نتایج جستجو برای: chiral media
تعداد نتایج: 317554 فیلتر نتایج به سال:
Carbon nanotubes (CNTs) are specific structures with valuable characteristics. In general, the structure of each nanotube is defined by a unique chiral vector. In this paper, different structures of short single-walled CNTs are simulated and their mechanical properties are determined using finite element method. For this aim, a simple algorithm is presented which is able to model the geometry o...
Diquarks may play an important role in hadronic physics particularly near the phase transitions (chiral, deconfinement points). By using vector diquark ideas in the chiral limit diquark correlations in the relativistic region and imposing HF interactions between quarks in a vector diquark, we calculate the mass of Theta pentaquark state. Also by using the tunnelling method we simultaneously c...
the high performance liquid chromatography (hplc) enantioseparation of four β-blocking agents metoprolol, bisoprolol, propranolol and atenolol was performed on amylose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase using n-hexane-ethanol-diethylamine (dea) as the mobile phase and related chiral recognition mechanisms were discussed. enantiomeric separation of the fourβ-blockers was ...
The melting of zigzag, armchair and chiral single walled boron nitride nanotubes (SWBNs) investigated using molecular dynamics (MD) simulation based on Tersoff-like many body potential. The MD simulation has been employed in the constant pressure, constant temperature (NPT) ensemble. The temperature and pressure of the system were controlled by Nose-Hoover thermostat and Berendsen barostat, res...
In this Account strategies using zeolites as media to achieve chiral induction are presented. Diastereomeric excesses as high as 90% and enantiomeric excesses up to 78% have been obtained with selected systems within zeolites. The same systems show no asymmetric induction in solution. Chiral induction is dependent on the alkali ions present in the zeolites. Alkali ions control not only the exte...
Few works on symmetric and asymmetric dielectrics have been published, specifically the case of chiral and bi-isotropic media. For this reason and taking into account the complexity of the studied environment, this paper treats the asymmetrical effects on the resonant frequency and the bandwidth of a rectangular microstrip patch antenna in a complex bi-anisotropic substrate-superstrate configur...
Time-harmonic electromagnetic waves are scattered by a homogeneous chiral obstacle. The corresponding transmission problem is reduced to a pair of coupled integral equations over S, where S is the interface between the obstacle and the surrounding medium. This is done using a generalization of the Stratton–Chu representation that is valid for chiral media. The integral equations obtained are a ...
Sum-frequency generation in isotropic media is in the electric-dipole approximation the only symmetry allowed for chiral systems. We demonstrate that the sum-frequency intensity from an optically active liquid depends quadratically on the difference in concentration of the two enantiomers. The dominant contribution to the signal is found to be due to the chirality specific electric-dipolar thre...
Differential scattering of leftand right-handed circularly polarized waves is a general property of scattering media lacking space-inversion symmetry. We show in this paper that this scattering difference has remarkable properties in the case of an almost transparent chiral random medium. By tuning the refractive indices of the materials composing the medium, this scattering difference can be v...
در این پژوهش منشاء خزندگان را مورد بررسی قرار داده، خانواده های سوسماران را در ایران معرفی نموده و ویژگی های آنها را ذکر کرده ایم، خانواده lacertidae را از منظر فیلوژنی، رده بندی و همچنین جنس های آن را، مرور کرده ایم. جنس lacerta که هدف اصلی پژوهش حاضر است در ایران دارای دو گونه می باشد؛ یکی گونه ی lantz & cyrén, 1920 lacerta media که از این گونه، تنها زیرگونه ی lacerta media media lantz & cy...
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