1,356 research outputs found

    RNA catalysis in model protocell vesicles.

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    We are engaged in a long-term effort to synthesize chemical systems capable of Darwinian evolution, based on the encapsulation of self-replicating nucleic acids in self-replicating membrane vesicles. Here, we address the issue of the compatibility of these two replicating systems. Fatty acids form vesicles that are able to grow and divide, but vesicles composed solely of fatty acids are incompatible with the folding and activity of most ribozymes, because low concentrations of divalent cations (e.g., Mg(2+)) cause fatty acids to precipitate. Furthermore, vesicles that grow and divide must be permeable to the cations and substrates required for internal metabolism. We used a mixture of myristoleic acid and its glycerol monoester to construct vesicles that were Mg(2+)-tolerant and found that Mg(2+) cations can permeate the membrane and equilibrate within a few minutes. In vesicles encapsulating a hammerhead ribozyme, the addition of external Mg(2+) led to the activation and self-cleavage of the ribozyme molecules. Vesicles composed of these amphiphiles grew spontaneously through osmotically driven competition between vesicles, and further modification of the membrane composition allowed growth following mixed micelle addition. Our results show that membranes made from simple amphiphiles can form vesicles that are stable enough to retain encapsulated RNAs in the presence of divalent cations, yet dynamic enough to grow spontaneously and allow the passage of Mg(2+) and mononucleotides without specific macromolecular transporters. This combination of stability and dynamics is critical for building model protocells in the laboratory and may have been important for early cellular evolution

    Toy Train Group 1

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    Create a toy train that lays its own tracks

    Potential Effects of Industrial Air Pollution and Wood-Product Supply and Demand, and Structure of the Wood-Products Industry, in Poland

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    This study aimed to determine potential changes in the production structure of the wood-processing industry up to 2020, resulting from unfavorable impact of industrial pollutants upon forests in Poland. The paper consists of four chapters. In the first section, forecasts of consumer demand for forest products, based on patterns of actual demand, are presented. The structure of industrial demand for wood assortments, and the degree to which it is met, are the topics of the second chapter. In the third chapter, we present forecasts of the possibilities of wood-raw-material consumption by industry with regard to the unfavorable impact of industrial pollution. The last chapter contains forecasts of production regarding foreseen changes in the structure of the wood-processing industry, taking into account qualitative changes in wood raw-material and expected changes in techniques and technology. Our results show that, up to 2020, negative effects of industrial pollutants on forests will have a significant influence on the degree of meeting consumer demands for wood products

    The Emergence of Competition Between Model Protocells

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    The transition from independent molecular entities to cellular structures with integrated behaviors was a crucial aspect of the origin of life. We show that simple physical principles can mediate a coordinated interaction between genome and compartment boundary, independent of any genomic functions beyond self-replication. RNA, encapsulated in fatty acid vesicles, exerts an osmotic pressure on the vesicle membrane that drives the uptake of additional membrane components, leading to membrane growth at the expense of relaxed vesicles, which shrink. Thus, more efficient RNA replication could cause faster cell growth, leading to the emergence of Darwinian evolution at the cellular level

    In vitro selection of RNA aptamers against a composite small molecule-protein surface

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    A particularly challenging problem in chemical biology entails developing systems for modulating the activity of RNA using small molecules. One promising new approach towards this problem exploits the phenomenon of ‘surface borrowing,’ in which the small molecule is presented to the RNA in complex with a protein, thereby expanding the overall surface area available for interaction with RNA. To extend the utility of surface borrowing to include potential applications in synthetic biology, we set out to create an ‘orthogonal’ RNA-targeting system, one in which all components are foreign to the cell. Here we report the identification of small RNA modules selected in vitro to bind a surface-engineered protein, but only when the two macromolecules are bound to a synthetic bifunctional small molecule

    Real Time Global Tests of the ALICE High Level Trigger Data Transport Framework

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    The High Level Trigger (HLT) system of the ALICE experiment is an online event filter and trigger system designed for input bandwidths of up to 25 GB/s at event rates of up to 1 kHz. The system is designed as a scalable PC cluster, implementing several hundred nodes. The transport of data in the system is handled by an object-oriented data flow framework operating on the basis of the publisher-subscriber principle, being designed fully pipelined with lowest processing overhead and communication latency in the cluster. In this paper, we report the latest measurements where this framework has been operated on five different sites over a global north-south link extending more than 10,000 km, processing a ``real-time'' data flow.Comment: 8 pages 4 figure

    Study of W± boson in the ALICE muon spectrometer: considerations and analysis using the HLT tool

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    W± bosons produced in proton-proton collisions can be observed in the ALICE muon spectrometer via their decay into single muons at a transverse momentum, pt ~ Mw/2 40 GeV/c. However the identification of these single muons is complicated by a large amount of muonic background, especially in the low pt region. Therefore, it is necessary to apply precise pt cuts below the region of interest. This can be done by means of the High Level Trigger (HLT). In this paper we present the performance of detecting high pt muons at the HLT level. In order to improve the momentum resolution of the L0 trigger, fast clusterization of the tracking chambers together with L0 trigger matching and fast tracking reconstruction is applied. This will reduce the background in the high pt muon analysis

