Creep Properties of 9Cr and 14Cr ODS Tubes Tested by Inner Gas Pressure

Oxide-dispersion strengthened steels are promising materials for extreme service conditions including nuclear reactors core. In service conditions, nuclear fuel claddings are exposed to the fission gas pressure at temperatures about 700 °C. This paper presents novel results on ODS creep properties from a round robin of inner gas pressure creep test. A gas pressure creep test, simulating fission gas loading, was designed and achieved by four different European teams. Lifetime and specific behavior of ODS steel tube are prospected. Based on a mechanical clamping achieving gas tightness, short length tubes samples are tested by different laboratories. In situ laser measurements exhibit the radial expansion of ODS steel tubes before failure. Post-mortem, geometrical characterizations are performed to determine hoop strains at failure. A consistent creep lifetime is observed by all the teams even with slightly different testing apparatus and clamping systems. Under inner gas pressure, ODS steels exhibit a typical failure by leakage associated to a very small radial expansion. This behavior results from a brutal failure (burst) without evidence of tertiary creep stage. This failure mode of ODS cladding in creep conditions is consistently observed on all samples of the study. Inner gas pressure creep tests were compared, for the first time, by four European laboratories on ODS steel tube. This technique, simulating the fission gas pressure loading, is applied on small and mechanically clamped samples. This technique shows a remarkable consistency between the different laboratories results and demonstrates to be efficient for ODS steel cladding tube qualification. The results show a correlation between the creep properties and the microstructure.

     

Photo-vulcanization using thiol-ene chemistry: Film formation,morphology and network characteristics of UV crosslinked rubber latices

The photo-vulcanization with versatile thiol-ene chemistry represents an innovative approach to crosslink diene-rubber materials both in latex and in solid film state. In this work, the structure of elastomer-based thiol-ene networks and the morphology after film formation are studied in detail using electron microscopic techniques, atomic force microscopy and multiple-quantum solid-state NMR spectroscopy. Additionally, film formation properties and corresponding macroscopic properties of photo-vulcanized natural rubber (NR) latex and its synthetic counterpart, isoprene rubber (IR) latex, are determined in dependence on the curing procedure (pre- and post-vulcanization). The results reveal that thiol-ene cured elastomers comprise homogenously distributed crosslinks with a low amount of short chain defects. Whilst photochemically pre-cured NR latex particles provide coherent films, the film formation and mechanical properties of IR are strongly governed by the crosslink density of the latex particles. In film state, photo-vulcanization promotes narrow crosslink distributions and excellent tensile properties of both NR and IR.     

Brassica Plant Responses to Mild Herbivore Stress Elicited by Two Specialist Insects from Different Feeding Guilds

Compensation growth and chemical defense are two components of plant defense strategy against herbivores. In this study, compensation growth and the response of primary and secondary metabolites were investigated in Brassica rapa plants subjected to infestation by two herbivores from contrasting feeding guilds, the phloem-feeding aphid Brevicoryne brassicae and the leaf-feeding caterpillar Pieris brassicae. These specialist herbivores were used at two different densities and allowed to feed for seven days on a young caged leaf. Changes in growth rates were assessed for total leaf area and bulb mass, whereas changes in primary and secondary metabolites were evaluated in young and mature leaves, roots, and bulbs. Mild stress by caterpillars on young plants enhanced mean bulb mass and elicited a contrasting regulation of aliphatic and indolic glucosinolates in the leaves. In contrast, mild stress by aphids enhanced leaf growth and increased glucosinolate concentrations in the bulb, the most important storage organ of B. rapa. A similar mild stress by either herbivore to older plants did not alter plant growth parameters or concentrations of the metabolites analyzed. In conclusion, Brassica plant growth was either maintained or enhanced under mild herbivore stress, and defense patterns differed strongly in response to herbivore type and plant development stage. These results have implications for the understanding of plasticity in plant defenses against herbivores and for the management of Brassica rapa in agroecosystems.     

