Shaswat Srivastava

Title: Re-oxidation of lead dioxide residue in Soluble Lead Redox Flow Battery (SLRFB): effect on cyclability

Abstract:
Soluble lead redox flow battery (SLRFB) has been an actively studied system in the past two decades, given its high energy efficiency of about 70% and charge efficiency of about 90% [1]. It is a cost-effective energy storage device with a similar capacity to other large-scale electrochemical energy storage devices. This is due to common electrochemical active species for both electrodes and the cell’s membrane-less single-compartment physical design. However, the number of cycles with stable output parameters achieved is less than 100 [2]. The degradation observables are the solid deposit shedding from the lead dioxide electrode and the gas evolution reaction. On the other hand, the two-step charging potential profile seen in the cycling of soluble lead redox flow battery (SLRFB) is still not fully understood in its dynamics. Several mathematical models predict the feature relying on the solid-solid side reaction within the lead dioxide residue [1,3].

The two-step charging has been envisioned as advantageous in terms of the voltage efficiency of the system. Contrastingly, cyclability is enhanced when the charging happens at the higher potential of the two steps [4]. Hence, an investigation was done to investigate the changes in deposition dynamics and deposit properties due to the recursive low-charging potential region. Using a modified electrolyte in a two-compartment Nafion-divided cell, we show that the side reaction does not occur without Pb2+ in the electrolyte. FESEM images of deposits formed on re-charging under normal conditions show the growth of lead dioxide from Pb2+ ions in the electrolyte on the residual deposit/electrode surface, challenging the idea of charging current sustained through the side reaction. These features raise concerns about the prevailing hypothesis about SLRFB dynamics. The observed deposit was layered, structurally weak, and constituted of whisker-like particles (thickness- 200 nm). We hypothesize the accumulation of such alterations over cycling to restrict SLRFB to a limited number of cycles. The observations could prove vital in designing efficient operating conditions and protocols for performance optimization.

References:
1. M. N. Nandanwar. Modelling and experimental investigations into soluble lead redox flow battery: new mechanisms. Ph.D. Thesis, Indian Institute of Science (2015).
2. J. Collins, G. Kear, X. Li, C. T. J. Low, D. Pletcher, R. Tangirala, D. Stratton-Campbell, F. C. Walsh, and C. Zhang, J. Power Sources, 195, 1731 (2010)
3. A. A. Shah, X. Li, R. G. A. Wills, and F. C. Walsh, J. Electrochem. Soc., 157(5), A589 (2010).
4. M. G. Verde, K. J. Carroll, Z. Wang, A. Sathrum, and Y. S. Meng. Energy & Environmental Science, 6(5), pp.1573-1581 (2013).

Rajesh Pavan Pothukuchi

Title: Molecular Level Insights Into The Turkevich Mechanism of Reduction Of Gold Au(III) Using Citrate

Abstract:
Gold nanoparticles (AuNPs) are one of the most widely used and studied nanomaterials with potential applications in nanomedicine, bionanotechnology, microelectronics, optics, and catalysis. Precise control of these nanoparticles’ size, shape, and synthesis protocols is important in tuning the material properties at bulk. Turkevich’s method for synthesizing citrate-stabilized AuNPs is the most popular because of its straightforward methodology and reliability in producing highly stabilized AuNPs ranging from 5 to 150 nm. The ease of exchanging citrate stabilizers with ligands that show high affinity with gold, especially thiols, allows the multi-functionalization of the AuNPs. The mechanism involves the oxidation of citrate, reduction of auric salt Au(III) to aurous salt Au(I), and disproportionation of the aurous species to gold (Au) atoms.​ Several studies have been conducted in the last 20 years to understand the mechanism of the Turkevich method, which might look simple to the eye but complex to understand. The nucleation and growth mechanism of AuNP formation, the formation of various complexes, the formation of byproducts, and their role in the synthesis are yet to be fully understood at the molecular level. This study aims to understand the reduction of gold from Au(I) to Au(0), especially the disproportionation reaction in the Turkevich method. Force fields to perform classical molecular dynamics (MD) simulations of the complexes were developed using density functional theory (DFT) and analytical methods. The study primarily focuses on understanding the formation of the Gold – di carboxy acetone (DCA-Au) complex and the dependence of the protonation state of DCA on complex formation. The study also highlights the role of the Au-O bond in complex formation.