    Improved Method of Springback Compensation in Metal Forming Analysis

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    This paper presents an innovative compensation method for both forming and trimming die for the construction of vehicle parts manufactured by a transfer press. This method allows one to optimize the accuracy of compensation, consequently reducing springback in a more exact way than currently used methods, which account only for the influence of trimming on springback without generating compensated surfaces for the trimming die and the next forming operation. Moreover, there is a possibility to include the positioning effect during multioperation forming because of the huge impact of results on separate operations. When the positioning is not considered between operations there are problems with a proper shape even if the final part has the correct geometry. These problems generate some additional costs during the die production, which can be avoided by using the multioperation compensation

    Building zeolites from precrystallized units: nanoscale architecture

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    This is the peer reviewed version of the following article: Angew. Chem. Int. Ed. 2018, 57, 15330 15353, which has been published in final form at https://doi.org/10.1002/anie.201711422. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] Since the early reports by Barrer in the 1940s on converting natural minerals into synthetic zeolites, the use of precrystallized zeolites as crucial inorganic directing agents to synthesize other crystalline zeolites with improved physicochemical properties has become a very important research field, allowing the design, particularly in recent years, of new industrial catalysts. This Review highlights how the presence of some crystalline fragments in the synthesis media, such as small secondary building units (SBUs) or layered substructures, not only favors the crystallization of other zeolites with similar SBUs or layers, but also permits control over important parameters affecting their catalytic activity (chemical composition, crystal size, or porosity, etc.). Recent advances in the preparation of 3D and 2D zeolites through seeding and zeolite-to-zeolite transformation processes will be discussed extensively in this Review, including their preparation in the presence or absence of organic structure-directing agents (OSDAs). The aim is to introduce general guidelines for more efficient approaches for target zeolites.This work has been supported by the Spanish Government (MINECO through "Severo Ochoa" (SEV-2016-0683) and MAT2015-71261-R), by the European Union through ERC-AdG-2014-671093 (SynCatMatch), and by the Fundacion Ramon Areces (through the "Life and Materials Science" program).Li, C.; Moliner Marin, M.; Corma Canós, A. (2018). Building zeolites from precrystallized units: nanoscale architecture. Angewandte Chemie International Edition. 57(47):15330-15353. https://doi.org/10.1002/anie.201711422S15330153535747Cundy, C. S., & Cox, P. A. (2005). The hydrothermal synthesis of zeolites: Precursors, intermediates and reaction mechanism. Microporous and Mesoporous Materials, 82(1-2), 1-78. doi:10.1016/j.micromeso.2005.02.016Martínez, C., & Corma, A. (2011). Inorganic molecular sieves: Preparation, modification and industrial application in catalytic processes. 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    Fatigue Fracture Analysis of Composite Plates with an Elliptical Hole

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    In this study, the analysis of fatigue fracture of composite plates with an elliptical hole having a longer axis parallel to the direction of the applied force is performed. The plates were made of glass/epoxy preimpregnate consisting of eight individual layers with the fiber configuration of [ +45° / -45° / +45° / -45° ]S. The mechanical properties and material constants were assessed by performing static tensile tests and analytical calculations. The nominal fiber volume in the composite plates was experimentally determined. The test method of infrared passive thermography was implemented as a non-destructive testing, which provided the determination of the temperature distribution throughout the entire fatigue process. The thermograms were obtained and compared to the real-time photographs of the plates. Moreover, the specific results concerning fatigue phenomena and basic composite failure forms, which usually occur during the fatigue process, are discussed in detail. The theoretically predicted three individual fatigue fracture phases were corroborated the original test results. The first-ply failure (FPF) occurred in the local stress concentration area and propagated in the direction of the corners, along the fibers. The failure forms observed in the static and fatigue tests were nearly the same. Moreover, the comparative analysis of the fatigue fracture of laminates with three various types of holes was performed and presented in the graphical and tabular forms.Проанализировано усталостное разрушение композитных пластин с эллиптическим отверстием, более длинная ось которого параллельна направлению приложенной силы. Пластины изготовлены из стеклоэпоксидного препрега, состоящего из восьми отдельных слоев с ориентацией волокон [ +45° / -45° / +45° / -45° ]S Механические свойства и константы мате риала исследовались и определялись по результатам статических испытаний на растяжение и экспериментальных измерений. Экспериментально определен также номинальный объем волокон в композитных пластинах. Метод экспериментального исследования на основе данных пассивной инфракрасной термографии был реализован как неразрушающий метод. Это позволило определять расположение температур при анализе усталостного разрушения. Полученные термограммы сравнивались с фотографиями пластин в реальном времени. Представлена конкретная информация об усталости и основных видах разрушения композита, что обычно имеет место в процессе усталости. В подтверждение теоретических положений при экспериментальном исследовании установлены три стадии усталостного разрушения. Разрушение первого слоя происходило в локальной зоне концентрации напряжений и распространялось вдоль волокон в направлении углов. Виды разрушения, наблюдаемые при статических и усталостных испытаниях, были почти одинаковыми. Приведены данные сравнения усталостного разрушения многослойного материала с тремя различными типами отверстий
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