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Thermoluminescence (TL) experiments were conducted for Ga 2 S 3 crystals to obtain information about trapping parameters. TL measurements were performed from 10 to 300 K with varying heating rates in the range of 0.2–0.8 K/s. Two TL glow peaks centered at 44 K (peak A) and 91 K (peak B) were observed at heating rate of β  = 0.5 K/s. For peak A, TL intensity decreased whereas that for peak B increased with elevating the heating rates that means anomalous heating rate occurred for peak B. TL glow curves were analyzed using initial rise method to find activation energies of traps. Distribution of trap centers was investigated using T max  −  T stop method. Quasi-continuous distributions with increasing activation energies from 40 to 135 meV and 193 to 460 meV were attributed to trap centers A and B, respectively. [ABSTRACT FROM AUTHOR]

Optical and electrical properties of TlInSSe layered single crystals have been studied by means of transmission, reflection and photoconductivity measurements. Transmission and reflection experiments have been carried out from 540 to 1000 nm at room temperature. Derivative analysis was applied to both transmission and reflection spectra and indirect band gap energy was found as 2.06 eV. Photoconductivity measurements have been performed in the temperature range from 245 to 300 K and in the voltage range from 10 to 80 V. From the temperature-dependent photoconductivity measurements, the observed single peak shifted to higher wavelengths with increase of temperature. The increase of photoconductivity with temperature is due to the increase in the mobility of photocarriers that can be explained by Bube model. From λ 1/2 method, room temperature indirect band gap of the crystal was also found as 2.06 eV. From voltage-dependent photoconductivity measurements, the peak maximum increased linearly with increase of voltage because of increase of the mobility of charge carriers. Dark current-voltage characteristic of TlInSSe crystal showed the ohmic behavior that means space charge limited current did not exist in the crystal. From the photocurrent with different illumination intensity analysis, the supralinear photoconductivity associated with the two center model was found. [ABSTRACT FROM AUTHOR]

The structural and optical characteristics of NaBi(Mo 0.5 W 0.5 O 4) 2 single crystals grown by Czochralski method were investigated. X-ray diffraction (XRD) pattern exhibited four well-defined peaks related to tetragonal crystalline structure with a space group I4 1/a. Raman and infrared transmittance spectra were recorded to investigate vibrational properties of the compound. Room temperature transmission spectrum was measured to reveal band gap energy of the crystal. The derivative spectral and absorption coefficient analyses resulted in direct band gap energy of 3.19 and 3.18 eV, respectively. Urbach energy of the crystal was also determined as 0.17 eV from photon energy dependency of absorption coefficient. The structural and optical parameters obtained for NaBi(Mo 0.5 W 0.5 O 4) 2 were compared with the parameters of the NaBi(XO 4) 2 (X: Mo,W) compounds to understand the effect of the composition on the studied properties. The reported characteristics of NaBi(Mo 0.5 W 0.5 O 4) 2 point out that the compound has significant potential to be used in optoelectronic devices. [Display omitted] • NaBi(Mo 0.5 W 0.5 O 4) 2 single crystals were grown by Czochralski method. • XRD pattern reveals the well-defined tetragonal crystal structure. • The absorption coefficient analysis revealed the direct band gap energy as 3.18 eV. • Urbach energy of the crystal was found as 0.17 eV. • NaBi(Mo 0.5 W 0.5 O 4) 2 may be a potential candidate for optoelectronic devices. [ABSTRACT FROM AUTHOR]

Abstract: Temperature variation of indirect band gap of Tl2In2S3Se layered single crystals were obtained by means of absorption and photoconductivity measurements. The temperature coefficient of −7.1×10−4 eV/K from absorption measurements in the temperature range of 10–300K in the wavelength range of 520–1100nm and −5.0×10−4 eV/K from PC measurements in the temperature range of 132–291K in the wavelength range of 443–620nm upon supplying voltage V =80V were obtained. From the analysis of dark conductivity measurements in the temperature range of 150–300K, conductivity activation energy was obtained as 0.51eV above 242K. The degree of the disorder, the density of localized states near Fermi level, the average hopping distance and average hopping energy of Tl2In2S3Se crystals were found as, 1.9×105 K, N f =4×1020 cm−3eV−1, 29.1Å and 24.2meV in the temperature range of 171–237K, respectively. Activation energy of hopping conductivity at T =171K was obtained as 41.3meV and the concentration of trapping states was found as 1.6×1019 cm−3. [Copyright &y& Elsevier]

