Orbital domain state and finite size scaling in ferromagnetic insulating manganites

55Mn and 139La NMR measurements on a high quality single crystal of ferromagnetic (FM) La0.80Ca20MnO3 demonstrate the formation of localized Mn(3+,4+) states below 70 K, accompanied with strong anomalous increase of certain FM neutron Bragg peaks. (55,139)(1/T1) spin-lattice relaxation rates diverge on approaching this temperature from below, signalling a genuine phase transition at T(tr) approx. 70 K. The increased local magnetic anisotropy of the low temperature phase, the cooling-rate dependence of the Bragg peaks, and the observed finite size scaling of T(tr) with Ca (hole) doping, are suggestive of freezing into an orbital domain state, precursor to a phase transition into an inhomogeneous orbitally ordered state embodying hole-rich walls.Comment: 4 pages, 4 figure

Spin-polarized oxygen hole states in cation deficient La(1-x)CaxMnO(3+delta)

When holes are doped into a Mott-Hubbard type insulator, like lightly doped manganites of the La(1-x)CaxMnO3 family, the cooperative Jahn-Teller distortions and the appearance of orbital ordering require an arrangement of Mn(3+)/Mn(4+) for the establishment of the insulating canted antiferromagnetic (for x<=0.1), or of the insulating ferromagnetic (for 0.1<x<= 0.2) ground state. In the present work we provide NMR evidence about a novel and at the same time puzzling effect in La(1-x)CaxMnO(3+delta) systems with cation deficience. We show that in the low Ca-doping regime, these systems exhibit a very strong hyperfine field at certain La nuclear sites, which is not present in the stoichiometric compounds. Comparison of our NMR results with recent x-ray absorption data at the Mn K edge, suggests the formation of a spin-polarized hole arrangement on the 2p oxygen orbitals as the origin of this effect.Comment: 10 pages, 4 Figures, submitted to PR

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

Investigation on the Behavior of Austenite and Ferrite Phases at Stagnation Region in the Turning of Duplex Stainless Steel Alloys

This paper investigates the deformation mechanisms and plastic behavior of austenite and ferrite phases in duplex stainless steel alloys 2205 and 2507 under chip formation from a machine turning operation. SEM images and EBSD phase mapping of frozen chip root samples detected a build-up of ferrite bands in the stagnation region, and between 65 and 85 pct, more ferrite was identified in the stagnation region compared to austenite. SEM images detected micro-cracks developing in the ferrite phase, indicating ferritic build-up in the stagnation region as a potential triggering mechanism to the formation of built-up edge, as transgranular micro-cracks found in the stagnation region are similar to micro-cracks initiating built-up edge formation. Higher plasticity of austenite due to softening under high strain is seen responsible for the ferrite build-up. Flow lines indicate that austenite is plastically deforming at a greater rate into the chip, while ferrite shows to partition most of the strain during deformation. The loss of annealing twins and activation of multiple slip planes triggered at high strain may explain the highly plastic behavior shown by austenite

Helicobacter Pylori Infection in Pediatric Patients Living in Europe: Results of the EuroPedHP Registry 2013 to 2016

Objectives: The aim of the study was to assess clinical presentation, endoscopic findings, antibiotic susceptibility and treatment success of Helicobacter pylori (H. pylori) infected pediatric patients. Methods: Between 2013 and 2016, 23 pediatric hospitals from 17 countries prospectively submitted data on consecutive H. pylori-infected (culture positive) patients to the EuroPedHP-Registry. Results: Of 1333 patients recruited (55.1% girls, median age 12.6 years), 1168 (87.6%) were therapy naïve (group A) and 165 (12.4%) had failed treatment (group B). Patients resided in North/Western (29.6%), Southern (34.1%) and Eastern Europe (23.0%), or Israel/Turkey (13.4%). Main indications for endoscopy were abdominal pain or dyspepsia (81.2%, 1078/1328). Antral nodularity was reported in 77.8% (1031/1326) of patients, gastric or duodenal ulcers and erosions in 5.1% and 12.8%, respectively. Primary resistance to clarithromycin (CLA) and metronidazole (MET) occurred in 25% and 21%, respectively, and increased after failed therapy. Bacterial strains were fully susceptible in 60.5% of group A, but in only 27.4% of group B. Primary CLA resistance was higher in Southern and Eastern Europe (adjusted odds ratio [ORadj] = 3.44, 95% confidence interval [CI] 2.22-5.32, P < 0.001 and 2.62, 95% CI: 1.63-4.22, P < 0.001, respectively) compared with Northern/Western Europe. Children born outside Europe showed higher primary MET resistance (ORadj = 3.81, 95% CI: 2.25-6.45, P < 0.001). Treatment success in group A reached only 79.8% (568/712) with 7 to 14 days triple therapy tailored to antibiotic susceptibility. Conclusions: Peptic ulcers are rare in dyspeptic H. pylori-infected children. Primary resistance to CLA and MET is markedly dependent on geographical regions of birth and residence. The ongoing survey will show whether implementation of the updated ESPGHAN/NASPGHAN guidelines will improve the eradication success.info:eu-repo/semantics/publishedVersio

Do natural history data predict the movement ecology of fishes in Lake Ontario streams?

