Finite difference time domain analysis of a photonic crystal substrate patch antenna

Planar microstrip patch antennas can achieve a wide range of radiation patterns. However, due to surface-wave losses, they have low bandwidth, low gain, and a potential decrease in radiation efficiency. In order to minimize the surface-wave effects, a photonic-band gap (PBG) substrate is proposed. The PBG structure significantly diminishes the surface-wave modes and thus improves the gain and far-field radiation pattern and efficiency. In this paper, using FDTD, an accurate full-wave analysis of surface-wave propagation in a rectangular microstrip patch antenna with and without PBG is presented. Finally, the antenna fabricated and result of measurement was compared with numerical simulation.     

Polarization-controlled spatial localization of near-field energy in planar symmetric coupled oligomers

Arrays of planar symmetric coupled oligomers support higher sensitivity optical response than uncoupled plasmonic systems. In this work, the transition from isolated to collective optical modes in plasmonic oligomers, such as pentamers and quadrumers, is investigated via experimental characterization and simulation with good agreement. The designed and fabricated metallic oligomers consist of a single central disk and outer ring-like disks in nanoscales. It is shown that while the far-field spectral responses of oligomers are polarization-independent, due to the structure symmetry, the spatial localization of near-field energy in nanogaps can be polarization-controlled. This localization is established at a normal-incident light of a single source rather than co-illumination by two light sources accompanied by different incident angles or phase shift. It can overcome the spatial restrictions of conventional optics. The influence of the nano-disk sizes and gaps among them on the intensity and shape of the localized near-field energy in pentamers and quadrumers is also studied.     

Josephson current versus potential strength of the interface in ferromagnetic superconductors

Based on the scattering theory, we calculate the Josephson current in a junction between two ferromagnetic superconductors as a function of the interface potential z. We consider the ferromagnetic superconductor(FS) in three different Cooper pairing states: spin singlet s-wave pairing(SWP) state, spin triplet opposite spin pairing(OSP) state, and spin triplet equal spin pairing(ESP) state. We find that the critical Josephson current as a function of z shows clear differences among the SWP, OSP, and ESP states. The obtained results can be used as a useful tool for determining the pair symmetry of the ferromagnetic superconductors.     

Tensor product of C-injective modules

The purpose of this paper is to calculate all the character tables of Hecke algebras associated with finite Chevalley groups of exceptional type and their maximal parabolic subgroups when they are commutative. In the case when the groups are of classical type, the character values of Hecke algebras are expressed by using the q-Krawtchouk polynomials and the q-Hahn polynomials (See [10] and [15]). On the other hand, the character tables of commutative Hecke algebras associated with exceptional Weyl groups and their maximal parabolic subgroups are given in [12]. In §1, we discuss the structure of Hecke algebras and in §2, we calculate all the character tables of these commutative Hecke algebras associated with finite Chevalley groups of exceptional type. Although some of them are well known, we include them for completeness     

A rigorous analysis of simultaneous heat and mass transfer in the pasta drying process

This study presents a two dimensional analysis of coupled heat and mass transfer during the process of pasta drying. Velocity and temperature distributions of air flowing around the pasta are predicted in steady state condition. Using these profiles and the similarity between heat and mass boundary layers, local convective heat and mass transfer coefficients were determined on different points of pasta surface. By employing these values, the solution of coupled heat and mass transfer equations within the pasta object in unsteady state condition was obtained. Furthermore the effects of operating conditions such as velocity, temperature and relative humidity of air flow on drying rate of pasta were studied. Sensitivity analysis results show that the effects of air temperature and relative humidity on the rate of drying are more important than the effect of air velocity. Finally, the results obtained from this analysis were compared with the experimental data reported in the literatures and a good agreement was observed while, no adjustable parameter is used in the presented model.     

