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61.
Suraj Chandra Sharma Lok Kumar Shrestha Kenichi Sakai Hideki Sakai Masahiko Abe 《Colloid and polymer science》2010,288(4):405-414
We have studied the rheology and structure of a mixed long polyoxyethylene chain phytosterol (PhyEO30) and monoglyceride (monolaurin (ML) or monopalmitin (MP)) surfactants in an aqueous system. Both ML and MP are insoluble
in 10 wt.% PhyEO30 solution at normal room temperature, but their solubility is found to increase with the rise of temperature and an isotropic
solution is formed at higher temperature. A maximum viscosity as a function of temperature appears as ML or MP is solubilized
in the micellar solution of PhyEO30. With increasing temperature, viscosity increases rapidly for higher monoglyceride content and forms viscoelastic solution.
The oscillatory rheological behavior of the viscoelastic solution can be described by Maxwell model at low-frequency region,
which is the typical pattern of entangled wormlike micelles. Upon successive increase in temperature, the viscosity decreases
and ultimately a phase separation occurs. Small-angle X-ray scattering measurements were performed to provide a supportive
structural evidence for the rheological data. 相似文献
62.
van Vugt LK Rühle S Ravindran P Gerritsen HC Kuipers L Vanmaekelbergh D 《Physical review letters》2006,97(14):147401
Semiconductor nanowires of high purity and crystallinity hold promise as building blocks for miniaturized optoelectrical devices. Using scanning-excitation single-wire emission spectroscopy, with either a laser or an electron beam as a spatially resolved excitation source, we observe standing-wave exciton polaritons in ZnO nanowires at room temperature. The Rabi splitting between the polariton branches is more than 100 meV. The dispersion curve of the modes in the nanowire is substantially modified due to light-matter interaction. This finding forms a key aspect in understanding subwavelength guiding in these nanowires. 相似文献
63.
Pakorn Bovonsombat Rameez Ali Chiraphorn Khan Juthamard Leykajarakul Kawin Pla-on Suraj Aphimanchindakul Natchapon Pungcharoenpong Nisit Timsuea Anchalee Arunrat Napat Punpongjareorn 《Tetrahedron》2010,66(34):6928-181
para-Regioselective bromination of phenol and analogues, promoted by p-toluenesulfonic acid, is achieved in high to excellent yields at room temperature with N-bromosuccinimide. Chlorination with N-chlorosuccinimide and catalysed by p-toluenesulfonic acid also gives para-chlorinated phenol analogues in good yields at room temperature. 相似文献
64.
Epichlorohydrin was polymerized using boron trifluoride etherate or stannic chloride as initiators in presence of diols. The molecular weight of the polymer increased with increase in the ratio of epichlorohydrin to the diol in the reaction mixture. The polymers were characterized by IR, proton NMR and 13C NMR analysis. The terminal hydroxyl groups of the polymers were characterized by derivatizing them using trifluoro acetic anhydride and analyzing the resulting ester by NMR. Both primary and secondary hydroxyls were present in the polymer. The primary hydroxyl terminals of the polyepichlorohydrin (PECH) prepared using stannic chloride initiator were twice the amount of that present in the polymer prepared using BF3 etherate initiator. The 13C NMR spectrum of PECH prepared using BF3 etherate indicates that the polymer backbone is rich in H-T diad. Both cationic and co-ordination mechanisms operate during the polymerization in the presence of SnCl4 and the 13C NMR spectrum of the polymer showed more of T-T and H-H sequences. 相似文献
65.
V.L. Rao P.U. Sabeena C. Gopalakrishnan P.V. Ravindran K.N. Ninan 《European Polymer Journal》2004,40(11):2645-2651
Polyether ether ketone and polyether ether ketone copolymers were prepared by the nucleophilic substitution reaction of 4,4′-difluorobenzophenone with hydroquinone and with varying mole proportions of hydroquinone and methyl hydroquinone using sulfolane solvent in the presence of anhydrous K2CO3. The polymers were characterised by different physico-chemical techniques. The crystallinity of the polymers was found to decrease with increase in concentration of the methyl hydroquinone units in the polymer. Thermogravimetric studies showed that all the polymers were stable upto 430 °C with a char yield above 49% at 900 °C in N2 atmosphere. The glass transition temperature was found to increase and the crystalline melting temperature and activation energy were found to decrease with increase in concentration of the methyl hydroquinone units in the polymer. 相似文献
66.
S. S. Ravindran 《国际流体数值方法杂志》1997,25(2):205-223
We study the numerical solution of optimal control problems associated with two-dimensional viscous incompressible thermally convective flows. Although the techniques apply to more general settings, the presentation is confined to the objectives of minimizing the vorticity in the steady state case and tracking the velocity field in the non-stationary case with boundary temperature controls. In the steady state case we develop a systematic way to use the Lagrange multiplier rules to derive an optimality system of equations from which an optimal solution can be computed; finite element methods are used to find approximate solutions for the optimality system of equations. In the time-dependent case a piecewise-in-time optimal control approach is proposed and the fully discrete approximation algorithm for solving the piecewise optimal control problem is defined. Numerical results are presented for both the steady state and time-dependent optimal control problems. © 1997 John Wiley & Sons, Ltd. 相似文献
67.
68.
The quantitative impact of NLO-QCD corrections for searches of large and warped extra dimensions at hadron colliders are investigated
for the Drell-Yan process. The K-factor for various observables at hadron colliders are presented. Factorisation, renormalisation
scale dependence and uncertainties due to various parton distribution functions are studied. Uncertainties arising from the
error on experimental data are estimated using the MRST parton distribution functions.
相似文献
69.
Suraj Ravindran Rajesh Langoju Abhijit Patil Pramod Rastogi 《Optics and Lasers in Engineering》2007,45(7):766-772
The effectiveness of phase-shifting interferometry (PSI) techniques employing piezoelectric device PZT in the estimation of phase depends largely on the accuracy with which the phase shifts are imparted to the device and the noise influencing the measurement. Several effective algorithms have been proposed to compute the phase shifts imparted to the device and subsequently obtain the phase using least-squares estimation technique. In this paper, we propose a generalized approach, which accurately estimates the phase shifts in the presence of noise. The method is based on the idea of linear prediction and explores the fact that sampling more data frames yields a reliable phase step estimate in a least-squares sense. We also compare our method with a commonly used generalized phase-shifting method based on histogram analysis and show that our proposed approach is highly effective. We also present simulation and experimental validations of our proposed method. 相似文献
70.
M.C. Kumar Prakash Mathews V. Ravindran 《The European Physical Journal C - Particles and Fields》2007,49(2):599-611
In the extra dimension models of ADD and RS we study the dependence of the various parton distribution functions on observables
of Drell–Yan processes to NLO in QCD at LHC and Tevatron energies. Uncertainties at LHC due to factorisation scales in going
from leading to next-to-leading order in QCD for the various distributions get reduced by about 2.75 times for a μF range 0.5Q<μF<1.5Q. Further uncertainties arising from the error on the experimental data are estimated using the MRST parton distribution
functions. 相似文献