Department of Applied Mechanics

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Polymer bi-layer systems are often exposed to different environmental service conditions which can potentially alter the mechanical properties as it approaches the glass transition temperature of an inaccessible substrate. However, since the substrate is inaccessible, it is difficult to measure or quantify the changes in these properties while in use. A methodology has been proposed in this work for prediction of glass transition temperature and Young's modulus of an inaccessible substrate in a bilayer system. The composite mechanical property of a bi-layer system is a function of the mechanical properties of coating, substrate and the depth at which it is measured. In the present work, poly-Methylmethacrylate (PMMA) coating of 900 nm is deposited on epoxy substrate. Nanoindentation experiments are conducted at different temperatures on the bi-layer system as well as on bulk PMMA. Finite element analysis has been used to obtain the material dependency of stress distribution coefficient (α) for deconvoluting the modulus of the substrate. The methodology developed by the present authors can predict the glass transition temperature as well the magnitudes of Young's modulus of an inaccessible substrate reasonably well. © 2020

World University root node

Department of Mechanical Engineering

Polymer

Prediction of glass transition temperature and Young's modulus of an inaccessible polymer substrate in changing environment

Surface coatings are mainly applied to protect concrete structures against various environmental conditions. However, the interface between the concrete and coating is a weak link, and interfacial delamination is the primary mode of failure. Fracture resistance is the main design criteria for these materials, and therefore, it is necessary to investigate possible causes of interfacial failure for preventive measures. To this end, we have investigated the potential failure mechanisms and measured interfacial strength by performing a pull‐off adhesion test on epoxy coated cement paste. From the pull‐off adhesion test, adhesive (interface) failure between cement paste and epoxy is predominantly observed. It is observed that the adhesive (interfacial) strength for the sample tested on 50th day is more than the 28 days hydrated sample. This is due to additional curing of cement paste samples after coating epoxy which leads to higher interfacial strength. We also present the phase‐field model (PFM) to predict the adhesive failure for this system. The results obtained from the PFM, i.e., load at failure and crack path are validated against experimental results. Finally, the influence of various material parameters such as elastic modulus and fracture energy of the interface on interfacial fracture behaviour is studied. © The Author(s) 2021.

Department Of Civil Engineering

Fulltext

RILEM Technical Letters

Interfacial fracture behaviour between cement paste and epoxy coating ‐ an experimental and phase‐field approach

Microwave hyperthermia makes use of microwaves to deliver heat to biological tissues. Real time temperature monitoring during treatment is important for efficacy and effectiveness of the treatment. Non-invasive methods such as CT, MR and ultrasound (US) have been actively researched for use in hyperthermia monitoring. US has inherent advantages of real-time imaging, portability and non-ionizing nature. It is also known from the literature that acoustic properties of tissue are sensitive to temperature and this has been harnessed to track the evolution of hotspot and temperature in high temperature zones encountered in ablation treatments. However, their usage in low temperature zones typically observed in hyperthermia appears to be less explored. This study introduces an improved method of regularized Kurtosis imaging (RKI) and compares its performance against regularized log spectral difference (RLSD) and regularized Nakagami imaging methods. The performance of these methods is compared against the ground truth estimated from IR thermal images in an experimental study on tissue-mimicking PAG-agar based phantoms. The error in the area estimated by RKI was 10.6%. The error in the lateral and axial co-ordinate of the centroid was 5.92% and 0.47%, respectively. The structural similarity index was 0.82 for RKI when compared with RLSD and RNI having score of 0.76 and 0.72, respectively. The results are promising and offer an alternative way to track the hotspot during microwave hyperthermia treatment. © 2020 IEEE.

Department Of Biotechnology

Department of Engineering Design

Proceedings - International Symposium on Biomedical Imaging

Regularized Kurtosis Imaging and its Comparison with Regularized Log Spectral Difference and Regularized Nakagami Imaging for Microwave Hyperthermia Hotspot Monitoring

Actuator-assisted Subpitch Translation-capable Transducer for Elastography: Preliminary Performance Assessment

Gypsum scaling over a RO membrane significantly reduces the permeate flux. Since, the phenomenon is linked to concentration polarization; the present study aims to understand the effect of high shear rates over the membrane in reducing gypsum scaling of cross-flow RO filters. We have proposed an integrated CFD and moment-based population balance (MPB) formulation which is less complex than tracking the growth of individual particles. Most of the previous studies on modeling of scaling and permeate flux decline employing MPB formulation were limited to dead-end filters. The present numerical model for cross-flow RO filter has been verified by comparing the precipitate mass and permeate flux decline with the published results for channel filter. This model has been employed for different cross-flow conditions and geometries. We have demonstrated that scaling can be mitigated by increasing the shear rate over the membrane surface. In roto-dynamic RO filters, a 50% increase in the initial permeate discharge can be achieved, and permeate flux decline in time can be restrained if the shear rate is increased by rotating the disk. For a channel of identical membrane area, a similar improvement of permeate discharge requires an approximately two orders of magnitude higher feed discharge. In a channel, gypsum scale formation is significant at larger distances from the inlet. While for roto-dynamic filters, scaling occurs at the stagnation zone near the axis of rotation, the scaling potential decreases with radius. Additionally, we have also discussed some striking differences between fouling and scaling patterns in cross-flow RO filters. © 2020 Elsevier Ltd.

