Mega-Trends in der Telekommunikation

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Single Gaussian distribution of barrier height in Al/PS–ZnPc/p-Si type Schottky barrier diode in temperature range of 120–320 K

Possible current-transport mechanism in aluminum/polystrene–zincphthalocyanine/ptype silicon Schotky barrier diode (Al/PS–ZnPc/p-Si; SBD), for the forward bias current–voltage (I–V) characteristics were carried out in the temperature range of 120–320 K. The high value of ideality factor (n), especially at low temperatures, was attributed to the existence of PS layer, barrier in-homogeneities and particular density distribution of surface states between metal and semiconductor. An abnormal decrease in the zero-bias barrier height (BH) and increase in n with decreasing temperature which leads to non-linearity in the Richardson plot, have been observed. Linear relationship between BH and n was also observed. BH was plotted as a function of q/2kT to obtain evidence of Gaussian distribution (GD) of the BHs. The mean BH and its standard deviation (σ) were obtained as 1.03 eV and 0.117 V from the slope and intercept of this plot, respectively. Thus, the modified ln(Io/T²) ? q²σo²/2k²T² versus q/kT plot gives mean BH and the modified Richardson constant \({\text{A}}_{\bmod }^{*}\) as 1.043 eV and 29.824 A cm^?2 K^?2, respectively. This value of the Richardson constant is very close to the theoretical value of 32 A cm^?2 K^?2 for p-type Si. Therefore, non-ideal behavior of forward-bias I–V characteristics in Al/PS–ZnPc/p-Si might be successfully explained in terms of the thermionic emission mechanism with single GD of BHs.     

Interactions of Meibum and Tears with Mucomimetic Polymers: A Hint towards the Interplay between the Layers of the Tear Film

Recent clinical findings suggest that mucomimetic polymers (MMP) can alter not only the texture of the aqueous tear but also the spreading and structure of the tear film (TF) lipid layer, thereby allowing for their synchronized performance in vivo. Thus, we aimed to evaluate in vitro (i) the capability of pharmaceutically applicable MMP to ensure the formation of post-evaporative ferning patterns (a characteristic feature of the “healthy” tear colloid) and (ii) the MMP interactions with human meibum films accessed in the course of blink-like deformations via Langmuir surface balance and Brewster angle microscopy (BAM). Four MMP were used- hyaluronic acid (HA), cross-linked hyaluronic acid (CHA), carboxymethyl cellulose (CMC) and gellan gum (GG)- at the concentrations of 0.0001%, 0.001%, 0.01%, 0.05% and 0.1%. Significant differences were observed in the MMP fern formation capability: CHA (≥0.001%) > HA (≥0.01%) = CMC (≥0.01%) > GG (≥0.05%). All MMP affected the spreading of meibum, with BAM micrographs revealing thickening of the films. CHA was particularly efficient, showing concentration-dependent enhancement of tear ferning and of meibomian layer structure, surfactant properties and viscoelasticity. Thus, endogenous and exogenous MMP may play key roles for the concerted action of the TF layers at the ocular surface, revealing novel routes for TF-oriented therapeutic applications.     

Social isolates and urbanites in perceptual isolation.

10 young men reared on isolated farms and 10 matched urban controls underwent a 5-hr perceptual isolation experiment. In terms of a previously formulated behavioral system, it was hypothesized that the isolates would suffer fewer and less intense functional disturbances than the controls, as the isolates already were accustomed to long periods of unstructured time with minimally varied social and perceptual stimulation. On the 4 sensory-perceptual measures, 3 of the 4 cognitive-affective measures, and the restless movement measures, findings were as hypothesized. The isolates and controls also differed in their mode of adaptation to the experiment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of the concentration of hydrochloric acid and acetic acid aqueous solution for fast hydrogen production from methanol solution of NaBH4

The semi-methanolysis reactions with hydrochloric acid and acetic acid were used for the hydrogen production from sodium borohydride (NaBH₄). The effects of the NaBH₄ concentration, hydrochloric acid and, acetic acid concentration, and temperature on the reactions were investigated. The maximum hydrogen production rates in the semi-methanolysis with 1 M hydrochloric acid and acetic acid were 4875 and 3960 ml min^?1, respectively. At the same time, the semi-methanolysis reactions with the acids are completed within 4 and 5 s, respectively. The power law kinetic model is performed for kinetic studies. Activation energies for the semi-methanolysis reactions of NaBH₄ in the presence of hydrochloric acid and acetic acid were found as 5.84 and 2.81 kJ mol^?1, respectively.     

