Rapidly self-deoxygenating controlled radical polymerization in water via in situ disproportionation of Cu(i)

Rapidly self-deoxygenating Cu-RDRP in aqueous media is investigated. The disproportionation of Cu(I)/Me6Tren in water towards Cu(II) and highly reactive Cu(0) leads to O2-free reaction environments within the first seconds of the reaction, even when the reaction takes place in the open-air. By leveraging this significantly fast O2-reducing activity of the disproportionation reaction, a range of well-defined water-soluble polymers with narrow dispersity are attained in a few minutes or less. This methodology provides the ability to prepare block copolymers via sequential monomer addition with little evidence for chain termination over the lifetime of the polymerization and allows for the synthesis of star-shaped polymers with the use of multi-functional initiators. The mechanism of self-deoxygenation is elucidated with the use of various characterization tools, and the species that participate in the rapid oxygen consumption is identified and discussed in detail

Copper mediated reversible deactivation radical polymerization in aqueous media

Key advances within the past 10 years have transformed copper mediated radical polymerization from a technique which was not very tolerant to protic media into a range of closely related processes capable of control over the polymerization of a wide range of monomers in pure water at ppm catalyst loadings; yielding water soluble macromolecules of desired molecular weight, architecture and chemical functionality, with applications ranging from drug delivery to oil field recovery. In this review we highlight and critically evaluate the synthetic methods that have been developed to control radical polymerization in water using copper complexes, identify future areas of interest and challenges still to be overcome

Polymerisable surfactants for polymethacrylates using catalytic chain transfer polymerisation (CCTP) combined with sulfur free-RAFT in emulsion polymerisation

Statistical copolymers of methacrylic acid and methyl methacrylate were synthesised via free radical catalytic chain transfer polymerisation (CCTP) in emulsion to form a hydrophilic emulsifier/surfactant. The vinyl-terminated oligomers were in turn utilised as chain transfer agents, with no further purification, for the formation of diblock copolymers with butyl and methyl methacrylate which constitutes the emulsifier via sulfur-free reversible addition–fragmentation chain transfer polymerisation (SF-RAFT). In turn these polymers were solubilized with various concentrations of ammonium hydroxide and utilised in the surfactant-free emulsion polymerization of butyl methacrylate using persulfate initiators, which also stabilized the polymer particles with observed no coagulation, with solid contents as high as 40%

Copper mediated polymerization without external deoxygenation or oxygen scavengers

Overcoming the challenge of rigorous deoxygenation in copper mediated controlled radical polymerization processes (e.g. ATRP), we report a simple Cu(0)‐RDRP system in the absence of external additives (e.g. reducing agents, enzymes etc.). By simply adjusting the headspace of the reaction vessel, a wide range of monomers, namely acrylates, methacrylates, acrylamides and styrene, can be polymerized in a controlled manner yielding polymers with low dispersities, near‐quantitative conversions and high end group fidelity. Significantly, this approach is scalable (~ 125 g), tolerant to elevated temperatures, compatible with both organic and aqueous media and does not rely on external stimuli which may limit the monomer pool. The robustness and versatility of this methodology is further demonstrated by the applicability to a number of other copper mediated techniques including conventional ATRP and light‐mediated approaches

Ultra-low volume oxygen tolerant photoinduced Cu-RDRP

We introduce the first oxygen tolerant ultra-low volume (as low as 5 μL total reaction volume) photoinduced copper-RDRP of a wide range of hydrophobic, hydrophilic and semi-fluorinated monomers including lauryl and hexyl acrylate, poly(ethylene glycol methyl ether acrylate) and trifluoroethyl (meth)acrylate. In the absence of any external deoxygenation, well-defined homopolymers can be obtained with low dispersity values, high end-group fidelity and near-quantitative conversions. Block copolymers can be efficiently synthesized in a facile manner and the compatibility of the system to larger scale polymerizations (up to 0.5 L) is also demonstrated by judiciously optimizing the reaction conditions. Importantly, the online monitoring of oxygen consumption was also conducted through an oxygen probe and the role of each component is identified and discussed

DataCell: Exploiting the Power of Relational Databases for Efficient Stream Processing