Diksha Kadre

Title: Identification of crystal polymorphs of natural as hydrates using machine learning

Abstract:
The ability of the water molecules to form complex hydrogen bonded structures results in the formation of cages called host, that can fit up the other small or large gas molecule, for example methane in our case, also known as guests within it. Such structures are crystalline in nature and are termed as the natural gas hydrates. With the advances in computational techniques and the increase in computational power, it is now possible simulate such systems with higher accuracy. However, it is difficult to understand the mechanism of nucleation using molecular dynamics (MD) simulations. Furthermore, it is also important to identify crystal polymorphs for controlling nucleation by understanding their thermodynamic stabilities and kinetic properties as it aids in designing strategies to manipulate nucleation and characterizing synthesized materials. Many algorithms were proposed that can identify ice [1] or hydrates, or both [2] but failed to differentiate among their polymorphs. We propose a supervised machine learning method to analyse the local structure around a central atom and classify different crystal polymorphs of water in presence of natural gas (methane), for example: natural gas hydrates, ice and water during the nucleation of gas hydrates. The molecular arrangements seem to be better understood by computing and analysing bond order parameters, which has been proven to be an efficient in distinguishing different structures. In this work, we identify crystal polymorphs of natural gas hydrates by first simulating different structures of ice, water and natural gas hydrates using molecular dynamics simulation and then employing the machine learning algorithm that uses different sets order parameters for given crystal polymorphs. Our studies found that neighbouring environments to central atom plays an important role in classifying these polymorphs. In particular, the classification accuracy based on the order parameters computed using the vectors from the molecule to all the other neighbouring atoms is more than the ones computed using the vectors from the molecule to other molecules. We have also shown that our model classifies these crystal polymorphs with a very high accuracy (test accuracy > 99%) with only few features.

Shreya Chowdhury

Title: SYNERGISTIC EFFECT OF IMMUNE STIMULATION AND LATENCY REVERSAL MAY ELICIT LONG-TERM REMISSION OF SIV/SHIV INFECTION.

Abstract:
Current antiretroviral therapies (ART) for HIV infection are not curative. Extensive efforts are ongoing to devise strategies for eliciting cure. Recently experimental studies observed that a combination of latency reversal agents (LRAs) and broadly neutralizing antibodies (bNAbs) induced long-term remission of HIV infection, although the drugs failed individually. A question of great current interest follows: Why does combination therapy succeed while individual drugs fail? We hypothesized that LRA-induced reactivation of latent cells during suppressive ART stimulates transient viremia and promotes immune-complex formation with passively administered bNAbs that leads to effector priming against the virus, resulting in viremic control post-ART interruption. We test this hypothesis by constructing a mathematical model incorporating the effects of interventions on host immune cells. Our model predictions explained numerous confounding experimental observations. Importantly, it explained how the combination treatment works by simultaneously targeting latently infected cells and stimulating immune responses while the individual drugs fail. Furthermore, we show how the framework could be used to predict treatment strategies that would improve the chances of achieving a cure for HIV, which future experiments would test.

Karan Saxena

Title: Enhancing Sensitivity of Lateral Flow Immunoassays with Oxidative Coupling-Based Chromogenic Substrates for Horseradish Peroxidase

Abstract:
This work describes a novel approach to enhance the sensitivity of lateral flow immunoassays (LFIAs), which are commonly used in point-of-care diagnostics. We have developed novel oxidative coupling-based chromogenic substrates for horseradish peroxidase (HRP) enhancement of LFIA sensitivity. These substrates are inspired by the chemistry of commercial hair dyes consisting of two components: a primary intermediate and a colour developer that undergo an oxidative coupling reaction in the presence of HRP and hydrogen peroxide to generate an intensely coloured, precipitating dye. The LFIAs employing these substrates outperform conventional substrates and achieve an unprecedented sub-ng/mL limit of detection for Human IgG. The new substrates offer substantial cost savings compared to the commercially available gold nanoparticle-based LFAs, making them a compelling choice for point-of-care diagnostics. We have demonstrated the use of these substrates in detecting Human IgG as a model analyte, and the results indicate that LFIAs employing these substrates can detect Human IgG at 0.2 ng/mL, significantly surpassing reported sensitivities in the literature.

