Special Issue: New Challenges in Thin-Film Nanocomposite Membranes

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Genetic Techniques and Circuit Analysis

Reaching an understanding of how neuronal circuits work and what they compute is a fundamental aim of neuroscience, perhaps even the most fundamental. We have to both establish the connections between cell types and reversibly manipulate their activity cell-typeselectively. Such work sounds in principle straight-forward, but it has been difficult to achieve. This has now all changed. There has been a quite remarkable development of genetic techniques published in the last years, so that the topic of “Genetic techniques and circuit analysis ” covered by the articles in this Special Issue is truly flourishing. The extremely easy applicability of the channelrhodopsin-2 system (ChR2) in diverse animals and circuit settings has been a phenomenal breakthrough and captured the imagination of the neuroscience community (see, for example, Adamantidis et al., 2009; Han et al., 2009). A major advantage of ChR2 is that precise patterns of activation can be delivered cell-type selectively

Thermally stable anion-exchange materials

Anion-exchange materials are of great interest in a broad field of applications like water treatment, catalysis or electrochemical devices like electro dialysis or fuel cells. The anion-exchange materials are widely based on (cross-linked) polystyrene functionalized with trimethyl ammonium groups fixed via a methylene bridge to the benzene ring. Nearly all anion-exchange materials have in common, that they are thermally unstable at elevated temperature and high pH. However, in electrochemical applications like fuel cells or in electro dialysis high temperatures are desired for competitive performances. In a recent study Marino and Kreuer1 investigated the thermal stability of quaternary ammonium model compounds. Among the various compounds those based on piperidine (Fig. 1) turned out to be most stable ones. Pham and Jannasch2 reported on polymeric anion-exchange materials based on poly(ether sulfone)s bearing N-spirocyclic quaternary ammonium groups similar to those reported by Marino and Kreuer. However, these polymers showed only a low thermal stability. Please click Additional Files below to see the full abstract

E-I Balance and Human Diseases – from Molecules to Networking

Information transfer in the brain requires a homeostatic control of neuronal excitability. Therefore, a functional balance between excitatory and inhibitory systems is established during development. This review contains recent information about the molecular mechanisms orchestrating the establishment and maintenance of this excitation-inhibition (E-I) balance, and it reviews examples of deregulation of inhibitory and excitatory systems at a molecular, network and disease level of investigation

Ultrafiltration membranes based on PES-PEG block copolymers

Although subject to research for decades, fouling is still one of the major limiting factors in membrane applications. Numerous methods have been suggested to overcome this shortcoming, like crossflow filtration, backflushing, air sparging, all of them in combination with chemical cleaning. However many of these techniques imply off-production cycles, resulting in lower yield, shorter lifetime of membranes and therefore higher costs. Another approach to reduce fouling involves the modification of membranes with charged and / or hydrophilic polymers. These are either added to the casting solution or subsequently grafted onto the membrane surface. However, both methods have their specific drawbacks. Adding hydrophilic polymers to the dope solution leads to a significant loss during membrane preparation step (coagulation). On the other hand graft modification involves most often several steps and bears the risk of damaging (degrading) the membrane material resulting in loss of mechanical stability. In this work we report on UF membranes prepared from poly(ether sulfone)-poly(ethylene glycol) block copolymers with poly(ethylene glycols) of molecular weights varying from 200 g/mol to 4000 g/mol but constant molar fraction of 5 mol%. Furthermore, block copolymers with increasing content of PEG-200 up to 20 mol% were prepared. This approach has the advantage over surface modification that the degree of functionalization can be easily controlled by the monomer composition. UF-membranes from block copolymers were prepared by conventional NIPS process using NMP as solvent and water as non-solvent. The effect co-monomer type (molecular weight of PEG) and co-monomer concentration on the morphology of the resulting membranes (Figure 1) as well as their filtration properties including protein fouling will be discussed in detail. Please click Additional Files below to see the full abstract

Surface Modification of Membranes for Fouling Reduction

Despite great effort that has been made to reduce and understand fouling, this phenomenon is still a major problem in membrane applications. Numerous methods, both from a chemical and engineering point of view, have been introduced to overcome this problem. In this contribution, we report on the modification of membranes with polyelectrolytes and polyelectrolyte multilayers utilizing two of the mentioned strategies. The effect of surface modification on the fouling behavior as well as on the critical flux will be discussed on two examples, microfiltration membranes and RO membranes

Entwicklung eines Anforderungsprofils für Kontrolleure im Rahmen des Kontrollsystems nach der EU-Verordnung 2092/91

