Local Flooding Phenomena in Channel and Land Areas Occurring during Dynamic Operation of a PEFC

In this work, we report on flooding phenomena occurring during dynamic operation of a polymer electrolyte fuel cell (PEFC). The combination of high spatially and temporally resolved neutron radiography and submillimeter resolved current density distribution measurements enables the simultaneous observation of local liquid water content and current density transients in the channel and land areas of a differentially operated PEFC air cathode. The local transients of a triangular voltage sweep and a voltage step are presented here. Both results demonstrate that in the land area the current density is only marginally affected by the local liquid water content. In the voltage sweep experiment, at higher cell polarization a limiting current density is observed in the land area as a result of mass transport limitations due to the high lateral diffusion path length. In the channel area the corresponding transients of the liquid water content and the current density both exhibit a hysteresis. The transients of the voltage step indicate liquid water rearrangement in channel and land areas as a slow process occurring on a time scale of several minutes. Thereby, the local cell performance is primarily affected by the local liquid water content in front of the oxygen electrode.     

Phenolic compounds and plant extracts as potential natural anti-obesity substances

One strategy to prevent obesity could consist in the inhibition of the pancreatic lipase (PL). In an attempt to find natural antiobesity agents, phenolic compounds (PCs) and plant extracts were investigated on PL activity. Epigallocatechin-3-gallate > kaempferol and quercetin were detected as potent PL inhibitors, with ICs₅₀ of 0.8, 13.4 and 21.5 μM, respectively. Plant extracts from green tea and grape seed also shown potent inhibitory effect. Selected PCs were then assayed in an in vitro model of simulated intestinal fat digestion, based on the lipolysis of triolein. In such conditions closer to physiological reality, resveratrol, but also epigallocatechin-3-gallate and quercetin reduced the triolein digestion to ±50%. This could delay or decrease in vivo fatty acid absorption by enterocytes. This work therefore suggests that some PCs, at concentrations easily reached in the intestine following ingestion of tea beverages, fruits or vegetables, but also flavonoid-enriched supplements or functional food, are potential candidates for obesity prevention.     

Polybrominated diphenyl ethers (PBDEs) alter larval settlement of marine intertidal organisms across three phyla via reducing bacterial abundance on the biofilms

Polybrominated diphenyl ethers (PBDEs) have been widely used as flame retardants over the last three decades, and are now ubiquitous in the marine environment. While the harmful effects of PBDEs on the abnormal development and reproductive impairment in mammals and fish are well documented, the effects on marine invertebrates remain virtually unknown. Using three model intertidal species accross three phyla, including the polychaete Hydroides elegans (Phylum Annelida), the gastropod Crepidula onyx (Phylum Mollusca), and the barnacle Balanus amphitrite (Phylum Arthopoda), this study demonstrated that (a) chronic exposure to BDE-47 (at spiking concentrations up to 1000 ng L(-1)) throughout the entire larval stage did not affect settlement, development or growth of all three species per se, despite bioaccumulation was clearly evident (measured body burden ranging from approximately 7000 to 13?000 ng BDE-47 g(-1) lipid), and (b) BDE-47, at measured concentrations of 15 and 113 ng g(-1) lipid, reduced the bacterial abundance in biofilms and resulted in a concomitant change in larval settlement pattern of all the model intertidal species across three phyla.     

New roles for community pharmacists in modern health care systems: a challenge for pharmacy education and research

The academic activities led by the Unit of Community Pharmacy can be classified as translational. Our group is interested in person-centered pharmaceutical services aimed at a more responsible use of drugs (effectiveness, safety, efficiency) in collaboration with physicians and other health care professionals in a primary care setting. The following domains of education and research are high priorities for our group: medication therapy management, medication adherence, integrated care, individualization of therapies, care management for the elderly and e-health.     

Rapid Combinatorial Synthesis and Chromatography Based Screening of Phosphorescent Iridium Complexes for Solution Processing

This work reports the combinatorial synthesis and screening of phosphorescent iridium complexes as solution processable emitters for OLEDs. The approach taken here allows for the rapid synthesis, isolation, spectroscopic characterization and identification of the libraries based on chromatographic methods. Subsequent analysis of the irradiation induced degradation provides insight on the stability of the complexes under continuous excitation. The method is versatile and can easily be applied to other metal complexes or organic dyes for various applications, e.g., in electroluminescence, photovoltaics and sensing.     

