143 research outputs found

    Weak anion-exchange hypercrosslinked sorbent in on-line solid-phase extraction-liquid chromatography coupling to achieve automated determination with an effective clean-up

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    A mixed-mode polymeric sorbent was on-line coupled to liquid chromatography (LC) for the first time and applied it to the selective solid-phase extract a group of pharmaceuticals in complex environmental water samples. The mixed-mode polymeric sorbent is a high-specific surface area hypercrosslinked polymer resin (HXLPP) in the form of monodisperse microspheres further modified with 1,2-ethylenediamine (EDA) moieties. These properties allows its application as a weak anion-exchange (WAX) sorbent in the on-line solid-phase extraction (SPE) coupling. The on-line SPE-LC method developed using the HXLPP-WAX sorbent was successfully applied to percolate a large volume of ultrapure (500 ml), river (250 ml) and effluent sewage (100 ml) water samples. In all the cases, the HXLPP-WAX resin provided near total recoveries of the most acidic compounds studied and clean chromatograms. This is because the ion-exchange interactions enable a washing step to be added to the SPE protocol that removes the compounds with weak acidic, neutral and basic properties from the sample matrix

    Synthesis and application of hypercrosslinked polymers with weak cation-exchange character for the selective extraction of basic pharmaceuticals from complex environmental water samples

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    The synthesis of high specific surface area sorbents (HXLPP-WCX) in the form of hypercrosslinked polymer microspheres with narrow particle size distributions, average particle diameters around 6 µm, and weak cation exchange (WCX) character, is described. The WCX character arises from carboxylic acid moieties in the polymers, derived from the comonomer methacrylic acid. A novel HXLPP-WCX sorbent with an attractive set of chemical and physical properties was then used in an off-line solid-phase extraction (SPE) protocol for the selective extraction of a group of basic compounds from complex environmental samples, a priority being the clean separation of the basic compounds of interest from acidic compounds and interferences. The separation power of the new sorbent for basic pharmaceuticals was compared to two commercially available, mixed-mode sorbents, namely Oasis WCX and Strata X-CW. Under identical experimental conditions, HXLPP-WCX was found to deliver both higher capacity and better selectivity in SPE than either of the two commercially available materials. In an optimised SPE protocol, the HXLPP-WCX sorbent gave rise to quantitative and selective extractions of low µg l-1 levels of basic pharmaceuticals present in 500 ml of river water and 250 ml of effluent waste water

    Hydrophilic hypercrosslinked polymeric sorbents for the solid-phase extraction of polar contaminants from water

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    Three new hypercrosslinked polymers with hydrophilic character arising from hydroxyl moieties in their skeletons have been prepared in microsphere format and applied to the off-line solid-phase extraction (SPE) of polar compounds from water samples. For sample volumes of 1000 ml, the recoveries of various polar pesticides, such as oxamyl, methomyl, selected phenolic compounds, as well as some pharmaceuticals, were close to 90%. The HXLPP-polar polymer with the best performance characteristics was applied to real samples. Its performance was also compared to commercially available sorbents, such as LiChrolut EN (hydrophobic, hypercrosslinked), Oasis HLB (hydrophilic, macroporous) and Isolute ENV+ (hydrophilic, hypercrosslinked); the new sorbent out-performed the commercially available sorbents. The polymer was applied successfully in off-line SPE of river water samples followed by liquid chromatography and ultraviolet detection, providing a good linear range and detection limits of 0.2 μg l-1 for the majority of the compounds, with the exception of oxamyl, methomyl, guaiacol and salicylic acid where the detection limit was 0.5 μg l-1

    Hypercrosslinked materials

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    This chapter describes the chemistry of hypercrosslinked materials, and presents a description of their synthesis, defining physico-chemical features and their most important applications. The synthesis section will examine the different monomers, precursor polymers, reagents and synthetic strategies used to prepare hypercrosslinked materials. Each synthesis section also details the chemical and morphological properties of the hypercrosslinked materials and the main field of application

