The crystal structure of rathite-I

Die Kristallstruktur von Rathit-I wurde mittels dreidimensionaler Intensitätsdaten bestimmt. Vier Formeleinheiten (Pb,Tl)3As4(As,Ag)S10 sind in der Einheitszelle der Symmetrie Ρ 21/a mit a = 25,16 Å, 6 = 7,94 Å, c = 8,47 Å, β = 100° 28' enthalten. Die wahre Symmetrie von Rathit-I ist möglicherweise triklin. Die Lösung lieferten die Ähnlichkeit der Struktur mit derjenigen von Rathit-III und spezielle Verhältnisse der Röntgendiagramme. Von drei unabhängigen Pb(Tl)-Atomen sind zwei von neun S-Atomen umgeben, das andere von sieben. Die As-Atome weisen trigonal-pyramidale Koordination durch die S-Atome auf. Von einem As-Atom wird angenommen, daß es statistisch von zwei verschiedenen trigonal -pyramidalen S-Koordinationen umgeben wird. Ein anderes As-Atom ist teilweise durch Ag ersetzt. Die Struktur besteht aus zweierlei Schichten parallel zu (100). Die erste Art hat die Zusammensetzung (Pb,Tl)S3 und besteht aus den Koordinationspolyedern um die Pb(Tl)-Atome mit Neuner-Koordination. Die zweite Art ist aus Pb(Tl)-, As(Ag)- und S-Atomen zusammengesetzt, welche ein deformiertes PbS-Gitter bilden. Trigonale As-S3-Pyramiden sind zu Ketten endlicher Länge vereinig

Assessment of Cement Durability in Repository Environment

Portland cement paste is proposed as the material to filling in the annulus between the casing of a borehole and the geological formation in a deep repository for spent sealed radiation sources in Brazil. The cement paste is intended to function as structural material, an additional barrier against the migration of radionuclides outside the repository, and as a blockage against the transport of water between the different strata of the geological setting. The objective of this research is to investigate the behavior of the cement paste and to estimate its service life. In this paper we present the results of mechanical strength measurements and chemical and mineralogical analysis of samples to detect the changes caused by radiation, temperature and aggressive chemicals of groundwater to which the material will be exposed. Methods of analysis included Inductively Coupled Plasma Atomic Emission Spectroscopy, Ion Chromatography, XRay Diffraction, and Thermo Gravimetric Analysi

Re: Lack of association between Matrix Metalloproteinase-1 (MMP-1) promoter polymorphism and risk of renal cell carcinoma

Federal University of São Paulo Section of NephrologyFederal University of São Paulo Section of UrologyInstitute of Energetic and Nuclear ResearchUNIFESP, Section of NephrologyUNIFESP, Section of UrologySciEL

Serum trace element concentrations in children with chronic renal failure

PublishedN/

Nucleation of Al3Zr and Al3Sc in aluminum alloys: from kinetic Monte Carlo simulations to classical theory

Zr and Sc precipitate in aluminum alloys to form the compounds Al3Zr and Al3Sc which for low supersaturations of the solid solution have the L12 structure. The aim of the present study is to model at an atomic scale this kinetics of precipitation and to build a mesoscopic model based on classical nucleation theory so as to extend the field of supersaturations and annealing times that can be simulated. We use some ab-initio calculations and experimental data to fit an Ising model describing thermodynamics of the Al-Zr and Al-Sc systems. Kinetic behavior is described by means of an atom-vacancy exchange mechanism. This allows us to simulate with a kinetic Monte Carlo algorithm kinetics of precipitation of Al3Zr and Al3Sc. These kinetics are then used to test the classical nucleation theory. In this purpose, we deduce from our atomic model an isotropic interface free energy which is consistent with the one deduced from experimental kinetics and a nucleation free energy. We test di erent mean-field approximations (Bragg-Williams approximation as well as Cluster Variation Method) for these parameters. The classical nucleation theory is coherent with the kinetic Monte Carlo simulations only when CVM is used: it manages to reproduce the cluster size distribution in the metastable solid solution and its evolution as well as the steady-state nucleation rate. We also find that the capillary approximation used in the classical nucleation theory works surprisingly well when compared to a direct calculation of the free energy of formation for small L12 clusters.Comment: submitted to Physical Review B (2004

The impact of DMARD and anti-TNF therapy on functional characterization of short-term T-cell activation in patients with rheumatoid arthritis - A follow-up study

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by a systemic dysfunction of T-cells. In this study we tested the impact of DMARD and anti-TNF agents on short-term activation characteristics of T-cells. We enrolled 12 patients with newly diagnosed RA (naïve RA) who were treated with methothrexate (MTX) and glucocorticsteroid (GCS) and 22 patients with established RA non responding to conventional DMARD therapy who were treated with different anti-TNF agents. Nine healthy volunteers served as controls. Blood samples were taken at baseline, then at 4th and 8th week of therapy. The characteristics of several intracellular activation processes during short-term activation of T-cells including cytoplasmic Ca2+ level, mitochondrial Ca2+ level, reactive oxygen species (ROS) and nitric oxide (NO) generation were determined by a novel flow-cytometry technique. At baseline, the tested processes were comparable to controls in naïve RA. During GCS therapy, cytoplasmic Ca2+ level and ROS generation decreased. After the addition of MTX to GCS cytoplasmic Ca2+ level became comparable to controls, while ROS generation decreased further. In DMARD non responders, cytoplasmic Ca2+ level was higher than controls at baseline. The cytoplasmic Ca2+ level became comparable to controls and ROS generation decreased during each of the three anti-TNF-α agent therapies. Mitochondrial Ca2+ level and NO generation were unaltered in all of the patient groups. These results indicate that intracellular machinery is affected in T-cells of RA patients. This may alter the behavior of T-cells during activation. Different therapeutic approaches may modulate the abnormal T-cell functions. © 2014 Szalay et al

Trace elements in hemodialysis patients: a systematic review and meta-analysis

<p>Abstract</p> <p>Background</p> <p>Hemodialysis patients are at risk for deficiency of essential trace elements and excess of toxic trace elements, both of which can affect health. We conducted a systematic review to summarize existing literature on trace element status in hemodialysis patients.</p> <p>Methods</p> <p>All studies which reported relevant data for chronic hemodialysis patients and a healthy control population were eligible, regardless of language or publication status. We included studies which measured at least one of the following elements in whole blood, serum, or plasma: antimony, arsenic, boron, cadmium, chromium, cobalt, copper, fluorine, iodine, lead, manganese, mercury, molybdenum, nickel, selenium, tellurium, thallium, vanadium, and zinc. We calculated differences between hemodialysis patients and controls using the differences in mean trace element level, divided by the pooled standard deviation.</p> <p>Results</p> <p>We identified 128 eligible studies. Available data suggested that levels of cadmium, chromium, copper, lead, and vanadium were higher and that levels of selenium, zinc and manganese were lower in hemodialysis patients, compared with controls. Pooled standard mean differences exceeded 0.8 standard deviation units (a large difference) higher than controls for cadmium, chromium, vanadium, and lower than controls for selenium, zinc, and manganese. No studies reported data on antimony, iodine, tellurium, and thallium concentrations.</p> <p>Conclusion</p> <p>Average blood levels of biologically important trace elements were substantially different in hemodialysis patients, compared with healthy controls. Since both deficiency and excess of trace elements are potentially harmful yet amenable to therapy, the hypothesis that trace element status influences the risk of adverse clinical outcomes is worthy of investigation.</p