Designed for complex event processing, DataCell is a research prototype database system in the area of sensor stream systems. Under development at CWI, it belongs to the MonetDB database system family. CWI researchers innovatively built a stream engine directly on top of a database kernel, thus exploiting and merging technologies from the stream world and the rich area of database literature. The results are very promising

Exploiting the power of relational databases for efficient stream processing

textabstractStream applications gained significant popularity over the last years that lead to the development of specialized stream engines. These systems are designed from scratch with a different philosophy than nowadays database engines in order to cope with the stream applications requirements. However, this means that they lack the power and sophisticated techniques of a full fledged database system that exploits techniques and algorithms accumulated over many years of database research. In this paper, we take the opposite route and design a stream engine directly on top of a database kernel. Incoming tuples are directly stored upon arrival in a new kind of system tables, called baskets. A continuous query can then be evaluated over its relevant baskets as a typical one-time query exploiting the power of the relational engine. Once a tuple has been seen by all relevant queries/operators, it is dropped from its basket. A basket can be the input to a single or multiple similar query plans. Furthermore, a query plan can be split into multiple parts each one with its own input/output baskets allowing for flexible load sharing query scheduling. Contrary to traditional stream engines, that process one tuple at a time, this model allows batch processing of tuples, e.g., query a basket only after $x$ tuples arrive or after a time threshold has passed. Furthermore, we are not restricted to process tuples in the order they arrive. Instead, we can selectively pick tuples from a basket based on the query requirements exploiting a novel query component, the basket expressions. We investigate the opportunities and challenges that arise with such a direction and we show that it carries significant advantages. We propose a complete architecture, the DataCell, which we implemented on top of an open-source column-oriented DBMS. A detailed analysis and experimental evaluation of the core algorithms using both micro benchmarks and the standard Linear Road benchmark demonstrate the potential of this new approach

Oxygen tolerant copper-mediated reversible deactivation radical polymerization

The focus of this Ph.D. thesis is to develop Cu-RDRP and render it a more user-friendly and versatile platform. For this purpose, three different Cu-RDRP methodologies, Cu(0)-wire mediated RDRP (Chapter 2), photoinduced Cu-RDRP (Chapter 3) and aqueous Cu-RDRP with the pre-disproportionation of Cu(I) (Chapter 4), are studied in the absence of conventional deoxygenation. Without the use of extrinsic oxygen scavengers and reducing agents, a range of well-defined polymers (i.e. poly(acrylates), poly(methacrylates), poly(styrene) and poly(acrylamides)) are synthesized under various conditions (temperatures, solvents, reaction scale). In all the different oxygen tolerant approaches, high end-group fidelity is maintained, leading to well-defined block copolymers in-situ. In each of the three different approaches, the concentration of oxygen in the polymerization reactions is monitored in-situ with the use of an oxygen probe, and the mechanism of oxygen consumption is investigated and discussed. Furthermore, the role of the polymerization reagents on the evolution of oxygen consumption is elucidated, highlighting the importance of each component. Apart from the oxygen tolerant nature of these platforms, the effect of UV-irradiation on Cu-based complexes is investigated (Chapter 5), providing insights into the excited state dynamics and the photo-redox behaviour of Cu(II)-based complexes, and the effect of different aliphatic amines on photoinduced Cu-RDRP

Evaluating Conjunctive Triple Pattern Queries over Large Structured Overlay Networks

We study the problem of evaluating conjunctive queries com- posed of triple patterns over RDF data stored in distributed hash tables. Our goal is to develop algorithms that scale to large amounts of RDF data, distribute the query processing load evenly and incur little network traffic. We present and evaluate two novel query processing algorithms with these possibly conflicting goals in mind. We discuss the various tradeoffs that occur in our setting through a detailed experimental eval- uation of the proposed algorithms