This study provides a promising alternative to conventional substrates and has the potential to improve the sensitivity of LFAs in point-of-care diagnostics.

Suyash Gairola

Title: Tactile friction under boundary lubrication: Surfactants and their propensity to reduce fingertip friction

Abstract:
While holding any object, there is an active interaction between our fingertips and the object’s surface. Both the normal and the frictional load applied by the human fingers play an essential role in this tactile exploration. The system under study can be generalized, and the study’s goal is to investigate friction between a deformable patterned soft substrate (Elastic modulus ≈1MPa) and a stiffer substrate in the presence of boundary lubrication. Coefficient of friction (COF) values were calculated using the human finger for different lubricating solutions and different substrates. All the measurements were made on an in-house developed strain gauge-based force sensor, capable of measuring both the normal and the frictional force simultaneously and independently. The results indicate that adding a small quantity of lubricating solution between the finger and the substrate drastically reduces friction. Surfactant solutions like Sodium
dodecyl sulphate (SDS) facilitates boundary lubrication and gives COF values of about 0.2 for high bulk concentrations. The COF between the finger and the glass substrate varies with changing the bulk concentration of the surfactant. The adsorption of the surfactant onto the surface is responsible for a decaying nature of the COF vs time profile.

Ankit Kumar Verma

Title: In Silico Investigation of Molybdenum Oxide as a Potential Catalyst for Electrochemical Oxygen Evolution

Abstract:
Hydrogen (H2) has emerged as a promising alternative to fossil fuels. Its applications extend far beyond fuel cells, encompassing many industries such as fertilizer manufacturing, metal processing, and steam reforming. However, efficiently producing green and clean H2 at a commercial scale to meet the growing demand represents a crucial challenge. The electrochemical water-splitting method offers a promising way of enabling the conversion of renewable electricity into H2, thereby facilitating effective energy storage and conversion. The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are fundamental half-cell reactions involved in water splitting. Notably, the OER exhibits kinetically sluggishness due to the presence of four proton-coupled electron transfer steps, which hinder both the advancement and scalability of water-splitting technology. Developing and exploring stable, economically viable, and highly efficient catalysts for the OER beyond the conventional iridium and ruthenium-based oxide catalysts is of utmost significance in generating environmentally friendly H2. Therefore, our work focused on exploring transition metal-based catalysts that could serve as viable alternatives to Ru, and Ir-based catalysts in terms of cost, activity, and stability. Specifically, we present our findings on molybdenum oxide (MoO3) and doped MoO3 catalysts for the OER. Density functional theory is utilized to analyze the energetics of intermediates in the OER mechanism. This approach allowed us to identify the most favorable active site and dopant that can significantly enhance the OER activity of MoO3. Among all the explored dopants (iron, nickel, manganese, and cobalt) and active sites (symmetric oxygen, asymmetric oxygen, terminal oxygen, and metal), the Co-doped MoO3 catalyst demonstrated the highest OER activity at the symmetric oxygen active site. The findings are rationalized using oxidation state changes at the active transition metal centers. Our research primarily centers on using computational methods to explore innovative materials for enhancing the water-splitting technique, ultimately leading to cleaner hydrogen generation.

Anusha Tripathi

Title: Modelling and optimization of Multiphysics Alkaline Electrolyzer

Abstract:
The current challenge of 21st century is to deal with the growing energy demand and controlling the rapid climate change. However, hydrogen is found more versatile energy source which can be used as clean, green and sustainable alternative of fossil-fuel. Electrolyzers are leading technology for production of Hydrogen. and this project aims to model and optimize the Alkaline water electrolyzer using Machine learning or COMSOL (Multiphysics software).

Vimal Ruhela

Title: COMSOL multiphysics modelling of CO2 electrolysis.

