Department of Mechanical Engineering

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

In vitro, cellular processing on polymeric surfaces is fundamental to the development of biosensors, scaffolds for tissue engineering and transplantation. However, the effect of surface energy and roughness on the cell-surface interaction remains inconclusive, indicating a lack of complete understanding of the phenomenon. Here, we study the effect of surface energy (Es) and roughness ratio (r) of a polydimethylsiloxane (PDMS) substrate on cell attachment, growth, and proliferation. We considered two different cell lines, HeLa and MDA MB 231, and rough PDMS surfaces of different surface energy in the range Es = 21-100 mJ m-2, corresponding to WCA 161°-1°, and roughness ratio in the range r = 1.05-3, corresponding to roughness 5-150 nm. We find that the cell attachment process proceeds through three different stages marked by an increase in the number of attached cells with time (stage I), flattening of cells (stage II), and elongation of cells (III) on the surface. Our study reveals that moderate surface energy (Es ≈ 70 mJ m-2) and intermediate roughness ratio (r ≈ 2) constitute the most favourable conditions for efficient cell adhesion, growth, and proliferation. A theoretical model based on the minimization of the total free energy of the cell-substrate system is presented and is used to predict the spread length of cells that compares well with the corresponding experimental data within 10%. The performance and reusability of the rough PDMS surface of moderate energy and roughness prepared via facile surface modification are compared with standard T-25 cell culture plates for cell growth and proliferation, which shows that the proposed surface is an attractive choice for efficient cell culture. © The Royal Society of Chemistry.

World University root node

Fulltext

RSC Advances

Effect of surface energy and roughness on cell adhesion and growth-facile surface modification for enhanced cell culture

Lung cancer is a prominent type of cancer, which leads to high mortality rate worldwide. The major lung cancers lung adenocarcinoma (LUAD) and lung squamous carcinoma (LUSC) occur mainly due to somatic driver mutations in proteins and screening of such mutations is often cost and time intensive. Hence, in the present study, we systematically analyzed the preferred residues, residues pairs and motifs of 4172 disease prone sites in 195 proteins and compared with 4137 neutral sites. We observed that the motifs LG, QF and TST are preferred in disease prone sites whereas GK, KA and ISL are predominant in neutral sites. In addition, Gly, Asp, Glu, Gln and Trp are preferred in disease prone sites whereas, Ile, Val, Lys, Asn and Phe are preferred in neutral sites. Further, utilizing deep neural networks, we have developed a method for predicting disease prone sites with amino acid sequence based features such as physicochemical properties, conservation scores, secondary structure and di and tri-peptide motifs. The model is able to predict the disease prone sites at an accuracy of 81 % with sensitivity, specificity and AUC of 82 %, 78 % and 0.91, respectively, on 10-fold cross-validation. When the model was tested with a set of 417 disease-causing and 413 neutral sites, we obtained an accuracy and AUC of 80 % and 0.89, respectively. We suggest that our method can serve as an effective method to identify the disease causing and neutral sites in lung cancer. We have developed a web server CanProSite for identifying the disease prone sites and it is freely available at-https://web.iitm.ac.in/bioinfo2/CanProSite/. © 2020 Elsevier B.V.

Department Of Biotechnology

Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis

Predicting potential residues associated with lung cancer using deep neural network

An efficient synthesis of substituted 3,4-dihydroisoquinolinones through [4+2]-annulation ofN-chlorobenzamides/acrylamides having a monodentate directing group with alkylidenecyclopropanes in the presence of a less expensive, highly abundant and air stable Co(iii) catalystviaa C-H activation is demonstrated. In this reaction, the N-Cl bond ofN-chlorobenzamide serves as an internal oxidant and thus an external metal oxidant is avoided. The 3,4-dihydroisoquinolinone derivatives are converted successfully into the highly useful imidoyl chloride derivatives. The deuterium labeling and kinetic isolabelling studies reveal that the C-H activation is a rate-determining step in this cyclization reaction. © The Royal Society of Chemistry 2021.

