Sensitivity of Cylindrotheca closterium to copper: Influence of three test endpoints and two test methods

The present study checked the suitability of Cylindrotheca closterium (Bacillariophyceae) as a test species for ecotoxicology studies. To date, only limited use has been made of microphytobenthos in ecotoxicology, and C. closterium has been employed as a target organism in this study because the biological group is considered to be very relevant ecologically. The main objective was to assess the response of C. closterium to a contaminant-type (copper) using three different test endpoints (esterase activity, chlorophyll fluorescence and population growth) and two different test methods (Erlenmeyer flasks and microplates), to evaluate which combination of test conditions would provide the most sensitive approach for assessment of effects. Regardless of the endpoints, the response of C. closterium to copper was very similar; however lower sensitivity (EC₅₀ of 27.8 ± 0.7 µg Cu L^− 1) was observed when tests were carried out in microplates. Chlorophyll fluorescence measured by flow cytometry as total FL3 was slightly more sensitive (EC₅₀ of 4.7 ± 0.1 µg Cu L^− 1) than the other parameters measured, probably because it takes into account the effect on chlorophyll fluorescence and cell density simultaneously. The test method (Erlenmeyer flask or microplate) was the determining factor for the observed differences in sensitivity. These differences found for the two methods are explained by the higher metal adsorption capacity of microplate vessel walls (more than 40%), which decreases the available copper. C. closterium was demonstrated to be a suitable organism for adoption in ecotoxicological studies, given the reliability of the three endpoints and also of the two test methods evaluated here.     

Influence of the Germanium content on the amorphization of silicon–germanium alloys during ion implantation

We have studied by transmission electron microscopy the amorphization of silicon–germanium (SiGe) alloys by Ge⁺ implantation. We show that when implanted with the same amorphization dose, the resulting amorphous layers get narrower when the Ge content increases. The experimental results can be simulated using the critical damage energy density model assuming that the amorphization threshold rises linearly with the Ge content from 3 eV/at for pure Si to 5 eV/at for pure Ge. These results and simulations are needed to optimize the fabrication of highly doped regions in SiGe alloys.     

Nature and mechanisms of loss of motivation.

Loss of motivation refers either to the weakening of a motive q or to the loss of energy and persistence with which some subordinate goal p is planned for and pursued in view of q. Although interrelated, such aspects can be kept distinct, and the present work focuses on the loss of strength of the subordinate goal. An analysis is provided of such mental attitudes as subjective frustration, negative expectation, disappointment, and discouragement so as to clarify their respective roles in favoring loss of motivation. The necessary cognitive conditions for the occurrence of loss of motivation are singled out; namely, goal p should be an intention, and a disappointment should occur in regard to the instrumental relationship between p and q , p's attainability, or p's convenience. Both advantages and limits of the model are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Morphology and electrochemical activity of SOFC composite cathodes: I. experimental analysis

This paper describes the first part of an experimental and theoretical study performed on composite Lanthanum Strontium Manganite (LSM) and Yttria-stabilized Zirconia (YSZ) electrodes. Cathode electrocatalytic activity was investigated using different cell configurations and carrying out potentiodynamic polarisation and electrochemical impedance spectroscopy measurements (EIS). Measurements were carried out at different oxygen partial pressures, overpotentials, temperatures and electrode geometries. In order to identify the main steps involved in cathodic oxygen reduction, the NLLS-Fit procedure was used. The results for different cell geometries agree with each other, suggesting a transition in the overall reaction mechanism, from charge transfer to mass transfer control, at a critical temperature of about 750 °C. The experimental results also show a remarkable effect of electrode thickness on the overall reaction rate, throughout the temperature range tested. A grey level gradient along the thickness of the thicker electrodes were detected by analyzing microscopic images of the cells. These results, together with electrochemical measurements on cathodes with different thickness, confirm that morphology plays a key role in determining the performance of Solid Oxide Fuel Cells (SOFC) composite cathodes.     

Ultrahigh-sensitivity temperature fiber sensor based on multimode interference

The proposed sensing device relies on the self-imaging effect that occurs in a pure silica multimode fiber (coreless MMF) section of a single-mode-multimode-single-mode (SMS)-based fiber structure. The influence of the coreless-MMF diameter on the external refractive index (RI) variation permitted the sensing head with the lowest MMF diameter (i.e., 55 μm) to exhibit the maximum sensitivity (2800 nm/RIU). This approach also implied an ultrahigh sensitivity of this fiber device to temperature variations in the liquid RI of 1.43: a maximum sensitivity of -1880 pm/°C was indeed attained. Therefore, the results produced were over 100-fold those of the typical value of approximately 13 pm/°C achieved in air using a similar device. Numerical analysis of an evanescent wave absorption sensor was performed, in order to extend the range of liquids with a detectable RI to above 1.43. The suggested model is an SMS fiber device where a polymer coating, with an RI as low as 1.3, is deposited over the coreless MMF; numerical results are presented pertaining to several polymer thicknesses in terms of external RI variation.     

Effect of processing and cooking on phenolic acid profile and antioxidant capacity of durum wheat pasta enriched with debranning fractions of wheat

The effect of processing and cooking on phenolic acids profile and antioxidant properties of durum wheat (Triticum turgidum L. var. durum) pasta samples enriched with debranning fractions of an Italian wheat (Triticum aestivum L.) cultivar were studied.     

Performance evaluation of 3D video streaming services in LTE-Advanced networks

Due to the ever growing interest of 3-dimensional (3D) technology, together with the the widespread use of new generation smartphones, netbooks, and tablets, the idea to provide 3D multimedia services also to mobile users is attracting the attention of researchers worldwide. The emerging long term evolution-advanced (LTE-A) technology seems to have all the potential to offer such kind of services but no accurate studies have been yet conducted to demonstrate this assumption. To bridge this gap, we investigate herein how the LTE-A network configuration, the traffic load, and 3D video settings may influence to the quality of all services of all active flows. We consider a heterogeneous LTE-A network composed by macro and pico cells and a number of users uniformly distributed into the scenario, that receive at the same time 3D video streams, voice flows and best-effort applications. Moreover, several objective metrics, such as the ratio of lost packets, the peak signal to noise ratio, the Structural SIMilarity, the application goodput, and packet delays, have been evaluated to show the LTE-A effectiveness in delivering 3D videos in a realistic last generation mobile environment.