High-Resolution ESR Imaging of N@C60 Radicals on a Surface

Electron Spin Resonance Microcopy (ESRM) is an imaging method capable of observing stable free radicals in small samples with a spatial resolution of ∼1 micron. Currently this technique is pursued mainly for biological applications at room temperature and at relatively low static magnetic fields. Future progress, which involves the use of higher magnetic fields at cryogenic temperatures, could significantly improve sensitivity and resolution and thus make this method attractive to many solid-state and physical science applications. Here we consider a possible application of ESRM to the field of quantum computing employing Endohedral Nitrogen fullerene (N@C₆₀) molecules. In order to fully address the challenges of quantum computing, the resolution should be significantly improved to ∼10 nm and the sensitivity should approach the single spin level. In the present work we show some preliminary results conducted with diluted N@C₆₀ samples. A 2D image of N@C₆₀ dispersed on a surface was obtained at a field of ∼0.6 T and at room temperature. Under these conditions the current sensitivity of the ESRM system is around 10 ⁷ −10 ⁸ spins, and due to the low enrichment factor of the N@C₆₀ sample (∼10⁻⁶), we were able to reach image resolution of only ∼50 m̈m. Future steps that are taken in order to significantly improve resolution and sensitivity of the system are discussed. These include the use of highly concentrated samples to be measured at ∼4 K and at a field of more than 1 T, which would lead to a resolution of ∼100 nm and a sensitivity of ∼100 spins.     

Impedance Measurements as a Simple Tool to Control the Quality of Conjugated Polymers Designed for Photovoltaic Applications

The problem of batch‐to‐batch variation of electronic properties and purity of conjugated polymers used as electron donor and photon harvesting materials in organic solar cells is addressed. A simple method is developed for rapid analysis of electronic quality of polymer‐based materials. It is shown that appearance of impurities capable of charge trapping changes electrophysical properties of conjugated polymers. In particular, a clear correlation between the effective relaxation time τeff and relative photovoltaic performance (η/η_max) is revealed for samples of poly(3‐hexylthiophene) intentionally polluted with a palladium catalyst. This dependence is also valid for all other investigated samples of conjugated polymers. Therefore, fast impedance measurements at three different frequencies allow one to draw conclusions about the purity of the analyzed polymer sample and even estimate its photovoltaic performance. The developed method might find extensive applications as a simple tool for product quality control in the laboratory and industrial‐scale production of conjugated polymers for electronic applications.     

Decay of Bacteroidales genetic markers in relation to traditional fecal indicators for water quality modeling of drinking water sources

The implementation of microbial fecal source tracking (MST) methods in drinking water management is limited by the lack of knowledge on the transport and decay of host-specific genetic markers in water sources. To address these limitations, the decay and transport of human (BacH) and ruminant (BacR) fecal Bacteroidales 16S rRNA genetic markers in a drinking water source (Lake R?dasj?n in Sweden) were simulated using a microbiological model coupled to a three-dimensional hydrodynamic model. The microbiological model was calibrated using data from outdoor microcosm trials performed in March, August, and November 2010 to determine the decay of BacH and BacR markers in relation to traditional fecal indicators. The microcosm trials indicated that the persistence of BacH and BacR in the microcosms was not significantly different from the persistence of traditional fecal indicators. The modeling of BacH and BacR transport within the lake illustrated that the highest levels of genetic markers at the raw water intakes were associated with human fecal sources (on-site sewers and emergency sewer overflow). This novel modeling approach improves the interpretation of MST data, especially when fecal pollution from the same host group is released into the water source from different sites in the catchment.     

Comparison of Polyunsaturated Fatty Acids Content in Filets of Anadromous and Landlocked Sockeye Salmon Oncorhynchus Nerka