    Hypercrosslinked materials : preparation, characterisation and applications

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    This review article provides an overview of hypercrosslinking technology. In particular, it covers the preparation and characterisation of hypercrosslinked materials and their applications. The synthesis section examines the different monomers, precursor polymers and reagents used to prepare hypercrosslinked materials, but also the different synthetic approaches disclosed in the literature. The various chemical modification reactions relevant to this area are also reviewed. Several examples of applications for hypercrosslinked materials are described; these applications are grouped into thematic areas such as chromatography, gas storage and the trapping of organic contaminants

    Transforming Yekaterinburg into a Safe, Resilient-Smart and Sustainable City

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    The initiative (since 2014) project described in this paper is a product of a joint innovative research and implementation effort of the Civil Engineering and Architecture Institute, Ural Federal University, the Science and Engineering Centre "Reliability and Safety of Large Systems and Machines", Ural Branch Russian Academy of Sciences (both Yekaterinburg), Start-up OptiCits, Barcelona, Spain and the Old Dominion University, Norfolk, VA, USA. The project is based on using the MAICS convergent technology [1] to create a versatile multi-purpose tool for optimizing the science and art of risk based governance of resilience-smart and sustainable city infrastructure and communities operating in usual and extreme conditions. The tool being developed is tailored to the needs of the City of Yekaterinburg-the capital of the Urals Region and allegedly the third most important and vibrant city of Russia. It is also being offered to the Yekaterinburg City Administration as an every-day decision-support work-tool and addendum to the Strategic Program "Yekaterinburg 2030 - a Safe City"[2] during preparation of the city for winning and conducting the World Expo-2025. Authors believe that the findings of this research would also be useful to the Sverdlovsk Oblast cities of every size and type of communities that inhabit them, including, first and foremost, Nizhny Tagil, Kamensk Uralsky, Serov, Pervouralsk, Revda, Verkhnyaya Pyshma, multiple mono-cities et al. The project also incorporates block-chain technology, smart contracts and digital currency as an effective tool for implementing the project. © 2018 Institute of Physics Publishing. All rights reserved

    Comercio protohistórico: el registro del Nordeste peninsular y circulación de mineral de plomo en Ibiza y el Bajo Priorato (Tarragona)

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    Our recent research shows that lead from the Baix Priorat (Tarragona) mining area circulated in the Phoenician-Tartessian sphere. However, archaeometallurgical analysis of a group of ore and metallic samples from the island of Ibiza reveals the exploitation of local galena, whose use co-existed on the sa Caleta site with ores from Cartagena; on the other hand, lead from the Priorat mining area is not attested. If we also take into account the information provided by 7th-6th centuries BC pottery from Ibiza and Catalonia, a variety of trade networks between the south and the north-east of Iberia emerges

    La nécropole néolithique de la Feixa del Moro (Juberri, Andorre): Examen et nouvelles données

