Experimental observation of the origin and structure of elastoinertial turbulence.

Turbulence generally arises in shear flows if velocities and hence, inertial forces are sufficiently large. In striking contrast, viscoelastic fluids can exhibit disordered motion even at vanishing inertia. Intermediate between these cases, a state of chaotic motion, "elastoinertial turbulence" (EIT), has been observed in a narrow Reynolds number interval.

Nonlinear hydrodynamic instability and turbulence in pulsatile flow.

Pulsating flows through tubular geometries are laminar provided that velocities are moderate. This in particular is also believed to apply to cardiovascular flows where inertial forces are typically too low to sustain turbulence. On the other hand, flow instabilities and fluctuating shear stresses are held responsible for a variety of cardiovascular diseases.

Stokes flow analogous to viscous electron current in graphene.

Electron transport in two-dimensional conducting materials such as graphene, with dominant electron-electron interaction, exhibits unusual vortex flow that leads to a nonlocal current-field relation (negative resistance), distinct from the classical Ohm's law. The transport behavior of these materials is best described by low Reynolds number hydrodynamics, where the constitutive pressure-speed relation is Stoke's law. Here we report evidence of such vortices observed in a viscous flow of Newtonian fluid in a microfluidic device consisting of a rectangular cavity-analogous to the electronic system.

Elastic Alfven waves in elastic turbulence.

Speed of sound waves in gases and liquids are governed by the compressibility of the medium. There exists another type of non-dispersive wave where the wave speed depends on stress instead of elasticity of the medium. A well-known example is the Alfven wave, which propagates through plasma permeated by a magnetic field with the speed determined by magnetic tension.

AB corroles: Fluorescence signaling systems for sensing fluoride ions.

Four free base corroles, 1-4, AB, (where A = nitrophenyl, and B = pentafluorophenyl, 2, 6-difluoro, 3, 4, 5-trifluoro and 4-carboxymethylphenyl group) have been synthesized, characterized and demonstrated as excellent chemosensor for the detection of fluoride ions selectively in toluene solution. The reported corroles shows highest quantum yield in free base form of porphyrinoid systems so far. All these corrole, 1-4, have the excellent ability to sense fluoride ion.

Is there a common pathogenesis in aggressive periodontitis & ankylosing spondylitis in HLA-B27 patient?

HLA-B27 is having strong association to ankylosing spondylitis (AS) and other inflammatory diseases collectively known as seronegative spondyloarthropathy. In literature, although the evidence for association between AS and periodontitis as well as AS and HLA-B27 are there but the association of aggressive periodontitis in HLA-B27 positive patient with AS are not there. We hypothesize that there may be a common pathogenesis in aggressive periodontitis and ankylosing spondylitis in HLA-B27 patient.

Oscillatory elastic instabilities in an extensional viscoelastic flow.

Dilute polymer solutions are known to exhibit purely elastic instabilities even when the fluid inertia is negligible. Here we report the quantitative evidence of two consecutive oscillatory elastic instabilities in an elongation flow of a dilute polymer solution as realized in a T-junction geometry with a long recirculating cavity. The main result reported here is the observation and characterization of the first transition as a forward Hopf bifurcation resulted in a uniformly oscillating state due to breaking of time translational invariance.

Multiscale flow in an electro-hydrodynamically driven oil-in-oil emulsion.

Efficient mixing strategies in a fluid involve generation of multi-scale flows which are strongly suppressed in highly viscous systems. In this work, we report a novel form of multi-scale flow, driven by an external electric field, in a highly viscous (η∼ 1 Pa s) oil-in-oil emulsion system consisting of micron-size droplets. This electro-hydrodynamic flow leads to dynamical organization at spatial scales much larger than that of the individual droplets.

Large scale arrays of tunable microlenses.

We demonstrate a simple and robust method to produce large 2-dimensional and quasi-3-dimensional arrays of tunable liquid microlenses using a time varying external electric field as the only control parameter. With increasing frequency, the shape of the individual lensing elements (~40 μm in diameter) evolves from an oblate (lentil shaped) to a prolate (egg shaped) spheroid, thereby making the focal length a tunable quantity. Moreover, such microlenses can be spatially localized in desired configurations by patterning the electrode.

Self organization of exotic oil-in-oil phases driven by tunable electrohydrodynamics.

Self organization of large-scale structures in nature - either coherent structures like crystals, or incoherent dynamic structures like clouds - is governed by long-range interactions. In many problems, hydrodynamics and electrostatics are the source of such long-range interactions. The tuning of electrostatic interactions has helped to elucidate when coherent crystalline structures or incoherent amorphous structures form in colloidal systems.

Amorphous to amorphous transition in particle rafts.

Space-filling assemblies of athermal hydrophobic particles floating at an air-water interface, called particle rafts, are shown to undergo an unusual phase transition between two amorphous states, i.e., a low density "less-rigid" state and a high density "more-rigid" state, as a function of particulate number density (Φ).

Desorption to delamination: dynamics of detachment in a colloidal thin film.

Colloidal thin films of varying rigidity detaching from a substrate under an electric field induced stress are studied by video microscopy. For soft films, the process of detachment shows single-particle dynamics, analogous to desorption. For rigid films, a collective delamination spanning hundreds of particles occurs.

Combined bladder exstrophy and epispadias repair.

A 2-year-old male child of exstrophy-epispadias complex presented to us. He had not received any treatment at the time of presentation. It was decided to perform a combined bladder exstrophy and epispadias repair under general anaesthesia.

Multicentric GCT of tarsal bones in an immature skeleton: a case report with review of literature.

Multicentric giant cell tumor of the foot is rare. Multicentric giant cell tumor of the tarsal bones in an immature skeleton is unheard of. We report a case of synchronous multicentric giant cell tumor involving the talus and calcaneum in a 14-year-old boy with open epiphyseal plate for its rarity and successful treatment by curettage and synthetic bone graft.