79 research outputs found

    selective dissolution of woody biomass under hydrothermal conditions

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    Abstract This study analyzes semi-continuous hydrothermal hydrolysis of lignocellulosic biomass operating between 200°C and 300°C with constant inlet water flow rate. Experiments were executed in a novel reactor system that offered a nearly linear temperature behavior during the heating period with heating rates between 40°C/min and 60 °C/min and a nearly flat temperature profile during retention. Experimental results suggest that conversion efficiency improved at higher temperatures. After completion of the batch, solid and liquid products were collected and mass balance closures reached an average of 89%. It was discovered that, regardless of the temperature, a minimum of 90% of the total dissolution occurs within the first 15 minutes of the reaction. This work identifies various stages and conditions that favor the dissolution of certain components (hemicellulose, cellulose or lignin)

    A Spitzer view of protoplanetary disks in the gamma Velorum cluster

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    We present new Spitzer Space Telescope observations of stars in the young ~5 Myr gamma Velorum stellar cluster. Combining optical and 2MASS photometry, we have selected 579 stars as candidate members of the cluster. With the addition of the Spitzer mid-infrared data, we have identified 5 debris disks around A-type stars, and 5-6 debris disks around solar-type stars, indicating that the strong radiation field in the cluster does not completely suppress the production of planetesimals in the disks of cluster members. However, we find some evidence that the frequency of circumstellar primordial disks is lower, and the IR flux excesses are smaller than for disks around stellar populations with similar ages. This could be evidence for a relatively fast dissipation of circumstellar dust by the strong radiation field from the highest mass star(s) in the cluster. Another possibility is that gamma Velorum stellar cluster is slightly older than reported ages and the the low frequency of primordial disks reflects the fast disk dissipation observed at ~5 Myr.Comment: Accepted for publication in the Astrophysical Journal: 32 pages; 11 Figure

    Structural and vibrational study of Bi2Se3 under high pressure

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    The structural and vibrational properties of bismuth selenide (Bi2Se3) have been studied by means of x-ray diffraction and Raman scattering measurements up to 20 and 30 GPa, respectively. The measurements have been complemented with ab initio total-energy and lattice dynamics calculations. Our experimental results evidence a phase transition from the low-pressure rhombohedral (R-3m) phase (B-Bi2Se3) with sixfold coordination for Bi to a monoclinic C2/m structure (B-Bi2Se3) with sevenfold coordination for Bi above 10 GPa. The equation of state and the pressure dependence of the lattice parameters and volume of a and B phases of Bi2Se3 are reported. Furthermore, the presence of a pressure-induced electronic topological phase transition in B-Bi2Se3 is discussed. Raman measurements evidence that Bi2Se3 undergoes two additional phase transitions around 20 and 28 GPa, likely toward a monoclinic C2/c and a disordered body-centered cubic structure with 8-fold and 9- or 10-fold coordination, respectively. These two high-pressure structures are the same as those recently found at high pressures in Bi2Te3 and Sb2Te3. On pressure release, Bi2Se3 reverts to the original rhombohedral phase after considerable hysteresis. Symmetries, frequencies, and pressure coefficients of the Raman and infrared modes in the different phases are reported and discussed.This work was done under financial support from Spanish Ministry of Science and Innovation under Projects No. MAT2007-66129, No. MAT2010-21270-C04-03/04, and No. CSD-2007-00045 and from the Valencian government under Project No. Prometeo/2011-035. It is also supported by the Ministry of Education, Youth and Sports of the Czech Republic Project No. MSM 0021627501

    Pollution monitoring in two urban areas of Cuba by using Tillandsia recurvata (L.) L. and top soil samples: spatial distribution and sources

