468 research outputs found
Femtosecond Photoexcited Carrier Dynamics in Reduced Graphene Oxide Suspensions and Films
We report ultrafast response of femtosecond photoexcited carriers in single
layer reduced graphene oxide flakes suspended in water as well as few layer
thick film deposited on indium tin oxide coated glass plate using pump-probe
differential transmission spectroscopy at 790 nm. The carrier relaxation
dynamics has three components: ~200 fs, 1 to 2 ps, and ~25 ps, all of them
independent of pump fluence. It is seen that the second component (1 to 2 ps)
assigned to the lifetime of hot optical phonons is larger for graphene in
suspensions whereas other two time constants are the same for both the
suspension and the film. The value of third order nonlinear susceptibility
estimated from the pump-probe experiments is compared with that obtained from
the open aperture Z-scan results for the suspension.Comment: 4 pages, 4 figures, to appear in International Journal of Nanoscience
(IJN), 201
Femtosecond carrier dynamics and saturable absorption in graphene suspensions
Nonlinear optical properties and carrier relaxation dynamics in graphene,
suspended in three different solvents, are investigated using femtosecond (80
fs pulses) Z-scan and degenerate pumpprobe spectroscopy at 790 nm. The results
demonstrate saturable absorption property of graphene with a nonlinear
absorption coefficient, , of ~2 to 9x10^-8 cm/W. Two distinct time scales
associated with the relaxation of photoexcited carriers, a fast one in the
range of 130-330 fs (related to carrier-carrier scattering) followed by a
slower one in 3.5-4.9 ps range (associated with carrier-phonon scattering) are
observed.Comment: 3 pages, 2 figures, 2 table
Detection of Sugar-Lectin Interactions by Multivalent Dendritic Sugar Functionalized Single-Walled Carbon Nanotubes
We show that single walled carbon nanotubes (SWNT) decorated with sugar
functionalized poly (propyl ether imine) (PETIM) dendrimer is a very sensitive
platform to quantitatively detect carbohydrate recognizing proteins, namely,
lectins. The changes in electrical conductivity of SWNT in field effect
transistor device due to carbohydrate - protein interactions form the basis of
present study. The mannose sugar attached PETIM dendrimers undergo charge -
transfer interactions with the SWNT. The changes in the conductance of the
dendritic sugar functionalized SWNT after addition of lectins in varying
concentrations were found to follow the Langmuir type isotherm, giving the
concanavalin A (Con A) - mannose affinity constant to be 8.5 x 106 M-1. The
increase in the device conductance observed after adding 10 nM of Con A is same
as after adding 20 \muM of a non - specific lectin peanut agglutinin, showing
the high specificity of the Con A - mannose interactions. The specificity of
sugar-lectin interactions was characterized further by observing significant
shifts in Raman modes of the SWNT.Comment: 12 pages, 3 figure
Calculation and experimental verification of m drop in tsia electrodes of chlor-alkali cells
A computer program to analyss the current distribution in a chlor-alkali cell using Titanium Substrate
Insoluble Anode (TSIA) has baen developed. The program takes into account the polarisation resistance
characteristics of anode and camode and the electrolyte resistance, in a d d i i to anode nodal resistance.
The results are compared with the experimental data
A Study on “Security of Cyber-Physical Systems in the Cloud”
The existing security models are built with certain assumptions. The solutions like distributed accountability, provable data possession (PDP), Third Party Auditing (TPA) and so on are secure as long as the assumptions hold true. To ensure fool proof security for cloud storage security little research has been made on quantum key cryptography. Since the quantum key distribution is unconditionally secure, we propose a new scheme known as Cloud QKDP (Quantum Key Distribution Protocol for Cloud Computing) which exploits the benefits of quantum mechanisms to secure cloud storage and data dynamics. We consider a case study in which three parties such as cloud server, data owner and trusted client have provably secure communications with our proposed scheme which uses random oracle model. Our empirical study revealed mixture of success and failure rates with private and public clouds respectively
4-(4-Chlorophenyl)-N-[(E)-4-(dimethylamino)benzylidene]-1,3-thiazol-2-amine
The title compound, C18H16ClN3S, adopts an extended molecular structure. The thiazole ring is inclined by 9.2 (1) and 15.3 (1)° with respect to the chlorophenyl and 4-(dimethylamino)phenyl rings, respectively, while the benzene ring planes make an angle of 19.0 (1)°. A weak intermolecular C—H⋯π contact is observed in the crystal structure
Comparison of methods for evaluating the suitability of Vertisols for Gossypium hirsutum (Bt cotton) in two contrasting agro-ecological regions
This is the author accepted manuscript. The final version is available from Taylor and Francis (Routledge) via the DOI in this record.Cotton (Gossypium sp.) is a major crop grown under rainfed conditions in Vertisols and associated soils in semi-arid tropical (SAT) regions of Peninsular India. In recent years, cotton productivity has declined due to various biophysical factors including pest and diseases, seasonal water stress soil degradation and poor crop management practices. In this study, we compare two methods for evaluating the suitability of Vertisols for cotton in contrasting two agro-ecological regions viz., sub-humid moist (SHM) region and semi-arid dry(SAD) were characterized. Twelve cotton growing Vertisols (seven from SHM and five from SAD) were evaluated for their suitability for cotton cultivation using soil quality index (SQI) and modified Sys-FAO method. SQIs were calculated using the weighted additive index from transformed scores of selected indicators by principal component analysis. For Sys-FAO method both biophysical and soil characteristics were considered for suitability evaluation. We found that the soils of SHM region were moderately suitable for cotton cultivation with soil moisture as the major limiting factor, whereas the soils of SAD region are marginally suitable due to high exchangeable sodium percentage and poor hydraulic conductivity. From this, it may be concluded that the weighted SQI has better agreement with the cotton yield
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