Task-switching performance with 1:1 and 2:1 cue–task mappings: Not so different after all.

When task-switching studies use the task-cuing procedure with a 1:1 cue–task mapping, task switching and cue switching are confounded, which is problematic for interpreting switch costs. The use of a 2:1 cue–task mapping is a potential solution to this problem, but it is possible that introducing more cues may also introduce marked changes in task-switching performance. In 5 experiments involving 160 subjects, the authors compared performance with 1:1 and 2:1 mappings across several methodological changes. Differences in switch costs between mappings were small and, in most analyses, nonsignificant. In all experiments, both mappings yielded significant reductions in switch cost across cue–target interval, and there were significant cue-switching effects with the 2:1 mapping. A model of cue encoding fit the data from both mappings about equally well. Overall, task-switching performance was more similar than it was different between mappings, leading the authors to suggest that the use of a 2:1 mapping is a viable solution to the problem associated with a 1:1 mapping. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Atomic-scale electron-beam sculpting of near-defect-free graphene nanostructures

In order to harvest the many promising properties of graphene in (electronic) applications, a technique is required to cut, shape, or sculpt the material on the nanoscale without inducing damage to its atomic structure, as this drastically influences the electronic properties of the nanostructure. Here, we reveal a temperature-dependent self-repair mechanism that allows near-damage-free atomic-scale sculpting of graphene using a focused electron beam. We demonstrate that by sculpting at temperatures above 600 °C, an intrinsic self-repair mechanism keeps the graphene in a single-crystalline state during cutting, even though the electron beam induces considerable damage. Self-repair is mediated by mobile carbon ad-atoms that constantly repair the defects caused by the electron beam. Our technique allows reproducible fabrication and simultaneous imaging of single-crystalline free-standing nanoribbons, nanotubes, nanopores, and single carbon chains.     

Disentangling the adult attention-deficit hyperactivity disorder endophenotype: Parametric measurement of attention.

Attention deficit hyperactivity disorder (ADHD) persists frequently into adulthood. The decomposition of endophenotypes by means of experimental neuro-cognitive assessment has the potential to improve diagnostic assessment, evaluation of treatment response, and disentanglement of genetic and environmental influences. We assessed four parameters of attentional capacity and selectivity derived from simple psychophysical tasks (verbal report of briefly presented letter displays) and based on a “theory of visual attention.” These parameters are mathematically independent, quantitative measures, and previous studies have shown that they are highly sensitive for subtle attention deficits. Potential reductions of attentional capacity, that is, of perceptual processing speed and working memory storage capacity, were assessed with a whole report paradigm. Furthermore, possible pathologies of attentional selectivity, that is, selection of task-relevant information and bias in the spatial distribution of attention, were measured with a partial report paradigm. A group of 30 unmedicated adult ADHD patients and a group of 30 demographically matched healthy controls were tested. ADHD patients showed significant reductions of working memory storage capacity of a moderate to large effect size. Perceptual processing speed, task-based, and spatial selection were unaffected. The results imply a working memory deficit as an important source of behavioral impairments. The theory of visual attention parameter working memory storage capacity might constitute a quantifiable and testable endophenotype of ADHD. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Application of instantaneous profile measurement of moisture content and moisture potential in porous materials

Due to limits in current moisture content and moisture potential measurement technology, moisture transport is normally investigated under equilibrium conditions. Most processes we observe in nature are, however, transient and hardly ever reach an equilibrium stage. This means that future experimental methods in moisture transport investigation will focus on transient processes. One such method is the instantaneous profile measurement (IPM) technique frequently used in soil science. It can be applied to investigate moisture transport under transient conditions. Two measurement principles are combined in one material to record data for moisture content and moisture potential at the same time and at various points. As output, moisture content and moisture potential profiles are plotted against space and time. The method was applied to different porous materials, and hygroscopic loading and deloading cycles were conducted in the relative humidity range between 30 and 97%. The data obtained is not in strict agreement with static or steady-state observations. This reveals information about moisture transport kinetics. These findings are discussed in the context of the literature and with regard to their significance for current moisture transport models, which are typically based on equilibrium data.