4,053 research outputs found
Ultra-narrow and widely tunable Mn^(2+) Emission from Single Nanocrystals of ZnS-CdS alloy
Extensively studied Mn-doped semiconductor nanocrystals have invariably
exhibited photoluminescence (PL) over a narrow energy window of width <= 149
meV in the orange-red region and a surprisingly large spectral width (>= 180
meV), contrary to its presumed atomic-like origin. Carrying out emission
measurements on individual single nanocrystals and supported by ab initio
calculations, we show that Mn PL emission, in fact, can (i) vary over a much
wider range (~ 370 meV) covering the deep green-deep red region and (ii)
exhibit widths substantially lower (~ 60-75 meV) than reported so far, opening
newer application possibilities and requiring a fundamental shift in our
perception of the emission from Mn-doped semiconductor nanocrystals.Comment: 5 pages, 5 figure
Oscillation dynamics of embolic microspheres in flows with red blood cell suspensions
Dynamic nature of particle motion in blood flow is an important determinant of embolization based cancer therapy. Yet, the manner in which the presence of high volume fraction of red blood cells influences the particle dynamics remains unknown. Here, by investigating the motions of embolic microspheres in pressure-driven flows of red blood cell suspensions through capillaries, we illustrate unique oscillatory trends in particle trajectories, which are not observable in Newtonian fluid flows. Our investigation reveals that such oscillatory behavior essentially manifests when three simultaneous conditions, namely, the Reynolds number beyond a threshold limit, degree of confinement beyond a critical limit, and high hematocrit level, are fulfilled simultaneously. Given that these conditions are extremely relevant to fluid dynamics of blood or polymer flow, the observations reported here bear significant implications on embolization based cancer treatment as well as for complex multiphase fluidics involving particle
Finding the optimum activation energy in DNA breathing dynamics: A Simulated Annealing approach
We demonstrate how the stochastic global optimization scheme of Simulated
Annealing can be used to evaluate optimum parameters in the problem of DNA
breathing dynamics. The breathing dynamics is followed in accordance with the
stochastic Gillespie scheme with the denaturation zones in double stranded DNA
studied as a single molecule time series. Simulated Annealing is used to find
the optimum value of the activation energy for which the equilibrium bubble
size distribution matches with a given value. It is demonstrated that the
method overcomes even large noise in the input surrogate data.Comment: 9 pages, 4 figures, iop article package include
Sequence sensitivity of breathing dynamics in heteropolymer DNA
We study the fluctuation dynamics of localized denaturation bubbles in
heteropolymer DNA with a master equation and complementary stochastic
simulation based on novel DNA stability data. A significant dependence of
opening probability and waiting time between bubble events on the local DNA
sequence is revealed and quantified for a biological sequence of the T7
bacteriophage. Quantitative agreement with data from fluorescence correlation
spectroscopy (FCS) is demonstrated.Comment: 4 pages, 5 figures, to appear in Physical Review Letter
Ethnobotanical Studies on Dental Hygiene in District Hamirpur, Himachal Pradesh (H.P.), India
The present study was carried out to assess and document ethnobotanical knowledge of plants of District Hamirpur (H.P.) used for dental care, as the area has diverse flora and high ethnobotanical potential. It was found that 32 different plant species belonging to 24 families were used for dental hygiene. The studies reveal the use of 18 trees, 9 shrubs, 2 under-shrubs and 5 herbs for dental hygiene
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