Publications by authors named "Suresh Narayanan"

The construction of highly coherent X-ray sources, combined with next-generation detectors that are larger and faster, has enabled new research opportunities across the scientific landscape. Among the techniques that benefit most from these advancements is X-ray photon correlation spectroscopy (XPCS), where faster acquisition unlocks the ability to study faster dynamics within samples. However, faster acquisition on larger detectors also introduces unprecedented challenges for online data processing and offline data storage.

View Article and Find Full Text PDF

Cocaine seizures in Malaysia suggest that it is being used as a transit point to ship the drug to other destinations. Traces of cocaine found in a wastewater study are the only indirect evidence of its use within the country. This study is the first to present a comprehensive and detailed evidence of cocaine use in Malaysia, albeit based on a small sample of users.

View Article and Find Full Text PDF

Many critical phenomena in soft matter occur at large length scales, necessitating the resolution of their structure and dynamics at low wavenumbers. However, resolving wavenumber-dependent dynamics computationally via molecular dynamics simulations presents significant challenges, as these phenomena span several orders of magnitude in both time and length scales, resulting in high computational costs and memory demands. This work highlights the computational and memory challenges associated with analyzing molecular trajectories in reciprocal space and demonstrates a method to address them.

View Article and Find Full Text PDF

Shear induced frictional networks have been proposed to be responsible for the emergence of discontinuous shear thickening (DST) in complex fluids. However, little experimental evidence exists to support this model directly. Here, using x-ray photon correlation spectroscopy (XPCS), we show the existence of an intrinsic heterodyne feature during shear cessation, which originates from the relative motion of mobile particles against an aggregated or jammed network induced by shear thickening.

View Article and Find Full Text PDF

Linking the macroscopic flow properties and nanoscopic structure is a fundamental challenge to understanding, predicting, and designing disordered soft materials. Under small stresses, these materials are soft solids, while larger loads can lead to yielding and the acquisition of plastic strain, which adds complexity to the task. In this work, we connect the transient structure and rheological memory of a colloidal gel under cyclic shearing across a range of amplitudes a generalized memory function using rheo-X-ray photon correlation spectroscopy (rheo-XPCS).

View Article and Find Full Text PDF

Unlabelled: Medical students often struggle to appreciate the anatomy of the pterygopalatine fossa. This is due to the difficulty in understanding the spatial orientation through textbook diagrams, as well as its deeper location and smaller size in cadaveric specimens. Research has proven that three-dimensional visualization enhances the spatial understanding of anatomy.

View Article and Find Full Text PDF

Nonequilibrium states in soft condensed matter require a systematic approach to characterize and model materials, enhancing predictability and applications. Among the tools, X-ray photon correlation spectroscopy (XPCS) provides exceptional temporal and spatial resolution to extract dynamic insight into the properties of the material. However, existing models might overlook intricate details.

View Article and Find Full Text PDF

Understanding and interpreting dynamics of functional materials in situ is a grand challenge in physics and materials science due to the difficulty of experimentally probing materials at varied length and time scales. X-ray photon correlation spectroscopy (XPCS) is uniquely well-suited for characterizing materials dynamics over wide-ranging time scales. However, spatial and temporal heterogeneity in material behavior can make interpretation of experimental XPCS data difficult.

View Article and Find Full Text PDF

Anatomical images are commonly used in the teaching process to help students understand the spatial orientation of anatomical structures. Previous research has shown that images effectively visualize the relationship between anatomical structures that are difficult to comprehend through verbal or written explanations alone. However, there is a lack of guidelines that specifically address the various methods of utilizing anatomical images and delivering them through multimedia and cognitive load principles.

View Article and Find Full Text PDF

Temperature-dependent x-ray photon correlation spectroscopy (XPCS) measurements are reported for a binary diblock-copolymer blend that self-assembles into an aperiodic dodecagonal quasicrystal and a periodic Frank-Kasper σ phase approximant. The measured structural relaxation times are Bragg scattering wavevector independent and are 5 times faster in the dodecagonal quasicrystal than the σ phase, with minimal temperature dependence. The underlying dynamical relaxations are ascribed to differences in particle motion at the grain boundaries within each of these tetrahedrally close-packed assemblies.

View Article and Find Full Text PDF

Understanding the structural and dynamic properties of disordered systems at the mesoscale is crucial. This is particularly important in organic mixed ionic-electronic conductors (OMIECs), which undergo significant and complex structural changes when operated in an electrolyte. In this study, we investigate the mesoscale strain, reversibility and dynamics of a model OMIEC material under external electrochemical potential using operando X-ray photon correlation spectroscopy.

View Article and Find Full Text PDF

Introduction Activity-based teaching is a widely used pedagogical tool for enhancing anatomy learning. However, involving the learner in experiential activities in lectures is an unexplored area in medical research. The present study aims to determine whether incorporating student experiential activities into lectures impacts student's learning of neuroanatomy.