Little is known about the movements of most stream fishes, so fisheries managers often rely on natural history data from the literature to make management decisions. Observations of over 15 000 individuals from 37 species across 3 years were used to evaluate four aspects of the reliability of literature data for predicting the movement behaviour of stream fishes: (i) water temperature when fish enter streams; (ii) reasons for moving into the streams; (iii) stream residence times of migrants; and (iv) relative use of lake and stream habitats. Comparisons of our data for arrival times in the streams, water temperature at arrival, and time spent in the streams were highly correlated with literature data, whereas relative use of the lake was not. Further, our detailed data revealed two novel findings: (1) in many species juveniles were also moving into streams, even in those species where adults were clearly spawning in the streams; and (2) adult-sized individuals were moving into streams for nonreproductive purposes. Our results suggest that fishery managers can confidently use natural history information to gain general insights into the movement ecology of fishes, but should also recognize that this information remains incomplete in important ways. </jats:p

Mn magnetism in icosahedral quasicrystalline Al72.4Pd20.5Mn7.1

The unusual magnetism of manganese atoms in an icosahedral Al72.4Pd20.5Mn7.1 single-grain quasicrystal was studied by Al-27 nuclear magnetic resonance (NMR), magnetic susceptibility, and electrical resistivity measurements. Between room temperature and 50 K both the Al-27 NMR linewidth and the frequency shift exhibit a Curie-Weiss-type, 1/(T-theta) temperature dependence. At lower temperatures a significant narrowing of the linewidth, concomitant with a reduction of the frequency shift is observed. These features can be explained by a gradual reduction of the local exchange magnetic field at the position of the Al-27 nuclei that is transferred from the manganese d moments via the conduction electrons. Two possible origins of this phenomenon are discussed: (i) the Kondo-like screening of manganese moments by the conduction electrons and (ii) the ''resistivity'' -damping of the RKKY interaction due to increasing electron localization at low temperatures

An efficient synthesis of 3-fluoro-5-thio-xylofuranosyl nucleosides of thymine, uracil, and 5-fluorouracil as potential antitumor or/and antiviral agents

1,2:5,6-Di-O-isopropylidene-alpha-D-glucofuranose by the sequence of mild oxidation, reduction, fluorination, periodate oxidation, borohydride reduction, and sulfonylation gave 3-deoxy-3-fluoro-1,2-O-isopropylidene-5-O-p-toluenesulfonyl-alpha-D-xylofuranose (5). Tosylate 5 was converted to thioacetate derivative 6, which after acetolysis gave 1,2-di-O-acetyl-5-S-acetyl-3-deoxy-3-fluoro-5-thio-beta-xylofuranose (7). Condensation of 7 with silylated thymine, uracil, and 5-fluorouracil afforded nucleosides 1-(5-S-acetyl-3-deoxy-3-fluoro-5-thio-beta-D-xylofuranosyl) thymine (8), 1-(5-S-acetyl-3-deoxy-3-fluoro-5-thio-beta-D-xylofuranosyl) uracil (9), and 1-(5-S-acetyl-3-deoxy-3-fluoro-5-thio-beta-D-xylofuranosyl) 5-fluorouracil (10). Compounds 8, 9, and 10 are biologically active against rotavirus infection and the growth of tumor cells. (c) 2007 Elsevier Ltd. All rights reserved

Reorientational Motions and Ionic Conductivity in (NH4)2B10H10 and (NH4)2B12H12

We investigated molecular dynamics in two ammonium borane systems from the group of promising ion conductors. The investigation was performed by means of 1H and 11B NMR spectroscopy and spin-lattice relaxation techniques. We identified two reorientational processes, the rotations of NH4 units that are present already at low temperatures, and rotations of large boron cages, B10H10 or B12H12, which are thermally activated and become prominent above 250 K. Activation energies for these processes were determined. In addition, solid-state ion conductivity measurements were conducted to determine poor NH4 conductivity of both systems

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