Efeitos de tratamentos pré-germinativos e germinativos em sementes de Liquidambar styraciflua l. coletadas em Quedas do Iguaçu, PR.

Resumo

High-throughput synthesis of CeO₂ nanoparticles for transparent nanocomposites repelling Pseudomonas aeruginosa biofilms

Preventing bacteria from adhering to material surfaces is an important technical problem and a major cause of infection. One of nature’s defense strategies against bacterial colonization is based on the biohalogenation of signal substances that interfere with bacterial communication. Biohalogenation is catalyzed by haloperoxidases, a class of metal-dependent enzymes whose activity can be mimicked by ceria nanoparticles. Transparent CeO(2)/polycarbonate surfaces that prevent adhesion, proliferation, and spread of Pseudomonas aeruginosa PA14 were manufactured. Large amounts of monodisperse CeO(2) nanoparticles were synthesized in segmented flow using a high-throughput microfluidic benchtop system using water/benzyl alcohol mixtures and oleylamine as capping agent. This reduced the reaction time for nanoceria by more than one order of magnitude compared to conventional batch methods. Ceria nanoparticles prepared by segmented flow showed high catalytic activity in halogenation reactions, which makes them highly efficient functional mimics of haloperoxidase enzymes. Haloperoxidases are used in nature by macroalgae to prevent formation of biofilms via halogenation of signaling compounds that interfere with bacterial cell–cell communication (“quorum sensing”). CeO(2)/polycarbonate nanocomposites were prepared by dip-coating plasma-treated polycarbonate panels in CeO(2) dispersions. These showed a reduction in bacterial biofilm formation of up to 85% using P. aeruginosa PA14 as model organism. Besides biofilm formation, also the production of the virulence factor pyocyanin in is under control of the entire quorum sensing systems P. aeruginosa. CeO(2)/PC showed a decrease of up to 55% in pyocyanin production, whereas no effect on bacterial growth in liquid culture was observed. This indicates that CeO(2) nanoparticles affect quorum sensing and inhibit biofilm formation in a non-biocidal manner

Towards Biological Supramolecular Chemistry: A Variety of Pocket-Templated Metal Oxide Cluster Nucleations in the Cavity of a Mo/W-Storage Protein

Create and protect: The cavity shell of a molybdenum/tungsten‐storage protein acts as a polytopic host for several types of polyoxotungstate guests, which occur as individual clusters (one shown: yellow W, red O, ribbons protein) that are noncovalently or weakly bonded to the host. The formation of the guests is templated by the specific functionalities of the protein pockets

Druckentlastung in Systemen mit hoeherviskosen Fluessigkeiten Abschlussbericht

The purpose of the research project was to study pressure relief at the dome sid e of vessels in gas releasing and evaporating systems in the upper viscosity range. The viscosity of a liquid exerts an influence on fluid dynamics in the vessel and pressure relief system. Despite the pervasive use of high-range viscous liquids in chemical processes this parameter has hardly been examined until now. The results of the research project are expected to facilitate the design of reliable pressure relief systems for high-range viscous systems. (orig./HS)Ziel des durchgefuehrten Forschungsvorhabens ist die Untersuchung der behaelterdomseitigen Druckentlastung gasentloesender und siedender Systeme mit hoeherviskoser Fluessigkeitsphase. Die Fluessigkeitsviskositaet wirkt sich auf die Fluiddynamik im Behaelter und im Entlastungssytem aus. Obwohl in vielen chemischen Prozessen mit hoeherviskosen Fluessigkeiten umgegangen wird, ist der Einfluss dieses Parameters bislang kaum untersucht worden. Die Ergebnisse dieses Forschungsvorhabens sollen dazu dienen, Entlastungssysteme fuer Systeme mit hoeherviskosen Fluessigkeiten zuverlaessiger auslegen zu koennen. (orig./HS)Available from TIB Hannover: F93B1422+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Toward high-throughput chip calorimetry by use of segmented-flow technology

•Chip calorimeters with sample transport in segmented flow.•Analysis of the signal dynamics under segmented-flow conditions.•Suppression of biofouling in the flow channel.•Heat production of spheroids.•Heat production of human hair follicles. The adaptation of segmented-flow technology to flow-through calorimetry was demonstrated by different kinds of newly designed chip calorimeters useful for liquids and suspensions as well as for solid samples. In segmented-flow technology, sample material is suspended in aqueous segments of nano- or microliter volume and transported by a water-immiscible carrier liquid. The analysis of the signal dynamics given by segmented samples in flow led to optimal settings of flow rate and sample volume for maximal throughput. For 12μL sample segments, a cycle time of 4min could be achieved. The protection of the measuring chamber of the calorimeters against biofouling caused by the water-immiscible carrier liquid was verified for segmented bacterial samples. The unique possibility to measure solid and aggregated samples in flow-through was demonstrated by the investigation of human hair follicles and fibroblast spheroids