Recording 2-D Nutation NQR Spectra by Random Sampling Method

The method of random sampling was introduced for the first time in the nutation nuclear quadrupole resonance (NQR) spectroscopy where the nutation spectra show characteristic singularities in the form of shoulders. The analytic formulae for complex two-dimensional (2-D) nutation NQR spectra (I = 3/2) were obtained and the condition for resolving the spectral singularities for small values of an asymmetry parameter η was determined. Our results show that the method of random sampling of a nutation interferogram allows significant reduction of time required to perform a 2-D nutation experiment and does not worsen the spectral resolution

Semiconductive and Photoconductive Properties of the Single Molecule Magnets Mn12_{12}-Acetate and Fe8_8Br8_8

Resistivity measurements are reported for single crystals of Mn$_{12}$-Acetate and Fe$_8$Br$_8$. Both materials exhibit a semiconductor-like, thermally activated behavior over the 200-300 K range. The activation energy, $E_a$, obtained for Mn$_{12}$-Acetate was 0.37 $\pm$ 0.05 eV, which is to be contrasted with the value of 0.55 eV deduced from the earlier reported absorption edge measurements and the range of 0.3-1 eV from intramolecular density of states calculations, assuming $2E_a$= $E_g$, the optical band gap. For Fe$_8$Br$_8$, $E_a$ was measured as 0.73 $\pm$ 0.1 eV, and is discussed in light of the available approximate band structure calculations. Some plausible pathways are indicated based on the crystal structures of both lattices. For Mn$_{12}$-Acetate, we also measured photoconductivity in the visible range; the conductivity increased by a factor of about eight on increasing the photon energy from 632.8 nm (red) to 488 nm (blue). X-ray irradiation increased the resistivity, but $E_a$ was insensitive to exposure.Comment: 7 pages, 8 figure

Complex Epsilon-phases in the Al-Pd-transition-metal systems: towards a combination of an electrical conductor with a thermal insulator

epsilon-Phases in the Al-Pd-(Mn,Fe,Co,Rh,..,) alloy systems form in wide compositional ranges and belong to the interesting class of complex intermetallics that are characterized by giant unit cells with quasicrystals-like cluster substructure. In order to see how the exceptional structural complexity and the coexistence of two competing physical length scales affect the physical properties of the material, we performed investigation of the magnetic, electrical, thermal transport and thermoelectric properties of the epsilon-phases in the Al-Pd-Fe, Al-Pd-Co and Al-Pd-Rh systems. Magnetic measurements reveal that the materials are diamagnetic, containing tiny fractions of magnetic transition-metal atoms (of the order 10-100 ppm). Electrical resistivity is moderate, of the order 10(2) mu Omega cm, and shows weak temperature dependence (in most cases of a few %) in the investigated temperature range 4-300 K. An interesting feature of the epsilon-phases is their low thermal conductivity, which is at room temperature comparable to that of thermal insulators amorphous SiO2 and Zr/YO2 ceramics. While SiO2 and Zr/YO2 are also electrical insulators, E-phases exhibit electrical conductivity typical of metallic alloys, so that they offer an interesting combination of an electrical conductor with a thermal insulator. The reason for the weak thermal conductivity of the e-phases appears to be structural: large and heavy atomic clusters of icosahedral symmetry in the giant unit cell prevent the propagation of extended phonons, so that the lattice can no more efficiently participate in the heat transport. The thermoelectric power of the investigated epsilon-phase families is small, so that these materials do not appear promising candidates for the thermoelectric application. (c) 2006 Elsevier B.V. All rights reserved

Electrical, magnetic, thermal and thermoelectric properties of the "Bergman phase" Mg32(Al,Zn)49 complex metallic alloy

The Mg-Al-Zn system of intermetallics contains an exceptional crystalline phase Mg-32(Al,Zn)(49), named the Bergman phase, whose crystal structure is based on a periodic arrangement of icosahedral Bergman clusters within the giant-unit-cell, so that periodic and quasiperiodic atomic orders compete in determining the physical properties of the material. We have investigated electrical, magnetic, thermal and thermoelectric properties of a monocrystalline Bergman phase sample of composition Mg-29.4(Al,Zn)(51.6), grown by the Bridgman technique. Electrical resistivity is in the range rho approximate to 40 mu Omega cm and exhibits positive-temperature-coefficient with V dependence at low temperatures and T at higher temperatures, resembling non-magnetic amorphous alloys. Magnetic susceptibility x measurements revealed that the sample is a Pauli paramagnet with a significant Landau diamagnetic orbital contribution. The susceptibility exhibits a weak increase towards higher temperature. Combined analysis of the rho(T) and chi(T), together with the independent determination of the Pauli susceptibility via the NMR Knight shift suggests that the observed temperature dependence originates from the mean-free-path effect on the orbital susceptibility. The electronic density of states (DOS) at the Fermi energy E-F was estimated by NMR and was found to amount 72% of the DOS of the fee Al metal, with no evidence on the existence of a pseudogap. Thermal conductivity contains electronic, Debye and hopping of localized vibrations terms, whereas thermopower is small and negative. High structural complexity of the Bergman phase does not result in high complexity of its electronic structure. (c) 2006 Elsevier B.V. All rights reserved

