Tata Institute of Fundamental Research

About: Tata Institute of Fundamental Research is a education organization based out in Mumbai, Maharashtra, India. It is known for research contribution in the topics: Magnetization & Large Hadron Collider. The organization has 7786 authors who have published 21742 publications receiving 622368 citations. The organization is also known as: TIFR.

How and when does an anticancer drug leave its binding site

Abstract: Obtaining atomistic resolution of drug unbinding from a protein is a much sought-after experimental and computational challenge We report the unbinding dynamics of the anticancer drug dasatinib from c-Src kinase in full atomistic resolution using enhanced sampling molecular dynamics simulations We obtain multiple unbinding trajectories and determine a residence time in agreement with experiments We observe coupled protein-water movement through multiple metastable intermediates The water molecules form a hydrogen bond bridge, elongating a specific, evolutionarily preserved salt bridge and enabling conformation changes essential to ligand unbinding This water insertion in the salt bridge acts as a molecular switch that controls unbinding Our findings provide a mechanistic rationale for why it might be difficult to engineer drugs targeting certain specific c-Src kinase conformations to have longer residence times

On the Rate of Neutron Star Binary Mergers from Globular Clusters

Abstract: The first detection of gravitational waves from a neutron star - neutron star (NS-NS) merger, GW170817, and the increasing number of observations of short gamma-ray bursts (SGRBs) have greatly motivated studies of the origins of NS-NS and neutron star - black hole (NS-BH) binaries. We calculate the merger rates of NS-NS and NS-BH binaries from globular clusters (GCs) using realistic GC simulations with the \texttt{CMC} cluster catalog. We use a large sample of models with a range of initial numbers of stars, metallicities, virial radii and galactocentric distances, representative of the present-day Milky Way GCs, to quantify the inspiral times and volumetric merger rates as a function of redshift, both inside and ejected from clusters. We find that over the complete lifetime of most GCs, stellar BHs dominate the cluster cores and prevent the mass segregation of NSs, thereby reducing the dynamical interaction rates of NSs so that at most a few NS binary mergers are ever produced. We estimate the merger rate in the local universe to be $\sim\rm{0.02\,Gpc^{-3}\,yr^{-1}}$ for both NS-NS and NS-BH binaries, or a total of $\sim 0.04$~Gpc$^{-3}$~yr$^{-1}$ for both populations. These rates are about 5 orders of magnitude below the current empirical merger rate from LIGO/Virgo. We conclude that dynamical interactions in GCs do not play a significant role in enhancing the NS-NS and NS-BH merger rates.

Femtosecond laser written channel waveguides in tellurite glass

Abstract: We have made and characterized a new, erbium-doped tellurite glass that has high glass transition temperature. Addition of phosphate is found to increase the phonon energy. The peak emission cross section is 6 × 10-21 cm2 at 1537 nm and the fluorescence lifetime of the 4I13/2-4I15/2 transition is 4.1 ms. We have written 2-D channel waveguides in this glass using focused, 45-fs pulses from an amplified Ti:sapphire laser at different laser energies and writing speeds. Migration of atoms towards the periphery of the waveguides occurs, leading to refractive index changes. Channels show waveguiding at 1310 nm which is promising for the fabrication of integrated lasers and broadband amplifiers.