Migration of antifog additives in agricultural films of low‐density polyethylene and ethylene‐vinyl acetate copolymers

In this work, polymer films of low density polyethylene and ethylene‐vinyl acetate copolymers containing two types of antifog additives (nonionic surfactants) were exposed to two simulated horticultural greenhouse environments, reproducing hot and cold climate conditions. The evolution of the antifog effect was visually observed and that of the additive concentration measured using Fourier transform infrared spectroscopy (FTIR). All the films studied showed good antifog properties, but in all cases, the duration of the antifog effect was longer in the hot‐climate test. From the FTIR, we can conclude that the additives studied showed a low migration rate and, therefore, when the antifog effect is lost, important quantities of the additive remain in the bulk. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Real-time mapping of moisture migration in cereal based food systems with Aw contrast by means of MRI

The redistribution of water in prototype food systems, comprising phases with contrasting water activity (A_w), was investigated. To accomplish this task, MRI techniques adapted to migration rate were used. RARE and SPI measuring methods were used to monitor water redistribution in crunchy inclusions in water and biscuit shells with apple filling during storage, respectively. In the first case, fast migration, which typically last some tens of minutes, was monitored with a temporal resolution 3.5 min or better, while in the second case of slow migration it was monitored during 2 months with 10 days temporal resolution. 3D MR images with sub-millimeter resolution visualise the spatial redistribution of moisture and allow a quantification of its rate and extent of matrix swelling. Correlation with high resolution X-ray (XRT) images allows to identify structural elements responsible for unwanted fast hydration.     

The impact of metal transport processes on bioavailability of free and complex metal ions in methanogenic granular sludge

Bioavailability of metals in anaerobic granular sludge has been extensively studied, because it can have a major effect on metal limitation and metal toxicity to microorganisms present in the sludge. Bioavailability of metals can be manipulated by bonding to complexing molecules such as ethylenediaminetetraacetate (EDTA) or diethylenetriaminepentaacetate (DTPA). It has been shown that although the stimulating effect of the complexed metal species (e.g. [CoEDTA](2-)) is very fast, it is not sustainable when applied to metal-limited continuously operated reactors. The present paper describes transport phenomena taking place inside single methanogenic granules when the granules are exposed to various metal species. This was done using magnetic resonance imaging (MRI). The MRI results were subsequently related to technological observations such as changes in methanogenic activity upon cobalt injection into cobalt-limited up-flow anaerobic sludge blanket (UASB) reactors. It was shown that transport of complexed metal species is fast (minutes to tens of minutes) and complexed metal can therefore quickly reach the entire volume of the granule. Free metal species tend to interact with the granular matrix resulting in slower transport (tens of minutes to hours) but higher final metal concentrations.     

The structural and hydration properties of heat-treated rice studied at multiple length scales

The impact of heat-treatment on structure and hydration properties of rice was studied at different length scales (μm–nm). Heat-treatment introduced micro- and macro-pores within rice kernels (μCT) and, within intact cell walls, disintegrated starch granules were observed (SEM, CSLM). In native kernels starch predominantly occurred as crystalline A-type starch and, upon heat treatment, amorphous and V-type starch appeared (XRD, ¹³C CP MAS NMR). Plasticization of amorphous starch by water was more pronounced for heat-treated than for native kernels (¹³C SPE MAS NMR). Within native kernels, more effective spin diffusion between water and starch chains was present (WISE-Exchange), confirming the inter-helical nanoscale order of amylose helices. Upon heat-treatment, this inter-helical nanoscale order was lost, as well as microscale granular compartmentalisation (TD NMR). These findings explain why, upon heat-treatment, vapour sorption is lower and starch is more prone to gelatinization (DSC).