Search results for "Minerals"
showing 10 items of 247 documents
Healing of intrabony defects following treatment with a bovine-derived xenograft and collagen membrane
2003
Objectif: L'objectif de cette etude etait de comparer cliniquement le traitement de lesions intra-osseuses profondes avec xenogreffe d'origine bovine (BDX) associe a une membrane collagene bioresorbable pour acceder a la chirurgie a lambeau. Methode: Vingt-huit malades souffrant de parodontite chronique, chacun montrant une lesion intra-osseuse ont ete traites au hasard au BDX+membrane collagene (essai) ou avec chirurgie a lambeau (controle). Les mesures des tissus mous ont ete prises au depart et 1 an apres la therapie. Resultats: Aucune difference dans aucun des parametres etudies n'a ete observee au depart entre les deux groupes. La cicatrisation a ete sans incident pour tous les malades…
A post-trial survey to assess the impact of dissemination of results and unmasking on participants in a 13-year randomised controlled trial on age-re…
2011
Abstract Background The Italian-American Clinical Trial of Nutritional Supplements and Age-Related Cataract was designed to assess the impact of a multivitamin-mineral supplement on age-related cataract. Trial results showed evidence of a beneficial effect of the supplement on all types of cataract combined, opposite effects on two of the three types of cataract (beneficial for nuclear opacities and harmful for posterior sub-capsular opacities) and no statistically significant effect on cortical opacities. No treatment recommendations were made. A post-trial survey was conducted on 817 surviving elderly participants to assess their satisfaction, their understanding of treatment assignment t…
Effect of a two-year supplementation with low doses of antioxidant vitamins and/or minerals in elderly subjects on levels of nutrients and antioxidan…
1997
Eighty-one elderly hospitalized subjects (65 years) were recruited for a double-blind placebo-controlled study to examine low dose supplementation of antioxidant vitamins and minerals on biological and functional parameters of free radical metabolism. Subjects were randomly assigned to one of the four treatment groups, daily receiving for 2 years: placebo group; mineral group: 20 mg zinc, 100 micrograms selenium; vitamin group: 120 mg vitamin C (Vit C), 6 mg beta-carotene (beta CA), 15 mg vitamin E (Vit E); mineral and vitamin group: Zn 20 mg, Se 100 micrograms, Vit C 120 mg, beta CA 6 mg, Vit E 15 mg.Fifty-seven subjects completed the study. A large frequency of Vit C, Zn and Se deficienci…
Identification of carbonate-rich outcrops on Mars by the Spirit rover.
2010
Ancient Carbonate Minerals on Mars The historical presence of liquid water on Mars together with a CO 2 -rich atmosphere should have resulted in the accumulation of large deposits of carbonate minerals. Yet, evidence for the presence of carbonates on the surface of Mars has been scarce. Using data collected by the Mars Exploration Rover, Spirit, Morris et al. (p. 421 , published online 3 June; see the Perspective by Harvey ) now present evidence for carbonate-rich outcrops in the Comanche outcrops within the Gusev crater. The carbonate is a major outcrop component and may have formed in the Noachian era (∼4 billion years ago) by precipitation from hydrothermal solutions that passed through …
Time‐gated Raman and laser‐induced breakdown spectroscopy in mapping of eudialyte and catapleiite
2019
Abstract Raman analysis of rock samples containing rare earth elements (REEs) is challenging due to the strong fluorescence, which may mask the weaker Raman signal. In this research, time‐gated (TG) Raman has been applied to the construction of the mineral distribution map from REE‐bearing rock. With TG Raman, material is excited with a short subnanosecond laser pulse, and the Raman signal is collected within a picosecond‐scale time window prior to the formation of a strong fluorescent signal by means of single‐photon avalanche diode array. This allows signal readout with a significantly reduced fluorescence background. TG Raman maps are used to reveal the location of valuable minerals and …
The behaviour of zirconium and hafnium during water-rock interaction
2018
Abstract Zr and Hf are two elements with same ionic charge and similar ionic size at a given coordination number. Despite the Zr/Hf ratio is quite constant in meteorites and lithospheric rocks, in natural waters can be either higher or lower compared to values of interacting minerals and rocks. Here, we reanalyze very recent published and present new data on continental and brine waters indicating that the Zr and Hf behavior is dependent on the properties of the authigenic phases formed during the water-rock interaction process. Our results show that water pH in the range between 1 and 9 and water ionic strength in the range between 0.001 and 4 mol kg−1 are responsible for the change of the…
Influence of Glass Additions on Illitic Clay Ceramics
2020
A mixture of an illitic clay and waste glass was prepared and studied during the sintering process. The illitic clay, from the Liepa deposit (Latvia), and green glass waste (GW) were disintegrated to obtain a homogeneous mixture. The addition of disintegrated GW (5&ndash
A multi-technique characterisation of cronstedtite synthetized by iron-clay interaction in a step by step cooling procedure
2013
International audience; The cooling of steel containers in radioactive-waste storage was simulated in a step-by-step experiment from 90 to 40 degrees C. Among newly formed clay minerals observed in run products, cronstedtite was identified by a number of analytical techniques (powder X-ray diffraction, transmission electron microscopy, and scanning electron microscopy). Cronstedtite has not previously been recognized to be so abundant and so well crystallized in an iron-clay interaction experiment. The supersaturation of experimental solutions with respect to cronstedtite was due to the availability of Fe and Si in solution, as a result of the dissolution of iron metal powder, quartz, and m…
The pore structure of compacted and partly saturated MX-80 bentonite at different dry densities
2014
Compacted MX-80 bentonite is a potential backfill material in radioactive-waste repositories. Pore space in MX-80 has been the subject of considerable debate. 3D reconstructions of the pore space based on tomographic methods could provide new insights into the nature of the pore space of compacted bentonites. To date, few such reconstructions have been done because of problems with the preparation of bentonite samples for electron microscopy. The nanoscale intergranular pore space was investigated here by cryo-Focused Ion Beam nanotomography (FIB-nt) applied to previously high-pressure frozen MX-80 bentonite samples. This approach allowed a tomographic investigation of the in situ microstru…
Interfacial premelting of ice in nano composite materials
2018
Physical chemistry, chemical physics 21, 3734 - 3741 (2019). doi:10.1039/C8CP05604H