Chemical passivation of unstable FeO - a Mossbauer study

Highly unstable FeO is chemically passivated by incorporating Cr3+ ions by solid solution technique and forming FexO:Cr3+ single phase material. XRD, chemical analysis and Mossbauer spectroscopy are used for the characterization of the freshly prepared as well as samples aged in the desiccator for nearly three months. Optimum concentration range - 0.25 to 0.75 mole% - of Cr2O3 has been found to be necessary for stabilizing FexO:Cr3+. x is determined by chemical analysis. Mossbauer and XRD studies have confirmed the chemical passivation of unstable FeO

Risk and Return of the Tontine: A Brief Discussion

This article analyzes the stochastic aspects of a tontine using a Gompertz distribution. In particular, the probabilistic and demographic risks of a tontine investment are examined. The expected value and variance of tontine payouts are calculated. Both parameters increase with age. The stochastic present value of a tontine payout is compared with the present value of a fixed annuity. It is shown that only at very high ages the tontine is more profitable than an annuity. Finally, the demographic risks associated with a tontine are discussed. Elasticities are used to calculate the impact of changes in modal age on the tontine payout. It is shown that the tontine payout is very sensitive to changes in modal age

Lack of association between the development and clinical course of Type 1 and Type 2 Diabetes Mellitus and rare T130I variant of the HNF4A gene in the Polish population

Type 2 diabetes (T2DM) is a multifactorial disease related to both environmental and genetic factors. While environmental factors leading to the development for T2DM are well established, the majority of factors responsible for the genetic background of the disease remain unknown. The aim of this study was to test whether a rare variant within the HNF4A gene, Thr130Ile (rs1800961), may influence the development of clinical course of T1DM or T2DM subjects. The analysis included 574 patients with T2DM, 207 T1DM individuals and 284 healthy controls. All subjects were genotyped for the Thr130Ile polymorphism in HNF4A. For T2DM, no differences were found in allele frequencies between cases and controls. The percentage of CT genotype in these groups were 5.7% (33 patients) and 5.6% (16 healthy controls), respectively (p=0.89). For T1DM, the allele frequency was not statistically different from T2DM or control subjects. In conclusion, no association was found between rare variant Thr130Ile of the HNF4A gene and the development of either T2DM nor T1DM in the Polish population

Spatial distribution of radiogenic heat in the Iullemmeden basin – Precambrian basement transition zone, NW Nigeria

The area which transcends the Precambrian basement complex onto the Sokoto sector of the Iullemme-den basin in northwestern Nigeria presents a unique prospect for geothermal exploration research in the absence of regional heat production data, despite its tectonic history and depositional characteristics. In this study, geophysical exploration employing radiometric technique was adopted to classify the petrologic units within the fringes of the Iullemmeden basin and the adjoining crystalline basement complex so as to estimate the radiogenic heat potential within the terrain that may support geothermal considerations. Airborne radiometric measurements acquired over the area were digitized and processed to obtain radioelement concentration maps and the K/Th/U ternary map. Results show that the ranges of measured concentrations of 40K, 238U and 232Th are 4.6 to 18.9%, 0.7 to 4.9 ppm and 4.6 to 18.9 ppm respectively. Radiogenic heat estimation derived from radioelement data within eight petrologic units comprising quaternary sediments, schist, carbonates, shale/clay, younger granites, older granites, gneissic rock and migmatite showed that the lowest radiogenic heat production estimates ranging from 0.27–0.66 μW∙m−3 were recorded in the sedimentary terrain within the quaternary sediments while the highest radiogenic heat production values of between 2.04 to 2.34 μW∙m−3 were recorded in the basement com-plex within gneissic rocks. The spatial distribution of radiogenic heat in the area showed an increased heat gradient within the basement complex and a diminishing heat gradient over the Iullemmeded basin