Abstract:
My MTech project centers around developing a multiscale model to mitigate CO2 emissions. The core of my approach involves employing an electrochemical catalyst to facilitate the production of CO and other industrially significant compounds from CO2. I intend to design and construct a comprehensive Multiphysics model using the Finite element method to accomplish this ambitious goal. This intricate model will seamlessly integrate electrochemical processes and transport equations on a continuum scale, ultimately paving the way for a more sustainable and environmentally conscious industrial landscape.

Soumya Mittal

Title: Trade-off between the anti-viral and the vaccinal effect of passive immunisation

Abstract:
Passive immunization (PI) with antiviral antibodies can induce two major effects. Its classical effect is antiviral drug-like: it reduces the viral load. Recent studies have highlighted a second, vaccinal effect of PI, where it modulates the endogenous humoral response, leading to an increase in the affinity of the antibodies produced for their target antigen. Here, using an in silico germinal centre (GC) model, we elucidate a trade-off between these effects. The vaccinal effect has been argued to arise from the preferential presentation of immune complexes formed by high affinity administered antibodies, which increase B cell selection stringency in the GC. Increasing passively administered antibody dosage or their affinity for the target antigen could increase the immune complex formation and enhance GC output. Beyond a point, however, a strong antiviral effect could drive a substantial reduction in the target antigen, and hence immune complexes, lowering antigen availability in the GC. This lack of adequate antigen could cause the GC to be extinguished. An optimum dosage thus exists at which the germinal centre output is maximum. We constructed detailed discrete-generation Wright-Fisher simulations of the GC reaction to describe affinity maturation against a non-mutating target antigen. In an advance over previous formalisms, we coupled the GC reaction to within-host antigen dynamics, so that the antiviral and vaccinal effects could be explicitly and simultaneously described. The simulations predicted the existence of the trade-off between the two effects. Performing comprehensive parameter scans, we predicted PI dosing protocols that maximized the humoral response.

Isha Misra

Title: Dynamics of spherical particles in the presence of shear and oscillating magnetic field

Abstract:
The dynamics of a spherical particle in the presence of shear and an oscillating magnetic field in the shear plane, is defined in terms of the dimensionless numbers 𝜔∗, which is the ratio of the magnetic field frequency and the shear rate, and Σ, which is the ratio of the magnetic and hydrodynamic torques. As the magnetic field strength is increased, Σ increases and the behavior of the particle evolves from close to Jeffery orbit like to synchronized rotations in the shear plane. When 𝜔∗<1/2, this phase locking displays Arnol’d tongue at 𝜔∗=1/(2 𝑛0), where 𝑛0 is an odd integer, and then discontinuous change in the rotation number. The hydrodynamic torque exerted by the particle on the fluid changes as the behavior of rotation of the particle changes.

Satvik Verma

Title: A Pore Size Distribution based model to predict spatiotemporal variations of Saturation in paper microfluidic channels

Abstract:
The design and fabrication of paper-based microfluidic devices is critically dependent on modeling fluid flow through porous paper membranes. A commonly observed phenomenon is partial saturation, i.e., regions of the paper membrane not being filled completely due to pores of different sizes. The most comprehensive model till date of partial saturation during wicking flow in paper is Richard’s equation. However, the nonlinear nature of this equation and the requirement for numerical solvers for its solution make it largely inaccessible to the paper microfluidics and lateral flow assay community. Moreover, the parameters used in Richard’s equation often need to be tweaked (or assumed) to match experimental data. This necessitates the need for a simple and appropriate model of partial saturation in paper membranes, easily usable by the wider research community. In the current work, we present an approach to model paper membranes as a bundle of parallel capillaries whose radii follow a two-parameter log-normal distribution. Application of the Washburn equation to the bundle provides a distribution of fluid fronts, which can be used to calculate saturation. Using this approach, we developed the first analytical expression for spatiotemporal variation of saturation in 1D wicking flow. Experimentally obtained data for spatiotemporal saturation for four different paper materials were fit to this analytical model to obtain parameters for each material. Results obtained from this analytical model match both experimental data as well as numerical results obtained from the Richards equation model well. The availability of an analytical expression for partial saturation in wicking flow promises to significantly increase access to such modelling among the wider research community.

