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Pure GaAs and GaAs1−xBix alloys with different Bi ratios (1 %, 2.5 %, 3.5 %) fitted with silver contacts were measured with a dielectric spectroscopy device. Dielectric characterization was performed at room temperature in the frequency range of 0.1 Hz to 1 MHz. GaAs exhibits three relaxation regions corresponding to space-charge, dipolar and ionic polarizations in sequence with increasing frequency while GaAs1−xBix samples show only a broad dipolar polarization in the same frequency range. This result proves the filling of the lattice with Bi through making a new bonding reducing the influence of ionic polarization. This finding supports the previous results concerning optical properties of GaAs1−xBix, presented in the literature. [ABSTRACT FROM AUTHOR]

Bulk TlGaS 2 single crystals were produced by the Bridgman method. TlGaS 2 thin film samples were deposited from bulk crystals by the thermal evaporation technique under a high vacuum. TlGaS 2 thin films were deposited in the 100–750 nm thickness range. Dielectric spectroscopy measurements were operated in the frequency range of 1–105 Hz and temperature range of 273–373 K under the voltage of 1 V (rms). TlGaS 2 thin films have amorphous. Bulk TlGaS 2 has a crystalline structure based on X-Ray diffraction patterns. Three polarization mechanisms were detected from the analysis of Cole-Cole plots. At low frequencies, the effect of interfacial polarization was observed. Toward higher frequencies, two dipolar polarization mechanisms were detected. In comparison to the bulk TlGaS 2 single crystal, the dielectric constant of the thin films has 100–1000 times larger values at frequencies lower than 100 Hz. The thickness limit at which bulk physical properties started has been investigated. The transition thickness between bulk/thin film properties was detected at around 700 nm. The low dielectric constant and the good conductivity around 10−8 S/cm at105 Hz can give opportunities to use these thin films in technological applications. • The interfacial polarization is observed at frequencies lower than 100 Hz. • At higher frequencies, polarization mechanisms having dipolar nature are detected. • At frequencies below 100 Hz, the dielectric constant has 100–1000 times greater values for TlGaS 2 thin films. • The dielectric properties of TlGaS 2 thin films change to bulk dielectric properties with thickness-independent dielectric behavior at 800 nm. • TlGaS 2 thin films are suitable for nano-sized switching and thermoelectric applications. [ABSTRACT FROM AUTHOR]

Plasma polymerized poly(ethylene oxide) thin film samples with thickness of 500 nm were deposited using plasma assisted physical vapour deposition at radio-frequency plasma discharge powers of 0, 2, 5 and 30 W, respectively. For comparison, a conventional poly(ethylene oxide) precursor was also investigated. In order to investigate the effect of the plasma discharge power on the cross-linking density of the plasma poly(ethylene oxide) and poly(ethylene oxide) precursors, structural characterization using differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy was performed. Structural analysis showed that the density of cross-linking increased upon increasing the plasma discharge power. This increase was observed as an increase in the dynamic glass transition temperature during the DSC measurements. In addition to these characterizations, the dielectric response of the thin film plasma poly(ethylene oxide) samples and poly(ethylene oxide) precursors were measured. The dielectric spectroscopy results showed that changes in the cross-linking density changed the alternative current (AC) conductivity. The measured glass transition temperatures obtained using DSC are in accordance with the glass transition temperatures obtained from the temperature-dependent AC conductivity results. It was observed that the temperature-dependent AC conductivity exhibits Arrhenius behaviour. The activation energies obtained for the plasma polymer samples showed an increase from 0.38 eV to 0.5 eV upon increasing the plasma discharge power. The plasma discharge power dependent activation energy results also indicate the fragmentation of long polymer chains into more smaller oligomers and radicals occurred upon increasing the plasma power. [ABSTRACT FROM AUTHOR]

Takayasu arteritis is a non-specific inflammatory process of unknown aetiology affecting the aorta and its major branches. It may lead to stenosis or occlusion. We have examined eight patients with clinically diagnosed Takayasu arteritis using contrast-enhanced MRI and also 3-D MR angiography. All patients were female and their ages varied between 22 and 48 years. We were able to show subtle arteritic changes and stenotic lesions in branch vessels in the early phase of the disease by using this imaging modality. Thus, we can state that contrast-enhanced MRI with 3-D MR angiography can be used for the initial diagnosis of Takayasu arteritis. It provides a means to evaluate the vascular tree non-invasively and may replace conventinal angiography. [ABSTRACT FROM AUTHOR]

Fluorescence in situ hybridization analysis using telomere specific probes has been used to detect cryptic translocations in the chromosomal telomeric regions. This study was performed in five clinically normal couples who have had five or more spontaneous abortions and whose karyotypes were found to be normal using conventional cytogenetic techniques. Using the telomere specific probes, in one couple we determined a cryptic translocation between chromosome 3 and 10, and, in another couple, the signal in chromosome 20 was detected in another chromosome, which was probably a D group chromosome. Additionally, in the latter and also in two other couples, we observed a polymorphism. The approach will be helpful for screening cryptic translocations using telomere specific multiple probe sets in couples with recurrent miscarriages. As prenatal diagnosis will be available for these couples for future pregnancies, it will be possible to help these families to have healthy fetuses. [ABSTRACT FROM AUTHOR]

An abstract of the article "Prenatal management, pregnancy and pediatric outcome in fetuses with septated cystic hygroma," by I. Mendilcioglu, C. Y. Sanhal, S. Yakut, M. Simsek, M. Ozekinci, Z. Saritas, and G. Luleci is presented.