Abstract: Photoluminescence (PL) spectra of Ga0.75In0.25Se layered single crystals have been studied in the wavelength range of 580–670nm and temperature range of 7–59K. Two PL emission bands centered at 613nm (2.02eV, A-band) and 623nm (1.99eV, B-band) were revealed at T =7K. The excitation laser intensity dependence of the emission bands have been studied in the 0.06–1.40Wcm−2 range. Radiative transitions from shallow donor levels located at E A =0.11 and E B =0.15eV below the bottom of conduction band to single shallow acceptor level located at 0.01eV above the valence band are suggested to be responsible for the observed A- and B-bands. A simple model was proposed to interpret the recombination processes in Ga0.75In0.25Se single crystals. [Copyright &y& Elsevier]

Abstract: Thermally stimulated current (TSC) measurements have been carried out on Tl2In2Se3S layered single crystals in the temperature range of 10–175 K. The TSC spectra reveal the presence of two peaks (A and B). The electronic traps’ distributions have been analyzed by different light illumination temperature techniques. It was revealed that the obtained traps’ distribution can be described as an exponential one. The variations of one order of magnitude in the traps’ density for every 30 meV (A peak) and 59 meV (B peak) were estimated. Moreover, the mean activation energy, attempt-to-escape frequency, capture cross section and concentration of the traps were determined. [Copyright &y& Elsevier]

Abstract: As-grown Tl2In2S3Se layered single crystals were studied by thermally stimulated current measurements in the temperature range of 10–170K with different heating rates. Experimental data were analyzed according to various methods such as curve fitting and initial rise. The analysis of thermally stimulated current spectra registered at light excitation temperature T 0=10K revealed the trap level located at 30meV. Attempt-to-escape frequency, concentration and capture cross section of the traps were determined as 4.2s−1, 2.4×109 cm−3 and 1.7×10−24 cm2, respectively. It was concluded that slow retrapping (monomolecular condition) occurs for the traps in Tl2In2S3Se crystals. By the analysis of thermally stimulated current data at different light excitation temperatures, the value of 39meV/decade was obtained for traps distribution. [Copyright &y& Elsevier]

Abstract: The emission band spectra of undoped Tl2In2Se3S layered crystals have been studied in the temperature range of 25–63K and the wavelength region of 570–700nm. A broad photoluminescence band centered at 633nm (1.96eV) was observed at T=25K. Variation of emission band has been studied as a function of excitation laser intensity in the 2.7–111.4mWcm−2 range. Radiative transitions from shallow donor level located at 0.03eV below the bottom of conduction band to deep acceptor level located at 0.23eV above the top of the valence band were suggested to be responsible for the observed PL band. From X-ray powder diffraction and optical absorption study, the parameters of monoclinic unit cell and the energy of indirect band gap were determined, respectively. [Copyright &y& Elsevier]

Abstract: The Raman spectra of TlInS2x Se2(1−x) layered mixed crystals were studied for a wide composition range (0.25≤x≤1) in the frequency region 10–360cm−1 at room temperature. The shift of Raman-active phonon frequencies versus mixed crystals composition x were established. The effect of crystal disorder on the line width broadening of three high-frequency Raman-active modes is reported. [Copyright &y& Elsevier]

Ga 2 Se 3 and Ga 2 S 3 compounds take attention due to their potential applications in photovoltaics. Defects and impurities may affect the quality of optoelectronic devices. Therefore, it is worthwhile to determine the parameters (activation energy, order of kinetics, frequency factor) of traps associated with the defects and/or impurities. The aim of the present paper is to investigate the trapping parameters of (Ga 2 Se 3) 0.25 – (Ga 2 S 3) 0.75 single crystal which is one of the member of (Ga 2 Se 3) x – (Ga 2 S 3) 1-x mixed crystals. For this purpose, thermoluminescence (TL) experiments were performed on (Ga 2 Se 3) 0.25 – (Ga 2 S 3) 0.75 single crystals in the 10–300 K region. TL spectra were also recorded using various heating rates in between 0.2 and 1.0 K/s and stopping temperatures from 30 to 60 K to get the detailed information about the characteristics of the trapping parameters. TL glow curves exhibited the overlapped peaks. The stopping temperature experimental data indicated that traps present quasi-continuous distribution within the band gap. Initial rise method analyses were applied to get the activation energies of quasi-continuously distributed revealed traps. Thermal activation energies of distributed traps were found as increasing from 108 to 246 meV as stopping temperature was increased from 30 to 60 K. The structural characteristics (lattice constants and atomic compositions of constituent elements) of used compound were also reported in the present study. • Thermoluminescence properties of (Ga 2 Se 3) 0.25 – (Ga 2 S 3) 0.75 crystals were investigated. • T m − T stop method was applied to get information about the characteristics of trap centers. • Heating rate dependency of observed TL glow curves were investigated. • Activation energies of quasi-continuously distributed trapping centers were revealed. [ABSTRACT FROM AUTHOR]