The Knowledge About Celiac Disease Among Healthcare Professionals and Patients in Central Europe

OBJECTIVES: Celiac disease (CD) remains undiagnosed for a long time in many adult and pediatric patients. We assessed the knowledge about CD among healthcare professionals (HCPs) and CD patients in Central Europe (CE). METHODS: HCPs and CD patients from 5 CE countries were asked to complete the web-based questionnaire about CD. The questions were divided into subsections on epidemiology, clinical presentation, diagnostics, treatment, and follow-up. Achieved scores of different specialists managing patients with CD were compared and regional differences in patients' knowledge were analyzed. RESULTS: Questionnaire was completed by 1381 HCPs and 2262 CD patients or their caregivers from Croatia, Hungary, Germany, Italy, and Slovenia. Mean score achieved by HCPs was 50.9%, and by CD patients 56.4%. Pediatric gastroenterologists scored the highest (69.4%; P\u200a<\u200a0.001). There were significant differences in knowledge of patients from different CE regions with German participants scoring the highest (58.3%). Members of CD societies scored higher compared with nonmembers (mean score 58% vs 53.2%; P\u200a<\u200a0.001) and patients diagnosed less than 5 years ago scored higher compared with those diagnosed more than 10 years ago (mean score 57.3% vs 54.6%; P\u200a<\u200a0.001). CONCLUSIONS: The knowledge about CD among HCPs and CD patients is not satisfactory. Further awareness-raising and learning activities are needed to improve HCPs' knowledge and to minimize the number of unrecognized patients and unnecessary diagnostic delays. Patients should be better informed about their disease to reach higher compliance with the gluten-free diet

The Use of Biopsy and “No-Biopsy” Approach for Diagnosing Paediatric Coeliac Disease in the Central European Region

The current European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) guidelines introduced the option to diagnose coeliac disease (CD) in children and adolescents without upper endoscopy if the defined criteria are met. The aim of our study was to evaluate how frequently paediatric gastroenterologists in Central Europe used the “no-biopsy” approach and how often the duodenal biopsy could have been omitted. . Medical records of patients years diagnosed with CD in 2016 from five European countries were analysed, focusing on levels of transglutaminase antibodies (TGA) at the time of diagnosis and on whether the diagnosis was confirmed using duodenal biopsy or “no-biopsy” approach. Clinical presentation and delays until final diagnosis were analysed according to diagnostic approach. . Data from 653 children (63.9% female, median age: 7 years, range: 7 months-18.5 years) from Croatia, Hungary, Germany, Italy, and Slovenia were analysed. One fifth ( ) of included children were asymptomatic at diagnosis. Of 519 symptomatic children, 107 (20.6%) were diagnosed by the “no-biopsy” approach. Out of the remaining 412 children who underwent duodenal biopsies, 214 (51.9%) had times upper level of normal (ULN) and would have been eligible for the “no-biopsy” approach. Signs and symptoms of malabsorption were more frequent in children diagnosed without duodenal biopsies. There were no differences in diagnostic delays with respect to the diagnostic approach. . In this cohort, about 60% of symptomatic CD patients could have been diagnosed without duodenal biopsies. The aim of the “no-biopsy” approach was to make the diagnostic procedure less challenging without compromising its reliability. However, this option was applied only in 20%, in spite of fewer burdens to the family and reduced costs. The reasons for this discrepancy are unknown. Physicians should be made more aware about the reliability of CD diagnosis without biopsies when the ESPGHAN guidelines for CD diagnosis are followed

Reply to "Comment on 'Extrinsic origin of the insulating behavior of polygrain icosahedral Al-Pd-Re quasicrystals' "

We clarify issues raised in the preceding Comment regarding the viewpoint that the highly porous and oxidized arc-melted polygrain i-Al-Pd-Re samples could reveal intrinsic electrical transport properties of this icosahedral family. Flux-grown single-grain i-Al-Pd-Re samples of superior structural quality do not show insulatinglike behavior, and their transport properties are on common ground with all other Al-based icosahedral families.This article is published as Dolinšek, J., P. J. McGuiness, M. Klanjšek, I. Smiljanić, A. Smontara, E. S. Zijlstra, S. K. Bose, I. R. Fisher, M. J. Kramer, and P. C. Canfield. "Reply to “Comment on ‘Extrinsic origin of the insulating behavior of polygrain icosahedral Al-Pd-Re quasicrystals’”." Physical Review B 76, no. 21 (2007): 216202. DOI: 10.1103/PhysRevB.76.216202. Copyright 2007 American Physical Society. Posted with permission

Safety of Thiopurine Use in Paediatric Gastrointestinal Disease

Thiopurines, alone or in combination with other agents, have a pivotal role in the treatment of specific gastrointestinal and hepatological disorders. In inflammatory bowel disease and autoimmune hepatitis thiopurines have proven their value as steroid sparing agents for the maintenance of remission and may be considered for preventing postoperative Crohn disease recurrence where there is moderate risk of this occurring. Their use with infliximab therapy reduces antibody formation and increases biologic drug levels. The routine clinical use of thiopurines has, however, been questioned due to a number of potential adverse effects. The aim of this article is to provide information regarding the use, and in particular, safety of these agents in clinical practice in the light of such potentially severe, albeit rare, effects