High-Efficiency Heater for a Thermoluminescence Apparatus

The paper reports on the optimization of a heater used in a Thermoluminescence glow curve apparatus. Two variants of the heater, planchet system and block system, are described. Both variants performed by a cheap material as graphite and designed following cryogenic principles, are very simple constructively, ensure minimum heat losses and require lower power

ON THE LINESHAPE OF SPIN RELAXATION BROADENED MÖSSBAUER SPECTRA OF SOLID POTASSIUM TRIOXALATOFERRATE (III)

Les spectres Mössbauer du trioxalatoferrate de potassium (enrichi de 25 % en 57Fe), élargis en présence de la relaxation électronique, ont été obtenus dans l'intervalle de température de 77 à 300 K. Les spectres ont été analysés à l'aide des théories pour la forme de la ligne, notamment celle d'Afanas'ev et la théorie stochastique de Blume. La meilleure concordance avec les données expérimentales a été obtenue pour le cas de la relaxation isotrope. Le paramètre de relaxation γ est approximativement de 0,012 s/mm et le temps de relaxation spin-spin, donné par la théorie de Blume, de ≈ 2 x 10-9 s.Relaxation broadened Mössbauer spectra of solid potassium trioxalatoferrate (25 % enriched in 57Fe) have been obtained within the temperature range of 77-300 K. The spectra were analysed by means of Afanas'ev theory as well as with Blume stochastic theory for the lineshape. The best fit with experimental data was obtained in the case of isotropic relaxation. The relaxation parameter γ is about 0.012 s/mm and the spin-spin relaxation time given by Blume theory is ≈ 2 x 10-9s

Chemical, Mineralogical, and Mössbauer studies of Medieval pottery from the island of San Lorenzo di Ammiana (Venice)

Recent excavations in the small island of San Lorenzo di Ammiana, one of the first sites inhabited by Venetians in the northern part of the lagoon of Venice, resulted in the finding of continuous archaeological strata dating from the III to the XVI century AD. Selected ceramic sherds have been characterized by minero-petrographic methods, instrumental neutron activation analysis, and Mòssbauer spetroscopy. A differentiation between local and imported productions has been evidenced. An oxidizing atmosphere in baking has been inferred and the firing temperatures have been estimated. Recenti scavi nella piccola isola di San Lorenzo di Ammiana, uno dei primi siti abitati dai Veneziani nella parte nord della Laguna, hanno consentito il ritrovamento di uno strato archeologico continuo dal III al XVI See. Una serie di ceramiche ben selezionate sono state caratterizzate mediante tecniche minero-petrografìche, analisi per attivazione neutronica e spettroscopica Mòssbauer. La produzione locale è stata differenziata da quella importata. È stata dedotta una atmosfera ossidante in cottura e le temperature di cottura sono state determinate

MÖSSBAUER STUDIES OF ELECTRONIC RELAXATION PHENOMENA IN MI3 [Fe (C2O4)3]-XH2O (MI= Li, Na, K, Rb, Cs, NH4)

No abstract availabl

Chemical, mineralogical and Mössbauer studies of Medieval pottery from the island of S. Lorenzo di Ammiana (Venice).

Recent excavations in the small island of San Lorenzo di Ammiana, one of the first sites inhabited by Venetians in the northern part of the lagoon of Venice, resulted in the finding of continuous archaeological strata dating from the III to the XVI century AD. Selected ceramic sherds have been characterized by minero-petrographic methods, instrumental neutron activation analysis, and Mòssbauer spetroscopy. A differentiation between local and imported productions has been evidenced. An oxidizing atmosphere in baking has been inferred and the firing temperatures have been estimated. Recenti scavi nella piccola isola di San Lorenzo di Ammiana, uno dei primi siti abitati dai Veneziani nella parte nord della Laguna, hanno consentito il ritrovamento di uno strato archeologico continuo dal III al XVI See. Una serie di ceramiche ben selezionate sono state caratterizzate mediante tecniche minero-petrografìche, analisi per attivazione neutronica e spettroscopica Mòssbauer. La produzione locale è stata differenziata da quella importata. È stata dedotta una atmosfera ossidante in cottura e le temperature di cottura sono state determinate