Thejassvi Madireddi

Title: Modelling of Thermal Energy Storage Systems

Abstract:
According to IEA, industrial heat makes up almost one-fifth of global energy consumption and constitutes majority of the direct industrial CO2 emitted each year, as the industrial heat originates from fossil-fuel combustion. In order to decarbonize the heat demand, electrification integrated with renewable sources is one of the most feasible technological solutions. Thermal energy storage can play a key role in improving the overall economics by storing excess energy during high renewable production. In this work, we studied material aspect by performing multi-physics simulations of a phase change material and system aspect by developing a system level model of a two tank molten salt storage system.

Ramya Boddepalli

Title: Integrative analysis of innate immune response to Flavivirus infection

Abstract:
Viral infections caused by RNA viruses, particularly flaviviruses, affect millions annually and can cause severe morbidity and mortality in some cases. The innate immune system is the first line of defense against viruses. Pathogen recognition receptors (PRRs) present in all cells are essential in manifesting a robust antiviral response by signaling the production of a diverse range of cytokines and interferon-stimulating genes (ISGs). These cytokines and other innate immune cells (e.g., Natural killer (NK) cells) also play a major in activating the more specific adaptive immune response by priming the T cells. When induced, interferon-stimulating genes (ISGs) act at various stages of a viral life cycle, preventing it from creating a successful infection in a cell. This work aims to study these pathways in flavivirus infection, using a mathematical model complemented with experiments to identify potential bottlenecks to curb viral infections. We have integrated several individual pathways to set up an intracellular immune response model coupled with the RNA virus life cycle. Our model simulations corroborate a general understanding of how the innate immune response curbs the infection through the action of ISGs.

Shivam Tiwari

Title: Role of Binding Site Specificity in the Disaggregation of Abeta-42 Fibrils via Synthetic Paratope

Abstract:
Amyloid-β (Aβ) fibrils are the characteristic hallmark of Alzheimer’s disease(AD), and most drug development approaches for AD are focused on preventing and reversing the formation of these fibrillar aggregates. Previous studies show that synthetic antibodies have demonstrated great potential to inhibit the Aβ aggregation and disaggregate the preformed Aβ fibrils. Here, we perform explicit molecular dynamics(MD) simulation to elucidate the molecular mechanism of disaggregation of preformed LS-shaped Aβ 42 protofibril with a flex-
ible, hairpin-like synthetic paratope (SP) which, in a recent experimental study, has shown promising results. Our simulations demonstrate various potential binding sites for SP on Aβ 42 protofibril. However, binding of SP at the amyloidogenic core region (KLVFF) shows
pronounced structural disruption of Aβ 42 protofibril. Our results show heavy loss of β sheet content, dismantling of K28-A42 salt bridge, and destruction of key contacts in the hydrophobic cores of Aβ 42 protofibril in the presence of SP. We found the aromatic and hydrophobic
residues of Aβ 42 protofibril participating primarily in the binding with SP. Also, we found that π − π stacking and hydrophobic interactions are the most dominant mode of interaction between SP and Aβ 42 protofibril. This work provides a detailed atomistic perspective on the
Aβ 42 protofibril disaggregation mechanism with SP, and the findings can help develop more effective drugs for AD in the future.

Aditya Upasani

Title: 25-Hydroxycholesterol prevents the lytic activity of the pore-forming toxin Cytolysin-A