To analyze our institutional outcomes in heart-lung transplantation (HLTx). We performed a single-center retrospective analysis of all patients who underwent HLTx at the University Hospitals Leuven (UZL) from 1991 to 2018 and compared our results to ISHLT registry data. 50 patients underwent HLTx in UZL. In-hospital mortality was 24% vs 72% in the ISHLT database (p<1.10-5). On average baseline characteristics of donors and receptors were comparable between UZL and ISHLT. Kaplan-Meier survival curves for both are depicted in figure 1. When considering the eras 1991-2003 and 2004-2018, 1-, 5, and 10-year survival rates of UZL were more favorable for the latter era; 15-year survival was significantly better for era 2004-2018, as depicted in figure 2. Over time, we observed an increase in cardiac-related indications with Eisenmenger syndrome being the most important (56% vs 25% in the ISHLT registry, p<1.10-5). Other forms of pulmonary arterial hypertension (PAH) were an important indication to perform HLTx (24% in both groups). The major cause of late mortality in our population was rejection (41.4%), more specifically chronic lung allograft dysfunction. Between 1991 and 2018, we performed 50 HLTx's. The most frequent indication was Eisenmenger syndrome, but with a twofold higher proportion in our population compared to the ISHLT registry. The proportion of other forms of PAH was comparable. While over time the indications shifted from pulmonary to cardiac conditions, our survival continues to improve. [ABSTRACT FROM AUTHOR]

Abstract: Novel segmented polyurethanes with hard segments based on a single diisocyanate molecule with no chain extenders were prepared by the stoichiometric reactions of poly(tetramethylene oxide)glycol (M n=1000g/mol) (PTMO-1000) and 1,4-phenylene diisocyanate (PPDI), trans-1,4-cyclohexyl diisocyanate (CHDI), bis(4-isocyanatocyclohexyl)methane (HMDI) and bis(4-isocyanatophenyl)methane (MDI). Time dependent microphase separation and morphology development in these polyurethanes were studied at room temperature using transmission FTIR spectroscopy. Solvent cast films on KBr discs were annealed at 100°C for 15s and microphase separation due to self organization of urethane hard segments was followed by FTIR spectroscopy, monitoring the change in the relative intensities of free and hydrogen-bonded carbonyl (C Depending on the structure of the diisocyanate used, while the intensity of free Cround 1720–1730cm−1 decreased, the intensity of H-bonded Cround 1670–1690cm−1, which were not present in the original samples, increased with time and reached saturation in periods ranging up to 5 days. Structure of the diisocyanate had a dramatic effect on the kinetics of the process and the amount of hard segment phase separation. While PPDI and CHDI based polyurethanes showed self-organization and formation of well ordered hard segments, interestingly no change in the carbonyl region or no phase separation was observed for MDI and HMDI based polyurethanes. Quantitative information regarding the relative amounts of non-hydrogen bonded, loosely hydrogen bonded and strongly hydrogen bonded and ordered urethane hard segments were obtained by the deconvolution of Cand analysis of the relative absorbances in C [Copyright &y& Elsevier]

Objectives To quantify palatal bone thickness (PBT) in Down's syndrome (DS) patients in order to identify the best areas for miniscrew placement. Design The study group was formed of 40 DS patients (25 male and 15 female) with a mean age of 18.4 ± 6.3 years (range, 9–40 years). A control group of 40 non-syndromic age- and sex-matched individuals was selected. Maxillary CBCT images were available for all participants. Coronal sections of the hard palate were selected at 4, 8, 16 and 24 mm posterior to the distal wall of the incisive foramen. PBT measurements were performed at 20 selected points on these coronal sections at the midline and at 3 and 6 mm to right and left of the suture. Results Overall, PBT was similar in DS and controls and it was not affected by age or sex. In both groups PBT decreased progressively with increasing distance from the posterior wall of the nasopalatine foramen in an anteroposterior direction, except along the median palatal suture. PBT along the suture was lower in DS than in controls in all the paracoronal image planes ( P = 0.02, 0.007, 0.01 and 0.02 at 4 mm, 8 mm, 16 mm and 24 mm, respectively, from the incisive foramen). PBT at the most anterior paramedian locations was also lower in DS than in controls ( P = 0.02 and 0.03, respectively, 3 mm to the right and left of midline). Conclusions In DS individuals, the most suitable area for miniscrew placement in terms of bone volume is the median palatal suture, irrespective of age or sex, as occurs in the general population, followed by the paramedian sites closest to the incisive foramen. [ABSTRACT FROM AUTHOR]