Search results for " Mineralization"

Sedimentological and tectonic context of Paleoproterozoïque Franceville basin (Gabon) : fluid pressure structures, bitumen and uranium mineralization

2016

Metallogenic deposits within paleproterozoic basins depend on generation and migration of fluids. The aim of this study is to provide a better understanding of tectonic, sedimentological and diagenetic setting of the uranium deposits in the Franceville basin and to characterize hydraulic fracturing impact on fluid migration processes in sandstone reservoirs.Tectonic study define the N180-170° transfer faults, associated with Archean tectonic and the N110-120° longitudinal normal faults. These two fault directions split the Franceville basin into small sub-basins. The longitudinal normal faults are associated with footwall anticlines and hanging wall synclines. The uranium deposits of France…

Direct dating of gold by radiogenic helium: Testing the method on gold from Diamantina, Minas Gerais, Brazil

2013

New analytical developments have made radiogenic helium ( 4 He) applicable to archeological gold artifacts for age determinations. Here we report the application of the U/Th– 4 He method to the direct dating of gold from the historically important gold deposit in Diamantina, Minas Gerais, Brazil. The U/Th– 4 He age of 515 ± 55 Ma for the Diamantina gold is corroborated by a new U/Pb age of 524 ± 16 Ma for rutile recovered from auriferous pockets. These ages tie the Diamantina gold mineralization to the Brasiliano orogenic event, in the context of the Gondwana amalgamation. Our results indicate that U/Th– 4 He dating of gold is possible, opening new perspectives for the dating of gold deposi…

A portable fiber-optic raman spectrometer concept for evaluation of mineral content within enamel tissue

2017

BACKGROUND Measurement of tooth enamel mineralization using a clinically viable method is essential since variation of mineralization may be used to monitor caries risk or in assessing the effectiveness of remineralization therapy. Fiber optic Raman systems are becoming more affordable and popular in context of biomedical applications. However, the applicability of fiber optic Raman systems for measurement of mineral content within enamel tissue has not been elucidated significantly in the prior literature. MATERIAL AND METHODS Human teeth with varying degrees of enamel mineralization were selected. In addition alligator, boar and buffalo teeth which have increasing amount of mineral conten…

Prediction of bone mass gain by bone turnover parameters after parathyroidectomy for primary hyperparathyroidism: neural network software statistical…

2006

Background Primary hyperparathyroidism (pHPT) is the most frequent endocrine hypersecretion disease, and parathyroidectomy is the only curative option, since pharmacologic therapy reduces hypercalcemia but does not impede parathyroid hormone hypersecretion. According to guidelines from the National Institutes of Health, parathyroidectomy is associated with bone mass increase in some asymptomatic patients, while in others bone mass is not changed after surgery. Therefore, we performed the present study in an attempt to elucidate whether a preoperative biochemical bone parameter can be predictive of a significant vertebral bone mass increase in patients with pHPT. Methods For each patient we …

Biological properties of extracellular vesicles and their physiological functions

2015

The authors wish to thank Dr R Simpson and Dr D Taylor for critical reading of the manuscript and acknowledge the Horizon 2020 European Cooperation in Science and Technology programme and its support of our European Network on Microvesicles and Exosomes in Health & Disease (ME-HaD; BM1202 www.cost.eu/COST_Actions/bmbs/Actions/BM1202). In the past decade, extracellular vesicles (EVs) have been recognized as potent vehicles of intercellular communication, both in prokaryotes and eukaryotes. This is due to their capacity to transfer proteins, lipids and nucleic acids, thereby influencing various physiological and pathological functions of both recipient and parent cells. While intensive invest…

Background element content in the lichen Pseudevernia furfuracea: a comparative analysis of digestion methods

2019

In bioaccumulation studies, the interpretation of pollutant contents in the target biomonitor has to be performed by assessing a deviation from an unaltered reference condition. A common strategy consists in the comparison with background element content (BEC) values, often built up by uncritically merging methodologically heterogeneous data. In this respect, the acid digestion of samples was identified as a major step affecting BEC data. Here, the analytical outcomes of two acid mixtures were compared on a set of matched paired samples of the lichen Pseudevernia furfuracea, a widely used biomonitor for which BEC values based on partial digestion were previously provided. The standard refer…

A Biocatalytic Nanomaterial for the Label-Free Detection of Virus-Like Particles

2017

International audience; The design of nanomaterials that are capable of specific and sensitive biomolecular recognition is an on-going challenge in the chemical and biochemical sciences. A number of sophisticated artificial systems have been designed to specifically recognize a variety of targets. However, methods based on natural biomolecular detection systems using antibodies are often superior. Besides greater affinity and selectivity, antibodies can be easily coupled to enzymatic systems that act as signal amplifiers, thus permitting impressively low detection limits. The possibility to translate this concept to artificial recognition systems remains limited due to design incompatibilit…

The genesis of actively growing siliceous stromatolites: Evidence from Lake Specchio di Venere, Pantelleria Island, Italy

2010

This study documents the attributes of siliceous stromatolites growing in the Lake Specchio di Venere, on the volcanic island of Pantelleria, Italy, in a setting characterized by very shallow cold waters and pools and by scattered hydrothermal activity, which exhales mainly CO2, at emission point temperatures of 34 to 58 °C. The saturation indexes indicate that the lake waters are saturated with respect to tridymite, cristobalite, chalcedony and quartz, and slightly undersaturated with respect to amorphous silica. Common roughly laminated and poorly lithified stromatolites show scanning electron microscope (SEM) evidence for silicified microbial mat structures, including biofilms, filamento…

Photoassisted Mineralization of N-Heterocycles in TiO2 Aqueous Suspensions: Fate of the N-Heteroatoms

2008

Comparison of different tillage systems in organic farming : effect of soil structure and organic matter repartition on soil micro-organisms and thei…

2009

Over the last decades, the surface traditionally ploughed has tended to decrease and replaced by shallow working tillage techniques without soil inversion, i.e., no tillage or reduced tillage with tines or discs. These techniques were mostly developed in conventional farming systems but nowadays they are also developed in organic farming systems. Nevertheless, these tillage techniques could generate crop nutrients deficiencies and a deterioration of soil structure, especially during the first years of their application. As the use of synthetic fertilizers is forbidden in organic farming, a decrease of the soil fertility could be very detrimental for crop growth. Indeed, soil micro-organisms…