The smectitic minerals in a bentonite deposit from melo (Uruguay)

International audienceA nearly monomineralic 1.5 m thick bentonite bed sampled in Melo (Uruguay) appears to be a pure high-charge montmorillonite: [Si3.94 Al0.06] (Al1.40 Fe 3+ 0.11 Ti0.02 Mg0.49 Mn0.01) O10 (OH)2 Na0.01 K0.08 Ca0.18. However, contrasting swelling behaviors have been evidenced by fitting the experimental X-ray diffraction patterns recorded on oriented preparations of the same sample in different saturation states. According to the expandability of the layers in the Ca-, K- and K-Ca-saturated (that is saturated first with K + and subsequently with Ca2+) states, three "layer types" were defined. Low-, intermediate-, and high-charge layers are fully, partly, and not expandable, respectively, after K-saturation. Collapse of high-charge layers is not reversible after subsequent Ca-saturation, most likely because of tetrahedral substitutions. These three different layer types are segregated in two distinct randomly interstratified mixedlayer phases. TSA and CEC are shown to depend on the interlayer cation composition

Evidence for acoustic-like plasmons on epitaxial graphene on Pt(111)

The dispersion and the damping of the sheet plasmon in a graphene monolayer grown on Pt(111) have been studied by using angle-resolved electron energy loss spectroscopy. We found that the dispersion relation of the plasmon mode confined in the graphene sheet is linear, as a consequence of the screening by the metal substrate. Present results demonstrate that the presence of an underlying metal substrate could have striking consequences on the plasmon propagation even in the case of a system which exhibits a weak graphene-substrate interaction. Moreover, we found that Landau damping essentially occurs via interband excitations starting above the Fermi wave vector. On the contrary, intraband transitions do not have a significant influence on the collective mod

Use of Green Sulla Forage for Feeding. 1. Effects on Lamb Growth and Gastrointestinal Nematode Parasite Infestation

Recent studies have shown that some forage legumes containing condensed tannins (CT), such as sulla (Hedysarum coronarium L.), can reduce the gastrointestinal nematode burden in sheep (Niezen et al., 1998) and increase post-ruminal protein availability (Waghorn et al., 1994). This study aimed to evaluate the anthelmintic and nutritional properties of sulla forage in relation to its CT content. Thus, the growth performance and the level of nematode infestation of lambs fed sulla were compared with those of lambs fed ryegrass (Lolium multiflorum Lam. subsp. wersterwoldicum), lacking in CT

Clinical Evidence: a useful tool for promoting evidence-based practice?

Background: Research has shown that many healthcare professionals have problems with guidelines as they would prefer to be given all relevent information relevent to decision-making rather than being told what they should do. This study assesses doctors' judgement of the validity, relevance, clarity and usability of the Italian translation of Clinical Evidence (CE) after its free distribution launched by the Italian Ministry of Health. Methods: Opinions elicited using a standardised questionnaire delivered either by mail or during educational or professional meetings. Results: Twenty percent (n = 1350) doctors participated the study. Most of them found CE's content valid, useful and relevant for their clinical practice, and said CE can foster communications among clinicians, particularly among GPs and specialists. Hospital doctors (63%) more often than GPs (48%) read the detailed presentation of individual chapters. Twenty-nine percent said CE brought changes in their clinical practice. Doctors appreciated CE's nature of an evidence-based information compendium and would have not preferred a collection of practice guidelines. Conclusions: Overall, the pilot initiative launched by the Italian Ministry of Health seems to have been well received and to support the subsequent decision to make the Italian edition of Clinical Evidence concise available to all doctors practising in the country. Local implementation initiatives should be warranted to favour doctor's use of CE

Coexistence of halloysite and kaolinite: a study on the genesis of kaolin clays of Campo Alegre Basin, Santa Catarina State, Brazil

Kaolin at Campo Alegre Basin, Santa Catarina State, Brazilwas formed from alteration of volcanic acid rocks. Halloysite clays dominate the clay fraction of the matrix of the kaolin body, whereas a poorly crystalline kaolinite is abundant in veins. Some primary blocky structures have high amounts of illite, in one mine, but in general, only low contents of illite-smectite, illite, chlorite-vermiculite, vermiculite and quartz were identified in the clay fraction of the samples. Toward the top of the mines, hematite and lepidocrocite appear in horizontal red and ochre colored levels and the amount of kaolinite increases compared to halloysite. The vertical zoning of alteration levels, the changes in mineralogy, the positive correlation between depth and Cation Exchange Capacity of the clays, the preservation of different types of rock textures in the kaolin bodies, the dominant tube morphology of the halloysite clays indicate a supergene genesis for the deposits. Criteria to distinguish between supergene and hypogene kaolin are discussed. Transmission Electron Microscopy of the cross sections of halloysite tubes showed polygonal forms that are ascribed to be transitional between kaolinite and halloysite. It is proposed that some of the kaolinite of these deposits be inherited from the dehydration of halloysite tubes

Inter-channel Granger Causality for Estimating EEG Phase Connectivity Patterns in Dyslexia

Methods like Electroencephalography (EEG) and magnetoencephalogram (MEG) record brain oscillations and provide an invaluable insight into healthy and pathological brain function. These signals are helpful to study and achieve an objective and early diagnosis of neural disorders as Developmental Dyslexia (DD). An atypical oscillatory sampling could cause the characteristic phonological difficulties of dyslexia at one or more temporal rates; in this sense, measuring the EEG signal can help to make an early diagnosis of DD. The LEEDUCA study conducted a series of EEG experiments on children listening to amplitude modulated (AM) noise with slow-rhythmic prosodic (0.5–1 Hz) to detect differences in perception of oscillatory ampling that could be associated with dyslexia. The evolution of each EEG channel has been studied in the frequency domain, obtaining the analytical phase using the Hilbert transform. Subsequently, the cause-effect relationships between channels in ach subject have been reflected thanks to Granger causality, obtaining matrices that reflect the interaction between the different parts of the brain. Hence, each subject was classified as belonging or not to the control group or the experimental group. For this purpose, two ensemble classification algorithms were compared, showing that both can reach acceptable classifying erformance in delta band with an accuracy up to 0.77, recall of 0.91 and AUC of 0.97 using Gradient Boosting classifier.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech