Plastic Properties of a Mg-Al-Ca Alloy Reinforced with Short Saffil Fibers

AX41 magnesium alloy was reinforced with short Saffil fibers using squeeze cast technology. Samples of the composite were deformed in compression at elevated temperatures. The work hardening rate as a function of the flow stress in the matrix was investigated. A model taking into account two hardening and two softening processes was used for analyzing of experimental curves. Parameters of the model follow different temperature dependences. Possible hardening and softening processes are discussed.     

Light-harvesting bio-nanomaterial using porous silicon and photosynthetic reaction center

ABSTRACT: Porous silicon microcavity (PSiMc) structures were used to immobilize the photosynthetic reaction center (RC) purified from the purple bacterium Rhodobacter sphaeroides R-26. Two different binding methods were compared by specular reflectance measurements. Structural characterization of PSiMc was performed by scanning electron microscopy and atomic force microscopy. The activity of the immobilized RC was checked by measuring the visible absorption spectra of the externally added electron donor, mammalian cytochrome c. PSi/RC complex was found to oxidize the cytochrome c after every saturating Xe flash, indicating the accessibility of specific surface binding sites on the immobilized RC, for the external electron donor. This new type of bio-nanomaterial is considered as an excellent model for new generation applications of silicon-based electronics and biological redox systems.     

An electrically controlled quantum dot based spin current injector

We present a proposal for a fully electrically controllable quantum dot based spin current injector. The device consists of a quantum dot that is strongly coupled to a ferromagnetic electrode on one side and weakly coupled to a nonmagnetic electrode on the other side. The presence of the ferromagnetic electrode results in an exchange field that splits the dot level. We show that this exchange-induced splitting can lead to almost full spin polarization of the current flowing through the device. Moreover, we also demonstrate that the sign of polarization can be changed by the gate or the bias voltage within a switching time in the nanosecond range. Thus, the proposed device can operate as an electrically controlled, rapidly switchable spin current source, which can be realized in various state-of-the-art nanostructures.     

Methane production from citrus wastes: process development and cost estimation

BACKGROUND: Because of its extreme toxicity for microorganisms, the limonene content of citrus wastes (CWs) has been a major obstacle to the conversion of CWs to biofuels. The main objective of this study was to develop a new process for the utilization of CWs that can be economically feasible when the supply of CW is low. RESULTS: Steam explosion pre‐treatment was applied to improve the anaerobic digestibility of CWs, resulting in a decrease of initial limonene concentration by 94.3%. A methane potential of 0.537 ± 0.001 m³ kg^?1 VS (volatile solids) was obtained during the following batch digestion of treated CWs, corresponding to an increase of 426% compared with that of the untreated samples. Long‐term effects of the treatment were further investigated by a semi‐continuous co‐digestion process. A methane production of 0.555 ± 0.0159 m³ CH₄ kg^?1 VS day^?1 was achieved when treated CWs (corresponding to 30% of the VS load) were co‐digested with municipal solid waste. CONCLUSION: The process developed can easily be applied to an existing biogas plant. The equipment cost for this process is estimated to be one million USD when utilizing 10 000 tons CWs year^?1. 8.4 L limonene and 107.4 m³ methane can be produced per ton of fresh citrus wastes in this manner. Copyright © 2011 Society of Chemical Industry     

Investigations of Native and Resistant Starches and Their Mixtures Using Near-Infrared Spectroscopy

Resistant starches (RS) play important roles in our nutrition; therefore, the investigation of these starches is notably important. In our study, two native starches (maize and wheat) and two resistant starches (Hi-maize™260, high amylose maize starch as RS2 and Fibersym™70, phosphorylated wheat starch as RS4) were investigated as is and in their physical mixtures (samples containing 20%, 40%, 60% and 80% RS) using near-infrared (NIR) spectroscopy. The aim of our study was to examine the spectra of resistant starches and to differentiate the resistant starch components in different ratios by NIR spectroscopy. The differences of samples were presented in two characteristic absorption bands for carbohydrate: carbohydrate II (2,080–2,130 nm) and carbohydrate III (2,275–2,290 nm) regions. Additionally, principal component analysis (PCA) for all samples was carried out. It was shown that the increasing amount of amylose can be sensitively followed up in carbohydrate II region. The phosphorylated RS4 is not so characteristic probably due to the reduced mobility of amorphous chains; however, the RS4 addition can be observed. Additionally, it was proven that the carbohydrate III region is sensitive for the changes of amylose–amylopectin ratio as well. The wheat-based RS4 addition causes linear changes in maize-based mixtures; thus the botanical origin is determining in this region. The global PCA analysis justified that the RS2 addition can be sensitively followed up independent on the medium; however, the increasing amount of RS4 cannot be detected in the PCA plot. The loading spectra of PC1 component attribute great significance to the carbohydrate III region.     

Investigation of Phenolic Components of Hungarian Wines

Ninety-two wines from the southernmost wine-producing region in Hungary (Villány) were analyzed for their polyphenolic content by high performance liquid chromatography (HPLC). Our results show that wine variety or vintage year could not be distinguished based on polyphenol content, but winery origin could be. Resveratrol concentration is mainly dependent on variety and vintage year. The “human factor” (i.e., winemaking style and technology) seems to be more decisive for the polyphenolic composition of red wines than other factors, such as variety and vintage year.     

Inferring the outcome of an ongoing novel action at 13 months.

Many studies have demonstrated that infants can attribute goals to observed actions, whether they are presented live by familiar agents or on a computer screen by abstract figures. However, because most, if not all, of these studies rely on the repeated action presentations typical of infant studies, it is not clear whether infants are simply recognizing the completed action as goal directed, or whether they can productively infer a not-yet-achieved outcome from an ongoing action. We investigated this question by presenting 13-month-old infants with a single animated chasing event. Infants looked longer at the outcome of this action when, given the opportunity, the chaser did not catch the chasee than when it did. Crucially, this result was dependent on whether the action could be construed as efficient with regard to this goal state. This finding suggests the ability to infer the goal of an ongoing novel action and illustrates the productivity of 1-year-olds’ action understanding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Elastic peak electron spectroscopy

Elastic peak electron spectroscopy (EPES) determines the elastic peak intensity N (E_p) in absolute units (percentage). The experimental curve N (E_p) is affected by the type of electron spectrometer used (CMA, RFA, etc.) and represents the probability P_e (E, Z) of elastic electron reflection detected by the angular window of the spectrometer. P_e (E, Z) = N_Aσ_eff (E, Z) Δ is the product of the inelastic mean free path Δ, the density N_A of atoms and the effective elastic scattering cross-section σ_eff (E, Z). Elementary processes of elastic scattering are treated with a simplified model based on a single scattering process. A more refined analysis will be to use the Monte-Carlo approach. σ_eff is given by the differential elastic scattering cross-section determined by the atomic number Z, the energy E_p, and the input and scattering angles. Results of σ_eff (E, Z) are presented based on tabulated differential cross-section data published in the literature. Angular effects are discussed. A number of EPES applications are described for AES, plasmon-, ionization-, and low energy loss spectroscopies and SEM. EPES has been successful in the experimental determination of the inelastic mean free path Δ for a number of elements and compounds.