473 research outputs found

    CaSiO3-walstromite inclusions in super-deep diamonds

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    Diamonds are considered the unique way to trap and convey real fragments of deep material to the surface of our planet. Over the last thirty years, great strides have been made in understanding of Earth\u2019s lower mantle, mainly thanks to technological and instrumental advances; nevertheless, it is only in the last two decades that a whole range of inclusion parageneses derived from the lower mantle was discovered in diamonds from S\ue3o Luiz (Brazil) (Kaminsky, 2008 and references therein), thereby establishing a \u201cwindow\u201d into the lower mantle. These so-called super-deep diamonds form at depths greater than lithospheric diamonds, more precisely between 300 and 800 km depth, and contain mostly ferropericlase, enstatite (believed to be derived from MgSi-perovskite) and CaSiO3- walstromite (believed to be derived from CaSiO3-perovskite). Even though CaSiO3 not only adopts the perovskite structure with increased pressure and temperature, but also it is considered the dominant Ca-bearing phase in the Earth\u2019s lower mantle (Tamai and Yagi, 1989), at the present day there are no reliable literature data on the pressure at which CaSiO3 crystallizes within diamonds. In order to obtain for the first time a pressure of formation value for CaSiO3-walstromite, several inclusions still trapped in a diamond coming from Juina (Mato Grosso, Brazil) were investigated both by in-situ microRaman spectroscopy and in-situ single-crystal X-ray diffraction. First, we applied \u201csingle-inclusion elastic barometry\u201d as improved by Angel et al. (2014) to determine the pressure of formation of the diamond-inclusion pairs. Starting from the maximum remnant pressure value ever reported (Joswig et al., 2003) and adopting the thermoelastic parameters already present in literature (Swamy and Dubrovinsky, 1997; Liu et al., 2012), we obtained an appar- ent entrapment pressure of 3c7.1 GPa, corresponding to 3c250 km, at 1500 K. The presence of fractures around the inclusions indicates this is a minimum estimate, and it is possible that the entrapment pressure falls at least into the stability field of Ca2SiO4-larnite + CaSi2O5-titanite. In support of this hypothesis we secondly compared our Raman spectra with reference spectra of the same phases obtained from an experimental product of Gasparik et al. (1994). Our preliminary results indicate in at least one inclusion the coexistence of CaSiO3-walstromite + Ca2SiO4-larnite, suggesting that CaSiO3-walstromite forms in sub-lithospheric conditions from the back transfor- mation from CaSiO3-perovskite. Further investigations are in progress in order to find evidence of CaSi2O5-titanite in these inclusions

    Molecular and electronic structure investigation of encapsulated polytiophenes

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    Insulated molecular wires (IMWs) are expected to be applied to various optoelectronic applications due to their unique photophysical, electronic, and mechanical properties which originate from the absence of -stacking.[1] Kazunori et al have succeeded in the synthesis of a self-threading polythiophene with a polyrotaxane-like 3D architecture (PSTB, see Figure 1a), for which an intrawire hole mobility of 0.9 cm2 V−1 s−1 has been measured.[2] In this study we aim to evaluate for the first time the extension of the -conjugation in encapsulated polythiophenes. A comparison between the experimental Raman spectra of the self-threading PSTB polymer with their correspondent oligomers (i.e. 2STB-5STB) suggests that the effective conjugation length in the polymer is longer than five monomer units. Whether the effective conjugation length of the polymer is better described by using the long oligomer extrapolation approach or periodic DFT calculations of the polymer is discussed in detailed by exploiting the very recent potentialities of state-of-the-art quantum chemical simulations of vibrational properties for crystalline solids.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

    Molecularly Imprinted Polymer as Selective Sorbent for the Extraction of Zearalenone in Edible Vegetable Oils

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    A method based on the selective extraction of zearalenone (ZON) from edible vegetable oils using molecularly imprinted polymer (MIP) has been developed and validated. Ultra-high-pressure liquid chromatography coupled with a fluorescence detection system was employed for the detection of zearalenone. The method was applied to the analysis of zearalenone in maize oil samples spiked at four concentration levels within the maximum permitted amount specified by the European Commission Regulation (EC) No. 1126/2007. As a result, the proposed methodology provided high recoveries (>72%) with good linearity (R2 > 0.999) in the range of 10-2000 μg/kg and a repeatability relative standard deviation below 1.8%. These findings meet the analytical performance criteria specified by the European Commission Regulation No. 401/2006 and reveal that the proposed methodology can be successfully applied for monitoring zearalenone at trace levels in different edible vegetable oils. A comparison of MIP behavior with the ones of QuEChERS and liquid-liquid extraction was also performed, showing higher extraction rates and precision of MIP. Finally, the evolution of ZON contamination during the maize oil refining process was also investigated, demonstrating how the process is unable to completely remove (60%) ZON from oil samples