Φαρμακευτική θεραπεία της παχυσαρκίας

Η κλιμάκωση του επιπολασμού της παχυσαρκίας σε διαστάσεις πανδημίας και οι συνοσηρότητές της, οδηγούν σε ανεκπλήρωτες ιατρικές ανάγκες για ασφαλή και αποτελεσματικά φάρμακα για την θεραπεία της. Πάνω από έναν αιώνα χρονολογούνται οι πρώτες επιστημονικές προσπάθειες για δημιουργία σκευασμάτων, προς αντιμετώπισή της. Ακολουθεί πλήθος βραχυπρόθεσμων θεραπειών με παρενέργειες που επισκιάζουν την αποτεσματικότητά τους (aminorex,fenfluramine). Φτάνοντας στο πρόσφατο παρελθόν, δύο σκευάσματα,η sibutramine και το rimonabant, μετά από ολιγοετή πορεία, αποσύρθηκαν λόγω μη επιβεβαιωμένης ασφάλειας, για να δώσουν την σκυτάλη στην ασφαλή ορλιστάτη, την μόνη με μακρόχρονη εμπειρία. Θα ακολουθήσουν νεότερα φάρμακα (λορκασερίνη, φεντερμίνη/ τοπιραμάτη, ναλτρεξόνη/βουπροπιόνη, λιραγλουτίδη), που θα στοχεύουν σε διακριτούς πληθυσμούς νευρώνων στον υποθάλαμο και στο στέλεχος. Πλήθος σεροτονινεργικών, ντοπαμινεργικών, ενδοκανναβινοειδών και οπιοειδών υποδοχέων, προσφέρουν νέους στόχους για την ρύθμιση της τροφικής συμπεριφοράς. Συνδυασμοί φαρμάκων, έχουν να καταδείξουν ανώτερη αποτελεσματικότητα και ασφάλεια, σε σύγκριση με έναν μόνο παράγοντα, στοχεύοντας σε διαφορετικά νευροχημικά μονοπάτια. Αξιοσημείωτο είναι ότι, αποσαφηνίζεται ο ρόλος των ορμονών του γαστρεντερικού (GLP1,GIP,PYY,σεκρετίνη, οξυντομοντουλίνη και λοιπών), στη ρύθμιση της πρόσληψης τροφής, ανοίγοντας ένα καινούργιο, πολλά υποσχόμενο κεφάλαιο στη θεραπεία κατά της παχυσαρκίας. Το μέλλον της φαρμακευτικής θεραπείας της παχυσαρκίας, προμηνύεται πλούσιο και ενδιαφέρον. Η πυρετώδης έρευνα για την σύγχρονη αυτή πανδημία, δοκιμάζει μια ποικιλία νέων σκευασμάτων. Ίσως το κλειδί για έναν αποτελεσματικό, και ασφαλή παράγοντα, ν’απαιτεί πολυεπίπεδη αντιμετώπιση, έναν συνδυασμό δηλαδή νευροορμονικών, λιπολυτικών και θερμογενετικών παραγόντων, που θα στοχεύει στην ταυτόχρονη πρόκληση του κορεσμού, καταστολή της πείνας, αύξηση της λιπόλυσης, της θερμογένεσης και των ενεργειακών δαπανών.The escalation of the prevalence of obesity to pandemic proportions and its comorbidities, lead to unmet medical needs for safe and effective drugs to treat it. The first scientific attempts to create preparations to deal with it, date back more than a century. This is followed by number of short-term treatments, with side effects overshadowing their effectiveness (aminorex,fenfluramine). Reaching the recent past, two formulations, sibutramine and rimonabant, after a short period of time, were withdrawn due to unconfirmed safety, to give the baton to the safe orlistat, the only one with long experience. Newer drugs will follow (lorcaserin, fentermine/topiramate, naltrexone / bupropion, liraglutide), which will target distinct populations of neurons in the hypothalamus and brainstem. A number of serotonergic, dopaminergic, endocannabinoid and opioid receptors offer new targets in the regulation of eating behavior. Combinations of drugs have demonstrated superior efficacy and safety, compared to a single agent, targeting different neurochemical pathways. It is noteworthy, that the role of gastrointestinal hormones (GLP1, GIP, PYY, secretin, oxyntomodulin, e.t.c.), in regulating food intake is clarified, opening a new, promising chapter in the treatment of obesity. The future of drug treatment of obesity is predicted rich and interesting. Feverish research on this modern pandemic, is testing a variety of new formulations. Perhaps the key to an effective and safe agent requires a multilevel treatment, a combination of neurohormonal, lipolytic and thermogenetic agents, aimed at simultaneously inducing satiety, suppressing hunger, increasing lipolysis, thermogenesis and energy costs.