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    At the beginning of the 1980s, a series of archaeological interventions carried out by what was previously called the 'Servei d'Investigacions Arqueológiques del Patrimoni Artistic Nacional d'Andorra' in a Pyrenean valley in Andorra allowed the investigation of the Feixa del Moro site. In a high-altitude area below a series of abandoned terraces, several dwellings and burial structures were located, all of them with chronologies ranging between the Early and the Middle Neolithic (from the mid 5th millennium to the early 4th millennium cal. BC). The distinctiveness of this site does not only lie in its geographical location, nor in the kind of structures discovered, but also in the very good state of preservation of the human bone material recovered from the burials, making Feixa del Moro one of the reference sites for the Neolithic in the Pyrenees and, in general, the Western Mediterranean. So far, sites with a similar conservation of both bones and burial structures are really uncommon. Moreover, the concentration in so small an area, and in the same stratigraphic unit, of such a diversity of evidence, including burials, silos and hearths, is yet more unusual. There are no similar sites in Andorra, or even in the entire Pyrenees. The only other burial site of comparable chronology discovered in the area is the Segudet site, and only a few high-altitude Neolithic dwelling sites are known. Even if cist burials are quite common in the northeast of the Iberian Peninsula and in Southern France, Feixa del Moro is the first that has been found at high altitude. The archaeological work undertaken between 1983 and 1985 provided a picture of a farming community belonging to the so-called 'Sepulcros de fosa' Culture, established in the very heart of the Pyrenees and, thus, highlighted the complexity of Neolithic settlement patterns, even in mountainous zones. At the same time, several analyses of the archaeological materials were already carried out, making Feixa del Moro a reference site for archaeological research even now. Nevertheless, three decades later, new methodologies and the technical advances available are allowing archaeologists to refine old interpretations, to reopen old debates and to carry out new analyses that can improve our understanding of the past. In this respect, since 2011, within the research project 'Aproximación a las primeras comunidades neolíticas del NE peninsular a través de sus prácticas funerarias' (HAR2011-23149), funded by the Spanish Ministry for the Economy and Competitiveness, a group of interdisciplinary researchers have begun to study several Neolithic burial contexts in the northeast of the Iberian Peninsula, among which Feixa del Moro. Following this perspective, in this paper, we present the outcome of the new analyses carried out on the burial goods and of the biochemistry and radiocarbon analyses carried out on the human bone material from the three cist burials of Feixa del Moro, with the aim of better understanding the early farming communities who settled in the Pyrenees. Since the last archaeological work carried out in the 1990s, large quantities of data have been lost. This has produced a certain degree of confusion and misunderstanding that has been repeated in other studies undertaken a posteriori on the site by other scholars. Some of these interpretations need to be revised. That it is why, within the current research project, we are not only bringing in new analyses, but also re-examining all the old written and graphic information available, as well as the state of the conserved archaeological material. The data presented in this paper resume all the available information on the Feixa del Moro site, correcting old mistakes and bias, updating the 1980s archaeological registers and presenting new analyses as well. Our aim is to ensure that Feixa del Moro remains a reference site for the Pyrenean and Western Mediterranean Neolithic. At the same time, we wish to encourage other researchers to undertake new analyses and to embrace new perspectives in order to improve our understanding of Neolithic societies

    Kinetic, Isotherm and Thermodynamic Analysis on Adsorption of Cr(VI) Ions from Aqueous Solutions by Synthesis and Characterization of Magnetic-Poly(divinylbenzene-vinylimidazole) Microbeads

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    The magnetic-poly(divinylbenzene-1-vinylimidazole) [m-poly(DVB-VIM)] microbeads (average diameter 53–212 μm) were synthesized and characterized; their use as adsorbent in removal of Cr(VI) ions from aqueous solutions was investigated. The m-poly(DVB-VIM) microbeads were prepared by copolymerizing of divinylbenzene (DVB) with 1-vinylimidazole (VIM). The m-poly(DVB-VIM) microbeads were characterized by N2 adsorption/desorption isotherms, ESR, elemental analysis, scanning electron microscope (SEM) and swelling studies. At fixed solid/solution ratio the various factors affecting adsorption of Cr(VI) ions from aqueous solutions such as pH, initial concentration, contact time and temperature were analyzed. Langmuir, Freundlich and Dubinin–Radushkvich isotherms were used as the model adsorption equilibrium data. Langmuir isotherm model was the most adequate. The pseudo-first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models were used to describe the adsorption kinetics. The apparent activation energy was found to be 5.024 kJ mol−1, which is characteristic of a chemically controlled reaction. The experimental data fitted to pseudo-second-order kinetic. The study of temperature effect was quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy and entropy changes. The thermodynamic parameters obtained indicated the endothermic nature of adsorption of Cr(VI) ions. Morever, after the use in adsorption, the m-poly(DVB-VIM) microbeads with paramagnetic property were separeted via the applied magnetic force. The magnetic beads could be desorbed up to about 97% by treating with 1.0 M NaOH. These features make the m-poly(DVB-VIM) microbeads a potential candidate for support of Cr(VI) ions removal under magnetic field
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