View Article and Find Full Text PDF

Medical education has ventured into a new arena of computer-assisted teaching powered by artificial intelligence (AI). In medical institutions, AI can serve as an intelligent tool facilitating the decision-making process effectively. AI can enhance teaching by assisting in developing new strategies for educators.

View Article and Find Full Text PDF

Background: Leaves derived from the Kratom () tree have been traditionally ingested for their curative properties by diverse groups of the population including people who use drugs (PWUDs) in Southeast Asia. This study investigated the motives for using kratom among drug-dependent adolescents.

Methods: Eighty adolescents who were undergoing mandatory drug rehabilitation volunteered to participate in this mixed-method, cross-sectional study.

View Article and Find Full Text PDF

The macroscopic rheological response of a colloidal solution is highly correlated with the local microscopic structure, as revealed by an Rheo-SAXS experiment with a high temporal resolution. Oscillatory shear can induce a strain-controlled ordering-to-disorder transition, resulting in a shear-thickening process that is different from the normal shear-thickening behavior that is driven by hydrodynamics and particle friction. We reveal that there is a complex time-dependent kinetics toward structural ordering under different applied strains.

View Article and Find Full Text PDF

To study nanostructures on substrates, surface-sensitive reflection-geometry scattering techniques such as grazing incident small angle X-ray scattering are commonly used to yield an averaged statistical structural information of the surface sample. Grazing incidence geometry can probe the absolute three-dimensional structural morphology of the sample if a highly coherent beam is used. Coherent surface scattering imaging (CSSI) is a powerful yet non-invasive technique similar to coherent X-ray diffractive imaging (CDI) but performed at small angles and grazing-incidence reflection geometry.

View Article and Find Full Text PDF

The underlying microscopic response of filler networks in reinforced rubber to dynamic strain is not well understood due to the experimental difficulty of directly measuring filler network behavior in samples undergoing dynamic strain. This difficulty can be overcome with in situ X-ray photon correlation spectroscopy (XPCS) measurements. The contrast between the silica filler and the rubber matrix for X-ray scattering allows us to isolate the filler network behavior from the overall response of the rubber.

View Article and Find Full Text PDF

We probe the microstructural yielding dynamics of a concentrated colloidal system by performing creep/recovery tests with simultaneous collection of coherent scattering data via X-ray Photon Correlation Spectroscopy (XPCS). This combination of rheology and scattering allows for time-resolved observations of the microstructural dynamics as yielding occurs, which can be linked back to the applied rheological deformation to form structure-property relations. Under sufficiently small applied creep stresses, examination of the correlation in the flow direction reveals that the scattering response recorrelates with its predeformed state, indicating nearly complete microstructural recovery, and the dynamics of the system under these conditions slows considerably.

View Article and Find Full Text PDF

The entanglements of dynamically asymmetric polymer layers influence relaxations of nanoparticles in polymer nanocomposites. In this work, the dynamics of polymer-adsorbed and polymer-grafted nanoparticles in a poly(methyl acrylate) matrix polymer was investigated using X-ray photon correlation spectroscopy (XPCS) to understand the role of chain rigidity and chemical heterogeneities in particle dynamics. Locations of dynamic heterogeneities close to nanoparticles and away from particle surfaces were examined with the comparison of adsorbed and grafted nanoparticles.

View Article and Find Full Text PDF

Liquid mixtures composed of colloidal particles and much smaller non-adsorbing linear homopolymers can undergo a gelation transition due to polymer-mediated depletion forces. We now show that the addition of linear polymers to suspensions of soft colloids having the same hydrodynamic size yields a liquid-to-gel-to-re-entrant liquid transition. In particular, the dynamic state diagram of 1,4-polybutadiene star-linear polymer mixtures was determined with the help of linear viscoelastic and small-angle X-ray scattering experiments.

View Article and Find Full Text PDF

Many researchers have noted that media coverage of drugs can be sensationalized and/or have questionable accuracy. Additionally, it has been alleged that the media often treats all drugs as harmful and can fail to differentiate between different types of drugs. Within this context, the researchers sought to deconstruct how media coverage was similar and/or different according to drug type within a national media outlet in Malaysia.

View Article and Find Full Text PDF

Linking the physics of the relaxation behavior of viscoelastic fluids as they form arrested gel states to the underlying chemical changes is essential for developing predictive controls on the properties of the suspensions. In this study, 3 wt.% laponite suspensions are studied as model systems to probe the influence of salt-induced relaxation behavior arising from the assembly of laponite nanodisks.

View Article and Find Full Text PDF

Bicontinuous structures promise applications in a broad range of research fields, such as energy storage, membrane science, and biomaterials. Kinetically arrested spinodal decomposition is found responsible for stabilizing such structures in different types of materials. A recently developed solvent segregation driven gel (SeedGel) is demonstrated to realize bicontinuous channels thermoreversibly with tunable domain sizes by trapping nanoparticles in a particle domain.

View Article and Find Full Text PDF