Particle Size of Whole Meal Rye Bread does not Affect the Digestibility of Macro-Nutrients and Non-Starch Polysaccharides and the Energy Value of Dietary Fibre in Humans

The effect of particle size of whole meal rye bread on the apparent digestibility of macro-nutrients, non-starch polysaccharides (NSP) and energy, the energy value of rye NSP and on faecal weight was studied in balance experiments in seven young women. The whole meal breads were prepared from one single batch of rye milled to two different particle sizes (coarse bread: 50% of particles >2 mm, 90% >1 mm; fine bread: 86% of particles <0·5 mm, 58% <0·2 mm). Two diets containing either coarse (350 g day⁻¹) or fine (377 g day⁻¹) whole meal bread and a low fibre control diet were consumed for 3 weeks each in a 3×3 cross-over design. Relative to the low fibre control diet, digestibility of protein, NSP and energy was significantly lower for the diets containing the whole meal breads. Digestibility of fat was the same for all diets. Partial digestible energy value for each g of NSP from coarse and fine whole meal rye bread was calculated to be −3±7 and 1±5 kJ, respectively. There were no differences between coarse and fine whole meal rye bread in the effects on the parameters measured with the exception on faecal wet weight, which was higher for the coarse bread diet.     

Thin-film solar cells

The R&D status of cells and modules based on hydrogenated amorphous silicon (a-Si:H) and those based on CdTe and CuInSe₂ is reviewed. The stability of a-Si:H solar cells is still a major concern. Improvements have been achieved on an empirical basis by application of multijunction structures, optimization of interfaces, etc. Stabilized efficiencies of close to 10% have been reported. In parallel, the introduction of the ‘defect-pool model’ led to remarkable progress in understanding; it follows that a-SiGe:H instead of a-Si:H should be used for the i-layer (absorber). Improved cell engineering concepts, however, such as enhancement of the built-in electric field via reduction of the i-layer thickness and/or folded structures, are believed to be more promising. Polycrystalline thin-film cells based on CdTe and CuInSe₂ are not affected by inherent degradation mechanisms. the specific properties of these materials demand heterojunctions, and particular problems arise due to the polycrystallinity of the films and to the lattice mismatch and mismatch of the electronic band structures of the materials involved. These are discussed in conjunction with measures currently applied for optimizing solar cell performance. Both cell types exhibit eficiencies in the range 16-17%. Estimations of production costs and energy payback times of thin-film photovoltaic modules are reviewed (even below 1 US$ W_p⁻¹ and as low as 4 months, respectively) and environmental concerns, especially for Cd-containing cells, are summarized.     

Functional Characterization of the Solute Carrier LAT-1 (SLC7A5/SLC2A3) in Human Brain Capillary Endothelial Cells with Rapid UPLC-MS/MS Quantification of Intracellular Isotopically Labelled L-Leucine

The solute carrier L-type amino acid transporter 1 (LAT-1/SLC7A5) is a viable target for drug delivery to the central nervous system (CNS) and tumors due to its high abundance at the blood–brain barrier and in tumor tissue. LAT-1 is only localized on the cell surface as a heterodimer with CD98, which is not required for transporter function. To support future CNS drug-delivery development based on LAT-1 targeting, we established an ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) assay for stable isotopically labeled leucine ([¹³C₆, ¹⁵N]-L-leucine), with a dynamic range of 0.1–1000 ng/mL that can be applied for the functional testing of LAT-1 activity when combined with specific inhibitors and, consequently, the LAT-1 inhibition capacity of new compounds. The assay was established in a 96-well format, facilitating high-throughput experiments, and, hence, can support the screening for novel inhibitors. Applicable recommendations of the US Food and Drug Administration and European Medicines Agency for bioanalytical method validation were followed to validate the assay. The assay was applied to investigate the IC₅₀ of two well-known LAT-1 inhibitors on hCMEC/D3 cells: the highly specific LAT-1 inhibitor JPH203, which was also used to demonstrate LAT-1 specific uptake, and the general system L inhibitor BCH. In addition, the [¹³C₆, ¹⁵N]-L-leucine uptake was determined on two human brain capillary endothelial cell lines (NKIM-6 and hCMEC/D3), which were characterized for their expressional differences of LAT-1 at the protein and mRNA level and the surface amount of CD98. The IC₅₀ values of the inhibitors were in concordance with previously reported values. Furthermore, the [¹³C₆, ¹⁵N]-L-leucine uptake was significantly higher in hCMEC/D3 cells compared to NKIM-6 cells, which correlated with higher expression of LAT-1 and a higher surface amount of CD98. Therefore, the UPLC-MS/MS quantification of ([¹³C₆, ¹⁵N]-L-leucine is a feasible strategy for the functional characterization of LAT-1 activity in cells or tissue.     

