Induction of Phenolic Glycosides by Quaking Aspen (<Emphasis Type="Italic">Populus tremuloides)</Emphasis> Leaves in Relation to Extrafloral Nectaries and Epidermal Leaf Mining

We studied the effect of epidermal leaf mining on the leaf chemistry of quaking aspen, Populus tremuloides, during an outbreak of the aspen leaf miner, Phyllocnistis populiella, in the boreal forest of interior Alaska. Phyllocnistis populiella feeds on the epidermal cells of P. tremuloides leaves. Eleven days after the onset of leaf mining, concentrations of the phenolic glycosides tremulacin and salicortin were significantly higher in aspen leaves that had received natural levels of leaf mining than in leaves sprayed with insecticide to reduce mining damage. In a second experiment, we examined the time course of induction in more detail. The levels of foliar phenolic glycosides in naturally mined ramets increased relative to the levels in insecticide-treated ramets on the ninth day following the onset of leaf mining. Induction occurred while some leaf miner larvae were still feeding and when leaves had sustained mining over 5% of the leaf surface. Leaves with extrafloral nectaries (EFNs) had significantly higher constitutive and induced levels of phenolic glycosides than leaves lacking EFNs, but there was no difference in the ability of leaves with and without EFNs to induce phenolic glycosides in response to mining. Previous work showed that the extent of leaf mining damage was negatively related to the total foliar phenolic glycoside concentration, suggesting that phenolic glycosides deter or reduce mining damage. The results presented here demonstrate that induction of phenolic glycosides can be triggered by relatively small amounts of mining damage confined to the epidermal tissue, and that these changes in leaf chemistry occur while a subset of leaf miners are still feeding within the leaf.     

Whodunnit – Searching for the most important feature types signalling emotion-related user states in speech

In this article, we describe and interpret a set of acoustic and linguistic features that characterise emotional/emotion-related user states – confined to the one database processed: four classes in a German corpus of children interacting with a pet robot. To this end, we collected a very large feature vector consisting of more than 4000 features extracted at different sites. We performed extensive feature selection (Sequential Forward Floating Search) for seven acoustic and four linguistic types of features, ending up in a small number of ‘most important’ features which we try to interpret by discussing the impact of different feature and extraction types. We establish different measures of impact and discuss the mutual influence of acoustics and linguistics.     

Prebiotic fibre‐incorporated whey protein crisps processed by supercritical fluid extrusion

Prebiotic soluble fibre (fructooligosaccharides)‐incorporated whey protein crisps were produced by low‐shear supercritical fluid extrusion (SCFX), which utilises supercritical CO₂ as an expansion agent instead of steam. Protein crisps with desirable qualities were obtained with a formulation containing 8% prebiotic fibre and 60% whey protein concentrate (WPC‐80), which gave the final product with a protein content of 49.6% (w/w). A maximum of 70% WPC‐80 and 8% prebiotic fibre could be incorporated to produce expanded protein crisps; however, increasing WPC‐80 from 50% to 70% decreased the end‐product expansion ratio from 3.1 to 1.2 and increased the product hardness and piece density from 1.3 to 2.8 kN and 0.63 to 0.75 g mL^?1, respectively. Addition of 8% prebiotic fibre did not affect the textural qualities of final products. The process produced an expanded protein matrix with unique internal microstructure of uniformly distributed closed cells. Amino acid analysis indicated that 90% of the total lysine and 92% of the total essential amino acids were retained after SCFX processing and oven‐drying, indicating the preservation of protein nutritional quality during the process.     

On the temperature and voltage dependence of short-term negative bias temperature stress

Initial NBTI degradation is often explained by elastic hole trapping which also considerably distorts long-term measurements. In order to clarify this issue, short-term NBT stress measurements are performed using different temperatures, stress voltages, and oxide thicknesses. The data shows a clear temperature activation and a super-linear voltage dependence, thereby effectively ruling out elastic hole tunneling. Rather, our data supports an explanation based on a thermally activated hole capture mechanism.     

The effective hydrodynamic radius of single DNA-grafted colloids as measured by fast Brownian motion analysis

Optical tweezers accomplished with fast position detection enable one to carry out Brownian motion analysis of single DNA-grafted (grafting density: ∼1000 molecules per particle, molecular weight: 4000 bp) colloids in media of varying NaCl concentration. By that the effective hydrodynamic radius of the colloid under study is determined and found to be strongly dependent on the conformation of the grafted DNA chains. Our results compare well both with recent measurements of the pair interaction potential between DNA-grafted colloids (Kegler et al. Phys Rev Lett 2008; 100:118302) and with microfluidic studies (Gutsche et al. Microfluid Nanofluid 2006; 2:381-386). The observed scaling of the brush height with the ion concentration is in full accord with the theoretical predictions by Pincus, Zhulina, Birshtein and Borisov.     

Complexing agent assisted synthesis of high aspect ratio Fe3 +/Mg2 + layered double hydroxides

A new, facile synthesis for Fe^3 +/Mg^2 + LDHs is developed and investigated. The crucial feature of the synthesis is the usage of a complexing agent (diethylenetriamine, DETA) to increase the solubility of iron phases precipitated intermediately. The influences of different synthesis parameter like DETA concentration, pH value, and temperature are investigated. The optimized synthesis route yields high aspect ratio Fe^3 +/Mg^2 + LDHs which are expected to be interesting filler materials for flame retardant nanocomposites.     

Mixed crystalline films of co-evaporated hydrogen- and fluorine-terminated phthalocyanines and their application in photovoltaic devices

Blends of organic electron and hole conductive materials are widely used for ambipolar charge carrier transport and photovoltaic cells. An obvious choice for donor–acceptor blends are organic semiconducting materials in their hydrogenated and fluorinated form, since they combine potentially suitable electronic properties with structural compatibility of the two constituents. This study focuses on the structural, optical, and electrical properties of blends using hydrogenated copper-phthalocyanine (H₁₆CuPc) in combination with its per-fluorinated version (F₁₆CuPc). Using X-ray scattering, scanning force microscopy and optical absorption measurements we show that mixed crystalline films are obtained by co-evaporation of the two materials. Electrical transport measurements reveal a profound reduction of the current for bipolar charge injection in mixed films. We discuss the formation of self-trapped charge transfer excitons as possible explanation for this unexpected behaviour, which impedes the usability of this system in photovoltaic cells.     

A simulation model for reliability evaluation of space stationpower systems

The dependence of reliability and storage characteristics during Sun and eclipse periods is considered. The charging and discharging of energy storage modules is included on a continuous basis. Sample system studies are also presented. The Monte Carlo analysis program for reliability analysis of a hybrid configuration can model the charging and discharging of energy storage devices in a more realistic manner than the approach of C. Singh et al. (1987). The results shown do not indicate any significant effect on computed reliability indices by this more refined modelling of charge/discharge of energy storage