Abstract:
The plasma membrane’s function as a barrier to the outer environment is constantly challenged by many pathogens. Bacteria and viruses try to bypass or puncture the cell membrane to gain cell entry. Mammalian plasma membrane recognition by pathogens is driven by receptor or cell membrane specific lipid binding. One of the ways in which cells respond to this is by modifying accessible cholesterol levels in the plasma membrane. Generation of an oxidised form of cholesterol, 25-hydroxycholesterol (25HC) triggers depletion of cholesterol from the plasma membrane. Here we asked whether 25HC can have a direct role to play against these membrane attacks? For this we investigate how 25HC prevents pore formation by bacterial toxin, Cytolysin-A (ClyA) on lipid membranes. ClyA is an α-pore-forming toxin whose lytic activity is enhanced in the presence of cholesterol. Dye-leakage experiments with small unilamellar vesicles show that addition of 25HC to cholesterol-containing vesicles reduces the pore-forming activity of ClyA. Single particle tracking experiments on supported lipid bilayers showed that binding of ClyA is unaffected in the presence of 25HC. However, we see an increased membrane insertion of ClyA in the presence of 25HC, which is contradictory to the observed activity reduction. Molecular dynamics simulations indicate that 25HC has a higher affinity towards ClyA pores than cholesterol. We find, using transmission electron microscopy, that ClyA forms pore-like structures even when 25HC is added to cholesterol-containing vesicles. We extract these structures using a mild detergent to characterise the differences between them. 2D-class averaging of the pore-like structures from vesicles containing 25HC shows that a majority of these pore-like structures have their central region blocked. This indicates that ClyA can assemble into ring-like structures but it is unable to form a fully functioning trans-pore in the presence of 25HC.

Arunachalam S

Title: Breakage of buoyant drops using obstructions

Abstract:
Drop impact onto flat and sharp substrates have been studied from the perspective of maximum extension and contact time in liquid-air systems. In our study, we aim to break buoyant oil drops in a water column as a means for size reduction without expending energy. Experiments were conducted by letting oil drops impact carefully placed wedge like obstructions. We observe outcomes like non-breaking, breaking (symmetrically and asymmetrically) along with drops breaking and moving onto the same side of obstruction. The experiments seem to suggest that the outcome of the drop impact depends on impact velocity, off-center impact position and shape of the obstruction itself for the small parameter space explored.

Rajalakshmi Chockalingam
Title: Understanding the role of Sars-cov viral peptide in fusion process of cell membrane

Abstract:
The thorough investigation of membrane fusion process is one of the main targets for the development of novel antiviral therapies to combat COVID-19. The mechanism adopted by viral peptide on host cell membranes has been studied using molecular simulation studies. This work primarily focus on the strategies adopted by peptide and its influence on the membrane bilayer properties. The structural and dynamic variations shown by the membranes are discussed at the molecular level. The role of membrane compositons on the response mechanism to peptides are addressed in detail.

Rupesh Pawar
Title: Reactive Inkjet-Printed Metasurface Lens Antennas: Fabrication, Characterization, and Process Optimization

Abstract:
This research explores the fabrication, characterization, and process optimization of reactive inkjet-printed metasurface lens antennas for enhanced communication technologies. The study focuses on a cost-effective approach utilizing a low-cost HP Deskjet 1212 inkjet printer to produce highly conducting silver nanostructures on paper substrates. The metasurface array, consisting of a 5×5 arrangement of square conducting silver unit cells, is crafted on a paper substrate, demonstrating advantages such as easy fabrication, lightweight, and planar configuration. The fabrication process involves a novel print-expose-develop technique, eliminating the need for ink formulation and subsequent sintering.Material characterization encompasses dimensional analysis, silver loading assessment, electrical conductivity analysis, and morphology examination. Results indicate precise dimensional accuracy within the λ/100 limit and a direct relationship between the number of printing cycles and deposition thickness and silver loading. The fabricated antenna undergoes comprehensive evaluation through measurements of reflection coefficients (S11) and gain enhancement, showcasing the positive impact of increased silver loading on electrical performance. The study establishes a promising avenue for the scalable and cost-effective production of metasurface lens antennas through reactive inkjet printing, addressing challenges associated with traditional manufacturing methods.

