Synthesis and antibacterial effects of cobalt–cellulose magnetic nanocomposites

© The Royal Society of Chemistry. Green synthesis is employed to prepare cobalt/cellulose nanocomposites with cubic (α-cobalt) cobalt as a main component with antibacterial and magnetic properties. An in situ reduction of aqueous solutions of cobalt ions on a model cellulose substrate surface using hydrogen gas affords spherical, cellulose-stabilised cobalt nanoclusters with magnetic properties and an average diameter of 7 nm that are distributed evenly over the surface of the cellulose fibres. These cobalt/cellulose nanocomposites exhibit good antibacterial action against opportunistic pathogens both Gram-positive (S. aureus) and Gram-negative (E. coli, A. baumannii and P. aeruginosa), with zones of inhibition up to 15 mm, thereby encouraging the deployment of these advanced materials for the treatment of wastewater or within medical dressings. This method of preparation is compared with the analogous in situ reduction of cobalt ions on a cellulose surface using sodium borohydride as reducing agent

Theoretische Erfassung sozialer Bewegungen im Bekleidungssektor

Kleider machen Leute – nur zu welchen Konditionen? Mode und Markenfetischismus zahlen im Sinne der Verwertbarkeitslogik als äußere Vermarktung gesellschaftlicher Subjekt, zur eigenen Identitätskonstruktion. Ein Mix aus Medien und Marketing forciert den schnelllebigen Konsum der Überfluss- bzw. Wegwerfgesellschaft. SALE zu spottbilligen Preisen die ganze Saison! Die Kehrseite der Medaille, die unzählige ArbeiterInnen der Bekleidungsindustrie – vor allem junge Frauen aus so genannten Billiglohnländern – betrifft ist nur teilweise bekannt oder wird ignoriert: Arbeitsschichten zu einem Hungerlohn weniger Euros pro Tag, menschenunwürdige Arbeitsbedingungen in Sweatshops und mangelnde Sozialsysteme. Die komplexe und intransparenten Wertschöpfungskette gilt als Pionier internationalisierter Produktionsverhältnisse und neuer internationaler Arbeitsteilung. Seit Mitte der 1990er skandalisieren soziale Bewegungen – wie die Clean Clothes Kampagne – die gravierenden Arbeitsrechtsverletzungen in Produktionsbetrieben transnationaler Konzerne. Es wird versucht gegen diese Zustande anzukämpfen. Mit welchem Erfolg und wie ist dieses Engagement theoretisch zu erfassen? Letzteres bildet den Fokus des vorliegenden Forschungsinteresses. Auf eine kritische transdisziplinäre Analyse wird größter Wert gelegt, um Erkenntnisse zu erkunden die als zukünftiger Ausgangspunkt, kritischer Auseinandersetzungen mit sozialen Bewegungen dienen sollen. Methodisch basiert die Diplomarbeit auf sekundärer Literaturrecherche und ExpertInnen-Interviews.Clothes make the man – but under which conditions? Fashion and brand fetishism represents an essential tool of lifestyle industries mentality considering people’s own construction of identity in the 21st century. The fast pace of present consume patterns of so called throwaway society is enforced by a perfectly composed mix of media and marketing tools. SALE at dirt cheap prices anywhere and anytime! The flip side of the coin is either unknown or neglected on purpose affects numberless workers – especially young women – within the garment industry: Degrading working conditions mark the daily life in sweatshops. Overlong working shifts for a pittance of a few Euros per day and inadequate social security systems. Its complex and mostly intransparent value added chains represents a pioneer in internationalized relations of production and new international labor division. Transformations in the context of globalization challenge (non)governmental actors in regards to global production and its regulation. Since the mid 1990s social movements – e.g. Clean Clothes Campaign – are scandalizing serious violations of working rights within the production entities of multinational groups. What are the results and how is this commitment theoretically detected? To gather a vast insight into the topic the emphasis lies on a critical transdisciplinary analysis. The thesis is based on secondary literature research and experts-interviews

Analysis of vertical synchronous generator modal properties

Diplomová práce se zabývá analýzou modálních vlastností synchronního vertikálního generátoru. Cílem práce je určení vlivu jednotlivých částí generátoru na modální vlastnosti. Analyzována je kostra generátoru, rotor a celý generátor. Další část práce se zabývá analýzou různých variant uložení generátoru a také konstrukčních úprav, které vedou ke zlepšení modálních vlastností. Výpočtové modelování bylo provedeno v programu ANSYS.This Master´s thesis deals with the analysis of modal characteristics of the vertical synchronous generator. The goal of this work is to determine influence of individual parts of the generator on modal characteristics. Another part of this thesis contains analysis of different variants for storaging the generator and also structural modifications, which lead to the improvement of the modal properties. For modelation was used cumputional modeling in ANSYS.

