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81.
Motivated by experiments on single-headed kinesin KIF1A, we develop a model of intracellular transport by interacting molecular motors. It captures explicitly not only the effects of adenosine triphosphate hydrolysis, but also the ratchet mechanism which drives individual motors. Our model accounts for the experimentally observed single-molecule properties in the low-density limit and also predicts a phase diagram that shows the influence of hydrolysis and Langmuir kinetics on the collective spatiotemporal organization of the motors. Finally, we provide experimental evidence for the existence of domain walls in our in vitro experiment with fluorescently labeled KIF1A. 相似文献
82.
Wen J Chowdhury P Fulton DB Datta A Das K Andreotti AH Petrich JW 《Photochemistry and photobiology》2003,77(1):5-9
Nuclear magnetic resonance measurements indicate that hypericin exists in the same "normal" tautomeric form irrespective of whether the solvent is dimethyl sulfoxide or tetrahydrofuran. This result is discussed in the context of previous experimental and theoretical work. It is concluded that solvent perturbations cannot induce tautomerization in hypericin. 相似文献
83.
84.
Paramita Saha Chowdhury 《Journal of luminescence》2007,124(2):327-332
Here, we have examined the role of capping agent on the optical properties of CdS nanoparticles by steady-state and time-resolved photoluminescence (PL) spectroscopy. The estimated particles sizes are 3.45, 2.5 and 2.39 nm for uncapped, capped with silica (SiO2) and thiosalicylic acid (TSA), respectively. The absorption and emission spectra show a clear blue shift to shorter wavelengths in presence of TSA- and SiO2-capped nanoparticles. It is found that the average decay time 〈τ〉 are 6.24, 4.54 and 2.84 ns for uncapped, capped with SiO2 and TSA nanoparticles, respectively. Our analysis suggests that the hole or the electron is trapped on thiol molecule of TSA or hydroxyl group of SiO2, then radiative recombination of the electron and hole is delayed, resulting in strong quenching of PL efficiency. 相似文献
85.
A pore-scale analysis of nonaqueous phase liquid (NAPL) blob dissolution and mobilization in porous media was presented. Dissolution
kinetics of residual NAPLs in an otherwise water-saturated porous medium was investigated by conducting micromodel experiments.
Changes in residual NAPL volume were measured from recorded video images to calculate the mass transfer coefficient, K and the lumped mass transfer rate coefficient, k. The morphological characteristics of the blobs such as specific and intrinsic area were found to be independent of water
flow rate except at NAPL saturations below 2%. Dissolution process was also investigated by separating the mass transfer into
zones of mobile and immobile water. The fractions of total residual NAPL perimeters in contact with mobile water and immobile
water were measured and their relationship to the mass transfer coefficient was discussed. In general, residual NAPLs are
removed by dissolution and mobilization. Although these two mechanisms were studied individually by others, their simultaneous
occurrence was not considered. Therefore, in this study, mobilization of dissolving NAPL blobs was investigated by an analysis
of the forces acting on a trapped NAPL blob. A dimensional analysis was performed to quantify the residual blob mobilization
in terms of dimensionless Capillary number (Ca
I). If Ca
I is equal to or greater than the trapping number defined as , then blob mobilization is expected. 相似文献
86.
We have calculated the phonon and periodon dispersion relations in IV–VI semi-conducting bulk PbTe and SnTe and their superlattice
structure. The model used here is a one-dimensional lattice which includes harmonic interactions up to second neighbours as
well as on-site nonlinear electron-ion interactions at the anion site. We calculate the phonon and periodon dispersion relations
in bulk and PbTe-SnTe superlattice for the transverse optic and acoustic modes using the transfer matrix method. Our analysis
has predicted correct nature of the folding of acoustic and confinement of optical phonons at various frequency intervals
corresponding to pass and stop bands of the superlattices. 相似文献
87.
Iron Oxide Supported on Al2O3 Catalyst for Methane Decomposition Reaction: Effect of MgO Additive and Calcination Temperature 下载免费PDF全文
Ahmed S. Al‐Fatesh Anis H. Fakeeha Ahmed A. Ibrahim Wasim U. Khan H. Atia R. Eckelt Biswajit Chowdhury 《中国化学会会志》2016,63(2):205-212
Production of hydrogen is a challenging task and have significant impact in the recent scenario. The alumina supported iron oxide nanoparticle synthesized using non‐ionic surfactant Triton‐X was found very effective for steady production of hydrogen through methane decomposition reaction. The high surface area, easily reducible catalyst calcined at 500 °C and 800 °C temperature showed steady activity towards methane decomposition reaction. At a higher reaction temperature there was catalyst deactivation. The doping of MgO facilitated particle growth rendering the poor catalytic activity. The TPR study showed that reducibility of TPR was difficult in presence of MgO additive. The formation of Fe? Mg? Al solid solution confirmed by XRD study was found mainly responsible for the lower catalytic activity. The bamboo‐shaped carbon nanotube formed from 20 % Fe/Al2O3 catalyst which is mainly because of the poor wetting property of quasi‐liquid metal and carbon nanotube. 相似文献
88.
We present the calculation of envelope of boson and of both low-and high-mass fermion production at the end of inflation when
the coherently oscillating inflatons decay into bosons and fermions. We consider three different models of inflation and use
CWKB technique to calculate the envelope to understand the structure of resonance band formation. We observe that though low-mass
fermion production is not effective in preheating because of Pauli blocking, it is quite probable for high-mass fermion to
take part in pre-heating.
相似文献
89.
90.