1,944 research outputs found

    Influence of photodegradation on the removal of color and phenolic compounds from palm oil mill effluent by Arthrospira platensis.

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    Palm oil mill effluent (POME) released from conventional treatment systems poses severe environmental problems due to its dark color, its high chemical oxygen demand (COD), and high content of phenolic compounds. However, the possible biodegradation of phenolic compounds and color by microalgae was not well explored. This research aimed to reveal optimal conditions for pollutant removal through biodegradation by the cyanobacterium Arthrospira platensis. This species was grown under a range of POME fractions and environmental conditions (irradiance, salinity, nutrients) during which growth, final biomass, color, COD, and phenolic compound levels were followed. POME fractions influenced A. platensis growth rate, final biomass, COD, and color removal. The optimization of phenolic compound removal by using central composite design (CCD) response surface methodology (RSM) showed that low light and high initial phenolic compounds promoted the activity of A. platensis to degrade phenolic compounds. The combination of high initial phenolic compounds and high light intensity increased the growth rate up to 0.45 days −1 and final biomass up to 400 mg L −1, while total phenolic compounds were almost completely (94%) removed. Finally, this study showed that phenolic compounds and color degradation from POME were dominated by the activity of photodegradation at high irradiance, while the activity of A. platensis dominated at low light intensity

    Deciphering the complexity of human non-coding promoter-proximal transcriptome.

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    Long non-coding RNAs (lncRNAs) have gained increasing relevance in epigenetic regulation and nuclear functional organization. High-throughput sequencing approaches have revealed frequent non-coding transcription in promoter-proximal regions. However, a comprehensive catalogue of promoter-associated RNAs (paRNAs) and an analysis of the possible interactions with neighboring genes and genomic regulatory elements are missing. Integrating data from multiple cell types and experimental platforms we identified thousands of paRNAs in the human genome. paRNAs are transcribed in both sense and antisense orientation, are mostly non-polyadenylated and retained in the cell nucleus. Transcriptional regulators, epigenetic effectors and activating chromatin marks are enriched in paRNA-positive promoters. Furthermore, paRNA-positive promoters exhibit chromatin signatures of both active promoters and enhancers. Promoters with paRNAs reside preferentially at chromatin loop boundaries, suggesting an involvement in anchor site recognition and chromatin looping. Importantly, these features are independent of the transcriptional state of neighboring genes. Thus, paRNAs may act as cis-regulatory modules with an impact on local recruitment of transcription factors, epigenetic state and chromatin loop organization. This study provides a comprehensive analysis of the promoter-proximal transcriptome and offers novel insights into the roles of paRNAs in epigenetic processes and human diseases. Genomic coordinates of predicted paRNAs are available at https://figshare.com: https://doi.org/10.6084/m9.figshare.7392791.v1 and https://doi.org/10.6084/m9.figshare.4856630.v2. Supplementary data are available at Bioinformatics online

    Separation and measurement of Pa, Th, and U isotopes in Marine sediments by microwave-assisted digestion and multiple collector inductively coupled plasma mass spectrometry

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    This manuscript describes a new protocol for determination of Pa/Th/U in marine sediments. It is based on microwave-assisted digestion and represents an important reduction of working time over conventional hot-plate digestion methods, and the use of HClO(4) is avoided. Although Th and U are completely dissolved with a first microwave step, around 40% of (231)Pa remains undissolved, and a short hot-plate step with reverse aqua regia is required to achieve total digestion and spike equilibration. Next, the method involves a separation of these elements and a further purification of the Pa fraction using Dowex AG1-X8 resin. Separation with Bio-Rad and Sigma-Aldrich resins was compared; although both perform similarly for Th and U, Pa yields are higher with Bio-Rad. Finally, samples are measured using a Nu instruments multiple collector inductively coupled plasma mass spectrometer (MC-ICPMS). Overall chemical yields range around 50% for Pa, 60% for Th, and 70% for U

    Constructing 3D crystal templates for photonic band gap materials using holographic optical tweezers

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    A simple and robust method is presented for the construction of 3-dimensional crystals from silica and polystyrene microspheres. The crystals are suitable for use as templates in the production of three-dimensional photonic band gap (PBG) materials. Manipulation of the microspheres was achieved using a dynamic holographic assembler (DHA) consisting of computer controlled holographic optical tweezers. Attachment of the microspheres was achieved by adjusting their colloidal interactions during assembly. The method is demonstrated by constructing a variety of 3-dimensional crystals using spheres ranging in size from 3 µm down to 800 nm. A major advantage of the technique is that it may be used to build structures that cannot be made using self-assembly. This is illustrated through the construction of crystals in which line defects have been deliberately included, and by building simple cubic structures

    HP-LT rocks exhumed during intra-oceanic subduction: the example of the Escambray massif (Cuba).

