Optimized birefringence changes during isolated nerve activation

Single trial, birefringence signals associated with action potentials from isolated lobster nerves were optimized with high-intensity light-emitting diodes (LEDs) and glass polarizers. The narrow spectral output of the LEDs allowed us to select specific wavelengths, increasing the effectiveness of the polarizers and minimizing the stray light in the system. The LEDs produced intensity profiles equivalent to narrowband filtered 100-W halogen light, and birefringence signals were comparable or superior in size and clarity to halogen lamp recordings. The results support a direct correlation between signal size and polarizer extinction coefficient. Increasing the sensitivity of birefringence detection through the use of LED light sources could ameliorate noninvasive brain imaging techniques that employ fast optical consequences associated with action potential propagation.     

Do Multiple Representations Need Explanations? The Role of Verbal Guidance and Individual Differences in Multimedia Mathematics Learning.

Elementary school children, some of whom were nonnative speakers of English, learned to add and subtract integers in a discovery-based multimedia game either with or without verbal guidance in English or optionally in Spanish (Groups G--verbal guidance and No-G--no verbal guidance, respectively). Group G members chose to listen to verbal explanations in their first language and showed larger posttest scores than Group No-G. High-computer-experience students in Group G outperformed the rest of the students on training session scores and a transfer test. Longer latencies to respond to practice problems affected all learning measures positively. Results support the use of verbal guidance for discovery-based multimedia games and show that multimedia games may not be equally effective for all learners. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Molecular quantum similarity and the fundamentals of QSAR

A general overview on quantum similarity and applications to QSAR is presented. The concepts regarding quantum similarity from its theoretical foundation and consecutive development, involving mathematical formulation and similarity measures, are presented and complemented with application examples. The practical part, based on the well-known Crammer 31 steroids set, covers approximate quantum similarity calculations, molecular superposition, and statistics. In this way, the reader will find both basic general information and applicability of quantum similarity.     

Observed maternal strategies and children's health locus of control in low-income Mexican Americans.

This study examined the relationship among mothers' health locus of control (HLOC) beliefs, their socialization strategies, and their children's HLOC beliefs in 80 low-income Mexican American families. Maternal socialization strategies were assessed from videotaped interactions of mothers and children engaged in a structured task. Factor analysis of the coded strategies yielded 4 factors: Tell Answer, Teaching, Clarify, and Reinforce. Findings indicated that maternal-health-internally scores negatively predicted mothers' use of the Tell Answer strategies and positively predicted their use of Teaching strategies. Mothers who believed that Powerful Others (e.g., health professionals) controlled their health were more likely to use the Tell Answer strategy. In contrast, mothers who believed that health was due to chance were less likely to use Teaching. Maternal use of Teaching strategies predicted children's internal HLOC, whereas maternal Tell Answer strategies predicted children's external HLOC. Findings suggest that mothers' HLOC beliefs influence the socialization strategies they use and that these strategies are associated with children's HLOC beliefs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Compositional studies on Transylvanian gold nuggets: Advantages and limitations of PIXE-PIGE analysis

Minute fragments from nine gold nuggets from Transylvania - two belonging to placer deposits and seven to primary deposits - were analyzed by PIXE and PIGE at the AGLAE tandem accelerator of the Centre de Recherche et de Restauration des Musées de France (C2RMF) with a 3 MeV proton beam extracted into air. This study was triggered by some archaeological provenance issues for which the elemental characterization of the Transylvanian gold source, exploited from the Antiquity, was required. All analyzed Transylvanian gold nuggets are characterized by a consistently high amount of Ag (18% on average). Au and Ag add up to roughly 99%, the other elements - Cu, Fe, Te, Pb - being detected only at a trace level. The obtained results are in good agreement with the previous analyses of Transylvanian gold.     

Impact of whey protein addition on wheat bread fermented with a spontaneous sourdough

Wheat bread is consumed in large quantities throughout the world. However, it contains an inadequate amount of proteins. This fact can be improved by adding whey protein concentrate (WPC). Sourdough (S) fermentation generally improves some characteristics and the digestibility of bread. The aim of this paper was to determinate the physicochemical properties and in vitro protein digestibility of bread with 20% of WPC leavened with spontaneous S (WPC 20-S). To complete the experimental design, bread with S without WPC (WPC 0-S) and bread with yeast (Y) without and with WPC 20% (WPC 0-Y and WPC 20-Y, respectively) were produced. WPC 20-S bread had higher pH, lower moisture and higher hardness and chewiness, compared with WPC 0-S. Interestingly, WPC had a negative effect only on the specific volume of bread fermented with Y but not when S was used. For all formulations, WPC improved the protein content and in vitro protein digestibility.     

Esterolytic and lipolytic activities of lactic acid bacteria isolated from ewe's milk and cheese

In the present work, we report on the esterase and lipase activities of lactic acid bacteria representing the genera Lactococcus, Leuconostoc, Lactobacillus, and Enterococcus isolated from ewe's milk and cheeses. Esterase activity was studied using alpha- and beta-naphthyl derivatives of 2 to 12 carbon atoms and postelectrophoretic detection. The lactic acid bacteria evaluated had intracellular esterase activities, which preferentially degraded the alpha- and beta-naphthyl derivatives of 2 to 6 carbon atoms. By studying postelectrophoretic patterns, it was found that some strains presented more than one esterase. Lactobacillus plantarum O236 showed four enzymes that hydrolyze carboxyl ester linkages with different specificity. Lipase activity was studied in intracellular and extracellular fractions using tributyrin, tricaprylin, triolein, and milk fat as substrates. The intracellular and extracellular fractions of Leuconostoc mesenteroides O257, Lactobacillus plantarum O236, and Lactobacillus acidophilus O177 were able to hydrolyze tributyrin. L. plantarum O186, L. acidophilus O252, Enterococcus faecium O174 and O426, and Enterococcus faecalis Ov409 showed lipase activity associated with the intracellular fraction on tributyrin. Lactococcus lactis O233, L. plantarum O155, and Lactobacillus casei O190 did not hydrolyze triglycerides. Not all strains that showed esterase activity exhibited high activity on triglycerides. Esterase and lipase activities were species- and strain-specific. Wide variations in activity between strains highlight the need for selecting appropriate starters to produce enzyme-modified cheese as well as accelerated ripened cheese.     

Differentiation of Romanian Wines on Geographical Origin and Wine Variety by Elemental Composition and Phenolic Components

Several wines were analyzed by high-performance liquid chromatography (HPLC-PDA), inductively coupled plasma mass spectrometry (ICP-MS), and flame atomic absorption spectroscopy (FAAS) in order to associate the concentration levels of the chemical parameters with the geographical origin of wines and wine varieties. Thus, the concentrations of 22 elements (Li, Be, Co, Ni, Cs, U, Pb, V, As, Ba, Cr, Cu, Zn, Al, Mn, Rb, Sr, Fe, Ca, Mg, Na, and K) and seven phenolic compounds (gallic acid, (+)-catechin, (?)-epicatechin, p-coumaric acid, ferulic acid, trans-cinnamic acid, and resveratrol) were analyzed in 22 wines from two different wine-producing areas of Romania. Among the phenolic compounds, (+)-catechin, (?)-epicatechin, p-coumaric acid, ferulic acid, and resveratrol concentrations were the most useful markers for wine differentiation by geographical origin and wine variety, whereas Ba, Be, Cr, Cs, Li, Mg, Na, Ni, Sr, U, and Zn were the main inorganic parameters selected. To explore the distribution pattern of the samples, aimed at differentiating the wine samples by geographical region and wine variety, principal component analysis (PCA) was applied to the obtained data.     

Collagen/hydroxyapatite composite materials with desired ceramic properties

Our purpose was to obtain and characterize some collagen/hydroxyapatite (COLL/HA) hybrid composite materials with desired ceramic properties. The ceramic properties of these materials were achieved by combining two drying methods: controlled air drying at 30°C followed by freeze-drying. Through the function of the air drying times, the materials morphology varies from porous materials (when the materials are freeze-dried) up to dense materials (when the materials are air-dried), while the combined drying allows us to obtain an intermediary morphology. The composite materials intended to be used as bone grafts and in a drug delivery system were characterized by XRD, FTIR, SEM, and also by determining the ceramic properties by using the Arthur method. The ceramic properties of these COLL/HA composite materials vary in large range, for instance the density of the materials varies from 0.06 up to 1.5?g/cm(3) while the porosity varies from 96.5% down to 27.5%.     

Preparation and characterization of new hybrid nanostructured thin films for biosensors design

The present paper reports on an innovative route for the preparation of new hybrid nanostructured thin films based on hydroxyapatite and functionalized polyurethane. Hybrid nanopowders based on hydroxyapatite and functionalized polyurethane have been synthesized by a hydrothermal method with high pressure and low temperature conditions and further used for spin coating deposition. Biocompatible thin films with a thickness of about 50 nm have been deposited onto Si/SiO₂/Ti/Au substrates and their properties recommend them suitable as possible electrodes for the fabrication of impedance biosensors. Hybrid materials with improved properties are obtained, combining the mechanical properties of polyurethane with biocompatible properties of hydroxyapatite (bioactivity and osteoconductivity). The presence of functional groups in polyurethane structure ensures the existence of strong interactions between components and an increased affinity of the thin films for further protein bonding in biosensor design. Hybrid nanostructured thin films based on hydrothermally synthesized hydroxyapatite-polyurethane nanopowders could enhance the amount of immobilized biomolecules in the construction of an impedance biosensor for diagnosis and therapy of bone diseases.