Valence of cerium ions in selected ternary compounds from the system Ce-Rh-Sn

Over the last years, intermetallic compounds from the system Ce–Rh–Sn have attracted a considerable attention owing to a rich variety of strongly correlated electron phenomena they exhibit. CeRhSn2, Ce5Rh4Sn10, Ce2Rh3Sn5 and Ce3Rh4Sn13 are magnetically ordered heavy fermion systems [1-5]. Interestingly, for Ce3+xRh4Sn13-x (0.2<x<0.6) no sign of Kondo effect and long range magnetic order was found down to the temperature of 0.4 K [5]. In turn, CeRhSn shows non-Fermi liquid-type thermodynamic and transport properties at low temperatures [6-7] accompanied by an intermediate valence state of the Ce ions. Further, for CeRhSn, CeRhSn2 and CeRh2Sn4 spin fluctuations due to the Rh 4d electrons were also suggested [1,7-8]. The possible coexistence of magnetic phenomena originating from Ce and Rh makes the unequivocal interpretation of experimental data for these compounds very difficult. Consequently, a detailed understanding of the very complex physical properties/behavior requires the use of a broad spectrum of experimental methods, including extended thermodynamic and transport measurements as well as careful investigations of electronic structure. For these systems the full characterization of Ce 4f states in regard to their occupancy, localization in a conduction band and hybridization with the other valence band states is crucial for an unambiguous determination of ground state properties and the low energy excitations. Thus, X-ray absorption spectroscopy (XAS) is here of great use as a bulk probe which is highly sensitive on chemical states of elements. Furthermore, absorption measurements at the Ce LIII edge results in spectra with minimized lifetime broadening, largely unaffected by complicated many-electron final state effects. These spectra can be used to estimate the numbers for the fractional valence of Ce which originates from the strong hybridization between the Ce 4f and the other valence band states related to the valence fluctuation phenomena and/or to the formation of covalent bonds

Microplastics profile along the Rhine River

Microplastics result from fragmentation of plastic debris or are released to the environment as pre-production pellets or components of consumer and industrial products. In the oceans, they contribute to the ‘great garbage patches’. They are ingested by many organisms, from protozoa to baleen whales, and pose a threat to the aquatic fauna. Although as much as 80% of marine debris originates from land, little attention was given to the role of rivers as debris pathways to the sea. Worldwide, not a single great river has yet been studied for the surface microplastics load over its length. We report the abundance and composition of microplastics at the surface of the Rhine, one of the largest European rivers. Measurements were made at 11 locations over a stretch of 820 km. Microplastics were found in all samples, with 892,777 particles km −2 on average. In the Rhine-Ruhr metropolitan area, a peak concentration of 3.9 million particles km −2 was measured. Microplastics concentrations were diverse along and across the river, reflecting various sources and sinks such as waste water treatment plants, tributaries and weirs. Measures should be implemented to avoid and reduce the pollution with anthropogenic litter in aquatic ecosystems

Quantum phase transitions and multicriticality in Ta(Fe1-xVx)2

We present a comprehensive study of synthesis, structure analysis, transport and thermodynamic properties of the C14 Laves phase Ta(Fe1-xVx)2. Our measurements confirm the appearance of spin-density wave (SDW) order within a dome-like region of the x - T phase diagram with vanadium content 0.02 < x < 0.3. Our results indicate that on approaching TaFe2 from the vanadium-rich side, ferromagnetic (FM) correlations increase faster than the antiferromagnetic (AFM) ones. This results in an exchange-enhanced susceptibility and in the suppression of the SDW transition temperature for x < 0.13 forming the dome-like shape of the phase diagram. This effect is strictly related to a significant lattice distortion of the crystal structure manifested in the c/a ratio. At x = 0.02 both FM and AFM energy scales have similar strength and the system remains paramagnetic down to 2 K with an extremely large Stoner enhancement factor of about 400. Here, spin fluctuations dominate the temperature dependence of the resistivity \rho ~ T ^ 3/2 and of the specific heat C/T ~ - log(T) which deviate from their conventional Fermi liquid forms, inferring the presence of a quantum critical point of dual nature.Comment: 9 pages, 13 figure

Renal dimensions measured by ultrasonography in children: variations as a function of the imaging plane and patient position

The purpose of this study was to determine the effect of patient positioning on sonographic renal measurements and to test if the patient position alters the three-dimensional shape of the kidneys. The maximum longitudinal renal length and transverse renal width and depth were measured in the supine and prone position in 100 children (200 kidneys). Age ranged from 6 months to 16 years (mean age 5 years). The results were compared for statistically significant differences. The maximum measured longitudinal renal length was statistically significantly larger in the supine than in the prone position (supine position, left: 8.0cm; right: 7.7cm; prone position, left: 7.9cm, right: 7.6cm; P0.001) and renal volume (P>0.001) in the supine vs. prone positions. Our results show that position-induced reshaping of the kidneys is unlikely to be responsible for the discrepancy in maximum longitudinal renal measurements comparing supine with prone positions. Position-dependent changes in the degree of filling of the renal calyces and pelvis as well as errors in caliper distance measurements for the different scan depths (supine vs. prone) are more likely to be responsible for the encountered differences. Consequently, we recommend to add prone renal length measurements in addition to the supine measurements. In follow-up examinations, renal length measurements should only be compared that have been collected in the same patient positio