Abstract: Fatty acid composition and content of 2 forms of sockeye salmon Oncorhynchus nerka from lakes in Kamchatka Peninsula (Russia) were compared. One form of sockeye salmon was anadromous (“marine”), that is, adult fish migrated in ocean to feed and grow and than return in the lake to breed. Fish of another form, kokanee, never migrate in the ocean. Per cent levels of the main indicators of nutritive value, eicosapentaenoic acid (EPA, 20:5n‐3), and docosahexaenoic acid (DHA, 22:6n‐3), were significantly higher in the landlocked O. nerka. However, concentrations of EPA and DHA per wet weight of filets were higher in the marine form, because of the relatively higher content of sum of fatty acids in their muscle tissue. As concluded, fish fed in marine environment had higher contents of long‐chain n‐3 fatty acids per wet weight than fish of the same species, fed in fresh waters. In general, both the anadromous sockeye salmon and the landlocked kokanee salmon can be recommended for human diet as a valuable product concerning contents of EPA and DHA. Practical Application: The long‐chain polyunsaturated acids (PUFA) have been specifically recommended for humans to prevent cardiovascular disease and psychiatric disorders. Fish are known to be the main source of PUFA in human diet. Data on PUFA content in diverse food fish is essential to compare the benefits they offer for consumers’ health. We compared PUFA contents in 2 forms of popular food fish Oncorhynchus nerka, migrating sockeye salmon and landlocked kokanee salmon, and found that both forms are valuable product concerning PUFA content.     

Loss of swiss cheese in Neurons Contributes to Neurodegeneration with Mitochondria Abnormalities,Reactive Oxygen Species Acceleration and Accumulation of Lipid Droplets in Drosophila Brain

Various neurodegenerative disorders are associated with human NTE/PNPLA6 dysfunction. Mechanisms of neuropathogenesis in these diseases are far from clearly elucidated. Hereditary spastic paraplegia belongs to a type of neurodegeneration associated with NTE/PNLPLA6 and is implicated in neuron death. In this study, we used Drosophila melanogaster to investigate the consequences of neuronal knockdown of swiss cheese (sws)—the evolutionarily conserved ortholog of human NTE/PNPLA6—in vivo. Adult flies with the knockdown show longevity decline, locomotor and memory deficits, severe neurodegeneration progression in the brain, reactive oxygen species level acceleration, mitochondria abnormalities and lipid droplet accumulation. Our results suggest that SWS/NTE/PNPLA6 dysfunction in neurons induces oxidative stress and lipid metabolism alterations, involving mitochondria dynamics and lipid droplet turnover in neurodegeneration pathogenesis. We propose that there is a complex mechanism in neurological diseases such as hereditary spastic paraplegia, which includes a stress reaction, engaging mitochondria, lipid droplets and endoplasmic reticulum interplay.     

Surface‐Modified Mesoporous SiO2 Containers for Corrosion Protection

The development of active corrosion protection systems for metallic substrates is an issue of prime importance for many industrial applications. The present work shows a new contribution to the design of a new protective system based on surface modified mesoporous silica containers. Incorporation of silica‐based containers into special sol–gel matrix allows for a self‐healing effect to be achieved during the corrosion process. The self‐healing ability occurs due to release of entrapped corrosion inhibitors in response to pH changes caused by the corrosion process. A silica–zirconia‐based hybrid film is used in this work as a coating matrix deposited on AA2024 aluminum alloy. Mesoporous silica nano‐particles are covered layer‐by‐layer with polyelectrolyte layers and loaded with inhibitor [2‐(benzothiazol‐2‐ylsulfanyl)‐succinic acid]. The hybrid film with nanocontainers reveals enhanced long‐term corrosion protection in comparison with the individual sol–gel films. The scanning vibrating electrode technique also shows an effective healing ability of containers to cure the corrosion defects. This effect is due to the release of the corrosion inhibitor triggered by the corrosion processes started in the cavities. The approach described herein can be used in many applications where active corrosion protection of materials is required.     

Mechanical properties of Bombyx mori silk yarns studied with tensile testing method

The mechanical properties of Bombyx mori silk yarns and baves were investigated with tensile testing method. After silk yarns were pre‐extended at different strain levels and fixed for a while followed by recovery process, the tensile characteristics were examined in detail. It was commonly observed that low preliminary extensions up to 2–3% do not cause the changes of the mechanical properties and stress‐strain curves because they result in small structural changes and distortions, which were recovered within relatively short time (～ 1 min) in recovery process. However, pre‐extension values >3% strain lead to great changes of the mechanical properties and fibre structure, i.e., the changes of the shape of stress‐strain curve where additional transition point was observed, increase in the rigidity and stress at rupture, but decrease in extensibility as a result of orientation and destruction of the fibre structure especially in the amorphous region. It was stated that silk fibre consists of two distinct deformation regions, namely first linear region extending up to 2–3% strain and the second region beyond 2–3% strain where the main reorganization processes of the fibre structure, that is, the straining of macromolecular chains especially in the amorphous regions, the orientation of structural units such as β‐sheet microcrystals in stretching direction, and the destruction of macromolecules take place. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009