Ziel der Studie ist es, das Anforderungsprofil für Kontrolleure auf der Grundlage der EU-Öko-Verordnung 2092/91 für die unterschiedlichen Kontrollbereiche zu ermitteln. Grundlage dafür bilden die Analyse der Tätigkeiten von Kontrolleuren aufgegliedert nach Branchen in die verschiedenen Kontrollbereiche Landwirtschaft, Verarbeitung und Import aus Drittländern. Ergänzend wurde erfasst, welche Anforderungen in anderen Kontroll- und Qualitätssicherungsnormen und -verordnungen an das Kontroll- bzw. Auditpersonal gestellt werden. Ableitend von diesen Analysen wurde das Anforderungsprofil für die drei Kontrollbereiche erstellt. Das Anforderungsprofil gliedert sich in vier Teile: die persönliche Qualifikation (in Anlehnung an ISO 10011), die Basisqualifikation (mündliche und schriftliche Kommunikation, Kalkulation, Berufserfahrung), die fachliche Qualifikation, die sich je nach Kontrollbereich unterscheidet sowie die Kenntnisse der gesetzlichen Regelungen. Für jeden Baustein im Anforderungsprofil wurde abgeleitet, mit welcher Berufsausbildung, Trainingsmaßnahme o.ä. diese Qualifikation erreicht und wie sie nachgewiesen werden kann. In diesem Zusammenhang wurde auch das in Deutschland übliche Zulassungsverfahren für Kontrollpersonal diskutiert. Die Verordnung (EWG) 2092/91 sowie der ergänzend geltenden EN 45011 enthält keine Vorgaben, welche die Zulassung von Kontrolleuren durch Aufsichtsbehörden vor dem Einsatz erforderlich machen. Es muss allerdings im Rahmen der Überwachung der Kontrollstellen überprüft werden, ob die Kontrollstellen über sachgerechte Personalkriterien, ein angemessenes dokumentiertes Verfahren für die Auswahl des Personals sowie individuelle Leistungsbeurteilungen verfügen und das Personal angemessen aus- und fortbilden. Eine Umfrage bei den Kontrollstellen im deutschsprachigen Raum erfasste die derzeitigen Aus- und Fortbildungsmaßnahmen für Kontrollpersonal. Auf Grundlage der Auswertung der Tätigkeitsanalysen und der Rückmeldungen der Kontrollstellen wurde festgestellt, dass Bedarf an einem kontrollstellenüber-greifenden Fortbildungsangebot besteht, das sich vor allem auf die Spezialbereiche im Kontrollsystem konzentriert (z.B. Umgang mit schwierigen Kontrollsituationen, Aktuelle Änderungen der VO 2092/91, Hofverarbeitung, Rückstandsanalytik und Probenahmeverfahren, Importkontrolle)

Mesoscale distribution patterns of diatoms in surface sediments as tracers of coastal upwelling of the Galician shelf (NW Iberian Peninsula)

Diatom distribution on continental shelf sediments from the upwelling area off Galicia (NW Iberian Peninsula) has been determined in 78 surface sediment samples. Three well defined biofacies with a close relationship to upwelling influence along the coast have been distinguished from both the absolute diatom abundances in the sediments and assemblage diatom composition based on multivariate statistics: Rias Baixas and the shelf areas south and north to Cape Finisterre. Chaetoceros resting spores as well as highest absolute diatom content in the sediments are recorded in the highly productive Rias Baixas where most of the primary production is due to intense upwelling phenomena. The western shelf, south of Cape Finisterre. is characterized by Thalassionema nitzschioides and Thalassiosira cf. leptopus. Both taxa reflect a minor influence of upwelling conditions and productivity related to more persistent nutrient input due to coastal outwelling rather than upwelling. Minor and patchy upwelling conditions as well as lower productivity in the northern shelf are characterized by the lowest absolute diatom content in the sediments and the important increase in relative abundance of the resistant Paralia sulcata. Caution must be taken in the interpretation of Paralia sulcata dominated biofacies in downcore studies since a juxtaposition of discontinuous upwelling conditions and dissolution effects may be the factors responsible for the relative increase on the taxon in the sediments. The obtained results show the extent and limitations of fossil diatom distribution in surface sediments as tracers of regional coastal upwelling conditions in continental shelves where the existence of extensive areas of relict sediments and transported diatoms may mask the present-day upwelling signal of the photic zone.This work was supported by the European Union in the framework of the MAST programme, contract no. MAS2-CT93-0069 (Ocean Margin Exchange, OMEX). It is also a contribution to projects XUGA10307B93 (Xunta de Guliciu) and APC-950010 (Direccibn General de Znvestigacibn Cien tljica y Ticnica)Peer reviewe