Vishwesh Rai
Title: Unravelling Early Stage Dynamics of Cytolysin A – Lipid Membrane Interactions

Abstract:
The pore-forming toxins (PFTs) released by pathogenic bacteria1 disrupt the cell membranes by pore formation leading to osmotic imbalance due to selective ion transfer. The two broad classes of the PFTs – α-PFTs and β-PFTs – based on the mechanism of pore formation employed by the PFT, differ in the secondary structures of their transmembrane pore domains. In this context, one of the most commonly studied α-PFT – Cytolysin A – comprising a five α-helix bundle and a β-hairpin, transitions from inactive monomer to active protomeric form upon membrane association. The monomer employs the hydrophobic β-tongue region as the starting point for the assembly process upon membrane binding. Benke et al. proposed an off-pathway reaction model for the formation of the potent form of the monomer. The model proposed that the addition of DDM at its CMC to the soluble monomers triggers the formation of protomers, along with the reversible formation of a molten-globule-like intermediate. Although the presence of the non-native intermediates at the early stage of the assembly pathway is evident, very little is known about the role of these intermediate species in its assembly, host membrane pore formation, and bilayer remodeling. Researchers believe that the protein behaves identically in both environments – in detergents and in lipid membranes. Here, we measured the activity of the monomer, the intermediate, the protomer, the pre-pore, and the pore forms of ClyA using fluorescence microscopy. We tracked the detergent-triggered temporal evolution in the helicity of these forms via circular dichroism, FTIR and FRET measurements. Recent studies have established the role of cholesterol in the assembly of the ClyA on the membrane as cholesterol stabilizes the intermediates by interacting with two protomers and enhancing pore formation. To account for the effect of phase separation in lipid bilayers on the activity of ClyA, we investigated the ClyA actions on bilayers by varying the lipid compositions. Interestingly, our results with DDM-induced intermediates showed that the bilayer components greatly influence membrane disruption activities ClyA species during the assembly pathway. However, all our studies using lipid membranes essentially pointed towards prevalence of entirely different pathway, for which further studies are going on.

Gautam Vatsa

Title: The implications of shear dilatancy in slow granular flows

Abstract:
We first examine the velocity and density fields in a granular medium composed of polydisperse circular disks in a quasi-2D annular shear device. By video imaging the flow in the dense, slow flow regime, we extract the radial variation of the azimuthal velocity u_θ and the area fraction φ_a in the steady state. Most continuum models for slow granular flow assume the granular material to be incompressible. Our experimental results question the validity of this assumption. A recently proposed non-local continuum model by Dsouza and Nott (J. Fluid Mech., 2020) incorporates shear dilatancy (change in density due to shear). We applied the model to the problem of quasi-2D annular shear flow and found an excellent agreement between the model predictions and the experimental data. We next apply the model to the problem of a 2D plane shear in the presence of gravity and show that dilatancy in combination with gravity can lead to sustained secondary flows. Krishnaraj and Nott (Nature Communication, 2016) were the first to show this phenomenon through their discrete particle simulations. Our results are in qualitative agreement with the results of Krishnaraj and Nott.

Dhondi Pradeep

Title: Water and Ion Transport Through Functionalized Nanopores 2D Materials

Abstract:
Two-dimensional (2D) materials, consisting of a few atomic layers, are extensively researched for various applications, including seawater desalination. These materials can be engineered to contain nanopores, whose size, shape, and chemical character significantly affect the material’s performance as a membrane. Accordingly, nanoporous 2D materials and their functionalized forms have emerged as promising membrane materials for water desalination applications due to their remarkable mechanical strength, high water permeance, and excellent selectivity. In this regard, recent studies have demonstrated that the chemical functionalization of nanopores in graphene (for example, by adding hydroxyl groups) can enhance water permeability and provide 100% rejection of salt ions [1]. In this work, we examine both functionalized and unfunctionalized nanoporous hexagonal boron nitride (hBN) membranes for desalination with different salt solutions via molecular dynamics (MD) simulations. Our MD simulations reveal a significantly higher water permeance through hBN membranes, as compared to the typical water permeance of current polymeric membranes, which is around 0.1 L.cm-2.day-1.MPa-1. We find that functionalized nanopores in hBN (with hydrogen atoms at the edges) demonstrate a slightly lower water flux and higher overall ion rejection, as compared to unfunctionalized nanopores. Moreover, by studying ions of various charges and sizes, our study unravels the complex interplay between ion characteristics and membrane functionalization and their effects on the desalination performance of nanoporous hBN membranes. These findings have significant implications for the advancement of membrane technology, as they offer valuable insights that can be leveraged to design improved membranes for more efficient water desalination processes.