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71.
Dibakar Sahoo Prosenjit Bhattacharya Hirak Kumar Patra Paulami Mandal Sankar Chakravorti 《Journal of nanoparticle research》2011,13(12):6755-6760
Change of α-helical structure of heme protein (Hb) to a β-sheet and random coil conformation because of the interaction of
glycine capped gold nanoparticles (20–60 nm) as observed from attenuation total reflectance, absorption, Fourier transform
infra red, and Circular Dichroism spectroscopy has been reported in this article. Upon interaction, protein takes a cylindrical
shape of length 12 μm and diameter 0.35 μm as revealed from scanning electron microscopy and transmission electron microscopy.
The Selected-Area Electron beam Diffraction pattern shows change of crystalline structure in GNP to amorphous nature with
the interaction of Hb. 相似文献
72.
Kaushik Pal Uday Narayan Maiti Tapas Pal Majumder Subhas Chandra Debnath 《Applied Surface Science》2011,258(1):163-168
A series of novel wurtzite cadmium sulphide (CdS) nanowires with uniform diameter were synthesized by using a rapid and simple solvothermal route. CdS nano structures with certain morphology could be selectively produced by only varying the concentration of poly ethylene glycol (PEG) as a surfactant in the reaction system with cadmium acetate, sulphur powder and ethelynediamine (EDA). We extensively studied UV-vis absorption spectra, photoluminescence spectra after confirming CdS nanowires with diameter 24-25 nm and length ranging up to several nano meters by field emission scanning electron microscopy (FE-SEM). Therefore we may definitely propose a new formation mechanism of CdS nanowires assisted by PEG with its illustrating optical properties. 相似文献
73.
R. Jangir Tapas GanguliPragya Tiwari S. PorwalHimanshu Srivastava S.K. RaiB.Q. Khattak S.M. Oak 《Applied Surface Science》2011,257(22):9323-9328
β-Ga2O3 nanostructures including nanowires, nanoribbons and nanosheets were synthesized via thermal annealing of gold coated GaAs substrates in N2 ambient. GaAs substrates with different dopants were taken as the starting material to study the effect of doping on the growth and photoluminescence properties of β-Ga2O3 nanostructures. The nanostructures were investigated by Grazing Incident X-ray Diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, Energy Dispersive X-ray Spectroscopy, room temperature photoluminescence and optical absorbance. The selected area electron diffraction and High resolution-TEM observations suggest that both nanowires and nanobelts are single crystalline. Different growth directions were observed for nanowires and nanoribbons, indicating the different growth patterns of these nanostructures. The PL spectra of β-Ga2O3 nanostructures exhibit a strong UV-blue emission band centered at 410 nm, 415 nm and 450 nm for differently doped GaAs substrates respectively. A weak red luminescence peak at 710 nm was also observed in all the samples. The optical absorbance spectrum showed intense absorption features in the UV spectral region. The growth and luminescence mechanism in β-Ga2O3 nanostructures are also discussed. 相似文献
74.
Tapas Debsharma Yusuf Yagci Helmut Schlaad 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(51):18663-18666
The unsaturated bicyclic acetal levoglucosenyl methyl ether was readily obtained from sustainable feedstock (cellulose) and polymerized by cationic ring‐opening polymerization to produce a semicrystalline thermoplastic unsaturated polyacetal with relatively high apparent molar mass (up to ca. 36 kg mol?1) and decent dispersity (ca. 1.4). The double bonds along the chain can undergo hydrogenation and thiol–ene reactions as well as crosslinking, thus making this polyacetal potentially interesting as a reactive functional material. 相似文献
75.
Bikash Sahoo 《Central European Journal of Physics》2010,8(3):498-508
The entrained flow of an electrically conducting non-Newtonian, viscoelastic second grade fluid due to an axisymmetric stretching
surface with partial slip is considered. The partial slip is controlled by a dimensionless slip factor, which varies between
zero (total adhesion) and infinity (full slip). Suitable similarity transformations are used to reduce the resulting highly
nonlinear partial differential equation into an ordinary differential equation. The issue of paucity of boundary conditions
is addressed, and an effective numerical scheme has been adopted to solve the obtained differential equation even without
augmenting the boundary conditions. The important findings in this communication are the combined effects of the partial slip,
magnetic interaction parameter and the second grade fluid parameter on the velocity and skin friction coefficient. It is observed
that in presence of slip, the velocity decreases with an increase in the magnetic parameter. That is, the Lorentz force which
opposes the flow leads to enhanced deceleration of the flow. Moreover, it is interesting to find that as slip increases in
magnitude, permitting more fluid to slip past the sheet, the skin friction coefficient decreases in magnitude and approaches
zero for higher values of the slip parameter, i.e., the fluid behaves as though it were inviscid. 相似文献
76.