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    This work provides a comprehensive report on the chemical composition of 47 major and trace elements in Tillandsia recurvata (L.) L. and top soil samples from the cities of Cienfuegos and Santa Clara in Cuba. The main aims were to provide new information on the urban pollution degree in Caribbean urban regions where the availability of data of urban health indicators are very limited and to identify the main pollution sources. The abundance of the analyzed elements at both type of samples were different at each urban regions suggesting the influence of various sources. Top soils were slightly contaminated with Zn, V, Ba, Pb, Ni, Cr, Cu, Co and Hg and seriously contaminated with Ni and Cr in Santa Clara. These and other elements such as Se, S, P, Cd, Mo and Ca where highly enriched in T. recurvata indicating a significant impact of anthropogenic sources in the air quality of both urban areas. Cluster analysis helped us associate most of the elements with an anthropogenic origin with three main pollution sources: road traffic, industrial emissions and oil combustion. The spatial variability was particularly useful to identify some of these sources including the emissions from diesel and fuel oil combustion in power stations, biomass burning and metallurgic industries. The results also showed that V and Ni were strongly associated to the oil combustion and that V/Ni ratio indices in both indicators can be used to trace this type of sources. The results presented in this study confirmed the conclusion that both T. recurvata and top soils can be used as feasible indicators of the health of Caribbean urban ecosystems and the distribution of the main pollution sources that are affecting them

    Long-term survival in patients with non-small cell lung cancer and synchronous brain metastasis treated with whole-brain radiotherapy and thoracic chemoradiation

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    <p>Abstract</p> <p>Background</p> <p>Brain metastases occur in 30-50% of Non-small cell lung cancer (NSCLC) patients and confer a worse prognosis and quality of life. These patients are usually treated with Whole-brain radiotherapy (WBRT) followed by systemic therapy. Few studies have evaluated the role of chemoradiotherapy to the primary tumor after WBRT as definitive treatment in the management of these patients.</p> <p>Methods</p> <p>We reviewed the outcome of 30 patients with primary NSCLC and brain metastasis at diagnosis without evidence of other metastatic sites. Patients were treated with WBRT and after induction chemotherapy with paclitaxel and cisplatin for two cycles. In the absence of progression, concurrent chemoradiotherapy for the primary tumor with weekly paclitaxel and carboplatin was indicated, with a total effective dose of 60 Gy. If disease progression was ruled out, four chemotherapy cycles followed.</p> <p>Results</p> <p>Median Progression-free survival (PFS) and Overall survival (OS) were 8.43 ± 1.5 and 31.8 ± 15.8 months, respectively. PFS was 39.5% at 1 year and 24.7% at 2 years. The 1- and 2-year OS rates were 71.1 and 60.2%, respectively. Three-year OS was significantly superior for patients with N0-N1 stage disease vs. N2-N3 (60 vs. 24%, respectively; Response rate [RR], 0.03; <it>p</it>= 0.038).</p> <p>Conclusions</p> <p>Patients with NSCLC and brain metastasis might benefit from treatment with WBRT and concurrent thoracic chemoradiotherapy. The subgroup of N0-N1 patients appears to achieve the greatest benefit. The result of this study warrants a prospective trial to confirm the benefit of this treatment.</p

    The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

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    The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected

    Synthesis and Structure of Trinuclear W3S4 Clusters Bearing Aminophosphine Ligands and Their Reactivity toward Halides and Pseudohalides

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    The aminophosphine ligand (2-aminoethyl)- diphenylphosphine (edpp) has been coordinated to the W3(ÎŒ- S)(ÎŒ-S)3 cluster unit to afford trimetallic complex [W3S4Br3(edpp)3]+ (1+) in a one-step synthesis process with high yields. Related [W3S4X3(edpp)3]+ clusters (X = F−, Cl−, NCS−; 2+−4+) have been isolated by treating 1+ with the corresponding halide or pseudohalide salt. The structure of complexes 1+ to 4+ contains an incomplete W3S4 cubane-type cluster unit, and only one of the possible isomers is formed: the one with the phosphorus atoms trans to the capping sulfur and the amino groups trans to the bridging sulphurs. The remaining coordination position on each metal is occupied by X. Detailed studies using stopped-flow, 31P{1H} NMR, and ESI-MS have been carried out in order to understand the solution behavior and the kinetics of interconversion among species 1+, 2+, 3+, and 4+ in solution. Density functional theory (DFT) calculations have been also carried out on the reactions of cluster 1+ with the different anions. The whole set of experimental and theoretical data indicate that the actual mechanism of substitutions in these clusters is strongly dependent on the nature of the leaving and entering anions. The interaction between an entering F− and the amino group coordinated to the adjacent metal have also been found to be especially relevant to the kinetics of these reactions