    Exploring the biodiversity of Bifidobacterium asteroides among honey bee microbiomes

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    Bifidobacterium asteroides is considered the ancestor of the genus Bifidobacterium, which has evolved in close touch with the hindgut of social insects. However, recent studies revealed high intraspecies biodiversity within this taxon, uncovering the putative existence of multiple bifidobacterial species, thus, suggesting its reclassification. Here, a genomic investigation of 98 B. asteroides-related genomes retrieved from public repositories and reconstructed from metagenomes of the hindgut of Apis mellifera and Apis cerana was performed to shed light on the genetic variability of this taxon. Phylogenetic and genomic analyses revealed the existence of eight clusters, of which five have been recently characterized with a representative type strain of the genus and three were represented by putative novel bifidobacterial species inhabiting the honeybee gut. Then, the dissection of 366 shotgun metagenomes of honeybee guts revealed a pattern of seven B. asteroides-related taxa within A. mellifera that co-exist with the host, while A. cerana microbiome was characterized by the predominance of one of the novel species erroneously classified as B. asteroides. A further glycobiome analysis unveiled a conserved repertoire of glycosyl hydrolases (GHs) reflecting degradative abilities towards a broad range of simple carbohydrates together with genes encoding specific GHs of each B. asteroides-related taxa

    An Italian Study

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    The literature provides some evidence that the use of violent video games increases the risk for young people to develop aggressive cognitions and even behaviors. We aimed to verify whether exposure to violent video games is linked to problems of aggression in a sample of Italian children. Four questionnaires were administered to 346 children between 7 and 14 years of age, attending primary and secondary schools in Northern Italy. Variables measured were externalization, quality of interpersonal relationships, aggression, quality of coping strategies, and parental stress. Participants who preferred violent games showed higher scores for externalization and aggression. The use of violent video games and age were linked to higher levels of aggression, coping strategies, and the habitual video game weekly consumption of participants. Our data confirm the role of violent video games as risk factors for problems of aggressive behavior and of externalization in childhood and early adolescence

    miniaturized fish for screening of onco hematological malignancies

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    Fluorescence in situ hybridization (FISH) represents a major step in the analysis of chromosomal aberrations in cancer. It allows the precise detection of specific rearrangements, both for diagnost..

    Global transcriptional landscape and promoter mapping of the gut commensal Bifidobacterium breve UCC2003

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    Background: Bifidobacterium breve represents a common member of the infant gut microbiota and its presence in the gut has been associated with host well being. For this reason it is relevant to investigate and understand the molecular mechanisms underlying the establishment, persistence and activities of this gut commensal in the host environment. Results: The assessment of vegetative promoters in the bifidobacterial prototype Bifidobacterium breve UCC2003 was performed employing a combination of RNA tiling array analysis and cDNA sequencing. Canonical −10 (TATAAT) and −35 (TTGACA) sequences were identified upstream of transcribed genes or operons, where deviations from this consensus correspond to transcription level variations. A Random Forest analysis assigned the −10 region of B. breve promoters as the element most impacting on the level of transcription, followed by the spacer length and the 5’-UTR length of transcripts. Furthermore, our transcriptome study also identified rho-independent termination as the most common and effective termination signal of highly and moderately transcribed operons in B. breve. Conclusion: The present study allowed us to identify genes and operons that are actively transcribed in this organism during logarithmic growth, and link promoter elements with levels of transcription of essential genes in this organism. As homologs of many of our identified genes are present across the whole genus Bifidobacterium, our dataset constitutes a transcriptomic reference to be used for future investigations of gene expression in members of this genus

    Genomics of the genus Bifidobacterium reveals species-specific adaptation to the glycan-rich gut environment

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    Bifidobacteria represent one of the dominant microbial groups that occur in the gut of various animals, being particularly prevalent during the suckling period of humans and other mammals. Their ability to compete with other gut bacteria is largely attributed to their saccharolytic features. Comparative and functional genomic as well as transcriptomic analyses have revealed the genetic background that underpins the overall saccharolytic phenotype for each of the 47 bifidobacterial (sub)species representing the genus Bifidobacterium, while also generating insightful information regarding carbohydrate resource sharing and crossfeeding among bifidobacteria. The abundance of bifidobacterial saccharolytic features in human microbiomes supports the notion that metabolic accessibility to dietary and/or host-derived glycans is a potent evolutionary force that has shaped the bifidobacterial genome
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