Far- and mid-infrared of crystalline 2,2'-bithiophene: ab initio analysis and comparison with infrared response

Infrared intramolecular vibrations and lattice modes in the crystalline phase of 2,2'-bithiophene (2T) are investigated using the direct method combined with density functional theory (DFT)-based total energy calculations. For the first time, the far- and mid-infrared responses have been calculated from the Gamma-point modes and the Born effective charge tensors of the 2T crystalline phase. The relative good agreement between the calculated and experimental infrared spectra allows us to assign the origin of the main features of the experimental spectra, which is of particular interest in the far-infrared domain. These assignments are useful for understanding all the properties of the 2T crystalline phase in which phonon-phonon and electron-phonon interactions play an important role.     

Preparation of a fast-flow agarose-based chelating adsorbent with a novel dioxime derivative for selective column preconcentration of copper.

Fast-flow spherical homogeneous agarose beads were prepared by an emulsification method, and were cross-linked and activated by repeated treatment with allylbromide and bromine/water, followed by alkali. Bis(2-aminopyridyl)dioxime (APD) was synthesized by the reaction of 2-aminopyridine, and dichloroglyoxime and characterized by melting-point as well as IR, 1HNMR, 13CNMR and MS spectroscopies. APD was chemically linked to activated agarose beads to be employed for the column preconcentration of metal ions. Capacity measurements for eight metal ions indicated a high selectivity of the adsorbent towards Cu2+ with a capacity of 25.7 micromol per ml packed adsorbent. A factorial design was used for optimization of the effects of 5 different variables on the recovery of Cu2+. Under the optimized conditions, Cu2+ was quantitatively accumulated on a 0.25 ml packed column of the adsorbent in the pH range of 4 to 6, and simply eluted with 2 ml of a 1 mol 1(-1) hydrochloric acid solution. The column could tolerate salt concentrations up to 0.5 mol 1(-1), sample flow rates up to 15 ml min(-1), and sample volumes beyond 1000 ml. Matrix ions of Na+, Mg2+ and Ca2+ and potentially interfering ions of Ni2+, Cd2+, Zn2+, Fe3+ and Co2+ with relatively high concentrations did not show any significant effect on the analyte's signal. Preconcentration factors up to 500 and a detection limit of 0.16 microg 1(-1) were obtained for the determination of the analyte by flame AAS. Application of the method to the determination of natural and spiked copper in river water and seawater samples resulted in quantitative recoveries.     

Artomandin, a new xanthone from Artocarpus kemando (Moraceae)

A new furanodihydrobenzoxanthone, artomandin (1), together with three other flavonoid derivatives, artoindonesianin C, artonol B, and artochamin A, as well as β-sitosterol were isolated from the stem bark of Artocarpus kemando. The structures of these compounds were determined on the basis of spectral evidence. All of these compounds displayed inhibition effects to a very susceptible degree in cancer cell line tests. Compound 1 also exhibited significant antioxidant capacity in the free radical 1,1-diphenyl-2-picrylhydrazyl tests.     

Determination of methylcyclopentadienyl-manganese tricarbonyl in gasoline and water via ionic-liquid headspace single drop microextraction and electrothermal atomic absorption spectrometry

Microchimica Acta - We report on a rapid and effective method for the determination of methylcyclopentadienyl-manganese tricarbonyl (MMT) in water and gasoline samples. It is based on single drop...     

Lignans and other constituents from aerial parts of Haplophyllum villosum

During our phytochemical investigation of Haplophyllum villosum (Rutaceae), a perennial herb from Iran, a new 4,8-diaryl-3,7-dioxobicyclo-(3,3,0)-octane type lignan, eudesmin A (1), together with four known compounds--eudesmin (2), haplamine (3), umbelliferone (4) and scopoletin (5)--were isolated from aerial parts of the plant. The structures of the compounds were elucidated using NMR spectral analysis (1H-NMR, 13C-NMR, HSQC, COSY and HMBC) as well as UV, IR and MS spectra and comparison with previously reported data.