Department Of Chemistry

Chemical Communications

Cobalt(iii)-catalyzed redox-neutral [4+2]-annulation ofN-chlorobenzamides/acrylamides with alkylidenecyclopropanes at room temperature

In this work, ceramic reinforcement of soft Ag–Cu–Ti filler alloy has been attempted to produce a superior filler alloy to braze cBN to steel in high vacuum conditions without compromising wettability and joint strength. 2 and 5 wt% of micro-alumina (μAl2O3) particles of average particle size (APS) 10 μm were added to Ti-activated (2 wt%) eutectic (72Ag28Cu) filler alloy as reinforcements for brazing Cubic Boron Nitride (cBN) particles (APS: 427 μm) to steel substrate. The alloy-matrix wetted μAl2O3 particles appreciably. Cu3Ti3O phase formed (confirmed through TEM/SAED-pattern analyses) and grew surrounding the μAl2O3 particles with a very thin interlayer of γ-TiO. Nano-hardness of Cu3Ti3O was measured to be 17.6±2.42 GPa. Cu3Ti3O together with μAl2O3 particles resulted in substantially enhanced (63–76%) abrasion-resistance characteristics of the primary alloy. 5 wt% addition of μAl2O3 to Ag–Cu–2Ti alloy displayed superior performance to 2 wt% addition. However, with higher proportion (5 wt%), wettability of the reinforced filler on cBN part got slightly impaired. Few micro-voids also surfaced on cBN-encapsulating bonding layer. Considering joint strength and wettability, 2 wt% of μAl2O3 is recommended to produce brazed cBN tools for high-impact load applications. © 2020 Elsevier Ltd

Vacuum

High vacuum active brazing of cBN with improved composite filler: Microstructure, interfaces and performance evaluation

Current study investigates tribo-phenomena at sliding interface of Al2124-17SiCp disc and WC-6Co pin and explores suitability of nano-oil aerosols as lubricants. They form chip-tool tribo-pair in machining. Ploughing, adhesion, abrasion were predominant under dry sliding. Adhesion and friction-coefficient (COF) were severer with higher normal load and lower sliding velocity. Aerosol of palm-oil arrested adhesion of aluminium on carbide pin and reduced COF by 80–82% through film-lubrication but at low load conditions. Diamond/graphite nanoparticles (1 wt%) suspension helped palm-oil sustain film-lubrication at sliding interface even in extreme conditions, reducing COF further and arresting adhesion phenomenon. Rolling of near-spherical nano-diamonds or basal-plane shearing within graphite nano-platelets caused additional reduction in friction. Graphite nano-aerosol was superior and similarly effective in high-speed milling as SQL-medium. © 2020 Elsevier Ltd

Tribology International

Anti-frictional role of diamond and graphite suspended bio-oil based nano-aerosols at sliding interface of Al-SiCp and WC-6Co

The influence of temperature on the tribological performance of alloy 718 is studied in the present work. The alloy 718 samples were used in double aged condition for reciprocating wear test with a ball on flat configurations. The wear tests were conducted at two conditions viz: room temperature and 300 °C temperature. The testing temperature had a significant influence on the coefficient of friction (COF) and wear resistance of alloy 718. The alloy 718 sample, subjected to high-temperature testing environment had a lower COF and higher wear rate compared to samples tested at ambient temperature. The lower COF values of the alloy 718 samples subjected to high wear testing temperature conditions were attributed to the extent and presence of glaze layer formation, which is insignificant in the case of samples subjected to ambient temperature. The higher wear rate values of the alloy 718 samples subjected to high wear testing temperature conditions were attributed to the due to occurrence of tribo-chemical reactions at the contact zone of tribo-pair. © 2021, Springer Nature Singapore Pte Ltd.

Lecture Notes in Mechanical Engineering

Investigation on Elevated Temperature Tribological Performance of Alloy 718

In this work, a finite-difference-based axisymmetric off-lattice Boltzmann solver is developed to simulate blood flow through pathological arteries. The proposed solver handles arterial geometries using a body-fitted curvilinear mesh. The axisymmetric nature of the flow and the non-Newtonian behavior of blood are incorporated using external source terms. The solver is verified for spatially developing pulsatile inflow through an abdominal aortic aneurysm using reference data from literature. Thereafter, the effects of amplitude and frequency of an irregular-shaped stenosed artery are systematically studied. The results are analyzed using the instantaneous vorticity contours, streamlines, cycle-averaged and phase-averaged profiles of wall shear stress (WSS), and oscillatory shear index. Further, the correlation between the luminal surface concentration (LSC) of low-density lipoproteins and the WSS is studied to predict potential disease initiation and progression locations. It is noted that an increase in the amplitude of irregularity of the stenosis increases the magnitudes of maxima and minima of WSS profiles without altering their locations. On the other hand, an increase in the frequency of irregularity increases the magnitudes of WSS extrema while bringing the peaks closer together. Further, a positive correlation is found between the degree of irregularity as well as the number of locations of elevated LSC. The presence of irregularity creates additional vortices in the upstream section of the stenosis. Both the upstream and downstream sections of the stenosis are subjected to the opposing shear-layers with higher magnitudes, which may lead to endothelial damage. Finally, the shear-thinning effect of blood is studied using the power-law model. The magnitudes of the maxima and minima in WSS have a lower value for the shear-thinning model than the Newtonian case. Also, the vortices that were produced in the upstream section because of the irregularity get suppressed by the shear-thinning effect of the blood. © 2021 Author(s).

