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Full-Text Articles in Physics

Synthesis, Characterization And Nonlinear Optical Properties Of Silver/Pva Nanocomposites, Mahdi Shahmiri Jan 2012

Synthesis, Characterization And Nonlinear Optical Properties Of Silver/Pva Nanocomposites, Mahdi Shahmiri

mahdi shahmiri

Silver/polyvinyl alcohol (PVA) nanocomposites are prepared via quick precipitation method, using hydrazine as a reducing agent. Preparing of silver/PVA nanocomposites by this method is done for the first time. The samples are characterized by Uv-Visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM). Nonlinear optical properties are carried out by Z-scan technique using a blue CW laser beam operated at wavelength 405 nm. It is shown that the synthesized samples have negative nonlinear refractive index and the magnitude is in the order of 10􀀀8. The nonlinear refractive index increases as amount of reducing agent increases.


Fabrication And Characterization Of Graphene Hydrogel Via Hydrothermal Approach As A Scaffold For Preliminary Study Of Cell Growth, Huang Nay Ming Jan 2011

Fabrication And Characterization Of Graphene Hydrogel Via Hydrothermal Approach As A Scaffold For Preliminary Study Of Cell Growth, Huang Nay Ming

Huang Nay Ming

Three-dimensional assembly of graphene hydrogel is rapidly attracting the interest of researchers because of its wide range of applications in energy storage, electronics, electrochemistry, and waste water treatment. Information on the use of graphene hydrogel for biological purposes is lacking, so we conducted a preliminary study to determine the suitability of graphene hydrogel as a substrate for cell growth, which could potentially be used as building blocks for biomolecules and tissue engineering applications. A three-dimensional structure of graphene hydrogel was prepared via a simple hydrothermal method using two-dimensional large-area graphene oxide nanosheets as a precursor. The concentration and lateral size …


Heavy Quark Production By A Quasi-Classical Color Field In Proton-Nucleus Collisions, Kirill Tuchin Jan 2004

Heavy Quark Production By A Quasi-Classical Color Field In Proton-Nucleus Collisions, Kirill Tuchin

Kirill Tuchin

We calculate the inclusive heavy quark production cross section for proton-nucleus collisions at high energies. We perform calculation in a quasi-classical approximation (McLerran-Venugopalan model) neglecting all low-x evolution effects. The derived expression for the differential cross section can be applied for studying the heavy quark production in the central rapidity region at RHIC.


Nuclear Modification Factor In D + Au Collisions: Onset Of Suppression In The Color Glass Condensate, Dmitri Kharzeev, Yuri V. Kovchegov, Kirill Tuchin Jan 2004

Nuclear Modification Factor In D + Au Collisions: Onset Of Suppression In The Color Glass Condensate, Dmitri Kharzeev, Yuri V. Kovchegov, Kirill Tuchin

Kirill Tuchin

We perform a quantitative analysis of the nuclear modification factor in deuteron-gold collisions R dAu within the Color Glass Condensate approach, and compare our results with the recent data from RHIC experiments. Our model leads to Cronin enhancement at mid-rapidity, while at forward rapidities it predicts strong suppression of R dAu at all PT due to low-x evolution. We demonstrate that our results are consistent with the data for dAu charged hadron spectra, R dAu and R CP recently reported for rapidities in the interval η=0-3.2 by the BRAHMS experiment at RHIC. We also make a prediction for R pA …


Qcd In Curved Space-Time: A Conformal Bag Model, Dmitri Kharzeev, Eugene Levin, Kirill Tuchin Jan 2004

Qcd In Curved Space-Time: A Conformal Bag Model, Dmitri Kharzeev, Eugene Levin, Kirill Tuchin

Kirill Tuchin

We construct an effective low energy Lagrangian using constraints imposed by the renormalization group. Degrees of freedom are gluons and a scalar glueball. This effective theory has a dual description as classical gluodynamics on a curved conformal background. Color fields are dynamically confined, and the strong coupling freezes at distances larger than the glueball size. We make specific predictions (in particular, on the Nc dependence of glueball properties) which can be tested in lattice simulations of gluodynamics.


Classical Gluodynamics In Curved Space-Time And The Soft Pomeron, Dmitri Kharzeev, Eugene Levin, Kirill Tuchin Jan 2002

Classical Gluodynamics In Curved Space-Time And The Soft Pomeron, Dmitri Kharzeev, Eugene Levin, Kirill Tuchin

Kirill Tuchin

QCD at the classical level possesses scale invariance which is broken by quantum effects. This "dimensional transmutation" phenomenon can be mathematically described by formulating classical gluodynamics in a curved, conformally flat, space-time with non-vanishing cosmological constant. We study QCD high-energy scattering in this theory. We find that the properties of the scattering amplitude at small momentum transfer are determined by the energy density of vacuum fluctuations. The approach gives rise to the power growth of the total hadron-hadron cross section with energy, i.e., the pomeron. The intercept of the pomeron and the multiplicity of produced particles are evaluated. We also …


Higher Twist Corrections And Maxima For Dis On A Proton In The High Density Qcd Region, E. Gotsman, Eugene Levin, U. Maor, L. Mclerran, Kirill Tuchin Jan 2001

Higher Twist Corrections And Maxima For Dis On A Proton In The High Density Qcd Region, E. Gotsman, Eugene Levin, U. Maor, L. Mclerran, Kirill Tuchin

Kirill Tuchin

We show that the ratio of different structure functions have a maximum which depends on energy. We argue, using the Golec-Biernat and Wusthoff model as well as the eikonal approach, that these maxima are functions of the saturation scale. We analyze leading and higher twist contributions for different observables to check whether a kinematic region exists where high parton density effects can be detected experimentally.


The Pomeron Intercept In Lambda Phi**Theory In 4 Minkowski + 1 Compact Dimensions, Kirill Tuchin Jan 2001

The Pomeron Intercept In Lambda Phi**Theory In 4 Minkowski + 1 Compact Dimensions, Kirill Tuchin

Kirill Tuchin

We calculate the total cross section for two scalar particles scattering at high energies in λφ3 theory in five dimensions, four of which are usual Minkowski ones and the fifth is compact. It is shown that the cross section is dominated by exchange of Pomeron whose intercept is larger than in usual four-dimensional case.


A Simple Monochromatic Spark Discharge Light-Source, Chin Oi Hoong Jan 1989

A Simple Monochromatic Spark Discharge Light-Source, Chin Oi Hoong

Chin Oi Hoong

Spark light illumination has been used in high-speed photog-raphy since the beginning ofthe century and various designs ofthe spark discharge light source have since been reportedr with spark duration ranging from nanoseconds to millisec-onds. We report here a simple and easy to build spark dis-charge tube for operation as a monochromatic point light source. The design and construction ofthe spark discharge tube is shown in Fig. 1. The sharp-tip solid cone anode is made of stainless steel which is screwed onto a brass rod connected A compact spark discharge tube operated as a monochromatic light source at 587.5 nm is …