MÖSSBAUER AND CHEMICAL ANALYSES OF SOME SEDIMENTS FROM THE ROMANIAN SHORE OF THE BLACK SEA

On a étudié à l'aide de la spectroscopie Mössbauer et par analyse chimique, des sédiments extraits à différentes profondeurs (jusqu'à 1262 m.) provenant du bord de la Mer Noire ainsi que des nodules ferromanganeux extraits jusqu'à 200 m, de profondeur du fond de la Mer Noire, côte roumaine. On a mis en évidence la présence de Fe3+ dans les nodules prélevés jusqu'à 100 m. de profondeur et la coexistence de Fe3+ et de Fe2+ dans les échantillons à 200 m. de profondeur de la plateforme continentale de la Mer Noire. Dans les roches extraites du bord de la mer, on a identifié de l'hématite, de la magnétite, des phases amphiboles ainsi que d'autres oxydes et microéléments.By means of Mössbauer spectroscopy and chemical analyses, sediments collected at different depths (to 1262 m.) on shore as well as ferromanganese nodules to 200 m. depth on the bottom of the Black Sea, romanian coast, have been investigated. The presence of Fe3+ in the nodules to 100 m. depth and the coexistence of Fe3+ and Fe2+ in the samples at 200 m. depth on the continental platform of the Black Sea were evidenced. Hematite, magnetite, some amphiboles phases as well as others non-iron oxides and microelements were identified in the rock samples on shore at different depths

Synthesis and magnetic properties of haematite with different particle morphologies

Abstract Haematite particles of four different morphologies (polyhedral, platelike, needlelike and diskshape) were synthesized by the hydrothermal method. The morphology and average particle diameter (1.4; 7.4; 0.2 and 0.12 mm, respectively) were determined by transmission electron microscopy (TEM) combined with electron diffraction. The haematite samples were studied by transmission Mossbauer spectroscopy in the temperature range 4.2-300 K. In all cases, a weak ferromagnetic phase (WF) was present above the Morin temperature of 230 K and found to coexist with an antiferromagnetic phase (AF) below this temperature. However, the populations of the two phases at 230 K were demonstrated to depend on the morphology of the particles. Moreover, the WF and AF phases exhibit a different dependence of the magnetic texture on temperature and particle morphology

EXAFS investigation of iron local environment in metal-doped titania photocatalysts prepared by hydrothermal and high-energy ball milling routes

Stroke incidence in hemodialysis patients is up to 10 times greater than in the general population and is associated with a worse prognosis. Factors influencing stroke risk by subtype and subsequent prognosis are poorly described in the literature.Retrospective single-center cohort study.2,384 established maintenance hemodialysis patients at a single center from January 1, 2002, to June 1, 2009.Patient demographics, comorbid conditions.Incidence of acute stroke (International Classification of Diseases, 9th Revision codes 430, 431, 432.9, 433.1, and 434.1 with evidence of compatible neuroimaging), patient survival.Cumulative patient survival, incidence of acute fatal and nonfatal stroke.127 strokes occurred during 9,541 total patient-years of follow-up. First (incident) stroke occurred at a rate of 14.9/1,000 patient years (95% CI, 12.2-17.9) with a predominance of ischemic compared with hemorrhagic subtypes (11.2 vs 3.7/1,000 patient-years). 54% of hemorrhagic strokes occurred in patients of South Asian ethnicity compared with ischemic strokes, which occurred predominantly in white patients (45% of events). Diabetes mellitus (HR, 1.92; 95% CI, 1.29-2.85; P = 0.001) and prior cerebrovascular disease (HR, 4.54; 95% CI, 3.07-6.72; P < 0.001) were independently associated with incident cerebrovascular accident on multivariate analysis. Acute stroke was associated with worse patient survival (HR, 3.26; 95% CI, 2.47-4.30; P < 0.001) and overall 1-year mortality of 24%, which was significantly worse in patients with hemorrhagic events (39% vs 19% mortality for ischemic subtypes). Serum albumin level >3.5 g/L (HR, 0.38; 95% CI, 0.19-0.76; P = 0.007) and C-reactive protein level >3.0 mg/l (HR, 1.36; 95% CI, 1.12-1.64; P = 0.002) influenced survival after stroke on multivariate analysis.Retrospective analysis of data cannot prove causality.The high incidence of stroke in hemodialysis patients is associated with high mortality, especially hemorrhagic subtypes. Strict management of hypertension, better appreciation of hemodialysis anticoagulation, and large-scale interventional studies are urgently required to direct prevention and treatment of this significant disease