Physics of Fluids

An off-lattice Boltzmann method for blood flow simulation through a model irregular arterial stenosis: The effects of amplitude and frequency of the irregularity

This two-part article examines the distribution of metallic layers through the thickness of fiber metal laminates (FMLs) on their response and damage when subjected to high-velocity projectile impact. Glass fiber/epoxy and Ti-6Al-4V titanium alloy sheets are used to obtain four different layups of FMLs fabricating by the hand layup process and exhibiting the same thickness of the total metal layer. Part I deals with experimental investigations of fully clamped square FMLs normally impacting at the center by hemispherical steel projectile using compressed air gun set up. Different parameters are considered to evaluate the FMLs’ performance, which includes damage degree, first cracking energy, crack length, deformation profile, and damage developed on the surface and inside the laminate. The results indicate that the highest permanent deformation and cracking are exhibited by FML 4/3-0.3, exhibiting separation of composite layers with different orientations by the metallic layer. The other FMLs exhibit lower and approximately similar permanent deformations. However, lower cracking and a relatively higher lateral delamination spread and opening of the interlayer are exhibited by FML 2/1-0.6 in which composite layers are arranged together than FML 4/3-0.3, signifying that the damage spreading laterally can be reduced by dispensing titanium layers. The ballistic resistance is found to be similar for FMLs. The levels of permanent deformation, cracking, and delamination with their opening and spreading are lesser for titanium-based FMLs than aluminium-based FMLs. The ballistic response of FMLs will be evaluated using analytical modeling in an accompanying study (Part II). © 2021 Elsevier Ltd

Department of Aerospace Engineering

International Journal of Impact Engineering

High-velocity impact response of titanium-based fiber metal laminates. Part I: experimental investigations

Halbach EMATs can efficiently generate shear horizontal (SH) guided wave modes. Using the Halbach magnet structure, the EMATs can enhance the magnetic flux density within a material forming ultrasonic waves with relatively large amplitude. The paper first presents a comparison analysis of double-row Halbach EMATs with double-row PPM EMATs using Finite Element based simulation models for SH0 ultrasonic wave generation. The study then analyses the wave interference effects created by the staggered double-row Halbach EMAT configurations. This is also performed using numerical Finite Element Models (FEM) and experimentally validated in an Aluminum plate specimen. It is observed that the steering of the ultrasonic guided waves can be associated and predicted for different double-row staggered PPM EMAT configurations. © 2021 Elsevier Ltd

Department of Metallurgical and Materials Engineering

NDT and E International

Characterising the beam formation of SH waves using double-row Staggered Halbach EMAT configurations

In this paper, Artificial Intelligence (AI) algorithms are employed for first, automating the process of creating a large synthetic Total Focusing Method (TFM) imaging dataset using a small set of Finite Element (FE) simulation datasets, and second for the automated defect-recognition (ADR) in butt-welds. In this paper, six types of imaging datasets are created with three approaches. In the first approach, weld TFM images are constructed using ultrasonic A-scan signals obtained from Full Matrix Capture (FMC) performed using FE analysis on models with weld defects (porosity and slag). The second approach generates near real-time weld TFM images by implementing fast deep convolution generative adversarial networks (DCGAN). This second technique permits simulations that are several orders faster when compared to the FE method. In the third approach, noise is extracted from FMC-TFM experimental measurements using the sliding kernel approach, and this noise is supplemented to individual simulated datasets for creating near to realistic scenarios. The first dataset is created using the first approach. The second dataset is created using the second approach, and the third hybrid dataset is a combination of FE and DCGAN weld TFM imaging. The fourth dataset is noise supplemented to FE based dataset. The fifth dataset is generated by adding noise to DCGAN images. The sixth hybrid dataset with noise is a combination of FE and DCGAN weld TFM noise images. AI plays a significant role in object detection and classification through robust feature extraction, reducing human intervention. In this work, for automated weld defect recognition, a convolutional neural network (CNN) is trained using six types of simulation-assisted weld TFM imaging datasets, which improves the reliability and efficiency of welds quality assurance. The mAP value is 85% for the ADR model trained using the hybrid weld TFM dataset with noise. The model prediction on classification on the hybrid dataset for porosity is 0.86 F1-score, and for slag is 0.80 F1-score. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.