A mechanistic investigation of Pickering emulsion polymerization

Pickering emulsion polymerization offers a versatile way of synthetising hybrid core–shell latexes where a polymer core is surrounded by an armour of inorganic nanoparticles. A mechanistic understanding of the polymerization process is limited which restricts the use of the technique in the fabrication of more complex, multilayered colloids. In this paper clarity is provided through an in-depth investigation into the Pickering emulsion polymerization of methyl methacrylate (MMA) in the presence of nano-sized colloidal silica (Ludox TM-40). Mechanistic insights are discussed by studying both the adsorption of the stabiliser to the surface of the latex particles and polymerization kinetics. The adhesion of the Pickering nanoparticles was found not to be spontaneous, as confirmed by cryo-TEM analysis of MMA droplets in water and monomer-swollen PMMA latexes. This supports the theory that the inorganic particles are driven towards the interface as a result of a heterocoagulation event in the water phase with a growing oligoradical. The emulsion polymerizations were monitored by reaction calorimetry in order to establish accurate values for monomer conversion and the overall rate of polymerizations (Rp). Rp increased for higher initial silica concentrations and the polymerizations were found to follow pseudo-bulk kinetics

Trapped in a roman well: amphibians and reptiles from Tenuta Zuccarello near Marcon, Venice, Italy

Altres ajuts: this work has been supported by the Generalitat de Catalunya (CERCA Program).The Roman well US 100, located in the Tenuta Zuccarello near Venice, has yielded a large number of different animals remains, dated back to 2000 ± 40 years BP. Amphibians and reptiles are represented by at least 11 taxa: two caudates (Lissotriton gr. L. vulgaris, Triturus gr. T. cristatus), three anurans (Bombina sp., Bufo bufo, Rana dalmatina vel R. latastei), one turtle (Emys orbicularis), at least two lizards (Anguis gr. A. fragilis, Lacerta gr. L. viridis), and three snakes (Natrix natrix, cf. Coronella sp., Hierophis viridiflavus). Based on this assemblage, an ecotonal environment with water bodies, open and humid areas, as well as dry and sunny areas, is here suggested for the surroundings of the well when the sediments deposited.Most of the identified taxa were found in other Venetian sites since the Pleistocene, suggesting a certain continuity in the amphibians and reptiles population in Veneto during the Quaternary. The only taxon that is absent from the Venetian Lagoon today is Bombina. Its presence in a 2000-years-old archaeological site proves that the disappearance of suitable environments for the genus is a recent phenomenon near the Lagoon. This may support future reintroduction projects in suitable areas, following a conservation palaeobiology perspective

Design, Synthesis and Evaluation of Chromo-fluorogenic Probes for Contaminating Species

The present PhD thesis entitled “Design, Synthesis and Evaluation of Chromofluorogenic Probes for Contaminating Species” is focused on the development of new chromo-fluorogenic sensors based on the principles of molecular recognition. The first part of this thesis is focused on the design and synthesis of suitable organic compounds as sensors for metal cations. The selected sensing paradigm was the binding site-signalling subunit approach. The synthetized receptors employs a chromophore (fluorescein or BODIPY) skeleton as signalling subunit and it is functionalized with aminoethoxy moieties as binging site; the metal coordination reduces the electron-donating ability of the nitrogen atom conjugated to the chromophore resulting in optical changes noticeable to the naked-eye. The sensing behavior is highly selective to trivalent cations (Fe3+, Al3+ and Cr3+) with remarkable limits of detection. The receptors based on BODIPYdyes retain the sensing abilities in mixed aqueous solutions. The remaining chapters of the thesis are centered in the detection and removal of nerve agents surrogates. The design, synthesis, characterization and application of new BODIPY chemosensors were studied. These chemosensors were designed containing different reactive sites in order to avoid interferences produced by acids or hydrolysis products, and also be able to distinguish between the different G-nerve agent mimics (DCNP and DFP). The BODIPY-probes allows screening of nerve agent surrogates with remarkable limits of detection and optical changes noticeable to the naked-eye. The sensing abilities are retained in solid support, allowing practical application in real-time monitoring by simple colorimetric tests. The displacement assay approach has been used to develop a selective sensor for V-nerve agent surrogates versus G-type. For this purpose, two Eu3+ and Au3+ BODIPY-complexes were prepared. In this case, V-surrogate is capable of coordinate the metallic center, releasing the BODIPY ligand. This causes a change in the optical properties visible to the naked-eye. Finally, the use of supramolecular-based organocatalyst for destruction of OP nerve agent surrogates was studied. Hydrolysis studies were performed in presence of 1,3-diindolylureas and thioureas, amines, aminoalcohol and glycols. Addition of catalyst enhances the electrophilic character of the P atom, and the final nucleophilic attack of water that results in the formation of the corresponding less toxic organophosphate derivatives, thus higher hydrolysis rates are obtained.Barba Bon, A. (2014). Design, Synthesis and Evaluation of Chromo-fluorogenic Probes for Contaminating Species [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48521TESI