Resection of pediatric intracerebral tumors with the aid of intraoperative real-time 3-D ultrasound

Purpose: Intraoperative ultrasound (IOUS) has become a useful tool employed daily in neurosurgical procedures. In pediatric patients, IOUS offers a radiation-free and safe imaging method. This study aimed to evaluate the use of a new real-time 3-D IOUS technique (RT-3-D IOUS) in our pediatric patient cohort. Material and methods: Over 24months, RT-3-D IOUS was performed in 22 pediatric patients (8 girls and 14 boys) with various brain tumors. These lesions were localized by a standard navigation system followed by analyses before, intermittently during, and after neurosurgical resection using the iU22 ultrasound system (Philips, Bothell, USA) connected to the RT-3-D probe (X7-2). Results: In all 22 patients, real-time 3-D ultrasound images of the lesions could be obtained during neurosurgical resection. Based on this imaging method, rapid orientation in the surgical field and the approach for the resection could be planned for all patients. In 18 patients (82%), RT-3-D IOUS revealed a gross total resection with a favorable neurological outcome. Conclusion: RT-3-D IOUS provides the surgeon with advanced orientation at the tumor site via immediate live two-plane imaging. However, navigation systems have yet to be combined with RT-3-D IOUS. This combination would further improve intraoperative localizatio

Cytokine expression during early and late phase of acute Puumala hantavirus infection

<p>Abstract</p> <p>Background</p> <p>Hantaviruses of the family <it>Bunyaviridae </it>are emerging zoonotic pathogens which cause hemorrhagic fever with renal syndrome (HFRS) in the Old World and hantavirus pulmonary syndrome (HPS) in the New World. An immune-mediated pathogenesis is discussed for both syndromes. The aim of our study was to investigate cytokine expression during the course of acute <it>Puumala </it>hantavirus infection.</p> <p>Results</p> <p>We retrospectively studied 64 patients hospitalised with acute <it>Puumala </it>hantavirus infection in 2010 during a hantavirus epidemic in Germany. Hantavirus infection was confirmed by positive anti-hantavirus IgG/IgM. Cytokine expression of IL-2, IL-5, IL-6, IL-8, IL-10, IFN-γ, TNF-α and TGF-β1 was analysed by ELISA during the early and late phase of acute hantavirus infection (average 6 and 12 days after onset of symptoms, respectively). A detailed description of the demographic and clinical presentation of severe hantavirus infection requiring hospitalization during the 2010 hantavirus epidemic in Germany is given. Acute hantavirus infection was characterized by significantly elevated levels of IL-2, IL-6, IL-8, TGF-β1 and TNF-α in both early and late phase compared to healthy controls. From early to late phase of disease, IL-6, IL-10 and TNF-α significantly decreased whereas TGF-β1 levels increased. Disease severity characterized by elevated creatinine and low platelet counts was correlated with high pro-inflammatory IL-6 and TNF-α but low immunosuppressive TGF-β1 levels and <it>vice versa </it>.</p> <p>Conclusion</p> <p>High expression of cytokines activating T-lymphocytes, monocytes and macrophages in the early phase of disease supports the hypothesis of an immune-mediated pathogenesis. In the late phase of disease, immunosuppressive TGF-β1 level increase significantly. We suggest that delayed induction of a protective immune mechanism to downregulate a massive early pro-inflammatory immune response might contribute to the pathologies characteristic of human hantavirus infection.</p

Synthesis and Crystal Growth of Tetragonal Fe1.00Se

Single crystals of tetragonal Fe1.00Se were grown from polycrystalline material by chemical vapor transport reaction at temperatures below 723 K using AlCl3 as transport additive. The plate-shaped single crystals have edge lengths up to 4 mm. The single crystals display complete diamagnetic shielding factor 4piX = -1 below the superconducting transition.Comment: 8 pages, 9 figure

Incidence and pathophysiology of atrioventricular block following mitral valve replacement and ring annuloplasty

Background: In this retrospective study we evaluate the causative mechanisms underlying postoperative atrioventricular block (AVB) following mitral valve replacement and mitral valve annuloplasty. Methods: Between January 1990 and December 2003, 391 patients underwent mitral valve replacement or ring annuloplasty and quadrangular resection. Exclusion criteria were preoperative AV block, two or three valvular procedures, reoperations and procedures combined with coronary artery bypass grafting. The presence of the postoperative AVB was compared with preoperative and intraoperative variables. On 55 post-mortem specimens the relationship between the AV node, AV node artery and mitral valve annulus was investigated. Results: The mean age was 59±14 years and 44% of patients were female. Postoperatively AVB occurred in 92 (23.5%) patients. AVB III was found in 17 (4%) patents, in whom a pacemaker was implanted within median interval of 4 days. Second degree AVB occurred and first degree AVB in five (1.3%) and in 70 (18%) patients respectively. In dry dissected human hearts in 23% of investigated cases the AV node artery was discovered to run close to the annulus of the mitral valve. Conclusions: Data collected in this study showed that, sotalol and amiodarone as well as a prolonged cross-clamp time may slightly influence the 23% incidence of postoperative AVB. The morphological investigation showed that the AV node artery runs in close proximity to the annulus in 23% of cases. We speculate that damage of the AV node artery may play a role in development of AV