Kanoo P Ghosh AC Cyriac ST Maji TK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(1):237-244
A 3D porous Zn(II) metal-organic framework {[Zn(2)(H(2)dht)(dht)(0.5)(azpy)(0.5)(H(2)O)]·4H(2)O} (1; H(2)dht=dihydroxyterphthalate, azpy=4,4'-azobipyridine) has been synthesised by employing 2,5-dihydroxyterephthalic acid (H(4)dht), a multidentate ligand and 4,4'-azobipyridine by solvent-diffusion techniques at room temperature. The as-synthesised framework furnishes two different types of channels: one calyx-shaped along the [001] direction and another rectangle-shaped along the [101] direction occupied by guest water molecules. The dehydrated framework, {[Zn(2)(H(2)dht)(dht)(0.5)(azpy)(0.5)]} (1') provides 52.7% void volume to the total unit-cell volume. The pore surfaces of 1' are decorated with unsaturated Zn(II) sites and pendant hydroxyl groups of H(2)dht linker, thereby resulting in a highly polar pore surface. The dehydrated framework 1' shows highly selective adsorption of CO(2) over other gases, such as N(2), H(2), O(2) and Ar, at 195 K. Photoluminescence studies revealed that compound 1 exhibits green emission (λ(max)≈530 nm) on the basis of the excited-state intramolecular proton-transfer (ESIPT) process of the H(2)dht linker; no emission was observed in dehydrated solid 1'. Such guest-induced on/off emission has been correlated to the structural transformation and concomitant breaking and reforming of the OH···OCO hydrogen-bonding interaction in the H(2)dht linker in 1'/1. 相似文献
77.
A simplified analysis is employed to handle a class of singular integro-differential equations for their solutions 相似文献
78.
Mihir Samantaray Seshadev Sahoo Direndranath Thatoi 《Comptes Rendus Mecanique》2018,346(11):1043-1054
Direct Metal Laser Sintering (DMLS) is one of the leading additive manufacturing processes, which produces complex metallic parts directly from the powder. One of the major problems of this rapid manufacturing process is an inhomogeneous temperature distribution, which leads to residual stress in the build part. Thus, temperature analyses must be performed, to better understand the temperature distribution and sintering behavior of the powder bed with a different laser recipe. In this study, a comprehensive three-dimensional numerical model was developed to understand the temperature distribution during direct metal laser sintering of AlSi10Mg alloy powder. The computer simulation was carried out in ANSYS 17.0 platform. Further, the effect of process parameters such as laser power and scan speed on the temperature distribution and sintering behavior were studied. From the simulation results, it was found that, when the laser power increased from 70 W to 190 W, the maximum temperature of the molten pool increased from 731?°C to 2672?°C, and the molten pool length changed from 0.286 mm to 2.167 mm. A reverse phenomenon was observed with an increase in scan speed. The sintering depth of the powder layer increases significantly from 0.061 mm to 0.872 mm with increasing the applied laser power, but decreased from 0.973 mm to 0.209 mm as a higher scan speed was applied. The developed model helps to optimize the powder layer thickness and minimize the wastage of excess powders during the sintering process. 相似文献
79.
Bamadev Sahoo 《Nonlinear dynamics》2020,99(2):945-979
This paper investigates nonlinear combined parametric transverse vibrations of a traveling viscoelastic beam. The combined parametric excitations originate from the time dependency of axial velocity as well as axial tension. Two parametric excitations are enforced into the system amid the internal resonance. Two-frequency parametric resonance is assumed to be comprised of combination parametric resonance of first two modes due to the time dependency of axial velocity, and the principal parametric resonance of first mode due to the variable tension in the axial direction in the presence of internal resonance for viscoelastic beam is considered for the first time. The higher-order integro-partial differential equation of motion is solved through direct method of multiple scales. Continuation algorithm is employed to explore the stability and various bifurcations of the nonlinear dynamic system. Focus has been made to study the effect of variations of fluctuating tension component, fluctuating velocity component independently and when combined, internal and parametric frequency detuning parameters and damping on the system response. Frequency response equilibrium curves are complex and unique in shapes which are embodied with various bifurcations. Such steady-state behavior is not seen in the existent literature. With variation in fluctuating velocity component, the number of steady-state nontrivial equilibrium curves increases to three and with variation in fluctuating axial tension, they become four. In this process, significant changes in stability, number and position of various bifurcations like supercritical and subcritical pitchfork, Hopf and saddle node are observed. Unlike the previous study, the shape, stability and bifurcations of equilibrium curves under the combined effect of axial velocity and tension closely match with the case of fluctuating axial tension component. The effect of variation in internal and parametric frequency detuning parameter is more realized for second mode compared to first mode. A comparison of the present work with a previous one where axial tension is variable reveals many qualitative and quantitative similarities and dissimilarities. But when compared with earlier work where axial velocity is constant, significant dissimilarities are surfaced. The system displays a wide ranging dynamic behavior including stable periodic, quasiperiodic and unstable chaotic behavior. The numerical computation depicts various nonlinear characteristics and oscillatory behaviors which are not found so far in the existent literature. 相似文献
80.
Flexural gravity wave scattering by multiple articulated floating elastic plates is investigated in the three cases for water of finite depth, infinite depth and shallow water approximation under the assumptions of two-dimensional linearized theory of water waves. The elastic plates are joined through connectors, which act as articulated joints. In the case when two semi-infinite plates are connected through a single articulation, using the symmetric characteristic of the plate geometry and the expansion formulae for wave-structure interaction problem, the velocity potentials are obtained in closed forms in the case of finite and infinite water depths. On the other hand, in the case of shallow water approximation, the continuity of energy and mass flux are used to obtain a system of equations for the determination of the full velocity potentials for wave scattering by multiple articulations. Further, using the results for single articulation and assuming that the articulated joints are wide apart, the wide-spacing approximation method is used to obtain the reflection coefficient for wave scattering due to multiple articulated floating elastic plates. The effects of the stiffness of the connectors, length of the elastic plates and water depth on the propagation of flexural gravity waves are investigated by analysing the reflection coefficient. 相似文献