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    High-Presssure metabasites embedded in a serpentinite or metasedimentary matrix from the Sancti Spiritus dome (Escambray massif, Central Cuba) have been studied in order to better understand the origine and the evolution of the Northern Carribean boundary plate during the Cretaceous, in a global subduction context. Geochemical analyses (major, trace elements and isotopes) of the high pressure rocks show that they could be partially derived from the Cretaceous calc-alkaline arc described in Central Cuba, these were probably incorporated in the subduction zone by tectonic erosion. The High-Pressure rocks record a prograde path from the epidote bearing amphibolite facies to the barroisite bearing eclogite facies (P = 19 ± 2 Kbar, T = 590 ± 90 °C). These metabasites show evidence of retrogression starting from the glaucophane bearing eclogite facies to the lawsonite bearing blueschist facies. Therefore, these HP/LT rocks are characterized by a counter-clockwise cooling P/T path, which can be explained by the exhumation of HP rocks while the subduction was still active. Concordant geochronological data (Rb/Sr and Ar/Ar) suggest that the main exhumation of HP/LT rocks from the Sancti Spiritus dome occurred 70 Ma ago by top to SW thrusting. The retrogressed trajectory of these rocks, means that the northeast subduction of the Farallon plate continued after 70Ma. The final exhumation can be correlated with the beginning of the collision between the Bahamas platform and the Cretaceous island arc that induced a change of the subduction kinematic

    ATLAS AMBIENTAL DA BACIA DO RIO CORUMBATAÍ V. 2.0 – AMBIENTE MULTIMÍDIA INTERATIVO –

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    The Piracicaba river watershed is considered one of the most impacted areas in the country. The Corumbatai river is an important tributary because provides water for a population about 600,000 people. Any project which helps the improvement and the better understanding of the environment is always welcomed. The Environmental Atlas of the Corumbatai watershed can be considered a valuable tool in the management and protection of the natural resources and is acessed through the address: http://ceapla.rc.unesp.br/altas. The main objective of this project was up-to-date the atlas content, from 2001 until 2005, including researchs of graduate students and professors of the Campus. The content structure as seen on the Main Menu was organized through the Environmental Assessment concept, were the understanding of he landscape as a system is achieved using identification and interpretation techniques applied on the terrain surface characteristics. The specific objectives were: a) A new technological platform to improve the access and the data handling; b) An interactive module to be used by Intermediate School students; c) A benchmark between software’s to be used in the atlas structure. Key words: Atlas. Environment. Cartography. Natural Resources.A bacia do rio Piracicaba é considerada uma das mais impactadas áreas no país. O rio Corumbataí é um importante afluente porque fornece água para uma população aproximada de 600.000 pessoas e qualquer projeto que ajude a melhoria e a melhor compreensão do ambiente é sempre bem vindo. O Atlas Ambiental da Bacia do Rio Corumbataí pode ser considerado uma ferramenta valiosa na gestão e proteção dos recursos naturais da área e pode ser acessado através do endereço: http://ceapla.rc.unesp.br/atlas. O objetivo principal deste projeto foi atualizar o conteúdo do atlas, de 2001 a 2005, incluindo pesquisas de pós-graduandos e professores do Campus. A estrutura do conteúdo como visto no Menu Principal foi organizado através do conceito da Avaliação Ambiental, onde a compreensão da paisagem como um sistema é obtida utilizando-se de técnicas de interpretação e identificação de atributos da superfície terrestre. Os objetivos específicos foram: a) Uma nova plataforma tecnológica para melhorar o acesso e o processamento de dados; b) Um módulo interativo para ser usado por estudantes do Ensino Médio; c) Uma comparação entre aplicativos a serem usados na estrutura do atlas. Palavras-chave: Atlas. Ambiente. Cartografia. Recursos Naturais

    Frutos da Floresta Amazônica. Parte II: Sapotaceae

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    Descriptions and line drawings of fruits and seeds from 153 woody species of the family Sapotaceae occurring in Amazonia are presented, along with their preferred habitat, distribution, habit and seed dispersal.Descrições e desenhos de frutos e sementes de 153 espécies da família Sapotaceae na Amazônia Legal são apresentadas, com informações sobre o hábito, habitat, distribuição geográfica c dispersão de sementes de cada espécie

    Dynamics of a classical gas including dissipative and mean field effects

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    By means of a scaling ansatz, we investigate an approximated solution of the Boltzmann-Vlasov equation for a classical gas. Within this framework, we derive the frequencies and the damping of the collective oscillations of a harmonically trapped gas and we investigate its expansion after release of the trap. The method is well suited to studying the collisional effects taking place in the system and in particular to discussing the crossover between the hydrodynamic and the collisionless regimes. An explicit link between the relaxation times relevant for the damping of the collective oscillations and for the expansion is established.Comment: 4 pages, 1 figur

    Exploring the reactions of small rings.

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    PhDSmall rings are frequently found in natural products as well as incorporated into drugs and agrochemicals in which they impart valuable properties on the biological activity of these compounds. Cyclopropanes are also extremely useful as reagents in organic synthesis, in particular as “umpolung” reagents, allowing access to products which would otherwise be more difficult to synthesise. This thesis will describe forays into the synthesis and further substitution of small rings as well as the iminium-catalysed ring-opening of cyclopropanes. The introduction will outline the uses and properties of cyclopropanes, and will also describe some of the more common ways for incorporating cyclopropanes into larger structures. This will include the Horner–Wadsworth–Emmons procedure which has previously been developed by the group. The second chapter describes efforts towards the iminium-catalysed nucleophilic ring-opening of cyclopropanes. This is followed by Chapter 3, in which the Horner–Wadsworth–Emmons methodology for the synthesis of the cyclopropanes used in Chapter 2 is investigated as a procedure for the synthesis of 4-membered heterocycles. Chapter 4 describes the development of a decarboxylative method for the protodecarboxylation of cyclopropanecarboxylic acids. This was developed as the first step towards decarboxylative cross-coupling of cyclopropanes. Decarboxylative cross-couplings have been extensively developed as environmentally friendly and facile alternatives to the current cross-coupling methods. In Chapter 5 the attempted development of a decarboxylative cross-coupling reaction of cyclopropanes is described. Conclusions and future work are outlined in Chapter 6, followed by the experimental details in Chapter 7.Queen Mary University of London
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