (24.4–93.2) %, respectively. Their median ARAb titre increased 65.6 folds, from 38.2 U/mL to 3137 U/mL. Similarly, the proportion of participants with NAb increased from 56% to 86%, and the NAb proportion raised 2.7 folds, from 23% to 91%. A comparison of vaccine response between the study groups showed that all those with or without prior COVID-19 infection showed a significant rise in ARAb titre (p < 0.05) and NAb proportion (p < 0.05) after the two doses of vaccine administration. The median value of folds rise in anti-RBD and NAb between groups A and B were comparable. Hence, ARAb is present in more than 3/4th of KTRs before the ChAdOx1 vaccine in India. The titer of ARAb and the proportion of NAb significantly increased after the two doses of the ChAdOx1 vaccine in KTRs