Strip rolling

Tato práce řeší teoretický rozbor role plastické deformace u procesu zakružování pásů. Vysvětluje průběhy napětí při zatěžování a při odlehčování. Práce se dále zabývá výpočtem odpružení a ohybového momentu při určitém zakřivení pásů. Zpráva obsahuje ilustrativní příklad doplněný výpočtovým programem.This bachelor thesis focuses on theoretical analysis of the role of plastic deformation in the process of rolling strips. The work explains progress of stress waveform during straining and lightening. This work also focuses on computing of spring loading and bending moment due to specific curvature of strips. Report at the end of this work includes an illustrative example with executional program.

Whiter, brighter, and more stable cellulose paper coated with antibacterial carboxymethyl starch stabilized ZnO nanoparticles

Small, carboxymethyl-starch-stabilised zinc oxide nanoparticles with a defined shape, size and morphology were prepared in situ in water at relatively low reaction temperatures using soluble carboxymethyl starch (CMS) as a combined crystallising, stabilising and solubilising agent and triethanolamine as the reducing agent. Aqueous colloidal solutions of these CMS-stabilised ZnO nanoparticles were used to deposit a coating of ZnO nanoparticles on cellulose paper by a wet-chemistry, polyelectrolyte, layer-by-layer approach using water as the only solvent. Such cellulose paper samples, coated with these CMS-stabilised ZnO nanoparticles, show higher brightness and whiteness than that of blank reference paper and are more stable to UV-radiation than the paper reference as well as demonstrating good antibacterial activity against MRSA and A. baumannii

Molecular dynamics simulations of structural transformation of perfluorooctane sulfonate (PFOS) at water/rutile interfaces

Concentration and salinity conditions are the dominant environmental factors affecting the behavior of perfluorinated compounds (PFCs) on the surfaces of a variety of solid matrices (suspended particles, sediments, and natural minerals). However, the mechanism has not yet been examined at molecular scales. Here, the structural transformation of perfluorooctane sulfonate (PFOS) at water/rutile interfaces induced by changes of the concentration level of PFOS and salt condition was investigated using molecular dynamics (MD) simulations. At low and intermediate concentrations all PFOS molecules directly interacted with the rutile (110) surface mainly by the sulfonate headgroups through electrostatic attraction, yielding a typical monolayer structure. As the concentration of PFOS increased, the molecules aggregated in a complex multi-layered structure, where an irregular assembling configuration was adsorbed on the monolayer structure by the van der Waals interactions between the perfluoroalkyl chains. When adding CaCl2 to the system, the multi-layered structure changed to a monolayer again, indicating that the addition of CaCl2 enhanced the critical concentration value to yield PFOS multilayer assemblies. The divalent Ca2+ substituted for monovalent K+ as the bridging counterion in PFOS adsorption. MD simulation may trigger wide applications in study of perfluorinated compounds (PFCs) from atomic/molecular scale

Aqueous Solvation Dynamics at Metal Oxide Surfaces

Broadband transient absorption (TA) spectroscopy, three-pulse photon echo peak shift (3PEPS), and anisotropy decay measurements were used to study the solvation dynamics in bulk water and interfacial water at ZrO2 surfaces, using Eosin Y as a probe. The 3PEPS results show a multiexponential behavior with two subpicosecond components that are similar in bulk and interfacial water, while a third component of several picoseconds is significantly lengthened at the interface. The bandwidth correlation function from TA spectra exhibits the same behavior, and the TA spectra are well reproduced using the doorway-window picture with the time constants from PEPS. Our results suggest that interfacial water is restricted to a thickness of less than 5 angstrom. Also the high-frequency collective dynamics of water does not seem to be affected by the interface. On the other hand, the increase of the third component may point to a slowing down of diffusional motion at the interface, although other effects, may play a role, which are discussed