Toward sulfur-free RAFT polymerization induced self-assembly

Polymerization induced self-assembly (PISA) using methacrylate-based macromonomers as RAFT agents is an unexplored, attractive route to make self-assembled colloidal objects. The use of this class of RAFT-agents in heterogeneous polymerizations is however not trivial, because of their inherent low reactivity. In this work we demonstrate that two obstacles need to be overcome, one being control of chain-growth (propagation), the other monomer partitioning. Batch dispersion polymerizations of hydroxypropyl methacrylate in the presence of poly(glycerol methacrylate) macromonomers in water showed limited control of chain-growth. Semicontinuous experiments whereby monomer was fed improved results only to some extent. Control of propagation is essential for PISA to allow for dynamic rearrangement of colloidal structures. We tackled the problem of monomer partitioning (caused by uncontrolled particle nucleation) by starting the polymerization with an amphiphilic thermoresponsive diblock copolymer, already “phase-separated” from solution. TEM analysis showed that PISA was successful and that different particle morphologies were obtained throughout the polymerization

The management of water resources between traditions and sustainability: the qanats of Shahrood Province (North-eastern Iran)

Qanats, Iran, multidisciplinary study, water supply

Groundwater flow and geochemical modeling of the Acque Albule thermal basin (Central Italy): a conceptual model for evaluating influences of human exploitation on flowpath and thermal resource availability

Although the Acque Albule Basin has been studied since the middle of the 19th century, a comprehensive geologic conceptual model of the area has not yet been developed. The natural setting has been heavily modified by anthropic activities. Rapid evolution during the last 25 years has caused many interferences, which have led to a drastic increase of the hazards and linked risks, mainly related to water resource overexploitation and subsidence. The implementation of an exhaustive framework has become mandatory for environmental and management purposes. Starting from a critical review of previous studies, hydrogeologic and hydrogeochemical surveys and related numerical modeling have been carried out in order to achieve a quantitative understanding of the active phenomena and processes. Several hydrogeologic issues have been addressed concerning aquifer recharge areas and the different flowpaths of groundwater in respect to their division into a shallow and a deep circuit. Account has been taken of the groundwater chemistry as a function of water—rock interactions and mixing processes with uprising fluids. Different scenarios of groundwater flow in the Acque Albule aquifer have been built, using previously available piezometric measurements and the hydrodynamic parameters determined by in situ tests. These results led to the formulation of an updated hydrogeologic conceptual model to be further implemented, in which past, present and future anthropic instances and the potential of natural resources of the area have been included and taken into account. A sound conceptual model must rely on the design and development of a logical geo-database in which information is stored, updated and processed. This operational framework can result in a useful tool for land management, surveys planning and design, hazard and risk evaluation, identification of best practices and economic development of the area

The KINDRA project. Sharing and evaluating groundwater research and knowledge in Europe

Groundwater knowledge and research in the European Union is often scattered and non-standardised, because of different subjects involved and different approaches from Member States. The Horizon2020 project KINDRA has conducted an EU-wide assessment of existing groundwater-related practical and scientific knowledge based on a new Hydrogeological Research Classification System, identifying more than 280 keywords related to three main categories (namely Operational Actions, Research topics and Societal Challenges) to be intersected in a 3D-diagram approach. The classification is supported by a web-service, the European Inventory of Groundwater Research, which acts not only as knowledge repository but also as a tool to help identify relevant researchm topics, existing research trends and critical research challenges. The records have been uploaded during the project by 20 national experts from National Associations of Geologists, under the umbrella of the European Federation of Geologists. The total number of metadata included in the inventory at the end of the project are about 2300, and the analysis of the results is considered useful for producing synergies, implementing policies and optimising water management in Europe. By the use of additional indicators, the database content has been analysed by occurrence of keywords, type of document, level of innovation. Using the three-axes classification, more easily understandable by 2D diagrams as bubble plots, occurrence and relationship of different topics (main categories) in groundwater research have been highlighted. This article summarizes the activities realized in relation to the common classification system and to the metadata included in the EIGR, showing the distribution of thecollected information in different categories and attributes identified by the classification

Stability and pKa Modulation of Aminophenoxazinones and Their Disulfide Mimics by Host-Guest Interaction with Cucurbit[7]uril. Direct Applications in Agrochemical Wheat Models

Aqueous solubility and stability often limit the application of aminophenoxazinones and their sulfur mimics as promising agrochemicals in a sustainable agriculture inspired by allelopathy. This paper presents a solution to the problem using host-guest complexation with cucurbiturils (CBn). Computational studies show that CB7 is the most suitably sized homologue due to its strong affinity for guest molecules and its high water solubility. Complex formation has been studied by direct titrations monitored using UV-vis spectroscopy, finding a preferential interaction with protonated aminophenoxazinone species with high binding affinities (CB7 center dot APOH+ , Ka = (1.85 +/- 0.37) x 106 M-1; CB7 center dot DiS-NH3+ , Ka = (3.91 +/- 0.53) x 104 M-1; and DiS-(NH3+)2 , Ka= (1.27 +/- 0.42) x 105M-1). NMR characterization and stability analysis were also performed and revealed an interesting pKa modulation and stabilization by cucurbiturils (2-amino-3H-phenoxazin-3-one (APO), pKa = 2.94 +/- 0.30, and CB7 center dot APO, pKa = 4.12 +/- 0.15; 2,2 '-disulfanediyldianiline (DiS-NH2), pKa = 2.14 +/- 0.09, and CB7 center dot DiS-NH2 , pKa = 3.26 +/- 0.09), thus favoring applications in different kinds of crop soils. Kinetic studies have demonstrated the stability of the CB7 center dot APO complex at different pH media for more than 90 min. An in vitro bioassay with etiolated wheat coleoptiles showed that the bioactivity of APO and DiS-NH2 is enhanced upon complexation