    North African Influences and Potential Bias in Case-Control Association Studies in the Spanish Population

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    BACKGROUND: Despite the limited genetic heterogeneity of Spanish populations, substantial evidences support that historical African influences have not affected them uniformly. Accounting for such population differences might be essential to reduce spurious results in association studies of genetic factors with disease. Using ancestry informative markers (AIMs), we aimed to measure the African influences in Spanish populations and to explore whether these might introduce statistical bias in population-based association studies. METHODOLOGY/PRINCIPAL FINDINGS: We genotyped 93 AIMs in Spanish (from the Canary Islands and the Iberian Peninsula) and Northwest Africans, and conducted population and individual-based clustering analyses along with reference data from the HapMap, HGDP-CEPH, and other sources. We found significant differences for the Northwest African influence among Spanish populations from as low as ≈ 5% in Spanish from the Iberian Peninsula to as much as ≈ 17% in Canary Islanders, whereas the sub-Saharan African influence was negligible. Strikingly, the Northwest African ancestry showed a wide inter-individual variation in Canary Islanders ranging from 0% to 96%, reflecting the violent way the Islands were conquered and colonized by the Spanish in the XV century. As a consequence, a comparison of allele frequencies between Spanish samples from the Iberian Peninsula and the Canary Islands evidenced an excess of markers with significant differences. However, the inflation of p-values for the differences was adequately controlled by correcting for genetic ancestry estimates derived from a reduced number of AIMs. CONCLUSIONS/SIGNIFICANCE: Although the African influences estimated might be biased due to marker ascertainment, these results confirm that Northwest African genetic footprints are recognizable nowadays in the Spanish populations, particularly in Canary Islanders, and that the uneven African influences existing in these populations might increase the risk for false positives in association studies. Adjusting for population stratification assessed with a few dozen AIMs would be sufficient to control this effect

    Database of spatial distribution of non indigenous species in Spanish marine waters

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    Research in marine Spanish waters are focused on several actions to achieve an effectively management on protected areas, with the active participation of the stakeholders and research as basic tools for decision-making. Among these actions, there is one about the knowledge and control on NIS. One of its objectives is the creation of NIS factsheets, which are going to be added to the National Marine Biodiversity Geographical System (GIS) providing complementary information about taxonomic classification, common names, taxonomic synonyms, species illustrations, identification morphological characters, habitat in the native and introduced regions, biological and ecological traits, GenBank DNA sequences, world distribution, first record and evolution in the introduced areas, likely pathways of introduction, effects in the habitats and interaction with native species, and potential management measures to apply. The database will also provide data for (1) the European online platforms, (2) the environmental assessment for the Descriptor 2 (D2-NIS) of the EU Marine Strategy Framework Directive (MSFD), as well as (3) supporting decisions made by stakeholders. It is the result of extensive collaboration among scientist, manager’s and citizen science in the Spanish North-Atlantic, South-Atlantic, Gibraltar Strait-Alboran, Levantine-Balearic and Canary Islands marine divisions, providing an updated overview of the spatial distribution of relevant extended and invasive NIS of recent and established NIS introduced by maritime transport and aquaculture pathways, as well as on cryptogenic or native species in expansion due to the climatic water warming trend
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