Journal of Environmental Chemical Engineering

CFD modeling of gypsum scaling in cross-flow RO filters using moments of particle population balance

Garlic (Allium sativum L.), a popular spice, has been used for decades in treating several medical conditions. Although Allicin, an active ingredient of garlic has been extensively studied on carcinogen-induced hepatotoxicity and oxidative stress in rats (Rattus norvegicus), no systematic study on the beneficial effects of generic aged garlic and specific aged garlic extract-Kyolic has been done. The present study involves rats fed chronically with two liver carcinogens, p-dimethylaminoazobenzene and phenobarbital, to produce hepatotoxicity. The aged garlic extract was characterized by UV-spectra, FTIR, HPLC and GC-MS. Biochemical and pathophysiological tests were performed by keeping suitable controls at four fixation intervals, namely, 30, 60, 90, and 120 days, utilizing several widely accepted toxicity biomarkers. Compared to the controls, remarkable elevation in the activities of lactate dehydrogenase, gamma glutamyl transferase and decline in catalase and glucose-6-phosphate dehydrogenase were observed in the carcinogen fed rats. Daily administration of aged garlic extract, could favorably modulate the elevated levels of various toxicity biomarkers including serum triglyceride, creatinine, urea, bilirubin, blood urea nitrogen except total cholesterol. It also altered the levels of blood glucose, HDL-cholesterol, albumin, AST, ALT, and hemoglobin contents in carcinogen intoxicated rats, indicating its protective potential against hepatotoxicity and oxidative stress in the experimental rats. Down-regulation of Bcl-2 and p53 proteins caused cell cycle arrest and apoptosis in garlic fed group. Kyolic exhibited additional benefits by arresting cell viability of cancer cells. This study would thus validate the use of aged garlic extract in the treatment of diseases causing liver toxicity including hepatocarcinoma.

Benefits of aged garlic extract in modulating toxicity biomarkers against p-dimethylaminoazobenzene and phenobarbital induced liver damage in Rattus norvegicus

It is now well established that most of the tumors are heterogeneous in nature that comprise a population of cancer stem cells (CSCs) and differentiated cancer cells. Like normal stem cells, CSCs have also self-renewal, proliferation, and differentiation capacities that are responsible for the development of drug resistance and relapse. Therefore, targeting CSCs is essential for the elimination of tumor recurrence condition. Although several anti-CSC therapeutics have been used in clinics, they are found to have limited efficacy due to poor solubility, lesser stability, and short circulation time in the blood. Therefore, tools in nanomedicines are being used to tackle these limitations. Recently, nanodrug carriers have been used to target CSCs and somewhat eliminate drug resistance by targeting CSC metabolism, inhibiting drug transporters, disturbing CSC survival pathways, etc. Even with these progress, the challenges for targeting CSCs by nanomedicines still remain and open up plenty of space for further development and improvement in synthesizing drug carriers with higher efficacy. In this chapter, we summarize about CSCs and their biological characterization toward resistance, then discuss several anti-CSC therapeutic approaches based on nanomedicines in the current state of research and development, and finally overview their future directions.

Nanomedicine in Cancer Stem Cell Therapy

Failure of bioengineered meniscus implant after transplantation is a major concern owing to mechanical failure, lack of chondrogenic capability and patient specific design. In this article, we have, for the first time, fabricated a 3D printed scaffold with carbohydrate based self-healing interpenetrating network (IPN) hydrogels-based monolith construct for load bearing meniscus tissue. 3D printed PLA scaffold was surface functionalized and embedded with self-healing IPN hydrogel for interfacial bonding further characterized by micro CT. Using collagen (C), alginate (A) and oxidized alginate (ADA), we developed self-healing IPN hydrogels with dual crosslinking (Ca2+ based ionic crosslinking and Schiff base (A-A, A-ADA)) capability and studied their physicochemical properties. Further, we studied human stem cells behaviour and chondrogenic differentiation potential within these IPN hydrogels. In-vivo heterotopic implantation confirmed biocompatibility of the monolith showing the feasibility of using carbohydrate based IPN hydrogel embedded in 3D printed scaffold for meniscal tissue development. © 2020 Elsevier B.V.

Department of Ocean Engineering

International Journal of Biological Macromolecules

Meniscal tissue engineering via 3D printed PLA monolith with carbohydrate based self-healing interpenetrating network hydrogel

In the above paper [1], we proposed a novel framework that uses a constrained formulation of sum of squared correlation (SSCOR) approach as an alternative method for designing a spatial filter for steady-state visual evoked potential (SSVEP) based brain-computer interfaces (BCIs). To evaluate the target detection performance of the SSCOR method, the task-related component analyses (TRCA) were used as a benchmark [2]. The study used the SSVEP benchmark dataset containing 40 target data collected from 35 subjects [3]. During the evaluation of the proposed method, the SSCOR provided very high detection performance and outperformed the TRCA method and the results were reported. (Figure Presented). © 2001-2011 IEEE.

IEEE Transactions on Neural Systems and Rehabilitation Engineering

Erratum: Designing a sum of squared correlations framework for enhancing SSVEP based BCIs (IEEE Transactions on Neural Systems and Rehabilitation Engineering (2019) 27:10 (2044-2050) DOI: 10.1109/TNSRE.2019.2941349)

In this study, an attempt has been made to differentiate normal and cardiomegaly using cardio-mediastinal ratiometric features and machine learning approaches. A total of 60 chest radiographs including normal and cardiomegaly subjects are considered from a public dataset. The images are preprocessed using edge aware contrast enhancement technique to improve the edge contrast of lung boundaries. The mediastinal, cardiac and thoracic widths and their ratiometric indices are computed to characterize the morphological variations. The features are fed to three different classifiers for the differentiation of normal and cardiomegaly. Results show that the Linear discriminant analysis classifier is found to perform better with average values of recall 88.7%, precision 88.8%, and area under the curve 91.9%. Hence, the proposed computer aided diagnostic approach appears to be clinically significant to distinguish normal and cardiomegaly especially in remote and resource - poor settings. © 2020 European Federation for Medical Informatics (EFMI) and IOS Press.