Sensorische Analyse, Malat- und Saccharosegehalt und Fruchtfleischfestigkeit verschiedener Apfelsorten

Zusammenfassung Neben einer ausführlichen sensorischen Beurteilung der Frühsorte Jamba, der mittelspäten Sorten Holsteiner Cox und Roter Holsteiner Cox sowie der späten Sorte Gloster wurden parallel dazu der Malat- und Saccharosegehalt und die Fruchtfleischfestigkeit bestimmt. Die Korrelation dieser chemisch-physikalischen Parameter mit der Bewertung des Geschmacks und der Fruchtfleischstruktur sollte die Frage klären, ob eine Qualitätsaussage unter Umgehung der sensorischen Beurteilung möglich ist. Durch Vergleich ergab sich, daß für alle untersuchten Sorten der Malat- und/oder Saccharosegehalt wenig über die geschmacklichen Qualität der Früchte aussagt. Engere Beziehungen traten zwischen den Parametern sensorische Fruchtfleischbewertung und Festigkeit auf, wo bei einem Festigkeitswert von 5–5,3 kp/cm² und mehr das entsprechende senorische Urteil nicht schlechter als mittelmäßig ausfiel.

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Sensory evaluation, content of malate and sucrose, and fruit firmness of different apple varieties

Summary Parallel to a detailed sensory evaluation of the apple varieties Jamba, Holsteiner Cox, Red Holsteiner Cox and Gloster the content of malate and sucrose and fruit flesh firmness were measured. Comparisons between chemical and physical parameters and the sensory evaluation of taste and fruit flesh structure were performed to see, if apple quality can be determined without sensory assessment. The results for all samples show that content of malate and sucrose means little in relation to fruit taste. Recommendations for an optimum storage period could not be made. There was a closer relationship between sensory fruit flesh assessment and flesh firmness with a firmness of 5–5,3 kp/cm² or higher sensory evaluation was not worse than fair.

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Teil der Dissertation Mast, Kiel 1982     

Potent,Metabolically Stable 2‐Alkyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐adenines as Adenosine A2A Receptor Ligands

Inhibition of adenosine A_2A receptors has been shown to elicit a therapeutic response in preclinical animal models of Parkinson’s disease (PD). We previously identified the triazolo‐9H‐purine, ST1535, as a potent A_2AR antagonist. Studies revealed that ST1535 is extensively hydroxylated at the ω‐1 position of the butyl side chain. Here, we describe the synthesis and evaluation of derivatives in which the ω‐1 position has been substituted (F, Me, OH) in order to block metabolism. The stability of the compounds was evaluated in human liver microsomes (HLM), and the affinity for A_2AR was determined. Two compounds, (2‐(3,3‐dimethylbutyl)‐9‐methyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐purin‐6‐amine ( 3 b ) and 4‐(6‐amino‐9‐methyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐purin‐2‐yl)‐2‐methylbutan‐2‐ol ( 3 c ), exhibited good affinity against A_2AR (K_i=0.4 nM and 2 nM , respectively) and high in vitro metabolic stability (89.5 % and 95.3 % recovery, respectively, after incubation with HLM for two hours).     

Probing molecular mobility during crosslinking process of commercial resins by NMR multiexponential relaxation data analysis

In this study, we present the experimental results for the crosslinking process of a commercial polyester resin based on measurements of the spin lattice relaxation time T₁ of protons, as function of the crosslinking time evolution. Multiexponential decomposition of the evolution of magnetization measured in inversion‐recovery experiments is performed. The population of “rigid” and “mobile” nuclear spin sites was estimated as function of time evolution. In analogy to the usual monomer conversion u, site conversion from “mobile” to “rigid” sites u_M were also estimated as a function of time evolution and initial concentrations of the reagents. The multiexponential decomposition approach of T₁ relaxation data allows one to follow crosslinking processes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011